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Phytocoenoses in the dry subzone of the interior western hemlock zone of British Columbia Bell, Marcus Arthur Money 1964

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PHYTOCOENOSES IN THE DRY SUBZONE OF THE INTERIOR WESTERN HEMLOCK ZONE OF BRITISH COLUMBIA by Marcus Arthur Money B e l l B.S.F., The U n i v e r s i t y of B r i t i s h Columbia, 1957 M.F. Yale U n i v e r s i t y , 1958 A THESIS SUBMITTED IN PARTIAL FULFILLMENT OF THE REQUIREMENTS FOR THE DEGREE OF Doctor of Philosophy i n the Department of Bio l o g y and Botany We accept t h i s t h e s i s as conforming to the req u i r e d standard THE UNIVERSITY OF BRITISH COLUMBIA In p r e s e n t i n g t h i s t h e s i s i n p a r t i a l f u l f i l m e n t of the requirements f o r an advanced degree at the U n i v e r s i t y of B r i t i s h Columbia, I agree 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 reference and study* I f u r t h e r agree that per-m i s s i o n f o r extensive copying of 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 granted by the Head of my Department or by h i s r e p r e s e n t a t i v e s . I t i s understood that copying or p u b l i -c a t i o n of t h i s t h e s i s f o r f i n a n c i a l gain s h a l l not be allowed without my w r i t t e n permission* Department of ^/at^oCY <^ "T^As 7 The U n i v e r s i t y of B r i t i s h Columbia, Vancouver 8, Canada Date The University of B r i t i s h Columbia FACULTY OF GRADUATE STUDIES PROGRAMME OF THE FINAL ORAL EXAMINATION FOR THE DEGREE OF DOCTOR OF PHILOSOPHY of MARC ARTHUR MONEY BELL B.S.F., The University of B r i t i s h Columbia, 19. M.F., Yale University, 1958 FRIDAY, OCTOBER 9, 1964, AT 2;00 P.M. IN ROOM 3332, BIOLOGICAL SCIENCES BUILDING COMMITTEE IN CHARGE Chairman% I. McT. Cowan J. E. Bier P. G. Haddock V. J„ Kraj ina G. E. Rouse External Examiner: C. A. Rowles W. B. Schofield G. H. N. Towers D. J . Wort R. F. Daubenmire Professor o f Botany Washington State University Pullman, Washington PHYTOCOENOSES IN THE DRY SUBZONE OF THE  INTERIOR WESTERN HEMLOCK ZONE OF BRITISH COLUMBIA ABSTRACT Five plant associations and one A l l u v i a l Complex are recognized for the Dry Subzone of the I n t e r i o r Western Hemlock Zone of B r i t i s h Columbia. These include 22 phyto-coenoses, here described as biogeocoenoses or forest types. A d d i t i o n a l l y 3 intrazonal Pinus ponderosa plant associations and 2 interzonal ecotones are discussed. In phytosociological analysis modified Zurich-Montpellier techniques are employed. For tree studies, dominance/ frequency/density (DFD) indices and standard f o r e s t r y methods are applied, Phytocoenose descriptions are based on synthesis tables which include plant l i s t s ( t o t a l 538 species), habitat descriptions and tree growth data from 15.5 o n e - f i f t h acre plots. Forest types comprise: 1) Lichen a s s o c i a t i o n (Cladonietum) - open stands with Pseudotsuga menziesii as the edaphic climax dominant, occurring on xeric rock outcrops; 2) Moss assoc i a t i o n (Pachistimeto-Callier^gonelletum) - closed stands with Tsuga heterophylla as the c l i m a t i c climax dominant, occuring on me sic s i t e s ; t h i s includes 6 forest types; 3) A r a l i a Oakfern association ( A r a l i e t o -Gymnocarpietum) - closed stands with Tsuga heterophylla, Thuja p l i c a t a as the edaphic climax codominants, occuring on moist s i t e s ; t h i s includes 7 forest types; 4) Devil's Club association (Oplopanacetum) - closed stands with Thuja p l i c a t a as the edaphic climax dominant, occurring on wet s i t e s ; t h i s includes 4 forest types; 5) Skunk Cabbage asso c i a t i o n (Lysichitetum) - open stands with Thuja p l i c a t a as the edaphic climax dominant, occurring on water-saturated ground; t h i s includes 2 forest types; 6) A l l u v i a l Complex - unstable r i v e r s i d e vegetation dominated by Populus trichocarpa. The Lichen, Skunk Cabbage and A l l u v i a l Complex communities are f l o r i s t i c a l l y the most c l e a r l y defined, and are r e a d i l y recognizable on the basis of lesser vegetation dominants alone. Recognition of mesic communities r e l i e s on a c h a r a c t e r i s t i c combination of species. The zonal (climatic climax) biogeocoenose i s the Slope Normal Moss forest type of the Moss Association. The dynamic r e l a t i o n s h i p s of forest types are discussed. Secondary succession may go from the deforested stage d i r e c t l y to the climax, i f edaphotope disturbance i s minimal, but normally a pioneer-tree stage intervenes. This Subzone i s unique in that, the pioneer stage of the zonal community may 'differ s u b s t a n t i a l l y from the cl i m a t i c climax i f humus i s removed by f i r e . On mesic s i t e s , proceeding from pioneer-conifer to climax stages, crown cover decreases and lesser vegetation increases. Tsuga heterophylla i s the exclusive dominant of the climax forest„ In decreasing order of importance, as determined by DFD indices, Subzone trees are Tsuga heterophylla, Thuja  p l i c a t a . Pinus monticola, Pseudotsuga menziesii, Betula  papyrifera, Picea engelmannii, Lar i x occidental i s , Populus tremuloides, Pinus contorta, Populus trichocarpa. Abies lasiocarpa and Abies grandis. Most rapid tree height growth of Thuja p l i c a t a , Pseudotsuga menziesii, Pinus monticola and Picea engel-mannii occurs i n Devil's Club communities; of Tsuga heterophylla, L a r i x o c c i d e n t a l i s , Pinus contorta, Betula  papyrifera, Populus tremuloides i n A r a l i a Oakfern communities; and of Populus trichocarpa i n A l l u v i a l Complexes. Forest types are more productive i n pioneer than i n climax stages. Estimates of net primary productivity and standing crop of fo r e s t types for tree trunks of a l l tree species summed as one, showed that the greatest pioneer- conifer stand p r o d u c t i v i t y (1251 kilogram/ hectare/year) and climax stand standing crop (180 x 10^ kg/ha) belong to the Devil's Club association, and the least productive (126 kg/ha/yr) and lowest standing crop (15 x 10^ kg/ha) to the Lichen association. I t i s concluded that biogeocoenotic c l a s s i f i c a t i o n provides a sound basis for land use planning i n t h i s region, and should be applicable to other areas, PUBLICATION 1959 Forest C l a s s i f i c a t i o n s of B r i t i s h Columbia. In Forestry Handbook for B r i t i s h Columbia, 2nd ed., pp. 572-616. Forest Club, University of B r i t i s h Columbia, GRADUATE STUDIES F i e l d of Study: Botany Forest Autfecology Forest Synecology Bryology Advanced Plant Taxonomy Plant Phylogenet.ics Plant Physiology V. J. Krajina V. J. Krajina V. J„ Krajina T. M. G. Taylor •G. E„ Rouse D„ J. Wort Other Studies: Forest Research Methods J. H. G„ Smith S o i l Genesis, and C l a s s i f i c a t i o n C„ A. Rowles Soil-Pl a n t Relationships J. D. Beaton Forestry Graduate Seminar Forestry Faculty i i from Upper Arrow Lake. near Nakusp " - - - a most sublime view - - - w i t h l o f t y snowy peaks i n a l l d i r e c t i o n s . Contrasted w i t h t h e i r dark shady bases densely covered w i t h P i n e , the deep r i c h hue of Pinus canadensis (Tsuga h e t e r o p h y l l a ) w i t h i t s feathery cloudy branches q u i v e r i n g i n the breeze, and the l i g h t t i n t s but more m a j e s t i c height of Pinus strobus (Pinus monticola) e x a l t i n g t h e i r l o f t y tops beyond any other tree of the f o r e s t , imparts an i n d e s c r i b a b l e beauty to the scene." From the Jo u r n a l kept by David Douglas During His T r a v e l s i n North America, 1823-1827 (page 250). W i l l i a m Wesley and Son. London. (parentheses my own). i i i ABSTRACT F i v e p l a n t a s s o c i a t i o n s and one A l l u v i a l Complex are recognized f o r the Dry Subzone of the I n t e r i o r Western Hemlock Zone of B r i t i s h Columbia. These i n c l u d e 22 phytocoenoses, here described as biogeocoenoses or f o r e s t types. A d d i t i o n a l l y 3 i n t r a z o n a l Pinus ponderosa p l a n t a s s o c i a t i o n s and 2 i n t e r z o n a l ecotones are discussed. In p h y t o s o c i o l o g i c a l a n a l y s i s modified Z u r i c h - M o n t p e l l i e r techniques are employed. For t r e e s t u d i e s , dominance/ frequency/density (DFD) i n d i c e s and standard f o r e s t r y methods are a p p l i e d . Phytocoenose d e s c r i p t i o n s are based on s y n t h e s i s t a b l e s which i n c l u d e p l a n t l i s t s ( t o t a l 538 s p e c i e s ) , h a b i t a t d e s c r i p t i o n s and t r e e growth data from 155 o n e - f i f t h acre p l o t s . Forest types comprise: 1) Lichen a s s o c i a t i o n (Cladonie-tum) - open stands w i t h Pseudotsuga m e n z i e s i i as the edaphic climax dominant, o c c u r r i n g on x e r i c rock outcrops; 2) Moss a s s o c i a t i o n (Pachi s time to-Ca11i er-gonelletum) - c l o s e d stands w i t h Tsuga h e t e r o p h y l l a as the c l i m a t i c climax dominant, o c c u r r i n g on mesic s i t e s ; t h i s i n c l u d e s 6 f o r e s t types; 3) A r a l i a Oakfern a s s o c i a t i o n (Aralieto-Gymnocarpietum) - c l o s e d stands w i t h Tsuga  h e t e r o p h y l l a . Thuja p l i c a t a as the edaphic climax codominants, o c c u r r i n g on moist s i t e s ; t h i s i n c l u d e s 7 f o r e s t types; 4) D e v i l ' s Club a s s o c i a t i o n (Oplopanacetum) - c l o s e d stands with Thuja p l i c a t a as the edaphic climax dominant, o c c u r r i n g on wet s i t e s ; t h i s i n c l u d e s 4 f o r e s t types; 5) Skunk Cabbage a s s o c i a t i o n (Lysichitetum) - open stands w i t h Thuja p l i c a t a as the edaphic climax dominant, o c c u r r i n g on water-saturated ground; t h i s i n c l u d e s 2 f o r e s t types; 6) A l l u v i a l Complex - unstable r i v e r s i d e v e g e t a t i o n dominated by Populus  t r i c h o c a r p a . The L i c h e n , Skunk Cabbage and A l l u v i a l Complex communities are f l o r i s t i c a l l y the most c l e a r l y d e f i n e d , and are r e a d i l y recognizable on the b a s i s of l e s s e r v e g e t a t i o n dominants alone. Recognition of mesic communi-t i e s r e l i e s on a c h a r a c t e r i s t i c combination of s p e c i e s . i v The zonal ( c l i m a t i c climax)biogeocoenose i s the Slope Normal Moss f o r e s t type of the Moss a s s o c i a t i o n . The dynamic r e l a t i o n s h i p s of f o r e s t types are discussed. Secondary succession may go from the deforested stage d i r e c t l y to the clim a x , i f edaphotope disturbance i s minimal, but normally a pioneer-tree stage i n t e r v e n e s . This Subzone i s unique i n that the pioneer stage of the zonal community may d i f f e r s u b s t a n t i a l l y from the c l i m a t i c climax i f humus i s removed by f i r e . On mesic s i t e s , proceeding from pioneer-cOnifer to climax stages, crown cover decreases and l e s s e r v e g e t a t i o n i n c r e a s e s . Tsuga  h e t e r o p h y l l a i s the e x c l u s i v e dominant of the climax f o r e s t . In decreasing order of importance, as determined by DFD i n d i c e s , Subzone trees are Tsuga h e t e r o p h y l l a . Thuja p l i c a t a . Pinus m o n t i c o l a . Pseudotsuga  m e n z i e s i i . Betula p a p y r i f e r a . P i c e a engelmannii. L a r i x o c c i d e n t a l i s . Populus  tremuloides. Pinus c o n t o r t a . Populus t r i c h o c a r p a . Abies l a s i o c a r p a and Abies grandis. Most r a p i d tree height growth of Thuja p l i c a t a . Pseudotsuga m e n z i e s i i . Pinus monticola and P i c e a engelmannii occurs i n D e v i l ' s Club communities; of Tsuga h e t e r o p h y l l a . L a r i x o c c i d e n t a l i s . Pinus c o n t o r t a . B e t u l a p a p y r i f e r a . Populus tremuloides i n A r a l i a Oakfern communities; and of Populus t r i c h o c a r p a i n A l l u v i a l Complexes. F o r e s t types are more productive i n pioneer than i n climax stages. E s t i -mates of net primary p r o d u c t i v i t y and standing crop of f o r e s t types f o r tree trunks of a l l t r e e species summed as one, showed t h a t the great e s t pioneer-c o n i f e r stand p r o d u c t i v i t y (1251 kilogram/hectare/year) and climax stand 3 standing crop (180 x 10 kg/ha) belong to the D e v i l ' s Club a s s o c i a t i o n , and 3 the l e a s t productive (126 kg/ha/yr) and lowest standing crop (15 x 10 kg/ha) to the Lichen a s s o c i a t i o n . I t i s concluded t h a t biogeocoenotic c l a s s i f i c a t i o n provides a sound b a s i s f o r land use planning i n t h i s r e g i o n , and should be a p p l i c a b l e to other areas. V CONTENTS Page ACKNOWLEDGEMENT INTRODUCTION 1 C l a s s i f i c a t i o n and Land Use 1 Ecosystem C l a s s i f i c a t i o n i n B r i t i s h Columbia 3 DESCRIPTION OF THE STUDY AREA 6 METHOD 11 S o c i o l o g i c a l A n a l y s i s 11 P l a n t c o l l e c t i o n and photographic record 12 S o c i o l o g i c a l s y n t h e s i s 12 Synthesis t a b l e s - p l a n t a s s o c i a t i o n s 12 Forest types 13 Secondary succession stages . . . . . . . . . . 1 4 C h a r a c t e r i s t i c combination of species 14 L i f e form 16 Fore s t trees 16 RESULTS 18 Lichen a s s o c i a t i o n 19 Moss a s s o c i a t i o n 25 Slope Normal Moss f o r e s t type . . 28 Slope Dry Moss f o r e s t type . . 34 Slope Bunchberry Moss f o r e s t type 36 Slope Bunchberry Moss, southern v a r i a n t , f o r e s t type . . 40 A l l u v i a l Normal Moss f o r e s t type . 41 A l l u v i a l Dry Moss f o r e s t type 45 A r a l i a Oakfern a s s o c i a t i o n . . 47 Slope A r a l i a Oakfern f o r e s t type . 5 1 Slope A r a l i a Oakfern, pioneer hardwood v a r i a n t , f o r e s t type 56 v i Page Slope A r a l i a Oakfern, southern v a r i a n t , f o r e s t type . . . 58 Degraded A r a l i a Oakfern f o r e s t type 61 Degraded A r a l i a Oakfern, northern v a r i a n t , f o r e s t type . 63 A l l u v i a l A r a l i a Oakfern f o r e s t type 65 A l l u v i a l Bunchberry A r a l i a Oakfern f o r e s t type 69 D e v i l ' s Club a s s o c i a t i o n 70 Slope D e v i l ' s Club f o r e s t type 75 Slope D e v i l ' s Club, northern v a r i a n t , f o r e s t type . . . . 79 Tufa D e v i l ' s Club f o r e s t type 80 A l l u v i a l D e v i l ' s Club f o r e s t type 84 Skunk Cabbage A s s o c i a t i o n . . . . . 86 Creek Skunk Cabbage f o r e s t type 90 Depression Skunk Cabbage f o r e s t type 94 A l l u v i a l Complex 96 Wet A l l u v i a l Complex 98 Dry A l l u v i a l Complex 101 I n t r a z o n a l and Ecotone Communities . . 103 I n t r a z o n a l Ponderosa pine communities . . . . . 104 Pinus ponderosa - Agropyron spicatum a s s o c i a t i o n . . . . 105 Pseudotsuga m e n z i e s i i - A r c t o s t a p h y l o s u v a - u r s i Calamagrostis rubescens a s s o c i a t i o n 106 Pseudotsuga m e n z i e s i i - Calamagrostis rubescens a s s o c i a t i o n 108 D o u g l a s - f i r Zone / Hemlock Zone Ecotone I l l Pseudotsuga m e n z i e s i i - Arctostaphylos u v a - u r s i -Calamagrostis rubescens / Moss ecotone I l l Pseudotsuga m e n z i e s i i - Tsuga h e t e r o p h y l l a - Smilacina s t e l l a t a / A l l u v i a l A r a l i a Oakfern ecotone 113 v i i Page DISCUSSION 117 The zonal community 117 Zonal c h a r a c t e r i s t i c combination of species 117 Constant species composition 118 Dynamics of f o r e s t types 120 Primary succession 120 Secondary succession 122 Change i n t r e e composition 123 Change i n l e s s e r v e g e t a t i o n 125 Change i n bryophytes on decaying wood 126 R e l a t i o n s h i p of l e s s e r v e g e t a t i o n cover and t r e e d e n s i t y . . 126 Importance of trees i n f o r e s t types 128 P r o d u c t i v i t y of f o r e s t types 133 SUMMARY AND CONCLUSIONS 138 LITERATURE CITED 146 APENDICES A C h e c k l i s t of p l a n t s 155 B Table of constant species 168 C Forest Inventory Summary and DFD values 173 D Tree growth and p r o d u c t i v i t y of f o r e s t types 183 E L i s t of f o r e s t types; numerical l i s t of stands 196 F Methods - a d e t a i l e d account; s y n t h e s i s t a b l e s ; toposequence diagrams . . . . . . . . . . 204 v i i i Tables Table Page 1 Lichen a s s o c i a t i o n : c h a r a c t e r i s t i c combination of species . . 23 2 Lichen a s s o c i a t i o n : tree data summary 25 3 Moss a s s o c i a t i o n : c h a r a c t e r i s t i c combination of species . . . 26 4 Slope Normal Moss f o r e s t type: t r e e data summary 33 5 Slope Dry Moss f o r e s t type: tre e data summary 35 6 Slope Bunchberry Moss f o r e s t type: tre e data summary 38 7 Slope Bunchberry Moss, southern v a r i a n t , f o r e s t type: t r e e data summary 41 8 A l l u v i a l Normal Moss f o r e s t type: t r e e data summary 43 9 A l l u v i a l Dry Moss f o r e s t type: tre e data summary . . . . . . . 46 10 A r a l i a Oakfern a s s o c i a t i o n : C h a r a c t e r i s t i c combination of species . . . . . 49 11 Slope A r a l i a Oakfern f o r e s t type: tree data summary 56 12 Slope A r a l i a Oakfern, pioneer hardwood v a r i a n t , f o r e s t type: tree data summary 58 13 Slope A r a l i a Oakfern, southern v a r i a n t , f o r e s t type: t r e e data summary 60 14 Degraded A r a l i a Oakfern f o r e s t type: tree data summary . . . . 63 15 Degraded A r a l i a Oakfern, northern v a r i a n t , f o r e s t type: t r e e data summary 64 16 A l l u v i a l A r a l i a Oakfern f o r e s t type: tre e data summary . . . . 67 17 A l l u v i a l Bunchberry A r a l i a Oakfern f o r e s t type: tre e data summary 70 18 D e v i l ' s Club a s s o c i a t i o n : c h a r a c t e r i s t i c combination of species 73 19 Slope D e v i l ' s Club f o r e s t type; tre e data summary 78 i x Tables (cont'd.) Page 20 Slope D e v i l ' s Club.northern v a r i a n t , f o r e s t type: tr e e data summary 80 21 Tufa D e v i l ' s Club f o r e s t type: tr e e data summary 83 22 A l l u v i a l D e v i l ' s Club f o r e s t type: tr e e data summary . . . . 86 23 Skunk Cabbage a s s o c i a t i o n : c h a r a c t e r i s t i c combination of species 88 24 Creek Skunk Cabbage f o r e s t type: tree data summary . . . . . 93 25 Depression Skunk Cabbage f o r e s t type: tree data summary . . 95 26 A l l u v i a l Complex: c h a r a c t e r i s t i c combination of species . . 96 27 Wet A l l u v i a l Complex: tree data summary 101 28 Dry A l l u v i a l Complex: t r e e data summary 103 29 Pinus ponderosa - Agropftyron spicatum a s s o c i a t i o n : t r e e data summary 106 30 Pseudotsuga m e n z i e s i i - A r c t o s t a p h y l o s u v a - u r s i -Calamagrostis rubescens a s s o c i a t i o n : tree data summary . . . 108 31 Pseudotsuga m e n z i e s i i - Calamagrostis rubescens a s s o c i a t i o n tree data summary 110 32 Pseudotsuga m e n z i e s i i - A r c t o s t a p h y l o s u v a - u r s i -Calamagrostis rubescens / Moss ecotone: tr e e data summary. . 113 33 Pseudotsuga m e n z i e s i i - Tsuga h e t e r o p h y l l a - Sm i l a c i n a  s t e l l a t a / A l l u v i a l A r a l i a Oakfern ecotone: tr e e data summary 116 34 DFD values f o r s e l e c t e d trees i n stage 1 (climax) of a l l p l a n t a s s o c i a t i o n s 124 35 Average l a y e r coverage i n the D e v i l ' s Club a s s o c i a t i o n . . . 128 36 Height growth of pioneer c o n i f e r s at 50 years 136 X I l l u s t r a t i o n s F i g u r e F o l l o w i n g page 1 Map of study area showing g l a c i e r s and 4000 f o o t contour . . . . 6 2 Looking north on Slooan Lake. Steep f o r e s t e d slopes to waters edge preclude lowland farming 7 3 Snow s l i d e roads on f o r e s t e d slope above Trout Lake 7 4 Farmland near Nakusp , 8 5 Rugged h i g h country of S e l k i r k mountains (over 9000 f e e t ) near Trout Lake 9 6 Broad f o r e s t e d a l l u v i a l t e r r a c e (Makinson f l a t s ) i n Mosquito V a l l e y n o r t h of Arrow Park 9 7 Constancy diagram f o r Lichen a s s o c i a t i o n 20 8 Lichen a s s o c i a t i o n : a) average cover of constant dominant s p e c i e s ; b) v e g e t a t i o n l i f e form spectrum 20 9 Open Li c h e n a s s o c i a t i o n stand on rock outcrop 21 10 C l o s e r view of Lichen a s s o c i a t i o n 21 11 Constancy diagram f o r Moss a s s o c i a t i o n 28 12 Moss a s s o c i a t i o n : a) average cover of constant dominant s p e c i e s ; b) v e g e t a t i o n l i f e form spectrum 28 13 C l i m a t i c c l i m a x Slope Normal Moss f o r e s t type 30 14 Dense immature SNM stand 30 15 Mature Slope Dry Moss stand 34 16 Climax Slope Bunchberry Moss stand 37 17 Ground v e g e t a t i o n i n c l i m a x SBM stand 37 18 Dense young stand of Tsuga h e t e r o p h y l l a on nudum ANM s i t e . . . 42 19 Climax A l l u v i a l Normal Moss stand 42 20 Constancy diagram f o r A r a l i a Oakfern a s s o c i a t i o n 50 21 A r a l i a Oakfern a s s o c i a t i o n : a) average cover of constant dominant s p e c i e s ; b) v e g e t a t i o n l i f e form spectrum . . 50 x i I l l u s t r a t i o n s (cont'd.) F i g u r e F o l l o w i n g paj 22 85 year o l d SAO stand dominated by vigorous Pinus monticola . . 52 23 Ground v e g e t a t i o n i n young SAO stand . . . . . 52 24 Ground v e g e t a t i o n i n climax SAO stand 54 25 Young SAOp stand showing vigorous Populus tremuloides . . . . 56 26 Ground v e g e t a t i o n i n DAO stand 61 27 Mature AAO stand on a l l u v i a l outwash 65 28 Ground v e g e t a t i o n beneath young AAO stand . 66 29 Dense Epilobium a n g u s t i f o l i u m and Rubus p a r v i f l o r o u s on an AAO s i t e a f t e r l o g g i n g and burning 66 30 Mature ABAO stand on coarse outwash p l a i n 69 31 Ground v e g e t a t i o n i n clim a x ABAO 69 32 Constancy diagram f o r D e v i l ' s Club a s s o c i a t i o n 75 33 D e v i l ' s Club a s s o c i a t i o n : a) average cover of constant dominant s p e c i e s ; b) v e g e t a t i o n l i f e form spectrum 75 34 D e v i l ' s Club a s s o c i a t i o n 76 35 Ground v e g e t a t i o n i n D e v i l ' s Club stand 76 36 Thick t u f a deposit exposed by road cut near Trout Lake . . . . 81 37 Edaphic climax A l l u v i a l D e v i l ' s Club stand of vigorous Thuja p l i c a t a 84 38 Vigorous Oplopanax h o r r i d u s grows over 10 f t . high i n some AD stands 85 39 Ground v e g e t a t i o n on bank of small stream i n AD stand . . . . 85 40 Constancy diagram f o r Skunk Cabbage a s s o c i a t i o n 90 41 Skunk Cabbage a s s o c i a t i o n : a) average cover of constant dominant s p e c i e s ; b) v e g e t a t i o n l i f e form spectrum 90 42 Tsuga h e t e r o p h y l l a . Pinus m o n t i c o l a . and Pseudotsugs m e n z i e s i i growing on r a i s e d ground i n CSC stand . . . . . 91 x i i I l l u s t r a t i o n s (cont'd) F i g u r e F o l l o w i n g page 43 Ground v e g e t a t i o n i n CSC stand 91 44 Edaphic climax Depression Skunk Cabbage stand 94 45 Constancy diagram f o r A l l u v i a l Complex 98 46 A l l u v i a l Complex: a) average cover of constant dominant s p e c i e s ; b) ve g e t a t i o n l i f e form spectrum 98 47 Wet A l l u v i a l Com p l e x stands on s i l t y f l o o d p l a i n of Lardeau R i v e r 99 48 S c a t t e r e d Pinus ponderosa stands on rocky s o u t h - f a c i n g slopes across Columbia R i v e r from Burton 104 49 P a r k l i k e A-C a s s o c i a t i o n on r i d g e above Burton 106 50 The S/AAO ecotone stand, SB 173, near Salmo 113 51 Microcommunity i n S/AAO stand 113 52 Cover graphs of a l l constant species showing dominance (cover) i n each p l a n t a s s o c i a t i o n 119 53 D i a g n o s t i c c h a r t of s e l e c t e d constant dominant species 120 54 Diagram showing dynamic r e l a t i o n s h i p of f o r e s t types: primary succession to c l i m a t i c climax Slope Normal Moss community 121 55 I d e a l i z e d toposequences showing f o r e s t types on slopes . . . . 122 56 I d e a l i z e d toposequences showing f o r e s t types on a l l u v i a l f l a t s 122 57 Summary l a y e r coverage diagrams of stages i n a l l p l a n t a s s o c i a t i o n s . . . . . . 123 58 V a r i a t i o n i n tree composition i n the Moss a s s o c i a t i o n during secondary succession from bare land t o climax 124 59 V a r i a t i o n i n cover of some l e s s e r v e g e t a t i o n i n the Moss a s s o c i a t i o n d u ring secondary succession . 125 x i i i I l l u s t r a t i o n s (cont'd.) F i g u r e F o l l o w i n g page 60 V a r i a t i o n , i n the Moss a s s o c i a t i o n of: a) cover of decaying wood, and t o t a l bryophyte and l i c h e n cover on decaying wood; and b) some bryophytes c o n t r i b u t i n g to trend i n a) 126 61 Influence of dense pioneer c o n i f e r stands on cover of s e l e c t e d l e s s e r v e g e t a t i o n species i n the Moss a s s o c i a t i o n . . . 127 62 Curves of l a y e r coverage and b a s a l area i n the Moss a s s o c i a t i o n 128 63 Histograms showing r e l a t i v e importance of a l l t r e e s i n f o r e s t types 129 64 Summary height-age curves f o r f o r e s t types. Based on s t a n d averages of a l l dominants and codominants 132 65 Net primary p r o d u c t i v i t y of t r e e stems i n f o r e s t types 134 66 Average standing crop of l i v i n g t r e e stems i n climax stands of each f o r e s t type 135 67 Completed h a b i t a t data sheet 205 68 P o r t i o n s of completed v e g e t a t i o n a n l a y s i s sheets 208 69 Sample tree t a l l y sheet 208 70 Completed tre e measurement sheet 208 71 Sample stand and b a s a l area t a b l e 213 x i v ACKNOWLEDGEMENT I am indebted to Dr. V. J . K r a j i n a , Department of Bi o l o g y and Botany, U n i v e r s i t y of B r i t i s h Columbia, f o r h i s guidance throughout the research and f o r the considerable time he gave i n the e a r l y stages of f i e l d work; to Dr. R. G. McMinn, Canada Department of F o r e s t r y fbr o r i g i n a l f i e l d d a t a , a s s i s t a n c e , and f o r numerous h e l p f u l d i s c u s s i o n s ; and to Dr. W. B. S c h o f i e l d , Department of B i o l o g y and Botany, U n i v e r s i t y of B r i t i s h Columbia, f o r c o n s t r u c t i v e c r i t i c i s m s and suggestions i n the pr e p a r a t i o n of t h i s t h e s i s . A p p r e c i a t i o n i s expressed f o r the a s s i s t a n c e provided by personnel of the B.C. Fo r e s t S e r v i c e and timber companies of the Nelson and Kan loops F o r e s t D i s t r i c t s , and f o r the use of f a c i l i t i e s i n the Department of Bio l o g y and Botany, U n i v e r s i t y of B r i t i s h Columbia, and the Department of B i o l o g y , U n i v e r s i t y of V i c t o r i a . I am g r a t e f u l f o r the help of many s p e c i a l i s t s who v o l u n t a r i l y gave t h e i r time to i d e n t i f i c a t i o n of p l a n t c o l l e c t i o n s . Mr. F. M. Boas, V i c t o r i a , i d e n t i f i e d over 1500 bryophytes. Dr. Grace Howard, U n i v e r s i t y of Washington, i d e n t i f i e d most of the l i c h e n s . Dr. W. B. S c h o f i e l d , U n i v e r s i t y of B r i t i s h Columbia, Dr. E l v a Lawton, U n i v e r s i t y of Washington, and Dr. A h t i , H e l s i n k i , helped w i t h taxonomically d i f f i c u l t cryptogams. Dr. V. J . K r a j i n a , Dr. T. M. C. T a y l o r , and Mr. J . W. Eastham advised on d i f f i c u l t v a s c u l a r p l a n t s . F i n a n c i a l support, given by the f o l l o w i n g agencies, i s g r a t e f u l l y acknowledged: E. M. R. Grant 98, Canada Department of F o r e s t r y ; the N a t i o n a l Research C o u n c i l of Canada; and the U n i v e r s i t y of V i c t o r i a F a c u l t y Research Fund. To Dr. R. B. Smith, Canada Department of F o r e s t r y , whose bearded jowls appearing over the edge of the i n e v i t a b l e s o i l p i t earned him the a p p e l l a t i o n " G r i z z l y of the Monashee", I wish to express my si n c e r e thanks f o r companionship, cooperation, and u s e f u l d i s c u s s i o n i n a l l phases of the work. F i e l d work was brightened by the c h e e r f u l a s s i s t a n c e of Mr. R. W. Haigh. Of the many i n d i v i d u a l s who helped i n p r e p a r a t i o n of the manu-s c r i p t , I should l i k e to thank p a r t i c u l a r l y Mrs. P. C. Townsend, Miss E n i d Lemon and Miss E l i z a b e t h Swemle. The l o v i n g help and encouragement of my w i f e i n every aspect of the study i s deeply appr e c i a t e d . Without her a s s i s t a n c e much of the work would not have been completed. I share w i t h her the s a t i s f a c t i o n of p r e s e n t i n g the r e s u l t s i n t h e i r f i n a l form. INTRODUCTION 1. The need f o r c o r r e l a t i n g t r e e diseases w i t h e c o l o g i c s i t e c o n d i t i o n s l e d to an e c o l o g i c a l study of the Dry Subzone of the I n t e r i o r Western Hemlock Zone of B r i t i s h Columbia. Under the auspices of the Forest Biology Laboratory of the Canada Department of A g r i c u l t u r e , Dr. V.J. K r a j i n a of the U n i v e r s i t y of B r i t i s h Columbia, d i r e c t e d the research of R.B. Smith and myself. Work was d i v i d e d g e n e r a l l y i n t o two areas, 1) s t u d i e s of edaphotopes, undertaken by Smith (1963), and 2) s t u d i e s of v e g e t a t i o n i n c l u d i n g d e t a i l e d t r e e mensurational a n a l y s i s which I undertook. The purpose of t h i s t h e s i s i s to d escribe f o r e s t phytocoenoses i n the Subzone, and to i n c l u d e these phytocoenoses i n a c l a s s i f i c a t i o n of r e a d i l y r e cognizable ecosystematic u n i t s . Vegetation dynamics and t r e e p r o d u c t i v i t y are a l s o considered. The l i t e r a t u r e d e a l i n g w i t h the h i s t o r y of e c o l o g i c a l c l a s s i f i c a t i o n of n a t u r a l communities i s massive, and has been summarized r e c e n t l y by Becking (1957), Hanson (1958), and Whittaker (1962). E x c e l l e n t summaries of f o r e s t e c o l o g i c a l c l a s s i f i c a t i o n i n the P a c i f i c Northwest have been given by Becking (1954), Brayshaw (1954), Mueller-dombois (1959), and Smith (1963). C l a s s i f i c a t i o n and land use The h i s t o r y of science shows t h a t , g e n e r a l l y speaking, f i r s t steps i n any new f i e l d are d e s c r i p t i v e , and i n most cases a s s o c i a t e d very soon w i t h c l a s s i f i c a t i o n of media i n t o workable u n i t s . The mere " n a t u r a l " these u n i t s a r e , i . e . , the broader the base f o r t h e i r arrangement i n c l a s s e s , the b e t t e r the c l a s s i f i c a t i o n w i l l be. From such i n i t i a l c l a s s i f i c a t i o n f o l l o w s o b j e c t i v e a n a l y s i s , and from t h i s p o s s i b l y a r e a l i g n i n g of the groups p r e v i o u s l y c l a s s i f i e d . Formation of hypotheses on the nature of the media might then f o l l o w , and these hypotheses would be t e s t e d by f u r t h e r observ-a t i o n and e v e n t u a l l y by c o n t r o l l e d experiment. And so i t goes, becoming more and more o b j e c t i v e as knowledge i n c r e a s e s . Withrthe recent tremendous s t r i d e s i n o b j e c t i v e a n a l y s i s through bio-m e t r i c s and mathematics there i s o f t e n a s s o c i a t e d a d i s d a i n f o r the elem-entary and o f t e n tedious phase of s u b j e c t i v e d e s c r i p t i o n and c l a s s i f i c a t i o n . Yet i n ecology t h i s phase i s e s s e n t i a l to the proper s e q u e n t i a l development of the science (Poore, 1962). Poore p o i n t s out that o b j e c t i v e computational procedures f o r primary v e g e t a t i o n a l surveys, as f o r example the f a c t o r and gradient a n a l y s i s of Goodall (1953, 1954), and Hughes & L i n d l e y (1955) are inadequate f o r i n i t i a l c l a s s i f i c a t i o n . Such procedures may i n f a c t obscure v a r i a t i o n s , the causes of which would be p l a i n i n any d e t a i l e d s u b j e c t i v e f i e l d survey. I t should be evident then, that o r d e r l y a c q u i s i t i o n of knowledge g e n e r a l l y r e q u i r e s that 1) the f i r s t steps be e s s e n t i a l l y d e s c r i p t i v e and t h a t 2) d e s c r i p t i o n be immediately followed by arrangement of the described m a t e r i a l i n c l a s s e s , i . e . c l a s s i f i c a t i o n , from which g e n e r a l i z a t i o n s may be made. Without these two f i r s t steps science wallows. Indeed, without c l a s s i f i c a t i o n , there can be no science. To deny the need f o r t h i s most e s s e n t i a l f i r s t step i s to deny that " c l a s s i f i c a t i o n i s a fundamental pre-r e q u i s i t e of a l l conceptual thought" (Gilmour, 1951), yet r e c e n t l y prominent s c i e n t i s t s continued to maintain that c l a s s i f i c a t i o n of v e g e t a t i o n i n recognizable u n i t s i s not necessary (Bray and C u r t i s , 1957) nor r e a l i s t i c (Gleason, 1926). However u n a t t r a c t i v e c l a s s i f i c a t i o n may appear, or however 3. s u p e r f i c i a l l y unnecessary to meet a p a r t i c u l a r need, i n i t i a l c l a s s i f i c a t i o n of media i n any new d i s c i p l i n e i s v i t a l . Land use planning i s no exception. I n c r e a s i n g pressures f o r m u l t i p l e land use r e s u l t i n g from i n c r e a s i n g p o p u l a t i o n and r a p i d u r b a n i z a t i o n of l a r g e areas near i n d u s t r i a l centers make d e s c r i p t i o n and c l a s s i f i c a t i o n of remaining n a t u r a l areas of paramount importance. A sound base could be provided f o r land use planning i n a c l a s s i f i c a t i o n embodying as many n a t u r a l c h a r a c t e r i s t i c s of the landscape as p o s s i b l e . In North America l i t t l e has been done i n t h i s regard. To meet the need concerted e f f o r t s should soon be made to d e s c r i b e , catalogue, and map the n a t u r a l ecosystems before many more are destroyed by unwise use w i t h a l l i t s attendant and sometimes i n c u r a b l e i l l s . S u i t a b l e means f o r a c h i e v i n g t h i s goal may l i e i n the e v o l v i n g " n a t u r a l " e c o l o g i c a l c l a s s i f i c a t i o n systems based on combined concepts of t o t a l environment and t o t a l b i o t a (ecosystem, Tansley, 1936; biogeocoenosis, Sukachev, 1944; holocoen, F r i e d -e r i c h s , 1930; s y n t h e s i s of these views, K r a j i n a , 1960). Although methods may d i f f e r , these concepts are fundamentally s i m i l a r , and, i n terms of c l a s s i f i c a t i o n , the ends are the same, i . e . d e s c r i p t i o n and c l a s s i f i c a t i o n of ecosystems i n schemes that c l a r i f y r e l a t i o n s h i p s and e x p l a i n v a r i a t i o n . Ecosystem c l a s s i f i c a t i o n i n B r i t i s h Columbia In B r i t i s h Columbia much has been accomplished i n c l a s s i f i c a t i o n of t e r r e s t r i a l ecosystems w i t h i n B i o g e o c l i m a t i c Zones, which i n turn belong to l a r g e r B i o g e o c l i m a t i c Regions ( K r a j i n a 1964). Environmental and c l i m a t i c data f o r the Zones has been summarized by K r a j i n a (1959, 1964). D e s c r i p t i o n and c l a s s i f i c a t i o n of the v e g e t a t i o n / h a b i t a t complexes (biogeocoenoses = ecosystem types = f o r e s t types, as used i n t h i s t h e s i s ) w i t h i n a number of these Zones has been e f f e c t e d by K r a j i n a (1952, 1953, 1954), K r a j i n a and S p i l s b u r y (1953), Brayshaw (1955), A r l i d g e (1956), Mueller-dombois (1959), Lesko (1961), O r l o c i (1961, 1964), Smith (1963), Peterson (1964), Brooke (1964). A s s o c i a t e d s t u d i e s have been those of O g i l v i e (1953, 1955) and McMinn (I960) on s o i l s , and of E i s (1961) on r e l a t i o n s h i p s of a number of environmental v a r i a b l e s to c e r t a i n features of the v e g e t a t i o n . The b a s i s f o r most of these c l a s s i f i c a t i o n s has been the p l a n t a s s o c i a t i o n as defined by K r a j i n a (1960): A p l a n t ( f o r e s t ) a s s o c i a t i o n i s a d e f i n i t e uniform (homogeneous) phytocoenosis that i s i n dynamic e q u i l i b r i u m w i t h a c e r t a i n complex of environmental f a c t o r s (ecotope); i t s f l o r i s t i c s t r u c t u r e — i . e . , s t r a t i f i c a t i o n ( l a y e r i n g ) , species s i g n i f i c a n c e ( A r t m S c h t i g k e i t , or abundance and dominance), s o c i a b i l i t y , constancy, f i d e l i t y , and v i g o r of the component species l i e s w i t h i n l i m i t s governed not only by the ecotope ( c l i m a t e , s o i l , substratum, topography, and b i o t i c environmental f a c t o r s ) , but a l s o by the h i s t o r i c a l f a c t o r s of the v e g e t a t i o n a l development((the f o u r t h dimension or space-time f a c t o r ) . The conceptual b a s i s of ecosystem c l a s s i f i c a t i o n l i e s w i t h i n the d e f i n -i t i o n . I t i s on t h i s general biogeocoenotic foundation that the c l a s s i f i c -a t i o n i n t h i s t h e s i s i s based. Other recent s t u d i e s concerning e c o l o g i c a l c l a s s i f i c a t i o n i n B r i t i s h Columbia i n c l u d e the comments on Canadian p l a n t communities of I l v e s s a l o (1929) and K u j a l a (1945), and the more d e t a i l e d works of T i s d a l e (1947, 1957) on the grasslands and Douglas-Fir Zone of B.C., S p i l s b u r y and Smith (1947) on c o a s t a l Douglas-Fir f o r e s t s , Moss (1952) on the Peace R i v e r grass-lands, Szczawinski (1953) on c o r t i c o l o u s communities i n the Douglas-Fir Zone of C o a s t a l B.C., I l l i n g w o r t h and A r l i d g e (1960) on lodgepole pine and spruce-a l p i n e f i r stands of c e n t r a l B.C. Studies of v e g e t a t i o n i n the Kootenay d i s t r i c t i n c l u d e the survey of H o l l i c k (1927) on f l o r a of the Eugene s i l t s i n the Kootenay V a l l e y , and the d e s c r i p t i o n s of major v e g e t a t i o n u n i t s of the Rocky Mountain Trench by 5. Maclean and Holland (1958). Using l e s s e r v e g e t a t i o n , Johnson (1954) assessed s i t e q u a l i t y f o r trees on a l i m i t e d range of s i t e s i n the Arrow Lakes f o r e s t . K r a j i n a (1953-55) described s i x f o r e s t a s s o c i a t i o n s i n the Wet Subzone of the I n t e r i o r Western Hemlock Zone, and provided u s e f u l i n f o r m a t i o n on s o i l m i c r o f l o r a and s i l v i c u l t u r a l recommendations f o r commercial t r e e s . Ker (1957) developed volume and y i e l d t a b l e s f o r major timber species i n the Arrow Lakes area. H i s s i t e index curves, based on height growth of dominant c o n i f e r pioneers at 50 years, are p a r t i c u l a r l y u s e f u l f o r comparative s i t e q u a l i t y s t u d i e s . In developing the management plan f o r the Celgar tr e e farm l i c e n c e , Waldie (1954) o u t l i n e s the r e q u i r e -ments f o r sustained y i e l d management i n much of the Subzone. For e c o l o g i c a l l y r e l a t e d areas of northern Idaho, Daubenmire (1952) des c r i b e d a number of climax a s s o c i a t i o n s i n c l u d i n g Tsuga h e t e r o p h y l l a and Thula p l i c a t a . On mesic s i t e s , b e t t e r growth of L a r i x o c c i d e n t a l i s and Pinus monticola and poorer growth of Tsuga h e t e r o p h y l l a . an abundance of Abies g r a n d i s . and the prominence on mesic s i t e s i n some areas of Xero-phyllum tenax suggest that the c l i m a t e of Daubenmire's Western Hemlock -Western Red Cedar Zone i s more c o n t i n e n t a l than that of the Hemlock Zone north of the border. Communities of t h i s Subzone most c l o s e l y r e l a t e d to Daubenmire's a s s o c i a t i o n s are undoubtedly those described h e r e i n as "southern v a r i a n t s " of the average Subzonal f o r e s t types, and found p a r t i c -u l a r l y i n the E r i e Creek V a l l e y near Salmo. 6. DESCRIPTION OF THE STUDY AREA A d e t a i l e d d e s c r i p t i o n of l o c a t i o n , physiography, macroclimate, ecology and dominant tre e species f o r the study area has been given by Smith (1963), and i s not repeated here. A b r i e f d e s c r i p t i o n of the Subzone f o l l o w s . The Dry Subzone of the I n t e r i o r Western Hemlock Zone l i e s between longitude 117° 5* and 119°, and l a t i t u d e 49° 10' and 51' i n the S e l k i r k and Monashee ranges of the Columbia Mountains of southeast B r i t i s h Columbia ( F i g . 1). I t i n c l u d e s much of the Shuswap R i v e r v a l l e y system (Sugar Lake, Mabel Lake, and p a r t s of Mara and Shuswap Lakes) which d r a i n s west to the F r a s e r R i v e r , and most of the v a l l e y systems of the Arrow Lakes, Slocan Lake ( F i g . 2 ) , Trout Lake ( F i g . 3) and p a r t s of Kootenay Lake a l l of which c o n t r i b u t e to the Columbia R i v e r drainage. A l t i t u d i n a l l y the Subzone l i e s between 1200 to 4000 f t . e l e v a t i o n , i . e . between the I n t e r i o r Douglas-Fir Zone a t lower e l e v a t i o n s and the Subalpine Engelmann spruce - A l p i n e f i r Zone higher up. Due to the vag a r i e s of mountain c l i m a t e these a l t i t u d i n a l boundaries v a r y c o n s i d e r a b l y . The h i s t o r y of resource development i n the area i s r e l a t i v e l y s h o r t , p o s s i b l y one of the most i n t e n s i v e periods being during the 1890s when mining f o r s i l v e r , l e a d and z i n c , p a r t i c u l a r l y i n the Slocan area, was at i t s peak (Johnson, 1952). During t h i s p e r i o d much of the f o r e s t was burned, probably by prospectors seeking b e t t e r views of f o r e s t e d rock outcrops. At present the major a c t i v i t y i s l o g g i n g , mainly f o r sawlogs and pulpwood. I n t e n s i f i c -a t i o n of f o r e s t management and c l o s e r u t i l i z a t i o n of standing crops p a r a l l e l s the present manufacturing boom. Although narrow f r i n g e s along major r i v e r s , and low areas near l a k e s i d e towns a l l o w moderate success i n vegetable and f r u i t farming ( F i g . 4 ) , n e i t h e r the c l i m a t e nor the a v a i l a b l e a g r i c u l t u r a l to f o l l o w Fig. 1. Map of study area showing glaciers and 4000ft! contour. { (Vow <mith,l%}) 7. land are s u f f i c i e n t to s a t i s f y l o c a l needs. The study area belongs to the Southern Columbia S e c t i o n of the Columbia F o r e s t Region described by Rowe (1959). This region i s o f t e n c a l l e d the " I n t e r i o r Wet B e l t " or "Columbia F o r e s t " . K r a j i n a (1964) i n c l u d e s the I n t e r i o r Western Hemlock Zone i n the Canadian C o r d i l l e r a n Forest Region, one of seven B i o g e o c l i m a t i c Regions and 12 Zones i n B r i t i s h Columbia. E l e v a t i o n s range from v a l l e y bottoms near Malakwa at 1200 feet to peaks over 10,000 f e e t i n the S e l k i r k s (Putman, 1952). The t e r r a i n i s g e n e r a l l y rugged, w i t h frequent U-shaped v a l l e y s , c i r q u e s and moraines, p a r t i c u l a r l y a t higher e l e v a t i o n s ( F i g . 5). Broad sandy g l a c i o f l u v i a l t e r r a c e s cover la r g e areas a t lower e l e v a t i o n s i n the major v a l l e y s ( F i g . 6). Bedrock geology i s extremely complex, thus Smith (1963) was forced to r e s t r i c t h i s d e s c r i p t i o n of the area to the formations u n d e r l y i n g stands studied i n the f i e l d . Precambrian sedimentaries and metamorphics u n d e r l i e the Trout Lake area ( F i g . 5) and headwaters of Kootenay Lake; some Mesozoic v o l c a n i c s occur i n the Kaslo d i s t r i c t ; T r i a s s i c sedimentaries and meta-morphics dominate the s u b s t r a t a between Kootenay, Slocan and Upper Arrow Lakes; igneous i n t r u s i v e s u n d e r l i e areas at Caribou Creek, Burton, S i l v e r t o n , Duhamel Creek, Nakusp, Wilson Lake, Summit Lake and Whatshan Lake. Smith (1963) considered the zonal s o i l s to be Normal O r t h i c Podzols, Ortsfeein Podzols, and I Normal Minimal Podzols ( N a t i o n a l S o i l Survey Committee I960), a l l s t r o n g l y p o d z o l i z e d and c h a r a c t e r i z e d by low pH, low exchangeable c a t i o n s , low Ca: Mg r a t i o , and f e l t y mor humus. These zonal s o i l s , l i k e the zonal v e g e t a t i o n to be described l a t e r , r e f l e c t the i n f l u e n c e of p r e v a i l i n g macroclimate. In s i t u a t i o n s where edaphic or time f a c t o r s exert a greater i n f l u e n c e than c l i m a t e i n s o i l development, Smith (op. c i t . ) described many other s o i l types belonging to B r u n i s o l i c , G l e y s o l i c and Muck s o i l Sub-groups. to follow page 7. F i g . 2. Looking north on Slocan Lake. Steep forested slopes to waters edge preclude lowland farming. The Hemlock Zone extends approximately to the elevation shown. F i g . 3. C h a r a c t e r i s t i c snowslide roads on forested slope above Trout Lake. Top t h i r d of forest i s subalpine Engelmann Spruce f o r e s t . High country of S e l k i r k s i n distance. 8. In many respects t h i s f o r e s t Zone i s comparable to the C o a s t a l Western Hemlock Zone yet the c o n t i n e n t a l c l i m a t i c i n f l u e n c e i s evident i n sh o r t e r growing seasons and g r e a t e r temperature extremes. Kbppen's c l i m a t i c c l a s s i f i c a t i o n ( i n Trewartha, 1943) i n c l u d e s the Subzone mainly i n the Dfb*, w i t h f r i n g e s to south, west and east belonging to the wet Dsb. P r e v a i l i n g winds are from the northwest and p r e c i p i t a t i o n i s c h a r a c t e r i s t -i c a l l y orographic, moisture condensing from c o o l i n g a i r as i t i s forced up and over the g e n e r a l l y north-south t r e n d i n g Columbia Mountains. During the growing season r e l a t i v e h u m i d i t i e s are h i g h , s k i e s are o f t e n overcast f o r long p e r i o d s , and l i g h t n i n g storms are frequent. Much of the summer p r e c i p i t a t i o n i s a s s o c i a t e d w i t h these storms. The Okanagan V a l l e y to the west and Rocky Mountain Trench t o the east r e c e i v e l e s s p r e c i p i t a t i o n due to a combination of low e l e v a t i o n (Okanagan) and rainshadow e f f e c t s (Rocky Mountain Trench), phenomena common to many regions i n the western c o r d i l l e r a north of the T r o p i c of Cancer where p r e v a i l i n g winds are from the west. A summary of p e r t i n e n t c l i m a t i c i n f o r m a t i o n i s given below. Most of these data are a b s t r a c t e d from Department of Transport summaries of c l i m a t i c data taken at v o l u n t e e r s t a t i o n s throughout the Subzone (Province of B r i t i s h Columbia, 1962). C l i m a t i c s t a t i o n s p l u s t h e i r e l e v a t i o n s , on which the f o l l o w i n g summaries are based are Malakwa (1220 f t . above sea l e v e l ) , Sicamous (1400), Mabel Lake (1310), Sugar Lake (2000), Needles (1421), Fauquier (1570), East Arrow Park (1413), Nakusp (1500), New Denver (1850), Sandon (3550), Nelson (1760 and 1980), Kaslo (1930), Lardeau (1805), and Gerrard (2350). Because of the t y p i c a l l a k e s i d e s i t u a t i o n of large towns * Dfb and Dsb - p r i m a r i l y humid microthermal c l i m a t e w i t h no d i s t i n c t l y dry season; d r i e s t month of summer r e c e i v i n g more ( f ) or l e s s (s) than 1.2 inches p r e c i p i t a t i o n ; temperature of warmest month below 71.6 F. to follow page 8. F i g . 4. Farmland near Nakusp. Lands suitable f o r a g r i -culture are scarce due to rough topography and inadequate climates. 9. where weather readings are u s u a l l y taken, most s t a t i o n s are at low r a t h e r than middle or h i g h e l e v a t i o n s . Thus the average zonal c l i m a t e may be s l i g h t l y c o o l e r and moister than these data i n d i c a t e . Mean annual temperature 42 - 46° F Mean monthly temperature January 22 - 27° F J u l y 63 - 69° F Months above 50° F 5 Months below 32° F 3 (-4) Absolute maximum temperature 95 - 104° F Absolute minimum temperature -36 - -7° F F r o s t f r e e days 90 - 180 Mean annual p r e c i p i t a t i o n 1 9 - 4 0 inches Mean annual s n o w f a l l 52 - 173 inche; Seasonal occurence of p r e c i p i t a t i o n : wettest season - w i n t e r (40% ppt) wettest months - December and January 2.1 - 5.0 inches d r i e s t season - summer (20% ppt) d r i e s t months - mainly J u l y and August, but i n some areas March or A p r i l , 0.6 - 2.5 inches P o t e n t i a l e v a p o t r a n s p i r a t i o n 13.0 - 18.1 inches per year Vegetation of the Subzone i s dense c o n i f e r f o r e s t dominated by the 2 c l i m a t i c climax Tsuga h e t e r o p h y l l a (western hemlock) and the edaphic climax Thuga p l i c a t a (western red-cedar). Prominent c o n i f e r pioneers are Pseudotsuga  m e n z i e s i i ( D o u g l a s - f i r ) , Pinus monticola (western white pine) and L a r i x  o c c i d e n t a l i s , ( w e s t e r n l a r c h ) , the l a s t s p e c i e s , along w i t h Abies grandis (grand f i r ) , d i s t i n g u i s h i n g t h i s Subzone from the Wet Subzone to the north. * P o t e n t i a l e v a p o t r a n s p i r a t i o n i s estimated from mean annual temperature data u s i n g a simple method devised by Holdridge (1959). The value estimates the amount of water t h a t , t h e o r e t i c a l l y , c o u l d be l o s t through evaporation and t r a n s p i r a t i o n from s o i l and v e g e t a t i o n i f s u f f i c i e n t so&l moisture were always a v a i l a b l e . The values given here show that annual e v a p o t r a n s p i r a t i o n i s f a r l e s s than annual p r e c i p i t a t i o n , i n d i c a t i n g a favourable s o i l moisture regime f o r v e g e t a t i o n . 2 Species authorship given w i t h the c h e c k l i s t i n Appendix A. to follow page 9. F i g . 5. Rugged high country of S e l k i r k Mountains (over 9000 f t . ) near Trout Lake. Limestone mountains, possibly the source of subsurface streams depositing tufa at breaking out points at lower elevations. F i g . 6. Broad forested a l l u v i a l terrace (Makinson f l a t s ) i n Mosquito Va l l e y north of Arrow Park. 10. A s s o c i a t e d hardwoods are Populus tremuloides (trembling aspen), Betula  p a p y r i f e r a (paper b i r t h ) and Populus t r i c h o c a r p a (black cottonwood), the l a s t being p a r t i c u l a r l y evident along r i v e r banks. S a l i x bebbiana and S. s c o u l e r i a n a (willow) are o c c a s i o n a l l y common i n young f o r e s t s on l a r g e areas severely burned i n recent years. P i c e a engelmannii (Engelmann spruce) i s o f t e n frequent along bottoms of narrow high-walled stream v a l l e y s and o c c a s i o n a l l y occurs i n young stands upslope. I n d i v i d u a l s of Abies l a s i o c a r p a ( a l p i n e f i r ) and v e r y r a r e l y Pinus a l b i c a u l i s (white-bark p i n e ) , both azonal subalpine s p e c i e s , are sometimes s c a t t e r e d i n c s e r a l stands. C h a r a c t e r i s t i c l e s s e r v e g e t a t i o n dominants are Pachistima m y r s i n i t e s ( f a l s e box), Chimaphila  umbellata (p r i n c e ' s p i n e ) , Linnaea b o r e a l i s (twin f l o w e r ) , and the moss C a l l i e r g o n e l l a s c h r e b e r i . A c h a r a c t e r i s t i c combination of species f o r the Subzone, de r i v e d from data i n t h i s p r o j e c t , i s presented l a t e r i n the D i s c u s s i o n . 11. METHOD The d e s c r i p t i v e technique and the manner of arrangement i n t o c l a s s e s are e s s e n t i a l l y those u n i v e r s a l l y employed i n European v e g e t a t i o n c l a s s i -f i c a t i o n , but i n f r e q u e n t l y used i n North America. The standard method, o r i g i n a l l y designed s p e c i f i c a l l y f o r c l a s s i f i c a t i o n of phytocoenoses, has been expanded to i n c l u d e those h a b i t a t c h a r a c t e r i s t i c s necessary f o r d e t a i l e d s t u d i e s of f o r e s t biogeocoenoses (Sukachev, 1944), commonly r e f e r r e d to as f o r e s t types ( K r a j i n a , 1960; O r l o c i , 1961) or f o r e s t ecosystems ( K r a j i n a , 1960). Work i s d i v i d e d i n t o two stages: 1) a n a l y s i s , and 2) s y n t h e s i s . S o c i o l o g i c a l a n a l y s i s P r e l i m i n a r y reconnaissance of the study area l e d to the t e n t a t i v e r e c o g n i t i o n of four or f i v e reasonably d i s t i n c t f o r e s t communities at the p l a n t a s s o c i a t i o n l e v e l . Sample stands were chosen throughout the Zone w i t h i n each of these communities wherever c o n d i t i o n s appeared uniform. A number of these stands were l a t e r r e j e c t e d because they included fragments of other communities or because they occupied ecotones between communities. A t o t a l of 163 stands were s u b j e c t i v e l y sampled and described i n d e t a i l . With the a i d of compass, abney and topographic c h a i n , a o n e - f i f t h acre r e c t a n g u l a r p l o t was e s t a b l i s h e d i n each stand. The h a b i t a t and v e g e t a t i o n of each sample p l o t were described f o l l o w i n g methods of K r a j i n a (1933), w i t h s l i g h t m o d i f i c a t i o n . In a d d i t i o n , a l l trees over 6 f e e t t a l l were t a l l i e d by s p e c i e s , diameter c l a s s and crown c l a s s . Height and age of r e p r e s e n t a t i v e t r e e s i n a l l crown c l a s s e s were a l s o de-termined. 12. P l a n t c o l l e c t i o n and photographic record Specimens of a l l species i n c l u d e d i n t h i s study have been f i l e d i n the U n i v e r s i t y of B r i t i s h Columbia Herbarium. Manuals a n d , f l o r a s used as a i d s to i d e n t i f i c a t i o n are l i s t e d f o l l o w i n g L i t e r a t u r e C i t e d . Black-and-white and c o l o u r photographs were taken of r e p r e s e n t a t i v e stands. S o c i o l o g i c a l s y n t h e s i s Synthesis t a b l e s - p l a n t a s s o c i a t i o n s A n a l y t i c f i e l d data f o r each stand were arranged i n synthesis t a b l e s , one t a b l e f o r each p l a n t a s s o c i a t i o n (Appendix F ) . This i n v o l v e d constant checking, rearrangement, and sometimes r e j e c t i o n of stands when vegetation-h a b i t a t r e l a t i o n s h i p s became apparent as synthesis proceeded. Although a number of more o b j e c t i v e methods f o r grouping stands i n t o a s s o c i a t i o n s were t r i e d , p a r t i c u l a r l y groupings based on i n t e r s p e c i f i c a s s o c i a t i o n of a l i m i t e d number of prominent species ( G o o d a l l , 1953; Greig-Smith, 1957), no method proved as e f f e c t i v e i n t h i s i n i t i a l grouping i n t o a s s o c i a t i o n s as the very tedious yet time-proven method of s u b j e c t i v e arrangements. As Poore (1962) p o i n t s out, the i n i t i a l framework of c l a s s e s i s of n e c e s s i t y and by i t s proven u t i l i t y , a product of s u b j e c t i v e s h u f f l i n g and r e s h u f f l i n g . Objective s t a t i s t i c a l t e s t s may f o l l o w once the i n i t i a l s u b j e c t i v e c l a s s i f i c a t i o n i s made, but should not be w i d e l y used before t h i s i s accomplished. Data i n the s y n t h e s i s t a b l e s are arranged i n three major c a t e g o r i e s ; 1) h a b i t a t data, 2) t r e e data, 3) v e g e t a t i o n a n a l y s i s . Arrangement of stands i n s y n t h e s i s t a b l e s from which the p l a n t a s s o c i a -t i o n s were e v e n t u a l l y a b s t r a c t e d was based almost e n t i r e l y on v e g e t a t i o n c h a r a c t e r i s t i c s . H a b i t a t c h a r a c t e r i s t i c s were employed whete l e s s e r v e g e t a t i o n was spares.as, f o r example, beneath dense pioneer c o n i f e r t h i c k e t s on mesic 13. s i t e s . In such c a s e s , s o i l c h a r a c t e r i s t i c s u s u a l l y i n d i c a t e d what type of l e s s e r v e g e t a t i o n cover would normally be present were tree crowns l e s s dense. Once stands were grouped i n t e n t a t i v e p l a n t a s s o c i a t i o n s they were f u r t h e r d i v i d e d i n t o two major h a b i t a t s u b d i v i s i o n s : a) stands on slopes (mainly g l a c i a l t i l l , c o l l u v i u m , rock o u t c r o p s ) , and b) stands on a l l u v i a l f l a t s ( f l o o d p l a i n s , t e r r a c e s , e t c . ) . This provided a convenient physio-graphic s t a r t i n g p o i n t f o r diagnosing undescribed communities. F o r e s t types P l a n t a s s o c i a t i o n s were f u r t h e r d i v i d e d i n t o f o r e s t types on the b a s i s of a l l a v a i l a b l e c h a r a c t e r i s t i c s of the biogeocoenose^". These f o r e s t types c o n s t i t u t e the smallest p r a c t i c a b l e working u n i t s f o r f o r e s t r y purposes, i n d i v i d u a l stands ranging i n extent from o n e - f i f t h acre (e.g., Depression Skunk Cabbage) to many acres (e.g., A l l u v i a l Normal Moss). Most of the f o r e s t types are comparable to sub-associations i n that they d i f f e r f l o r i s t i c -a l l y from the t y p i c a l p l a n t a s s o c i a t i o n as a r e s u l t of edaphic i n f l u e n c e s (Drees, 1953). A good example i s the Tufa D e v i l ' s Club f o r e s t type of the D e v i l ' s Club a s s o c i a t i o n , which d i f f e r s f l o r i s t i c a l l y from the normal a s s o c i a t i o n as a r e s u l t of a high c o n c e n t r a t i o n of calcium carbonate i n the wet s o i l l a y e r s . A few f o r e s t types, however, are c a l l e d " v a r i a n t s " (Drees, 1953) due to the presumed dominating i n f l u e n c e of c l i m a t e i n causing f l o r i s t i c v a r i a t i o n . 1 Although c h a r a c t e r i s t i c s of both environment and biocoenose were considered i n d e l i m i t i n g f o r e s t types, v e g e t a t i o n i n most cases was s u f f i c i e n t l y d i s t i n c t to j u s t i f y separate c o n s i d e r a t i o n on the b a s i s of phytocoenose only. 14. Secondary succession stages Four s u c c e s s i o n a l stages were recognized w i t h i n each p l a n t a s s o c i a t i o n : Stage 4 - deforested land to very young regeneration; Stage 3 - dominant hardwood-pioneer f o r e s t ; c h a r a c t e r i z e d by an abundance of Betula p a p y r i f e r a . Populus tremuloides. P. t r i c h o c a r p a . or S a l i x spp. i n the main crown canopy; Stage 2 - dominant c o n i f e r - p i o n e e r f o r e s t ; c h a r a c t e r i z e d by an abundance of Pseudotsuga m e n z i e s i i . Pinus monticola. or L a r i x o c c i d e n t a l i s i n the main crown canopy; Stage 1 - climax f o r e s t , or approaching i t ; an abundance of u s u a l l y Tsuga h e t e r o p h y l l a or Thujta p l i c a t a i n the main crown canopy. These stages are d e l i m i t e d p r i m a r i l y on the b a s i s of composition of the tree l a y e r . Where l e s s e r v e g e t a t i o n and sometimes s o i l s vary c o n s i s t e n t l y w i t h change i n tree cover w i t h i n any one p l a n t a s s o c i a t i o n , stages may then be equivalent to sub- a s s o c i a t i o n s and are described as such. Recognition of secondary seres w i t h i n each p l a n t a s s o c i a t i o n emphasizes the dynamic nature of the biogeocoenose, p a r t i c u l a r l y i t s c a p a c i t y f o r v a r i a t i o n on any given s i t e over short periods of time (100-300 y e a r s ) . While p o s s i b l y d i f f e r i n g i n a number of ways stage 4 and stage 1 s t i l l belong to the same e c o l o g i c u n i t i n the sense t h a t , b a r r i n g disturbance (e.g., by f i r e ) , stage 4 w i l l unavoidably develop i n t o stage 1 i n a r e l a t i v e l y few c e n t u r i e s . This gradient of v e g e t a t i o n i n time i s another example of the continuum i n n a t u r a l p l a n t communities. C h a r a c t e r i s t i c combination of species F o l l o w i n g c a l c u l a t i o n of constancy and cover degree averages f o r each species i n each a s s o c i a t i o n , a t a b l e of constant species was produced (Appendix B) i n c l u d i n g the species constant (see below) i n any one or more p l a n t 15. a s s o c i a t i o n s . Mainly based on t h i s t a b l e and p a r t l y from f u r t h e r study of the s y n t h e s i s t a b l e , a " c h a r a c t e r i s t i c combination of spe c i e s " was a b s t r a c t e d f o r each p l a n t a s s o c i a t i o n i n c l u d i n g : a) Constant dominant species - species w i t h both high constancy (81% or more) and h i g h dominance ( a dominant species must have a h i g her ACD than the f o l l o w i n g : In the t r e e l a y e r ^ 20% cover; shrub l a y e r , herb l a y e r , bryophytes and l i c h e n s on ground l a y e r ^ 10% cover; bryophytes and l i c h e n s on rocks and decaying wood l a y e r s ^ 5% cover). b) Constant species - species w i t h a high constancy (81% or more), but r e l a t i v e l y low dominance (lower than values i n a) ). c) Important non-constant species - species which are n e i t h e r constant nor dominant, but which when present are u s e f u l i n d i c a t o r s f o r diagnosing p l a n t a s s o c i a t i o n s . Some d i f f e r e n t i a t i n g species may be i n c l u d e d here. The c h a r a c t e r i s t i c combination of species i s the most important combined value f o r d e f i n i n g p l a n t a s s o c i a t i o n s (Braun-Blanquet, 1932; K r a j i n a , 1933). As i t i s employed here, i t l a y s major emphasis on the o b j e c t i v e presence-or-absence of species and t h e i r r e l a t i v e dominance ( i . e . , constancy and cover r e s p e c t i v e l y ) , and complements t h i s where p o s s i b l e by i n c l u s i o n of the l e s s obvious d i a g n o s t i c a l l y important non-constant species. These important non-constants are comparable to the low constancy ' c h a r a c t e r i s t i c species' of Braun-Blanquet's f i d e l i t y s c a l e (1932). For e s t types and stages w i t h i n each p l a n t a s s o c i a t i o n were f u r t h e r c h a r a c t e r i z e d by d i f f e r e n t i a t i n g species as w e l l as other v e g e t a t i o n a l and e c o l o g i c c h a r a c t e r i s t i c s when a p p l i c a b l e . 16. L i f e form L i f e forms are shown i n the check l i s t of species i n Appendix A. Because l i f e form c l a s s e s , without m o d i f i c a t i o n , are more s u i t a b l e f o r c l a s s i f i c a t i o n s of f l o r a s than v e g e t a t i o n ( P o l u n i n , 1959), i n that they consider species l i s t s only and not r e l a t i v e abundance, an attempt was made here to u t i l i z e l i f e form v a l u e s , weighted by dominance, at the p l a n t a s s o c i a t i o n l e v e l . I t was hoped th a t such "vegetation l i f e form s p e c t r a " by emphasizing the means by which the dominant v e g e t a t i o n components of each p l a n t a s s o c i a t i o n s u r v i v e the unfavourable season, would f u r t h e r a i d i n c h a r a c t e r i z i n g these communities. Vegetation l i f e form values f o r each l i f e form c l a s s i n each p l a n t a s s o c i a t i o n were determined as f o l l o w s : 1) s e l e c t constant species i n the p l a n t a s s o c i a t i o n , 2) sum the ACDs of a l l constant species w i t h i n each l i f e form c l a s s , 3) add up the sums i n 2 ) , 4) express the values i n 2) as percentages of the t o t a l i n 3). These are the v e g e t a t i o n l i f e form values f o r each p l a n t a s s o c i a t i o n . F o r e s t trees From the f i e l d data, diameter c l a s s stand and b a s a l area t a b l e s were developed f o r each stand, i n a d d i t i o n to estimates of s i t e c a p a c i t y based on t r e e height-growth. Volume and weight estimates of standing crop and net primary p r o d u c t i v i t y of t r e e trunks ( a l l species included) i n each f o r e s t type were a l s o made. Dominance/frequency/density (DFD) values ( C u r t i s , 1947) were developed f o r each t r e e s p e c i e s , p r i m a r i l y to demonstrate the r e l a t i v e importance of tre e s i n each f o r e s t type. "Succession i n d i c e s " , based on DFD v a l u e s , were used to show the r e l a t i o n s h i p of f o r e s t types,to one another i n a primary 17. succession sere from bare land to c l i m a t i c climax community. For a d e t a i l e d account of these techniques see Appendix F. 18. RESULTS In the f o l l o w i n g pages twenty two f o r e s t types of the Dry Subzone of the I n t e r i o r Western Hemlock Zone are described. They are grouped i n s i x p l a n t a s s o c i a t i o n s (sensu K r a j i n a 1960). Some i n t r a z o n a l communities r e p r e s e n t a t i v e of the adjacent Douglas-Fir Zone (Brayshaw 1955) were a l s o s t u d i e d , b r i n g i n g the t o t a l number of commun-i t i e s described i n t h i s study to twenty seven (see l i s t of Forest types, Appendix E ) . In the f o r e s t type d e s c r i p t i o n s d e t a i l e d c o n s i d e r a t i o n i s always given f i r s t to the community most r e p r e s e n t a t i v e of each p l a n t a s s o c i a t i o n , i . e . the "type" community i n the taxonomic sense. The communities which f o l l o w are compared and con t r a s t e d w i t h the preceding type-community thereby mi n i m i z i n g exhaustive treatment of each type, yet a l l o w i n g emphasis to be placed on the most s i g n i f i c a n t d i a g n o s t i c f e a t u r e s . With the exception of some of the "important nonr.constant" s p e c i e s , the c h a r a c t e r i s t i c combination of species given f o r each a s s o c i a t i o n approximates the ve g e t a t i o n composition of the type-community more c l o s e l y than i t does any other f o r e s t type w i t h i n the p l a n t a s s o c i a t i o n . The "important non-constant" exceptions are " d i f f e r -e n t i a t i n g s p e c i e s " (Braun-Blanquet, 1932) f o r s u b - d i v i s i o n s of the p l a n t a s s o c i a t i o n . The d e s c r i p t i o n s are based on data compiled i n Synthesis Tables (Appendix F ) . The tree growth and inve n t o r y summaries, and DFD i n d i c e s are taken from summaries of tree measurement i n Appendices C and D. A l i s t of a l l stands s t u d i e d , by number, w i t h f o r e s t type, stage of secondary succession, e l e v a t i o n and l o c a l i t y f o r each stand i s given i n Appendix E. A c h e c k l i s t of the 538 p l a n t species i n c l u d e d i n t h i s study i s given i n Appendix A. 19. Lichen a s s o c i a t i o n (Cladonietum) Stands of t h i s community are g e n e r a l l y found on rock outcrops or k n o l l s where microclimate i s extremely dry and hot during the growing season. Summer temperatures at ground l e v e l may reach as h i g h as 152° F. Smith's s t u d i e s (1963) of s o i l moisture i n d i c a t e that the Lichen p l a n t a s s o c i a t i o n occupies the d r i e s t f o r e s t h a b i t a t s of the Subzone. Stands r e p r e s e n t a t i v e of t h i s p l a n t a s s o c i a t i o n were stud i e d i n the Nakusp area, near Sicamous, and at h i g h e l e v a t i o n near S i l v e r t o n . Stands are not e x t e n s i v e , u s u a l l y covering l e s s than an acre. They occur on k n o l l s at a l l e l e v a t i o n s w i t h i n the Subzone, at higher e l e v a t i o n s g e n e r a l l y on south exposures, but at lower e l e v a t i o n s on a l l exposures. Slope v a r i e s from 0 - 35° i n the stands stu d i e d and the topography g e n e r a l l y has a convex pro-f i l e and n e u t r a l contour w i t h bedrock outcroppings producing an i r r e g u l a r ground surface. S o i l s (summarized from Smith, 1963)^ are mainly coarse-textured Dry O r t h i c A c i d Brown Wooded. One stand i s a Dry Minimal Podzol and another a Mor Regosol. A l l s o i l s are shallow, depth to bedrock v a r y i n g from 30 - 73 cm. Parent m a t e r i a l i s residuum and/or c o l l u v i u m g e n e r a l l y admixed w i t h g l a c i a l t i l l , a t l e a s t i n deeper s o i l pockets. I f present, the leached Ae h o r i z o n i s g e n e r a l l y represented by only a t r a c e . The pH of the main r o o t i n g l a y e r ( i n t h i s p l a n t a s s o c i a t i o n g e n e r a l l y a B h o r i z o n leached of water s o l u b l e m a t e r i a l , but sometimes an Ah or C horizon) v a r i e s from 4.7 to 5.8. pH of the organic h o r i z o n immediately above mineral s o i l v a r i e s from 4.0 to 5.6. The f o r e s t c o n s i s t s of open stands dominated by c o n i f e r s of a l l heights and ages i n the t r e e l a y e r , and w i t h abundant dry s i t e shrubs and herbs i n the ground l a y e r s . Moss and lichen-covered rock outcrops are conspicuous. 1 Each f o r e s t type d e s c r i p t i o n that f o l l o w s i n c l u d e s s o i l c h a r a c t e r i s t i c s summarized from Smith, 1963. 20. Because of extremely v a r i a b l e s o i l depth w i t h i n any one community, v e g e t a t i o n i s markedly patchy, most v a s c u l a r p l a n t s g e n e r a l l y r o o t i n g i n s o i l pockets where moisture i s channelled and conserved during the dry growing season. In some cases dense shade beneath t r e e clumps appears to l i m i t the establishme* of many shade i n t o l e r a n t s p e c ies. According to the constancy diagram ( F i g . 7) the Lichen a s s o c i a t i o n i s homogeneous. Most species are i n C l a s s I (species o c c u r r i n g 20% or l e s s of stands) w i t h a secondary peak o c c u r r i n g i n C l a s s 5 (81% or more). The species l i s t f o r t h i s a s s o c i a t i o n i n c l u d e s 149 species. Cover diagrams of constant dominant species ( F i g . 8 a) show the average dominance of the major species i n the Lichen a s s o c i a t i o n . Taken w i t h the ve g e t a t i o n l i f e form spectrum ( F i g . 8 b ) , based on dominance of constant species o n l y , a good impression of the community composition and s t r u c t u r e i s obtained. Among constant s p e c i e s , the dominance of mosses and l i c h e n s and the absence of geophytes c h a r a c t e r i z e s the Lichen a s s o c i a t i o n . Cover of tree crowns i n the stands s t u d i e d ranges from 35 - 60% w i t h Pseudotsuga m e n z i e s i i dominating a t a l l stages from regeneration to climax. Pinus monticola and L a r i x o c c i d e n t a l i s are predominant and Betula p a p y r i f e r a i s o c c a s i o n a l l y common, the l a s t o c c u r r i n g only i n succession stages preceding the climax. Thuja p l i c a t a . though p o o r l y developed, i s q u i t e common i n the t r e e l a y e r . Tsuga h e t e r o p h y l l a i s present i n the tree l a y e r only i n climax stands and yet never exceeds the lower l i m i t s of t r e e cover. In one stand a t high e l e v a t i o n on a k n o l l above S i l v e r t o n , a few trees of the a l p i n e species Pinus a l b i c a u l i s had e s t a b l i s h e d , p o s s i b l y i n response to a sub-alpine " t o p - c l i m a t e " o f t e n c h a r a c t e r i s t i c of h i l l t o p s and k n o l l s , at an e l e v a t i o n w e l l below the normal montane-sub-alpine v e g e t a t i o n boundary. The shrub l a y e r , c o v e r i n g from 25 - 90% of the ground surface i s dom-in a t e d by Pachistima m y r s i n i t e s and Thuja p l i c a t a , w i t h Vaccinium membranaceum and Spiraea l u c i d a a t t h e i r g r e a t e s t abundance i n climax stages. Even i n to f o l l o w page 20. F i g . 7. Constancy diagram f o r Lichen a s s o c i a t i o n . £10 •> 10 o L 149 SPC. i m nz i Pl fOD 0T6\) 6-A C^Edx ie sU T H U J A PLltfttft P O L V U I CHUC-t TdlJ I P EA IMOM P g L T I ( r £ f t f l ftPWUQSft 3) 5 4 0 ^ 3 0 zo 5 O L PM P« C H O M L I F E F-oitM i —r 1 0 20 30 F i g . 8. Lichen a s s o c i a t i o n : a) Average cover of constant dominant species; b) Vegetation l i f e form spectrum based on cover of constant species. 21. climax stands, Pseudotsuga m e n z i e s i i i s common i n the shrub l a y e r t e s t i f y i n g to the edaphic climax nature of D o u g l a s - f i r i n t h i s community. S a l i x  s c o u l e r i a n a . S. bebbiana and vigorous Rosa gymnocarpa. though r a r e l y abundant, are r e s t r i c t e d to e a r l y stages of succession. Herbs provide 20 - 90% cover i n the stands s t u d i e d w i t h vigorous and h i g h l y s o c i a b l e A r c t o s t a p h y l o s u v a - u r s i ^ and Chimaphila umbellata dominating a l l stands. L i s t e r a cordata i s e x c e p t i o n a l l y vigorous and q u i t e s o c i a b l e i n the climax stand. C o r y d a l i s sempervirens. Cryptogramma c r i s p a . Asplenium  trichomanes. Carex r o s s i i . Heuchera c y l i n d r i c a , and Polypodium vulgare are among those vigorous species r e s t r i c t e d to the Lichen a s s o c i a t i o n but only s c a t t e r e d throughout the stand. Bryophytes and l i c h e n s cover most of the humus and bedrock a v a i l a b l e , from 50 - 85% of the ground surface. C a l l i e r g o n e l l a s c h r e b e r i i s conspicuously dominant, w i t h Polytrichum juniperinum. P e l t i g e r a aphthosa, Hylocomium splen-dens, and Dicranum scoparium (the l a s t two not always present) almost as common. Cladonia m i t i s , C. r a n g i f e r i a n and C. g r a c i l i s . the l a s t always present, may have e x c e l l e n t v i g o u r , p a r t i c u l a r l y i n o l d e r stands where the ground has been long undisturbed by f i r e . Numerous bryophytes and l i c h e n s , when growing on the humus or rock, are c h a r a c t e r i s t i c only of the Lichen a s s o c i a t i o n , among them Bartramia pomiformis, Rhacomitrium canescens w i t h good v i g o u r , T r i t o m a r i a s c i t u l a , C e t r a r i a i s l a n d i c a , Dermatocarpon miniatum. U m b i l i c a r i a phaea. Cladonia b e l l i d i f l o r a . C. arbuscula and C. u n c i a l i s , None of these are abundant but they are u s u a l l y vigorous when present. Many other Cladonia spp. , Stereocaulon tomentosum. Rhacomitrium heterostrichum and other x e r o p h y t i c cryptogams, w h i l e present i n other communities u s u a l l y i n e a r l y stages of succ e s s i o n , achieve t h e i r best development i n the Lichen a s s o c i a t i o n . 1 Because of i t s low s t a t u r e the creeping chamaephytic shrub A. u v a - u r s i i s i n c l u d e d i n the herb l a y e r . to follow page 21. F i g . 9. Open stand of Lichen association on rock outcrop. Trees are mainly Pseudotsuga  menziesii of a l l ages, with some small Thuja p l i c a t a . Shrubby ground cover i s Arctostaphylos uva-ursi. July 1960. F i g . 10. Closer view of Lichen as s o c i a t i o n showing poor growth of Pseudotsuga menziesii, scrubby Thuja  p l i c a t a understory, Arctostaphylos uva-ursi, Cladonia  m i t i s , Dicranum scoparium and C a l l i e r g o n e l l a schreberi on rock outcrop. On the small amount of decaying wood (10% cover a t the most) i n these stands a s i m i l a r s i t u a t i o n o b t a i n s ; Dicranum strieturn i s always dominant and vigorous w i t h P t i l i d i u m pulcherrimum constant but not very aggressive. A v a r i e t y of Cladonia species are present and vigorous along w i t h one or two poorly-developed l i v e r w o r t s on moist undersides of l o g s , such as Lophocolea h e t e r o p h y l l a and Lophozia i n c i s a . Hypnum c i r c i n a l e . Dicranum  fuscescens. and Cephalozia spp., are c h a r a c t e r i s t i c a l l y present. The c h a r a c t e r i s t i c combination of species i s given i n Table 1. Tree data i s summarized i n Table 2. TABLE 1. CHARACTERISTIC COMBINATION OF SPECIES LICHEN ASSOCIATION (CLADONIETUM) + Constant dominant only i n t h i s a s s o c i a t i o n * Constant only i n t h i s a s s o c i a t i o n !' Most s u o c e s s f u l i n t h i s a s s o c i a t i o n but may be present i n adjacent communities 1 I n c l u d i n g a l l species Layer Trees Shrubs Herbs Constant dominants Pseudotsuga m e n z i e s i i Pachistima m y r s i n i t e s +Pseudotsuga m e n z i e s i i Thuga p l i c a t a +Vaccinium membranaceum +Arctostaphyllos uva-ursi Chimaphila umbellata Bryophytes & Lichens a) on humus C a l l i e r g o n e l l a schreberi +D. scoparium +Polytrichum juniperinum + P e l t i g e r a aphthosa +Cladonia spp.* Constants only Pinus monticola Thuga p l i c a t a Amelanchier a l n i f o l i a Lonicera utahensis Tsuga h e t e r o p h y l l a *Festuca o c c i d e n t a l i s * L i l i u m columbianum Linnaea b o r e a l i s *Aulacomnium androgynum *Rhacomitrium heterostichum +Cladonia g r a c i l i s P e l t i g e r a canina Important Non-constants Pinus a l b i c a u l i s Juniperus communis !Lonicera c i l i o s a Asplenium trichomanes !Calamagrostis rubescens !Campanula r o t u n d i f o l i a C o r y d a l i s sempervirens Cryptogramma c r i s p a Heuchera c y l i n d r i c a Polypodium vulgare Woodsia scopulina Bartramia pomiformis Claopodium c r i s p i f o l i u m .'Dicranum rugosum Plagiothecium p i l i f e r u m !Rhacomitrium canescens T r i t o m a r i a s c i t u l a C e t r a r i a i s l a n d i c a C. f a h l u n e n s i s Dermatocarpon miniatum (on rock) CONT'D LICHEN ASSOCIATION (cont'd) Layer Constant dominants Constants only Important Non-constants a) on humus U m b i l i c a r i a phaea (on rock) (cont'd) !Stereocaulon tomentosum .'Peltigera membranacea P. canina var. s p u r i a .'P. malacea !numerous Cladonia spp. (i n c l u d e d i n constant dominants; see syn t h e s i s t a b l e f o r component species) b) on decaying wood +Dicranum s t r i c t u m Dicranum fuscescens ^Cladonia spp.^ Lophozia spp.'" P t i l i d i u m pulcherrimum c) on rock + C a l l i e r g o n e l l a s c hreberi *Aulacomnium androgynum +D. scoparium *Rhacomitrium heterostichum +Polytrichum juniperinum *Cladonia g r a c i l i s + C l a d o n i a spp. >vPeltigera canina + P e l t i g e r a aphthosa 25. TABLE 2. Tree data summary. Lichen a s s o c i a t i o n S i t e index of t r e e s : 1) Height at 50 years ( f t . ) 2) Height at 100 years ( f t . ) Pinus monticola  Pseudotsuga m e n z i e s i i  L a r i x o c c i d e n t a l i s Average maximum height ( f t . ) ; diameter of tree of average maximum height ( i n . ) : Pinus monticola (83; 12.8) Pseudotsuga m e n z i e s i i (73; 16.4) L a r i x o c c i d e n t a l i s (102; 16.1) (Thuja p l i c a t a and Tsuga h e t e r o p h y l l a grow so p o o r l y i n the Lichen a s s o c i a t i o n that height growth was d i f f i c u l t to estimate.) Stage 1 Stage 2 Basal area per acre (sq. f t . ) (126) 85 - 107 - 129 Number stems per acre (365) 490 - 797 - 1120 Average diameter of stand ( i n . ) (8.0) 4.3 - 5.1 - 6.1 Average age of dominants (yrs.) (220+) 72 - 94 - 120 Average height of dominants & codominants ( f t . ) (89) 57 - 65 - 75 Moss a s s o c i a t i o n (Pachistimeto - C a l l i e r g o n e l l e t u m s c h r e b e r i ) Of the f i v e p l a n t a s s o c i a t i o n s i n c l u d e d i n t h i s study, the Moss asso-c i a t i o n i s the most mesic and, p r e d i c t a b l y , the most common i n the Subzone. Representative stands of t h i s p l a n t a s s o c i a t i o n may cover very large areas and are encountered more f r e q u e n t l y than any other a s s o c i a t i o n . The Moss a s s o c i a t i o n i n c l u d e s a number of f o r e s t types ranging from the shallow-s o i l e d Slope Dry Moss f o r e s t type through the c l i m a t i c climax Slope Normal Moss f o r e s t type, to the more moist Slope Bunchberry Moss f o r e s t type and i t s southern v a r i a n t . A l l u v i a l f o r e s t types included i n t h i s p l a n t asso-c i a t i o n are the A l l u v i a l Dry Moss f o r e s t type and the A l l u v i a l Normal Moss f o r e s t type. The c h a r a c t e r i s t i c combination of species f o r the Moss a s s o c i a t i o n i s given i n Table 3. 25 - 35 - 45 50 - 75 - 100 50 - 65 - 80 50 - 65 - 80 TABLE 3. CHARACTERISTIC COMBINATION OF SPECIES MOSS ASSOCIATION (PACHISTIMETO - CALLIERGONELLETUM SCHREBERI) + Constant dominant only i n t h i s a s s o c i a t i o n * Constant only i n t h i s a s s o c i a t i o n ! Most s u c c e s s f u l i n t h i s a s s o c i a t i o n but may be present i n adjacent communities 1 I n c l u d i n g a l l species Layer Trees Shrubs Herbs Constant dominants +Pinus monticola Pseudotsuga m e n z i e s i i Tsuga he t e r o p h y l l a Pachistima m y r s i n i t e s Thuja p l i c a t a Tsuga h e t e r o p h y l l a Chimaphila umbellata +Linnaea b o r e a l i s Constants only Thuja p l i c a t a Amelanchier a l n i f o l i a Vaccinium membranaceum C l i n t o n i a u n i f l o r a Goodyera o b l o n g i f o l i a Pteridium aquilinum P y r o l a secunda Important Non-constants .'Pinus c o n t o r t a Ceanothus sanguineus Prunus emarginata IShepherdia canadensis JVaccinium m y r t i l l o i d e s JApocynum androsaemifolium F r a g a r i a glauca JG a u l t h e r i a o v a t i f o l i a G. s h a l l o n L i s t e r a c a urina !Lycopodium complanatum Melampyrum l i n e a r e Monotropa hypopitys P y r o l a chlorantha !P. p i c t a Spiranthes romanzoffiana c o n t 1 d ro MOSS ASSOCIATION (cont'd) Layer Constant dominants Constants only Important Non-constants Bryophytes & Lichens a) on humus C a l l i e r g o n e l l a s c hreberi b) on decaying wood Dicranum fuscescens * R h y t i d i o p s i s robusta P e l t i g e r a aphthosa Dicranum strieturn Hypnum c i r c i n a l e P t i l i d i u m pulcherrimum Cladonia spp.* !Dicranum fuscescens to 28. D i s t r i b u t i o n of species i n constancy c l a s s e s i n t h i s a s s o c i a t i o n i s shown i n F i g . 11. A t o t a l of 306 species were considered i n d e s c r i b i n g the Moss a s s o c i a t i o n , the bulk occuring i n l e s s than 20% of the sample stands (constancy c l a s s I ) . A second maximum i n c l a s s 5 suggests t h a t , based on constancy, the Moss a s s o c i a t i o n i s homogeneous. F i g . 12 a) shows the average cover of constant dominant species. F i g . 12 b) i n d i c a t e s that t h i s mesic community, apart from the obvious dominance of phanerophytes, i s p r i m a r i l y chamaephytic w i t h a l e s s e r abundance of bryophytes. Slope Normal Moss f o r e s t type (SNM) This i s probably the c l i m a t i c climax community of the Subzone and as such i s the community to which a l l others tend to develop i n primary succession. I t may be found on upland s i t e s of a l l exposures and moderate to considerable slopes. The stands studied cover from one-half t o s e v e r a l acres and range i n e l e v a t i o n from 1770 to 3310 f e e t . Topography i n c l u d e s a s l i g h t l y convex to n e u t r a l p r o f i l e and contour, w i t h the ground surface i n most cases being r e l a t i v e l y smooth, although hummocky i r r e g u l a r surfaces are not uncommon. S o i l s are g e n e r a l l y derived from coarse-textured g l a c i a l t i l l s , although some stands grow on banks of sandy a l l u v i a l t e r r a c e fragments. S o i l depth i s g e n e r a l l y unknown, i . e . , the depth to a l a y e r impervious to roots was not reached i n the s o i l p i t , but p a r t i a l l y compacted l a y e r s were o c c a s i o n a l l y found at depths ranging from 32 - 87 cm. i n some s o i l s . The thickness of the Ae h o r i z o n ranges from a t r a c e to 6 cm., averaging 2 cm., the t h i c k e s t l a y e r s being found beneath long e s t a b l i s h e d climax stands. A l s o i n climax stands of t h i s f o r e s t type, the pH of the organic horizons immediately above mineral s o i l l i e s at the a c i d end of the 3.4 - 5.8 pH range, the l a t t e r f i g u r e being more c h a r a c t e r i s t i c of e a r l y stages of secondary succession. pH of to f o l l o w page 28. F i g . 11. Constancy diagram f o r Moss a s s o c i a t i o n . JW JO vj 40 Mi <a. v/1 JO IA. Q .ID UJ cfl £ JO o z: .0 3T06 I II I I I COHSTftNCf Pieooo-riocfl Mcw* ie tM T i o C r f t M g T S r t O P H V L L f t  PftCVUSTlMf l MVftSlM>re4  T r l U T f l r V u f l T f t  LtNMOCf l &0<?6flLiS d ) PH Pu C H 6r M L I J I 1 1 1 \o z o 3 0 4 o ro 60 AV6RA-6-6 COMES. Dc6-Ctf ( °/W F i g . 12. Moss a s s o c i a t i o n : a) average cove'r of constant dominant s p e c i e s ; b) v e g e t a t i o n l i f e form spectrum based on cover of constant species. Pm megaphanerophytes; Pn nanophanerophytes; C chamaephytes; H hemicryptophytes G geophytes; M mosses; L l i c h e n s . f r r A 2fl b) r u 29. the main r o o t i n g h o r i z o n v a r i e s from 5.2 - 6.6. The c o n t r a s t i n a c i d i t y between climax and s e r a i stands i s of the same nature but l e s s evident than i n the organic l a y e r s . S o i l types are mainly Normal Minimal Podzols, but I I Normal Minimal Podsols, Normal O r t h i c Podsols, and Normal O r t h i c A c i d Brown Woodeds were a l s o d e s c r i b e d , the l a s t mainly i n the l e s s a c i d s o i l s of stands i n e a r l y stages of secondary succession. D i s t r i b u t i o n of v e g e t a t i o n w i t h i n any one stand i s g e n e r a l l y q u i t e u n i -form. Where l o c a l species aggregations are evident, thus i n t r o d u c i n g a heterogeneous p a t t e r n to the stand, such contagious d i s t r i b u t i o n s are g e n e r a l l y due to l o c a l v a r i a t i o n i n s o i l moisture (e.g., i n a depression) or to the i n f l u e n c e of tr e e crowns which e i t h e r r e s t r i c t l i g h t beneath dense clumps or a l l o w more l i g h t to reach the f o r e s t f l o o r beneath openings. In only one stand (SB 106) i s the p a t t e r n extremely heterogeneous; i t s clump - open area nature i s probably c o n d i t i o n e d by an unusual combination of a l l u v i a l parent m a t e r i a l , south exposure on a 30° slope, decaying wood patches l e f t by f i r e and an adjacent stand of pure hemlock. F o l l o w i n g the f i r e which o r i g i n a l l y c l e a r e d the area abundant hemlock e s t a b l i s h e d on the decaying wood l e a v i n g the adjacent bare, hot sandy slope to be c o l o n i z e d by a sparse cover of herbs, bryophytes and l i c h e n s . Steepness of the slope and sandy s o i l t e x t u r e prob-a b l y l e d t o r a p i d s o i l creep and sheet e r o s i o n f o l l o w i n g r a i n s , thus impeding establishment of t r e e s on the open areas. Dense shade of the clumps now pre-vents a l l but the most shade-tolerant herbs from growing beneath. Thus the stand today i s very heterogeneous. Were i t not f o r the e s s e n t i a l s i m i l a r i t y of the s o i l s beneath the clump and open area, each p a r t might be considered a d i s t i n c t v e g e t a t i o n type. The v e g e t a t i o n composition of the SNM i s e s s e n t i a l l y that of the Moss a s s o c i a t i o n ' s c h a r a c t e r i s t i c combination of species, 30. In the twenty stands s t u d i e d , the tree l a y e r covers from 45 - 90% of the ground surface w i t h an average of 70%. The c l i m a t i c climax Tsuga h e t e r o p h y l l a dominates the climax stands, where c o n i f e r pioneers are not as common as i n younger stands and where hardwoods are absent. I t i s a l s o present, and o f t e n abundant, i n the t r e e l a y e r of every stand from regeneration to climax. Pseudotsuga m e n z i e s i i and Pinus monticola are both w e l l represented i n most stands, w h i l e L a r i x o c c i d e n t a l i s i s common, though of l e s s importance, than white pine and D o u g l a s - f i r . Thuja p l i c a t a i s g e n e r a l l y present though never vigorous. Other t r e e s commonly abundant i n young stands are Betu l a p a p y r i f e r a . Populus tremuloides. and sometimes Pinus c o n t o r t a . Even Populus t r i c h o c a r p a may be present i n the youngest stands, where mineral s o i l has been exposed by f i r e , along w i t h s i n g l e low vi g o u r t r e e s Abies l a s i o c a r p a and Pi c e a engel-mannii. Shrub cover ranges from 107o beneath dense t r e e crowns of c o n i f e r pioneer second growth to 90% i n more open stands. Average cover i s 60%. Pachistima  m y r s i n i t e s dominates the shrub l a y e r , o f t e n covering over 50% of the p l o t s , Tsuga h e t e r o p h y l l a regeneration i s a l s o abundant, as i s that of Thuja p l i c a t a . the l a t t e r being of p a r t i c u l a r l y poor vigour. Vaccinium membranaceum i s constant but i s r a r e l y as abundant as i n the Lichen a s s o c i a t i o n , I t i s most vigorous and abundant i n young stands, as i s Shepherdia canadensis, a species r a r e l y found i n climax stands. Other species g e n e r a l l y common i n the young stands are Spiraea l u c i d a . L o n i c e r a u t a h e n s i s . Mahonia a q u i f o l i u m , and regen-e r a t i o n of Pinus monticola and Pseudotsuga m e n z i e s i i . Rubus p a r v i f l o r u s . w h i l e present i n a l l succession stages, reaches i t s best development i n young stands. L o n i c e r a i n v o l u c r a t a . Prunus emarginata. S a l i x s c o u l e r i a n a and S, bebbiana. although present i n very few stands and only o c c a s i o n a l l y vigorous and s o c i a b l e , are r e s t r i c t e d e n t i r e l y to the youngest stands r e p r e s e n t a t i v e of t h i s f o r e s t type. to f o l l o w page 30. F i g . 13. C l i m a t i c climax Slope Normal Moss f o r e s t . Pure Tsuga h e t e r o p h y l l a stand w i t h C a l l i e r g o n e l l a  s c h r e b e r i ground cover. August 14, 1961. F i g . 14. Dense immature SNM stand i n c l u d i n g Pseudo-tsuga m e n z i e s i i . Pinus monticola. Tsuga h e t e r o p h y l l a and Thuja p l i c a t a . Ground cover i s sparse. Note abundant dead f a l l . August 18, 1961. 31. The herb l a y e r again demonstrates a wide range of cover, from l e s s than 17. to 857. averaging 307. w i t h Chimaphila umbel l a t a and Linnaea b o r e a l i s dom-in a n t and v i g o r o u s , p a r t i c u l a r l y i n younger stands where bryophyte cover has not b u i l t up over t h i c k organic l a y e r s . C l i n t o n i a u n i f l o r a . P y r o l a secunda and V i o l a o r b i c u l a t a are a l s o prominent, and G a u l t h e r i a o v a t i f o l i a , P t e r i d i u m  aquilinum and P y r o l a a s a r i f o l i a may provide c o n s i d e r a b l e cover p a r t i c u l a r l y i n young stands. C o r a l l o r h i z a maculata and Goodyera o b l o n g i f o l i a a t t a i n t h e i r best development i n climax stands, w h i l e the u b i q u i s t Hieracium a l b i f l o r u m i s g e n e r a l l y common and o f t e n vigorous i n younger and more open stands. A l -though not always present, F r a g a r i a b r a c t e a t a a t t a i n s i t s best vigour and abundance i n the SNM type, g e n e r a l l y being r e s t r i c t e d to very young stands. Cover of bryophytes and l i c h e n s ranges from 1% beneath dense stands of white pine and D o u g l a s - f i r second growth, to over 80% i n stands where t h i c k , a c i d raw humus l a y e r s preclude the establishment of most v a s c u l a r p l a n t s i n favour of o x y l o p h y t i c mosses such as C a l l i e r g o n e l l a s c h r e b e r i * . Bryophytes on raw humus are dominated by abundant and vigorous C a l l i e r -g o n e l l a s c h r e b e r i . Hylocomium splendens. while not constant, may a l s o be abundant and dominant, p a r t i c u l a r l y i n o l d e r stands, as may be the constant and o f t e n v i g o r o u s , h i g h l y s o c i a b l e R h y t i d i o p s i s robusta. Some Brachythecium species are g e n e r a l l y present. Dicranum fuscescens, Lophozia lycopodioides and Heterocladium procurrens (on mineral s o i l ) may be present, though s c a t t e r e d , u s u a l l y only i n climax stands, w h i l e P t i l i u m c r i s t a - c a s t r e n s i s and R h y t i d i a -delphus t r i q u e t r u s achieve t h e i r best development i n younger stands. P e l t i g e r a 1 C a l l i e r g o n e l l a s c h r e b e r i may develop humus almost as a c i d as that produced by Sphagnum spp. (Hartmann, 1952). I t may e v e n t u a l l y e l i m i n a t e i t s e l f from the phytocoenose because humus becomes too a c i d . In combination w i t h a climax o v e r s t o r y of the oxylophyte Tsuga h e t e r o p h y l l a , s o i l s may be r a p i d l y leached of n u t r i e n t s and f o r e s t s i t e s c o n s i d e r a b l y depauperized i n a r e l a t i v e -l y short time. 32. aphthosa i s a constant and vigorous l i c h e n , w i t h P. canina much the same. Young stands g e n e r a l l y support the widest v a r i e t y of Cladonia spp., nine of which, other than C. g r a c i l i s , i s ever common i n any one stand. On decaying wood Dicranum fuscescens i s by f a r the most constant domin-ant bryophyte, p a r t i c u l a r l y i n o l d e r stands. C a l l i e r g o n e l l a s c h r e b e r i may a l s o be abundant along w i t h Hylocomium splendens. R h y t i d i o p s i s robusta and Hypnum c i r c i n a l e . Dicranum strieturn i s constant but never abundant. Among the l i v e r w o r t s , P t i l i d i u m pulcherrimum and P. c a l i f o r n i c u m are o f t e n r e l a t i v e -l y abundant and v i g o r o u s , growing w e l l on r o t t i n g wood of a l l tree species. L e p i d o z i a reptans, Lophozia porphyroleuca, L. i n c i s a and other u n i d e n t i f i e d Lophozia spp. may a l s o be common and vigorous on moist p a r t s of w e l l decayed logs. A v a r i e t y of l i c h e n s i n h a b i t decaying wood. Most prominent are P e l t i -gera aphthosa. P. canina and P. P o l y d a c t y l a . Other species are Cladonia  b a c i l l a r i s . C. carneola, C. deformis, C. f i m b r i a t a , C. g r a c i l i s , C. squamosa, C. b e l l i d i f l o r a , C e t r a r i a glauca, C. s c u t a t a , C. j u n i p e r i n a , Nephroma l a e v i g a -tum. P e l t i g e r a h o r i z o n t a l i s . and Physcia c a e s i a . none of which are c o n s i s t e n t -l y represented and are r a r e l y vigorous. In stands where rocks are s c a t t e r e d or exposed on the surface, many bryophytes and l i c h e n s may occur on these rock s u r f a c e s , none being very prominent. Among the most common are C a l l i e r g o n e l l a s c h r e b e r i . Mnium spinut-osum. P t i l i d i u m pulcherrimum. R h y t i d i o p s i s robusta, P e l t i g e r a aphrhosa. Nephroma spp. ( p a r t i c u l a r l y N. p a r i l e ) . Rhacomitrium canescens. R. hetero-stichum. and R. patens and the greater number of Cladonia spp., a l l of which are r a r e , are g e n e r a l l y r e s t r i c t e d to young r a t h e r than climax stands Data on f o r e s t trees i s summarized i n Table 4, TABLE 4. Tree data summary. Slope Normal Moss f o r e s t type S i t e index: 1) Height a t 50 years ( f t . ) 50 - 70 - 90 2) Height at 100 years ( f t . ) Pinus monticola 100 - 125 - 150 Pseudotsuga m e n z i e s i i 80 - 95 • • 120 L a r i x o c c i d e n t a l i s 90 - 105 - 120 Tsuga h e t e r o p h y l l a 70 - 80 - 100 Pinus contorta 90 - 100 - 110 Populus tremuloides (90) Average maximum height ( f t . ) ; Diameter of tree of average maximum height ( i n . ) : Pinus monticola (116; 24.7) Pseudotsuga m e n z i e s i i 111 - _118 - 131; 18.5 - 24.7 - 34.1 L a r i x o c c i d e n t a l i s (127; 23.0) Tsuga h e t e r o p h y l l a 98 - .104 - 111; 18.3 - 24.2 - 32.6 (Thuja p l i c a t a grows poorly i n the SNM. Height growth was inadequate f o r i n c l u s i o n here.) Stage 1 Stage 2 Stage 3 Basal area per acre (sq. f t . ) 229 - 274 - 296 233 - 276 - 313 120 - 155 - 197 Number stems per acre 540 - 1002 - 1270 1110 - 1795 - 2640 350 - 1465 - 4310 Average diameter of stand ( i n . ) 5.9 - 7Jt - 9.5 4.5 - 5J> - 6.6 2.8 - ^ _3 - 8.0 Average age of dominants (yrs.) 123 - 291 - 460 78 - 86 - 101 48 - 65 - 85 Average height of dominants & codominants ( f t . ) 96 - 112 - 129 86 - 99 - 111 52 - 65 - 85 Secondary succession index (%) 100 69 55 34, Slope Dry Moss f o r e s t type (SDM) The Slope Dry Moss f o r e s t type i s e d a p h i c a l l y d r i e r than the c l i m a t i c c limax SNM f o r e s t type and i s e c o l o g i c a l l y s i t u a t e d between i t and the Lich e n a s s o c i a t i o n on an i d e a l i z e d slope. C*.. ".-•[• i ,>•, ••••1'2: < V > The four p l o t s studied range i n e l e v a t i o n from 2300 to 2735 f e e t , and i n extent from one to s e v e r a l acres. A l l are s i t u a t e d on moderate to steep southto west exposures, w i t h topography showing n e u t r a l contour and p r o f i l e and hummocky surface c o n d i t i o n s , the l a s t o f t e n r e l a t e d to bedrock beneath t h i n s o i l . S o i l s d i f f e r from the SNM f o r e s t type i n that they are a l l shallow w i t h bedrock a t 20 - 70 cm. i n the s o i l p i t s . Parent m a t e r i a l i s e i t h e r residuum or a mixture of g l a c i a l t i l l and residuum w i t h the texture of the main root-in g h o r i z o n u s u a l l y a g r a v e l l y sandy loam. Thickness of the Ae h o r i z o n v a r i e s from a trac e i n the youngest stand to 2 cm. i n the o l d e s t high eleva-t i o n p l o t . pH of the main r o o t i n g h o r i z o n v a r i e s from 5,4 - 6.1, and of the organic l a y e r immediately above mineral s o i l from 3.9 - 5.9. The s o i l type i s mainly Dry Minimal Podzol although one stand has a Dry O r t h i c A c i d Brown Wooded. Pa t t e r n of v e g e t a t i o n i s s i m i l a r to the SNM f o r e s t type w i t h some pa t c h i n e s s , i n t h i s case g e n e r a l l y c o n ditioned by v a r i a t i o n i n s o i l depth, as i n the Lichen a s s o c i a t i o n . Stands are g e n e r a l l y c l o s e d and t r e e growth i s poorer than i n the SNM. Vegetation of the SDM f o r e s t type d i f f e r s from the SNM mainly by absence of c e r t a i n species and reduced v i g o u r of others which normally achieve t h e i r optimum i n the c l i m a t i c climax SNM or adjacent moister Slope Bunchberry Moss type. Populus tremuloides and Shepherdia canadensis are absent. Good-yera o b l o n g i f o l i a , although constant f o r the Moss a s s o c i a t i o n , i s c o n s i s t e n t l y to f o l l o w page 34 F i g . 15. Mature Slope Dry Moss stand of mixed L a r i x  o c c i d e n t a l i s (now dead), Tsuga h e t e r o p h y l l a and Thuja p l i c a t a . Ground cover of C a l l i e r g o n e l l a  s c hreberi and s c a t t e r e d Chimaphila umbellata. August 2, 1960. 35. abundant and vigorous here. V i o l a o r b i c u l a t a o f t e n achieves i t s best development i n stands of the SDM type. The r e l a t i v e l y dry microclimate favours abundant moss cover on the ground. C a l l i e r g o n e l l a s c h r e b e r i , Hylocomium splendens and Rhytidiadelphus  t r i q u e t r u s f l o u r i s h here and P e l t i g e r a aphthosa and R h y t i d i o p s i s robusta may show e x c e p t i o n a l vigour. Generally speaking, bryophytes on decaying wood and rock are the same kinds as those i n the SNM type but are more abundant. C a l l i e r g o n e l l a  s c h r e b e r i . Mnium spinulosum and Dicranuum fuscescens may be frequent and vigorous on rocks w i t h i n any one stand. Reduced v i g o u r of tre e s i s r e f l e c t e d i n the f o l l o w i n g t r e e measurement data: TABLE 5. Tree data summary. Slope Dry Moss f o r e s t type. S i t e index: 1) Height a t 50 y r s . ( f t . ) 2) Height a t 100 y r s . ( f t . ) Pinus monticola  Pseudotsuga m e n z i e s i i  L a r i x o c c i d e n t a l i s  Tsuga h e t e r o p h y l l a Average maximum height of trees ( f t . ) maximum height ( i n . ) , Pinus monticola  Pseudotsuga m e n z i e s i i  L a r i x o c c i d e n t a l i s  Tsuga h e t e r o p h y l l a 50 - 55 60 70 - .80 - 90 7 0 - 7 5 - 8 0 (90) 60 - 65 - 70 diameter of tree of average 94 - J07 - 120; 13.4 - 16.1 - 18.8 91 - 13 - 94; 14.8 - 17.1 - 19.4 (105) 93: 16.5 - 16,7 - 16.8 (Thuja p l i c a t a growth i s poor. I t does not belong to the main crown canopy t h e r e f o r e i s not in c l u d e d here), Stage 1 Stage 2 Basal area per acre (sq. f t . ) 187 - 237 - 330 (267) Number stems per acre 450 - 767 - 1195 (2070) Average diameter of stand ( i n . ) 6.0 - 7.3 - 8.9 (4.9) Average age of dominants (yrs.) 17 Of -• 192+ - 230+ (89) Average height of dominants & codominants ( f t . ) 93 - 97 - 104 (86) 36. Slope Bunchberry Moss f o r e s t type (SBM) Stands i n c l u d e d i n t h i s community occupy a p o s i t i o n e c o l o g i c a l l y be-tween the mesic c l i m a t i c climax SNM type and the moist Slope A r a l i a Oakfern f o r e s t type (SAO), Tree growth i s g e n e r a l l y b e t t e r than i n the SNM and, w i t h one or two exceptions, the v e g e t a t i o n i s intermediate to the SNM and SAO f o r e s t types p a r t i c u l a r l y i n younger stands. SBM stands occupy one to s e v e r a l acres. The twenty-four stands s t u d i e d ranged i n e l e v a t i o n from 1600 - 3320 f e e t on moderate to steep slopes (up to 37°), exposed i n a l l d i r e c t i o n s but mainly t o the south. Topography v a r i e s but the most common p r o f i l e and contour i s n e u t r a l , w i t h n e u t r a l to hummocky ground surface, the l a t t e r o f t e n from root upturn and very o l d decaying wood. S o i l s i n many instances are under the i n f l u e n c e of s l i g h t deep-lying temporary seepage and are predominantly Moist Minimal Podsols or Moist O r t h i c Podzols. Less common s o i l types are Normal Minimal Podzols, I I Normal Minimal Podzols, Normal O r t h i c Podzols and one stand each of Normal O r t h i c Brown Wooded, Dry O r t h i c Brown Wooded and Normal O r t h i c A c i d Brown Wooded, the Brown Woodeds a l l i n e a r l y stages of succession. Three stands have Dry Minimal Eodzols r e f l e c t i n g the presence of bedrock r e l a t i v e l y near the ground surface. However, u n l i k e the dry SDM type f u r t h e r up slope, these three SBM s o i l s are probably s l i g h t l y i n f l u e n c e d by s o i l moisture d e r i v e d from temporary seepage, which moves along the bedrock surfaces during p a r t of the growing season. Parent m a t e r i a l s are p r i m a r i l y g l a c i a l t i l l s , although stands may be found on steep a l l u v i a l banks under the i n f l u e n c e of s l i g h t temporary seep-age. In some cases s o i l p r o f i l e s are shallow, bedrock l y i n g between 34 and 80 cms. i n the three Dry Minimal Podzols studied. In most s o i l s , however, a l a y e r impervious to roots was not found, although p a r t i a l l y compacted 37. l a y e r s were of t e n encountered at depths ranging from 26 - 66 cms. The th i c k n e s s of the Ae l a y e r v a r i e s from 0 to 7 cms., the t h i n n e s t l a y e r s being found i n s o i l s of young stands on south t o southwest exposures. S o i l t e x t u r e s are s i m i l a r to the SNM stands w i t h g r a v e l l y sandy loams predomin-a t i n g , although loamy sands are not uncommon. The pH of the main r o o t i n g h o r i z o n (almost always a B l a y e r enriched w i t h hydrated i r o n and organic matter) v a r i e s from 5.0 - 6.8, only the very l e a s t a c i d being beneath the youngest stands. Temporary seepage i n the SBM, although s l i g h t , may part-i a l l y compensate f o r l e a c h i n g of n u t r i e n t s from upper s o i l h o r i z o n s , a process p a r t i c u l a r l y marked beneath the t h i c k humus of climax stands. Thus the trend, c h a r a c t e r i s t i c of the SNM, l o w r a c i d i t y i n young stands e a r l y i n secondary succession i n c r e a s i n g to high a c i d i t y i n climax stands, may be l e s s obvious i n the SBM due to the compensating nature of n u t r i e n t - r i c h temporary seepage. pH of the organic l a y e r immediately above the mineral horizons shows no such l e v e l l i n g - o f f , the range being 3.5 i n climax stands to 6.0 i n the youngest communities. The s l i g h t temporary seepage of the SBM i s probably i n s u f f i c i e n t to compensate f o r the a c i d i f y i n g i n f l u e n c e a t i t s source, the humus, as i s the permanent seepage of some D e v i l ' s Club types described l a t e r . The v e g e t a t i o n composition of the SBM type d i f f e r s from the SNM mainly i n the abundance of Cornus canadensis i n most stands, and the common occurr-ence of such moist s i t e species ( r a r e l y vigorous but by t h e i r presence i n -d i c a t i n g moister c o n d i t i o n s ) as T i a r e l l a u n i f o l i a t a . Adenocaulon b i c o l o r . t r i f l o r u m and Osmorhiza c h i l e n s i s . C l i n t o n i a u n i f l o r a i s more abundant and vigorous i n the SBM than i n any other Moss a s s o c i a t i o n community. Of the shrubs, l i t t l e d i f f e r e n c e e x i s t s except f o r the high v i g o u r and abundance of Rubus p a r v i f l o r u s i n young stands and s l i g h t l y more Vaccinium o v a l i f o l i u m than i s common i n the SNM. Corylus c a l i f o r n i c a and some Cornus s t o l o n i f e r a to f o l l o w page 37. F i g . 16. Climax Slope Bunchberry Moss stand of Tsuga  h e t e r o p h y l l a . Compare l a r g e r trees w i t h SNM climax F i g . 5. Note understory of T. h e t e r o p h y l l a . Thuja p l i c a t a and Taxus b r e v i f o l i a . August 14, 1961. F i g . 17. Ground v e g e t a t i o n i n climax SBM stand: Cornus  canadensis. Linnaea b o r e a l i s . Chimaphila umbellata, C o r a l l o r h i z a maculata. J u l y , 1960. 38. may a l s o be present but of low v i g o u r i n younger stands. As might be expected w i t h moister c o n d i t i o n s , there i s a s l i g h t l y h i g h e r cedar to hemlock r a t i o than i n the SNM, and growth i s b e t t e r f o r most species. Bryophytes and l i c h e n s on the ground are much the same as i n the SNM except that R h y t i d i o p s i s robusta i s r a r e l y as abundant or vigorous i n climax stands, and the number of l i c h e n s , apart from P e l t i g e r a aphthosa and P. canina. are almost n i l . Although never abundant, both Lophocolea hetero-p h y l l a and Plagiothecium denticulatum on mineral s o i l are almost e n t i r e l y r e s t r i c t e d t o the SBM type, w i t h i n the Moss a s s o c i a t i o n . Decaying wood, being somewhat moister than i n the SNM, supports a few more Lophozia s p e c i e s , some i n extremely vigorous c o n d i t i o n . Lophozia  barbata i s e n t i r e l y absent and Jamesoniella autumnalis. r a r e i n the SNM, may be s c a t t e r e d but vigorous i n some stands. Mnium spinulosum. R h y t i d i o p s i s robusta and C a l l i e r g o n e l l a s c h r e b e r i a l l show b e t t e r development on rocks i n the SBM than the SNM, Lichens are much the same as i n the SNM. Tree data i s summarized by the f o l l o w i n g : TABLE 6. Tree data summary. Slope Bunchberry Moss f o r e s t type. S i t e index: 1) Height a t 50 years ( f t . ) 2) Height a t 100 years ( f t . ) Pinus monticola  Pseudotsugs m e n z i e s i i  L a r i x o c c i d e n t a l i s  Tsuga h e t e r o p h y l l a  Pinus c o n t o r t a  Populus tremuloides  Thuja p l i c a t a Average maximum height ( f t . ) ; diameter of tree of average maximum height ( i n . ) ; p i m i s m o n t i c o l a (131. 22.3) Pseudotsuga m e n z i e s i i (111; 20.8) Tsuga h e t e r o p h y l l a (110 - JL12 - 116; 20.4 - 25.0 - 30.6) cont'd. 60 - 80 - 100 IJ J •-100 - L30 - 160 90 - 110 - 120 100 - JL10 - 130 70 - 100 - 150 (100) (120) (120) TABLE 6. (cont'd.) Stage 1 Stage 2 Stage 3 Stage 4 Basal area per acre (sq, f t . ) 220 - 277 - 317 247 - 324 - 451 125 - 211 - 305 -Number stems per acre 340 - 638 - 795 900 - 1598 -3195 235 - 1196 -4365 42,500 Average diameter of stand ( i n . ) 7.3 - 9.4 - 13.0 4.1 - 6.6 - 9.2 2.3- 7.0 -11.3 -Average age of dominants (yrs.) 190 - 223+ 250+ 81 - 89 - 108 25 - 66 - 98 -Average height of dominants & codominants ( f t . ) 97 - 109 - 119 101 - 109 - 121 39 - 98 - 120 _ Secondary succession index 100% 76% 54% -V O 40 Slope Bunchberry Moss, southern v a r i a n t , f o r e s t type (SBMs) In the southern and southeastern p a r t of the Zone near Nelson and Salmo, the presence of Abies grandis as a dominant i n the tree l a y e r , and the nearby presence of vigorous Pinus ponderosa on lowland and outcrop s i t e s i n a number of s t a n d s , r e f l e c t s l i g h t changes i n macroclimate. In these stands, hemlock may be l o c a l i z e d and of low v i g o u r w h i l e D o u g l a s - f i r may assume a stronger r o l e i n climax stands than i t does f u r t h e r north i n comparable communities. Two very dense stands were studied i n t h i s area, one on a steep south-e a s t - f a c i n g bank of an a l l u v i a l t e r r a c e and the other on a steep southwest slope of mixed g l a c i a l t i l l and colluvium. S o i l s were studied only i n the stand on g l a c i a l t i l l - c o l l u v i u m . The s o i l type here was a Normal O r t h i c Brown Wooded with no Ae l a y e r and the r a t h e r high pH of 6.6 f o r the main r o o t i n g h o r i z o n , and 5.6 f o r the organic l a y e r immediately above mineral s o i l . V egetation d i f f e r s from the SBM mainly i n the presence of Abies grandis i n both t r e e and shrub l a y e r s . Because of the extremely dense tree cover, shrubs, herbs, and bryophytes are few; the stands are "subnudum". Only the o c c a s i o n a l presence of c e r t a i n species such as Chimaphila umbellata, P y r o l a  chlorantha i n good v i g o u r , and V i o l a o r b i c u l a t a combined with the s l i g h t l y r i c h e r (than SNM) s o i l s and the improved t r e e growth suggest that these stands belong t o the SBM type. Study of more stands should lead to c l e a r e r d e f i n i t i o n of t h i s community. Tree data i s summarized as f o l l o w s : 41. TABLE 7. Tree data summary. Slope Bunchberry Moss, southern v a r i a n t , f o r e s t type. S i t e index: 1) Height at 50 years ( f t . ) 2) Height at 100 years ( f t . ) 60 - 70 - 80 Pinus monticola  Pseudotsuga m e n z i e s i i  Betula p a p y r i f e r a 120 - 130 - 140 90 - 95 - 100 (80) Stage 2 Stage 3 B a s a l area per acre (sq. f t . ) Number stems per acre Average diameter of stand ( i n . ) Average age of dominants (yrs.) Average height of dominants & codominants (324) (1100) (7.4) (83) (287) (3295) (4.0) (54) ( f t . ) (76) (113) A l l u v i a l Normal Moss f o r e s t type (ANM) In t h i s Subzone, species showing a marked preference f o r a l l u v i a l s o i l s , p a r t i c u l a r l y on dry to mesic s i t e s , are Picea engelmanii. Vaccinium m y r t i l l -o i d e s , Lycopodium complanatum. Melapyrum l i n e a r e . Comandra l i v i d a . F r a g a r i a  glauca, Spiranthes romanzoffiana. Apocynum androsaemifolium, and Dicranum  rugosum. The o c c a s i o n a l presence of these species i n slope f o r e s t types i s o f t e n a c c i d e n t a l and development i s u s u a l l y poor. The ANM f o r e s t type i s comparable to the SNM type i n that i t i s the most mesic community of those on a l l u v i a l s i t e s . Growth c h a r a c t e r i s t i c s are more uniform, i f not s l i g h t l y b e t t e r than on slope types. The 11 stands s t u d i e d are a l l on wide t e r r a c e s of major v a l l e y s ( F i g . 6). They cover from one to s e v e r a l acres and range i n e l e v a t i o n from 1425 to 2300 f t . Topography i s g e n e r a l l y f l a t w i t h the c h a r a c t e r i s t i c , i r r e g u l a r l y un-d u l a t i n g surface of broad a l l u v i a l f l a t s . S o i l s are mainly Normal Minimal Podsols and Normal Orthie Podzols. I I Normal Minimal Podzols and Normal O r t h i c A c i d Brown Wooded s o i l s may be present beneath younger stands. Thickness of the Ae h o r i z o n v a r i e s from a t r a c e i n 42. the Brown Wooded s o i l s to 6 cm. i n one of the O r t h i c Podzols. Texture of the main r o o t i n g h o r i z o n v a r i e s from sandy to sandy loam. pH of t h i s h o r i z o n i s s i m i l a r to the SNM type, ranging from 5.2 beneath the o l d e r stands to 6.2 i n one of the younger ones. pH of the organic l a y e r immediately above mineral s o i l v a r i e s from 3.8 to 5.2, Pa t t e r n of v e g e t a t i o n i s g e n e r a l l y uniform, although some stands occur where heterogeneity i s marked, u s u a l l y as a r e s u l t of v a r i a t i o n i n a v a i l -a b i l i t y of s o i l moisture. Depressions i n the ground surface and patches of f i n e r - t e x t u r e d s o i l s o ften favour establishment of m o i s t u r e - l o v i n g species, i n a d d i t i o n to a l l o w i n g b e t t e r growth of mesophytes. The only other major f a c t o r apparently causing d i s c o n t i n u i t i e s i n the ve g e t a t i o n p a t t e r n i s v a r i -a t i o n i n l i g h t a v a i l a b l e to the herbs and shrubs. Dense clumps or openings favour decreased or excessive cover, r e s p e c t i v e l y , of shade i n t o l e r a n t species, thus c r e a t i n g a patchy and apparently heterogeneous v e g e t a t i o n p a t t e r n . As i n the SNM f o r e s t type, t r e e cover averages about 70% w i t h a range from a p a r k - l i k e 50% to a t h i c k e t 95%. The reason some stands of equal age on s i m i l a r a l l u v i a l s i t e s and w i t h apparently s i m i l a r f i r e h i s t o r i e s are dense t h i c k e t s and others are almost p a r k - l i k e may be the r e s u l t of v a r i a t i o n i n t r e e seed a v a i l a b l i t y . immediately f o l l o w i n g the f i r e s which removedr>the preceding stands. Where abundant seed was a v a i l a b l e , some of the densest stands of regeneration encountered anywhere i n the Subzone developed. Where seed was scarce, open stands w i t h extensive shrub and herb u n d e r s t o r i e s soon e s t a b l i s h e d . Apart from the presence i n almost a l l p l o t s of one or two tre e s of Picea  engelmannii. t r e e cover i s very s i m i l a r to the SNM f o r e s t type. Shrub compos-i t i o n i s much the same although p o s s i b l y s l i g h t l y more abundant and vigorous. Amelanchier a l n i f o l i a i s i n every stand studied and the a l l u v i a l Vaccinium ?.; to follow page 42. Fig . 18. Dense young stand of Tsuga heterophylla on nudum ANM s i t e , Note hemlock regeneration. Large hemlock veteran i n background survived l i g h t f i r e which l e f t much unburned humus, and provided seed to es t a b l i s h present stand, July 10. 1960. Fi g . 19. Climax A l l u v i a l Normal Moss stand of Tsuga  heterophylla, Echinodontium tinctorium conk on hemlock at l e f t . August 18, 1961. 43. m y r t - i l l o i d e s i s common. Rubus p a r v i f l o r a s , u n l i k e i n the slope f o r e s t " types, i s never prominent or vigorous. The Moss a s s o c i a t i o n dominant Pachistima m y r s i n i t e s may be e x c e p t i o n a l l y vigorous i n the ANM. Herb l a y e r cover i s g e n e r a l l y greater than i n the SNM, averaging 45%, although herbs beneath dense t r e e cover may occupy only 5% of the a v a i l a l b e space. F a i r l y common Comandra l i v i d a and F r a g a r i a glauca are c h a r a c t e r i s t i c of t h i s community, p a r t i c u l a r l y i n young stages. Apocynum androsaemifolium may be abundant here, while Lycopodium complanatum and Melampyrum l i n e a r e may be well-developed. Spiranthes romanzoffiana (though not abundant) was found only i n ANM stands. L i k e the herb and shrub l a y e r s , cover of bryophytes and l i c h e n s on ground averages higher than the SNM (35%), w i t h a range of 0% i n the densest stands to 60% i n p a r k - l i k e stands where clumping of trees i s prominent. Mnium spinulosum, Plagiothecium denticulatum, and Dicranum  fuscescens are absent. Polytrichum juniperinum while comon i n young stages of almost any Moss a s s o c i a t i o n may be p a r t i c u l a r l y abundant and vigorous i n the ANM. On the ground Cladonia squamosa may be almost e x c l u s i v e l y r e s t r i c t e d to t h i s community. Bryophytes and l i c h e n s on decaying wood d i f f e r l i t t l e from those of the SNM. Rocks on the ground surface are rare. The river-smoothed stones that may be present are r a r e l y c o l o n i z e d by more than crustose l i c h e n s . Tree measurements are summarized as f o l l o w s : TABLE 8. Tree data summary. A l l u v i a l Normal Moss f o r e s t type. S i t e index: 1) Height at 50 years ( f t . ) 40 - 75 - 90 2) Height at 100 years ( f t . ) Pinus monticola 70 - 120 - 140 Pseudotsuga m e n z i e s i i 90 - 100 - 110 L a r i x o c c i d e n t a l i s 80 - 95 - 110 Tsuga h e t e r o p h y l l a 70 - 95 - 110 Thuia p l i c a t a 60 - 75 - 90 Pinus c o n t o r t a 90 - 95 - 100 cont'd. TABLE 8. (cont'd) 2) cont'd. Populus tremuloides 90 Betula p a p y r i f e r a (80) Average maximum height ( f t . ) ; diameter of tree of average maximum height ( i n . ) : Pseudotsuga m e n z i e s i i (133; 25.2) L a r i x o c c i d e n t a l i s (130; 20.7) Tsuga h e t e r o p h y l l a 92 - 94 - 95; 16.2 - 17.0 - 17.7 Thuia p l i c a t a (80; 19.6) Picea engelmannii (98; 13.0) Stage 1 Stage 2 Stage 3 Basal area per acre (sq. f t . ) (194) (281) 107 - 165 - 221 Number stems per acre (868) (1658) 390 - 1832 - 7570 Average diameter of stand ( i n . ) (6.4) (4.9) 1.9 - 5.7 - 9.3 Average age of dominants (yrs.) (250+) (79) 42 - 59 - 74 Average height of dominants & codominants ( f t . ) (100) (94) 31 - 78 - 116 -p--P-45. A l l u v i a l Dry Moss f o r e s t type (ADM) Apart from c o n s i s t e n t d i f f e r e n c e s i n h a b i t a t and t o some extent i n v e g e t a t i o n , the ADM type i s comparable i n tree growth c h a r a c t e r i s t i c s to the upland Lichen f o r e s t type. Vegetation i s c l o s e s t to the ANM, however, which i n t urn d i f f e r s from the SNM f l o r i s t i c a l l y , mainly by the common presence of the a l l u v i a l s i t e i n d i c a t o r s mentioned e a r l i e r under the ANM, Stands of the ADM f o r e s t type may cover s e v e r a l acres on g r a v e l l y to sandy t e r r a c e s w e l l above r i v e r l e v e l . Coarse-textured a l l u v i u m precludes adequate upward c a p i l l a r y movement of water and allows r a p i d drainage of p r e c i p i t a t i o n , thus the v e g e t a t i o n i s c h a r a c t e r i s t i c a l l y xweophytic. In the 3 stands s t u d i e d , e l e v a t i o n s range from 1440 f t . , almost the lower a l t i t u d -i n a l l i m i t of the Subzone near Nakusp, to 2500 f t . on a g l a c i o - f l u v i a l t e r r a c e east of Whatshan Lake. Topography i s g e n e r a l l y f l a t w i t h the i r r e g u -l a r hummocky surface c h a r a c t e r i s t i c of broad a l l u v i a l deposits. In o l d e r stands, w i t h t h i c k leached l a y e r s (9 - 27 cm.), s o i l s are Normal O r t h i c Podzols. One young stand has a Dry Minimal Podzol w i t h an Ae l a y e r 2 cm. t h i c k . The main r o o t i n g h o r i z o n i n the one climax stand i s a 27 cm. t h i c k Ae w i t h a pH of 3.5. In younger stands, the main r o o t i n g l a y e r i s a developing B h o r i z o n enriched w i t h i r o n ; pH i s 6.3. pH of the organic l a y e r immediately above the mineral s o i l i s 3.6 i n the climax stand, to 4.4 beneath the young second growth stand at Whatshan Lake. Vegetation i s g e n e r a l l y uniform, any e x i s t i n g patchiness being due to v a r i a b l e l i g h t reaching the f o r e s t f l o o r r e s u l t i n g from i r r e g u l a r t r e e crown cover. With some exceptions, v e g e t a t i o n composition i s s i m i l a r to the ANM and v i g o u r i s reduced. Although v i g o u r of a l l t r e e s i s low, Pinus contorta i s of t e n w e l l -developed i n the ADM type. In o l d e r stands, Tsuga h e t e r o p h y l l a dominates the tree l a y e r but growth i s poor. Thuja p l i c a t a i s u s u a l l y absent from the 46. t r e e l a y e r yet may be f a i r l y common i n shrub form. Shrub cover may be up to 95%, the major p o r t i o n of t h i s being hemlock, f i r and cedar regeneration. However, Vaccinium m y r t i l l o i d e s and Amelanchier  a l n i f o l i a may be abundant though not as vigorous as i t i s i n the ANM, The presence of abundant, though not vi g o r o u s , G a u l t h e r i a s h a l l o n and sometimes Campanula r o t u n d i f o l i a and the absence of V i o l a o r b i c u l a t a and P y r o l a a s s a r i -f o l i a may a i d i n diagnosing t h i s f o r e s t type. Dense moss cover dominated by extremely vigorous and abundant C a l l i e r g o n e l l a  s c h r e b e r i . Dicranum rugosum and P e l t i g e r a aphthosa u s u a l l y a s s o c i a t e d w i t h abundant Lophozia barbata. and a number of Cladonia species such as C. chloro-phaea, C. g r a c i l i s . C. r a n g i f e r i n a . C. s y l v a t i c a as w e l l as Stereocaulon  tomentosum. may a l s o serve to c h a r a c t e r i z e t h i s community. As i n the SDM, Hylocomium splendens may a l s o be abundant and vigorous here. Decaying wood, and rocks when present, support a good f l o r a , the former dominated by Dicranum rugosum. Lophozia barbata and P e l t i g e r a aphthosa. and the l a t t e r by C a l l i e r g o n e l l a s c h r e b e r i and Polytrichum juniperinum. Mnium  spinulosum and R h y t i d i o p s i s robusta. c h a r a c t e r i s t i c on rocks i n slope types, are absent i n the ADM. TABLE 9. Tree data summary. A l l u v i a l Dry Moss f o r e s t type. S i t e index: 1) Height at 50 y r s . ( f t . ) 20 - 35 - 50 2) Height a t 100 y r s . ( f t . ) Pinus monticola 50 - 75 - 100 Pseudotsuga m e n z i e s i i 60 - 55 - 70 L a r i x o c c i d e n t a l i s 80 Tsuga h e t e r o p h y l l a (50) Pinus c o n t o r t a (50) P i c e a engelmannii (60) cont'd. 47. TABLE 9. (cont'd.) Stage 1 Stage 2 Basal area per acre (sq. f t , ) Number stems per acre Average diameter of stand ( i n . ) Average age of dominants ( y r s , ) Average height of dominants & codominants (131) (1235) (4.4) (190) (172) (5606) (2,6) (86) ( f t . ) (89) (60) A r a l i a Oakfern a s s o c i a t i o n ( A r a l i e t o - Gymnocarpietum) The A r a l i a Oakfern a s s o c i a t i o n l i e s adjacent to and below the Moss a s s o c i a t i o n on an i d e a l i z e d slope f o r the Subzone (ooo d o p e diagram Appendix F->. The environment g e n e r a l l y i s c o o l e r and moister than the Moss a s s o c i a -t i o n ; most s o i l s i n the 48 stands stu d i e d are u s u a l l y i n f l u e n c e d by permanent seepage or the watertable during the growing season. Stands are g e n e r a l l y not as extensive as those of the Moss a s s o c i a t i o n except p o s s i b l y on a l l u v i a l f l a t s where c o n d i t i o n s are sometimes uniform over hundreds of acres. Vegeta-t i o n i s g e n e r a l l y denser than the Moss a s s o c i a t i o n however, probably due to the greater a v a i l a b i l i t y of moisture. As w i t h the Moss a s s o c i a t i o n , the h i s t o r y preceding establishment of AO stands g e n e r a l l y i n c l u d e s f i r e . S e v e r e f i r e s which removed ground cover and humus from extensive areas were probably i n d i r e c t l y r e s p o n s i b l e f o r the r e l a t i v e abundance of c e r t a i n hardwood species and herbaceous r u d e r a l s i n young stands. Heavier seed and infr e q u e n t "good seed years" of c o n i f e r s might have extended the p e r i o d of c o n i f e r r e - c o l o n i z a t i o n over one or two decades i n s t e a d of the year or so necessary f o r l i g h t e r - s e e d e d species. Brown Woodeds, Minimal Podzols, O r t h i c Podzols, sometimes Regosols or G l e y s o l s , a l l of a deci d e d l y moist nature, make up the soil';.type i n the AO a s s o c i a t i o n . The n u t r i e n t - r i c h temporary seepage i n slope community s o i l s o f t e n compensates f o r the l e a c h i n g e f f e c t of p r e c i p i t a t i o n - c a r r i e d humic a c i d s 48. thereby m a i n t a i n i n g a pH i n the s o i l r o o t i n g l a y e r s which may be l e s s a c i d than i n comparable Moss a s s o c i a t i o n types. On the other hand, a c i d i t y of the upper horizons may be the highest of any found i n the Subzone i n those stands on c o o l , moist north exposures such stands might be considered r e p r e s e n t a t i v e of the c o o l e r , moister wet Subzone to the north. Tree growth i s g e n e r a l l y b e t t e r than i n the Moss a s s o c i a t i o n , at l e a s t f o r the pioneer c o n i f e r s , and the r a t i o of cedar to hemlock i s approximately 1 to 1, somewhat higher than i n the Moss a s s o c i a t i o n . The seven f o r e s t types described w i t h i n the A r a l i a Oakfern a s s o c i a t i o n are the Slope A r a l i a Oakfern (SAO), i t s pioneer hardwood v a r i a n t (SA0p)*, and i t s southern v a r i a n t (SAOs), Degraded A r a l i a Oakfern (DAO), and i t s northern v a r i a n t (DAOn), A l l u v i a l A r a l i a Oakfern (AAO), and the A l l u v i a l Bunchberry A r a l i a Oakfern (ABAO). The c h a r a c t e r i s t i c combination of species f o r the A r a l i a Oakfern a s s o c i a t i o n i s given i n Table 10. The d i s t r i b u t i o n of species i n constancy c l a s s e s i s i l l u s t r a t e d i n F i g . 20. 313 species i n 48 sample stands are i n c l u d e d i n the synthesis t a b l e f o r t h i s a s s o c i a t i o n . F i g . 21 a) and b) show cover of constant dominants, and the v e g e t a t i o n l i f e - f o r m spectrum r e s p e c t i v e l y , f o r the A r a l i a Oakfern a s s o c i a t i o n - In t h i s community, u n l i k e the Moss a s s o c i a t i o n , geophytes and hemicryptophytes are almost as prominent as chamaephytes. 1 The "pioneer hardwood v a r i a n t " , as the name i m p l i e s , i s stage 3 i n succession developing toward the climax SAO community, U n l i k e s u c c e s s i o n a l stages i n other f o r e s t types t h i s phytocoenose i s s u f f i c i e n t l y d i s t i n c t to warrant separate c o n s i d e r a t i o n . TABLE 10. CHARACTERISTIC COMBINATION OF SPECIES ARALIA-OAKFERN ASSOCIATION (ARALIETO-GYMNOCARPIETUM) + Constant dominant only i n t h i s a s s o c i a t i o n * Constant only i n t h i s a s s o c i a t i o n ! Most s u c c e s s f u l i n t h i s a s s o c i a t i o n but may be present i n adjacent communities 1 I n c l u d i n g a l l species Layer Trees Shrubs Herbs Constant dominants Thuja p l i c a t a Tsuga h e t e r o p h y l l a Pachistima m y r s i n i t e s Taxus b r e v i f o l i a Thuja p l i c a t a Tsuga h e t e r o p h y l l a 2 A r a l i a n u d i c a u l i s + C l i n t o n i a u n i f l o r a , Gymnocarpium d r y o p t e r i s T i a r e l l a u n i f o l i a t a Bryophytes & Lichens a) on humus Constants only Lonicera utahensis Rosa gymnocarpa Vaccinium membranaceum Goodyera o b l o n g i f o l i a Linnaea b o r e a l i s P y r o l a secunda Smilacina racemosa Important Non-constants .'Salix s c o u l e r i a n a .'Bromus v u l g a r i s .'Corallorhiza maculata C. mertensiana Rubus n i v a l i s R. pedatus .'Smilacina s t e l l a t a IStreptopus streptopoides .'Rhytidiadelphus loreus .'Peltigera p o l y d a c t y l a cont'd. ARALIA-OAKFERN ASSOCIATION (cont'd) Layer Constant dominants Constants only Important Non-constants b) on decaying wood Dicranum fuscescens C a l l i e r g o n e l l a s c h r e b e r i Dicranum s t r i c t u m Hypnum c i r c i n a l e Mnium spinulosum P t i l i d i u m pulcherrimum ^ R h y t i d i o p s i s robusta , • 1 Cladonia spp. „ , . 1 P e l t i g e r a spp. A r a l i a n u d i c a u l i s and Gymnocarpium d r y o p t e r i s both have constancy = 4 to f o l l o w page SO. F i g . 20. Constancy diagram f o r A r a l i a Oakfern a s s o c i a t i o n . U J O r. r70 •iO •10 •HO •io -to -15 0 313 S PP" I I 1 I 1 COMSf ft NO* PftCV\l$TtrlR MYdinJltES TAUOS anevifouifl T H O T P \ cucflrft  T s o f r l V H £ T E A u P H W L i f t  CunTOMA uNlfLO Aft CoA.M05 CflWflbEU^iS TcAftcU-A. UKUFOUrVffl a) •2 e o £ o o r-60 -50 -40 -JO - 1 0 .10 - 0 P* Pu £ H 6- M L LIFE FOftM _ l_ ID ao 3o 4o so 60 F i g . 21. A r a l i a Oakfern a s s o c i a t i o n : a) average cover of constant dominant species; b) veg e t a t i o n l i f e form spectrum based on cover of constant species. Pm megaphanerophytes; Pn nanophanerophytes; C chamaephytes; H hemlcryptophytes; G geophytes; M mosses; L l i c h e n s . 51, Slope A r a l i a Oakfern f o r e s t type (SAO) Fourteen stands r e p r e s e n t a t i v e of t h i s community were studied, ranging from l e s s than one to s e v e r a l acres. E l e v a t i o n s vary from 2025 feet i n a south-facing stand near Mabel Lake to 3300 f e e t at Stevens Pass near Arrow Park. Slopes are moderate to very steep (to 36° on a n o r t h - f a c i n g slope at Keen Creek near Kaslo) and exposures cover a l l p o i n t s of the compass. Topography i s more v a r i a b l e than i n the upslope Moss a s s o c i a t i o n g e n e r a l l y i n c l u d i n g a n e u t r a l p r o f i l e , though complex p r o f i l e s are not uncommon, the l a t t e r to some extent f a v o u r i n g convergence of moisture i n pockets. Contour i s o f t e n complex, sometimes convex, and o c c a s i o n a l l y concave, w h i l e surface c o n d i t i o n s w i t h i n each stand are o f t e n hummocky or i r r e g u l a r . S o i l s are c h a r a c t e r i s t i c a l l y moister than Moss communities w i t h Moist Minimal Podzols or Moist O r t h i c Podzols p r e v a l e n t i n climax stands, add Brown Woodeds (Grey Brown, and Gleyed A c i d Brown) prominent i n yourn stands p a r t i c u l a r l y on south exposures. Two stands i n the Caribou Creek area near Burton have Normal Minimal Podzols p o s s i b l y due to coarse-textured s o i l s founded on parent m a t e r i a l dominated by a c i d i c igneous rocks. Apart from p a r t i a l l y - c o m p a c t e d l a y e r s at 25 to 65 cms., no l a y e r s impervious to roots were encountered i n the s o i l p i t s . Thickness of the Ae h o r i z o n ranges from 0 i n young stands, to 4 cms. beneath t h i c k humus of a high e l e v a t i o n , north-e a s t - f a c i n g stand i n Stevens Pass. The leached l a y e r i s g e n e r a l l y t h i c k e s t i n climax stands on Moist O r t h i c Podzols. Texture of the main r o o t i n g h o r i z o n (often a B h o r i z o n leached of water s o l u b l e m a t e r i a l yet enriched w i t h hydrated i r o n and accumulated organic matter; and sometimes even a C horizon) v a r i e s from loam to g r a v e l l y loamy sand, more of the l a t t e r than the former. In e a r l y J u l y , 1960, a check f o r seepage water i n s o i l p i t s dug the previous season showed seepage l e v e l s from 45 to 76 cms. from the ground surface, w e l l 52. w i t h i n reach of tree r o o t s . pH of the main r o o t i n g h o r i z o n i s l e s s a c i d than that of the Moss a s s o c i a t i o n because of the upward c a p i l l a r y movement of n u t r i e n t - r i c h moist-ure from the seepage l a y e r c o u n t e r a c t i n g downward moving a c i d moisture which leaches the upper horizons. pH v a r i e s from an a c i d 5.0 i n the highest e l e v a t i o n (3300 f t . ) stand on g r a n i t i c parent m a t e r i a l at Stevens Pass to a s t r o n g l y b a s i s 7.8 i n the l i m e s t o n e - r i c h Trout Lake area. The two s o i l s i n the Trout Lake area w i t h t h i s h i g h pH support the h e a l t h i e s t , most vigorous white pine and D o u g l a s - f i r of a l l the stands s t u d i e d throughout the Subzone. pH of the organic l a y e r immediately above mineral s o i l may even reachas high as 7.5 i n Trout Lake stands near creeks which overflow i n f r e s h e t , although such b a s i c c o n d i t i o n s are unusual. pHs of the organic l a y e r are g e n e r a l l y higher than i n the Moss a s s o c i a t i o n p a r t i c u l a r l y i n younger stands. Apart from the extremely b a s i c value given above, pHs range from 3.5 i n a high e l e v a t i o n stand w i t h t h i c k Ae to 5.8 beneath a south-facing Trout Lake stand. Vegetation p a t t e r n i s f a i r l y uniform, w i t h heterogeneity u s u a l l y the re-s u l t of v a r i a t i o n i n a v a i l a b l e s o i l moisture, t h i s being i n f l u e n c e d by the nature of the microtopography or the p r o x i m i t y of small surface streams. As w i t h the Moss a s s o c i a t i o n , v a r i a t i o n i n l i g h t reaching the f o r e s t f l o o r has a marked i n f l u e n c e on d i s t r i b u t i o n of c e r t a i n herbs and shrubs. Stands are g e n e r a l l y denser than Moss a s s o c i a t i o n communities, w i t h the t r e e cover ranging from 65 - 95% and averaging 80. Tsuga h e t e r o p h y l l a and Thuja p l i c a t a dominate the t r e e cover, the former o f t e n i n e x c e l l e n t vigour, Pinus monticola and Pseudotsuga m e n z i e s i i may be prominent p a r t i c u l a r l y i n younger stands, and, l i k e hemlock, may be very vigorous i n some stands. B e t u l a p a p y r i f e r a and Populus tremuloides may be present and vigorous i n young stands yet are most abundant i n stands of the SAOp; even s c a t t e r e d Populus t r i c h o c a r p a may be found i n young stands though i t i s not very vigorous. to f o l l o w page 52. F i g . 22. 85 year o l d SAO stand dominated by vigorous Pinus monticola. Understory mainly Thuja p l i c a t a w i t h some Tsuga h e t e r o p h y l l a . August 14, 1961. F i g . 23. Ground v e g e t a t i o n i n young SAO stand: Asarum caudatum. T i a r e l l a u n i f o l i a t a . C l i n t o n i a u n i f l o r a . Note abundant white pine needles i n l i t t e r . August 14, 1961. 53. L a r i x o c c i d e n t a l i s . when present, i s s c a t t e r e d and u s u a l l y of low v i g o u r . Near i t s northern l i m i t s i n t h i s Subzone l a r c h grows w e l l o nly i n the mesic Moss a s s o c i a t i o n communities, p a r t i c u l a r l y the SBM. Shrub cover averages 35%, w i t h i n d i v i d u a l stands ranging from 3% beneath dense t r e e crowns i n young t h i c k e t s of pioneer c o n i f e r s to 70% i n more open stands. As i n the SNM, Pachistima m y r s i n i t e s dominates the shrub l a y e r , and i s q u i t e v i g o r o u s , but does not flower and set seed as w e l l as i n the warmer and d r i e r Moss communities, and i s almost e n t i r e l y r e s t r i c t e d to o l d decaying logs or t o r a i s e d humps of ground. Taxus b r e v i f o l i a codominates w i t h P a c h i s t i m a. being p a r t i c u l a r l y well-developed i n climax stands. Thuja  p l i c a t a and Tsuga h e t e r o p h y l l a are a l s o constant dominants, both w i t h p o t e n t i a l l y good v i g o u r but the l a t t e r species o f t e n r e s t r i c t e d to decaying wood. Other species common and h e a l t h y i n many stands are Rosa gymnocarpa and Vaccinium o v a l i f o l i u m and Corylus c a l i f o r n i c a . Vaccinium membranaceum and Lo n i c e r a utahensis though constant i n the SAO are r a r e l y v i g o r o u s , the former i n most cases growing, l i k e P achistima. on decaying wood. Other wet s i t e shrubs o c c a s i o n a l l y i n t r u d i n g i n the A r a l i a Oakfern a s s o c i a t i o n are Viburnum edule. Ribes l a c u s t r e . Rhamnus purshiana. Oplopanax  h o r r i d u s . and Alnus c r i s p a . Cover of the herb l a y e r v a r i e s from 1% beneath dense t r e e cover of some young stands t o 80% beneath some climax f o r e s t s . Average cover (40%) f o r the SAO i s much greater than e i t h e r the SNM or SBM, mainly r e f l e c t i n g the improved s o i l moisture i n t h i s f o r e s t type. A r a l i a n u d i c a u l i s . C l i n t o n i a u n i f l o r a . Cornus canadensis. Gymnocarpium  d r y o p t e r i s . and T i a r e l l a u n i f o l i a t a . a l l s o c i a b l e and v i g o r o u s , dominate the herb l a y e r i n the SAO. In many stands, s c a t t e r e d yet o f t e n vigorous Adenocaulon  b i c o l o r . Asarum caudatum. Disporum oreganum. Galium t r i f l o r u m . Osmorhiza c h i -l e n s i s . and T i a r e l l a t r i f o l i a t a may be found. Other u s u a l l y wet s i t e herbs 54. sometimes present i n depressions but r a r e l y vigorous are Actaea arguta. Athyrium f i l i x - f e m i n a . Botrychium v i r g i n i a n u m . C i r c a e a a l p i n a ( r a r e ) , D r y o p t e r i s a u s t r i c a ( u s u a l l y on decaying wood), Equisetum arvense ( i n young stands o n l y ) , L i s t e r a c o n v a l l a r i o i d e s . Lycopodium selago (mainly i n o l d e r s t a n d s ) , Streptopus a m p l e x i f o l i u s . S. roseus. and V i o l a g l a b e l l a . Although Chimaphila umbellata i s a constant species i t i s s c a t t e r e d and weak when growing i n the more a c i d s o i l s of climax stands. Goodyera oblong-i f o l i a . Linnaea b o r e a l i s . P y r o l a secunda and Smilacina racemosa are SAO constant s p e c i e s , the f i r s t being the only one averaging good vig o u r . Bryophytes on humus i n the SAO cover from l e s s than 1% i n some young stands to over 60% of the ground surface i n cli m a x stands. Hylocomium  splendens f R h y t i d i o p s i s robusta (both o f t e n i n e x c e l l e n t v i g o u r ) and C a l l i e r -g o n e l l a s c h r e b e r i ane dominant. Lophozia lycopodioides i s u s u a l l y p r esent, sometimes abundant i n o l d e r stands c h a r a c t e r i s t i c a l l y i n t e r m a t t e d w i t h C a l l i e r g o n e l l a s c h r e b e r i . P o h l i a  cruda may be found on mi n e r a l s o i l bared by r o o t upturn of windthrown t r e e s . P t i l i u m c r i s t a - c a s t r e n s i s may be common and vigorous as may be Rhytidiadelphus JLoreus, the l a t t e r c h a r a c t e r i s t i c a l l y r e s t r i c t e d t o o l d e r stands. Species c h a r a c t e r i s t i c of h a b i t a t s wetter than the SAO yet o f t e n present here u s u a l l y on moist patches are Bryum s a n d b e r g i i . Mnium i n s i g n e . M. punctatum. and P l a g i o c h i l a a s p l e n i o i d e s . In these moist h a b i t a t s l i c h e n s are v i r t u a l l y absent, those present being predominantly P e l t i g e r a species (mainly P. aphthosa), u s u a l l y of poor v i g o u r and o f t e n r e s t r i c t e d to mineral s o i l patches. Decaying wood supports a r i c h bryophyte f l o r a i n c l u d i n g dominant C a l l i e r g o n e l l a s c h r e b e r i , Cephalozia spp., Dicranum fuscescens, Mnium s p i n u l -osum and sometimes R h y t i d i o p s i s robusta and Hylocomium splendens. a l l u s u a l l y v i g o r o u s , sometimes e x c e p t i o n a l l y so. Dicranum s t r i c t u m . P t i l i d i u m to f o l l o w page 54. F i g . 24. Ground v e g e t a t i o n i n climax SAO stand; Gymnocarpium d r y o p t e r i s . S m i l a c i n a racemosa. Streptopus roseus. C l i n t o n i a u n i f l o r a , T i a r e l l a  u n i f o l i a t a . R h y t i d i o p s i s robusta. August 9, 1960. 55. pulcherrimum and Mnium spinulosum are c h a r a c t e r i s t i c a l l y constant, the l a s t o f t e n e x c e p t i o n a l l y v i g o r o u s . The v a r i e t y of bryophytes i n SAO communities on decaying wood i s much great e r than i n the Moss a s s o c i a t i o n . Some of the more i n t e r e s t i n g species s u c c e s s f u l l y e s t a b l i s h e d here are Amblystegium juratzkanum and A. serpens. Anastrophyllum minutum. Buxbaumia i n d u s i a t a . Climacium dendroides. Lescuraea  i n c u r v a t a . Lophozia a t t e n u a t a . L. longidens. Oncophorus w a h l e n b e r g i i . Tet r a p h i s g e n i c u l a t a . Thuidium recognitum and T r i t o m a r i a e x s e c t i f o r m i s . Others are l i s t e d i n the s y n t h e s i s t a b l e , Appendix F. Only two l i c h e n s are common here, P e l t i g e r a aphthosa and P. p o l v d a c t y l a . both i n v a r i a b l y present and vigorous on very o l d moss-covered decaying wood of climax stands. C l a d o n i a f i m b r i a t a and Nephroma spp. (mainly N. laevigatum) may be present on o l d logs f r e e of moss, along w i t h a v a r i e t y of other low vi g o u r Cladonia s p e c i e s , c h a r a c t e r i s t i c of decaying wood i n many f o r e s t types, such as C. b e l l i d i f l o r a . C. c a r n e o l a . C. chlorophaea. C. coniocraea. C. nemoxyna and C. p o l y d a c t y l a . Apart from those mentioned as dominants, the few r a r e l i c h e n s which may be vigorous when present are Icmadophila ericetorum. Pannaria p e z i z o i d e s . P e l t i g e r a h o r i z o n t a l i s and P. membranacea. and some-times L o b a r i a pulmonaria. The only bryophytes common on rock are Mnium spinulosum and Lophozia  l y c o p o d i o i d e s . the former being present i n f a i r vigour i n almost every stand. Nephroma spp. are the only l i c h e n s commonly found w i t h good v i g o u r . Many other bryophytes and l i c h e n s present i n only one or two stands, and of l i t t l e d i a g n o s t i c v a l u e , are l i s t e d i n the synt h e s i s t a b l e s . Data on tree growth and importance i s summarized as f o l l o w s : 56. TABLE 11. Tree data summary. Slope A r a l i a Oakfern f o r e s t type. S i t e index: a) b) Height a t 50 years ( f t . ) Height at 100 years ( f t . ) 70 - 90 - 100 Pinus monticola 110 - 140 - 160 Pseudotsuga m e n z i e s i i 110 - 115 - 130 Tsuga h e t e r o p h y l l a 80 - 100 - 120 Thuia p l i c a t a 90 - 100 - 110 P i c e a engelmannii 100 - 120 - 140 L a r i x o c c i d e n t a l i s 110 - 115 - 120 Populus tremuloides (130) Average maximum height ( f t . ) ; diameter of t r e e of average maximum height ( i n . ) : 144 - 153 - 171; 27.1-31.2- 37.3 Pseudotsuga m e n z i e s i i 132 - 144 - 161; 23.0-33.2- 40.9 Tsuga h e t e r o p h y l l a 108 - 123 - 136; 22.3-27.4- 38.0 123 - 131 - 137; 29.7-35.3- 43.0 (139; 28.0) Basal area per acre (sq. f t . ) Number tre e s per acre Average diameter of stand ( i n . ) Average age of dominants (yrs.) Average h e i g h t of dominants & codominants ( f t . ) Secondary succession index Stage 1 278-398-655 230-453-780 8.1-13.8-19.6 200+-225+-250+ 107-129-143 100% Stage 2 229-332-544 676-1356-2955 4.2-7.0-9.0 62-73-90 96-116-144 72% (Stage 3 49%) Slope A r a l i a Oakfern. pioneer hardwood v a r i a n t , f o r e s t type (SAOp) Th i s community i s Stage 3 (the e a r l i e s t f o r e s t e d stage i n secondary succession) of the SAO type. I t s v e g e t a t i o n i s s u f f i c i e n t l y d i s t i n c t from the other stages however, to a l l o w separation i n t o a separate f o r e s t type. A l t o g e t h e r , f i v e stands of t h i s f o r e s t type were s t u d i e d , a l l young and f a i r l y open, and g e n e r a l l y on southern exposures w i t h slopes ranging from 2 - 32°. Stands vary i n s i z e from 1 to s e v e r a l acres and topography i s q u i t e v a r i a b l e . Contour i s u s u a l l y convex, p r o f i l e may be complex, concave, * Stage 3 i n t h i s type i s f l o r i s t i c a l l y so d i s t i n c t that i t i s described s e p a r a t e l y as the Slope A r a l i a Oakfern "pioneer hardwood v a r i a n t " f o r e s t type (SAOp). to follow page 56. F i g . 25. Young SAOp stand showing vigorous Populus  tremuloides ( l e f t ) , Pinus monticola and Pseudotsuga  menziesii (both r i g h t ) with Thuja p l i c a t a f i l l i n g i n below. Note Smilacina racemosa at base of aspen. Stand 100 years o l d . August 2, 1960. 57. convex or n e u t r a l , and ground surface may be n e u t r a l to hummocky. S o i l s are g e n e r a l l y Brown Wooded (Normal O r t h i s A c i d , Gleyed A c i d , Gleyed) i n c o n t r a s t to the a c i d Podzols u s u a l l y found i n the t y p i c a l SAO. Thi s may be due to a considerable extent to the h i s t o r y of severe f i r e which c l e a r e d wide areas before these stands became e s t a b l i s h e d , thus re-moving the humus and upper mineral l a y e r s (the l a t t e r by e r o s i o n f o l l o w i n g f i r e ) and t h e r e f y r e v e r t i n g s o i l succession from climax Podzol to Brown h Wooded s o i l . Apart from t h i n n e r Ae hor i z o n s (0-2 cm.), and l e s s a c i d main r o o t i n g h o r i z o n (pH 6.0 - 7.8) and organic h o r i z o n immediately above mineral s o i l (pH 5.0 - 5.6), the s o i l s are s i m i l a r to the t y p i c a l SAO. In a d d i t i o n to the greater number of pioneer hardwoods (Betula  p a p y r i f e r a . Populas tremuloides and sometimes even S a l i x s c o u l e r i a n a ) i h s t h e SAOp than i n the SAO, a number of shrubs, herbs and bryophytes c h a r a c t e r i z e the SAOp. Some species are s i g n i f i c a n t by t h e i r absence. Rubus p a r v i f l o r a s may be e x c e p t i o n a l l y abundant w h i l e Taxus b r e v i f o l i a , u s u a l l y common and vigorous i n climax stands of the SAO, i s r a r e l y present. B e t u l a p a p y r i f e r a and Populus tremuloides regeneration may be found i n SAOp stands, and Lo n i c e r a i n v o l u c r a t a . though not always present, may be common. D i s t i n g u i s h i n g c h a r a c t e r i s t i c s of the herb l a y e r are the usual absence of Gvmnocarpium d r v o p t e r i a and T i a r e l l a u n i f o l i a t a . T i a r e l l a t r i f o l i a t a . Lycopodium selago. and S m i l a c i n a s t e l l a t a are not present i n any of the SAOp stands s t u d i e d . F r a g a r i a b r a c t e a t a . A s t e r spp. and sometimes Epilobium  a n g u s t i f o l i u m are o c c a s i o n a l l y abundant i n t h i s pioneer stage, r a r e l y being found i n the t y p i c a l SAO. Linnaea b o r e a l l s and P t e r i d i u m aquilinum. while present i n most stands of the SAO, are o f t e n most abundant and v i g o r o u r i n the SAOp. Probably because of the f i r e and er o s i o n h i s t o r y of these stands and t h e i r r e l a t i v e growth, cover of bryophytes and l i c h e n s i s sparse i n a l l 58. stands, never exceeding 10%. I n s u f f i c i e n t humus has accumulated t o a l l o w the eventual moss dominants ( C a l l i e r g o n e l l a s c h r e b e r i , Hylocomium splendens and R h y t i d i o p s i s robusta) to become w e l l e s t a b l i s h e d . Most bryophytes and l i c h e n s are found on moist patches or on bare mineral s o i l , never i n more than small amounts. Decaying wood and rocks support a f l o r a s i m i l a r to t h a t of the t y p i c a l SAO but much reduced i n abundance f o r the reasons given above. Tree data i s summarized as f o l l o w s : TABLE 12. Tree data summary. Slope A r a l i a Oakfern, pioneer hardwood v a r i a n t , f o r e s t type. S i t e index: a) Height at 50 years ( f t . ) 80 - 95 - 110 b) Height at 100 years ( f t . ) Pinus monticola 160 P. c o n t o r t a (110) Pseudotsuga m e n z i e s i i 110 - 115 - 120 Thuja p l i c a t a (120) L a r i x o c c i d e n t a l i s " I ; - li'O - .120 - 130 Be t u l a p a p y r i f e r a (70) Populus tremuloides 70 - J35 - 100 Basal area per acre (sq. f t . ) 69 - 221 - 349 Number tre e s per acre 270 - 810 - 2105 Average diameter of stand ( i n . ) 2.4 - 8.5 - 10.9 Average age of dominants ( y r s . ) 28 - 72 - 101 Average height of dominants & codominants ( f t . ) 57 - 110 - 145 Secondary succession index 49% Slope A r a l i a Oakfern. southern v a r i a n t , f o r e s t type (SAOs) As i n the Moss a s s o c i a t i o n c e r t a i n communities i n the southern p a r t of the Subzone may be set apart as c l i m a t i c v a r i a n t s under the i n f l u e n c e of a d r i e r and warmer macroclimate. Stands are c h a r a c t e r i z e d by the presence of Abies grandis i n the t r e e l a y e r and by reduced v i g o u r and abundance of Tsuga h e t e r o p h y l l a . The l e s s - a c i d s e i l s (than SAO), as i n f l u e n c e d by a m i l d e r c l i m a t e , undoubtedly c o n t r i b u t e to t h i s s i t u a t i o n . 59. The three stands s t u d i e d d i f f e r from the t y p i c a l SAO i n that they are a l l southern communities on steep southwest exposures. S o i l s are Brown Woodeds w i t h no Ae h o r i z o n ; the Normal O r t h i c Brown Woodeds c h a r a c t e r i s t i c of younger stands are found only i n the SAOs. pH of the main r o o t i n g h o r i z o n s (6.0 - 7.0) and organic l a y e r s (5.2 - 6.3) are s i m i l a r t o those of the SAOp i n that they are l e s s a c i d than i n the t y p i c a l SAO stands. The tr e e l a y e r d i f f e r s from the SAO i n that Abies grandis i s present; i t i s common and vigorous i n young stands and tends to drop out of climax stands. In the stands s t u d i e d , Populus tremuloides i s absent and Tsuga  h e t e r o p h y l l a . i s g e n e r a l l y reduced i n importance and v i g o u r . As i n most SAO stands Pachistima m y r s i n i t e s dominates the shrubs. Taxus  b r e v i f o l i a , a species a l s o prominent i n other stands, may be e x c e p t i o n a l l y abundant and vigorous p a r t i c u l a r l y i n climax stands of the SAOs. Symphori-carpos albus i s common i n young stands w h i l e hemlock regeneration and Vaccinium membranaceum i s c o n s i d e r a b l y reduced, o f t e n being confined to de-caying wood. A good d i f f e r e n t i a t i n g herb f o r t h i s community i s 3 - r i l l i u m ovatum. A l -though never abundant or v i g o r o u s , i t s presence i n slope communities appears d i a g n o s t i c f o r the SAOs, and p o s s i b l y f o r southern v a r i a t i o n s of D e v i l ' s Club communities. C h a r a c t e r i s t i c s of the herb l a y e r which c o n t r a s t with the SAO are: the r e l a t i v e abundance and good v i g o u r of S m i l a c i n a s t e l l a t a . p a r t i c u l a r l y i n younger stands; the presence i n a l l stands of Asarum caudatum. u s u a l l y on moist spots; the complete absence of Cornus conadensis. P y r o l a  c h l o r a n t h a . Lycopodium selago and Streptopus roseus (present i n a wide range of communities f a r t h e r n o r t h ) ; and the reduced constancy, abundance and v i g o u r of Gymnocarpium d r y o p t e r i s (found i n only one stand), T i a r e l l a u n i -f o l i a t a and C l i n t o n i a u n i f l o r a . Bryophytes and l i c h e n s i n a l l stands are c h a r a c t e r i s t i c a l l y sparse on 60. humus, p o s s i b l y because of abundant l e a f f a l l ( c o n i f e r and hardwoods), which maintains a loose, dry, w e l l - a e r a t e d l i t t e r c o v e r i n g the s o i l . The maximum bryophyte and l i c h e n cover i s i n climax stands yet even there most p l a n t s are on decaying wood. Although much reduced, the f l o r a on humus i s s i m i l a r to the t y p i c a l SAO but C a l l i e r g o n e l l a s c h r e b e r i and Hylocomium  splendens are absent. R h y t i d i o p s i s robusta i s present i n a l l stands but u s u a l l y of low v i g o u r . M i n e r a l s o i l and wet pockets are c o l o n i z e d by s c a t t e r e d Brachythecium. Eurhynchium and some Mnium species (M. punctatum and M. i n s i g n e . the l a t t e r being the only one w i t h f a i r v i g o u r ) . A v a r i e t y of l i c h e n s i s a l s o present and i s d i s t i n g u i s h e d from the SAO by the complete absence of P e l t i g e r a aphthosa and r e l a t i v e l y good vi g o u r and constancy of P. canina p a r t i c u l a r l y on decaying wood. Tree data i s summarized as f o l l o w s : TABLE 13. Tree data summary. Slope A r a l i a Oakfern, southern v a r i a n t , f o r e s t type. S i t e index: a) Height at 50 years ( f t . ) 7 0 - 8 0 - 9 0 b) Height at 100 years ( f t . ) Pinus monticola 100 - 115 - 120 Pseudotsuga m e n z i e s i i 100 - 105 - 110 Tsuga h e t e r o p h y l l a (100) Thuja p l i c a t a (90) Pi c e a engelmannii (100) L a r i x o c c i d e n t a l i s (110) Abies grandis (110) Average maximum height ( f t . ) ; diameter of tree of average maximum height ( i n . ) Pinus monticola (169; 37.4) Tsuga h e t e r o p h y l l a (131; 29.1) Thuja p l i c a t a (129; 42.5) Stage 1 Stage 2 Basal area per acre (sq. f t . ) (420) 207 - 315 - 424 Number stems per acre (457) 676 - 903 - 1130 Average diameter of stand ( i n . ) (13.0) 5.8 - 8.3 - 10.7 Average age of dominants (yrs.) (108) 73 - . 21 - 110 Average height of dominants & codominants ( f t . ) (158) 101 - 116 - 130 61. Degraded A r a l i a Oakfern f o r e s t type (DAP) Some very o l d stands, o b v i o u s l y undisturbed f o r many c e n t u r i e s , occupy c o o l moist h a b i t a t s comparable to some of the SAO. Such stands are apparent-l y a f u r t h e r s u c c e s s i o n a l development of the SAO, developing only i n c o o l moist s i t u a t i o n s on no r t h slopes and/or at high e l e v a t i o n s p o s s i b l y comparable to h a b i t a t s supporting the Cornus canadensis - D r y o p t e r i s linnaeana a s s o c i -a t i o n described by K r a j i n a (1953) f o r the north Subzone. They are c a l l e d "degraded" because, over hundreds of year s , without d i s t u r b a n c e , the s o i l s have become markedly a c i d , and t h i c k accumulations of organic matter have developed. The complete absence of many neutrophilous s p e c i e s , common i n SAO stands, r e f l e c t s the reduced p r o d u c t i v i t y . Tree growth i s a l s o somewhat depressed when compared with the SAO. The s i x stands s t u d i e d of the DAO g e n e r a l l y occur at higher e l e v a t i o n s and on more moderate slopes than the SAO. S o i l s d i f f e r from the SAO i n t h a t s o i l types are u s u a l l y e i t h e r Normal O r t h i c Podzols, or O r t s t e i n Podzols. One stand on a l l u v i a l parent m a t e r i a l has a Moist O r t h i c Podzol. S o i l depth i s of t e n determined by the presence of an o r s t e i n l a y e r from 7 to 106 cms. bensath the surface. Ae l a y e r s i n a l l stands are c h a r a c t e r i s t i c a l l y t h i c k , 2 - 1 6 cms. i n the stands s t u d i e d . pH i s low, 4.2 - 5.6 being the range i n main r o o t i n g h o r i z o n s , and 3.4 - 4.0 being c h a r a c t e r i s t i c of the organic l a y e r immediately above mineral s o i l . In- the herb l a y e r at l e a s t , v e g e t a t i o n p a t t e r n may be marked, w i t h con-tagious d i s t r i b u t i o n s more prominent than i n the l e s s s t a b l e v e g e t a t i o n of young s e r a i stands. This may be due mainly to v a r i a t i o n s i n the a v a i l a b i l i t y of s o i l moisture at d i f f e r e n t p o i n t s on the ground s u r f a c e , and s e c o n d a r i l y to v a r i a t i o n s i n the amount of l i g h t reaching the f o r e s t f l o o r . In moist depressions or where an o l d hemlock has f a l l e n w i t h i n the l a s t century, producing an opening i n the canopy, herb cover i s g e n e r a l l y more abundant. to follow page 61. F i g . 26. Ground vegetation i n DAO stand: abundant, vigorous Streptopus streptopoides and Rubus pedatus indicate thick a c i d humus; other species are Gymnocarpium dr y o p t e r i s . T i a r e l l a u n i f o l i a t a . C l i n t o n i a  u n i f l o r a and Rhytidiopsis robusta. August 9, 1960. 62. Fewer species are found i n these stands than i n the SAO. The t r e e l a y e r of climax DAO stands i s composed almost e n t i r e l y of Tsuga h e t e r o p h y l l a . A l l other t r e e s p e c i e s , w i t h the exception of one or two low v i g o u r Thuja  p l i c a t a and an o c c a s i o n a l Pseudotsuga m e n z i e s i i or Pinus monticola have already dropped out of the stands, and cannot reappear unless the present stand, as w e l l as the t h i c k mor humus l a y e r , i s removed. As i n the SAO, Pachistima m y r s i n i t e s dominates the shrub l a y e r but grows mainly on decaying wood or on r a i s e d ground. Taxus b r e v i f o l i a and hemlock reg e n e r a t i o n are abundant, o f t e n on decaying wood, w h i l e Vaccinium membran-aceum may be more abundant here than i n any other A r a l i a Oakfern f o r e s t type, but never i n good v i g o u r unless on decaying wood. Shrubs common i n other A r a l i a Oakfern f o r e s t types, but u s u a l l y absent i n the DAO, are Acer glabrum. Rosa gymnocarpa. Rubus p a r v i f l o r u s and Viburnum  edule. Herbs i n c l u d e Galium t r i f l o r u m . Actaea arguta. Adenocaulon b i c o l o r . Asarum caudatum. Botrychium v i r g i n i a n u m . Eguiseturn arvense. P t e r i d i u m aqui-linum and S m i l a c i n a racemosa. More c h a r a c t e r i s t i c of the DAO herb l a y e r i s the abundance and good v i g o u r of Streptopus streptopoides and Rubus pedatus. Both are e x c e p t i o n a l l y good d i f f e r e n t i a t i n g species f o r t h i s community, A r a l i a n u d i c a u l i s i s found here i n yodung stands o n l y , yet Gymnocarpium d r y o p t e r i s and T i a r e l l a u n i f o l i a t a are both dominant and vigorous i n most stands. Chimaphila umbellata, although present i n many stands, i s r a r e l y common or vigorous. The b r y o f l o r a on the t h i c k raw humus i s much the same as i n the o l d e r stands of the SAO, yet the dominant C a l l i e r g o n e l l a s c h r e b e r i . Hylocomium  splendens. P t i l i u m c r i s t a - c a s t r e n s i s and R h y t i d i o p s i s robusta are even b e t t e r e s t a b l i s h e d , w i t h concomitant r e d u c t i o n of other bryophytes common to the slope AO communities. Lophozia lycopodoides and Mnium spinulosum are c h a r a c t e r i s t i c a l l y absent. 63. Decaying wood a l s o supports a s i m i l a r yet more abundant f l o r a than the SAO, undoubtedly because more decaying wood has accumulated through cen-t u r i e s without disturbance. Many taxonomically d i f f i c u l t Cephalozia spp. are common on the sides of well-decayed logs i n the DAO. Dicranum fuscescens I s notable f o r i t s e x c e l l e n t v i g o u r here. Tree data i s summarized as f o l l o w s : TABLE 14. Tree data summary. Degraded A r a l i a Oakfern f o r e s t type. S i t e index: a) Height a t 50 years ( f t . ) 60 - 8 0 - 9 0 b) Height at 100 years ( f t . ) Pinus monticola 110 -• 120 - 140 Pseudotsuga m e n z i e s i i 100 -• 115 - 130 Tsuga h e t e r o p h y l l a 80 - 90 - 100 Average maximum height ( f t . ) ; diameter of t r e e of average maximum height Pinus monticola 140 - 144 - 147; 26.7-31.7-36.6 Tsuga h e t e r o p h y l l a 110 - 120 - 130; (29.4) Stage 1 Stage 2 Basal area per acre (sq. f t . ) 237 - 340 - 529 297 - 308 - 318 Number stems per acre 365 - 641 - 800 585 - 725 - 865 Average diameter of stand ( i n . ) 7.8 -10.0 -12.8 8.2 - 8.9 - 9.6 Average age of dominants (yrs.) 132 - 25OI-300+- 80 . Average height of dominants & codominants ( f t . ) 111 - 122 - 140 (127) Degraded A r a l i a Oakfern. northern v a r i a n t , f o r e s t type (DAOn) This community i s s i m i l a r to the t y p i c a l DAO but i s found i n v a r i a b l y i n the c o o l e s t l o c a l e s , u s u a l l y northern exposures at high e l e v a t i o n s . From n o r t h to south, i t i s found at p r o g r e s s i v e l y higher e l e v a t i o n s . Vegetation does not d i f f e r very much from the DAO except that Thuja  p l i c a t a i s o c c a s i o n a l l y prominent i n the t r e e l a y e r , that Hylocomium splendens i s r a r e on humus, and th a t Lophozia l y c o p o d i o i d e s . Mnium spinulosum and Plagiothecium denticulatum are f a i r l y common i n most stands, u s u a l l y on mineral s o i l . R h y t i d i o p s i s robusta i s c l e a r l y the moss dominant, o f t e n more vigorous than anywhere e l s e i n the Subzone. This r e f l e c t s the c o o l subalpine 64. i n f l u e n c e i n these stands. The g r e a t e r p r o p o r t i o n of neutrophilous species and p o s s i b l y the l e s s a c i d nature of the s o i l types (Moist Minimal Podzols, Normal Minimal Podzols, and Normal O r t h i c A c i d Brown Woodeds) may be due i n p a r t to the c o n s i s t e n t l y steep slopes of the stands s t u d i e d (19° - 33°). Steep slopes a l l o w r a p i d s o i l creep thus keeping the upper s o i l l a y e r s more mixed than i n s o i l s on shallower slopes. As a r e s u l t of t h i s surface s o i l i n s t a b i l i t y , mineral s o i l f r e q u e n t l y may be exposed at the s u r f a c e , thus f a v o r i n g the e s t a b l i s h -ment of species more neutrophilous than one might expect i n such stands. Such species i n c l u d e Lophocolea h e t e r o p h y l l a . Blepharostoma t r i c h o p h y l l u m . Mnium punctatum. Lophozia porphyroleuca and Rhodobrvum roseum as w e l l as the bryophytes mentioned e a r l i e r . Other species never common but when present i n d i c a t i n g the e c o l o g i c a l p r o x i m i t y of some of these stands to sub-a l p i n e f o r e s t community are: Menziesia f e r r u g i n e a . Lycopodium clavaturn. Polystichum l o n c h i t i s . and Timmia a u s t r i a c a . P r e d i c t a b l y , on steep s l o p e s , the amount of r o t t i n g wood a v a i l a b l e f o r c o l o n i z a t i o n i s l e s s than i n stands on moderate slopes to f l a t ground. Bryo-phyte cover on decaying wood i s u s u a l l y sparse, yet composition i s much the same as the DAO. Tree data i s summarised as f o l l o w s : TABLE 15. Tree data summary. Degraded A r a l i a Oakfern, northern v a r i a n t , f o r e s t type. S i t e index: a) Height a t 50 years ( f t . ) 7 0 - 7 5 - 8 0 b) Height at 100 years ( f t . ) Pinus monticola 110 Pseudotsuga m e n z i e s i i (110) Tsuga h e t e r o p h y l l a 80 - 100 - 110 Thuja p l i c a t a 100 - 105 - 110 L a r i x o c c i d e n t a l i s 100 - 110 - 120 cont'd. 65. TABLE 15. (cont'd) Average maximum height ( f t . ) ; diameter of t r e e of average maximum height ( i n . ) : Pinus monticola 140-144-147: 26.7 - 31.7-36.6 Tsuga h e t e r o p h y l l a B a s a l area per acre (sq. f t . ) Number stems per acre Average diameter of stand ( i n . ) Average age of dominants ( y r s i ) Average height of dominants & codominants ( f t . ) 110-120-130: , (29.4) Stage 1 Stage 2 242 - 209 - 307 (266) 85 - 422 - 875 (1150) 7.7 -15.3 -28.0 (6.5) 200+- 270+- 300+ (105) 114 - 134 - 141 (119) A l l u v i a l A r a l i a Oakfern. f o r e s t type (AAO) Two f o r e s t types on a l l u v i a l f l a t s are recognized, the AAO and the ABAO, the l a t t e r p o s s i b l y r e p r e s e n t i n g an e c o l o g i c a l t r a n s i t i o n between the AAO and the ANM. In the Moss a s s o c i a t i o n s o i l moisture may be at a premium during the growing season t h e r e f o r e t e x t u r a l d i f f e r e n c e s , as between g l a c i a l t i l l and a l l u v i u m , may be c r i t i c a l i n determining what species c o l o n i z e . Where ade-quate moisture i s a v a i l a b l e , as i n AO communities, the i n f l u e n c e of t e x t u r e i s minimized. This may be why there are few species d i s t i n g u i s h i n g a l l u v i a l from slope A r a l i a Oakfern communities, w h i l e i n the Moss a s s o c i a t i o n , where moisture may be c r i t i c a l f o r a number of species, the d i s t i n c t i o n i s q u i t e marked. The AAO d i f f e r s from the SAO i n t h a t a l l stands occur on a l l u v i a l f l a t s near r i v e r s or l a r g e streams which may be subject to p e r i o d i c f l o o d s . S o i l s are g e n e r a l l y f i n e - t e x t u r e d loams to sandy loams and are t h e r e f o r e r e l a t i v e -l y m o i st, supporting some e x c e p t i o n a l l y vigorous v e g e t a t i o n . In c o n t r a s t to the O r t h i c Podzols, Minimal Podzols and Brown Wooded s o i l s of the SAO, many "younger" s o i l types are found i n the AAO i n c l u d i n g Mor Regosols, Duff M u l l Regosols, O r t h i c Regosols and Gleyed A c i d Brown Woodeds. The one Gleyed to f o l l o w page 65. F i g . 27. Mature AAO stand on a l l u v i a l outwash. Pinus monticola ( l e f t ) and Pseudotsuga m e n z i e s i i ( r i g h t and center) w i t h Thuja p l i c a t a of a l l ages f i l l i n g i n below. August 18, 1961. 66. Brown Fo r e s t s o i l type occurs i n a stand l y i n g against the base of a mountain slope near Burton''. The leached l a y e r i s never more than a t r a c e and i s o f t e n absent. pH range of the main r o o t i n g h o r i z o n i s s i m i l a r to the SAO (5.0 - 6.4), as i s the pH range of the organic l a y e r immediately above m i n e r a l s o i l (4.2 - 5.6). Although Populus t r i c h o c a r p a may be e x c e p t i o n a l l y vigorous and common, and Alnus t e n u i f o l i a may be found o c c a s i o n a l l y , the v e g e t a t i o n composition of the t r e e l a y e r d i f f e r s l i t t l e from the SAO. The tre e canopy may be some-what denser, and i n young stands B e t u l a p a p y r i f e r a may be abundant and vigorous beneath t a l l Populus t r i c h o c a r p a . P. tremuloides i s r a r e l y present and when found i s of low v i g o u r . P i c e a engelmannii i s present i n most stands and i s sometimes e x c e p t i o n a l l y v i g o r o u s . Pachistima m y r s i n i t e s i s o f t e n absent from the AAO. Shrubs which may be s i g n i f i c a n t d i a g n o s t i c a l l y , at l e a s t f o r wet a l l u v i a l s i t e s g e n e r a l l y , are Rubus pubescens. Symphoricarpos a l b u s . Physocarpus c a p i t a t u s and Alnus t e n u i f o l i a , the f i r s t two being the only ones that are o c c a s i o n a l l y common and vigorous. Few fe a t u r e s of the herb l a y e r c h a r a c t e r i z e the AAO. The dominants A r a l i a n u d i c a u l i s . C l i n t o n i a u n i f l o r a and Gymnocarpium d r y o p t e r i s . as w e l l as the l e s s prominent C o r a l l o r h i z a maculata. Asarum caudatum and Adenocaulon b i c o l o r , have e x c e l l e n t v i g o u r . Two p o s s i b l y d i a g n o s t i c herbs which are o f t e n common and vigorous are Equisetum pratense and Bromus v u l g a r i s , the former i n young and the l a t t e r i n o l d stands. Although present i n only one stand s t u d i e d , Rubus n i v a l i s was abundant and vigo r o u s . Other s p e c i e s , some of which undoubtedly achieve t h e i r optimum i n D e v i l ' s Club communities are Adianturn pedatum. Aruncus v u l g a r i s . Equisetum  hiemale. E. s y l v a t i c u m , P e t a s i t e s f r i g i d u s and T i a r e l l a l a c i n i a t a . Some stands may occur where a l l u v i a l f l a t s abut against bases of mountain slopes. Provided a l l u v i u m i s s u f f i c i e n t l y f i n e to h o l d moisture, such AAO fragments are u s u a l l y maintained by downslope seepage. 0 i - c - - - » *i\ .*... .'.£:: 1., to follow page 66. F i g . 28. Ground vegetation beneath young AAO stand: A r a l i a nudicaulis and Equisetum pratense. Abundant annual f a l l of cottonwood and bir c h leaves forms nutrient r i c h l i t t e r yet impedes bryophyte estab-lishment. July 14, 1960. F i g . 29. Dense Epilobium angustifolium and Rubus  p a r v i f l o r u s on AAO s i t e s a f t e r logging and burning hinders c o n i f e r establishment. August 3, 1960. 67. Bryophyte cover on humus i s s i m i l a r to the SAO both i n amount and composition, except that Mnium punctatum. M. a f f i n e , other Mnium spp., as w e l l as Plagiothecium sylvaticum may be abundant i n the wetter stands and R h y t i d i a l e l p h u s t r i q u e t r u s may be frequent and vigorous i n those of normal moisture. C a l l i e r g o n e l l a s c h r e b e r i . Hylocomium splendens. P t i l i u m c r i s t a -c a s t r e n s i s and R h y t i d i o p s i s robusta are the constant dominants i n a l l o l d stands w i t h extensive bryophyte cover. In none of the young stands s t u d i e d , however, does bryophyte cover on humus exceed 2%. Most bryophyte and l i c h e n (very few) cover i n young stands i s r e s t r i c t e d to decaying wood where moisture and n u t r i e n t s are r e a d i l y a v a i l a b l e . In a d d i t i o n , heavy annual l e a f f a l l g e n e r a l l y does not accumulate on decaying l o g s , t h e r e f o r e bryophytes are not annually " s u f f o c a t e d " as they may be on the ground where hardwood l e a f cover o f t e n forms an almost impenetrable wet-paper-like blanket c o v e r i n g l a r g e areas. Jamesoniella autumnalis. Lophocolea h e t e r o p h y l l a and many Lophozia spp. are a l l more common and vigorous i n the AAO than the SAO. Tree data i s summarized as f o l l o w s : TABLE 16. Tree data summary. A l l u v i a l A r a l i a Oakfern f o r e s t type. S i t e index: a) Height at 50 years ( f t . ) b) Height at 100 years ( f t . ) Pinus m o n t i c o l a  Pseudotsuga m e n z i e s i i  Tsuga h e t e r o p h y l l a  Thuja p l i c a t a  P i c e a engelmannii  L a r i x o c c i d e n t a l i s  B e t u l a p a p y r i f e r a  Populus t r i c h o c a r p a Average maximum height ( f t . ) ; diameter of tree of average maximum height (in.jB; Pinus m onticola 137-139-141: 28.0 - 28.7 - 29.4 Tsuga h e t e r o p h y l l a 114-119-122: 20.2 - 35.1 - 26.0 Thuja p l i c a t a 122-129-136: 34.7 - 38.5 - 42.2 P i c e a engelmannii 134-136-138: 18.6 - 19.6 - 20.5 70 - 95 - 110 110 - 145 - 170 120 - 125 - 130 90 - 55 - 100 90 - 110 - 130 100 - 115 - 140 (110) (90) 120 - 135 - 140 TABLE 16. (cont'd) Stage 1 Stage 2 Stage 3 B a s a l area per acre (sq. f t . ) 337 - 440 - 506 198 - 257 - 310 238 - 244 - 249 Number stems per acre 290 - 357 - 430 1040 -1652 -2635 1090 -1193 -1295 Average diameter of stand ( i n . ) 13.3-15.2 -17.9 3.7 - 5J3 - 6.9 5.9 - J*A - 6.3 Average age of dominants (yrs.) 17Of-210+-25Of 46 - _59 - 76 56 - _60 - 63 Average height of dominants & codominants ( f t . ) 118 - 128 - 137 89 - 106 - 121 105 - 114 - 122 A l l u v i a l Bunchberry A r a l i a Oakfern. f o r e s t type (ABAO) 69. The ABAO appears t r a n s i t i o n a l between the AAO and the ANM. F o r i s t i c -a l l y , however, i t i s property i n c l u d e d i n the AO a s s o c i a t i o n even though e d a p h i c a l l y , apart from land form and parent m a t e r i a l , i t approximates the SBM q u i t e c l o s e l y . U n l i k e the AAO, the ABAO stands are u s u a l l y f u r t h e r from r i v e r s , occu r on f l a t s r a i s e d s l i g h t l y higher above the water t a b l e and are u n d e r l a i n by coarser textured parent m a t e r i a l s ( g r a v e l l y loamy sands t o sandy loams). Consequently they are e d a p h i c a l l y d r i e r and more a c i d than the AAO, the s o i l being more under the i n f l u e n c e of p r e c i p i t a t i o n . In s o i l types the only s i m i l a r i t y w i t h the SAO i s found i n one stand which has a Normal Minimal Podzol. Most s o i l s are Normal O r t h i c Podzols, a c h a r a c t e r i s t i c of the very a c i d DAO community. Thickness of the Ae h o r i z o n ranges from 2 - 6 cms. and pH of the organic l a y e r immediately above mineral s o i l i s co r r e s -pondingly a c i d ( 3.3 - 4.8). Vegetation r e f l e c t s t h i s d r i e r , more a c i d edaphotope p r i m a r i l y i n re-duced v i g o u r of m o i s t u r e - l o v i n g n eutrophilous species and a concurrent i n -crease i n abundance of mesophilous forms. Tsuga h e t e r o p h y l l a i n the t r e e l a y e r may have e x c e l l e n t v i g o u r , and, w i t h Thuja p l i c a t a . comprises the bulk of the tree cover i n most stands. The s i n g l e young stand studied had considerable v i g r o u s P i c e a engelmannii i n the crown canopy. Populus t r i c h o c a r p a i s r a r e l y present ( i n the AAO i t may be abundant). Pachistima m v r s i n i t e s i s more abundant and vigorous here than i n the AAO and i s not always r e s t r i c t e d t o decaying wood. Tsuga h e t e r o p h y l l a re-generation i s abundant i n the shrub l a y e r . Neutrophilous herbs o c c a s i o n a l l y present i n the SAO and AAO but u s u a l l y absent here i n c l u d e Asarum caudatum. to f o l l o w page 69. F i g . 30. Mature ABAO stand on coarse outwash p l a i n . Pseudotsuga m e n z i e s i i ( l e f t ) , Pinus monticola ( r i g h t c e n t e r ) , Tsuga h e t e r o p h y l l a ( r i g h t ) and Thujia p l i c a t a . Shrubs are mainly T. p l i c a t a and Taxus b e e v i f o l i a . August 18, 1961. F i g . 31. Ground v e g e t a t i o n i n climax ABAO: Cornus canadensis. T i a r e l l a u n i f o l i a t a . Chimaphila umbellata. Streptopus roseus. Monotropa hypopitys. J u l y , 1960. 70. Athyrium f i l i x - f e m i n a . Equisetum arvense. E. s y l v a t i c u m . E. pratense. L i s t e r a c o n v a l l a r i o i d e s . and Adenocaulon b i c o l o r . Cornus canadensis (bunch-berry) i s abundant and vi g o r o u s . Gymnocarpium d r y o p t e r i s i s weak. Bryophyte and l i c h e n cover on humus and decaying wood i s s i m i l a r to the SAO except that Lophozia lycopodioides may be prominent and exception-a l l y vigorous on humus, and C a l l i e r g o n e l l a s c h r e b e r i and Hylocomium  splendens may o c c a s i o n a l l y have e x c e l l e n t v i g o u r i n o l d e r stands. Tree data i s summarized as f o l l o w s : TABLE 17. Tree data summary. A l l u v i a l Bunchberry A r a l i a Oakfern f o r e s t type. S i t e index: a) Height at 50 years ( f t . ) 70 - 25 - 90 b) Height at 100 years ( f t . ) Pinus monticola 100 - 130 - 160 Pseudotsuga m e n z i e s i i 100 Tsuga h e t e r o p h y l l a 80 - 95 - 100 Thuia p l i c a t a 80 - 90 - 100 P i c e a engelmannii 90 - 100 - 110 Average maximum height ( f t . ) ; diameter of tr e e of average maximum heij Pinus monticola (126; 17.4) Pseudotsuga m e n z i e s i i 129-132-134; 34.3 - 36.2 -Tsuga h e t e r o p h y l l a 111-127-142; 20.0 - 27.8 -Thuia p l i c a t a 102-121-139; 20.1 - 28.8 -P i c e a engelmannii (120; 17.8) Stage 1 Stage 2 Bas a l area per acre (sq. f t . ) 283 - 348 - 381 (240) Number t r e e s per acre 275 - 321 - 380 (1977) Average diameter of stand ( i n . ) 13.7-14.1 -15.7 (4.7) Average age of dominants ( y r s . ) 200 - 240 - 275 (50) Average height of dominants & codominants ( f t . ) 113 - 118 - 129 (89) D e v i l ' s Club a s s o c i a t i o n (Oplopanacetum) Th i s p l a n t a s s o c i a t i o n occupies steep lower slopes where seepage i s u s u a l l y abundant at or near the s u r f a c e , banks of fast-moving small streams, and a l l u v i a l f l a t s near l a r g e r i v e r s (but not f l o o d p l a i n s , which support A l l u v i a l Complexes). Except on a l l u v i a l f l a t s and at h i g h e l e v a t i o n s , stands seldom exceed one or two acres. Moving p r o g r e s s i v e l y south through the Subzone, D e v i l ' s Club a s s o c i a t i o n s become fewer, developing p r o p e r l y only i n the c o o l e s t m o i s t e s t s i t u a t i o n s such as on narrow east-west v a l l e y bottoms and north-f a c i n g s l o p e s , or slopes at h i g h e l e v a t i o n s . No stands were encountered below 2000 f t . e l e v a t i o n . Regosols, Brown Woodeds, Minimal Podzols and o c c a s i o n a l l y Muck s o i l s , a l l d e c i d e d l y moist or s a t u r a t e d , u s u a l l y u n d e r l i e the D e v i l ' s Club phytoco-enose. S o i l s are the l e a s t a c i d of a l l the ecosystems s t u d i e d , probably because of abundant n u t r i e n t - r i c h moisture moving through the s o i l d u r i ng the growing season. Stands of t h i s p l a n t a s s o c i a t i o n may be f a i r l y open i n young stages p a r t i c u l a r l y along small streams where the stream bed and immediate banks are kept f r e e of t r e e growth by stream movement. In wet h a b i t a t s such as these ( a l s o very dry ones such as Lichen a s s o c i a t i o n s ) , t r e e composition i n e a r l y stages of succession does not d i f f e r very much from that of the c l i m a x , p o s s i b l y because the t r e e species capable of vigorous pioneer growth i n stands (e.g., Thuja p l i c a t a and some-times Populus trictaocarpa) are c o n s i d e r a b l y fewer than i n stands on mesic s i t e s (Pseudotsuga m e n z i e s i i . Pinus m o n t i c o l a . L a r i x o c c i d e n t a l i s . Tsuga  h e t e r o p h y l l a . B e t u l a p a p r y i f e r a . Populus tremuloides. S a l i x bebbiana). F o l l o w i n g l o g g i n g or f i r e , D e v i l ' s c l u b a s s o c i a t i o n s may r e t u r n d i r e c t l y to the c l i m a x , mainly because s o i l s , u n l i k e s o i l s of upland s i t e s , may be l i t t l e changed, except i n the case of severe disturbances as by f l o o d i n g and heavy a l l u v i u m d e p o s i t i o n , or e r o s i o n . O c c a s i o n a l l y i n young stands one or two cottonwood tr e e s can be found as w e l l as a few D o u g l a s - f i r or white p i n e , the l a s t two sometimes the t a l l e s t and most vigorous w i t h i n the Zone. These pioneer c o n i f e r s however 72. are always on r a i s e d ground where s o i l a e r a t i o n i s good. They r a r e l y occur i n pure stands as i s common i n the Moss a s s o c i a t i o n . F o r e s t types defined w i t h i n t h i s a s s o c i a t i o n i n c l u d e the Slope D e v i l ' s c l u b , Slope D e v i l ' s c l u b northern v a r i a n t , Tufa D e v i l ' s c l u b and A l l u v i a l D e v i l ' s c l u b . Only i n the Tufa D e v i l ' s c l u b i s the phytocoenose markedly d i s t i n c t . Abnndant moisture seems to minimize v e g e t a t i o n d i f f e r e n c e s be-tween f o r e s t types w i t h i n t h i s p l a n t a s s o c i a t i o n . The c h a r a c t e r i s t i c combination of species f o r the D e v i l ' s Club a s s o c i -a t i o n i s given i n Table 18. TABLE 18. CHARACTERISTIC COMBINATION OF SPECIES DEVIL'S CLUB ASSOCIATION (OPLOPANACETUM) + Constant dominant only i n t h i s a s s o c i a t i o n * Constant only i n t h i s a s s o c i a t i o n ! Most s u c c e s s f u l i n t h i s a s s o c i a t i o n but may be present i n adjacent communities 1 I n c l u d i n g a l l species Layer Trees Shrubs Herbs Constant dominants Thuja p l i c a t a Tsuga h e t e r o p h y l l a Oplopanax h o r r i d u s Taxus b r e v i f o l i a Thuja p l i c a t a Tsuga h e t e r o p h y l l a T i a r e l l a u n i f o l i a t a Constants only Bryophytes & l i c h e n s a) on humus Mnium spp.' *Acer glabrum *Ribes l a c u s t r e Rubus p a r v i f l o r u s Athyrium f i l i x - f e m i n a C l i n t o n i a u n i f l o r a Cornus canadensis *D r y o p t e r i s a u s t r i a c a Galium t r i f l o r u m Goodyera o b l o n g i f o l i a Linnaea b o r e a l i s Smilacina racemosa Streptopus a m p l e x i f o l i u s V i o l a g l a b e l l a *Mnium i n s i g n e M. punctatum Important non-constants ISambucus pubens Adiantum pedatum C y s t o p t e r i s f r a g i l i s !Equisetum s c i r p o i d e s Geum macrophyllum M i t e l l a breweri Polystichum a n d e r s o n i i P. l o n c h i t i s Senecio pauperculus I T i a r e l l a l a c i n i a t a IT. t r i f o l i a t a iBryum sandbergii C a l l i e r g o n e l l a cuspidata Cratoneuron f i l i c i n u m IMnium orthorynchum DEVIL'S CLUB ASSOCIATION (cont'd) Layer Constant dominants b) on Mnium spp.* decaying wood Constants only Important non-constants *Brachythecium spp. x C a l l i e r g o n e l l a s c hreberi *Cephalozia spp.* Dicranum fuscescens Hypnum c i r c i n a l e Lophozie spp.* Mnium spinulosum *Plagiothecium denticuatum Cladonia spp.* P e l t i g e r a spp. 75. D i s t r i b u t i o n of species by constancy c l a s s e s i n t h i s a s s o c i a t i o n i s shown i n F i g . 32. The second maximum i n C l a s s 5 denotes that the a s s o c i -a t i o n i s homogeneous. A t o t a l of 272 species i n 18 sample stands are i n -cluded i n the s y n t h e s i s t a b l e f o r t h i s a s s o c i a t i o n . The e x c e p t i o n a l cover of edaphic climax Thuja p l i c a t a i s evident i n F i g . 33 a ) . F i g . 33 b) shows the prominence of nanophanerophytes and hemicryptophytes i n the v e g e t a t i o n l i f e form spectrum. Chamaephytes, im-portant i n d i r e r a s s o c i a t i o n s , are l e s s evident here. Slope D e v i l ' s Club f o r e s t type (SD) Stands of t h i s f o r e s t type occur on steep lower slopes possessing c o o l m i c r o c l i m a t e s and an abundant supply of permanent seepage a t or near the s u r f a c e . Topography g e n e r a l l y has a n e u t r a l p r o f i l e and contour, but complex r o l l i n g contour i s not uncommon. In the l a s t , most t r e e s grow on the r i d g e s . The stands s t u d i e d ranged i n e l e v a t i o n from 2500 to 3110 f e e t . S o i l s i n the stands s t u d i e d were Normal O r t h i c A c i d Brown Wooded and Shallow Muck w i t h no Ae h o r i z o n and r e l a t i v e l y high pH f o r the main r o o t i n g h o r i z o n (5.9 - 6.6). Reaction of the organic l a y e r immediately above mineral s o i l was 4.5 - 6.0. Because of the marked r a i s e d ground - wet depression nature of the ground surface and the open crown canopy through which much l i g h t may reach the f o r e s t f l o o r , ground v e g e t a t i o n o f t e n appears heterogeneous. This mosaid where hygrophilous species (e.g., C i r c a e a a l p i n a ) are r e s t r i c t e d to wet g u l l i e s and mesophilous species (e.g., Cornus canadensis) to d r i e r r i d g e s i s c h a r a c t e r i s t i c of the D e v i l ' s Club and the Skunk Cabbage a s s o c i a -t i o n s . Thuja p l i c a t a dominates the t r e e l a y e r , o f t e n w i t h e x c e l l e n t v i g o u r and i s the unchallenged edaphic c l i m a x t r e e . Tsuga h e t e r o p h y l l a may be common, Co f o l l o w page 7 5 . F i g . 32. Constancy diagram f o r D e v i l ' s Club a s s o c i a t i o n . .—. -fo —* UJ •40 o u l o. U . -30 O 10 <fi X •(0 • 0 171 5 I u m is TwoTft PUltVC* 0PUOPft Mft H. M o f U t D J S T A 4US flftEViFOuft T H o J f t PH CftTA T$Ufrft v<eteftofnvu»\ TiftftELLft UNtfOUfttA M W I M M 5PP. a) -50 -4o )o b) •20 •10 . rt 1 1 u p« C H (y M L LIF6 • Four'! 1 IO * o 30 40 TO 60 F i g . 33. D e v i l ' s Club a s s o c i a t i o n : a) average cover of constant dominant s p e c i e s ; b) vege t a t i o n l i f e form spectrum based on cover of constant species. Pm megaphanerophytes, Pn nanophanero-phytes, C chamaephytes, H hemicryptophytes, G geophytes, M mosses. L l i c h e n s . but i s i n v a r i a b l y e s t a b l i s h e d on r a i s e d ground or more commonly on decaying wood, being vigorous only i n the l a t t e r h a b i t a t . Pinus m o n t i c o l a . Pseudo-tsuga m e n z i e s i i and P i c e a engelmannii o c c a s i o n a l l y grow e x c e p t i o n a l l y w e l l on r a i s e d ground. Dense shrub cover, almost a l l of which may be vigorous and s o c i a b l e Oplopanax h o r r i d u s . ranges from 65 to 85% i n the stands s t u d i e d . Taxus  b r e v i f o l i a . w h i l e present i n a l l samples, i s abundant only i n climax stands. Healthy L o n i c e r a utahensis and Ribes l a c u s t r e (on decaying wood), and low v i g o u r Rosa gymnocarpa and Rubus p a r v i f l o r u s may be common i n young stands. Vaccinium o v a l i f o l i u m . V, membranaceum. Pachistima m y r s i n i t e s . and Tsuga  h e t e r o p h y l l a r e g e n e r a t i o n , are g e n e r a l l y r e s t r i c t e d to o l d decaying wood. Vigorous T i a r e l l a u n i f o l i a t a and Gymnocarpium d r y o p t e r i s i n v a r i a b l y dominate the herb l a y e r which may cover up to 90% of the ground i n young stands. Other species which o c c a s i o n a l l y may be common and are u s u a l l y very v i g o r o u s , are Adenocaulon b i c o l o r . C i r c a e a a l p i n a . Disporum oreganum. Smi l a c i n a racemosa and Streptopus roseus. Asarum caudatum may be common but i s never as vigorous as i n the A r a l i a Oakfern a s s o c i a t i o n . Others occasion-a l l y prominent are A r a l i a n u d i c a u l i s ( p a r t i c u l a r l y i n young sta n d s ) , C l i n t o n i a u n i f l o r a , Cornus canadensis ( u s u a l l y on decaying wood on r a i s e d ground), c y s t o p t e r i s f r a g i l i s ( r a r e ) , D r y o p t e r i s a u s t r i a c a (often abundant), Galium  t r i f l o r u m . Lycopodium selago (on humus i n o l d e r s t a n d s ) , Rubus pedatus ( a l -ways on decaying wood), Streptopus a m p l e x i f o l i u s . T i a r e l l a t r i f o l i a t a and V i o l a g l a b e l l a . I t i s s i g n i f i c a n t t h a t no P y r o l a spp. were present i n any of the stands s t u d i e d . Bryophyte cover on humus ranges from 15% on steep slopes w i t h surface seepage to 50% beneath stands on l e s s e r slopes w i t h subsurface seepage. Mnium i n s i g n e dominates i n o l d e r stands, sometimes w i t h M. punctatum. Both species are present i n a l l stands i n average v i g o u r . Other species occasion-to f o l l o w page 76. F i g . 34. D e v i l ' s Club a s s o c i a t i o n at base of north-f a c i n g slope. Dense Oplopanax h o r r i d u s grows beneath stand of Thuja p l i c a t a . J u l y 18, 1960. Gymnocarpium d r y o p t e r i s . Galium t r i f l o r u m . June 9, 1960 A 77. a l l y c overing 15 to 20% of the ground i n good v i g o u r are Brachythecium  hylotapetum. Hylocomium splendens ( r a i s e d ground) and Rhytidiadelphus  l o r e u s . Hygrophilous species o f t e n present but very s c a t t e r e d i n any one stand a r e , R i c c i a f l u i t a n s . Conocephalum conicum, Marchantia polymorpha. P l a g i o c h i l a a s p l e n i o i d e s and Metzgeria pubescens. Lichens r a r e l y e s t a b l i s h on the ground. In the o l d e r stands p a r t i c u l a r l y , bryophyte covered decaying wood may be abundant. No s i n g l e bryophyte c o n s t a n t l y dominates decaying wood i n the SD as may occur i n more mesic s i t e s (e.g., C a l l i e r g o n e l l a s c h r e b e r i i n the Moss and A r a l i a Oakfern a s s o c i a t i o n s ) . Brachythecium hylotapetum may dominate decaying wood i n one stand, Plagiothecium s y l v a t i c u m i n another and Jungermannia l a n c e o l a t a i n yet another. Hylocomium splendens dominates i n one p a r t i c u l a r stand where f a l l e n wood i s p a r t i c u l a r l y well-decayed and sub-equal w i t h the ground surface. In no case however does any s i n g l e bryophyte species ever exceed 10% cover, even though up to 40% of the ground may be covered by decaying wood. Other bryophytes which may grow v i g o r o u s l y on decaying wood i n the SD are Buxbaumia p i p e r i ( r a r e ) , €alypogeia neesiana. numerous Cephalozia spp. i n extensive f i l m s on the sides of o l d l o g s , Hylocomium pygenaicum. Jameson!ella autumnalis. L e p i d o z i a reptans. wet s i t e Lophozia spp., Mnium punctatum (vigour u s u a l l y poor on decaying wood but presence alone i s s i g n i f i c a n t ) , Plagiothecium denticulatum. R i c c i a f l u i t a n s . Rhytidiadelphus loreus and Tetraphis g e n i c u l a t a . The decaying wood bryophytes C a l l i e r g o n e l l a s c h r e b e r i . Dicranum fuscescens. D. s t r i c t u m . Hypnum c i r c i n a l e . Mnium spinulosum. and P t i l i d i u m pulcherrimum are u s u a l l y present i n poor to average v i g o u r . Other species o c c a s i o n a l l y found on de-daying wood, only i n the wettest f o r e s t h a b i t a t s are P l a g i o c h i l a a s p l e n i o i d e s . Brachythecium r i v u l a r e . Chiloscyphus p a l l e s c e n s . Conocephalum conicum. Dichodontium pellucidum. P e l l i a e n d i v i a e f o l i a . Plagiothecium pulchellum, and 78. Radula b o l a n d e r i . Lichens which grow reasonable w e l l on decaying wood but are u s u a l l y s c a t t e r e d are P e l t i g e r a p o l y d a c t y l a and P. canina. Others r a r e l y present are Cladoni a f i m b r i a t a . Icmadophila ericetorum, P e l t i g e r a  canina v a r . rufescens and P. malacea. Few bryophytes and l i c h e n s occur on r o c k s , the most c o n s i s t e n t and vigorous being Heterocladium procurrens. Other w e t - s i t e species which may occur o c c a s i o n a l l y i n vigorous c o n d i t i o n , depending on the type of rock and the degree of weathering of i t s s u r f a c e , are: Mnium i n s i g n e . M. punctatum. Chiloscyphus p a l l e s c e n s . Conocephalum conicum. Dichodontium pellucidum, Didymodon r e c u r v i r o s t r i s , F i s s i d e n s g r a n d i f r o n s . P e l l i a e n d i v i a e f o l i a . Metzgeria pubescens. P o h l i a w a h l e n b e r g i i . Poro