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Vegetation-environment relationships of Subalpine Mountain Hemlock Zone ecosystems. Brooke, Robert Charles 1966

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VEGETATION-ENVIRONMENT RELATIONSHI PS OF  SUBALPINE MOUNTAIN HEMLOCK ZONE ECOSYSTEMS  by ROBERT CHARLES BROOKE B . S . F . (Hon.), University of B r i t i s h Columbia, 1958 H.F.,  Yale U n i v e r s i t y , 1959  A THESIS SUBMITTED IN PARTIAL FULFILLMENT OF THE REQUIREMENTS FOR THE DEGREE OF DOCTOR OF PHILOSOPHY i n the Department of Biology and Botany  He accept t h i s thesis as conforming to the required standard  THE UNIVERSITY OF BRITISH COLUMBIA January 1966  In presenting this thesis  in p a r t i a l fulfilment of  the requirements for an advanced degree at the University of B r i t i s h Columbia,  I agree that the Library shall make it freely  available for reference and study.  I further agree that per-  mission for extensive copying of this thesis for scholarly purposes may be granted by the Head of my Department or by his representatives,,  It is understood that copying or p u b l i -  cation of this thesis for f i n a n c i a l gain shall not be allowed without my written permission.  Department of  Botany  The University of B r i t i s h Columbia Vancouver 8, Canada Date  29 A p r i l  1966  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  ROBERT CHARLES BROOKE B. S.F.  (Hons.)* The University of B r i t i s h Columbia M.F., Yale University, 1959  FRIDAY, APRIL 29, 1966, at 3:00 p.m. IN ROOM 3332, BIOLOGICAL SCIENCES BUILDING  COMMITTEE IN CHARGE Chairman: J. V. W. C.  I. McT. Cowan  E. Bier J . Krajina H. Mathews A. Rowles  W. B. Schofield T. M. C. Taylor G. H. N. Towers D. J . Wort  External Examiner: John W. Marr Director, I n s t i t u t e of A r c t i c and Alpine Research University of Colorado, Boulder, Colorado  Research Supervisor:  V. J . Krajina  VEGETATION-ENVIRONMENT RELATIONSHIPS OF SUBALPINE MOUNTAIN HEMLOCK ZONE ECOSYSTEMS . ABSTRACT Quantitative and q u a l i t a t i v e vegetation and environmental data from one-hundred-fourteen sample p l o t s were used to characterize and evaluate e c o l o g i c a l r e lationships and dynamics previously l i t t l e known for the Subalpine Mountain Hemlock Zone on the southwestern B r i t i s h Columbia mainland. Environmental analyses, presented i n d e t a i l , include the description of t h i r t y six kinds of s o i l representing several major categories. From the a n a l y t i c a l data, each sample p l o t consists of a single set of values representing l o c a l h i s t o r i c a l l y developed variations and patterns of vegetation, s o i l , microclimate and topography within the biogeoclimatic zonal concept of Krajina (1962) . A combined vegetationenvironment synthesis resulted i n the characterization of ecosystematic units at several l e v e l s of generalization (zone, subzone, order, a l l i a n c e , association, subassoc i a t i o n and variant) within the following c l a s s i f i c a t i o n scheme: (A)  Parkland Subzone i ) Chionophilous (Schneetalchen) units, with snow duration of at least 9 months 1) Vegetation of unstable sheet-wash slopes or hamada-like surfaces 2) Sedge vegetation of s e m i - t e r r e s t r i a l basin habitats i i ) Moderately chionophilous units with snow duration averaging between 8 and 9 months 1) Herbaceous vegetation of stream-edge, spring-line or s e m i - t e r r e s t r i a l habitats 2) Heath-like or low shrub vegetation o f t e r r e s t r i a l mesic to hygric habitats i i i ) Chionophobous forested units with snow durat i o n averaging about 8 months o r l e s s 1) Mesic habitats 2) Moderately dry habitats  (B)  Forest Subzone i ) Forested units lacking a seepage influence o r • with only a temporary seepage influence 1) Moderately dry l i t hie habitats o r habitats with shallow s o i l s  2)  ii)  iii)  Mesic habitats with shallow to deep s o i l s 3) Hygric habitats with deep s o i l s and a temporary seepage influence Forested units of hygric habitats with a permanent seepage influence 1) Seepage fast-flowing i n streamedge or s p r i n g - l i n e habitats 2) Seepage slow-moving or stagnating in depressions or s p r i n g - l i n e habitats Non-forested s e m i - t e r r e s t r i a l moor habitats  As orders and a l l i a n c e s include units of lower rank with strong environmental and f l o r i s t i c s i m i l a r i t i e s to those found i n other biogeoclimatic zones and subzones and elsewhere, a new dimension i s added to the organization of ecosystematic u n i t s . The Subalpine Mountain Hemlock Zone coincides with the main d i s t r i b u t i o n a l area of Tsuga mertensiana an area with a cool, snowy forest climate (Dfc after Koppen), podzolization and g l e i z a t i o n as the dominant soil-forming processes, and with the development of Humic and Humus Podzol s o i l s with thick, acid accumulations of mycelial ecto-humus on mesic zonal habitats. Discontinuity i n the forest cover coinciding with an increasing duration of snow provides a physiognomic, f l o r i s t i c and c l i m a t i c basis for the recognition of the Parkland and Forest Subzones. Vegetation and s o i l patterns and r e l a t i o n ships i n the Parkland Subzone are evidently most influenced by snow duration, s o i l moisture regime, topography and microclimate, whereas s o i l moisture regime, land type and topography are important i n fluences i n the Forest Subzone. The interplay of compensatory influences may promote the development of s i m i l a r f l o r i s t i c patterns on d i f f e r e n t topographic forms on an i n t r a - and interzonal scale. The environmentally integrating influence of snow depth and duration i n the Parkland Subzone r e s u l t s i n sharp f l o r i s t i c and microclimatic patterns. Vegetation may have a strong autogenic influence on microenvironmental dynamics by hastening snow melt and extending length of the growing season over short distances. .  Dynamics within the zone favoring successional trends are proceeding at a very slow rate. Climatic changes shortening the duration of snow rather than cumulative autogenic influences would probably contribute most to vegetation changes at high elevations in the subalpine zone.  GRADUATE STUDIES  F i e l d of Study:  Plant Ecology  Advanced Plant Autecology Advanced Plant Synecology Advanced Plant Physiology II Advanced Forest Pathology F i e l d Botany Seminar on Current Topics  V. J. Krajina V. J. Krajina D. J. Wort J. E. Bier Members of the Department II  II  II  n  Other Studies: Forest Tree Seed Forestry Seminar Geomorphology S o i l Chemistry Soil-plant Relationships  G. S. A l l e n P. J. Haddock W. H. Mathews J. S. Clark J. Basaraba C. A. Rowles J. S. Clark  PUBLICATIONS 1964  S t e i n J . R. and R. G. Brooke.. Red snow from Mt. Seymour B r i t i s h Columbia. Can. J. Botany 42; 1183=1188 s  3  1965  Brooke Robert C. The Subalpine Mountain Hemlock Zone. 11, Ecotopes and biogeoceonocic u n i t s . Ecol. Western North Amer. Is 79=101 s  Advisor:  Professor Vladimir J .  Krajina  ABSTRACT  Q u a n t i t a t i v e and q u a l i t a t i v e v e g e t a t i o n were used t o c h a r a c t e r i z e and e v a l u a t e  and e n v i r o n m e n t a l  d a t a from o n e - h u n d r e d - f o u r t e e n  e c o l o g i c a l r e l a t i o n s h i p s and dynamics p r e v i o u s l y l i t t l e  the S u b a l p i n e M o u n t a i n Hemlock Zone on the s o u t h w e s t e r n B r i t i s h Columbia m a i n l a n d . presented i n d e t a i l ,  sample p l o t s  i n c l u d e t h e d e s c r i p t i o n of t h i r t y - s i x  k i n d s of s o i l  known  Environmental  for  analyses,  r e p r e s e n t i n g s e v e r a l major  cate-  gori es. From t h e a n a l y t i c a l d a t a ,  each sample p l o t c o n s i s t s of a s i n g l e s e t of v a l u e s r e p r e s e n t i n g  h i s t o r i c a l l y d e v e l o p e d v a r i a t i o n s and p a t t e r n s b i o g e o c l i m a t i c zonal  of v e g e t a t i o n ,  c o n c e p t of K r a j i n a ( 1 9 6 2 ) .  [A]  a s s o c i a t i o n , s u b a s s o c i a t i o n and v a r i a n t )  within  the  synthesis resulted in  l e v e l s of g e n e r a l i z a t i o n ( z o n e , s u b z o n e ,  order,  w i t h i n the f o l l o w i n g c l a s s i f i c a t i o n scheme:  P a r k l a n d Subzone l]  Chionophilous 1)  ( S c h n e e t a l c h e n ) u n i t s w i t h snow d u r a t i o n of at l e a s t 9 months  Vegetation  of u n s t a b l e s h e e t - w a s h s l o p e s or h a m a d a - l i k e s u r f a c e s  2) Sedge v e g e t a t i o n II]  Moderately 1)  III]  habitats  c h i o n o p h i l o u s u n i t s w i t h snow d u r a t i o n a v e r a g i n g between 8 and 9 months  Mesic  of s t r e a m - e d g e ,  or low shrub v e g e t a t i o n  Chionophobous f o r e s t e d 1)  of s e m i - t e r r e s t r i a l b a s i n  Herbaceoussvegetation  2) H e a t h - l i k e  s p r i n g - l i n e or s e m i - t e r r e s t r i a l  of t e r r e s t r i a l mesic t o h y g r i c  habitats  habitats  u n i t s w i t h snow d u r a t i o n a v e r a g i n g about 8 months or  less  habitats  2) M o d e r a t e l y [B]  m i c r o c l i m a t e and topography  A combined v e g e t a t i o n - e n v i r o n m e n t  the c h a r a c t e r i z a t i o n of e c o s y s t e m a t i c u n i t s at s e v e r a l alliance,  soil,  local  dry h a b i t a t s  ^  F o r e s t Subzone l]  Forested 1)  u n i t s l a c k i n g a seepage i n f l u e n c e or w i t h o n l y a temporary Moderately  dry l i t h i c  h a b i t a t s or h a b i t a t s w i t h s h a l l o w  2) M e s i c h a b i t a t s w i t h s h a l l o w t o deep s o i l s 3) H y g r i c ll]  Forested 1)  III]  seepage  u n i t s of h y g r i c h a b i t a t s w i t h a permanent seepage Seepage f a s t - f l o w i n g  Non-forested  i n stream-edge  or s p r i n g - l i n e  influence  influence habitats  or s t a g n a t i n g i n d e p r e s s i o n s or s p r i n g - l i n e  s e m i - t e r r e s t r i a l moor  the o r g a n i z a t i o n  habitats  habitats  As o r d e r s and a l l i a n c e s i n c l u d e u n i t s of l o w e r rank w i t h s t r o n g e n v i r o n m e n t a l t i e s t o t h o s e found  influence  '  h a b i t a t s w i t h deep s o i l s and a temporary  2) Seepage s l o w - m o v i n g  seepage  soils  and f l o r i s t i c  similari-  i n o t h e r b i o g e o c l i m a t i c zones and subzones and e l s e w h e r e , a new d i m e n s i o n i s added  of e c o s y s t e m a t i c  to  units.  The S u b a l p i n e Mountain Hemlock Zone c o i n c i d e s w i t h t h e main d i s t r i b u t i o n a l a r e a of Tsuqa m e r t e n s i a n a — an a r e a w i t h a c o o l ,  snowy f o r e s t c l i m a t e (Dfc  a f t e r Koppen),  podzolization  and g l e i z a t i o n as the  i ii dominant s o i l - f o r m i n g p r o c e s s e s , and w i t h the development a c c u m u l a t i o n s of m y c e l i a l ecto-humus on mesic zonal  of Humic and Humus Podzol  habitats.  Discontinuity  w i t h an i n c r e a s i n g d u r a t i o n of snow p r o v i d e s a p h y s i o g n o m i c , f l o r i s t i c of the P a r k l a n d and F o r e s t S u b z o n e s .  V e g e t a t i o n and s o i l  are e v i d e n t l y most i n f l u e n c e d by snow d u r a t i o n , soil  m o i s t u r e r e g i m e , l a n d type and topography  soil  forms on an i n t r a - and i n t e r z o n a l The e n v i r o n m e n t a l l y i n sharp f l o r i s t i c environmental  acid  i n the f o r e s t c o v e r c o i n c i d i n g  and c l i m a t i c b a s i s f o r the r e c o g n i t i o n  p a t t e r n s and r e l a t i o n s h i p s i n the P a r k l a n d Subzone  m o i s t u r e r e g i m e , topography  are i m p o r t a n t  of compensatory i n f l u e n c e s may promote the development  s o i l s with t h i c k ,  and m i c r o c l i m a t e , whereas  i n f l u e n c e s i n the F o r e s t Subzone.  of s i m i l a r f l o r i s t i c  The  p a t t e r n s on d i f f e r e n t  interplay  topographic  scale.  i n t e g r a t i n g i n f l u e n c e of snow d e p t h and d u r a t i o n i n the P a r k l a n d Subzone r e s u l t s  and m i c r o c l i m a t i c p a t t e r n s .  V e g e t a t i o n may have a s t r o n g a u t o g e n i c i n f l u e n c e on m i c r o -  dynamics by h a s t e n i n g snow melt and e x t e n d i n g l e n g t h of the growing season over s h o r t d i s t a n c e s .  Dynamics w i t h i n the zone f a v o r i n g s u c c e s s ) o n a l t r e n d s are p r o c e e d i n g a t a very slow r a t e . changes s h o r t e n i n g the d u r a t i o n of snow r a t h e r than c u m u l a t i v e a u t o g e n i c i n f l u e n c e s would p r o b a b l y most t o v e g e t a t i o n changes at h i g h e l e v a t i o n s i n the s u b a l p i n e z o n e .  Climatic contribute  Iv TABL'E OF CONTENTS Page Acknowledgment  •  INTRODUCTION .  1  The approach, concept and presentation of material REGIONAL DESCRIPTION  2  '  The Subalpine Mountain Hemlock Zone The Study Area Topography . .  5  k  .  .  .  .  6 9 12  Geology  14  Climate Temperature Precipitation Soil Vegetation  14 16 19 23 23  - .  .  .  .  Pleistocene events and history SUBALPINE MICROCLIMATES AND CLIMATE  .  29 .  .  Methods of Microclimatic Measurement and Analysis . Results Solar r a d i a t i o n  33 .  .  .  .  .  33 36 38  Climatic patterns A i r and surface temperatures  39 42  .  S o i l temperature P r e c i p i t a t i o n , r e l a t i v e humidity, and evaporation during snow-free periods . Snow depth and duration . Snow and temperature patterns at a snow pocket s t a t i o n Comparison of Subalpine Microclimates by Communities and Subzones Subalpine Climate  . .  . .  . .  . .  50 57 61 66 73 76  SUBALPINE SOILS  78  Methods of S o i l Sampling, D e s c r i p t i o n , Analysis and C l a s s i f i c a t i o n  78  Results Parent material and rock i d e n t i f i c a t i o n Description and c l a s s i f i c a t i o n of the s o i l s . . T e r r e s t r i a l (Land) S o i l s . . . . . . . T e r r e s t r i a l Raw S o i l s Regosolic S o i l s Ranker-like S o i l s Brunisolic Soils ' Subalpine l.ntergrades to Podzolic S o i l s Podzolic S o i l s  83 83 86 88 88 90 91 94 95 98  Podzol Great Group Humic Podzol.Great Group Semi-Terrestrial S o i l s Gleysolic S o i l s Gleysol Great Group Eluviated Gleysol Great Group Anmoor-like S o i l s Organic S o i l s  . . ."  .  .  .  .  .  .  .  '  98 102 107 107 107 107 109 110  V TABLE OF CONTENTS (continued) Page SUBALPINE SOILS (continued) S o i l moisture Chemical c h a r a c t e r i s t i c s of the s o i l s  114 120  Comparison of subalpine s o i l s by communities and selected environmental variables  126  Subalpine s o i l s  131  ,  SUBALPINE ECOSYSTEMS  ,  Methods of analysis and synthesis Description of the units  .  .  .  .134  .  .  .  .  .  . 134 139  Parkland Subzone Chionophilous (Schneetalchen) units with snow duration of at least 9 months . . . Vegetation of unstable sheet-mash slopes or hamada-like surfaces . . . . Sedge vegetation of s e m i - t e r r e s t r i a l basin habitats . Moderately chionophilous units with snow duration averaging between 8 and 9 months Herbaceous vegetation of stream-edge, s p r i n g - l i n e or s e m i - t e r r e s t r i a l habitats Heath-like or low shrub vegetation of t e r r e s t r i a l mesic to hygric habitats . Chionophobous forested units with snow duration averaging about 8 months or less .  139 .139 .139 . 144 . 147 . 147 .151 .161  Mesic habitats  161  Moderately dry habitats  164  Forest Subzone Forested units lacking a seepage influence or with only a temporary seepage i n f l u e n c e . Moderately dry l i t h i c habitats or habitats with shallow s o i l s Mesic habitats with shallow to deep s o i l s Hygric habitats with deep s o i l s and a temporary seepage influence Forested units of hygric habitats with a permanent seepage influence Seepage f a s t - f l o w i n g i n stream-edge or s p r i n g - l i n e habitats Seepage slow-moving or stagnating i n depressions or s p r i n g - l i n e habitats Non-forested unit of a s e m i - t e r r e s t r i a l moor habitat Comparison of the Orders and A l l i a n c e s VEGETATION-ENVIRONMENT RELATIONSHIPS  SUMMARY AND CONCLUSIONS"  APPENDICES (Volume 2)  '  179 .179 .180 183 186 188  - .  ' '  .  '  Vegetation-environment r e l a t i o n s h i p s and dynamics Parkland Subzone Forest Subzone History and current dynamics  BIBLIOGRAPHY .  .  168 168' 168 169 174  188 189 . 198 201 212 217  LIST OF TABLES Table  Page  1  Rock types and bedrock units of the study area within the Subalpine Mountain Hemlock Zone .  2  Long-term c l i m a t i c records of selected southern coastal and Coast Range stations i n B r i t i s h Columbia  3  .  .  .• 15  .  Average snow depth, water content, and snow/water r a t i o s f o r selected snow courses within and adjacent to the study area (April 1st survey)  4  21  Five-year average snow depth, water content, and snow/water r a t i o s f o r the Seymour Mountain snow course, 3650 f t e l e v a t i o n , at d i f f e r e n t survey dates (1960—64 i n c l u s i v e )  5  17  .  .  .  .  21  C h a r a c t e r i s t i c zonal species and d i f f e r e n t i a t i n g combination of species f o r the Parkland and Forest Subzones, Subalpine Mountain Hemlock Zone  27  6  Outline of the c l a s s i f i c a t i o n of subalpine communities described i n d e t a i l by Peterson (1964).  28  7  Location, d e s c r i p t i o n and instrumentation of microclimatic stations  34  8  Seasonal summary of d a i l y temperature data f o r subalpine microclimatic s t a t i o n s , 1961  9  F r o s t - f r e e periods at various l e v e l s f o r subalpine microclimatic s t a t i o n s , 1961  10  .  .  .  45  Average and extreme weekly maximum-minimum temperature during summer at four l e v e l s f o r subalpine microclimatic stations  11  44  46  Temperature p r o f i l e comparison f o r an overcast day and a c l e a r day i n summer f o r selected subalpine microclimatic stations  48  12  Summary of s o i l temperature data at subalpine microclimatic s t a t i o n s , lilt. Seymour (1961)  .  .  52  13  Comparison of monthly s o i l and a i r temperature f o r 1961 and the ' i n s u l a t i n g e f f e c t ' of snow  .  55  14  Months i n which freezing temperatures occurred at any depth or i n any s o i l p i t f o r subalpine microclimatic stations (1960-62)  .  55  15  D i s t r i b u t i o n of freezing temperatures with depth based on a l l p i t s and monthly s o i l temperature 56  16  Comparison of 'snow-free' period p r e c i p i t a t i o n at the microclimatic s t a t i o n s (1960 and 1961) .  57  17  Summary of microclimatic data f o r the snow pocket s t a t i o n (1960 - 1962) .  68  18  Temperature differences at the snow pocket s t a t i o n on c l e a r days i n summer and f a l l , 1961 .  19  Comparison of temperature data f o r twelve microclimatic stations (44 day p e r i o d , August September 1961)  .  69  74  20  Comparison of the Parkland Subzone and Forest Subzone microclimates on Mount Seymour^ 1960-62  21  Comparison of 1961 subalpine microclimatic data with 1961 and long-term c l i m a t i c data from  22  selected coastal and coast range stations Comparison of bedrock and rock samples c o l l e c t e d from s o i l p i t s  -  75  77 85  LIST OF TABLES (continued) Table  Page  23  Synopsis of s o i l categories described and p r o v i s i o n a l l y c l a s s i f i e d  87  24  1961 Seasonal average s o i l moisture contents and annual range compared to the estimated f i e l d capacity  115  25  Average and range i n chemical properties f o r organic horizons i n s o i l s of the Podzolic Order  120  26  Average chemical c h a r a c t e r i s t i c s of s o i l s by major s o i l category  121  27  Average chemical c h a r a c t e r i s t i c s by major s o i l category calculated f o r a unit horizon  .  28  Average chemical c h a r a c t e r i s t i c s by plant associations calculated f o r a unit horizon .  .  29  A synopsis of the ecosystematic units described f o r the Subalpine Mountain Hemlock Zone .  30  Chionophilous ecosystem units of the Parkland Subzone, Subalpine Mountain Hemlock Zone  31  C h a r a c t e r i s t i c combination of species and r e l a t i o n s h i p s of the S a x i f r a g e t a l i a t o l n i e i and C a r i c i o n n i g r i c a n t i s  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . .  .  . .  125 129  .  .  137 .140  .  .  .  .  .  .  .  .  .  148  .  .  .  152  .  .  .  153  32  Moderately chionophilous ecosystem unit of a s e m i - t e r r e s t r i a l habitat .  33  C h a r a c t e r i s t i c combination of species f o r the Leptarrhenion p y r o l i f o l i a e i n d i c a t i n g  .  141  re 34  Moderately chionophilous low shrub ecosystem units of the Parkland Subzone  35  C h a r a c t e r i s t i c and d i f f e r e n t i a t i n g combinations of species f o r associations of the Phyilodoceto - Cassiopion i n d i c a t i n g r e l a t i o n s h i p s .  .  .  .  .  .  .  .  .  .  .  .  .  36  Chionophobous forested ecosystem unit v i t h snow duration averaging about 8 months or l e s s  .  162  37  C h a r a c t e r i s t i c combination of species and r e l a t i o n s h i p s of the Vaccinion nembranacei .  .  163  38  Forested moderately dry ecosystem u n i t s , Subalpine Mountain Hemlock Zone  39  C h a r a c t e r i s t i c combination of species f o r the Tsugeto - Cladothamnetua and d i f f e r e n t i a t i n g  . . . . . . . 1 6 5  combination of species f o r the variants i n d i c a t i n g r e l a t i o n s h i p s . .  .  .  .  .  . .  .  .  .  .  .  .  166  .  .  .  .  .  .  170  40  Forested units of mesic habitats with shallow to deep s o i l s  41  C h a r a c t e r i s t i c combination of species f o r the Abieteto - Tsugetun mertensianae and d i f f e r e n t i a t i n g combination of species f o r the variants i n d i c a t i n g r e l a t i o n s h i p s . .  42  Forested hygric ecosystem u n i t s , Subalpine Mountain Hemlock Zone  43  C h a r a c t e r i s t i c combination of species f o r the Abieteto - Streptopetua and d i f f e r e n t i a t i n g combination of species f o r the variants i n d i c a t i n g r e l a t i o n s h i p s  44 45  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  171  .  175  .  176  Azonal forested hygric to hydric ecosystem u n i t s , Subalpine Mountain Hemlock Zone . . . . C h a rLaycstiecrhi isttiiocn combination americani i nofd i cspecies a t i n g r ef o l art ithe o n s hThujeto i p s . - . Oplopanacion . . . . h. o r .r i d i. and . . . . .  181 182  viii LIST OF TABLES (continued) Table  Page  46  Non-forested ecosystem unit of a s e m i - t e r r e s t r i a l moor habitat, Forest Subzone  47  C h a r a c t e r i s t i c combination of species f o r the Eriophoreto - Caricion a q u a t i l i s indicating relationships  48  185  Condensed table of Orders and A l l i a n c e s i n d i c a t i n g c h a r a c t e r i s t i c combinations of species and r e l a t i o n s h i p s , Subalpine Mountain Hemlock Zone  49  167  Summary of the habitat c h a r a c t e r i s t i c s of the Phyllodoceto - Cassiopetalia i n comparison to other units i n the Parkland Subzone  50  51  184  195  Indices of f l o r i s t i c s i m i l a r i t y f o r associations of the Parkland Subzone based on species presence and calculated according to the formula of Sorenson  198  Indices of f l o r i s t i c s i m i l a r i t y f o r associations of the Forest Subzone based on species presence  .  201  LIST OF FIGURES Figure  Page  1  The Subalpine Mountain Hemlock Zone — a panoramic view i n Garibaldi Park  8  2  Topography, study areas, c l i m a t i c s t a t i o n s , and snow courses  3  The Parkland Subzone, Round Mountain i n Garibaldi Park (elevation 4500 - 5000 f t )  4  T r e e - l i m i t at 5700 - 6000 f t e l e v a t i o n , Diamond Head i n Garibaldi Park  26  5  A recently glaciated landscape i n the Garibaldi Park area  30  6  A view of the Garibaldi Park area showing the p o s i t i o n of l a t e snow-lie (26 July 1961) .  7  Yearly snow accumulation, moving ten-year averages, and long-term average snow  -  11 .  .  .  .  .  .  accumulation at A p r i l 1 survey f o r two subalpine snow courses  26  30  32  8  The angle of mid-day i n s o l a t i o n f o r the astronomical seasons  37  9  Hygrothermograph trace f o r 23 July to 30 July 1960, Mount Seymour  40  10  Hygrothermograph trace f o r 24 August to 31 August 1961, Garibaldi Park  11  Hygrothermograph trace f o r 28 August to September 1961  41  12  Hygrothermograph trace f o r 15 January to 21 January 1961  41  13  Daily temperature range .  43  14  Weekly temperature range at various l e v e l s f o r selected subalpine microclimatic stations  15  (1960, 1961) . . Temperature patterns by level of measurement, i n p r o f i l e , and temperature range f o r the  .  .  •  40  .  47  Control microclimatic s t a t i o n on Mt. Seymour f o r 25 J u l y , 1962  49  16  Temperature pattern f o r three l e v e l s of measurement at Station 7 on Mt. Seymour f o r 1961  .  17  S o i l temperature patterns i n r e l a t i o n to snow cover at three subalpine microclimatic  18  Weekly range of r e l a t i v e humidity and evaporation at four subalpine microclimatic stations during snow-free periods of 1960 and 1961  .  s t a t i o n s , 1961  19  54 59  Relative evaporation at 1.2 m, P/E r a t i o s , and black/white-bulb atmometer r a t i o s f o r subalpine microclimatic s t a t i o n s , 1960 and 1961  20  21  60  Snow depth and duration at three subalpine microclimatic stations and the r e l a t i o n s h i p of snow depth and temperature patterns . . . . .  62  Comparison of 1951 f r o s t - f r e e and snow-free periods, 1960-61 and 1961-62 continuous snow cover, and 1961 and 1962 maximum snow depth at subalpine microclimatic stations  22  53  .  .  Diagrammatic representation of the snow pocket s t a t i o n and d i s t r i b u t i o n of several species at 3575 f t , Mt. Seymour  .  64  67  X  LIST Cf FIGURES (continued) Figure  Page  23  Snow o e l t patterns at the snow pocket s t a t i o n on Mt. Seymour, 1961 and 1962  67  24  S o i l temperature (2 cm) and snow melt patterns at f i v e distances along a transect  70  25  Light i n t e n s i t y pattern and s o i l temperature patterns (2 cm) at the snow pocket s t a t i o n  26  Alpine Rawmark s o i l at a Saxifragetus tolmiei (BP 72)  27  The 'hamada' surface of a T e r r e s t r i a l Raw S o i l habitat  28  A Dystrophic Ranker p r o f i l e  29  (A)  Subalpine Intergrade to Orthic Humic Podzol  (B)  Ignition micro-monolith  .  .  .  .  .  .  .  .  .  .  .  72 89  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . .  .  . .  .  .  .  .  .  .  .  89  .  92  .  97 97  30  A (Peaty) Minimal Podzol p r o f i l e  31  Ortstein Podzol p r o f i l e .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  100  32  Ortstefcn Podzol (7) p r o f i l e  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  100  33  Ignition micro-monolith of an Ortstein Podzol p r o f i l e  34  Gleyed Humic Podzol p r o f i l e (A) and i g n i t i o n micro-monolith (B)  .  .  .  .  .  .  .  .  .  .  .  103  35  Gleyed Humic Podzol p r o f i l e (A) and i g n i t i o n micro-monolith (B)  .  .  .  .  .  .  .  .  .  .  .  103  36  Ignition micro-monoliths of Humic Podzol s o i l s  37  Molken-podzol p r o f i l e  104  38  Humus Podzol p r o f i l e s  106  39  Peaty Low Humic Eluviated Gleysol  40  Snow Basin Anmoor s o i l s  41  (Woody) Organic S o i l  42  Organic S o i l ( O l i g o t r o p h y  43  Organic S o i l (Pernesotrophic Moor)  44  Relationship of snow, depth, centimeters depth of water i n s o i l , and snow-free period p r e c i p i t a t i o n and evaporation f o r the Tsugeto - Cladothaonetum and Vaccinietum d e l i c i o s i communiti es on Mto Seymour, 1961 « « e . . . « . o o o » . - o » . . a o . 1 1 7  45  Relationship of snow depth, centimeters depth of water i n s o i l , and snow-free period p r e c i p i t a t i o n f o r the Abieteto - Tsugetum oertensianae and Chamaecypareto - Lysichitetum communities on Mt. Seymour, 1961 . . . . . . . . . . . . . . . . . . . .  118  Relationships of the major s o i l categories and plant associations  127  46  .  100  .  .  .  .  .  .  .  .  .  .  .  .  .  . .  .  .  . .  .  .  .  .  .  . .  .  .  . .  .  .  .  .  .  .  .  .  .  .  .  .  . 100  .  . . . . . . . . . 1 0 8 .  .  . .  .  .  .  .  .  .  .  .  .  .  .  Moor) (A) and i g n i t i o n micro-nonlith (B) . .  .  . . . . . . . . . 1 0 4  .  .  .  .  . .  .  .  .  .  .  . .  .  .  .  .  .  .  . .  .  .  .  .  .  .  .  .  .  . .  .  . .  . .  .  I .  . .  .  1  . .  .  0 111  .112 1  .  1  3  xi LIST OF FIGURES (continued) Figure  Page'  47  D i s t r i b u t i o n of chemical properties of s o i l s f o r subalpine plant associations  130  48  Relationship of some major s o i l categories to topographic p o s i t i o n , snow duration and moisture regime  .132  49  Saxifragetum tolmiei (BP 72), 5050 feet elevation  142  50  Saxifragetum tolmiei (BP 6 3 ) , 5050 feet elevation  142  51  Gymnomitrium v a r i a n s . an early colonizer i n mat-like forms  143  52  Caricetura n i g r i c a n t i s showing invasion of Phyllodoce and Cassiope heath .  53  Leptarrheneto - Caltheturo leptosepalae forming a s l i g h t l y raised lobe on the seepage area .  54  Phyllodoceto - Cassiopetum mertensianae (BP 75), 4650 feet elevation  .  155  55  Gymnomitrium varians c o l o n i z i n g an eroded s o l i f l u c t i o n area i n the Phyllodoceto - Cassiopetum  155  56  Nano-Tsugetum mertensianae s . nano-tsugetosum mertensianae" (BP 116), 4850 feet elevation  .  .  158  57  Nano-Tsugetum mertensianae s . hippuridetosum montanae (BP 4 0 ) , 3310 feet elevation  .  .  158  58  Vaccinietum d e l i c i o s i (BP 77), 4650 feet elevation  160  59  Tsugeto - Cladothamnetum v . vacciniosum d e l i c i o s i (BP 124), 4000 feet elevation  167  60  The Abieteto - Tsugetum mertensianae microclimatic s t a t i o n (BP 15), 3225 feet elevation  .  .  172  61  Abieteto - Tsugetum mertensianae v . vacciniosum o v a l i f o l i i (BP 8 2 ) , 4530 feet elevation  .  .  172  62  Abieteto - Streptopetum (BP 37), 4050 feet elevation  63  Abieteto - Streptopetum v . tsugosum heterophyllae (BP 17), 3050 feet e l e v a t i o n , Mount  „  144  .  .  .  .  .  174  Seymour, showing the dense herb layer  177  64  Thujeto - Oplopanacetum v . abietetosum amabilis (BP 9 2 ) , 3700 feet elevation  65  Eriophoreto - Sphagnetum (BP 7 8 ) , 4500 feet elevation  66  Diagram showing a representative ridge and p o s i t i o n of the Saxifragetum t o l m i e i , Parkland  67  (Upper) Subzone . * . . . . . . . . Diagram showing the sequence and r e l a t i o n s h i p of biogeocoenotic (ecosystem) units In the Parkland (Upper) Subzone .  68  69  .180 186  .  190 191 .  Sharp d i f f e r e n t i a t i o n of bands of communities surrounding an i s o l a t e d group of t r e e s , 4600 feet e l e v a t i o n , Parkland Subzone . . . . .  192  Sharp d i f f e r e n t i a t i o n of bands of communities adjacent to a more continuous f o r e s t , 4600 feet e l e v a t i o n , Parkland Subzone  70  147  .  .  .  .  .  192  Sharp d i f f e r e n t i a t i o n of the s p r i n g - l i n e and f l u s h habitats of the Leptarrhena - Caltha community from the Phyllodoce - Cassiope heath  .192  xi i LIST OF FIGURES (continued) Figure  Page  71  Relationship of the ecosystem units with s o i l c a t e g o r i e s , snow duration and moisture regime .  72  Diagram showing the sequence and r e l a t i o n s h i p of biogeocoenotic (ecosystem) units i n the  .  Forest (Lower) Subzone  199  73  Map showing the locations where charcoal was found i n s o i l p i t s i n the Garibaldi Park area  74  Decade of establishment f o r tree species on a l l plots and on plots where charcoal was found i n  75  soil pits The e f f e c t of exposure of Abies lasiocarpa tops to extreme weather changes i n winter and protection of the lower branches by snow  193  .  .  .  205  .  207  76  Rapid vegetation and microclimatic differences due to slope and exposure  77  Snowcreep i n spring f l a t t e n s many of the shrubs and trees and causes a strong basal crook or  .  .  .  .  .  .  .  .  .  208  sweep i n the stems . 78  Early snow pocket development around an i s o l a t e d mountain hemlock tree .  79  Rapid vegetative a c t i v i t y of Vaccinium o v a l i f o l i u m following snow melt  204  208 .  .  .  .  .  .  .  . .  210 .  210  ACKNOWLEDGMENT  This t h e s i s , l i k e nost i n ecology, has received c r i t i c a l guidance f r o a i n d i v i d u a l s representing diverse i n t e r e s t s and assistance f r o a many sources. Or. V l a d i a i r J . K r a j i n a , Professor of Plant Ecology, whose s c h o l a r l y i n f l u e n c e , p h i l o s ophy and ecological works are widely known, advised me at the University of B r i t i s h Columbia,  He  gave i n s p i r a t i o n , generous counsel and time which w i l l always be remembered with a p p r e c i a t i o n , and helped to develop the higher ecological units presented i n the t h e s i s . Or. E. B. Peterson shared parts of the f i e l d program with me and permitted me to draw on his basic d a t a .  I value h i s cooperation i n the f i e l d and t h i s additional courtesy.  Financial support f o r the program was provided as studentships from National Research C o u n c i l , from National Research Council Operating Grant T-92 of my a d v i s o r , and f r o a personal sources.  To a l l of these, I am g r a t e f u l . F i e l d and laboratory programs were made possible through the space and f a c i l i t i e s provided  me by the Department of Biology and Botany, f a c i l i t i e s of the Department of S o i l Science f o r the analyses of s o i l s by Mr. B. von S p i n d l e r , by Or. D. B. Turner and the B r i t i s h Columbia Department of Recreation and Conservation, the Greater Vancouver Water Board and Diamond Head Chalets L t d . To ay research and t h e s i s committee and to my ecological colleagues, i am grateful f o r numerous d i s c u s s i o n s , c r i t i c i s m s and considered opinions of d i f f e r e n t aspects of the i n v e s t i g a t i o n . Dr. ill. B. Schofield added much to the study with h i s i n t e r e s t and gave valuable d i r e c t i o n i n the f i n a l preparation of the manuscript. t appreciate the patient support and encouragement given by ay f a m i l y ; Betty, p a r t i c u l a r l y , contributed many tedious hours i n f i n a l and preliminary typing of the tables and manuscript. To ay f a m i l y , ay advisor and my ecological colleagues, I aa indebted.  VEGETATION-ENVIRONMENT RELATIONSHIPS OF SUBALPINE MOUNTAIN HEMLOCK ZONE ECOSYSTEMS  INTRODUCTION  For many geographic areas, the ecological l i t e r a t u r e documents well the environmental differences associated with changes i n the composition, s t r u c t u r e , pattern and dynamics of vegetation.  These r e l a t i o n -  ships are p a r t i c u l a r l y evident i n rigorous high-elevation mountain environments inhere unproductive f o r e s t s give way with increasing elevation to slow-growing isolated t r e e s , alpine tundra areas and often g l a c i e r s on mountains of great r e l i e f .  Such conditions r e f l e c t a complex h i s t o r y , diverse array of h a b i t a t s , and the strong  s e l e c t i v e influence of a rigorous environment on the g e n e t i c a l l y c o n t r o l l e d , p h y s i o l o g i c a l l y and morphologically expressed tolerances of the a v a i l a b l e b i o l o g i c a l populations. In western North America, considerable attention has been given to these vegetation-environment  relation-  ships i n alpine and a r c t i c tundra areas ( c f . C h u r c h i l l and Hanson 1958, B l i s s 1962), or i n areas with merchantable and productive f o r e s t s ( c f . Krajina 1952 et s e q . , Daubenmire 1952, Becking 1954 and 1956, among o t h e r s ) . With the exception of studies i n the Rocky Mountains (Daubenmire 1952, Oosting and Reed 1952, E l l i s o n 1954, Man* 1961, and Patten 1963), less attention has been given to the ecological characterization and evaluation of subalpine areas.  Elsewhere, subalpine l i t e r a t u r e includes generalizations and descriptions which have been made  from phytogeographic or zonal treatments of the vegetation, local f l o r a s , timberline s t u d i e s , or other studies where ecology was not of p a r t i c u l a r concern.  Daubenmire (1943, 1952) summarized much of the environmental and  zonal information a v a i l a b l e f o r the Rocky Mountains, Krajina (1959) presented an o u t l i n e of c l i m a t i c , edaphic and vegetation differences f o r B r i t i s h Columbia i n a b i o c l i m a t i c c l a s s i f i c a t i o n , and Heusser (1960) included some d e t a i l s known f o r coastal subalpine areas i n h i s comprehensive i n t e r p r e t a t i o n of l a t e - P l e i s t o c e n e environments along the North P a c i f i c Coast.  The l i m i t e d quantitative information on environments i n r e l a t i o n to coastal  subalpine vegetation constitutes an unfortunate void i n the ecology of western North America.  Information on  the c l i m a t e , microclimates and s o i l s , p a r t i c u l a r l y , i s e i t h e r non-existent or very meagre and t h i s has l i m i t e d ecological assessment of subalpine vegetation-environment  relationships.  In 1959, I undertook a m u l t i - f a c t o r  study i n cooperation with Peterson (1964, 1965) to obtain such information from a coastal subalpine area near Vancouver i n the Coast Mountains of southwestern B r i t i s h Columbia. The purpose of t h i s thesis i s 1) to obtain quantitative and q u a l i t a t i v e data f o r c h a r a c t e r i z a t i o n of subalpine microclimates and s o i l s , 2) to describe, integrate and Interpret t h e i r r e l a t i o n s h i p s with vegetation based  2 l a r g e l y on the plant communities described by Peterson (1964), and 3) to incorporate these r e l a t i o n s h i p s into a f l e x i b l e c l a s s i f i c a t i o n of i d e n t i f i a b l e subalpine ecosystematic u n i t s . The approach, concept and presentation of material In t h i s study, as i n a l l synecological s t u d i e s , the question at once a r i s e s as to what level of generalization and on what basis data are to be evaluated i n order to c l a r i f y r e l a t i o n s h i p s .  Comprehen-  sive d e t a i l e d discussions and reviews of various approaches, concepts and problems involved i n ecological studies have been given by Tansley (1935), Sukachev (1945, 1960), Major (1951), B i l l i n g s (1952), Daubennrire (1952), Poore (1955, 1956, 1962), Becking (1957), Hanson (1958), C h u r c h i l l and Hanson (1958), Krajina (1960, 1965), Rowe (1960), Whittaker (1962), Waring and Major (1964), and Sukachev and O y l i s (1964).  It i s important here only to outline and c l a r i f y the approach and concept that I have adopted  i n consequence. A common experience of many plant ecologists i s that plants are generally not randomly d i s t r i b u t e d (Poore 1962, Greig-Smith 1964); quantitative and q u a l i t a t i v e differences occur i n plant d i s t r i b u t i o n from place to place r e s u l t i n g i n the development of vegetation pattern and s t r u c t u r e .  The d i s t r i b u t i o n and  pattern of vegetation apparent i n a landscape i s commonly described as a 'complex mosaic'; individual pieces of the mosaic r e f l e c t p a r t i c u l a r combinations of the holocoenotic environment ( B i l l i n g s 1952) which may be subdivided into c l i m a t i c , b i o t i c , topographic and parent material factors a l l modified by time f o r purposes of study (Jenny 1941,  1958, and 1961, Major 1951, Crocker 1952, and Krajina 1965).  The  i n t e r r e l a t i o n s h i p s of these factors provided the conceptual basis f o r evaluation of subalpine vegetationenvironment patterns and dynamics and f o r designation of the various units described as ecosystematic ( c f . Tansley 1935) or biogeocoenotic ( c f . Sukachev 1945, 1960).  The approach may be separated into two  stages, analysis and s y n t h e s i s , as f o l l o w s . Sample plots f o r analysis were j o i n t l y selected with Peterson (1964) so that each represented a community making up the subalpine landscape ' m o s a i c ' .  Communities of rock c l i f f s and ledges, bryophyte  and lichen communities of exposed rock k n o l l s or s l i d e d e b r i s , and aquatic communities, however, were not sampled.  Peterson analyzed the vegetation on each plot quantitatively and q u a l i t a t i v e l y employing the  phytosociological techniques of the Zurich-Montpellier School (Braun-Blanquet 1932, Krajina 1933, and Becking 1957).  To provide a comparable basis f o r d e s c r i p t i o n and evaluation of the habitats and f o r empir-  i c a l snvironmental v e r i f i c a t i o n of the vegetation u n i t s , major emphasis i n the present study was placed on to  3 environmental factors which could be measured.  These included the morphological and a n a l y t i c a l properties  of the s o i l s , topography (slope, exposure and e l e v a t i o n ) , and microclimate (temperature, evaporation, humi d i t y , p r e c i p i t a t i o n , snow duration, snow depth and s o i l temperature) and s o i l moisture on selected p l o t s . Parent material was assessed i n d e s c r i p t i v e terms on the basis of o r i g i n and rock type.  These data com-  bined with f i e l d habitat descriptions and observations over a f i v e - y e a r period provided the basic data f o r the environmental analysis and synthesis.  Methods of microclimatic measurement and s o i l analysis are  outlined i n d e t a i l l a t e r i n the thesis and generally followed the procedures of McMinn (1957), M u e l l e r Dombois (1959), Lesko (1961), Eis (1962) and Smith (1963) i n other environmental studies of d i f f e r e n t biogeoclimatic areas i n B r i t i s h Columbia. From the a n a l y t i c a l data, each sample plot consists of a single set of values which represent local h i s t o r i c a l l y developed v a r i a t i o n s and patterns of topography, s o i l , vegetation and microclimate within a broader biogeoclimatic concept of the Subalpine Mountain Hemlock Zone as described by Krajina (1959, 1962 and 1965).  In the sense of Sjors (1955), Marr (1961) and Orloci (1964), each sample p l o t represents  an i n d i v i d u a l ecosystem or biogeocoenosis type characterized i n terms of the properties just mentioned. While i t i s r e a d i l y apparent that no plots of the one hundred fourteen analyzed i n the above manner are exactly identieal i n every d e t a i l , comparison of the vegetation and environmental data reveal that c e r t a i n plots have many s i m i l a r i t i e s i n both f l o r i s t i c and habitat c h a r a c t e r i s t i c s .  These are grouped  together f o r d e s c r i p t i v e purposes using a synthesizing procedure c l o s e l y resembling the process of "successive approximation" described by Poore (1955, 1962).  "Successive approximation" i n t h i s study was  extended to include environmental features whereby vegetation-environmental l i s t s of values by p l o t are exhaustively compared f o r s i m i l a r i t i e s and d i f f e r e n c e s , consistency of groups and conformity to a general pattern of r e l a t i o n s h i p s .  In t h i s way, various ecosystematic units at d i f f e r e n t l e v e l s of generalization  are developed by a n a l y s i s , synthesis and s t r a t i f i c a t i o n on the basis of both f l o r i s t i c and environmental variables.  Units are named i n accordance with the Zurich-Montpellier School to indicate systematic rank  and are characterized by quantitative and q u a l i t a t i v e environmental  'parameters' together with the char-  a c t e r i s t i c combination of species of the phytocoenosis ( c f . Peterson 1964, Orloci 1964).  Coenotic, sub-  zonal and zonal units are the basis f o r evaluation and i n t e r p r e t a t i o n of ecosystematic r e l a t i o n s h i p s and dynamics.  It i s believed that use of the ecosystem (biogeocoenotic) concept at l e v e l s of generalization f r o a small to very broad provides a f l e x i b l e but i d e n t i f i a b l e dynamic system s u f f i c i e n t l y large f o r p r a c t i c a l purposes yet s u f f i c i e n t l y detailed f o r further basic s c i e n t i f i c s t u d i e s . Presentation of material c l o s e l y follows the a n a l y t i c and synthetic stages by which the study was conducted.  Following the Introduction, a Regional Description presents characterizing features of the  Subalpine Mountain Hemlock Zone and describes the topography,  geology, c l i m a t e , Pleistocene events and  h i s t o r y , and general c h a r a c t e r i s t i c s of the vegetation of the study areas.  The next three s e c t i o n s ,  Subalpine Microclimates and Climate, Subalpine S o i l s , and Subalpine Ecosystems, include descriptions and evaluation of the data r e s u l t i n g from the analysis and s y n t h e s i s . a d e s c r i p t i o n of the methods of study f o r the readers convenience.  Each of these sections i s preceded by The arrangement of presenting the  environmental r e s u l t s p r i o r to the d e s c r i p t i o n of the ecosystematic units i s made because i t i s f e l t that these sections include the necessary background information on which the Subalpine Ecosystems section i s e c o l o g i c a l l y organized.  The section Vegetation-environment  Relationships i n t e r p r e t s and evaluates the  data, dynamics and i n t e r r e l a t i o n s h i p s of the units at a l l systematic l e v e l s with reference to the contemporary and apparent h i s t o r i c a l pattern of development of the coastal subalpine landscape. Appendices include a c h e c k l i s t of the plant species, detailed summaries of the microclimatic records d e s c r i p t i o n s , chemical analyses and moisture content of selected subalpine s o i l s , and the vegetation synthesis t a b l e s . the environment-vegetation  environment-  Explanatory notes on the symbols used f o r the horizon terminology and f o r  synthesis tables are also included i n the Appendices.  5  REGIONAL DESCRIPTION  The Subalpine Mountain Hemlock Zone occurs on the crests and slopes of innumerable peaks and ridges forming the Coast Mountains.  These mountains form a rugged, strongly a r t i c u l a t e d chain of bold r e l i e f  along the mainland coast of B r i t i s h Columbia and extend north from Vancouver into the Yukon.  Fiords and  sounds which penetrate deeply inland from the P a c i f i c Coast interrupt the continuity of the zone and provide termini f o r the many r i v e r s and streams cascading down the mountain slopes from sources near g l a c i e r s and late-melting snow accumulation areas at subalpine and alpine elevations.  Valleys have steeply sloping  sides and are narrow and generally deeply entrenched into the i n t r u s i v e complex of the Coast Mountains. There are few through-valleys which dissect the range and l i n k i t s coastal and i n t e r i o r s i d e s .  The physio-  graphic h i s t o r y , features and processes of t h i s rugged largely inaccessible area are described i n d e t a i l in Bostock (1948), Heusser (1960), and Holland (1964). The climate i s mild along windward P a c i f i c slopes of the Coast Mountains but conditions change rapidly with increasing elevation and distance from the P a c i f i c Ocean.  The moderating maritime influence  of the ocean, the pressure patterns which contribute to a generally onshore c i r c u l a t i o n of a i r , and the b a r r i e r effect of the Coast Mountains create considerable differences i n temperature and p r e c i p i t a t i o n with both p o s i t i o n (windward or leeward) and elevation along the mountain chain (Trewartha 1943, Chapman 1952, Kendrew and Kerr 1955, and t a l k e r 1961).  Moisture-laden a i r masses from P a c i f i c source regions, although  more common i n winter and f a l l , bring much cloud and p r e c i p i t a t i o n to the area at most times during the year.  A late f a l l and winter p r e c i p i t a t i o n maximum combined with low temperatures at high elevations r e s u l t  in great accumulations of snow which p e r s i s t s u n t i l l a t e spring and early sunnier at most subalpine e l e v a t i o n s . Such a p r e c i p i t a t i o n and temperature pattern has contributed to Pleistocene g l a c i a t i o n i n the past and i s s t i l l s u f f i c i e n t to maintain numerous mountain g l a c i e r s and snow f i e l d s within the Coast Mountains. The d i s t r i b u t i o n and pattern of vegetation i n the Coast Mountains now r e f l e c t s both the many changes which have occurred since that time and the strong c l i m a t i c and physiographic influence of t h i s mountainous area.  Physiographic and c l i m a t i c c h a r a c t e r i s t i c s associated with the d i s t r i b u t i o n a l patterns of tree  species have been widely employed as a c l a s s i f i c a t i o n basis f o r broad vegetation patterns along the P a c i f i c slopes.  Whitford and Craig (1918) recognized four c l i m a t i c forest types, Halliday (1937) included a l l  6 areas dominated by coastal coniferous forests into an extremely broad and heterogeneous unit which he c a l l e d "The Southern Coast S e c t i o n " , Rowe (1959) revised and separated the "Coastal Subalpine Section" from H a l l i d a y ' s u n i t , and Krajina (1959) described four b i o c l i m a t i c zones f o r the coastal mainland area of B r i t i s h Columbia.  S o i l s were included subsequently as a t h i r d c r i t e r i o n f o r the d i f f e r e n t i a t i o n and  designation of biogeoclimatic zones (Krajina 1962, 1965) and zonal categories were established at three broad l e v e l s of generalization (biogeoclimatic regions, zones and subzones); regions and zones were considered comparable, r e s p e c t i v e l y , to the formations and associations i n the sense of both Clements (1928) and Weaver and Clements (1938).  Following K r a j i n a ' s biogeoclimatic c l a s s i f i c a t i o n of B r i t i s h Columbia,  the study area i s part of the P a c i f i c Coastal Subalpine Forest Region and I t s only zonal category, the Subalpine Mountain Hemlock Zone. C h a r a c t e r i s t i c s of the Subalpine Mountain Hemlock Zone and features d i f f e r e n t i a t i n g i t from adjacent zones have been given by Krajina (1959, 1965), Peterson (1964), and Orloci (1964).  These are b r i e f l y  reviewed i n the following paragraphs and the remainder of t h i s section i s concerned with a more d e t a i l e d d e s c r i p t i o n of the study a r e a .  The Subalpine Mountain Hemlock Zone In the biogeoclimatic c l a s s i f i c a t i o n of Krajina (1962, 1965), each zone i s characterized i n terms of macroclimate (temperature and p r e c i p i t a t i o n ) , vegetation of the mesic (zonal) h a b i t a t s , and zonal s o i l c h a r a c t e r i s t i c s which r e f l e c t the dominant regional pedogenlc processes of these h a b i t a t s .  On t h i s b a s i s ,  K r a j i n a ' s d e s c r i p t i o n of the Subalpine Mountain Hemlock Zone i s as follows Macroclimate ^ ;  mainly Dfc (Kb'ppen system) — a microtherraal subcontinental (subalpine) humid climate with heavy snow cover Annual t o t a l p r e c i p i t a t i o n (inches) (70) 87 - 170 Annual snowfall (inches) 110 - 800 Mean annual temperature ( F^ 38 - 44 (tentative) Number of months: above 50 F 2 - 3(4)(tentative) below 32°F 1 6 (tentative) Number of f r o s t - f r e e days  Altitude (feet):  ^  B r i t i s h Columbia:  North South  40 - 120  (tentative)  1000 - 2500 (  3000 - 5000 (windward slopes)  (  3700 - 6000 (leeward slopes)  Macroclimate symbols (Kb'ppen): D climates: f  :  cold snowy forest climate (humid microthermal); average temperature of coldest month below 26.6 F; average temperature of warmest month above 5 0 ° F . no d i s t i n c t dry season; d r i e s t summer month with more than 1.2 inches p r e c i p i t a t i o n ,  c  :  cool short summer; l e s s than 4 months above 50 F.  7 Vegetation:  Climatic climax a s s o c i a t i o n s :  Climatic climax tree species: Soil:  Abieteto - Tsugetum mertensianae (Forest Subzone) Tsugeto - Vaccinietum nembranacei (Parkland Subzone) 2) Tsuqa mertensiana (mountain hemlock)  P r e v a i l i n g pedogenic processes: strong p o d z o l i z a t i o n , strong mor formation and strong gleization Zonal s o i l s  :  Subalpine humic (humus) podzol  Humus  :  Ligno-mycelial mor  It i s evident that macrodistatic and s o i l c h a r a c t e r i s t i c s are not as obvious and therefore as useful as the vegetation f o r f i e l d recognition of the zone.  As s p e c i f i c f l o r i s t i c information was not known u n t i l  the study of Peterson (1964), i t mas necessary to base f i e l d recognition of the zone on the d i s t r i b u t i o n a l p a t t e r n , presence and/or absence of p a r t i c u l a r tree s p e c i e s .  Tsuqa mertensiana aas selected f o r t h i s purpose  as i t s main d i s t r i b u t i o n a l area i s c l i m a t i c a l l y d i s t i n c t and i t has been recognized as a c l i m a t i c climax tree species (Oaubenmire 1952, Krajina 1959). as f o l l o w s :  For t h i s study, f i e l d recognition and d e l i m i t a t i o n of the zone was  that forested or p a r t i a l l y forested area l y i n g within the main d i s t r i b u t i o n a l area of Tsuqa  mertensiana. associated with Abies amabilis and Chamaecyparis nootkatensis. and which occurs a l t i t u d i n a l l y above the main d i s t r i b u t i o n a l area of Tsuqa heterophylla. Thuja p l i c a t a and Pseudotsuqa m e n z i e s i i .  Areas  were considered within the lower a l t i t u d i n a l l i m i t s of the zone, when i n addition to t h i s c r i t e r i o n . Tsuqa mertensiana was e i t h e r the dominant tree species present or was present i n greater number than Tsuqa heterophylla — - the zonal climax tree species of the adjacent a l t i t u d i n a l l y lower zone (Orloci 1964). These c r i t e r i a are s i m i l a r to those employed by Peterson (1964) to d e l i m i t the lower a l t i t u d i n a l l i m i t of the zone.  Peterson (1964) defined the upper l i m i t of the zone on the basis of the presence of Tsuqa  mertensiana i n tree form to d i f f e r e n t i a t e i t from the Alpine Zone where mountain hemlock may occur but only as a krummholz growth form (Archer 1963). There are several reasons which make i t d i f f i c u l t to present a precise d e f i n t i o n f o r the upper l i m i t of the zone.  These a r e :  a) sparsity of tree cover near the apparent a l t i t u d i n a l tree l i m i t (see Figure  1),  b) the influence of recent and contemporary g l a c i a t i o n near Mt. Garibaldi, (8767 f t ) which affords a r e l i e f where tree l i m i t might be r e a d i l y recognized, and c) c l i m a t i c f l u c t u a t i o n s which have evidently been respons i b l e f o r the presence of trees at higher elevations i n the past (Taylor 1937,  Mathews 1951,  No attempt aas made, consequently, to p r e c i s e l y define the upper l i m i t of the zone. 2) Species authorship i s given i n Appendix  I.  and Archer 1963).  The upper l i m i t was  Figure 1.  The Subalpine Mountain Hemlock Zone •— a panoramic view i n Garibaldi Park. (Elevation range shown i s from approximately 4000 f t (lower l e f t ) to the 8700 f t south peak of Mount Garibaldi (Atwell Peak, upper l e f t ) .  The  upper l i m i t of the subalpine zone i s at approximately 5500 - 5800 f t e l e v a t i o n .  Round Mountain  i s the long ridge i n the r i g h t foreground).  tentatively designated by a r b i t r a r i l y joining the highest elevations with trees present on a e r i a l photographs, t r a n s f e r r i n g t h i s information to maps and considering elevations below the projected l i n e s as representing subalpine c o n d i t i o n s . The Subalpine Mountain Hemlock Zone has a t h i r d boundary which occurs toward the leeward side of the Coast Mountains.  This boundary i s represented by the Engelmann Spruce - Subalpine F i r Zone  a zone  which may be recognized as before by being outside the main d i s t r i b u t i o n a l area of Tsuga mertensiana and within the main d i s t r i b u t i o n a l area of Picea enqelmannii and Abies l a s i o c a r p a . Environmental  differences between the Subalpine Mountain Hemlock Zone and the adjacent zones have  been described i n d e t a i l i n Krajina (1959 and 1965) and Orloci (1964).  Important differences are mentioned  under the appropriate heading i n the d e s c r i p t i o n of the study area.  The Study Area Local areas which were studied i n d e t a i l include part of Garibaldi Provincial Park (Round Mountain Oiamond Head area) and the North Shore Mountains (The L i o n s , Grouse Mountain and Mount Seymour areas) (Figure 2 ) .  Broadly defined, these areas are near or along 123°00 U longitude and between 49°15 and 50°00  N latitude.  Much of t h i s area i s considered unproductive f o r f o r e s t s (Slhitford and Craig 1918;  Forest Service 1957)  B. C.  watershed and recreational resources, however, are of great importance to the  densely populated metropolitan area of Greater Vancouver, B r i t i s h Columbia, some 5 to 40 miles to the south.  With the exception of the few access roads, t r a i l s and s k i i n g f a c i l i t i e s , the area i s l i t t l e d i s -  turbed. Subalpine areas within the Coast Mountains are largely inaccessible and known only to the mountaineer or explorer.  Year-round a c c e s s i b i l i t y necessary f o r c l i m a t i c measurements and environmental  was a major consideration governing choice of area.  observations  The area selected (Figure 2) f u l f i l l e d t h i s r e q u i r e -  ment and, i n a d d i t i o n , represents much of the physiographic h i s t o r y , features and processes described f o r t h i s mountain chain (Bostock 1948, Heusser 1960, and Holland 1964), the general macroclimatic patterns and controls of the B r i t i s h Columbia mainland, the approximate midway l a t i t u d i n a l point of the main d i s t r i b u t i o area of Tsuga mertensiana ( c f . range map i n Heusser 1960), and the strong c l i m a t i c and physiographic i n fluence of t h i s mountainous area on the d i s t r i b u t i o n and pattern of vegetation.  Explanatory notes to accompany Figure 2.  The major d i v i s i o n s on the map are based a r b i t r a r i l y on a l t i t u d e ranges to emphasize r e l i e f . Although the range 3000 - 6000 f t includes the Subalpine Mountain Hemlock Zone, zonal boundaries vary with p o s i t i o n from the coast as explained i n the t e x t . Zonal a l t i t u d i n a l l i m i t s vary from approximately 3000 - 5000 f t north of Burrard Inlet (lower part of map) to 3700(4000) - 5500 (5800) f t i n the Mt. Garibaldi area (upper part of map). D i s t r i b u t i o n of p l o t s used i n the study: North Shore Mountains including:  62 p l o t s  Mt. Seymour  44 p l o t s  Grouse Mountain  9 plots  The Lions  2 plots  Hollyburn Ridge  7 plots  Round Mountain  47 p l o t s  Garibaldi Park including:  52 p l o t s Oiamond Head area  5 plots  Climatic and snow course s t a t i o n s shown on map: Climatic stations 1 2 3 4 5 6 7 8 9 10  Squamish altitude: B r i t t a n i a Beach Tunnel Camp ( B r i t t a n i a ) Hollyburn Ridge Grouse Mountain Mosquito Creek Seymour F a l I s Mount Seymour Coqui tlam Lake Garibaldi  5 160 2200 3120 3625 1130 674 2700 528 1200  ft ft ft ft ft ft ft ft ft ft  Snow course s t a t i o n s A B C 0 E F G  Loch Lomond Palisade Lake Burwell Lake Hollyburn Grouse Mountain Dog Mountain Seymour Mountain  3600 f t 2900 f t 2900 f t 3350 3800 3550 3650  ft ft ft ft  Topography Approximately  11,000+ years ago (Heusser 1960), topographic features of the study area were almost  completely concealed by a vast continental i c e sheet.  Pre-Pleistocene u p l i f t resulted i n increased  erosion of valleys (Davis and Mathews 1944) and these p r e - g l a c i a l l i n e s of drainage, represented within Figure 2 by the major r i v e r v a l l e y s and f i o r d s , were widened and deepened by the i c e sheet (Burwash Davis and Mathews 1944).  1918,  Upper known l i m i t s of the C o r d i l l e r a n i c e sheet range from 5000 f t just north  of Burrard Inlet to 7000 f t at alpine elevations i n the v i c i n i t y of Garibaldi Lake (James 1929, Mathews 1958, Glacial Map of Canada 1958).  Wane of the ice revealed rounded peaks and ridges such as those of  Mt. Seymour (4766 f t ) , Grouse Mountain (3974 f t ) ,  The Lions (5245 and 5401 f t ) and Round Mountain (4870  to 5420 f t ) . Movement of the ice sheet removed much of the weathered mantle of earth from the rock surfaces, smoothed the surfaces of the rock and, on wane of the i c e , varying depths of g l a c i a l t i l l and areas of rock were exposed.  Since Pleistocene g l a c i a t i o n , local mountain g l a c i e r s i n parts of the study area have  further modified the land features.  B a s a l , l a t e r a l and terminal moraines, c i r q u e s , small hanging v a l l e y s ,  small eskers and other g l a c i a l forms are conspicuous i n the Garibaldi Park area.  Near Squamish, Mathews  (1951, p. 373) found cirques at elevations below 4000 f t which "contain no moralnal ridges to indicate the presence of alpine g l a c i e r s at any time since the disappearance of the C o r d i l l e r a n i c e sheet". the North Shore Mountains, a s i m i l a r s i t u a t i o n occurs at elevations as low as 3200 f t .  On  It i s apparent  that i f "alpine g l a c i a t i o n " occurred subsequent to withdrawal of the C o r d i l l e r a n i c e sheet i n the North Shore Mountain area, the current erosion cycle has removed t h e i r morainal ridges or the local g l a c i e r s were of l i t t l e s i g n i f i c a n c e i n e f f e c t i n g modifications of the topography.  Mathews (1951) interprets  such low-elevation cirques as belonging to a period of alpine g l a c i a t i o n preceding the climax stage of the C o r d i l l e r a n i c e sheet.  Following the four phases of g l a c i a t i o n described by Davis and Mathews (1944),  the alpine g l a c i e r s sculpturing these cirques may have subsequently increased i n s i z e and coalesced into a stage of g l a c i a t i o n reaching i c e sheet proportions. P o s t - g l a c i a l processes have further altered the earth mantle.  L o c a l l y , s o l i f l u c t i ' o n at high a l t i -  tudes has s h i f t e d surface material downslope ( c f . Brink 1964), small basins have been p a r t i a l l y f i l l e d i n with water- and snow-deposited inorganic and organic sediments, and s l i d e s scar many of the steep mountain slopes leaving a narrow swath of talus b l o c k s , debris and exposed rock.  Sheet-wash i s pronounced  13 on slopes l i t t l e protected by a vegetational cover, snowcreep nay remove loose debris from snoothened rock surfaces (Mathews and Mackay 1963), and freeze-thaw cycles may contribute to nixing of the surface s o i l or be an important f a c t o r i n surface weathering and e x f o l i a t i o n of rocks (Peterson 1964). Topography of the North Shore Mountain area i s rugged and broken. p a r t i c u l a r l y , are steep and p r e c i p i t o u s . l i k e basins. till.  East, west and north-facing s l o p e s ,  Ponds and snail lakes occur i n many of the depressions and c i r q u e -  Peaks and ridges are rounded i n p r o f i l e and flanked on t h e i r sides by variable thicknesses of  Exposed rock surfaces are common at higher elevations i n the subalpine zone.  ridges and slopes have few exposed rock surfaces, t i l l  At lower e l e v a t i o n s ,  i s deeper and the r e l i e f l e s s abrupt and broken.  Benches, slopes and a l l but the peaks and small ridge crests are strewn with boulders. Topography of the subalpine zone i n the Round Mountain - Diamond Head area i s generally i n sharp contrast.  Round Mountain i s an elongated north-easterly trending ridge with steep but generally smooth  p r o f i l e s and contours (Figure 1).  With the exception of the highest points along t h i s ridge and the few  t a l u s slopes along i t s length, exposed rock surfaces are comparatively few.  Boulders scattered near and on  the surface are common only l o c a l l y at higher elevations within the zone but appear somewhat more frequent on the lower forested slopes near the southwestern end of Round Mountain. Quaternary Pele'an eruptions i n the Diamond Head area (Mathews 1952a, 1952b) account f o r some of the major topographic differences between the Garibaldi and North Shore Mountain areas.  From the main topo-  graphic center of the eruption (Mt. Garibaldi 8787 f t , and Atwell Peak i n Figure 1 ) ,  t u f f breccias and  other volcanic debris ranging i n s i z e from large blocks to dust were deposited over the foundation surfaces of the i n t r u s i v e rocks and the surfaces of the C o r d i l l e r a n i c e sheet which was gradually waning i n the immediately surrounding v a l l e y s .  Lava flows emanating from other local centers surrounding the massif add  to the variety of the geomorphic processes and forms evident i n t h i s area.  Lava flows from C l i n k e r Mountain  a few miles north of Mt. Garibaldi which ponded against the i c e sheet indicate the approximate period i n which these events took place (Mathews 1952b).  On wane of the ice sheet, much of the volcanic debris  slumped i n t o the v a l l e y s (Mathews 1952a) and subsequent alpine g l a c i a t i o n i n the area has considerably modified tee shape of the o r i g i n a l cone. however, s t i l l  The long gradually i n c l i n e d slope of the volcanic cone s u r f a c e ,  remains evident (Figure 1, upper l e f t surface below Atwell  Peak).  Topographic differences i n combination with f u r t h e r differences i n geology and history described l a t e r provide a convenient basis f o r separation of the study area i n t o two major u n i t s :  the North Shore  14 M o u n t a i n a r e a and t h e G a r i b a l d i  Park (Round Mountain - Diamond Head) a r e a . Geology  The geology are l i s t e d  of the study  i n Table 1.  a r e a i s w e l l known.  Rock t y p e s and bedrock u n i t s o c c u r r i n g i n t h e  The p r e s e n c e of Quaternary v o l c a n i c r o c k s i n the G a r i b a l d i  a r e a and t h e i r absence  i n the N o r t h Shore Mountain a r e a i s t h e major d i f f e r e n c e i n geology v i i t h i n the study Bedrock t y p e s exposed o r u n d e r l y i n g t i l l  area  area.  i n The L i o n s and the Grouse Mountain a r e a s ( T a b l e 1)  g r a n o d i o r i t e s and q u a r t z d i o r i t e s of the M e s o z o i c C o a s t i n t r u s i v e s .  include  P l a g i o c l a s e and ' h o r n b l e n d e form  h i g h e s t f e l d s p a r and m a f i c c o n t e n t s r e s p e c t i v e l y of t h e s e r o c k s a l t h o u g h t h e i r p e r c e n t c o n t e n t s are (Armstrong  1954).  variable  Mount Seymour d i f f e r s s l i g h t l y i n geology from the o t h e r t l o r t h Shore Mountains which are  almost e x c l u s i v e l y g r a n i t i c .  A n d e s i t i c porphyries  (greenstone)  and o t h e r m e t a v o l c a n i c s of the  Mesozoic  C h e h a l i s v o l c a n i c group C3p the h i g h e s t e l e v a t i o n s of Mount Seymour and o v e r l i e m i g m a t i t e and o t h e r r o c k s of the C o a s t i n t r u s i v e s (Burwash 1918,  Roddick and Armstrong  Q u a t e r n a r y v o l c a n i c r o c k t y p e s i n the G a r i b a l d i m e t a v o l c a n i c and and b a s a l t s .  raetasediraentary  rocks.  of C r e t a c e o u s q u a r t z d i o r i t e s ,  The v o l c a n i c s i n c l u