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The paleoecology of a raised bog and associated deltaic sediments of the Fraser River Delta 1977

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THE PALEOECOLOGY OF A RAISED BOG AND ASSOCIATED DELTAIC SEDIMENTS OF THE FRASER RIVER DELTA by RICHARD JOSEPH HEBDA B.Sc., McMaster University, 1973 A THESIS SUBMITTED IN PARTIAL FULFILLMENT OF THE REQUIREMENTS FOR THE DEGREE OF DOCTOR OF PHILOSOPHY i n THE FACULTY OF GRADUATE STUDIES DEPARTMENT OF BOTANY We accept t h i s thesis as conforming to the required standard THE UNIVERSITY OF BRITISH COLUMBIA February, 1977 (c) Richard Joseph Hebda, 1977 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 degree at the U n i v e r s i t y o f B r i t i s h Co lumb ia , I a g ree that 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 tudy . I f u r t h e r agree 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 purposes may be g r a n t e d by the Head o f my Department o r 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 tha 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 t h e s i s f o r f i n a n c i a l g a i n s h a l l not be al1 owed w i thout my w r i t t e n p e r m i s s i o n . Department o f BOTANY The U n i v e r s i t y o f B r i t i s h Co lumbia 2075 Wesbrook Place Vancouver, Canada V6T 1W5 Date March 23, 1977 ABSTRACT In t h i s study, three cores obtained from Burns Bog just south of the Fraser River i n Delta, B r i t i s h Columbia, were analyzed p a l y n o l o g i c a l l y . The paleoecology of the bog was reconstructed from the r e s u l t s of these analyses, together with data from vegetation studies of the bog, p o l l e n r a i n and surface p o l l e n spectrum i n v e s t i g a t i o n s of selected wetland environ- ments, as well as p o l l e n tetrad and p o l l e n p r o d u c t i v i t y studies of bog ericads. The vegetation of Burns Bog was sampled by estimating species cover i n 2 s e l e c t i v e l y placed 100 m quadrats. These f i e l d data were used i n combina- t i o n with an a i r photographic mosaic to map the eight vegetation types of the area. The palynomorph " f i n g e r p r i n t s " of selected wetland environments, determined from p o l l e n r a i n and surface p o l l e n spectrum studies, were used to recognize analogous phases recorded i n cores. Tetrad diameter and p o l l e n p r o d u c t i v i t y data for bog ericads a s s i s t e d i n recognizing e c o l o g i c a l l y s i g n i f i c a n t e r i c a d species that distinguished wet and dry r a i s e d bog phases. The study shows that Burns Bog has developed on Fraser River d e l t a i c deposits which appeared above sea l e v e l j u s t a f t e r 5,000 years BP. The seemingly synchronous emergence of the three core s i t e s and a l o c a l i t y i n adjacent Boundary Bay i n d i c a t e a p o s s i b l e r e l a t i v e sea l e v e l decrease at t h i s time. The s i l t y emergent sediments are characterized by high percent- ages of Pinus and Picea p o l l e n deposited by r i v e r water, and Cyperaceae p o l l e n from l o c a l Scirpus and Carex stands. Following t h i s emergence, sedges colonized the area, forming a sedge peat containing abundant Cyper- aceae p o l l e n . At the western end of the bog, a s a l t marsh developed i i i (4,125 + 110 BP) i n response to a marine advance. This was possibly caused by a shut-off of fresh-brackish water from the Fraser River when the d e l t a reached Point Roberts. In the eastern section of the bog, at the foot of Panorama Ridge, the sedge phase was only transient.- A Myrica-Spiraea- Lysichitum swamp developed, remaining u n t i l very recently. A f t e r the sedge phase i n the c e n t r a l part of the bog, Myrica and Spiraea-thickets appeared; these were subsequently replaced by Sphagnum bog at 2,925 ± 85 years BP. In the western end of the bog, sedges were replaced by heaths, predominantly Ledum. At the foot of Panorama Ridge, Sphagnum a r r i v e d very recently. Pines seem to have invaded a l l s i t e s at the 2.00 m l e v e l . The AP p o l l e n spectrum shows that the regional upland vegetation remain- ed unchanged throughout the h i s t o r y of Burns Bog u n t i l s e t t l e r s cleared the f o r e s t s . On the d e l t a , however, fl u c t u a t i o n s i n alder p o l l e n were probably associated with alder c o l o n i z a t i o n of levees and swamps near the channels. F i r e has played an important r o l e i n bog ecology. Natural Sphagnum accumulation processes are modified because f i r e destroys the vegetation of s l i g h t l y higher, dry s i t e s . Unburned wet depressions then become centers of peat accumulation. These s i t e s eventually r i s e above the surrounding burned areas, which are converted to depressions. A model for r a i s e d bog development i s proposed for the Fraser Lowland. The prograding d e l t a - f r o n t i s colonized by emergent aquatics growing on s i l t s . This phase i s followed by the advent of a sedge swamp perhaps con- t a i n i n g some wetland grasses. Eventually, shrubs such as Myrica and Spiraea begin to appear, accompanied i n the l a t e r stages by Ledum groenlandicum. Increased a c i d i t y of the substrate due to peat accumulation promotes i v Sphagnum, which eventually takes over and r e s u l t s i n the establishment of ra i s e d bog conditions. This study, the f i r s t d e t a i l e d o u t l i n e of r a i s e d bog development i n western North America, provides a framework f o r further i n v e s t i g a t i o n s of bogs i n the area. TABLE OF CONTENTS PAGE LIST OF TABLES LIST OF FIGURES ACKNOWLEDGEMENTS CHAPTER 1: INTRODUCTION The Study Area Physiology and Geology S o i l s Climate Hydrology Regional Vegetation Previous Studies CHAPTER 2: THE VEGETATION OF BURNS BOG AND OBSERVATIONS ON PLANT ECOLOGY 12 Introduction 12 The Vegetation Types of Burns Bog 12 Methods 12 Results 15 Heathland 15 Pine Woodland 21 Birc h Woodland 22 Spiraea Brushland 22 Mixed Coniferous Woodland 23 Salmonberry Bushland 25 Alder Woodland 26 Unvegetated Peatland 27 The O r i g i n a l Vegetation of the Burns Bog Area 28 The Role of F i r e i n Burns Bog 32 The e f f e c t of Sphagnum on Pine Growth 36 Summary 38 CHAPTER 3: BOG ERICACEAE: POLLEN TETRAD SIZE, POLLEN PRODUCTIVITY 39 Tetrad Diameter of Bog Ericaceae and Empetrum nigrum 39 Appli c a t i o n of Results 43 Pollen P r o d u c t i v i t y of Bog Ericaceae 44 i x x x i v 1 3 3 7 7 8 9 10 v i (Table of Contents cont'd) PAGE CHAPTER, 4:. POLLEN DEPOSITION IN WETLAND ENVIRONMENTS OF THE FRASER RIVER DELTA 47 Methods 48 Modern Pollen Rain 48 Surface Samples 50 Results 51 Sit e s from the Southern Periphery of Burns Bog 51 Sit e s from the I n t e r i o r of Burns Bog 55 Coastal S i t e s from Boundary Bay 60 F l u v i a l Environments 61 Summary and Conclusions 66 CHAPTER 5: CORE CBB FROM CENTRAL BURNS BOG 96 Introduction 96 Methods 96 Pollen Diagrams 97 Results and Discussions 99 Palynomorph and Macrofossil Zonation for Core CBB 101 Zone CBB - I 101 Zone CBB - II 104 Zone CBB - III 106 Zone CBB - IV 108 Summary and Conclusions 111 CHAPTER 6: CORE BBDC FROM WESTERN BURNS BOG 117 Introduction 117 Methods 117 Absolute P o l l e n 117 Sediment Analysis 120 Results and Discussion 121 Stratigraphy 121 Sedimentology 121 Absolute Pollen: Results and Discussion 126 Zone BBDC - I 126 Zone BBDC - II 126 Zone BBDC - I I I 127 Zone BBDC - IV 127 Zone BBDC - V 127 Zone BBDC - VI 127 Pollen and Macrofossil Zonation 128 Zone BBDC - I 128 Zone BBDC - II 129 Zone BBDC - III 130 v i i (Table of Contents cont'd) PAGE Zone BBDC - IV 130 Zone BBDC - V 131 Zone BBDC - VI 132 Summary 134 CHAPTER 7: CORE DNR FROM EASTERN BURNS BOG 141 Introduction 141 Methods 143 Results and Discussion 143 Stratigraphy and Radiocarbon Dating 143 Pollen and Macrofossil Zonation 143 Zone DNR - I 145 Zone DNR - II 146 Zone DNR - III 148 Summary 149 CHAPTER 8: SYNTHESIS, DISCUSSION AND SUMMARY 155 Introduction 155 Synthesis 155 The Or i g i n and Growth of Burns Bog 155 Delta-Front Phase 155 Shrub and Heathland Phase 157 Sphagnum Bog Phase 158 F i r e Horizons 158 Burns Bog Development i n Relation to Other Raised Bogs i n the Fraser River Delta 160 A General Model for Raised Bog Development i n the Fraser Delta 161 Colonization Phase 161 Sedge-Grass Phase 161 Shrub Phase 161 Sphagnum Bog Phase 163 Discussion Comparison of Fraser River Delta Raised Bog Development with Other Raised Bog Sequences 164 The Role of the Raised Bog i n Fraser River Delta Evolution 166 The Relationship of the Main Paleoecologic Events i n Burns Bog to the Development of the Fraser Delta 168 Sea Level Changes 168 River Channel Changes 171 V l l l (Table of Contents cont'd) Ap p l i c a t i o n of the Study Thesis Summary REFERENCES APPENDIX 1: Species Composition of the Vegetation Types of Burns Bog, Delta, B. C. APPENDIX 2: Computer Programs Used to Calculate Relative and Absolute P o l l e n Values f o r Computer Plot t e d Diagrams \ 2a - Program for Ca l c u l a t i n g Relative Pollen Frequencies 2b - Program for C a l c u l a t i n g Absolute Poll e n Concentrations Per Cubic Centimeter APPENDIX 3: Selected Palynomorphs Recovered from Burns Bog Sediments IX LIST OF TABLES TABLE PAGE 1. Tetrad diameters of major ericad species i n Burns Bog, Delta, B. C. 41 2. Pollen t e t r a d p r o d u c t i v i t y of major bog Ericaceae, Burns Bog, Delta, B. C. 46 3. Non-vascular plant palynomorphs from surface samples c o l l e c t e d from wetland environments i n the Fraser River Delta. 95 4. S a n d : s i l t : c l a y r a t i o s , core BBDC, Burns Bog, Delta, B. C. 123 5. Average species cover f o r the vegetation types of Burns Bog, Delta, B. C. 186 •-•.X LIST OF FIGURES FIGURE PAGE 1. Map showing the l o c a t i o n of Burns Bog, Delta, B r i t i s h Columbia. 4 2. S u r f i c i a l geology of the Burns Bog study area. 6 2 2 3. Arrangement of the 100 m and 1 m quadrats used f o r vegetation analysis i n Burns Bog. 14 4. Vegetation types of Burns Bog, Delta, (in pocket B r i t i s h Columbia at back) 5. Photographs i l l u s t r a t i n g the major vegetation types of Burns Bog. 16, 17 6. O r i g i n a l vegetation of the Burns Bog area (1873) 30 7. Fire-induced hummock-hollow c y c l i n g i n Burns Bog, Delta, B r i t i s h Columbia. 34 8. Relationship of pine growth to Sphagnum hummock formation. 37 9. D i s t r i b u t i o n of te t r a d s i z e s of bog Ericaceae and Empetrum nigrum. 42 10. Location of the surface sample and core s i t e s i n the Fraser Delta. 49 11. Diagrams f or s i t e A, open Betula o c c i d e n t a l i s woodland with Pteridium aquilinum understorey; a) p o l l e n r a i n diagram 69 b) surface p o l l e n spectrum, c) species cover 70 12. Diagrams f o r s i t e B, Ledum groenlandicum heathland i n Pinus contorta woodland; a) p o l l e n r a i n diagram 71 b) surface p o l l e n spectrum, c) species cover 72 13. Diagrams for s i t e C, Ledum groenlandicum heathland i n Pinus contorta woodland; a) p o l l e n r a i n diagram 73 b) surface p o l l e n spectrum, c) species cover 74 14. Diagrams for s i t e D, Spiraea d o u g l a s i i t h i c k e t s i n open Betula o c c i d e n t a l i s woodland; a) p o l l e n r a i n diagram 75 b) surface p o l l e n spectrum, c) species cover 76 x i ( L i s t of Figures cont'd) FIGURE PAGE 15. Diagrams f or s i t e H, Pinus contorta woodland; a) p o l l e n r a i n diagram 77 b) surface p o l l e n spectrum, c) species cover 78 16. Diagrams for s i t e I, Sphagnum heathland; a) p o l l e n r a i n diagram 79 b) surface p o l l e n spectrum, c) species cover 80 17. P o l l e n r a i n diagram f o r s i t e R, Sphagnum heathland. 81 18. Diagrams f or s i t e G, Sphagnum heathland c l e a r i n g i n Pinus contorta woodland; a) p o l l e n r a i n diagram 82 b) surface p o l l e n spectrum, c) species cover 83 19. Surface p o l l e n spectrum f or s i t e NP, "Nuphar pond", i n Sphagnum heathland. 84 21. Diagrams f or s i t e E, Chenopodiaceae s a l t marsh; a) p o l l e n r a i n diagram 85 b) surface p o l l e n spectrum, c) species cover 86 22. Diagrams for s i t e F, coastal grassland; a) p o l l e n r a i n diagram 87 b) surface p o l l e n spectrum, c) species cover 88 23. Surface p o l l e n spectra of r i v e r marsh s i t e s ; a) S i t e L - l , Menyanthes-Lysichitum-Gramineae 89 b.) S i t e L-2, Equisetum-Scirpus-Sagittaria-Alisma 89 c) S i t e L-3, Scirpus-Sagittaria-Equisetum 90 24. Surface p o l l e n spectra of r i v e r swamp s i t e s ; a) S i t e L-4, r i v e r swamp: Typha-Equisetum 91 b) S i t e L-4, r i v e r swamp: Equisetum- Lysichitum-Scirpus 91 25. Vegetation zones of the Lulu Island foreshore. 92 26. Surface p o l l e n spectra from d e l t a - f r o n t marshes; DF 1, 2, 3 & 4; a) S i t e DF 1 & 2, Scirpus zone 93 b) S i t e DF 3, Typha zone 93 c) S i t e DF 4, Carex-Potentilla zone 93 27. Pollen diagram of major species i n short core DF—5, Carex- P o t e n t i l l a zone, i n t e r t i d a l d e l t a - f r o n t . 94 X l l ( L i s t of Figures cont'd) FIGURE PAGE 28. Stratigraphy and macrofossils of core CBB 100 29. Pol l e n diagram f o r core CBB, Burns Bog, Delta, B r i t i s h Columbia 112 30. Arboreal p o l l e n diagram excluding pine f o r core CBB, Burns Bog, Delta, B. C. 113 31. Arboreal p o l l e n diagram f or core CBB, Delta, B. C. 114 32. Non-arboreal p o l l e n diagram for core CBB, Burns Bog, Delta, B. C. 115 33. Palynomorph diagram, core CBB. 116 34. Stratigraphy and macrofossils of core BBDC. 122 35. S a n d : s i l t : c l a y r a t i o t r i a n g l e f o r selected samples from core BBDC 123 36. Absolute p o l l e n and spore concentrations f o r core BBDC, Burns Bog, Delta, B. C. 125 37. Pol l e n diagram f o r core BBDC, Burns Bog, Delta, B. C. 135 38. Arboreal p o l l e n diagram excluding pine f o r core BBDC, Burns Bog, Delta, B. C. 136 39. Arboreal p o l l e n diagram f o r core BBDC, Burns Bog, Delta, B. C. 137 40. Non-arboreal p o l l e n diagram f or core BBDC, Burns Bog, Delta, B. C. 138 41. Size range composition of e r i c a d spectrum, core BBDC, Burns Bog, Delta, B. C. 139 42. Palynomorph diagram, core BBDC. 140 43. V e r t i c a l section of eastern Burns Bog (core DNR) showing shallow basin i n the foot of Panorama Ridge. 142 44. Stratigraphy and macrofossils of core DNR. 144 45. P o l l e n diagram f or core DNR, Burns Bog, Delta, B. C. 151 X l l l ( L i s t of Figures cont'd) FIGURE PAGE 46. Arboreal p o l l e n diagram for core DNR, Burns Bog, Delta, B. C. 152 47. Non-arboreal p o l l e n diagram for core DNR, Burns Bog, Delta, B. C. 153 48. Palynomorph diagram, core DNR. 154 49. C o r r e l a t i o n of the three cores from Burns Bog. 156 50. Proposed model for r a i s e d bog development i n the Fraser Delta. 162 51. Selected palynomorphs recovered from Burns Bog sediments. 201, 202 x i v ACKNOWLEDGEMENTS I am indedted to many i n d i v i d u a l s who a s s i s t e d with the tec h n i c a l aspects of t h i s work and gave of t h e i r time f o r encouragement and discus- sion. F i n a n c i a l support f o r the pro j e c t was provided by the National Research Council of Canada through grants to Dr. G. E. Rouse and three scholarships to me. A l l e n Banner a s s i s t e d i n the f i e l d and i n the laboratory. Joan M i l l e r also helped with laboratory preparations and drew some of the fi g u r e s . Wayne G. Biggs, currently with Entech Environmental Consultants Limited, was a welcome co-worker i n the study of Burns Bog vegetation. Thanks are expressed to Western Peat Moss Limited for allowing access to the parts of the bog under t h e i r c o n t r o l . I would l i k e to thank the many graduate students of the Botany Depart- ment of the Univ e r s i t y of B r i t i s h Columbia who to l e r a t e d the ravings of the "bog man" and provided welcome company i n the f i e l d . I wish also to thank L e s l i e Borleske who typed the f i n a l d r a f t of the t h e s i s . Special thanks go to the members of my thesis committee: Drs. R. L. Taylor, F. R. Ganders (Botany Department, Uni v e r s i t y of B r i t i s h Columbia), W. H. Mathews (Geology Department, Uni v e r s i t y of B r i t i s h Columbia), and R. W. Mathewes (Biology Department, Simon Fraser U n i v e r s i t y ) . Dr. W. B. Schofield, also a committee member, deserves p a r t i c u l a r thanks f o r i d e n t i f y - ing the numerous bryophytes brought i n from the bog. F i n a l l y , I am immeasurably g r a t e f u l to my supervisor, Dr. G. E. Rouse, whose pa t i e n t discussion, encouragement and i n s p i r a t i o n made my years as a graduate student a most e x c i t i n g experience. 1 THE PALEOECOLOGY OF A RAISED BOG AND ASSOCIATED DELTAIC SEDIMENTS OF THE FRASER RIVER DELTA, BRITISH COLUMBIA CHAPTER 1: INTRODUCTION The coastal zone of western North America contains many r a i s e d (ombrogenous) bogs. The paleoecology of these bogs, i n contrast to Euro- pean ra i s e d bogs (Moore and Bellamy, 1973; Godwin, 1975), has been studied only s u p e r f i c i a l l y . Among the f i r s t i n vestigators i n western North America was Anrep (1928), who evaluated peat reserves i n southwestern B r i t i s h Columbia. Later Rigg and Richardson (1938) investigated bog ecology and peat stratigraphy i n some raised bogs on the west coast. Hansen (1947) and Heusser (1960) c a r r i e d out p a l y n o l o g i c a l investigations of bogs for the purposes of reconstructing regional f o r e s t h i s t o r y and c l i m a t i c changes. U n t i l now, however, there has been no concerted e f f o r t which combines both current vegetation studies and palynologic and s t r a t i g r a p h i c approaches to elucidate the development of these bogs. The main objective of t h i s thesis i s to provide the f i r s t d e t a i l e d o u t l i n e of the paleoecology of one of these r a i s e d bogs, Burns Bog, from the Fraser River Delta of southwestern B r i t i s h Columbia (Fig. 1). The main thrust of the present study i s to apply palynologic and other paleoecologic techniques to reconstructing l o c a l vegetation h i s t o r y , rather than i n t e r - p r e t i n g p o s t - g l a c i a l , regional f o r e s t succession and c l i m a t i c changes. The l a t t e r have already been considered for the area by Mathewes (1973) and Mathewes and Rouse (1975), from studies of lake sediments. In addition, t h i s study intends to give f a i r l y p recise reconstruction of lower mainland 2 peatland and d e l t a i c environments. These are based on m i c r o f o s s i l assem- blages preserved i n three cores from the bog (Ch. 5-7) , as well as on data obtained from i n v e s t i g a t i o n of pollen-vegetation r e l a t i o n s h i p s . The l a t t e r are based on studies of p o l l e n - r a i n and surface samples of what are con- sidered to be modern analogous communities (Ch. 4) together with analyses of plant assemblages within the Burns Bog area (Ch. 2). The present i n v e s t i g a t i o n was i n i t i a t e d i n Burns Bog (Delta Bog of Anrep (1928), Great Delta Bog of Osvald (1933) and Rigg and Richardson (1938)) for a number of reasons. Except for one preliminary i n v e s t i g a t i o n by Hansen (1940) on adjacent Lulu Island, l i t t l e had been reported on the e c o l o g i c a l successions within bogs of the Fraser River Delta. Although p a r t l y disturbed, t h i s bog contains enough areas of r e l a t i v e l y natural peatland to serve as a useful study area. This provided i n i t i a l l y wide scope for analysis of vegetation-sediment r e l a t i o n s within a region of complex deposition, water conditions, and diverse plant assemblages. F i n a l l y , factors such as human population growth, urban development, and peat e x p l o i t a t i o n have been inc r e a s i n g l y i n t e r f e r i n g with the bog ecosystem and r e s u l t i n g i n the destruction of large sections of the bog; thus informa- t i o n from c e r t a i n areas had to be obtained before s i t e s were permanently l o s t . Investigation of Burns Bog paleoecology could be expected to shed l i g h t on a number of other basic problems. Included are those problems r e l a t e d to d e l t a formation such as sedimentation, rate of development, age, channel changes, and sea l e v e l changes, as well as those r e l a t e d to bog development such as the sequence, duration and nature of plant communities 3 involved i n r a i s e d bog formation, the nature of t r a n s i t i o n s , and the r o l e of f i r e . Increased i n s i g h t into these problems would be useful i n p r e d i c t i n g the natural development of current vegetation i n the Fraser River Delta and foreseeing the e f f e c t of disturbance such as f i r e and drainage on the bog ecosystem. I t would also provide a h i s t o r i c a l , environmental framework for i n t e r p r e t a t i o n of archaeological s i t e s i n the v i c i n i t y . The Study Area Physiography and Geology: Burns Bog ( l a t i t u d e 49°08'N and longitude 123°00'W) occupies approxi- mately 4,000 hectares of the southern h a l f of the Fraser River Delta i n the Corporation of Delta (Fig. 1). Burns Bog and the Corporation of Delta l i e within the Fraser Lowland subdivision of the Coastal Trough Physiographic Region (Luttmerding and Sprout, 1969). The western end of the Fraser Low- land containing Burns Bog and the Fraser River Delta occupy the northeast- ern corner of Whatcom Basin, a large . subsiding trough that has been receiv- ing sediments at l e a s t since the Upper Cretaceous (Rouse et ê L. , 1975). Since then the surrounding area has been subjected to considerable t e c t o n i c and mountain b u i l d i n g a c t i v i t y with the u p l i f t of the Coast Mountains i n the l a t e T e r t i a r y (Roddick, 1965). In the l a t e Pleistocene, the Fraser Lowland was covered by some 1,500 m of i c e during the maximum of the Vashon g l a c i a t i o n (Mathews et a l . , 1970). Deglaciation of the area began about 13,000 years ago (Mathews et a l . , 1970), with the Burns Bog region i c e - f r e e by about 12,600 BP (White Rock, B. C. 12,625 ± 450, IGSC6 (Walton et a l . , 1961), Point Roberts, B. C. 12,600 ± 170, IGSC248 (Trautman and Walton, 1962)). A f t e r i c e r e t r e a t and during subsequent sea l e v e l readjustments from 10,000- 9,000 BP (Blunden, 1975), the Fraser River began dumping sediments i n t o the 4 123̂ V A N C O U V E R BURNABY 5 area occupied by the present f l o o d - p l a i n . Around 10,000 BP the Fraser River penetrated through the Port Mann gap to the S t r a i t of Georgia (Blunden, 1975). Subsequently the active Fraser River d e l t a - f r o n t advanced at a rate of 9 m per year (Mathews and Shepard, 1962) and d e l t a i c sediments b u i l t up to the point where the Island of Point Roberts was joined to the mainland (Blunden, 1975). The s u r f i c i a l geology of the Burns Bog area (Fig, 2) has been mapped by Armstrong (1956, 1957). The east side of the bog i s bordered by Panorama Ridge, part of the Surrey Upland, reaching elevations of 80 m. I t consists of g l a c i a l l y derived outwash sands and gravels (Armstrong, 1957). Extensive well-sorted pebble beaches appear to have formed along the bottom portion of the westward slope of Panorama Ridge (Luttmerding and Sprout, 1969). On the south side of the bog, there are s i l t y clays and sand, i n places covered by shallow layers of peat (Luttmerding and Sprout, 1969). The s a l t marshes and t i d a l f l a t s of Boundary Bay l i e d i r e c t l y to the south of these deposits (Kellerhals and Murray, 1969). S a l t marsh peats exposed by erosion i n Boundary Bay were radiocarbon dated at 4,350 ± 100 years BP (Kellerhals and Murray, 1969). To the west of the bog up to 4 m of s i l t y d e l t a i c sediments, of marine and non-marine o r i g i n , o v e r l i e f i n e to medium sands. These s i l t y deposits e x h i b i t a gently undulating topography (Armstrong, 1956). An abandoned slough, Crescent Slough, defines the western edge of Burns Bog (Luttmerding and Sprout, 1969). North of the bog, the South Arm of the Fraser River i s flanked by both natural and a r t i f i c i a l levees. Between the r i v e r and the bog, shallow s i l t s blanket f i n e to medium sand (Armstrong, 1956). Blunden (1975) has suggested that t h i s channel of the Fraser River i s of recent o r i g i n and became established when the r i v e r broke through the F i g u r e - 2: S u r f i c i a l geo logy * o f the Burns Bog s tudy a r e a . t (8m) ove r c l a y e y s i l t l i t (2m) o v e r pent (lm) yey s i l t I ••I 1 S i l t (2m) over f i ne -med ium sand 1 y.C^ S i l t (4m) over f i ne -med ium sand ;.•/.•;•„•.'•'I F ine-medium sand Beach g r a v e l N i comek l S i l t / — C o l e b r o o k G r a v e l * i S u r r e y T U 1 * * HI P?.«*_jV| Newton Stoney C l a y * * *Modi f : led from Armstrong (1956,1957) . * * P l e i s t o c e n e d e p o s i t s o f Panorama R idge . N K 3 km 7 large Greater Lulu Island-Delta (Burns Bog) peat bog sometime a f t e r 2,500 years BP. S o i l s : Most of the d e l t a south of the South Arm of the Fraser River contains s o i l s of the g l e y s o l i c and organic orders (Luttmerding and Sprout, 1969). The poorly drained mineral deposits have developed i n a complex pattern dominated for the most part by s a l i n e o r t h i c and s a l i n e rego gleysols or humic eluviated g l e y s o l s . In the area immediately around and including the bog, the organic s o i l s range from sphagno-fibrisols to t y p i c humisols. Climate: The climate of the area can best be described as a modified maritime type, or a Csb Koeppen Mediterranean type (Hoos and Packman, 1974). Winters are usually mild and rainy with peak r a i n f a l l i n December, whereas summers are usually warm and dry with July being the d r i e s t month. The nearest c l i m a t o l o g i c a l s t a t i o n to Burns Bog i s located at Ladner, 1 km south of the study area. This s t a t i o n records long term normals of p r e c i p i t a t i o n , i n t e n s i t y of r a i n f a l l and temperature. The average annual p r e c i p i t a t i o n at Ladner i s 958 mm i n c l u d i n g an average annual snowfall of 37 cm. The annual average temperature i s 9.2°C; the July mean 16.7°C and the January mean 2.2°C ( B r i t i s h Columbia Department of A g r i c u l t u r e , 1971). The average number of f r o s t - f r e e days i s 183 (Luttmerding and Sprout, 1969). The p r e v a i l i n g winds blow from the southeast at an average v e l o c i t y of 12.9-16.4 km/hr (8-10 mph). Strong winds are not common, and are usually associated with the passage of a c t i v e weather disturbances blowing from the southeast or northwest. The r e l a t i v e humidity remains high throughout the 8 year, r a r e l y dropping below 60%, with readings of 80-90% common. The meteorological s t a t i o n at Vancouver International A i r p o r t approximately 15 km northwest of the study area, records an average of 1900 hours of bright sun per year (Hoos and Packman, 1974). The c l i m a t i c conditions of Burns Bog are believed to be s i m i l a r to those recorded at the Ladner s t a t i o n . R a i n f a l l i s probably s l i g h t l y higher as a r e s u l t of the increased orographic e f f e c t of the coastal mountains (Hoos and Packman, 1974). Hydrology: Topographic maps for the area (Department of Energy, Mines and Resources, 1970) i n d i c a t e that Burns Bog i s a dome-shaped mass of peat. The c e n t r a l cupola of the bog reaches about 5-6 m above mean sea l e v e l ( a . s . l . ) , whereas the perimeter i s about 1-2 m a . s . l . At the eastern end, peats onlap onto Panorama Ridge at about 5-6 m a . s . l . The o r i g i n a l drainage pattern of the bog i s unknown. The trenching of drainage ditches and extensive conversion of perip h e r a l areas to a g r i - c u l t u r a l use ea r l y i n the 20th century (Anrep, 1928) have o b l i t e r a t e d many of the perip h e r a l features that might have revealed t h i s pattern. Current drainage patterns are governed by a r t i f i c i a l ditches and pump-stations associated with the diking program of the southern Fraser River Delta. Generally, most of the northern p o r t i o n of the bog drains northward to the Fraser River; the northwestern corner drains westward i n t o Crescent Slough which empties i n t o the Fraser River. In the southern part, flow i s in t o the ditches that empty into Boundary Bay (Biggs, 1976). Along the north- eastern boundary, at the foot of Panorama Ridge, a sluggish stream previous- l y c a r r i e d water northward i n t o the Fraser River. This stream has now been 9 replaced by a d i t c h that follows a recently i n s t a l l e d (1974) trunk sewer, bu i l t more or le s s along the o l d stream course. During spring, when rains saturate the bog, water, presumably draining from the bog, often accumulates and moves slowly i n Spiraea thickets around the bog periphery. Flow i s commonly concentrated along cleared areas under B. C. Hydro power trans- miss ion l i n e s . In a way, these seem to function as a lagg. Water l e v e l s i n the bog can vary considerably. In the cupola, the water table fluctuates no more than .2 to .5m between the wet winters and the dry summers. In p e r i p h e r a l areas where l i t t l e Sphagnum grows, the water table (based on observations i n shallow ditches) drops by at l e a s t a meter during the l a t e summer dry s p e l l . Regional Vegetation: The Fraser River Delta, on which Burns Bog i s situated, l i e s within the Wetter Subzone of the Coastal Douglas-Fir Biogeoclimatic Zone of B r i t i s h Columbia (Krajina, 1969). Panorama Ridge and other upland areas around the bog are covered by vegetation more or le s s t y p i c a l of t h i s zone. Pseudo- tsuga menziesii i s the dominant tree i n mesic habitats, whereas Tsuga heterophylla predominates i n sub-hygric s i t e s (Krajina, 1969). Other important tree species of t h i s zone include: Thuja p l i c a t a Abies grandis Picea s i t c h e n s i s Pinus monticola (not present near Burns Bog) Arbutus menziesii (not present near Burns Bog) Prunus emarginata Populus balsamifera subsp. trichocarpa 10 Acer macrophyllum Acer circinatum. Alnus rubra grows i n disturbed areas; as a r e s u l t of man's dis r u p t i v e ac- t i v i t y i t i s now a major component of upland vegetation. The edaphic conditions of the immediate d e l t a are not s u i t a b l e f or the development of d o u g l a s - f i r f o r e s t . Currently, much of t h i s area i s covered by peat bog vegetation, farmland, and r i v e r or estuarine marshes and swamps. A narrow band of s a l t marsh vegetation borders Boundary Bay to the south of Burns Bog. The vegetation of Burns Bog i t s e l f i s treated i n Chapter 2. Previous Studies: The f i r s t i n v e s t i g a t i o n of Burns Bog deposits seems to be that of Anrep (1928), who produced an inventory of the economically valuable peat deposits of the lower mainland of B r i t i s h Columbia. He established a ser i e s of transects through the bog, and d r i l l e d holes to determine the depth of Sphagnum or humic Sphagnum peat. He found that Sphagnum peat was deepest (3.3 m) i n the center of the bog (approximately at the present s i t e of the Ladner plant of the Western Peat Moss Ltd.) and that i t gradually decreased i n depth i n a l l d i r e c t i o n s from t h i s point. S i g n i f i c a n t l y , Anrep indi c a t e d a large "Area under c u l t i v a t i o n or burnt over" surrounding the bog. This zone extended well beyond the present bog l i m i t s , p a r t i c u l a r l y to the south. He also recognized that he was probably i n v e s t i g a t i n g a r a i s e d bog because: "the peat moss layer i s above sea l e v e l and can be drained to the Fraser River". Osvald (1933) noted the plant associations of Burns Bog, and ind i c a t e d the s i m i l a r i t y to those i n Lulu Island Bog. He noted that the margins had been reclaimed i n the southern part. Osvald did not comment on peat 11 stratigraphy. The l a s t published, early examination of Burns Bog peat deposits was c a r r i e d out by Rigg and Richardson (1938). Using a H i l l e r borer, they ran a si n g l e transect from north to south and p l o t t e d a p r o f i l e of the bog. S i g n i f i c a n t l y , these workers p l o t t e d the surface of the bog as i f i t were f l a t rather than domed. The resultant v e r t i c a l section d i s t o r t e d s t r a t i - graphic boundaries downward i n the c e n t r a l part of the bog so that i t ap- pears that i t formed i n a shallow depression. I t i s possible that Rigg and Richardson (1938) knew that they were i n a r a i s e d bog but had no way of cor r e c t i n g f or e l e v a t i o n a l differences because the bog had not been sur- veyed. Most recently, i n a synthesis of data from both published and unpub- l i s h e d sources, Biggs (1976) (noting problems i n peat c l a s s i f i c a t i o n ) pro- duced a peat isopach model for Burns Bog. When compared with surface topography, the depths indicate that the dome shape of the bog i s due to Sphagnum peats, whereas the contact between these, and deposits below, i s h o r i z o n t a l . 12 CHAPTER 2: THE VEGETATION OF BURNS BOG AND OBSERVATIONS ON PLANT ECOLOGY Introduction For the purposes of t h i s paleoecologic study, knowledge of the vegeta- t i o n of Burns Bog and the factors c o n t r o l l i n g plant d i s t r i b u t i o n are con- sidered to be c r i t i c a l to the understanding of f o s s i l deposits. An understanding of the ecology of plant species and composition and dynamics of plant communities associated with bog development makes possible much more precise paleoenvironmental reconstructions. This chapter outlines the vegetation of present-day Burns Bog, discusses the vegetational structure before i t s a l t e r a t i o n by major disturbance by immigrants and contains some observations and in t e r p r e t a t i o n s of the role of f i r e and Sphagnum growth on bog vegetation. The Vegetation Types of Burns Bog Several researchers have studied the plant assemblages of Burns Bog (Osvald, 1933; Rigg and Richardson, 1938; Beamish, Krajina and Bednar, 1968). To date, however, no d e t a i l e d account of the vegetation has been published. As a r e s u l t i t was decided to map the vegetation and determine the quanti- t a t i v e , f l o r i s t i c composition of the major plant communities. The informa- t i o n presented here i s a condensation of a study c a r r i e d out i n co l l a b o r a t i o n with W. G. Biggs, Plant Science Department, University of B r i t i s h Columbia (Hebda and Biggs, i n preparation). Methods The vegetation of Burns Bog was investigated systematically during the 13 summer of 1975 as follows: A preliminary base map, showing the generalized vegetation units, was prepared from a c o n t r o l l e d a i r photographic mosaic. The mosaic (1" = 800') was created by P a c i f i c Surveys Corporation for Western Peat Moss Ltd. from a e r i a l photography BC5588, flown on July 12, 1974. F i e l d i n v e s t i g a t i o n s of the area were i n i t i a t e d i n June, 1975. A t o t a l 2 of 6,000 m of the bog was sampled q u a n t i t a t i v e l y by p l a c i n g s i x t y quadrats, 10 m x 10 m, at selected s i t e s . Single quadrats or transect l i n e s contain- ing a number of quadrats, were located so that the more extensive vegetation types were well sampled whereas les s important types were examined les s i n t e n s i v e l y . Transect l i n e s were run from the eastern, southern, western and northern peripheries toward the center of the bog. Examination of a i r photographs indi c a t e d that t h i s transect l i n e placement would ensure as thorough a sampling as possible of the major vegetation units i n the l i m i t e d time a v a i l a b l e . Quadrats were usually spaced at 100 m i n t e r v a l s along transects. However, where the nature of the vegetation changed r a p i d l y , a 50 m spacing was used. Within each quadrat, cover estimates were made for tree and shrub species (Mueller-Dombois and Ellenberg, 1974). Shrub, herb, bryophyte and l i c h e n cover was estimated i n f i v e p l o t s , 1 m x 1 m, arranged i n s i d e the large quadrats as shown i n F i g . 3. A d d i t i o n a l vegetation informa- t i o n was c o l l e c t e d i n many areas where i t was considered desirable to v e r i f y composition for the map. Voucher specimens of most species were c o l l e c t e d for deposit i n the Herbarium of the University of B r i t i s h Columbia. Species names and a u t h o r i t i e s used i n the following d e s c r i p t i o n follow Taylor and MacBryde (1977) f o r vascular plants, Crum, Steere and Anderson (1973) for mosses, and Hale and Culberson (1970) f o r l i c h e n s . 14 10 m 100 m 2 1 m n " r TRANSECT LINE ^ Figure 3, Arrangement of 100 var and 1 m Quadrats Used f or Vegetation Analysis i n Burns Bog, Information obtained from the quadrats was tabulated, with the quad- rats s u b j e c t i v e l y grouped according to species composition and cover. Revisions of the o r i g i n a l base map were made following analysis of quadrat data and examination of a i r photographs (1" = 500') of the area made av a i l a b l e by the Land Assessment Department, Ladner, B. C. Vegetation types were delineated as being more or less homogenous assemblages of plants, recognizable and mappable on the air photographic mosaic (1" = 800'). V. ' 15 Results Eight vegetation types were recognizable i n Burns Bog, with two sub- types within the heathland type. 1. Heathland: l a . wet (Sphagnum) subtype l b . Dry (Ledum) subtype 2. Pine Woodland 3. Birch Woodland 4. Spiraea Brushland 5. Mixed Coniferous Woodland 6. Salmonberry . Bushland 7. Alder Woodland 8. Unvegetated Peatland. The quantitative f l o r i s t i c composition of each vegetation type i s presented i n Appendix - 1. The map of the vegetation types of Burns Bog i s shown i n F i g . 4 (in pocket at back). Photographs t y p i c a l of each major vegetation type are also included (Fig. 5). 1. Heathland (Fig. 5a) Main features: 1. open character, with scrub or small Pinus contorta; 2. shrub storey dominated by heaths (Ericaceae), mainly Ledum groenlandicum; 3a. wet (Sphagnum) subtype - numerous mats and hummocks of Sphagnum spp.; 16 Figure 5: Photographs il l u s t r a t i n g the major vegetation types of Burns Bog. a) Heathland (wet subtype in foreground) b) Pine Woodland c) Birch Woodland (dense stands of young birch) d) Spiraea Brushland (shrubs in foreground) e) Mixed Coniferous Woodland f) Alder Woodland (mixed with birch) The dense growth of Salmonberry Bushland made i t impossible to obtain a representative photograph. No photograph of Unvegetated Peatland is included.  18 3b. dry (Ledum) subtype - few hummocks or mats of Sphagnum spp. Heathland vegetation occupies the ce n t r a l portion of the bog (Fig. 4) and covers the greatest area of a l l the vegetation types. O u t l i e r s of t h i s assemblage are also found near the edges of the bog as open islands i n pine woodland. Sphagno-fibrisol s o i l s characterize t h i s vegetation type (Luttmerding and Sprout, 1969). Drainage i s poor and the water table i s never more than a few centimeters below the surface. Heathland vegetation i s d i v i s i b l e into two subtypes; wet (Sphagnum) heathland and dry heathland. Most of the wet, ce n t r a l area of the bog f a l l s into the Sphagnum heathland category and represents t y p i c a l r a i s e d bog conditions characterized by p r o l i f i c growth of Sphagnum spp. Dry (Ledum) heathland occupies recently burned-over s i t e s within and around the rai s e d , c e n t r a l area. Extensive stands of Ledum groenlandicum cover these areas, and l i t t l e Sphagnum cover i s present. These two subtypes are recognizable l o c a l l y i n the f i e l d , but cannot be distinguished i n the a i r photographic mosaic used to map the vegetation, l a . Wet (Sphagnum) heathland There i s no s i g n i f i c a n t tree overstorey i n Sphagnum heathland. Stunted Pinus contorta with growth rates of around 1 cm diameter every 15 years i s - abundant. Occasional dwarfed specimens of Tsuga heterophylla and Betula o c c i d e n t a l i s also occur. The shrub layer consists c h i e f l y of Ericaceae. Ledum groenlandicum and Vaccinium uliginosum are the dominant species. Ledum, occupying the 19 r e l a t i v e l y dry s i t e s , i s the more abundant of the two, whereas V. uliginosum favours wetter spots, p a r t i c u l a r l y the t r a n s i t i o n a l habitat between Sphagnum hummocks and depressions. Vaccinium m y r t i l l o i d e s and Gaultheria shallon frequently t h r i v e i n dry s i t e s under t a l l e r (3-10 m) pines. Kalmia microphylla subsp. o c c i d e n t a l i s and Andromeda p o l i f o l i a favour wetter conditions. Empetrum nigrum grows i n a l l but the wettest s i t e s . The herb layer i s best developed i n hygric depressions. Here, Rhyncho- spora alba and scattered Eriophorum chamissonis t h r i v e , with sporadic Dulichium arundinaceum. Sphagnum mats and hummocks support Vaccinium oxycoccos, Rubus chamaemorus and Drosera r o t u n d i f o l i a . T o f i e l d i a glutinosa and Drosera an g l i c a grow i n a r e s t r i c t e d area i n the c e n t r a l bog. These two taxa were probably more widespread before draining and peat mining a c t i v i t i e s decimated the populations. Nuphar lut e a occupies pools choked by Sphagnum. The ground cover consists p r i n c i p a l l y of Sphagnum spp. with Sphagnum capillaceum predominating. This moss t o l e r a t e s the d r i e s t conditions of a l l the sphagna of t h i s vegetation type and i s presently a c t i v e l y advancing i n t o dry heathland and Pine Woodland along a large front i n the southern sector of the bog. Sphagnum fuscum f l o u r i s h e s best under s l i g h t l y wetter condi- tions and combines with S_. capillaceum to form extensive mat-hummock complexes. Sphagnum recurvum var. tenue f l o a t s along with Nuphar lut e a i n depressions where standing water i s present throughout the year. In shallow, flat-bottomed hollows that dry out i n summer and autumn, Sphagnum tenellum usually forms a monospecific carpet. Sphagnum papillosum develops best 20 under a moisture regime intermediate between that preferred by S_. c a p i l - laceum/S. fuscum and S_. recurvum/S. tenellum. S_. papillosum i s a major hummock-forming species i n the c e n t r a l bog. Other mosses occur i n wet heathland, but are le s s abundant than i n dry heathland. Polytrichum juniperinum, however, often crowns the tops of Sphagnum hummocks. Two c h a r a c t e r i s t i c bog liverworts, Mylia anomala and Gymnocolea i n f l a t a , grow interspersed among the sphagna. Lichens are a major element of the ground cover type. Two l i c h e n species, Cladina m i t i s and Cladina r a n g i f e r i n a , t y p i c a l l y form cushions on hummock tops. l b . Dry .(Ledum) heathland This subtype can be best envisaged as a monoculture of Ledum groen- landicum, which forms an almost continuous shrub storey, interrupted here and there by Vaccinium m y r t i l l o i d e s . Most of the other species c h a r a c t e r i s - t i c of wet heathland are also present but i n fewer numbers. Pinus contorta i s e i t h e r absent of represented only by young saplings. Thickets of Spiraea d o u g l a s i i and Myrica gale along with Pteridium aquilinum brakes grow where dry heathland reaches the edges of the bog, and i n d i c a t e both more humic and s l i g h t l y d r i e r conditions. The herb stratum i s very poorly developed. Instead there i s often an abundance of mosses and l i c h e n s . Polytrichum juniperinum forms extensive mats on disturbed peat. Aulocomnium androgynum grows near r o t t i n g wood. The following species form colonies among heath stems and under Pinus: Dicranum scopariuirt S t o k e s i e l l a oregana 21 Hylocomium splendens Pleurozium schreberi Rhytidiadelphus loreus Rhytidiadelphus tr i g u e t r u s Lichens grow p r i m a r i l y on the dry surface layer of heath peat that often contains charcoal. Gladonia cenotea, Cladonia chlorophaea, Cladonia subsquamosa and Cladonia transcendens t h r i v e under these conditions. 2. Pine Woodland (Fig. 5b) Main features: 1. stands of Pinus contorta greater than 4 m high; 2. shrub l a y e r dominated by Ledum groenlandicum and Gaultheria shallon; 3. medium to well developed bryophyte cover. Pine Woodland forms a band of vegetation surrounding the c e n t r a l mass of Heathland. Typic mesisol s o i l s are c h a r a c t e r i s t i c (Luttmerding and Sprout, 1969). The water table can vary as much as 1 m, and drops well below the surface i n l a t e summer. The closed to p a r t i a l l y open tree stratum i s composed of Pinus contor- ta, usually much t a l l e r than 4 m. Growth rates, as noted i n tree rings from transverse sections, range from 1-6 years for each centimeter of diameter, a rate much higher than i n Heathland. Tsuga heterophylla and Betula o c c i d e n t a l i s are present i n a few s i t e s . The shrub layer, dominated by Ledum and Gaultheria i s usually well developed, whereas Vaccinium m y r t i l l o i d e s i s l o c a l l y abundant. Spiraea d o u g l a s i i and Pteridium aquilinum grow p r i m a r i l y i n the t r a n s i t i o n to b i r c h woodland. Heathland species such as Vaccinium uliginosum, Kalmia microphylla, and Vaccinium oxycoccos occupy s i t e s where sphagnum mosses appear to be advancing. 22 In wet areas the herb layer consists of the same species as those found i n wet heathland. In several s i t e s T r i e n t a l i s europaea subsp. a r c t i c a , Cornus unalaschkensis and Garex l e n t i c u l a r i s occur i n patches. Sphagnum mosses (:S. capillaceum, S_. papillosum) are c h a r a c t e r i s t i c of the t r a n s i t i o n to wet heathland. In the r e s t of the Pine Woodland, mosses c h a r a c t e r i s t i c of dry heathland abound, at times forming extensive carpets. 3. Birch Woodland (Fig. 5c) Main features: 1. dense stands of mature Betula o c c i d e n t a l i s ; 2. shrub storey of Spiraea d o u g l a s i i ; 3. profuse growth of Pteridium aquilinum. B i r c h Woodland surrounds the bog proper, i n places a l t e r n a t i n g with Spiraea Brushland. The poorly drained s o i l s , composed of well decomposed organic matter, are c l a s s i f i e d as t y p i c humisols (Luttmerding and Sprout, 1969) . Betula o c c i d e n t a l i s dominates the tree stratum, with Pinus contorta and S a l i x hookeriana o c c a s i o n a l l y interspersed. In the understorey, Spiraea and Pteridium grow i n great numbers. L o c a l l y Gaultheria sometimes dominates. Rubus s p e c t a b i l i s , Ledum groenlandi- cum and Myrica gale appear sp o r a d i c a l l y . Carex r o s t r a t a , Carex l e n t i c u l a r i s , T r i e n t a l i s europaea and Cornus unalaschkensis constitute most of the impoverished herb l a y e r . The same moss species are present as i n Pine Woodland, of which Polytrichum juniperinum, Polytrichum commune, and Isothecium spiculiferum are the most abundant. 4. Spiraea Brushland (Fig. 5d) Main features: 23 1. absence of a tree stratum; 2. dense thickets of Spiraea d o u g l a s i i ; 3. sparse herb-bryophyte cover. This vegetation type surrounds most of Burns Bog. As i n Birch Wood- land, the substrate i s a t y p i c humisol (Luttmerding and Sprout, 1969). In t h i s zone, dense th i c k e t s of Spiraea predominate over a l l species. Betula o c c i d e n t a l i s and Malus fusca occur as i s o l a t e d i n d i v i d u a l s . In the t r a n s i t i o n regions i n t o bog vegetation types, Gaultheria shallon, Ledum groenlandicum and Myrica gale appear. Usually only T r i e n t a l i s europaea grows i n the herb l a y e r . Moss growth i s also suppressed, with only Poly- trichum juniperinum reaching appreciable cover values. This Spiraea Brushland vegetation type i s also common on the wetlands of the Fraser River Delta. Around the bog, i t seems to occupy the p o s i t i o n of a poorly defined lagg, a s i t u a t i o n also c h a r a c t e r i s t i c of a number of other west coast bogs (Rigg and Richardson, 1938). 5. Mixed Coniferous Woodland (Fig. 5'e') Main features: 1. a canopy of Thuja p l i c a t a , Picea s i t c h e n s i s , Tsuga heterophylla and, i n places, Alnus rubra; 2. a shrub layer dominated by Gaultheria shallon, Rubus s p e c t a b i l i s , and Menziesia ferruginea; 3. abundant Lysichitum americanum; 4. extensive bryophyte cover. The Mixed Coniferous Woodland i s best developed i n the eastern section of the bog along the foot of Panorama Ridge. Remnants of t h i s vegetation 24 type also border Crescent Slough. The humic mesisol (Luttmerding and Sprout, 1969) s o i l i s usually saturated, r e s u l t i n g i n swampy conditions. The upper storey consists mainly of mature Thuja p l i c a t a , Picea si t c h e n s i s and Tsuga heterophylla. One recently f e l l e d Picea specimen, measuring 80 cm i n diameter, was determined to be 515 years o l d . There are also some large Pinus contorta that are 30 cm i n diameter and up to 125 years o l d . The most abundant, t a l l , deciduous trees are Alnus rubra and Betula o c c i d e n t a l i s . Alnus seems to be r e s t r i c t e d to s i t e s where there i s a mineral horizon within 1-2 m of the surface. In several areas there i s a shrubby t r e e / t a l l shrub stratum in c l u d i n g i n most cases Rhamnus purshianus, Acer circinatum, Cornus s e r i c e a and the occasional Viburnum edule. Within t h i s vegetation type there i s a dense shrub layer, usually dominated by Gaultheria shallon, with l e s s e r numbers of Menziesia, Rubus s p e c t a b i l i s , Spiraea d o u g l a s i i , Vaccinium o v a l i f o l i u m and Vaccinium alaskaense. Vaccinium pa r v i f o l i u m i s usually l i m i t e d to r o t t i n g stumps. The herb stratum of Mixed Coniferous Woodland i s dominated by 2 Lysichitum americanum, which reaches d e n s i t i e s of 90 i n d i v i d u a l s per 100 m . Athyrium f i l i x - f e m i n a and Dryopteris a s s i m i l i s sometimes occur i n associa- t i o n with Lysichitum. Mosses and liverworts cover much of the ground, logs and tree trunks. The most common of these are: Rhytidiadelphus loreus S t o k e s i e l l a oregana Mnium glabrescens Isothecium spiculiferum Hylocomium splendens 25 F r u l l a n i a tamarisci P e l l i a 'neesiana Scapania bolanderi. 6. Salmonberry Bushland Main features: 1. I r r e g u l a r l y developed tree canopy; 2. dense small t r e e / t a l l shrub la y e r , dominated by Rubus s p e c t a b i l i s (Salmonberry); 3. well developed bryophyte carpet. The removal of large trees by logging from Mixed'Coniferous Woodland i n the eastern part of the bog has resulted i n the growth of rather dense stands of Rubus s p e c t a b i l i s . The s o i l i s a humic mesisol,(Luttmerding and Sprout, 1969). The common tree species that remained or colonized a f t e r logging include: Picea s i t c h e n s i s Thuja p l i c a t a Tsuga heterophylla Alnus rubra Betula o c c i d e n t a l i s Maius fusca Rhamnus purshianus S a l i x l a s i a n d r a . Although Rubus s p e c t a b i l i s dominates the shrub storey, there are other shrub species also present, i n c l u d i n g : 26 Cornus s e r i c e a Gaultheria shallon Lonicera i n v o l u c r a t a Menziesia ferruginea Sambucus racemosa Spiraea d o u g l a s i i Vaccinium o v a l i f o l i u m Vaccinium parvifolium. Lysichitum americanum i s the most abundant member of the poorly developed herb stratum. There are also scattered plants of Maianthemum dilatatum, Penanthe sarmentosa, S c u t e l l a r i a l a t e r i f l o r a and S t e l l a r i a c r i s p a . The large number of o l d logs i n t h i s vegetation type has contributed to an extensive bryophyte cover. The species found are those that are also c h a r a c t e r i s t i c of the Mixed Coniferous Woodland (see previous vegetation type). 7. Alder Woodland (Fig. 5f) Main features: 1. an Alnus rubra canopy; 2. a shrub stratum characterized by Rubus s p e c t a b i l i s ; 3. sparsely developed herb and bryophyte s t r a t a . Alder Woodland has developed on a logged a l l u v i a l fan, deposited by a small creek flowing o f f Panorama Ridge. The s o i l s under Alder Woodland . were o r i g i n a l l y mapped as humic mesisols (Luttmerding and Sprout, 1969). However, on f i e l d checking, the s o i l s appear to contain abundant mineral material, often within a few centimeters of the surface and thus are not organic i n nature. 21 The canopy i s composed c h i e f l y of Alnus rubra, with the occasional S a l i x lasiandra. Other tree species occurring i n the assemblage are: Picea s i t c h e n s i s Thuja p l i c a t a Acer circinatum Betula o c c i d e n t a l i s Malus fusca Rhamnus purshianus. Rubus s p e c t a b i l i s i s the most common shrub. The following occur sparsely: Lonicera i n v o l u c r a t a Menziesia ferruginea Sambucus racemosa Vaccinium par v i f o l i u m Viburnum edule. The shaded conditions r e s t r i c t the growth of herbs, and only Claytonia s i b i r i c a and S t e l l a r i a c r i s p a provide any appreciable cover; The bryophyte stratum i s s i m i l a r i n composition but l e s s developed than that of Mixed Coniferous Woodland. 8. Unvegetated Peatland Peat has been extracted from a large area i n the center of Burns Bog since early i n the 20th century (Biggs, 1976). Currently, large areas are being mined by e i t h e r the hydraulic method or the "scratching" method. Both of these p r a c t i c e s produce large expanses of bare peat. In areas mined by the hydraulic method, large excavated pools are l e f t behind with ridges of 28 o r i g i n a l vegetation i n between. The scratching method consists of annually removing the top 8 cm of dry surface peat from- extensive p l o t s that remain vegetation-free. When an area i s f i n a l l y abandoned, i t slowly recolonizes into a t y p i c a l Sphagnum heathland, with an assemblage i n i t i a l l y i ncluding Polytrichum juniperinum, Rubus chamaemorus and Rhynchospora alba. The O r i g i n a l Vegetation of the Burns Bog Area Although the plant assemblages of the c e n t r a l bog are probably repre- sentative of the o r i g i n a l vegetation cover, the peripheral areas are badly disturbed as a r e s u l t of c l e a r i n g , draining and burning since European immigration. Knowledge of the o r i g i n a l vegetation can provide clues to the successional phases i n the development of Burns Bog as well as i d e n t i f y i n g neighbouring p o l l e n sources that were p o t e n t i a l contributors to the palyno- assemblages found i n cores. Data for reconstructing pre-disturbance plant cover can be obtained from e a r l y Land Survey Records (cf. Janssen, 1967). Surveyors mapping the Fraser Delta i n the early 1870's provided notes on the vegetation i n the area around Burns Bog, although they d i d not survey within the bog. North and Teversham (1977) have synthesized these data into a map showing the o r i g i n a l vegetation. Despite problems i n i n t e r p r e - t a t i o n of some of the surveyors' terms f o r plants, North and Teversham were able to recognize 28 vegetation types based mainly on physiognomic characters. In the map they prepared, vegetation units were not o u t l i n e d ; the occurrence of a vegetation type at a l o c a l i t y was simply denoted on a map of the Fraser Lowland, by a l e t t e r designated to represent that type. For the purposes of the present study, the map of North and Teversham, along with some of the o r i g i n a l information from an early map (Scott, Pinder and Cridge, unpublished) containing surveyors' notes, 29 has been used to produce a map of the vegetation zones extant i n the Burns Bog area i n 1873-1874 (Fig. 6). Some i n t e r p r e t a t i o n and gene r a l i z a t i o n of the data are made here, so that boundaries and descriptions must be con- sidered very approximate. Descriptions of the vegetation types are mostly those used by North and Teversham (1977), and come d i r e c t l y from surveyors' reports. The map: Nine vegetation types are recognized for the Burns Bog area and p l o t t e d on the map: 1. S a l t marsh - containing s a l t g r a s s , probably same as current s a l t marsh vegetation. 2. Wet grass p r a i r i e - bunchgrasses, rushes and reeds i n t e r - spersed, probably containing sedges also; no current equivalent. 3. Red top p r a i r i e - coastal grassland, may have contained Agrostis sp.; no known current equivalent. 4. Grass, hardhack and willow. 5. Grass with shrubs - mainly grass with patches of willow, hardhack, crabapple and rose. 6. Mixed scrub - hardhack, willow, crabapple, rose; common wetland vegetation type i n the Fraser Delta, perhaps s i m i l a r to Spiraea Brushland (Ch. 2). 7. Bog - small withered pines, cranberry bush, moss; labrador tea around the edges i n places; equivalent with current Heathland vegetation type (Ch. 2). FIGURE - 6: Or i g ina l vegetation of the Burns Bog area (1873). LEGEND Pr^D p e a t B og ( 7 ) * t M a r s h ( 1 ) G r a s s P r a i r i e ( 2 ) Top P r a i r i e ( 3 ) s s w i t h S h r u b s ( 5 ) s s , H a r d h a c k , W i l l o w w o mp F o r e s t - C e d a r , ( 8 ) u c e , H e m l o c k , A l d e r e d S c r u b - H a r d h a c k , l o w , C r a b a p p l e ( 6 ) S p r u c e F o r e s t ( 9 ) N BOUNDARY BAY * N u m b e r s r e f e r t o d e s c r i p t i o n s i n t h e t e x t . 31 8. Swamp for e s t - cedar, spruce, hemlock, alder, willow, crabapple; s i m i l a r to Mixed Coniferous Forest (Ch. 2). 9. Spruce f o r e s t - somewhat swampy; spruce, crabapple, willow, alder, b r i a r s , vine maple; s i m i l a r to current r i v e r bank vegetation. The map reveals remarkable differences between the o r i g i n a l and the present vegetation of the bog (Fig. 4). At the time of the survey, Pine Woodland and B i r c h Woodland did not e x i s t . The areas they now occupy then supported a Heathland or bog type vegetation. This i s substantiated by the observa- t i o n that no specimens of Pinus contorta within the Pine Woodland have been found to be over 70 years o l d . Also within a few centimeters of the surface, t y p i c a l Sphagnum peat i s present under the Pine Woodland and much of the Bi r c h Woodland. These two vegetation types have probably o r i g i n a t e d as a r e s u l t of c l e a r i n g , burning and draining. Biggs (1976) and Osvald (1933) both r e f e r to c l e a r i n g and burning of the southern parts of the bog. The farmland regions to the south of the bog were covered by wet grass- land containing bunchgrasses, rushes and reeds. S i g n i f i c a n t l y , no mention i s made of sedges here or i n any of the wetland environments and i t i s probable that surveyors lumped sedges along with grasses i n t h e i r descrip- t i o n s . To the east, there was good grass p r a i r i e , c l a s s i f i e d into the red top p r a i r i e vegetation type by North and Teversham (1977). Bordering the bog on the west and north, shrubs were an important part of the vegetation, occurring i n clumps among grasses (types 4 and 5) or i n thickets (mixed scrub). Hardhack (Spiraea douglasii) seems to have been one of the dominant 32 species involved. Some spruce f o r e s t grew along Crescent Slough. Swamp fore s t occupied the banks of the Fraser River. In short, the area was apparently covered l a r g e l y by bog vegetation with considerable zones of wet grassland, intermediate grass and shrubs and shrubby t h i c k e t s . Both the Birch and Pine Woodland zones appear to have developed i n r e l a t i v e l y recent times. The Role of F i r e i n Burns Bog F i r e s have been documented i n Burns Bog since the l a t e 19th century (North and Teversham, 1977; Osvald, 1933) . As recently as August 1975, there was a major f i r e i n the northern sector of Burns Bog. F i r e s are recorded i n the cores as charcoal horizons. An understanding of the r o l e of f i r e i n bog ecology i s necessary f o r i n t e r p r e t i n g sections of p o l l e n d i a - grams and explaining some of the current features of the vegetation. The importance of f i r e s i n bog development f i r s t became apparent when two types of wet depression were i d e n t i f i e d i n the bog. One type of de- pression i s .5-1 m deep and i s choked with Nuphar lutea and Sphagnum recurvum. The Sphagnum papillosum flanks of these "Nuphar ponds" descend steeply i n t o the water which p e r s i s t s throughout the year. These are the t y p i c a l depressions that characterize many of the bogs of south- western B. C. (Osvald, 1933) and are probably r e l a t e d to normal ra i s e d bog growth. The second type of depression i s shallow (.2 m), d r i e s out i n the summer and has a f i r m f l a t bottom. I t i s characterized by a feeble carpet of Sphagnum tenellum and extensive growth of Rhynchospora alba. The sides of these "Rhynchospora lows" grade_gradually into hummocks of Sphagnum capillaceum and Sphagnum fuscum. They also often contain pine stumps. Both types of depression occur within a few yards of each other. 33 A s i g n i f i c a n t feature of "Rhynchospora lows" i s that within the top .15 m of the surface of the bottom deposits there i s always a thick (up to 2 cm) layer of charcoal. Shallow p i t s dug i n shrubby vegetation beside these "Rhynchospora lows" did not reveal a s i m i l a r charcoal layer. As a r e s u l t , the,scheme o u t l i n e d i n F i g . 7 was o r i g i n a l l y conceived as a possible explanation for the development of "Rhynchospora lows". This scheme was l a t e r confirmed a f t e r observations of the area burned i n August 1975. The undisturbed bog surface i s a mosaic of wet, Sphagnum-dominated and dry, shrub-dominated patches; that i s , a mosaic of Sphagnum heathland and dry (Ledum) heathland. Many of the depressions i n the Sphagnum heath- land are s u f f i c i e n t l y wet that they do not support any shrub growth. The shrubby vegetation of the dry heathland, dominated by Pinus contorta and Ledum groenlandicum, seems predisposed to f i r e . The dense, low growth form of the Pinus, with many dead branches, provides i d e a l conditions for the i g n i t i o n and spread of f i r e (Rowe and Scotter, 1973). S i m i l a r l y , Ledum seems i d e a l l y s u i t e d f or f i r e because i t produces great numbers of t i n d e r - l i k e stems and also because of i t s high o i l content, a c h a r a c t e r i s t i c shared by many fire-adapted plants (pyrophiles) (Main, 1976). Burning of dry leaves of Ledum i n the lab showed that t h i s o i l would appear on the l e a f surface and s i z z l e i n t o flame. Ledum and many other shrubby bog plants have extensive root crown systems that regenerate a f t e r f i r e , and set a e r i a l stems within a short time. A f t e r a f i r e has burned over the bog surface, most of the shrubby vegetation i s destroyed along with any Sphagnum growing among the stems. However, the wet depressions are l e f t untouched because there are no shrubs to carry the flames over. Hence, a f t e r a f i r e , a desolate wasteland, 34 FIGURE - 7: F i r e - i n d u c e d h u m m o c k - h o l l o w c y c l i n g i n B u r n s B o g , 1 D e l t a , 3.C 00& h i g h , d r y ow, wet Sphagnum hummock FRE c h a r c o a l ( f r o m p r e v i o u s f i r e ) - p o o r Sphagnum p e a t g r o w t h ^ . ...SELiBiji REGENERATION r a p i d sphagnum p e a t g r o w t h , . „ „ „ . r \ LATER STAGES OF REGENERATION h i g h , d r y b u r i e d h o r i z o n .35 dotted with patches of unburned Sphagnum; i s l e f t behind. These Sphagnum islands then serve as centers of Sphagnum expansion over the surrounding, charred surface. They also become the centers of Sphagnum peat accumulation, r e s u l t i n g i n the elevation of these s i t e s above the surrounding area. In contrast to t h i s , Sphagnum co l o n i z a t i o n of the r e l a t i v e l y f l a t , burned surface i s slow. Although small cushions form from Sphagnum disseminules (spores and plant fragments), the colonies do not spread quickly. Observations ind i c a t e that about 20 years a f t e r a f i r e , cushions of Sphagnum capillaceum and Sphagnum papillosum were only sparsely s c a t t e r - ed and only 15-30 cm i n diameter. I n i t i a l l y , the burned areas are quickly revegetated from root crowns of shrubs, of which Vaccinium m y r t i l l o i d e s i s the f i r s t to dominate, follow- ed by a massive p r o l i f e r a t i o n of Ledum. Observations made one year a f t e r the August 1975 f i r e , i ndicated that along with these shrubs Polytrichum juniperinum, Funaria hygrometrica, and Aulocomnium androgynum quickly colonized the burned substrate. Marchantia polymorpha, absent at other times i n the bog, appeared abundantly i n very wet spots. This bryophyte phase i s a common p o s t - f i r e phenomenon i n European bogs (Froment, 1975) and i n the boreal f o r e s t (Rowe and Scotter, 1973) . Heath peat accumulation under these conditions i s very slow (approxi- mately 1 mm per year based on one observation) because decomposition seems almost to keep pace with heath l i t t e r deposition. The r e s u l t i s that these formerly shrubby areas become lower than the unburned, a c t i v e l y growing, Sphagnum isl a n d s . Thus many spots, e s p e c i a l l y those where the f i r e has burned i n t o the peat substrate, become shallow, w a t e r - f i l l e d depressions with a charcoal base. These "lows" are eventually colonized by Rhyncho- 36 spora alba, Sphagnum tenellum and algae. In time a "Rhynchospora low" r e s u l t s ; because i t i s wetter than the surrounding area, i t eventually converts to a center for Sphagnum growth and peat accumulation. Thus a cycle of hummock-hollow a l t e r n a t i o n , a mechanism at l e a s t p a r t i a l l y responsible f o r r a i s e d bog growth, i s continued. I t i s questionable whether t h i s c y c l i c process n e c e s s a r i l y speeds up peat accumulation, because; a) i t may remove considerable amounts of previously accumulated peat; and b) burned-over areas i n i t i a l l y accumulate peat very slowly compared to s i t e s with a c t i v e Sphagnum growth. Thus, i n t e r r u p t i o n of natural Sphagnum c y c l i n g by f i r e may severely retard normal peat accumula- t i o n . A f t e r the i n i t i a l Polytrichum-shrub stage, but before Sphagnum growth, lichens of the genus Cladonia move i n and blanket extensive areas. For example, a section of Burns Bog burned around 1955 i s characterized by very high cover values for Cladonia spp. This i s a feature also commonly ob- served i n the boreal f o r e s t following f i r e (Rowe and Scotter, 1973). The small amount of peat produced by these has a slimy character and contains many fungal hyphae. The E f f e c t of Sphagnum on Pine Growth Pinus contorta seedlings sometimes emerge as early as one year a f t e r a f i r e , but the i n t e r v a l f o r t h e i r appearance i s usually 2-5 years later... Those Pinus seedlings that have landed on unburned Sphagnum hummocks or mats grow very poorly (1 cm diameter every 15 years), and develop a stunted stature (.6m high) (Fig. 8). Those that germinate on burned surfaces (even i f they are wet) grow r e l a t i v e l y w ell (1 cm diameter every 1-6 years) and appear normal (4 m high). Pinus seedlings with part of the root systems FIGURE - 8: R e l a t i o n s h i p o f p i n e g r o w t h t o Sphagnum hummock f o r m a t i o n . Both trees are 15 years o l d and sprouted a f t e r a f i r e that destroyed a l l shrub and pine growth, w h i l e burning Sphagnum hummocks only s l i g h t l y . to Sphagnum fuscum/Sphagnum capillaceum Charcoal estimated 60 - 80 vears old 38 covered by an a c t i v e l y growing Sphagnum patch e x h i b i t intermediate features with progressive reduction of r i n g growth on the side of the trunk that faces the advancing hummock. This pattern i s probably c o r r e l a t e d with the highly competitive a b i l i t y of hummock-forming mosses, such as Sphagnum capillaceum, to absorb nutrients (Moore and Bellamy, 1974). This hypothesis may also explain a s u r p r i s i n g p e r i o d i c i t y of 10-20 years i n r i n g growth found i n c e r t a i n buried Pinus stumps. Local increased growth of hummock-forming sphagnum mosses would r e s u l t i n a period of poor growth, whereas a decrease or s t a n d s t i l l i n Sphagnum would r e s u l t i n improved growth. Summary In summary, the modern composition and d i s t r i b u t i o n of the vegetation of the bog appears to r e l a t e to changes that have occurred i n the o r i g i n a l vegetation. Clearing of land and a l t e r a t i o n of drainage patterns have l e d to the development of Pine woodland and B i r c h Woodland on Sphagnum peats around the bog. Wet grassland and shrubland communities of a possible successional nature were present around the bog. F i n a l l y the impact of f i r e on the bog ecosystem was discussed showing that i t caused a sudden change i n vegetation that was r e f l e c t e d i n sediments by a decrease i n rate and change i n nature of peat accumulation. 39 CHAPTER 3: BOG ERICACEAE: POLLEN TETRAD SIZE, POLLEN PRODUCTIVITY Members of the Ericaceae and Empetrum nigrum are important components of bog vegetation, p a r t i c u l a r l y i n Burns Bog. As such, i t would be of considerable value to know the r o l e ericads have played i n bog development. To gain as much information as possible from p o l l e n diagrams, studies were made of: 1. diameter ranges of ericad p o l l e n tetrads; 2. the p o l l e n p r o d u c t i v i t y of these bog ericads. The r e s u l t s of both studies have been applied to the reconstruction of the vegetation of those i n t e r v a l s containing s u f f i c i e n t amounts of ericaceous p o l l e n . 1. Tetrad Diameter of Bog Ericaceae and Empetrum nigrum The p o l l e n of the Ericaceae and Empetrum i s preserved i n varying amounts i n bog deposits, but unfortunately i t i s d i f f i c u l t to i d e n t i f y the various genera, and even more d i f f i c u l t to i d e n t i f y the species ( O l d f i e l d , 1959). In the present study, a rudimentary, but quick system u t i l i z i n g t e t rad diameter was developed to d i s t i n g u i s h e c o l o g i c a l l y s i g n i f i c a n t groups of species i n Burns Bog. The e r i c a d species found abundantly i n Burns Bog are: Ledum groenlandicum Kalmia microphylla var. o c c i d e n t a l i s Andromeda p o l i f o l i a Vaccinium m y r t i l l o i d e s Vaccinium oxycoccos 40 Vaccinium uliginosum Gaultheria shallon Empetrum nigrum. Diameter measurements (see O l d f i e l d , 1959) were made on 100 acetolyzed tetrads taken from flowers c o l l e c t e d from numerous plants at various l o c a l - i t i e s i n Burns Bog. The r e s u l t s are presented i n Table 1 and the siz e d i s t r i b u t i o n for each group i s p l o t t e d i n F i g . 9. Three diameter groups can be distinguished: 1. les s than 30 um - including most of Ledum and Empetrum tetrads; 2. 30-36 um - incl u d i n g mainly Kalmia microphylla and Vaccinium m y r t i l l o i d e s tetrads; 3. greater than 36 um - incl u d i n g Vaccinium oxycoccos, Vaccinium uliginosum, Andromeda p o l i f o l i a , and Gaultheria shallon tetrads. F o r t u i t o u s l y , these groups of species have ecologic s i g n i f i c a n c e and can be used to i n d i c a t e : Group 1. - dry (Ledum) heathland conditions; Group 2. - intermediate to wet conditions; Group 3. - very wet (Sphagnum) heathland conditions. Ledum groenlandicum of Group 1 i s the prime i n d i c a t o r of dry (Ledum) heathland conditions i n the bog (see Ch. 2), and flowers profusely i n these r e l a t i v e l y dry s i t e s . Empetrum nigrum, on the other hand, i s not necessa r i l y an i n d i c a t o r of dry s i t u a t i o n s since i t can grow w e l l among Sphagnum hum- mocks. However, i n t h i s wetter habitat i t has been observed to flower poorly (cf. B i r k s , 1975). Secondly, under conditions of i d e a l preservation, TABLE 1: TETRAD DIAMETERS OF MAJOR ERICAD SPECIES IN BURNS BOG, DELTA, B. Species Mean tetrad diameter Range Standard Deviation Ledum groenlandicum 27.20 ym* 24-30 1.41 Empetrum nigrum 26.15 22-31 1.77 Kalmia microphylla subsp. occidentalis 32.54 28-37 1.75 Vaooinium myrtilloides 33.21 28-39 2.46 Vaccinium oxycoccos 38.63 33-44 2.24 Vaccinium uliginosum 41.78 36-48 2.83 Andromeda polifolia 43.29 38-51 2.64 Gaultheria shallon 46.97 41-53 2.50 *A11 measurements are i n pm. Sample s i z e f o r a l l species was 100 tetrads. FIGURE - 9: Distribution of tetrad sizes of bog Ericaceae and Etnpetrum nigrum. Group 3 Andromeda pollfolia N3 Vaccinium uliginosum T E T R A D D I A M E T E R IN MICROMETERS Sample size for each species is 100 tetrads. Broken lines are used for purposes of clarity in presentation and have no other significance. 43 i t s tetrads can be distinguished morphologically from those of Ledum. Kalmia microphylla i s the i n d i c a t o r of intermediate conditions i n Group 2. Vaccinium m y r t i l l o i d e s i s a problematic species i n Burns Bog and the Fraser Delta, as i t s populations are d i s j u n c t from the main range i n the pine forests of i n t e r i o r B r i t i s h Columbia. Examination of c o l l e c t e d material from various sources has not helped c l a r i f y whether V. m y r t i l l o i d e s has a r r i v e d i n the Delta area recently, or i f i t has grown here ever since s u i t a b l e conditions became a v a i l a b l e i n these lowland bogs. Vigorous growth and flowering of t h i s plant are r e s t r i c t e d to p o s t - f i r e s i t u a t i o n s on deep peats where i t i s not choked out by Ledum. A l l taxa of Group 3, except Gaultheria are excellent i n d i c a t o r s of very wet conditions, and also of active Sphagnum growth. In contrast, Gaultheria shallon does not grow i n very wet habitats, although i t i s sometimes present on the r e l a t i v e l y dry tops of Sphagnum hummocks. I t does not usually flower under these conditions and for t h i s reason i t has been excluded from further discussion. A p p l i c a t i o n of r e s u l t s : The information obtained can be applied to paleoecology by measuring the diameter of tetrads recovered from f o s s i l deposits. Once the frequency of tetrads i n each size-range i s known, comparison with surface samples permits i n t e r p r e t a t i o n of the ericad component of the vegetation. One assumption must be kept i n mind. I t i s possible that ericaceous species present at one time i n the bog may not have survived through to modern times. Hence, caution must be used i n i n t e r p r e t a t i o n , p a r t i c u l a r l y i f there are macrofossils i n d i c a t i n g such l o c a l l y e x t i n c t species, or i f there are other good i n d i c a t o r s of environmental change. F i n a l l y the 44 ecology of each species used needs to be well understood. For Burns Bog, the species composition and te t r a d diameters of ericads c o r r e l a t e well enough to give a good model for i n t e r p r e t a t i o n . Although applicable i n t h i s case, i t does not nec e s s a r i l y follow that t h i s model w i l l work when extended to other bogs, e s p e c i a l l y those with d i f f e r e n t species of ericads or d i f f e r e n t sedimentary regimes. 2. Po l l e n P r o d u c t i v i t y of Bog Ericaceae To increase the usefulness of the three diameter groups i n paleoecologi- c a l i n t e r p r e t a t i o n , information on the comparative p o l l e n p r o d u c t i v i t y of the e r i c a d species was also obtained by f i e l d sampling. With these data the l e v e l s of each e r i c a d group i n a f o s s i l p o l l e n sample can be compared, a f t e r c o r r e c t i n g for differences i n p r o d u c t i v i t y . The p o l l e n p r o d u c t i v i t y per square meter per year was determined f o r a l l the species i n Table 1, except Empetrum nigrum and Gaultheria shallon. For each species, ten quadrats, 10 cm by 10 cm, were chosen from areas where the highest density of flowers of that species seemed to occur. This provided a maximum p r o d u c t i v i t y value under i d e a l conditions. In these quadrats the number of flowers was counted and the cover of the species estimated. For each species, the average number of stamens per flower was obtained from 10 flowers. Then, the average number of p o l l e n grains per anther, from a sample of 10 undehisced anthers, was determined. To do t h i s , anthers were placed i n a drop of 10% KOH on a glass s l i d e , squashed, and the p o l l e n tetrads dispersed by c i r c u l a r motion of a c o v e r s l i p . A l l the po l l e n tetrads i n the anther were counted. F i n a l l y , the maximum t e t r a d p r o d u c t i v i t y per square meter per year was cal c u l a t e d for each species. 45 From Table 2 i t can be noted that Kalmia and Ledum are the most pro- l i f i c p o l l e n producers. Under optimal conditions they contribute 4.1 x 10 8 and 3.3 x 10 8 tetrads/m 2/year, re s p e c t i v e l y , to the p o l l e n crop. V. m y r t i l - l oides y i e l d s 1.82 x 10 8 tetrads/m 2 annually. The remaining three species are r e l a t i v e l y poor p o l l e n producers; V. uliginosum at 7.15 x 10 7 tetrads/ m 2/year; V. oxycoccos at 5.57 x 10 7 tetrads/m 2/year; and Andromeda p o l i f o l i a at 2.3 x 10 7 tetrads/m 2/year. These r e s u l t s i n d i c a t e that although low percentages of Group 3 tetrads may occur i n a f o s s i l e r i c a d assemblage, they are nevertheless s i g n i f i c a n t i n terms of the o r i g i n a l vegetation cover, because fewer tetrads are pro- duced by t h i s group. In an area dominated by Group 3 vegetation there are often some Ledum (Group 1) and Kalmia (Group 2) plants. On the basis of te t r a d p r o d u c t i v i t y , these l a s t two diameter classes could dominate the e r i c a d spectrum. However, as long as a s i g n i f i c a n t portion of the spectrum belonged to the greater than 36 ym group (for a reasonable sample s i z e ) , the wet habitat species probably predominated i n the heath cover. Also, the r e s u l t s imply that o v e r a l l percentages of Ericaceae must be expected to be lower i n spectra from Group 3 assemblages than i n areas dominated by the more productive Group 1 and Group 2 species. In conclusion, three e c o l o g i c a l l y s i g n i f i c a n t groups of ericads can be recognized i n Burns Bog on the basis of t e t r a d diameter. When combined with the p o l l e n p r o d u c t i v i t y values for the constituent species of these groups, the p l o t t i n g of t e t r a d s i z e s provides a p o t e n t i a l l y useful t o o l f o r recog- n i z i n g dry, intermediate and wet heathland vegetation types i n f o s s i l deposits. TABLE 2: POLLEN TETRAD PRODUCTIVITY OF MAJOR BOG ERICACEAE, BURNS BOG, DELTA, B. C. Species Andromeda polifolia Kalmia microphylla subsp. occidentalis Ledum groenlandicum Vaccinium oxyooooos Vaccinium myrtilloides Vaccinium uliginosum Flowers per 100 cm2* Mean 73 129 352 54 452 95 Range 43-90 97-180 234-455 39-74 401-500 51-127 Anthers per flower* 10 10 7 10 10 10 Tetrads per anther* Mean 317 1823 1031 402 753 Range 277-428 3200 2915-4016 1500-2100 881-1152 264-480 551-865 Pr o d u c t i v i t y i n t e t r a d s / „2* m 2.3 x 10' 4.1 x 10 8 3.3 x 10° 5.6 x 10 7 1.8 x 10 8 7.5 x 10 7 Species cover* 51% 56% 95% 56% 91% 78% *Means determined f o r 10 values. 47 CHAPTER 4: POLLEN DEPOSITION IN WETLAND ENVIRONMENTS OF THE FRASER RIVER DELTA Study of surface samples and p o l l e n r a i n forms an important aspect of Quaternary palynology. Wright (1967) emphasized the value of such i n v e s t i - gations i n previously unstudied regions and also where vegetation has been disturbed. Cohen (1973) demonstrated that p o l l e n spectra of surface samples provided f i n g e r p r i n t s for wetland communities. Such studies i n d i - cate that f o r e l u c i d a t i n g l o c a l vegetation changes, p o l l e n r a i n and surface sample data are indispensible, providing the information necessary to re l a t e vegetation to p o l l e n assemblages. In the present study, many surface sample analogs and near-analogs were found for zones recognized i n cores. This chapter presents the data and conclusions obtained from paly- nologic i n v e s t i g a t i o n s of modern environments and forms the basis for the in t e r p r e t a t i o n of f o s s i l deposits. The work was not intended to be exhaustive, but was used to provide as much c r i t i c a l information as possible to supplement the main paleoecologic research. A preliminary examination of core BBDC revealed that modern p o l l e n data from s a l t marsh, i n t e r t i d a l d e l t a - f r o n t , r i v e r marsh and bog environ- ments would be valuable for assistance i n accurate paleoecologic i n t e r p r e - t a t i o n . To obtain these data three d i f f e r e n t approaches were used: 1. P o l l e n r a i n was monitored at s a l t marsh and bog s i t e s i n the Fraser River Delta during the flowering seasons of 1974 and part of 1976. 2. Cover estimates of species i n the vegetation were made at these sites.. 3. M u l t i p l e surface samples from recently deposited sediments at 48 these and other l o c a t i o n s were analyzed f o r palynomorphs, A short core, an extension of surface sampling, was taken to provide i n s i g h t into the developmental sequence at a d e l t a ^ f r o n t s i t e . Methods Stations from three areas were chosen f o r intensive study (Fig. 10). At these l o c a l i t i e s , p o l l e n r a i n was monitored, surface samples analyzed and vegetation evaluated. At s i t e R, only p o l l e n r a i n data were obtained. Surface samples only were c o l l e c t e d from s i t e NP, r i v e r marsh, and de l t a - front environments because constant flooding washed away p o l l e n r a i n samp- l i n g dishes and j a r s . A short core was obtained from a sedge community ju s t outside the dike, south of the Middle Arm of the Fraser River on Lulu Island. Modern Polle n Rain: Various sampling methods for p o l l e n r a i n are av a i l a b l e (Lewis and Ogden, 1965). Most are designed to trap p o l l e n above the ground and do not r e g i s t e r material dropping d i r e c t l y to the surface from l o c a l flowers. This l a t t e r component supplies the most precise information f o r i n t e r p r e t - ing i n s i t u vegetation. In the present study, p o l l e n r a i n was c o l l e c t e d i n i t i a l l y on glass s l i d e s coated with glycerine j e l l y , and placed i n p e t r i dishes. Because of wash-out during rainy periods, the s i t e s had to be v i s i t e d too frequently, so the use of 100 mm deep glass jars containing g l y c e r i n and a few drops of phenol was substituted. Screens were attached over the mouths of the j a r s to keep out insects and voles (Sorex vagrans vagrans). Jars and dishes were c o l l e c t e d at various i n t e r v a l s , ranging from weekly to monthly, as time xE,F BOUNDARY BAY S T R A I T OF GEORGIA 50 permitted. Contents of j a r s and p e t r i dishes were rinsed out with hot water and poured through a coarse mesh screen i n t o 15 cc c o n i c a l centrifuge tubes. The material was then processed by a c e t o l y s i s , stained and mounted i n g l y c e r i n j e l l y on glass s l i d e s . Two hundred p o l l e n grains and spores were counted along transects on the s l i d e f o r each sample. Surface Samples: To provide the average p o l l e n and spore composition of the sediments below various vegetation types, 10-20 mm of the surface deposits were sampled with a 20 mm diameter, sharpened aluminum pipe. For s i t e s where po l l e n r a i n was also being monitored, three such samples were taken, a l l within .5 m of the c o l l e c t i n g j a r or dish, and inside the 2 m x 2 m quadrat evaluated f o r vegetation. This was done to keep the s p a t i a l r e l a t i o n s of surface sample, c o l l e c t i n g j a r and p o l l e n producing vegetation as close as possi b l e . Surface deposits were processed using a standard procedure con- s i s t i n g of HF treatment (when necessary), b o i l i n g i n 5% potassium hyroxide, a c e t o l y s i s , bleaching, screening (250 um) and s t a i n i n g with safranin. The residue was passed through an alcohol dehydration s e r i e s i n t o t e r t i a r y - b utyl alcohol and mounted i n s i l i c o n e o i l on glass s l i d e s . On the delta- front, j u s t outside the dike, a i m core was obtained by pushing a s t a i n l e s s s t e e l sampling tube into the s i l t s . The samples from the core were pro- cessed as above. In a l l cases, p o l l e n grains and spores were i d e n t i f i e d and counted along transects of s l i d e s , to a t o t a l of 200. 51 Results The r e s u l t s of p o l l e n r a i n , surface sample and vegetation analyses are presented and discussed together for each s i t e . A l l the figures (11-27) and Table 3 containing the r e s u l t s are located at the end of the chapter (PP- Sit e s from the Southern Periphery of Burns Bog: 1. Open Betula o c c i d e n t a l i s woodland with Pteridium aquilinum understorey (Site A). 2. Ledum groenlandicum heathland i n open Pinus contorta woodland (Sites B S C ) . 3. Spiraea d o u g l a s i i thickets i n open Betula o c c i d e n t a l i s woodland (Site D). 1. Open Betula o c c i d e n t a l i s woodland with Pteridium aquilinum understorey (Site A). The s i t e i s covered with t a l l Pteridium aquilinum from June u n t i l mid- September. I t also contains immature specimens of Spiraea d o u g l a s i i and Ledum groenlandicum (Fig. 11c). Stands of Betula o c c i d e n t a l i s surround the area, providing a cover ranging from 20-100%. The surface i s covered by a mat of Pteridium l i t t e r throughout the year. The s i g n i f i c a n t features of the p o l l e n r a i n (Fig. 11a) are as follows. Alnus, which i s part of the regional r a i n , dominates i n l a t e March and e a r l y A p r i l . This i s followed f i r s t by a heavy r a i n of Betula i n mid-April, and next by a small peak i n c f . Thuja. The Pinus contorta p o l l e n r a i n i s heavy i n mid-June, produced mainly by the pine stands 200 m to the north. This Pinus phase i s terminated by a gradual r i s e i n Gramineae p o l l e n that appears 52 to come from wetland stands of Ph a l a r i s arundinacea and mixed grasses from a g r i c u l t u r a l f i e l d s to the south. Grass p o l l e n dominates the spectrum u n t i l mid-August. During t h i s time, p o l l e n a t t r i b u t e d to Rumex c f . aceto- s e l l a and Chenopodiaceae also occurs, transported i n t o the s i t e from surrounding f i e l d s and perhaps from s a l t marshes i n Boundary Bay. Spiraea d o u g l a s i i p o l l e n , apparently produced by adjacent t h i c k e t s , ranges from l a t e July to October. In August-September, spores from on-site Pteridium aquilinum appear. F i n a l l y , when fern fronds have died down, Betula p o l l e n shows an abrupt increase i n September that appears anomalous. This i s at t r i b u t e d to b i r c h p o l l e n that has been s t i r r e d up from the dry surface by wind, or has f a l l e n along with dead leaves, and deposited i n the c o l l e c t i n g j a r s . Surface samples from s i t e A (Fig. l i b ) contain approximately equal qu a n t i t i e s (15-20%) of Pinus, Alnus, Betula and Pteridium. These types are well represented i n the po l l e n r a i n . The r e l a t i v e l y high Ericaceae l e v e l s seem anomalous as they are absent from both the p o l l e n r a i n and the vegeta- t i o n . Possibly, they derived from the peat substrate on which b i r c h woodland has developed. Notable i s the low value of Gramineae po l l e n , so common i n the summer p o l l e n r a i n . Together with the absence of c f . Thuja t h i s suggests that these r e l a t i v e l y t h i n walled grains do not survive on the dried-out fern l i t t e r substrate. Thin walled Pteridium spores may be pro- tected i n sporangia attached to frond fragments, as fern annuli are present i n the surface samples. Abundant quantities of fungal spores (see Table 3), Gelasinospora and Type-3 of Van Geel (V.G. 3) (see Appendix 3, F i g . 51c) are probably i n d i c a t o r s of humified l i t t e r (Van Geel, 1973). 53 2. Ledum groenlandicum heathland i n open Pinus contorta woodland (Sites B S C ) . Sit e s B and C are located 250 m and 450 m r e s p e c t i v e l y north of s i t e A (Fig. 10) i n open Ledum groenlandicum heathland within Pine Woodland vege- t a t i o n . Both l o c a l i t i e s are surrounded by dense Ledum (Figs. 12c, 13c), with s i g n i f i c a n t numbers of Vaccinium m y r t i l l o i d e s that are flowering at C, but barely flowering at B. S i t e C has a considerable cover of Gaultheria shallon, which', flowers only poorly. Pteridium aquilinum occurs at both l o c a l i t i e s . The p o l l e n r a i n diagrams from both B and C s i t e s (Figs. 12a, 13a) show reduced Betula peaks compared to s i t e A. The marked decreases i n Betula through the s i t e sequence, A, B, C, proceeding away from b i r c h stands, implies that 75% of the p o l l e n i s deposited within the f i r s t 500 m from the Betula stands. The d i s p e r s a l distance seems i n o r d i n a t e l y short e s p e c i a l l y because of the strong southeasterly winds that blow during t h i s period. Pinus p o l l e n l e v e l s are generally higher at s i t e s B and C than at A through- out the summer, presumably because of the proximity of the source trees. The non-arboreal (NAP) component at s i t e s B and C exhibits reductions i n p o l l e n of Gramineae, Rumex c f . a c e t o s e l l a and the Chenopodiaceae derived from farmlands. Apparently t h i s r e l a t e s to the increased distance of these stations from the edge of the bog. Ericaceae form a prominent part of the summer NAP. In July there i s an i n f l u x of tetrads l e s s than 30 um i n diameter that are ascribed to Ledum (see Ch. 3). At s i t e C tetrads i n the 30-36 um range o r i g i n a t e from whole flowers and anthers, f a l l e n or washed from plants of Vaccinium m y r t i l l o i d e s hanging above the sampling j a r . Low l e v e l s of Spiraea almost c e r t a i n l y transported from profusely flowering thickets around the bog periphery (cf. Janssen, 1973) are also recorded at 54 t h i s time. Fewer Pteridium spores are deposited than at s i t e A, r e f l e c t i n g the diminished r o l e of t h i s species i n the vegetation. The surface spectra of s i t e s B and C are dominated by Pinus (Figs. 12b, 13b). Ericaceae tetrads, most of which belong to Ledum, represent the l o c a l vegetation dominant. At s i t e C, s i g n i f i c a n t q u a n t i t i e s of Alnus and Tsuga are considered to represent the regional p o l l e n component. I t i s unclear why Alnus reaches much higher l e v e l s (25%) at s i t e C than at B. Sphagnum spores i n the surface samples at C i n d i c a t e that the s i t e i s s i t u a t e d on a Sphagnum peat substrate. Fungal m i c r o f o s s i l s from the surface include V.G. 3, and Microthyria- ceae ascocarps. Assulina and c f . Helicosporium rhizopod tests are also present. 3. Spiraea d o u g l a s i i thickets i n open Betula o c c i d e n t a l i s woodland (Site D). S i t e D was established i n extensive thickets of Spiraea d o u g l a s i i , 150 m east of s i t e A. Spiraea excludes almost a l l other species, with only Ledum occurring along with i t (Fig. 14c). The ground i s carpeted with Polytrichum juniperinum. The p o l l e n - r a i n diagram for t h i s s i t e (Fig. 14a) resembles that of s i t e A, but d i f f e r s i n having a major Spiraea peak i n l a t e July to September. There i s no Betula resurgence i n l a t e September as at s i t e A; dense growth of Spiraea probably prevents vigorous wind a c t i v i t y at ground l e v e l . Pollen analysis of surface deposits of l e a f and twig l i t t e r at s i t e D (Fig. 14b) shows s u b s t a n t i a l numbers of Betula and Spiraea p o l l e n . S i g n i f i - cantly, the f i r s t sample c o l l e c t e d i n A p r i l contained much more Betula p o l l e n than the two obtained l a t e r . This phenomenon was also observed at 55 s i t e A, and in d i c a t e s that a number of samples should be taken throughout the year to avoid anomalies a r i s i n g from coincident sampling time and l o c a l p o l l e n production. Alnus percentages are high, e s p e c i a l l y i n comparison to Pinus (15%), even though the pine p o l l e n source i s 200 m away, while the Alnus p o l l e n source i s at l e a s t 2 km d i s t a n t . Such a sharp decrease i n pine p o l l e n within a short distance of the producing vegetation has been observed by Turner (1964), and supports the exponential drop-off model (Janssen, 1973). Spiraea grains appear "melted", most l i k e l y as a r e s u l t of oxidation. P o l l e n of Nuphar lut e a and Sphagnum spores have probably been recycled from disturbed peat under the current vegetation. As at s i t e s A, B and C, grass and other herbaceous species are absent, although they are abundant i n the p o l l e n r a i n . Gelasinospora and traces of Desmidi- ospora and Assulina are also recorded at s i t e D. S i t e s from the I n t e r i o r of Burns Bog: 1. Pinus contorta woodland (Site H). 2. Sphagnum heathland (Sites I and R). 3. Sphagnum heathland c l e a r i n g i n Pinus contorta woodland (Site G). 4. Nuphar lut e a pond i n Sphagnum heathland (Site NP). 1. Pinus contorta woodland (Site H). This s t a t i o n i s characterized by a dense stand of Pinus contorta, con- t a i n i n g an understorey of Ledum groenlandicum and Vaccinium uliginosum (Fig. 15c). Throughout the year, the p o l l e n r a i n i s c l e a r l y dominated by Pinus, with percentages r a r e l y dropping below 50% (Fig. 15a). Alnus reaches appreciable l e v e l s i n spring and autumn, when the l o c a l Pinus component drops enough to unmask the regional p o l l e n r a i n . Ericaceae, including 56 tetrads of a l l s i z e classes, f a l l from the surrounding bushes i n the summer. The lack of other p o l l e n types r e f l e c t s the overwhelming l o c a l Pinus pro- duction, and perhaps also a f i l t e r i n g e f f e c t from the crowns of the trees. The surface spectrum of s i t e H c l e a r l y demonstrates that Pinus p o l l e n d i l u t e s a l l other types (Fig. 15b). Thus high Pinus percentages would be expected to characterize pine woodland vegetation i n f o s s i l deposits. Only Alnus and Ericaceae (from plants on the site ) contribute s i g n i f i c a n t l y . Most Ericaceae tetrads are of the Ledum type although some belong to the greater than 36 um s i z e c l a s s , r e f l e c t i n g l o c a l l y abundant Vaccinium uliginosum and Gaultheria shallon. In addition to p o l l e n , the samples contain numerous fungal hyphae and brown, amorphous, organic aggregates. One Assulina t e s t was recorded. 2. Sphagnum heathland (Sites I and R). These stations are located about 100 m and 300 m r e s p e c t i v e l y , north of the pine woods containing s i t e H. At s i t e I, the sampling j a r was placed i n a shallow, Sphagnum-lined depression, occupied by Andromeda p o l i f o l i a , Vaccinium oxycoccos and Vaccinium uliginosum (Fig. 16c). Shoots of Rhynchospora alba are common although they do not constitute a high cover value. Stunted Pinus contorta trees grow around the s i t e . The vegetation at s i t e R i s s i m i l a r to that at s i t e I, but with more V. u l i g i n o - sum and le s s Rhynchospora. In contrast to the s i t u a t i o n i n pine woodland, Pinus does not dominate the p o l l e n r a i n diagrams of s i t e s I and R (Figs. 16a, 17). In A p r i l and early May, regional arboreal p o l l e n types such as c f . Thuj a, Tsuga, Pseudo- tsuga, Alnus and Betula compose the p o l l e n r a i n . Large Ericaceae tetrads shed by the heath species at the s i t e s are present during the year. At 57 s i t e I, c f . Rhynchospora p o l l e n i s produced e a r l y i n August. Much of the p o l l e n a r r i v i n g i n Sphagnum heathland during the summer, e.g. Gramineae, i s derived from sources external to the bog. Sphagnum spores are conspicu- ously absent although Sphagnum spp. completely blanket the ground around s i t e I. The surface deposits of s i t e I (Fig. 16b) reveal that much of the pre- served p o l l e n o r i g i n a t e d outside the l o c a l area. Alnus and Tsuga make up 45% of the t o t a l . Pinus, although i t produces l i t t l e p o l l e n at the s i t e , reaches 39% i n the c o l l e c t e d samples. The Ericaceae, which blanket the ground around the s i t e , comprise only 4% of the pol l e n spectrum, a case of very pronounced underrepresentation. A l l of the tetrads were greater than 30 ym i n diameter, and most f e l l i n t o the greater than 36 ym size range. As has been shown i n Ch. 3, er i c a d species producing p o l l e n tetrads i n t h i s diameter range are characterized by low p o l l e n p r o d u c t i v i t y values and these surface sample r e s u l t s confirm the p r e d i c t i o n of underrepresenta- t i o n f o r these species growing at the s i t e . The absence of Sphagnum spp. spores agrees with the p o l l e n r a i n r e s u l t s . I r r e g ular Sphagnum spore p r o d u c t i v i t y has been observed by others (Tinsley and Smith, 1973) and seems to be a function of l o c a l conditions ( T a l l i s , 1964). Desmidiospora i s preserved abundantly i n the Sphagnum peats along with other indeterminate fungal aggregates. The rhizopod c f . Helicosporium i s also present. The e c o l o g i c a l s i g n i f i c a n c e of Desmidiospora i s not under- stood. Since the o r i g i n a l d e s c r i p t i o n by Thaxter (1891) of Desmidiospora growing on ants under a r o t t i n g log, t h i s fungus has remained uninvestigat- ed. This spore type i s always associated with Sphagnum/heath peats i n 58 Burns Bog and has been noticed i n the same habitat i n Camosum Bog, Vancou- ver, B r i t i s h Columbia (R. J . Bandoni, personal communication), Van Geel (1973), while including a photograph of Desmidiospora, was unable to make an i d e n t i f i c a t i o n , nor assign to i t s p e c i f i c ecologic conditions. 3. Sphagnum heathland c l e a r i n g i n Pinus contorta woodland (Site G). This area of a c t i v e Sphagnum growth i s located i n a small elongate c l e a r i n g , 100 m south of s i t e H, surrounded on a l l sides by dense stands of Pinus contorta. To the north and south, Pine Woodland approaches within 25 m of the s i t e ; to the east and west the trees are at l e a s t 100 m dista n t . The vegetation i s characterized by heaths (Fig. 18c), growing on and between Sphagnum capillaceum hummocks. Sphagnum recurvum occupies the low, wet inter-hummock areas. Two drainage ditches occur nearby, causing some l o c a l a l t e r a t i o n of the water table. Although t h i s s i t e i s c l o s e l y associated with pine woods, the p o l l e n r a i n of t h i s s t a t i o n (Fig. 18a) shows d i s t i n c t i v e features, resembling the patterns of s i t e s I and R i n Sphagnum heathland. A pronounced peak i n Sphagnum spores occurring i n l a t e July distinguishes the p o l l e n r a i n of s i t e G from that of s i t e s I and R. The surface spectrum of t h i s Sphagnum heathland c l e a r i n g (Fig. 18b) reveals that Pinus p o l l e n occurs at a much lower percentage than i n nearby pine stands ( s i t e H). This observation implies that even small clearings i n a pine matrix could be recognizable i n the f o s s i l record. Ericaceae tetrads f a l l i n the 30-36 um group, and are probably those of Kalmia microphylla which grows abundantly at the site(Fig.32-18c). There are many Sphagnum spores present i n the surface samples, i n contrast to the other Sphagnum s i t e , I. Desmidiospora, indeterminate fungal aggregates, Assulina, 59 c f . Helicosporium and A c t i n o p e l t i s abound i n the surface deposits. 4. Nuphar lut e a pond i n Sphagnum heathland (Site NP), Two surface samples were analyzed from s i t e NP (Fig, 19) to determine whether Nuphar ponds could be d i f f e r e n t i a t e d p a l y n o l o g i c a l l y from other Sphagnum heathland associations. The pond sampled i s s i t u a t e d i n the cen- t r a l portion of Burns Bog (Fig. 10). Sphagnum recurvum i s packed i n among the Nuphar plants so that i n the dry, l a t e summer the s i t e does not look l i k e a pond. T y p i c a l wet habitat heaths, such as Kalmia microphylla, Andromeda p o l i f o l i a , Vaccinium oxycoccos, and Vaccinium uliginosum approach to within a meter of the sampling s i t e , while Ledum and Pinus grow about 5 m away. Pinus p o l l e n from l o c a l sources and Alnus from the regional arboreal component are the two most abundant types (approximately 30% each). Another regional p o l l e n type, Tsuga, i s next i n abundance at 12%. Gramineae and Chenopodiaceae p o l l e n , presumably derived from a g r i c u l t u r a l f i e l d s around the bog also occur i n s i g n i f i c a n t q u a n t i t i e s . Ericaceae are very poorly represented as expected from p r o d u c t i v i t y studies. Nuphar p o l l e n and Sphagnum spores, the two types r e f l e c t i n g the .in s i t u vegetation are record- ed i n extremely small q u a n t i t i e s . This observation supports the p r i n c i p l e that i n t e r p r e t a t i o n s of plant assemblage composition cannot be made on the basis of abundance of p o l l e n types (Cohen, 1973). C h a r a c t e r i s t i c palyno- l o g i c f i n g e r p r i n t s f o r communities must be obtained from the sediments into which they are incorporated. Desmidiospora fungal spores, c f . Helicosporium rhizopod tests and Nuphar lu t e a trichomes were also recorded from the sediments. 60 Coastal S i t e s from Boundary Bay: 1. Chenopodiaceae s a l t marsh (Site E ) . 2. Coastal grassland (Site F ) . 1. Chenopodiaceae s a l t marsh (Site E). S i t e E i s located 3 km d i r e c t l y south of Burns' Bog, at the edge of a very extensive, t i d a l - f l a t dominated, shallow bay (Fig. 10). The vegeta- t i o n around the s i t e i s composed of S a l i c o r n i a v i r g i n i c a , D i s t i c h l i s s picata, P u c c i n n e l l i a grandis and Plantago maritima (Fig. 21' c ) . Coastal grassland begins 30 m to the north, whereas t i d a l f l a t s extend to within 10 m i n the other d i r e c t i o n s . Waves, driven by storm winds, inundate the s a l t marsh p e r i o d i c a l l y . The p o l l e n r a i n diagram f o r s i t e E (Fig. 21a) indicates that arboreal p o l l e n from d e l t a i c and upland trees dominates during the spring, with Alnus (60%) as the major component. In May there i s an i n i t i a l peak i n grasses, followed by peaks i n Plantago maritima and T r i g l o c h i n maritimum. Grass p o l l e n predominates i n July, followed by high numbers of l o c a l l y derived chenopod p o l l e n , produced by S a l i c o r n i a and A t r i p l e x t r i a n g u l a r i s . The s i l t y sands of t h i s s i t e contain moderately high numbers of p o l l e n of Chenopodiaceae (30%), Gramineae (22%) and Alnus (21%) (Fig. 21b). In contrast, the l e v e l s of Pinus p o l l e n and T r i g l o c h i n p o l l e n are low. Many of the grains are badly corroded, r e f l e c t i n g the considerable b i o l o g i c a c t i v i t y i n the sediments. Chitinous t e s t s of microforaminifera and hystrichospheres are abundant, and there i s a l o t of f i n e l y dispersed black d e t r i t u s . 2. Coastal grassland (Site F). At t h i s l o c a l i t y , about 70 m north of s i t e E and behind a ridge of 61 d r i f t e d logs colonized by Elymus m o l l i s , grasses predominate (Fig. 22c) with Aster subspicatus and A c h i l l e a m i l l e f o l i u m as the other major compon- ents of the vegetation. The p o l l e n r a i n diagram (Fig. 22a) resembles that from the chenopod s a l t marsh i n the spring, with regional arboreal species well represented. Peaks i n Rumex and T r i g l o c h i n occur immediately afterward. Throughout the re s t of the season, grass p o l l e n comprises v i r t u a l l y a l l of the p o l l e n r a i n . At t h i s s i t e , chenopod p o l l e n never reaches as high values as at s i t e E, suggesting that the absolute number of grains to reach s i t e F i s lower. At the end of the season, p o l l e n produced by l o c a l l y growing Compositae i s mixed with that of the grasses. Poll e n analysis of the sandy fibrous s o i l reveals that the po l l e n of the Chenopodiaceae i s the most common. Grass p o l l e n occurs i n s u r p r i s i n g l y low q u a n t i t i e s i n s p i t e of i t s high l e v e l i n the p o l l e n - r a i n (Fig. 22b). Many of the grains are folded and corroded. As i n bog sediments, grass p o l l e n i s apparently s e l e c t i v e l y destroyed because of i t s t h i n exine. The percentage of Compositae p o l l e n r e f l e c t s the proportion of t h i s group i n the vegetation (Fig. 22c). The s o i l contains numerous amorphous, organic aggregates a t t e s t i n g to the possible loss of p o l l e n through decomposition. F l u v i a l Environments - Surface Samples: 1. River marshes (Sites L - l , 2, & 3). 2. River swamps (Sites L-4, 5). 3. Delta-front marshes (Sites DF-1, 2, 3 & 4). 4. Delta-front short core (Site DF-5). Surface samples were analyzed p a l y n o l o g i c a l l y from selected environ- ments along channels and at the mouth of the Fraser River (Fig. 10) to 62 obtain the p o l l e n and spore " f i n g e r p r i n t s " c h a r a c t e r i s t i c of the sediments i n these s i t e s . In addition, a short core was taken to determine whether the h o r i z o n t a l zonation of plant assemblages on the emergent d e l t a - f r o n t was recorded as a successional sequence i n sediments just outside the dike. 1. River marshes (Sites L - l , 2, & 3). Three samples of organic s i l t s were obtained from a marsh between the tree-covered banks (Alnus rubra, Populus balsamifera subsp. trichocarpa, S a l i x spp., Picea sitchensis) and the active r i v e r channel. Here the vege- t a t i o n consists of emergent aquatics, with Menyanthes t r i f o l i a t a , Lysichitum americanum, Carex sp. and Gramineae growing nearest to the bank. Dense stands of Scirpus sp., Equisetum sp. and sometimes Typha l a t i f o l i a are located at the edge of the water, and Alisma plantago-aquatica and S a g i t t a r - i a l a t i f o l i a grow among the stems of these plants. In the AP (Fig. 23 a, b, c ) , Pinus and Alnus predominate, with smaller but s i g n i f i c a n t amounts of Tsuga heterophy11a and Picea also present. Many of the arboreal grains are considerably corroded. Taken together, these features i n d i c a t e a r i v e r source for at l e a s t p art of the arboreal component. The high l e v e l s of Pinus must be a t t r i b u t e d to r i v e r transport, as the nearest source of pine i s Burns Bog 5 km away. Cyperaceae p o l l e n character- i z e s the NAP, probably o r i g i n a t i n g from two sources; r i v e r transport and l o c a l vegetation. Undamaged grains are f a i r l y abundant and i t seems that these were produced l o c a l l y . The NAP appears to r e f l e c t vegetation v a r i a - t i o n from s i t e to s i t e as demonstrated i n F i g . 23a from s i t e L - l , near which Lysichitum and Gramineae grow, and i n F i g . 23c from s i t e L-3 surrounded p a r t l y by Equisetum sp. In a l l cases the proportion of the p o l l e n and spore 63 types of these species i s low i n comparison to t h e i r major r o l e i n the l o c a l vegetation. P a r t i c u l a r l y i n t e r e s t i n g i s the absence of Menyanthes poll e n at L - l (Fig. 23a) where the plant grows well and many seed pods are produced. Typha, occupying major areas of the l o c a l vegetation, i s also poorly represented, as are S a g i t t a r i a and Alisma. I t was observed that very few flowers were formed by these l a s t two genera. Equisetum i n these habitats, produces l i m i t e d numbers of spores i n small s t r o b i l i . Fungal spores are not abundant; only a few c f . Curvularia, c f . Periconia and type 1 were found. 2. River swamps (Sites L-4, & 5). Samples from s i t e L-4 and L-5 were taken from a quiet backswamp, behind p a r t i a l l y natural levees. The same tree species as near s i t e s L - l to L-3 surround the area and S a l i x spp., Rubus s p e c t a b i l i s and Cornus s e r i c e a . appear to be advancing into the swamp. The surface i s infrequently inundat- ed during periods of high water. The vegetation of L-4 and L-5 i s very s i m i l a r to that of the r i v e r marshes, with Lysichitum americanum, Typha l a t i f o l i a , Equisetum sp. and Scirpus sp. dominating. S i m i l a r i t i e s also occur i n the p o l l e n spectra of the r i v e r marshes (Fig. 23a, b, c) and r i v e r swamp s i t e s (Fig. 24a, b), with Pinus and Alnus predominating. Tsuga i s also present, whereas Picea i s absent. The l o c a l colonies of Typha, Equisetum and Lysichitum are r e f l e c t e d i n the NAP f r a c - t i o n . The discovery of Sphagnum spores at both L-4 and L-5 seems unusual as no Sphagnum grows anywhere i n the v i c i n i t y . The source of these spores appears to be a d i t c h some 200 m east of the s i t e s which drains Burns Bog, about 1-2 km to the south. I t also seems l i k e l y that d i t c h output also provides some of the pine p o l l e n . 64 Fungal m i c r o f o s s i l s are also preserved i n these backswamp sediments, including c f . Periconia, T i l l e t i a and c f . D a c t y l a r i a , 3, Delta-front marshes (Sites DF-1, 2, 3, 4). Surface samples were analyzed from each of three recognizable plant assemblages (zones) seaward of the dike on the northern end of Lulu Island (Fig. 10). Conditions here are brackish from mixing of fresh water from the Middle Arm of the Fraser River with s a l t water from the S t r a i t of Georgia. The emergent plant communities of the d e l t a - f r o n t have been described by Forbes (1972). Scirpus americanus and Scirpus paludosus form the f i r s t emergent plant assemblage (Fig. 25). A surface sample was taken from each of two s i t e s ; one dominated by S_. americanus (DF-1), the other dominated by S_. paludosus (DF-2) . S i l t s were sampled i n the Typha l a t i f o l i a zone (DF-3) , bordering the Scirpus spp. zone on the shoreward side, and also from the Carex l y n g b e y i - P o t e n t i l l a p a c i f i c a assemblage (two samples) ( s i t e DF-4) between the Typha zone and the dike. This l a s t assemblage, although domin- ated by sedges, also contains considerable numbers of Penanthe sarmentosa. The p o l l e n spectra f or DF-1, 2, 3, and 4 (Fig. 26a, b, c, respectively) a l l show high percentages of Pinus and Alnus and hence are comparable with s i t e s along the r i v e r . In the Scirpus spp. and Carex-Potentilla zones, Cyperaceae p o l l e n ranges from 40-50%. P o t e n t i l l a p o l l e n , although present i n small q u a n t i t i e s (2%) (Fig. 26c), i s probably diagnostic of the Carex- P o t e n t i l l a zone. In the Typha l a t i f o l i a stand, Typha tetrads reach about 30%, whereas Cyperaceae frequencies are reduced. Gramineae p o l l e n i s s i g - n i f i c a n t l y represented i n a l l diagrams, r e f l e c t i n g the a g r i c u l t u r a l f i e l d s on shore. The percentages of c f . Athyrium fern spores i s s u r p r i s i n g as no 65 ferns grow i n these marshes. However, Athyrium f i l i x - f e m i n a has been observed growing s p o r a d i c a l l y i n semi-open, swampy habitats along the r i v e r . This fern produces tremendous qu a n t i t i e s of spores i n sporangia that r e a d i l y break away from t h e i r attachment i n the sorus. Both sporan- gi a and spores may be subsequently f l o a t e d down the r i v e r and deposited i n the s i l t s of the d e l t a - f r o n t . Reworked T e r t i a r y p o l l e n (recognized on the basis of amber colour) seems s i m i l a r l y to be washed down the r i v e r and deposited l i t o r a l l y , as numerous reworked grains are recovered from DF-1 and 2. F l u v i a l transport of palynomorphs with subsequent l i t t o r a l deposi- t i o n has been noted f o r other large r i v e r s (Muller, 1959). A host of non-vascular plant palynomorphs characterizes d e l t a - f r o n t sediments. Two types, c f . Periconia and Type 1 occur i n great numbers i n these p a r t i c u l a r habitats. Large, cle a r , thick-walled palynomorphs (fungal oogonia) ' also appear to be representative of these sediments. Other types encountered include D i p o r i s p o r i t e s Hammen emend E l s i k ( E l s i k , 1968) and chitinous t e s t s of foraminifera. There i s a high concentration of organic fragments and f i n e black d e t r i t u s . 4. Delta-front short core (Site DF-5). A short core (1 m x .05 m diameter) was obtained by d r i v i n g a s t a i n l e s s s t e e l tube into the organic s i l t s j u s t o f f the dike i n the Carex-Potentilla community. Ninety centimeters were recovered, divided into 15 cm lengths, and analyzed for p o l l e n . The p o l l e n diagram of the major species (Fig. 27) reveals two stages. The bottom h a l f with high percentages of Cyperaceae p o l l e n represents the Scirpus spp. zone. From about the .65 m l e v e l , the frequency of Typha l a t i f o l i a increases markedly, accompanied by a decrease i n Cyperaceae p o l l e n . This change represents the development of the Typha 66 l a t i f o l i a community shoreward of the Scirpus spp, zone. The s h i f t to the present Carex-Potentilla assemblage has occurred very recently, as there i s no i n d i c a t i o n of t h i s (such as decreasing Typha) i n the upper l e v e l s of the core. Grass p o l l e n i s well preserved, i n marked contrast to both bog and coastal meadow deposits. One possible explanation i s that the r e l a t i v e - l y t h i n walled grass p o l l e n preserves best when deposited i n an environment that i s often submerged, whereas grass p o l l e n deposited on surfaces that dry out i s r a p i d l y destroyed, p o s s i b l y by oxidation and microorganism attack. Summary and Conclusions The r e s u l t s of t h i s study of p o l l e n r a i n , of p o l l e n spectra of surface samples,and of the r e l a t i o n s h i p of these to vegetation, show that vegeta- t i o n types i n the study area can be characterized and d i f f e r e n t i a t e d on the basis of palynomorph assemblages including m i c r o f o s s i l s other than p o l l e n and spores. However as Cohen (1973) observed, i n t e r p r e t a t i o n of plant assemblage composition can not be made on the basis of abundance of po l l e n types. Currently forming bog deposits contain high concentrations of Pinus, Alnus, and Ericaceae and sometimes of Sphagnum spores. Wet and dry heath- land communities can be d i f f e r e n t i a t e d on the basis of te t r a d diameter d i s t r i b u t i o n i n the er i c a d spectrum of the surface sediments. Areas of b i r c h , Spiraea or Pteridium contain r e l a t i v e l y high percentages of these species i n the surface deposits. S a l t marsh and coastal grassland se d i - ments are characterized by high concentrations of chenopod and grass p o l l e n . F l u v i a l sediments of marshes and swamps contain high percentages of Pinus along with considerable Picea, Tsuga and Alnus. Cyperaceae grains also 67 occur abundantly but other l o c a l l y dominant types such as Menyanthes and Equisetum sp. are underrepresented. Sediments of the i n t e r t i d a l zone of the d e l t a - f r o n t s i m i l a r l y contain abundant quantities of Pinus, Picea, Tsuga and Alnus p o l l e n . Cyperaceae p o l l e n l e v e l s are high i n the s i l t s of the Scirpus spp.-dominated zone and the Carex l y n g b e y i - P o t e n t i l l a p a c i f - i c a zone. The s i l t s below Typha stands contain abundant Typha tetrads. The palynomorph assemblages of the d i f f e r e n t wetland environments examined provide " f i n g e r p r i n t s " for the recognition of these environments i n sediments obtained from cores. 68 Figures 11-27, Table _3• The following pages contain the figures r e f e r r e d to i n Ch. 4. The diagrams for each s i t e are grouped under one figure number which i s sub- divided as follows: a) p o l l e n r a i n , b) surface p o l l e n spectrum, c) species cover (vegetation). F i g . 25 (p. 92) depicts the vegetation zones of the Lulu Island fore- shore. F i g . 27 (p. 94) i s the p o l l e n diagram for the short core taken at s i t e DF-5. Table 3 (p. 95) summarizes the d i s t r i b u t i o n of non-vascular plant palynomorphs from wetland s i t e s investigated by p o l l e n analysis of surface samples. 69 Figure 11: Diagrams for site A, open Betula occidental is woodland with Pteridium aquilinum understorey; 11a) pollen rain diagram Other t y p e s ; Tsuga, Picea, Abies, Pseudotsuga, Acer macrophgllum, E r i c a c e a e Hynca, Cyperaceae, Plantago, L i l i a c e a e , C o n p o s i t a e , Typha, Leguminosae, Monolete P o l y p o d i a c e a e , Sphagnum. 70 Figure 1lb,c: Diagrams for site A continued; lib) surface pollen spectrum TOO -B 80 -S •a | 40 J £ 20 - f 1 WOODY PEAT 1 / Other t y p e s ; Picea(1%), Kbies(.5%) , Pseudotsuga(3%), Spiraea(1%), Compositae)'l%J , Gramineae(2%) , average o f 3 samples. l ie) species cover 100 - j 80 -1 ce 71 Figure 12: Diagrams for site B, Ledum groenlandicum.heathland in Pinus contorta woodland; 12a) pollen rain diagram M Other t y p e s ; Tsuga, Picea, Abies, Pseudotsuga, Ilex, Salix, Acer macrophgllum, Cyperaceae, Chenopodiaceae, Plantago, Rumex, Compositae, U r a b e l l i f e r a e , M o n o l e t e P o l y p o d i a c e a e , Sphagnum. 72 figure ]2byc: Diagrams for site B continued; T2b) surface pollen spectrum Other t y p e s ; A b i e s (1%), Picea(2%) , Pseudotsuga(1%) of. Thuja (1%), Betula(2%) , Gramineae(2%), Cyperaceae (1%) Sphagnum(1%) , average jof 3 samples. 12c) species cover \OO-t um 60 A 73 Figure 13: Diagrams for site C, Ledum groenlandicum heathland in Pinus contorta woodland; 13a) pollen rain diagram M A M J J A S 0 Other t y p e s ; Tsuga, Picea, Abies, Pseudotsuga, Acer macrophgHum, Salix, Spiraea, Cyperaceae, Plantago, Rumex, Typha, Leguminosae, U m b e l l i f e r a e . 74 Figure 13 b,c: Diagrams for site C continued; 13b) surface pollen spectrum 10O- w 80 -•3 z U J PO LL  60 - =! TO T/  40 - 20 _ 1 HEATH P E A T 1 / Other types; Abies (IX), Picea(l%), Pseudotsuga(1%), cf.Thuja (IX), Betula(2%) , Umbelliferae(1%) , Grainineae(3%),Chenopodiaceae (1%), Compositae(1%), Pteridium(3%), average of 3 samples. 13c) species cover TOO - 80 - CC j§ 60 - >- z U J £ 40 - 20 - 0 1 v cf 75 .Figure 14: Diagrams for site D, Spiraea douglasii thickets in open Betula occidentalis woodland; 14a) pollen rain diagram Other t y p e s ; Tsuga, Picea, Abies, Pseudotsuga, Acer rnacrophyllum, Sali Cyperaceae, Chenopodiaceae, Plantago, L i l i a c e a e , Compositae, Typha, Leguminosae, U m b e l l i f e r a e , Monolete P o l y p o d i a c e a e . 76 Figure 14b,c: Diagrams for site D continued; 14b) surface pollen spectrum 100- 1 J L 1 •S Other t y p e s ; Abies(lX), Picea(2%), Pseudotsuga(IX), cf.Thuja(1%), Acer macrophyllum(lX), Ericaceae(2%) ,Gramineae(4%), Chenopodiaceae (IX),Compositae(7%;, Typha latifolia(lX), Cyperaceae(2%) , Nuphar (2%),Pteridium aqullinum(4%), Sphagnum(2X), average o f 3 samples. 14c) species cover K>0 i 80 -I cn L U 60 - 40 - 20 - 0 4 77 Figure 15: Diagrams for site H, Pinus contorta woodland; 15a) pollen rain diagram M A M J J A S 0 Other t y p e s ; Thuja-type, Tsuga, Abies, Pseudotsuga, Betula, Typha, ..Chenopodiaceae, Plantago, Leguminosae, Sphagnum, Pteridium, P o l y p o d i a c e a e . 78 Figure 15 b,c: Diagrams for site H continued; 15b) surface pollen spect rum co 100-a 80 -j 60 -I 20 HEATH PEAT Other t y p e s ; Ab ies(.5%), Gramineae(1%), a ve rage o f 3 samples. 15c) species cover 80 S 60 - i g 40 L U c 20 0 •/ / / / / / 79 Figure 15: Diagrams for site I, Sphagnum heathland; 15a) pollen rain diagram Pinus ^^^^ Thuja / ^ s - ^ ^ Pseudotsuga s« - i n CVI - m _ cr. • a m >•• TJ - u ra Ci - •u " c _ O o i- • Ci B e t u l a E r i c a c e a e Chenopodiaceae Gramineae ^ ^ ^ ^ ^ ^ ^ ^ - P o l y p o d i a c e a e _ ^ . M A M J J A S 0 Other t y p e s ; Tsuga, Picea, Abies, Acer macrophyllum. Spiraea, Cyperaceae, Plantago, Rumex, Compositae, Typha, Leguminosae, L i l i a c e a e , U m b e l l i f e r a e , Sphagnum. 80 Figure 16 b,c: Diagrams for site I continued; 16b) surface pollen spectrum 100 "> 80 I 60 40 20 -I s E 0 1 . 1 . C h e n o p o d i a c e a e a * ; , C y p e r a c e a e a * ; , Typha<1%,, Sphagnwn(3%) average of 3 samples. j"""gnum (j*;, 16c) species cover lOO-i 80 H UJ > 8 60 H 40 - 20 - 0 1 o > V A ? s i 81 Figure 17: Pollen rain diagram for site R, Sphagnum heathland. Other types; Picea, Abies, Acer macrophyllum, Cyperaceae, Plantago, Rumex, Typha, Compositae, Leguminosae, P o l y p o d i a c e a e , Sphagnum. 82 Figure 18: Diagrams for site G, Sphagnum heathland clearing in in Pinus contorta woodland. 18a) pollen rain diagram M M Other t y p e s ; Picea, Abies, Acer macrophyllum, Salix, Myrica, Spiraea, Typha, Rhynchospora, Cyperaceae, Chenopodiaceae, Compositae, Plantago, Polygonum, Rumex, Nuphar, Leguminosae," Pteridium, P o l y p o d i a c e a e . 83 Figure 18 b,c: Diagrams for site G continued; 18b) surface pollen spectrum tn KO- c= o c_ «! 80 . 3 60 o~ o 40 t— & £ 0 SPHAGNUM PEAT Other types; Abies(l%), Picea(.5%), Pseudotsuga (15), cf.Thuja (1%), Rubus chamaemorus(.5%), Gramineae(1%), average of 3 samples. 18c) species cover 1CO-* 80 -| 60 40 ~ f 20 - I 0 J . / v A o / 84 Fi V) U4 ce s s o gure 19: Surface pollen spectrum, site NP, Nuphar pond, in Sphagnum heathland. lOO-i 80 - 60 -I 40 - 20 - &e 1 JL LIVE SPHAGNUM / JO cf / Other t y p e s ; Abies(1%), Picea(.5%), Pseudotsuga(1%), cf.Thuja (2%), Betula(2%), Myrica(1%), Plantago(.5%), Uuphar(2%). Sphagnum(.5%), average o f 2 samples. 85 Figure 21: Diagrams for site E, Chenopodiaceae salt marsh; 21a) pollen rain diagram I P i n u s CM » 1 u S- o Betula Alnus / - Gramineae \ PJantago >v Triglochin Other t y p e s ; Pseudotsuga, A c e r macrophyllum, Salix, Rumex, Spergularia, Cuscuta, J u n c u s - t y p e , Compositae, P o l y p o d i a c e a e . 86 Figure 21b,c: Diagrams for site E continued; 21b) surface pollen spectrum 100 - f Other t y p e s ; Abies(.5%) , Picea(2%), Tsuga(2%), Pseudo- tsuga (2%) , c f . Thuja(1%), Plantago(2%), Compositaef2%; , Cyperaceae(1%), average o f 3 samples. 87 Figure 22: Diagrams for site F, coastal grassland; 22a) pollen rain diagram Pinus - Thuja • Tsuga Abies IT) • C J Pseudotsuga to * l — Alnus c: '—-—"— - ^ o - v> > Betula ch  d i > • Chenopodiaceae // / /^ S sV.^ /^^""^^^- 1 | rc en t (e a G r a m i n e a ^ ^ ^ ^ ^ ^ ^ ^ ^ <t>. a. Composicae- T u b u l i f l o r a e Rumex • Triglochin ^•^^^ A M J J A S 0 Other t y p e s ; Acer macrophyllum, Salix, Cuscuta, Plantago, Galium, Typha, Cyperaceae, U m b e l l i f e r a e , P o l y p o d i a c e a e . 88 Figure 22 b.c: Diagrams for site F continued; 22b) surface pollen spectrum DRY, PEATY SAND Other t y p e s ; Picea(.5%), Tsuga(2%), average of 3 sample 22c) species cover 100- eo H g 60 -] | 4 0 - | 20 A / / / *• / / 0* // sy 89 Figure 23: Surface pollen spectra of river marsh sites; 23a). Site L - l , river marsh, Menyanthes-Lysichitum-Gramineae s " 8 0 - 1 a 6o_| £ I 40 -j t- 2 0 - | U J C J cc £ 0 j — J L ORGANIC SILTS 1 Other .types; P s e udotsugaf.5%,, B e t u l a f . 5 % , , E r i c a c e a e a * ; , Typha (3%), Equisetum(3.5%), Monolete f e r n s ,3.5*;, S ^ h a g ^ u ^ ^ J ' 23b) Site L-2, river marsh, Ejuise_tum-Scirpus-Sagittaria-AIisma £2 100-, c: £ 1 80 H | 60 A -i 20 " i ORGANIC SILTS I • • • • A A V. A / Other t y p e s ; Abies(.5%), Pseudotsuga(1%), c f . T h u j a ( 2 % ) , Betula(1%) SalixUZ), E r i c a c e a e ^ . 5 % ; , Chenopodiaceaef2%; , T y p h a f l . 5 % ; , ALisrca ^.5,;, Eguisetu/nn.5%;, Monolete f e r n s f 4 % ; , Sphagnum(3.5%) . 90 Figure 23c) Surface pollen spectra of river marsh sites continued; Site L-3, Scirpus-Sagittaria-Equisetum. S3 E CO WO-, 80 - i 3 6 0 - | o Cc ° 20-1 £ 0 ORGANIC SILTS I • - I I • £ <* «? V Other t y p e s ; Abies(1%), Pseudotsuga(1.5%), cf.Thuja(.5%), Betula (.5%), Salix(.5%), Myrica(.5%), Typha (2%) , Monolete f e r a s ; , Sphagnum(1%). 91 Figure 24: Surface pollen spectra of river swamp sites, L-4, L-5; 24a) site L-4, Typha-Equisetum w TOO-» e « 80 -I a 60 o H 40 - | 20 H S 0 SILTY PEATS °J?r 'y?6S; (J"5%;- Pseudotsuga cf .Thuja C e a e ^ 5 % ; ' ; 5 r c e"t^«'nr.5%;, L a b i a t a e C l * ; , Gramin- eae (2%) , Chenopodiaceae f.5%), Compositae f .5*;, Lysichitum(1.5%) Sagittana(1.5%) , Equisetum(.5%), Monolete iems(l%) , Sphagnum (8%). 24b) site L-5, Equisetum-Lysichitum-Scirpus loo-* — i o 80 60 40 20 0 1 SILTY" PEATS V CP 4 / •Jo Other t y p e s ; Abies(1.5%), Picea(3%), Pseudotsuga(1%), Betula (.5%), E r i c a c e a e ( 3 % ) , Gramineae (1.5%), Chenopodiaceaef.5%;, Malvaceae(.5%) , Typha(3%), Sagittariaf.5%), Sphagnum(13%). 92 FIGURE 25 :VEGETATION ZONES OF THE LULU ISLAND FORESHORE* LEGEND FRASER RIVER 93 Figure 25: Surface pollen spectra from delta-front marshes, DF 1,2,3 & 4; 26a) sites DF 1&2, Scirpus zone o 100 - CO eS 8 0 - z _J —1 6 0 - a. < 4 0 - ES • i 2 0 - o CC Other t y p e s ; Abies(.5%), Pseudotsuga(.5%), Betula'.5%) , Salix( .5%) , Tilia(.5%) , Plant ago (1.5%)i', L i l l a c e a e (1.5%), Typha(2%), Chenopodiaceae(.5%), average of 3 samples. 1 SANDY SILT 1 Li / Qj 26b) site DF 3, Typha zone CO CC £ 100-W •8 z 80 -f £ 6 0 - | 1-1 6 20-1 CC Other t y p e s ; Abies(1%), Picea(5%), Tsuga(2%), Betula(1%) , Salix(.5%), Myricaf.5%), Gramineae(3%), L i l i a c e a e (1%), Compositae(.5%). SILT • l 1 1 / J ? o c- 26c) site CO ^ 1 0 0 - co * 80 J z a —J e g' 4 0 DF 4, Carex-Potentilla zone Other t y p e s ; Pseudotsuga C2%; , cf.Thuja (1.5%) , Betul,a (1%) , Potentilia(2%), U m b e l l i f e r a e ( . 5 % ) , Chenopodiaceae(.5%; , CompositaeY.5%;, average of 2 samples. 6 0 PEATY SILT J 1 I I CC J" / 0/ o f Figure 27: Po l len diagram of major species i n short core DF-5, Ca rex -Po ten t i l l a zone, i n t e r t i d a l d e l t a - f r o n t . Unshaded c u r v e s a r e expanded 10X POLLEN FREQUENCIES z Cn M Z K Z o § 3 a w o D § K ( B CO <D 3 ft rt W •>] D M W W PI Z H M H > I H H cn jo cn H a w H H D tn cn >-3 W Cn O M CO H 1-3 W t n cn to cn o M o H > M cn cn ^ w w c n w c n c n c n c n c n H M M H H H H H H W R M W H W t r i W M • ^ H Z O M K O O C O + * » + + + * + + + + + + + * * * + + + + + + + + + + 3 w H w * Gelasincspcra Desmidiospora + + + V.G. Type-3 (V.G.3) (Van Geel, 1973) » + + * * + + + + + + + Actinopeltis c f . Helicosporium Assulina Tilletia c f . Periconia c f . Dactylaria c f . Curvularia Diporsporites Type-1 (App. 3, Fig.51a) Thick walled oogonia Hystrichospheres Forams Fine black detritus * * Fern annuli Reworked Te r t i a r y pollen S6 96 CHAPTER 5: CORE CBB FROM CENTRAL BURNS BOG Introduction The following three chapters (5, 6, 7) contain the r e s u l t s and d i s - cussions of pa l y n o l o g i c a l and macrofossil analyses of the three cores (CBB, BBDC, DNR) examined i n d e t a i l . The r e s u l t s obtained from core CBB are presented f i r s t because t h i s core was taken at a s i t e near the top of the c e n t r a l cupola of Burns Bog (Fig. 10), an area l i k e l y to contain the most t y p i c a l and complete sequence of r a i s e d bog development. This core i s used as a reference f o r the two subsequent cores that were taken from the edges of the bog, where bog succession has been aff e c t e d by various di s r u p t i v e f a c t o r s . Methods The core was obtained from a shallow, flat-bottomed, Sphagnum tenellum- Rhynchospora alba depression. The top 1.50 m of the p r o f i l e was sampled i n 5 cm i n t e r v a l s from the wall of a p i t excavated i n the peat because the poorly consolidated deposits would not remain i n the sampling tube. The remaining i n t e r v a l (1.50-6.75. m) was cored using a 5 cm diameter by 50 cm long p i s t o n corer. Extruded cores were divided into 10 cm samples, immediately placed into p l a s t i c bags, and stored i n the laboratory a f t e r addition of a few drops of phenol (except to samples f or radiocarbon dating) to prevent fungal and b a c t e r i a l growth. Samples f o r radiocarbon dating were obtained at 5.50-5.30 m and 2.10-2.00 m and l a t e r sent f o r processing to Teledyne Isotopes, Westwood Laboratories, Westwood, New Jersey. 97 In the laboratory, samples were s p l i t i n h a l f lengthwise and a 1 cm x 1 cm channel removed from the center of one of the halves for p o l l e n analysis. This material was processed according to the standard p o l l e n preparation o u t l i n e i n Ch. 4, and mounted i n s i l i c o n e o i l . Part of the remaining unprocessed material was screened f o r macrofossils, Pollen and spores were i d e n t i f i e d and counted along transects to ob- t a i n a t o t a l of 400 i f p o s s i b l e . Monolete fern spores were counted along with other palynomorphs; however, they were excluded from the t o t a l because t h e i r numbers were s u f f i c i e n t l y high to completely suppress the other species. P o l l e n Diagrams In recent times palynologists have been turning to computers to a s s i s t i n c a l c u l a t i n g r e l a t i v e p o l l e n percentages and p l o t t i n g p o l l e n diagrams (Voorrips, 1973; Squires and Holder, 1970). The time required to produce p o l l e n diagrams i s much shorter, and the r e s u l t a n t diagrams much more pre c i s e . In the present study c a l c u l a t i o n s of a l l p o l l e n values have been made by using a PDP11 D i g i t a l Data Corporation Computer and the p o l l e n d i a - grams have been p l o t t e d by a Calcomp p l o t t e r , both within the Biology Data Center at the University of B r i t i s h Columbia, Vancouver. Programs were written for c a l c u l a t i n g p o l l e n percentages and absolute p o l l e n concentra- tions (see Appendix-2), and the r e s u l t s arranged so that a canned p l o t t i n g program (SPLOT Lauriente, unpublished) could be used. Relative p o l l e n diagrams i n c l u d i n g a l l major species were obtained for each core. These were p l o t t e d out d i r e c t l y by the Calcomp p l o t t e r , and are presented here i n e s s e n t i a l l y unaltered form. To improve presentation of data, as well as to 98 examine r e l a t i o n s h i p s among c e r t a i n groups of p o l l e n (e.g. AP, NAP, AP - Pine), the program for c a l c u l a t i n g p o l l e n percentages was designed so that by removing or adding sets of data cards, separate diagrams could be p l o t - ted f o r the groups of p a r t i c u l a r i n t e r e s t , independently of the percentages of others. Manual or c a l c u l a t o r - a s s i s t e d determinations for many d i f f e r e n t combinations of species can be very time consuming and have usually been done to the l e v e l of d i s t i n g u i s h i n g f l u c t u a t i o n s within regional and l o c a l p o l l e n groups. Also, some workers have separated out groups that they thought were of c l i m a t i c s i g n i f i c a n c e , such as those i n d i c a t i n g wet or dry conditions (Sears and C l i s b y , 1955). In the present study, various groups have been p l o t t e d independently from the main p o l l e n diagram. F i r s t , a l l of the arboreal p o l l e n types, excluding pine, are presented i n one diagram. These species do not appear to be major constituents of l o c a l s i t e environments (except i n core DNR). In most cases they seem to be derived from regional or i n some cases extra- l o c a l sources (sensu Janssen, 1973). Pine i s excluded because i t forms part of l o c a l bog vegetation. Removal of l o c a l f l u c t u a t i o n s i n pine gives a c l e a r e r p i c t u r e of changes occurring i n other f o r e s t types. A separate AP diagram including pine i s also included, since i n the lower sections of cores, before pine appears l o c a l l y on the bog, i t can be considered part of the regional p o l l e n component. A l l other p o l l e n and spore types (excluding monolete ferns, see above) are considered to be l o c a l shrub and herb layer constituents ( l o c a l NAP). Generally, these r e f l e c t the l o c a l successional changes that accompany the processes of bog formation. Most of the l o c a l species have probably been s i g n i f i c a n t components of i n s i t u communities recorded i n the cores. As i n the complete p o l l e n diagram, monolete Poly- podiaceae have been excluded from the NAP sums. 99 Results and Discussions Stratigraphy and Radiocarbon Dating The stratigraphy of the bog at t h i s s i t e i s i l l u s t r a t e d i n F i g . 28. B a s i c a l l y , the bottom 1.75 m (6.75-5.00 m) records a gradual change i n sediment type from grey-blue, s i l t y sands to grey s i l t s . Black organic streaks are present, p a r t i c u l a r l y i n the lower parts, with increasing amounts of organic material towards the top. The upper part of t h i s i n t e r - v a l , 5.10-5.30 m was radiocarbon dated at 3960 ± 130 years BP (1-9594). The next .8 m (5.0-4.20 m) i s characterized by grey-brown organic s i l t s which change to brown peaty s i l t s . At 4.20 m the sediments become brown, crumbly peats with woody fragments, gradually changing to s l i g h t l y s i l t y sedge peats at 3.75 m. These continue up to 3.00 m, grading into a 1.00 m long i n t e r v a l of sloppy, woody peats mixed with sedge leaves and rhizomes. At 2.00 m, the f i r s t red, fibrous Sphagnum peats were radiocarbon dated at 2925 ± 85 years BP (1-9593). These Sphagnum peats contain several woody phases; one occurs j u s t before 1.25 m, followed by 2 cm of charcoal. From .20 m to .10 m there i s a layer of dense, dark-brown peat, also containing charcoal lenses. Above t h i s there i s .05 m of coarse, dark peat, .02 m of Rhynchospora remains,capped by .03 m of l i v i n g Sphagnum tenellum. The radiocarbon date on the s t a r t of Sphagnum bog conditions indicates that most of the time (3,000 years) represented i n the core was taken up by the Sphagnum bog phase. The peat accumulation rate during t h i s i n t e r v a l works out to be 6.67 cm/100 years. This value i s much lower than the approximately 82 cm/100 years determined for a c t i v e l y growing hummocks of Sphagnum fuscum and Sphagnum capillaceum from a recently disturbed area i n ICO F i g u r e 2 8 : S t r a t i g r a p h y a n d m a c r o f o s s i 1 s o f c o r e CBB ZONES CBB IVb CBB IVa 2925:85 CBB III CBB II sum \2m- /vvv /vv \ l / V V V i / V V V i / vv\ / V v\ • vv\ • vv\ 14m 3960^ 130-I-^LT CBB I L—_:—! 6m Rhynchospora alba achenes, charcoal r - e d d i s h , w e l l - p r e s e r v e d Sphagnum p e a t phagnum fuscum, cf.Sphagnum capillaceum with e r i c a d c u t i c l e s — charcoal, jRhynchospora alba achenes, Ledum groenlandicum leaves r e d d i s h , w e l l - p r e s e r v e d Sphagnum p e a t Sphagnum papillosum Pinus contorta stump indeterminate Sphagnum(?S. fimbriatum) cyperaceous remains s l o p p y , w o o d y p e a t w i t h some sedge p e a t Mgrica twigs, sedge leaves, crowns, rhizomes small twigs, sedge remains d a r k brown sedge p e a t s i l t b l u e - g r e y s i l t w i t h s and l e n s e s b l u e - g r e y , w e l l s o r t e d , f i n e s i l t y sand w i t h b l a c k o r g a n i c s t r e a k s 101 Burns Bog (Biggs, 1976). The o v e r a l l accumulation rate i s even s l i g h t l y less than the minimum accumulation rate (7 cm/100 years) i n a wet almost barren depression at the same s i t e . Apparently, the low, o v e r a l l accumula- t i o n rate (6.67 cm/100 years), i s a r e s u l t of compaction, intermittent Sphagnum growth, decomposition and burning during the h i s t o r y of the s i t e . The rate compares favourably with that obtained for Jesmond Bog, southwest- ern B r i t i s h Columbia (7 cm/100 years) (Nasmith ejt a l . , 1967), a Minnesota peatland (5 cm/100 years), investigated by Heinselman (1963), and for B r i t i s h peat bogs (2-8 cm/100 years) (Walker, 1970). However, i t i s le s s than that obtained for c e r t a i n bogs i n the northeastern United States (10-20 cm/100 years) (Cameron, 1970). Palynomorph and Macrofossil Zonation for Core CBB. The complete diagram, showing the d i s t r i b u t i o n of 38 p o l l e n and spore groups i n core CBB, i s presented i n F i g . 29. Four major zones are d i s t i n - guishable i n the diagram (CBB I-IV), with zone CBB IV divided into two sub- zones, a and b. ZONE CBB - I, (6.75-4.40 m): This i n t e r v a l i s characterized by constant high percentages of coni- f e r s , p a r t i c u l a r l y Pinus. Although not ind i c a t e d i n the diagram, the majority of the pine p o l l e n belonged to the Pinus contorta type, with only a few belonging to the Pinus monticola type. Picea, Tsuga heterophylla and Pseudotsuga p o l l e n each represent from 5-15% of the spectrum. Many of the c o n i f e r grains have a battered appearance, i n d i c a t i v e of considerable transport. Also present are numerous reworked, T e r t i a r y p o l l e n grains (Fig. 33) recognizable on the basis of t h e i r amber to brown colouration 102 a f t e r safranin s t a i n i n g . S u r p r i s i n g l y t h e i r frequencies reach up to 25% of non-Tertiary p o l l e n and spores. Reworked palynomorphs include: Pinus, cf. Picea, Tsuga, c f . Cedrus, Abies, Carya and Juglans and the form-genus C i c a t r i c o s i s p o r i t e s . O v e r a l l , the arboreal component (AP) (Fig. 31) dominates the assemblage, averaging around 80%. This seems to indicate l i t t l e deposition from l o c a l NAP sources. These features of the AP, v i z . high Pinus, battered grains, reworked T e r t i a r y palynomorphs, low NAP, ind i c a t e that much of the AP assemblage i n t h i s i n t e r v a l has been derived from the p o l l e n load of the waters of the Fraser River as occurs i n i n t e r - t i d a l d e l t a - f r o n t and estuarine environments (see Ch. 4). Zone CBB - I i s also characterized by s i g n i f i c a n t percentages of Cyperaceae, Typha and Rosaceae p o l l e n . Cyperaceae are most abundant (30%) near the bottom, whereas Typha tetrads reach r e l a t i v e l y high values (10%) i n the upper h a l f . The Rosaceae p o l l e n , reaching 60% of the NAP (Fig. 32), appear to belong to P o t e n t i l l a , on the basis of the f i n e l y s t r i a t e ornamen- t a t i o n of the exine. I t seems l i k e l y that t h i s represents P o t e n t i l l a anserina subsp. p a c i f i c a , which i s common i n the upper i n t e r t i d a l marsh of the d e l t a - f r o n t as well as i n other l o c a l i t i e s along the coast. Modern p o l l e n studies (Ch. 4) i n d i c a t e that the percentages of Typha and P o t e n t i l l a i n the diagrams can be expected i n vegetation dominated by e i t h e r species. Increases i n both types i n the core are accompanied by decreases i n Cyper- aceae p o l l e n , p a r t i c u l a r l y i n the upper part of the i n t e r v a l . Other marsh in d i c a t o r s include:. Malvaceae (cf. Sidalcea hendersonii) and Equisetum as well as Cyperaceae. At the boundary between zone I and zone I I , fern spores occur i n very high frequencies, being up to 12 times as abundant as the t o t a l of a l l 103 other p o l l e n and spores. Although surface samples from the delta-^-front reveal some concentration of monolete fern spores (cf, Athyrium), the high numbers, together with many sporangia and sc a l a r i f o r m tracheids, strongly suggest that Athyrium f i l i x - f e m i n a was growing at or near the core s i t e . A convincing analog f o r t h i s s i t u a t i o n has not been observed; however, sparsely dispersed clumps of t h i s fern grow i n Spiraea thickets along the P i t t River, some 30 km northeast of Burns Bog. During at l e a s t part of the fern spore peak i n core CBB, Spiraea i s also present. In addition, Athyrium produces copious q u a n t i t i e s of spores. This i n d i c a t e s that only a small number of plants growing i n an area i s required to achieve high spore f r e - quencies i n the sediments. Other features c h a r a c t e r i s t i c of CBB-I include the c f . Periconia fun- gal c onidia and the chitinous t e s t s of microforaminifera (Fig. 33), The i d e n t i f i a b l e macrofossil record (Fig. 28) i s poor, with mostly rus h - l i k e and sedge l e a f and rhizome fragments incorporated into the sediments. An analog f o r zone CBB~I can be found on the e x i s t i n g i n t e r t i d a l marshes of the Fraser River d e l t a - f r o n t . In the Scirpus zone (Forbes, 1972) , t i d a l a c t i v i t y i s most pronounced between s l i g h t l y elevated tussocks of Scirpus americanus and T r i g l o c h i n maritimum. These trap the f i n e r sediments while sand i s moved back and f o r t h i n the low spots by t i d a l a ction, r e s u l t i n g i n the deposition of lenses of sand i n the s i l t s . The organic content i s low, r e s t r i c t e d to b u r i a l of i n s i t u Scirpus americanus and Scirpus palludosus remains by s i l t s and fine-grained well sorted sands derived from the Fraser River. Typha l a t i f o l i a stands occur near fresh water sources, such as near r i v e r channels (Fig. 25); on the basis of 104 surface p o l l e n spectra even low percentages of Typha po l l e n i n d i c a t e stands of t h i s species nearby. In the p o l l e n spectra of the sediments of the Fraser River analog, Pinus and Picea from r i v e r waters predominate. Local NAP p o l l e n i s charac- t e r i z e d by Cyperaceae. These deposits form the base f o r any plant succes- sion that occurs as the a c t i v e l y growing d e l t a - f r o n t moves away from a s i t e . The upper part of CBB - I equates more c l o s e l y to vegetation shore- ward of the Typha zone (Fig. 25), or shoreward of the Scirpus zone where Typha stands are absent ( i . e . away from r i v e r channel mouths). Carex lyngbeyi i s the most c h a r a c t e r i s t i c species with many other emergent aquat- i c s very abundant (Forbes, 1972). P o t e n t i l l a anserina subsp. p a c i f i c a also grows here, although the pollen' percentage'preserved i s low. ZONE CBB - II (4.40-3.00 m) : At the t r a n s i t i o n from CBB - I to CBB - II Pinus, Picea and Pseudo- tsuga l e v e l s drop sharply, whereas Tsuga remains constant. Cf. Thuj a p o l l e n occurs i n trace amounts. Alnus l e v e l s gradually increase throughout the i n t e r v a l . The sudden conifer drop i s accompanied by a large increase i n Cyperaceae p o l l e n to 60-70%. A peak i n Spiraea p o l l e n occurs i n the bottom h a l f of the zone, while at the same time monolete fern spores (cf. Athyrium) reach the highest values recorded i n the core. The arboreal diagram (Fig. 31) c l e a r l y shows that the tree p o l l e n types f a l l i n t o two categories. Picea, Pseudotsuga and Pinus drop markedly i n the t r a n s i t i o n to CBB - I I . The second group of Tsuga, c f . Thuja, Abies and Alnus e i t h e r r i s e s sharply or stays the same. These four are species c h a r a c t e r i s t i c of e i t h e r the d e l t a lowlands or the nearby surrounding uplands. This suggests that i n t h i s zone, the arboreal p o l l e n being 105 deposited was derived from the regional, atmospheric p o l l e n r a i n , and not from r i v e r sources. This coincides with the change i n deposition from dominantly mineral sediments i n CBB ^ I to dominantly organic sediments i n CBB - I I . The o v e r a l l drop i n the AP (Fig. 31) i s probably a r e s u l t of: a) decreased f l u v i a l input of p o l l e n and sediment; and b) increased p o l l e n deposition from l o c a l NAP p o l l e n contributors, p a r t i c u l a r l y Cyperaceae. The NAP diagram (Fig. 32) c l e a r l y shows domination by Cyperaceae .ac- companied by sedge l e a f and rhizome remains i n the macrofossil record, strongly suggesting sedge swamp conditions. The Spiraea peak at the bottom of the i n t e r v a l implies that thickets of Spiraea were probably close-by. F i n a l l y , near the top of the zone i t appears that grasses may have become established l o c a l l y . The very high monolete fern spore values continue from the zone below, and are s t i l l associated with Spiraea. Even though present i n trace amounts, Lonicera p o l l e n i n t h i s zone and i n the upper part of CBB - I suggest that Lonicera i n v o l u c r a t a was growing i n the sedge marshes (fens) of the area, perhaps along abandoned channels or i n backwater habitats of the r i v e r . Reworked T e r t i a r y p o l l e n types (Fig. 33) disappear at the beginning of zone CBB - I I . At t h i s same horizon, c f . D a c t y l a r i a and cf. Curvularia fungal m i c r o f o s s i l s , c h a r a c t e r i s t i c of r i v e r i n e marshes, appear f o r the f i r s t time. Trace quantities of microforaminiferal t e s t s and cf. Periconia in d i c a t e the l a s t time for i n t e r t i d a l d e l t a - f r o n t influence i n the core. Diagnostic macrofossils (Fig. 28) are scarce, with the sedge leaves suggest- ing that the cyperaceous p o l l e n i s that of Carex. Twiglets i n the same sediment appear to resemble those of Spiraea, although Spiraea p o l l e n occurs 106 i n r e l a t i v e l y low amounts (see Ch, 4), Vegetation of zone CBB -•• II i s not obviously represented i n the present de l t a , probably because the areas i t would occupy have been diked and turned into farmland. However, the P i t t River Delta, which i s presently b u i l d i n g into the southern end of P i t t Lake (G. Ashley, personal communication) serves as a l i k e l y analog. In the wet meadows flanking the P i t t River, sedges (Carex rostrata) and grasses (Calamagrostis canadensis) grow on s i l t y peats (Barnard, 1975). When lake l e v e l s are high, these fens are flooded with up to .30 m of water. The degree of flooding decreases with distance from the lake and the r i v e r , with the formation of clumps of Spiraea douglassi and Myrica gale. At s i t e s s t i l l f a r t h e r from the r i v e r , Spiraea and Myrica combine to form continuous t h i c k e t s , sometimes accompani- ed by Malus fusca and Lonicera invol u c r a t a (Barnard, 1975). In short i t appears that zone CBB - II records wet sedge fens which show signs near the top of the zone of developing shrubby vegetation. ZONE CBB - I I I (3.0-2.0 m) : In t h i s i n t e r v a l the l e v e l s of arboreal p o l l e n change l i t t l e from zone CBB - I I , except f o r increases i n c f . Thuja. This indicates no major f l u c - tuations i n regional or lowland f o r e s t s . At the t r a n s i t i o n from CBB - II to CBB - I I I , Cyperaceae p o l l e n l e v e l s drop suddenly, followed by a gradual increase to reach previous values near the top of the zone. Most prominent i n t h i s i n t e r v a l i s the 90% peak i n Myrica p o l l e n followed by a 10% peak i n Spiraea. The overwhelming dominance of Myrica p o l l e n along with Myrica stems, rhizomes and seeds (Fig. 28), c l e a r l y indicates a Myrica shrubland. Subsequently Spiraea t h i c k e t s recurred with Ledum groenlandicum (Ericaceae 107 tetrads l e s s than 30 ym i n diameter) appearing near the top of the zone. Cyperaceous p o l l e n also becomes dominant again, along with Spiraea and grasses. The f i r s t s i g n i f i c a n t Sphagnum spores, together with decomposed Sphagnum leaves of the Sphagnum fimbriatum type near the top of CBB - I I I indicates Sphagnum c o l o n i z a t i o n i n t h i s area, Cf. Van Geel Type 55 (V.G. 55) fungal spores (Van Geel, 1976a) are r e s t r i c t e d to the upper end of t h i s zone. Gelasinospora spores ind i c a t e humification during the Spiraea peak. In general, then, zone CBB - III was deposited during a Myrica- Spiraea-Ledum shrub phase containing areas of sedges in- the early stages, and occupied by Sphagnum mosses i n the c l o s i n g stages. S i g n i f i c a n t l y , i n the P i t t River wetlands there i s a very s i m i l a r vegetation assemblage i n the t r a n s i t i o n between the sedge-grass wetlands, analagous to CBB - I I , and the vegetation of a small area of r a i s e d bog ( P i t t Lake Bog), developed on the lowlands (Barnard, 1975). Islands of Myrica and Spiraea appear within the sedge-grass marshes, becoming more numerous nearer the bog. S i g n i f i c a n t l y i n terms of a s i t u a t i o n analogous to CBB - I I I , Sphagnum fimbriatum occurs within the Myrica-Spiraea shrubland. Although t h i s i s a mesotrophic species (W. B. Schofield, personal communica- tion) , i t s occurrence implies that Sphagnum species can become established i n such habitats. Sphagnum palustre also occurs, but i s more abundant with Ledum. The Sphagnum leaves that are preserved i n CBB - III with Myrica and Spiraea appear to be of the Sphagnum fimbriatum type, although they cannot be d e f i n i t e l y i d e n t i f i e d . At the t r a n s i t i o n from CBB - III to CBB - IV, Ledum tetrads appear, a s i t u a t i o n quite analogous to the occurrence of Ledum stands between Myrica-Spiraea shrubland and Sphagnum bog at the edge of P i t t Lake Bog. 108 ZONE CBB - IV (2..0-0.-0 m) ; This zone i s characterized by assemblages dominated by pine and Sphagnum, together with s i g n i f i c a n t numbers of Ericaceae. Two subzones are d i s t i n g u i s h a b l e : subzone a) (1.9-.2 m) with more or les s constant frequencies of Tsuga and other c o n i f e r s except pine; and subzone b) (.20-̂ 0.00 m) with sharply reduced c o n i f e r l e v e l s (except p i ne), and sudden alder and grass increases. Subzone IVa shows an increase i n arboreal p o l l e n over that of CBB - I I I . This can be a t t r i b u t e d to the jump i n pine, suggesting that Pinus contorta had colonized the bog around the core s i t e . A pine stump was re- covered at the 2.00 m level„at t h i s s i t e supporting t h i s conclusion. The arboreal diagram (Fig. 31) shows t h i s increase i n pine as being gradual. Most of the other arboreal species except c f . Thuja also seem to increase during i n t e r v a l CBB - IV, but at d i f f e r e n t times. These r e l a t i v e r i s e s appear to be a t t r i b u t a b l e to the decline i n alder and cf. Thuja from higher values at the beginning of the i n t e r v a l (Fig. 30). Sphagnum i s c l e a r l y the dominant NAP palynomorph, i n d i c a t i n g the development of Sphagnum bog conditions (Fig. 32). This conclusion i s further supported by the v i r t u a l disappearance of Cyperaceae and the presence of notable amounts of Ericaceae, tetrads, p a r t i c u l a r l y i n the lower parts of the zone. Ledum-type tetrads dominate i n the lower section. These tetrads are gradually replaced by those l a r g e r than 30 um i n diameter, i n d i c a t i n g the advent of species t o l e r a n t of wetter conditions such as Kalmia microphylla, Andromeda p o l i f o l i a , Vaccinium oxycoccos and Vaccinium uliginosum. A thick charcoal layer at 1.20 m records a major f i r e that burned the preceding heathland. 109 Subzone IVb represents a very short i n t e r v a l where a sudden drop i n con i f e r p o l l e n (except pine) i s accompanied by a pronounced ..increase i n both alder and grasses. This i s almost c e r t a i n l y the r e s u l t of the a r r i v a l of European man, who cleared and logged the surrounding areas. Increases i n pine, c f . Rhynchospora and Pteridium along with a decrease i n Sphagnum seem to be the r e s u l t of burning and p a r t i a l draining of the l o c a l bog area. This was accompanied by the development of a Rhynchospora alba-Sphagnum tenellum hollow at the core s i t e . The sudden r i s e i n grasses may also r e s u l t from r e l a t i v e l y good preservation i n the very wet conditions at the s i t e , i n addition to increased grass growth on cleared land (see Ch. 4). A host of new fungal and rhizopod types (Fig. 33) appears i n zone CBB - IV, the most c h a r a c t e r i s t i c being Desmidiospora, a constant associate of Sphagnum. Many of the others correspond to those reported by Van Geel (1973) from a r a i s e d bog i n West Germany. Cf. V.G. 55 fungal spores are very abundant but of unknown e c o l o g i c a l s i g n i f i c a n c e . Gelasinospora and V.G. 3 fungal m i c r o f o s s i l s are associated with f i r e horizons or humified l a y e r s , r e f l e c t i n g changes i n s o i l conditions (Van.Geel, 1973). Macrofossil recovery varies throughout, with best preservation and greatest d i v e r s i t y associated with charcoal and humified layers. Right a f t e r the advent of Ledum, Sphagnum peat begins to accumulate i n the deposits at the base of zone CBB - IV. Sphagnum macrofossils at t h i s l e v e l have been i d e n t i f i e d as very p a p i l l o s e Sphagnum papillosum which i n B r i t i s h Columbia i s an oceanic type, c h a r a c t e r i s t i c of the bogs of the west coast of Vancouver Island (W. B. Schofield, personal communication). Sphagnum papillosum of the very p a p i l l o s e type i s not currently gorwing i n Burns Bog, suggesting that the habitat was more oceanic than at present. Above the S_. papillosum 110 layer, the peats seemed to have been formed from Sphagnum fuscum and Sphagnum capillaceum. At the edge of P i t t Lake Bog, the t r a n s i t i o n from Myrica-Spiraea thickets i n t o Sphagnum bog i s also marked by the development of Ledum. However the attendant Sphagnum species i n t h i s region i s Sphagnum palustre. With increasing boginess, Sphagnum capillaceum s t a r t s to form hummocks. The large Pinus contorta stump uncovered at the 2.00 m l e v e l i n core- CBB ex h i b i t s the c h a r a c t e r i s t i c low growth rates and o s c i l l a t i n g poorer and better growth expected f o r an area of active Sphagnum develop- ment (see Ch. 2). I t i s i n t e r e s t i n g to note that i n the P i t t Lake Bog, Pinus contorta does not grow outside the Ledum-Sphagnum band around the bog periphery. This implies that c e r t a i n s o i l conditions perhaps r e l a t e d to pH and water content must be established before pine w i l l colonize (Birks, 1975) . The two major f i r e horizons i n CBB - IV are of i n t e r e s t because they support observations made on the e f f e c t of f i r e i n the present bog environ- ment (Ch. 2). In both cases, the f i r e horizons are preceded by peaks i n Ledum-type p o l l e n and are followed by sudden drops i n Sphagnum spores and Ledum, along with the f i r s t appearance of Rhynchospora alba achenes. Abundant Rhynchospora indicates the formation of a shallow depression with low accumulation rates u n t i l recolonized by Sphagnum. Immediately a f t e r the f i r e at 1.22 m, a l l arboreal p o l l e n percentages r i s e suddenly, apparently a response to the elim i n a t i o n of l o c a l NAP. Pinus recovers somewhat l a t e r , to l e v e l s twice as high as before the f i r e , and then gradually decreases as Sphagnum recolonizes the burned surface and r e s t r i c t s n u t r i e n t uptake (see I l l Ch. 2). The f i r e ( s ? ) i n the top .20 m have l e f t the s i t e with the same Rhynchospora dominated cover as ju s t a f t e r the f i r e at 1.22 m. Summary and Conclusions The ce n t r a l part of Burns Bog has formed on i n t e r t i d a l l y deposited s i l t s of the Fraser River Delta. As the d e l t a - f r o n t emerged more than 4,000 years ago, brackish water conditions supported emergent aquatics such as Scirpus and Typha. With decreased influence from the sea and the r i v e r , sedges became established i n p e r i o d i c a l l y flooded fens and organic accumula- t i o n replaced mineral deposition. This phase was followed by the advent of shrubs such as Myrica and Spiraea. Once a suitable substrate developed, about 3,000 years ago, Sphagnum spp. and Ledum groenlandicum took over, leading to the eventual establishment of a r a i s e d bog ecosystem. The f i r e horizons recorded by charcoal i n the core were followed by temporary l o c a l disappearance of Sphagnum and appearance of Rhynchospora alba. The core also indicates that the regional AP, r e f l e c t i n g upland for e s t s , remained unchanged u n t i l the advent of immigrants at the .20 m l e v e l , with subsequent increases i n alder and grasses and decreases i n a l l AP types except pine. ZONES CBB IVb |;"s-;y;:.il SAND |~-Z-Z-j S ILT Unshaded curves are expanded 10X SEDGE PEAT | y y y ) WOODY PEAT SPHAGNUM PEAT • " • » • • CHARCOAL Each d i v i s i o n i s 50% Minor Types Lycopodium 112 Rubus chamaemorus Drosera Rubus chamaemorus Rubus chamaemorus Lonicera, Lycopodium Lonicera Lycopodium Lonicera Lycopodi um Lonicera FIGURE 29 : POLLEN DIAGRAM FOR CORE CBB, BURNS BOG, DELTA, BRITISH COLUMBIA• Monolete Polypodiaceae are excluded from the t o t a l . 113 E----H S I L T w o o d y p e a t ' C H A R C O A L F I G U R E 3 0 ; ARBOREAL POLLEN DIAGRAM EXCLUDING PINE FOR CORE CBB/ BURNS BOG, DELTA, BRITISH COLUMBIA. Unshaded curves are expanded 10X PJQjjj SILT [y y y 1 WOODY PEAT min i CHARCOAL Unshaded curves are expanded 10X FIGURE 31 : ARBOREAL POLLEN DIAGRAM FOR CORE CBB, BURNS BOG, DELTA, BRITISH COLUMBIA. 114 115 Minor Types Lycopodium Drosera Rubus chamaemorus Drosera Plantago Drosera Rubus chamaemorus Rubus chamaemorus Plantago Lonicera Lonicera Loni cera Lonicera, Lycopodium Lonicera, Lycopodium Lonicera Lycopodi um Lonicera Each d i v i s i o n i s 50% 100 200 300 Mono l e t e P o l y p o d i a c e a e a r e e x c l u d e d from t h e t o t a l . |ff:..;.,J SAND £13 S I L T )|| IHU SEDGE PEAT SPHAGNUM PEAT - \y,Y,y,\ WOODY PEAT • • CHARCOAL FIGURE 32 ! NON-ARBOREAL POLLEN DIAGRAM FOR CORE CBB, BURNS BOG, DELTA, BRITISH COLUMBIA. Unshaded curves are expanded 10X DEPTH IN METERS ON U l . o c o t o Gelasinospora Desmidiospora V.G. 3 Actinopeltis cf.Helicosporium c f . M o u g e o t e a V.G. 55 Microthyriaceae Tilletia Amphitrema Assulina c f . P e r i c o n i a c f . D a c t y l a r i a c f . C u r v u l a r i a Forams Tertiary pollen Fine Black detritus Fern annuli us c s n> CO CO - o •< 3 o 3 O - J T3 0J CQ -i 0> 3 o - 5 O o -s CD O ca CO 9TT 117 CHAPTER 6: CORE BBDC FROM WESTERN BURNS BOG Introduction Core BBDC was obtained from the southwest corner of Burns Bog adjacent to the Vancouver Sanitary L a n d f i l l S i t e (Fig. 10). This l o c a l i t y was chosen because of the necessity to c o l l e c t information from the western part of the bog for completeness and before b u r i a l of t h i s area by l a n d f i l l . Dwarf Pinus contorta, Ledum groenlandicum and Sphagnum capillaceum are the major plants growing on the s i t e . Methods The core was obtained i n the same manner as core CBB (see Ch. 5). The samples were prepared using a modified procedure from that employed f o r core CBB and DNR, so that absolute p o l l e n values could be obtained from both the volume and the weight of the sediment. Absolute p o l l e n In p a l y n o l o g i c a l analyses, absolute p o l l e n determinations can be made to obtain values of the actual numbers of po l l e n grains present i n samples of known volume and weight. As such they also record the actual number of grains dispersed by the various species during a s p e c i f i c i n t e r v a l of time. I f radiocarbon dates are obtained at various horizons throughout the core, the sedimentation rates f o r the various i n t e r v a l s can be calculated, and the corresponding annual p o l l e n deposition determined (Davis, 1967). The absolute p o l l e n determination removes the problems inherent i n i n t e r p r e t i n g r e l a t i v e percentages i n po l l e n diagrams. 118 I t i s apparent that for consistent r e s u l t s , sedimentation rates must be accurately determined by multiple radiocarbon dates on every core; constant sedimentation rates are assumed between dates. This condition i s approximated i n open lakes, where sedimentation i s dominated by a constant v e r t i c a l component ( f a l l i n g d e t r i t u s -*• gyttja) and more or l e s s uniform p h y s i c a l and b i o l o g i c a l turbation of sediments. Where such conditions do not e x i s t , assuming constant accumulation rates i s not a v a l i d procedure. This i s p a r t i c u l a r l y true f o r cases that recorded r a p i d l y changing environ- ments such as those investigated i n t h i s study. Nevertheless absolute p o l l e n determinations were made for core BBDC to discover the sorts of palynomorph concentrations ch a r a c t e r i z i n g the environments represented. The samples were prepared using the standard procedure with the follow- ing modifications. F i r s t , the' i n i t i a l volume of the sample was determined by the following method. The sample was suspended i n water and placed i n a 50 cc graduated- c o n i c a l centrifuge tube and centrifuged f o r one minute at 7,100 rpm. The volume of sediment was read from the scale on the side of the tube. This techinque, suggested by Faegri and Iversen (1965, p. 41), was used because ext r a c t i n g f i x e d volumes by the "plug" method of Mathewes (1973) was prevented by the fibrous nature of the peat deposits. A f t e r volume determination, the dry weight (oven drying at 80°C) of each sample was also determined. The exotic p o l l e n method (Benninghof, 1962) was chosen f o r absolute p o l l e n determination because i t does not require the time-consuming weighing of s l i d e s , and counting a l l grains on a s l i d e as i n the "volume" method (Mathewes, 1973). A standard s o l u t i o n of Sciadopitys v e r t i c i l l a t a p o l l e n was employed as a source of the exotic grains. Sciadopitys was used because 119 i t i s reasonably distinguishable from native p o l l e n and spore types and i s a v a i l a b l e l o c a l l y i n large q u a n t i t i e s . To prevent any confusion of Sciadopitys p o l l e n with s u p e r f i c i a l l y s i m i l a r Tsiiga heterophylla p o l l e n , the exotic grains were stained for one minute with a 1% s o l u t i o n of methyl green. The exotic grains were found to maintain t h e i r green colour i n s i l i c o n e o i l i f TBA, n e u t r a l i z e d with a few grains of K2CC>3, was used i n the f i n a l wash before mounting i n s i l i c o n e o i l . Thus, the Sciadopitys grains were rendered e a s i l y d i s t i n g u i s h a b l e by both morphology and colour. The concentration of the exotic p o l l e n s o l u t i o n , 7.62 x 10 6 grains per ml, was determined by using a corpuscle counting chamber (Improved Neubauer, U l t r a Plane, S p o t l i t e Counting Chamber, 1/400 mm2 x .1 mm deep, C. A. Haus- ser and Son). A measured volume of p o l l e n sample was "doped" with 100 ]il of the exotic grain s o l u t i o n , and mounted i n s i l i c o n e o i l . The f o s s i l palynomorphs and the exotic grains were i d e n t i f i e d and counted to a t o t a l of 400 p o l l e n and spores whenever poss i b l e . Then the following formula was applied to determine the absolute concentration of p o l l e n and spores for each sample. Absolute p o l l e n and spore concentration/cc = x K/(R^ x V Q) Absolute p o l l e n and spore concentration/gm = R x K/(R^ x WQ) where; R = Number of f o s s i l grains/Number of exotic grains K • = Concentration of exotic s o l u t i o n x Volume of exotic s o l u t i o n used R V = Volume of doped sub-sample*/Total volume of o r i g i n a l prepared sample V = Volume of o r i g i n a l sediment sample a f t e r c e n t r i f u g i n g (in cc) 120 Wq = Dry weight of o r i g i n a l sediment sample (in grams) *usually only part of the p o l l e n residue prepared from a sediment sample was doped with exotic p o l l e n . Absolute p o l l e n diagrams were prepared using a computer program written for the p a r t i c u l a r purpose (Appendix-2b). Sediment analysis Environments, as well as being characterized by m i c r o f o s s i l and macro- f o s s i l assemblages, are also i d e n t i f i a b l e by sedimentary characters. To get an idea of the nature of the mineral sediments at the bottom of core BBDC, and thus a better idea of the environments i n which they were deposit- ed, the s a n d : s i l t : c l a y r a t i o s were determined f o r selected samples. The sand f r a c t i o n was determined by wet s i e v i n g , whereas the percent- ages of the s i l t and clay f r a c t i o n s were obtained by the pipe t t e method (Folk, 1968). Samples of 40-50 grams were taken at about .50 m i n t e r v a l s from the mineral deposits comprising the l a s t 3.00 m of core BBDC. The sediments were disaggregated and dispersed i n d i s t i l l e d water. Then they were wet-sieved at 210 ym to remove large plant fragments. I f any sand greater than 210 ym was found, the residue was treated with H2C>2 overnight, washed, oven-dried, and weighed. The material that passed through the 210 ym mesh was s i m i l a r l y treated with ^2°2 a n d s i - e v e d again at 63 ym; then the grains greater than 63 ym (sand f r a c t i o n , Folk, 1968, p. 25) . were oven-dried at 110-130°C and weighed. The t o t a l weight of the sand f r a c t i o n consisted of a l l mineral grains greater than 63 ym i n s i z e . The fines which passed through the 63 ym mesh were dispersed i n a weak Calgon s o l u t i o n , checked f o r f l o c c u l a t i o n , and then analyzed by the pipette method for 121 s i l t and clay f r a c t i o n s . The s i l t / c l a y boundary was set at 2 ym (Folk, 1968). Results and Discussion Stratigraphy The s t r a t i g r a p h i c sequence for core BBDC (Fig. 34) begins with f i n e - grained s i l t y sands. Gradually i n the i n t e r v a l 5.50-5.00 m, the sediments change to s i l t s with occasional sand lenses and black organic streaks. S i l t s continue up to about 4.20 m, where they are replaced by peats and peaty s i l t s . At 3.75 m peaty s i l t s and sands appear. These terminate sharply at 3.45 m, where they are o v e r l a i n by s i l t y sedge peats. The sedge peats continue to 2.50 m, where they are succeeded by heath peats. Sphagnum peat gradually takes over from about 1.10 m and continues to the surface, with some woody peat layers i n the top .50 m. A pronounced layer of charcoal in t e r r u p t s the Sphagnum peats at the .62 m l e v e l . Traces of charcoal also appear i n the top .20 m. Sedimentology The s a n d : s i l t : c l a y r a t i o s obtained from sediment analyses are presented i n Table 4', and p l o t t e d i n F i g . 35. At the bottom of the core the sediments are composed of a 50:50 r a t i o of sands to s i l t s . The proportion of sand decreases i n the i n t e r v a l 5.50- 4.50 m, with a concomitant r i s e i n the s i l t component. The peaty deposits above (at 4.50-4.60 m and 4.00-4.10 m) show a s i g n i f i c a n t clay f r a c t i o n . At 3.50-3.60 m the proportion of s i l t increases markedly to 95% whereas the clay p a r t i c l e s disappear. The upward sequence of decreasing sediment s i z e resembles the sediment- .: , .122 H g u r e 3 4 : S t r a t i g r a p h y a r i d m a c r o f o s s i 1 s o f c o r e BBDC Z O N E S | BBDC Vlb BBDC Via BBDC BBDC IV 14125:110 BBDC 111 BBDC II 4670:100 BBDC I 4935-100 iyvi\y dm 4m K5m >charcoal, abundant Rhynchospora seeds and cf.Rhynchospora leaves Sphagnum fuscum, Sphagnum capillaceum r e d d i s h , w e l l - p r e s e r v e d sphagnum p e a t Sphagnum fuscum. Sphagnum capillaceum twigs, badly decomposed c f . Sphagnum fimbriatum cf.S.fimbriatum, ericad> leaves woody, h e a t h p e a t ||2m c f . sedge leaves and e r i c a d c u t i c l e s c f . sedge leaves, e r i c a d c u t i c l e s , Carex achenes and c f . sedge leaves 3m da rk brown sedge p e a t Carex achenes and c f . sedge leaves p e a t y , s a n d y , s i l t Atripiex seeds Carex achenes, c f . sedge leaves d a r k , dense oenanthe-sedge p e a t Scirpus b r i s t l e s s i l t s w i t h t r a c e s o f m i c a Scirpus b r i s t l e s Scirpus stem b l u e - g r e y s i l t s w i t h s a n d l e n s e s b l u e - g r e y , w e l l - s o r t e d , f i n e s i l t y s and s c o n t a i n i n g b l a c k o r g a n i c s t r e a k s 16m 123 TABLE 4: SAND:SILT:CLAY RATIOS, CORE BBDC, BURNS BOG, DELTA, B.C. Sample No. Sample Depth (m) Sediment % Sand % S i l t % Clay 1 3.50-3.60 s i l t 3.0 95.0 2.0 2 4.00-4.10 s i l t y peat 0.0 67.8 32.2 3 4.50-4.60 peaty s i l t 1.0 70.6 28.4 4 5.00-5.10 s i l t 5.2 78.6 16.2 5 5.50-5.60 sandy s i l t 38.2 53.4 8.4 6 6.00-6.10 s i l t y sand 53.0 46.0 4.0 7 6.50-6.60 s i l t y sand 50.0 50.0 0.0 sand - greater than 63 ym s i l t - 2-63 ym clay - l e s s than 2 ym Figure 35: Sand:Silt:Clay ratio triangle for selected samples from core BBDC. SAND CLAY PERCENT 124 ary changes that can be observed i n traversing shoreward from the edge of the vegetated i n t e r t i d a l brackish water marshes of the d e l t a - f r o n t to the dike (Fig. 25). About 1.5 km seaward of the dike, t i d a l and wave a c t i v i t y i s strong enough to so r t out f i n e sands from s i l t s and clays. The sands are l e f t behind, and are deposited i n small t i d a l channels among scattered clumps of Scirpus americanus and T r i g l o c h i n maritimum. The s i l t s and clays, on the other hand, are transported landward. Sand fr a c t i o n s of sediments on the seaward side of i n t e r t i d a l marshes of the Fraser Delta are usually around 50% (Luternauer and Murray, 1973; D. Grieve, personal communication). This sand l e v e l corresponds to the content of the i n t e r v a l s 6.50-6.40 m and 6.00-6.10 m i n core BBDC. The few data a v a i l a b l e f o r s i t e s c l o s e r to shore, and well within the marsh, indi c a t e much lower percentages of sand (around 20%) (D. Grieve, personal communication). This i s i n agreement with the decreased proportion of sand observed between the two samples from 5.50-5.60 m and 5.00-5.10 m. Thus, moving shoreward, wave and t i d a l energy decreases and s i l t s are deposited among Scirpus and Typha stands. Much les s sand gets t h i s close to shore and there are fewer t i d a l channels. S t i l l c l o s e r to shore, f i n e s i l t s and clays are deposited along with abundant organic material. As noted i n the next section, t h i s sedimentologic sequence p a r a l l e l s c l o s e l y the palynologic succession that shows a t r a n s i t i o n s e r i e s from an assemblage of mainly r i v e r - d e r i v e d palynomorphs through a zone of bulrush and c a t t a i l and f i n a l l y to one dominated by sedges and umbellifers. The high proportion of s i l t s at the 3.50-3.60 m l e v e l i ndicates a major change i n the sedimentary environment. In t h i s i n t e r v a l , there was increased transportive energy with a proportionate decrease i n peat 125 Figure 36: Absolute p o l l e n and spore c o n c e n t r a t i o n s f o r core BBDC, Burns Bog, D e l t a , B r i t i s h Columbia. Pollen & spores Pollen & spores Density gm/cc per gram per cc 0 5 0 5 0 5 10 15 x 1 0 X 10 stippled shading X 1 0 4 X 1 0 3 unshaded 126 accumulation. From the radiocarbon dates at 5.45 m (4,935 ± 100 BP, 1-7629) and again at 4.97 m (4,670 ± 100 BP, 1-7628), the mean sedimentation rate f o r t h i s i n t e r v a l i s .17 cm/year. The marked difference i n s a n d : s i l t ; r a t i o from 5.45-4.97 m, however, c l e a r l y shows that t h i s rate was not constant throughout the i n t e r v a l . The next higher i n t e r v a l , 4.97-3.45 m, terminating at 4,125 ± 110 BP, (1-7627), shows a considerably greater sediment accumula- t i o n rate of .29 cm/year. Large v a r i a t i o n s i n rate probably also charac- t e r i z e t h i s period, as both peats and s i l t s are present. The upper 3.45 m of peats i n t h i s core were accumulated at an average rate of .08 cm/year. Absolute Pollen: Results and Discussion The amount of v a r i a t i o n i n sediment type and accumulation rate i s so great that absolute annual p o l l e n and spore sedimentation rates (Davis, 1967) cannot be c a l c u l a t e d r e l i a b l y . Consequently, absolute p o l l e n data are discussed here only i n terms of concentration of p o l l e n and spores per gram and per cubic centimeter, and then r e l a t e d to sediment density (Fig. 36) . Zone BBDC - I/. In t h i s zone, p o l l e n and spore concentrations are extremely low, ranging between 1,000 and 8,000 grains/cc and 1,000 and 10,000 grains/ gm of sediment. These low concentrations could be expected i n such dense, sandy s i l t s deposited i n d e l t a - f r o n t environments (Muller, 1959). They r e s u l t from both the r e l a t i v e l y high sedimentation rate (approx. .17 cm/ year), and the r e l a t i v e l y low p o l l e n p r o d u c t i v i t y of the sparse l o c a l vegetation. Zone BBDC - JEI: The peats overlying the previous s i l t y deposits contain higher p o l l e n and spore concentrations than these s i l t s , ranging from 127 15,000 to 40,000 grains/cc and 30,000 to 440,000 grains/gm of sediment. These extremely high values per gram of sediment occur because of the l i g h t weight of the peats, the high concentrations of monolete fern spores-, and probably because of increased contribution from l o c a l vegetation. These values are comparable to high concentrations obtained i n Orinoco River backswamps (Muller, 1959). Zone BBDC - I I I : The s i l t y deposits from 3.80-3.45 m contain fewer po l l e n and spores (8,000-13,000/cc, 30,000-100,000/gm) than the peats below. These decreased concentrations r e f l e c t the return to mineral sedimentation. Zone BBDC - IV: The sedge peats that occur i n t h i s i n t e r v a l e x h i b i t highly va r i a b l e concentrations of p o l l e n and spores. In the lower part, concentra- tions r i s e to 22,000/cc and 390,000/gm. However, i n the upper part there i s a marked decline i n these l e v e l s to 1,000/cc and 20,000/gm. The reasons for such large changes i n concentration within an apparently uniform peat type are not c l e a r . Perhaps there were decreases i n p o l l e n p r o d u c t i v i t y of sedge species, or perhaps preservation was markedly poorer i n t h i s upper i n t e r v a l . Zone BBDC - V: The absolute p o l l e n concentrations i n the heath peats are much higher than i n the sedge peats below, ranging up to 23,000/cc and 320,000/gram. Peaks and troughs do not seem to be associated with e i t h e r major sediment density changes or differences i n peat types. The increases are d i f f i c u l t to explain, other than as r e s u l t i n g from increases i n l o c a l p r o d u c t i v i t y and changes i n preservation conditions. Zone BBDC - VI_: In t h i s Sphagnum peat i n t e r v a l , concentrations begin at about the same l e v e l s as i n the preceding heath peats, but increase sub- s t a n t i a l l y just a f t e r f i r e horizons, and also i n the denser peats of the top .20 m. Peat accumulation rates are very low j u s t a f t e r the f i r e s , 128 e s p e c i a l l y i n "Rhynchospora lows" (see Ch. 2). Pollen preservation appears to be good and i s probably r e l a t e d to deposition i n standing, a c i d water. This probably explains the marked increase at the 0.60 m horizon and i n the top .20 m. Concentrations reach 35,000/cc and 2,100,000/gm, and are compar- able to those obtained for lake g y t t j a by Mathewes (1973). In summary, p o l l e n concentrations change markedly throughout core BBDC, r e f l e c t i n g the varying sediment types and accumulation rates. Concentra-^ tions were most affe c t e d by changes i n sediment type as r e f l e c t e d by density. The dense, basal, s i l t y sands contain very low l e v e l s of p o l l e n and spores. The numbers increase i n peaty sediments because of the r e l a t i v e l y low dens- i t y of the peat and from increases i n l o c a l p o l l e n p r o d u c t i v i t y . Highest concentrations are reached i n the f i n e , dense, g y t t j a - l i k e sediments of shallow p o s t - f i r e depressions within the Sphagnum peats. Polle n and Macrofossil Zonation The p o l l e n diagrams for core BBDC (Fig. 37; F i g . 38 (AP - pine); F i g . 39 (AP); F i g . 40 (NAP); F i g . 41 (Ericaceae)) have been divided into 6 zones with zone BBDC - VI subdivided into subzones a and b. These diagrams and the fungal spore and other palynomorph diagram- (Fig. 42) are at the end of t h i s chapter. The macrofossil records are shown i n F i g . 34. ZONE BBDC - I (6.10-4.40 m): The AP of t h i s zone (Fig. 39) i s dominated by Pinus, with s i g n i f i c a n t Picea, Tsuga, cf. Thuja and Alnus, and constitutes 50-80% of the t o t a l p o l l e n and spore sum. The S a l i x peak at the end of the zone probably records a l o c a l stand of willow. Cyperaceae p o l l e n makes up most of the NAP (Fig. 40) and i s ascribed to e i t h e r Scirpus americanus or Scirpus 129 palludosus on the basis of Scirpus sp, b r i s t l e s i n the sediments (Fig. 34). Other emergent aquatic types include S a g i t t a r i a , Malvaceae (cf. Sidalcea hendersonii) and Equisetum. Typha tetrads reach r e l a t i v e l y high l e v e l s near the top of t h i s zone. The p o l l e n and spore assemblage of BBDC - I i s s i m i l a r to that of CBB - I and probably indicates a very s i m i l a r i n t e r t i d a l to estuarine d e l t a - f r o n t environment. Other palynomorphs usually occurring i n t h i s environment are also present, including forams, hystrichospheres, reworked T e r t i a r y p o l l e n grains and both c f . Periconia and c f . D a c t y l a r i a fungal conidia, as well as f i n e black d e t r i t u s (Fig. 42). ZONE BBDC - II (4.40-3.80 m): The boundary between BBDC - I and BBDC - I I , as i n core CBB, i s placed where the AP drops and the NAP r i s e s i n response. This change r e f l e c t s the decrease i n importance of r i v e r - d e r i v e d palynomorphs such as Pinus and Picea. S i g n i f i c a n t l y , Tsuga does not decrease, probably i n d i c a t i n g that proportionately more of t h i s p o l l e n was derived from the atmospheric p o l l e n r a i n than e i t h e r Pinus or Picea. The AP diagram (Fig. 39) shows that, at the top of the zone, Alnus increases at the expense of Abies, Picea and Thuja. This may represent the invasion by Alnus of r i v e r banks near the s i t e . Based on the occurrence of high Cyperaceae frequencies and abundant f o s s i l achenes (either Carex lyngbeyi or Carex obnupta), i t appears that sedges dominated the bottom part of BBDC - I I . Umbelliferae replaced sedges i n the upper part of the zone. Studies of p o l l e n grain morphology of selected Umbelliferae i n d i c a t e that t h i s p o l l e n was probably produced by Oenanthe sarmentosa (see Appendix 3, Fig.51b). Penanthe i s commonly a s s o c i - 130 ated with Carex lyngbeyi and P o t e n t i l l a anserina subsp, p a c i f i c a i n a band of vegetation at the edge of the i n t e r t i d a l zone of the de l t a - f r o n t j u s t landward of the Typha l a t j f o l i a stands (see Ch. 4), As i n core CBB, monolete fern spores are numerous. There are also high numbers of c f . Periconia conidia with l e s s e r amounts of c f . D a c t y l a r i a , c f . C u r v u l a r i a and spiny Sigmopollis. The s i l t y sediments, containing reworked T e r t i a r y p o l l e n grains, ind i c a t e that some r i v e r - d e r i v e d p o l l e n was s t i l l reaching the s i t e . This zone probably represents the high-water l i m i t of i n t e r t i d a l d e l t a - front vegetation, and may be environmentally c o r r e l a t i v e with the upper part of CBB - I. However, BBDC - II exhibits a greater degree of peat accumula- t i o n and l e s s s i l t / c l a y sedimentation than the upper part of CBB - I. ZONE BBDC - III (3.80-3.45 m): Pollen of grasses and chenopods supplant those of Oenanthe and Carex i n zone BBDC - I I I . Seeds of A t r i p l e x t r i a n g u l a r i s are present along with chitinous t e s t s of microforaminifera. These features, along with the presence of f i n e black d e t r i t u s and forams (Fig. 41) indic a t e a s a l t marsh environment (see Ch. 4), and thus a marine transgression j u s t before 4,125 ± 110 BP. At t h i s time, fresh water from the Fraser River must have been prevented from reaching the s i t e , perhaps by a s h i f t i n r i v e r channels. In t h i s i n t e r v a l the AP changed only s l i g h t l y from that below, with r e l a t i v e increases i n Pinus, Picea, Abies and a gradual decrease i n Alnus. ZONE BBDC - IV (3.45-2.50 m): At 3.45 m, fresh to brackish water conditions suddenly return to the s i t e ; as at t h i s l e v e l there i s a sharp contact between the sandy s i l t s 131 below and the o v e r l y i n g s i l t y sedge peats. High percentages of Cyperaceae, probably Carex (achenes - F i g . 34) ind i c a t e that a sedge swamp developed during t h i s i n t e r v a l . Many of the m i c r o f o s s i l s c h a r a c t e r i s t i c of the upper part of BBDC - II return b r i e f l y , eventually disappearing midway through BBDC - IV. In the AP, Tsuga replaces Alnus as the most abundant p o l l e n . Tsuga may have colonized the swamp l o c a l l y or Alnus s i t e s on the banks of the r i v e r may have been destroyed by s h i f t i n g channels. ZONE BBDC - V (2.50-1.10 m): The t r a n s i t i o n from BBDC - IV to BBDC - V i s c l e a r l y marked by the appearance of large numbers of e r i c a d tetrads, mostly of the Ledum type, together with some of the Empetrum nigrum type. At the same time Cyper- aceae. p o l l e n v i r t u a l l y disappears. This zone also marks the f i r s t occur- rence of Sphagnum spores. In the macrofossil record, sedge leaves and c u t i c l e s are replaced by e r i c a d c u t i c l e s and twigs. Also there are well preserved Ledum leaves at the base of zone V. Branch leaves of the Sphagnum fimbriatum type occur, although there are no stem leaves to confirm the i d e n t i f i c a t i o n . At approximately the 1.90 m l e v e l , the AP component doubles ..from 30-60%- (Fig. 39). This r i s e i s a t t r i b u t a b l e c h i e f l y to an increase i n Pinus (compare F i g . 38 with F i g . 39), and probably r e f l e c t s the invasion by pine of the s i t e . Alnus increases noticeably at the beginning of the zone, accompanied by a drop i n Tsuga. Again as i n zone BBDC - I, t h i s may r e f l e c t the development of fresh mineral substrates along nearby r i v e r channels. 132 There were also notable changes i n the fungal spore assemblage from zone IV to zone V (Fig. 42), The appearance of Desmidiospora i s p a r t i c u l a r - l y diagnostic, as i t i s known to characterize only Sphagnum/heath environ- ments. The s i g n i f i c a n c e of the appearance of V.G. 55 i s unknown as i t has not been recovered from modern surface samples. I t also appears to be r e s t r i c t e d i n the core to Sphagnum/heath deposits. Gelasinospora and V.G. 3 fungal m i c r o f o s s i l s both ind i c a t e some degree of humification; they do not appear u n t i l a f t e r Pinus became l o c a l l y established. The t r a n s i t i o n from sedge swamp to bog conditions i n core BBDC d i f f e r s from that i n core CBB. In core CBB, there i s a Spiraea-Myrica shrub stage preceding a very short Ledum in t e r v a l , ( s e e F i g . 32; end of CBB - III to beginning of CBB - IV). In BBDC, however, there i s only a s l i g h t i n d i c a - t i o n of Spiraea-Myrica shrubland at the bottom of zone V. The r e s t of BBDC - V seems to represent a Ledum heathland. ZONE BBDC - VI (1.10-0 m): This zone begins with a sharp increase i n Sphagnum spores, accompanied by a drop i n Ericaceae l e v e l s . Macrofossil examination revealed that the v i r t u a l l y pure Sphagnum peat consists of Sphagnum fuscum and Sphagnum capillaceum, i n d i c a t i n g that these two had replaced the Sphagnum fimbriatum type of BBDC - V. Analysis of the er i c a d spectrum (Fig. 41) reveals that wet (Sphagnum) heathland species with tetrads greater than 30 ym had re- placed those of Ledum type. Inasmuch as the wet heathland species (Androm- eda p o l i f o l i a , Vaccinium oxycoccos, and Vaccinium uliginosum) are very low p o l l e n producers (Ch. 3), t h e i r moderate frequencies i n zone VI in d i c a t e that these species were probably dominant i n the vegetation. A 2 cm-thick charcoal horizon interrupts the Sphagnum peat sequence at 133 .62 m. Before t h i s f i r e , Pinus rose to very high l e v e l s and the Ledum type dominated the ericad spectrum. This r e f l e c t s the growth of a shrubby, p y r o p h i l i c assemblage of Ledum groenlandicum and Pinus contorta at the s i t e . Close i n t e r v a l sampling (2 cm) i n the i n t e r v a l a f t e r the f i r e detected the burn-off of Pinus and Ledum as well as a sudden drop i n Sphagnum spores. The sharp drop i n Pinus i s accompanied by a r i s e i n the l e v e l of regional AP p o l l e n types, p a r t i c u l a r l y Alnus. The sudden disappearance of c f . Thuja as well as low o v e r a l l p o l l e n concentrations may be a t t r i b u t e d to the poor preservation within the charcoal layer. A f t e r the f i r e , there i s a f a s t r e c o l o n i z a t i o n of Sphagnum and Ericaceae. Both t h i s f i r e horizon and the poorly defined f i r e horizons at about .20-.10 m are followed immediately by Rhynchospora alba seeds and sedge-like remains, i n d i c a t i n g a p o s t - f i r e development s i m i l a r to that recorded i n core CBB. Desmidiospora fungal spores, c h a r a c t e r i s t i c of Sphagnum heathland conditions, are abundant throughout BBDC - VI. Also, Gelasinospora and V.G. 3 fungal m i c r o f o s s i l s occur i n t y p i c a l a s s o c i a t i o n with the two f i r e horizons. Subzone BBDC - VIb i s delimited from BBDC - V i a by a marked drop i n AP except Alnus and Pinus. As i n core CBB, t h i s represents the c l e a r i n g of forests by s e t t l e r s . In response to c l e a r i n g there i s a sharp increase i n Alnus, with concomitant decreases i n a l l coniferous types except pine. The Betula increase can be a t t r i b u t e d to the development of a b i r c h woodland i n the pe r i p h e r a l bog region, following c l e a r i n g and draining. The NAP shows increases i n Pteridium and Cyperaceae (cf. Rhynchospora), that are probably a d i r e c t r e s u l t of l o c a l f i r e s . The increase i n grass p o l l e n i s from the 134 establishment of a g r i c u l t u r a l f i e l d s i n the v i c i n i t y . Summary Core BBDC records an i n t e r t i d a l d e l t a - f r o n t , or estuarine Scirpus marsh at 4,900 BP. By 4,500 BP, the s i t e had developed into a Carex- Oenanthe freshwater marsh, probably s t i l l near the d e l t a - f r o n t . A s a l t marsh phase occurred just before 4,100 BP, produced by cu t - o f f of fresh water influence and subsequent marine transgression. At 4,100 BP a fresh water sedge fen suddenly replaced the saltmarsh, l a s t i n g u n t i l the 2.5 m l e v e l . The fen was replaced by a Ledum groenlandicum shrubland. During t h i s heath shrubland phase, Pinus contorta a r r i v e d at the s i t e . In the l a t e r stages of the heath phase, Sphagnum appeared and the Sphagnum bog conditions with c h a r a c t e r i s t i c e r i c a d species became established. The top 0.20 m shows the reduced co n i f e r l e v e l s and sharply increased Alnus f r e - quencies c h a r a c t e r i s t i c of vegetational disturbance produced by the a r r i v a l of s e t t l e r s . F i r e horizons preserved i n the Sphagnum peats are character- iz e d by the same "Rhynchospora lows" as i n core CBB. Ov e r a l l , there i s the same sequence of development as i n CBB including i n t e r t i d a l - d e l t a - f r o n t marshes, sedge swamps, shrubland and Sphagnum bog. The main differences are the occurrence of a s a l t marsh phase and the replacement of the Myrica-Spiraea shrubland phase of CBB by a Ledum groenlandicum shrubland phase i n BBDC. 135 / / / / / / / y / • / / . / / / / / / Minor Types Arceu thobium Arceuthobium Lycopodium Rubus chamaemorus Arceuthobium Acer macrophyllum Lycopodium Drosera Acer macrophyllum, Plantago Plantago Drosera Arceuthobium Menyanthes Leguminosae Leguminosae Plantago Leguminosae Leguminosae Leguminosae Arceuthobium, Lycopodium, Menyanthes Menyanthes, Labiatae Acer macrophyllum Labiatae Lycopodium Lycopodi um Lycopodium, Selaginella Monolete Polypodiaceae are excluded from the t o t a l . SPHAGNUM PEAT Unshaded curves are expanded 10X FIGURE 37 : POLLEN DIAGRAM FOR CORE BBDC. BURNS BOG, DELTA, BRITISH COLUMBIA. 136 cf / SAND SI" jggg^ SPHAGNUM PEAT I 1 1 OENANTHE-SEDGE f ' ' '1 I ..I P E A T l/VV\< WOODY PEAT rnTTTI SEDGE PEAT CHARCOAL Unshaded c u r v e s a r e expanded 10X E a c h d i v i s i o n i s 50% FIGURE 3 8 : ARBOREAL POLLEN DIAGRAM EXCLUDING PINE FOR CORE BBDC, BURNS BOG, DELTA, BRITISH COLUMBIA. 137 OENANTHE-SEDGE WOODY PEAT PEAT Each d i v i s i o n i s 50% ----J S I L T tlllHI SEDGE PEAT , , " » " CHARCOAL SPHAGNUM PEAT Unshaded c u r v e s a re expanded 10X FIGURE 39 : ARBOREAL POLLEN DIAGRAM FOR CORE BBDC, BURNS BOG, DELTA, BRITISH COLUMBIA. r -'Ericaceae — / J * J 4 •i / J * OP 132> Minor Types A r c e u thobium Arceuthobium Lycopodium R u b u s c h a m a e m o r u s A r c e u t h o b i u m A c e r m a c r o p / i y l l u m L y c o p o d i u m D r o s e r a A c e r macrophyllum, Plantago Plantago Drosera Arceuthobium Menyanthes Leguminosae Leguminosae Plantago Leguminosae Leguminosae Leguminosae Arceuthobium, Lycopodium, Menyanthes Menyanthes, Labiatae Acer macrophyllum Labiatae E a c h d i v i s i o n i s 50% OENANTHE-SEDGE fry y y| WOODY PEAT PEAT >•••••« CHARCOAL Efti&l SAND |= t-Z-ZW SILT l l l l l l l l SEDGE PEAT ££3=3 SPHAGNUM PEAT Unshaded curves are expanded 10X Lycopodium Lycopodium Lycopodium, Selaginella M o n o l e t e P o l y p o d i a c e a e a r e e x c l u d e d from t h e t o t a l . FIGURE 40 : NON-ARBOREAL POLLEN DIAGRAM FOR CORE BBDC, BURNS BOG, DELTA, BRITISH COLUMBIA. m . l .FN F E R C E N T A S I F O R E A C H T Y P E ! C O U N T E D DEPTH IN METERS -n U3 c -5 ft) ro Gelasinospora Desmidiospora V.G. 3 Actinopeltis V.G. 55 Microthyriaceae Tilletia Sigmopollis c f . S p i x o g y r a c f . P e r i c o n i a c f . D a c t y l a r i a c£.Curvularia Forams Hystichospheres Tertiary pollen Fine black detritus Fern annuli -o s u <<* 3 O 3 O -5 -a rr C L B l l O -5 Cl o ro co co a o < T) ro H i-( (D w •<! to 63 m a M (a 3 n ON bu rr < H 3 M on dant OPT 141 CHAPTER 7: CORE DNR FROM EASTERN BURNS BOG Introduction Core DNR was obtained to elucidate the developmental sequence from an area i n the eastern section of Burns Bog. The eastern flank of the bog i s characterized by patches of Sphagnum heathland vegetation within mixed coniferous woodland. The coring s i t e was located about 400 m west of the foot of Panorama Ridge (Fig. 10). A probe transect from east to west i n t h i s area (Fig. 43), c a r r i e d out to determine peat depths, indicated that t h i s part of the bog has developed i n a shallow basin with the steeply sloping eastern edge abutting on the pebble beach deposits of Panorama Ridge. In contrast, the western flank i s marked by a low subsurface ridge containing blue-grey s i l t s i n the upper part. From the s o i l s map (Lutter- merding and Sprout, 1969), the vegetation d i s t r i b u t i o n (Fig. 4), and add i t i o n a l f i e l d observations, the .mineral ridge appears to form an arc extending from an a l l u v i a l fan deposited by the creek running o f f Panorama Ridge, northward to s a l i n e rego gleysol/rego g l e y s o l s o i l s i n the northeast- ern corner of Burns Bog. The sampling s i t e l i e s i n a t r a n s i t i o n from Sphagnum heathland to d i s - turbed Mixed Coniferous Woodland. The l o c a l trees are Thuja p l i c a t a , and Tsuga heterophylla. Shrubs at the s i t e include Gaultheria shallon, Kalmia microphylla, Ledum groenlandicum and Myrica gale. There i s a Lysichitum hollow (Turesson, 1916) within 2 m of the s i t e and the ground cover consists of a loose carpet of Sphagnum capillaceum. Much of the surrounding area, p a r t i c u l a r l y to the east, i s f a i r l y swampy. F i g u r e 43: V e r t i c a l s e c t i o n o f e a s t e r n Burns B o g ( c o r e DNR) s how ing s h a l l o w b a s i n a t t h e f o o t Of Panorama R i d g e . Profile follows vegetation sampling transect at eastern end of Burns Bog (see Figure 4, in pocket at back). Surface was assumed to be f l a t , although up to 1 meter of r e l i e f is present Distance from r i d g e i n meters 143 Methods A t o t a l of 8.1 m of deposits was penetrated and sampled for analysis. The top .5m was obtained from a wall of a p i t dug at the s i t e , whereas the remainder of the core was sampled with a H i l l e r borer. Samples were prepared by the standard procedure o u t l i n e d i n chapter 5. Pollen recovery from the l a s t .6 m was unsatisfactory, and the r e s u l t s are not included. A sedgy s i l t sample from 6.90-7.00 m was obtained f o r radiocarbon dating at a s i t e 100 m to the east. Results and Discussion Stratigraphy and Radiocarbon Dating The stratigraphy of core DNR i s summarized i n F i g . 44. In general, the basal grey sandy s i l t s appear s i m i l a r i n character to the deposits at the bottom of cores BBDC and CBB. These gradually become more organic i n composition, u n t i l about the 5.20 m l e v e l where the f i r s t crumbly sedge peats occur. Organic s i l t s obtained from a depth of 7.00-6.80 m, 100 m to the east of the core s i t e , were dated at 5,085 ± 100 radiocarbon years BP (1-9595). There i s a long sequence of crumbly, amorphous brown peats (5.20-.40 m) , containing sedge remains, wood fragments and Menyanthes seeds. In places, these peats appear to be d e t r i t a l ; p ossibly they formed i n a shallow swamp through which a low stream p e r i o d i c a l l y flowed. The upper .40 m consists of woody Sphagnum peats containing l i v e Lysichitum roots. P o l l e n and Macrofossil Zonation The p o l l e n and m i c r o f o s s i l diagrams for core DNR (Fig. 45, complete diagram; F i g . 46, AP; F i g . 47, NAP; F i g . 48, fungal and other m i c r o f o s s i l s ) ! 144 F i g u r e 4 4 : S t r a t i g r a p h y a M d m a c r o f o s s i l s o f c o r e DNR Z O N E S ; 5s* DNR III DNR II earn DNR I vv ' V V V >. V vv ' v vv t v vv 5085:100 3m 6m 7m Sphagnum p e a t , m o s t l y S. capillaceum c h a r c o a l Menyanthes trifoliata with Myrica twigs Menyanthes trifoliata seeds sedge crowns charcoal, Myrica twigs, sedges sedge crowns, indeterminate Sphagnum c r u m b l y , amorphous p e a t s c o n t a i n i n g l a y e r s Of Myrica t w i g s Sedge crowns and twigs c f . Carex sitchensis achene wood, Myrica stems Sphagnum squarrosum Tsuga heterophylla needle Oenanthe sarmentosa f r u i t , woody d e t r i t u s c f . sedge leaves c r u m b l y , sedge t y p e p e a t s Carex achene, Menyanthes seed Menyanthes seed s i l t b l u e - g r e y , sandy s i l t s w i t h b l a c k o r g a n i c s t r e a k s 145 are included at the end of the chapter, pages ZONE DNR-I (7.5-5.4 m): The p o l l e n assemblages of the lower part of zone DNR-I are dominated by arboreal p o l l e n (Fig. 45). Pinus p o l l e n predominates, with r e l a t i v e l y high frequencies of Tsuga and Pseudotsuga. S i g n i f i c a n t l e v e l s of Picea are present but are proportionately lower than i n s i m i l a r deposits from zones CBB-I and BBDC-I. There are unusually low values for Alnus, i n d i c a t - ing that nearby Panorama Ridge was probably covered by the r e g i o n a l l y climax Pseudotsuga f o r e s t . Low Alnus l e v e l s also suggest that there was very l i t t l e of the Fraser Delta emergent i n the v i c i n i t y , as Alnus grows commonly on wet d e l t a i c s i t e s . Near the top of zone DNR-I, the proportion of AP drops, probably as a r e s u l t of establishment of l o c a l stands of emergent aquatic vegetation (cf. CBB-I, BBDC-I) and decreasing deposition of s i l t s that normally contain a high AP load. The NAP i s dominated by Cyperaceae p o l l e n as i n the other two cores. In the upper part of the zone, at l e a s t , the high cyperaceous frequencies represent l o c a l stands of Carex, judging from the occurrence of Carex achenes. The presence of p o l l e n , spores and macrofossils of other emergent aquatics such as Typha l a t i f o l i a , Malvaceae, Equisetum sp. and Menyanthes t r i f o l i a t a , along with Carex, indicates an emergent land surface. The non-vascular plant m i c r o f o s s i l assemblage (Fig. 48), characterized by abundant c f . Periconia conidia, traces of c f . D a c t y l a r i a conidia, and forams, resembles that of zones CBB - I and BBDC - I . S i m i l a r l y , there are large numbers of reworked T e r t i a r y p o l l e n grains, together with a high concentration of f i n e black d e t r i t u s . 146 In summary, the h i s t o r y of DNR <- I appears to be e s s e n t i a l l y the same as the equivalent i n t e r v a l s of both CBB 1 and BBDC - 1, representing an emergent i n t e r t i d a l d e l t a - f r o n t , brackish to fresh water environment. ZONE DNE-II (5.40-0.4 0 m): In keeping with zonation i n cores CBB and BBDC, the boundary between DNR - I and DNR - II has been placed at the Pinus-Picea decline which occurs at the s i l t to peat t r a n s i t i o n . Throughout t h i s long i n t e r v a l (DNR--- II) , Tsuga and Pseudotsuga remain the main AP types (Fig. 46) . Because these trees maintain more or l e s s constant frequencies, i t seems that the f o r e s t on Panorama Ridge remained e s s e n t i a l l y unchanged. Alnus i n i t i a l l y r i s e s to high l e v e l s at 4.00 m and probably i n d i c a t e s coloniza- t i o n of newly-emergent d e l t a i c environments near the s i t e . As the s o i l s matured and swamps developed, Picea seems to have taken over. Alnus rubra does not seem to grow presently on deep organic deposits below Panorama Ridge (see Ch. 2), whereas Picea s i t c h e n s i s t h r i v e s on these s i t e s . Hence, the increase of Picea may also i n d i c a t e that s u f f i c i e n t organic material had accumulated i n the l o c a l swamp (2m) at s i t e DNR to exclude alder. Thuja, which also grows well i n the present swampy s i t e s , reaches i t s best representation i n the lower part of zone DNR - I I , but curiously fades out near the top. This may be a preservational phenomenon. At the 2.00 m l e v e l there i s a marked increase i n Pinus p o l l e n to 50% AP, l i k e l y a t t r i b u t - able to two f a c t o r s : Pinus contorta could have colonized l o c a l d r i e r organic substrates, as i t does now; or pine may have invaded the mature surface of the adjacent r a i s e d bog at that time, with p o l l e n d i s p e r s a l by wind e a s t e r l y i n t o the swampy areas. 147 The NAP diagram (Fig. 47) indicates that there may have been two l o c a l vegetational phases. The f i r s t i s characterized by grasses and sedges (5.40-4.00 m). The second phase (4.00-^0.40 m) contains shrubs such as Myrica and Spiraea, together with Lysichitum americanum and Menyanthes t r i f o l i a t a . These l a t t e r two species appear to alternate, suggesting there may have been shallow ponds a l t e r n a t i n g with wet Myrica-Spiraea t h i c k e t s . The NAP diagram for zone DNR - II indicates that grasses (up to 60% NAP) probably grew l o c a l l y , along with c f . Athyrium f i l i x - f e m i n a , whose spores (monolete Polypodiaceae) and sporangia occur i n great numbers. Attempts were made to d i f f e r e n t i a t e monocot l e a f macrofossils i n the se d i - ments to confirm that grasses d i d indeed grow at the s i t e . Although some of the epidermal patterns were g r a s s - l i k e , i t was impossible to d i f f e r e n t i - ate them d e f i n i t i v e l y from Carex epidermal patterns. The peat corresponding to the grass peak i s of a crumbly nature, very much l i k e that forming i n wet grasslands today. Also, many of the grass grains are folded and crumpled, a feature c h a r a c t e r i s t i c of wet grassland deposits. F i n a l l y , the apparently stable upland vegetation of Panorama Ridge (based on constant Pseudotsuga levels^ and high, presumably lowland-derived Alnus p o l l e n levels) suggest that there probably was not any source of grass p o l l e n external to the s i t e . Cyperaceae, probably Carex sp. and some Typha l a t i - f o l i a occurred with the grasses. Also, an Penanthe sarmentosa seed was found at 5.10 m. This wetland umbellifer grows today near s i t e DNR, favour- ing habitats that are p e r i o d i c a l l y submerged (e.g. swamp hollows). Penan- the p o l l e n occurs sparsely throughout zone DNR - I I . Between 4.50 and 4.00 m, the NAP gradually changes with an i n f l u x of Lysichitum americanum p o l l e n and p o l l e n from Myrica gale and Spiraea 148 d o u g l a s i i . This change i s also shown by the presence of twigs, some of which belong to Myrica. The occurrence of a f r u i t of Carex s i t c h e n s i s indicates that t h i s swamp sedge was also part of the vegetation. Although there i s l i t t l e p o l l e n of Menyanthes preserved i n DNR - II (cf. Ch. 4), high numbers of Menyanthes seeds i n the peat suggest that the upper 2.20 m was deposited i n a shallow Menyanthes-fi1led depression. A period of Myrica shrubland interrupted the Menyanthes stage at 2.40 m, pointing to a b r i e f i n t e r v a l of emergence. There i s also a prominent layer of charcoal at t h i s same horizon, i n d i c a t i n g a sub s t a n t i a l f i r e during the b r i e f Myrica phase. Large numbers of fern annuli occur throughout DNR - I I , confirming i n s i t u growth of a fern, probably Athyrium f i l i x - f e m i n a , a common swamp species of the region. A few fungal spores and a l g a l m i c r o f o s s i l s were also recovered from DNR - I I . These include c f . Curvularia fungal spores, Spirogyra sp. zygo- spores (sensu Van Geel, 1976b) and spiny Sigmopollis types. A l g a l zygo- spore production suggests again that p e r i o d i c submersion i n shallow water was a feature of t h i s s i t e (Van Geel, 1976b) . In short, the extended zone DNR - II represents a fresh water swamp phase, with a l t e r n a t i n g periods of emergence and submergence. DNR -III (0.40-0 m) : Sphagnum peats and Sphagnum spores indicate the very recent advent of bog conditions near the boundary of zones DNR - II and DNR-III. At the beginning of the zone, the AP i s unchanged from DNR - I I . Soon a f t e r , Alnus r i s e s sharply, whereas the co n i f e r p o l l e n frequencies drop. There are also increases i n Pteridium and Spiraea frequencies during t h i s time. 149 These events s i g n a l the a r r i v a l of European man, together with logging of parts of the l o c a l swamp fo r e s t . The occurrence of Epilobium p o l l e n con- firms l o c a l c l e a r i n g and r e f l e c t s the f i r e i ndicated by the charcoal horizon at 0.30 m. The high Lysichitum l e v e l s are produced by nearby plants. The fungal spores and rhizopods occurring i n DNR III are those c h a r a c t e r i s t i c of Sphagnum bog habitats.. I t i s d i f f i c u l t to determine whether Sphagnum bog conditions arose as a r e s u l t of disturbance of the area, or as a consequence of natural succes- s i o n a l events. The vegetation map (Fig. 4) shows that bog conditions may have spread from the north, perhaps derived from the cent r a l cupola of Burns Bog to the west. I f t h i s were the case, then the spread of Sphagnum had probably begun long before the a r r i v a l of European man, and only recently has reached t h i s part of Burns Bog. Both to the east and to the west of s i t e DNR, i n mixed coniferous f o r e s t , there appears to be no evidence f o r Sphagnum peats near the surface. At present, s i t e DNR occurs i n the t r a n s i t i o n between swamp and bog,vegetation. This suggests that unless there are a d d i t i o n a l further disturbances, the boggy portion of the eastern bog w i l l continue expanding. Summary Core DNR records the vegetation of a shallow basin at the foot of Panorama Ridge, separated from the r e s t of Burns Bog by a subsurface mineral ridge. Succession began around 5,000 BP with emergent aquatic vegetation dominated by Cyperaceae. As s i l t deposition tapered o f f at the 5.40 m l e v e l , a sedge-grass marsh became established. This was followed by a 150 swampy Myrica-Spiraea shrubland containing Lysichitum. At the same time Alnus appeared to colonize lowland mineral s i t e s , being subsequently replaced by Picea. Near the upper end of the swamp/marsh i n t e r v a l , Menyanthes t r i f o l i a t a grew abundantly at the s i t e . Very recently (.40 m) the current Sphagnum bog conditions became established. Charcoal horizons and Epilobium p o l l e n accompanied by decreased c o n i f e r frequencies and increased Alnus r e f l e c t l o c a l f i r e s and logging a c t i v i t y . ZONES 4* y • Ericaceae- If 7 / / J / / 151 cr v» » ^ ^ o" / SILT l l l l l l l l SEDGE PEAT p—-7—1 CRUMBLY, I ' A AMORPHOUS PEAT fcvtfj WOODY PEAT E a c h d i v i s i o n i s 50% Minor Types Acer macrophyllum, Epilobium Acer macrophyllum Acer circinatum Cruciferae Epilobium Cruciferae Epilobium Nuphar lutea Cruciferae Lonicera Lonicera Cruciferae Lonicera Sagittaria Lonicera Lonicera Acer macrophyllum Selaginella Nuphar lutea SPHAGNUM PEAT CHARCOAL M o n o l e t e P o l y p o d i a c e a e a r e e x c l u d e d f r o m t h e t o t a l . Unshaded curves are expanded 10X • SAND FIGURE 45 : POLLEN DIAGRAM FOR CORE DNR, BURNS BOG/ DELTA, BRITISH COLUMBIA, 152 Each d i v i s i o n i s 50% h_-_--i SILT y CRUMBLY, AMORPHOUS PEAT l l l l l l l l SEDGE PEAT .. Evvd WOODY PEAT Unshaded curves are expanded 10X E=^=3 SPHAGNUM PEAT mum CHARCOAL SAND FIGURE 46 : ARBOREAL POLLEN DIAGRAM FOR CORE DNR/ BURNS BOG/ DELTA, BRITISH COLUMBIA. ZONES DNR III DNR II DNR I ii' iff / JtVSMwVm'ir, 5085=100 ---"J S I L T CRUMBLY, 1 5 3 Minor Types A c e r macrophyllum, Epilobium Acer macrophyllum Acer circinatum C r u c i f e r a e Epilobium C r u c i f e r a e Epilobium Nuphar lutea C r u c i f e r a e Loni cera Lonicera C r u c i f e r a e Loni cera Sagittaria ' Lonicera Lonicera Acer macrophyllum Selaginella Nuphar lutea AMORPHOUS PEAT SEDGE PEAT . WOODY PEAT Unshaded c u r v e s a r e expanded 10X SPHAGNUM PEAT • » " • " CHARCOAL * • • ' • • • SAND E a c h d i v i s i o n i s 50% M o n o l e t e P o l y p o d i a c e a e a r e e x c l u d e d f r o m t h e t o t a l . FIGURE 47: NON-ARBOREAL POLLEN DIAGRAM FOR CORE DNR, BURNS BOG, DELTA, BRITISH COLUMBIA. DEPTH IN METERS Gelasinospora V.G. 3 Actinopeltis Microthyriaceae Assulina Sig^opollis Spirogyra cf.Periconia ct.Dactglaria cf.Curvularia Forams Tertiary pollen Fine black detritus Fern annuli d -S co o 3 o -s T3 Oi CO -s Oi o o -s ; 0 N: O z C/2 H (a c 3 a. f» 3 rt XI i-i fD CO fD 3 r r vST 155 CHAPTER 8; SYNTHESIS, DISCUSSION AND SUMMARY INTRODUCTION This chapter synthesizes the information obtained from the three cores (CBB, BBDC, DNR) i n t o a general o u t l i n e of the o r i g i n of Burns Bog s t a r t i n g with the f r e s h l y exposed d e l t a i c surface and i t s development through sedge swamp and shrub phases to the current r a i s e d Sphagnum bog. This develop- mental sequence i s compared to what i s known about other r a i s e d bogs i n the area and a model i s proposed for raised bog development on the Fraser Low- land. The Burns Bog sequence i s compared with the o r i g i n and growth of rai s e d bogs i n B r i t i s h Columbia, and d e l t a i c r a i s e d bogs elsewhere. The paleoecology of Burns Bog i s discussed i n terms of the evolution of the southern Fraser Delta, p a r t i c u l a r l y i n terms of sea l e v e l and r i v e r channel changes. The p o t e n t i a l applications of the r e s u l t s of t h i s study are d i s - cussed and the major contributions of the thesis are summarized. SYNTHESIS The O r i g i n and Growth of Burns Bog A general sequence of events i n the development of Burns Bog can be synthesized by comparing r e s u l t s and c o r r e l a t i n g zones of the three cores, along with observations on bog stratigraphy from other exposed sections (Fig. 49). Delta-Front Phase: At about 5,000 years BP, well a f t e r the current region- a l f o rests had become established (Mathewes, 1973), pioneering vegetation F i g u r e 49 : C o r r e l a t i o n o f t he t h r e e c o r e s f r om Burns Bog. elevations are accurate to * .5 meter Position of Phases on delta-front Core (elevation 3.6m) BBDC Core (elevation 4.6m) CBB. Core(elevation III Bog Phase 5.3m) Sedge Swamp Oenanthe / peat A,125+1101 • ISISIBIgESIIIIIIIIIIIIIIIIIIIigiB&a Typha All t Scirpus(silty sand) V Heathland Phase IV Sedge Swamp Phase \it\ imiTi^oi i^ftUi J W i V h 1111111 II -4,670 +100 -4,935 ± 100 Delta Front Phase 2,925+85 III Shrub Phase II Sedge "---.^ Swamp Phase - B B S B S ( B B B B B B B E B B B B B B B B B B B B B B B B B B E B B B B B E | "3,960±130 Delta Front Phase II Swamp Phase EBEEEBBEBflRBBBS I I- 5,085-100 8 157 probably c o n s i s t i n g of Scirpus spp, and other emergent aquatics began to colonize the brackish, s i l t y sands of the i n t e r t i d a l zone of the prograding d e l t a - f r o n t . The change from the sand-dominated submerged environment to the silt/peat-dominated sub-aerial environment seems to have been nearly isochronous at the three s i t e s as shown by radiocarbon dates i n core BBDC and DNR, and an extrapolated date f o r core CBB, based on a sedimentation rate of .17 cm per year. Subsequently, as organic sedimentation replaced s i l t deposition, there was a d i s t i n c t change to sedge-dominated swamps. In core CBB, the t r a n s i - t i o n occurred immediately a f t e r 3,960 ± 130 BP. In core BBDC, following the development of an Oenanthe sarmentosa wetland, a marine transgression temporarily interrupted the succession to sedge swamps by interposing a s a l t marsh phase at 4,125 ± 110 years BP. The sedge swamp phase i n core DNR has not been designated as a zone; rather i t i s considered as a short i n t e r v a l of sedge-grass dominance following the emergent d e l t a - f r o n t period. In a l l three cores, the switch to predominantly organic accumulation happened at a depth very close to present sea l e v e l (geodetic datum). At t h i s point i n development, there was periodic, weak flooding, i n d i c a t e d by traces of s i l t . The area, during the sedge-swamp period, was probably a low f l a t wetland, covered with many shallow pools r e s u l t i n g from f l a t top- ography and poor drainage. Numerous observations of peat diggings, drain- age ditches, and H i l l e r borings by Rigg and Richardson (19 38), indicate that the sedge-swamp deposits underlie much of the bog. Shrub and Heathland Phase: The sedge-swamp phase i s followed by the devel- opment of shrubby vegetation i n cores CBB (Myrica-Spiraea) and BBDC (Ledum). This shrub phase, characterized by the accumulation of woody peat, seems to have been widespread throughout the bog (Rigg and Richardson, 1938). In 158 core DNR, a swampy Myrica-Spiraea shrubland appears to have developed; swamp conditions are indicated by the high p o l l e n l e v e l s of Lysichitum americanum. Sphagnum Bog Phase: The shrubby phase marks the f i r s t appearance of Sphag- num leaves (Sphagnum fimbriatum type) with a few Sphagnum spores. In both cores CBB and BBDC, the appearance of t h i s moss i s followed by a Sphagnum bog phase, apparently much l i k e the present vegetation of Burns Bog. This t r a n s i t i o n occurs at about the same horizon above sea l e v e l i n both cores. I t i s traceable i n drainage ditches and peat cuttings, and follows a more or l e s s h o r i z o n t a l plane across the bog. Comparison of surface elevations with determinations of Sphagnum peat depth (Anrep, 1928) further supports t h i s conclusion. A radiocarbon date on t h i s t r a n s i t i o n from shrubs to Sphagnum i n core CBB indicates that r a i s e d bog conditions developed at t h i s s i t e at about 2,925 ± 85 BP. Sphagnum bog conditions at core s i t e DNR d i d not a r i s e u n t i l very recently, following an extended shrubby to open swamp period, probably maintained by run-off from Panorama Ridge. The Sphagnum mosses presumably spread from the extensive areas of Sphagnum i n Burns Bog to the west. The advent of Sphagnum bog conditions i n Burns Bog i s accompanied by a change i n the er i c a d spectrum from an association of Ledum with some Empetrum, to one c o n s i s t i n g most l i k e l y of Andromeda p o l i f o l i a , Kalmia microphylla, Vaccinium oxycoccos and Vaccinium uliginosum. Pinus contorta appears to have a r r i v e d before the f u l l establishment of the Sphagnum heathland vegetation. F i r e Horizons: The Sphagnum peats contain a number of d i s t i n c t charcoal horizons. These are p a r t i c u l a r l y abundant i n the upper few centimeters. 159 There i s a c l e a r l y recognizable effect, from these f i r e s expressed i n both the p o l l e n and macrofossil record. Pines appear to be af f e c t e d i n two ways; where pine seemed to grow well (e.g. .62 m l e v e l core BBDC) f i r e r e s u l t e d i n a sharp decrease of t h i s species with only a s l i g h t recovery l a t e r . Where i t grew r e l a t i v e l y poorly (1.25 m l e v e l , core CBB), burning produced a sharp increase, with eventual return to p r e - f i r e l e v e l s . This increase probably occurred because Sphagnum was destroyed by the f i r e , per- mitting vigorous growth of pine seedlings i n contrast to the p r e - f i r e s i t u a t i o n . To v e r i f y t h i s i n t e r p r e t a t i o n more f i r e horizons need to be examined i n d e t a i l . The major f i r e s i n the Sphagnum phase appear to have t o t a l l y destroyed the ground-cover vegetation. A l l the major f i r e horizons i n cores BBDC and CBB are followed by the sudden disappearance of Sphagnum and pronounced reductions i n Ericaceae.. Ericaceae recovered quickly, whereas Sphagnum (spores) showed a slower rate of re c o l o n i z i n g . Fungal m i c r o f o s s i l s c h a r a c t e r i s t i c of humification became quite abundant i n the f i r e horizons, i n d i c a t i n g temporarily stagnant conditions p r i o r to re- establishment of Sphagnum. During the p o s t - f i r e period, peat accumulated slowly, c o n s i s t i n g mainly of heath l i t t e r , fungal hyphae and Rhynchospora alba remains. These burned areas became wet depressions, while surrounding unburned hollows took over as s i t e s of active Sphagnum growth. Eventually, these unburned depressions became extensive hummock-mat complexes that contributed to the growth of the r a i s e d bog. With time, Sphagnum re- occupied the burned depressions, and converted them to active accumulation s i t e s . This process was accelerated i f new f i r e s razed the area while these depressions were s t i l l wet. A model of the f i r e induced hummock-hollow syndrome i s shown i n Ch. 2 (Fig. 7). 160 An i n t e r e s t i n g p a r a l l e l to the fire*-induced formation of depressions ("Rhynchospora lows") i n Burns Bog occurs i n the Okefenokee Swamp of Georgia. Studies of peat petrography and paleoecology by Cohen (1974) indic a t e that major f i r e s often converted cypress (Taxodium)-dominated swamps to water lily-dominated marshes and that t h i s e f f e c t has been instrumental i n modifying swamp vegetation. This sort of f i r e phenomenon, a f f e c t i n g peat deposits and peatland vegetation, may be more widespread, but as f a r as i s known by the author, i t has not been previously recognized i n Sphagnum bogs. Burns Bog Development i n Relation to Other Raised Bogs i n the Fraser River Delta There i s one core from the Fraser Lowland to which the developmental sequence of Burns Bog can be compared. Hansen (1940) obtained a 5 m core from Lulu Island Bog north of Burns Bog with the purpose of determining the regional f o r e s t h i s t o r y . Although h i s sample i n t e r v a l was .5 m, the sequence obtained seems to p a r a l l e l that of Burns Bog. In the Lulu Island core, Pinus and Picea are the dominant p o l l e n types i n the lower, sandy/ s i l t y deposits. In peat at 2.5 m, Typha tetrads predominate and Cyperaceae p o l l e n appears i n s i g n i f i c a n t q u a n t i t i e s , increasing to very high frequencies at 2.0 m. Some chenopod and grass grains also indicate a trace of s a l t marsh vegetation.- The sedge period i s succeeded by fibrous peat, containing abundant Ericaceae, very s i m i l a r to corresponding l e v e l s i n cores CBB and BBDC. Unfortunately no note was made by Hansen of Sphagnum spores, although Sphagnum was reported i n the surface vegetation. 161 A General Model for Raised Bog Development i n the Fraser Delta (Fig. 50) A model can be constructed for r a i s e d bog development i n the Fraser River Delta based on r e s u l t s from Burns Bog, Lulu Island Bog, and on observations on P i t t Lake Bog vegetation (Barnard, 1975). Colonization Phase: The f i r s t stage, " c o l o n i z a t i o n " , i s equivalent to that preserved i n the basal sediments of the three cores i n t h i s study, and occurs when prograding d e l t a i c surfaces are colonized by aquatics, e.g. Scirpus and Carex. I t i s characterized by sandy s i l t s grading to peaty s i l t s . Sedge-Grass Phase: For further accumulation above the l o c a l water table, the conditions necessary f o r a peat-forming template must be met (Moore and Bellamy, 1973). Enough water must be retained at the s i t e so that organic decomposition i s retarded. In the Fraser Delta, p e r i o d i c flooding and l o c a l p r e c i p i t a t i o n combined with poor lowland drainage provide s u i t a b l e moisture regimes so that peat accumulation can occur. Traces of s i l t are added by p e r i o d i c flooding. Under these conditions - sedges t h r i v e , along with wetland grasses, producing the organic material responsible for peat formation. The sedge stage i s preserved i n sediments throughout Burns Bog, as well as i n Lulu Island Bog (Hansen, 1940). A modern analog of t h i s stage occurs i n the wetlands south of P i t t Lake (Barnard, 1975). Shrub Phase: Shrub development follows the accumulation of sedge peats, with Myrica, Spiraea and l a t e r Ledum, replacing sedges and grasses.. The change from sedge-grass wetlands to shrubs may r e s u l t from; a) organic a c i d accumulation, b) decreased nutrient a v a i l a b i l i t y from the mineral 162 Figure 50: Proposed model f o r r a i s e d bog development i n the Fr a s e r Delta,B.C. POLLEN AND SPORES STAGES AND PROCESSES SEDIMENTS PINE SPHAGNUM ERICACEAE ERICACEAE CYPERACEAE GRAMINEAE POLY PODIACEAE OENANTHE TYPHA CYPERACEAE PINE SPRUCE REWORKED TERTIARY POLLEN SPHAGNUM BOG SPHAGNUM GROWTH 7 LEDUM HEATHLANDS MYRICA - SPIRAEA THICKETS SHRUB GROWTH SEDGE - GRASS WETLANDS t z SEDGE GROWTH DELTA - FRONT ESTUARY TYPHA - CAREX OENANTHE t SCIRPUS t 7 Z COLONIZATION UNDER WATER 7 SPHAGNUM PEAT HEATH PEAT WOODY PEAT SEDGE PEAT PEATY S I L T S I L T SANDY S I L T SAND 1 163 horizon buried under the sedge peats, c) increased elevation and drying as a r e s u l t of sedge peat accumulation. Myrica i s known to be a p r o f i c i e n t nitrogen f i x e r under anaerobic a c i d i c conditions (Moore and Bellamy, 1973; p. 127). Spiraea must also be adapted to these conditions, as i t i s the dominant shrub of poorly drained wetlands of southwestern B r i t i s h Columbia and often grows at the edges of bogs (Osvald, 1933; Rigg and Richardson, 1938). With further increases i n elevation from peat accumulation, and decreases i n the water-holding capacity of the coarse, woody peat, desicca- t i o n of the surface i s increased. This leads to accelerated decomposition, and presumably to increased a c i d i t y i n the upper peat layers. Eventually the substrate becomes sui t a b l e f o r the growth of those Sphagnum species (e.g. S_. fimbriatum) t o l e r a n t of somewhat d r i e r conditions. Sphagnum Bog Phase: Once Sphagnum mosses become established, the storage capacity of the s i t e increases markedly, r e f l e c t i n g the high water-retention a b i l i t y of the hyaline c e l l s of these mosses (Rigg, 1940). The hyaline c e l l s , through c a p i l l a r y action (Moore and Bellamy, 1973), delay the outflow of p r e c i p i t a t i o n , the main source of water f o r the system. Sphagnum may also decrease evaporation, acting as a seal over the surface. The net e f f e c t i s an increase i n the storage capacity of the peat mass and addition- a l peat accumulation. The disappearance of Spiraea and Myrica i s associated with Sphagnum development. Sphagnum has a high exchange capacity f o r cations (Clymo, 1963),and probably deprives Myrica and Spiraea of nutrients. Sphagnum growth eventually also r e s t r i c t s the growth of Ledum r e s u l t i n g i n the development of t y p i c a l r a i s e d bog vegetation. 164 Although the order of progression of Sphagnum species i n bog develop- ment has not yet been established for the Fraser Delta, i t appears that Sphagnum capillaceum plays an important r o l e i n the process. For example, at P i t t Lake Bog, capillaceum i s the main b u i l d e r of hummocks within the Ledum-dominated area. In southern Burns Bog, areas regenerating a f t e r e i t h e r f i r e or c l e a r i n g ,are a c t i v e l y being covered by coalescing hummocks and mats of Sphagnum capillaceum. Sphagnum papillosum hummocks also occur i n these regenerating areas, but i n fewer numbers. Once S_. capillaceum becomes established, presumably there i s a progression towards the develop- ment of a c l a s s i c r a i s e d Sphagnum bog. The general model f o r r a i s e d bog development presented here i s not intended to represent the sequence to be found at every l o c a l i t y i n every bog i n the Fraser River Delta, nor can a l l the phases of the sequence be expected to occur i n every core. The shrub phase varies i n duration and composition as i l l u s t r a t e d by core BBDC where Ledum dominates and core CBB where Myrica and Spiraea dominate. However, i t seems, that i n general, r a i s e d bog development on the Fraser River Delta involves a sedge stage, followed by some sort of shrub stage, eventually leading to the Sphagnum stage. A d d i t i o n a l cores from other bogs need to be analyzed to confirm and r e f i n e t h i s model. DISCUSSION Comparison of Fraser River Delta Raised Bog Development with Other Raised Bog Sequences Rigg (1925) discussed Sphagnum bog development of the North P a c i f i c Coast of North America on the basis of a f i e l d study of 78 bogs. Although 165 he did not use palynologic techniques he was able to suggest that i n many bogs the development sequence was from sedge to shrub to Sphagnum bog phases. He concluded that i n most cases Sphagnum bog encroached on swamp environ- ments (shrubs) and thus that "the bog as s o c i a t i o n commonly follows a swamp association". These conclusions are c l e a r l y confirmed for the bogs of the Fraser River Delta by t h i s study. Heusser (1955, 1960) described a number of cores from various bogs i n the Queen Charlotte Islands, Vancouver Island and the west coast of B r i t i s h Columbia. Some of these appear to have developed without a limnic basal peat, and to have produced considerable depths of peat, and so appear to be ra i s e d bogs. D i r e c t comparison of these to Burns Bog i s d i f f i c u l t because Heusser's main objective was to obtain paleoclimatic information. However, i t appears that sedge peats always form the basal organic layer_as i n Burns Bog. Ligneous peats follow, although the nature of these i s not always c l e a r , and they may have been produced mainly by trees instead of shrubs. Heusser's p o l l e n p r o f i l e s do not i n d i c a t e c l e a r l y the presence of shrub- dominated horizons. Sphagnum peats and high numbers of Sphagnum spores occur toward the tops of most of these sequences. Heusser ascribed most of these l o c a l vegetation/peat changes to c l i m a t i c f a c t o r s . From the r e s u l t s i n Burns Bog, i t i s probable that at l e a s t some of the changes are the r e s u l t of natural successional phases i n bog development. For example, some of the c l i m a t i c reasons given by Heusser (1960; p. 128-130) for appearances, disappearances and frequency changes i n species might be accounted f o r be t t e r by successional changes. Auer (1930) c a r r i e d out an extensive i n v e s t i g a t i o n of peat bogs i n southeastern Canada. In the case of r a i s e d bogs, p a r t i c u l a r l y the maritime 166 ones of eastern Canada, he found that Carex peat rested on mineral s o i l , with tree stumps seldom found i n the basal Carex layers. He concluded that p a l u d i f i c a t i o n of the land into peat bogs was c h i e f l y the r e s u l t of the spread of Carex associations, and that Sphagnum peats developed sub- sequently on t h i s substrate. In contrast to Burns Bo.g, none of the r a i s e d bog p r o f i l e s of the east coast show a d e f i n i t e shrub stage, although Auer mentions the growth of dwarf shrub plant assemblages on Carex peat. Elsewhere i n the world, only one s i m i l a r d e l t a i c or estuarine r a i s e d bog has been found for comparison. This i s Shopwick Heath, Somerset, England, where Godwin (1975) describes a r a i s e d bog that developed on estuarine clays. The sequence of development i s : Phragmites-Cladium (sedge-type peat), followed by a t h i n layer of woody peat (Betula fen wood); a Calluna-Sphagnum stage and f i n a l l y Molinia-Sphagnum peats. Although the species composition i s very d i f f e r e n t from that of Burns Bog, there i s a marked successional s i m i l a r i t y between t h i s sequence and that proposed for the Fraser River Delta. In both, emergence i s followed by open sedge fens, which presumably give s u i t a b l e conditions for the eventual advent of more acidophilous species t y p i c a l of r a i s e d bogs. In general i t seems that the Burns Bog sequence bears some s i m i l a r i t y to that of other r a i s e d bogs, most p a r t i c u l a r l y on the west coast of North America. The basal sedge phase seems to be e s p e c i a l l y c h a r a c t e r i s t i c , although the development of a shrub phase i s apparently not shared with other bogs. The Role of the Raised Bog i n Fraser River Delta Evolution Another i n t e r e s t i n g aspect of the r a i s e d bogs of the Fraser Delta i s 167 that these bogs seem to form the main organic phase of the d e l t a evolution- ary sequence. The backwaters and i n t e r d i s t r i b u t a r y areas of many other major r i v e r deltas, e.g. M i s s i s s i p p i , Orinoco, are the s i t e s for major accumulation of organic deposits because the constantly wet conditions s a t i s f y the requirements for a peat-forming template (Moore and Bellamy, 1973). I t i s i n t e r e s t i n g that i n the Fraser Delta, extensive tree-dominated swamplands do not occur, and that the natural organic r e s e r v o i r seems to be ra i s e d bogs. A map of the peat resources of the Fraser Lowland prepared by Anrep (1928) shows the considerable extent of bog deposits on the d e l t a surface. E i t h e r there are not tree species i n t h i s part of North America that can be involved i n organic accumulation i n d e l t a swamps, or the condi- tions are more favourable f o r the formation of r a i s e d bogs, so that poten- t i a l swamp vegetation has no opportunity to become permanently established. Possibly with s u i t a b l e v e r t i c a l growth of these r a i s e d bogs, the crowns might become dry enough to support the growth of f o r e s t trees such as Tsuga (Rigg, 1925). Currently i t seems that the bogs are s t i l l in:.the "youthful" active growth stage. An i n t e r e s t i n g p a r a l l e l i n the formation of r a i s e d , d e l t a i c , organic deposits can be found i n the compound d e l t a of the Klang and Langat Rivers of Malaysia (Coleman et al_. , 1970) . Large mounds of organic material composed of logs and limbs are accumulating i n the i n t e r d i s t r i b u t a r y areas, to l e v e l s above the impounding levees. Quite c o i n c i d e n t a l l y , the peat accumulation i n one of these "raised" organic deposits began at 4,540 ± 100 BP, very close to the time of i n i t i a l organic accumulation i n Burns Bog. The poor drainage i n these Malaysian organic heaps, together with high r a i n f a l l and decreased evaporation (Coleman et a l . , 1970) appear to account 168 for organic accumulation above the water l e v e l ; t h i s i s a s i t u a t i o n s i m i l a r to that i n the Fraser Delta. I t would be valuable to investigate other d e l t a i c areas to determine what conditions are p r e r e q u i s i t e for the develop- ment of such "raised" organic deposits. The Relationship of the Main Paleoecologic Events i n Burns Bog to the Development of the Fraser Delta The r e s u l t s obtained from t h i s study of Burns Bog provide an i n s i g h t into the h i s t o r y of the southern section of the Fraser Delta. Sea Level Changes: The upper part of the i n t e r t i d a l d e l t a - f r o n t phase at the base of the three cores i n t h i s study corresponds e s s e n t i a l l y to sea l e v e l (Fig. 49). I t also appears that at the time of the appearance of these s i t e s above water, j u s t a f t e r 5,000 BP, sea l e v e l must have been very near what i t i s today, with any difference probably being le s s than a meter. In Boundary Bay, s a l t marsh peats, approximately at sea l e v e l (geodetic datum) are dated at 4,350 years BP (Kellerhals and Murray, 1969). These peats apparently d i r e c t l y o v e r l i e s i l t s belonging to the i n t e r t i d a l d e l t a - front phase (Hebda, unpublished r e s u l t s ) . This i n d i c a t e s that the emergence of the d e l t a surface at the Boundary Bay l o c a l i t y occurred at the same time as at the three core s i t e s i n Burns Bog. This nearly synchronous emergence of four widely separated l o c a l i t i e s may ind i c a t e a l o c a l r e l a t i v e decline i n sea l e v e l . Recent studies of e u s t a t i c sea l e v e l changes i n the southwestern P a c i f i c Ocean (Bloom, 1970; Curray et a l . , 1970) and the western A t l a n t i c Ocean (Redfield, 1967) seem to i n d i c a t e that between 4,000 and. 5,000 years ago sea l e v e l s were probably s t i l l r i s i n g , but that the rate of r i s e had 169 decreased considerably over previous rates. In addition, these workers concluded that sea l e v e l s i n these areas i n the Holocene never surpassed the current p o s i t i o n although they may have approached i t . Studies from Scandinavia seem to ind i c a t e a s i m i l a r though gradually decreasing rate of sea l e v e l r i s e (with o s c i l l a t i o n s ) , with the current p o s i t i o n being approached over the l a s t 4,000 years (M5rner, 1971), C l e a r l y the l o c a l emergence of the southern Fraser Delta does not con- form to the above pattern. The Fraser River Delta i s being formed i n a t e c t o n i c a l l y a c t i v e area with u p l i f t c urrently occurring i n surrounding uplands (Mathews et a l . , 1970). Such te c t o n i c a c t i v i t y , together with other movements such as earthquakes (Blunden, 1975) could e a s i l y account for the apparent sea l e v e l drop. Another possible explanation for the seemingly synchronous emergence r e l a t e s to the rate of e u s t a t i c sea l e v e l change. I f , as demonstrated for the western P a c i f i c and A t l a n t i c , the rate of sea l e v e l r i s e decreased between 4,000-5,000 years BP, then the rate of d e l t a emergence (progradation) would be expected to increase, assuming the same rate of sediment input. Only small changes i n the r e l a - t i o n s h i p of land to sea l e v e l are required for large expanses of d e l t a i c f l a t l a n d s to become emergent. Following t h i s l o c a l emergence, there i s a marine transgression, recorded by s a l t marsh peats i n core BBDC and Boundary Bay, but s i g n i f i c a n t - l y not i n cores CBB and DNR. Normally, such a transgression would imply a r e l a t i v e r i s e i n sea l e v e l i n the western and southern parts of the study area. Although t h i s may be true, there i s at l e a s t one a l t e r n a t i v e explanation that should be'considered. 170 Currently i n Boundary Bay, s a l t marsh peats form at about the mean high t i d e l e v e l which i s 0-1 m above mean sea l e v e l (geodetic datum). Thus the s a l t marsh peat horizons (BBDC, Boundary Bay) formed at an eleva- t i o n equivalent to or above the elevation of formation ( '0-11 m) of the upper i n t e r t i d a l d e l t a - f r o n t s i l t y peats which underlie them. This means that no change i n sea l e v e l would have been necessary to account f o r the environmental change from estuarine marsh to s a l t marsh (e.g. BBDC - II to BBDC - I I I ) . A switch from fresh-brackish water influence (estuary) to s a l t water influence ( t i d a l f l a t s ) would be a l l that was necessary for the vegetation and sedimentary change. At l e a s t two explanations for t h i s conversion are poss i b l e . The main channel of the Fraser River may have moved northward, thereby sharply de- creasing fresh water and sediment supply to t h i s part of the d e l t a . A l t e r - n a t i v e l y , the d e l t a may have b u i l t out far enough to have joined Point Roberts to the mainland, thus preventing fresh-brackish estuarine water from flowing south along the edge of the d e l t a to s i t e BBDC. This i s exactly what happens today, and i s the main reason.that Boundary Bay water i s very s a l i n e . Zone BBDC - II represents a s i t u a t i o n approximating the f i r s t permanently emergent horizon of the d e l t a - f r o n t . The actual edge of the d e l t a - f r o n t (-10 m level) would be expected to be located about 6 km further out to sea (Luternauer and Murray, 1973). At 4,400-4,100 BP t h i s would mean that the submerged d e l t a - f r o n t would have reached at l e a s t the lower slopes of the Point Roberts upland, j o i n i n g i t to the d e l t a , l i k e l y i n d i c a t i n g annexation of Point Roberts at t h i s time. Cut-off of sediment supply accompanied by continuing sediment subsi dence through natural compaction, may also have promoted a marine trans- gression. Of course e u s t a t i c sea l e v e l changes, tectonic movements 171 (Mathews et a l . , 1970) and earthquakes (Blunden, 1975) should not be ruled out as a d d i t i o n a l factors f o r the s l i g h t r e l a t i v e r i s e i n sea l e v e l . The abrupt termination of the s a l t marsh phase i n core BBDC, followed by sedge peats, containing s l i g h t traces of s i l t , seems to imply e i t h e r a l o c a l sea l e v e l drop, or renewed flooding from the Fraser River, perhaps r e s u l t i n g from channel r e l o c a t i o n . Following the termination of the s a l t marsh phase, there i s no evidence of marine readvance i n any of the cores. The r e l a t i v e sea l e v e l changes suggested i n the foregoing discussion seem to i n d i c a t e some modifications to Blunden's sea l e v e l curve for the Fraser River Delta, at l e a s t for the southern part of the d e l t a . F i r s t , as Blunden shows, r e l a t i v e sea l e v e l had reached i t s current p o s i t i o n between 4,000 and 5,000 BP. Before t h i s time, i t may possibly have been above and not below present l e v e l s , as indicated by Blunden. Second, contrary to Blunden's curve, there seems to be no conclusive evidence that sea l e v e l s were s i g n i f i c a n t l y above those of the present between 2,000 and 4,000 BP. With the current l i m i t e d number of radiocarbon-dated sea l e v e l horizons f o r the 5,000-2,000 BP i n t e r v a l , i t i s not p o s s i b l e to a r r i v e at any firm conclusions regarding exact sea l e v e l p o s i t i o n s , or the causes and e f f e c t s of l o c a l sea l e v e l change. More dates need to be obtained on horizons whose exact o r i g i n a l e l e v a t i o n of formation i s known with respect to sea l e v e l . River Channel Changes: The r e s u l t s from Burns Bog also have some bearing on i n t e r p r e t i n g the p o s i t i o n of the Fraser River channels i n the past 5,000 years. The c o n t i n u i t y of the deposits across Burns Bog seem to i n d i c a t e that the Fraser River has not passed through the area i n the l a s t 5,000 years. This i s opposite to the view expressed by K e l l e r h a l s and Murray 172 (1969). Channels would be expected to leave some trace i n subsurface top- ography or sediments that should be r e f l e c t e d by vegetational differences on the surface (cf. the f i l l e d - i n channel that runs northwest through Lulu Island (Blunden, 1975) ). Unless such evidence i s found, no case can be made for southward flow of the Fraser River into Boundary Bay since 5,000 BP. Blunden (1975) has suggested that the South Arm of the Fraser River i s very recent i n o r i g i n (post-2,500 BP). According to him, i t formed when the Fraser River, which was previously flowing to the northwest, breached the Greater Lulu Island Bog-Burns Bog r a i s e d bog complex, taking the path of l e a s t resistance to the S t r a i t of Georgia. Results from the cores do not c l e a r l y show any i n d i c a t i o n of such an event. I t i s l i k e l y that the s i t e s were too f a r away from the r i v e r to be a f f e c t e d and that levees would have confined the r i v e r water. I f such a southerly d i v e r s i o n occurred, a regional increase i n alder would be expect- ed, as t h i s pioneering tree colonized the newly established banks of the r i v e r . S i g n i f i c a n t increases i n alder do occur at the 2.5 m l e v e l i n both cores CBB and BBDC. Although suggestive, t h i s i s not f i r m proof that avulsion occurred at that p a r t i c u l a r time; confirmation w i l l have to come from d e t a i l e d d r i l l i n g along the river-bog contact faces. In view of the f a c t that r a i s e d bog development i s a natural phase of d e l t a maturation, i t i s also possible that Lulu Island Bog and Burns Bog developed independently. However, t h i s p o s s i b i l i t y seems remote i n the l i g h t of the s i m i l a r i t i e s i n depth of peat and stratigraphy, opposed p o s i t i o n of the bogs, and abrupt margins of the peat bogs against the r i v e r channel. 173 A p p l i c a t i o n of the Study The r e s u l t s of the present i n v e s t i g a t i o n have a number of a p p l i c a t i o n s : 1. F i r s t , the sequence of development i n Burns Bog provides a basic frame- work for further i n v e s t i g a t i o n of Fraser Lowland r a i s e d bogs. This sequence can also be used as an example to which the paleoecology of other r a i s e d bogs i n western North America can be compared. 2. The c h a r a c t e r i z a t i o n of wetland vegetation types using palynomorph " f i n g e r p r i n t s " (including m i c r o f o s s i l s other than p o l l e n and spores of vascular plants) from surface samples of modern analogs provides a valuable t o o l f o r i n t e r p r e t i n g the paleoecology of depositional s i t e s containing t e r r e s t r i a l peats. I f more of these kinds of data were to be c o l l e c t e d from wetland environments,precise reconstructions of the l o c a l h i s t o r i e s of such s i t e s could be made. 3. During the h i s t o r y of the bog, Sphagnum seems to have recolonized quickly areas that were destroyed by f i r e , j u s t as i t recolonizes badly disturbed areas today. This implies that the parts of the bog abandoned a f t e r peat mining can be expected to return to vi a b l e r a i s e d bog conditions i n a r e l a t i v e l y short period of time (50 years). This means that Burns Bog s t i l l r e tains the a b i l i t y to maintain i t s e l f , and should not be abandoned as being beyond recovery. 4. The great contrast i n peat accumulation rate f o r peat deposits (6.67 cm /100 years) and the Sphagnum hummock growth rate (82 cm/100 years) indicates that under i d e a l conditions a much greater y i e l d of Sphagnum may be obtained. The peat cutt i n g s i t e s i n Burns Bog seem to be i d e a l f o r t h i s high rate of Sphagnum growth. I f the demand for raw, clean Sphagnum increased (e.g. for f i l t r a t i o n and absorption of heavy metal, contaminants i n water) Sphagnum 174 culture i n these s i t e s would appear to be a d i s t i n c t p o s s i b i l i t y , 5. The success of t h i s study i n recognizing and dating the i n t e r t i d a l d e l t a - f r o n t phase ( i . e . sea level) means that a d d i t i o n a l radiocarbon dating of t h i s horizon i n the Fraser Delta and other coastal s i t e s should provide an accurate method f or e l u c i d a t i n g the h i s t o r y of d e l t a growth and sea l e v e l changes. The advantage of t h i s technique i s that dates can be obtained f o r autochthonous horizons rather than on materials such as logs and s h e l l s which may be allochthonous, and possibly not the same age as the matrix containing them. 6. Archeologists w i l l be able to use the paleoecologic sequence e s t a b l i s h - ed to i n t e r p r e t the h i s t o r y of neighbouring s i t e s such as St. Mungo Cannery (Calvert, 1970) and Glenrose Cannery i n terms of the environmental factors a f f e c t i n g the cultures. 7. The computer program developed here provides a quick method f or calcu- l a t i n g r e l a t i v e and absolute p o l l e n values. I t also f a c i l i t a t e s the use of d i f f e r e n t combinations of taxa to obtain a c l e a r e r p i c t u r e of changes i n ce r t a i n parts of the vegetation. 8. Most s i g n i f i c a n t l y , the i d e n t i f i c a t i o n of successional sequences sets the stage f o r p r e d i c t i n g natural vegetational changes i n the wetlands of the Fraser Lowland, and pos s i b l y other wetland s i t e s of the north P a c i f i c Coast. In addition, i t provides the opportunity to forecase environmental consequences that might be expected where man disturbs the vegetation, peat or drainage of ra i s e d bogs. 175 THESIS SUMMARY The following main conclusions have been reached from the analyses performed i n t h i s i n v e s t i g a t i o n : 1. Burns Bog developed on Fraser River d e l t a i c deposits which appeared above sea l e v e l j u s t a f t e r 5,000 years BP. The basal s i l t y sand sequence, containing high percentages of Pinus and Picea p o l l e n as well as recycled T e r t i a r y p o l l e n , indicates that r i v e r transport was very important i n the formation of the palynomorph assemblages of these basal sediments. Local stands of Scirpus and Carex colonized the newly av a i l a b l e land surface and contributed to the high Cyperaceae p o l l e n l e v e l s . 2. A f t e r the i n i t i a l c o l o n i z a t i o n phase, the development of the bog progres- sed through three major stages; sedges, shrubs and Sphagnum. F i r s t sedges (perhaps with some grasses) occupied most of the area producing sedge peats. Eventually, shrubs such as Myrica and Spiraea appeared, e i t h e r accompanied or c l o s e l y followed by Ledum groenlandicum. In the ce n t r a l part of the bog, these shrubs were subsequently replaced (at 2,925 ± 125 BP) by Sphagnum bog conditions t y p i c a l of the present r a i s e d bog. 3. At the western end of the bog, there was a short s a l t marsh phase (4,125 ± 100 BP), characterized by chenopod and grass p o l l e n . This was caused p o s s i b l y by a shut-off of fresh/brackish water from the Fraser River, r e s u l t i n g from juncture of the d e l t a to Point Roberts. 4. In the eastern section of the bog, at the foot of Panorama Ridge, the sedge-grass phase was only t r a n s i e n t . I t was c l o s e l y followed by a 176 Myrica-Spiraea-Lysichitum swamp which l a s t e d u n t i l the onset of true Sphagnum bog conditions i n very recent times. 5. F i r e s have played an important role i n the ecology of t h i s Sphagnum bog. P e r i o d i c a l l y the vegetation of r e l a t i v e l y high, dry s i t e s was burned o f f , while wet depressions remained untouched. The unburned depressions maintained l i v e Sphagnum and became centers of peat accumu- l a t i o n that eventually grew to an elevation above the surrounding burned areas. As a r e s u l t , many of the burned s i t e s were converted to depressions. 6. The AP spectrum of the three cores examined, indicates that the region- a l upland vegetation around the southern Fraser Delta remained essen- t i a l l y unchanged throughout the h i s t o r y of Burns Bog. On the d e l t a proper, however, fl u c t u a t i o n s i n alder p o l l e n were probably associated with c o l o n i z a t i o n of levees along s h i f t i n g r i v e r channels. 7. Recent logging and c l e a r i n g of upland and d e l t a s i t e s have res u l t e d i n decreases i n Abies, Tsuga, Pseudotsuga and Picea p o l l e n l e v e l s while Alnus and grass p o l l e n frequencies have increased markedly. 8. Three groups of ericad t a x a , d i f f e r e n t i a t e d on the basis of tetrad d i a - meter and p o l l e n productivity, were found to r e f l e c t dry, intermediate and wet Sphagnum bog habitats. In t h i s way a more precise i n t e r p r e t a - t i o n of events i n the Sphagnum phase was po s s i b l e . 9. The r e l a t i o n s h i p s of p o l l e n to the vegetation of selected wetland en- vironments was studied by the use of surface samples. The r e s u l t s obtained were applied d i r e c t l y to the i n t e r p r e t a t i o n of vegetation and peat development i n the cores. Although surface sample palynomorph spectra do not give a d i r e c t quantitative measure of the vegetation , 177 they do provide " f i n g e r p r i n t s " by which vegetation types can be recog- nized i n the sedimentary record of the bog. 10. The major paleoecologic changes indicated by peat and p o l l e n s t r a t i - graphy, r e s u l t mainly from successional processes that are s t i l l observable i n the Fraser Lowland, rather than from c l i m a t i c changes. This suggests that more emphasis should be placed on understanding normal ecologic processes i n wetlands ( p a r t i c u l a r l y bogs). Although c l i m a t i c changes can play an important part i n vegetation change, they may be subordinate to the e f f e c t s of sedimentary processes, physio- graphic changes and successional trends. As f a r as the author knows t h i s i s the f i r s t d e t a i l e d o u t l i n e of ra i s e d bog development i n western North America. This study demonstrates that studies of current vegetation and pollen-vegetation r e l a t i o n s h i p s can be combined with palynologic i n v e s t i g a t i o n s to reconstruct the h i s t o r y of a ra i s e d bog. 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Palynology of a section from the r a i s e d peat bog "Wietmarscher Moor" with s p e c i a l reference to fungal remains. Acta Bot. Neerl. 21: 261-284. Van Geel, B. 1976a. A Paleoecological Study of Holocene Peat Bog Sections, Based on the Analysis of Po l l e n , Spores and Macro and Microscopic Remains of Fungi, Algae,Cormophytes and Animals. Ph.D. Thesis, University of Amsterdam. 75 p. Van Geel, B. 1976b. F o s s i l spores of the Zygnemataceae i n ditches of a p r e h i s t o r i c settlement i n Hoogkarspel (The Netherlands). Rev. Palaeobotan. Palynol. 2£: 337-344. Voorrips, A. 1973. An ALGOL-60 program for computation and graphical representation of p o l l e n a n a l y t i c a l data. Acta Bot. Neerl. 22: 645-654. Walker, D. 1970. D i r e c t i o n and rate i n some B r i t i s h p o s t - g l a c i a l hydroseres. In Studies i n the Vegetational History of the B r i t i s h I s l e s . Edited by D. Walker and R. G. West. Cambridge. Walton, A., M. A. Trautman, and J . P. Friend. 1961. Isotopes, Inc. Radiocarbon measurements. Radiocarbon 3_: 47-59. Wright, H. E. J r . 1967. The use of surface samples i n Quaternary p o l l e n analysis. Rev. Palaeobotan. Palynol. 2_: 321-330. 184 APPENDIX 1: SPECIES COMPOSITION OF THE VEGETATION TYPES OF BURNS BOG, DELTA, BRITISH COLUMBIA This appendix contains the data from which the vegetation type descrip- tions were made (Ch. 2) and from which the vegetation map (Fig. 4) was produced. The species cover data are presented according to the following cover estimate scale modified from the Braun-Blanquet scale (Mueller- Dombois and Ellenberg, 1974): Percentage Range Verbal Equivalent Symbol 50-100 Dominant DOM 25-50 Very common VCM 5-25 Common COM 1-5 Occasional OCC Less than 1 if- Absent The bracketed numbers i n i t a l i c s that follow cover designations i n the table are the actual average percentage cover values f o r vegetation types where f i v e or more quadrats were investigated (averaging le s s than 5 quad- rats was considered not to give a meaningful value). N o n - i t a l i c i z e d numbers i n brackets are species frequencies (number of quadrats containing species/ t o t a l number of quadrats of the vegetation type). Frequency (together with average cover where possible) i s used f o r herbs, ferns, mosses, liverworts and lichens which were estimated i n 1 m x 1 m quadrats. Frequency i s a better measure of the ro l e of these plants which are ubiquitous i n the 185 vegetation but have low cover. S o l i t a r y + signs denote that a species i s present within the vegetation type but was not encountered i n quadrats studied. Of the 60 quadrats examined, 6 were judged to be intermediate i n nature between vegetation types. The cover values of these 6 quadrats were excluded from averages. TABLE 5: AVERAGE SPECIES COVER FOR THE VEGETATION TYPES OF BURNS BOG, DELTA, B. C. Species Number of 10 m x 10 m quadrats Number of 1 m x 1 m quadrats Mixed Pine B i r c h Spiraea Coniferous Salmonberry Alder Heathland Woodland Woodland Brushland Woodland Bushland Woodland 20 100 11 55 15 15 40 30 15 Gymnosperm Trees Picea sitchensis Pinus contorta Taxus brevifoiia Thuja plicata Tsuga heterophylla Angiosperm Trees Acer circinatum • Acer macrophyllum Alnus rubra Betula occidentalis Crataegus douglasii Ilex aquifolium Populus tremuloides Populus balsamifera subsp. trichocarpa VCM(38) + + + D0M(53) + + + 0CC(3.5) DOM + + + + o c c COM + + COM (14) OCC(5.5) + VCM(36) C0M(15) 0CC(2.5) + OCC(2) COM(IO) 0CC(4) + + C0M(22) OCC(4) VCM(28) COM (12) + + + OCC + OCC + OCC DOM OCC oo CTI Table 5 (Continued) Mixed Pine Birch Spiraea Coniferous Salmonberry Alder Species Heathland Woodland Woodland Brushland Woodland Bushland Woodland Angiosperm Trees (cont.) Malus fusca Rhamnus purshianus Salix hookeriana Salix lasiandra Sorbus auouparia Shrubs Amelanchier alnifolia Andromeda polifolia Cornus serioea subsp. ocaidentalis Empetrum nigrum Gaultheria shallon Kalmia miorophylla subsp. oceidentalis Ledum groenlandicum Lonicera involucrata Menziesia ferruginea Myrica gale Ribes lacustre COM (5) + C0M(13) C0M(9) D0M(69) OCC COM OCC OCC + VCM(45) OCC OCC(1.5) - D0M(62) COM + COM OCC COM OCC + 0CC(6. 5) OCC(2.5) + DOM (51) 0CC(4) COM(ll) + C0M(23) C0M(17) + OCC(2) + OCC(2.5) COM(19) C0M(9) VCM(25) OCC(3) + + COM COM OCC + oo OCC OCC + 188 c 0 Is Co C o 1 co + Co Co Co Co Co I CO U TS u c <U (ti " I—I X w a PQ fti r w + •+. •+• Co S3 8 vs. C o 53 c o S c o c o + co o o Co Co I Co c ? Co to —  0 C -O M (ti d) (D i—I X M-l -0 -H -H 0 SCO 8 s LO Ml 00 co c o c3 CO + C o vs 1 + § C o CO Co CO CO T3 « B C£> (ti « r-l Ss X M cn a . 3 co u + Ci X (ti O H •H O CQ O s C o Co Co + 8 Co Co Co i -a a) § c H ft o o s Ml to s C o t-s. 1 to I C o i >0 a (ti iH ,C -P (ti SB + LO i-S —. C o CO T) CD 3 a •i-i c 0 u i n CD i-H •s EH W CD •H O CD A W -P C 0 U CO CO CJ CO CO s o Ss O s o CO CB CJ 3 O s a O K +i C (3 CO CO CO Ss O CO co CO CO CO e « Ss .CO s CO 3 3 K CO CO CO CO CO 3 a <3 3 3 s 3 3 O S  O S  s 3 q n  c | ft; ft; ft; ft; f ? ft; CO CJ CB CO s CJ A ? CO _ CJ Cj> ^ o "CJ S Cj CB g co o co T—i <B CO (» o ?s Ss a, CO o s Cn 3 CO 3 CB in  s s in  co co <o CO CO CO CO CO CO co CO w • ^ » Table 5 ' (Continued) Species Mixed Pine Birch Spiraea Coniferous Salmonberry Alder Heathland Woodland Woodland Brushland Woodland Bushland Woodland Herbs Cardamine breweri Carex lentioularis Carex obnupta Carex pauciflora + Carex pauperoula + Carex phyllomanica + Carex rostrata Ciroaea alpina Claytonia sibiriaa Cornus unalasahkensis Drosera anglioa + (3) Drosera rotundifoHa OCC (1,17) DuHchium arundinaoevm + Epilobiwn angusti- foliim Epilobiwn minutum • - Eriophomm chamissonis +(31) Galeopsis tetrahit Galium aparine + (3) +(3.5) + +(8.5) + 0CC(21) + d) + (13) + (33) Table 5 (Continued) Species Mixed Pine Birch Spiraea Coniferous Salmonberry Alder Heathland Woodland Woodland Brushland Woodland Bushland Woodland Herbs (cont.) Galium ?triflorum Glyceria grandis Holcus lanatus Junaus effusus Lycopus uniflorus Lysichitum americanum Lysimachia thursiflora Maianthemum dilatatum Myosotis laxa Nuphar lutea subsp. polysepala Oenanthe sarmentosa Phalaris arundinacea Phlewn pratense Rhynchospora alba Rubus chamaemorus - M l ) OCC(2. 5, 28) -M38) + + + (7) + (12) + (3) + (1) + COM(14,20) COM (13120) VCM (60) 0CC(1,12.5) 0CC(2,5.5) - - + - + OCC(4. 5, 20) + (5) + (5.5) Table 5 (Continued) Mixed Pine Birch Spiraea Coniferous Salmonberry Alder Species Heathland Woodland Woodland Brushland Woodland Bushland Woodland Herbs (cont.) Rumex acetosella Scutellaria lateriflora - Solarium dulcamara Stachys cooleyae Stellaria crispa Tiarella trifoliata Tofieldia glutinosa + Trientalis europaea subsp. arctica Tri folium repens Typha latifolia Vaccinium oxycoccos Viola palustris Ferns Athyrium filix-femina Dryopteris assimilis Polypodium glycyrrhiza + + (27) + C0M(7,65) +(14.5) + + + + + COM(6,25) C0M(7,15) + OCC (1) + + (10) + COM (6,53) OCC(1,20) + (17) + + + (7) 0CC(3,53) OCC (1,20) + Table 5 (Continued) Mixed Pine Birch Spiraea Coniferous Salmonberry Alder Species Heathland Woodland Woodland Brushland Woodland Bushland Woodland Ferns (cont.) Polystichum rmnitum - - - - +(5) OCC(2,23) OCC{3,60) Pteridium aquilinum OCC(2,19) COM(18, COM(8,33) COM(19, OCC(2,15) - 60) 57) Mosses Antitriohia ourti- pendula + + (7) + (7) + +(3) + (7) Aulaoomnium androgynum +(4) +(9) +(33) + + +(10) Aulaaomnium palustre + + - +(7) - + Brachythecium sp. - + - - - + +(7) Claopodium arispi- folium Dioranum fuscesoens -(1) +(4) - + + + + Dicranum sooparium +(7) 0CC(4,35) + +(7) +(3) - + Drepanocladus unainatus + + Fontinalis sp. _ _ _ _ _ + Homalotheoium fulge- saens + - +(7) Hylocomium splendens + +(7) +(7)l +(7) +(10) OCC a, 30) +(7) Hypnum oiroinale + + +(7) + + +(13) +(7) 193 TJ a M fd CD rH Tj TJ d 0 «c o o CO to I o Co Co Q CN r-- •+• + r o co o CM U TJ 0) m 8 (0 to CO o 00 " 2 8 + ro ro IT) IT) Co Co <o TJ CD Cl •rH -P c o U i n m rH •s TJ tn 3 TJ O C RH (TJ 0) 0 RH .X MH TJ •H -H 0 SCO o s u TS C (d H r H .-! •A 10 a, 3 CO M m a rC (TJ o rH u TJ •H 0 « o s TJ C Q) (TJ c rH •H TJ PH o o s TJ S h lc  +J (0 (1) CO <u •rH U CD ft to •p c 0 u '—V .—. , ̂  CO » » ro rH CN CN '* ' ' •» + + + + + + o CM + CB •A r-i •A •A •A CO S •A CO CB •A •A CB •A CO CO S S M K CB o CB K CB CB CO o Si CB S CO o S « CB r H 3 1 | CO r Q s CB •A _ a, A ; a- •A •A CB _ (35 CO JH CB - r - -P O O o <a s •A •A CB r H •§ «3 •A <a CB +i o •A C32 OH CB CB CO CB RH i n + •A r ^ CO 1 + CN CN •- «~H ,—^ ^—• CN LO " — '— ' CO <_ oo ro s •A ? H CB K X •A Si _ CO CO •A M Ss CO O K CB •A CO •A o RH ro + + cn co s CB ? H O CO CO ro rH IM Co co CN CO s a, a, co CB CB rn " « CB 'XS T_ cy •A -A r H S3 4i ' A Si ... Qq Qq Table 5 (Continued) Mixed Pine B i r c h Spiraea Coniferous Salmonberry Alder Species Heathland Woodland Woodland Brushland Woodland Bushland Woodland Mosses (cont.) Sphagnum oapillaceum var. tenellum C0M{12, C0M(8,36) + - + 59) Sphagnum fuscum OCC(1,8) OCC(4) - Sphagnum papillosum OCC(1,10) + - - Sphagnum reourvum COM(1,21) -f(13) -M13) + - Sphagnum squarrosum - + - - +(3) - + Sphagnum tenellum OCC(2,IS) + Stokesiella oregana OCC(2,27) COM(11, OCC(4, OCC(3,60) COM(6,52) COM(9,87) COM(6,80) 80) 93) Stokesiella praelonga - - +(10) 0CC(1,63) +(20) Tetraphis pellucida - +(2) - - + - + Liverworts Frullania tamarisci subsp. nisquallensis (Sull.) Hatt. - - +(3) -f(lO) + Gymnooolea inflata (Huds.) Dum. +(3) - Table 5 (Continued) Mixed Pine Birch Spiraea Coniferous Salmonberry Alder Species Heathland Woodland Woodland Brushland Woodland Bushland Woodland Liverworts (cont.) Mylia anomala (Hook.) S. Gray Pellia c f . neesiana (Gott.) Limpr. Porella sp. Radula sp. Scapania bolanderi Aust. Lichens Cladina spp. Cladonia spp. Hypogymnia spp. Platismatia sp. Usnea sp. + (8) COM(10, 55) C0M(5,62) + (83) + (8) OCC(2,10) OCC(1,10) + +(10) +(27) + (13) + (7) OCC(2,11) + (13) + (42) + (13) + (11) + (20) + (7) + (13) + (7) 196 APPENDIX 2: COMPUTER PROGRAMS USED TO CALCULATE RELATIVE AND ABSOLUTE POLLEN VALUES FOR COMPUTER PLOTTED POLLEN DIAGRAMS These programs c a l c u l a t e percentages or absolute values for a l l spec- ies at one depth. The r e s u l t s are stored i n POLLEN and eventually output, one species at a time (not one depth at a time) into the f i l e that w i l l be used by the p l o t t i n g program. The values are output i n a format that can be used by the general p l o t t i n g program SPLOT (Lauriente, unpublished) to create a standard p o l l e n diagram. A s p e c i f i c example with r e a l values i s used i n the following sections f o r i l l u s t r a t i n g the programs. Appendix 2a: Program f o r c a l c u l a t i n g r e l a t i v e p o l l e n frequencies. Preliminary cards $JOB HEBDA[101,4). /TIME: 45; POLLEN DIAGRAM $RUN FORTRN *MAIN, LP : <BI: /OH/OP,: O/CK Main program 1 DIMENSION DEPTH(90),POLSTR(35),TOTALP(90),EXCLD1(90) C DEPTH, TOTALP, EXCLD1 must equal the number of samples + 2 C POLSTR( ) must be greater than the number of species to be included i n the percentage c a l c u l a t i o n s . 2 DIMENSION POLLEN(90,68) C POLLEN( , ) i s the array i n which values are stored for eventual output. The second number (e.g. 68) must be twice as large as the number of species because room must be a v a i l a b l e f o r 10 x expanded values. 3 IN=5 4 10=6 5 IND=0 6 J=0 7 L=l 8 M=l 9 SMPLES=84. C number of samples + 2 10 SP=3000. , C number of species x 100 , 11 1 READ(IN,100,END=2)DPTHIN C Reads i n a l l depths (1 per data card) corresponding to samples i n core. 12 100 FORMAT(1F5.0) 197 13 DEPTH(L)=-DEPTHIN*.01 14 L=L+1 15 IF(L.GT. SMPLES)GO TO 2 16 GO TO 1 17 2 J=j+1 18 I F ( J . GT. SMPLES)GO TO 60 19 TOTAL=.l 20 1=1 21 3 READ(IN,101,END=90)POLCNT C Reads i n p o l l e n counts (1 per data card) for a l l species at one depth. 22 101 FORMAT(1F5.0) 2 3 POLSTR(I)=POLCNT 24 TOTAL=TOTAL+POLSTR(I) C Totals a l l p o l l e n counts for a sample 25 1=1+1 26 IF(I.GT.SP/100)GO TO 10 27 GO TO 3 28 10 S=0.0 29 TOTALP(J)=(TOTAL/10.)+SP C Outputs t o t a l f o r each sample so that the number of grains comprising the sum can be graphed on the diagram. 30 READ(IN, 101)FRNCNT C Reads i n count f o r p o l l e n and spore types to be excluded from the t o t a l (e.g. ferns i n t h i s case). 31 EXCLD1(J)=SP+100.+(FRNCNT*100./TOTAL) C Calculates excluded counts as a percent of the t o t a l . 32 IF (EXCLDl.(J) .GT. 3400. )EXCLD1(J) =3400. 33 JK=1 34 K=l 7 35 11 PCNT=(POLSTR(JK)*100/TOTAL)+S C Calculates the percent of each species. 3 6 POLLEN(J,K)=PCNT 37 K=K+1 38 PCNTEX=(PCNT-S)*10+S C Calculates the lOx expansion of the percentage. 39 IF(PCNTEX.LT.100.+S)GO TO 50 40 PCNTEX=S+100 41 50 POLLEN(J,K)=PCNTEX 42 K=K+1 43 S=S+100. C Adding 100 to S serves to s h i f t the values for the next species along the x axis i n the p o l l e n diagram. 44 IF(S.GT.SP)GO TO 2 45 JK=JK+1 46 GO TO 11 C START OF WRITING SEQUENCE - writes i n output values arranged i n correct order and format f o r use by the p l o t t i n g program. 47 60 N=l 48 61 WRITE(10,102)POLLEN(N,M),DEPTH(N),IND 198 49 102 FORMAT(2F10.3,13) 50 N=N+1 51 IF(N.GT.SMPLES)GO TO 62 52 GO TO 61 53 62 M=M+1 54 IF(M.GT.2*SP/100)GO TO 90 55 GO TO 60 56 90 KK=1 57 94 WRITE (10,102)TOTALP(KK),DEPTH(KK),IND 58 KK=KK+1 59 IF(KK.GT.SMPLES)GO TO 91 60 GO TO 94 61 91 KK=1 62 97 WRITE(10,102)EXCLDl(KK),DEPTH(KK),IND 63 KK=KK+1 64 IF(KK.LE.SMPLES)GO TO 97 65 96 IND=1 66 STOP 67 END C End of main program $RUN LINK #MAIN,LP:/SH <MAIN/CC/B:50000,FTNLIB/E $KILL $UNIX RM MAIN. OBJ $UNIX LN /TMP/DATA TMP $ASSIGN SY:TMP,5 $ASSIGN SY:POLLEN,6 $RUN MAIN Data cards are included a f t e r the $RUN MAIN card. Data cards should be arranged as follows: Set of n cards, one for each depth, containing depth value with the f i r s t and l a s t depth repeated twice (necessary to obtain standard looking p o l l e n diagram). n sets containing m cards, where m i s the number of species, with one p o l l e n count per card. Species arrangement i n the data deck (containing m cards) should be the same as i t would read from l e f t to r i g h t on the p o l l e n diagram. $ASSIGN $ASSIGN SY:POLLEN,l $RUN SPLOT SPLOT cards would follow. 199 Appendix 2b: Program f or c a l c u l a t i n g absolute p o l l e n concentrations per cubic centimeter. Only the major differences from Appendix 2a are explained. Preliminary cards same as i n Appendix 2a. Main program 1 DIMENSION DEPTH(42),EXOTIX(42),VOLSED(42),WGTSED(42), VOLSAM(42) 2 DIMENSION VOLSSM(42),POLSTR(64),ABTOTV(42),ABSLTV(42,65) C D i f f e r s from Appendix 2a by the i n c l u s i o n of values necessary f o r c a l c u l a t i n g and outputting absolute values. 3 IN=5 4 10=6 5 IND=0 6 CONSTX=762000. C CONC. OF EXOTIC SOLUTION USED * VOL. OF SOLUTION ADDED 7 M=l 8 L=l 9 J=0 10 SMPLES=40. 11 SP=3100. C NUMBER OF SPECIES BEING CALCULATED * 100. 12 1 READ(IN,100,END=2)DPTHIN,EXTXIN,VSEDIN,WSEDIN,VSAMIN,VSSMIN C Along with depth, t h i s command reads i n other values necessary f o r c a l c u l a t i n g absolute p o l l e n concentrations. 13 100 FORMAT(6F7.2) 14 DEPTH(L)=DPTHIN*.01 15 EXOTIX(L)=EXTXIN 16 VOLSED(L)=VSEDIN 17 WGTSED(L)=WSEDIN 18 VOLSAM(L)=VSAMIN 19 VOLSSM(L)=VSSMIN 20 L=L+1 21 IF(L.LE.SMPLES)GO TO 1 22 2 J=J+1 23 IF(J.GT.SMPLES)GO TO 60 2 4 RV=VOLS SM(J)/VOLSAM(J) 25 TOTAL=.l 26 1=1 27 3 READ(IN,101,END=90)POLCNT 28 101 FORMAT(1F5.0) 29 POLSTR(I)=POLCNT 30 T0TAL=T0TAL+P0LSTR(I) 31 1=1+1 32 IF(I.GT.SP/100^GO TO 10 200 33 GO TO 3 34 10 S=0.0 35 ABTOT=(TOTAL*CONSTX/(EXOTIX(J)*1000.*RV*VOLSED(J))) C Calculates absolute concentration of t o t a l p o l l e n and spores. 36 ABTOTV(J)=ABTOT/10.+SP 37 K=l 38 JK=1 39 11 RP=POLSTR(JK)/EXOTIX(J) 40 ABSLT=(RP*CONSTX/(1 0000. * RV*VOLSED(J)))+S C Calculates absolute concentration of each p o l l e n and spore type. 41 ABSLTV(J,K)=ABSLT 42 K=K+1 43 ABSLTX=(ABSLT-S)*10.+S 44 IF(ABSLTX.LT.100.+S)GO TO 50 45 ABSLTX=S+100. 46 50 ABSLTV(J,K)=ABSLTX 47 K=K+1 48 JK=JK+1 49 S=S+100- 50 IF(S.GT.SP)GO TO 2 51 GO TO 11 C START OF WRITING SEQUENCE 52 60 N=l 53 61 WRITE(10,102)ABSLTV(N,M),DEPTH(N),IND 54 102 FORMAT(2F10.3,I3) \ 55 N=N+1 56 IF(N.LE.SMPLES)GO TO 61 57 62 M=M+1 58 IF (M. GT.2*SP/100)GO TO 90 59 GO TO 60 60 90 KK=1 61 94 WRITE(10,102)ABTOTV(KK),DEPTH(KK),IND 62 KK=KK+1 63 IF(KK.LE.SMPLES)GO TO 94 64 IND=1 65 STOP 66 END End of main program. For r e s t of program, see Appendix 2a. Data cards are arranged as i n Appendix 2a, except that the n cards containing depths also contain the pertinent values necessary f o r determining absolute p o l l e n concentrations. 201 Figure 51: Selected palynomorphs recovered from Burns Bog sediments. a) Type 1 (1,000X) b) Oenanthe sarmentosa (1,000X) c) Van Geel type 3 (V.G. 3) (400X) d) cf.Periconia (1,000X) e) Desmidiospora (1,000X) 202 e 1975 BURN k O O - o o o ° o CM „ TAAAA/1 VA A AAAA A A A / J A A A A A A A A A A A A A A A A A A / y . ' A A A A A A A A A A A A A A A A AA/o A A A A A A A A A > V A A A A A iT o * Radio Towers A; A A A 'S.'-Xh A A A '/A A A A A A A A A A A A A A A A A A A A A A A A A A A AA A A A A A l^rrm^^rrtr* A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A [KAAAAAAAAAAAAAAAA IKAAAAAAAAAAAAAAAA (KAAAAAAAAAAAAAAAA l l A A A A A A A / ^ A A A A A A A A A A A A A A A A A A A A A A A \ A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A / i AAA A A A A ^ A A A A A A A / ^ A A A A A ^ A A A A A A A A / n A A A A A A A M \ A A A A A A A A A A A A A A A K A % A A A A A A A A A A A A A A A  A A A A A A A A A A A A A A ^ A A A A A A A A A A A A A A A ^ A A A A A A A A A A A A A A '3^ A A A A / 3 A A A A A/ A A A A A / A A A A A A 1A A A A A A A A A A A A l A A A A A A A A A A A A A A A A A A ' A A A A A] A A A A A 1«J U A A \ A A A | A AAA ( A A A A I AAAA | A A-A A V A A A U A A \ A A A A A A A . _ _., A AAA A A A A A ,. ,„ \ A A A A A A A A A A A A mmmr\ /\AAAAAAAAAAAA Ay 0 - 0 0 l i ^ : A A A A A A A A A A A A A A A A A / 0 o ' o o .»?AA A AA AAA A A A A A A A AAA/1* „ oo ° J 'A A A A A A A A A A A A A A A A A A A / ! 0 ' A A A A A A A A A A A A A A A A A A A / 0 ° o 5 ^ A A A A A A A A A A A A A A A A A A #O O 0 /Lr A A A A A A A A A A A A/o o °>f-_- TTA AAAAAAAAAAAA 1 ^AAAAAAAAAAAAAAAA " ^« AA A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A «J« A A AS\ A A A A A A A A A A A A A A A A A A A A ' A A A A S A A A A A A A A A A A A A A A A A A A A ' AAAA AJ\ A A A A A A A A A A A A A A A A A A A A AAA A A H A AAAAAAAAAAAAAA AV"«'- A A / 1 5 o o*A A A A A A A A AAA A ' A A A / 0 f o OoVAiiAA**^ A //O f l °„ " ° -° ° „ CO? O O ° O O o o A A A A A A A / A A A A ^ r r - A A l\r A A f o o r oo A A ( o ° o > « A A . \ o oo f-_r-_r^N A A j A / o o ^b=z-£?z-z-£HHKH?£b • o°o« . o ° r_--r-__ - - r ^ . _- 70 o ° o ° ^A A A A A A \A ' A A I 5 ^ o o A. A \A \A A J o " "o o o" o oo RIDGE 3 o ob S'< oo ^ oo , O o "o i ' o oo ° oo •°--o-*o-°"b- -0 AAA' , A AA \ J A A A . , A A A A » 0 0 < \ A A A A \ A A A A - u*> . \ A A A A A A A T W V X A A A A f e V s i w v n W K s ^ A J n A B A A d A A A \ A A A A A A A A A A A A A A Wt. _° °̂ A A A A A A A ' A ™ A A A A A ( | A A / A » ' * • ' ' ' ' . A A A A A A A A A A A A A A A A A A A A A A A A A A | ! A A » A r A / \ A A A A A A A A A A A A A A A A A A A A A j ; A A * > A A A A A A A A A A A A A A A A A A I [ A A J \ , " V i > * A A A A A A A A A A A A A A / J A A A A A A A A A A A A ... - • • O'o o o oo . A - „ o o >"-*iAV\ A ° o o O X A A A A „ o « o ° o o o A A A . » n C O o 0 o 0 O 0 O ^ A A A A \ ° 0 O < o „ ° ° C o 0 0 0 0 0 o f A A A A A y o o 0 o O ' 0 . o . . 0 ° * V A A A A A / o _ o 0 0 i o o o . o ° o° °o o" o° °o o ° o ° A A A A A . A A A A X T A ^ \ S O O° I °o o° J ° 0 0 ° o ̂ T A T A A A A A . 0 ° o ^ A A A A A A A A A ^ ^ > - ^ 0 / ^ A A A oo ° / A A A A C 1 A A A A A A A A ^ S ^ A A A L ^ A A A A A A A A A A A ° - ' AJVAA^A^AAAAAAA A.AAAAAXAAAAAA A A A A • oo ° ̂  ° 0 o V A A AA/4-_-^-Vv A A A A A A A A A A A A ' " , % ° ° o o f A AA AAh_-^>A A A A A A A A A A A A o o ° o oYA A A A A AKr^TTpA A A A A A A A A A A A °o / A A A A A Af-—_-N A A A A A A A A A A A A City of Vancouver Landf i l l S i te A A A A ^ A X A A ^ A J A A A - A A A A ^ A A A A A A A A A A A A A I A A A A A A A A A A A A A A A A AW A A A A J / A A A A A A ---"^AAAAAA ^ . . A A A A A A A A A A A A A * A A A AAAAAAAAAAAAAAAAAAAA W A A A A A A A - . - . - . J A A A A A A . A A AAA AAA AAAAAAAAAAA A A A A A A A A A A A A A A A A A A AAA AA AAA AA.AA " - - J A A A A A A A A A A. A A A A A(A. A A AAAAAAAAAAAA,v A A A A A A A A A A A A A A A A A A A A AAAAAAAAAAA ^ _ - ^ _ - f A A A A A ̂  A A ACV>^_" o^J?£k AAAAAAAAAAAA.\ A A A A A A A A A A A A A A A A A A A A AAAAAAAAAAA r T _ - " * A ' A A A A A A XVKA A A A A A A A A A A A A /? A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A[r^_-\ A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A * \AAAAAAAAAAAAAAAAAAAAA/»AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA,A \A A A A A A A A A A A A A A A A A A A A A&K A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A IA A AAA A A A A A A A A AAAA AAA A «A AAAAAAAAAAA AAA AAAA A A A A A A A A A A A A - A Vi-4-A«AA A A A A A A A AAA A A AAA A/SA A AAAAAAAAA A AAA A A A A A A A A AAA ' A A A A A A A A A A A A A A A £ A A A A A A A A A A A A A A A A A A A A A A A A A /t^ A A A A A A A A A A A A A A A A / J A A A A A A A A A A A A A A A A A A A A A A A A A A T * "^AAAAAAAAAAAAAA/IAAAAAAAAAAAAAAAAAAAAAAAAAAA KA A A AAAAAAAAA A / * A AAA A A A A A A A A A A A A A A A A A A A A A A A A VAAA-A AAAAAAAAA AAA A A A A A A A A A A A A A A A A A A A A A A A A y ^•^gV\ A AAAA A AAA/*/, A A AAA AAAAAAAAA AAA A AAA AAA A A A A V. A A A A //»JA.A A /*/, A A A A A A A A A A A' A / j j & ^ W * ^ A A A A A. A A A A, " , A A A A A A>-A A A A /JV' ' S X A A A A A A ^AAAAAAAAAAA CO 0> Pond Burns H i g h w a y 499 FIGURE - 4: VEGETATION TYPES OF BURNS BOG, DELTA, B R I T I S H COLUMBIA.* HEATHLAND PINE WOODLAND BIRCH WOODLAND SPIRAEA BRUSHLAND MIXED CONIFEROUS WOODLAND SALMONBERRY BUSHLAND ALDER WOODLAND UNVEGETATED PEATLAND V e g e t a t i o n t y p e b o u n d a r y , r o a d s Bog Boundary S i n g l e q u a d r a t s Boundary o f v e g e t a t i o n d i f f e r i n g s l i g h t l y from map c a t e g o r y * * „ . , . „ . . T r a n s e c t l i n e Kanroad • •• c o n t a i n i n g q u a d r a t s T h i s map was p r e p a r e d f r o m a e r i a l p h o t o g r a p h y BC5588 f l o w n 12 J u n e , 1974 and f i e l d d a t a c o l l e c t e d i n J u n e - A u g u s t , 1975. **The l a r g e a r e a i n w e s t - c e n t r a l Burns Bog i s r e g e n e r a t i n g from d i s t u r b a n c e by p e a t m i n i n g and i s d o m i n a t e d by t h e wet (Sphagnum) s u b t y p e o f H e a t h l a n d ( c o n t a i n s few p i n e s ) . The s m a l l a r e a i n t h e c e n t e r o f t h e bog c o n t a i n s n o t i c e a b l y t a l l e r (2 - 4 m) p i n e s t h a n u s u a l l y o c c u r i n H e a t h l a n d . © 1976 R.J.Hebda and W.G.Biggs

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