"Science, Faculty of"@en . "Botany, Department of"@en . "DSpace"@en . "UBCV"@en . "Beil, Charles Edward"@en . "2011-05-18T23:35:39Z"@en . "1969"@en . "Doctor of Philosophy - PhD"@en . "University of British Columbia"@en . "The objectives of this study were to obtain quantitative and qualitative data on the vegetation and environmental factors of the Cariboo Zone and to synthesize these data into an ecosystematic classification.\r\nSample plots were chosen selectively according to criteria based on uniformity and discreteness. Vegetation was studied using the phyto-sociological methods of the Z\u00FCrich-Montpellier School. On all plots data were also obtained for edaphic and physiographic factors.\r\nBased on floristic composition and environmental data the 131 plots were synthesized into a flexible ecosystematic classification in which eight orders, twelve alliances, twenty associations and six subassociations were described. The order Pseudotsugetalia menziesii with three associations dominated most of the forested areas, occurring on subhygric to subxeric habitats. The order Piceetalia glaucae with three associations occurred only marginally; always on subhygric to subhydric habitats. The order Koelerio -Agropyretalia spicati with eight associations dominated the grassland areas, occurring on fine textured soils of aeolian origin. The order Puccinellietalia airoidis with two associations dominated the saline-alkaline habitats. The orders Betuletalia glandulosae, Salicetalia, Scirpetalia validi, and Caricetalia rostratae were represented by single associations of restricted distributions.\r\nSoils representative of all six orders of the Canadian Soil Classification system were distinguished with Chernozemic and Brunizolic soils the most common. Melanization appeared to be the dominant soil-forming process and the soils were generally rich having high cation exchange capacities, high amounts of exchangeable cations and alkaline reactions.\r\nAn examination of the population structures of the major tree species showed that Pseudotsuga menziesii had the widest amplitude and formed the climax forest cover over much of the Cariboo Zone. Picea glauca had a narrower amplitude and Pinus contorta and Populus tremuloides reached dominance only as pioneer species. \r\nSelected ecosystem units were characterized microclimatically. The Agropyrion spicati occupied microclimatically warm areas while the floristically related Stipion columbianae was present in areas with a cool microclimate. The Antennario - Poetum secundae and Stipetum richardsonii, although bordering associations, occupied microclimately distinct habitats. Forest communities were shown to develop at higher elevations where a cool microclimate prevails. \r\nBased on species significance data, plots were objectively grouped by the weighted-pair-group and the weighted-variable-group methods of cluster analysis. The resulting hierarchical arrangements of plots paralleled very closely the subjectively derived ecosystematic classification. On the dendrogram obtained by the weighted-variable-group method, associations were distinguished and their degree of homogeniety and ecological relationships were demonstrated. \r\nThe forest-grassland boundary in the Cariboo Zone was assessed to be relatively stable and to be controlled by available soil moisture as related to soil texture. It was apparent though, that minor fluctuations in the boundary as a result of grazing and fire occur. \r\nDetailed topographic relationships of the associations were demonstrated and it was apparent that topography, which represents a complex of physiographic factors, is important in controlling the distribution of associations. \r\nSuccessional changes appeared to be operating at a slow rate and \r\nthus most of the associations described were in a stable condition. The Agropyretum spicati most closely approximated the climatic climax association, occurring on ridges and slopes. Other stable associations were rated as edaphic or topographic climaxes. The successional relationships of the associations were demonstrated within a monoclimax concept in which it was assumed that ultimately all associations would change into the climax as a result of soil weathering and peneplanation of the land. \r\nIt was concluded that the gynecological approach and classification methods used allowed the presentation of data in an ecosystematic format which could be directly applied to range or forest management but could also serve as a basis for more detailed scientific studies."@en . "https://circle.library.ubc.ca/rest/handle/2429/34693?expand=metadata"@en . "THE PLANT ASSOCIATIONS OF THE CARIBOO - ASPEN LODGEPOLE PINE - DOUGLAS-FIR PARKLAND ZONE - by CHARLES EDWARD BEIL B.Sc, University of Alberta, 1963 M.'Sc, University of Alberta, 1966 A THESIS SUBMITTED IN PARTIAL FULFILMENT OF THE REQUIREMENTS FOR THE DEGREE OF DOCTOR OF PHILOSOPHY in the Department of ' '\u00E2\u0080\u00A2' Botany We accept this thesis as conforming to the required standard THE UNIVERSITY OF BRITISH COLUMBIA December, 1969 In p r e s e n t i n g t h i s t h e s i s in p a r t i a l f u l f i l m e n t o f the r e q u i r e m e n t s f o r an advanced d e g r e e a t the U n i v e r s i t y o f B r i t i s h C o l u m b i a , I a g r e e t h a t the L i b r a r y s h a l l make i t f r e e l y a v a i l a b l e f o r r e f e r e n c e and S t u d y . I f u r t h e r a g r e e t h a t p e r m i s s i o n f o r e x t e n s i v e c o p y i n g o f t h i s t h e s i s f o r s c h o l a r l y p u r p o s e s may be g r a n t e d by the Head o f my Department or by h i s r e p r e s e n t a t i v e s . It i s u n d e r s t o o d t h a t c o p y i n g o r p u b l i c a t i o n o f t h i s thes . is f o r f i n a n c i a l g a i n s h a l l not be a l l o w e d w i t h o u t my w r i t t e n p e r m i s s i o n . Department o f B O T A N Y The U n i v e r s i t y o f B r i t i s h Co lumbia V a n c o u v e r 8, Canada Date December i s 1 9 6 9 ABSTRACT The o b j e c t i v e s of t h i s study were to obtain q u a n t i t a t i v e and q u a l i t a t i v e data on the vegetation and environmental factors of the Cariboo Zone and to synthesize these data i n t o an ecosystematic c l a s s i f i c a t i o n . Sample p l o t s were chosen s e l e c t i v e l y according to c r i t e r i a based on uniformity and discreteness. Vegetation was studied using the phyto-s o c i o l o g i c a l methods of the Ziirich-Montpellier School. On a l l p l o t s data were also obtained f o r edaphic and physiographic f a c t o r s . Based on f l o r i s t i c composition and environmental data the 131 p l o t s were synthesized i n t o a f l e x i b l e ecosystematic c l a s s i f i c a t i o n i n which eight orders, twelve a l l i a n c e s , twenty associations and s i x subassociations were described. The order Pseudotsugetalia menziesii with three associations dominated most of the forested areas, occurring on subhygric to subxeric h a b i t a t s . The order P i c e e t a l i a glaucae with three associations occurred only marginally; always on subhygric to subhydric h a b i t a t s . The order Koelerio -Agropyretalia s p i c a t i with eight associations dominated the grassland areas, occurring on f i n e textured s o i l s of aeolian o r i g i n . The order P u c c i n e l l i e t a l i a a i r o i d i s with two associations dominated the s a l i n e - a l k a l i n e h a b i t a t s . The orders B e t u l e t a l i a glandulosae, S a l i c e t a l i a , S c i r p e t a l i a v a l i d i , and C a r i c e t a l i a rostratae were represented by s i n g l e associations of r e s t r i c t e d d i s t r i b u t i o n s . S o i l s representative of a l l s i x orders of the Canadian S o i l C l a s s i f i c a t i o n system were d i s t i n g u i s h e d with Chernozemic and B r u n i z o l i c s o i l s the most common. Melanization appeared to be the dominant soi l - f o r m i n g process and the s o i l s were generally r i c h having high cation exchange c a p a c i t i e s , high amounts of exchangeable cations and a l k a l i n e r e a c t i o n s . An examination of the population structures of the major tree species showed that Pseudotsuga menziesii had the widest amplitude and formed the climax forest cover over much of the Cariboo Zone. Picea glauca had a narrower amplitude and Pinus contorta and Populus tremuloides reached dominance only as pioneer species. Selected ecosystem units were characterized microclimatically. The Agropyrion spicati occupied microclimatically warm areas while the f l o r i s t i c a l l y related Stipion columbianae was present in areas with a cool microclimate. The Antennario - Poetum secundae and Stipetum richardsonii, although bordering associations, occupied microclimately distinct habitats. Forest communities were shown to develop at higher elevations where a cool microclimate prevails. Based on species significance data, plots were objectively grouped by the weighted-pair-group and the weighted-variable-group methods of cluster analysis. The resulting hierarchical arrangements of plots paralleled very closely the subjectively derived ecosystematic cl a s s i f i c a t i o n . On the dendro-gram obtained by the weighted-variable-group method, associations were distinguished and their degree of homogeniety and ecological relationships were demonstrated. The forest-grassland boundary in the Cariboo Zone was assessed to be relatively stable and to be controlled by available s o i l moisture as related to s o i l texture. It was apparent though, that minor fluctuations in the boundary as a result of grazing and f i r e occur. Detailed topographic relationships of the associations were demonstrated and i t was apparent that topography, which represents a complex of physio-graphic factors, i s important in controlling the distribution of associations. Successional changes appeared to be operating at a slow rate and i i thus most of the associations described were in a stable condition. The Agropyretum spicati most closely approximated the climatic climax association, occurring on ridges and slopes. Other stable associations were rated as edaphic or topographic climaxes. The successional relationships of the associations were demonstrated within a monoclimax concept in which i t was assumed that ultimately a l l associations would change into the climax as a result of s o i l weathering and peneplanation of the land. It was concluded that the gynecological approach and cla s s i f i c a t i o n methods used allowed the presentation of data in an ecosystematic format which could be directly applied to range or forest management but could also serve as a basis for more detailed s c i e n t i f i c studies. i i i TABLE OF CONTENTS Page I INTRODUCTION 1 II CONCEPT AND APPROACH 5 III REGIONAL DESCRIPTION 8 Area of Study Defined 8 Physiography 8 Soils 11 Climate 12 IV THE ECOSYSTEM UNITS 15 Methods of Analysis 15 Plant Identification and Nomenclature 17 Soil Sampling and Analyses 18 Vegetation Synthesis and Classification 20 Description of the Plant Associations (by Order and Alliance) 21 Caricetalia rostratae Caricion rostratae Caricetum rostratae 23 Salicetalia Salicion monticolae Carico (rostratae) - Salicetum monticolae 32 Scirpetalia v a l i d i Scirpion v a l i d i Scirpetum v a l i d i 41 Puccinellietalia airoidis Distichlion strictae 48 1. Puccinellio (airoidis) - Hordeetum jubati 48 2. Distichlo (strictae) - Spartinetum g r a c i l i s 57 iv TABLE OF CONTENTS (Continued) Page Betuletalia glandulosae Muhlenbergio (richardsonis)- Betulion glandulosae Muhlenbergio (richardsonis) - Betuletum glandulosae 66 Koelerio (gracilis) - Agropyretalia spicati 74 Stipion columbianae 1. Poo (juncifoliae) - Elymetum cinerei 76 2. Antennario (dimorphae) - Poetum secundae 86 (1) antennario (dimorphae)-poetosum secundae 95 (2) juncetosum b a l t i c i 96 3. Agropyro (spicati) - Balsamorhizetum sagittatae 97 4. Stipetum richardsonii 107 Agropyrion spicati 1. Agropyretum spicati 115 2. Agropyro (spicati) - Artemisietum tridentatae 125 3. Opuntio (fragilis) - Stipetum comatae 133 4. Agropyro (spicati) - Juniperetum scopulorum 143 Pseudotsugetalia menziesii 150 Arctostaphylo (uva-ursi) - Pseudotsugion *glaucae Arctostaphylo (uva-ursi) - Junipero (communis) -Pseudotsugetum *glaucae 151 Calamagrostido (rubescentis) - Pseudotsugion *glaucae 1. Calamagrostido (rubescentis) - Pseudotsugetum *glaucae 162 (1) calamagrostido (rubescentis) - pseudotsugetosum *glaucae 171 (2) pinetosum contortae 173 v TABLE OF CONTENTS (Continued) Page 2. Rhytidiadelpho (triquetri) - Pleurozio (shreberi) - Pseudotsugetum *glaucae 176 Piceetalia glaucae 186 Poo (interioris) - Calamagrostido (rubescentis) -Populion tremuloidis Poo (interioris) - Calamagrostido (rubescentis) -Populetum tremuloidis 189 (1) poo (interioris) - calamagrostido (rubescentis)-populetosum tremuloidis 195 (2) lonicero (involucratae) - caricetosum leptopodae 200 Carico (concinnae) - Piceion glaucae Carico (concinnae) - Piceetum glaucae 203 Equiseto (arvensis) - Piceion glaucae Equiseto(arvensis) - Piceetum glaucae 213 V POPULATION STRUCTURES OF THE MAJOR TREE SPECIES OF THE CARIBOO ZONE 224 Methods of Analysis and Synthesis 224 Growth and Population Size of the Tree Species 224 Population Dynamics of the Tree Species 230 VI MICROCLIMATE 238 Methods of Analysis and Synthesis 238 Comparison of Selected Associations Based on Microclimate 240 VII CLUSTER ANALYSES 249 Methods of Synthesis 249 Comparison of the Weighted-Pair-Group and the Weighted-Variable-Group Methods of Cluster Analysis 252 v i TABLE OF CONTENTS (Continued) Relationship of Ecosystem Units on the Dendrogram Obtained by the Weighted-Variable-Group Method of Cluster Analysis RELATIONSHIP BETWEEN FOREST AND GRASSLAND VEGETATION ECOLOGICAL RELATIONSHIPS OF THE ASSOCIATIONS Spatial Relationships Topographic Sequence of Forest Associations Present in the Area North of Williams Lake Topographic Sequence of the Associations Present in the Major Valleys of the Fraser Plateau Topographic Sequence of the Associations Present in Upland Areas of the Fraser Plateau Topographic Sequence of the Associations of Saline-Alkaline Habitats Topographic Sequence of the Associations formed in Glacial Stream Depressions Successional Relationships Successional Relationships of Associations Formed Primarily on Aeolian Deposits or Aeolian Deposits over Glacial Drif t . Successional Relationships of Associations Formed Primarily on Glacial D r i f t Successional Relationships of Associations Formed Primarily on Alluvium Successional Relationships of Associations Formed on Sediments in Lakes without Drainage Successional Relationships of Associations Formed on Sediments in Drained Lakes and Connecting Channels SUMMARY AND CONCLUSIONS v i i TABLE OF CONTENTS (Continued) Page XI BIBLIOGRAPHY 312 XII APPENDICES 321 v i i i LIST OF TABLES Table Page 1. Temperature and Precipitation Summaries for Big Creek and Williams Lake, British Columbia 13 2. Hierarchical Arrangement of the Ecosystem Units Described for the Cariboo Zone 22 3. Caricetum rostratae Environment Data 24 4. Caricetum rostratae Vegetation Data 25 5. Caricetum rostratae Soil Texture 28 6. Caricetum rostratae Soil Chemical Analysis 29 7. Carico - Salicetum monticolae Environment Data 33 8. Carico - Salicetum monticolae Vegetation Data 34 9\u00C2\u00BB Carico - Salicetum monticolae Soil Texture 36 10. Carico - Salicetum monticolae Soil Chemical Analysis 37 11. Scirpetum v a l i d i Environment Data 42 12. Scirpetum v a l i d i Vegetation Data 43 13. Scirpetum v a l i d i Soil Texture 45 14. Scirpetum v a l i d i Soil Chemical Analysis 46 15o Puccinellio - Hordeetum jubati Environment Data 50 16. Puccinellio - Hordeetum jubati Vegetation Data 51 17. Puccinellio - Hordeetum jubati Soil Texture 53 18. Puccinellio - Hordeetum jubati Soil Chemical Analysis 54 19. Distichlo - Spartinetum g r a c i l i s Environment Data 58 20. Distichlo - Spartinetum g r a c i l i s Vegetation Data 59 ix LIST OF TABLES (Continued) Table Page 21. Distichlo - Spartinetum g r a c i l i s Soil Texture 62 22. Distichlo - Spartinetum g r a c i l i s Soil Chemical Analysis 63 23. Muhlenbergio - Betuletum glandulosae Environment Data 67 24. Muhlenbergio - Betuletum glandulosae Vegetation Data 68 25. Muhlenbergio - Betuletum glandulosae Soil Texture 71 26. Muhlenbergio - Betuletum glandulosae So i l Chemical Analysis 72 27. Poo - Elymetum cinerei Environment Data 79 28. Poo - Elymetum cinerei Vegetation Data 80 29. Poo - Elymetum cinerei Soil Texture 82 30. Poo - Elymetum cinerei Soil Chemical Analysis 83 31. Antennario - Poetum secundae Environment Data 87 32. Antennario - Poetum secundae Vegetation Data 88 33. Antennario - Poetum secundae Soil Texture 90 34. Antennario - Poetum secundae Soil Chemical Analysis 91 35. Agropyro - Balsamorhizetum sagittatae Environment Data 99 36. Agropyro - Balsamorhizetum sagittatae Vegetation Data 100 37. Agropyro - Balsamorhizetum sagittatae Soil Texture 102 38. Agropyro - Balsamorhizetum sagittatae Soil Chemical Analysis 103 39. Stipetum richardsonii Environment Data 108 40. Stipetum richardsonii Vegetation Data 41. Stipetum richardsonii Soil Texture 42. Stipetum richardsonii Soil Chemical Analysis 43. Agropyretum spicati Environment Data 117 x LIST OF TABLES (Continued) Table Page 44. Agropyretum spicati Vegetation Data 118 45. Agropyretum spicati Soil Texture 120 46. Agropyretum spicati Soil Chemical Analysis 121 47. Agropyro - Artemisietum tridentatae Environment Data 126 48. Agropyro - Artemisietum tridentatae Vegetation Data 127 49. Agropyro - Artemisietum tridentatae Soil Texture 130 50. Agropyro - Artemisietum tridentatae Soil Chemical Analysis 131 51. Opuntio - Stipetum comatae Environment Data 135 52. Opuntio - Stipetum comatae Vegetation Data 136 53. Opuntio - Stipetum comatae Soil Texture 138 54. Opuntio - Stipetum comatae Soil Chemical Analysis 139 55. Agropyro - Juniperetum scopulorum Environment Data 144 56. Agropyro - Juniperetum scopulorum Vegetation Data 145 57. Agropyro - Juniperetum scopulorum Soil Texture 147 58. Agropyro - Juniperetum scopulorum Soil Chemical Analysis 148 59. Arctostaphylo - Junipero - Pseudotsugetum *glaucae Environment Data 153 60. Arctostaphylo - Junipero - Pseudotsugetum *glaucae Vegetation Data 154 61. Arctostaphylo - Junipero - Pseudotsugetum *glaucae Soil Texture 156 62. Arctostaphylo - Junipero - Pseudotsugetum *glaucae Soil Chemical Analysis 157 63. Calamagrostido - Pseudotsugetum *glaucae Environment Data 163 64. calamagrostido - Pseudotsugetum *glaucae Vegetation Data 164 x i LIST OF TABLES (Continued) Table Page 65. Calamagrostido - Pseudotsugetum *glaucae Soil Texture 167 66. Calamagrostido - Pseudotsugetum *glaucae Soil Chemical Analysis 168 67. Rhytidiadelpho - Pleurozio - Pseudotsugetum *glaucae Environment Data 178 68. Rhytidiadelpho - Pleurozio - Pseudotsugetum *glaucae Vegetation Data 179 69. Rhytidiadelpho - Pleurozio - Pseudotsugetum *glaucae Soi l Texture 181 70. Rhytidiadelpho - Pleurozio - Pseudotsugetum *glaucae Soil Chemical Analysis 182 71. Poo - Calamagrostido - Populetum tremuloidis Environment Data 190 72. Poo - Calamagrostido - Populetum tremuloidis Vegetation Data 191 73. Poo - Calamagrostido - Populetum tremuloidis S o i l Texture 193 74. Poo - Calamagrostido - Populetum tremuloidis So i l Chemical Analysis 194 75. Carico - Piceetum glaucae Environment Data 205 76. Carico - Piceetum glaucae Vegetation Data 206 77. Carico - Piceetum glaucae Soil Texture 208 78. Carico - Piceetum glaucae Soil Chemical Analysis 209 79. Equiseto - Piceetum glaucae Environment Data 215 80. Equiseto - Piceetum glaucae Vegetation Data 216 81. Equiseto - Piceetum glaucae Soil Texture 218 82. Equiseto - Piceetum glaucae Soil Chemical Analysis 219 83. Summary Synthesis Table for the Ecosystem Units of of the Cariboo Zone 223 x i i LIST OF TABLES (Continued) Table Page 84. The Density of Pseudotsuga menziesii, Picea glauca, Pinus contorta and Populus tremuloides by Height Class Expressed as the Number of Stems per Acre Together with Height, Age and Diameter Measurements 231 85. Location of Microclimatic Stations 239 86. Summary of Snow-Cover Data for the Antennario - Poetum secundae and the Stipetum richardsonii 247 x i i i LIST OF FIGURES Figure Page 1. The Chilcotin River Valley 9 2. The Upland Region of the Fraser Plateau 9 3. The Caricetum rostratae 31 4. The Carico - Salicetum monticolae 31 5. The Scirpetum v a l i d i 40 6. The Puccinellio - Hordeetum jubati 56 7. The Distichlo - Spartinetum g r a c i l i s 56 8. The Muhlenbergio - Betuletum glandulosae 65 9. The Poo - Elymetum cinerei 77 10. The Antennario - Poetum secundae antennario -poetosum secundae 94 11. A Close-up View of the Antennario - Poetum secundae juncetosum b a l t i c i 94 12. The Agropyro - Balsamorhizetum sagittatae 106 13. The Stipetum richardsonii 106 14. The Agropyretum spicati 124 15. The Agropyro - Artemisietum tridentatae 124 16. The Opuntio - Stipetum comatae 142 17. The Agropyro - Juniperetum scopulorum 142 18. The Arctostaphylo - Junipero - Pseudotsugetum *glaucae 161 19. The Calamagrostido - Pseudotsugetum *glaucae calamagrostido - pseudotsugetosum *glaucae 161 20. The Calamagrostido - Pseudotsugetum *glaucae pinetosum contortae 174 xiv LIST OF FIGURES (Continued) Figure Page 21. The Calamagrostido - Pseudotsugetum *glaucae pinetosum contortae with an Understory Layer of Pseudotsuga menziesii 174 22. The Rhytidiadelpho - Pleurozio \u00E2\u0080\u0094 Pseudotsugetum *glaucae 185 23. The Pleurozio - Vaccinio - Piceetum glaucae 185 24. The Poo - Calamagrostido - Populetum tremuloidis poo - calamagrostido - populetosum tremuloidis 199 25. The Poo - Calamagrostido - Populetum tremuloidis lonicero - caricetosum leptopodae 199 26. The Carico - Piceetum glaucae 212 27. The Equiseto - Piceetum glaucae 212 28. Basal Area Estimates in Square Feet per Acre for Pseudotsuga menziesii, Picea glauca, Pinus contorta and Populus tremuloides by Height Class for Associations of Occurrence 225 29. Maximum, Average Maximum, Average Minimum and Minimum Monthly Temperatures Recorded at the Microclimatic Stations for the Months of May, June, July, August and September (1968) 241 30. Dendrogram of the 131 Plots Obtained by the Weighted-Pair-Group Method of Cluster Analysis 253 31. Dendrogram of the 131 Plots Obtained by the Weighted-.Variable-Group Method of Cluster Analysis 254 32. A Soil Profile Characteristic of Grassland Areas 262 33. Topographic Sequence of Forest Associations Developed on Sandy Outwash Deposits 268 34. Topographic Sequence of Forest Associations Developed on Glacial Drif t (with a clay matrix) 270 35. Topographic Sequence of the Associations Present i n the Major Valleys of the Fraser Plateau 272 xv LIST OF FIGURES (Continued) Figure Page 36. A Deep Water-Cut Ravine in the Chilcotin Valley 274 37. Topographic Relationship Between the Opuntio -Stipetum comatae and the Agropyretum spicati 276 38. An Illustration of the Effect of Exposure on the Development of Associations in the Chilcotin Valley 276 39. Topographic Sequence of the Associations Present in the Upland Areas of the Fraser Plateau 278 40. Topographic Relationships of the Calamagrostido -Pseudotsugetum *glaucae, the Stipetum richardsonii and the Antennario - Poetum secundae 280 41. Topographic Sequence of the Associations Present i n Saline-Alkaline Habitats 282 42. Topographic Sequence of Associations Formed in Glacial Stream Depressions and their Relationship to Associations of Upland Habitats 284 43. Proposed Successional Relationships of the Associations and Subassociations of the Cariboo Zone 288 xvi LIST OF APPENDICES Appendix I II III IV Table IV-A IV-B Scales used for Estimating Species Significance and Sociability Checklist of Plants Explanatory Notes for Vegetation, Environment and So i l Tables Summary of the Temperature Data for the Microclimatic Stations Weekly Temperature Summaries for the Microclimatic Stations Monthly Temperature Summaries for the Microclimatic Stations Page 322 323 332 338 339 342 x v i i ACKNOWLEDGEMENTS The writer wishes to thank Dr. V. J. Krajina for suggesting the topic of investigation and for his guidance, assistance and encouragement during a l l phases of this study. Thanks are also due to Dr. C. D. Bird for identifying the lichen collections; to Mr. Frank Boas for identifying the bryophyte collections; to Dr. V. Bednar for identifying the Carex collection and for help with the vegetation synthesis; to Mr. M. K. Wali for aid with the chemical analyses of the soils and also for many helpful suggestions and discussions; to Mr. B. von Spindler for performing certain chemical analyses on the so i l s ; to Dr. W. B. Schofield and Dr. G. E. Rouse for suggestions on the preparation of this thesis; to Mr. D. I. Grant, Mr. B. T. Koshman and Mr. Rod Watt for assistance i n the f i e l d and to the Department of Botany for supplying space and equipment. Special thanks are due to \"the Watts of Big Creek\" who gave the writer food, shelter and companionship during the f i e l d portion of this study. This study was supported in part by a National Research Council Post Graduate Scholarship awarded to the author and by a National Research Council operating grant (No. A-92) awarded to Dr. V. J. Krajina, both of which are gratefully acknowledged. x v i i i I INTRODUCTION The natural vegetation of British Columbia has, to date, been l i t t l e studied. Several authors have, however, made general vegetation classifications. Whitford and Craig (1918) divided the province into forest types. Halliday (1937), using a regional approach in his Forest Types of Canada, divided B r i t i s h Columbia into seven regions. Later Rowe (1959) provided a similar division of the province. These studies were based primarily on forest vegetation and climate. Krajina (1965) provided a more detailed division of British Columbia, based on vegetation, climate and s o i l s . He divided the province into seven biogeoclimatic regions and eleven biogeoclimatic zones. Forest as well as non-forest vegetation was considered i n this division. A detailed characterization of these zones based on the ecological function of forest trees i s given by Krajina (1969) . Within this zonal framework a series of ecological investigations on the vegetation of British Columbia i s in progress. The present study i s part of this and i s concerned with the Cariboo - Aspen - Lodgepole Pine -Douglas-fir Parkland Zone. For convenience, in this dissertation the name of the Zone has been shortened to, simply, Cariboo Zone. The Cariboo Zone, i s part of the Canadian Cordilleran Forest Region (Krajina 1965) and has a dry continental subhumid climate. The Zone is located i n the rain shadow area east of the Coast Mountains and for the most part i s forested but also contains areas of native grassland. The present study was concentrated in the southern part of the Cariboo Zone. Previous studies of vegetation which make reference to this area 2 are relatively few. Dawson (1876) in his report on geological explorations in British Columbia mentioned that the forests along the Fraser River occur at relatively high elevations and are dominated by Pseudotsuga menziesii and Pinus contorta. He further stated that the benches along the major rivers are warmer, open prairie like and clothed with bunch-grass in which Artemisia spp. and cactus occur. Whitford and Craig (1918) referred to the area as being mostly forested by Pseudotsuga menziesii with Pinus contorta present extensively as a result of f i r e s . They mentioned an Artemisia tridentata (sage brush) type to be present along the Fraser and Chilcotin Rivers which is bordered by an open grassland, dominated by Agropyron spicatum, that extends up to meet the forest. Ilvessalo and Kujala, two Finnish foresters, c l a s s i f i e d Canadian forests based on understory vegetation. The Arctostaphylos, Calamagrostis -Arctostaphylos and Calamagrostis types described by Ilvessalo (1929) correspond to forest communities of the Cariboo Zone. Similarly, Kujala (1945) in a more comprehensive work described a \"semi-arid interior region\" which encompasses most of the Cariboo Zone. He also recognized an Arctostaphylos type, an Arctostaphylos - Calamagrostis type and a Calamagrostis type. These types were present under canopies of Pseudotsuga menziesii or Pinus contorta. Neither of these Finnish authors referred to the more arid treeless vegetation, common i n the area. Tisdale (1947) made an ecological study of the grasslands of the southern interior of British Columbia which included part of the present study area. He recognized three grassland zones, located at successively higher elevations, and a l l dominated by Agropyron spicatum. He described a number of associations (Clements 1936) within each zone and paid particular attention to retrogressive changes which take place as a result of grazing. 3 McLean and Marchand (1964), classified the grasslands of the area into condition classes with reference to the degree of grazing. The s o i l s and climate of the grasslands of B r i t i s h Columbia were br i e f l y discussed by van Ryswyk et a l . (1965), based largely on the work of Tisdale. Illingworth and Arlidge (1960) described some lodgepole pine forest s i t e types from the interior of Br i t i s h Columbia; their Calamagrostis and Calamagrostis - Arctostaphylos site types are represented i n the study area. Hamet-Ahti (1965) in a brief description of vegetation zones of British Columbia placed the region along the lower Fraser River, encompassing the present study area, i n her Hemiboreal Zone. She did not make any detailed investigation i n this area and mentioned only that pseudotsuga menziesii i s the dominant species. South of the study area, Brayshaw (1955, 1965) described associations of the Bunch Grass - Ponderosa Pine Zone, many of which are similar to communities of the Cariboo Zone. Further to the south, in eastern Washington and adjacent Idaho, Daubenmire (1942, 1952) has described associations from steppe and forest vegetations. In the grassland regions of Washington, Daubenmire (1942) recognized the same three zones that Tisdale later recognized for Br i t i s h Columbia. In dealing with the forest areas Daubenmire (1952) distinguished four zones of which the Pseudotsuga menziesii zone shows a close similarity to the forested parts of the Cariboo. It i s apparent from this brief literature review that previous to the present study the Cariboo Zone has been ecologically poorly documented. This investigation on the vegetation and environment of the Cariboo Zone was i n i t i a t e d in 1967 and continued through 1968. The main objectives were: 4 (1) to obtain q u a n t i t a t i v e and q u a l i t a t i v e data on e x i s t i n g vegetation; (2) to obtain s i m i l a r data on the p h y s i c a l environment with p a r t i c u l a r emphasis on physiographic and edaphic f a c t o r s ; and (3) to present these data i n the form of a f l e x i b l e c l a s s i f i c a t i o n of recognizable ecosystem u n i t s . From such a c l a s s i f i c a t i o n s p a t i a l as w e l l as successional r e l a t i o n -ships of ecosystem units can be i n t e r p r e t e d . D e tailed a u t e c o l o g i c a l information was not obtained i n t h i s study. However, the autecology, of at l e a s t the dominants, can be i n f e r r e d from the ecosystematic data provided. A l l previous studies which have dea l t with t h i s area have been concerned e i t h e r with f o r e s t or with grassland; none have attempted to deal with both vegetation types i n d e t a i l . The present study includes d e s c r i p t i o n s of both types as w e l l as data on t h e i r e c o l o g i c a l r e l a t i o n s h i p s . Thus i t i s b elieved that the information obtained could be u s e f u l as an a i d i n land management o f t h i s economically important region. 5 II CONCEPT AND APPROACH In current plant ecology there exist two concepts on the nature of vegetation, namely the continuum concept and the community concept. Proponents of the continuum adhere to the idea that vegetation varies continually in space and time and that recognizable vegetation units do not exist. The continuum concept has recently been reviewed in detail by Mcintosh (1967). Adherents of the community concept believe that vegetation i s composed of a mosaic of homogeneous vegetation units (plant communities), which occur repetitively, as recognizable entities i n similar habitats i n any area with a similar vegetation history. A review of the literature dealing with communities and their classification has been made by Whittaker (1962). A possible third concept on the nature of vegetation i s available from an amalgamation of these two as put forward by Poore (1955, 1956, 1964). Here, vegetation i s regarded to be continuous but to contain distinct and repetitive reference points or \"noda\". Noda are formed by abstraction from large numbers of similar stands and thus approximate the associations of phytosociology. This nodal concept of vegetation has been adopted i n the present study. The basic unit of study i n this dissertation i s the plant associa-tion as proposed at the Third International Botanical Congress of 1910 (according to Braun-Blanquet 1932) and modified by Krajina (1960) to include environment. It i s by definition considered to be ecosystematic. The association i s formed by abstraction from sampled communities which are vegetationally and environmentally homogeneous. The association as used here i s comparable to the biogeocoenosis type of Sukachev (1944, 1945) 6 and the ecosystem of Tansley (1935) while the individual plant communities (plots) are comparable to the biogeocoensis of Sukachev (1944, 1945) and Krajina (1965, 1969). A system of selective sampling was employed in this study in preference to a random or systematic scheme (Greig-Smith 1964). By this technique the infrequently occurring communities as well as the commonly occurring ones are adequately sampled and thus a more complete description of the area i s possible. If, on the other hand, a random sampling scheme had been used, the common communities would be sampled more often than the rare ones and a great many more samples would be required to provide the same descriptions. Recently there has been a trend in ecology to replace subjective methods of vegetation analysis with objective more quantitative ones. Although objective methods may yie l d an increase in accuracy they are time consuming to use. In view of this fact traditional phytosociological subjective methods of analyses have been used in this study. It i s believed that any loss in accuracy which may be inherent in the methods i s compensated for by their rapidity; thus allowing more communities to be studied. Transitional communities were not sampled in this work, instead emphasis was placed on the description of the vegetation noda. This provides a clearly defined ecological framework of plant associations. It i s believed that most transitional communities occurring in the Cariboo Zone can be placed with accuracy into this framework. In a general synecological study, such as this, i t i s not possible, nor practical to measure in detail a l l the factors operating in a holocoenotic environment (Billings 1952). Therefore some of the information presented in the association descriptions i s only observational being inferred from measured 7 factors or landscape position of the sampled communities. The inclusion of such data may be c r i t i c i z e d , and perhaps justly so. However, i t i s reasoned that i f careful thought and understanding accompanies such observations and inferences, the data, although subjective, are of value. Hopefully, the inclusion of these data w i l l make the ecology of this zone more meaningful and understandable. Certainly by discussing a l l the seemingly important factors and not simply the quantitatively measured ones, this study w i l l be of more use as a basis for detailed autecological studies and management practices. In general the approach used i n this study i s regarded to be ecosystematic. Traditional phytosociological methods are coupled with detailed environmental measurements to f a c i l i t a t e the descriptions of the associations. 8 III REGIONAL DESCRIPTION Area of Study Defined The area covered by this study i s the Southern Subzone of the Cariboo - Aspen - Lodgepole Pine - Douglas-fir Parkland Zone (Krajina 1965, 1969). Geographically the study area i s divided into two parts. One part extended from Williams Lake (52\u00C2\u00B010' N - 122\u00C2\u00B005'W) north to McAllister (52\u00C2\u00B027', 122\u00C2\u00B023*). The other part was centred in the Chilcotin region and extended from Riske Creek (51\u00C2\u00B057'N - 122\u00C2\u00B032'W) southwest to Big Creek (51\u00C2\u00B044' N, 123\u00C2\u00B002'W) and southeast to the Gang Ranch (51\u00C2\u00B033,N, 122\u00C2\u00B022'W). The area north of Williams Lake i s predominantly forested with Pseudotsuga menziesii as the dominant species. The Chilcotin region, on the other hand, i s largely an area of grassland with forested h i l l s and valleys (Fig. 1 and 2). Agropyron spicatum i s the dominant grass and the forests are mostly composed of Pseudotsuga menziesii, Pinus contorta and Populus tremuloides. Phytogeographically, this area l i e s north of the distributional limits of Pinus ponderosa, as defined by Brayshaw (1955). It i s south of the distributional limits of Picea mariana, and Picea glauca i s only marginally represented. The forested areas show greatest similarity to the Douglas-fir Biogeoclimatic Zone (Krajina 1965). The grassland areas of the Chilcotin valley are very similar to those to the south in the Thompson and Nicola valleys as described by Tisdale (1947). Physiography The area studied forms the central portion of the physiographic region designated as the Interior Plateau which has a length of 560 miles and a maximum width of 235 miles (Holland 1964). The Plateau i s flanked by the Coast and Cascade Mountains on the west and by the Rocky Mountains and Columbia 9 F i g . 1. The C h i l c o t i n River v a l l e y showing the r e l a t i o n s h i p between grassland and f o r e s t vegetation. The e f f e c t of g l a c i a t i o n i s evident by the U-shape of the v a l l e y and the rounded ridge tops. The T e r t i a r y s i l t c l i f f s , common along the r i v e r , can be seen i n the lower right-hand corner. F i g . 2. The upland region of the Fraser Plateau showing the gently r o l l i n g country and c h a r a c t e r i s t i c pattern of vegetation. The ridge tops, g u l l i e s and v a l l e y s are forested while grassland associations dominate the open slopes. Pseudotsuga men z i e s i i var. glauca i s the dominant tree species with \u00E2\u0080\u00A2.Populus\"tremuloides and Picea glauca occurring i n the g u l l i e s and v a l l e y s . Agropyron spicatum and Poa spp. are the dominant grasses. 10 Mountains on the east and southeast. Drainage of the central region of the Interior Plateau i s to the west by way of the Fraser River and i t s tributaries. The study centred on the Fraser Basin and Fraser Plateau parts of the Interior Plateau. The area north of Williams Lake i s in the Fraser Basin which i s an irregularly shaped area of low r e l i e f extending from Williams Lake, northward to McLeod Lake. It has a f l a t or gently r o l l i n g surface and for the most part l i e s below the elevation of 3000 feet. The underlying bed rock i s mostly of Permian or ear l i e r age and belongs to the Cache Creek Group (Tipper 1959). It consists largely of chert, a r g i l l i t e , limestone and greenstone. There are some localized areas of plateau lavas. These are mostly basalt and andesite of Miocene age although some lavas may be as young as Pleistocene (Tipper 1959). The plateau lavas are generally not thick, probably 500-1000 f t at the most. Most of the basin i s covered by g l a c i a l d r i f t and alluvium, and bed rock i s exposed i n only a few places. These deposits average in depth from 25 to 50 f t although i n some places they are as deep as 600 to 700 f t (Tipper 1959). Ice movement during the Pleistocene has been judged to have been northward as based on the orientation of drumlins formed in the g l a c i a l d r i f t (Holland 1964). The Fraser Plateau l i e s west of the Fraser River and includes the part of the study area centred in the Chilcotin region. It i s a f l a t to gently r o l l i n g country with large areas of undissected upland at elevations between 3000 and 5000 f t . The Plateau i s cut by deep U-shaped, glaciated valleys, whose floors l i e at elevations of 1400 to 2000 f t . The geology of the Fraser Plateau i s poorly understood and only general statements are possible. Most of the Plateau i s underlain by gently dipping plateau lava flows (Tipper 1959, Holland 1964). These are of late Miocene or Pliocene age and consist mostly of olivine basalts and andesites. 11 The flows have steep escarpments along the rivers and almost horizontal upper surfaces. The existing lava i s concentrated largely between the elevations of 3000 and 4500 f t and i s believed to represent the remains of a large lava plain from which tongues extended along the major valleys and depressions. These lavas provide a parent rock for the s o i l which i s rich i n basic cations, especially magnesium and calcium. Below the lavas along the Chilcotin River are exposed large c l i f f s of s i l t and silstone which are believed to be of Tertiary age. Most of the Plateau i s covered by gl a c i a l d r i f t and i t i s estimated that less than 5% bedrock i s exposed (Holland 1964). Much of the d r i f t was moulded into drumlin\u00E2\u0080\u0094like landforms during the Pleistocene and these provide most of the r e l i e f . During the last glaciation, the ice movement across the Plateau i s believed to have been i n a north to northeastward direction. Fig. 1 and 2 i l l u s t r a t e the physiography of the Chilcotin region. Soils At the present time there i s no published description of the soil s of this region. Based on observations made during this study i t appears that soil s representative of a l l six orders of the Canadian s o i l c l a s s i f i c a t i o n scheme are present in this area. Soils classed in the Chernozemic and Brunizolic Orders are the most common. It appears that the most common s o i l forming process i s melanization. Soils of the Gleysolic, Regosolic and Solonetzic \"Orders are of localized importance. Soils belonging to the Podzolic order are rare in this region. However, there i s evidence that Podzolization i s occurring as integrades to the Podzolic Order from the Brunizolic and Chernozemic .Orders are present. A detailed account of the soil s i s given with the association descriptions. 12 Climate The climate of the area i s controlled largely by the presence of the Coast Mountains to the west which act as an ef f i c i e n t barrier to the westerly wind. Air masses moving eastward from the Pacific lose most of their moisture i n passing over the mountains. Thus the study area i s i n a rain-shadow region and i s di s t i n c t l y dry. The climate i s characterized as microthermal subhumid continental (Dfb) according to Kfippen's cla s s i f i c a t i o n (Chapman 1952; Krajina 1965) and as subhumid according to that of Thorthwaite (Sanderson 1948). c In Table 1 climatic summaries are presented for Big Creek and Williams Lake, the two closest Meteorological Stations. The temperature and precipitation data are based on a 30 year average for Big Creek and on a 10 year average for Williams Lake(\"Temperature Normals for Br i t i s h Columbia\" 1965 and \"Precipitation Normals for Br i t i s h Columbia\" 1965). At Big Creek, which i s at the western boundary of the study area, the mean annual temperature i s 36.3\u00C2\u00B0 F. The mean monthly temperatures are above 32\u00C2\u00B0F for the months of April through October, the highest being 56.4\u00C2\u00B0F in July and the lowest being 13.2\u00C2\u00B0F in January. The highest mean maximum monthly temperature i s 71.5\u00C2\u00B0F i n July and the lowest mean minimum monthly temperature i s 1.8\u00C2\u00B0F i n January. The annual precipitation averages 12.63 inches and occurs as a summer maximum with 6.06 inches recorded during the months of June through September. The average annual snowfall i s 49 inches occurring mainly in the months of November through March but snow has been recorded for every month of the year except July and August. Based on the data from the Williams Lake Meteorological Station, the area appears warmer and more moist than that of Big Creek. At Williams Lake the mean annual temperature i s 43.5\u00C2\u00B0F. The mean monthly temperatures are above 32\u00C2\u00B0F for months of March through October, the Table 1 Temperature and Precipitation Summaries for Big Creek and Williams Lake, British Columbia Recording Station Mean Annual Temp (degrees) No. Months with Mean Temp Above 32\u00C2\u00B0F Mean Max Monthly Temp (degrees F) Mean Min Monthly Temp (degrees F) Mean Annual Precipi-tation (inches) Mean Annual Snowfall (inches) Big Creek 51\u00C2\u00B044' N, 123\u00C2\u00B002' W Elevation - 3720' 36.3 71.5 1.8 12.63 49.0 Williams Lake 52\u00C2\u00B010' N, 122\u00C2\u00B005' W Elevation - 1945' 43.5 80.0 14.1 14.9 40.9 0 o highest being 64.4 F in July and the lowest being 22.2 F i n January. The highest mean maximum monthly temperature i s 80.0\u00C2\u00B0F in July and the lowest mean minimum monthly temperature i s 14.1\u00C2\u00B0F in January. The mean annual precipitation i s 14.9 inches of which 8.2 inches occurs during May to September. The mean annual snowfall i s 40.9 inches occurring mainly i n the months of December through February. Snow has never been recorded in June, July or August. Detailed temperature observations on a microclimatic scale were made as part of this study and are presented in Chapter VI. 15 IV THE ECOSYSTEM UNITS The ecosystem i s a basic unit in ecology and can be defined as an energy driven complex of organisms and i t s controlling environment (Billings 1965). . Tansley (1935) originated the concept of the ecosystem and considered i t to be flexible, and fundamental to ecology. He recognized that ecosystems could exist at different biological levels of organization and be of various sizes and kinds. In this study the concept i s similarly applied. Ecosystems are considered here to be both concrete and abstract and to vary from detailed to very broad levels of organization. Ecosystem units are dealt with at levels of organization ranging from the concrete and detailed level of the plant community (individual plot) through the abstract and successively broader levels of the subassociation, association alliance and order. A l l of these units are applied within the zonal ecosystem concept of Krajina (1965). Comparable ecosystematic structures have been developed in British Columbia by Orloci (1964) and Brooke (1966). Methods of Analysis Two reconnaissance trips were made at the beginning of the study (1) \u00E2\u0080\u0094 one i n May 1967, to the area north of Williams Lake and one in July 1967 to the Fraser Plateau. During these t r i p s , observations were made on the com-position and structure of the vegetation and a comprehensive collection of plants was obtained and identified. As a result, a l i s t of tentative plant associations based on dominance and physiognomy was prepared. Potential communities for sampling were located i n accordance with the tentative associations and the following selection c r i t e r i a : J. Krajina accompanied the author on both tr i p s . 16 (1) A cornmunity had to be uniform in composition and structure, f l o r i s t i c a l l y and environmentally, (i.e. homogeneous). (2) A community had to be large enough to allow the incorporation of a sample plot of predetermined size. This ensured that edge effect would be minimal and that association fragments (Braun-Blanquet 1932, page 25) would not be sampled. (3) A community had to occur as a repeatable ecological unit throughout the study area. A l l communities were sampled using a single plot method. Forest communities were sampled with a 20 m x 20 m (400 sq m, 1/10 acre) plot and non-forest communities were sampled with a 10 m x 10 m (100 sq m, 1/40 acre) plot. Plots were subjectively placed i n communities selected for study using a Brunton compass and metallic tape. This careful placement of sample plots allowed an accurate description of associations with a minimum of samples. The vegetation was analyzed following the quantitative and qualita-tive phytosociological methods developed by Ztirich Montpellier School (Braun-Blanquet 1932, Becking 1957, Krajina 1933). Percentage cover estimates were made for the following vegetation layers where present. A\u00E2\u0080\u0094Tree Layer\u00E2\u0080\u0094woody plants over 33\" in.height. Sublayers - over 66 f t A 2 \" 49 f t to 66 f t A 3 - 33 f t to 49 f t B\u00E2\u0080\u0094Shrub Layer\u00E2\u0080\u0094woody plants between 1 f t and 33 f t i n height Sublayers B x - 6 f t to 33 f t (high shrub) B 2 - 1 f t to 6 f t (low shrub) C\u00E2\u0080\u0094Herb and Dwarf Shrub Layer\u00E2\u0080\u0094Herbaceous plants and woody plants less than 12 inches high. 17 D\u00E2\u0080\u0094Bryophyte and Lichen Layer E\u00E2\u0080\u0094Epiphytic Layer Species were l i s t e d by strata 'and a subjective estimate of species significance was made for each, using the eleven point Domin-Krajina scale (Krajina 1933). Estimates of sociab i l i t y or dispersion patterns were made for l i s t e d species using an eleven point scale after Krajina (1933). Both scales are given in Appendix I. Unknown species were assigned a descriptive name and collected for positive determination. Quantitative and qualitative data were obtained on the physiographic factors of slope angle, exposure, latitude, longitude, elevation, landform type, and pattern of topography. Notes were made on the evidence of f i r e history, amount of grazing and the type and degree of erosion. Estimates of the percentage of ground surface covered by humus and l i t t e r , exposed mineral s o i l , decaying wood and rock were also made for each plot. A total of one hundred and thirty one plots was analyzed. Plant Identification and Nomenclature Unknown vascular plants collected were identified using the following manuals: \"Vascular Plants of the Pacific Northwest\", Vol. 2-5 (Hitchcock et a l . 1955-1964); \"The Flora of Idaho\" (Davis 1952) ; \"Illustrated Flora of the Pacific States\" (Abrams 1940-1951); \"Flora of Alberta\" (Moss 1959); \"Flora of Alaska\" (Hulten 1968); \"Manual of the Grasses of the United States\" (Hitchcock 1950) ; \"The L i l y Family (Liliaceae) of British Columbia\" (Taylor 1966); \"The Ferns and Fern A l l i e s of Bri t i s h Columbia\" (Taylor 1963). Lichen collections were identified by Dr. C. D. Bird of the University of Calgary. Bryophyte collections were identified by Mr. F. M. Boas. Carex collections were identified by Dr. V. Bedner, Dr. V. J. Krajina identified some of the more d i f f i c u l t vascular plants and checked the identifications of a l l specimens of V 18 the family Gramineae. A l l plant collections are deposited as voucher specimens in the Herbarium of the Department of Botany, University of British Columbia. The authorities for species referred to in the text and tables are given in Appendix II. Variety status of species i s not indicated in the text or tables but i s assigned where appropriate in the checklist (Appendix II). It should be mentioned that the dominant tree species, Pseudotsuga menziesii, referred to in this dissertation i s the interior variety glauca. r S o i l Sampling and Analyses One s o i l p i t was dug in each plot and the profil e described by horizon. The following were included i n the descriptions: horizon depth and thickness; evidence of mottling; presence of coarse fragments; efferves-cense with dilute HC1; and root distribution. A total of 432 s o i l samples w a s collected for chemical and textural analyses. Soil samples were screened through a 2 mm screen and the less than 2 mm size fraction collected. To determine the source of the parent material some of the coarse fragments collected were tentatively identified by Dr. G. E. Rouse of the Department of Botany and Geology. Textural analysis on the less than 2 mm size fraction of the mineral soi l s was done by the revised hydrometer method (Bouyoucos 1951) , using a reciprocal shaker to agitate the s o i l suspension. The textural cla s s i f i c a t i o n followed was that of the United States Department of Agriculture (sand = 2.00 to 0.05 mm; s i l t - 0.05 to 0.002 mm; clay, less than 0.002 mm). This method was selected because of i t s simplicity and rapidity. It should be noted that the hydrometer method does not c a l l for soils to be pretreated by HC1 to destroy carbonates and with H2O2 t o destroy organic matter. These materials are dispersed and measured i n the main group 19 separates (Bouyoucos 1951). Chemical analyses were made on the less than 2 mm size fraction of the s o i l s . Determinations of carbon, total nitrogen,total phosphorus and cation exchange capacity were done by Mr. B. von Spindler of the Department of Soil Science, University of Bri t i s h Columbia. The determinations of pH and exchangeable calcium, magnesium, potassium and sodium were performed in the Department of Botany. Carbon determinations were made using a Leco total carbon analyzer and the results were expressed directly in per cent total carbon. Total nitrogen, which i s expressed as a percentage, was measured by a macro Kjeldahl method (NH-j d i s t i l l e d i n boric acid, and titrated with sulphuric acid). Carbon:nitrogen ratios were calculated from these data. The dilute acid-fluoride extraction method (method 1) of Bray and Kurtz (1945) as adapted by the Department of S o i l Science, University of Bri t i s h Columbia was used to colorimetrically determine total phosphorus (Metson 1961). To extract the exchangeable cations (calcium, magnesium, sodium and potassium), s o i l samples were leached with 1 N ammonium acetate (pH adjusted to 7) and f i l t e r e d gravimetrically following a method adapted by the Department of S o i l Science, University of Br i t i s h Columbia from Peech et a l . (1947). The concentrations of the cations were then determined from the leachates on a Perkin-Elmer, model 303, atomic adsorbtion spectrophotometer. The results were expressed i n meg/100 g of s o i l . For so i l s with high salt concentrations, the exchangeable cation determinations w i l l be slig h t l y high as the leaching process tends to extract, otherwise unavailable cations from soluable salts. Cation exchange capacity (CEC) was determined using the leached s o i l after washing with ethyl alcohol and then d i s t i l l a t i o n of ammonia into boric acid and t i t r a t i o n with dilute sulphuric acid (method of Department of 20 S o i l Science, U n i v e r s i t y of B r i t i s h Columbia). S o i l pH was determined with a Beckman model N pH meter on s o i l samples mixed to a paste consistency and allowed to e q u i l i b r a t e (Wilde and Voigt 1955). Vegetation Synthesis and C l a s s i f i c a t i o n Synthesis of the a n a l y t i c a l data was the second phase of t h i s study. Sampled p l o t s were grouped according to the c r i t e r i o n of f l o r i s t i c s i m i l a r i t y i n t o associations following standard p h y t o s o c i o l o g i c a l methods. Constancy and average species s i g n i f i c a n c e were c a l c u l a t e d f o r species by a s s o c i a t i o n . Constancy i s a s y n t h e t i c character expressing the frequency of occurrence o f a species w i t h i n an a s s o c i a t i o n when a l l sample p l o t s are of the same s i z e . I t was c a l c u l a t e d by expressing the number of p l o t s of occurrence as a percentage of the t o t a l p l o t s . Constancy percentages were expressed on the following f i v e - c l a s s s c a l e . Class Percentage I 0-20 II 21-40 II I 41-60 IV 61-80 V 81-100 Average species s i g n i f i c a n c e i s considered as an i n d i c a t i o n of the importance of a species w i t h i n an a s s o c i a t i o n . I t was c a l c u l a t e d by summing the species s i g n i f i c a n c e estimates and d i v i d i n g by the number of p l o t s i n the a s s o c i a t i o n . The associations were r e l a t e d and compared using constancy and average species s i g n i f i c a n c e data i n a synthesis table (Table 83, page 223 ). Only species which had occurred i n at l e a s t one a s s o c i a t i o n with a constancy of 60% or greater were used i n formation of the t a b l e . Thus the e f f e c t of 21 sporadic species was removed. From the table, characteristic species were determined for each association. These are species which reach maximum importance (high constancy and high average species significance) i n the association under consideration. Associations for which good characteristic species could not be found were reduced to the rank of subassociations for which characteristic species are not necessary and habitat conditions become paramount for differentiation (Krajina 1933). Differential species (Braun-Blanquet 1932, p. 59, Krajina 1933) were determined for a l l subassociations. The associations were united into the higher units of alliances and orders. Environmental as well as f l o r i s t i c data were used i n the forma-tion of higher units to ensure an ecosystematic cl a s s i f i c a t i o n . Characteristic species were determined for each category formed. Finally the characteristic combination of species (Braun-Blanquet 1932e Krajina 1933, Brooke 1966) was determined for each association. These are species, which taken as a group, best characterize the association under consideration and show i t s f l o r i s t i c relationships to the corresponding alliance and order. The ecosystem units were named following standard phytosociological practice to indicate systematic rank. Unit designations are formed from the generic name of a characteristic species as follows: Order: - e t a l i a Alliance: -ion Association: -etum Subassociation: -etosum Description of the Plant Associations In this section the associations and where appropriate, the subassociations, are characterized environmentally and f l o r i s t i c a l l y . Each 22 H i e r a r c h i c a l Arrangement of the Ecosystem Units Described for the Cariboo Zone SUBASSOCIATION ASSOCIATION Caricetum ros t r a t a e C a r i c i o n rostratae C a r i c e t a l i a rostratae Carico - Salicetum monticolae S a l i c i o n monticolae S a l i c e t a l i a Scirpetum v a l i d i S c i r p i o n v a l i d i S c i r p e t a l i a v a l i d i P u c c i n e l l i o -Hordeetum j u b a t i D i s t i c h l o -Spartinetum g r a c i l i s D i s t i c h l i o n s t r i c t a e P u c c i n e l l i e t a l i a a i r o i d i s , Muhlenbergio -Betuletum glandulosae Muhlenbergio -Betulion glandulosae B e t u l e t a l i a glandulosae juncetosum b a l t i c i antennario -poetosum secundae Poo - Elymetum c i n e r e i Antennario -Poetum secundae Agropyro -Balsamorhizetum s a g i t t a t a e Stipetum r i c h a r d s o n i i Agropyretum s p i c a t i Agropyro -Artemisietum t r i d e n t a t a e Opuntio - Stipetum comatae Agropyro -Juniperetum scopulorum S t i p i o n columbianae Agropyrion s p i c a t i Koelerio -Agropyretalia s p i c a t i calamagrostido - ) Arctostaphylo - Junipero -Pseudotsugetum *glaucae pseudotsugetosum *glaucae ) Calamagrostido -) Pseudotsugetum *glaucae pinetosum contortae ) Rhytidiadelpho - Pleurozio -Pseudotsugetum *glaucae Arctostaphylo -Pseudotsugion *glaucae Calamagrostido -Pseudotsugion *glaucae Pseudotsugetalia menziesii poo - calamagrostido -populetosum tremuloidis l o n i c e r o -caricetosum leptopodae Poo - Calamagrostido -Populetum tremuloidis Carico - Piceetum glaucae Poo - Calamagrostido -Populion tremuloidis Carico - Piceion glaucae P i c e e t a l i a glaucae Equiseto - Piceetum glaucae Equiseto - Piceion glaucae habitat i s rated trophotopically and hygrotopically according to the scheme of Progrebniak (1930), and Krajina (1969). The soi l s are classed according to the Canadian System of Soil Classification (N.S.S.C.C. 1965). Comparisons, where necessary, are made to the Canadian System of Soil Classification (N.S.S.C.C. 1968). The associations are described and discussed by alliances and orders following the scheme presented i n Table 2. The ecosystem units are arranged, physiognomically, into two sections, namely, non-forest vegetation and forest vegetation. Within the non-forest section, units are arranged along a gradient of decreasing moisture from the Caricion rostratae to the Agropyrion s p i c a t i . Within forest vegetation section the ecosystem units are arranged along an increasing moisture gradient from the Arctostaphylo \u00E2\u0080\u0094 Pseudotsugion *glaucae to the Equiseto - Piceion glaucae. The presentation of the ecosystem units according to this scheme allows the relationships between them to be easily recognized. The complete synthesis table l i s t i n g characteristic species for a l l associations, alliances, and orders i s given at the end of this chapter on page 2.23as Table 83. The explanations for symbols and abbreviations used in the vegetation, environment and s o i l s tables are given i n Appendix III. Caricetalia rostratae Caricion rostratae Caricetum rostratae (ref. Tables; 3, 4, 5, 6, 83, and Fig. 3) Characteristic Combination of Species Order, Alliance and Association Characteristic Species Calamagrostis neglecta Carex aquatilis Carex rostrata Hippuris vulgaris 24 Table 3 Caricetum rostratae Plot Data Number of Plots Plot No. Plot Size (m2) Date analyzed Elevation (ft) Locality Physiography Landform Relief shape Exposure Slope gradient (\u00C2\u00B0) Layer coverage (%) C layer D layer Plot coverage (%) Humus and l i t t e r Water Soil Hygrotope Trophotope Erosion Drainage Horizon depth (in) surface subsurface 1 2 3 4 5 114 112 104 113 115 100 100 100 100 100 30/8 26/8 14/8 26/8 27/8 1968 1968 1968 1968 1968 3400 2460 3500 3500 3550 FP - FP FP FP FP 51\u00C2\u00B044' 51044. 51\u00C2\u00B044' 51\u00C2\u00B043' 51\u00C2\u00B044' 122\u00C2\u00B052' 122 0 53 ' 122\u00C2\u00B039' 122\u00C2\u00B054' 122\u00C2\u00B053 91 8 95 100 86 12 96 100 shallow lake ... f l a t ... ,..neutral..., 0 90 6 98 100 85 10 100 100 hydric to (hygric) permesotrophic . n i l ...... impeded .... 89 6 100 100 0-12 12-35+ 0-13 13-26+ 0-12 12-28+ 0-14 4-26+ 0-12 12-24+ Parent material sediments Table 4 Caricetum r o s t r a t a e Number of P l o t s 1 2 3 4 5 P l o t No. 114 112 104 113 115 P l o t S i z e (m2) 100 100 100 100 100 E l e v a t i o n ( f t ) 3400 3460 3500 3500 3550 C Layer Sporadic species C Layer 8 Calamagrostis canadensis 9 Carex p r a e g r a c i l i s Avg Species Constancy S i g n i f i c a n c e 1 Carex r o s t r a t a 8.6 8. ,5 8. 7 8 .6 8. .6 V 8. 0 2 Carex a q u a t i l i s 6.3 6. ,3 7. 3 5 .3 6. ,3 V 6. 0 3 Calamagrostis neglecta 2.1 3. ,2 4. 2 3 .2 3. .1 V 3. 0 4 Hip p u r i s v u l g a r i s - 2. , 1 2. 2 2 .1 1. ,1 IV 1. 4 5 Ranunculus s c e l e r a t u s - 2. ,+ 1 .+ II 0. 6 6 Epilobium p a l u s t r e 1.1 + , ,+ II 0. 3 D Layer 7 Drepanocladus aduncus 4.2 5. ,2 5. ,2 4 .2 4. ,2 V 4. 4 TOTAL SPECIES ( i n c l . sporadics) 7 5 4 6 5 114(1.1) 113(1.1) 10 Juncus b a l t i c u s 114(1.1) D Layer 11 Amblystegium serpens 114(1.1) 26 The Caricetalia rostratae i s considered to be related to the European Phragmitietalia described by Koch (1926), mainly on the basis of habitat s i m i l a r i t i e s . Similarly, the Caricion rostratae has a strong a f f i n i t y with the European Magnocaricion elatae (Koch 1926). The Caricetalia rostratae i s represented i n the Cariboo Zone by a single alliance and a single association. The Caricetum rostratae develops on the Fraser Plateau i n shallow, well drained, lakes at elevations over 3200 f t above sea level. The lakes are formed in g l a c i a l stream depressions and are interconnected by small streams. Water movement through the lakes i s continuous although slow. In the shallow parts of these lakes the Caricetum rostratae forms closed communities while in deeper parts of the lakes open communities develop and bodies of open water are present. The only release from submergence of this association occurs near the edges of the lakes where the water recedes below the s o i l surface i n the late f a l l . However, even i n such cases, the s o i l remains saturated and free water i s always present. The hygrotope i s therefore rated as hydric but may occasionally be lowered to subhydric. This association i s considered to be aquatic. From 95% to 100% of the surface of the association i s covered by a layer of Carex l i t t e r which i s present as a floating mat during submergence. There i s no evidence of surface erosion but rather because of the aqueous situation, some deposition of mineral s o i l i s probably taking place. The s o i l has two horizons. The surface horizon varies from 12 to 14 inches in thickness and contains an accumulation of organic matter with measured carbon ranging from 2.5% to 42.3%. The subsurface horizon i s a strongly gleyed mineral horizon. Organic matter, as a result of deposition, i s present in this horizon, and the percentage of measured carbon ranges from 1.4% to 13.4%. 27 The s o i l i s formed from a parent material Of sediments. Plots 114 and 115, because of a high sand and gravel content probably represent f l u v i a l sediments, while the other plots, a l l of which have finer sediments, are probably of a lacustrine origin. However, because the soils were under water sedimentation bands were not observed. The textural class of the surface horizon ranges from sandy loam to clay loam. These measurements are only approximate because the organic matter content may interfere with the texture determination (Bouyoucos 1951). The subsurface horizon varies i n textural class from sandy loam to loam. In both horizons the s i l t and sand fraction i s greater than the clay fraction which i s similar to the soils on the surrounding uplands. The s o i l reaction i s neutral to alkaline in both horizons with measured pH values ranging from 7.4 to 8.1. The cation exchange capacity i s high i n the surface horizon corresponding to the accumulation of organic matter and decreases considerably in the subsurface horizon as does the organic matter content. Exchangeable cations and phosphorus are present i n high concentrations near the surface and decrease i n amount down the p r o f i l e . Exchangeable calcium i s generally present i n higher amounts than exchangeable magnesium due possibly to the higher s o l u b i l i t y of calcium salts in water, particularly carbonates and sulfates, and to the higher calcium content of organic matter. The habitat i s considered to be permesotrophic to eutrophic because of the favourable pH and high concentrations of exchangeable cations. Nitrogen i s present in moderate amounts in the surface horizon but the carbon:nitrogen ratios are relatively high indicating that the organic matter accumulated in this horizon may not contain sufficient nitrogen for i t s decomposition and thus a competition for nitrogen between higher plants and microorganisms may result. Nitrogen i s present i n lower amounts in the subsurface horizon but the carbon:nitrogen ratios are more favourable which Number of Plots Plot No. Surface Horizon Textural class Clay (%) S i l t (%) Sand (%) Coarse fragments Subsurface Horizon Textural class Clay (%) S i l t (%) Sand (%) Coarse fragments Table-5 Soil Texture Caricetum rostratae 1 2 3 4 5 114 112 104 113 115 L CL SiL SL L 14 30 22 8 12 36 49 54 34 44 50 21 24 58 44 None SL L SL L SL 11 24 9 23 10 11 41 47 44 17 78 35 44 33 73 g. None None None g. 29 Table 6 Soil Chemical Analysis Caricetum rostratae Number of Plots Plot No. Surface Horizon 1 114 2 112 3 104 4 113 5 115 C% N% C/N P ppm Na K Ca Mg CEC PH 42.3 1.35 31.3 36.0 2.08 .52 29.0 40.2 103.7 7.4 11. 6. .5 .21 .9 .0 .76 .50 15.2 14.5 24.8 7.8 4.9 .23 21.3 10.0 .87 .30 12.8 24.6 36.4 7.9 17.3 .83 20.8 16.0 2.28 .86 29.8 3.8 45.3 8.0 32.2 .96 46.7 13.0 1.36 1.24 34.8 28.2 76.3 7.5 Subsurface Horizon C% 13.4 1.3 N% .69 .08 C/N 19.4 16.3 P ppm 11.0 9.0 Na .72 .74 K .43 .16 Ca 18.8 17.9 Mg 6.7 10.1 CEC 32.8 22.0 pH 7.6 7.7 .0 ,15 .0 .0 .61 .35 17.8 20. 15. 17. 40. 7. 1.4 .09 15.6 8.0 1.1 .19 7.1 19.9 10.7 8.1 8.4 .45 18. 7. 17 7 7 0 38 53 9 1 26.8 7.8 30 suggests that nitrogen i s available for the growth of higher plants. Compared to t e r r e s t r i a l s o i l s , the aeration of these submerged soils i s considered to be poor even though some water movement i s occurring. Thus a reducing atmosphere w i l l exist and anaerobic decomposition w i l l be favoured over aerobic decomposition. This probably results i n a reduction i n the rate of decomposition which w i l l l i m i t the a v a i l a b i l i t y of nitrogen and other nutrients bound in the accumulated organic matter. The soi l s of the Caricetum rostratae are classed either as Orthic Humic Gleysols (horizon sequence Ah, Cg) i f the surface horizon has less than 30% organic matter or as Rego Gleysols (horizon sequence L-H, Cg) i f the surface horizon contains more than 30% organic matter. The Caricetum rostratae i s structurally simple, consisting of a well developed C layer with a coverage ranging from 85% - 91% and a poorly developed D layer covering 6% - 12% of the sampled area. Carex rostrata and Carex aguatilis are constant dominants with average species significances of 8.0 and 6.0 respectively. Calamagrostis neglecta i s the only other constant dominant and i s present with an average species significance of 3.0. Hippuris vulgaris, although occurring with a constancy of only class IV and an average species significance of 1.4, i s considered as a characteristic species because i t i s exclusive to this association. Calamagrostis canadensis i s present as a sporadic species where the pH i s close to neutral. The sporadic occurrence of Juncus balticus and Carex praegracilis, both characteristic of semi-terrestrial and t e r r e s t r i a l sites, indicates the shallowness of the water. The D layer i s composed largely of one species> Drepanocladus aduncus which occurs as a constant species with an average species significance of 4.4. The Caricetum rostratae has a history of slight grazing, as the 31 Fig. 3. The Caricetum rostratae showing the dense growth of Carex rostrata and Carex aquatilis. The open body of water, in which Hippuris vulgaris can be seen, i s typical of this association. Fig. 4. The Carico - Salicetum monticolae showing the closed nature of the shrub layer dominated by Salix spp. The dominance of the C layer by Carex rostrata and Carex aquatilis shows the similarity of this association to the Caricetum rostratae. 32 shallow water communities are grazed i n the late f a l l . In very dry years the Caricetum rostratae may be cut as \"swamp hay\" on some parts of the Fraser Plateau. Sal i c e t a l i a Salicion monticolae Cario (rostratae) - Salicetum monticolae (ref. Tables; 7, 8, 9, 10, 83, and Fig. 4) Characteristic Combination of Species Alliance and Association Characteristic Species Salix arbusculoides Salix monticola Aster junciformis Calamagrostis canadensis Galium trifidum Mnium rugicum Rhynchostegiella compacta Important Companion Species Carex aquatilis Carex rostrata Calamagrostis neglecta Juncus balticus The Salicetalia i s an order proposed to unite associations character-ized by Salix species. In this study i t i s represented by one alliance, the Salicion monticolae, and one association, the Carico (rostratae) - Salicetum monticolae. The Carico - Salicetum monticolae i s found along the stream channels connecting shallow lakes located in g l a c i a l stream depressions. It also develops in local depressions which were formerly parts of shallow lakes. The surface topography of this association i s f l a t and the exposure i s neutral. It usually adjoins the Caricetum rostratae but i s a few feet higher in r e l i e f . This association i s flooded annually and remains submerged during the early part of the growing season. By mid-summer the water table has Table 7 .Carico (rostratae) - Salicetum monticolae Plot Data Number of Plots Plot No. Plot Size (m2) Date analyzed Elevation (ft) Locality Physiography Landform Relief shape 1 2 3 4 5 127 128 126 129 130 100 100 100 100 100 4/9 4 /9 30/8 5/9 5/9 1968 1968 1968 1968 1968 3200 3250 3300 3300 2600 FP FP FP FP FP 5 1 \u00C2\u00B0 4 4 ' s i \" ^ 1 5 1 \u00C2\u00B0 4 4 ' 5 1 \u00C2\u00B0 4 4 ' 51\u00C2\u00B042 1 2 2 \u00C2\u00B0 5 1 ' 1 2 2 \u00C2\u00B0 5 1 ' 1 2 2 \u00C2\u00B0 4 8 ' 1 2 2 \u00C2\u00B0 4 8 ' 1 2 2 \u00C2\u00B0 5 7 ' Depres-sion edge of stream channel f l a t Exposure Slope gradient (\u00C2\u00B0) 0 0 0 0 0 Layer coverage (%) Bi layer 52 58 48 52 48 B2 layer 22 24 18 24 18 C layer 88 84 94 86 91 D layer 29 26 45 35 36 Plot coverage (%) Humus and l i t t e r 96 96 95 93 96 Water 100 (temporary) Soi l Hygrotope hydric - hygric Trophotope Erosion Drainage Horizon depth (in) surface subsurface permesotrophic ..... n i l .... impeded ... 0-10 10-30+ 0-11 11-26+ 0-13 13-26+ 0-11 11-38+ 0-10 10-32+ Parent material organic matter and sediments Table 8 Carico (rostratae) - Salicetum monticolae Number of Plots 1 2 3 4 5 Plot No. 127 128 126 129 130 Plot Size (m ) 100 100 100 100 100 Elevation (ft) 3200 3250 3300 3300 3600 sub Avg Species Pi Layer layer Constancy S i g n i f i c a n c e 1 S a l i x monticola 1 7.3 8.2 5.3 6.3 6.2 V 6.4 2 5.1 5.2 4.2 3.2 4.2 - 3.8 2 S a l i x arbusculoides 1 2.1 3.3 4.4 5.4 5.4 V 4.2 2 3.2 4.2 3.2 5.2 3.2 - 3.6 3 S a l i x brachycarpa 2 3.2 4.2 - - 3.2 V 2.0 4 S a l i x b a r c l a y i 2 2.+ - 2.+ \u00E2\u0080\u0094 II 0.8 c Layer 5 Carex r o s t r a t a 7.5 8.6 8.6 8.4 8.5 V 7.8 6 Carex a q u a t i l i s 6.4 6.4 6.5 6.3 6.7 V 6.2 7 Calamagrostis neglecta 4.1 5.2 5.1 4.2 5.2 V 4.6 8 Aster junciformis 2.1 3.2 3.2 4.1 3.2 V 3.0 9 Juncus b a l t i c u s + .+ + .+ 2.1 1.+ 1.+ V 1.0 10 Calamagrostis canadensis 3.2 - 1.+ 1.1 2.1 IV 1.4 S a l i x brachycarpa - 2.2 1.+ 2.1 1.+ - 1.2 11 Taraxacum o f f i c i n a l e - 1.+ 2.+ 2.+ 1.1 IV 1.2 12 Galium t r i f i d u m - 2.1 1.+ - 2.1 III 1.0 13 Hordeum jubatum 1.+ - - I I I 0.4 D Layer 14 Drepanocladus aduncus 6.2 5.2 7.3 6.2 6.2 V 6.0 15 Rhynckestegiella compacta 3.2 3.2 2.2 3.2 3.2 V 2.8 16 Mnium rugicum - 3.2 4.2 4.2 3.2 IV 2.8 17 Bryum w e i g e l l i i - 2.2 3.1 - - II 1.0 TOTAL SPECIES ( i n c l . sporadics) 16 16 19 15 14 Sporadic species C Layer 18 Carex p r a e g r a c i l i s 19 Epilobium pulustre 127(3.2) 126(+.+) 21 Poa i n t e r i o r 126(+.+) 22 Polygonum hydropiperoides 126(+.+) 23 T r i g l o c h i n palustre 127(1.+) 35 generally receded to below the s o i l surface but free water i s always present in the profile within approximately six inches of the surface. Soil drainage i s thus rated as impeded. This habitat i s considered to be hydric to hygric and the Carico - Salicetum monticolae i s judged to be a semi-terrestrial association. The s o i l surface i s covered by an extensive l i t t e r layer composed of the leaves of Salix and Carex. This material forms the major source of s o i l organic matter. The s o i l consists of two recognizable horizons. The surface horizon i s an organic-mineral one, varying from 10 to 13 inches i n thickness and has a carbon content ranging from 14% to 26.5%. It overlies a predominantly organic horizon with measured carbon ranging from 14.5% to 45.3%. The subsurface horizon i s regarded to be the surface horizon of a previously formed Humic Gleysol or Rego Gleysol. The present s o i l appears to have been formed by deposition of alluvium carried in during flooding and organic matter formed i n s i t u . The s o i l i s considered to be regosolic and to be evolving from a s o i l similar to that of the Caricetum rostratae. It i s classed as a buried s o i l . Texturally, the surface horizon varies from a sandy loam to a s i l t y loam. Sand and s i l t are most abundant s o i l particles and are mixed with pa r t i a l l y decomposed organic matter. No particles are present greater than 2 mm i n size. These results are only approximate because the organic matter content may interfere with the texture analysis. Texture was not analyzed for the sub-surface horizon because of the high organic matter content. The surface horizon has a circumneutral reaction with pH values ranging from 6.4 to 7.4. The subsurface horizon i s weakly alkaline with pH values in the range of 7.4. Exchangeable cations are present i n high amounts with calcium dominating the exchange complex. The high exchangeable calcium concentrations, Table 9 Soil Texture Carico - Salicetum monticolae Number of Plots Plot No. Surface Horizon Textural class Clay (%) S i l t (%) Sand (%) Coarse fragments Subsurface Horizon Textural class Clay (%) S i l t (%) Sand (%) Coarse fragments 1 2 3 127 128 126 L SL SL 23 10 13 42 38 34 35 52 53 SL SL SL 9 10 11 35 38 35 56 52 54 None 37 Table 10 Soil Chemical Analysis Carico - Salicetum monticolae Number of Plots 1 2 3 4 5 Plot No. 127 128 126 129 130 Surface Horizon C% 17.1 26.5 15.3 23.8 14.7 N% .84 1.07 .64 .87 .63 C/N 20.4 24.8 23.9 27.4 23.3 P ppm 23.0 28.0 14.0 9.0 17.0 Na .44 .54 .92 1.04 1.32 K .16 .24 .38 .34 .88 Ca 25.6 17.0 59.6 44.2 42.0 Mg 16.4 20.2 20.4 23.0 19.6 CEC 46.3 88.3 60.3 71.5 42.5 pH 7.1 6.4 6.4 6.5 6.6 Subsurface Horizon C% 40.7 37.8 N% 1.34 1.06 C/N 30.4 35.7 P ppm 36.0 16.0 Na 1.52 .36 K .46 .12 Ca 35.8 31.1 Mg 27.8 17.2 CEC 111.7 84.0 pH 7.6 7.2 45.3 21.0 14.5 .99 1.06 .21 45.8 19.8 21.4 18.0 18.0 7.0 .68 1.68 .82 .28 .76 .54 46.8 31.0 65.8 14.6 13.0 20.4 136.5 74.8 20.6 7.4 7.4 7.4 38 which increase with depth are thought to be due partly to the high s o l u b i l i t y of calcium salts and partly to the release of calcium from decomposing plant remains. Phosphorus occurs in relatively high concentrations and increases in concentration down the profil e as does the organic matter content. Because of the circumneutral s o i l reaction phosphorus i s readily soluble and available. The cation exchange capacity i s very high, because of the high amount of organic matter, and a maximum value of 136.5 meg/100 g was recorded i n the subsurface horizon. This habitat i s rated as permesotrophic. Nitrogen con-centrations are high and increase with depth. However, the carbon:nitrogen ratios are also high, especially i n the lower horizons. This indicates that the organic matter present contains insufficient nitrogen to satisfy the microflora requirements and thus a competition for nitrogen between microflora and higher plants may result. Aeration i s poor because these soi l s are water saturated. Under such conditions a reducing atmosphere exists and anaerobic decomposition i s favoured over aerobic decomposition which results in slow decomposition and an accumulation of organic matter. The odour of ammonia and hydrogen sulfide, both products of reduction from plant remains, was noticed to be present i n the subsurface horizons. Structurally, the vegetation of the Carico - Salicetum monticolae consists of four recognizable horizons. The C layer i s best developed with percentage cover ranging from 84% to 94%, followed by the B-^ layer which varies in cover from 48% to 58%. The B^ and D layers are less well developed with cover ranges of 18% to 24% and 26% to 45% respectively. The B^ layer i s dominated by Salix monticola which i s present with a constancy of Class V and an average species significance of 6.4. The only other species of this layer i s Salix arbusculoides which has an average species significance of 3.8. 39 The layer i s composed of Salix arbusculoides, Salix brachycarpa and Salix barclayi. The presence of woody plants i n a dominant role i n this association i s indicative of the elevated topographic position and semi-terrestrial s o i l s . The C layer i s dominated by Carex rostrata with an average species significance of 7.8 and Carex aquatilis with an average significance of 6.2. These species, which are characteristic of the Caricetum rostratae, are important companion species i n this association even though the habitat has been altered from their optimal one. The Carico - Salicetum monticolae habitat i s considered to be i n a state of flux; t e r r e s t r i a l enough to allow the establishment of Salix spp. but s t i l l aqueous enough to be within the amplitude of the aquatic Carex spp. Juncus balticus, a species characteristic of t e r r e s t r i a l subhygric to hygric sites i s present here as a constant non-dominant with an average species significance of 1.0. Calamagrostis canadensis occurs with a constancy of Class IV and i s believed to be present because of the weakly acidic to neutral reaction of the surface horizon. However, this habitat i s s t i l l within the amplitude of Calamagrostis neglecta (characteristic of the Caricetum rostratae) which i s a constant species here, with an average species significance of 4.6. Aster junciformis, and Galium trifidum because of their exclusive-ness for this association are considered as characteristic species. Drepanocladus aduncus with an average species significance of 6.0 i s the major species of the D layer. Rhynchostegiella compacta and Mnium rugicum are the only other important constituents of the D layer. These species occur mostly at the base of willow clumps where they are sl i g h t l y elevated above the s o i l surface. The Carico - Salicetum monticolae appears to have a history of slight grazing by cattle as well as browsing by native ungulates. The Sc i rpetum v a l i d i developed around the edges of an a l k a l i n e pond which i s formed i n a p o s t -g l a c i a l s t ream d e p r e s s i o n . S p a r t i n a g r a c i l i s dominates the foreground v e g e t a t i o n b o r d e r i n g the Sc i rpe tum v a l i d i . 41 Scirpetalia v a l i d i Scirpion v a i i d i Scirpetvim v a l i d i (ref. Tables; 11, 12, 13, 14, 83, and Fig. 5) Characteristic Combination of Species Order, Alliance and Association Characteristic Species Scirpus validus Chenopodium rubrum Ranunculus sceleratus Rumex maritimus The Scirpetalia i s considered to be closely related to the European Order Juncetalia maritimi L*Br. B l . 1939 (cited from Szafer 1966)] as both contain associations with similar habitat characteristics. One alliance and one association compose this Order i n the Cariboo Zone. The Scirpetum v a l i d i i s found i n alkaline ponds formed in shallow post-glacial stream depressions i n the upland areas (over 2900 f t elevation) of the Fraser Plateau. Some of the larger ponds have intermitent drainage outlets, however most have no visible inlets or outlets. Their water levels appear to be maintained mostly by runoff. These ponds appear stagnant and contain high concentrations of soluble salts. The Scirpetum v a l i d i develops around the edges of these ponds and remains submerged for most of the growing season. Only by late August has the water receded, due largely to evaporation, to expose the s o i l surface. However, water may s t i l l be extracted from the surface horizon by squeezing and free water persists in the subsurface horizon. Soil drainage i s regarded to be impeded. Therefore the habitat of this association i s considered to be hydric to sub-hydric. The surface topography i s f l a t and the exposure i s neutral. There i s no evidence of erosion; instead, because of the topographic position sedimentation i s probably taking place. ~~ 42 Table 11 Scirpetum v a l i d i Plot Data Number of Plots 1 2 3 4 5 Plot No. 116 118 117 119 120 Plot Size (m2) 100 100 100 100 100 Date analyzed 27/8 1968 28/8 1968 28/8 1968 29/8 1968 29/8 1968 Elevation (ft) 2900 2950 2970 3050 3500 Locality FP 51\u00C2\u00B046' 122\u00C2\u00B032' FP 51\u00C2\u00B046' 122\u00C2\u00B033' FP 51047' 122\u00C2\u00B032' FP 51\u00C2\u00B046' 122\u00C2\u00B035' FP 51\u00C2\u00B043' 122\u00C2\u00B047 Physiography Landform Relief shape Exposure Slope gradient (\u00C2\u00B0) f l a t .... ....neutral... 0 0 0 0 0 Layer coverage (%) C layer 96 4 94 6 96 11 80 3 92 6 Plot coverage (%) Humus and l i t t e r Water 91 100 96 100 96 100 89 100 92 100 Soil Hygrotope Trophotope Erosion Drainage Horizon depth (in) surface subsurface 0-12 12-24+ hydric to hygric . hypereutrophic . n i l impeded 0-13 13-24+ 0-16 16-25+ 0-15 15-26+ 0-12 12-26+ Parent material sediments Table 12 Scirpetum v a l i d i Number of P l o t s P l o t No. P l o t S i z e (m2) E l e v a t i o n (ft) C Layer 1 Scirpus v a l i d u s 2 Chenopodium rubrum 3 Rumex maritimus 4 Ranunculus s c e l e r a t u s 5 Hordeum jubatum D Layer 6 Drepanocladus aduncus 116 118 117 119 120 100 100 100 100 100 2900 2950 2970 3050 3500 9.6 9.7 9.7 8.5 9.5 3.2 3.2 2.2 4.3 3.3 5.3 2.2 3.3 2.2 2.2 2.1 1.1 2.1 - 2.2 + .+ - + \u00E2\u0080\u009E + 3.2 3.2 4.2 3.2 3.2 Constancy V V V IV II Avg Species S i g n i f i c a n c e 8.8 3.0 2.8 1.0 0.2 3.2 TOTAL SPECIES ( i n c l . sporadics) Sporadic species 7 Juncus b a l t i c u s 120(+.+) 8 Mentha arvensis var. g l a b r a t a 117(1.+) 9 Polygonum coccineum 116(2.+) 10 P o t e n t i l l a anserina 11 P u c c i n e l l i a a i r o i d e s 12 Tanacetum vulgare 118(1.+) 116 (+.+) 119(1.1) 44 The s o i l surface i s covered by a layer of dead Scirpus validus stems which form a floating mat during times of submergence. This material i s decomposed slowly and forms the major source of organic matter i n the s o i l . The s o i l consists of a dark surface horizon varying from 12 to 16 inches in thickness overlying a light coloured gleyed subsurface horizon. Measured carbon in the surface horizon varies from 4.6% to 27.1% with three plots containing more than 20% carbon. There i s no measureable carbon i n the subsurface horizon. Texturally, the surface horizon has a very low clay content while in the subsurface horizon clay i s the dominant textural fraction. The sampled subsurface horizons are classed as clays, s i l t y clay loams and clay loams. No particles greater than 2 mm in size were found i n either horizon. Because of the high content of fine material, the parent material i s considered to be formed from pond sediments. However, the textural difference between the two horizons suggests that the s o i l i s evolving through deposition. Wind blown s i l t s from the surrounding upland mixed with organic matter form the surface'horizon. These soils are expected to eventually become t e r r e s t r i a l . The s o i l reaction i s alkaline with pH values ranging from 7.6 to 7.9 in the surface horizon and from 8.0 to 8.1 in the subsurface. Magnesium i s available in greater amounts than calcium i n both horizons possibly because magnesium rich rocks were the original s o i l source and because the higher clay content of these soils results in magnesium being extracted from the clay l a t t i c e . The exchangeable cations are present i n substantially higher amounts in the surface horizon than i n the subsurface horizon due to secondary deposi-tion and capillary rise of dissolved salts of exchangeable bases during periods when the s o i l surface i s exposed to evaporation. The high calcium and magnesium values coupled with a high cation exchange capacity indicate that these soils are very rich and the habitat i s therefore considered to be Number of Plots Plot No. Surface Horizon Textural class Clay (%) S i l t (%) Sand (%) Coarse fragment Subsurface Horizon Textural class Clay (%) S i l t (%) Sand (%) Coarse fragment Table 13 Soil Texture Scirpetum v a l i d i 1 2 3 4 5 116 118 117 119 120 SL L L SL SiL 1 16 14 20 3 44 50 48 17 52 55 35 38 64 45 CL C L SiC CL 30 67 24 47 34 42 17 45 43 36 28 14 31 10 30 None cn 46 Table 14 Soil Chemical Analysis Scirpetum v a l i d i Number of Plots Plot No. 1 116 2 118 3 117 4 119 5 120 Surface Horizon C% 27.1 24.7 22.0 4.6 13.4 N% 1.08 1.34 .92 .15 .64 C/N 25.1 16.2 23.9 30.6 20.9 P ppm 24.0 16.0 19.0 9.0 21.0 Na 1.8 1.15 1.58 .68 .91 K .64 .53 .88 .89 .67 Ca 27.6 13.4 23.8 11.2 17.1 Mg 36.4 16.7 24.0 19.3 21.4 CEC 96.4 82.6 96.4 33.8 42.6 pH 7.6 7.8 7.6 7.8 7.9 Subsurface Horizon C% 0 0 N% .10 .08 C/N 0 0 P ppm 7.0 8.0 Na .41 .40 K .75 .21 Ca 9.6 9.6 Mg 15.1 14.4 CEC 18.3 16.9 pH 8.0 8.0 0 9. 9 14 18 8 .08 .0 .48 .37 .1 .4 .3 .1 0 .11 0 3.0 .64 .55 11.2 16.2 16.1 8.1 .08 0 10.Q .97 .81 9.1 13.2 22.9 8.0 47 hypereutrophic. Nitrogen may possibly be a limiting factor, as i t i s present in the subsurface horizon only as traces (.08% to 0.1%). There i s more nitrogen in the surface horizon but the relatively high carbon:nitrogen ratios suggest that most of i t i s unavailable to higher plants. The soil s are also poorly aerated because of their water-logged conditions. The low available nitrogen and poor aeration suggests that decomposition occurs slowly which accounts for the organic matter accumulation. These soils are classed i n the Gleysolic Order as either Orthic Humic Gleysols, i f the organic matter content of the surface horizon i s less than 30%, or as Rego Gleysols i f the organic matter content of the surface horizon i s greater than 30%. The Scirpetum v a l i d i i s f l o r i s t i c a l l y simple. Most of the C layer coverage i s contributed by Scirpus validus which dominates the association with an average species significance of 8.8. Chenopodium rubrum and Rumex maritimus are constantly present beneath the Scirpus validus cover. Ranunculus sceleratus i s the only other vascular plant occurring with regularity. Several species, including Hordeum jubatum, Juncus balticus, Potentilla anserina and Puccinellia airoides occur sporadically at the drier edges of the habitat. A l l plants present here can tolerate alkaline conditions and are capable of growing submerged. Only one bryophyte, Drepanocladus aduncus, occurred with measureable cover. This species was most common i n cattle hoof prints in parts of the association longest released from submergence. Scirpus validus i s also present in a truly aquatic community of the large fresh water lakes in the region. This community, however, was not studied. 48 Puccinellietalia airoidis Distichlion strictae The order Puccinellietalia airoidis i s proposed for the inclusion of t e r r e s t r i a l alkaline-saline associations which have characteristically solonetzic s o i l s . It i s related to the European Puccinellio - Salicornietalia (Br.-Bl. -de Leeuv 1936) but i s distinguished by higher sodium:calcium ratios. The Puccinellietalia airoidis i s represented in the Cariboo Zone by one alliance, the Distichlion strictae. This alliance i s formed in depressions or on the edges of alkaline ponds in the upland area of the Fraser Plateau. The habitats are strongly alkaline with high salt concentrations and are frequently flooded. The Distichlion strictae i s characterized by Puccinellia airoides, Hordeum jubatum, Spartina g r a c i l i s , D i s t i c h l i s s t r i c t a and Carex praegracilis. The D i s t i c h l i s association described by Daubenmire (1942) in central Washington would most like l y be placed in this alliance. Two associations are recognized in this a l l i a n c e \u00E2\u0080\u0094 t h e Puccinellio-Hordeetum jubati and the Distichlo - Spartinetum g r a c i l i s . They are distinguished, f l o r i s t i c a l l y , largely on the basis of dominance of the major characteristic and constant species. 1. Puccinellio (airoidis) - Hordeetum jubati (ref. Tables,- 15, 16, 17, 18, 83 and Fig. 6) Characteristic Combination of Species Order and Alliance Characteristic Species Aster pansus Carex praegracilis D i s t i c h l i s s t r i c t a Hordeum jubatum Puccinellia airoides Spartina g r a c i l i s Association Characteristic Species Eleocharis palustris Elymus glaucus Ranunculus cymbalaria Triglochin palustris 49 Important Companion Species Juncus balticus Potentilla pennsylvanica The Puccinellio - Hordeetum jubati occurs on the edges of alkaline ponds or i n drainage pathways. The surface topography i s f l a t and the expo-sure i s neutral. This association i s flooded i n the spring, but the water level i s well below the s o i l surface for most of the growing season and by late summer free water i s not found anywhere i n the p r o f i l e . However, the B horizon remains moist and water can be extracted from the C horizon by squeezing. The hygrotope of this habitat varies from hydric i n the spring to hygric for the remainder of the season. There i s no evidence of erosion i n this association. Based on the topographic position and s o i l texture the drainage i s regarded as impeded to imperfect. Much of the water loss from the s o i l i s probably accomplished through evapo-transpiration. The s o i l surface i s covered by a thin layer of l i t t e r but some mineral s o i l was exposed i n a l l communities studied (6 to 12%). The s o i l has an A, B, C, horizon sequence formed on a parent material of sediments. The C and B horizons are strongly gleyed and a few mottles are present i n the A horizon as well. With the exception of plots 123 and 124 organic matter accumulation i s present in the A horizon and to a lesser extent also i n the B horizon. In plots 123 and 124 there was no measureable evidence of melanization Texturally the s o i l i s composed of sand, s i l t and clay size particles except for plot 124 where a few gravels were also found in the B and C horizons. There i s apparent eluviation of clay from the A horizon resulting in an accumulation of clay i n the B horizon. Measured clay in the B ranges from 24% to 61%. Sampled B horizons are classed texturally as clay loams to clays. The corresponding C horizons are s i l t loams to clay loams. Table 15 Puccinellio (airoidis) - Hordeetum jubati Plot Data Number of Plots 1 2 3 4 5 Plot No. 122 121 123 124 125 Plot Size (m2) 100 100 100 100 100 Date analyzed 29/8 28/8 29/8 30/8 30/8 1968 1968 1968 1968 1968 Elevation (ft) 2950 2980 3000 3440 3440 Locality FP FP FP FP FP 51\u00C2\u00B046' 51\u00C2\u00B046' 41\u00C2\u00B047' 51\u00C2\u00B045' 51\u00C2\u00B045' 122\u00C2\u00B031' 122\u00C2\u00B034' 122\u00C2\u00B032' 122o40' 122\u00C2\u00B040' Physiography Landform drainage drainage path ...... edge of pond path 2R,@!L 3 . 6 f S help 6 \u00C2\u00AB \u00C2\u00AB o \u00C2\u00AB \u00E2\u0082\u00AC 6 c c \u00C2\u00AB c o o o \u00C2\u00AB \u00C2\u00AB a \u00C2\u00AB 4 c e o f Id t \u00E2\u0080\u00A2\u00C2\u00AB\u00E2\u0080\u00A2>*\u00E2\u0080\u00A2\u00E2\u0080\u00A2\u00E2\u0080\u00A2\u00E2\u0080\u00A2\u00E2\u0080\u00A2\u00E2\u0080\u00A2\u00E2\u0080\u00A2\u00E2\u0080\u00A2\u00E2\u0080\u00A2\u00E2\u0080\u00A2\u00E2\u0080\u00A2\u00E2\u0080\u00A2\u00E2\u0080\u00A2\u00C2\u00AB\u00E2\u0080\u00A2\u00E2\u0080\u00A2 Exposure neutral Slope gradient (\u00C2\u00B0) 0 0 0 0 0 Layer coverage (%) C layer 88 92 86 86 85 D layer 28 46 18 14 10 Plot coverage (%) Humus and l i t t e r 92 94 88 92 94 Mineral s o i l 8 6 12 8 6 Soil Hygrotope ............... hydric to hygric Trophotope hypereutrophic Erosion n i l Drainage impeded Horizon depth (in) A 0-5 0-3 0-4 0-5 0-4 B 5-11 3-12 4-12 5-11 4-11 C 11^ -22+ 12-22+ 12-22+ 11-24+ 11-25+ Parent material sediments 51 Table 16 P u c c i n e l l i o ( a i r o i d i s ) - Hordeetum j u b a t i Number of Plots 1 2 3 4 5 Plot No. 122 121 123 124 125 Plot Size (m2) 100 100 100 100 100 Elevation (ft) 2950 2980 3000 3440 3440 Avg Species C Layer Constancy S i g n i f i c a n c e 1 Hordeum jubatum 8.4 7.3 7.4 8.3 7.3 V 7.4 2 P u c c i n e l l i a a i r o i d e s 3.2 4.2 5.2 4.2 3.2 V 4.8 3 Carex p r a e g r a c i l i s 3.3 4.2 3.2 5.4 5.3 V 4.0 4 Aster pansus 2.1 4.1 2.1 4.1 4.1 V 3.2 5 Spartina g r a c i l i s 3.1 + .+ 3.1 4.2 4.2 V 2.9 6 D i s t i c h l i s s t r i c t a 3.+ + .+ 2.1 3.1 3.1 V 2.3 7 Ranunculus cymbalaria 2.2 3.2 2.2 2.2 2.2 V 2.2 8 P o t e n t i l l a pennsylvanica 1.1 1.1 1.+ 2.2 3.2 V 1.6 9 Juncus b a l t i c u s 4.1 5.3 3.2 4.2 - IV 3.2 10 Eleocharis p a l u s t r i s 3.1 +. + 2.1 - 1.1 IV 1.3 11 Elymus glaucus - 3.1 - 2.1 3.2 III 1.6 12 T r i g l o c h i n p a l u s t r i s - + .+ 1.+ - 2.+ III 0.7 13 Carex p r a t i c o l a 1.1 - - 1.1 1.1 III 0.6 14 Scirpus validus 1.+ 1.+ - - - II 0.4 D Layer 15 Drepanocladus aduncus 6.3 6.2 4.2 5.2 4.2 V 5.0 TOTAL SPECIES ( i n c l . sporadics) 14 15 14 15 12 Sporadic species 16 Agropyron spicatum 123(+.+) 17 Calamagrostis neglecta 121(2.+) 18 Elymus hirsutws 123(4.2) 19 Poa j u n c i f o l i a 124(+.+) 20 Poa l o n g i l i g u l a 122(2.+) 21 Poa pratensis 124(1.+) 22 T r i g l o c h i n maritima 124(2.+) 52 The s o i l reaction i s strongly alkaline i n a l l horizons because of the accumulation of basic cations and clay resulting from deposition coupled with the imperfect drainage. Measured pH values range from 7.8 to 8.9. Exchangeable calcium and magnesium are present in very high amounts with magnesium being substantially higher than calcium. This suggests that a magnesium rich parent rock was the source of the s o i l . Although the high amounts of available magnesium may be caused by the high clay accumulation, as magnesium i s an important constituent of the clay l a t t i c e . Total nitrogen measured i s low and decreases to only trace amounts in the C horizon. However, the carbon:nitrogen ratio of the A and B horizons i s also low, indicating that sufficient nitrogen i s present to satisfy the requirements of the microbial population of the s o i l . This together with the fact that s o i l aeration i s adequate throughout most of the growing season w i l l ensure active aerobic decomposition thus maintaining a nutritionally rich habitat. Exchangeable sodium i s high, particularly in the A horizon (concentrations of up to 6.8 meq/100 g were measured) which may cause some inhibition to plant growth. A thin layer of crusted salts i s present on the s o i l surface of most communities by late summer. This results from capillary rise and eva-poration of ground water. Although s o i l s a l i n i t y was not measured, i t i s probable that the A horizons of these soils contain a high concentration of salts which w i l l limit extensively the flora capable of growing in this habitat. The high concentrations of exchangeable cations in the A horizon, relative to the lower horizons, suggests that there are soluble salts composed of the measured bases present. The high cation exchange capacity and large amounts of exchangeable bases indicate that this habitat i s nutritionally very r i c h . However, the strong salt concentrations may limit the a v a i l a b i l i t y of these ions through the creation of unfavourable osmotic pressures. The trophotbpe of this ' Table 17 Soil Texture Puccinellio (airoidis) - Hordeetum jubati Number of Plots 1 2 3 4 5 Plot No. 122 121 123 124 125 A Horizon Textural class Clay (%) S i l t (%) Sand (%) Coarse fragments B Horizon Textural class Clay (%) S i l t (%) Sand (%) Coarse fragments C Horizon Textural class Clay (%) S i l t (%) Sand (%) Coarse fragments SiL 4 58. 38 CL 34 42 24 None SiL 25 52 23 None SiL 13 54 33 Data not avail-able None CL 31 42 27 None CL 29 39 32 None C 61 29 10 None CL 39 30 31 None CL 36 28 36 C 60 28 12 g-SiCL 34 48 18 g-CL 25 46 30 SiL 24 54 22 None L 22 48 30 None 54 Table 18 Soil Chemical Analysis Puccinellio (airoidis) - Hordeetum jubati Number of Plots 1 2 3 4 5 Plot No. 122 121 123 124 125 A Horizon C% 10.1 12.8 0 0 14.0 N% .63 .68 .07 .12 .61 C/N 16.0 18.8 0 0 22.9 P ppm 18.0 14.0 5.0 5.0 14.0 Na .59 1.06 2.9 4.9 6.9 K .52 .63 9.4 1.67 1.23 Ca 8.5 6.6 5.5 1.28 5.5 Mg 18.3 24.4 41.0 5.3 21.1 CEC 88.1 36.5 17.3 13.2 43.5 pH 7.9 8.5 7.8 8.9 8.5 B Horizon C% N% C/N P ppm Na K Ca Mg CEC pH 6.3 .26 24.2 8.0 1.30 .54 8.1 18.2 27.5 8.2 0 .06 0 8.0 .48 .13 13.1 12.5 17.3 8.1 0 9. 6 20 13 8 .06 0 87 64 5 3 5 1 7.5 .41 18.3 8.0 7.10 .92 8.1 15.6 42.6 8.5 C Horizon C% 0 0 0 0 6.1 N% .08 .08 .06 .08 .28 C/N 0 0 0 0 21.8 P ppm 4.0 6.0 6.0 6.0 4.0 Na 1.39 .38 .41 .76 5.7 K .48 .27 .14 .57 .83 Ca 9.3 8.4 14.7 10.5 8.3 Mg 17.8 19.0 15.2 15.9 14.5 CEC 3.8 13.7 12.2 23.1 26.8 pH 8.1 8.5 7.8 8.4 8.5 55 habitat i s considered to be hypereutrophic. Because of the high pH, clay accumulation and s a l t concentrations, the soi l s are placed i n the Solonetz Great Group and potentially into the Brown Solonetz Subgroup. However, because of their weak solonetzic charac-t e r i s t i c s they are recognized to intergrade towards the Chernozemic Order and might well be placed as Gleyed Solonetzic Dark Brown Chernozems. Structurally this association i s simple, having only two layers of vegetation, a well developed C layer and a poorly developed D layer. The C layer has a percentage cover of 86% to 92% while the D varies in cover from 10% to 46%. The Puccinellio - Hordeetum jubati i s dominated by Hordeum jubatum which i s constantly present with an average species significance of 7.4. Puccinellia airoides and Carex praegracilis are constant co-dominants with lower species significances, 4.8 and 4.0 respectively. Aster pansus, Spartina g r a c i l i s , D i s t i c h l i s s t r i c t a , and Ranunculus cymbalaria are present as constant non-dominants. Potentilla pennsylvanica occurs with low significance but increases in importance in drier communities of the association. Eleocharis palustris, Elymus glaucus and Triglochin palustris, although recorded only as non-constants, are considered as characteristic species because of their preference for this association. Eleocharis palustris, Triglochin palustris and Ranunculus cymbalaria together with Juncus balticus are good indicators of the hydric to hygric conditions. The D layer i s composed largely of one species, Drepanocladus aduncus, which occurs with a Constance of class V and an average species significance of 5.0. The regularly occurring species form a characteristic flora which i s capable of tolerating a hygrotope varying from submergence to par t i a l desiccation as well as extremely alkaline conditions with high concentrations 56 Fig. 6. The Puccinellio - Hordeetum jubati shown here bordering the Scirpetum v a l i d i . Hordeum jubatum forms almost closed stands i n this association. Fig. 7. The Distichlo - Spartinetum g r a c i l i s showing the characteristic dominance of Spartina g r a c i l i s and the sporadic occurrence of Hordeum jubatum. The Scirpetum . v a l i d i can be seen in the upper l e f t and the lighter coloured slope at the top of the picture i s dominated by the Antennario - Poetum secundae. 57 of soluble salts. Species like Agropyron spicatum, Calamagrostis neglecta and Poa pratensis which are less tolerant of these conditions occur only sporadically. The Puccinellio - Hordeetum jubati appears to have a history of only slight grazing, the effects of which are noticeable by the disturbance of the s o i l surface. 2. Distichlo (strictae) - Spartinetum g r a c i l i s (ref. Tables; 19, 20, 21, 22, 83, and Fig. 7) Characteristic Combination of Species Order and Alliance Characteristic Species Aster pansus Carex praegracilis D i s t i c h l i s s t r i c t a Hordeum jubatum Puccinellia airoides Spartina g r a c i l i s Association Characteristic Species Agropyron trachycaulum Atriplex truncata Grindelia squarrosa Polygonum aviculare Suaeda depressa Important Companion Species Juncus balticus Poa j u n c i f o l i a The Distichlo - Spartinetum g r a c i l i s i s found on three related landforms\u00E2\u0080\u0094old pond bottoms, drainage pathways and edges of alkaline ponds. The surface topography i s either f l a t or very gently sloping and the exposure i s neutral. Measured slope gradients vary from 2\u00C2\u00B0 to 5\u00C2\u00B0. Communities of the Distichlo - Spartinetum g r a c i l i s occurring in the pond bottom depressions and the drainage pathways are flooded for short periods in the spring. Those on slopes above the alkaline ponds are rarely submerged but probably benefit from seepage temporarily. S o i l drainage i s 58 Table 19 Distichlo (strictae) - Spartinetum g r a c i l i s 1 - 2 3 4 5 6 052 053 081 080 048 049 100 100 100 100 100 100 19/8 19/8 18/7 18/7 11/8 11/8 1967 1967 1968 1968 1967 1967 2930 2930 2970 3000 3050 3090 FP FP FP FP FP FP 51\u00C2\u00B050' 51\u00C2\u00B050' 51\u00C2\u00B046' 51\u00C2\u00B047' 51\u00C2\u00B047' 51\u00C2\u00B047' 122\u00C2\u00B030' 122\u00C2\u00B030\" 122\u00C2\u00B031' 122\u00C2\u00B032' 122\u00C2\u00B033' 122\u00C2\u00B034 Plot Data Number of Plots Plot No. Plot Size (m2) Date analyzed Elevation (ft) Locality Physiography Landform old pond bot- drainage edge of drainage ..torn depression.. path pond path Relief shape straight f l a t f l a t straight straight f l a t Exposure SE neutral neutral NE SW neutral Slope gradient 2 0 0 3 5 0 Layer coverage (%) C layer 84 88 84 82 67 82 D layer 0 0 0 0 3 3 Plot coverage (%) Humus and l i t t e r 90 97 90 88 79 86 Mineral s o i l 10 3 10 12 21 14 Soil Hygrotope subhygric - (hydric) Trophotope hypereutrophic Erosion n i l n i l n i l . slight n i l n i l water Drainage imperfect moderate moder- moderate ate to well Horizon depth (in) A 0-7 0-8 0-6 0-7 0-8 0-6 B 7-16 8-16 6-13 7-14 8-24 6-16 C 16-30+ 16-28+ 13-24+ 14-26+ 24-39+ 16-35+ Parent material shallow sediments shallow sediments over gla c i a l . ... over glacial d r i f t .... dr i f t ? 59 Table 20 Distichl o ( s t r i c t a e ) - Spartinetum g r a c i l i s Number of Plots 1 2 3 4 5 6 Plot No. 52 53 81 80 48 49 Plot Size (m2) 100 100 100 100 100 100 Elevation (ft) 2930 2930 2970 3000 3050 3090 Avg Species C Layer Constancy Significance 1 Spartina g r a c i l i s 8.6 8.5 8.3 8.3 7.4 7.5 V 7.7 2 Aster pansus 5.5 6.4 4.2 4.2 3.2 5.3 V 4.5 3 D i s t i c h l i s s t r i c t a 4.3 3.2 3.1 4.1 5.2 6.4 V 4.2 4 Poa j u n c i f o l i a 4.2 2.2 4.1 3.1 3.1 1.1 V 2.8 5 Carex praegracilis 3.2 4.3 3.1 3.2 2.1 - V 2.5 6 Hordeum jubatum 2.2 1.2 2.1 2.1 - 1.1 V 1.3 7 P u c c i n e l l i a airoides 2.2 1.2 3.1 1.+ - - IV 1.2 8 Agropyron trachycaulum + .+ 2.2 - 2.+ - 1.1 IV 0.9 9 Comandra umbellata - + .+ - 1.+ +.+ 1.1 IV 0.5 10 Juncus balticus 3.2 4.3 - 2.1 - - III 1.5 11 Suaeda depressa 2.1 2.1 4.2 - - - III 1.3 12 Antennaria umbrinella - - - 2.2 1.+ 2.1 III 0.8 13 Artemisia f r i g i d a - - - 1.+ 3.1 + .+ III 0.8 14 Lepidium densiflorum - - 1.+ 2.+ 2.+ - III 0.8 15 Taraxacum o f f i c i n a l e - - - 1.+ 1.+ +.+ III 0.3 16 G r i n d e l l i a squarrosa 3.1 - - - 2.+ - II 0.8 17 Polygonum aviculare - - - - 3.1 2.1 II 0.8 18 Chenopodium leptophyllum - - 2.+ 2.+ - - II 0.7 19 Erigeron acr i s - - 2.+ 1.+ - - II 0.5 20 Orthocarpus hispidus - - - - 2.+ 1.+ II 0.5 21 Poa secunda - - 2.1 1.1 - - II 0.5 22 Antennaria dimorpha - - - - 1.+ 2.1 II 0.3 23 Atriplex truncata - - - - 1.+ 1.+ II 0.3 24 Koeleria g r a c i l i s - - - - 1.1 1.+ II 0.3 D Layer (Lichens) 25 Cladonia pocillum - - - - 3.+ 3.1 II 1.0 TOTAL SPECIES(incl.sporadics) 14 13 15 18 18 17 Sporadic species 26 Agoseris glauca 053(+.+) 27 Carex pr a t i c o l a 052(1.1) 28 Chenopodium freemontii 081(1.2) 29 Elymus glaucus 052(2.2) 30 Erigeron speciosus 048(+.+) 31 Poa pratensis 080(3.1) 32 P o t e n t i l l a pennsylvanica 08K+. + ) 33 Ranunculus cymbalaria 081(2.1) 34 Smilacina s t e l l a t a 053(2.+) 35 Salicornia rubra 052(1.1) 36 Viola adunca 049(2.1) 60 classed as moderate to imperfect. Runoff i s light and was observed to cause slight water erosion in only one plot. The hygrotope varies from hydric for a short time in the spring to subhygric for most of the growing season. The s o i l surface i s covered by a thin l i t t e r layer varying i n extent from 79% to 97% of the surface area. In a l l communities studied exposed mineral s o i l was present. The s o i l i s formed from a parent material of sediments overlying g l a c i a l d r i f t . In plots 048 and 049 however, the finer material may be of aeolian origin rather than sediments. Three distinct horizons are recognizable in the p r o f i l e . The A horizon which i s dark brown contains an accumulation of organic matter with measured carbon ranging from 3.8% to 24.8%. It i s six to eight inches in thickness and contains no coarse fragments. Texturally the sampled A horizons range from s i l t loams to sandy loams. Underlying the A i s a lighter coloured B horizon. Some organic staining i s evident here although carbon i n measureable amounts, was recorded only in plot 081. Clay accumulation was present i n three of the sampled communities. S i l t and sand sized particles are the most abundant and the textural classes range from s i l t loams to loamy sands. Coarse fragments of gravel size were present in a l l samples. The C horizon i s present at a depth of 13 to 24 inches and has a high accumulation of carbonates as revealed by a strong effervescense with hydrochloric acid. Sampled C horizons range from sandy loams to sandy clays. Coarse fragments ranging i n size from gravels to stones were present in a l l samples. There are a few mottles present i n the C horizon which i s indicative of the restricted drainage. The s o i l reaction i s alkaline in a l l horizons and measured pH values range from 7.8 to 8.4. The cation exchange capacity and the concentrations of the exchangeable cations are very high indicating that the habitat i s nutritionally r i c h . Cation concentrations are highest near the surface and 61 decrease with depth. Magnesium i s present in higher amounts than i s calcium, suggesting a magnesium rich parent source of the s o i l . Concentrations of exchangeable sodium are very high in this association particularly in the A horizon where sodium concentrations of up to 27 meg/100 g were measured. This high sodium level may interfere with the exchange complex and limit plant growth. Nitrogen i s present in low amounts i n the A horizon and decreases through the B horizon to just trace amounts in the C horizon. The carbon: nitrogen ratios are highest i n the A horizon and decreases with depth indicating that nitrogen competition between the microflora and higher plants may occur near the surface. A study of the plant root distribution shows the roots to be massed i n the A horizon; only a few reach as low as the C horizon. Thus the edaphic conditions of the A horizon appear to have the greatest effect on growth of plants. The Distichlo - Spartinetum g r a c i l i s i s judged as hypereutrophic because of the medium texture of the s o i l , basic s o i l reaction and high accumulation of cations. A white salt crust probably resulting from capillary rise and evaporation of ground water containing soluble salts, was observed on the surface of four communities studied (052, 053, 081, 049). However, a second possible source of this salt crust i s from salts deposited in solution during times of flooding. These would remain at or near the surface because i n these habitats the effect of evapo-transpiration i s greater than that of leaching. The salt layer of plot 052 was analyzed and found to contain 245 meg/100 g of sodium, 250 meg/100 g of magnesium, 28 meg/100 g of calcium and 4.68 meg/100 g of potassium. This suggests that the salts present are largely those of sodium and magnesium. Number of Plots Plot No. A Horizon Textural class Clay (%) S i l t (%) Sand (%) Coarse fragments B Horizon Textural class Clay (%) S i l t (%) Sand (%) Coarse fragments C Horizon Textural class Clay (%) S i l t (%) Sand (%) Coarse fragments Table 21 Soil Texture Distichlo (strictae) - Spartinetum g r a c i l i s 1 2 3 4 5 6 052 053 081 080 048 049 SiL SL SiL LS SL SL 7 9 12 3 8 5 52 42 51 18 47 49 41 49 37 79 45 46 None L 21 48 31 g-L 23 33 44 g. LS 2 26 72 g. SiL 14 51 35 g-SiL 0 59 41 g-SiL 1 61 38 g-CL 33 27 40 g.c.s. L 24 26 50 g.c, CL 33 31 36 g.c. SCL 27 23 50 g.c. SL 3 47 50 g.c.s, SL 1 48 51 g.c. to 63 Table 22 Soil Chemical /Analysis Distichlo (strictae) - Spartinetum g r a c i l i s Number of Plots 1 2 3 4 5 6 Plot No. 052 053 081 080 048 049 A Horizon C% 14.7 24.8 11.3 3.8 9.5 8.9 N% .78 .97 .46 .18 .23 .41 C/N 18.8 25.6 24.6 21.1 41.3 21.7 P ppm 16.0 16.0 23.0 9.0 13.0 16.0 Na 8.43 10.95 27.2 7.3 1.20 13.47 K 1.79 1.41 2.51 1.56 2.56 2.31 Ca 4.0 8.3 7.0 5.8 5.5 16.8 Mg 31.7 34.2 20.1 19.2 10.6 38.3 CEC 61.7 69.3 62.3 24.3 52.3 52.4 pH 8.0 8.2 8.2 8.4 7.8 7.8 B Horizon c% 0 0 4.7 0 0 0 N% .11 .03 .16 .12 .61 .10 C/N 0 0 29.4 0 0 0 P ppm 4.0 3.0 17.0 12.0 7.0 6.0 Na 8.61 1.76 4.0 1.01 7.39 2.06 K .83 .51 1.63 .3 1.73 1.47 Ca 5.5 7.5 8.4 8.5 7.8 11.6 Mg 21.7 11.8 16.0 13.5 28.3 44.8 CEC 12.1 12.0 26.8 21.4 21.4 24.3 PH 8.3 8.2 8.1 8.4 8.3 8.0 C Horizon C% 0 0 0 0 0 0 N% .08 .06 .21 .04 .07 .10 C/N 0 0 0 0 0 0 P ppm 4.0 5.0 5.0 4.0 5.0 5.0 Na 2.17 2.18 1.38 .98 8.96 2.17 K 1.60 .18 .36 .39 1.67 1.60 Ca 8.5 10.0 7.3 4.3 7.5 10.3 Mg 13.0 11.5 15.6 15.5 12.8 13.0 CEC 14.3 9.9 12.9 11.7 24.7 14.3 pH 8.3 8.3 8.1 8.2 8.3 8.3 64 Because of the capillary rise of ground water, the A horizon i s also expected to contain strong concentrations of soluble salts. The higher concentrations of sodium as compared to calcium i n both the A horizon and the salt crust, indicates that the s o i l i s of a sodic nature. This i s supported by the presence of Suaeda depressa which is characteristic of sodic soils and by the only sporadic occurrence of Salicornia rubra which i s more characteristic of alkaline-calcic s o i l s . The soi l s of the Distichlo - Spartinetum g r a c i l i s are classed in the Solonetz Great Group and tentatively into the Brown Solonetzic Subgroup of the Canadian s o i l c l a s s i f i c a t i o n scheme. However, because of their relatively weak solonetzic characteristics they are thought to grade strongly toward the Chernozemic Order where they would be classed as Dark Brown Solonetzic Chernozems. The Distichlo - Spartinetum g r a c i l i s i s dominated by Spartina g r a c i l i s which i s constantly present with an average species significance of 7.7. Aster pansus and Di s t i c h l i s s t r i c t a are constant co-dominants with average species significances of 4.5 and 4.2 respectively. A l l three of these species are indicators of alkaline habitats. The remaining constant species are: Carex praegracilis, Poa j u n c i f o l i a , and Hordeum jubatum. Puccinellia airoides and Juncus balticus are important non-constants which are probably established because of the alkaline, hygric conditions. Atriplex truncata, Suaeda depressa, Grindelia squarrosa, and Polygonum aviculare, although present with low constancy, are considered as characteristic because of their exclusiveness to this association. Orthocarpus hispidus, Poa secunda, Antennaria dimorpha, and Koeleria g r a c i l i s occur in the drier parts of the association. The bryophyte and lichen occurrence i n this association i s almost negligible. Only one species, Cladonia pocillum was recorded. The apparent absence of bryophytes i s probably due to the strong concentrations of salts on The Muhlenbergio - Betuletum glandulosae showing the characteristic hummocky surface topography formed by the clumps of Betula glandulosa. Muhlenbergia richardsonis i s the dominant species between the hummocks. Young trees of Picea glauca are common in this association suggesting a successional advancement to forest. 66 the s o i l surface. This association appears to have a history of only moderate grazing. Betuletalia glandulosae Muhlenbergio (richardsonis) - Betulion glandulosae Muhlenbergio (richardsonis) - Betuletum glandulosae (ref. Tables; 23, 24, 25, 26, 83, and Fig. 8) Characteristic Combination of Species Order, Alliance, and Association Characteristic Species Betula glandulosa c Salix brachycarpa Erigeron acris Muhlenbergia richardsonis Sisyrinchium sarmentosum Cladonia cariosa Important Companion Species Arctostaphylos uva-ursi Carex praegracilis Aster pansus Juncus balticus Poa juncifolia Hordeum jubatum Potentilla anserina Koeleria g r a c i l i s Aster campestris Carex concinna Rosa acicularis Antennaria anaphaloides The Order Betuletalia glandulosae i s considered characteristic of subalpine and subarctic regions where i t was previously described by Lambert (1968). In the Cariboo Zone, this Order i s represented by a single alliance and a single association. The Muhlenbergio - Betuletum glandulosae i s an association of restricted distribution on the Fraser Plateau. It develops at elevations greater than 3000 feet above sea lev e l , in depressions, at the base of exposed 67 Table 23 Muhlenbergio (richardsonis) - Betuletum glandulosae Plot Data Number of Plots 1 2 3 4 5 Plot No. 135 131 134 133 132 Plot Size (m2) 100 100 100 100 100 Date analyzed 10/9 6/9 10/9 9/9 6/9 1968 1968 1968 1968 1968 Elevation (ft) 3050 3100 3100 3200 3400 Locality FP FP FP FP FP 51\u00C2\u00B043' 51\u00C2\u00B044' 51\u00C2\u00B044' 51\u00C2\u00B044' 51\u00C2\u00B044' 122037' 122\u00C2\u00B048' 122\u00C2\u00B038* 122\u00C2\u00B051' 122\u00C2\u00B050 Physiography Landform i o e \u00C2\u00AB s \u00C2\u00AB e c * \u00C2\u00AB depression Relief shape ........ > e o \u00C2\u00AB e * c * o o hummocky Exposure ........ .. neutral Slope gradient (\u00C2\u00B0) 0 0 0 0 0 Layer coverage (%) A3 layer - 4 - -B\ layer 6 - 0 2 B2 layer 56 48 52 68 44 C layer 82 86 88 74 82 D layer 18 18 14 12 8 Plot coverage (%) Humus and l i t t e r 94 92 92 92 94 Mineral s o i l 4 6 6 . 6 4 Soil Hygrotope (hydric) - hygric - (subhygric) . eutrophic Erosion n i l Drainage Horizon depth (in) A 0-6 0-6 0-5 0-7 0-4 B 6-14 6-12 5-8 7-10 4-16 C 14-25+ 12-20+ 8-22+ 10-25+ 16-24+ Parent material alluvium Table 24 Muhlenbergio (richardsonis) - Betuletum glandulosae Number of Plots 1 2 3 4 5 Plot No. 135 131 134 133 132 plot Size (m2) 100 100 100 100 100 Elevation (ft) 3050 3100 3100 3200 3400 sub Avg Species A Layer laver Constancy Significance 1 Picea glauca 3 - i.+ - - - III 0.6 B Laver Picea glauca 1 - 2.+ - - 3.+ 1.0 2 Betula glandulosa 2 6.3 7-3 7.3 8.4 7.3 V 7.0 3 S a l i x brachycarpa 2 3.3 2.1 3.3 2.1 2.1 V 2.4 C Laver 4 Muhlenbergia richardsonis 7.4 7.4 7.4 7.4 8.4 V 7.2 5 Arctostaphylos uva-ursi 5.3 5.3 3.2 4.2 5.3 V 4.4 S a l i x brachycarpa 4.3 4.2 5.3 4.2 5.3 4.4 6 Carex p r a e g r a c i l i s 5.3 2.2 3.2 2.1 4.3 V 3.2 7 Juncus b a l t i c u s 3.2 3.2 3.2 2.1 4.2 V 3.0 8 Aster pansus 3.2 2.+ 3.1 3.1 3.1 V 2.8 9 Koeleria g r a c i l i s 3.2 1.1 3.1 3.2 2.1 V 2.4 10 Poa j u n c i f o l i a 2.1 2.1 1.1 2.1 3.1 V 2.0 11 Rosa a c i c u l a r i s 2.1 3.1 1.1 1.+ 3.1 V 2.0 12 Agropyron spicatum 2.1 2.1 3.1 1.1 1.1 V 1.8 13 V i o l a adunca 2.+ 1.+ 2.1 3.2 1.1 V 1.8 14 A c h i l l e a m i l l e f o l i u m 1.+ 1.+ 2.+ 2.+ 2.+ V 1.6 15 Antennaria anaphaloides 2.+ 2.2 1.+ 1.1 2.1 V 1.6 16 Erigeron a c r i s 1.+ 2.+ 1.+ 2.+ 2.+ V 1.6 17 V i c i a americana 2.1 1.1 1.1 2.1 2.+ V 1.6 18 Taraxacum o f f i c i n a l e 2.+ 1.+ 2.+ 1.+ 1.+ V 1.4 19 Carex concinna - 4.2 4.2 3.2 3.2 IV 2.8 20 P o t e n t i l l a pennsylvanica 4.2 - 4.2 1.+ 2.+ IV 2.2 21 Sisyrinchlum sarmentosum 1.+ 1.+ 2.+ 1.+ IV 1.0 22 Aster campestris 1.+ 1.+ 1.+ 1.+ - IV 0.8 23 Orthocarpus hispidus 1.+ - 1.+ 1.+ +.+ IV 0.7 24 Smilacina s t e l l a t a 1.+ + .+ + .+ + .+ - IV 0.5 25 Anemone m u l t i f i d a - + .+ + .+ +.+ IV 0.4 26 Antennaria umbrinella - 2.2 2.2 1.1 - III 1.0 27 Agoseris glauca 2.+ - 1.+ +.+ - III 0.7 Picea glauca 1.+ 1.+ - - + .+ 0.5 28 Hordeum jubatum + .+ - + .+ - + .+ III 0.3 29 P o t e n t i l l a anserina 1.+ - - - 1.+ II 0.4 30 Senecio pauperculus - 1.+ - 1.+ - II 0.4 31 Thalictrum occidentale +.+ - + .+ - - II 0.3 32 Stipa r i c h a r d s o n i i - - +.+ - II 0.2 33 Parnassia p a l u s t r i s + .+ - +.+ - - II 0.2 D Laver (Brvophvtes) 34 Amblystegium serpens 5.2 5.2 4.2 4.2 4.2 V 4.4 35 Ceratodon purpureus 3.2 4.2 2.2 3.2 3.2 V 3.0 36 Tortula r u r a l i s - 3.2 - - 1.+ II 0.8 (Lichens) 37 P e l t i g e r a canina var. rufescens 1.+ 3.2 2.2 2.2 1.1 V 1.8 38 Cladonia cariosa - 1.2 - 1.+ 2.2 III 0.8 39 Cladonia chlorophaea - - - 1.+ II 0.3 40 P e l t i g e r a malacea - +.+ - - + .+ II 0.2 TOTAL SPECIES ( i n c l . sporadics) 37 34 35 35 36 Sporadic species B Layer 41 S a l i x bebbiana C Laver 42 Agropyron subsecundum 43 Aster c i l i o l a t u s 44 Astragalus dasyglottis 45 Calamagrostis neglecta 46 Cerastium arvense 47 Fragaria v i r g i n i a n a 48 P o t e n t i l l a g r a c i l i s 135(2.1) 132(2.1) 135(2.1) 134 (+. + ) 131(2.1) 133<+.+) 133(+.+) 135(2.1) 49 P u c c i n e l l i a airoides 50 S a l i x monticola 51 Solidago canadensis 52 V i o l a canadensis D Layer 53 Blastenia sinapisperma 54 Cladonia coniocraea 55 Cladonia g r a c i l i s 56 C e t r a r i a ericetorum 57 Distichium capillacftum 134(+.+) 135(1.1) 133(1.1) 135(+.+) 132(1.1) 132(+.+) 132(+.+) 131(2.2) 135(2.2) 69 slopes. These depressions are formed i n g l a c i a l stream courses which appear as shallow valleys. The surface topography is hummocky and the exposure i s considered to be neutral. So i l drainage i s judged to vary from imperfect to moderate. Free water i s present i n the profile for part of the year as evidenced by the mottling of the C horizon. Occasionally, during the spring and early summer, the association may be submerged for a short time. By late summer the s o i l of the B horizon i s moist and water may be obtained from s o i l of the C horizon by squeezing. Temporary runoff and seepage are additional factors regarded as important in maintaining the moisture conditions of this habitat. The hygrotope of this association i s considered to range from sub-hygric to hygric arid occasionally i n the spring, up to hydric. The Muhlenbergio - Betuletum glandulosae, or a variation, has been observed to be more common i n open meadows of the subalpine zone. It i s believed to be present in the Cariboo Zone largely due to local r e l i e f features which allow a cool microclimate to develop. The g l a c i a l stream courses containing the depressions with the Muhlenbergio - Betuletum glandulosae appear to act as cold a i r drainage pathways from the surrounding uplands. The local depressions further amplify this phenomenon as they trap cold a i r and thus act as frost pockets. A phenological observation supports this. Leaves of Betula and Salix were observed to be damaged by frost earlier in the autumn than were plants in neighbouring habitats. These depressions are also snow pockets and i n early March, 1969, were observed to have snow depths 2 to 4 times greater than those of the surrounding slopes. The snow accumulation i s thought to protect the vegetation against freezing, particularly during c r i t i c a l seedling stages and to provide a source of moisture at the beginning of the growing season. Over 90% of the s o i l surface i s covered by a thin l i t t e r layer 70 composed mostly of the leaves of Betula and Salix. This forms a constant source of organic matter which i s incorporated into the s o i l . The s o i l has a chernozemic A horizon varying in thickness from four to seven inches overlying a B horizon i n which some melanization has occurred. Below the B horizon i s a li g h t colored C horizon. The s o i l i s formed from a parent material of alluvium. In plots 131 and 132, sand i s the dominant s o i l fraction with rounded gravels and cobbles present i n a l l horizons. In the remaining soils coarse fragments are absent, and s i l t and clay sized particles predominate. The soil s range from gravelly sandy loams to clay loams. There i s evidence of eluviation of clay from the A horizon as a result of leaching i n plots 131, 134, and 135. The corresponding clay accumulation in the B horizon i s accompanied by a weakly columnar structure which suggests that solonization of the s o i l may be occurring. The cation exchange capacity of these s o i l s i s high as are the concentrations of exchangeable cations indicating that the sites are edaphically r i c h . The cation exchange capacity decreases from the A to the C horizon corresponding to the decrease i n measured carbon. Total nitrogen i s relatively low i n the A and B horizons but the carbon:nitrogen ratios are also low. Thus i t i s apparent that decomposition occurs readily and that there i s ample nitrogen available to satisfy the microflora requirements. Concentration of exchangeable sodium i s generally low with the exception of the A and B horizons of plot 134 which had sodium concentrations of 6.6 and 9.3 meg/100 g respectively. Since the pH of both horizons i s high (over 8.5), the excess sodium may cause a dispersal of s o i l colloids and the development of a structure unfavourable to water entry and root growth. The increased sodium content of the B horizon i s indicative of leaching. Exchangeable calcium i s present in higher con-centrations in the B horizon than in the A horizon suggesting that the A i s being degraded by leaching. This i s supported by the pH values which are Table 25 Soil Texture Muhlenbergio (richardsonis) - Betuletum glandulosae Number of Plots Plot No. A Horizon Textural class Clay (%) S i l t (%) Sand (%) Coarse fragments B Horizon Textural class Clay (%) S i l t (%) Sand (%) Coarse fragments C Horizon Textural class Clay (%) S i l t (%) Sand (%) Coarse fragments 1 135 2 131 3 134 4 133 5 132 SiL 15 49 36 None LS 3 21 76 g.c. L 26 34 40 None CL 34 40 26 None SL 16 15 69 g.c. L 25 49 26 None SCL 26 15 59 g.c. CL 37 37 26 None SCL 22 28 50 None SL 15 18 67 g.c. SiC 41 44 16 None SL 12 9 79 g.c. CL 38 42 21 g. SiCL 29 53 18 None LS 6 14 80 g.c. 72 Table 26 Soil Chemical Analysis Muhlenbergio (richardsonis) - Betuletum glandulosae Number of Plots Plot No. 1 135 2 131 3 134 4 133 5 132 A Horizon C% N% C/N P ppm Na K Ca Mg CEC pH 5.0 .37 13, 12, 17 20 31 8 5 0 76 13 5 1 0 0 9.8 .43 22.8 7.0 .37 1.12 13.7 19.8 38.5 7.9 6.1 .28 21.8 7.0 6.6 2.35 5.8 19.3 26.9 8.9 10 11 3 1 8 ,4 .22 .9 .0 .6 .18 .3 20.0 18.5 8.2 7.0 .41 17.5 12.0 1.12 1.63 9.9 21.4 32.6 8.1 B Horizon C% .fi N% C/N P ppm Na K Ca Mg CEC PH 2.4 .21 11.4 10.0 .48 .23 15.4 11.2 16.8 7.9 0 5. 17 15 10 8 ,12 .0 .32 .96 .0 ,3 .4 .3 8.3 \u00E2\u0080\u00A2 57 14.6 17.0 9.30 2.20 7.2 19.6 42.1 9.0 28. 7. 1. .4 .05 .0 .0 .4 .66 9.3 20.5 10.0 8.7 11, 9, 12 14 14.8 8.4 1 18 7 0 45 96 6 7 C Horizon c% 0 0 0 0 0 N% .17 0.10 .13 .06 .10 C/N 0 0 0 0 0 P ppm 6.0 4.0 3.0 3.0 5.0 Na .46 .34 3.4 .87 .46 K .23 .42 1.10 .68 .98 Ca 28.7 13.1 9.8 12.8 9.8 Mg 12.5 10.0 12.5 11.9 14.1 CEC 8.3 4.6 10.8 6.3 11.3 pH 7.6 8.1 8.5 8.5 8.0 73 highest in the B horizon possibly as a result of i l l u v i a t i o n of basic cations. The s o i l reaction i s alkaline in a l l horizons. The trophotope of this habitat i s considered to be eutrophic. The so i l s of the Muhlenbergio - Betuletum glandulosae are classed as Gleyed Dark Grey Chernozems or Gleyed Solonetzic Dark Grey Chernozems. The soils of plots 132 and 135 are developed over a buried melanized horizon which indicates that vegetation other than that now present once occupied these depressions. It i s possible that the buried horizons developed under vegetation similar to the Caricetum rostratae as this association presently occupies neighbouring habitats in the stream depressions. Structurally the Muhlenbergio - Betuletum glandulosae consists of a well developed layer and a well developed C layer with cover ranges of 44% to 68% and 74% to 88% respectively. The D layer i s poorly developed with a percentage cover varying from 8% to 18%. There i s also a very poorly developed B^ layer (present in two plots) and a weakly developed layer (present in one plot). Picea glauca forms the A-j and B^ layers and i t s presence i s indicative of the cool hygric conditions of this habitat as Picea glauca grows only in moist sites in the Cariboo Zone. Betula glandulosa and Salix brachycarpa constitute the B 2 layer with average significances of 7.0 and 2.4 respectively. Salix, because of i t s growth form, i s more common in the C layer where i t has an average significance of 4.4. Both species are boreal-subarctic elements (Krajina, personal communication) and are thus considered to be indicators of the cool microclimate of this association resulting from cold a i r drainage. Muhlenbergia richardsonis, a species characteristic in the Cariboo Zone of moist alkaline areas with heavy snow accumulation, dominates the C layer with an average significance of 7.2. Arctostaphylos uva-ursi i s constantly 74 present and attains i t s best growth on the drier hummocks which are rarely flooded. Additional species on the hummocks include: Koeleria g r a c i l i s , Agropyron spicatum, Poa jun c i f o l i a , Potentilla pennsylvanica and Aster campestris. The presence of Carex praegracilis, Aster pansus, Juncus balticus, Hordeum jubatum, Sisyrinchium sarmentosum, Potentilla anserina, Parnassia palustris and Puccinellia airoides reflects the hygric to hydric alkaline conditions that prevail between the hummocks. Carex concinna, Rosa acicularis, Antennaria anaphaloides and Vicia americana together with Arctostaphylos uva- ursi and Picea glauca are forest species which occur in this association. They are thought to be present because of the cool frost-pocket microclimate. The most important bryophyte species i s Amblystegium serpens with an average significance of 4.4. Ceratodon purpureus and Tortula ruralis are the only other bryophytes occurring i n two or more plots. n The lichen flora i s poorly developed and confined mostly to the hummocks. The most important species are Peltigera canina var. rufescens, Cladonia cariosa, C. chlorophaea and Peltigera malacea. This association appears to have a history of moderate grazing. Koelerio (gracilis) - Agropyretalia spicati Extensive areas of the Cariboo Zone are represented by associations described in the Koelerio - Agropyretalia s p i c a t i . The soil s of these associations are formed from fine textured parent materials considered to be aeolian in origin. The habitats are rated trophically from permesotrophic to eutrophic and hygrotopically from very xeric to submesic. The order i s charac-terized^ by Agropyron spicatum, Arabis h o l b o e l l i i , Artemisia f r i g i d a , Erigeron f l a g e l l a r i s , Koeleria g r a c i l i s , Tragopogon dubius, Tortula ruralis and Cladonia pocillum. This order i s believed to encompass the grass type described by Whitford and Craig (1918) and the lower, middle and upper grassland zones 75 proposed by Tisdale (1947). It i s similar to the Palouse grasslands of Washington as described by Daubenmire (1942) . Two alliances are recognized for the Koelerio - Agropyretalia s p i c a t i \u00E2\u0080\u0094 t h e Stipion columbianae and the Agropyrion spi c a t i . Stipion columbianae The Stipion columbianae i s an upland alliance occurring on the Fraser Plateau at elevations over 2500 f t . Hygrotopes of this alliance range from xeric to submesic. It i s characterized by cool temperatures, and frosts are frequent even during the summer (see page240 ) . The growing season i s shorter than that of the Agropyrion s p i c a t i . This alliance i s characterized by: Antennaria rosea, A. umbrinella, Aster campestris, Astragalus dasyglottis, Carex praticola, Cerastium arvense, Festuca saximontana, Juncus balticus, Orthocarpus hispidus, Poa juncif o l i a, Poa pratensis, Potentilla pennsylvanica and Stipa columbiana. Astragalus dasyglottis, which i s a halophilous species and Juncus balticus which i s a hygrophilous species are representative of moist, saline sit e s . Thus, these species are considered to have only minor importance as characteristic species of the Stipion columbianae. The middle and upper grassland zones of Tisdale (1947) would be included i n this alliance. The alliance appears to be similar to the Agropyron -Poa Zone described by Daubenmire (1942) i n Washington. Agropyrion spicati The Agropyrion spicati i s confined to low elevations and reaches i t s best development on the slopes and bottoms of the major river valleys. Hygrotopes of this alliance range from very xeric to xeric. It i s characterized by a warmer climate and summer temperatures over 90\u00C2\u00B0 are common (see page ). Summer frosts are very infrequent and thus i t i s considered to have a long growing season. The alliance i s characterized by: Calochortus macrocarpus, 76 comandra umbellata, Lithospermum ruderale, Lomatium macrocarpum, Opuntia f r a g i l i s , Diploschistes canadensis, Lecidea decipiens, and Physcia muscigena. Previously described vegetation types in Br i t i s h Columbia which would be included in this alliance are: the sagebrush type and Agropyron spicatum grass type of whitford and Craig (1918); the grassland formation of Halliday (1937); the bunch grass prairie of Rowe (1959); the lower grassland zone of Tisdale (1947) and the Agropyron spicatum (grassland) associations of Brayshaw (1955, 1965). This alliance resembles the sagebrush-grass type of Pickford (1932) and Stoddart (1941) in Northern Utah and the Agropyron-Artemisia zone of Daubenmire (1942) in Southeastern Washington. Stipion columbianae L Poo (juncifoliae) - Elymeturn cinerei (ref. Tables; 27, 28, 29, 30, 83, and Fig. 9) Characteristic Combination of Species Order Characteristic Species Agropyron spicatum Arabis h o l b o e l l i i Artemisia fr i g i d a Erigeron f l a g e l l a r i s Koeleria g r a c i l i s Tragopogon dubius Tortula ruralis Cladonia pocillum Cladonia pyxidata Alliance Characteristic Species Antennaria rosea Antennaria umbrinella Aster campestris Astragalus dasyglottis Carex praticola Cerastium arvense Festuca saximontana Juncus balticus Orthocarpus hispidus Poa j u n c i f o l i a Poa pratensis Potentilla pennsylvanica \u00E2\u0080\u00A2 \u00E2\u0080\u00A2 \u00E2\u0080\u00A2 \u00E2\u0080\u00A2 \u00E2\u0080\u00A2 \u00E2\u0080\u00A2 -\u00E2\u0080\u00A2'\u00E2\u0080\u00A2>\u00E2\u0080\u00A2 The Poo - Elymetum c i n e r e i as developed on an o l d a l l u v i a l t e r r ace. The dominant Elymus cinereus occurs i n widely spaced clumps suggesting vegetative propagation. 78 Alliance Characteristic Species (Cont'd) Stipa columbiana Association Characteristic Species Elymus cinereus \" Important Companion Species Populus tremuloides Carex praegracilis Smilacina s t e l l a t a The Poo - Elymetum cinerei occurs as isolated pockets either on old stream terraces or on benches below slopes with permanent seepage. In this study the sampled plots were a l l located on stream terraces at the base of exposed slopes but none were permanent seepage slopes. Measured slope gradients ranged from 0\u00C2\u00B0 to 4\u00C2\u00B0 and the exposure was generally neutral. The surface topography i s f l a t to straight. There i s no evidence of surface erosion in this association and the s o i l drainage i s considered to be moderate. The s o i l i s developed on a parent material of alluvium. Three horizons are present\u00E2\u0080\u0094a chernozemic A horizon varying in thickness from three inches to four inches, overlying a lighter coloured B horizon which ranges in thickness from three inches to 10 inches and a mineral C horizon which shows a strong effervescence with hydrochloric acid indicating the presence of carbonates. Texturally the sampled A horizons ranged from sandy loams to s i l t y loams and no particles greater in size than two mm were present. The B horizon i s finer textured and the samples were predominantly loams. There i s an accumulation of clay here, accompanied by a slight columnar structure in plots 037 and 073. This suggests that the A horizon is being eluviated as a result of leaching. The C horizon i s generally coarser and samples ranged from loams to loamy sands. Particles of gravel size or larger were present i n three sampled C horizons. So i l moisture content appears to increase downward in the p r o f i l e . Table 27 Poo (juncifoliae) - Elymetum cinerei Plot Data Number of Plots 1 2 3 4 5 Piot No. 073 075 072 037 136 Plot Size (m2) Date analyzed 4/7 5/7 4/7 2/8 11/9 1968 1968 1968 1967 1968 Elevation (ft) 2850 2900 3000 3040 3150 Locality FP FP FP FP FP 51\u00C2\u00B048' 51\u00C2\u00B048' 51\u00C2\u00B048' 51\u00C2\u00B047' 51\u00C2\u00B035' 122\u00C2\u00B037' 122\u00C2\u00B039' 122\u00C2\u00B037' 122\u00C2\u00B038' 122\u00C2\u00B024' Physiography Landform old Relief shape f l a t straight straight concave f l a t Exposure neutral SE W SE neutral Slope gradient (\u00C2\u00B0) 0 2 1 4 0 Layer coverage (%) B 2 layer - 8 4 - \u00E2\u0080\u00A2 2 C layer 88 92 91 80 86 D layer 10 8 15 38 16 Plot coverage (%) Humus and l i t t e r 94 94 95 86 97 Mineral s o i l 6 6 5 14 3 Soil Hygrotope submesic Trophotope eutrophic Erosion ni l Drainage Horizon depth (in) A 0-5 0-5 . 0-5 0-4 0-5 B 5-15 5-11 5-11 4-7 5-9 C 15-30+ 11-32+ 11-26+ 7-27+ 9-26+ Parent material alluvium 80 Table 28 Poo ( j u n c i f o l i a e ) - Elymetum c i n e r e i Number of P l o t s 1 2 3 4 5 P l o t No. 073 075 072 037 136 P l o t S i z e (m2) 100 100 100 100 100 E l e v a t i o n ( f t ) 2850 2900 3000 3040 3150 sub Avg Species 1 Populus tremuloides 2 4. , + 3. , + 3. , + I I I 2. 0 C Layer 2 Elymus cinereus 7. 3 7. . 2 7. .2 7. . 3 7 . 3 V 7. .0 3 Poa j u n c i f o l i a 7. 2 4. .1 7. .2 4. ,1 4. . 1 V 5. ,2 4 Poa p r a t e n s i s 3. 1 5. ,1 3. . + 3. 2 4. , 2 V 3. ,6 5 Taraxacum o f f i c i n a l e 4. 2 3. ,1 3. , + , + 3. ,+ V 2. ,8 6 A s t r a g a l u s d a s y g l o t t i s 1. 1 4 . 1 1. .+ 2. . 1 +. . + V 1. 7 7 A c h i l l e a m i l l e f o l i u m 1. + 1. , + 1. ,+ 4 . 1 + . , + V 1. ,5 8 Cerastium arvense 2. 1 3. . 1 3. , 1 4. . 3 IV 2. ,4 9 Carex p r a e g r a c i l i s 3. 1 2 . 1 4. , 1 2. .1 IV 2 . ,2 10 S m i l a c i n a s t e l l a t a 3. .1 2. .1 4, . 1 2 .1 IV 2. .2 11 S t i p a columbiana 2. .1 3. .1 3. .2 2. .1 IV 2 , .0 12 Juncus b a l t i c u s 3. .1 2. .1 3. .2 1. . + IV 1. .7 13 A s t e r campestris 2. , 1 3. .1 2. .+ 1. .1 IV 1. .6 14 V i o l a adunca 3. . 1 1. .1 2. .1 2, .1 IV 1. .6 15 Tragopogon dubius 1. , + 1. .+ 2, . + 1 .+ IV 0. .9 16 Carex concinna 1. .1 1, .2 6 .3 II I 1. .6 17 E r i g e r o n f l a g ' e l l a r i s 1. . 1 2. . 2 3, .1 I I I 1, .2 18 Festuca saximontana 1, .1 3. . 1 2, . 1 I I I 1, .2 19 K o e l e r i a g r a c i l i s 3, . 1 1. . + 1. . 1 I I I 1, .6 Populus tremuloides +. . + +. , + 1. . + 0. . 4 20 Anemone m u l t i f i d a +, , + +, . + +. . + I I I 0. . 2 21 Antennaria rosea 5, .2 + . + II 1. .1 22 S t i p a r i c h a r d s o n i i 3, . 1 1. . 1 II 0. . 8 23 Antennaria u m b r i n e l l a 1. . 2 2, . 2 II 0 . 6 24 V i c i a americana 1, . 1 2 .+ II 0. .6 25 Agropyron spicatum +. . + 2 .2 II 0, .5 26 A r t e m i s i a f r i g i d a 1. . 1 2 , . 1 11 0 .6 27 Galium boreale 1. . + 1 .+ II 0. . 4 28 P o t e n t i l l a pennsylvanica 1. . 1 1. .+ II 0. .4 D Layer (Bryophytes) 29 T o r t u l a r u r a l i s 4. .2 3, . 1 4 . 2 3, . 2 5. . 3 V 3 , . 8 30 Ceratodon purpureus 3. .1 1, . 1 2, . 1 2, .1 IV 1. .4 31 Amblystegium serpens 1. . 1 3, .2 3 .2 II I 1. .4 32 Bryum argenteum 1. . 1 1 .1 1 . + I I I 0. .5 33 Brachythecium salebrosum 1. . + 3. .2 II 0. .7 (Lichens) 34 C l a d o n i a p o c i l l u m 2. . 2 3, . 1 3, . 1 6. . 4 2 . 1 V 3. .2 35 P e l t i g e r a malacea 2 . 1 3. . 2 3 . 1 III 1. .4 TOTAL SPECIES ( i n c l . sporadics) 30 30 29 34 20 Sporadic s p e c i e s B Layer 36 Amelanchier a l n i f o l i a 073(3.+) 37 Symphoricarpos o c c i d e n t a l i s 073(4.2) C Layer 38 Agropyron subsecundum 075(2.1) 39 A g r o s t i s c x a r a t a 073(2.1) 40 A l l i u m cernuum 075(+.+) 41 Antennaria dimorpha 037(3.2) 42 A r a b i s h o l b o e l l i i 037(+.+) 43 Aster pansus 136(3.1) 44 Carex obtusata 037(3.1) 45 Hordourn jubatum 136(+. + ) 46 Muhlenbergia r i c h a r d s o n i s 073(1.+) 47 Orthocarpus h i s p i d u s 4 8 Penstemon procerus 49 Poa i n t e r i o r 50 Rosa a c i c u l a r i s 51 S i l e n e s c o u l e r i 52 S i s y r i n c h i u m sarmentosum 53 Solidago m u l t i r a d i a t a 54 S p a r t i n a g r a c i l i s D Layer 55 C l adonia pyxidata 56 P e l t i g e r a canina var. rufescens 57 Polytrichum junipcrinum 037(2.+) 075 (+. + ) 072(1.1) 037(1.+) 037 (1. + ) 073 (1. + ) 037(+.+) 073(2.1) 072(2.1) 037(2.1) 037(2.2) 81 The A horizon i s always dry and the B horizon i s only slightly moist. However, the C horizon i s always very moist and sometimes moisture can be exuded from the s o i l by squeezing. The higher moisture content of the C horizon i s thought to be caused partly by a high water table and partly by lateral movement of water downslope due to temporary seepage. However, free water i s probably seldom present as there i s no evidence of mottling in the C horizon. The hygrotope of the Poo - Elymetum cinerei i s considered to range from submesic up to mesic. Moisture i s believed to be an important factor in controlling the distribution of this association as the characteristic species, Elymus cinereus, i s dependent on moist habitats. Over 90% of the s o i l surface i s covered by a thin layer of l i t t e r . Measured carbon in the A horizon i s correspondingly high, suggesting an accumulation of organic matter. The amount of carbon decreases through the B horizon and carbon i s only sl i g h t l y present i n the C horizon. The carbon: nitrogen ratios of the A horizons are relatively high indicating that the nitrogen content of the incorporated organic matter i s not sufficient to satisfy the microfloral requirements. Thus a competition for nitrogen between the microflora and higher plants may occur. The carbon:nitrogen ratios of the B and C horizons are lower, suggesting that the nitrogen present here i s available to higher plants. The cation exchange capacity i s high in the A horizon largely due to the incorporated organic matter. Recorded values range from 36.0 meg/100 g to 126.4 meg/100 g. i t decreases through the B horizon and i s relatively low in the C horizon because of the coarse texture of the s o i l . Exchangeable calcium and magnesium are present in moderate amounts with magnesium generally higher than calcium. A high concentration of exchangeable sodium i s present especially in the B horizon where concentrations of up to 17.12 meg/100 g were measured. This excess of sodium i s at the expense of potassium, as sodium w i l l Table 29 Soil Texture Poo (juncifoliae) - Elymetum cinerei Number of Plots 1 2 3 4 5 Plot No. 073 075 . 072 037 136 A Horizon Textural class Clay (%) S i l t (%) Sand (%) Coarse fragments B Horizon Textural class Clay (%) S i l t (%) Sand (%) Coarse fragments C Horizon Textural class Clay (%) S i l t (%) Sand (%) Coarse fragments SL 9 34 57 L 16 43 41 None LS 4 15 81 g. SL 3 45 52 SiL 2 53 45 None SiL 4 74 21 None SiL 1 52 47 None SL 3 41 56 g. SL 3 45 52 g. SL 9 46 45 L 24 38 38 g-L 20 41 39 g.c. SL 9 50 41 L 11 43 45 None L 22 37 41 None 83 Table 30 Soil Chemical Analysis Poo (juncifoliae) - Elymetum cinerei Number of Plots 1 2 3 4 5 Plot No. 073 075 072 037 136 A Horizon C% 17.4 14.6 37.4 12.7 19.3 N% .84 .61 1.16 .46 .63 C/N 20.7 23.9 32.2 27.6 . 30.6 P ppm 11.0 12.0 31.0 9.0 19.0 Na 7.51 .36 .27 1.21 .64 K 2.48 2.41 1.96 6.83 2.14 Ca 9.2 \u00E2\u0080\u00A2 11.5 10.3 6.5 10.7 Mg 28.2 7.9 9.6 4.6 8.7 CEC 36.0 83.5 126.4 46.5 94.0 pH 8.2 6.8 7.0 7.1 7.5 B Horizon c% 0 1.4 7.1 7.0 17.1 N%- .08 .12 .41 .09 .84 C/N 0 11.7 17.3 7.78 20.4 P ppm 4.0 10.0 8.0 10.0 16.0 Na 3.53 .40 3.34 17.12 . 1.42 K .61 1.63 1.51 6.12 2.51 Ca 12.5 6.6 5.6 6.5 11.7 Mg 15.8 6.3 9.8 14.1 16.3 CEC 12.9 31.8 32.7 34.8 90.6 pH 8.5 6.1 6.8 8.5 8.1 C Horizon C% N% C/N P ppm Na K Ca Mg CEC pH 0 .10 0 3.0 .66 .33 12.8 6.8 4.7 8.4 8 11 1 1 6 .9 .34 .5 .0 .4 .42 .6 15.7 13.0 8.2 0 .07 0 9.0 1.12 .63 9.4 14.0 16.8 8.5 0 .06 0 3.0 7.98 .30 14.5 14.7 18.0 8.9 0 8. 2. 6. 13. .13 .0 ,38 .42 ,6 .5 16.3 9.3 84 replace potassium on the exchange complex. Also, the high sodium coupled with pH i n the range of 8.5 may cause the dispersion of s o i l colloids resulting in a structure unfavourable to root development and water entry. In such soils a further development may occur i n which dispersed clay i s moved down the p r o f i l e and forms a dense layer with columnar structure which i s inpenetrable to plant roots and water. This process appears to be occurring in plots 037 and 072. The s o i l reaction i s neutral to alkaline at the surface and becomes strongly alkaline with depth. Measured pH values of the C horizon range from 8.2 to 9.3. This increase i n pH could be due to a leaching of soluble salts by ground water and seepage. With the exception of plots 037 and 072 the s o i l s of this association are c l a s s i f i e d into the Orthic Dark Brown Chernozemic subgroup of the Canadian Soi l Classification System. Plots 037 and 072 are c l a s s i f i e d as Solonetzic Dark Brown Chernozems because of their high sodium contents and columnar B horizons. They are considered to be intermediate between the Solonetzic and Chernozemic Orders. Structurally, the Poo - Elymetum cinerei consists of a well developed C layer with a percentage cover ranging from 80% to 92%, a poorly developed D layer with a coverage ranging from 8% to 38% and a weakly developed B 2 layer with a percentage cover ranging from 2% to 8%. The B 2 layer i s composed entirely of transgressives of Populus tremuloides which are probably stems from root suckers of Populus clones occurring on the same stream terraces. Their presence i s indicative of a relatively high water table. The C layer i s dominated by Elymus cinereus which i s constantly present with an average significance of 7.0. It i s the only characteristic species of this association. Poa ju n c i f o l i a , a characteristic species of moist 85 alkaline habitats i s the only other constant dominant with an average species significance of 5.2. Poa pratensis, Achillea millefolium, and Astragalus dasyglottis are constant non dominants, a l l present with low species significance. Smilacina s t e l l a t a and Juncus balticus with average species significances of 2.2 and 1.7 respectively are indicative of the moist habitat. Cerastium arvense, Stipa columbiana, Aster campestris, Koeleria g r a c i l i s , Erigeron f l a g e l l a r i s , and Festuca saximontana occur as non constants with low significance. These species are more characteristic of the exposed slopes occupied by the Antennario - Poetum secundae and their presence is probably because of the very dry, less alkaline A horizon i n which most are rooted. The high alkalinity, moist subsoil as well as the presence of soluble salts i n this association i s indicated by the presence of the following halophytic species: Carex praegracilis, with a constancy of Class IV; Aster pansus, Hordeum jubatum; and Spartina g r a c i l i s . The D layer i s dominated by Tortula ruralis and Cladonia pocillum with average species significances of 3.8 and 3.2 respectively. No other bryophytes or lichens contribute significantly to the structure of this layer. The Poo - Elymetum cinerei appears to be closely related to the Elymetum cinerei (mentioned by Brayshaw 1965) which occupies a l l u v i a l flood plains of the Thompson River Valley. The two d i f f e r , however, by the fact that the Poo - Elymetum cinerei i s developed on Chernozemic rather than on Regosolic soi l s and that i t has a large compliment of dry steppe-like plants. It i s possible that the Poo - Elymetum cinerei represents a r e l i c t association of a once more widely spread Elymetum cinerei. The association presently exists in isolated pockets where basic cations have accumulated and where the water table i s relatively high. The Poo - Elymetum cinerei maintains i t s identity through the presence of Elymus cinereus which i s probably surviving only by asexual reproduction, as at the present time the s o i l surface appears to be too dry for 86 the establishment of seedlings of Elymus cinereus. The Poo - Elymetum cinerei appears to have a history of moderate but selective grazing as Poa ju n c i f o l i a and Poa pratensis are more heavily grazed than Elymus cinereus. 2. Antennario (dimorphae) - Poetum secundae (ref. Tables; 31, 32, 33, 34, 83, and Fig. 10, 11) Characteristic Combination of Species Order Characteristic Species Agropyron spicatum Arabis h o l b o e l l i i Artemisia frigida Erigeron f l a g e l l a r i s Koeleria g r a c i l i s Tortula ruralis Tragopogon dubius Cladonia pocillum Cladonia pyxidata Alliance Characteristic Species Antennaria rosea Antennaria umbrinella Aster campestris Astragalus dasyglottis Carex praticola Cerastium arvense Festuca saximontana Poa j u n c i f o l i a Poa pratensis Potentilla pennsylvanica Stipa columbiana Association Characteristic Species Antennaria dimorpha Lepidium densiflorum Poa secunda The Antennario - Poetum secundae i s the most common grassland association at higher elevations on the Fraser Plateau. It reaches i t s best development at elevations greater than 3000 feet. Here the climate i s cool and the growing season relatively short. The association occurs on gentle but exposed slopes. The measured slope gradients ranged from 1\u00C2\u00B0 to 7\u00C2\u00B0 . 87 Table 31 P l o t Data Number of Plots Plot No. Plot Size (m2) Date analyzed Elevation (ft) L o c a l i t y Physiography Landform R e l i e f shape Exposure Slope gradient (\u00C2\u00B0) Layer coverage (%) C layer D layer P l o t coverage Humus and l i t t e r Mineral s o i l Rock S o i l Hygrotope Trophotope Erosion Drainage Horizon depth (in) Parent material Antennario (dimorphae) -antennario - poetosmn secundae Poetum secundae juncetosum b a l t i c i 1 2 . 3 4 5 6 7 8 9 10 11 12 033 071 026 030 054 029 055 077 079 078 076 082 100 100 100 100 100 100 100 100 100 100 100 100 30/7 2/7 26/7 26/7 22/8 28/7 23/8 14/7 16/7 16/7 13/7 19/7 1967 1968 1967 1967 1967 1967 1967 1968 1968 1968 1968 1968 3050 3150 3250 3300 3360 3400 3420 3300 3300 3350 3420 3540 FP FP FP FP FP FP FP FP FP FP FP FP 51*47' 51*42' 51-48\u00E2\u0080\u00A2 51*49' 51*36' 51*48' 51*36' 51*46' 51*48' 51*47' 51*43' 51*44' 122*39' 122*36' 122*36' 122*35' 122*33' 122*36' 122*33' 122*52' 122*54' 122*53' 122*50' 122*51 exposed ridge slope top st r a i g h t f l a t SE neutral . . . s t r a i g h t . . .exposed slope convex .. . s t r a i g h t . 74 4 75 24 1 75 15 75 25 0 70 2 66 33 1 83 1 84 15 1 76 15 80 17 3 76 20 2 xer i c .permesotrophic. depres-sion ....concave... neutral sw 0 1 76 76 9 6 78 80 20 18 2 2 ...base of slope s t r a i g h t concave s t r a i g h t HW SW SE 3 2 2 82 8 85 13 2 .submesic.. .eutrophic. 86 12 89 11 0 ei 22 88 11 1 s l i g h t water . . s l i g h t water, .well . . . s l i g h t water, .moderate 0-4 4-9 9-21* 0-5 5-15 15-28+ 0-4 4-11 11-25+ 0-6 6-14 14-24* 0-5 5-12 12-24+ 0-5 0-5 5-15 5-11 15-26+ 11-24+ .aeolian deposit over g l a c i a l d r i f t . 0-5 0-6 0-5 0-5 0-5 5-12 6-11 5-11 5-11 5-14 12-28+ 11-26+ 11-24+ 11-24+ 14-26+ aeolian deposit over g l a c i a l d r i f t 88 32 Antennario (dimorphae) - Poetum secundae antennario - poetosum secundae juncetosum b a l t i c i Number of P l o t s P l o t No. P l o t S i z e E l e v a t i o n ( f t ) 1 Poa secunda 2 Antennaria dimorphia 3 A r t e m i s i a f r i g i d a 4 An t e n n a r i a u m b r i n e l l a 5 Poa j u n c i f o l i a 6 Cerastium arvense 7 K o e l e r i a g r a c i l i s 8 P o t e n t i l l a p e n n s y l v a n i c a 9 Antennaria rosea 10 A s t r a g a l u s d a s y g l o t t i s 11 A s t e r campestris 12 A c h i l l e a m i l l e f o l i u m 13 Festuca saximontana 14 Taraxacum o f f i c i n a l e 15 Agropyron spicatum 16 S t i p a columbiana 17 A l l i u m cernuum 18 A r a b i s h o l b o e l l i i 19 Juncus b a l t i c u s 20 Poa p r a t e n s i s 21 Carex p r a t i c o l a 22 E r i g e r o n f l a g e l l a r i s 23 S o l i d a g o m u l t i r a d i a t a 24 Lappula r e d o w s k i i 25 Lepidium d e n s i f l o r u m 26 E r i g e r o n compositus 27 Tragopogon dubius 28 Chenopodium l e p t o p h y l l u m 29 E r i g e r o n speciosus 30 Carex obtusata 31 Eriogonum h e r a c l e o i d e s 32 Comandra umbellata 33 Linum l e w i s i i 34 Lomatium macrocarpum 35 Orthocarpus h i s p i d u s 36 S i l e n e s c o u l e r i 37 Geum t r i f l o r u m 38 Rosa a c i c u l a r i s 39 Agropyron subsecundum 40 Anemone m u l t i f i d a 41 A s t r a g a l u s t e n e l l u s 42 A n t e n n a r i a n e g l e c t a 43 C r e p i s tectorum 44 Agropyron trachycaulum 45 Androsace s e p t e n t r i o n a l i s 46 S t i p a r i c h a r d s o n i i D Layer (Bryophytes) 47 T o r t u l a r u r a l i s 48 Bryum argenteum (Lichens) 49 C l a d o n i a p o c i l l u m 50 P e l t i g e r a malacea 51 C l a d o n i a p y x i d a t a 52 C a l o p l a c a s t i l i c i d i o r u m 53 Parmelia c h l o r o c h r o a 1 2 3 4 5 6 7 033 071 028 030 054 029 055 100 100 100 100 100 100 100 30S0 3150 3250 3300 3360 3400 3420 10 11 12 077 079 078 076 082 100 100 100 100 100 3300 3300 3350 3420 2540 Avg Species S i g n i f i c a n c e Avg Species S i g n i f i c a n c e Constancy A s s o c i a t i o n Avg Species S i g n i f icance 3.2 4.1 6.2 3.1 5 3 5.3 5.2 4 4 5 2 4 1 5 1 5.2 2.1 4.2 V 4 3 4.2 5.2 4.3 3.2 4 2 5.3 6.3 4 4 4 2 4 2 4 2 2.1 4.2 2.8 V 3 8 3.1 3.1 5.3 2.2 5 2 5.3 4.3 3 9 4 1 3 2 5 2 3.1 3.1 3.6 V 3 8 3.2 6.3 2.1 2.1 6 2 3.3 5.3 3 9 3 1 3 2 3 2 3.2 3.2 3.0 V 3 5 2.2 - 6.2 2.1 6 3 4.3 S.2 3 6 1 1 5 1 1 1 - 3.1 2.0 V 3 2 1.1 2.1 1.+ 3.2 2 1 2.1 2.2 1 B 6 2 4 2 4 2 5.2 4.1 4.6 V 3 0 2.1 4.2 2.1 2.1 6 3 3.1 7.3 3 7 2 1 2 1 1 1 2.1 2.1 1.8 V 2 9 2.1 3.+ 3.1 3.+ 3 + 3.+ 4.2 3 0 3 1 1 + 2 + 3.+ 3.+ 2.4 V 2 8 6.3 2.2 6.3 3.3 3 2 6.4 3.2 4 0 1 1 2 2 1.+ - 0.8 V 2 7 2.+ 2.+ 3.+ 1.+ 2 + 3.+ 3.+ 2 3 2 + 2 3 1 2.+ 2.+ 2.2 V 2 3 - +.+ 3.1 3.1 2 + 2.1 2.2 1 8 3 3 + 3 + 3.+ 3.1 3.0 V 2 3 3.+ +.+ - 1.+ 3 1 3.1 3.+ 1 9 2 + 2 + 3 + +. + 2.+ 1.9 V 1 8 2.1 3.+ 1.+ - 1 1 1.1 2.1 1 3 1 1 3 1 2.1 3.1 1.8 V 1 5 1.+ 1.+ 1.1 1.1 1 + 2.+ +. + 1 1 2 + 2 + 1 + - - 1.4 V 1 2 2.1 - 2.1 2.1 3 2 2.1 3.2 2 0 2 1 1 1 - 2.1 1.0 IV 1 5 1.+ 2.1 + . + 7.3 +. + +.+ 1 6 2 + 2 1 2.1 - 1.2 IV 1 1 1.+ +. + 2.+ - + + 1.+ 2.+ 1 0 3 + - 1.+ 0.8 IV 0 9 + .+ 1.+ - - - 0 3 2 1 1 + + + 2.+ 1.+ 1.3 IV 0 7 - - - - 2 1 - - 0 3 7 1 7 2 7 2 7.2 7.1 7.0 I I I 3 1 - 4.2 - 3.3 - - 0 9 3 1 3 2 3.1 5.1 2.8 I I I 1 7 - - - - + + - 3.+ 0 5 3 + 3 2 3 1 3.1 2.1 2.8 I I I I 5 7.3 1.+ +. + - 3.2 - 1 6 4 1 2 1 - - 1.2 I I I 1 5 - + .+ 1.+ 2.+ 2.+ - 0 8 2 + 1 1 3 1 - - 1.2 I I I 1 0 - 2.+ - +. + - - 0 4 2 + 2 + 2.+ 1.+ 1.4 I I I 0 9 - - 2.+ 1.+ 2.* +. + 0 8 1 + t + - 2.+ 0.7 I I I 0 B 1.+ +. + 2.1 - 2.1 2.2 1 1 - - _ I I I 0 6 1.+ 2.+ + .+ - 1 + 2.+ 1.+ 1 1 - - _ I I I 0 6 - + .+ - - - - 0 1 2 + 1 + 1 + 1.+ - 1.0 I I I 0 5 2.1 - - - 2 1 - - 0 4 1 + 1 1 1 + - - 0.6 I I I 0 5 2.2 3.1 3.2 - - 3.1 1 6 - - I I 0 9 3 2 2 1 3 1 2.1 - 2.0 I I 0 8 - - +. + - 2 + - 2.+ 0 6 2 + - - 0.4 11 0 5 1.+ - - - - 2.1 0 4 1 + + + - - 0.3 II 0 3 1.+ - - - - 1.+ 0 3 1 + - - 0.2 I I 0 3 1 + 1 + - 1.+ 0.6 11 0 3 + .\u00E2\u0080\u00A2 - - - - 0 1 + + - - 0.1 I I 0 1 2 2 3 2 - - 1.0 I 0 4 2.+ 3.+ \u00E2\u0080\u00A2 - - - 0 7 - - _ I 0 4 + . + 0 1 2 1 - - 0.4 I 0 3 2.+ 2.+ - - - - 0 6 _ - _ I 0 3 - - 2.+ - 1.1 - 0 4 - _ I 0 3 - - 2.+ - + . + - 0 4 - - _ I 0 2 - - - - - - 1 + 1 \u00E2\u0080\u00A2 - - 0.4 I 0 2 - 1.+ - - - - 0 1 1 + - - 0.2 I 0 1 + .+ - - - - - 0 2 - - - I 0 1 1 + +. + ~ 0.2 1 0 1 3.2 4.2 +.+ 4 2 +. + 3.1 2 2 3 2 4 2 3 2 4.2 5.3 3.8 V 3 0 3 1 2.1 0 9 2 1 1 1 1 + 2.2 3.2 1.8 I I I 1 4 3.2 3.2 2.1 1.1 3 2 2.1 2.1 2 3 3 1 3 1 3 1 3.2 2.1 2.8 V 2 5 1.1 - 2 1 - - 0 4 1 + 3 2 2.2 2.1 1.6 I I I 1 0 2 1 1 + 3.2 1.+ 1.4 II 0 7 - 1.1 - - - - 0 1 - 2.1 0.4 I 0 3 2.1 2.1 0 6 I 0 3 TOTAL SPECIES ( i n c l . s p o r a d i c s ) 32 33 29 22 25 27 33 Sporadic s p e c i e s C Layer 66 C l a d o n i a chlorophaea 082(1 + ) 54 A r t e m i s i a campestris 055(1 + ) 60 Polemonium pulcherrimum 076(2 1) 67 C l a d o n i a nemoxyna 055(1 1) 55 Bromus anomalus 055( + + ) 61 P o t e n t i l l a d i v e r s i f o l i a 077(1 + ) 68 C o r n i c u l a r i a a cuteata 071(2 1) 56 Chenopodium f r e m o n t i i 082(2 + ) 62 Sedum stenopetalum 078(1 1) 69 Dermatocarpon hepaticum 082(1 1) 57 Delphinium b i c o l o r 079(1 + ) 63 Senecio pauperculus 079(2 1) 70 P e l t i g e r a lepidophora 082 (1 *) 58 Heuchera c y l i n d r i c a 078(1 +) 64 S t i p a comata 033( + + ) 71 D i p l o s c h i s t e s canadensis 078( + + ) 59 Pinus c o n t o r t a 033 <\u00E2\u0080\u00A2 65 Zygadenus gramincus 078(1 + ) 89 Slope exposure does not appear to be a controlling factor as slopes of a l l exposures are present. The surface topography varies from concave through straight to convex. There was evidence of slight water erosion in most plots studied suggesting that some surface runoff takes place. However, erosion by wind appears to be of more importance as dust storms were frequently observed in areas occupied by this association. Wind erosion i s thought to be affecting the vegetation both by removal of the surface s o i l as well as by s o i l blast by wind-carried particles. The s o i l drainage i s considered to range from moderate to well drained. The hygrotope of this association i s rated from xeric up to submesic. The s o i l surface i s covered by a thin l i t t e r layer varying in extent from 66% to 86% of the total surface area. Mineral s o i l was exposed in a l l plots studied and in most plots a few rocks were present on the surface. This exposure of mineral s o i l may greatly increase s o i l moisture loss by evaporation. The s o i l i s developed from a parent material consisting of a thin layer of aeolian deposits overlying g l a c i a l d r i f t . Three horizons are recognizable. At the surface i s a chernozemic A horizon developed in fine material and varying from four inches to six inches in thickness. Sampled A horizons range texturally from sandy loams to loams. Coarse fragments are generally absent but occasionally a few gravels are present. The B horizon varies in thickness from five inches to 10 inches. There i s a substantial increase in the clay content of the B horizons and texturally they range from sandy loams to clay loams with clay loams and loams being the most prevalent. Coarse fragments ranging in size from gravels to stones are constantly present. Beneath the B horizon i s a light coloured C horizon which effervesces with dilute hydrochloric acid indicating the presence of carbonates, probably Table 33 Soil Texture Antennario (dimorphae) - Poetum secundae antennario - poetosum secundae juncetosum b a l t i c i imber of Plots 1 2 3 4 5 6 7 8 9 10 11 12 Lot No. 033 071 028 030 054 029 055 077 079 078 076 082 Horizon Textural class L SL SL L SiL SL SL SL SiL SiL SL SL Clay (%) 11 8 8 14 5 7 7 3 11 10 2 2 S i l t (%) 42 38 ' 44 46 53 35 43 39 59 50 48 38 Sand (%) 47 54 48 40 42 52 50 58 30 40 50 \u00E2\u0080\u00A2 60 Coarse fragments None None g. None g- None g. None None g- g- None Horizon Textural class L SiL CL CL L CL SL L SiL CL L SL Clay (%) 19 4 27 28 20 29 7 11 26 31 19 9 S i l t (%) 32 58 31 27 38 27 44 39 51 34 31 25 Sand (%) 49 38 42 45 42 44 49 50 23 35 50 66 Coarse fragments g. g.c. g.c. s. g.c.s. g.c.s. g.c. g.c.s. g- g- g.c. g.c.s. g-C.Horizon Textural class L L CL L L CL L L LS L SL SL Clay (%) 25 26 36 24 23 29 22 19 3 18 6 9 S i l t (%) 31 27 28 57 30 28 33 36 24 42 34 33 Sand (%) 44 47 36 39 47 43 45 45 73 40 60 58 Coarse fragments g.c. g.c.s. g.c.s. g.c.s. g.c.s. g.c.s. g.c.s. g.c.s. g.c.s. g.c.s. g.c.s. g.c.s 91 Table 34 Antennario (dimorphae) - Poetum secundae antennario - poetosum secundae juncetosum baltici Number of Plots 1 2 3 4 5 6 7 8 9 10 11 12 Plot No. 033 071 028 030 054 029 055 077 079 078 076 082 A Horizon C% 6.7 18.3 10.5 8.3 12.4 9.8 21.0 19.3 8.1 18.1 21.5 8.4 U\ .32 .9 .82 .64 .74 .87 .96 1.16 .37 .76 1.13 .31 C/N 20.9 20.3 12.8 12.9 16.8 11.3 21.9 16.6 21.9 23.8 19.0 27.1 P ppm 12 19.0 10.0 11.0 16.0 9.0 13.0 16.0 19.0 18.0 18.0 13.0 Na 1.74 .11 1.52 1.17 1.18 1.87 .12 .26 .22 .20 .14 .24 K 1.54 1.07 1.28 1.79 1.28 1.79 2.05 1.44 .87 .80 1.16 1.33 Ca 7.5 7.4 6.5 6.0 9.5 7.0 7.8 8.7 7.9 8.4 10.4 12.5 Mg 4.9 5.5 5.7 5.2 5.3 4.7 7.1 6.8 6.6 6.0 5.9 6.6 CEC 12.5 76.1 37.5 32.7 68.4 42.5 61.3 61.5 64.3 121.5 78.4 38.9 PH 7.3 7.3 6.9 6.6 7.0 6.5 6.6 6.6 6.7 6.9 6.8 6.5 B Horizon C% 5.8 3.4 0 2.1 6.3 0 4.8 4.9 7.1 2.3 2.8 8.3 N% .41 .19 .05 .17 .30 .05 .09 .24 .29 .14 .15 .32 C/N 14.1 17.9 0 12.3 21.0 0 53.3 20.4 24.5 16.4 18.7 25.9 P ppm 13 14.0 8.0 8.0 12.0 6.0 10.0 13.0 9.0 6.0 8.0 12.0 Na .91 .15 1.65 1.52 .97 1.30 .76 2.58 .52 .81 .22 .45 K .77 .59 .14 .22 1.09 .22 1.09 .94 .57 .89 .73 .89 Ca 7.5 6.3 6.0 4.5 7.5 6.0 5.3 22.4 8.3 5.8 8.6 11.8 Mg 5.8 6.5 9.6 7.3 6.4 7.4 11.2 32.8 10.7 11.0 7.8 12.4 CEC 16.4 24.7 11.3 19.5 31.4 21.6 26.4 26.3 33.8 18.1 25.8 41.6 pH 7.4 7.3 7.8 7.6 7.3 7.4 7.3 7.4 7.1 7.3 6.5 7.1 C Horizon C\u00C2\u00BB 0 1.0 0 0 0 0 0 0 3.3 2.8 0 0 N% .07 .07 .03 .26 .08 .05 .03 .10 .19 .17 .11 .07 C/N 0 14.3 0 0 0 0 0 0 17.4 16.5 0 0 P ppm 8.0 10.0 7.0 5.0 9.0 6.0 8.0 6.0 18.0 5.0 8.0 4.0 Na 2.09 .69 1.83 2.13 .74 2.00 .79 .63 1.17 1.22 .46 .59 K .09 .32 .13 .123 1.15 .13 1.35 .90 1.01 .70 .51 .64 Ca 11.0 9.3 8.0 10.5 10.5 8.5 10.2 5.3 13.5 5.1 13.0 12.2 Hg 10.7 5.8 11.8 12.6 9.3 7.0 13.1 12.2 12.2 11.1 17.3 11.8 CEC 10.7 18.3 12.8 24.7 19.3 8.4 16.3 13.8 38.1 12.7 15.4 13.1 pH 8.6 8.0 8.2 8.2 8.3 8.4 8.3 7.7 7.8 7.5 7.6 7.9 92 calcium carbonate. Texturally, the sampled C horizons range from loamy sands to clay loams with again loams and clay loams being the most prevalent. Coarse fragments were present i n a l l samples taken. These fragments are dominated by basalt suggesting that this material may be a prime source of the s o i l . A study of the root distribution in these profiles shows that most of the plant roots are concentrated i n the fine material of the A horizon. Root concentration decreases with depth and only a few roots are present in the C horizon. The s o i l reaction i s circumneutral i n the A horizon but becomes alkaline with depth. The A horizon contains a relatively high amount of organic matter as judged from measured carbon, which ranged from 6.7% to 21%. The humic acids released from this material may account for the relatively low pH values of the surface s o i l (6.5 to 7.3). Percent carbon and thus organic matter decreases down the prof i l e and i s generally absent i n the C horizon. Correspondingly the cation exchange capacity and phosphorus values are high in the A horizon and decrease down the p r o f i l e . Exchangeable cations are present in high amounts and increase in concentration with depth suggesting that there i s a movement of s o i l colloids down the prof i l e as a result of leaching. Calcium dominates the exchange complex in the A horizon, possibly due to the high calcium content of the incorporated organic matter. At lower levels magnesium i s present in higher amounts than calcium suggesting that the parent material i s magnesium rich. Carbon:nitrogen ratios are generally low, indicating that the organic matter contains sufficient nitrogen for decomposition and that a minimum of nitrogen competition between microflora and higher plants w i l l occur. Nitrogen i s present in high concentrations in the A horizon and 93 decreases to very Low dtuuaunts i n \u00C2\u00A3 horizon.. The Antennario - Poetum Sff^JIHIIjJtiff* X S ii'nii l^y^ffH^Tngyj^ tCO fae jjT\u00C2\u00BBg*yrmt\"aj j^l? pippTi T f 'to? tffei'ifr rrrijjirr.T r\u00C2\u00BB The s o i l s erf t h i s association are classified: into the Dark Brown . Cfayir|,|i/'a<||Tiit,|^r^\"a!W>^\"\" *j^wfjw'frt*iii.'fiTr^yn'r,g. Other constant 54 Poa j u n c i f o l i a 063(+. . + ) C Layer 55 Poa p r a t e n s i s 066(2. . + ) 56 P o t e n t i l l a p e n n s y l v a n i c a 095(1. . + ) 44 A l l i u m cernuum 066(2. . + ) 57 S a x i f r a g a o c c i d e n t a l i s 063(2, . + ) 45 Anemone m u l t i f i d a 094(1. . + ) 58 S i l e n e s c o u l e r i 094(+, . + ) 46 Chenopodium le p t o p h y l l u m 095(+. . + ) 59 S t i p a r i c h a r d s o n i i 098(3, .2) 47 C r e p i s a t r a b a r b a 063(1. . + ) D Layer 098(2 .1) 48 Descurainea p i n n a t a 063(+, . + ) 60 Bryum argenteum 49 Lepidium d e n s i f l o r u m 095(+. . + ) 61 C a l o p l a c a jungermanniae 098(2. .1) 50 Lithospermum r u d e r a l e 094(3. .2) 62 C a n d e l a r i e l l a v i t e l l i n a 094(3, .2) 51 Opuntia f r a g i l i s 095(1. .1) 63 C e t r a r i a e r i c e t o r u m 066(2 .1) 52 Poa f e n d l e r i a n a 098(2. . + ) 64 C l a d o n i a chlorophaea 063(3, .2) 53 Poa i n t e r i o r 098(2. .1) 65 P e l t i g e r a canina v a r . r u f e s c e n s 066(1, .1) 101 studied and three plots had rocks present on the s o i l surface. The s o i l i s developed from a parent material of aeolian deposits overlying g l a c i a l d r i f t . However, in the gully habitats the parent material may be mostly g l a c i a l d r i f t as the fine surface material appears to have been removed by surface runoff. Three distinct horizons are recognizable. The surface horizon i s a dark coloured chernozemic A horizon ranging in thickness from five inches to eight inches. It overlies a lighter coloured humified B horizon with a thickness range of six inches to 16 inches. The C horizon i s very light coloured and appears to be cemented possibly by calcium. It i s the only horizon which shows a reaction with hydrochloric acid, indicating the presence of carbonates, probably calcium carbonate. Texturally, the A horizon i s composed largely of sand and s i l t sized particles. A l l sampled A horizons are c l a s s i f i e d as sandy loams. In two plots, no coarse fragments were present in the A horizon; in the others a few gravels and cobbles were found. The sampled B horizons ranged from sandy loams to s i l t loams. The concentration of clay increases in the C horizon but in a l l plots sand composed over 40% of the sample with a maximum of 75% in plot 094. Coarse fragments ranging from gravels to stones were present in a l l samples. Because of the coarse texture, the soils are considered to be well drained and water movement from seepage w i l l be increased. A study of root distribution shows that the roots are largely con-centrated in the surface horizon. However, the roots of Balsamorhiza sagittata penetrate deeper and are present into the C horizon. The s o i l reaction i s circumneutral in the A horizon and becomes alkaline with increasing depth. Measured pH values of the C horizon ranged from 7.8 to 8.1. The higher alkalinity of the lower horizons may be due to the higher concentrations of basic cations. Table 37 Soil Texture Agropyro (spicati) - Balsamorhizetum saggitate Number of Plots 1 2 3 4 5 Plot No. 094 095 066 063 098 A Horizon Textural class SL Clay (%) 2 S i l t (%) 43 Sand (%) 54 Coarse fragments g.c. B Horizon Textural class SL Clay (%) 16 S i l t (%) 28 Sand (%) 55 Coarse fragments g.c.s. C Horizon Textural class LS Clay (%) 4 S i l t (%) 21 Sand (%) 75 Coarse fragments g.c.s, SL 6 47 47 g.c. SL 3 31 66 g.c.s. L 28 28 43 g.c.s, SL 1 38 61 None SL 5 33 61 g.c.s. SL 6 32 62 g.c.s. SL 3 45 52 None SL 2 39 59 g.c. L 23 31 46 g.c.s. SL 3 49 48 g-SL 6 34 40 g.c.s. CL 31 28 42 g.c.s. o to 103 Table 38 Soil Chemical Analysis Agropyro (spicati) - Balsamorhizetum sagittatae Number of Plots Plot No. 1 094 2 095 3 066 4 063 5 098 A Horizon C% N% C/N P ppm Na K Ca Mg CEC pH 7.3 .41 17.8 13.0 2.5 .57 9.5 12.5 28.6 6.8 15 13 1 8 6 41.7 7.4 3 48 2 0 21 4 2 1 22.0 1.14 19.3 13.0 .24 1.23 18.4 5.3 67.9 6.7 11.8 .46 25.7 23.0 .33 1.09 11.3 5.2 63.6 7.4 36. 1. 28. 1. 13, 1, 108, 6, 1 26 7 25.0 .39 03 3 6 3 6 B Horizon C% N% C/N P ppm Na K Ca Mg CEC PH 6.7 .31 21. 8, 1 14 5.7 26.4 7.5 6 0 17 05 3 4.8 .41 11.7 9.0 .22 1.11 12.1 7.6 22.8 7.5 3.1 .42 7-4 6.0 .16 .21 ,8 .1 ,1 .1 7 5 16 7 4.7 .32 14.7 12, 12 5 21 7 0 32 84 3 4 2 3 6.8 .29 23.4 15.0 .24 .30 18.9 3.9 65.0 7.2 C Horizon C% 1.4 0 0 0 0 N% .09 .05 .08 .04 .06 C/N 15.6 0 0 0 0 P ppm 7.0 8.0 6.0 8.0 10.0 Na .19 .35 .46 .47 .39 K .82 .82 .18 .12 .23 Ca 22.9 14.7 11.8 12.3 15.4 Mg 6.4 9.6 7.7 7.7 5.5 CEC 17.3 23.4 10.8 20.1 13.1 pH 7.8 7.9 8.0 8.1 7.7 104 Measured carbon content of the A horizon varies from 7.3% to 36.1% indicating that organic matter i s being incorporated into the s o i l . Lesser amounts of carbon are present in the B horizon and carbon was measureable in only one plot. The presence of carbon in the lower horizons suggests the movement of surface materials down the pro f i l e as a result of good drainage in these coarse textured s o i l s . The concentrations of available phosphorus, exchangeable potassium, and total nitrogen appear to be closely related to the amount of organic matter in the s o i l and decrease i n amounts with increasing depth. The carbon:nitrogen ratios are generally low suggesting that the organic matter in the s o i l contains sufficient nitrogen to satisfy the microbial populations and thus nitrogen w i l l be made available to higher plants. The cation exchange capacity i s high in the A horizon but decreases with depth due to the increased coarseness of the s o i l . Exchangeable calcium and magnesium are present in high concentrations and tend to increase in amount with depth, probably as a result of leaching. This association i s considered to be eutrophic. These soils are cl a s s i f i e d as Orthic Dark Brown Chernozems. Structurally the Agropyro - Balsamorhizetum sagittatae has four vegetation layers. The B^ layer i s present only in one plot with a percentage cover of 2%. The B 2 i s poorly developed and has a percentage cover ranging from 1% to 6%. The C and D layers are better developed with percentage covers ranging from 84% to 91% and 5% to 36% respectively. Pseudotsuga menziesii i s the only species present in the B^ layer and i t also occurs with low significance in the B 2 and C layers. The presence of Pseudotsuga menziesii i s indicative of the coarser soi l s and better moisture conditions of this habitat. Rosa acicularis, with an average species significance of 2.0, i s the dominant species of the B^ layer. The C layer i s dominated by Balsamorhiza sagittata with an average 105 species significance of 6.4. This species appears to be confined to coarser textured soi l s i n the Cariboo Zone. Other constant dominant species include: Agropyron spicatum, Antennaria umbrinella and Stipa columbiana. Festuca saximontana, Poa secunda, Achillea millefolium, Carex praticola, Artemisia frigida and Tragopogon dubius are present as constant non-dominant species. Non-constant species which are considered as important components of the characteristic combination of species for this association include: Antennaria rosea, Zygadenus gramineus, Lomatium macrocarpum, Cerastium arvense, Koeleria g r a c i l i s and Geum triflorum\u00C2\u00BB Arnica sororia, Dodecatheon pauciflorum, and Delphinium bicolor, occur only with a constancy of class II, but are exclusive to this association. Eriogonum heracleoides and Penstemon procerus are considered as characteristic species because of their high preference for this association. Tortula ruralis with an average species significance of 4.8 dominates the D layer. The only other bryophyte of importance i s Brachythecium salebrosum, whose presence indicates a moderately moist habitat. Cladonia pocillum, Peltigera malacea, and Cladonia pyxidata are the most important lichen species. In the Cariboo Zone the Agropyro - Balsamorhizetum sagittatae appears to be developed only on coarse textured, sandy s o i l s , where water i s available in the lower horizons. It has a history of burning as judged by the f i r e scars on trees in close proximity to sampled plots. This may effect the distribution of the association as light burning has been reported to increase vegetative reproduction of Balsamorhiza sagittata (Brayshaw 1955) . The association also has a history of moderate grazing which does not appear to have altered i t s structure. Fig. 12. The Agropyro - Balsamorhizetum sagittatae showing the characteristic dominance of Balsamorhiza sagittata and Agropyron spicatum. The association i s developed in a gully protected by continuous forest. Fig. 13. The Stipetum richardsonii showing the scattered occurrence of Pinus contorta and the proximity of continuous forest. The herb layer (C) i s dominated by Stipa richardsonii which forms almost closed stands. 107 4. Stipetum richardsonii (ref. Tables; 39, 40, 41, 42, 83, and Fig. 13) Characteristic Combination of Species Order Characteristic Species Agropyron spicatum Arabis h o l b o e l l i i Artemisia frigida Erigeron f l a g e l l a r i s Koeleria g r a c i l i s Tragopogon dubius Tortula ruralis Cladonia pocillum Cladonia pyxidata Alliance Characteristic Species Antennaria rosea Aster campestris Astragalus dasyglottis Carex praticola Cerastium arvense Festuca saximontana Juncus balticus Orthocarpus hispidus Poa pratensis Potentilla pennsylvanica Stipa columbiana Association Characteristic Species Astragalus tenellus Carex obtusata Geranium viscosissimum Stipa richardsonii Important Companion Species Pinus contorta Rosa acicularis Erigeron speciosus Bromus anomalus Geum triflorum Brachythecium salebrosum The Stipetum richardsonii i s found at elevations of greater than 3000 feet on the Fraser Plateau. It occurs either on protected slopes or in shallow gu l l i e s . The slope habitats can be divided into three types; in a l l of them the protection i s provided by continuous forest. These are: 108 Table 39 Stipetum r i c h a r d s o n i i P l o t Data Number of P l o t s 1 2 3 4 5 \u00E2\u0080\u00A2 ' 6 7 P l o t No. 027 026 024 035 021 050 038 P l o t Size (m2 ) 100 100 100 100 100 100 100 Date analyzed 25/7 23/7 22/7 31/7 21/7 12/8 3/8 1967 1967 1967 1967 1967 1967 1967 El e v a t i o n (ft) 3100 3160 3200 3320 3400 3480 3600 L o c a l i t y FP FP FP FP FP FP FP 51\u00C2\u00B042' 51\u00C2\u00B043' 5 1 0 4 3 . 51\u00C2\u00B047' 51\u00C2\u00B045' 51\u00C2\u00B047' 51\u00C2\u00B047' 122\u00C2\u00B039' 122\u00C2\u00B038' 122\u00C2\u00B038' 122\u00C2\u00B040' 122\u00C2\u00B042' 122\u00C2\u00B036' 122\u00C2\u00B037 Physiography Landform g u l l y R e l i e f shape . . . s t r a i g h t . . . . convex concave convex s t r a i g h t convex Exposure E NW NE SE NE NE E Slope gradient' (\u00C2\u00B0) 4 6 4 4 3 7 2 Layer coverage (%) Bj la y e r 3 - - - - - 8 B 2 l a y e r 1 1 2 3 - - 1 C laye r 100 98 98 92 95 96 98 D laye r 11 75 8 18 14 68 86 P l o t coverage Humus and l i t t e r 100 100 100 96 99 98 98 Mineral s o i l - - - 4 1 2 2 S o i l Hygrotope Trophotope Erosion Drainage Horizon depth (in) A B C n i l ...(subhygric) - submesic - (subxeric)... permesotrophic - eutrophic n i l n i l s l i g h t n i l n i l water n i l 0-5 0-6 0-5 5-12 6-17 5-13 12-27+ 17-30+ 13-26+ . w e l l . 0-5 5-14 14-30+ 0-4 0-7 0-6 4-9 7-16 6-14 9-24+ 16-34+ 14-24+ Parent ma t e r i a l t h i n a e o l i a n deposit over g l a c i a l d r i f t ? 109 Table 40 Stipetum richardsonii Number of Plots 1 2 3 4 5 6 7 Plot No. 027 026 024 035 021 050 038 Plot~Size (m2) 100 100 100 100 100 100 100 Elevation (ft) 3100 3160 3200 3320 3400 3480 3600 sub Avg Species B Layer layer Constancy Significance 1 Pinus contorta 1 3.+ _ _ - - _ _ III 0.4 2 - 3.+ 3.+ 2.+ - - - 1.1 2 Rosa a c i c u l a r i s 2 - 2.+ - 3.+ - - - V 0.9 C Layer 3 Stipa richardsonii 9.7 9.6 9.7 6.2 8.4 8.5 9.6 V 8.3 4 Carex praticola 3.2 3.2 2.1 5.3 4.2 3.1 4.3 V 3.4 5 Cerastium arvense 3.3 3.3 3.2 2.2 3.1 2.1 2.1 V 2.3 6 Anemone multifida 1.+ 2.1 2.+ 4.1 2.2 1.+ 2.1 V 2.0 7 Agropyron subsecundum 2.1 - 3.2 2.1 2.2 2.1 3.1 V 2.0 8 Stipa columbiana - 2.2 2.1 1.1 2.1 4.3 2.2 V 1.9 9 Erigeron speciosus 2.+ 3.1 2.+ - 2.+ 2.+ 2.1 V 1.9 10 Antennaria rosea 2.2 2.2 2.1 2.2 2.3 1.1 2.1 V 1.7 11 Carex obtusata 2.2 2.2 3.2 - 1.+ 2.1 2.2 V 1.7 12 Taraxacum o f f i c i n a l e 1.+ 1.2 3.2 2.+ 2.2 1.+ 1.1 V 1.6 13 Achillea millefolium 2.+ 1.+ 1.1 2.1 1.+ 1.+ 1.+ V 1.4 14 Koeleria g r a c i l i s 1.1 2.1 + .+ 2.1 1.+ 1.1 2.1 V 1.4 15 Aster campestris 1- + 1.1 1.+ 1.1 2.1 2.1 1.1 V 1.3 16 Artemisia f r i g i d a + .+ 1.+ + .+ 1.+ 2.1 1.+ 2.2 V 1.1 Rosa a c i c u l a r i s 1.+ 1.+ + .+ 1.+ + .+ 3.+ + .+ 1.1 17 Erigeron f l a g e l l a r i s + .+ 1.+ 1.+ 2.1 1.+ - 1.+ V 0.9 18 Solidago multiradiata 2.1 - 2.1 - 3.2 4.2 3.1 IV 2.0 19 Astragalus dasyglottis + .+ - 2.1 3.2 3.+ - 3.1 IV 1.6 20 Bromus anomalus 2.1 - 3.2 3.1 2.2 - 1.1 IV 1.6 21 P o t e n t i l l a pennsylvanica 1.+ - 2.1 + .+ 3.2 - 1.+ IV 1.1 22 Tragopogon dubius + .+ - + .+ 1.+ 1.+ + .+ - IV 0.5 23 Geum triflorum 2.1 1.+ - - 3.+ 2.1 - III 1.1 24 Agropyron spicatum - 2.2 - 1.+ 3.2 - 1.2 III 1.0 25 Orthocarpus hispidus + .+ - 1.+ - 1.+ 3.1 - III 0.8 26 Astragalus tenellus - 1.1 - 1.1 1.+ 2.1 - III 0.7 27 Geranium viscosissimum + .+ - - 2.2 - - 2.2 III 0.6 Pinus contorta 1.+ 1.+ 1.+ 1.+ - - - 0.6 28 Poa pratensis 1.1 - 1.+ - 2.1 - - III 0.6 29 Astragalus miser - 2.2 - - 4.2 - - II 0.9 30 Agoseris glauca - - - 2.+ - - 2.+ II 0.6 31 Galium boreale - 2.+ - - 2.2 - II 0.6 32 Elymus glaucus - - - - - ' 1.1 2.1 II 0.4 33 Heuchera c y l i n d r i c a 2.1 - - - - - 1.+ II 0.4 34 Lithospermum ruderale -' - - 1.1 - - 2.1 II 0.4 35 Zygadenus gramineus - - - - 1.+ - 1.+ II 0.4 36 Festuca saximontana - - - 1.2 1.1 - - II 0.3 37 Chenopodium leptophyllum - - - + .+ + .+ - - II 0.1 38 Eriogonum heracleoides + .+ - + .+ - - - - II . 0.1 39 Lomatium macrocarpum - - - - + .+ + .+ - II 0.1 40 Silene scouleri - - + .+ + .+ - - - 1 1 0.1 D Layer (Bryophytes) 41 Brachythecium salebrosum 4.3 8.7 3.2 4.3 3.2 7.3 8.7 v 5.3 42 Tortula ruralis. - 2.1 3.2 3.2 5.3 3.2 3.2 V 2.7 43 Polytrichum juniperinum 2.1 2.1 - 1.+ - - 4.3 III 1.3 4 4 Ceratodon purpureus - - 2.1 - 2.1 1.+ 2.2 III 1.0 45 Eurhynchium pulchellum 1.1 1.1 - 1.1 - 1.1 - III 0.6 (Lichens) 46 Cladonia pocillum 3.2 3.3 2.2 4.2 2.1 3.1 2.1 V 2.7 47 Peltigera canina var. rufescens 1.1 3.2 3.2 2.1 1.1 3.1 3.2 V 2.3 4 8 Cladonia pyxidata - \u00E2\u0080\u0094 ~ 2.2 - 3.2 II 0.7 TOTAL SPECIES ( i n c l . sporadics) 33 28 34 39 38 35 34 Sporadic species B Layer 49 Amelanchier a l n i f o l i a C Layer 50 Arabis h o l b o e l l i i 51 C a s t i l l e j a miniata 52 Danthonia spicata 53 Juncus balticus 54 Lathyrus ochroleucus 55 Poa i n t e r i o r 56 Sedum stenopetalum 026(2.+) 035(1.+) 050(1.+) 021(1.1) 021(3.1) 035(+.+) 024(1.+) 035(+.+) 57 Sisyrinchium sarmentosum 58 V i c i a americana D Layer 59 Hedwigia c i l i a t a 60 Hypnum revolutum 61 Drepanocladus uncinatus 62 Cladonia cariosa 63 Cladonia chlorophaea 64 Peltigera lepidophora 65 Peltigera malacea 024(1.+) 027(+.+) 035(1.+) 050(1.1) 050(1.1) 050(1.1) 050(2.1) 035(2.1) 038(2.2) 110 (1) Habitats which occur on the edge of continuous exposed grassland slopes next to the forest border. These are the most common habitats of the Stipetum richardsonii. (2) Habitats which are park-like openings in the continuous forest. (3) Habitats on open sloping ridges bordered by gullies containing forest. The gully habitats extend downslope from forested ridges and dissect the exposed slopes occupied by the Antennario - Poetum secundae. Thus the Stipetum richardsonii i s always in close proximity to the continuous forest and i s regarded as a forest boundary association. Because of i t s topographic position the effect of wind i s negligible in this association which results i n a deep snow accumulation. This i s believed to be an important source of available moisture at the beginning of the growing season. The Stipetum richardsonii i s non-specific with reference to slope exposure and occurs on gentle slopes with gradients ranging from 2\u00C2\u00B0 to 7\u00C2\u00B0. The surface topography varies from concave to convex. Generally, there i s no evidence of surface erosion except for the gully habitats where slight water erosion may occur. The s o i l surface i s covered by a thick l i t t e r layer ranging in extent from 96% to 100% of the available surface area. This l i t t e r may substantially reduce moisture loss by evaporation from the s o i l surface as well as increase the surface moisture retention. The soils are well drained and appear to benefit from temporary seepage and runoff. The hygrotope of the Stipetum richardsonii i s considered to vary from subhygric for short periods in the spring following snow melt, to submesic for most of the growing season, and then be reduced to subxeric for a short period in the late summer. The s o i l has an A,B,C, horizon sequence and i s developed from a parent material of thin aeolian deposits overlying g l a c i a l d r i f t . Although, in plots 027, 026, 050, the parent material may be only g l a c i a l d r i f t as the textural I l l difference between the surface and subsurface horizons is small. The A horizon i s dark brown in color and varies i n thickness from four inches to seven inches. The B horizon is lighter in colour with a thickness of five to 11 inches and overlies a light coloured C horizon which appears to be cemented, possibly by calcium. The C horizon also shows a strong efferve-scence with hydrochloric acid, indicating the presence of carbonates, probably calcium carbonate. The texture of the sampled A horizons ranged from sandy loams to s i l t loams with sandy loams being the most prevalent. Coarse fragments are generally absent from the A horizon except for three plots i n which gravels were found. In the lower horizons there i s an increase i n clay content over that of the A horizon, with the maximum clay concentration present i n the C horizon. Here, measured clay ranged from 23% to 39%. The B and C horizons contain coarse fragments ranging in size from gravels to stones. The higher clay content and unsorted material of these horizons i s characteristic of the g l a c i a l d r i f t . Texturally the sampled B horizons ranged from sandy loams to clay loams and the sampled C horizons ranged from loams to clay loams. In both horizons loams are the dominant textural class. Plant roots are concentrated in the fine material of the A horizon with a lesser number present in the B horizon. Very few roots reach as low as the cemented C horizon. Exchangeable cations are present in moderate amounts with calcium dominating the exchange complex. The highest amounts of calcium and magnesium are present i n the C horizon suggesting a movement down the p r o f i l e of these cations. Calcium i s also present in relatively high amounts in the A horizon which could be coupled with calcium release form the decomposing organic matter. Percentage carbon and thus organic matter i s highest i n the A horizon and decreases down the p r o f i l e . The C horizon contains no measureable carbon. Table 41 Soil Texture Stipetum richardsonii Number of Plots Plot No. A Horizon Textural class Clay (%) S i l t (%) Sand (%) Coarse fragments B Horizon Textural class Clay (%) S i l t (%) Sand (%) Coarse fragments C Horizon Textural class Clay (%) S i l t (%) Sand (%) Coarse fragments 1 027 2 026 3 024 4 035 5 021 6 050 7 038 SL SL SL L SL SiL L 6 3 7 12 6 3 14 19 47 49 40 45 53 38 75 50 44 48 49 44 48 g. g. None None None g- None L SL L L L CL L 23 17 20 23 16 30 23 34 24 30 33 35 29 37 43 59 50 44 49 41 43 g.c. g.c.s. g.c. g.c. g. g.c.s. g.c. L L L L CL L SiCL 25 23 25 27 33 24 39 33 30 26 30 30 40 44 42 47 49 43 37 36 17 g.c.s. g.c.s. g.c.s. g.c. g.c.s. g.c.s. g.c.s. Number of Plots 1 Plot No. 027 A Horizon c% 7 N% \u00E2\u0080\u00A241 C/N 17.1 P ppm 6.0 Na 1.04 K 1.03 Ca 7.0 Mg 6.0 CEC 38.5 pH 6.9 B Horizon c% 0 N% .07 C/N 0 P ppm 4.0 Na 1.26 K .33 Ca 5.5 Mg 7.1 CEC 12.4 pH 7.3 C Horizon C% 0 N% .03 C/N 0 P ppm 4.0 Na 1.35 K .14 Ca 8.5 Mg 9.9 CEC 11.3 pH 8.3 Table 42 Soil Chemical Analysis Stipetum richardsonii 2 3 4 026 024 035 8.9 6.3 8.7 .74 .42 .31 12.0 15.0 28.1 3.0 6.0 11.0 .83 .96 .10 1.28 1.54 7.05 8.0 5.5 10.0 4.8 4.9 5.8 40.9 25.9 36.7 6.5 6.3 6.7 0 1.0 5.2 .07 .11 .24 0 9.1 21.7 4.0 3.0 4.0 .96 .52 .44 .20 .26 6.41 6.0 4.5 8.0 6.5 6.6 9.7 13.6 15.4 23.5 7.4 7.5 7.6 0 0 0 .03 .06 .08 0 0 0 3.0 2.0 5.0 1.17 .56 .48 .14 .15 .28 8.0 5.5 19.5 6.6 6.6 14.5 18.0 18.3 16.3 8.1 8.4 8.4 113 5 6 7 021 050 038 14.3 34.1 17.5 .83 1.08 .84 17.2 31.6 20.8 12.0 23.0 22.0 .23 .10 .47 .77 2.24 6.41 9.6 15.0 15.0 4.8 7.6 5.9 43.8 98.5 61.7 6.8 7.2 6.8 6.4 3.4 4.0 .51 .09 .14 12.5 37.8 28.6 11.0 12.0 7.0 1.33 .79 .44 .67 1.6 ' 6.56 6.9 6.8 11.0 7.5 11.1 7.5 28.4 26.3 31.8 6.8 7.6 7.6 0 0 0 .06 .02 .08 0 0 0 9.0 8.0 5.0 1.29 1.69 .48 .15 .15 .28 2.3 15.0 19.5 6.5 9.7 14.5 12.9 12.0 16 .\"3 8.2 8.1 8.4 114 Similarly total phosphorus, cation exchange capacity and exchangeable potassium are highest i n the A horizon and decrease with depth. The carbon:nitrogen ratios are generally low suggesting that nitrogen i s available for higher plants. The nitrogen content i s highest i n the A horizon and decreases to trace amounts in the C horizon. The reaction of the A horizon i s circumneutral with measured pH values ranging from 6.3 to 7.2. The s o i l reaction becomes more alkaline with depth and pH values for the C horizon range from 8.1 to 8.4. This alkaline reaction i s probably due to the higher concentration of basic cations. The Stipetum richardsonii i s considered to be permesotrophic to eutrophic. The soils of this association are c l a s s i f i e d as Orthic Dark Brown Chernozems. Structurally the Stipetum richardsonii consists of four vegetation layers. The B^ layer was present only in two plots and the B 2 has a percentage cover of only 1% to 3%. Thus the shrub layers are considered to be poorly developed. The C layer i s very well developed and has a percentage cover ranging from 92% to 100%. The D layer i s variably developed and ranges in cover form 8% to 86%. Pinus contorta and Rosa acicularis are the only species present in the B^ and B2 layers. Pinus contorta i s thought to be here because the snow accumulation and generally moist habitat w i l l favour the establishment of tree seedlings. Stipa richardsonii dominates the C layer with an average species significance of 8.3. It i s largely responsible for the physiognomy and cover of this layer. Carex praticola i s a constant subdominant with an average species significance of 3.4. Both species appear to favour moist habitats. Constant nondominants indicative of moist conditions include: Anemone multifida, Agropyron subsecundum, Erigeron speciosus, Rosa acicularis, Stipa columbiana 115 and Carex obtusata. Antennaria rosea, Koeleria g r a c i l i s , Aster campestris, Artemisia f r i g i d a and Astragalus dasyglottis are constant grassland species occurring with low species significances. Non-constant species considered as indicative of the moist habitat conditions of this association are: Poa pratensis, Solidago multiradiata, Bromus anomalus, Geum triflorum and Orthocarpus hispidus. Erigeron f l a g e l l a r i s , Potentilla pennsylvanica and Agropyron spicatum occur with low species significance i n the more exposed parts of the association. Astragalus tenellus and Geranium viscosissimum, both occurring with low species significance, are considered as characteristic species because of their preference for this association. The D layer i s composed largely of one species, Brachythecium salebrosum which i s present with an average species significance of 5.3. This species forms a very extensive mat under the Stipa richardsonii l i t t e r and i s indicative of the moist s o i l surface. Tortula r u r a l i s , Cladonia pocillum, which are more characteristic of exposed dry habitats, are present here, with low species significance. The only other constant species of this layer i s Peltigera canina var. rufescens. The Stipetum richardsonii has a history of only light grazing i n which certain plants are selected. Agropyron spicatum and Rosa acicularis appear to be heavily grazed. Stipa richardsonii, however, i s hardly grazed at a l l possibly because of i t s sharply awned f r u i t s . Parts of this association also appear to have a history involving f i r e as judged by the presence of charcoal i n the s o i l profiles. The occurrence of Pinus contorta here, may be / related to this f i r e history, as Pinus contorta regenerates quickly in suitable habitats following f i r e . Agropyrion spicati 1. Agropyretum spicati (ref. Tables; 43, 44, 45, 46, 83, and Fig. 14) 116 Characteristic Combination of Species Order Characteristic Species Agropyron spicatum Artemisia frigida Arabis h o l b o e l l i i Koeleria g r a c i l i s Tragopogon dubius Tortula ruralis Cladonia pocillum Cladonia pyxidata Alliance Characteristic Species Lithospermum ruderale Lomatium macrocarpum Calochortus macrocarpus Opuntia f r a g i l i s Diploschistes canadensis Physcia muscigena Association Characteristic Species Crepis atrabarba Heuchera cylindrica Linum lewisii Zygadenus gramineus Peltigera lepidophora Important Companion Species Artemisia campestris The Agropyretum spicati occurs at elevations below 3000 feet on the Fraser Plateau and thus i s restricted to the major river valleys. It i s formed on the steep sides of water eroded ravines, on exposed slopes and on ridges. The sampled plots were located on slopes with northerly exposures and gradients ranging from 23\u00C2\u00B0 to 4 3 0 . The northerly exposures of these habitats cause them to be microclimaticaly cooler and more moist than the neighbouring habitats. They also remain snow covered longer in the spring (see page246 ). The surface topography ranges from straight to convex. So i l surface i s covered by a thick layer of Agropyron spicatum l i t t e r which w i l l aid in s o i l moisture conservation by decreasing surface evaporation. However, some mineral s o i l was exposed in a l l plots sampled. The hygrotope of this association is rated as subxeric. Table 43 Agropyretum spicati Plot Data Number of Plots 1 2 3 4 5 Plot No. 087 060 064 043 031 Plot Size (m2) 100 100 100 100 100 Date analyzed 24/7 6/6 16/6 8/8 29/7 1968 1968 1968 1967 1967 Elevation (ft) 1800 2120 2200 2210 2400 Locality FP FP FP FP FP 51\u00C2\u00B049' 51\u00C2\u00B048* 51\u00C2\u00B050' 51\u00C2\u00B048' 51\u00C2\u00B050' 122\u00C2\u00B033' 122\u00C2\u00B033' 122\u00C2\u00B032' 122\u00C2\u00B030\" 122\u00C2\u00B032\" Physiography Landform side of exposed ravine slope Relief shape straight convex concave straight convex NW N NW NW NW Slope gradient (\u00C2\u00B0) 43 23 28 36 27 Layer coverage (%) A3 layer - 12 - - -B2 layer - 2 1 - -C layer 88 84 88 91 70 D layer 40 39 35 32 3 Plot coverage (%) Humus and l i t t e r 94 96 97 94 76 Mineral s o i l 6 4 3 6 24 Soil Hygrotope .......... ......... Trophotope ......... . eutrophic Erosion slight water Drainage .......... ......... Horizon depth (in) A 0-8 0-7 0-8 0-13 0-5 B 8-14 7-19 8-19 13-24 5-10 C 14-34+ 19-36+ 19-26+ 24-37+ 10-24+ Parent material aeolian deposit aeolian - \u00E2\u0080\u00A2 \u00E2\u0080\u00A2 aeolian deposit over over gla- deposit gl a c i a l d r i f t c i a l d r i f t 118 Table 44 Agropyretum s p i c a t i Number of Plots Plot No. Plot Size (m2) Elevation (ft) B Laver 1 2 3 4 5 087 060 064 043 031 100 100 100 100 100 1800 2120 2200 2210 2400 sub laver Constancy Avg Species S i g n i f i c a n c e 1 Artemisia t r i d e n t a t a 2 - 2.1 2.+ - - II 0.8 C Laver 2 Agropyron spicatum 8.2 8.4 8.3 9.7 8.6 V 8.2 3 Artemisia f r i g i d a 2.1 3.2 3.1 3.2 3.2 V 2.8 4 Heuchera c y l i n d r i c a 2.1 4.2 4.2 1.+ 2.1 V 2.7 5 Lomatium macrocarpum 2.1 3.+ 3.+ 2.+ 3.+ V 2.6 6 Zygadenus gramineus 2.+ 2.+ 1.+ 1.+ 2.+ V 1.6 7 Arabis h o l b o e l l i i 1.1 1.+ 1.1 1.+ 1.+ V 1.0 8 Taraxacum o f f i c i n a l e + .+ + .+ 2.+ 1\u00E2\u0080\u009E+ 1.+ V 1.0 9 Tragopogon dubius + .+ 1.+ 1.+ + .+ 2.+ V 1.0 10 K o e l e r i a g r a c i l i s - 3.1 2.1 3.3 4.3 IV 3.0 11 Solidago multiradiata 3.+ 1.+ 2.1 2.2 - IV 1.6 12 Crepis atrabarba - 2.+ 2.+ 2.1 1.+ IV 1.4 13 Lithospermum ruderale - 1.1 2.1 1.1 2.1 IV 1.0 14 Antennaria umbrinella 3.2 5.2 4.3 - - III 2.4 15 Artemisia campestris - - 2.1 2.1 2.+ III 1.2 16 Linum l e w i s i i - - 1.1 + .+ 1.+ III 0.5 17 Antennaria rosea - - 1.1 3.2 - II 1.0 18 Geum t r i f l o r u m 2.1 2.2 - - - II 0.8 19 Opuntia f r a g i l i s - - - 2.1 3.2 II 0.8 20 Sedum stenopetalum 1.+ 1.+ - - - II 0.4 21 Calochortus macrocarpus 2.+ - - - II 0.4 22 A c h i l l e a m i l l e f o l i u m 1.+ + .+ - - - II 0.3 D Laver 23 S e l a g i n e l l a densa 4.2 - 2.2 - II 1.2 (Bryophytes) 24 T o r t u l a r u r a l i s 4.3 3.2 4.2 3.2 2.2 V 3.2 25 Ceratodon purpureus 3.2 2.1 1.1 2.1 1.+ V 1.8 26 Eurhynchium pulchellum 4.1 - 3.2 + .+ - III 2.2 (Lichens) 27 Cladonia pocillum 4.2 5.3 5.3 5.2 2.1 V 4.2 28 D i p l o s c h i s t e s canadensis 2.1 2.1 2.1 2.1 3.1 V 2.2 29 P e l t i g e r a canina var. rufescens 3.2 3.2 - 2.2 - I I I 1.6 30 P e l t i g e r a lepidophora - 2.2 2.1 2.2 - III 1.2 31 Cladonia pyxidata - 4.2 4.2 - - II 1.6 32 Cladonia chlorophaea 3.2 2.2 - - - II 1.0 33 P e l t i g e r a malacea 2.2 3.1 - - - II 1.0 34 Ochrolechia u p s a l i e n s i s 1.1 1.+ - - II 0.4 TOTAL SPECIES ( i n c l . sporadics) 30 28 27 25 21 Sporadic species A Layer 35 Pseudotsuga menziesii C Laver 36 Agoseris glauca 37 A l l i u m cernuum 38 Antennaria dimorpha 39 Chenopodium leptophyHum 40 Chrysothamnus nauseosus 060(3. + ) 064(1.+) 087 (2. + ) 031(2.1) 064(+. + ) 043 (2.. + ) 41 Erigeron speciosus 42 Poa secunda 43 Saxifraga o c c i d e n t a l i s 44 Woodsia oregana D Layer 45 Amblystegium serpens 46 Physcia muscigena 47 Thrombium epigaeum 060(2. + ) 031(1.1) 087(2.+) 087 (1.1) 087(1.+) 087(2.+) 031(1.+) 119 The s o i l has an A,B,C, horizon sequence and i s formed from a parent material of aeolian deposits overlying g l a c i a l d r i f t . Because of the high percentage of sand in the lower horizons, the d r i f t may actually be outwash material. Plot 060, however, appears to be formed only on aeolian material as no g l a c i a l d r i f t was encountered to a depth of 40 inches. The A horizon, which varies in thickness from five to 13 inches, i s well melanized and contains no coarse particles. Texturally the sampled A horizons are cl a s s i f i e d as s i l t y loams or sandy loams. The B horizon has a thickness ranging from five inches to 12 inches and i s lighter i n colour than the A horizon because of a lower organic matter accumulation. Sand sized particles are the dominant fraction in sampled B horizons, which range texturally from sands to sandy clay loams. Coarse fragments were present in three samples. The C horizon i s very light coloured and generally devoid of organic matter. It effervesces strongly with hydrochloric acid indicating the presence of carbonates, probably calcium carbonate. Sampled C horizons were composed largely of sand sized particles and are c l a s s i f i e d as sands, sandy loams or s i l t loams. Gravels, cobbles and stones were present i n a l l profiles except 060. The coarse fragments present are mostly basalts and other lavas; these w i l l provide an alkaline parent material. Serpentine was also present and this w i l l release magnesium on weathering which may account for the high magnesium values of the s o i l . Cation exchange capacity i s high in the A horizon because of the relatively large amounts of incorporated organic matter (measured carbon ranges from 4.6% to 13.1%). Cation exchange capacity decreases with depth corresponding to the increased coarseness of the texture of the lower horizons. Exchangeable cations are present in high amounts with calcium dominating the exchange complex. The highest concentrations of calcium and magnesium occur i n the C layer indicating a movement of these elements down the p r o f i l e . The high calcium concentrations Number of Plots Plot No. A Horizon Textural class Clay (%) S i l t (%) Sand (%) Coarse fragments B Horizon Textural class Clay (%) S i l t (%) Sand (%) Coarse fragments C Horizon Textural class Clay (%) S i l t (%) Sand (%) Coarse fragments Table 45 Soil Texture Agropyretum spicati 1 087 2 060 3 064 4 043 5 031 SL SiL SL SiL SL 2 10 2 4 3 35 53 50 51 45 63 37 48 45 52 * \u00E2\u0080\u00A2 None S SL SL SL SCL 1 18 3 8 23 13 32 47 38 25 86 51 50 55 52 gravels None None g. g.c. S SiL SL SL SL 1 13 6 11 14 4 54 24 19 13 96 32 70 70 73 g.c.s. None g. g.c. g.c.s. to o 121 Number of Plots Plot No. Table 46 Soil Chemical Analysis Agropyretum spicati 1 087 2 060 3 064 4 043 5 031 A Horizon C% N% C/N P ppm Na K Ca Mg CEC PH 13.1 .42 31.2 26.0 .33 .29 12.8 4.8 57.6 7.4 11.8 .53 22. 13. ,3 .0 .12 .61 8.8 5.7 43.6 7.0 4.7 .29 16.2 7.0 .12 .45 7.2 4.7 12.9 6.9 22 12 6 11 4 41 7 .4 .28 .9 .0 .13 .41 ,0 .3 .6 .3 4.6 .26 17.7 9.0 1.30 1.03 6.5 4.9 16.3 7.7 B Horizon C% N%' C/N P ppm Na K Ca Mg CEC PH 1.3 .17 7.6 2.0 .28 .22 11.9 4.1 4.9 8.2 12 15 6 10 5 19 7 ,7 ,30 ,3 .0 .61 .37 .1 ,9 ,7 .8 3.1 .42 7.4 6.0 .17 .21 11.4 6.3 16.1 7.7 2.1 .09 23.3 8.0 .39 \u00E2\u0080\u00A2\u00E2\u0080\u00A2. 23 17. 5. 22. 8. 16 8 1 9 7 12 7 .7 .16 ,9 ,0 .22 .29 .0 .8 .2 .9 C Horizon C% 0 2.3 0 0 0 N% .05 .15 .08 .03 .06 C/N 0 15.3 0 0 0 P ppm 3.0 5.0 4.0 5.0 3.0 Na .41 4.20 .57 .57 1.61 K .17 .61 .18 .25 .17 Ca 15.8 11.8 19.6 21.5 9.0 Mg 4.2 7.1 7.5 9.8 10.2 CEC 3.4 18.3 5.0 8.9 6.8 pH 8.3 8.4 8.4 8.5 8.4 122 support the idea that the carbonates present are probably calcium carbonate. Exchangeable sodium i s present i n low amounts so probably w i l l not interfere with the exchange complex. The highest concentration of exchangeable potassium i s in the A horizon and this cation decreases in amount with depth. Similarly the concentrations of total phosphorus and total nitrogen decrease from the surface down the p r o f i l e . A l l of these elements appear to be closely correlated with the amount of organic matter i n the s o i l which also decreases with depth (organic matter i s estimated from the measured carbon). The carbon:nitrogen ratios are sufficiently high in some of the sampled A horizons to suggest that a competition for nitrogen between the microflora and the higher plants may occur. However, carbon:nitrogen ratios in the B horizons are generally very low, thus nitrogen i s probably available for higher plants. The s o i l reaction i s neutral to slig h t l y alkaline in the A horizon with measured pH values ranging from 6.9 to 7.7. Alkalinity increases with depth and pH values of the C horizon range form 8.3 to 8.5. The higher pH values of the C horizon are most lik e l y due to the higher concentrations of basic cations, particularly calcium. These soil s are considered to be eutrophic because of the high ava i l a b i l i t y of nutrients and the favourable pH. The soils are cl a s s i f i e d as Orthic Brown Chernozems. A study of the root distribution showed that roots were concentrated in the A and B horizons with only a few roots extending into the C horizon. The Agropyretum spicati generally consists of two vegetation layers, a well developed C layer and a moderately well developed D layer. However, occasionally a poorly developed B layer or even an A^ layer may be present. In sampled plots, the C layer had a percentage cover of 70% to 91% and the D layer a cover of 3% to 40%. The A layer, when present, (plot 060) i s composed of Pseudotsuga menziesii which occurs with low species significance. Generally P. menziesii 123 grows poorly in these dry habitats with fine textured s o i l s . The B layer, present only in two plots, was composed solely of Artemisia tridentata with very low species significance. Agropyron spicatum dominates this association with an average species significance of 8.2, and i s largely responsible for the physiognomy and structure of the C layer. Heuchera cylindrica, Zygadenus gramineus, Crepis atrabarba and Linum lewisii are considered as characteristic species because of their high preference for this association. Other constant species occurring with low significance include; Artemisia frigida, Lomatium macrocarpum, Tragopogon dubius, Koeleria g r a c i l i s . Lithospermum ruderale, Artemisia campestris, Opuntia f r a g i l i s , Sedum stenopetalum and Calochortus macrocarpus a l l occur as non-constants with low significance and are characteristic of the dry exposed habitat. Cladonia pocillum with an average species significance of 4.2 and Tortula ruralis with an average species significance of 3.2 dominate the D layer. Diploschistes candensis and Ceratodon purpureus are the only other constant D layer species. The presence of Eurhynchium pulchellum indicates the moist s o i l surface conditions existing under the l i t t e r layer. Peltigera lepidophora i s the only non-vascular species considered as characteristic for this association. The Agropyretum spicati i s generally very heavily grazed in the Cariboo Zone which i s resulting in a reduction in the area covered by this association. However, on very steep slopes the grazing i s considerably less and here, the association appears to be only moderately grazed. Communities, f l o r i s t i c a l l y very similar to the Agropyretum spica t i , were observed on steep open slopes with southerly exposures in the forested areas. These slopes were always bordered by associations of the Pseudotsugetalia menziesii. None of these communities were sampled in the present study. 124 Pig. 14. The Agropyretum spicati shown here as developed on a steep slope i n near virgin condition. The association i s characterized by an almost complete cover of Agropyron spicatum. Fig. 15. The Agropyro - Artemisietum tridentatae showing the dominance of Artemisia tridentata which averages between three and five feet in height. The association i s developed on a level river terrace on a fine textured regosolic s o i l . Agropyron spicatum and Artemisia frigida dominate the C layer. 125 2. Agropyro (spicati) - Artemisietum tridentatae (ref. Tables; 47, 48, 49, 50, 83, and Fig. 15) Characteristic Combination of Species Agropyron spicatum Arabis h o l b o e l l i i Artemisia frigida Erigeron f l a g e l l a r i s Koeleria g r a c i l i s Tragopogon dubius Tortula ruralis Cladonia pocillum Cladonia pyxidata Alliance Characteristic Species Calochortus macrocarpus Comandra umbellata Lithospermum ruderale Lomatium macrocarpum Opuntia f r a g i l i s Diploschistes canadensis Lecidea decipiens Physcia muscigena Association Characteristic Species Artemisia tridentata Artemisia dracunculus Sisymbrium l o e s e l i i Candelariella v i t e l l i n a Important Companion Species Stipa comata The Agropyro - Artemisietum tridentatae occurs near the bottoms of the major valleys and i s best developed at elevations below 2000 feet. It i s usually formed on gently sloping river terraces located at the base of steep valley slopes. Fine textured s o i l i s constantly deposited on these terraces as a result of wind and water erosion of the slopes above. TheQ association also occurs on steep ravine sides, but i s not as well developed on such sites. The association reaches i t s best development on northerly exposures and Artemisia tridentata was observed to grow only marginally on slopes with southerly exposures. 126 Table 47 Agropyro ( s p i c a t i ) - Artemisietum tr i d e n t a t a e Plot Data Number of Pl o t s P l o t No. P l o t Size (m2) Date analyzed El e v a t i o n (ft) L o c a l i t y Physiography Landform R e l i e f shape Exposure Slope gradient (\u00C2\u00B0) Layer coverage (%) B2 la y e r C layer D l a y e r P l o t coverage (%) Humus and l i t t e r Mineral s o i l Decaying wood S o i l Hygrotope Trophotope Erosion Drainage Sample depth (in) 1 2 3 Parent material 1 2 3 4 5 6 039 040 047 046 041 045 400 400 400 400 400 400 5/8 5/8 10/8 10/8 6/8 9/8 1967 1967 1967 1967 1967 1967 1540 1540 1600 1620 1800 2020 FP FP FP FP FP FP 51\u00C2\u00B050' 51\u00C2\u00B050' 51\u00C2\u00B048' 51\u00C2\u00B048' 51o49. 51\u00C2\u00B0481 122\u00C2\u00B034' 122\u00C2\u00B034' .122\u00C2\u00B038' 122\u00C2\u00B038' 122\u00C2\u00B034' 122\u00C2\u00B028 r i v e r terrace f l a t n e u t r al 0 59 56 25 66 25 8 NW 2 84 18 5 61 27 12 NE 6 70 66 32 74 23 3 s t r a i g h t N 5 61 38 33 72 25 3 , x e r i c .. eutrophic s l i g h t water ... well ... 0-6 12-18 20-50+ Regosol 0-6 0-6 0-6 12-18 12-18 12-18 25-35+ 20-36+ 22-36+ NW 3 55 71 20 74 22 4 side of ravine NE 33 78 20 5 53 42 5 moderate water 0-6 0-5 12-18 5-18 20-36+ 18-36+ aeolian deposits a e o l i a n deposit over g l a -c i a l d r i f t ! 127 T a b l e 48 Agropyro ( s p i c a t i ) - A r temisietum t r i d e n t a t a e Number of P l o t s P l o t No. P l o t S i z e (m2) E l e v a t i o n ( f t ) 1 039 400 1540 2 040 400 1540 3 047 400 1600 4 046 400 1620 5 041 400 1800 6 045 400 2020 B Layer sub l a y e r Constancy Avg S p e c i e s S i g n i f i c a n c e 1 A r t e m i s i a t r i d e n t a t a 2 8. .4 8 .5 8.5 8 .5 8, .5 9.6 V 8. ,2 2 Chrysothamnus nauseosus 2 - 2 .3 2.3 I I 0. ,7 C Layer 3 K o e l e r i a g r a c i l i s 5, .3 4 .2 5.2 5 .3 5. .2 4.2 V 4 . ,7 4 Agropyron spicatum 3, .2 3 .2 4.2 6 .3 6, .2 5.3 V 4 . ,5 5 A r t e m i s i a f r i g i d a 3, .3 3 .2 3.1 3 .2 3, .1 2.2 V 2. , 8 A r t e m i s i a t r i d e n t a t a 3, .3 2, .2 2.1 2 .2 3, .2 3.3 2. ,5 6 Opuntia f r a g i l i s 3, .2 2.1 3 .2 2. .2 2.1 V 2. ,0 7 Lomatium macrocarpum 2, .3 2 .1 2.+ 2 .1 4, .+ 1.+ V 1. . 8 8 A c h i l l e a m i l l e f o l i u m 2, . 1 2 .2 3.1 2. .1 + .+ V 1. ,4 9 Taraxacum o f f i c i n a l e 2, .2 1 . + 2.+ 1 .1 1. .+ - V 1. ,2 10 S o l i d a g o m u l t i r a d i a t a 3. .1 1 .1 +. + + . + +, . + 1.+ V 0. ,9 11 A r a b i s h o l b o e l l i i +, . + + . + - 1 . + 1. . + + . + V 0. ,6 12 E r i g e r o n f l a g e l l a r i s 3, .2 2 .2 2.1 3 .2 - IV 1. ,7 13 Lithospermum r u d e r a l e 2, .2 2 .2 - +, 1.+ IV 0. ,9 14 A r t e m i s i a dracunc u l u s +, . + + .+ + .+ + . + - IV 0. .3 15 S t i p a comata 5, .3 2 .1 - 3. .2 - I I I 1. .7 16 A n t e n n a r i a r o s e a 2, .2 3.1 2 . + - I I I 1. .2 17 Sisymbrium l o e s e l i i 4 .1 1.+ 3 . + - I I I 0. .8 18 E r i g e r o n compositus 2. , + +. + + . + - I I I 0. .5 19 A g o s e r i s g l a u c a + . + - + . + +, .+ - I I I 0. .3 20 A n t e n n a r i a u m b r i n e l l a 4, .3 - 2. .2 - I I 1. .0 21 Sporobolus c r y p t a n d r u s 3.2 2 .2 - I I 0. \u00E2\u0080\u00A28. 22 A n t e n n a r i a dimorpha 2.1 2 .1 - I I 0. 23 Poa secunda 2.1 2 . 1 - I I 0. .1 24 A n t e n n a r i a n e g l e c t a +. + 1 .+ - I I 0. .3 25 Comandra u m b e l l a t a - 1. , + 1.+ I I 0. .3 26 C r e p i s a t r a b a r b a 1. . + 1 . + - - I I 0. .3 27 E r i g e r o n s p e c i o s u s 1. - 1. - I I 0. .3 28 P o t e n t i l l a p e n n s y l v a n i c a 1 . + - + , + - I I 0. .3 29 Linum l e w i s i i +. + + . + - I I 0. .2 30 Tragopogon dubius 1. . + - +. . + - I I 0. . 2 D Layer (Bryophytes) 31 T o r t u l a r u r a l i s 5, . 3 3 . 2 4.3 4 .3 4 .2 3.1 V 3, .8 32 Ceratodon purpureus 2 .1 2 . 1 1.1 2 . 1 - IV 1, . 2 33 Eurhynchium p u l c h e l l u m 1. .1 1 .1 - - I I 0. .3 (Lichens) 34 C l a d o n i a p o c i l l u m 5. .3 3 .2 5.4 4 . 2 5. .3 3.2 V 4 . 2 35 L e c i d e a d e c i p i e n s 2. .1 1 . + 2.1 2 . 1 1. . + - V 1. . 3 36 C a n d e l ^ r i e l l a v i t e l l i n a 2, . 1 1.1 1 .1 1. . + - IV 0, .8 37 Dermatocarpon hepaticum 4 .+ 4 . + - I I 1. . 3 3 8 Thrombium epigaeum 3.2 3 .2 - I I 1. .2 39 C l a d o n i a chlorophaea - 3 . 1 2 . 1 - I I 0 , .8 40 P e l t i g e r a c a n i n a v a r . r u f e s c e n s 2 .1 2 . 1 - - I I 0. , 7 41 P h y s c i a muscigena - 2 .1 2.1 I I 0, .7 42 C a l o p l a c a s t i l i c i d i o r u m 2.1 1 . 1 - I I 0, . 5 4 3 Collema tenax 1 - 1 . + I I c, , 3 TOTAL SPECIES ( i n c l . s p o r a d i c s ) 35 26 30 31 25 S p o r a d i c s p e c i e s B Layer 44 Symphoricarpos o c c i d e n t a l i s C Layer 45 A r n i c a s o r o r i a 46 A r t e m i s i a campestris 47 A s t r a g a l u s d a s y g l o t t i s 48 C a l o c h o r t u s macrocarpus 49 Carex p r a t i c o l a 50 C r e p i s tectorum 51 Eriogonum h e r a c l e o i d e s 52 Heuchera c y l i n d r i c a 039(+. . + ) 040(3. .3) 53 Poa j u n c i f o l i a 040(2. .2) 54 Poa p r a t e n s i s 047(+. . + ) 55 Zygadenus gramineus 040(+, .+) 040(+. . + ) 039(2. .2) D Layer 039(+. . + ) 039(2. .1) 56 Brachythecium salebrosum 039(2. .1) 039(1. .1) 57 C l a d o n i a p y x i d a t a 045(3 .1) 039(2. . + ) 58 D i p l o s c h i s t e s canadensis 047(3. .2) 041(+. . + ) 59 F u l g e n s i a b r a c t e a t a 045(1. . + ) 128 The s o i l surface of the Agropyro - Artemisietum tridentatae i s covered by a thin layer of l i t t e r which i s mostly composed of leaves and decaying stems of Artemisia tridentata. However, mineral s o i l was exposed in a l l plots sampled, thus evaporation from the s o i l surface i s believed to occur readily. The s o i l i s well drained although moderate surface runoff occurs as there i s evidence of slight water erosion. The association i s rated as xeric. With the exception of plot 045 which was located on a steep slope, the s o i l i s formed from a parent material of aeolian deposits and has no discernible horizonation. In plot 045 the parent material appears to be aeolian deposits overlying g l a c i a l d r i f t and the s o i l has an A,B,C, horizon sequence. The A horizon i s melanized and five inches thick; the B horizon i s lighter coloured and 13 inches thick and the C horizon i s ligh t coloured and appears to be cemented. The lower levels of a l l profiles effervesced with hydrochloric acid indicating the presence of carbonates. The sampled surface horizons vary texturally from sandy loams to s i l t loams with s i l t sized particles being the dominant s o i l fraction. Clay content increases in the second sample (B) and these are cl a s s i f i e d as sandy loams, s i l t s or loams. Clay content i s generally greater s t i l l in the third sample and these range texturally from sandy loams to clay loams. Soil pits were dug to a depth of over forty inches and no coarse particles were found; with the exception of plot 045 which had gravels and cobbles present i n the lower horizons. The s o i l reaction i s neutral to alkaline near the surface and becomes alkaline with depth. Measured pH values at the surface ranged from 7.1 to 8.0 and those of the third sample from 8.2 to 8.6. Exchangeable cations are present in moderately high amounts, with calcium dominating the exchange complex. Calcium and magnesium both increase in 129 amounts with depth indicating that some enrichment of the lower horizons i s occurring. The higher calcium concentrations iri the lower horizons may in part account for the higher alkalinity of the s o i l . Exchangeable sodium i s present in low amounts so most l i k e l y w i l l not alter the exchange complex. The concentration of exchangeable potassium i s high in the surface sample with a range of 6.1 meg/100 g to 6.7 meg/100 g, and decreases with depth. This suggests that the l i t t e r of Artemisia tridentata contains a high concentration of potassium. It appears that some organic matter i s being incorporated into the s o i l , as estimated from the presence of carbon in measureable amounts. The percentage of measured carbon i s highest in surface horizons and decreases down the p r o f i l e . Similarly, available phosphorus which i s present i n low amounts decreases with depth. Total nitrogen i s present i n low to moderate amounts and decreases down the pr o f i l e . The carbon:nitrogen ratios are generally low indicating that the organic matter i n the s o i l contains sufficient nitrogen for decomposition, thus nitrogen w i l l be available for higher plants. The cation exchange capacity i s high in the surface horizon and corresponds to the higher amounts of organic matter present. It decreases only slightly with depth because of the fine textured s o i l s . Based on the available chemical data this association i s considered to be eutrophic. With the exception of plot 045 the so i l s are cla s s i f i e d as Orthic Regosols because of their lack of horizon development. Plot 045 i s c l a s s i f i e d as an Orthic Brown Chernozem. The deposition of s o i l from the slopes above i s believed to be helping to maintain the soils in a regosolic condition. Three vegetation layers are present in the Agropyro - Artemisietum tridentatae. The shrub (B2 ) layer has a percentage cover ranging from 55% to 78% under which i s developed a herb (C) layer with a coverage ranging from 18% to 20%. The Bryophyte and lichen layer i s moderately well developed Table 49 Soil Texture Agropyro (spicati) - Artemisietum tridentatae Number of Plots 1 2 3 4 5 6 Plot No. 039 040 047 046 041 045 Sample 1 Textural class SL SiL SiL SL SiL SL Clay (%) 6 12 8 7 7 6 S i l t (%) 45 61 53 47 51 32 Sand (%) 49 27 39 46 42 62 V^ r L>4> ^ \u00C2\u00BB7_> \"w \u00E2\u0080\u00A2\u00E2\u0080\u00A2- W M l l l W 11 U *J Sample 2 Textural class SL SiL L L SiL SL Clay (%) 9 9 20 24 14 8 S i l t (%) 44 59 45 46 52 24 Sand (%) 47 32 35 30 34 68 Coarse fragments None None None None None g. Sample 3 Textural class SL SiL L CL SiL SL Clay (%) 10 25 26 31 19 9 S i l t (%) . 46 61 40 40 57 30 Sand (%) 44 14 34 29 24 Coarse fragments None None None None None g.c.s. \u00C2\u00B0 131 Table 50 Soil Chemical Analysis Agropyro (spicati) - Artemisietum tridentatae Number of Plots 1 2 3 4 5 6 Plot No. 039 040 047 046 041 045 Sample 1 C% 4.8 7.0 13.5 10.6 16.4 7.1 N% .17 .28 .69 .63 .84 .41 C/N .28.2 25.0 19.6 16.8 19.5 17.3 P ppm 5.0 6.0 7.0 15.0 8.0 17.0 Na .12 .44 .27 .13 .34 .13 K 6.1 6.41 6.4 6.7 6.33 6.4 Ca 11.0 18.0 11.5 11.0 9.0 9.5 Mg 2.25 6.0 4.7 4.8 5.2 2.3 CEC 28.6 22.8 48.0 33.7 52.8 24.8 pH 8.0 7.8 7.1 7.5 7.3 8.0 Sample 2 C% 3.6 9.4 6.1 3.4 1.9 3.9 N% .21 .26 .29 .17 .07 .28 C/N 17.1 36.2 21.0 20.0 27.1 13.9 P ppm 5.0 6.0 8.0 8.0 5.0 13.0 Na .67 5.0 .53 .96 1.10 .13 K 8.2 6.6 .28 .26 6.13 .34 Ca 16.5 6.0 21.5 19.0 7.5 16.5 Mg 6.92 10.3 6.7 9.8 9.6 3.3 CEC 24.3 45.3 32.6 28.5 27.6 18.4 pH 8.4 8.0 8.1 8.3 8.0 7.9 Sample 3 C% 0 2.3 3.4 0 0 0 N% .05 .13 .23 .04 .03 .11 C/N 0 17.7 14.8 0 0 0 P ppm 2.0 5.0 5.0 9.0 4.0 3.0 Na 1.4 1.4 1.41 1.8 1.99 .42 K 5.4 6.7 .34 .38 5.89 .23 Ca 16.5 10.0 22.5 17.5 22.5 16.0 Mg 11.2 9.3 9.8 9.2 15.9 4.8 CEC 16.5 21.7 23.7 19.3 20.4 8.9 pH 8.4 8.6 8.4 8.5 8.3 8.2 132 with a percentage cover ranging from 5% to 33%. The association i s dominated by Artemisia tridentata with an average species significance of 8.2. The only other shrub species present i s Chrysothamnus nauseosus. These xerophytic shrub species which are characteristic of semi-arid climates (annual precipitation from five to seven inches), are established in subhumid regions, such as the Cariboo Zone only on fine textured s i l t - c l a y s o i l s . In these soi l s a substantial part of the moisture i s held i n hygroscopic condition and i s unavailable to plants. Because of this such sites are essentially drier than would be anticipated in a subhumid climate. The C layer i s dominated by Koeleria g r a c i l i s and Agropyron spicatum with average species significance of 4.7 and 4.5 respectively. Other constant species includes Artemisia f r i g i d a , Opuntia f r a g i l i s , Lomatium macrocarpum, Solidago multiradiata and Arabis h o l b o e l l i i . Artemisia dracunculus, with a constancy of class IV, and Sisymbrium l o e s e l l i i with a constancy of class III, are considered as characteristic species because of their high preference for this association. Other non constant species important i n the definition of the Agropyro - Artemisietum tridentatae are: Erigeron f l a g e l l a r i s , Lithospermum ruderale, Stipa comata, Sporobolus cryptandrus, Comandra umbellata and Linum l e w i s i i . In this dry habitat lichens compose more of the structure of the D layer than do bryophytes. The most important bryophytes are Tortula ruralis with an average species significance of 3.8 and Ceratodon purpureus with an average species significance of 1.2. Eurhynchium pulchellum and Brachythecium salebrosum occur with low constancy near the base of Artemisia tridentata plants where more moisture i s available. Cladonia pocillum and Lecidea decipiens are the dominant lichens 133 with average species significances of 4.2 and 1.3 respectively. Candelariella v i t e l l i n a , Dermatocarpon hepaticum, Thrombium epigaeum, Cladonia chlorophaea, Physcia muscigena, and Diploschistes canadensis occur with low constancy but are indicative of the xeric habitat. The regularly occurring species of this association form a group which i s characteristic of xeric, alkaline habitats as well as fine textured s o i l s . The Agropyro - Artemisietum tridentatae has a history of moderate to severe grazing as i t forms a major part of the spring cattle range. Grazing may actually favour the development of this association. Through grazing, a reduction i n the density of shallow rooting grass species w i l l occur, which . in turn w i l l allow some moisture to penetrate into the s o i l and become available to deeply rooting shrub species, like Artemisia tridentata. 3. Opuntio (fragilis) - Stipetum comatae (ref. Tables; 51, 52, 53, 54, 83, and Fig. 16) Characteristic Combination of Species Order Characteristic Species Agropyron spicatum Artemisia f r i g i d a Erigeron f l a g e l l a r i s Arabis h o l b o e l l i i Koeleria g r a c i l i s Tragopogon dubius Tortula ruralis Cladonia pocillum Alliance Characteristic Species Lomatium macrocarpum Comandra umbellata Calochortus macrocarpus Opuntia f r a g i l i s Lecidea decipiens Diploschistes canadensis Physcia muscigena 134 Association Characteristic Species Stipa comata Sporobolus cryptandrus Thrombium epigaeum The Opuntio - Stipetum comatae i s found at low elevations on the Fraser Plateau and reaches i t s best development near the bottoms of the major valleys. Here, a warm climate and long growing season prevail. The association occurs on gently sloping terraces with south or southwest exposures. Measured slope angles ranged from 2P to 130. These terraces are located at the base of steep slopes on which the Agropyretum spicati i s developed and appear to benefit from deposition of s o i l eroded by wind and water from the steep slopes. The terraces are greatly dissected by water formed ravines and thus the habitat of the Opuntio - Stipetum comatae has the appear-ance of sloping ridges. The slopes are snow free earlier than any other areas; sometimes being bare as early as February 15. Thus moisture loss by evaporation may begin early i n the season. The s o i l surface i s covered by an extensive but very thin layer of l i t t e r which does l i t t l e to prevent moisture loss. Evaporation and surface drying in some areas i s severe enough in the summer to cause cracking of the s o i l surface. The s o i l i s well drained and very l i t t l e surface runoff occurs. The hygrotope of this association i s considered to be very xeric. Plant roots are matted i n the top 15 inches of the s o i l and very few roots were found at lower depths. This surface root concentration could be a response to water penetration, as moisture w i l l seldom be present in the lower horizons. The s o i l i s developed from a parent material of aeolian material overlying gl a c i a l d r i f t with the exception of plot 062 in which the parent material appears to be only aeolian deposits. In the profiles of plots 062 and 044 no horizon development was apparent whereas in the remaining profiles Table 5 1 Qpuntio (fragilis) - Stipetum comatae Plot Data Number of Plots 1 2 3 4 5 Plot No. 062 044 059 032 042 Plot Size (m2) 100 100 100 100 100 Date analyzed 10/6 8/8 8/9 29/7 8/8 1968 1967 1967 1967 1967 Elevation (ft) 1700 1920 2000 2150 2260 Locality FP FP FP FP FP 51\u00C2\u00B050' 51\u00C2\u00B050' 51\u00C2\u00B050' 51\u00C2\u00B050' 51\u00C2\u00B050' 122\u00C2\u00B031' 122\u00C2\u00B030' 122\u00C2\u00B030' 122\u00C2\u00B032' 122\u00C2\u00B030' Physiography Landform river terrace exposed Relief shape straight straight convex straight straight Exposure SW S SW SW SW Slope gradient (\u00C2\u00B0) 2 4 4 13 13 Layer coverage (%) B2 layer 5 - - 3 -C layer 81 88 84 88 82 D layer 12 5 15 4 14 Plot coverage (%) Humus and l i t t e r 85 90\" 91 90 85 Mineral s o i l 15 10 9 10 15 Soil Hygrotope Trophotope eutrophic Erosion slight slight slight water n i l water water n i l Drainage Horizon depth (in) Regosol Regosol A 0-6 0-18 0-7 0-7 0-8 B 6-12 18-23 7-17 7-15 8-17 C 24-30+ 23-30+ 16-30+ 15-27+ 17-28+ Parent material aeolian deposit ..aeolian deposit over glacial d r i f t 136 Table 52 Opuntio ( f r a g i l i s ) - Stipetum comatae Number of Plots 1 2 3 4 5 Pl o t No. 062 044 059 032 042 Pl o t Size (m2) 100 100 100 100 100 El e v a t i o n (ft) 1700 1920 2000 2150 2260 Avg Species C Layer Constancy S i g n i f i c a n c e 1 S t i p a comata 7.2 8.5 8.4 8.5 8.4 V 7.8 2 Sporobolus cryptandrus 6.1 3.1 4.2 3.2 5.2 V 4.2 3 Artemisia f r i g i d a 1.1 5.2 5.2 4.2 3.1 V 3.6 4 Opuntia f r a g i l i s 4.2 3.1 4.3 3.2 4.2 V 3.6 5 K o e l e r i a g r a c i l i s 2.1 3.2 3.1 2.1 2.1 V 2.4 6 Lomatium macrocarpum 3.+ 1.+ 2.+ 3.1 3.+ V 2.4 7 Tragopogon dubius 2.+ 1.+ + .+ 1.+ + .+ V 1.0 8 Arabis h o l b o e l l i i + .+ 1.+ 1.+ + .+ + .+ V 0.7 9 Comandra umbellata - 1.1 1.+ 3.2 2.1 IV 1.4 10 Chenopodium leptophyllum 2.+ + .+ - 1.+ - III 0.7 11 Artemisia campestris - - 2.1 2.1 - II 0.8 12 Chrysothamnus nauseosus - - - 1.+ 1.+ II 0.4 13 P o t e n t i l l a pennsylvanica 1.+ + .+ - - - II 0.3 14 Taraxacum o f f i c i n a l e + .+ + .+ - - - II 0.2 IS Cirsium undulatum + .+ + .+ - - - II 0.2 D Layer (Bryophytes) 16 T o r t u l a r u r a l i s 2.1 3.1 3.1 2.2 3.2 V 2.6 (Lichens) 17 Cladonia pocillum 4.1 3.2 4.2 3.2 3.2 V 3.4 18 Lecidea decipiens 3.1 2.1 2.1 3.1 2.1 V 2.4 19 Thrombium epigaeum 2.1 2.1 1.1 2.1 3.1 V 2.0 20 D i p l o s c h i s t e s canadensis 2.1 2.1 3.1 - 2.1 IV 1.8 21 Physcia muscigena 3.1 3.1 - - - II 1.2 22 Dermatocarpon hepaticum 2.1 1.1 - - - II 0.6 23 Fulgensia bracteata 2.1 1.1 II 0.6 TOTAL SPECIES ( i n c l . sporadics) 27 24 16 19 17 Sporadic species B Layer 24 Artemisia t r i d e n t a t a C Layer 25 Agropyron spicatum 26 Agoseris glauca 27 Androsace s e p t e n t r i o n a l i s 28 Calochortus macrocarpus 29 Crepis atrabarba 30 Descurainea pinnata 31 Erigeron compositus 062(3.+) 032(2.1) 032(1.1) 059(1.+) 044(3.1) 044(+.+) 062(1.+) 032(1.1) 32 Erigeron f l a g e l l a r i s 33 Lappula redowskii 34 Lepidium densiflorum 35 Lepidium virginicum 36 Zygadenus gramineus D Layer 37 C a n d e l a r i e l l a v i t e l l i n a 38 P e l t i g e r a canina var. rufescens 39 Physcia s t e l l a r i s 042(1.1) 062 (2. + ) 062(+.+) 062(1.+) 044(+.+) 042(3.3) 062(2.1) 062(1.1) 137 an A,B,C, horizon sequence was present. The A horizon i s seven to eight inches thick and contains an accumulation of organic matter. It overlies a lighter coloured, less melanized B horizon ranging i n thickness from eight to nine inches. The C horizon i s very light coloured and effervesces moderately with hydrochloric acid indicating a carbonate accumulation. In plots 044 and 062 a slig h t effervescence occurred indicating that some carbonate accumulation i s taking place. Texturally, the surface horizons are cl a s s i f i e d as sandy loams to s i l t loams and no coarse fragments were present i n any of the samples taken. With the exception of plot 062, which i s medium textured throughout, the so i l s increase in coarseness with depth and the sampled C horizons are composed largely of sand. Coarse fragments ranging i n size from gravels to stones were present i n a l l samples. These coarse particles are mostly basalts, thought to originate from local outcrops. The s o i l reaction i s sl i g h t l y alkaline near the surface and increases i n a l k a l i n i t y with depth. Measured pH values for the C horizon range from 8.2 to 8.5. This alkaline reaction i s due partly to weathering of the basic basaltic parent rock and partly to the secondary accumulation of basic cations in the C horizon as a result of leaching. Exchangeable calcium and magnesium are present in high amounts and increase s l i g h t l y i n concentration with depth indicating that some movement down the pr o f i l e due to leaching and drainage i s occurring. Exchangeable sodium i s present i n low amounts so should not interfere with the exchange complex. Exchangeable potassium and total phosphorus occur i n the surface horizons i n high concentrations and decrease i n amount down the p r o f i l e . Nitrogen i s present only in moderate amounts i n the A horizon and decreases to just trace amounts in the C horizon. However, the carbon:nitrogen ratios are generally low, suggesting that nitrogen i s present in sufficient amounts to satisfy the microflora Table 53 Soil Texture Opuntio (fragilis) - Stipetum comatae Number of Plots Plot No. 1 062 2 044 3 059 A Horizon Textural class SL Clay (%) 4 S i l t (%) 39 Sand (%) 57 Coarse fragments None B Horizon Textural class SL Clay (%) 2 S i l t (%) 43 Sand (%) 55 Coarse fragments None C Horizon Textural class SiL Clay (%) 4 S i l t (%) 50 Sand (%) 46 Coarse fragments None SiL 4 51 44 None SL 9 37 54 LS 8 19 73 g.c. SL 5 41 54 None SL 9 32 59 LS 6 11 83 g.c.s, 4 032 5 042 SL 3 48 48 None SL 8 46 45 g.c. LS 4 9 87 g.c.s. SiL 4 51 45 None SiL 6 53 41 g-SL 10 38 51 139 Table 54 Soil Chemical Analysis Opuntio (fragilis) - Stipetum comatae Number of Plots 1 2 3 4 5 Plot No. 062 044 059 032 042 A Horizon C% 7.2 6.4 7.3 3.8 14.6 N% .32 .41 .41 .14 .69 C/N 22.5 15.6 17.8 27.1 21.2 P ppm 11.0 9.0 13.0 6.0 21.0 Na .11 .12 .10 .28 .13 K .36 6.59 .77 1.09 5.38 Ca 8.6 11.5 7.5 5.0 9.0 Mg 2.3 4.3 2.9 5.8 5.6 CEC 31.7 34.6 34.8 19.3 41.8 pH 7.8 7.8 7.4 7.7 7.4 B Horizon C% 0 3.3 2.1 2.4 3.5 N% .13 .31 .13 .18 .14 C/N 0 10.6 16.2 13.3 25.0 P ppm 6.0 8.0 14.0 6.0 10.0 Na .14 .50 .12 .11 6.0 K .31 .30 .16 2.17 .24 Ca 11.7 20.5 13.8 8.0 8.0 Mg 3.5 7.9 4.8 10.8 7.7 CEC 8.4 26.7 23.5 13.7 27.3 pH 7.7 8.2 8.1 8.3 8.0 C Horizon C% 0 0 0 0 0 N% .05 .07 .09 .03 .06 C/N 0 0 0 0 0 P ppm 3.0 6.0 6.0 7.0 7.0 Na .83 .74 .91 .17 1.28 K .44 .26 .10 2.17 .25 Ca 12.5 22.5 13.3 8.5 21.5 Mg 5.6 8.1 5.9 7.1 9.5 CEC 7.1 5.6 4.1 3.8 13.1 pH 8.2 8.4 8.5 8.4 8.5 140 requirements as well as those of the higher plants. Percentage carbon ranges from 3.8% to 14.6% in the surface horizon indicating that organic saatter i s being incorporated into the s o i l . The amount of carbon decreases i n the B horizon to a range of 2.1% to 3.3%. No carbon was measureable in the C horizon. Even i n the profiles which do not have disti n c t horizons some organic matter accumulation occurs at the surface. The cation exchange capacities are high i n the sampled surface horizons ranging from 19.3 meg/100 g to 41.8 meg/100 g. Cation exchange capacity decreases rapidly with depth due to a decrease i n organic matter content and an increase i n sand content of the s o i l . Cation exchange capacities of the sampled C horizons ranged from 3.8 meg/100 g to 13.1 meg/100 g. The habitat of this association i s considered to be eutrophic. The s o i l s of the Opuntio - Stipetum comatae are cl a s s i f i e d either as Regosols (plots 044 and 062) or as Orthic Brown Chernozems although these do not appear to be well developed, and may actually be Rego Brown Chernozems. The lack of s o i l development here, i s possibly due partly to the extreme dryness of the habitat where evaporation appears to be a controlling factor and partly to constant deposition of fine s o i l from the slopes above as a result of erosion by wind and water. Structurally the Opuntio - Stipetum comatae has a well developed C \u00E2\u0080\u00A2 layer with a percentage cover ranging from 81% to 88% and a poorly developed D layer with a percentage cover ranging from 5% to 15%. In two plots sampled, isolated individuals of Artemisia tridentata occurred with low significance and thus constituted a fragmentary B horizon. The association i s dominated by Stipa comata with an average species significance of 7.8. Sporobolus cryptandrus i s a constant associate of high species significance, averaging 4,2. These species are both characteristic for the association and appear to be dependent on xeric habitats with regosolic 141 s o i l s . Artemisia fr i g i d a and Opuntia f r a g i l i s which are indicative of dry habitats occur with species significances of 3.6. Other constant species include: Koeleria g r a c i l i s , Lomatium macrocarpum, Tragopogon dubius and Arabis h o l b o e l l i i . Bryophytes are noteably lacking from the D layer and only Tortula rur a l i s occurred with any degree of dominance. Lichens are more common under these xeric conditions and form most of the structure of this layer. Cladonia pocillum, Lecidia decipiens, and Thrombium epigaeum are the constant species. Diploschistes canadensis i s the only other lichen species of importance and occurs with an average significance of 1.8. The Opuntio - Stipetum comatae has a history of moderate to severe grazing. Because of i t s topographic position and corresponding early release from snow this association forms an essential part of the early spring cattle range. Grazing at this time i s concentrated on the vegetation produced i n the preceding season. By the time active new growth begins, grazing pressure has usually been reduced and thus the association i s able to regain i t s vigor substantially. However, continued cropping may result in a serious reduction of organic matter accumulation i n the s o i l and therefore essential elements like nitrogen and phosphorus could become limiting. The Opuntio - Stipetum comatae also appears to be promoted to some extent by grazing as the dominant, Stipa comata, can withstand grazing pressures better than other dominants of this area, for example, Agropyron spicatum. Tisdale (1947) and Brayshaw (1955) reported that this association i s largely promoted by grazing. L42 Fig. 16. The Opuntio - Stipetum comatae shown here as developed on a gently sloping terrace. Stipa comata dominates the association and gives i t a characteristic appearance. Fig. 17. The Agropyro - Juniperetum scopulorum on a steep south facing slope. It i s dominated by Juniperus scopulorum, Artemisia tridentata and Agropyron spicatum and i s characteristic of unstabilized slopes. 143 4. Agropyro (spicati) - Juniperetum scopulorum (ref. Tables; 55,56, 57, 58, 83, and Fig. 17) Characteristic Combination of Species Order Characteristic Species Agropyron spicatum Artemisia frigida Erigeron f l a g e l l a r i s Arabis h o l b o e l l i i Koeleria g r a c i l i s Tortula ruralis Alliance Characteristic Species Comandra umbellata Lithospermum ruderale Opuntia f r a g i l i s Diploschistes canadensis Lecidea decipiens Association Characteristic Species Chrysothamnus nauseosus Juniperus scopulorum Important Companion Species Artemisia tridentata Artemisia dracunculus Stipa comata Sporobolus cryptandrus The Agropyro - Juniperetum scopulorum occurs on steep exposed slopes or on the steep sides of water cut ravines. Measured slope gradients range from 28\u00C2\u00B0 to 44\u00C2\u00B0. The exposures are usually southerly, although two plots had northwest exposures. The surface topography ranges from straight to convex. The s o i l surface i s partly covered by a thin layer of l i t t e r ranging in extent from 42% to 88% of the surface area. A large amount of mineral s o i l was exposed i n a l l plots sampled and i n four plots rocks were present on the s o i l surface. The soi l s of this association are considered to be well drained and the hygrotope i s rated as xeric. There i s evidence of surface erosion varying in intensity from moderate to extreme which i s caused by surface runoff water. Erosion due to 144 Table 55 Agropyro ( s p i c a t i ) - Juniperetum scopulorum P l o t Data Number of P l o t s 1 2 3 4 5 6 7 Pl o t No. 092 093 083 084 085 086 017 P l o t Size (m2) 100 100 100 100 100 100 100 Date analyzed 31/7 31/7 20/7 20/7 20/7 24/7 8/7 1968 1968 1968 1968 1968 1968 1967 El e v a t i o n (ft) 2000 2050 2100 2160 2200 2200 2560 \u00E2\u0080\u00A2 L o c a l i t y FP FP FP FP FP FP WL 51\u00C2\u00B048' 51\u00C2\u00B048' 51\u00C2\u00B048' 51\u00C2\u00B048' 51\u00C2\u00B048' 51\u00C2\u00B050' 52\u00C2\u00B026' 122\u00C2\u00B033' 122\u00C2\u00B033' 122\u00C2\u00B032' 122\u00C2\u00B031' 122\u00C2\u00B032 ' 122\u00C2\u00B034' 122\u00C2\u00B020 Physiography Landform R e l i e f shape Exposure Slope gradient (\u00C2\u00B0) Layer coverage (%) A3 l a y e r B2 l a y e r C la y e r D l a y e r P l o t coverage (%) Humus and l i t t e r Mineral s o i l Rock S o i l Hygrotope Trophotope Erosion Drainage Sample depth (in) 1 2 3 Parent material exposed slope convex S 36 68 12 10 72 28 convex S 33 20 62 10 8 71 26 3 .side of ravine s t r a i g h t . SW 28 36 12 14 42 48 8 NW 44 4 52 72 40 88 11 very x e r i c .permesotrophic NW 34 8 43 52 21 64 32 subxeric (eutrophic) S 33 22 61 24 6 55 45 4 exposed slope SW 33 11 52 5 58 32 10 strong extreme extreme moderate moderate strong moderate water water water water water water water 0-6 12-18 24-30 aeoli a n deposit 0-6 12-18 g l a c i a l d r i f t 0-6 12-18 24-30 g l a c i a l d r i f t . well 0-6 12-18 24-30 0-6 12-18 24-30 0-6 12-18 0-6 12-18 24-30 ae o l i a n depo-s i t over gla-. . c i a l d r i f t . . . g l a c i a l g l a c i a l d r i f t d r i f t 145 Table 56 Agropyro (spicati) - Juniperetum scopulorum Sporadic species C Layer 74 A c h i l l e a millefolium 25 Arctostaphylos uva-ursi 26 Astragalus miser 27 Koeleria g r a c i l i s 28 Linum l e w i s i i 29 Lithospermum ruderale Number of Plots 1 2 3 4 5 6 7 Plot No. 092 093 083 084 085 086 017 Plot Size (m2) 100 100 100 100 100 100 100 Elevation (ft) 2000 2050 2100 2160 2200 2200 2560 sub Avg Species A L a y e r layer Constancy Significance 1 Pseudotsuga menziesii 3 5.+ - 3.+ 4.+ 5.+ - IV 3.0 B Layer 2 Juniperus scopulorum 2 7.4 8.4 6.3 7.3 6.4 7.6 4.+ V 6.4 3 Artemisia tridentata 2 4.3 4.3 4.3 4.3 5.3 4.2 - V 4.2 4 Chrysothamnus nauseosus 2 2.2 3.2 3.3 2.2 2.1 3.2 - V 2.5 C Layer 5 Agropyron spicatum 4.2 4.2 4.2 8.3 7.2 5.2 5.2 v 5.3 6 Artemisia f r i g i d a 4.2 3.1 3.1 3.1 3.1 4.1 5.2 V 3.5 Artemisia tridentata 2.1 1.+ 2.1 2.1 2.1 1.+ - 1.4 Chrysothamnus nauseosus 2.+ 1.+ 1.1 - 2.+ 1.+ 1.+ 1.1 Juniperus scopulorum 2.1 1.1 1.1 - 2.1 2.1 - 1.2 7 Comandra umbellata 1.1 - 1.+ +. + - 1.+ 3.+ IV 0.9 8 Artemisia dracunculus 2.+ - 2.1 1.+ 2.+ - - III 1.0 9 Solidago multiradiata - - - 3.1 2.+ 2.+ - III 1.0 10 Artemisia campestris - - - - - 3.+ 5.1 II 1.2 11 Erigeron f l a g e l l a r i s - - - 4.2 - - 2.2 II 0.8 12 Stipa comata 3.2 - +. + - - - - II 0.7 13 Opuntia f r a g i l i s 2.2 - - - - - 2.2 II 0.6 14 Sporobolus cryptandrus 1.+ - - - - 1.+ - II 0.2 15 Arabis h o l b o e l l i i + .+ - - - - - + .+ II 0.1 D Layer (Bryophytes) 16 Tortula r u r a l i s 4.2 3.2 4.3 6.3 4.3 4.2 3.1 v 4.3 17 Ceratodon purpureus - 3.2 2.2 3.2 3.2 - - II 1.6 18 A b i e t i n e l l a abietina'' - - - 4.3 4.2 - - II 1.3 (Lichens) 19 Dermatocarpon hepaticum 3.2 2.2 2.1 1.1 2.2 1.1 - V 1.6 20 Lecidea decipiens 2.2 2.2 3.1 1.1 2.2 1.1 - V 1.6 21 Fulgensia fulgescens 1.1 1.1 1.1 - - - - III 0.4 22 Diploschistes scruposus - 2.1 2.1 - - 1.1 - II 0.7 23 Physcia s t e l l a r i s 2.1 ~ 2.1 \u00E2\u0080\u0094 II 0.6 TOTAL SPECIES ( i n c l . sporadics) 19 15 21 18 16 14 17 017(2.2) 083(2.1) 083(1.+) 0 1 7 ( 1 . + ) 0 1 7 ( 2 . 0 1 7 ( 2 . 2 ) D Layer 30 C a n d e l l a r i e l l a v i t e l l i n a 017(1.+) 31 Collema tenax 083(2.+) Diploschistes canadensis 017(1.+) Lecidea auriculata 017(1.+) 32 33 34 Peltigera canina var. 35 Peltigera malacea rufescens084 (3.2) 084 (2.2) 146 wind also occurs in these habitats as evidenced by the presence of unstabilized sand dunes and the frequent occurence of dust storms. The s o i l i s formed from parent materials of aeolian deposits, aeolian deposits overlying g l a c i a l d r i f t or on g l a c i a l d r i f t . The g l a c i a l d r i f t here appears to be a coarse outwash material. No distinct horizons were present in the sampled s o i l s . The s o i l i s relatively coarse textured and sampled soils ranged from loamy sands to s i l t loams. There i s no significant textural change with depth. With the exception of plot 092 which i s formed on aeolian deposits, coarse fragments ranging i n size from gravels to stones were present i n a l l samples. The s o i l reaction i s alkaline and does not change significantly with increasing depth. Measured pH values range from 7.3 to 8.4. Exchangeable cations are present in moderate amounts and there i s no indication of con-centration changes down the p r o f i l e . Calcium i s the most abundant cation followed by magnesium. The high concentration of these cations i s probably because the parent rock of the s o i l i s mostly basalt and this may also account for the alkaline reaction of the s o i l . Exchangeable sodium and potassium were present in low amounts in a l l samples. There i s very low accumulation of organic matter in this association and carbon was measureable in the surface samples of only three plots. Correspondingly, available phosphorus and total nitrogen are present i n low quantities. Cation exchange capacity i s only moderately high partly because of the lack of organic matter in the s o i l and partly because of the coarseness of the s o i l . Trophically this association i s considered to be permesotrophic up to eutrophic. The soi l s are c l a s s i f i e d as Orthic Regosols as they are practically unaltered from the original parent material. The lack of s o i l development in this association i s probably due to the general unstabelness of the slopes. These are being actively eroded and thus vegetation colonization and accompanying Table 57 Soil Texture Agropyro (spicati) - Juniperetum scopulorum Number of Plots Plots No. 1 092 2 093 3 083 4 084 5 085 6 086 7 017 Sample 1 Textural class LS SL Clay (%) ' 2 8 S i l t (%) 22 \" 34 Sand (%) 76 58 Coarse fragments None g.c. Sample 2 Textural class LS Clay (%) 1 S i l t (%) 25 Sand (%) 74 Coarse fragments None g.c.s. Sample 3 Textural class SL Clay (%) 4 S i l t (%) 34 Sand (%) 62 Coarse fragments None g.c.s. SL 3 41 55 g.c. SiL 8 52 40 g.c. SiL 1 51 48 g.c.s* SL 5 44 51 None SL 5 38 57 g. SL 2 42 56 g. SL 1 41 58 None SL 2 41 56 g. SL 2 35 63 g.c. SL 16 24 60 g.c. L 21 31 48 g.c. g.c.s. SL 18 24 58 J g. SL 15 17 68 g.c. SL 15 17 68 g. c. 148 Table 58 Soil Chemical Analysis Agropyro (spicati) - Juniperetum scopulorum Number of Plots 1 2 3 4 5 6 7 Plot No. 092 093 083 084 085 086 017 Sample 1 C% 0 0 0 2.0 4.1 3.4 0 N% .08 .10 .10 .15 .09 .31 .05 C/N 0 0 0 13.0 45.6 10.9 0 P ppm 0 11.0 5.0 4.0 13.0 3.0 2.0 Na .29 .25 1.18 .67 3.3 .45 1.06 K .34 .82 .17 .12 .16 .56 .29 Ca 14.6 18.2 12.8 19.4 18.5 14.0 6.2 Mg 1.8 4.1 5.8 4.7 7.5 8.3 3.3 CEC 0 34.7 13.6 8.4 23.7 8.1 18.3 PH 7.9 8.1 7.9 8.0 7.9 7.7 7.3 Sample 2 C% 0 - 0 N% .12 - .08 C/N 0 - 0 P ppm 5.0 - 7.0 Na .47 - 5.6 K .65 - .72 Ca 16.9 - 11.1 Mg 5.7 - 7.6 CEC 4.8 - 7.3 pH 8.1 - 8.2 0 3.3 0 0 .06 .18 .08 .05 0 27.5 0 0 7.0 6.0 3.0 5.0 2.3 3.5 .41 1.05 .16 .29 .68 .16 12.6 12.3 14.9 7.6 7.2 6.3 7.4 3.3 13.1 18.9 3.8 16.4 8.0 7.8 7.8 8.2 Sample 3 C% 0 - 0 N% .07 - .05 C/N 0 - 0 P ppm 5.0 - 6.0 Na .27 - 7.10 K .85 - .77 Ca 16.2 - 15.4 Mg 4.7 - 9.3 CEC 4.6 - 11.6 pH 7.9 - 8.1 0 1 . 9 - 0 .07 .12 - .05 0 15.8 - 0 5.0 6.0 - 6.0 3.2 .66 - .57 .29 .20 - .13 15.5 20.8 - 6.7 5.5 7.0 - 13.0 17.9 17.3 - 11.9 8.0 8.1 - 8.4 149 organic matter accumulation i s limited. Structurally, this association has four vegetation l a y e r s \u00E2\u0080\u0094 a poorly developed tree layer (A), a well developed shrub layer (B), a well developed herb layer (C) and a moderately well developed bryophyte and lichen layer (D). Juniperus scopulorum dominates the association with an average species significance of 6.4. Artemisia tridentata and Chrysothamnus nauseosus are constant associates of the shrub layer with average species significances of 4.2 and 2.5 respectively. A l l three species are also present in the C layer with lower species significances. Juniperus scopulorum because of i t s low spreading growth form tends to stabilize the s o i l surface and conserve surface moisture which may favour the growth of arboreal species. Pseudotsuga menziesii i s the only tree species present and occurs with low abundance. It i s always associated with a mat of Juniperus scopulorum. Agropyron spicatum i s the dominant species of the C layer and occurs as isolated bunches. Vegetative spread of this species appears to be limited by surface runoff. The only other constant species i s Artemisia frigida which i s characteristic of exposed habitats. Other species characteristic of this association but occurring with lower constancy and species significance include: Comandra umbellata, Artemisia dracunculus, Erigeron f l a g e l l a r i s , Opuntia f r a g i l i s , Stipa comata, Sporobolus cryptandrus, and Arabis h o l b o e l l i i . Artemisia campestris, a species characteristic of dry habitats with coarse textured soil s i s present here, but with low species significance and constancy. A l l species composing the C layer have very low soci a b i l i t y values indicating the open dispersed pattern of the individual plants. This appears to be caused largely by the severe surface erosion. The D layer i s dominated by bryophytes which occur mostly in patches at the bases of woody plants where moisture i s available. Tortula ruralis 150 i s the dominant bryophyte with an average species significance of 4.3. Ceratodon purpureus and Abietinella abietina are the only other bryophytes of importance and both occur with low constancy and significance. The only constant lichen species are Dermatocarpon hepaticum and Lecidea decipiens, both occurring with a species significance of 1.6. The Agropyro - Juniperetum scopulorum differs from other members of the Agropyrion spicati by the greater dominance of woody plants. It i s thought that the coarse s o i l favours the growth and development of these species. Also their deep rooting habit makes them more successful than shallow rooting herb species in this well drained habitat where erosion results in the constant removal of surface s o i l . The Agropyro - Juniperetum scopulorum appears to have a history of light burning as evidenced by the moderate f i r e scars on some of the trees. Grazing i s negligible here, probably because of the inaccessibility of this association. Pseudotsugetalia menziesii Most of the forested area of the Cariboo Zone i s composed of communities cl a s s i f i e d into the Pseudotsugetalia menziesii. The soil s of these communities are formed on coarse textured parent materials of glac i a l d r i f t . The habitats range trophically from submesotrophic to permesotrophic, and hyrotopically from subxeric to subhygric. The Pseudotsugetalia menziesii i s believed to reach i t s most northern extension i n the Cariboo Zone. F l o r i s t i c a l l y , because of i t s geographical, location, the order i s enriched by many Canadian boreal species in this zone. The Order i s characterized by: Pseudotsuga menziesii, Arctostaphylos uva-ursi, Carex concinnoides, Hieracium umbellatum, Spiraea b e t u l i f o l i a , Dicranum polysetum, Cladonia chlorophaea, Cladonia g r a c i l i s , Cladonia mitis, Cladonia 151 rangiferina, and Peltigera aphthosa. Two alliances are recognized for the Pseudotsugaetalia menziesii\u00E2\u0080\u0094 the Arctostaphylo (uva-ursi) - Junipero (communis) - Pseudotsugion *glaucae and the Calamagrostido (rubescentis) - Pseudotsugion *glaucae. Arctostaphylo (uva-ursi) - Junipero (communis) -Pseudotsugion *glaucae. The Arctostaphylo - Junipero - Pseudotsugion *glaucae has a restricted distribution and appears to be confined to coarse subxeric outwash s o i l s . It i s represented by a single association in the Cariboo Zone. The Arctostaphylos type described by Ilvessalo (1929) and the Arctostaphylos association described by Brayshaw (1965) would be included i n this alliance Calamagrostido (rubescentis) - Pseudotsugion *glaucae The Calmagrostido - Pseudotsugion *glaucae i s widely spread in the Cariboo Zone and i s present on submesic to subhygric habitats. It i s characterized by: Calamagrostis rubescens, Aster conspicuus, Hypnum revolutum, Polytrichum juniperinum and Rhytidiadelphus triguetrus. The Pseudotsuga -Calamagrostis association and the Pseudotsuga - Arctostaphylos - Calamagrostis association described by Brayshaw (1965); the Calamagrostis - Arctostaphylos and Calamagrostis types described by Ilvessalo (1929); the Arctostaphylos -Calamagrostis and Calamagrostis types described by Kujala (1945) and the Pseudotsuga - Calamagrostis association described by Daubenmire (1952) would be included in this alliance. This alliance i s represented by two associations in the Cariboo Zone. Arctostaphylo (uva-ursi) - Junipero (communis) - Pseudotsugion *glaucae Arctostaphylo (uva-ursi) - Junipero (communis) - Pseudotsugetum *glaucae (ref. Tables; 59, 60, 61, 62, 83, and Fig. 18) Characteristic Combination of Species 152 Order Characteristic Species Pseudotsuga menziesii Arctostaphylos uva-ursi Carex concinnoides Hieracium umbellatum Spiraea b e t u l i f o l i a Dicranum polysetum Cladonia chlorophaea Cladonia g r a c i l i s Cladonia mitis Cladonia rangiferina Peltigera aphthosa Alliance and Association Characteristic Species Juniperus communis Prunus virginiana Apocynum androsaemifolium Artemisia campestris Gaillardia aristata Oryzopsis pungens Selaginella densa Cladonia nemoxyna Important Companion Species Pinus contorta Amelanchier a l n i f o l i a Shepherida canadensis Rosa acicularis Allium cernuum Agropyron spicatum Fragaria virginiana Solidago multiradiata Stipa richardsonii Tortula ruralis The Arctostaphylo - Junipero - Pseudotsugetum *glaucae develops on slopes with a surface topography which i s convex or straight. The slopes are moderately steep with measured gradients ranging from 17\u00C2\u00B0 to 24\u00C2\u00B0 and have southerly exposures. Snow accumulation i s low and duration short on these sites which are usually snow free by March 30. The s o i l surface i s covered by an extensive but very thin layer of l i t t e r composed mostly of Pseudotsuga menziesii leaves. In a l l sampled plots mineral s o i l was exposed, and in four plots rocks were present on the surface. The surface of sampled plots showed evidence of only slight water erosion 153 Arctostaphylo (uva-ursi) - Junipero (communis) -Pseudotsugetum *glaucae P l o t Data Number of Plots 1 2 3 4 5 6 7 Plot No. 016 057 058 018 009 010 056 Pl o t Size (m2) 400 400 400 400 400 400 400 Date analyzed 7/7 28/8 29/8 8/7 27/6 28/6 27/8 1967 1967 1967 1967 1967 1967 1967 Elevation (ft) 2500 2600 2650 2700 2800 2800 2850 L o c a l i t y WL WL WL WL WL WL WL 52\u00C2\u00B017' 52\u00C2\u00B017' 52\u00C2\u00B017' 52\u00C2\u00B027\" 52\u00C2\u00B012' 52\u00C2\u00B012' 52\u00C2\u00B012' 122\u00C2\u00B014 ' 122\u00C2\u00B014' 122\u00C2\u00B013 ' 122\u00C2\u00B021' 122\u00C2\u00B013' 122\u00C2\u00B014' 122\u00C2\u00B013 Physiography Landform slope (outwash terrace) slope slope (outwash terrace' ( t a l l u s ) , R e l i e f shape convex s t r a i g h t convex s t r a i g h t s t r a i g h t s t r a i g h t convex Exposure SW SE SE SE SW SW SW Slope gradient (\u00C2\u00B0) 21 19 17 24 22 23 21 Layer coverage (%) Aj layer - - - - 4 - 14 A 2 layer 9 24 9 17 12 10 16 A 3 layer 3 12 15 2 4 2 3 layer 5 5 6 15 13 5 1 B 2 layer 41 27 26 31 34 32 16 C layer 54 76 79 23 48 42 62 D layer 28 44 55 5 18 12 41 Plot coverage (%) Humus and l i t t e r 86 97 92 88 56 65 89 Mineral s o i l 12 3 7 4 43 33 9 Decaying wood 2 - 1 1 1 - -Rock - - - 7 2 2 3 S o i l Hygrotope Trophotope Erosion Drainage Horizon depth (in) L-H 1/2-0 1/2-0 1/2-0 1/2-0 1/2-0 n i l 1/2-0 Bl 0-10 0-4 0-4 0-6 0-3 0-4 0-5 B 2 10-25 4-14 4-23 0-14 3-19 4-22 5-24 C 25-56+ 14-41+ 23-50+ 14-30+ 19-48+ 22-58+ 24-42+ Parent material sandy outwash colluvium ....sandy outwash over outwash 60 Arctostaphylo (uva-ursi) - Junipero (communis) - Pseudotsugetum *glaucae 154 Number of P l o t s P l o t No. P l o t S i z e 018(3.1) 018(+.+> 009{+. + ) 018(2.1) 018(+.+) 018(3.2) 057(2.1) (V) (V) (V) (V) (V) (IV) (IV) (IV) (III) (III) (III) 61 Cladonia cenotea 62 Cladonia c o c c i f e r a 63 Cladonia cornuta 64 Cladonia c r i s p a t a 65 Dicranum fuscescens 66 Eurhynchium pulchellum 67 Hedwigia c i l i a t a 68 Parmelia chlorochroa 69 P e l t i g e r a h o r i z o n t a l i s 70 Rhacomi trium heteros t i chum. 82 Parmeliopsis hyperopta 83 Usnea h i r t a 84 Usnea s o r e d i i f e r a 85 Candelaria concolor 86 C e t r a r i a p i n a s t r i 87 Lecanora cadubr i ae 88 A l e c t o r i a americana 89 C e t r a r i a p l a t y p h y l l a 90 C e t r a r i a glauca 91 Usnea a l p i n a 9 2 Usnea g l a b r a t a 016(1.1 057(2.1 058(2.1 016 (2.2 057 (1.+ 057(1.1 018(1.+ 018I+.+ 018(1.+ 018(3.1 (III (III (III (II (II (II (I (I (I (I (I 155 indicating that surface runoff i s minimal. The s o i l has three mineral horizons formed under a thin L-H horizon. The surface horizon i s a dark coloured horizon ranging i n thickness from three inches to 10 inches and i t overlies a lighter coloured B2 horizon varying i n thickness from eight inches to 19 inches. Below the B 2 horizon i s a C horizon of undetermined depth. In two plots the C horizon showed a slight effervescence with hydrochloric acid, indicating the presence of carbonates. A study of the root distribution shows that roots are mostly concentrated in the surface horizons and only a few roots reach as deep as the C horizon. With the exception of plot 018, a l l horizons are composed mostly of sand and the sampled soil s are c l a s s i f i e d texturally, as sands. In plot 018 the horizon i s c l a s s i f i e d as a loam with only 39% sand. However, sand increases in amount with depth and 90% of the C horizon i s composed of sand. Coarse fragments ranging in size form gravels to stones were present in a l l sampled horizons. These fragments are mostly cherts, quartzites and shales which belong to the Cache Creek Group (geological formation after Tipper 1959). The Parent material of the s o i l s i s sandy g l a c i a l outwash with the exception of plot 018. In plot 018, which i s located at the base of a rock out-crop, the parent material i s considered to be colluvium overlying g l a c i a l d r i f t . The s o i l s of this association are very rapidly drained because of their coarse texture. The hygrotope of the Arctostaphylo - Junipero - Pseudotsugetum *glaucae i s rated as subxeric. Based on geomorpholocical evidence the slopes containing this assoc-iation are considered to be parts of outwash terraces. Plot 018 appears to be an exception and is thought to occur on a talus slope. The s o i l reaction i s circumneutral at the surface with pH values in the B horizon ranging from 6.7 to 7.1. It becomes alkaline with depth and pH Arctostaphylo (uva-ursi) Table 61 Soil Texture - Junipero (communis) - Pseudotsugetum *glaucae Number of Plots Plot No. 1 016 2 057 3 058 4 018 5 009 6 010 7 056 Horizon Textural class S S Clay (%) 5 2 S i l t (%) 3 2 Sand (%) 92 96 Coarse fragments g.c. g.c. B2 Horizon Textural class S S Clay (%) 0 5 S i l t (%) 0 7 Sand (%) 100 88 Coarse fragments g.c. g.c.s. C Horizon Textural class S S Clay (%) 1 0 S i l t (%) 1 1 Sand (%) 98 99 . Coarse fragments g.c.s. g.c.s. S 5 7 88 g.c. S 2 2 96 g.c.s. S 0 0 100 g.c.s. L 25 36 39 g.c.s. LS 4 25 71 g.c.s. S 1 9 90 g.c.s. S 2 0 98 g. s 1 0 99 g.c. S 5 5 90 g.c. S 4 5 91 g. S 2 4 94 g. s 2 0 98 g.c. S 5 5 90 g.c. S 1 1 98 g.c. LS 5 10 85 g.c.s. 157 Number of Plots 1 Plot No. 016 L-H Horizon Table 62 Soil Chemical Analysis Arctostaphylo (uva-ursi) - Junipero (communis) Pseudotsugetum *glaucae 2 '3 4 5 057 058 018 C% N% C/N P ppm Na K Ca Mg CEC pH Horizon C% N% C/N P ppm Na K Ca Mg CEC PH B2 Horizon 22.5 1.06 21.2 16.0 .88 .43 17.1 2.9 45.0 6.9 1.5 .08 18.8 5.0 1.06 .11 4.2 1.3 7.1 6.9 009 31.8 1.62 19. 15. .6 .0 .17 .51 17.5 3.7 42.6 6.3 2.0 .09 22.2 13.0 .10 .77 4.8 .9 12.0 6.9 24.0 1.17 20.5 18.0 .18 .71 14.0 2.8 51.7 5.7 7.3 .41 17.8 13.0 .10 .19 4.5 1.1 34.8 6.9 18.6 .93 20.0 12.0 .68 1.44 16.1 5.7 48.5 7.1 4.9 .31 15.8 12.0 1.03 .68 No L-H 9.8 12.3 28.8 7.5 2.2 .16 13.8 5.0 .07 .26 3.45 .78 11.7 6.8 6 010 16.3 .81 20.1 24.0 .17 .47 10.2 1.73 19.3 7.1 3.4 .22 15.5 9.0 .09 .28 3.2 .8 13.5 6.7 7 056 36.8 1.49 24.7 18.0 .19 .46 13.0 2.2 41.5 6.1 3.4 .18 18.9 5.0 .09 .45 10.0 1.2 26.1 7.1 c% 0 0 2.1 2.9 0 0 0 N% .03 .13 .13 .30 .02 .06 .10 C/N 0 0 16.2 9.7 0 0 0 P ppm 6.0 6.0 14.0 16.0 6.0 13.0 4.0 Na .45 .10 .09 .57 .09 .09 .09 K .03 .17 .04 .62 .15 .13 .09 Ca 6.5 4.5 4.0 14.8 3.25 2.7 4.5 Mg 8.0 1.0 1.7 15.7 .98 .82 1.9 CEC 3.4 6.1 23.5 19.2 8.3 16.4 4.7 pH 8.2 6.9 7.0 8.0 6.9 6.9 6.5 jrizon C% 0 0 0 3.3 0 0 0 N% .02 .11 .09 .21 .03 .05 .08 C/N 0 0 0 15.7 0 0 0 P ppm 3.0 5.0 6.0 10.0 4.0 8.0 5.0 Na 1.4 .08 .09 1.35 .09 .09 .09 K .05 .10 .03 .56 .06 .07 .05 Ca 4.7 7.0 5.3 23.0 4.15 3.0 3.5 Mg 7.2 .8 .8 22.3 .75 1.4 1.9 CEC 6.0 0 4.1 18.8 10.1 4.4 0 pH 8.0 7.9 8.0 8.3 7.8 7.3 7.0 158 values of the C horizon range from 7.0 to 8.3. This suggests that the parent material i s alkaline. The lower pH values at the surface are probably due to incorporation into the s o i l of humic acids derived from the L-H horizon which has pH values ranging from 5.7 to 7.1. Available phosphorus and total nitrogen are present in relatively high amounts in the L-H horizon and the carbon:nitrogen ratios are low indicating that the organic matter contains sufficient nitrogen for decomposition. There i s an accumulation of organic matter i n the horizon as judged by the presence of carbon which ranges from 1.5% to 7.3%. In the B^ horizon nitrogen i s present i n low amounts but the carbon:nitrogen ratios are also low indicating that n i t r i f i c a t i o n i s taking place and that nitrogen i s available to higher plants. The amount of carbon decreases with depth and i s present i n the B\u00C2\u00A3 horizon of only two plots and in the C horizon of only one plot. Similarly, total phosphorus and total nitrogen decrease i n amounts from the surface down the p r o f i l e with nitrogen being present in only trace amounts in the lower horizons. Exchangeable cations are present i n the mineral s o i l i n low amounts with calcium dominating the exchange complex. The calcium concentration of the l i t t e r i s substantially higher than that of the mineral s o i l because of the high amount of calcium present in the l i t t e r of Pseudotsuga menziesii (Daubenmire 1953). Exchangeable sodium and magnesium are present i n very low amounts as i s potassium which decreases constantly with depth. The cation exchange capacity i s very high in the L-H horizon because of the high amount of organic matter present. It decreases sharply through the mineral horizons. The lower cation exchange capacity i s due partly to the lower concentration of organic matter and partly to the coarse texture of the s o i l . These soils do not appear to be rich and thus are considered to be submesotrophic to oligotrophic. The soi l s are cl a s s i f i e d as Orthic Brown Wooded soil s because they have an L-H horizon, a brownish B horizon and a weakly acidic to slig h t l y 159 alkaline s o i l reaction. Structurally, the vegetation of this association i s composed of four layers. The tree layer i s represented by three sublayers of which the A2 i s best developed with a percentage cover ranging from 9% to 24%. The shrub layer consists of two sublayers\u00E2\u0080\u0094a poorly developed B^ layer with a coverage ranging from 1% to 15% and a well developed B2 layer with a coverage ranging from 16% to 41%. The herb layer (C) has a percentage cover ranging from 23% to 79% and the D layer i s variably developed with a percentage cover ranging from 5% to 55%. Pseudotsuga menziesii dominates the association and i s present in a l l three sublayers of the tree layer. It has a low density and forms an open canopy. The only other tree species present i s Pinus contorta which occurs in the A2 and A^ layers but only with a constancy of class III. The B^ layer consists entirely of transgressives of Pinus contorta and Pseudotsuga menziesii which occur aggregated in microhabitats suitable for seedling establishment. Both species are also represented i n the B2 layer but only Pseudotsuga menziesii seedlings are present i n the C layer. The B2 layer i s dominated by Juniperus communis with average species significance of 5.6. This species i s indicative of dry exposed habitats. Other constant shrub species include % Shepherdia canadensis, Rosa acicularis, Amelanchier a l n i f o l i a and Spiraea b e t u l i f o l i a . Arctostaphylos uva-ursi, which i s characteristic of dry forest habitats, i s the most important species of the C layer with an average species significance of 6.7. Carex concinnoides is a constant associate with an average species significance of 3.7. Oryzopsis pungens, Apocynum androsaemifolium, and Artemisia campestris, a l l of which reach their best development on dry exposed sites, are constant species characteristic for the association. Gaillardia aristata although only present with a constancy of class III, i s also 160 considered as characteristic because of i t s exclusiveness for this association. Agropyron spicatum, Achillea millefolium, Allium cernuum, Stipa richardsonii, Arabis h o l b o e l l i i and Festuca saximontana are present because of the rapidly drained so i l s and open tree canopy which provides an exposed habitat. The presence of these species coupled with the absence of Calamagrostis rubescens i s indicative of the dryness of this forest association. Selaginella densa, a characteristic species for the association, dominates the D layer with an average species significance of 4.4. The most significant bryophytes are Tortula ruralis and Ceratodon purpureus with average species significances of 3.4 and 2.7 respectively. Dicranum polysetum and Pleurozium schreberi are present with low significance at the base of woody plants where more moisture i s available. Lichens are more important than bryophytes in this submesic habitat with the dominant species being Cladonia pocillum and C. g r a c i l i s , which have average species significances of 3.6 and 3.3 respectively. The only other constant species are Peltigera malacea and Diploschistes canadensis. Important non-constant species include: Peltigera canina var. rufescens, Cladonia nemoxyna, C. pyxidata, C. mitis, C. chlorophaea and C. rangiferina. The epiphytic growth in this association i s poorly developed probably because of the dry southerly exposures. Alectoria glabra, Cetraria canadensis, Hypogymnia physodes, Letharia vulpina and Parmelia sulcata are the only constant species. A l l studied plots of this association were located north of Williams lake on south exposures. The association also occurs on the Fraser Plateau at low elevations in the major valleys on coarse textured terraces. However, here i t i s on northerly exposures because the general climate i s drier and warmer. 161 Fig. 18. The Arctostaphylo - Junipero - Pseudotsugetum *glaucae showing the characteristic open forest development. This association i s developed on sandy g l a c i a l outwash and i s dominated by Pseudotsuga menziesii, Juniperus communis and Arctostaphylos uva-ursi. Fig. 19. The Calamagrostido - Pseudotsugetum *glaucae calamagrostido -pseudotsugetosum *glaucae showing the excellent development of Pseudotsuga menziesii. The climax stature of this association i s indicated by the abundant Douglas-fir regeneration. Calamagrostis rubescens i s the dominant C layer species. 162 The Arctostaphylo - Junipero - Pseudotsugetum *glaucae has been burned in recent history as evidenced by f i r e scarred trees. The association also has a history of slight grazing which does not appear to have altered the vegetation structure. Calamagrostido (rubescentis) - Pseudotsugion *glaucae 1. Calamagrostido (rubescentis) - Pseudotsugetum *glaucae (ref. Tables; 63, 64, 65, 66, 83, and Fig. 19, 20, 21) Characteristic Combination of Species Order Characteristic Species Pseudotsuga menziesii Arctostaphylos uva-ursi Carex concinnoides Hieracium umbellatum Spiraea b e t u l i f o l i a Dicranum polysetum Cladonia chlorophaea Cladonia g r a c i l i s Cladonia mitis Cladonia rangiferina Peltigera aphthosa Alliance Characteristic Species Aster conspicuus Calamagrostis rubescens Hypnum revolutum Polytrichum juniperinum Rhytidiadelphus triquetrus Association Characteristic Species Astragalus miser Cetraria ericetorum Cladonia cornuta Stereocaulon tomentosum Important Companion Species Rosa acicularis Shepherdia canadensis Solidago multiradiata Lathyrus ochroleucus Vicia americana Anemone multifida Erigeron speciosus 163 63 Plot Data Number of Plots calamagrostido Calamagrostido (rubescentis) pseudotsugetosuin Pseudosugetum \"glaucae i contortae Plot No. Plot Size (m2) Date analyzed Elevation (ft) Locality Physiography Landform Relief shape Slope gradient (\") Layer coverage (\u00C2\u00BB) Aj layer A 2 layer A 3 layer Bj layer B 2 layer C layer D layer Plot coverage (%) Humus and l i t t e r Mineral Soil Decaying wood Soil Nygrotope Trophotope Erosion Drainage Horizon depth (in) L-H 061 400 7/6 1968 006 400 23/6 1967 51*47\" 52*25' 122*34' 122*23' 007 400 24/6 1967 S2*25' 122*23' 067 400 25/6 1968 51*46' 122*34' 013 400 3/7 1967 52*26' 122*22' 014 400 5/7 1967 52*26' 122*22' slope bench convex ... .concave. Slope straight convex straight .submesic - mesic .-permesotrophic. n i l well 2-0 1-0 1-0 0-9 0-5 0-4 9-21 5-21 4-29 21-30+ 21-32+ 29-36+ 2-0 0-11 1-0 0-20 1-0 0-19 051 400 18/8 1967 51*46' 122*37' 023 400 22/7 1967 51*43' 122*38' 025 400 23/7 1967 51*43' 122-38' 034 400 31/7 1967 51*47* 122*40' 069 400 1/7 1968 51*48' 122*48' 070 400 2/7 1968 51*48' 122\u00C2\u00B048' . .concave straight concave f l a t . N NE NW neutral 088 400 26/7 1968 51*43' 122*55' gully gully slope bench Blope ....mesic.... .tnesotrophic. n i l well 2-0 2-0 0-10 0-3 3-15 10-30* 15-27+ 2-0 0-13 13-26 26-36+ 1-0 0-10 10-19 19-32+ 1-0 0-13 1-0 0-7 2-0 0-6 Parent material .glacial d r i f t glacial d r i f t 164 64 Calanagroatldo (rubeacantla) \u00E2\u0080\u00A2 calamagrostido - peeudotsugatoau* 'glauca* F**udotaug*tua 'olaucae pknetoau* contort O t l 006 007 0(7 0 t l O i l 400 400 400 400 400 400 2SO0 2\u00C2\u00AB50 1*10 3(00 1850 29O0 T 1 \u00E2\u0080\u00A2 10 11 12 13 051 021 0JS 034 049 070 O i l 400 400 400 400 400 400 400 1000 1025 JOTS 1120 3400 3400 3*50 Populus tremuloldc* 7 Spiraea b a t u l i f o l l e \u00E2\u0080\u00A2 Juniperus communis > Aaelanchier \u00E2\u0080\u00A2 l n i f o t i * 10 Juniperus acopulorun C Layer 11 C a l a n a g r o i t i a rube*cent 1] Arctottaphyloa u v i - u m 13 Astragalus o i l e r 14 Galium boreale t l Solidaqo n u l t i r a d l a t a Pseudotsuga Rieniles i i I t A c h i l l e a a l l l e t o U u * 17 Aster conspicuua I I L i t h y r u t ochroleucus 1* V l e i * amer lean* 20 Anemone n u l t i f i d a 21 Agropyron apicatun Rosa a c i c u l a r i s 32 Fragaria v i r g i n i a n a 23 Hieraciun umbellatum 24 A l t e r c i l i o l a t u a 25 Erigeron apecioaui I t A l l i u a cernuun Pinua contorta 17 Taraaacun o f f i c i n a l * 21 Geranium vlscoslisimum Spiraea b e t u l i f o l k a 39 Care* concinnoides 30 Carea coneinns 31 Antennaria neglect* 32 Antennaria anaphaloidea 33 Antennaria rosea 34 Ceum t r i f l o r urn 35 Arnica c o r d i f o l i a 36 S t i p a r i c h a r d s o n i i 37 pyrole vlrens )\u00E2\u0080\u00A2 Agoaeria glauca 39 Elynus hirautua 40 LIthaapernun ruderale 41 Mahonla aquifolium 43 v i o l a adune* *1 Agropyron aubsccundun 44 Disporum trachycerpua 45 P o t e n t i l l a pennsylvanlca 4S Linnaea b o r e a l i a 47 Antennaria umbrinelle 41 Oryiopsia pungent 49 Poa i n t e r i o r 50 Ceraetiure arvense 51 Epiloblum anguatifolium S3 Sytnphoricarpos O c c i d e n t * t i l 3) Kauchera c y l i n d r i c a Populus treouloides Juniperua scopuloruai 34 S t i p a Columbiana 5( Dleranum polyaetum 57 Eurhynehium pulchelluai SI Hyloconiun splendcni 59 Rnytldiadelphua t r i q u e t f u s 40 Ceratadon purpureua t l Dicranun fusceacens t l Hypnum revolutum 63 p t i l i u m c r i s t a - c a r t r e n i i * 44\"DrepanocIadua uncinatua 13 P o l y t r i c h i a juniperir.ua-t t Tiffenla a u a t r i a c a t7 DicranuB accparium t l Hrachythecium salebroaun 19 Hnium splnulosum 70 T o r t u l a r u r a l i a 71 P e l t i g e r a malacea 72 P e l t i g e r a aphthoae 73 Cladonia g r a c i l i s 74 P e l t i g e r a canina var. .-ufesc 75 Cladonia r e n g i f e r i n a 7t Stereocaulon toaientosujn 77 C e t r a r i a e r i c e t o r u n 71 P e l t i g e r a canina var. canlnj T9 Cladonia cornuta \u00E2\u0080\u00A20 Cladonia mitts I t Cladonia chloropnaea \u00E2\u0080\u00A22 Cladonia pyxidata 13 Cladonia p o c i l l u a i \u00E2\u0080\u00A24 C e t r a r i a c u c u l l e t a IS Cladonia arbuscule I t Cladonia multiformis 17 B a c i d i a aphaeroides I I B l a a t e n i a sinapisperm* \u00E2\u0080\u00A29 Lecidea bcrcngerlana 7.4 fi.l 4.4 1.2 S.4 4.2 4.3 2.2 2.3 3.2 3.2 1.3 1.2 - - 3.1 1.2 3.1 2.3 1.2 1.2 1.2 t . 2 2.2 2.; 4.1 2.1 2.1 S.2 ).t 1.3 1.7 2 2.1 - I.I 2 3.1 2.* i . : * 2.* 1.* 2.' .3 7.4 l . f 3.1 I.* 2.1 2.2 2.2 1.2 7.4 7.3 6.3 3.2 1.1 4.2 1.1 1.1 1.2 1.2 1.2 4.1 1.2 TOTAL SPECIES ( i n c l . aporadics 1 Ac;ropyron trachycaului 1 Agrostis acabra ] Antennaria p a r v l f o l l a I A r m a r i a l a t e r i f l o r a ( Artemisia campestrii S Aater eampeatrla i l l i r a , Epiphyses 1 IS A l a c t o r i a a l a n r * J i t Mypc-jymnla phyaodei 117 L e t h a r i a vi.lplna 111 P a r M l t a Bulcata 119 P i r M l I o p i L i aatilgua 120 P a r M l i o p i l a hyper opt a 12 1 Uanea^labreecene 132 C e t r a r i a canadenal* 12) Arceuthobiuin anarlcanum 124 C e t r a r i a p l n a a t r l 125 C e t r a r i a m e r r e l l l l U t Lecanora v a n a 007(...( 02X1.1) 013(2.1) 025(1.1) 011(1.1) 02SH *) 0)4 I* 02512.11 007(*.\u00E2\u0080\u00A2) 070(2.*) 070(1.1) (V) (IV) (111) ( I I I I ( I I I ) I I I I ) 103 ledum stenopataluai 10) Senecio pauperculue 104 S s i l a c l n a a t e l l a t a 105 Anblyetagiuv serpent lOt C e t r a r i a n i v a l i s 107 Cladonia cenotea 101 Cladonia furcata 10* Cladonia scabrluacula 110 Pannaria p e i i i o i d a a 111 P e l t i g e r a venoaa 112 P o h l i a crude 11) P o l y t r i c h i a p i l i f e r u a i 114 M t y t i d l u * rugoau* 131 (Jenaa hkrte 121 A l a c t o r i a ajwrlcen* 129 C e t r a r i a ha l e i 1)0 C e t r a r i a erlcetorvam 1)1 C e t r a r i n qlauca 1)3 Uinea a o r e d i l f e r a D ) A l a c t o r i a glabra 1)4 l u a l l l a punctata IIS HypOvY*>nia v i t t a t a I)\u00C2\u00AB Uanea glebrata 1)7 Uanaa e ^ a b r a t a 1II l a n t h o r l a f a l l a * 0tl(l.\u00C2\u00BB) 0 t 7 [ l . l ) 011(1.1) Of7(3.1) 165 Important Companion Species (Cont'd) Allium cernuum Pleurozium schreberi Eurhynchium pulchellum The Calamagrostido-Pseudotsugetum *glaucae i s the most common forest association in the Cariboo Zone being widespread on the Fraser Plateau as well as i n the area north of Williams Lake. It occurs i n shallow gullies, on level benches or on slopes with gentle to moderately steep gradients. Measured slope gradients ranged from 2\u00C2\u00B0 to 21\u00C2\u00B0 . No specific slope exposure appears to favour the development of this association and a l l exposures were represented by the sampled plots. The surface topography i s varied with convex, concave, straight and f l a t r e l i e f shapes represented. There i s no evidence of surface erosion and the soi l s are rated as being well drained. The hygrotope of this association i s considered to be subhygric up to mesic. The s o i l surface i s covered by a thin layer of l i t t e r varying i n extent from 92% to 98% of the total surface area. Decaying wood was present on a l l plots sampled and a small amount of mineral s o i l was exposed in seven plots. The s o i l i s developed from a parent material of glacial d r i f t and has the following horizon sequence: A thin L-H horizon overlying a brownish coloured B horizon and a light coloured C horizon which in some samples effervesced sl i g h t l y with hydrochloric acid. In some soil s the B horizon is subdivided into a B^ and B 2 horizon. The surface mineral horizon (B^) i s medium textured and composed predominately of s i l t s and sands. The sampled horizons are c l a s s i f i e d as loams, sandy loams, or clay loams. Coarse fragments, mostly of gravel size, are constantly present. In most so i l s the clay content increases with depth and the C horizon i s finer textured. However, in the three plots (067, 013, 014) there was an increase i n sand content, and,\u00E2\u0080\u009Ethe C horizons were coarser than the corresponding surface horizons. Sampled C horizons have 166 a range of textural classes from sands to s i l t clay loams. Coarse fragments varying in size from gravels to stones were present in a l l samples. The s o i l reaction i s acidic to neutral at the surface and increases in a l k a l i n i t y with depth. Measured pH values for the L-H horizon ranged from 4.7 to 7.1. The B horizon i s weakly acidic to neutral with pH values ranging from 6.0 to 7.3 and the C horizon i s circumneutral to alkaline with pH values ranging from 6.5 to 8.1. The B-^ horizon appears to be enriched with organic matter originating from the L-H horizon. Measured carbon ranges from 2.7% to 9.3% in the B horizon and decreases down the p r o f i l e . Carbon i s generally not detectable i n the C horizon. Total nitrogen i s present in high amounts in the L-H horizon, decreases to moderate concentrations in the B horizon and i s present in low amounts in the C horizon. The carbon:nitrogen ratios are also high in the L-H horizon suggesting that decomposition and n i t r i f i c a t i o n takes place slowly. However, i n the B horizon the carbon:nitrogen ratios are more favourable indicating that nitrogen i s available for plant growth. Available phosphorus i s present in high amounts in the L-H horizon with values ranging from 10% to 32%. It decreases in the mineral s o i l with depth corresponding to the decrease i n organic matter content. Similarly, exchangeable potassium i s present in high concentration in the L-H horizon and decreases in concentration slightly in the mineral s o i l . Exchangeable sodium i s present in low to moderate amounts in a l l horizons but i s slightly higher at the surface. High amounts of exchangeable calcium and magnesium occur in the mineral s o i l with calcium reach-ing a maximum concentration of 16.8 meq/100 g and magnesium a maximum of 10.4 meq/100 g. Calcium i s present in greater concentrations than magnesium and both cations tend to be present in higher amounts in the C horizon than in the B horizon. However, the highest concentrations of calcium are in the L-H horizon where values range from 7.1 meq/100 g to 37 meq/100 g. This i s because the l i t t e r o Table 65 Soil Texture Calamagrostido (rubescentis) - Pseudotsugetum *glaucae calamagrostido - pseudotsugetosum *glaucae pinetosum contortae Number of Plots Plot No. 1 061 2 006 3 007 4 067 5 013 6 014 7 051 8 023 9 025 10 034 11 069 12 070 13 088 Bi Horizon Textural class Clay (%) S i l t (%) Sand (%) Coarse fragments B2 Horizon Textural class Clay (%) S i l t (%) Sand (%) Coarse fragments C Horizon Textural class Clay (%) S i l t (%) Sand (%) Coarse fragments L 13 50 38 g-SiL 3 61 36 9-SL 13 23 64 L 18 47 35 g-L 13 47 40 SCL 27 24 49 L 20 36 44 g-SCL 31 22 47 g.c.s. g.c.s. SCL 32 25 43 L 17 40 43 g.c. No B 2 LS 0 16 84 SL 11 20 69 No B 2 S 3 3 94 SL 19 28 53 g.c.s. g.c.s. No B 2 S 3 6 92 g.c.s. g.c.s. g.c.s. g.c.s. g.c.s. g.c.s. L 27 31 42 g.c. No B 2 L 23 36 42 L 13 38 49 g-L 23 32 45 L 19 39 42 g.c. SCL 21 28 51 L 27 32 41 SCL 21 25 54 CL 30 36 34 g-CL 28 38 34 g.c.s. g.c.s. g.c. SiCL 34 50 16 SL 8 41 51 NO B 2 L 14 35 51 SL 3 32 65 No B 2 SL 16 30 54 SL 9 30 61 g.c.s. g.c.s. g.c. No B 2 L 23 33 44 g.c.s. g.c.s. g.c.s. g.c.s. g.c.s. g.c.s. g.c.s. 168 B2 Horizon C% N% C/N P ppm Na K Ca Mg CEC pH C Horizon Table 66 S o i l Chemical Analysis Calamagrostido (rubescentis) - Pseudotsugetum *glaucae calamagrostido - pseudotsugetosum 'glaucae pinetosum contortae 5.9 .20 29.5 13.0 .13 .37 6.6 6.6 28.3 6.9 1.8 .11 16.4 6.0 .11 1.10 11.2 5.1 12.0 6.8 .06 3.0 .43 .54 11.7 1.9 12.4 6.5 No B 2 No B 2 No B 2 No B 2 0 .02 0 4.0 .87 4.87 7.5 4.6 18.5 6.8 0 .03 0 6.0 .69 .18 5.0 6.1 21.7 7.5 1.3 .11 11.8 7.0 1.30 .38 7.0 7.4 18.3 7.4 No B 2 No B 2 Number of Plots 1 2 3 4 5 6 7 8 9 10 11 12 13 Plot NO. 061 006 007 067 013 014 051 023 025 034 069 070 088 L-H Horizon C% 46.2 42.8 22.0 45.4 18.4 32.8 21.4 33.4 32.8 32.7 41.6 16.3 . N% 1.64 1.63 .84 1.47 .87 .98 .88 1.07 1.10 .92 1.09 .94 C/N 28.2 26.3 26.2 30.9 21.1 33.5 24.3 31.2 29.8 35.5 38.2 17.3 * P ppm 32.0 31.0 17.0 18.0 13.0 18.0 18.0 10.0 15.0 21.0 12.0 13.0 Data Na .17 .18 .19 .19 1.23 .11 .18 2.78 1.72 1.30 .64 .34 not K 2.36 1.33 1.74 2.26 .65 1.28 6.15 .24 1.03 1.28 1.42 .88 a v a i l Ca 27.8 7.1 18.3 37.0 16.2 20.1 20.5 12.0 22.2 10.0 24.8 26.0 able Mg 12.8 4.8 4.8 6.6 3.0 5.5 7.0 7.0 14.6 5.7 12.8 6.2 . CEC 94.7 88.4 58.7 87.0 39.4 83.7 64.8 63.4 71.8 84.3 72.9 34.7 pH 6.0 6.8 6.7 5.7 7.1 6.6 5.4 , 5.6 4.9 4.7 5.2 5.3 '\u00E2\u0080\u00A2 Bi Horizon c% 7.1 0 4.8 6.0 0 4.9 2.6 7.5 3.8 3.4 2.7 0 9.3 N% .29 .04 .25 .24 .05 .29 .13 .72 .23 .21 .12 .12 .58 C/N 24.5 0 19.2 25.0 0 16.9 20.0 10.4 16.5 16.2 22.5 0 16.0 P ppm 11.0 7.0 4.0 3.0 4.0 5.0 9.0 16.0 4.0 16.0 16.0 4.0 7.0 Na .08 .09 .09 .11 .13 .88 .09 .69 1.26 1.13 .19 .18 .31 K 1.09 .97 .68 .94 .35 1.18 1.99 2.56 .27 .38 .37 .36 .83 Ca 7.5 7.4 8.0 10.0 4.9 9.4 7.25 10.0 7.0 7.5 8.3 5.5 8.5 Mg 5.7 2.0 2.7 4.1 2.5 3.5 3.5 5.3 6.7 6.6 3.8 2.8 5.8 CEC 32.5 17.4 18.3 18.3 21.2 22.0 16.3 31.0 13.6 21.7 34.6 7.6 36.5 pH 6.8 7.3 6.9 6.8 6.5 6.8 6.2 7.4\" 6.9 6.6 6.2 6.0 6.2 No B 2 c% 3 8 0 0 0 0 0 0 0 0 0 1.8 2.6 5.8 N% 16 .03 .04 .13 .05 03 .06 .03 .03 .06 .16 .16 .16 C/N 23 8 0 0 0 0 0 0 0 0 0 11.3 16.3 36.3 P ppm 8 0 2.0 3.0 5.0 5.0 6 0 6.0 6.0 3.0 5.0 7.0 9.0 5.0 Na 31 .12 .50 .12 .28 16 .10 .74 1.13 1.69 .40 .32 .20 K 27 .87 .51 .33 3.13 17 1.73 1.03 .15 .37 .60 .41 1.12 Ca 5 9 9.9 16.8 5.7 3.5 5 9 9.0 10.5 9.0 8.5 7.8 9.1 8.4 Mg 6 7 4.8 1.1 2.7 2.4 2 6 4.9 4.8 5.8 7.0 10.4 8.9 6.9 CEC 18 6 13.5 10.0 4.9 12.2 7 4 22.5 13.5 24.8 9.8 23.1 20.5 19.9 pH 7 3 7.0 6.5 7.0 6.7 7 4 6.8 8.1 8.0 8.0 7.5 6.5 7.1 169 Pseudotsuga menziesii i s rich in calcium (Daubenmire 1953). The high concentrations of calcium and magnesium i n the mineral s o i l may in part account for the alkaline reaction of the C horizon. The cation exchange capacity of the L-H horizon i s very high with values ranging from 34.7 meg/100 g to 94.7 meg/100 g. It decreases in the mineral s o i l but i s s t i l l high because the s o i l has a high clay content. Cation exchange capacity ranges from 7.6 meg/100 g to 36.5 meg/100 g in the B horizon and 4.9 meg/100 g to 24.8 meg/100 g i n the C horizon. These soils are considered to be edaphically rich and the association i s rated as mesotrophic to permesotrophic. The soi l s of this association are classed as Orthic Brown Wooded soils because they have an L-H horizon, a brownish B horizon and a weakly acidic to alkaline s o i l reaction. c Structurally, the association consists of four vegetation l a y e r s \u00E2\u0080\u0094 a well developed tree layer, a poorly developed shrub layer, a well developed herb layer and a well developed bryophyte and lichen layer. The tree layer has three sublayers of which the A2 is the best developed. Pseudotsuga menziesii i s the only constant tree species. The shrub layer consists of two sublayers. The B^ i s composed entirely of tree transgressives of which Pseudotsuga menziesii i s the most common species. The layer i s dominated by Rosa acicularis with an average species significance of 2.5. Shepherdia canadensis, Juniperus communis, Amelanchier a l n i f o l i a and Juniperus scopulorum are a l l present as non-constant species with lower significances. Symphoricarpos occidentalis, which has a constancy of class III, i s indicative of the permesotrophic habitat. The herb layer (C) has a percentage cover ranging from 42% to 90%. It i s dominated by Calamagrostis rubescens with an average species significance of 6.9 and Arctostaphylos uva-ursi with an average species significance of 3.3. 170 Astragalus miser, which i s characteristic of this association i s a constant associate with an average species significance of 2.6. Galium boreale, Solidago multiradiata, Achillea millefolium, Aster conspicuus and Pseudotsuga menziesii (as seedlings) are the only other constant species of the C layer. The presence of Agropyron spicatum, Cerastium arvense, and Heuchera cylindrica i s indicative of the grassland influence on this forest association. Non-constant C layer species important in the characterization of this association include: Lathyrus ochroleucus, V i c i a americana, Anemone multifida, Fragaria virginiana, Hieracium umbellatum, Erigeron speciosus and Allium cernuum. The bryophyte and lichen layer (D) varies from poorly developed to well developed as indicated by i t s percentage cover which ranges from 5% to 72%. The constant bryophyte species are: Pleurozium schreberi, Dicranum polysetum, Eurhynchium pulchellum. Important non-constant species include: Hylocomium splendens, Rhytidiadelphus triquetrus, Ceratodon purpureus, Dicranum fuscescens and Hypnum revolutum. Lichens are less important in the structure of the D layer than are bryophytes and no constant species are present. Common species of constancy class IV include: Peltigera malacea, P. aphthosa, Cladonia g r a c i l i s , Peltigera canina var. rufescens and Cladonia rangiferina. Stereocaulon tomentosum, Cetraria ericetorum and Cladonia cornuta, although present with low constancy, are considered as characteristic species of the association. The epiphytic flora i s moderately well developed and the constant species are: Alectoria glabra, Hypogymnia physodes, Letharia vulpina, Parmelia sulcata, Parmeliopsis ambigua, Parmeliopsis hyperopta and Usnea glabrescens. The Clamagrostido - Pseudotsugetum *glaucae i s used primarily for logging as these sites are very productive for Douglas\u00E2\u0080\u0094fir. It i s grazed only l i g h t l y because Calamagrostis rubescens appears to have a low p a l a t i b i l i t y for cattle. 171 The Calamagrostido - Pseudotsugetum *glaucae i s divided into two subassociations which are: (1) the calamagrostido - pseudotsugetosum *glaucae and (2) the pinetosum contortae. These are differentiated on the basis of species composition of the tree layer, minor f l o r i s t i c differences of the B and C layers and small habitat differences. Calamagrostido (rubescentis) - Pseudotsugetum *glaucae 1. calamagrostido (rubescentis) - pseudotsugetosum *glaucae (ref. Fig. 19) Differential Species Spiraea b e t u l i f o l i a Carex concinnoides This i s the drier of the two subassociations and i s rated as mesic. It reaches best development on exposed slopes at low elevations. It i s most common north of Williams Lake, in the continuous forest area, where i t occurs usually on southerly exposures. Snow accumulation i s low and snow duration short in this subassociation with most sites being snow free by mid-April. The s o i l reaction has a narrower range than that described for the association. The L-H horizon i s weakly acidic to neutral with pH values ranging from 6.0 to 7.1. The B and C horizons are circumneutral with pH ranges of 6.5 and 7.3 and 6.5 to 7.4 respectively. This and the drier hygrotope appear to be the only edaphic conditions which differentiate the calamagrostido - pseudotsugetosum *glaucae. F l o r i s t i c a l l y , the calamagrostido - pseudotsugetosum *glaucae i s differentiated by the presence of Spiraea b e t u l i f o l i a with an average species significance of 2.7 and Carex concinnoides with an average species significance of 2.3. Antennaria neglecta, Elymus hirsutus, Mahonia aquifolium and Disporum trachycarpum are present in the Calamagrostido - Pseudotsugetum *glaucae only in this subassociation but with low constancy and significance. 172 The subassociation i s dominated by Pseudotsuga menziesii which occurs in the A,B, and C layers. It i s the only tree species present and forms an open canopy. Rosa acicularis dominates the shrub layer with an average species significance of 1.7 but i s less important here than in the pinetosum contortae. The drier habitat i s reflected i n the poorer development of the C layer which has a percentage cover ranging from 42% to 78%. Clamagrostis rubescens i s the dominant species with an average species significance of 6.0 which i s considerably lower than i t s rating in the pinetosum contortae. Similarly because of the drier habitat and low degree of shade the D layer i s less well developed than i t s counterpart i n the pinetosum contortae Pleurozium schreberi i s the dominant species but with a lower species significance than in the pinetosum contortae. Lichens are more abundant in this subassociation with Peltigera malacea, and Peltigera canina var. rufescens being the most important species. The calamagrostido - pseudotsugetosum *glaucae i s considered to be in climax state and appears to be represented by two varieties of different hygrotopes although these were not distinguished i n this study. The sub-association described here represents the drier variety which i s developed at low elevations on exposed slopes. The second variety develops i n the Cariboo Zone at higher elevations (over 3000 ft) and i s common throughout the Douglas-f i r Zone. Here a cooler moister climate prevails which w i l l produce a moister hygrotope. Of the sampled plots, 061 and 067 most closely approximate this moist variety as they occur on north exposures, have more acidic surface s o i l reactions and have well developed bryophyte and lichen layers with Pleurozium schreberi reaching a species significance of 6 and 7 respectively. This subassociation appears to have been burned in recent history based on the presence of f i r e scarred trees. Following f i r e , regeneration i s 173 considered to be by Pseudotsuga menziesii, because at the low elevations where this subassociation develops, Pinus contorta appears unable to compete successfully for control of the edaphically rich, dry sites. However, in the moist variety mentioned above, regeneration following f i r e would probably be by Pinus contorta as this species i s more common in the higher elevations where i t i s established quickly on newly available sites. Calamagrostido (rubescentis) - Pseudotsugetum *glaucae 2. pinetosum contortae (ref. Fig. 20 and 21) Differential Species Pinus contorta Geranium viscosissimum Carex concinna Geum triflorum Linnaea borealis Populus tremuloides Epilobium angustifolium The pinetosum contortae i s considered as a moister subassociation and i s rated as mesic. It is most common on the Fraser Plateau and i s best developed at higher elevations where the climate i s cooler. Sampled plots ranged in elevation from 3000 feet to 3650 feet. It i s formed on slopes and gullies with northerly exposures or on level benches. Snow duration i s longer than in the calamagrostido - pseudotsugetosum *glaucae. The sites may also benefit from seepage i n the early spring. The s o i l reaction of the L-H and B horizons is more acidic than in the calamagrostido -pseudotsugetosum *glaucae but the C horizon has a similar circumneutral to alkaline reaction. Measured pH values of the L-H horizon range from 4.7 to 5.4 and pH values of the B horizon range from 6.0 to 7.4. The lower surface pH values are thought to result from the l i t t e r of Pinus contorta which i s more acidic than that of Pseudotsuga menziesii. F l o r i s t i c a l l y , this subassociation i s differentiated largely on the 174 Fig, 20. The Calamagrostido - Pseudotsugetum *glaucae pinetosum contortae showing the typical high stem density of generally even-aged lodgepole pine trees. Standing dead trees are common in this subassociation and can be seen on the l e f t of the picture. The subassociation has a well developed herb layer (C) dominated by Calamagrostis rubescens. Fig. 21. The Calamagrostido - Pseudotsugetum *glaucae pinetosum contortae with a well developed understory of Pseudotsuga menziesii. It w i l l eventually dominate this forest because of i t s shade tolerance and the pinetosum contortae w i l l advance, successionally, to the calamagrotido -pseudotsugetosum *glaucae. 175 constant presence of Pinus contorta which occurs as the dominant tree species. It forms an almost closed canopy with species significances ranging from 5 to 7. Pseudotsuga menziesii i s less important in this subassociation and reaches i t s best development as an understory tree i n the A^ layer. However, Pseudotsuga menziesii transgressives and seedlings are constantly present in the subordinate vegetation layers. Populus tremuloides is present in the tree and shrub layers of this subassociation and i s indicative of the moist conditions. Rosa acicularis i s the dominant shrub species, as i n the calamagrostido - pseudotsugetosum *glaucae, but occurs here with an average species significance of 3.1. Because of the moister hygrotope the C layer i s better developed in this subassociation, with a percentage cover ranging from 63% to 90%. Calamagrostis rubescens i s again the dominant species but occurs here with a higher species significance of 7.7. Geranium viscosissimum, and Geum triflorum are represented in the Clamagrostido - Pseudotsugetum *glaucae only i n this subassociation. Similarly, Linnaea borealis and Epilobium angustifolium are present only here and are considered to be good indicators of the moister conditions that prevail. Antennaria rosea, Stipa richardsonii, Agropyron subsecundum, Potentilla pennsylvanica and Stipa Columbiana are present i n the pinetosum contortae because of the close proximity of communities of the Stipion columbianae. The bryophyte and lichen layer i s better developed i n this subassociation because of the moister habitat, acidic s o i l surface and higher degree of shade. The most important species are Pleurozium schreberi, Dicranum polysetum and Eurhynchium pulchellum. This subassociation i s considered to be of successional status as the dominant Pinus contorta w i l l eventually be replaced by the more shade tolerant Pseudotsuga menziesii which now occurs as an understory species (Fig. 21). Succession w i l l terminate in a climax community of the moist variety 176 of the calamagrostido - pseudotsugetosum *glaucae because of the cooler climate which prevails in the area now occupied by the pinetosum contortae. The pinetosum contortae i s considered to be strongly affected by f i r e as old charred logs are often present on the s o i l surface and some of the older trees are f i r e scarred. This subassociation i s regarded to be maintained by repeated burning as Pinus contorta appears to be shade intolerant on these moist sites and thus requires open sites for establishment and survival. At these higher elevations colonization of new areas i s by Pinus contorta as Douglas-fir does not seem to be able to compete successfully here, for space, in the early stages of succession. 2. Rhytidiadelpho (triquetri) - Pleurozio (schreberi) - Pseudotsugetum *glaucae (ref. Tables; 67, 68, 69, 70, 83, and Fig. 22) Characteristic Combination of Species Order Characteristic Species Pseudotsuga menziesii Carex concinnoides Arctostaphylos uva-ursi Hieracium umbellatum Spiraea b e t u l i f o l i a Dicranum polyseturn Cladonia chlorophaea Cladonia g r a c i l i s Cladonia mitis Cladonia rangiferina Peltigera aphthosa Alliance Characteristic Species Aster conspicuus Calamagrostis rubescens Hypnum revolutum Polytrichum juniperinum Rhytidiadelphus triquetrus Association Characteristic Species Acer glabrum Betula papyrifera Aralia nudicaulis Arnica co r d i f o l i a Calypso bulbosa 177 Association Characteristic Species (Cont'd) Clematis columbiana Disporum trachycarpum Goodyera oblongifolia Habenaria obtusata Lathyrus nevadensis Oryzopsis asperifolia Pyrola virens Smilacina racemosa Timmia austriaca Mnium spinulosum Important Companion Species Rosa acicularis Shepherdia canadensis Pleurozium schreberi The Rhytidiadelpho - Pleurozio - Pseudotsugetum *glaucae i s formed on the lower parts of steep slopes or i n gul l i e s , some of which appear to be old stream courses. The surface topography i s generally concave. The slopes are moderately steep and have either north or northeast exposures. Measured slope gradients range from 17\u00C2\u00B0 to 29\u00C2\u00B0. The consistent northerly exposures allow a cool moist microclimate to develop. These sites have a long snow duration with snow being observed to be present past the beginning of May. Over 90% of the s o i l surface i s covered by a thick layer of l i t t e r composed largely of dead bryophytes. This l i t t e r layer w i l l effectively decrease moisture loss from the s o i l as a result of evaporation. In a l l sampled plots a small amount of decaying wood was present on the s o i l surface. There i s no evidence of surface erosion and the soils are judged to be moderately well drained. The association i s considered to benefit from temporary seepage because of i t s topographic position. Hygrotopically, this association i s rated as subhygric. The parent material i s g l a c i a l d r i f t i n a l l plots except plots 005 and 015 where the parent material i s alluvium. With the exception of plot 015 the s o i l consists of a thin L-H horizon, a brownish coloured B. horizon (in 178 Table 67 Plot Data Number of Plots Plot No. Plot Size (m2) Date analyzed Elevation (ft) Locality Physiography Landform Relief shape Exposure Slope gradient (\") Layer coverage (%) Aj layer A2 layer A3 layer Bi layer B 2 layer C layer D layer Plot coverage (%) Humus and l i t t e r Mineral s o i l Decaying wood Soil Hygrotope Trophotope Erosion Drainage Horizon depth (in) L-H Bl B 2 C Parent material Rhytidiadelpho (triquetri) Pleurozio (schreberi) -Pseudotsugetum *glaucae Pleurozio - Vaccinio Piceetum glaucae 1 2 3 4 5 6 7 002 003 004 008 005 015 020 400 400 400 400 400 400 400 16/6 18/6 20/6 26/6 22/6 6/7 18/7 1967 1967 1967 1967 1967 1967 1967 2550 2600 2650 2800 2850 2950 2800 WL WL WL WL WL WL WL 5 2 \u00C2\u00B0 1 7 ' 52 0 19' 52 0 14' 5 2 o 2 2 . 5 2 \u00C2\u00B0 2 4 ' 52 0 26' 5 2 \u00C2\u00B0 1 3 ' 1 2 2 \u00C2\u00B0 1 4 ' 1 2 2 \u00C2\u00B0 1 4 ' 1 2 2 \u00C2\u00B0 2 2 ' 12Z0\T 1 2 2 \u00C2\u00B0 2 2 ' 1 2 2 \u00C2\u00B0 2 2 ' 1 2 2 \u00C2\u00B0 1 3 base of gully base of head of gully stream slope slope stream course terrac< NE NE N NE NE N NE 18 24 17 24 28 29 9 23 38 22 21 31 13 2 3 4 24 28 15 18 21 5 1 16 16 5 3 32 10 7 3 8 2 11 12 18 12 2 2 2 26 8 63 60 9 11 9 32 76 60 58 84 83 68 66 82 93 95 94 96 91 94 88 2 1 1 1 1 - -5 4 5 3 8 6 12 hygric permesotrophic n i l well sub-mesotrophic 2-0 0-30 30-45+ 1-0 0-24 1-0 0-17 24-46+ 17-34+ . glacial d r i f t . Regosol 1-0 1-0 2-0 0-7 0-12 0-6 7-26 12-21 12-18 26-34+ 21-39+ 24-36+ alluvium a l l u -over vium glacial d r i f t moderate L-H 2-0 Ae 0-5 B 5-12 C 12-25+ alluvium over glacial d r i f t 68 Rhytidiadelpho ( t r l q u e t r l ) - TlrrrtUO (auatrlacae) -pseudotsugetum *glaucae Pleurozio - v a c c l n l o Piceetum glaucae Number of P l o t * Plot No. Plot Size (m1) Elevation (ft) 002 003 400 400 2550 2600 004 400 26S0 001 400 2800 0 0 5 400 2850 015 400 2950 020 400 2800 A Layer 1 Pseudotsuga menziesii 2 Pinus contorta 3 Picca glauca 4 Betula p a p y r i f c r a B Layer Pseudotsuga menziesii 5 Rosa a c i c u l a r i s 6 Shepherdi\u00C2\u00AB canadensis 7 Spiraea b e t u l l f o l i a 8 Acer glabrum Betula papyrifera 10 Symphoricarpos o c c l d e n t a l i s 0.7 0.2 0.5 0.7 0.7 0.3 2.2 0.6 2.5 0.2 0.2 0.4 11 Linnaea b o r e a l i s 12 Calamagrostis rubcscens 13 Pyrola virens Spiraea b c t u l i f o l i a 14 Arnica c o r d i f o l i a Rosa a c i c u l a r i s 15 Disporum trachycarpum 16 Clematis Columbians 17 Fragaria v i r g i n i a n a Pseudotsuga menziesii 18 Pyrola secunda 19 A r a l i a n u d i c a u l i s 20 Aster conapicuus 21 Oryzopais a s p e r i f o l i a 22 Carex concinnoidea 23 Galium boreale 24 Smilacina racemosa 25 Habenaria obtusata 26 Lathyrus ochroleucus Acer glabrum Anelanchier a l n i f o l i * 27 Lathyrua nevadensia 28 Coodyera o b l o n g i f o l i a Picea glauca 29 Rubus idaeus 30 Calypso bulboaa 31 Epilobium angustifolium Shepherdia canadensis 32 Mahonia aquifolium 33 Cornua canadensis 34 Ribea oxyacanthoidea 35 Arctostaphylos uva-ursi 36 Chimaphila umbellota 37 Astragalus miser 38 A c h i l l e a m i l l e f o l i u m 39 Moneses u n i f l o r a 40 Oamorhiza depauperate 41 Smilacina s t e l l a t e 42 V i c i a Americana 43 V i o l a adunca 44 Carex concinna 45 Epilobium wotaonii 46 Galium t r i florum 47 Liliutr. columbiana Betula pap y r i f e r a \u00C2\u00A3 Layer (Bryophytes) 48 Plcuroiium schrebcri 49 Hylocomium splcndens 50 Rhytidiadclphus tr i g u e t r u s 51 Dicranum polysetum 52 Eurhynchium pulchellum 53 P t i l i u m c r i s t a - c a s t r c n a i a 54 Timnia auatriaca 55 Mnium spinulosum 56 Dicranum fuscescena 57 Polytrichum juniperirum SB Hypnum revolutum 59 Dicranum scoparium 60 Drepanocladus uncinatua (Lichens) 61 P e l t i g e r a aphthosa 62 P e l t i g e r a canina var. rufesi 63 Cladonia mi t i s 64 Cladonia g r a c i l i s 65 Cladonia r a n g i f e r i n a 66 PcItigora canina va 67 P e l t i g e r a malacea 6B Lecidea berengerian 69 P e l t i g e r a lepidopho 2.2 2.1 5.2 4.3 3.2 3.2 2.1 1.1 2.5 2.0 2.0 1.7 1.7 1.0 3.0 2.2 l . B 0.9 0.6 0.8 0.8 0.5 0.5 0.4 0.3 0.3 0.3 1.3 0.B 0,7 0.5 0.5 0.4 0.3 0.3 0.3 0.3 0.3 0.3 0.2 0.2 0.2 0.2 5.9 5.0 4.2 4.0 2.3 2.2 2.6 0.4 0.5 0.5 0.5 0.5 0.5 0.5 TOTAL SPECIES U n c i , sporadical 54 54 49 36 40 44 47_ Sporadic species B Layer 70 Juniperus communis 0 1 5 ( 3 3] 71 Ribes l a c u s t r c 0 1 5 ( 4 2) C Layer 0 Layer 72 Antennaria neglccta 0 0 2 ( 2 2) 82 Cladonia chlorophaea 0 0 8 ( 2 . 1 ) 73 Aquilegia formosa 0081 + + ) 83 Cladonia l u r c a t a 0 0 3 ( 1 . + ) 74 Aster c i l i o l a t u s 0 0 3 1 * + ); 0 2 0 ( 1 . * ) 84 Cladonia poci Hum 0 0 2 ( 1 . * ) 75 Coodyera repens 0 0 2 ( 1 + ) 85 Nephroma hie 1 vet i cum 0 0 4 ( 1 . + ) 76 Hicracium unbellatum 0 0 3 ( 1 \u00E2\u0080\u00A21 86 P e l t i g e r a hori z o n t a l i s 0 0 8 ( 2 . 1 ) 77 M i t e l l a nuda 004<* \u00E2\u0080\u00A2 I 87 P e l t i g e r a polydactyla 0 0 2 ( 1 . * ) 78 Polyatichum muni turn 0 0 4 1 * \u00E2\u0080\u00A21 B8 Pohlia cruda 0 0 5 ( * . \u00C2\u00BB ) 79 T h c l y p t c r i s orcopter 0 0 4 ( 1 11 B9 Pohlia nutans 002 (-\u00C2\u00BB. + ) 80 T r i f o l i u m repens 0031 + + ) 90 Stereocaulon tomentosura 0 0 4 ( * . + ) 81 Vaccinium mcmbranaeeum 004 (1 1)1 0 2 0 ( 2 . 2 ) Epiphytes 91 C e t r a r i a canadcr.if i s (V) 100 Hypogymnia enteromorpha (IV) 109 Basidia sphaeroldea (II) 92 C e t r a r i a h a l e i 101 A l e c t o r l a fremontii (III) 110 C a n d e l l a r i a concolor (11) 93 C e t r a r i a p i n a s t r i (V) 102 A l e c t o r l a glabra (III) 111 Lecanor* cadubriae (II) 94 llypogyfnn ia phyaodea (V| 101 A l e c t o r i a Barmentoaa (III) 112 Uanea glabrescens (III 95 Lethar I J v u lpi na (V) 104 C e t r a r i a glauca (IIII 111 A l e c t o r i a anwjricana (II 96 Parmelis suIcata (V) 105 C e t r a r i a scutata (IIII 114 Brachytheeiurn salebrosum (I) 97 Parme 1 lop* i s ambiqua (V) 106 Cladonia coniocraea (III) 115 B u e l l i a punctata (I) 98 Usnea h i r t a (IV) 107 Parme1iops i a hyperopta (III) 116 Eurhynchium pulchellum (II 99 Uanea s o r e d i i f e r a (IV) 108 P t i l i d i u m pulcherrimum (III) 117 Hypogyauiia v i t t a t a (I) Specie* exclusive to 020 11B Ccocaulon 1ividum 3 1 121 Lyenpodium complunatua 3.1 124 Viburnuai edul* 1.* 119 Habenaria o r b i c u l a t * 1 * 122 Vaccinium cacspltoaun 4.2 125 Populus tranuloldea 120 Lycopodjum annotinum ' i 1 123 Vaccinium n y r t i l l o l d e s 5.2 180 plots 008 and 005 there i s also a horizon), and a light coloured C horizon. The s o i l of plot 015 has a thin L-H horizon overlying an undifferentiated mineral sodium. The surface horizons are medium to coarse textured and range from loamy sands to loams. The sand content increases with depth and sampled C horizons are c l a s s i f i e d as sands, loamy sands or sandy loams. Coarse fragments ranging from gravels to stones are present i n both the B and C horizons of a l l plots except 005 and 015. In these plots coarse fragments are not present in the surface horizon. The coarse fragments collected are mostly cherts, quartzites, and shales belonging to the Cache Creek Group (geological formation Tipper 1959) but there are also a few volcanic tuffs, cinders and lavas present. The reaction of the L-H horizon i s acidic with measured pH values ranging from 5.4 to 6.6. The s o i l reaction becomes neutral to alkaline with depth and pH values of the C horizon range up to 8.2. However, plots 004 and 005 have weakly acidic C horizons with pH values of 6.1 and 6.6 respectively. The range of pH i n the subsurface soi l s i s considered to be related directly to the composition of the parent material as determined from the coarse fragments. Cherts for example w i l l weather out sli g h t l y acidic whereas lavas are more l i k e l y to form alkaline s o i l s . Exchangeable magnesium i s present i n very low amounts but increases sl i g h t l y with depth. These low concentrations suggest that the parent rock had a low magnesium content. Exchangeable calcium i s present i n the L-H horizon i n high concentrations because of the large amount of calcium present in the l i t t e r of Pseudotsuga menziesii (Daubenmire 1953). It i s present i n moderately high amounts in the mineral s o i l and reaches a maximum in the C horizon where measured concentrations range from 4.0 to 10.9 mecr/100 g. The dominance of the exchange capacity by calcium may p a r t i a l l y account for the neutral to alkaline reaction of the mineral s o i l . Available phosphorus i s Rhytidiadelpho (triquetri) Table & Soil Texture - Pleurozio (schreberi) - Pseudotsugetum *glaucae Number of Plots Plot No. 1 002 2 003 3 004 4 008 5 005 Pleurozio - Vaccinio Piceetum glaucae 6 7 015 020 B, Horizon Ae Horizon Textural class SL SL SiL LS SL L SL Clay (%) 13 14 12 10 9 18 10 S i l t (%) 14 26 51 10 39 39 26 Sand (%) 73 60 37 80 52 43 64 Coarse fragments g .c.s. g.c.s. g .c.s g.c.s. None None None. B 2 Horizon B Horizor Textural class No LS SL L L Clay (%) 10 15 13 11 S i l t (%) B 2 6 29 41 42 Sand (%) 84 56 46 47 Coarse fragments s e n t g.c.s. g- None None C Horizon C Horizor Textural class LS SL SL S LS - CL Clay (%) 12 18 15 6 10 Data 29 S i l t (%) 9 24 21 3 8 not 38 Sand (%) 79 58 64 91 82 available 33 Coarse fragments g .c.s. g.c.s. g .c.s. g.c.s. g.c.s. g.c. g. Table 70 S o i l Chemical Analysis Rhytidiadelpho (triquetri) -Pleurozio (schreberi) - Pseudotsugetum *glaucae Vaccinio - Pleurozio Piceetum glaucae Number of Plots 1 2 3 4 5 6 7 Plot No. 002 003 004 008 005 015 020 L-H Horizon L-H Horizon C\u00C2\u00BB 11.9 13.1 28.4 39.1 37.0 41.7 43.7 N% .64 .43 1 .06 1.30 1.26 1.29 1.31 C/N 18.6 30.5 26.8 30.1 29.4 32.3 33.4 P ppm 20.0 16.0 16.0 18.0 26.0 27.0 17.0 Na .18 .18 .19 .77 .20 .37 4.77 K .39 .93 1.18 1.52 1.03 1.23 2.46 Ca 11.4 13.8 23.8 12.5 17.3 21.1 17.8 Mg 1.8 1.7 3.13 3.9 2.5 6.17 2.5 CEC 28.5 22.2 46.9 83.5 67.5 126.1 pH 5.7 6.6 6.0 6.4 5.4 5.6 6.1 Bx Horizon Ae Horizon C* 0 1.1 0 2.3 .8 11.0 4.0 N% .02 .10 .02 .14 .09 .63 .27 C/N 0 11.0 0 16.4 20.0 17.5 14.8 P ppm 9.0 8.0 3.0 7.0 6.0 13.0 4.0 Na .09 .08 .09 .08 .42 .50 1.01 K .09 .25 .51 .38 .46 .65 .24 Ca 5.5 5.5 4.7 5.3 5.5 14.8 3.6 Mg .7 .82 1.15 .82 2.9 6.13 2.5 CEC 16.3 7.8 12.5 16.1 13.9 32.7 18.3 pH 7.S 6.7 6.3 7.0 5.5 6.1 6.3 B2 Horizon B2 Horizon c% 0 0 1.3 0 N% .03 .04 .14 .06 C/N 0 0 9.3 0 P ppm 3.0 6.0 8.0 3.0 Na No No No .09 .37 .53 1.59 K B2 B2 B2 .10 .14 .11 .22 Ca 3.2 3.2 10.9 4.7 Mg .52 1.8 7.5 3.8 CEC 8.4 16.4 16.8 16.5 pH 7.2 5.2 7.0 6.7 C Horizon C Horizon c% 0 0 0 0 0 1.8 0 N% .05 .04 .02 .06 .06 .10 .04 C/N 0 0 0 0 0 18.0 0 P ppm 7.0 4.0 5.0 5.0 4.0 8.0 6.0 Na .08 .09 .44 .08 .47 .43 .49 K .06 .19 .29 .04 .59 .07 .26 Ca 10.9 4.0 6.9 6.9 5.8 10.8 6.8 Mg .8 1.3 4.25 .48 4.8 8.2 3.8 CEC 6.9 4.3 10.0 6.3 8.9 13.6 9.3 PH 8.2 7.0 6.1 8.2 6.6 7.3 7.5 183 present i n high concentrations in the L-H horizon and decreases to moderate amounts in the mineral s o i l . Similarly, the highest concentrations of exchangeable potassium are in the l i t t e r layer and potassium decreases i n concentration with depth. Exchangeable sodium i s present in low amounts i n a l l horizons. The carbon content of the surface mineral horizon i s low and measureable carbon i s present in the C horizon of only plot 015. The low carbon concentration suggests that the addition of organic matter to the s o i l from decomposing l i t t e r and roots occurs slowly. Consequently, total nitrogen i s present in low amounts in the mineral s o i l . Nitrogen i s present i n high amounts in the L-H horizon but the carbon:nitrogen ratios are also high indicating that the organic matter does not contain sufficient nitrogen for decomposition and thus release of nutrients from the l i t t e r w i l l occur slowly. The cation exchange capacity i s high i n the L-H horizon but decreases sharply with depth in the mineral s o i l corresponding to the increasing coarseness of the s o i l . The Rhytidiadelpho - Pleurozio - Pseudotsugetum *glaucae i s considered to be permesotrophic. Based on the presence of the L-H horizon, the brownish B horizon and the weakly acidic to alkaline s o i l reaction these soi l s are cla s s i f i e d into the Orthic Brown Wooded Subgroup with the exception of plot 015 which i s cla s s i f i e d as an Orthic Regosol. Structurally the association has four recognizable vegetation layers. The tree layer i s represented by a well developed A^ layer with a percentage cover ranging from 13% to 38%, a less well developed ^ layer with a coverage ranging from 3% to 28% and a poorly developed A^ layer with a cover ranging from 1% to 16%. Pseudotsuga menziesii i s the dominant species in a l l layers with species significances up to 7. It forms a moderately closed canopy thus creating habitat of heavy shade. Pinus contorta occurs in the A and A layers but with 184 low constancy and significance. Picea glauca i s present in the tree layer of only two plots but i s present i n a l l three sublayers. The only other tree species present i s Betula papyrifera which occurs i n only one plot with a significance of 2. The shrub layer consists of a high shrub (B^) and a low shrub (B2) layer neither of which is well developed. The B^ layer i s composed largely of tree transgressives of which Pseudotsuga menziesii i s the dominant, followed by Picea glauca with a constancy of class IV. Acer glabrum i s the most important shrub species of this layer. In the B^ layer, Rosa acicularis, Shepherdia canadensis, and Spiraea b e t u l i f o l i a are the only constant species. Important non-constants include: Acer glabrum, Amelanchier a l n i f o l i a , and Symphoricarpos occidentalis. The only tree transgressives present are those of Pseudotsuga menziesii and Betula papyrifera, both with low significance. The herb and dwarf shrub layer, (C), because of the heavily shaded habitat ranges from poorly to moderately well developed with percentage cover ranging from 9% to 63%. Linnaea borealis dominates the C layer with an average species significance of 2.5. Other constant species characteristic of cool moist forest habitats include: Disporum trachycarpum, Pyrola virens, Arnica cor d i f o l i a , Clematis Columbiana and Pyrola secunda. Common species present with low significance but important i n the characterization of the association are: Aster conspicuus, Oryzopsis asperifolia, Carex concinnoides, Smilacina racemosa, Habenaria obtusata, Lathyrus ochroleucus, Lathyrus nevadensis, Goodyera oblongifolia, Calypso bulbosa, and Aralia nudicaulis. The bryophyte and lichen layer (D) i s well developed with a percentage cover ranging from 58% to 84%. Bryophytes are more common than lichens in this moist habitat. Pleurozium schreberi and Hylocomium splendens are constant dominants of the D layer with average species significances of 5.9 and 5.0 185 Fig. 22. The Rhytidiadelpho - Pleurozio - Pseudotsugetum *glaucae formed near the base of a north facing slope which has temporary seepage. The association i s dominated by Pseudotsuga menziesii and has a very well developed bryophyte layer (D). Fig. 23. The Pleurozio - Vaccinio - Piceetum glaucae formed on fine textured alluvium of an old stream terrace. It i s dominated by Picea glauca and has a very well developed bryophyte layer (D) in which Pleurozium schreberi is the most abundant species. This association is rare in the Cariboo Zone and i t s development i s controlled by edaphic and topographic factors. 186 respectively. Rhytidiadelphus triquetrus and Timmia austriaca, both constant species, indicate that the surface s o i l reaction i s alkaline to only sli g h t l y acidic as neither can tolerate highly acidic conditions. Other constant species include: Dicranum polysetum, Eurhynchium pulchellum, Ptilium crista-castrensis, and Mnium spinulosum. Peltigera aphthosa and Peltigera canina var. rufescens are the only constant lichen species with average species significances of 2.3 and 1.5 respectively. The epiphytic flora i s well developed with the constant species being: Cetraria canadensis, Cetraria halei, Cetraria pinastri, Hypogymnia physodes, Letharia vulpina, Parmelia sulcata and Parmeliopsis ambigua. The Rhytidiadelpho - Pleurozio - Pseudotsugetum *glaucae appears to have a history involving f i r e as evidenced by the presence of charcoal i n the s o i l and f i r e scars on the older trees. The effects of grazing are negligible i n this association. A l l studied plots of this association were located north of Williams Lake as the association i s rare and very localized on the Fraser Plateau. Here i t occurs at high elevations on very steep valley slopes with northerly exposures. Piceetalia glaucae The Piceetalia glaucae i s only marginally present in the Cariboo Zone and i s known to occur more extensively in the northern regions of Br i t i s h Columbia which have a cooler more moist climate. In the Cariboo Zone i t occurs on subhygric to subhydric habitats which range trophically from permesotrophic to subeutrophic. This order i s characterized by Picea glauca, Salix bebbiana, Agoseris glauca, Aster c i l i o l a t u s , Delphinium brownii, Epilobium angustifolium, Peasites v i t i f o l i u s , Pyrola secunda, Silene menziesii, Smilacina s t e l l a t a , 187 Thalictrum occidentale and Drepanocladus uncinatus. The Piceetalia glaucae includes three alliances\u00E2\u0080\u0094the Poo -Calamagrostido - Populion,tremuloidis, the Carico - Piceion glaucae and the Equiseto - Piceion glaucae. Each alliance i s represented by a single association. The Pleurozio - Vaccinio - Piceetum glaucae, i s also included into this order. However, because i t i s represented here by only one plot,comparison between i t and other associations of the Piceetalia glaucae are not made. Pleurozio (schreberi) - Vaccinio (myrtilloidis) Piceetum glaucae (ref. Tables; 67, 68, 69, 70, and Fig. 23) This association i s represented only by plot 020. It i s considered to be an association more common i n the Boreal Zone. In the Cariboo Zone i t shows a close f l o r i s t i c similarity to the Rhytidiadelpho - Pleurozio -Pseudotsugetum *glaucae. Plot 020 was located on an old stream terrace at the base of a slope in a narrow valley. The valley i s considered to act as a cold a i r drainage pathway. The terrace has a slope gradient of 9\u00C2\u00B0 and a northeast exposure. Because of the topography, a microclimate cooler and moister than those of the surrounding areas has developed here. The habitat has a long snow duration with snow being observed to be present u n t i l near the beginning of June. Soil drainage i s moderate and the association i s believed to benefit from temporary seepage. The hygrotope i s rated as subhygric. The s o i l i s cl a s s i f i e d into the Podzolic Order and has an Ae,B,C, horizon sequence. It i s developed from a parent material of alluvium overlying gravelly g l a c i a l outwash. Texturally, the Ae horizon i s cl a s s i f i e d as a sandy loam, the B horizon as a loam and the C as a clay loam. Coarse fragments of gravel size are present only in the C horizon. The s o i l reaction i s weakly acidic in a l l horizons except the C 188 horizon which has a pH of 7.5. This suggests that the leaching of humic acids from the L-H horizon i s strongly affecting the development of the. s o i l . Exchangeable cations are present i n low amounts and the cation exchange capacity, although high in the L-H horizon decreases sharply with depth. Similarly, total nitrogen and total phosphorus occur i n low concentrations. Trophically, this s o i l i s considered to be submesotrophic to mesotrophic. The association consists of four vegetation layers. The tree layer i s dominated by Picea glauca which reaches i t s best growth in the A^ layer with a significance of 7. The only other tree species present i s Pinus contorta which occurs with low significance. The shrub layer i s dominated by Picea glauca and Shepherdia canadensis. Pseudotsuga menziesii i s present i n this plot as a single transgressive. The C layer i s dominated by Cornus canadensis and Linnaea borealis with species significances of 7.0 and 5.0 respectively. These species also occur i n the Rhytidiadelpho - Pleurozio - Pseudotsugetum *glaucae but with lower significance. Other important species in common between the two associations include: Calamagrostis rubescens, Pyrola virens, Oryzopsis asperifolia. Arnica cordifolia and Pyrola secunda. Vaccinium myrtilloides and Vaccinium caespitosum >with species significances of 5 and 4 respectively, are dominant, characteristic species because of their exclusiveness for this association. The presence of V. caespitosum i s indicative of the long snow duration. The remaining characteristic species are: Geocaulon lividum, Habenaria orbiculata, Lycopodium annotinum, Lycopodium complanatum and Viburnum edule. The D layer i s dominated by Pleurozium schreberi with a significance of 8. Constant associates include: Hylocomium splendens, and Ptilium c r i s t a - castrensis. Rhytidiadelphus triquetrus occurs here with a species significance of only 2 because of the more acidic surface s o i l . The only lichen species 189 present in this association i s Peltigera aphthosa with a significance of 3. The Pleurozio - Vaccinio - Piceetum glaucae i s dominated by Canadian boreal elements and i s present i n the Cariboo Zone only i n localized habitats with cool microclimates and fine textured soils with a high moisture retention capacity. Poo (interioris) - Calamagrostido (rubescentis) - Populion tremuloidis Poo (interioris) - Calamagrostido (rubescentis) - Populetum tremuloidis (ref. Tables; 71, 72, 73, 74, 83, and Fig. 24, 25) Order Characteristic Species Picea glauca Agoseris glauca Aster c i l i o l a t u s Delphinium brownii Epilobium angustifolium Pyrola secunda Silene menziesii Smillacina s t e l l a t a Thalictrum occidentale Drepanocladus uncinatus Alliance and Association Species Populus tremuloides Salix glauca Symphoricarpos occidentalis Astragalus alpinus Bromus anomalus Poa interior Potentilla g r a c i l i s Amblystegium serpens Important Companion Species Calamagrostis rubescens Lathyrus ochroleucus Rosa acicularis Vicia americana Agropyron subsecundum Pleurozium schreberi Brachythecium salebrosum The Poo - Calamagrostido - Populetum tremuloidis i s included in the order Piceetalia glaucae because of i t s similarity to associations dominated 190 Table 71 Plot Data Number of Plots Plot No. Plot Size (m2) Date analyzed Elevation (ft) Locality Physiography Landform Relief shape Exposure Slope gradient (\u00C2\u00B0) Layer coverage (%) Aj layer A 2 layer A 3 layer Bj layer B 2 layer C layer D layer Plot coverage (%) Humus and l i t t e r Mineral s o i l Decaying wood So i l Hygrotope Trophotope Erosion Drainage Horizon depth (in) Poo ( i n t e r i o r i s ) - Calamagrostido (int e r i o r i s ) - calamagrostido - populetosum (rubescentis) - Populetum tremuloidis lonicero (involucratae) - caricetosum leptopodae 1 2 3 4 5 6 7 8 9 10 091 105 089 106 107 019 074 110 108 109 400 400 400 400 400 400 400 400 400 400 8/8 16/8 7/8 16/8 18/8 11/7 5/7 20/8 19/8 21/8 1968 1968 1968 1968 1966 1967 1968 1968 1968 1968 3300 3500 3600 3700 3700 2200 3000 3650 3700 3750 FP FP FP FP FP WL FP FP FP FP 51\u00C2\u00B043' 51\u00C2\u00B046' 51043' S l M l ' 51\u00C2\u00B041' 52-16' 51048' 51\u00C2\u00B041' 51\u00C2\u00B042' 51-43' 122\u00C2\u00B046' 123\u00C2\u00B002' 123\u00C2\u00B001' 123\u00C2\u00B003' 122\u00C2\u00B015' 122\u00C2\u00B039' 123\u00C2\u00B003' 1 123\u00C2\u00B003' 123\u00C2\u00B003' edge of gully edge of lake bench bottom gully concave f l a t f l a t concave concave straight .neutral. SW SE NE 0 0 0 11 4 8 0 0 0 0 _ _ 10 _ _ 62 . 21 26 23 53 SI 42 60 52 5 21 40 40 42 8 14 12 11 12 - 47 8 4 6 - 5 4 1 1 4 9 5 3 1 20 8 28 3 5 32 73 81 75 76 84 72 94 71 88 91 61 64 66 68 12 6 6 7 6 6 3 4 5 8 100 98 98 99 98 96 98 99 98 99 - 2 2 - - - - - - -- - - 1 2 4 2 1 2 1 subhygric - hygric \u00E2\u0080\u00A2mesotrophic to permesotrophic. n i l moderate to well .hygric - subhydric. ...permesotrophic... n i l imperfect L-H 2-0 2-0 2-0 2-0 2-0 L-H 3-0 2-0 2-0 2-0 2-0 A - 0-5 - 0-6 0-4 Bl 0-15 0-4 0-5 0-6 0-5 B 0-6 5-13 0-7 6-12 4-13 B 2 - 4-16 5-15 - 5-13 C 6-24+ 13-28+ 7-26+ 12-23+ 13-24+ C 15-26+ 16-30+ 15-30+ 6-24+ 13-24+ Parent material g l a c i a l . . . g l a c i a l d r i f t . . . d r i f t ? . . g l a c i a l d r i f t . g l a c i a l d r i f t alluvium T a b i . 7 2 Poo ( i n t e r i o r i s ) - Calamagroatido (rubescentis) - Populetum tremuloidis :al*magroetlda - populetoaun treaajloldla (i nvolucrati ricetoaum leptopodae Number of Plots Plot Six* (n> 1 Elevation (ft) 1 Populua tremuloides 091 105 089 106 107 400 400 400 400 400 3300 3500 3600 3700 3700 019 074 110 108 109 400 400 400 400 400 2200 3000 3650 3700 3750 Avg Speclea Significance Asaociatlon Avg Species Significance 2 Pinus contorta 3 R\"\u00C2\u00BB* a c i c u l a r i a 4 Symphoricarpos o c c i d e n t a l i s Populus tremuloides 5 S a l i x glauca 6 A w l M c h l a r a l n l f o l l a 7 Lonicer* lnvolucrata 8 ftubua ldaeus 9 Shapherdl* canadensis 10 S a l i x bebblon* 11 Rlbes locustre Pinus contorta 12 Picea glauca C Layer 13 Calamagrostis rubescens 14 Lathyrua ochroleucus 15 Poa i n t e r i o r 16 Thalictrum occidentale 17 Aster c i l i o l a t u s 16 Bromus anomalus Rosa a c i c u l a r i s 19 V i c i a americana 20 A c h i l l e a m i llefolium 21 Fragaria v i r g i n i a n a 22 Galium boreal* 23 Smlleclna s t e l l a t a 24 Agropyron subsecundum 25 Taraxacum o f f i c i n a l e 26 Arctostaphylofl uva-ursi 27 Astragalus alpinus 28 Axenaria l a t e r i f l o r a 29 Erigeron specioaus 30 P o t e n t i l l a g r a c i l i s 31 V i o l a canadensis 32 Epilobium angustifolium 32 Gaum t r i f l o r u m 34 V i o l a adunca 35 Agoserls glauca 36 Carex coneinna 37 Petasites v l t i f o l i u a 38 Carex leptopoda 39 Allium cernuum 40 Heracleum 1anaturn 41 Clnna l a t i f o l i a Symphoricarpos o c c i d e n t a l i s 42 Astragalus miser Rubus ldaeus 43 Actaea rubra 44 Anemone mu l t i f i d a 45 Aster campestris 46 Qsmorhixa chi l e n a i s 47 Antennaria rosea 48 Delphinium brownii Picea glauca 49 Poa j u n c i f o l i a 50 Calamagrostis neglecta 51 Pyrola aecunda S3 P o t e n t i l l a pennsylvanlca Rlbea lacuatra 53 Stipa. columbiana 54 Cqulsetum arvenae 55 Phleum pretense 56 Sllene mensieaii 57 Stipa r i c h a r d s o n i i 56 T r l f o l i u j u repens 59 Cirsium follosum 60 Slymus glaucus 61 Agropyron spicatum 62 Geranium viscosissimum 63 Bromus inermls 64 C a s t l l l e j a ailniata 65 Hleracium umbellatum 66 Lithospermum ruderala 67 Poa pratenaia 68 V i o l a o r b i c u l a t a 69 Calamagrostis canadensis 70 Senecio lndecorus 71 Senecio pauperculus 9. I**yer (Bryophytes) 72 Amblyategium serpens 73 Pleurozium schreberi 74 Brachytheclum salebrosum 75 Ceratodon purpureu* 76 Drepanocladua uncinatus 77 Eurhynchlum pulchellum 78 Tortula r u r a l i s 79 Aulacomnium palustre B0 P t l l i u m c r i s t a - c a a t r e n s i s (Lichens) Bl P e l t i g e r a canina var. rufeac B2 P e l t i g e r a malacea B3 Pel t i g e r a aphthosa 84 P e l t i g e r a canina var. canina 4.2 2.2 4.+ 3.* 7.3 3.2 4.2 3.2 7.5 2.1 3.2 3.+ 4.2 2.1 1.1 2.1 3.1 3.2 2.1 2.1 2.1 3.2 3.1 1.* 2.* 1.* 3.2 6.4 6.4 3.2 3.2 3.2 2.1 2.1 2.2 2.2 2.2 2.1 3.2 3.2 3.2 2.2 3.1 3.2 2.1 2.1 2.1 2.1 3.2 2.2 3.2 3.2 2.2 2.1 1.8 1.5 3.2 2.2 2.0 2.6 2.2 2.2 i.e 2.0 l.B 4.6 2.4 0.8 0.8 0.2 0.4 0.6 0.2 0.2 O.S 0.4 0.4 0.6 3.2 2.6 2.2 0.4 0.2 2.0 1.4 0.8 1.0 0.4 0.6 5.3 7.3 7.6 8.6 7.6 3. * 2.* 2.* 4. * - 3.* 3.* 1.* 2.* 2.* - 2.1 -1.* 2.1 2.+ 2.2 1.1 3.2 1.4 3.3 3.2 - 3.2 2.2 3.3 2.1 3.1 2.1 2.1 2.* 3.2 2.2 2.2 4.2 7.4 2.1 4.3 2.1 3.1 5.3 4.3 5.2 4.2 5.2 3.1 3.1 1. + 2. * 5.2 2.1 2.+ 1.+ 2.1 1.1 2.2 1.-2.1 1.1 1.1 4.1 3.1 3.2 3.3 3.8 3.B 2.0 2.2 2.2 1.8 1.6 0.7 1.6 1.6 0.8 0.4 2.4 1.8 0.4 0.6 0.4 0.6 1.8 0.4 0.6 0.4 0.5 0.8 0.6 0.6 0.3 0.9 0.7 0.7 0.6 0.6 0.6 0.5 O.S 0.2 0.2 0.4 0.4 0.3 0.3 0.2 0.2 0.2 1.7 0.9 0.9 1.0 0.7 0.4 O.S 0.4 0.3 TOTAL SPECIES U n c i , sporadic*) Sporadic species 8 Layer SS Cornus s t o l o n i f e r a 86 Juniperus acopulorum 87 Rib*a oxyacanthoidee 69 Salix laaiandra C Layer 89 Agropyron trachycaulum 90 Antennaria anaphaloidai 91 Carex p r a e g r a c i l i a 92 Caraitium arvenae 93 Clematis columbiana 94 Cornus canadensis 95 Diaporum ttachycarpum 96 Peatuca saximontana 97 Linnaea borealia 074(2.1) 074(1 .\u00E2\u0080\u00A2) 074(2.1) 074(1.1) 074(3.1) 106(2.1) 074(1.1) 107(1.1) 019(4.*) 019(2.2) 019(*.+) 106(1.1) 019(2.2) 98 Hahonia aquifolium 99 Oryzopai* a s p a r i f o l l a 100 Poa g r a c i l l i m a 101 Solidago multlradiata 102 Zygadenua gramlneus 103 Barbula convoluta 104 Dicranum polysetum 105 Hylocomium splendens 106 Leptobryum pyriforme 107 peltigera polydactyla 106 Pohlia nutans 109 P y l a i a i a polyantha 110 Tismia auatriaca 019(3.1) 019(3.2) 106(1.1) 107(2.1) 074(*.+> 106(1.*) 019(2.1) 091(3.2) 107(1 .\u00E2\u0080\u00A2) 108(1.+) 109(1.+) 074(1.*) 109(2.1) Epiphytes Brachythecium aalebrosum Amblyatagium serpens 111 Xanthoria f a l l a x 112 Buell l a punctata 113 Rypogymnia phyaodee 114 Parmelia exaaperatula U S Peltigera praetaxtata 116 Physcia adscandena 192 by Picea glauca with regard to habitat and species of the C layer. It i s considered possible that this association may advance successionally to an association dominated by Picea glauca. The Poo - Calamagrostido - Populetum tremuloidis i s an association of restricted distribution in the Cariboo Zone and reaches i t s best development at elevations of greater than 3000 feet. It develops on subhygric to hygric habitats formed i n g u l l i e s , on level benches or at the edge of lakes, and on hygric to subhydric habitats formed in valleys on recently exposed stream terraces. It i s most common on level sites but also occurs on gentle slopes with either southerly or northerly exposures. There i s no evidence of surface erosion and s o i l drainage i s considered to vary from imperfect to moderate. The s o i l surface i s covered by a very extensive layer of l i t t e r composed mostly of Populus leaves. The s o i l s are developed from a parent material of either g l a c i a l d r i f t or alluvium. Four vegetation strata are present i n this association. The tree layer i s represented by three sublayers of which the A2 i s best developed. Populus tremuloides i s the dominant tree species with species significance ranging from 7 to 8. The shrub layer has two sublayers and ranges from poorly developed to very well developed. The most important shrubs are Rosa acicularis and Symphoricarpos occidentalis. The herb layer (C) is well developed with percentage cover ranging from 61% to 94%. Calamagrostis rubescens i s the dominant C layer species with an average species significance of 5.3. Lathyrus ochroleucus and Poa interior are constant subdominants with average species significances of 3.5 and 3.3 respectively. Other constant species characteristic of these moist habitats include: Thalictrum occidentale, Aster c i l i o l a t u s , Bromus anomalus, Smilacina s t e l l a t a and Agropyron subsecundum. Astragalus alpinus and Potentilla g r a c i l i s , Poo (interioris) Table 73 Soil Texture - Calamagrostido (rubescentis) - Populetum tremuloidis Number of Plots Plot No. poo - calamagrostido -populetosum tremuloidis 1 091 2 105 3 089 4 5 106 107 lonicero (involucratae) -caricetosum leptopodae 6, 7 8 9 10 019 074 110 108 109 A Horizon Bj Horizon Textural class . L L SL SiL SiCl LS SL S Clay (%) Mo 18 No 16 9 13 33 4 8 3 S i l t (%) 7\ 34 7\ 41 36 52 50 18 17 2 Sand (%) A 48 A 43 55 35 17 78 75 96 Coarse fragments \u00E2\u0080\u00A2 \u00E2\u0080\u00A2 g\u00C2\u00BB g. g- g.c.s. None None None None Horizon B2 Horizon Textural class LS L SL CL SiL \u00E2\u0080\u00A2 SiC LS \u00E2\u0080\u00A2 LS Clay (%) 3 23 6 31 19 No 47 2 No 5 S i l t (%) 22 25 26 34 51 T\") 45 16 14 Sand (%) 75 52 68 35 30 B 2 8 82 B 2 81 Coarse fragments g.c. g- C.S. None g.c. g.c. \u00E2\u0080\u00A2 None None \u00E2\u0080\u00A2 None Horizon C Horizon Textural class LS L SL L SL SCL SiL S S S Clay (%) 4 21 3 14 13 30 48 0 2 ' 1 S i l t (%) 15 31 38 39 31 2 44 0 2 3 Sand (%) 81 48 59 47 56 68 8 100 96 96 Coarse fragments g.c.s. g. C.S. g.c. g.c. g.c.s. g.c.s. g- g.c. g.c.s. g.c.s CO 194 Table 74 S o i l Chemical Analysis Poo ( i n t e r i o r i s ) - Calamagrostido (rubescentis) - Populetum tremuloidis poo ( i n t e r i o r i s ) - calamagrostido populetosum tremuloidis lonicero (involucratae) caricetosum leptopodae Number of Plots 1 3 4 5 6 7 8 9 10 Plot No. 091 105 089 106 107 019 074 110 108 109 L-H Horizon L-H Horizon C% 30.6 34 9 44 .0 41 .3 48 4 36.8 41 9 41 6 35. 8 32.9 N% 1.10 1 39 1 .21 1 .49 1 83 .87 1 74 1 03 1. 36 1.26 C/N 27.8 25 1 36 .4 27 .7 26 4 42.3 24 1 40 4 26. 3 26.1 P ppm 9.0 11 0 15 .0 12 .0 10 0 22.0 18 0 15 0 16. 0 8.0 Na .34 38 .40 .32 38 1.23 27 36 32 .28 K 1.76 2 98 3 .26 2 .5 2 88 3.18 1 64 3 52 2.64 3.46 Ca 51.6 34 8 33 .4 36.0 43 2 35.5 25 2 36 8 44. 8 41.6 Mg 15.6 24 8 16 .8 20 .8 23 8 17.0 29 4 13 4 13. 4 13.0 CEC 38.7 61 8 73 .5 81 .5 53 8 84.9 152 0 66 4 39. 8 42.3 PH 6.4 6 3 6 .5 6 .6 6 8 5.9 6 8 6 6 6. 7 6.5 A Horizon Bi Horizon C% 7 0 8 .1 7 0 0 3 1 5 7 0 3.9 N% 48 .28 41 .04 16 20 10 .20 C/N 14 6 28 .9 17 1 0 19 4 28 5 0 19.5 P ppm 16 0 8 .0 13 0 3.0 13 0 6 0 4. 0 6.0 Na No 22 No .12 11 .96 57 14 23 .12 K A 1 18 A 1 .38 1 41 .62 86 1 71 41 .41 Ca 5 9 5 .9 4 9 3.0 7 0 14 4 8. 1 6.7 Mg 8 3 6 .7 4 1 2.0 14 3 9 8 6. 7 3.5 CEC 24 5 31 .8 46 4 19.3 27 5 16 5 3. 9 8.9 pH 6 8 6 .3 6 9 6.3 7 6 6 4 6.6 6.3 B Horizon B 2 Horizon C* 8.3 2 2 .9 3 .4 2 5 0 1 6 0 N% .39 09 .07 .16 19 07 13 .05 C/N 21.3 24 4 12 .9 21 .3 13 2 0 12 3 0 P ppm 10.0 3 0 3 .0 3 .0 7 0 8 0 10 0 0 Na .43 61 .28 .55 54 No 53 21 No .33 K .52 1 52 .96 .86 95 B, 62 12 I .25 Ca 13.0 11 2 10 .9 9 .9 9 3 9 5 9 5 4.6 Mg 3.4 10 8 6 .4 17 .6 6 6 14 6 4 3 3.1 CEC 53.1 16 1 11 .4 7 .4 12 0 19 3 32 4 0 pH 6.5 7 8 6 .3 8 .2 7 5 8 2 6 6 7.0 C Horizon C Horizon c% 1.6 0 0 0 0 0 0 0 0 0 N% .12 06 .12 .13 07 .05 10 07 16 .06 C/N 13.3 0 0 0 0 0 0 0 0 0 P ppm 6.0 3 0 4 .0 6 .0 3 0 5.0 7 0 0 0 0 Na .57 1 14 .34 .68 59 .81 57 16 14 .17 K .74 1 01 1 .14 .61 1 72 .34 38 28 21 .65 Ca 11.7 11 2 13 .0 9 .5 12 1 4.S 10 9 4 2 5. 5 4.2 Mg 5.9 16 8 9 .0 12 .4 16 5 6.0 11 4 2 3 19. 3 1.9 CEC 16.8 11 8 7 .6 17 .4 4 1 12.1 16 1 0 0 0 pH 7.6 8 4 7 .8 8 .5 8 1 7.7 8 2 7 7 7. 8 7.6 195 both non-constants, are considered as characteristic species of this association. The D layer i s very poorly developed because of the heavy l i t t e r layer and has a percentage cover ranging from 3% to 12%. The most important bryophytes are: Amblystegium serpens, Pleurozium schreberi, Brachythecium salebrosum, and Ceratodon purpureus. The only lichens present are Peltigera spp. and with low significances. The lack of lichens i s indicative of the hygric surface conditions. The epiphytic flora i s also poorly developed with Brachythecium salebrosum and Amblystegium serpens occurring as the dominant species. The association appears to have a history of slight burning and may actually be promoted by f i r e as Populus tremuloides advances quickly by root suckers into li g h t l y burned areas (Rowe 1953, Moss 1955). The Poo -Calamagrostido - Populetum tremuloidis i s grazed only slightly as Calamagrostis rubescens appears to have low p a l a t i b i l i t y for cattle. Two subassociations of the association are described, namely, the poo - calamagrostido - populetosum tremuloidis and the lonicero - caricetosum leptopodae. These have different hygrotopes and correspondingly different species compositions. Poo - Calamagrostido - Populetum tremuloidis 1. poo - calamagrostido - populetosum tremuloidis (ref. Fig. 24) Differential Species Shepherdia canadensis Arctostaphylos uva-ursi Astragalus miser Carex concinna Anemone multifida Aster campestris Antennaria rosea Geum triflorum Potentilla pennsylvanica 196 Differential Species (Cont'd) Stipa richardsonii This subassociation i s formed on lake edges, benches or gully bottoms with r e l i e f shapes ranging from f l a t to concave. The soi l s are considered to be moderately drained to well drained and only occasionally i s there evidence of gleying in the lower parts of the C horizon. This is the drier of the two subassociations and i s rated as subhygric to hygric. The soils are developed on a parent material of g l a c i a l d r i f t and are classed as either Orthic Dark Grey Chernozems (plots 105, 106 & 107) with a L-H,A,B,C, horizon sequence or Orthic Brown Wooded Soils (plots 091, & 089) with a L-H,B,C, horizon sequence. The Dark Grey Chernozemic s o i l s are closely related to Dark Grey Wooded Soils but have insufficient degradation of the surface horizon to be placed in the Podzolic Order. In the N.S.S.C. (1968) report they would most l i k e l y be placed as Luvisols. The soils are medium to coarse textured and there i s no significant textural change with depth. Coarse fragments were present in a l l horizons of the sampled soils with the exception of plot 089 which had coarse fragments only in the C horizon. Thus the parent material of plot 089 i s considered to be alluvium overlying g l a c i a l d r i f t . The L-H horizon has a weakly acidic reaction with pH values ranging from 6.3 to 6.8. The s o i l reaction of the mineral s o i l i s weakly acidic to circumneutral at the surface with pH values of 6.3 to 6.9 and becomes alkaline with depth. The pH values of the C horizon vary from 7.6 to 8.4. Exchangeable calcium and magnesium reach their highest concentrations in the L-H horizon where calcium values range from 33.4 meq/100 g to 51.6 meq/100 g, and magnesium values from 15.6 meq/100 g to 24.8 meq/100 g. This i s because the l i t t e r of Populus contains very high amounts of these cations (Daubenmire 1953). Both cations are present in lower amounts in the mineral s o i l and tend 197 to increase in concentration down the p r o f i l e . The higher concentrations of calcium and magnesium with increasing depth may in part account for the increased alkalinity with depth. In three of the sampled C horizons magnesium was present in higher amounts than was calcium which suggests that the s o i l developed from a magnesium rich parent rock. Exchangeable sodium i s present in low amounts in a l l horizons. Exchangeable potassium occurs in high amounts in the L-H horizon and decreases in concentration down the profile as does total phosphorus and percentage carbon. Carbon was not measureable in the C horizon with the exception of plot 091 where a trace amount was present. Nitrogen i s present in high amounts in the L-H horizon but the carbon:nitrogen ratios are also moderately high suggesting that decomposition may be retarded. Nitrogen concentrations are lower in the mineral s o i l and decrease with depth. However, the carbon:nitrogen ratios are also lower indicating that nitrogen i s available to higher plants. The cation exchange capacity i s high in the L-H horizon and decreases down the profile corresponding to the decrease in organic matter content. However, because of the generally loamy texture of the s o i l i t remains high even in the C horizon. These soils are considered to be mesotrophic to permesotrophic. Populus tremuloides i s the only tree species present in this sub-association and reaches i t s maximum importance in the A^ layer where i t has an average species significance of 7.2. Only in plot 089 are Populus trees t a l l enough to form an A( layer which i s poorly developed with a percentage cover of ten percent. The B, layer i s very poorly developed with a percentage cover varying from 0 up to 5%. It i s composed entirely of transgressives of Populus tremuloides and Pinus contorta. 198 The Bjlayer i s moderately well developed and i s dominated by Rosa acicularis with an average species significance of 3.4. Salix glauca, a boreal subarctic species, i s present with an average species significance of 1.8 and i s most abundant in this subassociation as is Shepherdia canadensis which occurs with an average species significance of 1.6. The C layer of the Poo - Calamagrostido - Populetum tremuloidis i s best developed in this drier subassociation with percentage cover ranging from 71% to 94%. Calamagrostis rubescens dominates the C layer with an average species significance of 7.2. Arctostaphylos uva-ursi, a species characteristic of dry forest habitats, i s a constant subdominant with an average species significance of 4.8. Other species considered as d i f f e r e n t i a l for this subassociation include; Agoseris glauca, Astragalus miser, Carex concinna, Geum triflorum, Anemone multifida, Aster campestris, Antennaria rosea, Potentilla pennsylvanica and Stipa richardsonii. A l l of these species are i n -dicative of drier sites. Cirsium foliosum, Agropyron spicatum, C a s t i l l e j a miniata, and Lithospermum ruderale are present in the Poo - Calamagrostido -Populetum tremuloidis only in this subassociation but with low species significances. ^ The D layer i s poorly developed with a percentage cover ranging from 6% to 12%. Pleurozium schreberi i s the dominant bryophyte with an average species significance of 3.2. Other important bryophytes include: Brachythecium salebrosum, Ceratodon purpureus, Tortula r u r a l i s , and Amblystegium serpens. The lichen flora of the Poo - Calamagrostido - Populetum tremuloidis i s best developed in this subassociation. The dominant species are Peltigera canina var. rufescens with an average species significance of 1.8 and Peltigera malacea with an average species significance of 1.0. Of the two subassociations of the Poo - Calamagrostido - Populetum tremuloidis this one has the heaviest grazing history because of i t s upland position in close proximity to the open rangeland. 199 Fig. 24. The Poo - Calamagrostido - Populetum tremuloidis poo -calamagrostido - populetosum tremuloidis showing the characteristic dominance of Populus tremuloides and open understory. The herb layer (C) i s well developed in this association and i s dominated by Calamagrostis rubescens. Fig. 25. The Poo - Calamagrostido - Populetum tremuloidis lonicero caricetosum leptopodae showing the excellent development of Populus tremuloides and the characteristic densely developed shrub layer (B) which i s dominated largely by Rosa acicularis. 200 Poo - Calamagrostido - Populetum tremuloidis Z. lonicero (involucratae) - caricetosum leptopodae (ref. F i g . 25) Differential Species Amelanchier a l n i f o l i a Lonicera involucrata Rubus idaeus Salix bebbiana Ribes lacustre Petasites v i t i f o l i u s Carex ieptopoda Heracleum lanatum Cinna l a t i f o l i a Viola canadensis Arenaria laterflora Actaea rubra Osmorhiza chilensis Equisetum arvense This subassociation i s formed on stream terraces or in seepage gul l i e s . The surface r e l i e f shape was f l a t and the \"exposure was neutral for a l l plots sampled except 019 which was located on an 8\u00C2\u00B0 slope with a northeast exposure. The so i l s are imperfectly drained and moderate to strong gleization i s evident in the C horizon. Because of i t s proximity to streams this sub-association i s considered to be flooded occasionally and thus the hygrotope i s rated as hygric to subhydric. The soi l s are formed on a parent material of alluvium with the exception of plot 019 where they appear to be formed on gl a c i a l d r i f t . They are classed as Orthic Brown Wooded soil s and have an L-H, B,C horizon sequence. The s o i l s are medium to coarse textured ranging from s i l t y clays to sands. Coarse fragments are present only in the C horizon with the exception of plot 019 where gravel sized particles were found right to the surface. The reaction of the L-H horizon i s weakly acidic with pH values ranging from 5.9 to 6.8. The reaction of the mineral s o i l i s weakly acidic to circumneutral at the surface and becomes alkaline with depth. Measured 201 pH values at the surface range from 6.3 to 7.6 whereas in the C horizon pH values range from 7.6 to 8.2. Exchangeable calcium i s present in high concentrations in the L-H horizon because of the large amounts of calcium in Populus l i t t e r (Daubenmire 1953). It occurs in lower concentrations in the mineral s o i l and tends to decrease with depth as does the organic matter content. Exchangeable magnesium is also present in high concentrations in the L-H horizon and decreases i n concentration in the mineral s o i l . Magnesium is present in greater concen-tration than calcium i n three plots suggesting that the parent material i s inherently rich in magnesium. Exchangeable sodium i s present i n low amounts in a l l horizons and thus i s not l i k e l y to interfere with the exchange complex. Potassium occurs with high concentrations in the L-H horizon and decreases down the p r o f i l e . Similarly, total phosphorus and percentage carbon decrease in concentration with depth; carbon i s not detectable in the C horizon. Nitrogen i s present in high amounts in the L-H horizon but the carbon:nitrogen ratios are also high suggesting that decomposition occurs slowly and that nitrogen may be limiting. Nitrogen i s present in lower concentrations in the mineral s o i l and decreases slightly with depth. However, the carbon:nitrogen ratios are more favourable indicating that nitrogen i s available to higher plants. The cation exchange capacity i s very high in the L-H horizon because of the high organic matter content. It i s substantially lower in the mineral s o i l and decreases down the profile as s o i l texture becomes coarser. The soils are considered to be inherently rich in nutrients and to also benefit from secondary enrichment of nutrients brought in during times of flooding. The habitat of this subassociation i s rated as being permesotrophic. The tree layer i s better developed i n this subassociation than in the poo - calamagrostido - populetosum tremuloidis and i s represented by three 202 sublayers. Populus tremuloides i s the dominant species with species significances ranging up to 8. The high shrub layer (B-^ ) i s poorly developed and i s composed largely of transgressives of Populus. The only other species represented i s Salix bebbiana which i s considered as d i f f e r e n t i a l for this subassociation. The B 2 layer i s very well developed in this moist habitat and has a percentage cover ranging up to 81%. The dominant shrub species are Rosa acicularis and Symphoricarpos occidentalis with an average species significance of 6.8 and 5.2 respectively. Other species indicative of moist habitats and considered d i f f e r e n t i a l for the lonicero - caricetosum leptopodae include: Amelanchier a l n i f o l i a , Lonicera involucrata, Rubus idaeus and Ribes lacustre. The C layer i s not as well developed as i t s counterpart in the poo -calamagrostido - populetosum tremuloidis. Lathyrus ochroleucus i s the constant dominant species with an average species significance of 4.6. Thalictrum occidentale and Aster c i l i o l a t u s are constant subdominants, both with average species significance of 3.8. Calamagrostis rubescens i s not as abundant in this wetter subassociation and occurs with an average species significance of only 3.4. Species indicative of moist habitats and considered d i f f e r e n t i a l for the subassociation include: Carex leptopoda, Osmorhiza chilensis, Petasites v i t i f o l i u s , Cinna l a t i f o l i a , Heracleum lanatum, Viola canadensis, Arenaria l a t e r i f l o r a , Actaea rubra and Equisetum arvense. Geranium viscosissimum, Bromus inermis, Viola orbiculata, Calamagrostis canadensis and Senecio indecorus occur in the Poo - Calamagrostido - Populetum tremuloidis only i n this sub-association. In the D layer of the lonicero -'caricetosum leptopodae, which is poorly developed, bryophytes are more important than lichens because of the hygric habitat. Amblystegium serpens i s the dominant species with an average species significance of 3.2 and Pleurozium schreberi i s a constant associate 203 but with a very low average significance of 1.4. Brachythecium salebrosum, Ceratodon purpureus, Eurhynchium pulchellum and Drepanocladus uncinatus are the only other bryophytes present. The lonicero - caricetosum leptopodae has a history of only very slight grazing, the effects of which do not appear to have altered the structure of the subassociation. Carico (concinnae) - Piceion glaucae Carico (concinnae) - Piceetum glaucae (ref. Tables; 75, 76, 77, 78, 83, and Fig. 26) Characteristic Combination of Species Order Characteristic Species Picea glauca Salix bebbiana Agoseris glauca Aster c i l i o l a t u s Epilobium angustifolium Petasites v i t i f o l i u s Pyrola secunda Silene menziesii Smilacina s t e l l a t a Thalictrum occidentale Drepanocladus uncinatus Alliance and Association Characteristic Species Antennaria anaphaloides Carex concinna Equisetum scirpoides Geocaulon lividum Schizachne purpurascens Senecio pauperculus Aulacomnium palustre Important Companion Species Rosa acicularis Shepherdia canadensis Betula glandulosa Salix monticola Salix brachycarpa Calamagrostis rubescens Arctostaphylos uva-ursi 204 Important Companion Species (Cont'd) Pleurozium schreberi Hylocomium splendens Ptilium crista-castrensis This association develops i n old g l a c i a l stream depressions or occasionally on old stream terraces and often borders the lakes in which the Carico - Salicetum monticolae i s found. The surface topography i s hummocky and the exposure i s considered to be t o t a l . The stream depressions i n which the association occurs appear to act as cold air drainage pathways from the surrounding uplands and thus a cool microclimate i s present. The s o i l surface i s covered by a small amount of decaying wood and by the extensive layer of l i t t e r composed largely of Picea needles. There is no evidence of surface erosion in this association and based on topographic position the s o i l drainage i s considered to vary from moderate to impeded. ^ The soi l s are formed on parent materials of alluvium and are classed either in the Chernozemic or Gleysolic Orders. Plots 068 and 111 have L-H, Ah, B, Cg horizon sequences and are classed as Gleyed Dark Grey Chernozems. These are closely related to Dark Grey Wooded soil s but have insufficient degradation of the surface horizon to be placed in the Podzolic Order. In the 1968, N.S.S.C. report they would probably be placed as Luvisols. Plot 099 has a L-H,Bg, Cg horizon sequence and i s classed as an Orthic Gleysol whereas plots 102 and 103 have L-H, Ah, Cg horizon sequences and are placed as Rego Humic Gleysols. A l l soi l s are strongly gleyed in the subsurface horizons and in plots 099 and 103 free water was present in the lower parts of the C horizon. Thus the s o i l s are considered to be poorly aerated and subjected to reducing conditions for at least part of the growing season. In the spring standing water may be present, temporarily, in the topographically lowest parts of the hummocky surface. There i s , however, no evidence that the association i s ever completely submerged. The hygrotope of the Carico - Piceetum glaucae i s therefore rated as being Table 75 Carico (concinnae) - Piceetum glaucae Plot Data Number of Plots 1 2 3 4 5 Plot No. 099 102 103 068 111 Plot Size (m2) 400 400 400 400 400 Date analyzed 9/8 13/8 14/8 26/6 22/8 1968 1968 1968 1968 1968 Elevation (ft) 3000 3150 3150 3250 3600 Locality FP \u00E2\u0080\u00A2 FP FP FP FP 51\u00C2\u00B045 51043. 51\u00C2\u00B043' 51\u00C2\u00B043' 51\u00C2\u00B042' 122\u00C2\u00B049 ' 122\u00C2\u00B039' 122\u00C2\u00B039' 122\u00C2\u00B040' 122\u00C2\u00B059' Physiography Landform stream terrace Relief shape hummocky Exposure ..neutral. Slope gradient (\u00C2\u00B0) 0 0 0 0 0 Layer coverage (%) layer 8 22 21 - 42 A 2 layer 38 46 52 13 21 A3 layer 11 . 8 10 45 10 Bi layer 5 4 4 6 5 B 2 layer 26 21 10 14 8 C layer 16 46 42 48 45 D layer 41 58 56 57 38 Plot coverage (%) Humus and l i t t e r 97 96 99 92 98 Mineral s o i l - - - 2 -Decaying wood 3 4 1 6 2 Soil Hygrotope . (hydric) - hygric - (subhygric) Trophotope Erosion . .. n i l .. Drainage moderate moderate Horizon depth (in) L-H 7-0 3-0 2-0 1-0 2-0 A No A 0-13 0-12 0-9 0-4 B 0-14 No B No B 9-24 4-12 C 14-24+ 13-26+ 12-30+ 24-36+ 12-24+ Parent material alluvium T a L l e C a r i c o ( c o n c i n n a e ) - P i e c e t u n g l . i u c a c Number o l P l o t s P l o t No. P l o t Size (m2) E l e v a t i o n ( f t ) 099 10? I l l 068 111 400 400 400 400 400 3000 3150 1)50 3250 3600 3 P o p u l u s t r e n u l o i d c s 4 Rosa a c i c u l a r i s 5 B e t u l a g l a n d u l o s a 6 S h e p h o r d i a c a n a d e n s i s 7 S a l i x n o n t i c o l a 8 S y n p h o r i c a r p o s O c c i d e n t a 1 i 9 S a l i x b r a c h y c a r p a 10 S a l i x b e b b i a n a 11 S a l i x l a s i a n d r e 3.* 3.* 3.- 3. 3.2 2.1 3.1 3.1 3.1 5.2 1.* 3.1 2.* 2.1 3.* 2.1 3.. 12 Carex . 13 A n t e n n a r i a a n a p h a l o i d c s 14 A s t e r c i l i o l a t u s 15 C a l a m a g r o s t i s r u b e s c e n s Rosa a c i c u l a r i s 16 Taraxacum o f f i c i n a l e 17 A c h i l l e a m i l l e f o l i u m IS S e n e c i o p a u p o r c u l u s 19 G c o c a u l o n l i v i d u m 20 S m i l a c i n a s t e l l a t a 21 G a l i u m b o r c a l e 22 A r c t o s t a F h y l o s u v a - u r s i 23 E p i l o b i u n angust i f o l i ur. 24 A g o s e r i s g l a u c a 25 Poa j u n e i f o l i a 26 P y r o l a secunda 27 V i o l a acunca 2B S i l e n e r c n z i c i i i 29 E q u i s e t u r s c i r p o i d o s 30 L i n n a c a b o r c a l i s 31 S c h i z a c h n e n u r p u r a s c e n s 32 V i c i a a r r e r i c a n a 33 M i t f . l l a nuda 34 F r a g a r i a v i r g i n i a n a 35 Anemone n u l t i f i d a 36 T h a l i c t r u i r o c c i d e n t a l e 37 A n t e n n a r i a u n b r i n e l l a 38 Ranunculus a c c i t r a t u s 39 M u h l e n b e r g i a r i c h a r d s o n i s 40 A g r o p y r o n s p i c a t u m 41 A s t r a g a l u s a l p i n u s 42 C a r e x s a l t u c n s i s 43 P o t e n t i l l a a n s e r i n a 44 H a b e n a r i a o b t u s o t a 45 J u n c u s b a l t i c u s 46 P o t e n t i l l a d i v o r i i f o l i a S h e p h e r d i a c a n a d e n s i s 47 C a r e x p r a o g r a c i l t s 49 Pa m a s s i a p a l u s t r i s 49 E q u i s c t u m a r v e n s e 0 L a y e r ( B r y o p h y t e s ) 50 Aulacomniura p a l u s t r c 51 P l e u r o z i u m s c h r c b o r i 52 C e r a t o t l o n p u r p u r e u s 53 Hylocomium s p l c n d e n s 54 P t i l i u m c r i s t a - c a s t r e n s i s 55 Eurhynchium p u l c h e l l u m 56 Dicranum p o l y s c t u m 57 D r e p a n o c l a d u s u n c i n a t u s 58 Dicranum f u s c c s c c n s 59 R h y t i d i a t l c l p h u s t r i q u e c r u s 60 B r a c h y t h o c i u i r s a l e b r o s u m 61 T o r t u l a r u r a l i s 62 D i s t i c h i u m c a p i l l a c o u m 6 3 Hypnum r e v o l u t u n 64 Torcnthypnum n i t e n s 65 A n b l y s t e g i u m s e r p e n s 66 P o l y t r i c h u m j u n i p o r i n u r r 67 Dicranum s c o p a r i u n 68 T o r t e l l a t o r t u o s a ( L i c h e n s I 69 C l a d o n i a c h l o r o p h a c a 70 Pc11 i g e r a aph t h o s a 71 P e l t i g e r a c a n i n a v a i 72 C l a d o n i a g r a c i l i s 7 3 Pc 1 t i g e r a n a l a c c a 74 C l a d o n i a p o c i l l u n 75 C l a d o m a r i t i s 76 P e l t i g e r a c a n i n a var 77 C l a d o n i a c o r n u t a 7B L e c i d e a b c r c n g c r i a n a 79 C e t r a r i a o r i c c t o r u r 80 C l a d o n i a c e n o t c a 61 C l a d o n i a nemoxyna 3.2 5.3 5.3 5.2 4.2 1.1 2.2 3.2 2.1 4.2 3.* 1.1 1.* 1.* 2.* 2.- 2.* 1.* 1.* 3.1 3.1 3.2 2.2 3.2 2.2 1.' 1.1 1. 3.2 3.2 3.2 2.2 2.2 2.2 6.4 5.3 5.3 5.2 3.2 3.2 5.3 4.3 4.3 4.3 3.2 3.2 2.1 1.1 . 1 3.2 2.1 3.2 3.1 2.1 . r u f e s c e n s 3.2 2.1 2.1 3.2 2.1 2.1 3.2 0.6 0.6 0.6 0.4 TOTAL SPECIES ( i n c 1. s p o r a d i c s ) S p o r a d i c s p e c i e s 82 A m e l a n c h i e r a l n i f o l i a 0 66(2. 8 3 J u n i p e r u s coranums 10 3(1. B4 R i b e s l a c u s t r e 1021*. 95 Sa H x g l a u c a 111(1. C Laypr 86 A g r o p y r o n t r a c h y c a u 1 urn 099(2. 67 A r c n a r i a l a t e r i f l o r a 0 6BI1. B8 A s t e r c o n s p i c u u s 1L1I+. B9 A s t e r ] u n c i f o r m i s 103(1. 90 A s t e r p.insus 099 (1 . 91 Carex i l i s p c r m a 102(1. 12 l l r i q c r o n a c r i s 103(1. 93 L a t h y r u s o c h r o l e u c u s 111(1. 94 Moneses u n i f l u r j 09911. E p i p h y t e s 109 A i c c t o r i a q 1 afti a 110 ilypoqymn i J physodes 11 1 C c t r u r u p i n a s t r i 95 O x y t r o p i s campestr 96 P e t a s i t c s v i t i f o l i 97 P y r o l a a s a r i f o l i a 99 C l a d o n i a 100 C l a d o n i a 101 C l o u o n i a 102 C l a d o n i a 105 Psoror.a hypnorum 10 6 Rhyncostea 1e1 l a c o r p a 107 Tor to 11a f r a g i 1 i s lriB T o r t u l a r u r a l i f o r t r i s I 2'i Mypi-gyirn i 0681 1 .-10212.-099 I * . \u00E2\u0080\u00A2 102 i ; . 0^8(1.-102 (1 .\u00E2\u0080\u00A2 099 I 2 . \u00E2\u0080\u00A2 10 3(1.-111(1.. 10 3(1.-099(1.-i Of.8 11 . 102 11.-009(1.-i' 1 i a c losis h y p c r o p t a u i a itdscvndens 207 hygric, with the depressions between the hummocks being hydric in the spring and the hummocks drying to a subhygric condition during the summer. The soils are medium to coarse textured and tend to become coarser with depth because of an increase in sand content. They are classed, texturally, as s i l t y clay loams, s i l t y loams, sandy loams or sands. Coarse fragments are absent except in the subsurface horizons of 068 and 111 which contained a few gravels and cobbles. The L-H horizon ranges from circumneutral to alkaline with pH values varying from 6.4 to 8.1. The s o i l reaction of the mineral s o i l i s alkaline with pH values ranging from 7.8 up to 8.1 and there i s no significant change in alkalinity with depth. The highest cation concentrations occur in the L-H horizon with calcium dominating the exchange complex. Exchangeable sodium i s present in very high amounts in the l i t t e r with values up to 8.4 meg/100 g but decreases substantially through the mineral s o i l so i s not li k e l y to inhibit plant growth. Exchangeable potassium and total phosphorus are present i n high amounts i n the L-H horizon and decrease with depth corresponding to a decrease i n organic matter content. Exchangeable calcium and magnesium are present i n high amounts in the mineral s o i l and do not significantly change i n concentration with depth. Carbon percentages are high in the L-H and A horizons indicating a large accumulation of organic matter. However, in the subsurface horizons carbon i s not measureable, thus i t appears that the s o i l i s not enriched by organic matter movement down the profil e from the surface. Nitrogen i s present in high amounts in the L-H horizon and decreases in concentration with depth through the mineral s o i l corresponding to the decrease in organic matter content. Similarly, the cation exchange capacity i s very high in the L-H horizon with values ranging up to 138 meg/100 g and decreases with depth in the mineral s o i l to values around 20 meg/100 g. Table 77 Soil Texture Carico (concinnae) - Piceetum glaucae Number of Plots 1 2 3 Plot No. 099 102 103 A Horizon Textural class Clay (%) S i l t (%) Sand (%) Coarse fragments B Horizon Textural class Clay (%) S i l t (%) Sand (%) Coarse fragments C Horizon Textural class Clay (%) S i l t (%) Sand (%) Coarse fragments No A SiL 25 49 26 None SiCL 15 55 30 None Data not avail-able None No B SiL 17 57 26 None S i i 7 49 44 None No B SL 11 30 59 None 068 111 SL SL 2 12 29 20 69 68 None None SiL SL 12 16 49 23 39 61 None g. S SL 0 13 1 12 99 75 209 Table 78 Soil Chemical Analysis Carico (concinnae) - Piceetum glaucae Number of Plots Plot No. 1 099 2 102 3 103 4 068 5 111 L-H Horizon C% N% C/N P ppm Na K Ca Mg CEC PH A Horizon C% N% C/N P ppm Na K Ca Mg' CEC pH B Horizon C% N% C/N P ppm Na K Ca Mg CEC pH C Horizon C% N% C/N P ppm Na K Ca Mg CEC pH 37.6 1.47 25.8 18.0 2.54 .78 34.2 37.0 103.7 7.7 No A 0 5. 17 13, 8, 7, .06 0 41 36 2 7 3 8 0 .12 0 6.0 .50 .73 18.5 15.6 26.2 8.0 46.8 1.72 27.2 27.0 8. 1. 27. 9, 138. 8. 4 82 4 6 0 1 Data not avail-able No B 0 .10 0 5.0 .69 .54 13.9 14.5 20.2 8.1 45.3 1.18 38.4 18.0 2.66 2.52 42.2 38.4 61.4 7.1 11.5 .53 21.7 16.0 1.38 1.21 9.3 20.0 73.1 8.1 No B 0 5. 13 14 20 8 .10 .0 .69 ,54 .9 ,5 .2 .1 36.5 1.25 29.2 19.0 2.58 .94 22.4 32.8 85.3 6.5 7.4 .31 23.9 10.0 1.11 .71 16.5 16.4 24.5 8.2 .11 0 7.0 .47 .40 15.9 9 17 7 0 .10 0 0 .33 .20 6.4 4.4 9 8.0 42.6 1.10 38.7 13.0 .66 2.70 49.6 15.0 62.3 6.4 25. 10. .2 .28 .7 ,0 .23 .51 14.6 7.7 31.1 7.8 35. 9. .4 .04 .0 .0 .29 .67 14.8 10.1 17.1 8.2 0 .06 0 8.0 .21 .51 11.2 7.8 11.8 8.1 210 There appears to be very l i t t l e movement of s o i l colloids down the profile by leaching in these poorly drained s o i l s . The uniform s o i l reaction and nutrient distribution i s thought to be controlled by the fluctuating water table which w i l l cause an upward movement of colloids through capillary r i s e . These soil s are nutritionally rich and the Carico - Piceetum glaucae i s con-sidered to be permesotrophic. Structurally the association consists of four vegetation layers. The well developed tree layer creates a heavily shaded habitat and i s composed of three sublayers of which the has the greatest percentage cover. The shrub layer (B) i s generally poorly developed and consists of two sublayers. The herb layer (C) is well developed as i s the bryophyte and lichen layer (D). Picea glauca, characteristic of these hygric sites, dominates the tree layer with species significances of up to 7. Pinus contorta and Populus t?:emuloides occur with low constancy and species significance in the drier communities of the association. Picea glauca also dominates the high shrub (B^) layer with an average species significance of 3.0. Salix monticola and Salix bebbiana are the only other species present in this layer with average species significances of 1.4 and 1.0 respectively. The B-, layer i s dominated by Rosa acicularis with an average species significance of 3.4. The presence of Betula glandulosa and Salix brachycarpa i s indicative of the cool microclimatic conditions of this association. Shepherdia canadensis i s the only other constant species and occurs on the drier hummocks. The C layer i s dominated by Carex concinna and Antennaria anaphaloides both of which are characteristic of this association. The constant presence of Calamagrostis rubescens suggests that the association i s seldom flooded as this species does not appear to be able to tolerate prolonged submergence. 211 Other constant species are Aster c i l i o l a t u s , Achillea millefolium and Senecio pauperculus. Arctostaphylos uva-ursi occurs with low species significance on hummocks which are drier than the rest of the habitat. Additional species occupying the drier parts of the association include: Geocaulon lividum, Galium boreale, Agoseris glauca, Vicia americana, Fragaria virginiana, Anemone multifida, Antennaria umbrinella and Agropyron spicatum. Equisetum scirpoides, Equisetum arvense, Ranunculus sceleratus, Parnassia palustris and Silene menziesii occur in depressions between the hummocks where the hygrotope varies from hygric to hydric. Species characteristic of moist forest sites include: Smilacina s t e l l a t a , Pyrola secunda, Linnaea borealis, Schizachne purpurascens, Mitella nuda and Thalictrum occidentale. Poa juncif o l i a, Juncus balticus, Potentilla anserina and Carex praegracilis a l l occur with low significance but are indicative of the alkaline, hygric conditions of the surface s o i l promoted by the fluctuating water table. Aulacomnium palustre with an average significance of 5.0 dominates the D layer and reaches i t s best development in the hygric to hydric depressions of the association. Pleurozium schreberi, Ceratodon purpureus, and Hylocomium splendens are constant subdominants occurring mostly on hummocks and at the base of trees. Other constant bryophytes include : Ptilium crista\u00C2\u00BB-castrensis , Eurhynchium pulchellum, Dicranum polysetum and Drepanocladus uncinatus. Lichens constitute less of the structure of the D layer than do bryophytes and reach maximum development in the drier parts of the association. The constant species are Cladonia chlorophaea, Petigera aphthosa, and Peltigera canina var. rufescens, a l l of which are present with low significance. Additional lichens present with low significance but characteristic of dry sites include: Cladonia g r a c i l i s , C. pocillum, C. mitis and Cetraria ericetorum. The epiphytic flora i s well developed in this deeply shaded cool 212 Fig. 26. The Carico - Piceetum glaucae showing the hummocky development of the ground which is characteristic of the association and controls the distribution of species. Fig. 27. The Equiseto - Piceetum glaucae formed on an a l l u v i a l terrace and showing the excellent growth of Picea glauca. The C layer i s dominated by a dense stand of Equisetum arvense which gives the association i t s characteristic appearance. 213 habitat. The most important epiphytes are: Alectoria glabra, Hypogymnia physodes, Cetraria pinastri, Letharia vulpina, Parmelia sulcata, and Usnea glabrescens. The Carico - Piceetum glaucae has a history of very slight grazing which does not appear to have substantially altered the structure of this association. Equiseto (arvensis) - Piceion glaucae Equiseto (arvensis) - Piceetum glaucae (ref. Tables; 79, 80, 81, 82, 83, and Fig. 27) Characteristic Combination of Species Order Characteristic Species Picea glauca Salix bebbiana Aster c i l i o l a t u s Delphinium brownii Epilobium angustifolium Petasites v i t i f o l i u s Pyrola secunda Silene menziesii Smilacina s t e l l a t a Thalictrum occidentale Drepanocladus uncinatus Alliance and Association Characteristic Species Alnus tenuifolia Cornus stolonifera Lonicera involucrata Ribes lacustre Viburnum edule Actaea rubra Cinna l a t i f o l i a Equisetum arvense Mitella nuda Moneses uniflora Pyrola a s a r i f o l i a Important Companion Species Rosa acicularis Linnaea borealis Eurhynchium pulchellum Pleurozium schreberi 214 Important Companion Species (Cont'd) Hylocomium splendens Ptilium crista-castrensis The Equiseto - Piceetum glaucae i s developed on newly formed a l l u v i a l terraces along streams and rivers on the Fraser Plateau. The terraces are either level with neutral exposures or gently sloping with northerly exposures. The r e l i e f shape varies from f l a t to concave. A cool microclimate prevails in this association as a result of cold a i r movement along the streams and rivers. The s o i l surface i s covered by a thick l i t t e r layer ranging in extent from 90% to 98% of the total surface area. In a l l plots sampled a small percentage of the surface was covered by decaying wood and mineral s o i l was exposed in only one plot. Soil drainage i s rated as moderate to imperfect and free water i s always present in the lower part of the s o i l p r o f i l e . Evidence of gleization in the form of mottling i s consistently present i n the subsurface s o i l s . This association i s frequently flooded. The Equiseto - Piceetum glaucae i s considered to be subhydric up to hydric during times of flooding. The soi l s are developed on a parent material of alluvium and c l a s s i f i e d as follows: Plots 090, 096, 100 and 101 have Gleyed Regosolic soi l s with an L-H, Cg, horizon sequence; plot 097 has a Rego Gleysolic s o i l with an L-H, Cg horizon sequence and plot 036 has an Orthic Humic Gleysolic s o i l with an L-H, Ah, Cg horizon sequence. The soi l s are medium to coarse textured and range from s i l t loams to sands. The soi l s tend to become coarser with depth as sand content increases down the p r o f i l e . Coarse fragments are generally absent but gravels and cobbles were found in the lower part of the C horizon of two plots. The coarse s o i l texture w i l l allow rapid drainage of the surface soi l s following flooding and thus maintain a well aerated s o i l . 215 Table 79 Equiseto (arvensis) - Piceetum glaucae Plot Data Number of Plots 1 2 3 4 5 6 Plot No. 097 096 036 100 101 090 Plot Size (m2) 400 400 400 400 400 400 Date analyzed 5/8 2/8 31/7 9/8 27/8 1/8 1968 1968 1967 1968 1968 1968 Elevation (ft) 2800 2850 3020 3500 3600 3650 Locality FP FP FP FP FP FP 51\u00C2\u00B048' 51\u00C2\u00B047' 51044. 51\u00C2\u00B043' 51044. 122\u00C2\u00B037' 122\u00C2\u00B037' 122\u00C2\u00B038 ' 122\u00C2\u00B058' 122\u00C2\u00B056' 122\u00C2\u00B057 Physiography Landform stream Relief shape concave concave f l a t Exposure NW NW neutral , Slope gradient (\u00C2\u00B0) 9 14 0 0 0 0 Layer coverage (%) Aj layer 41 42 64 51 48 26 A 2 layer 9 24 12 18 18 42 A3 layer 3 12 6 5 4 22 Bi layer 15 11 4 6 8 1 B 2 layer 20 18 9 11 26 4 C layer 96 46 85 64 75 71 D layer 74 86 21 13 23 41 Plot coverage (%) Humus and l i t t e r 98 95 90 98 98 96 Mineral s o i l - 1 - - - -Decaying wood 2 4 10 2 2 4 Soil Hygrotope Trophotope Erosion Drainage hygric - (hydric) .. subeutrophic .. n i l moderate moder-to imperfect ate imperfect Horizon depth (in) L-H surface subsurface 0-13 13-27+ 3-0 0-10 10-22+ 6-0 0-11 11-20+ 2-0 0-10 10-26+ 2-0 0-10 10-26+ 1-0 0-10 10-30+ Parent material alluvium Table 80 E q u i s e t o (arvensis) - Piceetum glaucae Number of P l o t s P l o t No. P l o t S i z e I 0.1(0-+) I 0.5(0-3) I I I 0.5(1T1> IV 0.3(+T+) I I 0.6(1-2) I I I 0.7(1-2) I I I 0.8(1-2) I 0.6(0-3) IV 1.8(+-4) I 0.6(0-3) V 2.0(2-3) I I I 0.8(1-2) IV 0.4(+rl) V 1.3(1-3) I 0.2(0-1) I 0.K0-+) V 2.6(2-4) I 0.4(0-2) IV 1.9(2-4) I 0.4(0-2) I 0.1(0-1) I 0.3(0-2) IV 0.5I+-+) IV 0.7I+-1) Drepanocladus uncinatus POO - CALAMAGROSTIDO - POPULION TREMULOIDIS POO - CALAMAGROSTIDO - POPULETUM TREMULOIDIS POO - CALAMAGROSTIDO - POPULETOSUM TREMULOIDIS I I I 0 . 5(+O) I I I 0 .5(1-2) V 1.6I+-3) IV 1.3(4-3) I I I 0.4I+-1) i 0.1(0-+) I I I 0.3I+-1) I 0 .1(0-1) V 1.0(+-2) I 0 .1(0-1) I I 0.3I+-1) I 0 . 1(0 - 4 ) I I I 1.6(2-3) I ' 0 .5 (1-2) I I I 0 8(1-2) I 0.1(0-+) V 6.0(4-7) V 6.5(5-8) IV 1.6(2-3) I I 1.0(2-3) I I I 1.3(2-3) V 1 6(1-2) I 0.4(0-2) IV 1.0(1-2) V 1 5(+-2) V 3.8(2-5) V 2.6(2-3) V 3.8(3-4) I 0 6(0-2) I I 0.4(1-1) I I I 0.6(+-2) I I 0 6(1-2) IV 1.8(1-5) IV 1.3(1-3) V 1.2(1-2) V 1.8(1-2) I 0.4(0-2) V 2.2(1-5) I I 0 4(1-1) I I 0.4(1-1) IV 0.9(4-2) V 2.9(2-4) I 0 2(0-11 I I 0.4(1-1) I I I 1.6(2-3) V 2.0(2-3! V 1 8(1-2) V 2.2(1-3) I I I 2.2(3-5) V 2.9(2-4) IV 1 8(1-3) V 3.8(3-4) I I I 0.8(1-2) IV 1.2(1-3) I 0 4(0-2) I I 1.4(0-2) V 1.6(1-3) V 2.7(2-3) Populus trewuloides I I I 2.0(3-4) I 0.1(0-1) I 0.2(0-1) V 1.6(4-3) V 7.2(7-8) V 7.0(6-B) I 0.6(0-3) I I 1.2(3-4) S a l i x glauca I I I 1.8(2-4) I 0.4(0-2) I 1.0(0-1) synphoricarpoa o c c i d e n t a l i s I 0.8(0-4) I 0.5(0-3) I 0.4(0-3) I I I 1.3(1-5) I I I 1.0(2-3) I I 0.4(4-2) I I I 1.6(2-3) IV 5.2(4-7) I I I 1.6(2-3) I I I 1.0(1-3) Astra g a l u s a l p i n u s V 2.4(2-3) I I I 0.6(1-4) Bromis a n o M l u s IV 1.6(1-3) i l 0.4(4-2) V 3.2(2-4) IV 2.0(1-4) I I I 0.8(1-2) Poa i n t e r i o r V3.4(3-4) V 3.2(1-51 I I I 0.8(1-3) P o t e n t i l l a g r a c i l i s I 0.1(0-1) I I 0.7(1-4) IV 1.0(1-2) I I I 0.4(4-1) A\u00C2\u00ABtolytt*gluB serpens V 4.4(4-5) I I I 1.4(4-3) IV 1.6(2-2) IV 3.2(3-4) I I 0.6(1-2) I 0.5(0-2) I 0.1(0-4) LONICERO - CARICETOSUM LEPTOPOOAB Rubus idaeus I I I 0.4(4-4) IV 2.0(2-3) A r . n a r i a l a t e r i f l o r a I 0.1(0-1) V 1.6(1-2) Carea leptopoda V 1.6(1-2) Beraclaua l a n a t u a IV 2.4(2-5) Osnorhiza c h i l e n a l s I I I 1.2(1-3) V i o l a canadensis V 2.4(2-3) I Z I 1.3(2-3) I 0.2(0-1) I 0.3(0-2) IIX 1.2(+-4) I I I 1.3(1-4) CARICO - FICTION GLAUCAE CARICO - PICEETUM GLAUCAE Antennaria anaphaloidss Carex concinna Equisetum s c i r p o i d s s Geocaulon l i v i d u m Schizachna purpurascsns Senecio pauperculus Aulacosmium p a l u s t r e BOUISETO - PICEION GLAUCAE EQUISETO - PICEETUM GLAUCAE Alnus t e n u i f o l i a Cornus s t o l o n i f e r a Lonicera i n v o l u c r a t a Viburnum edule Ribes l a c u s t r e Actaea rubra Clans l a t i f o l i a Equisetum arvense H i t e l l a nuda Moneses u n i f l o r a , Py r o l a a s a r i f o l i a GENERAL COMPANION SPECIES A c h i l l a e a m i l l e f o l i u m Agropyron subsecundum A l l i u m cemuum Erig e r o n speciosus Geum t r i f l o r u m Taraxacum o f f i c i n a l * Brachythecium salebrosum Ceratodon purpureus Drepanocladus aduncus P e l t i g e r a canina v a r . ru f a s c s n s P e l t i g e r a malacea FOREST COMPANION SPECIES Awelanchier a l n i f o l i a r r a g a r i a v i r g i n i a n a Iainnaea b o r e a l i s V i c i a americana Dicranum fuseescens Bylocomium splendens P e l t i g e r a canina v a r . c a i na FOREST COMPANION SPECIES (BOREAL ELEMENTS) Rosa a c i c u l a r i s Shepherdia canadensis Anemone m u l t i f i d a Galium b o r e a l * Lathyrus ochroleucus Solidago multiradiata V i o l a adunca Earhynchium pulchallum Pleuroxium schrsbsrt Ptiliam cxlsta-castrensis V 1.6(1-2) IV 2.8(2-4) I I 0.4(1-1) I I 0.3(1-1) I I I 0.6(1-2) IV 1,3(1-3) I 0.1(0-+) Z 0.4(0-2) t 0.2(0-+), IV 1.1(1-2) 1 0.6(0-3) I 0.2(0-1) IV 1.4(1-2) V 3.4(2-4) V 4.4(3-5) XII 1.2(2-2) IV 2,8(3-5) I I I 1.2(1-3) V 1.0(1-1) V 5.0(4-6) I I 0.7(0-2) IX 0.7(2-2) I I 0.6(+-3) I 0.1(0-+) I I I 1.2(2-3) IV 2.0(1-3) I I I 1,2(2-3) I I I 1.4(1-3) IV 2.2(1-4) I I I 0.6(1-1) I 0.1(0-+) V 1.6(1-2) 1 0.4(0-2) IV 1.2(1-2) V 4.4(4-5) V 6.0(5-7) X 0.1(0-+) I I I 0.3(+-l) V 1.5)1-4) I 0.4(0-2) I 0.1(0-+) V 1.4(1-2) V 2.8(1-4) V 3.2(3-4) V 5.0(4-6) V 1.8(1-3) I I 0.2(0-+) I 0.4(0-2) I I I 1.4(1-3) V 1.9(4-3) V 1.9(1-3) V 2.2(2-3) V 1.4(1-2) I 0.4 to- 2) I 0.1(0-4) V 2 .0 (2 -3 ) l l 0 . 8 I I - 3) V 1 .0(4 -2 ) I 0.4(0-2) I I I 0 . 6 (1 - 1) I I 0.4(1-2) I I 1.0(2-3) V 1.9(2-2) I I 1.0(2-3) I I I 0 .8(1-2) I I I 1.1(1-3) IV 1.4(1- 2) V 1.1(4-2) IV 1.6(1-4) I I 1.6(1-3) IV. 2.0(2-4) V 5 .3 (3-8) IV 0.4(1- 3) I I I 1.0(1-2) I 0 .1(0-1) I 0.2(0-1) V 2.3(1-3) IV 1 .6(1- 3) I I 0.4(1-21 V 1.8(1-3) I 0 .3(0-2) I 0.2(0-1) I 0 .3 (0 -2 ) 0.4(0-2) : 0.4(0-2) 0.8(2-2) ' 1.0I+-2) 1.6(2-3) 1.0(2-3) V 1.2(1-2) I I 0.2(+-+) I 0.3(0-2) IV 0.2(1-2) I I 0.7(2-2) I 0 . 4(0-2) I I I 0.8(1-2)-IV 0.8(+-2) I I I 1 .5(2-3) V 2.7(2-4) I I I 0.6I+-2) V 1.3I+-2) I I I 0.4(1-1) \u00E2\u0080\u00A2 I I I 0.5(4-4) I I I 1.1(1-3) IV 0.9(1-2) IV 0.8(4-2) I I 0.3(0-1) I I I 0.9(1-3) I 0.4(0-3) I 0.3(0-2) IV 1.6(1-3) V 2.4(2-3) V 2.2(2-3) I I I 1.0(2-3) V 2.8(2-5) I I I 1.6(2-4) V 1.1(4-3) V 1.4(1-2) I I 0.2(4-1) I 0.1(0-1) I I I 0.9(1-2) I I 0.5(1-2) I I I 0.4(4-1) IV 1.7(2-3) IV 1.0(1-3) .7(1-7) I I 0.6(1-3) V 1.3(4-2) I I 1.4(4-6) IV 1.7(2-3) I I 0.4(1-2) V 5.4(3-7) I I 0.3(4-1) V 2.6(1-3) IV 2.0(2-3) I I I 0.6(4-1) IV 1.2(1-2) IV 1.8(2-3) V 1.8(1-3) V 2.8(2-3) V 2.2(2-3) V 1.5(1-2) V 1.8(1-2) I I 0.5(1-2) I I I 1.0(1-2) IV 1.9(1-4) V 1.2(1-2) V 3.0(2-4) I I 0.3(1-1) IV 1.0(1-2) 5.9(4-6) I I 0.3(1-1) I I I 1.0)1-3) I I I 0.6(1-2) I I 0.5(1-2) I I 0.6(1-2) I I 0.7(2-3) I I I 2.0)3-4) V 1.1(1-3) IV 0.4(4-4) I I I 0.2(4-4) I I 0.4(1-1) I 0.2(0-1) I 0 . 4(0-2) I 0.3(0.2) V 1.8(1-3) I 0.1(0-4) I I I 1.2(1-2) I I I 0.8(4-2) IV 1.6(1-3) V 2.0(1-4) I I 0.6(2-2) I 0.5(0-+) IV 2.0(2-4) IV 1.6(1-3) V 0 .9(1-2) I I I 1.0(2-3) V 1.6(+-2) V 2 .1 (1-3) V 1 .1(4 -2 ) I I 0 .3 (1-1) I I I 0 .9 (1-3) V 2 .3 (1-4) I 0.1(0-+) I 0 .1 (0-1) I I I 0 .9 (1-2) V 1.7(1-3) V 1.8(+-2) I I I 0.3I+-1) V 1.7(1-2) IV 1.8(2-3) V 1.7(2-2) I I I 0.3I+-+) IV 1.5(1-3) V 3.7(1-7) V 2.3(1-5) V 1.7(1-2) I I I 0.9(+-3) IV 0.9I+-2) V 2 ,3(1-3) V 2 .4(2-4) V 1.4I+-3) I I 0 .2(4 -1) V 2 .2(4 -3) V 5.4(3-7) I I I 1.6(1-5) V 2 .5 (1 -3 ) V 1.3(1-2) IV 0 .8 (4-2) I I I 1 .3(2-3) I I 0 .3 (4-1) V 2 .3 (1 -3 ) V 5 .9(4-6) V 5 .0(3-7) V 3 .4(2-4) I I I 1.6(2-3) IV 1.4(1-2) V 2 .2 (2-3) V 2 .4 (1 -4 ) I 0 .4 (0 -2 ) V 1 .4(1-2) I 0 .2 (0 -1 ) V 3 .2 (3-4) I 0 .6 (0 -3 ) V 2.2(1-3) V 1.8(2-3) I I I 0.8(1-2) I I I 0.8(1-2) I I 0.4(1-1) V 1.6(1-2) I I I 0.1(1-2) V 1.6(1-2) IV 2.4(1-4) I 0.4(0-2) V 3.2(2-5) V 1.4(4-3) V 6.8(5-8) I 0.4(0-2) V 2.2(1-3) V 4.6(3-7) I I 0.8(2-2) I I 1.6(1-3) V 1.4(4-3) I 0.1(0-4) I I 0.3(4-1) I 0.2(0-1) I 0.1(0-+) V 1.3 (+-2) IV 0.8(1-1) I I 1.2(3-3) V 2.6(2-3) IV 1.6(2-2) I 0.4(0-2) I I I 4.5(+-2) I I I 1.2(1-3) I I I 1.2(2-2) IV 2.0(2-3) V 3.8(4-5) 3.0(3-5) 2.6(1-5) 0.8(1-2) 2.0(2-3) 0.2(0-1) I I I IV I I I 1.1(+-2) I I I 1.0(2-2) V 3.3(2-5) IV .1.5(1-3) V 2.3(1-3) rv 1.3(1-3) V 2.7(2-4) V 6.5(5-9) V 3.2(1-6) V 1.3(1-2) V 2.3(1-5) rv 0.8 (4-2) v 1.2(1-2) rv 1.2(1-3) m 0.4(2-3) in 0.4(+-l) in 0.8(1-2) V 4.3(3-6) V 1.2(1-2) I I I 0.8(1-2) V 3.3(2-7) I I I 0.8(1-2) V 3.2(2-4) I 0.1(0-+) I I I 1.0(1-3) rv 1.3(1-3) V 1.8(2-3) 2.4(2-4) 2.2(1-3) 1 3.8(4-5) 3.0(2-4) 4.2(3+5) 3 .3 (2-7) 3 .8 (1-6) 224 V POPULATION STRUCTURES OF THE MAJOR TREE SPECIES OF THE CARIBOO ZONE Methods of Analysis and Synthesis In a l l sampled forest communities the diameter of trees over 2 inches in dbh was recorded using a Lufkin Tree Tape. Average diameter was calculated for each species by layer and association. From the diameter data basal area per acre was calculated. The heights of a l l trees in the high shrub (B^) and tree layers were measured in feet using a Spiegle Relaskop. Height-age relationships were not calculated but the maximum height of tree species i s used as an i n d i -cation of growth. In order to determine ages, longevity and growth rate of tree species a series of increment cores was taken from trees of representative size classes. Ring counts were made on a l l cores and the results expressed as age at breast height. In each association the maximum age of the tree species present was determined by the oldest core of each species counted. Average age was calculated for a l l species by association. In addition to numbers of trees tabulated with the dbh measurements, the numbers of saplings (individuals 6 f t to 2 inches dbh) , transgressives (individuals 1 f t to 6 f t high) and tree seedlings (individuals less than 12 inches high) were counted and the densities recorded by species. Density per acre was calculated for tree species by height classes for a l l associations. For mensurational measurements separate records for l i v i n g and dead individuals were maintained. Growth and Population Size of the Tree Species In Fig. 28 basal area per acre for the major tree species i s presented by associations and in Table 84 age, height and diameter data i s presented. The following discussion i s based on these data. 225 Fig. 28. Basal Area Estimates in Square Feet per Acre for Pseudotsuga menziesii, Picea glauca, Pinus contorta and Populus tremuloides by Height Class for Associations of Occurrence J I k\\\\k\\\\\\\\\N kWWWWWWWW i 51 K\\\\\\\\\\\^ J a g I I 3 g a u 226 Pseudotsuga menziesii In the Cariboo Zone Pseudotsuga menziesii has the widest ecological amplitude of the tree species, being present in ecosystems varying from hygric to subxeric. In the Equiseto - Piceetum glaucae P. menziesii had a low basal area of 4.3 sq ft/acre because few trees are established in this hygric-subhydric association. Here, the largest tree of Pseudotsuga menziesii was 14.6 inches in diameter and 76 f t high and the maximum age recorded was 199 years. Pseudotsuga menziesii was only marginally represented in the Calamagrostido - Pseudotsugetum *glaucae pinetosum contortae with a basal area of 7.2 sq ft/acre. Here the trees were small, maximum height 61 f t and maximum diameter 10.0 inches\u00E2\u0080\u0094but also young. The maximum age of f i r was 55 years and average age 44 years. P. menziesii appears to be established recently (see page 233) and to be surviving with good vigor. Thus, i t i s predicted that the population size of Douglas-fir w i l l increase in this subassociation in the future. Pseudotsuga menziesii showed poor growth in the Arctostaphylo -Pseudotsugetum *glaucae which i s rated as the driest (subxeric) and trophically poorest (submesotrophic - ologotrophic) of a l l forest associations. Here, i t s total basal area was only 64.2 sq ft/acre of which the A2 layer constituted 63%. On these poor sites the average tree growth i s to a height of between 50 f t and 66 f t and the maximum height recorded was only 77 f t . However, the trees are relatively large with an average dbh of 10.1 inches and a maximum dbh of 25.3 inches, probably because the low density reduces competition for space. P_. menziesii appears to be long-lived in the Arctostaphylo - Pseudotsugetum *glaucae although i t s growth rate i s slow. The oldest tree of P_. menziesii cored was in this association at an age of 286 years and the average age of P. menziesii here was computed to be 131 years. 227 P. menziesii reached i t s best growth in the permesotrophic, Calamagrostido - Pseudotsugetum *glaucae calamagrostido - pseudotsugetosum *glaucae with a total basal area of 168.1 sq f t per acre. Sixty-six per cent of this total was contributed by individuals of the A^ layer which indicates that the height of mature trees i s commonly in excess of 66 f t . The highest tree measured was 102 f t . The largest tree of P_. menziesii, with a dbh of 33.4 inches, was found in this subassociation and the average diameter for the species was calculated here, to be 10.2 inches. The oldest tree cored was 198 years and the average age for the subassociation was 111 years. In the Rhytidiadelpho - Pleurozio - Pseudotsugetum *glaucae (which i s rated as permesotrophic) the growth of P_. menziesii was slig h t l y poorer than in the Calamagrostido - Pseudotsugetum *glaucae calamagrostido -pseudotsugetosum *glaucae but s t i l l very good. Here, i t s total basal area was 148.7 sq ft/acre and again over 2/3 of this was contributed by individuals of the A-^ layer. The t a l l e s t tree of P_. menziesii was in this association at 104 f t . The oldest tree cored was counted at 222 years and the average age of the association was calculated to be 119 years. The trees are relatively small with an average dbh of 7.3 inches, although the maximum dbh recorded was 30.1 inches. The density of P_. menziesii i s greater in this association than in any other, which i s probably because of the better moisture conditions, as this association i s considered to benefit from seepage and i s rated as subhygric. Picea glauca Picea glauca has a relatively narrow amplitude and i s confined to habitats which range from subhygric to subhydric. In the subhygric Rhytidiadelpho - Pleurozio - Pseudotsugetum *glaucae i t occurs with a very low basal area of 7.0 sq ft/acre. Here i t s maximum height i s only 67 f t and i t s maximum age i s 111 years. The trees are small, as the average dbh i s 4.6 inches 228 and the maximum diameter only 11.5 inches. In the subhygric to hygric, permesotrophic Carico - Piceetum glaucae the growth of P_. glauca i s much better. The total basal area was 142.5 sq ft/acre but only 22% was contributed by individuals of the A^ layer which suggests that trees produced on these sites seldom attain a height of over 66 f t . The highest tree measured was only 81 f t high. The oldest core counted was 156 years and the average age of the association was calculated to be 77 years. The density of spruce i s very high and correspondingly the trees are small with an average diameter of 7.3 and a maximum dbh of only 18.8 inches. The best growth of P_. glauca was in the hygric to subhydric, subeutroph Equiseto - Piceetum glaucae. P_. glauca had a total basal area of 182 sq ft/acre which was the highest of any species in any forest ecosystem. Of this total 74% was contributed by individuals of the A( layer indicating that mature spruce trees are generally t a l l e r than 66 f t in this association. A 117 f t high spruce, in the Equiseto - Piceetum glaucae was the t a l l e s t tree measured in any association. In this association the growth rate of spruce appears to be rapid as most trees are over 66 f t high and yet the average age is only 85 years. The largest spruce tree measured was 31.7 inches dbh and 153 years old. However, the trees are generally smaller and the average diameter for the association was calculated as 7.8 inches dbh. Pinus contorta Pinus contorta reached i t s best growth in the Calamagrostido -Pseudotsugetum *glaucae pinetosum contortae where i t had a total basal area of 120.7 sq ft/acre. Individuals of the A^ and A^ layers contributed 86% of this total and the A^ layer had a basal area of only 9.6 sq ft/acre. Thus i t i s apparent that P_. contorta on this habitat rarely grows t a l l e r than 66 f t although the t a l l e s t tree measured was 78 f t . The oldest tree of P. contorta cored was.176 years and the average 229 age of P. contorta was calculated to be 84 years. In this association the trees are relatively small; the largest tree measured was 17 inches dbh and the average diameter i s only 6.4 inches. P. contorta i s also present in the following associations: Arctostaphylo - Pseudotsugetum *glaucae with a basal area of 2.7 sq ft/acre in the Rhytidiadelpho - Pleurozio - Pseudotsugetum *glaucae with a basal area of 2.1 sq ft/acre in the Poo - Calamagrostido -Populetum tremuloidis lonicero - caricetosum leptopodae with a basal area of 2.6 sq ft/acre and in the Carico - Piceetum glaucae with a basal area of 4.1 sq ft/acre. Populus tremuloides Populus tremuloides i s present sparingly in the Carico - Piceetum glaucae and the Calamagrostido - Pseudotsugetum *glaucae pinetosum contortae. It assumes importance only in the Poo - Calamagrostido - Populetum tremuloidis (abbreviated in this section to P. - C. - P.t.). In the P. - C. - P . t . lonicero -caricetosum leptopodae i t has a total basal area of 161.3 sq ft/acre as compared to a total basal area of 111.2 sq ft/acre in the P. - C. - P.t. poo -calamagrostido - populetosum tremuloidis. The trees are generally t a l l e r in the P. - C. - P.t. lonicero - caricetosum leptopodae as 31% of the total basal area was contributed by the A^ layer compared to only 4% i n the P. - C. - P.t. poo -calamagrostido - populetosum tremuloidis. The t a l l e s t tree of P_. tremuloides measured, was in the P. - C. - P.t. lonicero - caricetosum leptopodae at 93 f t high. The maximum height of P. tremuloides in the P. - C. - P.t. poo -calamagrostido - populetosum tremuloidis was 72 f t . In both subassociations the trees are relatively small with an average dbh of 6.0 inches and a maximum dbh of 13.8 inches in the P. - C. - P.t. poo - calamagrostido - populetosum tremuloidis and an average dbh of 6.6 inches and a maximum dbh of 15.1 inches in the P. - C. - P.T. lonicero - caricetosum leptopodae. 230 In both subassociations the trees appear to be rather even-aged as the differences between maximum and average age i s less than for any other species. In the P. - C. - P.t. poo - calamagrostido - populetosum tremuloidis the maximum age i s 88 years and the average age i s 58 years and in the P. - C. -P.t. lonicero - caricetosum leptopodae the maximum age i s 97 years and the average age is 69 years. This even-aged condition suggests that P. tremuloides i s a successional species established in newly available habitats. It i s apparent that P. tremuloides reaches i t s best growth in the P. - C. - P.t. lonicero - caricetosum leptopodae. This higher site productivity i s thought to be due largely to the better moisture conditions of the P. - C. -P.t. lonicero - caricetosum leptopodae (see page ) as both subassociations are trophically similar. Population Dynamics of the Tree Species In Table 84 the densities of the four major tree species are summarized by height classes for the forest associations. The following discussion i s based on these data. Arctostaphylo - Pseudotsugetum *glaucae Pseudotsuga menziesii i s the dominant tree in the Arctostaphylo -Pseudotsugetum *glaucae. The seedling class has the highest number of individuals with a density of 400 stems per acre; There i s a general decrease in density with increasing height class to a low of six stems per acre in the A^ class. The density distribution of this association suggests that P_. menziesii i s easily and consistently established but suffers a high mortality in a l l successively greater height classes. This high mortality i s most l i k e l y a result of competition for moisture and nutrients as the Arctostaphylo -Pseudotsugetum *glaucae i s rated as subxeric and submesotrophic. The result i s a poorly stocked tree layer characterized by sparce tree cover and open forest 231 Table 84 The Density of Pseudotsuga menziesii (P.m.). Picea glauca (P.g.), Pinus contorta (P.c.) and Populus tremuloides (P.t.) by Height Class Expressed as the Number of Stems Per Acre Together with Height, Age and Diameter Measurements Under 1' Seed-l i n g -6' B 2 -33\" Bl -50* A3 -66' \u00C2\u00BB2 Over 66* Max Max Height Age Avg Age Max dbh Avg dbh Arctostaphylo -Pseudotsugetum P.m. P.g. P.c. P.t. 400 4 108 52 2 9 17 3 27 3 77 286 131 25.3 10.1 58 107 72 12.1 6.9 C. - P.*g. P.m. calamagrostido - P.g. pseudotsugetosum P.c. P.t. 460 77 100 28 70 87 102 198 111 33.4 10.2 C. - P.*g. pinetosum contorta\u00C2\u00A9 P.m. P.g. P.c. P.t. 134 160 23 53 81 110 5 21 187 4 180 11 61 78 37 55 176 44 84 10.0 5.3 17.0 7.2 6.4 4.6 Rhytidiadelpho Pseudotsugetum P.m. P.g. P.c. P.t. 803 32 42 7 63 15 85 7 82 133 10 104 67 79 222 111 128 119 30.1 7.3 11.5 4.6 9.3 P. - C. -poo -populetosum P.t P.m. P.g. P.c. P.t. 36 ? 18 8 34 134 212 204 72 88 58 13.8 6.0 P. - C. -lonicero -caricetosum P.t. P.m. P.g. P.c. P.t. 44 82 80 206 110 71 93 90 97 69 12.1 10.9 15.1 6.6 Carico -Piceetum P.m. P.g. P.c. P.t. 20 24 154 14 222 2 16 138 36 81 49 48 156 129 59 77 18.8 19.3 16.0 7.3 4.8 Equiseto Piceetum P.m. P.g. P.c. P.t. ? 110 2 27 2 50 5 65 2 5 72 142 76 117 199 123 14.6 7.2 153 85 31.7 7.8 232 conditions. P_. menziesii, because of i t s high reproductive capacity and presence in a l l height classes, i s considered as a climax species in this association. Pinus contorta also occurs in the Arctostaphylo - Pseudotsugetum *glaucae but with low density. It i s considered as a minor constituent and appears to be established with d i f f i c u l t y on these low elevational, subxeric sites. Calamagrostido - Pseudotsugetum *glaucae calamagrostido - pseudotsugetosum *glaucae In the Calamagrostido - Pseudotsugetum *glaucae calamagrostido -pseudotsugetosum *glaucae, Pseudotsuga menziesii i s the only tree present. The greatest number of individuals are present as seedlings and there i s a sharp drop in density to the next height class. This suggests that seedlings are easily established but because of competition, their survival rate i s low. There i s a second density drop between the and A^ layers (100 to 28) indicating that of the individuals established only a few reach tree size. On the other hand, the relatively high densities of the B^ and B^ layers as compared to the tree layers suggest that P. menziesii has the capacity to survive in a suppressed condition for relatively long periods of time in this association. Within the tree layer there i s an increase in density from the A3 to the A]L layer and the density of standing dead individuals i s very low at six stems per acre. Thus i t i s apparent that once P. menziesii reaches tree size, i t has a high survival rate, which i s probably because of reduced competition. Based on the density data P_. menziesii appears to be shade tolerant in this habitat and thus i s considered as the climax species of the Calamagrostido - Pseudotsugetum *glaucae calamagrostido - pseudotsugetosum *glaucae. 233 Calamagrostido - Pseudotsugetum *glaucae pinetosum contortae Pinus contorta i s the dominant tree and reaches i t s maximum density in the A 2 and A^ layers. It i s apparent that this species rarely reaches a height of greater than 66 f t as a density of only 11 stems per acre was recorded for the A^ layer. Regeneration of P. contorta appears to occur with d i f f i c u l t y as the densities of the seedling, B 2 and layers are substantially less than those of the tree layers. P. contorta i s thought to regenerate successfully only in areas which have been released from heavy shade by removal of the overstory. Pseudotsuga menziesii occurs as an understory species i n this sub-association and i s only sparingly present in tree layer. It has evidently become established after the dominant Pinus contorta as i t i s consistently younger. Pseudotsuga menziesii has a maximum age of 55 years and an average age of 44 years compared to the maximum age of 176 years and the average age of 84 years for Pinus contorta. A comparison of the density data of the two species shows that the ratio of Pinus contorta to Pseudotsuga menziesii in the A layer i s 14.6 to 1. The ratio of Pinus contorta to Pseudotsuga menziesii decreases to 2.3 to 1 i n the B layer and then to 1.2 to 1 in the seedling layer. It appears from these data that Pseudotsuga menziesii i s more shade tolerant than Pinus contorta and is thus regenerating more successfully. This i s supported by an examination of the numbers of standing dead individuals of the two species. In the understory (A3 and B layers) of the Calamagrostido - Pseudotsugetum *glaucae pinetosum contortae the density of standing dead individuals for Pinus contorta was 58.6 stems per acre and no dead individuals of Pseudotsuga menziesii were counted. Therefore Pseudotsuga menziesii because of i t s shade tolerance and long l i f e span w i l l replace the less shade tolerant, short lived Pinus contorta and become the climax species. 234 Rhytidiadelpho - Pleurozio - Pseudotsugetum *glaucae Pseudotsuga menziesii i s the dominant species of the Rhytidiadelpho -Pleurozio - Pseudotsugetum *glaucae where i t reaches i t s greatest density. It appears to be established easily in this subhygric habitat as reproduction counts show a seedling density of 803 stems per acre. There i s a sharp decline in numbers in the layer to a density of 42 stems per acre. This suggests that there is a high mortality rate of individuals in this size class and that perhaps P. menziesii cannot tolerate long periods of suppression in this moist habitat. This is supported by the fact that the greatest number of dead individuals at a density of 23 stems per acre was found in the understory, layer. However, numbers of individuals increase with each successive class from the B 2 layer through to the A^ layer. Thus i t i s apparent that once P_. menziesii reaches sapling size i t s survival rate increases through the remaining height classes. Picea glauca shows a relatively even density distribution through a l l size classes in this association. It i s apparent that relatively few seedlings of P_. glauca become established but that of these a high proportion survive. It i s believed that Pseudotsuga menzieii because of i t s high reproductive capacity and moderate shade tolerance w i l l continue to dominate this association and Picea glauca w i l l remain as a constant subdominant because of i t s apparent high survival rate. Poo - Calamagrostido - Populetum tremuloidis Populus tremuloides has an uneven density distribution in both sub-associations of the Poo - Calamagrostido - Populetum tremuloidis. It has high densities i n the tree layers and shows a marked reduction i n numbers in the understory. P_. tremuloides seedlings were not counted in either subassociation. This lack of reproduction suggests that P_. tremuloides i s a highly shade intolerant species and that young trees are established only when parts of the 235 overstory are removed. P. tremuloides is thus considered a pioneer species possibly established following f i r e as has been reported by Rowe (1952) and Moss (1955) , Picea glauca i s present with low density in the seedling and layers of the Poo - Calamagrostido - Populetum tremuloidis. Since Picea glauca i s more shade tolerant than Populus tremuloides, i t i s possible that i t may become the climax species of this association. Carico - Piceetum glaucae Picea glauca i s the dominant tree of the Carico - Piceetum glaucae and i s present in a l l height classes. It has a very low seedling density of 20 stems per acre. However, the number of individuals increases through the B layer to a maximum density of 222 stems per acre in the A^ layer. As was previously stated, Picea glauca rarely reaches a height i n excess of 50 f t i n this association and thus the densities of the and A^ layers are substantially lower at 138 stems per acre and 36 stems per acre respectively. The low numbers of seedlings and transgressives suggests that P_. glauca regeneration occurs with d i f f i c u l t y . P. glauca i s considered to be only marginally shade tolerant in this hygric to hydric habitat and seedling establishment i s thought to occur on the better drained hummocky sites. Once established, spruce appears to survive well up to the B^ layer. Here, the greatest number of dead individuals, at a density of 46 stems per acre was found, suggesting that P. glauca cannot survive well in a suppressed condition in this habitat. However, once trees reach a position in the A layer their survival rate i s high as no standing dead individuals were present i n the A^ and A2 layers and a low dead density of 8 stems per acre was recorded for the A^ layer. P. glauca i s considered as a climax species in this association as there appears to be sufficient evidence of restocking. 236 Equiseto-Piceetum glaucae Picea glauca dominates the Equiseto - Piceetum glaucae where i t i s present in a l l height classes. The seedling density i s relatively low at 110 stems per acre. There is a continual increase in densities from 27 stems per acre for the B 2 layer to 142 stems per acre for the A^ layer. It i s apparent that P. glauca seedlings are established in low numbers, perhaps because P. glauca i s only moderately shade tolerant in this hygric-subhydric habitat. Of those established a high proportion survive up to the B, and A3 layers. Here the greatest number of trees succumb with densities of dead individuals being calculated at 48.3 stems per acre and 20 stems per acre respectively. This suggests that in this wet habitat, P. glauca, because of i t s shade intolerance cannot survive well as a suppressed understory tree. However, once individuals reach a position in the canopy their survival rate appears to be high as the density of standing dead trees in these classes was very low at 10 stems per acre for A 2 layer and 6.7 stems per acre for the A^ layer. The result i s a well stocked tree layer with a closed canopy. Picea glauca w i l l continue to dominate this association as seedling establishment and survival appears to be adequate to restock any vacancy created in the overstory. Pseudotsuga menziesii occurs as a minor constituent with low density and only in the driest parts of this association. No seedlings of P_. menziesii were counted. It thus appears that P. menziesii is only rarely established here. This is due partly to i t s shade intolerance in hygric to hydric sites and partly to i t s intolerance to frequent flooding. In general, i t is apparent, that relatively few seedlings of Picea glauca do become established but of this a rather high proportion survive, while quite the reverse i s true of Pseudotsuga menziesii seedlings which become established in high numbers but suffer a high mortality in the understory height 237 classes. Thus i t appears that Picea glauca maintains i t s dominance because of a high survival rate while Pseudotsuga menziesii maintains dominance because of i t s p r o l i f i c reproduction. Pinus contorta and Populus tremuloides reach dominance only as pioneer species as neither appears to be very shade tolerant and thus they both regenerate poorly under established forest canopies. 238 VI MICROCLIMATE Methods of Analysis and Synthesis Ten micro-climatic stations were established in previously sampled plots and maintained from May 20 to September 15, 1968. Each station con-sisted of a Stevenson Screen inside which a Fuess hygrothermograph was placed to continually record temperature and humidity. The screens were placed directly on the ground instead of at conventional meteorological height in order to record data at the plant level. A l l stations were in the Farwell Canyon area of the Fraser Plateau and the locations are given by plot and association in Table 85. During the period of analysis the thermographs were frequently checked against a standard mercury thermometer and, i f necessary, recalibrated. In this dry dusty area i t was not possible to maintain the hair bundle of the hygrograph in a satisfactory operating condition. Thus the humidity data obtained were considered to be only very approximate and are not presented in deta i l . Daily maximum, minimum and mean temperatures were computed from the thermograph charts for each station. These data, summarized by the week and the month are given in Appendix IV. The monthly summaries showing the average maximum temperatures, the average minimum temperatures, the maximum temperatures and the minimum temperatures are presented graphically for the ten stations by association in Fig. 29. Detailed winter observations were not included in this study. However, one reconnaissance t r i p was made to the Fraser Plateau during the period of March 1 to March 4, 1969. Snow depths were measured on previously sampled plots and observations were made on snow d r i f t i n g , melting, wind packing and accumulation. 239 Table 85 Location of Microclimatic Stations Station Plot Association No. Slope Longi- Lati-Elevation Exposure Angle tude tude (ft) Agropyro -Artemisietum 039 tridentatae 1540 total 0\u00C2\u00B0 122\u00C2\u00B034' 51\u00C2\u00B050' Opuntio -062 Stipetum comatae 1700 SW 2\u00C2\u00B0 121\u00C2\u00B031' 51\u00C2\u00B050' Agropyro -Artemisietum 041 tridentatae 1800 NW 3\u00C2\u00B0 122\u00C2\u00B034' 51\u00C2\u00B049' Opuntio -044 Stipetum comatae 1920 S 4\u00C2\u00B0 122\u00C2\u00B030' 51\u00C2\u00B050' Agropyretum 060 spicati 2120 N 23\u00C2\u00B0 122\u00C2\u00B033' 51\u00C2\u00B048' Agropyretum 064 spicati 2200 NW 28\u00C2\u00B0 122\u00C2\u00B032' 51\u00C2\u00B050' G. - P.*g. calamagrostido -061 pseudotsugetosum *glaucae 2500 N 14\u00C2\u00B0 122\u00C2\u00B034' 51\u00C2\u00B047' C. - P.*g. pinetosum 051 contortae 3000 N 5\u00C2\u00B0 122\u00C2\u00B037' 51\u00C2\u00B046' Stipetum 027 richardsonii 3100 E 4\u00C2\u00B0 122\u00C2\u00B039' 51\u00C2\u00B042' 10 Antennario -071 Poetum secundae 3150 total 0\u00C2\u00B0 122\u00C2\u00B038* 51\u00C2\u00B042' 240 Comparison of Selected Associations Based on Microclimate Based on temperature i t i s possible to characterize the two alliances of the Koelerio - Agropyretalia spi c a t i . Associations of the Agropyrion spicati (represented by stations 1-6, Fig. 29), develop at low elevations and correspondingly in a warm climate. Average minimum temperature for the summer season ranged from 46\u00C2\u00B0F to 50\u00C2\u00B0F and the temperature never dropped below 32\u00C2\u00B0F; the minimum summer temperature ranged from 33\u00C2\u00B0F to 38\u00C2\u00B0F. The average maximum temperatures in the Agropyrion ranged from 75\u00C2\u00B0F to 80\u00C2\u00B0F and the maximum summer temperature ranged from 96\u00C2\u00B0F to 100\u00C2\u00B0F. In contrast, associations of the Stipion columbianae (represented by stations 9 and 10 in Fig. 29) are formed on upland sites at high elevations where a much cooler climate prevails. Here, the average minimum temperature for the summer ranged from 37\u00C2\u00B0F to 39\u00C2\u00B0F and the minimum summer temperatures were well below freezing at 24\u00C2\u00B0F and 27\u00C2\u00B0F. The average maximum summer temperatures recorded for this alliance were 66\u00C2\u00B0F and 70\u00C2\u00B0F. The maximum temperatures were much lower than the previous alliance at 88\u00C2\u00B0F and 89\u00C2\u00B0F. Temperature data were recorded for three associations of the Agropyrion spicati, namely, the Agropyro - Artemisietum tridentatae (stations 1 and 3), the Opuntio - Stipetum comatae (stations 2 and 4), and the Agropyretum spicati (stations 5 and 6). The temperature data for these associations are very similar. The average maximum temperatures range from lows in May of 66\u00C2\u00B0F in the Agropyretum spicati (station 6) and 69\u00C2\u00B0F in the Opuntio - Stipetum comatae and Agropyro -Artemisietum tridentate,to highs in July of 85\u00C2\u00B0F for the Agropyretum sp i c a t i , 84\u00C2\u00B0F for the Opuntio - Stipetum comatae and 87\u00C2\u00B0F for the Agropyro - Artemisietum tridentatae. The highest temperatures were recorded in July at 98\u00C2\u00B0F for the Opuntio - Stipetum comatae and 100\u00C2\u00B0F for the Agropyretum spicati and Agropyro -Artemisietum tridentatae. The average minimum temperatures ranged from lows i n 241 Fig. 29. Maximum ( ), Average Maximum ( ), Average Minimum ( ) and Minimum ( ) . Temperatures Recorded at the Microclimatic Stations for the Months of May, June, July, August and September (1968). In May temperature was recorded only from the 26 to 31 and i n September temperature was recorded only from the 1 to 14. The f i r s t graph shows a temperature summary based on the May to September observation period. 242 May of 39\u00C2\u00B0F for the Agropyretum spicati and 43\u00C2\u00B0F for the Opuntio - Stipetum comatae and Agropyro - Artemisietum tridentatae to highs in July of 52\u00C2\u00B0F for the Agropyretum spicati and 53\u00C2\u00B0F for the Opuntio - Stipetum comatae and Agropyro - Artemisietum tridentatae. The minimum temperatures were in the high t h i r t i e s during late May and June and in the low forties for July and August. Frost was not encountered in any of the three associations during the summer of 1968. The minimum temperatures of the Agropyretum spicati are consistently slightly lower than corresponding temperatures in the other two associations. This i s thought to be a function of the northerly exposures on which the Agropyretum spicati reaches i t s best development. Temperature data were recorded for only two associations of the Stipion columbianae\u00E2\u0080\u0094the Stipetum richardsonii (station 9) and Antennario -Poetum secundae (antennario - poetosum secundae) (station 10). Based on temperature i t appears that the two associations occupy microclimatically different habitats. The average maximum summer temperatures were 70\u00C2\u00B0F for the Stipetum richardsonii and 660F for the Antennario - Poetum secundae. The average minimum o o temperatures were 41 F for the Stipetum richardsonii and 44 F for the Antennario -Poetum secundae. Average maximum temperatures were consistently higher in the o 0 Stipetum richardsonii and ranged from a low of 61 F in May to a high of 76 F in July. Average maximum temperatures for the Antennario - Poetum secundae ranged from 60\u00C2\u00B0F in May to 74\u00C2\u00B0F in July. The warmest temperatures recorded were in July at 87\u00C2\u00B0F for the Stipetum richardsonii and 88\u00C2\u00B0F for the Antennario - Poetum secundae. A completely opposite temperature trend was recorded for the minimum temperatures as the Stipetum richardsonii had consistently lower temperatures than the Antennario - Poetum secundae. The average minimum temperatures for the o 0 Stipetum richardsonii ranged from a low of 32 F in May to a high of 41 F in July 243 and was below 40\u00C2\u00B0F for four months. The average minimum temperatures for the Antennario - Poetum secundae ranged from a low of 34\u00C2\u00B0F in May to a high of 44\u00C2\u00B0F in July. The minimum monthly temperatures recorded for the Stipetum richardsonii was below 32\u00C2\u00B0F for a l l months with the lowest being 24\u00C2\u00B0F in June. Thus i t i s apparent that frosts occur in every month of the growing season. On the other hand, the minimum monthly temperatures for the Antennario - Poetum secundae were below 32\u00C2\u00B0F only in May and June with lowest temperatures being recorded in June at 27\u00C2\u00B0F. During the period of observation, temperatures below 32\u00C2\u00B0F were recorded on 28 days in the Stipetum richardsonii and on only 11 days in the Antennario - Poetum secundae. From these data i t is apparent that the Stipetum richardsonii has a greater temperature range than the Antennario - Poetum secundae. The higher maximum and lower minimum temperatures of the Stipetum richardsonii are thought to be a result of the protected habitats in which i t develops. These habitats provide protection from wind and thus convection cooling w i l l be minimal, so high daily temperatures are reached. In the exposed habitats of the Antennario -Poetum secundae, the reverse i s true; here convection cooling resulting in a lowering of the maximum temperatures i s thought to be an important factor. The low minimum temperatures recorded in the Stipetum richardsonii are thought to result from the trapping of cold a i r by the protected habitats where-as in the Antennario - Poetum secundae, the exposed habitat has continual a i r circulation, preventing cold air build-up and thus warmer minimum temperatures prevail. From the temperature data i t appears that \"frost-pocket\" conditions prevail in the Stipetum richardsonii and the development of the association i s considered to be linked to this phenomenon. Stations 7 and 8 were located, at relatively high elevations, in the calamagrostido - pseudotsugetosum *glaucae and the pinetosum contortae, both 244 subassociations of the Calamagrostido - Pseudotsugetum *glaucae. Because the stations were located at ground level the temperatures recorded were greatly affected by the presence of the tree canopy. The average maximum temperature for the summer in the pinetosum contortae (station 8) was 65\u00C2\u00B0F, compared to 70 F in the calamagrostido - pseudotsugetosum *glaucae (station 7) and the corresponding maximum temperatures were 84\u00C2\u00B0F and 94\u00C2\u00B0F. These temperatures are lower than would have been recorded on nonforest sites at the same elevations as the tree canopy acts as a f i l t e r to direct insolation and thus effectively lowers the temperature. The average summer minimum temperatures were 44\u00C2\u00B0F at station 7 and 40\u00C2\u00B0F at station 8. These are slightly higher than would be obtained on similarly located non-forest sites because the tree canopy acts as a radiation shield and thus cuts down on effective heat loss from the s o i l surface by re-radiation at night. However, the minimum summer temperatures were 32\u00C2\u00B0F at station 7 and 26\u00C2\u00B0F at station 8 indicating frosts do occur in these forest communities during the growing season. The consistently higher temperatures recorded at station 7 are thought to be partly because i t was located at an elevation 500 f t lower than station 8 and partly because the forest canopy i s very open as compared to station 7, thus insolation w i l l be increased. Compared with the other stations the temperature of these forested communities i s most similar to those recorded for the associations of the Stipion columbianae. During the entire summer the forest communities had temperatures significantly lower than those of the Agropyrion spi c a t i . This indicates that forest communities are restricted to the cooler parts of the region and that possibly temperature limits tree growth in the major valleys as the high temperatures which prevail there may be lethal to tree seedlings. These high temperatures are less harmful to species of the Agropyrion spicati, perhaps because during the time when the highest surface temperatures were recorded many species were already i n a state of dormancy, 245 having completed flowering and fruiting in the early summer. During the period of observation the diurnal temperature regime followed a constant pattern. Daily maxima were reached usually between 3 p.m. and 5 p.m. (Pacific Standard Time) with the upland stations (7-10) reaching their maxima approximately one hour in advance of the valley stations (1-6). This indicates that cooling effects which result in a negative net radiation balance (outgoing greater than incoming) occur f i r s t at the higher elevations. The daily minimum temperatures were usually reached between 4 a.m. and 6 a.m. (P.S.T.) with the upland stations reaching their minima approximately one hour in advance of the valley stations. Thus the reversal of the radiation balance from negative to positive occurs f i r s t at the higher elevations as these sites are influenced earlier by morning sun. In areas such as this the cooling effect experienced in the valley i s regarded to be associated with a cold a i r drainage resulting from down-valley winds which occur at night (Geiger 1965). In contrast up-valley winds prevail during the day because of the ri s i n g effect of warm a i r . The diurnal relative humidity regime followed a pattern opposite to the temperature pattern. The lowest humidities were recorded in the late afternoon and the highest in the early morning. The relative humidity at stations 9 and 10 was frequently recorded in the range of 20% to 30% during the day and i n the range of 80% to 90% at night. In the valley (stations 1-6) the daily humidities were generally higher possibly because of the effect of moist air rising off the Chilcotin River. At night, however, the humidities reached highs similar to those of the upland sites . The significant daily humidity regain (of up to 60%) i s thought to be an important factor helping to maintain the moisture balance of plants growing in this sub-humid region. 246 No precipitation records were kept during the study period but total precipitation for the Farwell Canyon i s estimated to be less than the annual average of 12 inches recorded at Big Creek, B. C. During the summers of 1967 and 1968, thunder showers of narrow amplitude and short duration were observed to be frequent occurrences. Thus i t appears that summer precipitation in this region i s often very localized. In the area in which the climatic data were recorded the snow pattern i s very distinct. The valley associations (Agropyrion spicati) have a lower total snow accumulation than do the upland associations (forest and Stipion columbianae) and are snow free approximately one month earli e r in the spring. Snow melt occurs f i r s t on the gentle southerly exposed slopes occupied by the Opuntio - Stipetum comatae; secondly in the Agropyro - Artemisietum tridentatae and l a s t l y on the steep northerly exposed slopes on which the Agropyretum spicati occurs (see Fig. 38). The late snow l i e of the Agropyretum spicati i s considered to be important in i t s development by providing a longer supply of available moisture at the beginning of the growing season. In the upland areas snow measurements were made on March 4, 1969 in communities of the Stipetum richardsonii and Antennario - Poetum secundae (antennario - poetosum secundae); these are summarized in Table 86. Recorded snow depths ranged from 6 inches to 14 inches in the Antennario - Poetum secundae and from 21 inches to 27 inches in the Stipetum richardsonii. In the Antennario - Poetum secundae the snow surface was observed to be strongly wind packed and small d r i f t s were present. No such conditions were present in the Stipetum richardsonii. By March 4, 1969, the snow cover of the Antennario - Poetum secundae was already strongly affected by spring melt whereas in the Stipetum richardsonii only slight evidence of melting was observed. The low snow accumulation coupled with rapid melting in the Antennario -Poetum secundae exposes the s o i l surface well in advance of the growing season. 247 Table 86 Summary of Snow-Cover Data for the Antennario - Poetum secundae and Stipetum richardsonii March 4, 1969 Association Snow Depth Drifting Evidence of Melt Wind Packed Avg Range Antennario -Poetum secundae 8\" Stipetum richardsonii 24\" 6-14\" yes 21-27' no strong slight Yes no 248 In contrast the higher snow accumulation and slow melting i s believed to b e n e f i t the development of the Stipetum r i c h a r d s o n i i by providing a source of a v a i l a b l e moisture at the beginning of the growing season. It appears, a l s o , that plants composing the Stipetum r i c h a r d s o n i i are w e l l protected i n the winter by the deep snow coupled with n e g l i g i b l e wind e f f e c t s . This may i n part explain the frequent occurrence of tree seedlings and transgressives i n t h i s a s s o c i a t i o n . It i s p o s s i b l e to b r i e f l y summarize the microclimate r e s u l t s as follows. The associations of the Agropyrion s p i c a t i are developed i n areas with warm microclimates where summer f r o s t s are infrequent. In contrast, associations of the Stipion columbianae are developed i n areas with cool micro-climates where summer f r o s t s are frequent. The Stipetum r i c h a r d s o n i i c o n s i s t e n t l y reaches lower minimum temperatures than does the Antennario - Poetum secundae and thus summer f r o s t s are more frequent i n the Stipetum r i c h a r d s o n i i . It i s a l s o influenced by greater snow accumulation and longer snow duration. It appears that \" f r o s t -pocket\" conditions p r e v a i l i n the Stipetum r i c h a r d s o n i i and may p a r t i a l l y c o n t r o l i t s development. The f o r e s t associations monitored showed a temperature pattern s i m i l a r to that of the Stipion columbianae. Thus, i t appears that f o r e s t communities are r e s t r i c t e d to the cooler parts of the region and that high temperatures may be a l i m i t i n g f a c t o r to tree growth i n the major v a l l e y s . 249 VII CLUSTER ANALYSES In Chapter IV, using traditional phytosociological methods the 131 sampled plots (communities) were grouped into associations and these in turn were grouped into the higher ecosystem units of alliances and orders. This resulted in a meaningful hierarchial classification based primarily on f l o r i s t i c c r i t e r i a . The methods of construction used were subjective and for the most part relied on simple presence and absence of species (calculated as constancy) to form the ecosystem units. In this chapter the communities are objectively compared as to their degree of f l o r i s t i c similarity using quantitative data (species significances) and then objectively grouped so as the degree of a f f i n i t y between individual communities and groups of communities is demonstrated. This chapter i s intended as a supplement to the previously discussed cla s s i f i c a t i o n (Chap. IV). Methods of Synthesis S t a t i s t i c a l methods which can be applied to show the relationships between vegetation units using subjectively gathered plot data are limited. Becking (1957) gives a brief review of appropriate mathematical equations developed by earlier workers. Of those discussed The Index of Similarity (Sorensen 1948) has been most widely used. This index was chosen to compare the sampled communities in this study because of i t s wide usage and because i t employs quantitative data in i t s mode of calculation. The Index of Similarity i s computed by the formula 2W x 100, where \"a\" is the sum a + b of the quantitative measures of the plants in one plot (community), \"b\" is the corresponding value for a second plot and \"w\" is the sum of the lesser values for only those species which are in common to both plots (Oosting 1956, p. 77, Greig-Smith 1964, p. 137). The index has a range from 0 for two communities with no measures in common to 100% for two communities which are 250 quantitatively identical. The quantitative measures used in the calculations were the species significance values of a l l vascular, bryophyte and lichen species. The indices of similarity between the communities were calculated using a program developed by Ream (1965) and modified by Bordon (1967). Following the calculation of the indices of similarity between the 131 sampled plots (communities), methods of cluster analysis using the indices of similarity as a basis were employed to group communities according to f l o r i s t i c similarity, so that the degree of a f f i n i t y between groups would be demonstrated. Cluster analysis, according to Sokal and Sneath (1963) i s a name given to numerical techniques used to determine groups of related units (in this case plant communities) on the basis of high coefficients of similarity. Basically cluster analysis i n i t i a l l y groups together highly similar communities (those with high indices of simi l a r i t y ) . This usually means that communities in these groups have a l l major species in common. Then new indices of similarity are calculated for the groups formed and these are united according to their degrees of similarity. This results in a hierarchical arrangement of communities and groups of communities. Two average linking methods of cluster analysis were used in this study. These were the weighted-pair-group method and the weighted-variable-group method which are described by Sokal and Sneath (1963) and recognized to produce similar results. Community groupings were made by both methods in order to determine which method results in the ecologically most meaningful arrangement of communities. The weighted-pair-group method has been used in previous ecological studies by West (1966) and Lambert (1968) with satisfactory results. This method pairs the two most highly correlated communities or groups of 251 communities at each cycle. In each case the resulting new group has for i t s similarity index the average between the similarity indices of the two communities or groups of communities which were paired to form i t , i.e. x + 1 2 This method i s considered by Sokal and Sneath (1963) to show the least dis-tortion of the original similarity coefficient matrix and to be devoid of any arbitrary criterion of group formation. However, this method of simple averaging, where each new member i s weighted equal to the sum total of a l l old group members, w i l l tend to reduce the importance of communities admitted early and increase the importance of those admitted later, i n the determination of new groups. This increased importance of late arrivals may result in a distortion of the relationship between clusters, as communities admitted late in the clustering necessarily have a low similarity with communities already grouped. The weighted-variable-group method appears to be used less frequently possibly because of the greater computational load involved i n i t s mode of calculation (Sokal and Sneath 1963). In this method each new group, resulting from the pairing of highly correlated communities, or community groups has for i t s index of similarity the average of a l l similarity indices between communities composing the group, i.e. X X X + 1 ( S l + S 2 Sn* > - S l n In this method a l l communities are weighted equally and thus there i s a tendency to reduce the importance of members which because of their lower coefficients of similarity are omitted late in the clustering. This method i s also free of any 252 arbitrary criterion of group formation. The most convenient and informative way of representing the clusters resulting from these analyses i s in the form of two-dimensional dendrograms. In these dendrograms, communities (plots) are represented on the abcissa and the level of vegetation similarity in per cent i s shown on the ordinate. The indices of similarity between pairs of highly similar communities are shown by the position of the highest horizontal connecting lines between vertical lines representing communities. I n i t i a l community pairs are grouped with other unpaired communities or groups of communities by calculation of the corresponding indices of similarity. The relationships between these successively larger and more diverse community groups are shown by horizontal connecting lines placed at progressively lower levels of similarity. These dendrograms can be used to interpret the degree of vegetation homogeneity of community groupings (West 1966) as the more homogeneous the grouping of communities the higher i s i t s level of similarity. Comparison of the Weighted-Pair-Group and the Weighted-Variable-Group Methods of Cluster Analysis Dendrograms representing the clusters of communities calculated by the weighted-pair-group method and the weighted-variable-group method are presented in Fig. 30 and 31 respectively. On both dendrograms, the subassociations and associations, synthesized and described in Chapter IV are delimited. The degree of similarity between communities (plots) composing associations can readily be seen on the dendrograms. These within group similarities are used as estimates of the homogeneity of the associations\u00E2\u0080\u0094the higher the level of similarity within the association, the more homogeneous i t i s considered to be. Although not delimited, the higher ecosystem units of alliances and 253 Fig. 30. Dendrogram of the 131 Plots Obtained by the Weighted-Pair-Group Method of Cluster /analysis. Plots are l i s t e d on the abcissa and the level of vegetation similarity in per cent i s shown on the ordinate. The sub-associations and associations described in Chapter IV are delimited and the degree of similarity between plots composing associations i s shown by the horizontal lines connecting the vertical plot lines. J4\u00C2\u00BB / / Antennario-Poetum secundae ^ \u00E2\u0080\u00A2 c s i c o ^ i n U J C T i O c o r - O a J r - . 0 - N < N f O N ( M C M / # 4 \u00C2\u00B0 CO O) CM 00 ID \u00E2\u0080\u0094 -sr 00 CSI \u00E2\u0080\u0094 O CD CO CO N C N O J C J M 1 0 0 5 C O C O \u00C2\u00ABg- co CNI \u00E2\u0080\u0094 in CM in n to N / p / >> CO M O O) CMIOO CO UO -*T CO o c o o c o r ^ K o c o ^ r ^ r ^ c o c ^ ^ co - * O \u00E2\u0080\u0094 \u00C2\u00A9 9 Calamogrostido - Pseudotsugetum \u00E2\u0080\u00A2glaucae \u00E2\u0080\u00A2tc* a. / Poo -Calamagrostido Populetum tremuloidi $ l s N C M ' t N N M C - l t l D C O l O l D C n O C O N c D O B ' \" * in f to t to \u00E2\u0080\u0094 ca O) oo co cn oo \u00E2\u0080\u0094 \u00E2\u0080\u0094 in in m \u00E2\u0080\u0094 \u00E2\u0080\u0094 iff & oo r - to / A A i-\u00C2\u00BB \u00E2\u0080\u0094|cr> o \u00E2\u0080\u0094 t in n m ID in N \u00E2\u0080\u0094 OTlcnooorrcnoo'S'iocNooLn' ( D I O U 3 M n n N N C 0 0 0 0 0 1 C O O - O N o ai I \u00C2\u00A9* / O ICS! 00 00 \u00E2\u0080\u0094 CO CM O O to \u00E2\u0080\u0094 CO i> co \u00E2\u0080\u0094 o O r^ to oo O o co cn a> > b DC < I CO Lu o _ J UJ > LxJ INDIVIDUAL PLOTS 254 Fig. 31. Dendrogram of the 131 Plots Obtained by the Weighted-Variable-Group Method of Cluster Analysis Plots are l i s t e d on the abcissa and the level of vegetation similarity in per cent i s shown on the ordinate. The sub-associations and associations described in Chapter IV are delimited and the degree of similarity between plots composing associations i s shown by the horizontal lines connecting the vertical plot lines. L E V E L OF SIMILARITY (96) 255 orders can be determined by the horizontal lines connecting the associations. These units are formed at much lower levels of similarity and are thus considered to be less homogeneous, which is to be expected, as they contain a greater diversity of habitats and species. In general the results obtained by the two clustering methods, as depicted in the dendrograms are similar. Clusters grouping communities or groups of communities to the level of associations are very similar i n both dendrograms. The only difference i s the level of similarity at which the association groups are f i n a l l y completed. In most instances, association clusters by the weighted-variable-group method are formed at levels of similarity ranging up to 4% higher than are corresponding clusters in the weighted-pair-group method. The greatest difference, however, between the two methods is the way in which the associations are clustered and thus the suggested relationships between associations. By the weighted-pair-group method (Fig. 30) the Agropyro -Balsamorhizetum sagittatae i s shown to be less similar to the Antennario - Poetum secundae than i s the Stipetum richardsonii. In contrast, by the weighted-variable-group method (Fig. 31) the Agropyro - Balsamorhizetum sagittatae i s shown to be directly related to the Antennario - Poetum secundae. Based on the environmental and f l o r i s t i c data given in Chapter IV and on the relationships between these associations in the f i e l d , t h e Agropyro-Balsamorhizetum sagittatae is considered to be more similar to the Antennario - Poetum secundae than i s the Stipetum richardsonii. Thus the arrangement presented in Fig. 31 (weighted-variable-group method) is most meaningful. A second example of differing association arangements between the two methods involves the associations of the Pseudotsugetalia menziesii and Piceetalia glaucae. By the weighted-pair-group method (Fig. 30) the Poo -Calamagrostido - Populetum tremuloidis i s grouped with associations of the 256 Pseudotsugetalia menziesii and the Rhytidiadelpho - Pleurozio - Pseudotsugetum \u00E2\u0080\u00A2glaucae i s grouped with associations of the Piceetalia glaucae. The resulting arrangement i s d i f f i c u l t to understand and interpret. However, in the weighted-variable-group method (Fig. 31) the placement of the Poo - Calamagrostido -Populetum tremuloidis and Rhytidiadelpho - Pleurozio - Pseudotsugetum *glaucae i s reversed and thus the orders Pseudotsugetalia menziesii and Piceetalia glaucae are easily distinguishable. This arrangement of associations i s considered to be the most meaningful phytosociologically and ecologically. Based on the data presented here, i t appears that the weighted-variable-group method provides a more satisfactory clustering arrangement of communities than does the weighted-pair-group method as association clusters are generally formed at higher levels of similarity and associations are grouped so as to show relationships which appear to be ecologically more correct. Sokal and Michner (1958) and Sokal and Sneath (1963) in their dis-cussion of the two methods elected the weighted-pair-group as being more desirable than the weighted-variable-group method. Their choice appears to be based on the assumption that clusters whether composed of several units (communities) or a single unit are independent entities and should thus be treated with equal importance. This i s probably defensible in numerical taxonomy where the main purpose i s to derive an arrangement of discrete taxonomic classes. In contrast, the purposes of most ecosystem studies are twofold\u00E2\u0080\u0094 (1) to provide a meaningful classification of communities and (2) to emphasize the f l o r i s t i c and environmental relationships between the cla s s i f i e d units. Thus for ecological studies the weighted-variable-group method i s considered to be superior because i t appears that by i t s mode of calculation, (the similarity indices of clusters are determined by a l l communities composing the clusters) a meaningful grouping of communities is found and the a f f i n i t y between clusters 257 i s emphasized. Relationship of Ecosystem Units on the Dendrogram obtained by the Weight- Variable-Group Method of Cluster Analysis (Fig. 31) The levels of similarity at which individual plots are paired are high, ranging from 64% to 92%. This indicates that sampled plots are similar in their f l o r i s t i c composition and can be regarded as representative of the association noda. The subjective grouping of plots into associations (Chapter IV) i s substantiated by the objective clustering of plots represented on the dendrogram, with two minor exceptions. Plot 037 was subjectively placed into the Poo - Elymetum cinerei but on the dendrogram i t i s clustered with the Antennario - Poetum secundae. These two associations intergrade under natural conditions and thus have many species in common. They are differentiated largely on the presence or absence of Elymus cinereus. On this basis plot 037 i s considered to belong to the Poo - Elymetum cinerei, however, perhaps more correctly, i t should be viewed as transitional between the Poo - Elymetum cinerei and the Antennario - Poetum secundae. The second exception concerns plots 069 and 070. Because of the dominance of Pinus contorta they were subjectively placed in the Calamagrostido -Pseudotsugetum *glaucae pinestosum contortae but based on quantitative f l o r i s t i c data objectively clustered with the Calamagrostido - Pseudotsugetum *glaucae calamagrostido - pseudotsugetosum *glaucae. However, the difference i s minor, since the pinetosum contortae i s considered as a successional stage of the calamagrostido - pseudotsugetosum *glaucae, transitional communities between the two subassociations are to be expected. Association clusters of communities are easily recognizable on the dendrogram and range in their levels of similarity from 40% to 80% with the majority of association groupings finalized at levels of similarity greater than 50%. The highest within-group similarities occurred in the f l o r i s t i c a l l y simple aquatic and semiterrestrial associations because 258 here much of the quantitative measure is made up by single dominant species of high significance. Similarity levels for these associations were: 79% for the Caricetum rostratae, 77% for the Carico - Salicetum monticolae and 80% for the Scirpetum v a l i d i . The within-group association similarities decreased as the complexity of vegetation increased. Thus f l o r i s t i c a l l y rich grassland and forest associations were frequently clustered at similarity levels between 50% and 60%. In general, the levels of similarity at which the associations are clustered i s high. Thus the associations represented on the dendrogram and described in Chapter IV are considered to represent very homogeneous groupings of f l o r i s t i c a l l y similar communities. The associations are clustered together at lower levels of similarity on the basis of their f l o r i s t i c relationships. On this basis the associations are divided into two physiognomic groups, distinguishable at the 20% level of similarity. Non-forested associations are related on the l e f t of the dendrogram and forested associations on the right. The relationships within these groups can be interpreted ecologically by assuming that the distribution of species i s controlled by environmental r causes\u00E2\u0080\u0094an assumption which is usually ecologically j u s t i f i a b l e . In the dendrog the associations appear to be related primarily along a moisture gradient. Starting in the centre of the figure, from the xeric Agropyro - Juniperetum and subxeric Arctostaphylo - Pseudotsugetum gradients of increasing moisture are implied. These terminate, for forest associations with the subhydric Equiseto -Piceetum and for non-forest associations with the hydric Caricetum rostratae. At lower levels of similarity i t i s possible to ecologically interpret the relationships between higher ecosystem units. For example at the 20% level of similarity i t is possible to recognize a climatic gradient between the warm valley associations of the Agropyrion spicati (placed i n the xeric part of the figure) and the cool upland associations of the Stipion columbinae (placed i n a 259 mesic position on the figure). There exist certain inherent disadvantages to two-dimensional models, such as the one used here. In such a model when a single environmental parameter (in this case moisture) appears to dominate the relationship between units, other often significant environmental relationships are masked and i t becomes d i f f i c u l t to obtain a complete ecosystematic understanding. Secondly, often vegetation units (associations) which are ecologically and spatially similar, are placed far apart because a l l units necessarily have to be linearly arranged. These disadvantages can really only be overcome sati s f a c t o r i l y by the use of multi-dimensional models. However, even with these inherent disadvantages, cluster analysis i s considered to be a very useful technique in ecosystematic studies. By this method i t i s possible to: (1) quantitatively substantiate ecosystematic classifications incorporating ecosystem units of varying degrees of generalization; (2) show the degree of homogeneity of the ecosystem units based on within group similarity and (3) interpret f l o r i s t i c and environmental relationships between the ecosystem units. 260 VIII THE RELATIONSHIP BETWEEN GRASSLAND AND FOREST VEGETATION Physiognomically, the associations of the Cariboo Zone can be grouped into two broad types\u00E2\u0080\u0094forest associations and grassland associations. The distributions of these types appears to be directly related to s o i l texture. Grassland associations are usually developed on fine textured soils in which coarse fragments (greater than 2mm in size) are generally absent whereas forest associations are developed on soils containing a high percentage of coarse fragments. This relationship between s o i l and vegetation i s believed to result from- the effect of s o i l texture on the av a i l a b i l i t y of s o i l moisture. Trees are deep rooting plants and thus for their growth i t i s essential that moisture be available well below the surface. Grasses, on the other hand, are shallow rooting plants and can survive in places where moisture i s available only near the surface. Generally speaking, coarse textured so i l s allow deep percolation of surface moisture and thus favour the growth of trees whereas fine textured soils tend to trap moisture near the surface and favour the growth of grasses. Once established, grasses w i l l tend to amplify the surface moisture retention due to their fibrous root system. Therefore, i f the grassland i s not disturbed entry by trees i s considered to be very d i f f i c u l t . This control of vegetation by s o i l texture applies only in semi-arid and subhumid regions where moisture i s supplied predominantly from the surface and i s often a limiting factor. This i s supported by the fact that in the Cariboo Zone on high water table habitats, where moisture i s not limiting and fine soils persist, tree growth i s excellent. The Equiseto - Piceetum glaucae i s an example of such a case. The present distribution of the vegetation and corresponding s o i l types can be summarized as follows. In upland regions the tops of h i l l s and ridges as well as water eroded gullies and stream valleys are forested, while the 261 exposed h i l l s i d e s and shallow valleys are under grassland cover. The major valleys are for the most part non-forested; trees occur along the crests of the valley sides and extend into the valleys in deep water eroded ravines, (see Fig. 1 and 2, page 9 ). The fine and coarse textured soils underlying the grass and forest associations in the study area appear to be formed on two geologically different parent materials. Because of this, the distribution of associations i s believed to have been hi s t o r i c a l l y determined. In the upland areas the fine textured soils are relatively shallow, ranging in thickness from 5\" to 12\" and are classed as aeolian deposits. However, in the major valleys the fine s o i l deposits are sometimes much deeper, ranging up to several feet. Here, the s o i l may be formed from a parent material of sediments as well as aeolian deposits. Underlying the aeolian deposits of the grassland i s the same coarse textured material, classed as gl a c i a l d r i f t , found under forest associations (Fig. 32). The distribution of the two parent materials i s believed to have been determined directly after the last glaciation. In the following discussion an hypothesis attempting to explain this distribution i s presented. During glaciation a mantle of gl a c i a l d r i f t i s believed to have been deposited over the entire region. Directly following retreat of the ice (approx. 10,000 years ago) the d r i f t would have been l a i d bare and not being stabilized by vegetation, easily eroded. According to F l i n t (1963) the climate following glaciation was dry with strong winds and s o i l movement by ai r was common. It i s , therefore, proposed that wind removed fine material from the exposed d r i f t on the ridges and deposited i t as loess on the slopes below, forming one type of the aeolian material. A second and probably more important type of aeolian material is believed to have been the Tertiary lacustrine s i l t deposits present along the Chilcotin River. Following glaciation they would have F i g . 32. A s o i l p r o f i l e c h a r a c t e r i s t i c of the grassland areas showing a parent material of f i n e textured aeolian material overlying g l a c i a l d r i f t . The s o i l p i c t u r e d i s developed under the Agropyretum s p i c a t i . 263 been exposed and parts of these deposits could easily have been moved, as loess, to the uplands resulting in the present aeolian layer. The continual ablation of ridges by wind because of their exposed position, i s thought to have resulted in the exposure of coarse material on which forest vegetation has become established. On the other hand, the continued aggradation of slopes by deposition of loess deposits is thought to have led to the establishment and survival of grasses. It i s believed that once the area was stabilized by vegetation the effect of wind was reduced and the forest-grassland boundaries were established. An exception, however, i s the present distribution of forest in gullies, which i s considered to have resulted from water erosion of areas originally colonized by grassland. Here, the fine surface material is thought to have been removed exposing the coarse gla c i a l d r i f t and thus making these areas more suitable for the establishment of forest. The general hypothesis of aeolian deposition over g l a c i a l d r i f t i s supported by the following points. 1) The consistent relationship of fine aeolian material over gla c i a l d r i f t indicates an i n i t i a l deposit of d r i f t and a later deposition of fine material. 2) Two sources of loess would have been available in the area after glaciation namely, exposed g l a c i a l d r i f t plains and Tertiary s i l t deposits along the river. 3) The fine surface material appears to be unsorted, thus suggesting wind deposition. 4) On aerial photographs longitudinal ridges oriented with the prevailing wind can be seen. These are common features of areas of aeolian deposition (Flint 1963) and tend to increase the effects of gully erosion. 5) The presence in the s o i l of soft, easily eroded minerals like serpentine strongly indicates that the fine soils are not a result of weathering in s i t u . 6) Boulder trains are a frequent geomorphic feature in the area, suggesting 264 an i n i t i a l deposition of gl a c i a l d r i f t and that the fine s o i l surrounding these boulders is a later deposit. 7) Texturally, the fine soils have a relatively high s i l t content and low clay content which i s characteristic of wind deposited material. The low content of clay reduces the p o s s i b i l i t y that the fine material i s of lacustrine origin. Similar observations on the relationships between grassland and forest vegetation have been made by researchers working in areas vegetationally similar to the Cariboo Zone. Spillsbury and Tisdale (1944) made a study on soil-plant relationships of the Tranquille Range, B.C., involving grassland and Douglas-fir forest. They mentioned b r i e f l y that the s o i l of the forest stands i s coarser than in the neighbouring grassland. Unfortunately they did not give the results of texture analysis of the soi l s other than to state that they are generally loams or sandy loams derived from g l a c i a l t i l l . Brayshaw (1955, 1965) showed that in low elevations of the Pinus Ponderosa Zone, where the climate i s semi-arid to subhumid, grassland associations are formed on fine textured soils ranging from loams to clays and the forest associations are formed on coarser textured s o i l s . He also showed that at higher elevations where the climate i s more moist and s o i l moisture i s not limiting, forest associations were found on coarse as well as fine textured s o i l s . These authors did not indicate, whether or not, the distribution of grassland and forest associations i s h i s t o r i c a l l y determined as i s suggested to be the case in the Cariboo Zone. Daubenmire (1942) in his study of the vegetation of semi-arid south-eastern Washington reported that the grasslands are developed on fine textured loessal material derived from basalt. He stated that the region has been non-forested since Pliocene time which is when the climate became arid and the loess originated. Daubenmire also reported that a l l the Pleistocene d r i f t of 265 the area bears a mantle of postglacial loess. The relationship between s o i l texture and grassland vegetation given by Daubenmire appears to correlate well with the s o i l vegetation relationships suggested in this study for the Cariboo Zone. The grassland-forest boundary has been oftened reported in the literature to be altered by f i r e and grazing. The effect of f i r e has been reported by many authors. Palli s e r (1863) reported the region near the Alberta-Saskatchewan border as old forest land with good s o i l , the forest having been destroyed by f i r e and the region now occupied by grassland with Poplar clumps. Dawson (1879) reported that the prairies of the Peace River have been produced and are maintained by f i r e . Moss (1932, 1952, 1953) and Moss and Campbell (1947) stated that in the parkland regions of Alberta, where fires have been prevented, woodland has often expanded at the expense of pr a i r i e . Tisdale (1950) reported that in the interior of British Columbia grassland is promoted and maintained by frequent burning. Similarly Brayshaw (1955)^ stated that shrubs and young trees are more susceptible to f i r e than are grasses and that burning induces an encroachment of grassy vegetation into areas formerly occupied by woody plants. Grazing has been reported frequently as a factor favouring the expansion of forest into grassland areas. Moss (1932) reported that in Alberta parkland, where grazing i s severe, Populus tremuloides tends to advance into the grassland. Tisdale (1950) noted that in the interior of British Columbia heavy grazing promotes the establishment of Pseudotsuga menziesii in grassland areas. Similarly, Brayshaw (1955) reported that because of heavy grazing shrubs and trees invade the Agropyron grassland i n southern British Columbia. In central Washington a positive correlation between the reproduction of Pinus ponderosa and heavy grazing was reported by Rummell (1951). He concluded that overgrazing is more important in fostering the successful establishment of young 266 trees than freedom from f i r e . At the present time the southern subzone of the Cariboo Zone i s largely protected from f i r e and parts of i t are heavily grazed. As a result, in some areas the advancement of trees into the grassland i s occurring. This i s particularly noticeable in heavily grazed associations of the Stipion columbianae. Here, young trees of Pinus contorta and Pseudotsuga menziesii become established in large numbers and appear to survive well for a few years. However, they then suffer a high mortality which results in the forest-grassland boundary returning to i t s former position. The explanation of this fluctuation i s thought to be related to s o i l moisture. It i s believed that tree seedlings are established on the fine textured grassland so i l s during seasons when moisture i s not limiting and survive only u n t i l the f i r s t severe summer drought at which time they succumb. At the present time the grassland-forest boundary in the area studied is considered to be relatively stable and to be controlled by available s o i l moisture as related to s o i l texture. However, i t i s apparent that temporary fluctuations of the boundary occur. In this area these are largely a result of reduced competition between grasses and trees as a result of grazing. The ultimate successional pattern of grassland and forest associations i s dealt with in detail in the following chapter. 267 IX ECOLOGICAL RELATIONSHIPS OF THE ASSOCIATIONS In previous chapters, ecosystem units, synthesized from analytical data, have been described and discussed. Under natural conditions these units are united into a vegetation-environment complex which i s visualized to be dynamic, varying continuously in space and constantly in time. In this chapter the ecological relationships of the associations are presented in an attempt to synthesize the vegetation-environment complex which i s representative of the broader biogeoclimatic concept of the Cariboo Zone. The presentation i s divided into two sections\u00E2\u0080\u0094the f i r s t deals with spatial relationships of the associations and the second with the successional relationships. Such a division of the space-time continuum i s arbitrary and made only for convenience. Spatial Relationships Topographic Sequence of Forest Associations Present in the Area North of Williams Lake The area north of Williams Lake i s forested and consists largely of associations belonging to the Pseudotsugetalia menziesii. Associations cla s s i f i e d in the Piceetalia glaucae are present only in locally very moist habitats. Fig. 33 and 34 shows schematically, the topographic relationships among the common forest associations. The distribution of associations on sandy outwash soils (Fig. 33) appears to be largely determined by topography. The Arctostaphylo - Junipero -Pseudotsugetum *glaucae i s developed on benches or slopes with southerly exposures. Because of i t s exposed position, on rapidly drained s o i l s , i t i s the driest forest association and is rated as subxeric. Trophically, i t i s the poorest association partly because the sandy parent material has an inherently low nutrient level and partly because the rapid drainage results in leaching out of the nutrients. It i s considered to be submesotrophic to oligotrophic. Fig. 33. Topographic Sequence of Forest Associations Developed on Sandy Outwash Deposits. Arctostaphylo - Junipero -Pseudotsugetum *glaucae Calamagrostido - Pseudotsugetum *glaucae Rhytidiadelpho - Pleurozio -Pseudotsugetum *glaucae to cn co 269 In shallow gullies or on northerly exposures the Junipero - /Arctostaphylo -Pseudotsugetum *glaucae grades into the Calamagrostido - Pseudotsugetum *glaucae. This association, largely due to seepage, i s more moist and i s rated as submesic. At the base of the outwash slopes in deep water formed gullies the Arctostaphylo - Junipero - Pseudotsugetum *glaucae gives way to the Rhytidiadelpho -Pleurozio - Pseudotsugetum *glaucae. Here, the hygrotope i s increased up to subhygric because of seepage from the slopes above. Nutritionally, this habitat i s richer than those above, because of a constant supply of nutrients with the seepage water. The boundaries between these three associations are generally abrupt and can be seen by the change in f l o r i s t i c structure as well as by the change in the vigor of the trees. The Arctostaphylo - Junipero - Pseudotsugetum *glaucae i s environmentally and f l o r i s t i c a l l y dissimilar from the other two. This can readily be seen on the dendrogram (Fig. 31) as i t i s joined into the Pseudotsugetalia menziesii cluster at a low similarity level of 32%. On g l a c i a l d r i f t s o i l s , with a matrix composed largely of clay and s i l t sized particles (Fig. 34) the Arctostaphylo - Junipero - Pseudotsugetum *glaucae does not develop because the habitats are maintained at a higher moisture content. On this parent material the Calamagrostido - Pseudotsugetum *glaucae covers the largest area and i s present on ridges, gentle slopes of a l l exposures and on level benches. The association i s represented only by t n e subassociation, calamagrostido - pseudotsugetosum *glaucae in the area north of Williams Lake, as Pseudotsuga menziesii appears to be able to colonize new areas in this dry region and thus form successional as well as climax stands. On slopes covered by g l a c i a l d r i f t with steep gradients (17\u00C2\u00B0 to 25\u00C2\u00B0) and frequently northerly exposures the Calamagrostido - Pseudotsugetum *glaucae grades into the Rhytidiadelpho - Pleurozio - Pseudotsugetum *glaucae. Because of Fig. 34. Topographic Sequence of Forest Associations Developed on Gracial Drift (with a clay matrix) tremuloidis 3. Rhytidiadelpho - Pleurozio -Pseudotsugetum *glaucae o 271 i t s topographic position this association appears to benefit from seepage and greater snow accumulation. Therefore, i t i s moister than the Calamagrostido -Pseudotsugetum *glaucae and is considered to be subhygric. Trophically, the two associations are similar and both are rated as permesotrophic. F l o r i s t i c a l l y , they are the most similar associations in the order Pseudotsugetalia menziesii and are grouped on the dendrogram at the 38% level of similarity (Fig. 31). In this forested region, through the influence of topography and s o i l texture associations of the Piceetalia glaucae may become locally important. The Poo - Calamagrostido - Populetum tremuloidis i s formed on fine textured soils in depressions or gullies with temporary to permanent seepage. These gullies are bordered by associations of the Pseudotsugetalia menziesii. Occasionally, on north facing slopes which are influenced by cold a i r drainage and late snow, truly boreal associations like the Pleurozio - Vaccinio -Piceetum *glaucae develop. In this area, this association i s dependent on fine textured s o i l s , like alluvium, which have a high moisture retention c a b i b i l i t y . It i s bordered by communities of the Rhytidiadelpho - Pleurozio - Pseudotsugetum *glaucae which are formed on glacial d r i f t and are located in areas less affected by cold a i r drainage. Topographic Sequence of Associations Present in Major Valleys of the Fraser Plateau In Fig. 35 the topographic relationships of the associations of the major valleys of the Fraser Plateau are schematically diagrammed on a north-south transect. On the tops of the valley slopes at elevations over 2500 feet the Calamagrostido - Pseudotsugetum *glaucae i s developed on coarse glacial d r i f t s o i l s . The climate here, is cool and during the summer of 1968 temperatures measured in the Calamagrostido - Pseudotsugetum *glaucae were consistently lower than those in the valley below. Below the Calamagrostido - Pseudotsugetum *glaucae a forest-grassland Fig. 35. Topographic Sequence of the Associations Present in the Major Valleys of the Fraser Plateau Parent materials from which the soils of the associations are formed are coded as follows: G.D. - glacial d r i f t ; A.G. - aeolian deposit over gla c i a l d r i f t ; A.D. - aeolian deposit. 1. 2. 3. 4. 5. Calamagrostido - Pseudotsugetum *glaucae \"Agropyro - Pseudotsugetum *glaucae\" Agropyretum spicati Agropyro - Artemisietum tridentatae Opuntio - Stipetum comatae north 273 transitional community i s present. Here, Pseudotsuga menziesii occurs in more open stands and the understory changes f l o r i s t i c a l l y . Calamagrostis rubescens i s replaced by Agropyron spicatum as the dominant species. Similarly, other forest species decrease in importance in favour of open grassland species. This f l o r i s t i c change corresponds to a decreasing coarseness of the texture of the surface s o i l and a warmer microclimate. These soils are richer and drier than those of the forest sites above. This community was not described as an association because of i t s obvious transitional nature. However, plot 060, c l a s s i f i e d with the Agropyretum spicati, closely resembles this transitional type. The transitional \"Agropyro - Pseudotsugetum *glaucae\" extends well into the major valleys at the bottom of water-cut ravines (Fig. 36) where the coarse s o i l i s exposed and more moisture i s available. An association similar to the \"Agropyro - Pseudotsugetum *glaucae\" was described by Brayshaw (1955). Below the \"Agropyro - Pseudotsugetum *glaucae\" on the exposed slopes as well as on the sides of water cut ravines, the Agropyretum spicati i s present. The slopes on which i t reaches i t s best development are generally very steep and range up to 43\u00C2\u00B0. The s o i l i s chernozemic and is formed from fine aeolian deposits although some coarse fragments may be present in the lower horizons. This association i s considered to be eutrophic and xeric. At lower elevations near the bottoms of the valleys on gently sloping terraces the Agropyretum spicati i s replaced by the Agropyro - Artemsietum tridentatae. Here, the s o i l i s regosolic, formed from fine textured parent material which i s three to four feet deep. The clay content i s higher than in the neighbouring Agropyretum spicati and coarse fragments are absent from the pr o f i l e . The greater depth of fine s o i l here, may be a result of the deposition by wind of s o i l from the slopes above. This habitat like that of the Agropyretum spicati i s eutrophic and xeric. The very xeric Opuntio - Stipetum comatae i s developed near the bottoms F i g . 36. A deep water-cut ravine i n the C h i l c o t i n V a l l e y i n which Pseudotsuga menziesii i s present because of the coarser s o i l and more a v a i l a b l e s o i l moisture. The e r o s i o n a l force of runoff water i s evident from the sharply cut channel sides and uprooted plants of Artemisia t r i d e n t a t a . 275 of the major valleys on gently sloping (2\u00C2\u00B0 to 13\u00C2\u00B0) terraces with southerly exposures. These terraces are located at the base of steep valley slopes on which the Opuntio - Stipetum comatae i s replaced by the Agropyretum spicati. The Opuntio - Stipetum comatae i s absent from steep slopes, most li k e l y because of i t s i n a b i l i t y to tolerate surface runoff and water erosion such as that occurring the spring and following summer \"cloud bursts\". On such habitats only plants like Agropyron spicatum with growth forms that tend to stabilize the s o i l surface against erosion appear to be successful. The Opuntio - Stipetum comatae appears to benefit from deposition of fine material resulting from wind and water erosion of the steep slopes above. The resulting soils are fine textured Regosols or Rego-Chernozems, although coarse fragments may be present in the lower horizons. The topographic relationships between the Agropyretum spicati and the Opuntio - Stipetum comatae are shown in Fig. 37. The Agropyretum spicati i s present on northerly steep slopes of ravines where surface runoff and erosion are maximum. The Opuntio - Stipetum comatae occurs on gently sloping terraces, dissected by ravines where the surface runoff i s minimal and deposition rather than erosion occurs. Because of i t s topographic position and exposure the Agropyretum spicati i s considered to be more moist and to have a cooler micro-climate than that of the Stipetum comatae. The effect of exposure i s i l l u s t r a t e d in Fig. 38 where the Agropyretum spicati i s s t i l l snow covered while the Opuntio -Stipetum comatae and southerly exposed ravine slopes are snow free. These southerly slopes support a community resembling the Agropyro - Artemisietum tridentatae. The fourth association of the major valleys i s the Agropyro - Juniperetum scopulorum. It i s present only on steep slopes which are being actively eroded by wind and water. The soils are regosolic and due to the constant erosion of fine material coarse s o i l i s exposed on which Pseudotsuga menziesii i s established. 276 Fig. 37. The topographic relationship between the Opuntio -Stipetum comatae which is developed on the level terraces and the Agropyretum spicati which i s developed on the northerly ravine sides. This topographic sequence of associations is common in the major valleys of the Fraser Plateau where water-cut ravines have dissected the sloping terraces. The extension of Pseudotsuga menziesii into the valley at the bottom of the ravines can also be seen. Fig. 38. An i l l u s t r a t i o n of the effect of exposure on the development of associations in the Chilcotin Valley. The Agropyretum spicati (developed on the north facing ravine slopes) i s s t i l l snow covered while the Opuntio - Stipetum comatae (developed on sloping terraces at the top of the ravines) and southerly exposed ravine slopes are snow free. 277 The f l o r i s t i c relationships of the four valley associations (Agropyrion spicati) i s shown on the dendrogram (Fig. 31). The Agropyretum spicati and the Agropyro - Artemisietum tridentatae are the most similar, being grouped together at the 45% level of similarity. These two associations intergrade but reach their respective optima on ecologically different habitats. The Opuntio - Stipetum comatae which has been shown to be ecologically different i s grouped with the Agropyretum spicati and the Agropyro - Artemisietum tridentatae at the 39% level of similarity. The Agropyro - Juniperetum scopulorum which i s present on the most unstable sites i s grouped with the other three associations at the 32% level of similarity. Topographic Sequence of the Associations Present in Upland Areas of the Fraser Plateau The topographic sequence of associations occurring i n the climatically cool upland regions of the Fraser Plateau i s ill u s t r a t e d diagramatically in Fig. 39. The Calamagrostido - Pseudotsugetum *glaucae i s developed on the ridge tops on g l a c i a l d r i f t in which coarse fragments are common. It is represented by either the pinetosum contortae i f recently established or the calamagrostido -pseudotsugetosum *glaucae i f i t i s in climax condition. The permesotrophic to eutrophic Stipetum richardsonii develops on the edge of grassland slopes and borders the Calamagrostido - Pseudotsugetum *glaucae. In this habitat the surface s o i l i s of a finer texture than the coarse g l a c i a l d r i f t under the forest and i s thought to represent thin aeolian deposits. However, coarse fragments are occasionally present near the surface and the subsurface s o i l i s coarse textured. This association i s cooler and moister than either the Antennario - Poetum secundae or the Calamagrostido - Pseudotsugetum *glaucae which border i t largely because of a \"frost pocket phenomenon\" and a greater accumulation of snow. Hygrotopically, this association i s considered to Fig. 39. Topographic Sequence of the Associations Present i n the Upland Areas of the Fraser Plateau Parent materials from which the soils of the associations are formed are coded as follows: G.D. - gla c i a l d r i f t ; A.G. - aeolian deposit over gla c i a l d r i f t ; A. - alluvium. r4 4 2 A.G. 3 A.G. 2 A.G. 1 D. 5 A. 4 A.G. 3 A.G. 1. 2. 3. 4. 5. 6. Legend Calamagrostido - Pseudotsugetum *glaucae Stipetum richardsonii Antennario - Poetum secundae antennario -poetosum secundae Antennario - Poetum secundae juncetosum b a l t i c i Poo - Elymetum cinerei Poo - Calamagrostido - Populetum tremuloidis lonicero - caricetosum leptopodae Equiseto - Piceetum glaucae to co 279 vary from subhygric, in the spring, to submesic for most of the growing season. The Stipetum richardsonii has a greater f l o r i s t i c similarity to the grassland associations of the Stipion columbianae than to the forest associations. It i s grouped with other grassland associations at the 36% level of similarity on the dendrogram Fig. 31. The permesotrophic to eutrophic Antennario - Poetum secundae antennario - poetosum secundae is developed on exposed slopes and borders the Stipetum richardsonii. It i s drier than the Stipetum richardsonii being rated as xeric, largely because of higher evaporation from the exposed s o i l surface. Also this association does not benefit from deep snow accumulation. The surface s o i l i s fine textured with only occasional coarse fragments and overlies g l a c i a l d r i f t . The Antennario - Poetum secundae grades into the Stipetum richardsonii in shallow gullies extending down the exposed slopes. These gullies appear to have a higher amount of available moisture which i s thought to be the major factor controlling the distribution of the two communities. The boundary between the two as represented by species composition i s abrupt. The low f l o r i s t i c similarity between the Stipetum richardsonii and the Antennario -Poetum secundae i s apparent on the dendrogram (Fig. 31) as these associations are not directly linked. The Antennario - Poetum secundae antennario poetosum secundae grades into the moister, submesic, Antennario - Poetum secundae juncetosum b a l i t i c i at the base of exposed slopes. The juncetosum b a l t i c i appears to benefit from temporary seepage and runoff from the slopes above. F l o r i s t i c a l l y the two sub-associations are very similar and are united at the 54% level of similarity on the dendrogram (Fig. 31). Where exposed slopes border on old stream terraces the Antennario -Poetum secundae may grade into the submesic Poo - Elymetum cinerei. The soils 1 G.D. Fig. 40. Topographic Relationships of the Calamagrostido -Pseudotsugetum *glaucae pinetosum contortae (1), the Stipetum richardsonii (2), and the Antennario -Poetum secundae (3). Parent materials from which the soils of the associations are formed are coded as follows: G.D. - gla c i a l d r i f t ; A.G. - aeolian deposit over gla c i a l d r i f t . 281 here, are formed from a parent material of alluvium and are eutrophic. The Poo - Calamagrostido - Populetum tremuloidis lonicero - caricetosum leptopodae frequently borders, the Poo - Elymetum cinerei on stream terraces but i s formed at a lower r e l i e f position. Thus i t has a higher water table and i s hygric to subhydric. The Equiseto - Piceetum glaucae develops on recent alluvium on stream terraces and often borders the Poo - Calamagrostido - Populetum tremuloidis lonicero - caricetosum leptopodae. However, because of i t s proximity to streams the Equiseto - Piceetum glaucae i s moister being rated as hygric to subhydric. A frequently observed topographic sequence between the Antennario -Poetum secundae, Stipetum richardsonii and Calamagrostido - Pseudotsugetum *glaucae i s diagramed in Fig. 40. The Antennario - Poetum secundae develops on fine textured soils on xeric ridge tops. The Stipetum richardsonii develops on wind protected slopes below the Antennario - Poetum secundae. It is submesic and benefits from temporary seepage. Here, the microclimate i s cooler as a result of cold a i r drainage. Below the Stipetum richardsonii the Calamagrostido - Pseudotsugetum *glaucae i s developed in water cut gullies. Here, fine textured s o i l has been eroded away, exposing coarse gla c i a l d r i f t . This association benefits from seepage and runoff concentrated in the gullies and i s rated as mesic. Topographic Sequence of the Associations of Saline-alkaline Habitats In Fig. 41 the topographic sequence of associations developed around alkaline ponds i s shown. The Scirpetum v a l i d i i s formed in the ponds which have no drainage outlets. They are continually enriched by salts moved in by runoff and seepage from the surrounding slopes. The s o i l surface is only rarely exposed and thus the hygrotope is considered as hydric. 282 F i g . 41. Topographic Sequence of the Associations Present i n S a l i n e - A l k a l i n e Habitats. This sequence of associations corresponds to a gradient of decreasing moisture. Note the abrupt community boundaries. Legend 1. Antennario - Poetum secundae 2. D i s t i c h l o - Spartinetum g r a c i l i s 3. P u c c i n e l l i o - Hordeetum j u b a t i 4. Scirpetum v a l i d i 283 The Puccinellio - Hordeetum jubati i s formed on the edges of these ponds and borders the Scirpetum v a l i d i . This association i s drier than the Scirpetum v a l i d i being flooded only in the spring and i s considered to be hygric. The Distichlo - Spartinetum g r a c i l i s develops above the Puccinellio -Hordeetum jubati on gentle slopes with gradients ranging from 2\u00C2\u00B0 to 5\u00C2\u00B0. The s o i l drainage i s improved over that of the Puccinellio - Hordeetum jubati and Distichlo, - Spartinetum g r a c i l i s i s flooded only rarely. Thus i t occupies a drier habitat and i s rated as subhygric. The three associations of this sequence have high salt concentrations and are considered as hypereutrophic. F l o r i s t i c a l l y the Distichlo - Spartinetum g r a c i l i s and the Puccinellio -Hordeetum jubati are very similar. On the dendrogram (Fig. 31) they are united at the 39% level of similarity. The Scirpetum v a l i d i , however, is shown to be quite distinct as i t i s joined to the other two at a similarity of only 8%. On the exposed slopes above the Spartinetum g r a c i l i s , communities of the Antennario - Poetum secundae are developed. The boundary between these two associations i s very distinct and appears to coincide with the maximum level that flood waters ever reach. Topographic Sequence of the Associations Formed in Glacial Stream Depressions The topographic relationships of associations formed in g l a c i a l stream depressions and their relationship to associations of upland habitats is shown in Fig. 42. In the well drained fresh water lakes the Caricetum rostratae i s developed. It i s constantly submerged and thus considered to be hydric. The Carico - Salicetum monticolae is formed around the edges of the lakes and borders the Caricetum rostratae but i s a few feet higher in r e l i e f . Topographic Sequence of the Associations Formed in Glacial Stream Depressions and their Relationship to Associations of Upland Habitats. Parent materials from which the soils of the associations are formed are coded as follows: G.D. - gla c i a l d r i f t ; A.G. - aeolian deposit over glacial d r i f t ; S. - Sediments (lacustrine or f l u v i a l ) . Legend 1. Calamagrostido - Pseudotsugetum *glaucae 2. Antennario - Poetum secundae antennario - poetosum secundae 3. Antennario - Poetum secundae juncetosum b a l t i c i 4. Muhlenbergio - Betuletum glandulosae 5. Carico - Piceetum glaucae 6. Carico - Salicetum monticolae 7. Caricetum rostratae 285 It i s drier than the Caricetum rostratae and i s a semi-terrestrial association. This association i s flooded annually but during the summer the water level recedes to below the s o i l surface. Thus the hygrotope of the Carico -Salicetum monticolae is hydric - hygric. F l o r i s t i c a l l y the Caricetum rostratae and Carico - Salicetum monticolae are similar. This i s illustrated on the dendrogram (Fig. 31) where they are joined at the 50% level of similarity. The Muhlenbergio - Betuletum glandulosae often borders the Carico -Salicetum monticolae. It i s developed on alluvium at higher r e l i e f positions and i s t e r r e s t r i a l . The hygrotope of this association varies from hygric to subhydric and occasionally up to hydric. The boundary between the Muhlenbergio - Betuletum glandulosae and the Carico - Salicetum monticolae i s very distinct and corresponds to the abrupt change in r e l i e f and parent material. Frequently on exposed slopes above the Muhlenbergio - Betuletum glandulosae the Antennario - Poetum secundae i s developed. Physiognomically the boundary between the two associations i s distinct and follows the distribution of Betula glandulosa which i s believed to be partly controlled by cold a i r drainage and the accumulation of snow. The Carico - Piceetum glaucae i s also found in stream depressions and like the Muhlenbergio - Betuletum glandulosae, i t s development appears to be influenced by cold a i r drainage. When present i t occupies a habitat which i s topographically lower than the Muhlenbergio - Betuletum glandulosae and is located next to the Carico - Salicetum monticolae. The drainage here i s poorer than in the Muhlenbergio - Betuletum glandulosae and the hygrotope varies from hydric to hygric. F l o r i s t i c a l l y the Carico - Piceetum glaucae and the Muhlenbergio -Betuletum glandulosae have many species in common which reflects the similarity of their habitats. However, because of the quantitative differences 286 of the common species and the influence of exclusive species, the two associations are placed far apart on the dendrogram (Fig. 31). They are linked indirectly at only the 11% level of similarity. Successional Relationships The concept of vegetation change with time corresponding to changes in habitat factors i s fundamental to plant ecology. Such changes can best be documented by long term observations (Cooper 1928). Since long term observations are not available for the Cariboo Zone, in this discussion successional changes to stable climax communities are inferred from the interpretation of data available on existing plant associations. For the purpose of this discussion an association i s considered to be climax i f i t appears to be self-regenerating and i f there i s no evidence that i t w i l l be followed by a different association. Such associations are regarded to be in dynamic equilibrium with contemporary habitat factors. Associations which do not meet these requirements are referred to as successional. The classification of climax associations used in this discussion follows that outlined by Daubenmire (1952) and modified by Krajina (1965) . Associations which are characteristic of undulating topography and have loamy moderately drained soils are called the climatic climax (Tansley 1935). These are considered to be the f i n a l result of vegetation and habitat succession that the climate of the region w i l l permit (i.e. they are believed to be controlled by climate alone). Within the same climatic region, associations which d i f f e r from the climatic climax because of important s o i l characteristics are called edaphic climaxes. Similarly, those that d i f f e r because of the influence of topography are referred to as topographic climaxes. Each biogeoclimatic subzone i s characterized by a single climatic climax association which i s regarded as the zonal association occurring on the zonal habitat (Krajina 1965). However, within the same biogeoclimatic subzone 287 interzonal, intrazonal and azonal habitats are present; the stable communities on these habitats are edaphic or topographic climax associations. In the southern subzone of the Cariboo Zone the Agropyretum spicati is believed to be the climatic climax association. A l l other associations described, either successional or climax, are considered to be evolving toward this climatic climax. In proposing this monoclimax concept i t i s assumed that ultimate peneplanation of the land surface to one of gently undulating topography and the ultimate weathering of the s o i l to one of fine texture w i l l occur without significant change in the subhumid climate. It i s recognized, however, that most stable associations in the Cariboo Zone w i l l continue to exist in their present climax form for many hundred years to come. The f i n a l successional stages to the climatic climax, Agropyretum spicati, w i l l occur very slowly and w i l l require time, measured in many tens of thousands of years to be completed. In Fig. 43 the successional relationships between the subassociations and associations described for the southern subzone of the Cariboo Zone are diagrammatically presented. In the discussion to follow proposed successional changes are developed entirely on the basis of presently existing associations. No consideration has been given to the po s s i b i l i t y of future associations being developed that are different than those now present. Also, no attempt has been made to reconstruct h i s t o r i c a l vegetation changes from the time of glaciation up to the present. Thus the arrows in the diagram from \"Terrae Novae\" to the associations, indicate only the substrate on which the associations develop. None of the associations, with the possible exception of the Caricetum rostratae and the Scirpetum v a l i d i , are regarded as i n i t i a l stages of primary successions in newly formed habitats. In the discussion, comparisons are made to associations of similar status previously described from vegetationally related areas. F i g . 43 Proposed Successional Relationships of the Associations and Subassociations Described for the Cariboo Zone (Boxed associations are stable edaphic or topographic climaxes) Terrae Novae aeolian deposit aeolian deposit over g l a c i a l d r i f t aeolian deposit over g l a c i a l d r i f t Agropyro -Artemisietum tridentatae Climatic Climax Agropyretum s p i c a t i Opuntio -Stipetum comatae Agropyro -Balsamorhizetum sagittatae Antennario -Poetum secundae -t-1 t r Agropyro - Juniperetum scopulorum \"Agropyro - Pseudotsugetum *glaucae\" L r Arctostapyhlo - Junipero -Pseudotsugetum *glaucae C. - P.*g calamagrostido - pseudotsugetosum *glaucae Stipetum r i c h a r d s o n i i 1 D i s t i c h l o -Spartinetum g r a c i l i s Carico - Piceetum glaucae t P u c c i n e l l i o -Hordeetum j u b a t i t Scirpetum v a l i d i t undrained lakes Muhlenbergio -Betuletum glandulosae t Carico -Salicetum monticolae t ' Caricetum rostratae t drained lakes C. - P.*g ^_ ->\u00E2\u0080\u00A2 pinetosum contortae Rhytidiadelpho - Pleurozio Pseudotsugetum *glaucae P. - C. - P.t. poo - calmagrostido - <-populetosum tremuloidis P. - C.1 - P.t. lonicero - caricetosum leptopodae Poo - Elymetum c i n e r e i sediments Equiseto \u00E2\u0080\u0094 Piceetum glaucae Terrae Novae alluvium Terrae Novae aeolian deposit over g l a c i a l d r i f t sandy outwash g l a c i a l d r i f t CO CO 289 Successional Relationships of Associations Formed Primarily on Aeolian Deposits or Aeolian Deposits over Glacial Drif t The Agropyretum spicati develops in the major valleys which are climatically warmer than the surrounding uplands. It occurs on ridges and slopes in habitats that have medium textured soils c l a s s i f i e d as loams to sandy loams. These soils are developed as Brown Chernozems. The topography occupied by the Agropyretum spicati i s similar to that visualized to be the f i n a l product of peneplanation of the land surface. The so i l s of this association are similar in texture and genetic development to those visualized as the f i n a l product of weathering under the existing subhumid climate. For these reasons, the Agropyretum spicati, i s considered to occupy habitats most in equilibrium with the climate and i s named as the climatic climax association for the southern subzone of the Cariboo Zone. The Agropyro - Artemisietum tridentatae i s developed near the bottoms of the major valleys on gently sloping terraces. The so i l s on these terraces are very deep fine textured Regosols with a high clay content. Deposition of s o i l as a result of erosion from the steep slopes above the terraces appears to be operational here. In this habitat the Agropyro - Artemisietum tridentatae i s considered to be an edaphic climax association. Artemisia tridentata has been l i s t e d by Daubenmire (1942) and Ellison (1960) as a climax species. Daubenmire (1942) described an association dominated by Artemisia tridentata and Agropyron spicatum as the climatic climax association of the Agropyron - Artemisia Zone of central Washington. He did not, however, describe a separate Agropyron association in the same zone. Tisdale (1947) provided a similar treatment of his lower grassland zone in British Columbia. This arrangement appears not to be applicable on the Fraser Plateau as the Agropyretum spicati and the Agropyro - Artemisietum tridentatae are ecologically distinct. Daubenmire (1942) did describe an association dominated by Agropyron 290 spicatum as a climatic climax association but of the Agropyron - Poa zone in Washington and Tisdale (1947) described a similar association in his middle grassland zone of British Columbia. These associations, however, appear to be most similar to the Antennario - Poetum secundae of this study which i s formed in upland areas. The Opuntio - Stipetum comatae i s formed at low elevations on gently sloping terraces, with southerly exposures and fine textured regosolic s o i l s . These terraces are located at the base of steep slopes and deposition of s o i l as a result of erosion of the slopes appears to be maintain the soi l s as Regosols. In these habitats the Opuntio - Stipetum comatae i s considered to be an edaphic climax association. Similar edaphic climax associations were described by Daubenmire (1942) in central Washington and by Tisdale (1947) in the Kamloops area of British Columbia. Both the Opuntio - Stipetum comatae and the Agropyro - Artemisietum tridentatae are believed to be long persisting climaxes in the Cariboo Zone. However, ultimately their gently sloping habitats w i l l l i k e l y be changed into undulating topography as a result of erosion of the steep valley slopes during the peneplanation process. At the termination of this process s o i l deposition as a result of erosion would cease and the soi l s would begin to evolve from Regosols to Chernozems. Under these conditions the growth of Agropyron spicatum would be favoured over that of either Stipa comata or Artemisia tridentata and succession to the climatic climax, Agropyretum spicati would be complete. At the present time, however, the successional relationships of these three associations are being altered as a result of grazing. On gentle slopes occupied by the Agropyretum spica t i , Stipa comata i s replacing Agropyron spicatum as the dominant species and thus the Opuntio -Stipetum comatae i s increasing in distribution. Similar observations on the replacement of Agropyron spicatum by Stipa comata as a result of grazing have 291 been made by Spillsbury and Tisdale (1944) , Tisdale (1947), Brayshaw (1955) and McLean and Marchand (1964). Artemisia tridentata i s replacing Agropyron spicatum as the dominant species in the Agropyretum spicati on the lower slopes of the major valleys. The advancement of Artemisia tridentata as a result of the removal of Agropyron spicatum by grazing has been noted by many authors (Pickford 1932; Cottam and Stewart 1940, Shantz and Piemeisel 1940, Spillsbury and Tisdale 1944, Tisdale 1947, Brayshaw 1955, McLean and Marchand 1964). Communities of the Opuntio - Stipetum comatae and Agropyro - Artemisietum tridentatae which have developed as a result of grazing can usually be recognized from the s o i l p r o f i l e . Under these communities the s o i l has chernozemic characteristics rather than regosolic characteristics as i t was developed originally under the Agropyretum spic a t i . Primarily, as a result of grazing, well developed communities of the climatic climax Agropyretum spicati are being restricted to steep northerly slopes on which Artemisia tridentata i s established with d i f f i c u l t y and on which Stipa comata i s not established because the habitats are not xeric enough and have too great a surface runoff. However, with reduction in grazing pressure, Agropyron spicatum w i l l regain i t s former dominance (Tisdale 1947). The Agropyro - Juniperetum scopulorum occurs in the major valleys on steep slopes which are actively being eroded by water and wind. The soils of this association are regosolic and because of the erosion of fine material some coarse fragments are exposed. It i s considered to be a successional association which w i l l change into the forest-grassland transitional \"Agropyro - Pseudotsugetum *glaucae\". This change w i l l occur through the stabilization of the s o i l surface b v Agropyron spicatum. Successionally, the \"Agropyro - Pseudotsugetum *glaucae\" i s thought to advance to the climatic climax, Agropyretum sp i c a t i , due to further 292 weathering of the s o i l which w i l l result in fine s o i l s of considerable depth. On such fine textured s o i l s , in the subhumid climate, trees would be eliminated in favour of grassland species. The Antennario - Poetum secundae i s widespread in the upland areas of the Fraser Plateau and i s considered to be a topographic climax. It i s represented by the juncetosum b a l t i c i in moist depressions and at the bottom of seepage slopes and by the antennario - poetosum secundae on exposed slopes. Both of these subassociations appear to be climax in their respective habitats. However, the juncetosum b a l t i c i w i l l probably, eventually change into the antennario - poetosum secundae as a result of the disappearance of depressions through erosion and deposition. The Antennario - Poetum secundae appears to be stable and i n dynamic equilibrium with a l l habitat factors. Thus i t w i l l persist i n i t s present form u n t i l the forces of peneplanation and ultimate s o i l weathering become dominant. However, local fluctuations in the structure of this association as a result of grazing are common. Overgrazing results in a reduction in importance of species like Agropyron spicatum, Festuca saximontana and Koeleria g r a c i l i s and the increase in importance of species like Stipa columbiana. Antennaria spp., Artemisia fr i g i d a and Cerastium arvense. Daubenmire (1940) in Washington and Tisdale (1947) in British Columbia, recognized a community dominated by Poa secunda and Stipa columbiana to be formed as a result of overgrazing. However, based on personal observations and the research of Tisdale (1947) , i t i s apparent that by reduction in grazing pressure the structure of the community w i l l return to i t s original form. Locally, by gully erosion, near the forest-grassland border, the Antennario - Poetum secundae may be changed into communities of the Stipetum richardsonii. Similarly, i t may be changed into communities of the Agropyro -Balsamorhizetum sagittatae, as Balsamorhiza sagittata appears to be dependent 293 on the higher moisture available through the concentration of runoff and seepage in gullies. The occasional grass f i r e may also be an important factor in the successional change to the Agropyro - Balsamorhizetum sagittatae as Balsamorhiza sagittata has been reported to be promoted by burning (Brayshaw 1955). However, in the Cariboo Zone the effect of f i r e on this association i s considered to be minimum and the Agropyro - Balsamorhizetum sagittatae appears to be an edapho-topographic climax association in gullies where the hygrotope i s submesic and the soils contain a high percentage of sand. Similarly, Tisdale (1947) observed that Balsamorhiza sagittata was co-dominant with Poa secunda and Stipa columbiana on coarse, stoney s o i l s . Daubenmire (1942) included areas dominated by Balsamorhiza sagittata as part of the Agropyron association which he described as the climatic climax association of the Agropyron - Poa zone. The Stipetum richardsonii appears to be a topographic climax association occupying cool, moist habitats which have a high snow accumulation. There i s evidence of the establishment of Pseudotsuga menziesii and Pinus contorta in this association.which suggests that i t may eventually change to associations dominated by these species, such as the Calamagrostido -Pseudotsugetum *glaucae pinetosum contortae or, Calamagrostido - Pseudotsugetum *glaucae calamagrostido - pseudotsugetosum *glaucae. However, this change would necessarily be slow, as summer drought in this area w i l l limit tree growth on the finer textured s o i l s . Ultimately, the upland climax associations of the Antennario - Poetum secundae, Stipetum richardsonii and Agropyro - Balsamorhizetum sagittatae w i l l be changed into the Agropyretum spic a t i . These successional changes w i l l be brought about by the lowering of the upland habitats as a result of peneplanation and the simultaneous increase in depth of fine textured s o i l as a result of weathering of coarse fragments in the s o i l . 294 Successional Relationships of Associations Formed Primarily on Glacial Drift (including Sandy Outwash) The Calamagrostido - Pseudotsugetum *glaucae i s the most widespread association on gla c i a l d r i f t soils in the Cariboo Zone. It is represented by two subassociations\u00E2\u0080\u0094the calamagrostido - pseudotsugetosum *glaucae and the pinetosum contortae. These two have very similar understory vegetation and d i f f e r only in the tree layer. The calamagrostido - pseudotsugetosum *glaucae i s dominated only by Pseudotsuga menziesii which has been shown to be s e l f -regenerating (page 232 ). This subassociation, i s thus considered to be an edaphic climax which i s in dynamic equilibrium with i t s environment and w i l l persist u n t i l the forces of peneplanation and s o i l weathering become dominant. The pinetosum contortae i s dominated by Pinus contorta and frequently has an understory of Pseudotsuga menziesii. It i s a successional sub-association and changes rapidly to the climax calamagrostido - pseudotsugetosum *glaucae (page 233 ). This subassociation appears to be able to colonize recently exposed areas of gla c i a l d r i f t to form an early stage i n primary succession. However, the pinetosum contortae i s more commonly developed as an early stage of a secondary succession following destruction of the previous vegetation by f i r e . The identity of the pinetosum contortae i s maintained by frequent f i r e s . The Pseudotsuga - Arctostaphylos - Calamagrostis association described by Brayshaw (1955) as the climatic climax association of the Pseudotsuga zone, appears to be very similar to the Calamagrostido - Pseudotsugetum *glaucae calamagrostido - pseudotsugetosum *glaucae. It would most l i k e l y also include the Rhytidiadelpho - Pleurozio - Pseudotsugetum *glaucae described here as a topographic climax association, although, this association i s very rare south of the Cariboo Zone. The Calamagrostido - Pseudotsugetum *glaucae i s thought to 295 advance to the \"Agropyro - Pseudotsugetum *glaucae\" as a result of increasing fineness of the s o i l texture due to weathering of the coarse g l a c i a l d r i f t . It appears that on finer textured s o i l s , forest understory species like Arctostaphylos uva-ursi and Calamagrostis rubescens are replaced by xeric grass-land species like Agropyron spicatum and Koeleria g r a c i l i s . The \"Agropyro -Pseudotsugetum *glaucae\" w i l l eventually change to the Agropyretum spicati as further weathering increases the depth of fine textured s o i l s . The Rhytidiadelpho - Pleurozio-Pseudotsugetum *glaucae i s developed usually on steep northerly slopes, with temporary seepage. Pseudotsuga menziesii i s the dominant species and there i s good evidence of i t s self-regeneration (page234 ). This association i s considered to be a stable topographic climax. Successional development of this association toward the climatic climax i s believed to occur only very slowly. It w i l l depend on reduction of the present steep seepage slopes through peneplanation to gentle well drained ones. Through this topographic change the Rhytidiadelpho - Pleurozio - Pseudotsugetum *glaucae w i l l be changed into the Calamagrostido - Pseudotsugetum *glaucae calamagrostido -pseudotsguetosum *glaucae which w i l l advance to the Agropyretum spicati as a result of s o i l weathering. The Arctostaphylo - Junipero - Pseudotsugetum *glaucae is developed on well-drained subxeric sandy outwash s o i l s . Pseudotsuga menziesii regenerates successfully in this habitat (page232 ) a n c j thus the association i s considered as an edaphic climax. Successionally, there appear to be two possible routes along which i t may advance toward the climatic climax. The Arctostaphylo -Junipero - Pseudotsugetum *glaucae may change into the Calamagrostido -Pseudotsugetum *glaucae calamagrostido - pseudotsugetosum *glaucae as a result of an increase in the hygrotope. This could occur through s o i l weathering as the finer s o i l formed would have a higher moisture retention capability. From the calamagrostido - pseudotsugetosum *glaucae succession would occur to the 296 \"Agropyro - Pseudotsugetum *glaucae\" and then to the Agropyretum s p i c a t i . A second and most l i k e l y line of development i s from the Arctostaphylo -Pseudotsugetum *glaucae to the \"Agropyro - Pseudotsugetum *glaucae\" to the Agropyeretum sp i c a t i . This would occur through long term weathering which would result in the formation of a s o i l of medium or loamy texture from the present coarse textured one. The Poo - Calamagrostido - Populetum tremuloidis poo - calamagrostido -populetosum tremuloidis i s present on g l a c i a l d r i f t in subhygric to hygric habitats where i t i s successional because of the shade intolerance of Populus tremuloides. It appears to commonly represent an early stage of secondary succession following f i r e . This association may advance successionally to the Calamagrostido - Pseudotsugetum *glaucae pinetosum contortae and then to the calamagrostido - pseudotsugetosum *glaucae as Populus tremuloides and Pinus contorta are frequent associates. A second possible line of development i s to the calamagrostido - pseudotsugetosum *glaucae by direct establishment of Pseudotsuga menziesii under the Populus tremuloides canopy. The actual success-ional sequence followed, by this subassociation i s not entirely clear. However, i t i s apparent that the f i n a l stage i s the climax Calamagrostido - Pseudotsugetum \u00E2\u0080\u00A2glaucae calamagrostido - pseudotsugetosum *glaucae which w i l l eventually change to the climatic climax. Successional Relationships of Associations Formed Primarily on Alluvium The Equiseto - Piceetum *glaucae i s developed on regosolic so i l s of recent stream terraces which are frequently flooded. This association i s dominated by Picea glauca which has been shown to be regenerating well enough to maintain dominance (page 236). Thus, the Equiseto - Piceetum glaucae i s considered to be an edaphic climax which w i l l persist as long as the habitat remains unchanged from a hygric to subhydric condition. With time the Equiseto - Piceetum glaucae w i l l probably change to the 297 Rhytidiadelpho - Pleurozio - Pseudotsugetum *glaucae. This change w i l l depend on elevating the present terrace to above the high water line as a result of further downcutting of the stream. Pseudotsuga menziesii w i l l then be able to colonize the habitat and being a long lived tree with a high reproductive capacity w i l l succeed Picea glauca and become the dominant. From here, successional change w i l l be to the Calamagrostido - Pseudotsugetum \u00E2\u0080\u00A2glaucae calamagrostido - pseudotsugetosum *glaucae and then to the climatic climax. The Poo - Calamagrostido - Populetum tremuloidis lonicero -caricetosum leptopodae i s developed on stream terraces which are infrequently flooded but have a high enough water table to maintain a hygric to subhydric hygrotope. It is a successional subassociation of short duration as the dominant Populus tremuloides appears to be shade intolerant and was shown to be regenerating poorly (page 234 )\u00E2\u0080\u00A2 Successionally, the lonicero - caricetosum leptopodae may change into the climax Calamagrostido - Pseudotsugetum *glaucae calamagrostido -pseudotsugetosum *glaucae. This change would accompany a lowering of the water table and corresponding increased s o i l drainage. Populus tremuloides would be replaced by the shade tolerant Pseudotsuga menziesii and the understory would change from moist forest species to those characteristic of drier sites like Calamagrostis rubescens and Arctostaphylos uva-ursi. A second possible line of development i s to the Poo - Calamagrostido -Populetum tremuloidis poo - calamagrostido - populetosum tremuloidis and then to the Calamagrostido - Pseudotsugetum *glaucae which w i l l advance to the climatic climax. This change is supported by the fact that transitions between the two subassociations of the Poo - Calamagrostido - Populetum tremuloidis frequently occur. On stream terraces in the Cariboo Zone the Poo - Elymetum cinerei occurs 298 at an early stage of succession. Daubenmire (1942) described a similar Elymus association of seepage areas of central Washington as an edaphic climax and Brayshaw (1955, 1965) mentioned the occurrence of an Elymus association on a l l u v i a l terraces as a successional-stage to a Pinus ponderosa forest. Successionally the Poo - Elymetum cinerei w i l l most l i k e l y change to the Antennario - Poetum secundae as a result of a lowering of the water level and correspondingly the hygrotope. Sampled plots of the Poo - Elymetum cinerei appear to be advancing in this manner as the surface s o i l i s already dry enough to permit the establishment of species like Poa junc i f o l i a, Antennaria rosea, Stipa columbiana, and Koeleria g r a c i l i s , a l l of which are characteristic of the Antennario - Poetum secundae. Elymus cinereus i s deep rooting and i s regarded to be maintaining i t s position here only through vegetative reproduction as E. cinereus seedlings are unlikely to be able to germinate under the xeric surface conditions. Succession from the Antennario - Poetum secundae w i l l be directly to the Agropyretum spic a t i . Successional Relationships of Associations Formed on Sediments in Lakes without Drainage The Scirpetum v a l i d i , Puccinellio-Hordeetum jubati and Distichlo -Spartinetum g r a c i l i s are successionally related on alkaline-saline habitats. The Scirpetum v a l i d i represents the i n i t i a l stage of succession, colonizing alkaline ponds (lakes without drainage) with high salt concentrations. These ponds w i l l be transformed to t e r r e s t r i a l habitats through the continual import of sediments from the surrounding slopes. With the lowering of the water table and exposure of the s o i l surface, capillary rise and evaporation of ground water resulting in an accumulation of soluble salts near the s o i l surface becomes important. This change in habitat characteristics results in replacement of the Scirpetum v a l i d i by the Puccinellio - Hordeetum jubati in which t e r r e s t r i a l alkaline tolerant plants li k e , Hordeum jubatum, Puccinellia airoides, Spartina 299 g r a c i l i s and Di s t i c h l i s s t r i c t a are present. By continued sedimentation and a further lowering of the water table which results in an improved s o i l drainage, the Puccinellio - Hordeetum jubati i s changed into the Distichlo - Spartinetum g r a c i l i s . Here, the dominance of Hordeum jubatum and Puccinellia airoides i s replaced by Spartina g r a c i l i s and Disti c h l i s s t r i c t a corresponding to the reduction in hygrotope and amount of soluble salts present at the surface. The Distichlo - Spartinetum g r a c i l i s appears to be a stable edaphic climax association on alkaline-saline habitats with solonetzic soils in the Cariboo Zone. However, i t i s considered possible that the Distichlo - Spartinetum g r a c i l i s w i l l eventually evolve into the Antennario - Poetum secundae. This change would occur slowly and would require a lowering of the water table resulting in improvement of the drainage and lowering of the hygrotope in the Distichlo - Spartinetum g r a c i l i s habitat. Soluble salts would then be moved out of the rooting zone by leaching and the habitat would be changed from hyper-eutrophic to eutrophic status. The reduction in nutrient and moisture status would favour the growth of species characteristic of the Antennario - Poetum secundae which are only marginally present in the Distichlo - Spartinetum g r a c i l i s . From here, successional change would, in time, result in formation of the climatic climax. Daubenmire (1942) described a Di s t i c h l i s association as an edaphic climax association in saline areas in central Washington. This association appears to be similar to the Puccinellio - Hordeetum jubati and the Distichlo - Spartinetum g r a c i l i s described in this study, and therefore would be placed in the same alliance\u00E2\u0080\u0094the Distichlion strictae. Successional Relationships of Associations Formed on Sediments in Drained Lakes and Connecting Channels On the Fraser Plateau in fresh water lakes with drainage the Caricetum 300 rostratae develops as an i n i t i a l stage of hydric succession. The aquatic habitat of this association i s believed to evolve through sedimentation of mineral s o i l transported into the lakes and organic matter formed in s i t u into a semi-terrestrial one. This semi-terrestrial habitat supports the growth of woody plants, notably Salix spp. as well as the aquatic Carex spp. Thus the Caricetum rostratae advances successionally to the Carico - Salicetum monticolae. The Carico - Salicetum monticolae i s also considered as a successional association as Salix spp. are shade intolerant and regenerate slowly. This association i s thought to possibly advance to the Muhlenbergio - Betuletum glandulosae as the two occupy similar topographic locations (glacial stream depressions). This change would involve an increase in s o i l depth through sedimentation and a corresponding decrease in the hygrotope from hygric-hydric to subhygric - hygric. This successional change i s supported by the presence of buried organic horizons in two plots of the Muhlenbergio - Betuletum glandulosae. Picea glauca i s easily established in the Muhlenbergio - Betuletum glandulosae because of the cool microclimate and subhygric conditions which exist. Successionally, the Muhlenbergio - Betuletum glandulosae i s replaced by the Carico - Piceetum glaucae, which frequently borders i t . The soils of these two associations were cla s s i f i e d as Dark Grey Chernozems. These are believed to be evolving by podzolization to Grey Wooded s o i l s . This change in s o i l characteristics (development of an Ae horizon) w i l l favour the successional advancement to a forest association. In the Carico - Piceetum glaucae, Betula glandulosa and Salix brachycarpa both characteristic of the Muhlenbergio -Betuletum glandulosae occur with low significance and vigor because they appear to be shade intolerant. These shrubs are replaced by shade tolerant ones like Shepherdia canadensis. At present the Carico - Piceetum glaucae represents an 301 edapho-topographic climax association as Picea glauca i s regenerating in sufficient abundance to maintain dominance (page ). However, by lowering of the water table which w i l l result in improved drainage, i t i s possible that this association w i l l change into the Calamagrostido - Pseudotsugetum *glaucae calamagrostido - pseudotsugetosum *glaucae. Under these reduced moisture conditions Pseudotsuga menziesii would replace Picea glauca as in this subhumid climate Picea glauca i s able to survive only on moist sites. From the Calamagrostido - Pseudotsugetum *glaucae, successional changes would in time, result in formation of the climatic climax, Agropyretum sp i c a t i . In conclusion i t must be emphasized again that the ultimate successional changes from stable edaphic and topographic climax associations to the climatic climax, Agropyretum spicati, w i l l require, many tens of thousands of years to be completed. During this time peneplanation of the land surface and weathering of the s o i l to a fine texture must occur without significant change in the present climate. However, i t is to be expected that with changes of the physiographic conditions in surrounding biogeoclimatic zones, the microclimate of the Cariboo Zone w i l l be changed, and thus also i t s climatic climax association. 302 X SUMMARY AND CONCLUSIONS The purposes of this thesis are to obtain quantitative and qualitative data on vegetation and environmental factors of the Cariboo Zone and to incorporate these into a usable ecosystematic cl a s s i f i c a t i o n . The main results of this study are summarized in this section. (1) The study was centered on the Fraser Basin and Fraser Plateau parts of the Interior Plateau of British Columbia. It i s a f l a t to gently r o l l i n g country with large areas of undissected upland. For the most part the area i s covered by a mantle of g l a c i a l d r i f t from which the soil s are formed. The II climate, according to Koppen's clas s i f i c a t i o n , i s microthermal subhumid continental (Dfb). (2) Previous to this study the Cariboo Zone has been ecologically poorly documented. During the summers of 1967 and 1968 131 plots were analyzed in the Cariboo Zone using a system of selective sampling. The vegetation was studied by standard phytosociological methods and in a l l plots data were obtained for edaphic and physiographic factors. (3) The 131 plots were cla s s i f i e d into a flexible ecosystematic scheme. Ecosystem units are dealt with at levels of organization ranging from the concrete and detailed level of the plant community (individual plot) through the abstract and successively broader levels of the subassociation, association, alliance and order. Where applicable the units are compared to those previously described from related areas. (4) Eight orders, twelve alliances, twenty associations and six subassociations are distinguished and described in this study. The order Pseudotsugetalia menziesii dominates most of the forested areas and occurs on moderate to well drained subxeric to subhygric sites. It i s believed to reach i t s most northern extension in the Cariboo Zone and thus i s enriched by many Canadian boreal species. Three associations are distinguished in this order-- the Arctostaphylo - Junipero -303 Pseudotsugetum *glaucae, the Calamagrostido - Pseudotsugetum *glaucae and the Rhytidiadelpho - Pleurozio - Pseudotsugetum *glaucae. (5) The order Piceetalia glaucae i s present only marginally on subhydric habitats which range trophically from permesotrophic to subeutrophic. Three associations are distinguished in this order-- the Poo - Calamagrostido -Populetum tremuloidis, the Carico - Piceetum glaucae and the Equiseto - Piceetum glaucae. The Pleurozio - Vaccinio - Piceetum glaucae which is represented only by a single plot i s considered to also belong to this order. (6) The grassland areas of the Cariboo Zone are dominated by the order Koelerio - Agropyretalia spicati which i s developed on fine textured soils considered to be aeolian in origin. The habitats of this order range trophically from permesotrophic to eutrophic and hygrotopically from xeric to submesic. Two elevationally distinct alliances are recognized for this order. The Stipion columbianae i s considered as an upland alliance and is present at elevations of greater than 2500 feet, whereas the Agropyrion spicati i s characteristic of low elevations and reaches i t s best development on the slopes and bottoms of the major valleys. Four associations are distinguished in the Stipion columbianae--the Antennario - Poetum secundae, the Agropyro - Balsamorhizetum sagittatae, Poo - Elymetum cinerei and the Stipetum richardsonii. Four associations are distinguished in the Agropyrion s p i c a t i - - the Agropyretum spicati, the Agropyro -Artemisietum tridentatae, the Opuntio - Stipetum comatae and the Agropyro -Juniperetum scopulorum. (7) The order Betuletalia glandulosae is represented in the Cariboo Zone by a single association-- the Muhlenbergio Betuletum glandulosae. It occurs on subhygric to hygric habitats. Its distribution appears to be controlled by cold air drainage and late snow l i e . (8) Terrestrial saline-alkaline habitats in the Cariboo Zone are dominated by the order Puccinellietalia a i r o i d i s . These habitats are frequently flooded 304 and are rated trophically as hypereutrophic. Two associations are distinguished in this order-- the Puccinellio - Hordeetum jubati and the Distichlo - Spartinetum g r a c i l i s . (9) The order Scirpetalia v a l i d i has a very restricted distribution being formed in alkaline, hypereutrophic ponds with no v i s i b l e drainage outlets. Only one association i s distinguished in this order-- the Scirpetum v a l i d i . (10) The order Salicetalia i s restricted to hydric habitats along stream channels and on the edges of lakes. Only one association i s distinguished in this order-- the Carico - Salicetum monticolae. (11) The Caricetalia rostratae dominates shallow fresh water lakes in the Cariboo Zone and i s represented by a single association-- the Caricetum rostratae. (12) Following the classification c r i t e r i a outlined in the N.S.S.C.C. (1965) report the 131 plots were tentatively c l a s s i f i e d as to s o i l type. Soil profiles representative of a l l six orders of the Canadian Soil Classification System were distinguished. Soils classed into the Chernozemic and Brunizolic Orders are the most common. Soils of the Gleysolic, Regosolic and Solonetzic Orders are of localized importance while soils belonging to the Podzolic Order are rare in this region. (13) The soils of the Cariboo Zone are relatively young (less than 10,000 years). Soil development appears to be occurring slowly, largely because the mean annual precipitation of less than fourteen inches imparts a low leaching potential to the s o i l s . Also where erosion and deposition of the surface by wind occurs, s o i l development is hindered. Melanization i s the dominant s o i l forming process in the Cariboo Zone. Gleization is favoured in topographic situations with restricted drainage such as old stream channels, ponds and a l l u v i a l terraces. There i s evidence that the process of podzolization is occurring in localized areas as soils which are 305 regarded as intergrades to the Podzolic Order from the Chernozemic Order are present. (14) Generally, the soils of the Cariboo Zone are rich. The high Cation Exchange Capacity, high amounts of exchangeable cations and alkaline s o i l reaction are important chemical characteristics of these s o i l s . (15) Although detailed s o i l moisture analyses were not made in this study, moisture i s thought to frequently be a limiting factor in the Cariboo Zone. Many upland soils appear to reach permanent wilting during the latter part of the growing season as a result of the low annual precipitation and the high evaporation potential. None of the soils appear to have permanent seepage but the effect of temporary seepage i s evident in many soils and is believed to be important in the development of vegetation. (16) Ten microclimatic stations were maintained during the summer of 1968 in the Farwell Canyon area of the Fraser Plateau. Using data collected at these stations i t i s concluded that the two alliances of the Koelerio -Agropyretalia spicati can be differentiated on the basis of temperature. The Agropyrion spicati develops at low elevations where a warm microclimate prevails, and summer frosts are infrequent. In contrast the Stipion columbianae develops at high elevations where a cooler microclimate prevails and summer frosts are frequent. The forest communities for which data are available have a temperature pattern similar to that of the Stipion columbianae. Thus i t appears that forest communities are restricted to the cooler parts of the region and that high temperature may be a limiting factor to tree growth in the major valleys. (17) In the Cariboo Zone the Antennario - Poetum secundae and the Stipetum richardsonii frequently border each other but occupy microclimatically different habitats. The Antennario - Poetum secundae is developed on exposed slopes where snow accumulation i s low and duration short. In contrast the Stipetum richardsonii i s developed on protected habitats with high snow accumulation and 306 longer snow duration. From the temperature data i t i s apparent that the Stipetum richardsonii consistently reaches lower minimum temperatures than does the Antennario - Poetum secundae, and consequently summer frosts are much more frequent in the Stipetum richardsonii. It i s concluded that \"frost pocket\" conditions prevail in the Stipetum richardsonii and that the development of the association may be linked to this phenomenon. (18) The topographic relationships of the associations are presented in det a i l . It i s concluded that topography, which i s representative of a complex of physiographic factors, i s very important in controlling the distribution of associations in the Cariboo Zone. (19) It appears that dynamics within the Cariboo Zone which favour successional changes are operating at a slow rate. Thus most of the associations described are in a stable condition. Fire, s o i l weathering, degradation of slopes and aggradation of depressions are important factors influencing succession in this region. (20) A monoclimax concept is proposed for the Cariboo Zone in which i t i s assumed that ultimate peneplanation of the land surface and ultimate weathering of the s o i l to one of fine texture w i l l occur without significant changes in the climate. However, presently existing stable associations are classed as edaphic or topographic climaxes and i t i s recognized that their eventual change to the climatic climax w i l l occur very slowly; most l i k e l y taking many tens of thousands of years to be complete. The Agropyretum spicati most closely approximates the climatic climax in the Cariboo Zone where i t occurs on ridges and slopes. Soil profiles are well drained, medium textured, Brown Chernozems which are similar to those visualized as the f i n a l product of weathering under the existing subhumid climate. (21) Development on glacial d r i f t and a l l u v i a l parent materials appears to be toward the Calamagrostido - Pseudotsugetum *glaucae calamagrostido -307 pseudotsugetosum *glaucae which is considered to be a stable edaphic climax. This i s the most common forest association in the Cariboo Zone being present on ridges, gentle slopes of a l l aspects and level benches. Fire appears to be an important factor in this successional series and permits the establishment of the Calamagrostido - Pseudotsugetum *glaucae pinetosum contortae and the Poo - Calamagrostido - Populetum tremuloidis as early successional stages. The Arctostaphylo - Junipero - Pseudotsugetum *glaucae i s established as an edaphic climax association on suboligotrophic sandy outwash s o i l s . Early successional stages in this series would most l i k e l y be communities of bryophytes and lichens. The Antennario - Poetum secundae and Stipetum richardsonii are established as topo-edaphic climaxes on a parent material of aeolian deposits overlying g l a c i a l d r i f t . These are believed to be long persisting associations but w i l l ultimately change into the climatic climax. Development in saline-alkaline habitats i s towards the Distichlo -Spartinetum g r a c i l i s which i s considered here to be the successionally most advanced type in alkaline pond depressions with restricted drainage. This developmental pattern i s proceeding at a slow rate and appears to be controlled by s o i l deposition from the surrounding uplands. Development in lakes with drainage i s from the aquatic Caricetum rostratae through intermediate stages dominated by Salix and Betula to the edaphic climax, Carico - Piceetum glaucae. The controlling environmental process appears to be sedimentation of mineral s o i l transported into the lakes and organic matter formed in si t u . (22) The upland vegetation of the Cariboo Zone can be divided, physiognomically, into grassland and forest vegetation. The distribution of these two types is believed to have been hi s t o r i c a l l y determined. During the last glaciation a layer of gla c i a l d r i f t was deposited over the entire region. The forest 308 vegetation i s developed directly on this coarse textured material. However, under the grassland vegetation a thin mantle of fine textured s o i l (in which particles greater than 2mm in size are absent) overlies the glac i a l d r i f t . This fine s o i l i s thought to have originated from the Tertiary s i l t c l i f f s along the Chilcotin River and to have been deposited by wind, directly following glaciation. (23) Grazing and f i r e are factors which have had a strong influence on the vegetation of the Cariboo Zone. In the major valleys intense grazing i s resulting in the replacement of parts of the climatic climax, Agropyretum spicat i , by the Opuntio - Stipetum comatae and the Agropyro - Artemisietum tridentatae. The Antennario - Poetum secundae i s the most heavily grazed association in the Cariboo Zone and as a result i t s structure i s being altered in many areas. However, through reduction in grazing pressure these associations w i l l regain their original structures and distributions. The Cariboo Zone has suffered frequent and sometimes severe fi r e s i n the past. As a result of f i r e much of the forest area i s being maintained as successional associations. At present, because the area i s largely protected from f i r e and heavily grazed, advancement of young trees of Pinus contorta and Pseudotsuga menziesii into associations of the Stipion columbianae i s occurring. It i s believed that tree seedlings are established on the fine textured grassland soi l s during seasons when moisture i s not limiting but rarely survive the f i r s t severe drought. (24) It i s concluded that the grassland-forest boundary in the area studied i s at the present time relatively stable and appears to be controlled by available s o i l moisture as related to s o i l texture. However, temporary fluctuations in the boundary may occur as a result of f i r e and grazing. (25) The population structures and dynamics of the major tree species are examined in detail. Pseudotsuga menziesii has the widest ecological amplitude 309 of the tree species found in the zone. It grows on habitats ranging from hygric to subxeric and may even become established as a pioneer tree species. It i s shade tolerant and thus forms the climax forest cover over much of the Cariboo Zone. Pseudotsuga menziesii reaches i t s best growth in the Calamagrostido - Pseudotsugetum *glaucae calamagrostido - pseudotsugetosum \u00E2\u0080\u00A2glaucae. The lowest basal area counts for Pseudotsuga menziesii are in the Arctostaphylo - Junipero - Pseudotsugetum *glaucae. Pseudotsuga menziesii i s a long lived, slow growing tree in the Cariboo Zone; the oldest tree cored was a Douglas-fir, at 286 years. In the Cariboo Zone Picea glauca has a narrower amplitude and i s confined to habitats ranging from subhygric to subhydric. The best growth of white spruce i s in the subeutrophic Equiseto - Piceetum glaucae where i t has a very rapid growth rate. The t a l l e s t tree measured was a white spruce in this association, at 117 f t . Pinus contorta reaches i t s best growth in the Calamagrostido -Pseudotsugetum *glaucae pinetosum contortae where i t i s regarded as a successional species. It does not assume a position of dominance in any other association. Populus tremuloides has a narrow amplitude in the Cariboo Zone and reaches a dominant position only in the Poo - Calamagrostido - Populetum tremuloidis. (26) Based on the density data of the tree species and the principle of shade tolerance, i t i s concluded that relatively few seedlings of Picea glauca do become established but of this a rather high proportion survive while quite the reverse i s true of Pseudotsuga menziesii seedlings which become established in high numbers but suffer a high mortality in the understory height classes. Thus i t appears that Picea glauca maintains i t s dominance because of a high survival rate while Pseudotsuga menziesii maintains i t s dominance because of i t s p r o l i f i c reproduction. It i s concluded that Pseudotsuga menziesii is the climax tree species of the Calamagrostido - Pseudotsugetum *glaucae, the Arctostaphylo -310 Junipero - Pseudotsugetum *glaucae, and the Rhytidiadelpho - Pleurozio -Pseudotsugetum *glaucae and that Picea glauca is the climax tree species of the Carico - Piceetum glaucae and the Equiseto - Piceetum glaucae. Pinus contorta and Populus tremuloides reach dominance only as pioneer species as neither appears to be very shade tolerant and thus they both regenerate with d i f f i c u l t y under established forest canopies. (27) Based on species significance data, plots were objectively grouped by the weighted-pair-group and by the weighted-variable-group methods of cluster analysis. Community groupings were made by both methods in order to determine which method results in the ecologically most meaningful arrangement of communities. It i s concluded that the weighted-variable-group method provides the most satisfactory clustering arrangement as association clusters are generally formed at higher levels of similarity and associations are grouped so as to show relationships which appear to be ecologically more correct. It should be noted, however, that the differences between the two methods are not great. (28) The hierarchical arrangement of plots resulting from the cluster analysis paralelled very closely the ecosystematic classification subjectively developed using traditional phytosociological methods. Association groupings are easily recognizable on the dendrogram resulting from the cluster analysis and range in their levels of similarity from 40% to 80% with the majority of association groupings finalized at levels of similarity greater than 50%. The within-group association similarity was high in the f l o r i s t i c a l l y simple associations and decreased as the f l o r i s t i c complexity of associations increased. It is concluded, that in general, the levels of similarity at which the associations are clustered i s high and thus the associations are considered to represent very homogeneous groupings of f l o r i s t i c a l l y similar communities. (29) It i s concluded that cluster analysis i s a useful technique in 311 ecosystematic studies. Using this method i t i s possible to: (1) quantitatively substantiate ecosystematic classifications incorporating ecosystem units of varying degrees of generalization; (2) show the degree of homogeneity of the ecosystem units based on within group similarities and (3) interpret f l o r i s t i c and environmental relationships between the ecosystem units. (30) It i s concluded that the synecological approach and clas s i f i c a t i o n methods used in this study allow the presentation of vegetation - environment relationships in a truly ecosystematic format. This format provides information which could be readily used for range or forest management and at the same time could serve as a basis for additional more detailed s c i e n t i f i c studies. 312 XI BIBLIOGRAPHY ABRAMS, L. 1940-1951. Illustrated flora of the Pacific States. Vol. 1-3 Stanford Univ. Press. BECKING, R. W. 1957. The Ziirich-Montpellier School of Phytosociology. Bot.Rev. 23:411-488. BILLINGS, W. D. 1952. The Environmental Complex in relation to plant growth and distribution. Quart. Rev. of B i o l . 27:251-265. BILLINGS, W. D. 1965. Plants and the Ecosystem. Wardsworth Publ. Co. 154 pp. BIRD, C. D. 1966. A catalogue of the lichens reported from Alberta. Dept. of Biology, The University of Calgary, Alberta, Canada. 24 pp. BORDEN, S. 1967. Computer program for calculation of cluster analyses. Department of Botany, University of Br i t i s h Columbia, Vancouver, Canada. (Unpublished program). B0UY0UC0S, G. J. 1951. A recalibration of the hydrometer method for making mechanical analysis of s o i l s . Agron. J. 43:434-438. BRAUN-BLANQUET, J. 1932. Plant Sociology: [Engl, transl. of Plfanzensoziologie (1928) by G. D. Fuller and H. S. Conard]] . New York: McGraw-Hill 439 pp. BRAUN-BLANQUET, J. and W. C. De LEEUW, 1936. Vegetationsskizze von Ametand. Comm. S.I.G.M.A. 50, Nederl. Kruidk. Arch. 46. BRAY, R. H. and L. T. KURTZ. 1945. Determination of tot a l , organic and available forms of phosphorus in s o i l s . Soil Sci. 59:39-45. BRAYSHAW, T. C. 1955. An ecological classification of the ponderosa pine stands in the southern interior of British Columbia. Ph.D. thesis, Department of Biology and Botany, University of British Columbia, Vancouver, Canada. 240 pp. BRAYSHAW, T. C. 1965. The Dry Forest of Southern British Columbia. The Ecology of Western North America. 1:65-75. 313 BROOKE, R. C. 1966. Vegetation - environment relationships of Subalpine Mountain Hemlock Zone ecosystems. Ph.D. thesis, Department of Botany, University of Bri t i s h Columbia, Vancouver, Canada. 225 pp. CHAPMAN, J. D. 1952. The climate of Br i t i s h Columbia. Paper presented to the f i f t h B. C. Natural Resources Conference, Feb. 27, 1952. CLEMENTS, F. E. 1936. Nature and structure of the climax. J. Ecol. 24:252-284. COOPER, W. S. 1928. Seventeen years of successional change upon Isle Royale, Lake Superior. Ecology 9:1-5. COTTAM, W. P. and G. STEWART. 1940. Plant succession as a result of grazing and of meadow desiccation by erosion since settlement in 1862. J. For. 38:613-626. CRUM, H.; W. C. STEERE and L. E. ANDERSON. 1965. A l i s t of the mosses of North America. The Bryologist 68:377-431. DAUBENMIRE, R. F. 1940. Plant succession due to overgrazing in the Agropyron bunchgrass prairie of southeastern Washington. Ecology 21:55-64. DAUBENMIRE, R. F. 1942. An ecological study of the Vegetation of southeastern Washington and adjacent Idaho. Ecol. Monogr. 12:53-79. DAUBENMIRE, R. F. 1952. Forest vegetation of northern Idaho and adjacent Washington, and i t s bearing on concepts of vegetation cl a s s i f i c a t i o n . ' Ecol. Monogr. 22:301-330. DAUBENMIRE, R. F. 1953. Nutrient content of leaf l i t t e r of trees in the northern Rocky Mountains. Ecology 34:786-793. DAVIS, R. J. 1952. The Flora of Idaho. Wm. C. Brown Co. Publ. Dubuque, Iowa. 836 pp. DAWSON, G. M. 1876. Report on Explorations in British Columbia. Progress Report of the Geological Survey of Canada 1875-76:233-240. 314 DAWSON, G. M. 1879. Report on the climate and agricultural value, general geological features and minerals of economic importance of part of the northern portion of British Columbia and the Peace River Country. Canada Geological Survey. Appendix 7. ELLISON, L. 1960. Influence of grazing on plant succession of rangelands. Bot. Rev. 26:1-78. FLINT, R. F. 1963. Glacial and Pleistocene geology. John Wiley and Sons, Inc., Publishers 553 pp. GEIGER, R. 1965. The climate near the ground. Harvard University Press, 611 pp. GREIG-SMITH, P. 1964. Quantitative Plant Ecology 2nd ed. Butterworths, London. 256 pp. HALE, M. E. Jr. and W. L. CULBERSON. 1966. A third checklist of the lichens of the continental United States and Canada. The Bryologist 69:141-181. HALLIDAY, W. E. D. 1937. A forest classification of Canada. Canada, Dept. Mines and Resources Forest Serv. Bull. 89, Kings Printer, Ottawa, 50 pp. HAMET-AHTI, L. 1965. Notes on the vegetation zones of western Canada, with special reference to the forests of Wells Gray Park, British Columbia. Ann. Bot. Fenn. 2:274-300. HITCHCOCK, A. S. 1950. Manual of the grasses of the United States. Ed. 2, revised by A. Chase. U.S.D.A. Miscl. Publ. 200. HITCHCOCK, C. L., A. CRONQUIST, M. OWNBEY and J. W. THOMPSON. 1955-1964. Vascular Plants of the Pacific Northwest. Vol. 2-5 University of Washington Press. Seattle. HOLLAND, S. S. 1964. Landforms of British Columbia, A physiographic outline. Brit. Col. Dept. of Mines & Petr. Res. Bull. No. 48, 138 pp. 315 HULTEN, E. 1968. The flora of Alaska and neighbouring t e r r i t o r i e s . Stanford University Press, Stanford, C a l i f . 1008 pp. ILLINGWORTH, K. and J. W. C. ARLIDGE. 1960. Interm report on some forest site types in lodgepole pine and spruce-alpine f i r stands. B. C. Dept. of Lands and Forests, For. Ser. Res. Notes. No. 35, 44 pp. ILVESSALO, Y. 1929. Notes on some forest site types in North America. Acta Forestalia Fennica, 34:1-111. JACKSON, M. L. 1958. Soil chemical analysis. Prentice-Hall Inc. N. J . 498 pp. KOCH, W. 1926. Die Vegetationseinheiten der Linthebene unter Bertlcksichtigung der Vernaltnisse in der Nordostschweiz. Systematisch-Kritische Studie, Diss. E.T.H. Jahrb. & St. Gall, naturwiss, Ges. 61, 11. KRAJINA, V. J. 1933. Die Pflanzengesellschaften des Mlynica-Tales in den Vysoke Tatry (Hohe Tatra) mit besonderer Beriicksichtigung der okologischen Verhaltnisse. Bot. Centralbl. Beih., (Abt 2) 50:744-957; 51:1-244. KRAJINA, V. J. 1960. Ecosystem clas s i f i c a t i o n of forests. Silva Fennica 105:107-110. KRAJINA, V. J. 1965. Biogeoclimatic zones and biogeocoenoses of Br i t i s h Columbia. Ecology of Western North America 1:1-17. KRAJINA, V. J. 1969. Ecology of forest trees in British Columbia. Ecology of Western North America. Vol. 2 (in press). KUJALA, V. 1945. Waldvegetationsuntersuchungen in Kanada. Annales Academiae Scientiarum Fennicae, Series A:IV. Biologica 7. LAMB, I. M. 1963. Index Nominum Lichenum, Inter-annas 1932 et 1960 divulgatorum. Ronald Press Company, N.Y. 809 pp. 316 LAMBERT, J. D. H. 1968. The ecology and successional trends of tundra plant communities in the Low Arctic Subalpine Zone of the Richardson and British Mountains of the Canadian Western Arctic. Ph.D. thesis, University of British Columbia, Vancouver, Canada. 164 pp. McINTOSH, R. P. 1967. The continuum concept of vegetation. Bot. Rev. 33:130-187. McLEANt A. and L. S. MARCHAND. 1964. Guide to types and conditions of grassland ranges in southern interior British Columbia. Can. Dept. Agric. Res. Station, Kamloops, B. C. (mimeo). METSON, A. J. 1961. Chemical measurements used to characterize so i l s for classification purposes. Proc. Pacific Sci. Congr. 18:60-67. MOSS, E. H. 1932. The vegetation of Alberta. IV. The poplar association and related vegetation of central Alberta. J . Ecol. 20:380-415. MOSS, E. H. 1952. Grassland of the Peace River region, western Canada. Can. J . Bot. 30:98-124. MOSS, E. H. 1953. Forest communities in northwestern Alberta. Can. J. Bot. 31:212-252. MOSS, E. H. 1955. The vegetation of Alberta. Bot. Rev. 21:493-567. MOSS, E. H. 1959. The flora of Alberta. Toronto Univ. of Toronto Press. 546 pp. MOSS, E. H. and J. A. CAMPBELL. 1947. The fescue grassland of Alberta. Can. J. Res. C. 25:209-227. NATIONAL SOIL SURVEY COMMITTEE OF CANADA. 1965. Report on the sixth meeting. Laval University, Quebec. 132 pp. (mimeo). NATIONAL SOIL SURVEY COMMITTEE OF CANADA. 1968. Preliminary s o i l c l a s s i f i c a t i o n . (mimeo). OOSTING, H. J. 1956. The study of plant communities. San Francisco; W. H. Freeman & Co. 440 pp. (2nd ed.). 317 ORLOCI, L. 1964. Vegetational and environmental variations in the ecosystems of the Coastal Western Hemlock Zone. Ph.D. thesis, Department of Botany, University of British Columbia. 125 pp. OTTO, G. F. and T. Ahti. 1967. Lichens of British Columbia, preliminary checklist. University of Br i t i s h Columbia. 40 pp. (mimeo). PALLISER, J. 1863. Exploration-British North America, (cited from Moss 1955). PEECH, M., L. T. ALEXANDER, L. A. DEAN and J. F. REED. 1947. Methods of s o i l analysis for s o i l - f e r t i l i t y investigations. U.S.D.A. Circ. 757. 25 pp. PICKFORD, G. D. 1932. The influence of continued heavy grazing and of promiscuous burning on spring-fall ranges in Utah. Ecology 13:159-171. POORE, M. E. D. 1955, 1956. The Use of Phytosociological methods in ecological investigations. I-The Braun-Blanquet system. J. Ecol. 43:226-244; II-Practical issues involved in an attempt to apply the Braun-Blanquet system. J. Ecol. 43:245-269; I l l - P r a c t i c a l applications. J. Ecol. 43:606-651; IV-General discussion of phytosociological problems. J. Ecol. 44:28-50. POORE, M. E. D. 1964. Intergration in the plant community J. Ecol. 52:(suppl.)213-226. PRECIPITATION NORMALS FOR BRITISH COLUMBIA. 1965. Clim. Div.. Meteorological Br., Dept. of Transport, Canada. PROGREBNJAK, P. S. 1930. Uber die Methodik der Standortsuntersuchungen in Verbindung mit Waldtypen. Verh. Int. Congr. For s t l . Versuchsanstalten 1929, Stockholm. REAM, R. R. 1965. A standard computer program for determining the index of similarity among vegetation stands. Abstr. Bull. Ecol. Soc. Amer. 43:98. 318 ROWE, J. S. 1953. Forest sites - a discussion. For. Chron. 29:278-279. ROWE, J. S. 1959. Forest regions of Canada. Canada Dept. Northern Affairs & National Resources, Forestry Branch, Bull. 123. Queen's Printer, Ottawa. 71 pp. RUMMEL, R. S. 1951. Some effects of livestock grazing on ponderosa pine forest and range in central Washington. Ecology 32:594-607. RYSWYK, A. L.; van, A. McLEAN and L. S. MARCHAND. 1966. The climate, native vegetation and soil s of some grasslands at different elevations in British Columbia. Can. J. Plant Sci. 46:35-50. SANDERSON, M. 1948. The climates of Canada according to the New Thornthwaite cla s s i f i c a t i o n . Sci. Agr. 28:501-517. SHANTZ, H. L. and R. L. PIEMEISEL. 1940. Types of vegetation in Escalante Valley, Utah, as indicators of s o i l conditions. U.S.D.A., Tech. Bull. 713 46 pp. SOKAL, R. R. and C. D. MICHENER. 1958. A s t a t i s t i c a l method for evaluating systematic relationships. Univ. Kansas Sci. Bull. 38:1409-1438. SOKAL, R. R. and P. H. A. SNEATH. 1963. Principles of numerical taxonomy. W. H. Freeman and Co. San Francisco and London. 359 pp. SORENSEN, T. 1948. A method of establishing groups of equal amplitude in plant sociology based on similarity of species content and i t s application to analysis of the vegetation on Danish Commons. K. Danske Vidensk. Selsk. , Bi o l . Skr. 5_(4)-.1-34. SPILSBURY, R. H. and E. W. TISDALE. 1944. Soil-plant relationships and vertical zonation in the southern interior of British Columbia. Sci. Agr. 24:395-436. STODDART, L. A. 1941. The Palouse grassland association in northern Utah. Ecology 22:158-163. SUKACHEV, V. N. 1944. On principles of genetic c l a s s i f i c a t i o n in biogeocoenology. Zhur. Obschch. Bi o l . 5:213-227. (In Russian with English summary). SUKACHEV, V. N. 1945. Biogeocoenology and phytogeocoenology CR. Acad. Sci. U.S.S.R., 47:429-431. SZAFER, W. 1966. The vegetation of Poland. Int. Ser. Magr. in Pure and Appl. B i o l . , Bot. Div., Vol. 9. Pergamon Press, N.Y. 738 pp. TANSLY, A. G. 1935. The use and abuse of vegetational concepts and terms. Ecology 16:284-307. TAYLOR, T. M. C. 1963. The ferns and fern a l l i e s of Bri t i s h Columbia. British Columbia Provincial Museum, Handbook No. 12, Queens Printer, B. C. 172 pp. TAYLOR, T. M. C. 1966. The l i l y family (Liliaceae) of Bri t i s h Columbia. Bri t i s h Columbia Provincial Museum Handbook No. 25, Queens Printer, B. C. 109 pp. TEMPERATURE NORMALS FOR BRITISH COLUMBIA. 1965. Clim. Div., Meteorological Br., Dept. of Transport, Canada. TIPPER, H. W. 1959. Map 12-1959. Geology, Quesnel, Cariboo D i s t r i c t , B r i t i s h Columbia. Geological survey of Canada. Sheet 93B. TISDALE, E. W. 1947. The grasslands of the southern interior of Bri t i s h . Columbia. Ecology 28:346-382. TISDALE, E. W. 1950. Grazing of forest lands in interior British Columbia. J. Forestry 48:856-860. WEST, N. E. 1966. Matrix cluster analysis of montane forest vegetation of the Oregon Cascades. Ecology 47:975-980. WHITFORD, H. N. & R. D. CRAIG. 1918. Forests of British Columbia. Comm. Conservation Canada 1-409. 320 WHITTAKER, R. H. 1962. Classification of natural communities, Bot. Rev. 28:1-239. WILDE, S. A. and G. K. VOIGT. 1955. Analysis of soils and plants for foresters and horticulturists. J. W. Edwards, Publ. Inc. Ann Arbor, Mich. 117 pp. 321 XII APPENDICES 322 Appendix I Scales used for estimating species Significance and Sociability Domin-Krajina Scale for Species Significance (after Krajina 1933) + very sparsely present, cover negligible 1 seldom, cover negligible 2 very scattered, cover negligible 3 scattered, cover to 5% of the plot 4 common, cover to 5% - 10% of the plot 5 often, cover to 10% - 20% of the plot 6 very often, cover to 20% - 30% of the plot 7 abundant, cover to 30% - 50% of the plot 8 abundant, cover to 50% - 75% of the plot 9 abundant, cover to 75% - 95% of the plot 10 abundant, cover to 100% of the plot Sociability Scale (after Krajina 1933) + solitary, not touching others of the same species 1 2-3 plants, clumps of bryophyteslh in x lh in 2 a few plants, clumps of one square foot 3 groups, l~3h square feet 4 groups, 3^-10 square feet 5 groups, 10-20 square feet 6 groups, 50 square feet 7 groups, 250-500 square feet 8 groups, 1000 square feet 9 groups, 2000-5000 square feet 10 groups, 5000 square feet 323 Appendix II Check Lis t of Plants The check l i s t of plants i s arranged alphabetically and includes a l l species referred to in the text and tables. The nomenclature of the vascular plants i s according to the following references: \"Vascular Flora of Bri t i s h Columbia, Preliminary Check L i s t \" Taylor 1966; \"Vascular Plants of the Pacific Northwest\", vols 2-5, Hitchcock et a l . (1955 - 1964) and \"Flora of Alaska\", Hulten (1968). The nomenclature of lichens follows, \"A Third Check List of the Lichens of the Continental United States and Canada\" Hale and Culberson (1966), \"Lichens of Bri t i s h Columbia, Preliminary Check L i s t \" Otto and Ahti (1967), \"A Catalogue of the Lichens Reported from Alberta\" Bird (1966) and \"Index Nominum Lichenum\" Lamb (1963). The nomenclature of the bryophytes i s after \"A Lis t of the Mosses of North America\" Crum et a l . (1965). Vascular Plants Acer glabrum Torr. Achillea millefolium L. Actaea rubra (Ait.) Willd. Agoseris glauca (Pursh) Raf. Agropyron spicatum (Pursh) Scribn. & Sm. (includes: A. inerme Rydb.) Agropyron subsecundum (Link) Hitchc. Agropyron trachycaulum Malte. Agrostis exarata Trin. Agrostis scabra Willd. Allium cernuum Roth. Alnus tenuifolia Nutt. Amelanchier a l n i f o l i a Nutt. Androsace septentrionalis L. Anemone multifida Poir. Antennaria anaphaloides Rydb. Antennaria dimorpha (Nutt.) T. & G. Antennaria neglecta Greene Antennaria parvifolia Nutt. Antennaria rosea Greene Antennaria umbrinella Rydb. Apocynum androsaemifolium L. Aquilegia formosa Fisch. 324 Check L i s t (Continued) Arabis h o l b o e l l i i Hornem. Aralia nudicaulis L. Arceuthobium americanum Nutt. Arctostaphylos uva-ursi (L.) Spreng. Arenaria l a t e r i f l o r a L. Arnica cordifolia Hook. Arnica sororia Greene Artemisia campestris L. Artemisia dracunculus L. Artemisia frigida Willd. Artemisia tridentata Nutt. Aster campestris Nutt. Aster c i l i o l a t u s Lindl. Aster conspicuus Lindl. Aster junciformis Rydb. Aster modestus Lindl. Aster pansus (Blake) Crong. Astragalus alpinus L. Astragalus americanus (Hook.) Jones Astragalus dasyglottis Fisch. Astragalus miser Dougl. Astragalus tenellus Pursh Atriplex truncata (Torr.) Gray Balsamorhiza sagittata (Pursh) Nutt. Betula glandulosa Michx. Betula papyrifera Marsh Bromus anomalus Rupr. Bromus inermis Leyss. Bromus marginatus Nees. Calamagrostis canadensis (Michx.) Beauv. Calamagrostis neglecta (Ehrh.) Gaertn. Calamagrostis rubescens Buckl. Calochortus macrocarpus Dougl. Calypso bulbosa (L.) Oakes. Carex aquatilis Wahlb. Carex concinna R. Br. Carex concinnoides Mack. Carex disperma Dewey. Carex leptopoda Mack. Carex obtusata L i l j e b l . Carex pachystachya Cham. Carex praegracilis Boott. Carex praticola Rydb. Carex rostrata Stokes Carex saltuensis L. H. Bailey C a s t i l l e j a miniata Dougl. Ceanothus sanguineus Pursh. Cerastium arvense L. Chenopodium fremontii Wats. var. atrovirens (Rydb.) Fosberg. Chenopodium leptophyllum (Moq.) Wats. Chenopodium rubrum L. Chimaphila umbellata (L.) Bart. Chrysothamnus nauseosus (Pall.) B r i t t . Cinna l a t i f o l i a (Trevir.) Griseb. Check List (Continued) Circaea alpina L. Cirsium foliosum (Hook.) DC. Cirsium undulatum (Nutt.) Spreng. Clematis columbiana (Nutt.) T. & G. Comandra umbellata (L.) Nutt. var. pallida A Cornus canadensis L. Cornus stolonifera Mx. Corydalis aurea Willd. Crepis atrabarba Heller Crepis tectorum L. Danthonia spicata (L.) Beaun. Delphinium bicolor Nutt. Delphinium brownii Rydb. Descurainia pinnata (Walt.) B r i t t . Disporum trachycarpum (S. Wats.) B. S H. Dist i c h l i s s t r i c t a (Torr.) Rydb. Dodecatheon pauciflorum (Due.) Greene Eleocharis palustris (L.) R. & S. Elymus cinereus Scribn. & Merr. Elymus glaucus Buckl. Elymus hirsutus Presl. Epilobium angustifolium L. Epilobium palustre L. Epilobium watsonii Barbey Equisetum arvense L. Equisetum scirpoides Michx. Erigeron acris L. Erigeron compositus Pursh Erigeron f l a g e l l a r i s Gray Erigeron speciosus (Lindl.) DC. Eriogonum heracleoides Nutt. Eriogonum niveum Dougl. Festuca idahoensis Elmer. Festuca saximontana Rydb. Fragaria virginiana Duchesne Gaillardia aristata Pursh Galium boreale L. Galium trifidum L. Galium triflorum Michx. Geocaulon lividum (Richards.) Fern. Geranium richardsonii Fisch. & Travt. Geranium viscosissimum Fish. & Mey. Geum macrophyllum Willd. Geum triflorum Pursh Glyceria striata (Lam.) Hitchc. Goodyera oblongifolia Raf. Goodyera repens R. Br. Grindelia squarrosa (Pursh) Dunal Habenaria obtusata (Banks ex Pursh) Richards Habenaria orbiculata (Pursh) Torr. Habenaria saccata Greene Heracleum lanatum Michx. Heuchera cylindrica Dougl. Check Lis t (Continued) Hieracium umbellatum L. Hippuris vulgaris L. Hordeum jubatum L. Juncus balticus Willd. Juniperus communis L. Juniperus scopulorum Sarg. Koeleria g r a c i l i s Pers. Lappula redowskii (Hornem.) Greene Lathyrus ochroleucus Hook. Lathyrus nevadensis S. Wats. Lepidium densiflorum Schrod. Lepidium virginicum L. Lilium columbianum Hanson Linnaea borealis L. Linum lewisii L. Lithospermum ruderale Dougl. Lomatium macrocarpum (H. & A.) C. & R. Lonicera involucrata (Rich.) Banks Luzula parviflora (Ehrh.) Desn. Lycopodium annotinum L. Lycopodium complanatum L. ' Mahonia aquifolium (Pursh) Nutt. Mentha arvensis L. var. glabrata (Benth.) Fern Mitella nuda L. Moneses uniflora (L.) A. Gray Muhlenbergia richardsonis (Trin.) Rydb. Opuntia f r a g i l i s (Nutt.) Haw. Orthocarpus hispidus Benth. Oryzopsis asperifolia Michx. Oryzopsis hymenoides (Roem. & Schult.) Ricker Oryzopsis pungens (Torr.) Hitchc. Osmorhiza chilensis Hook, and Am. Osmorhiza depauperata Phil. Oxytropis campestris (L.) DC. Parnassia palustris L. var. neogaea Fern. Penstemon procerus Dougl. Petasites v i t i f o l i u s Greene Phleum pratense L. Picea glauca (Moench) Voss Pinus contorta Dougl. var. l a t i f o l i a Engelm. Poa fendleriana (Steud.) Vasey Poa gracillima Vasey Poa interior Rydb. Poa juncifolia Scribn. Poa longiligula Scribn. & W i l l . Poa nervosa (Hock.) Vasey Poa palustris L. Poa pratensis L. Poa secunda Presl Polemonium pulcherrimum Hook. Polygonum aviculare L. Polygonum coccineum Muhl. Polygonum hydropiperoides Michx. Polystichum munitum (Kaulf.) Presl 327 Check Lis t (Continued) Populus tremuloides Michx. Populus trichocarpa T. & G. Potentilla anserina L. Potentilla d i v e r s i f o l i a Lehm. Potentilla g r a c i l i s Dougl. Potentilla pennsylvanica L. Prunus virginiana L. Pseudotsuga menziesii (Mirb.) Franco var. glauca (Beissn.) Franco Puccinellia airoides (Nutt.) Wats. Pyrola a s a r i f o l i a Michx. Pyrola secunda L. Pyrola virens Schweigg Ranunculus cymbalaria Pursh Ranunculus scerleratus L. Ribes americanum M i l l . Ribes lacustre (Pers.) Poir. Ribes oxyacanthoides L. Rosa acicularis Lindl. Rubus idaeus L. Ssp. sachalinensis (Levi.) Focke Rubus pubescens Raf. Rumex maritimus L. Salicornia rubra A. Nels. Salix arbusculoides Anderss. Salix barclayi Anderss. Salix bebbiana Sargent Salix brachycarpa Nutt. Salix glauca L. Salix lasiandra Benth. Salix monticola Bebb. Salix sitchensis Sanson Saxifraga occidentalis S. Wats. Schizachne purpurascens (Torr.) Swallen Scirpus validus Vahl. Sedum stenopetalum Pursh Selaginella densa Rydb. Senecio indecorus Greene Senecio pauperculus Michx. Shepherdia canadensis (L.) Nutt. Silene menziesii Hook. Silene scouleri Hook. Sisymbrium l o e s e l i i L. Sisyrinchium sarmentosum Suksd. Smilacina racemosa (L.) Desf. Smilacina ste l l a t a (L.) Desf. Solidago canadensis L. Solidago multiradiata Ait. Spartina g r a c i l i s Trin. Spiraea b e t u l i f o l i a P a l l . var. lucida (Dougl.) C. L. Mitch. Sporobolus cryptandrus (Torr.) Gray Stipa columbiana Macoun. Stipa comata Trin. & Rupr. Stipa richardsonii Link Suaeda depressa (Pursh) Wats. Check Lis t (Continued) Symphoricarpos O c c i d e n t a l i s Hook. Tanacetum vulgare L. Taraxacum officinale Weber Thalictrum occidentale A.Gray Thelypteris oreopteris (Ehrh.) Slosson Tragopogon dubius Scop. Trifolium repens L. Triglochin maritima L. Triglochin palustris L. Urtica dioica L. Vaccinium caespitosum Michx. Vaccinium membranaceum Dougl. Vaccinium myrtilloides Michx. Virburnum edule (Michx.) Raf. Viola adunca J. E. Smith Viola americana Muhl. Viola canadensis L. Viola glabella Nutt. var. nephrophylla Greene Viola orbiculata Geyer Woodsia oregana D. C. Eaton Zygadenus gramineus Rydb. Lichens Alectoria americana Mot. Alectoria fremontii Tuck. Alectoria glabra Mot. Alectoria sarmentosa (Ach.) Ach. Bacidia sphaeroides (Dicks.) Zahlbr. Blastenia sinapisperma (Lam.) Mass. Buellia punctata (Hoffm.) Mass. Caloplaca s t i l l i c i d i o r u m (Vahl) Lynge Candelaria concolor (Dicks) B. Stein Candelariella v i t e l l i n a (Ehrh.) Mull. Arg. Cetraria canadensis (Ras.) Ras. Cetraria cucullata (Bell.) Ach. Cetraria ericetorum Opiz. Cetraria glauca (L.) Ach. Cetraria halei Culb. & Culb. Cetraria m e r r i l l i i Du Rietz Cetraria nivalis (L.) Ach. Cetraria pinastri (Scop.) S. Gray Cetraria platyphylla Tuck. Cetraria scutata (Wulf.) Poetsch Cladonia arbuscula (Wallr.) Rabenh. ssp. arbuscula C. Cladonia arbuscula (Wallr.) Rabenh. ssp. beringiana Ahti Cladonia cariosa (Ach.) Spreng. Cladonia cenotea (Ach.) Schaer. Cladonia chlorophaea Florke Cladonia coccifera (L.) Willd. Cladonia coniocraea (Florke) Spreng. Check Lis t (Continued) Cladonia cornuta (L.) Hoffm. Cladonia crispata (Ach.) Flot. Cladonia deformis (L.) Hoffm. Cladonia fimbriata (L.) Fr. Cladonia furcata (Huds.) Schrad. Cladonia g r a c i l i s (L.) Willd. var. dilatata (Hoffm.) Schaer. Cladonia mitis Sandst. Cladonia multiformis Merr. Cladonia nemoxyna (Ach.) Am. Cladonia pocillum (Ach.) 0. Rich. Cladonia pyxidata (L.) Hoffm. Cladonia rangiferina (L.) Wigg. Cladonia scabriuscula (Del. ex Duby) Leight. Cladonia squamosa (Scop.) Hoffm. Collema tenax (Sw.) Ach. var. corallinum (Mass.) Degel. Cornicularia aculeata (Schreb.) Ach. Dermatocarpon hepaticum (Ach.) Th. Fr. Diploschistes canadensis Ras. Diploschistes scruposus (Schreb.) Norm. Fulgensia bracteata (Hoffm.) Ras. Fulgensia fulgens (Sw.) Elenk. Hypogymnia austerodes (Nyl.) Ras. Hypogymnia enteromorpha (Ach.) Nyl. Hypogymnia physodes (L.) Nyl. Hypogymnia vittata (Ach.) Gas. Lecanora cadubriae (Mass.) Hedl. Lecanora coilocarpa (Ach.) Nyl. Lecanora hageni (Ach.) Ach. Lecanora subrugosa Nyl. Lecanora varia (Ehrh.) Ach. Lecidea auriculata Th.Fr. Lecidea berengeriana (Mass.) Nyl. Lecidea decipiens (Hedw.) Ach. Letharia vulpina (L.) Hue Lobaria pulmonaria (L.) Hoffm. Nephroma helveticum Ach. var. sipeanum (Gyeln.) Wetm. Ochrolechia upsaliensis (L.) Mass. Pannaria pezizoides (G. Web.) Trev. Parmelia chlorochroa Tuck. Parmelia exasperatula Nyl. Parmelia subolivacea Nyl. Parmelia sulcata Tayl. Parmeliopsis ambigua (Wulf.) Nyl. Parmeliopsis hyperopta (Ach.) Arn. Peltigera canina (L.) Willd. var. canina Peltigera canina (L.) Willd. var. rufescens (Weiss) Mudd Peltigera canina (L.) Willd. var. spuria (Ach.) Schaer. Peltigera horizontalis (Huds.) Baumg Peltigera lepidophora (Nyl.) Vain. Peltigera malacea ( Ach.) Funk Peltigera polydactyla (Neck.) Hoffm. Peltigera praetextata (Florke ex Somm.) Vain. Peltigera venosa (L.) Baumg 330 Check L i s t (Continued) Physcia adscendens (Fr.) Oliv. Physcia muscigena (Ach.) Nyl. Physcia s t e l l a r i s (L.) Nyl. Psoroma hypnorum (Vahl) S.Gray Ramalina farinacea (L.) Ach. Ramalina po l l i n a r i a (Westr.) Ach. Stereocaulon tomentosum Fr. Thrombium epigaeum (Pers.) Wallr. Usnea alpina Mot. Usnea cavernosa Tuck. Usnea comosa ( Ach.) Ach. Usnea glabrescens (Wyl. ex Vain.) Vain. ssp. glabrella (Mot.) Mot. Usnea glabrata (Ach.) Vain. Usnea hirta (L.) Wigg. Usnea scabrata Nyl. var. nylanderiana Mot. Usnea sorediifera (Am.) Lynge var. substerilis (Mot.) Keissl. Xanthoria fallax (Hepp) Am. Bryophytes Abietinella abietina (Hedw.) Fleisch. Amblystegium serpens (Hedw.) B.S.G. Aulacomnium palustre (Hedw.) Schwaegr. Barbula convoluta (Hedw.) Brachythecium salebrosum (Web. & Mohr.) B.S.G. Bryum argenteum Hedw. Bryum weigelii Spreng. Ceratodon purpureus (Hedw.) Brid. Climacium dendroides (Hedw.) Web. & Mohr. Cratoneuron filicinum (Hedw.) Spruce Dicranum fuscescens Turn. Dicranum polysetum Sw. Dicranum scoparium Hedw. Distichium capillaceum (Hedw.) B.S.G. Drepanocladus aduncus (Hedw.) Warnst. Drepanocladus uncinatus (Hedw.) Warnst. Eurhynchium pulchellum (Hedw.) Jenn. Funaria hygrometrica Hedw. Hedwigia c i l i a t a (Hedw.) P. Beauv. Hylocomium splendens (Hedw.) B.S.G. Hypnum revolutum (Mitt.) Lindb. Leptobryum pyriforme (Hedw.) Wils. Marchantia polymorpha L. Mnium rugicum Laur. Mnium spinulosum B.S.G. Oncophorus wahlenbergii Brid. Pleurozium schreberi (Brid.) Mitt. Pohlia cruda (Hedw.) Lindb. Pohlia nutans (Hedw.) Lindb. Polytrichum juniperinum Hedw. Polytrichum piliferum Hedw. Ptilidium pulcherrimum (Weber) Mampe. Ptilium crista-castrensis (Hedw.) De Not. Check List (Continued) P y l a i s i e l l a polyantha (Hedw.) Grout Rhacomitrium heterostichum (Hedw.) Brid. Rhynchostegiella compacta (C. Mull.) Loeske Rhytidiadelphus triquetrus (Hedw.) Warnst. Rhytidium rugosum (Hedw.) Kindb. Thuidium recognitum (Hedw.) Lindb. Timmia austriaca Hedw. Tomenthypnum nitens (Hedw.) Loeske Tortella f r a g i l i s (Hook, ex Drumm.) Limpr. Tortella tortuosa (Hedw.) Limpr. Tortula ruraliformis (Besch.) Dix. Tortula ruralis (Hedw.) Gaertn., Meyer & Scherb. 332 Appendix III Explanatory Notes for Vegetation, Environment, and Soil Tables A. Vegetation Tables, 1. Nomenclature of the ecosystem units follows standard phytosociological practice. Unit designations are formed from the generic name of a characteristic species and in some cases the specific name appears in the genitive case. Order - et a l i a Alliance - ion Association - etum Subassociation - etosum 2. Plots are arranged horizontally across the table by increasing elevation from l e f t to right. ^ 3. Species are arranged verti c a l l y in a l l tables according to the following scheme: (a) by layers where present A layer A^ Trees over 66 f t in height A 2 Trees 49 f t - 66 f t in height A 3 Trees 33 f t - 49 f t B layer B^ Woody plants between 6 f t and 33 f t B 2 Woody plants 1 foot to 6 f t in height C layer Herbacious plants and woody plants less than 1 foot high D layer Bryophytes and lichens (b) by decreasing constancy values within each layer. (c) by decreasing average species significance within each constancy class. 4. Species ratings for species significance and sociab i l i t y follow the scales given in Appendix I and are given by two figures (e.g. 5.1). 333 5. Constancy and average species significance value ratings are l i s t e d in the tables for a l l species except those l i s t e d as \"Sporadic Species\". These occurred in only one plot so no averages are obtainable. For species occurring in two, or more, layers, only one rating was made. Average species significance values for individual species was calculated by totalling their species significance values and dividing by the number of plots in the association. Constancy was rated on a linear scale of five classes as indicated below. Constancy Class Species occurring on % of plots V 81-100 IV 61-80 III 41-60 II 21-40 I 1-20 B. Environment Tables Nomenclature of the ecosystem units and arrangement of the plots within any ecosystem unit i s described in section A, notes 1 and 2. 1. Locality i s designated as follows: Fraser Plateau - FP Area North of Williams Lake (Fraser Basin) - WL Each plot i s located by degrees west longitude and degrees north latitude. 2. Landform describes the land surface topography where the plot i s located (e.g. depression, stream terrace, exposed slope, gully). 3. Relief shape describes the surface shape of the sample plot (i.e. hummocky, f l a t , straight, convex or concave). 4. Exposure refers to the direction the plot faces (i.e. N., NE , E, SE, S, SW, W, NW or neutral). 334 5. Slope gradient ( ) refers to the steepness of the plot, i.e. the inclination of the ground surface from the horizontal plane. 6. Layer coverage (%) refers to the area covered by the indicated layer as a percentage of the plot area. .7. Plot coverage (%) refers to the area covered by humus & l i t t e r , mineral s o i l , rock, water or decaying wood as a percentage of the plot area. 8. Hygrotope classes refer to the moisture status of plots studied i n the Cariboo Zone. The classes are related to topography, s o i l profile characteristics, drainage and levels of water table in the p r o f i l e , i f present. The descriptions of the classes used are as follows: C Hygrotope Class Xeric Subxeric Description Ridge tops and exposed slopes. Soils are well to rapidly drained with a minimum of surface runoff. The evapo*transpiration rate i s very high and the s o i l surface may crack from drying in the late summer. Protected slopes and shallow g u l l i e s . The soils are well drained and there i s some surface runoff. Moderate to high evapo-transpiration occurs at the s o i l surface. Submesic Mesic Subhygric Hygric Depressions, protected slopes, and base of exposed slopes. The soil s are medium textured, moderate to well drained and may occasionally have temporary seepage. The evapo-transpiration rate i s low. Medium textured soi l s with good drainage. Temporary seepage occurs in the lower part of the pr o f i l e in the early summer. The evapo-transpiration rate i s low. Lower parts of steep slopes or depressions. Soil drainage i s moderate and seepage occurs. Faint mottling may be present in the lower parts of the s o i l p r o f i l e . The evapo-transpiration rate i s very low. Edges of lakes and ponds, stream terraces and g l a c i a l stream depressions. Soil drainage is moderate to imperfect and free 335 Subhydric Hydric water i s present in the p r o f i l e for at least part of the year. Gleying i s evident. Edges of lakes and ponds, stream terraces and g l a c i a l stream depressions. Soil drainage is imperfect to impeded and free water is always present in the p r o f i l e . Strong gleying is evident. Lakes and alkaline ponds. Soil drainage i s impeded. Water level i s at or above the surface during the summer. 9. Trophotope classes refer to the nutrient status of plots studied in the Cariboo Zone. The classes are related to s o i l chemical characteristics, s o i l texture, topography, and vigor of dominant plants. Description of the classes used are as follows: Trophotope Class Hypereutrophic Eutrophic Permesotrophic Mesotrophic Description Depressions surrounding alkaline ponds which are continually being enriched by soluble salts. The s o i l i s fine textured with a high clay content. The exchangeable cations are present in very high concentrations and pH i s usually 8.0 or higher. Salt crusts may form on the s o i l surface i n late summer. Fine to medium textured soi l s usually with an Ah horizon. The exchangeable cations are present in high amounts, the cation exchange capacity i s high, and the s o i l reaction i s alkaline. Growth of grassland species i s excellent. Fine to medium textured s o i l s , usually with humus incorporation in the upper mineral horizons. The cation exchange capacity i s high and the exchangeable cations are present in high amounts. Nutritional enrich-ment through seepage or flooding may occur. The s o i l reaction is circumneutral to alkaline. Growth of grassland species is good and tree growth i s excellent. Medium to coarse textured s o i l s . Exchange-able cations are present in moderate to high amounts and the soils are not enriched through seepage. The s o i l reaction i s weakly acidic to alkaline. Growth of trees i s good. 336 Submesotrophic Soil i s coarse textured and easily leached. Exchangeable cations are present in low amounts and the cation exchange capacity i s low. The s o i l reaction is circumneutral to acidic. Growth of trees i s poor. Oligotrophic Soils are heavily leached and often coarse textured. Exchangeable cations are present in very low amounts, cation exchange capacity i s very low and the s o i l reaction i s acidic. Growth of trees i s very poor (not encountered in this study). 10. Erosion i s an estimate of the operative erosion agent (either water or wind) and the degree of destruction of the land surface (i.e. n i l , slight, moderate or extreme). 11. Drainage i s an estimate, based largely on s o i l texture and topography, of the moisture condition of the plots during the summer (i.e. impeded, imperfect, moderate, well or rapid). 12. Parent material refers to the geological substrata from which the s o i l has been formed (i.e. alluvium, gl a c i a l d r i f t , sediments, aeolian deposits, or aeolian deposit over gla c i a l d r i f t ) . C. Soil Texture Tables Nomenclature of the ecosystem units and arrangement of the plots within any ecosystem unit i s described in section A, notes 1 and 2. 1. Textural classes are those currently accepted by the United States Department of Agriculture and are abbreviated as follows: Abbreviation Textural Class C Clay SiC S i l t y Clay SiCL S i l t y clay loam CL Clay loam SC Sandy clay SCL Sandy clay loam SiL S i l t Loam L Loam 337 Si S i l t SL Sandy loam LS Loamy sand S Sand 2. The clay, s i l t and sand fractions are determined on the less than 2mm size fraction of the s o i l and follow the classification of the United States Department of Agriculture, (sand = 2.00 to 0.05mm; s i l t = 0.05 to 0.002mm,-clay, less than 0.002mm). 3. Coarse fragments refer to the presence of particles in the s o i l greater than 2mm in size. The classes used with their abbreviations are as follows: Abbreviation Class g. gravels - 2mm - 3 inches c. cobbles - 3 inches - 10 inches s. stones > 10 inches D. Soil Chemical Analysis Nomenclature of the Ecosystem Units and arrangement of plots within any ecosystem unit i s described in Section A, Notes 1 and 2. 1. Chemical analyses were made on the less than 2mm size fraction of the s o i l . 2. Carbon and nitrogen are given as percentages. Phosphorus i s given in parts per million. Sodium, potassium, calcium, magnesium and cation exchange capacity are. given in milli-equivalents per 100 grams of s o i l . 338 Appendix IV Summary of Temperature Data f o r the M i c r o c l i m a t i c Stations Table IV-A - Weekly Temperature summaries f o r the M i c r o c l i m a t i c S t a t i o n s . Table IV-B - Monthly Temperature summaries f o r the M i c r o c l i m a t i c Stations. 339 Table IV-A Weekly Temperature Summaries for the Microclimatic Stations zation Avg Max Avg Mean Avg Min Max Min Avg Max Avg Mean Avg Min Max ' Min May 26 - June 1, 1968 June 2 - June 8 , 1968 1 69 57 44 74 38 69 - 44 72 36 2 67 55 43 72 36 69 56 43 78 35 3 68 56 43 72 38 68 56 44 70 36 4 66 55 44 70 39 67 56 45 69 38 5 66 55 43 71 38 67 55 42 68 35 6 68 54 40 73 34 69 55 41 71 32 7 60 49 39 64 34 60 49 38 62 32 8 55 44 33 58 30 56 46 35 58 28 9 62 47 31 66 27 61 - 34 64 26 10 59 46 33 64 29 60 48 36 61 28 June 9 - June 15, 1968 June 16 - June 22, 1968 1 78 62 45 84 38 75 60 44 80 40 2 76 60 45 79 38 73 58 43 78 40 3 76 61 45 83 38 73 59 44 80 40 4 75 60 45 80 40 72 59 45 78 41 5 75 59 44 81 38 71 57 43 77 40 6 76 59 42 82 36 75 58 40 80 37 7 68 54 40 74 34 66 52 38 73 34 8 65 50 35 78 28 61 48 34 67 31 9 68 50 32 73 24 67 49 31 73 28 10 68 51 33 73 27 65 50 34 74 29 June 23 - June 29 , 1968 June 30 \u00E2\u0080\u00A2 - July 6, 1968 1 78 62 46 80 38 80 65 50 90 37 2 74 60 45 78 37 77 63 49 84 37 3 76 61 46 79 40 78 64 50 90 36 4 75 61 47 78 41 76 64 51 84 40 5 74 60 45 76 40 77 63 49 86 36 6 78 61 44 80 36 77 62 47 87 35 7 69 55 41 72 36 72 58 45 84 32 8 64 50 37 68 29 66 54 42 72 29 9 71 53 34 78 26 68 54 40 74 26 10 68 53 37 73 30 _ - - - -Table IV-A (continued) Avg Avg Avg Station Max Mean Min Max Min Jul y 7 - July 1 3 , 1968 1 95 73 52 100 44 2 90 70 50 93 42 3 94 73 52 100 44 4 92 73 54 98 47 5 91 71 51 98 44 6 94 72 50 100 41 7 89 68 47 95 38 8 78 59 39 84 32 9 82 59 .36 86 30 10 - - - - -J u l y 21 - July 27 , 1968 1 77 63 50 82 42 2 73 61 49 80 42 3 73 61 49 78 45 4 73 62 51 80 46 5 71 . 60 49 78 44 6 74 61 48 84 41 7 66 55 44 78 40 8 59 50 41 62 34 9 66 53 40 77 30 10 65 53 42 70 32 August 4 - August 10, 1 968 1 93 \u00E2\u0080\u00A2 75 58 98 46 2 90 73 57 94 47 3 86 71 56 95 46 4 90 73 56 96 50 5 87 71 56 91 48 6 92 73 55 97 43 7 83 67 51 88 44 8 78 61 44 83 37 9 81 61 42 84 36 10 83 65 47 86 40 340 Avg Avg Avg Max Mean Min Max. Min July 14 - Ju l y 20, 1 968 87 73 58 97 51 84 70 56 96 48 86 72 57 96 51 85 72 59 92 53 84 70 56 93 50 85 70 54 99 48 79 66 53 93 46 72 60 48 82 43 8 0 62 45 89 40 78 64 49 89 42 July 28 - August 3, 1968 86 71 57 98 50 83 69 54 94 50 83 69 54 96 49 83 70 56 94 52 81 67 54 91 50 86 70 54 97 49 76 63 49 88 46 69 57 45 81 40 77 \u00E2\u0080\u00A2 60 44 85 39 75 61 47 88 44 August 11 - August 1 7 , 196c 82 67 52 93 45 80 65 50 90 42 80 65 50 90 44 80 65 51 94 44 80 65 50 87 44 81 65 49 94 40 72 59 45 82 39 66 53 4 1 75 33 73 56 38 79 31 75 59 43* 83 36 Table IV-A (continued) 341 Avg Avg Avg Avg Avg Avg bation Max Mean i Min Max Min Max Mean Min Max Min August 1\u00C2\u00A3 ! - August 24, 1968 August 25 - August 31, 1968 1 77 66 55 86 51 72 61 49 80 45 2 73 63 53 83 48 70 59 48 78 42 3 73 64 54 85 50 70 59 48 78 43 4 72 63 54 82 51 69 59 49 76 44 5 71 63 54 80 50 70 59 48 79 42 6 73 63 52 84 48 71 59 47 78 41 7 69 59 49 78 47 62 52 43 68 38 8 62 55 48 70 42 58 50 41 64 36 9 68 57 46 77 40 63 50 38 70 32 10 69 59 49 77 44 63 53 43 70 37 September 1 - September 7, 1968 September 8 - September 14, 19( 1 74 59 44 82 38 79 65 50 90 43 2 71 57 43 79 40 75 61 48 86 40 3 72 58 45 80 41 76 63 49 86 40 4 73 59 45 78 42 75 63 51 84 42 5 68 56 44 76 41 72 60 49 81 40 6 73 58 43 82 38 75 61 47 85 39 7 61 51 41 68 37 67 56 45 77 37 8 60 48 36 66 34 64 52 40 72 32 9 65 49 34 70 31 68 \u00E2\u0080\u00A2 53 38 78 30 10 66 51 37 72 34 69 55 42 78 33 September 15 - September 21, 1968 1 75 62 49 84 42 2 73 60 47 83 41 3 73 61 49 82 42 4 72 61 51 82 47 5 70 60 49 78 45 6 72 60 47 82 42 7 66 56 46 74 42 8 62 53 43 69 37 9 67 54 41 74 35 10 67 54 40 74 33 342 Table IV-B Monthly Temperature Summaries f o r the Microclimatic Stations tation Avg Max Avg Mean Avg Min Max Min Avg Max Avg Mean Avg Min Max Min May 26 - May 31, 1968 June i, 1968 1 69 - 43 74 36 78 62 46 90 37 2 69 55 42 78 35 75 60 46 84 37 3 68 55 43 72 36 76 61 46 90 36 4 67 55 43 70 38 75 61 47 84 40 5 66 54 42 71 35 74 60 45 86 36 6 69 54 39 73 32 77 60 44 87 35 7 60 48 37 64 32 69 55 41 84 32 8 56 45 34 58 28 64 50 37 78 28 9 61 - 32 66 26 68 51 35 78 24 10 60 47 34 64 28 70 - 37 77 27 Jul y , 1968 August, 1968 1 87 71 55 100 42 78 65 51 98 38 2 83 68 53 96 42 75 63 50 94 40 3 84 69 53 100 44 75 63 50 95 41 4 84 69 55 98 46 75 63 51 96 42 5 82 68 53 98 44 74 62 50 91 41 6 85 68 52 100 41 76 63 49 97 38 7 78 63 49 95 40 68 57 46 88 37 8 70 57 43 84 34 63 53 42 83 33 9 77 59 41 89 30 69 ' 54 39 84 31 10 74 59 44 90 32 70 57 44 86 34 September 1 - September 14, 1968 1 78 '64 50 90 42 2 74 61 48 86 40 3 75 62 49 86 40 4 74 62 51 84 42 5 72 60 49 81 40 6 74 61 47 85 39 7 67 56 45 77 37 8 63 52 41 72 32 9 68 53 39 78 30 10 68 55 41 78 33 "@en . "Thesis/Dissertation"@en . "10.14288/1.0093383"@en . "eng"@en . "Botany"@en . "Vancouver : University of British Columbia Library"@en . "University of British Columbia"@en . "For non-commercial purposes only, such as research, private study and education. Additional conditions apply, see Terms of Use https://open.library.ubc.ca/terms_of_use."@en . "Graduate"@en . "Plant associations of the Cariboo - Aspen - Lodgepole pine - Douglas-Fir parkland zone"@en . "Text"@en . "http://hdl.handle.net/2429/34693"@en .