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Analysis and modelling of interspecies competition during forest secondary succession Bellefleur, Pierre 1978

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Analysis  and m o d e l l i n g o f i n t e r s p e c i e s c o m p e t i t i d u r i n g f o r e s t secondary s u c c e s s i o n by PIERRE BELLEFLEUR  B.A. (Hon.). U n i v e r s i t y o f M o n t r e a l , 1967 B.Sc. (Hon.), U n i v e r s i t y o f M o n t r e a l , 1970 M . S c , M c G i l l U n i v e r s i t y , 1972  A THESIS SUBMITTED IN PARTIAL FULFILLMENT OF THE REQUIREMENTS FOR THE DEGREE OF DOCTOR OF PHILOSOPHY  in THE FACULTY OF GRADUATE STUDIES I n s t i t u t e o f Animal Resource E c o l o g y and Department o f Zoology  We accept t h i s t h e s i s as conforming t o the r e q u i r e d s t a n d a r d  THE UNIVERSITY OF BRITISH COLUMBIA May, 1978  Copyright  1978,  Pierre Beliefleur  In  presenting this  thesis  an advanced degree at the L i b r a r y I  f u r t h e r agree  for  scholarly  by h i s of  shall  make i t  that permission  I agree  r e f e r e n c e and  f o r e x t e n s i v e copying o f  this  i s u n d e r s t o o d that gain shall  n  e  1  6  t  h  1  9  7  8  Columbia  for  that  study. thesis or  copying o r p u b l i c a t i o n  not be a l l o w e d without my  Z o o l o g y , I n s t i t u t e o f Animal Resource E c o l o g y  2075 W e s b r o o k P l a c e V a n c o u v e r , Canada V6T 1W5  u  It  for financial  The U n i v e r s i t y o f B r i t i s h  J  for  Columbia,  permission.  Department o f  Oate  freely available  the requirements  purposes may be g r a n t e d by the Head o f my Department  thesis  written  fulfilment of  the U n i v e r s i t y of B r i t i s h  representatives.  this  in p a r t i a l  THESIS ABSTRACT  The  C o a s t a l f o r e s t of southwestern B r i t i s h Columbia i s examined  at t h r e e l e v e l s of i n t e r p r e t a t i o n : the B i o g e o c l i m a t i c Subzone the p l o t  l e v e l , and  the s i n g l e t r e e l e v e l .  These l e v e l s correspond  the t h r e e major s t r a t a of the p o p u l a t i o n : the geographic community, and observations The level,  on 730  highest  covers  The  d a t a base c o n s i s t s of 40 years  climate.  The  of  e l e v a t i o n B i o g e o c l i m a t i c Subzones.  The  age  on an average span of 80 years  type to another,  varied  t o t a l study a r e a i s s u b d i v i d e d i n t o  The v e r y nature  five  s t r u c t u r e of each  and f o r e s t - t y p e of f o r e s t  succession  w i t h a f i n i t e number o f p o s s i b l e f o r e s t - t y p e s  over the time h o r i z o n , seems admirably  s u i t e d f o r a f i n i t e - s t a t e Markov  However, the Markov models cannot f i t adequately  t i o n s at the subzone l e v e l because t r a n s i t i o n p r o b a b i l i t i e s  the  observa-  are not  e n t i r e l y time-homogeneous and because t h e r e i s a wide range of and  the  Permanent Sample P l o t s d e s c r i b i n g over 70,000 t r e e s .  s u c c e s s i o n dynamics i s d e s c r i b e d .  process.  to  l e v e l of i n t e r p r e t a t i o n , the B i o g e o c l i m a t i c Subzone  subzone i s analysed  from one  range,  s e v e r a l thousand square k i l o m e t e r s of extremely  topography and main low  the i n d i v i d u a l .  level,  communities  o r i g i n s of p e r t u r b a t i o n w i t h i n a subzone. The  sample p l o t  i s considered forest.  The  l e v e l of i n t e r p r e t a t i o n  s u f f i c i e n t l y homogeneous t o r e p r e s e n t  The  growth of a g i v e n s p e c i e s i s l i k e l y to  i n a pure f o r e s t than i n a mixed one,  and  l a r g e r u n i t s of  e n t i r e f o r e s t can be d e s c r i b e d by the agglomeration  fundamental u n i t s . different  o f f e r s an i n t e r m e d i a t e  of  the  be  and between d i f f e r e n t  types o f mixed f o r e s t s .  Tree species  v a r i a b l e s with the highest  which r e p r e s e n t any  given  growth.  Subzone i s d i v i d e d i n t o s e v e r a l  plot-types  fundamental u n i t s o f f o r e s t c o m p o s i t i o n . . The growth o f  species  shows, i n d e e d , s i g n i f i c a n t v a r i a t i o n from one p l o t -  type t o another.  The trends  i n succession  a t t h e p l o t type l e v e l  c l o s e l y w i t h those observed a t t h e B i o g e o c l i m a t i c i s hypothesized that succession v a r i a t i o n i n species t i o n s and  of b i o t i c  biomass and a r e e s t i m a t e d t o have a h i g h  b i o t i c impact on each o t h e r ' s Each B i o g e o c l i m a t i c  c o n s t i t u t e the p o o l  Subzone l e v e l .  coincide Thus i t  a t the subzone l e v e l i s a consequence o f  growth r a t e between p l o t ' t y p e s , due t o s i t e  condi-  competition.  At t h e lowest stratum o f t h e p o p u l a t i o n , regeneration  o f a s i n g l e t r e e are i n v e s t i g a t e d .  t h e growth, m o r t a l i t y , and The growth r a t e o f a t r e e  i s dependent on i t s p a s t h i s t o r y , on t h e c l i m a t i c and g e o g r a p h i c compo-. nents c h a r a c t e r i z i n g a B i o g e o c l i m a t i c growing i n i t s immediate neighborhood. significant The  Subzone, and on t h e o t h e r  These v a r i a b l e s have a v e r y  e f f e c t on whether a t r e e l i v e s or d i e s i n any time p e r i o d .  a n a l y s i s i n d i c a t e s t h a t r e c e n t l y dead stems appear t o have a h i s t o r y  of sub-standard growth when compared w i t h t h e p o p u l a t i o n .  Moreover, the  immediate neighborhood o f dead stems corresponds t o a s p e c i f i c and  trees  composition  s t r u c t u r e of the vegetation. On the other  t h e i r preference surroundings.  hand, new stems show l a r g e i n t e r s p e c i e s d i f f e r e n c e s i n  f o r f o r e s t c o m p o s i t i o n and s t r u c t u r e o f t h e i r  immediate  The h a b i t a t c o m p o s i t i o n arid s t r u c t u r e l e a d i n g t o the  m o r t a l i t y o f a stem o f one s p e c i e s may c o n s t i t u t e a good h a b i t a t f o r the  iv regeneration  of a stem of another s p e c i e s .  T h i s i s viewed as a mechanism  which g i v e s r i s e t o p l o t type s u c c e s s i o n , which i n t u r n leads to type s u c c e s s i o n .  The  l e v e l s of the i n d i v i d u a l , of the community, and  the geographic range d i s p l a y c o n s i s t e n t p o p u l a t i o n dynamics. appears to be l i g h t and  forest-  e x p l a i n e d by  Succession  simple mechanisms i n v o l v i n g c o m p e t i t i o n  space; i t i s not n e c e s s a r y  or a n t a g o n i s t i c mechanisms of s p e c i e s  of  for  to p o s t u l a t e more complex s y n e r g i s t i c interaction.  V  TABLE OF CONTENTS  THESIS ABSTRACT  '  ••  L i s t of Figures L i s t of Tables  i i .... . v i i i  .  -ix  AC KNOWLEDGEMENTS  x  GENERAL INTRODUCTION CHAPTER I  xi '  * i  ABSTRACT  \  2  RESUME*  •  3  INTRODUCTION  4  DATA SAMPLING  6  The d a t a base  6  Study a r e a  7  D e s c r i p t i o n of the data  7  1) T r e e parameters  14  2) P l o t parameters Assessment o f t h e d a t a  •  ..14  •-.  ....15  METHODS  . . .17  The a n a l y s i s o f s u c c e s s i o n  17  The Markov approach t o s u c c e s s i o n  18  The u n d e r l y i n g assumptions t o t h e Markov p r o c e s s  23  RESULTS AND DISCUSSION  24  The Markov s i m u l a t i o n  24  Dry D o u g l a s - f i r Subzone  ....26  Wet D o u g l a s - f i r Subzone  39  Dry Western Hemlock Subzone  43  Wet Western Hemlock Subzone  45  Fog Western Hemlock Subzone  46  CONCLUSION  ....  LITERATURE  CITED  •  . .47 50  vi  CHAPTER I I  •  ABSTRACT  ,.  RESUME  •  55  ..  INTRODUCTION  56  .  57  DATA AND METHODS  58  H e t e r o g e n e i t y w i t h i n subzones Definition RESULTS AND  o f the c l a s s i f i c a t i o n  • • • •.  ••  58  scheme  61  DISCUSSION  Dynamics o f f o r e s t  .63  stands  63  D o u g l a s - f i r Zone  .....63  Western Hemlock Zone  75  P l o t type c l a s s i f i c a t i o n  .......  76  A n a l y s i s o f b a s a l a r e a growth v a r i a t i o n Dry  54  D o u g l a s - f i r Subzone  83  .•  Major s p e c i e s  (Table 10)  Minor s p e c i e s  (Table 11)  ..85 ........  85  -  87  Wet D o u g l a s - f i r Subzone  ......89  Major s p e c i e s  (Table 12)  .....89  Minor s p e c i e s  (Table 13)  91  Dry Western Hemlock Subzone  94  Major s p e c i e s  (Table 14)  ........  Minor s p e c i e s  (Table 15)  . ...  94 ..96  Wet Western Hemlock Subzone  98  Major s p e c i e s  (Table 16)  98  Minor s p e c i e s  (Table 17)  ..102  Fog Western Hemlock Subzone Major s p e c i e s  (Table  Minor s p e c i e s  (Table 19)  S i t e index v a r i a t i o n  102  18)  ' . ...  ...102 105 .107  vii  CONCLUSION  ....  LITERATURE CITED  . . . 113  .. .  .  ..115  CHAPTER I I I  '  .. ABSTRACT  .  .  RESUME  ... . . .  . .... ...  •  INTRODUCTION  .116  .  . .. . . .  ,  •  . . .118  ••••••  • • -1-19  DESCRIPTION OF THE DATA  •  120  THE CHOICE OF AN APPROACH  ....121  L i t e r a t u r e review Methods  121 ...  ....  122  RESULTS AND DISCUSSION  127  R e g r e s s i o n models Mortality  ..134  indicators  137  trends  CONCLUSION  139 .  LITERATURE, CITEDCHAPTER IV:  .134  indicators  Regeneration Succession  127  and r e g e n e r a t i o n a n a l y s i s  Mortality  .117  • .  S y n t h e s i s and conclusion-  ' '  •  141 •  144 147  APPENDIX A  . . -152  APPENDIX B ..  ...153  APPENDIX C  .159  viii  LIST OF FIGURES  1. P l o t s o f Vancouver I s l a n d  .8  2. P l o t s o f t h e Queen C h a r l o t t e I s l a n d s  .10  3. D i s t r i b u t i o n o f major t r e e s p e c i e s 4. T r a n s i t i o n p r o b a b i l i t y m a t r i x  evaluation  5. Markovian s i m u l a t i o n o f s u c c e s s i o n 6. Mean s p e c i e s r e l a t i v e abundance 7. P_. m e n z i e s i i s i t e index d i s t r i b u t i o n 8. T. h e t e r o p h y l l a s i t e  index d i s t r i b u t i o n  9. I n d i c e s o f c o m p e t i t i o n  13 •  ....22 27 .64 ..108 ....110 .....124  ix  LIST OF TABLES  1. Subzone c l i m a t i c parameters  . ..  12  2. D i s t r i b u t i o n o f the sample p l o t s  16  3. I n i t i a l  25  stand-type frequencies  4. T h e o r e t i c a l subzone s t e a d y - s t a t e s  ............  .40  5. P l o t types o f the Dry D o u g l a s - f i r Subzone  77  6. P l o t types o f the Wet D o u g l a s - f i r Subzone  79  7. P l o t types o f the Dry Western Hemlock Subzone  ....80.  8. P l o t types o f the Wet Western Hemlock Subzone  ........81  9. P l o t types o f the Fog Western Hemlock Subzone  82  10. Anova o f major s p e c i e s , Dry D o u g l a s - f i r Subzone  86  11. Anova of minor s p e c i e s , Dry D o u g l a s - f i r  Subzone  ....88  12. Anova o f major s p e c i e s , Wet D o u g l a s - f i r  Subzone  .90  13. Anova o f minor s p e c i e s , Wet D o u g l a s - f i r  Subzone  ......92  14. Anova o f major s p e c i e s , Dry Western Hemlock Subzone  95  15. Anova o f minor s p e c i e s , Dry Western Hemlock Subzone  ....97  16. Anova o f major s p e c i e s , Wet Western Hemlock Subzone  .-...99  17. Anova o f minor s p e c i e s , Wet Western Hemlock Subzone  ....103  18. Anova o f major s p e c i e s , Fog Western Hemlock Subzone .......... 104 19. Anova o f minor s p e c i e s , Fog Western Hemlock Subzone  106  20. Mean subzone s i t e i n d i c e s  112  21.  '  R e g r e s s i o n models  22. Anova t a b l e on r e g r e s s i o n models  128 ....130  23. M o r t a l i t y i n d i c a t o r s ....................................  135  24. R e g e n e r a t i o n i n d i c a t o r s  138  ACKNOWLEDGEMENTS  I wish t o thank Fred  B u n n e l l , A l a n Chambers, Dave Handley,  George Hochbaum, Buzz H o l l i n g , Ed Packee, R a n d a l l Perterman, Don Reimer, Nick Sonntag, W i l l i a m Thompson, C a r l W a l t e r s , reviewing Don  and c r i t i s i z i n g my m a n u s c r i p t .  Reimer o f M a c M i l l a n  information.  I am s p e c i a l l y g r a t e f u l t o  Blbedel Limited, Forestry D i v i s i o n , f o r providing  the whole d a t a base and a l l kinds Packee p r o v i d e d  and Con Wehrhahn f o r  four years  o f encouragement and support.  of c r i t i c i s m  and was an endless  Ed  source o f  I acknowledge t h e N a t i o n a l Research C o u n c i l o f Canada f o r  a s c h o l a r s h i p and C a r l Walters f o r a r e s e a r c h a s s i s t a n t s h i p d u r i n g my d o c t o r a l program.  xi  GENERAL INTRODUCTION  Succession p l a n t ecology. repeatable  appears t o be a c e n t r a l concept i n b o t h animal and  I n i t s broadest  sense, s u c c e s s i o n can be d e f i n e d as a  sequence o f dominant s p e c i e s i n an ecosystem.  i s , however, p e r c e i v e d w i t h a d i f f e r e n t at which t h e ecosystem i s observed.  f l a v o r according  T h i s concept t o the s c a l e  On a v e r y s m a l l s c a l e , l a r g e  areas  of v e g e t a t i o n can appear t o be r a t h e r homogeneous, w h i l e on a l a r g e s c a l e the heterogeneity  o f the communities and the v a r i a b i l i t y among  i n d i v i d u a l s become obvious. The  problem i s then t o e v a l u a t e how p e r s p e c t i v e s about the f o r c e s  a c t i n g d u r i n g secondary s u c c e s s i o n change w i t h t h e l e v e l o f i n t e r p r e t a t i o n . The  c o a s t a l f o r e s t o f southwestern B r i t i s h Columbia i s l a r g e enough to  o f f e r observations hypothesis  from a v e r y s m a l l t o a v e r y l a r g e s c a l e .  o f t h i s study  i s that, although  The g e n e r a l  the perception of succession  might be q u i t e d i f f e r e n t a t the s c a l e o f the B i o g e o c l i m a t i c Subzone, at the s c a l e o f the f o r e s t s t a n d , and a t t h e s c a l e o f the i n d i v i d u a l t r e e , each l e v e l o f i n t e r p r e t a t i o n must be c o n s i s t e n t w i t h  the o t h e r s .  Furthermore, t h e r e must be some u n d e r l y i n g mechanism r e s p o n s i b l e f o r the p o p u l a t i o n dynamics observed a t each l e v e l . The  B i o g e o c l i m a t i c Subzone l e v e l i s s t u d i e d i n Chapter I , t h e  p l o t l e v e l , i n Chapter I I , and the i n d i v i d u a l t r e e l e v e l , i n Chapter III.  1  A n a l y s i s and modelling of i n t e r s p e c i e s competition during f o r e s t secondary succession.  Pierre Bellefleur  CHAPTER I  A Markov model of f o r e s t - t y p e succession a f t e r disturbance i n Coastal B r i t i s h Columbia.  2  ABSTRACT  S u c c e s s i o n models were b u i l t  f o r f i v e B i o g e o c l i m a t i c Subzones of  the c o a s t a l f o r e s t o f B r i t i s h Columbia Each p l o t was abilities  from a d a t a bank o f 730  plots.  c h a r a c t e r i z e d by a f o r e s t - t y p e every f i v e years and  o f moving from one type t o another  were c a l c u l a t e d .  over the next f i v e  prob-  years  The models t e s t e d the h y p o t h e s i s t h a t the f u t u r e  s t a t e o f the f o r e s t , g i v e n p a s t and p r e s e n t s t a t e s , i s not f i x e d , but i s determined  by a s e t o f t r a n s i t i o n p r o b a b i l i t i e s based  p r e s e n t s t a t e o f the  o n l y on the  forest.  P_. m e n z i e s i i s t a n d - t y p e s showed a v e r y slow decrease i n the Dry D o u g l a s - f i r Subzone t o the advantage o f T. p l i c a t a , t h i s being f a s t e r i n the wet succeeded  after  decrease  subzone where T. h e t e r o p h y l l a stand-types  100 y e a r s ; t h i s s u c c e s s i o n o c c u r r e d a f t e r 50 years i n  the Dry Western Hemlock Subzone.  In the wet  p a r t o f t h i s subzone, T.  h e t e r o p h y l l a stand-types always s t a y e d prominent  w i t h minor s u c c e s s i o n  p o s s i b l y o c c u r r i n g from P_. s i t c h e n s i s stand-types t o A. a m a b i l i s .  In  the Fog Subzone, J_. p l i c a t a s t a n d - t y p e s were more abundant soon a f t e r d i s t u r b a n c e , but T. h e t e r o p h y l l a stand-types would p r o g r e s s i v e l y  take  over. The models d i d not adequately r e p l i c a t e the o b s e r v a t i o n s and to produce  realistic  long-term p r e d i c t i o n s .  Transition  failed  probabilities  were not e n t i r e l y time-homogeneous and the models were too g e n e r a l i n r e l a t i o n t o the d i v e r s i t y o f communities, types of d i s t u r b a n c e , and patterns of invasion.  Using t h i s type o f d a t a , i t i s concluded  f o r e s t s u c c e s s i o n i s not a Markov p r o c e s s .  that  3 RESUME  On  a c o n s t r u i t des modeles de s u c c e s s i o n pour c i n q sous-zones  biogeoclimatiques  de  l a foret  c S t i e r e de Colombie B r i t a n n i q u e a p a r t i r  d'une banque de donnees d e 7 3 0 p l a c e t t e s . p l a c e t t e a ete determine a tous  Le type f o r e s t i e r de  l e s c i n q ans  et l e s p r o b a b i l i t e s de  t r a n s i t i o n d'un  type a un  ete c a l c u l e e s .  Les modeles ont t e s t e l'hypothese  f u t u r de  a u t r e durant  l a f o r e t , connaissant  les prochaines  c i n q annees ont  selon laquelle  ses e t a t s passe et p r e s e n t , n'est  f i g e , mais p l u t 6 t determine par un ensemble de p r o b a b i l i t e s de basees seulement sur l ' e t a t  chaque  a c t u e l de  l'etat pas  transition  l a forSt.  Le type f o r e s t i e r P_. m e n z i e s i i a diminue t r e s  lentement dans l a  sous-zone seche du s a p i n de Douglas au p r o f i t de J_. p l i c a t a e t p l u s  rapi-  dement dans l a sous-zone humide ou l e type J_. h e t e r o p h y l l a l u i succede apres  100  ans;  zone seche de  c e t t e meme s u c c e s s i o n se p r o d u i t egalement dans l a sousl a pruche de  l ' o u e s t apres  50 ans.  Dans l a p a r t i e humide  de c e t t e sous-zone, l e type f o r e s t i e r J_. h e t e r o p h y l l a e s t demeure proeminent t a n d i s qu'une s u c c e s s i o n mineure p o u v a i t  se p r o d u i r e du type  Dans l a bande brumeuse de  P_.  s i t c h e n s i s au type A.  amabilis.  l a zone, l e  type T. p l i c a t a e t a i t  l e p l u s abondant immediatement apres p e r t u r b a t i o n  mais l e type J_. h e t e r o p h y l l a p o u r r a i t l u i succeder. Les modeles n'ont pas  reproduit fidelement  les observations  n'ont pu p r o d u i r e de p r e d i c t i o n s r e a l i s t e s a long terme.  Les  l i t e s de t r a n s i t i o n ne f u r e n t pas rigoureusement constantes f u r e n t t r o p i m p r e c i s quant a l a v a r i e t e des t u r b a t i o n et d ' i n v a s i o n des  especes.  On  communautes, des  a c o n c l u que  r e s t i e r e n'est pas Markovienne, s e l o n l e s o b s e r v a t i o n s  et  probabi-  et l e s modeles types de  per-  l a succession foanalysees.  4 INTRODUCTION  There e x i s t s no p r e c i s e theory e c o l o g i c a l systems.  Yet v e r y  man-made d i s t u r b a n c e s  to p r e d i c t the response of d i s t u r b e d  l a r g e ecosystems s u b j e c t e d  are r o u t i n e l y e x p l o i t e d and  of t h e i r b i o t i c responses i s r e q u i r e d . Forest for  ( K r a j i n a 1969)  over a c e n t u r y  The  of B r i t i s h Columbia  and  a better  Raup (1967) p o i n t e d  (Canada) has  been e x p l o i t e d  the study  was  Cooper (1913) showed  preponderant soon a f t e r w i n d f a l l and  t o low g e r m i n a t i o n  performance.  r e c o n s t r u c t e d f o r e s t s u c c e s s i o n f o r 300 was  more important  succession. spruce  a key f a c t o r i n the g e n e r a t i o n species composition.  Henry and  Flaccus  of new  Swan (1974)  disturbance  changes than was  autogenic the  over hundreds of  (1973) found t h a t w i l d f i r e s were successions  and  i n the c o n t r o l of  (1959) s t u d i e d the r e v e g e t a t i o n and  s u c c e s s i o n of s p e c i e s on 29 l a n d s l i d e s i n the White Mountains of Hampshire and  showed the g r a d u a l  t r a n s i t o r y s p e c i e s by age  70.  was  and found t h a t  m o r t a l i t y i n stands  K i l g o r e (1973) and V i e r e c k  replacement of p i o n e e r  Recently  Horn (1976) has  the New  species  by  studied  the  e f f e c t o f d i f f e r e n t p a t t e r n s of d e v a s t a t i o n on s u c c e s s i o n , S l a t y e r Connell  how  t h i s s p e c i e s never  (1963) and H b l l i n g e t a l . (1975) showed t h a t  budworm can cause up t o 100%  hectares.  years  i n creating compositional  Morris  of  out t h a t most f o r e s t s have a c o n s t a n t h i s t o r y  then out-competed by B e t u l a p a p y r i f e r a Marsh., although became abundant due  understanding  f o r a time range c o v e r i n g the f o r e s t r o t a t i o n .  of f i r e s , d i s e a s e , i n s e c t p e s t s , and w i n d f a l l s . Abies balsamea ( L O M i l l ,  and  P a c i f i c C o a s t a l Mesothermal  r e c e n t l y c o l l a t e d d a t a permit  succession after disturbance  to n a t u r a l  (1976) have documented the p a t t e r n s o f c o l o n i z a t i o n a f t e r  and  5 p e r t u r b a t i o n , and Shugart effect  et_ al_.  (1973) have looked at the feedback  of d i s t u r b a n c e on p i o n e e r s p e c i e s . Man  Bartos  i s the major b i o t i c agent a f f e c t i n g the f o r e s t  (1973) has  shown how  fire  and  (Kimmins 1972).  c u t t i n g cause the aspen  (Populus  t r e m u l o i d e s Michx.) community to r e v e r t to e a r l y s u c c e s s i o n a l s t a g e s . Likens et_ a l . (1970) have made a d e t a i l e d study on the e f f e c t s of c u t t i n g and h e r b i c i d e s on s o i l n u t r i e n t contents  and  cycling.  clear-  They  showed t h a t c l e a r c u t t i n g can produce h i g h n u t r i e n t l o s s e s from  soils  b e f o r e the r a t e of n u t r i e n t u t i l i z a t i o n by e a r l y s u c c e s s i o n a l s p e c i e s reaches  the r a t e of s u p p l y .  (1973) s t u d i e d the impact  C o l e and G e s s e l  (1968) and G e s s e l et a l .  of c l e a r c u t t i n g and  f o r e s t p r o d u c t i v i t y and m i n e r a l c y c l i n g . i n the amount o f water i n t h e s o i l  even-age management on  They found  a 54 to 60%  after clearcutting.  There i s abundant  l i t e r a t u r e on o t h e r examples of human d i s t u r b a n c e t o the  forest.  E a r l y stages of s u c c e s s i o n i n c l u d i n g mosses, l i v e r w o r t s , and  s h o r t - l i v e d p e r e n n i a l s , shrubs  Mueller-Dombois  (1965),  and  increase  annuals  t r e e s e e d l i n g s were s t u d i e d by  Kellman (1969),  and Dyrness  (1973).  The  present  d a t a s e t d i d not p r o v i d e o b s e r v a t i o n s on u n d e r s t o r y v e g e t a t i o n and i t s i n c l u s i o n i n the models was  not p o s s i b l e .  v e g e t a t i o n s t r a t a , Kellman (1969) found  In  t h a t no p r e d i c t i o n c o u l d be  made as to f l o r i s t i c o r g a n i z a t i o n at d i f f e r e n t because of the h i g h l y s t o c h a s t i c p r o c e s s vegetation.  stages of s u c c e s s i o n  of propagule  For the purpose of p r e d i c t i n g  d i s p e r s a l i n minor  l a t e r stages of f o r e s t  c e s s i o n , i t appears t o be s a f e r to wait u n t i l hazard  h i s study c o v e r i n g a l l  a f t e r the a p p a r e n t l y hap-  s t a g e o f e a r l y c o m p e t i t i o n among minor v e g e t a t i o n and  saplings.  suc-  tree  6 The  purpose of t h i s paper i s to p r o v i d e  a synthesis  of the  s i o n dynamics of the c o a s t a l f o r e s t of southwestern B r i t i s h a f t e r disturbance, first  at the s c a l e of the B i o g e o c l i m a t i c  approach a s m a l l - s c a l e  the g e n e r a l horizon  b e h a v i o u r of t h i s  (the p e r i o d  perceive  succes-  Columbia  Subzone.  As  a n a l y s i s i s judged n e c e s s a r y to encompass l a r g e ecosystem  (1.3 x 10  of time over which m o d e l l i n g  5  km ).  The  2  i s applied)  c u t t i n g r o t a t i o n i s assumed to be  s i x t y to e i g h t y  Under these c o n d i t i o n s , an adequate model of s u c c e s s i o n s y n t h e t i c and study a r e a and  dynamic; g e n e r a l , due  should  be  to the s i z e and v a r i a b i l i t y  because d e t a i l s are u s e l e s s  at t h i s  time  required  the dynamics o f the system must be kept r a t h e r s h o r t , by  s i t y , s i n c e the  a  to  necesyears. general,  of  the  l e v e l of i n t e r p r e t a t i o n ;  s y n t h e t i c , because i n t e g r a t i o n over s e v e r a l l e v e l s of response i s necessary; dynamic, because growth p r o c e s s e s of a community g e n e r a t e changes i n environmental c o n d i t i o n s r e l y on an o r d e r l y flow  and  constant  because f o r e c a s t i n g t e c h n i q u e s  of events from one  time p e r i o d  to the  next.  DATA SAMPLING  The  d a t a base The  data f o r t h i s  study were c o l l e c t e d by M a c M i l l a n B l o e d e l  F o r e s t r y D i v i s i o n , on t h e i r T r e e Farms and B r i t i s h Columbia. R i v e r Company and  T r e e Farm L i c e n c e s  the B r i t i s h Columbia F o r e s t  p a r t of the Company's Permanent Sample P l o t and programs.  in coastal  Some of the o l d e s t p l o t s were e s t a b l i s h e d by by  They are  Service.  The  Limited,  Powell plots  are  Spacing Assessment P l o t  l o c a t e d mainly i n the Powell R i v e r r e g i o n , on a  few  7 i s l a n d s of the Johnstone S t r a i t , and  at many l o c a t i o n s on Vancouver  and  The  on the Queen C h a r l o t t e  Islands.  p l o t s are grouped i n c l u s t e r s o f  v a r i a b l e s i z e i n the d i f f e r e n t B i o g e o c l i m a t i c p o s i t i o n of the and  Study  Zones  c l u s t e r s on Vancouver I s l a n d and  on the Queen C h a r l o t t e  Islands  Island  (Packee 1974).  the adjacent  are shown ( F i g u r e s  1 and  The  mainland, 2).  area The  study a r e a  is classified  into four Biogeoclimatic  Zones:  Douglas-^fir, C o a s t a l Western Hemlock, S u b a l p i n e Mountain Hemlock, Alpine.  The  study p l o t s are r e s t r i c t e d to the f i r s t  two  Coastal and  zones, the  lower  e l e v a t i o n zones (^lOOOm.), each of which i s f u r t h e r d i v i d e d i n t o a dry and  a wet  subzone ( K r a j i n a 1965,  also recognizes  a Fog  e l e v a t i o n along  the west coast  Charlotte  1969;  Packee 1974,  1976).  Packee  Western Hemlock / S i t k a Spruce Subzone at of Vancouver . I s l a n d and on  I s l a n d s , w i t h i n the Western Hemlock Zone.  The  listed  i n T a b l e 1.  zone appears i n F i g u r e  D e s c r i p t i o n of the The  The  low  the Queen  main c l i m a t i c  parameters forming the b a s i s f o r c l a s s i f i c a t i o n of these f i v e are  (1974)  subzones  d i s t r i b u t i o n of major t r e e s p e c i e s  i n each  sub-  3.  data  F o r e s t r y D i v i s i o n of M a c M i l l a n B l o e d e l  L i m i t e d has  established  the Permanent Sample P l o t program as a complement to i t s i n v e n t o r y  system  to assess timber p r o d u c t i o n ,  cut,  and  f o r e s t r o t a t i o n , and  annual a l l o w a b l e  the Spacing Assessment P l o t program as a t o o l f o r experimenting w i t h  s t o c k i n g , t h i n n i n g , f e r t i l i z a t i o n , and angular or square, and  vary  from 0.04  planting. to 0.8  The  hectares  p l o t s are r e c t i n area.  They  grouped i n c l u s t e r s of 2 t o 10 p l o t s , i n s e v e r a l management b l o c k s  in  are  FIGUBE 1 L o c a t i o n o f t h e sample p l o t s c f V a n c o u v e r I s l a n d and t h e a d j a c e n t i s l a n d s and m a i n l a n d . The B i o geoclimatic Subzcnes after Fackea (1974) are indicated by the map t e x t u r e . The s i z e o f t h e c l u s t e r marker i n d i c a t e s t h e a p p r o x i m a t e number cf plots p e r c l u s t e r . The s u b z o n e s w i t h o u t any sample p l o t s have not been i n c l u d e d .  128°  127°  126°  125°  124°  123° W.  10  FIGURE 2 location o f the sample p l o t s on the Queen Charlotte Islands. The B i o g e o c l i m a t i c Subzcnas a f t e r Packee (personnal communication) are i n d i cated by the map texture. The s i z e of the cluster marker i n d i c a t e s the approximate number of p l o t s per c l u s t e r . The subzonas without any sample p l o t s have not been i n c l u d e d . The i n s e r t shews the r e l a t i v e p o s i t i o n of Vancouver I s l a n d and the Queen C h a r l o t t e I s l a n d s .  12 i  r  Coastal Douglas-fir  EICGECCLTMATIC ZONE  Coastal Western Hemlock -j  EIOGECCLIMATIC SUEZONE  Dry  Wet  Dry  102-152 9.3  165-280 6.2  PRECIPITATION (cm) Annual T o t a l Moist. D e f i c i t  1  66-102 13.a  1.5-4.8 12.7-26. 4 25-107 4-10  DRIEST MONTH WETTEST MONTH ANNUAL SNOWFALL SNOW IN % OF ANN. PREC. climate (KCPPEN)2  CSB  temperature (°C) MEAN ANNUAL ANNUAL EANGE (MEAN MONTHLY) MEAN JANUARY MEAN JULY NUMBER CF FROST-FREE DAYS r  I | Fog +I ! I 2 8 0 - 6 6 5 ! <1 65 2.7 | 0.4 Ret  3-16. 5 28-117 13-750 1-38  (+DRIEST CFB)  9-11 12-18  CFB  (+ MILDEST DFB)  5-9 9-21  1-4 16-19  - 4 TO 5 13-18  150-250  120-250  —+-  elevaticn (M) WINDWARD LEEWABD  -I  •+ \  0-150 0-450  C-900 450-1050  I | 0-150 L  1  TABLE 1 The main c l i m a t i c parameters which are used t c c l a s s i f y the B i o q e o c l i m a t i c Zones ( K r a j i n a 1 9 6 5 , 1969, Packee 1974). The Fog Western Hemlock / S i t k a Spruce sutzone i s a f t e r Packee (1974). Knowledge of the climax s p e c i e s i s a l s o needed to c o r r e c t l y a s s e s s the zone and the subzone. Mean Annual Moisture D e f i c i t with 2 0 0 mm o f s o i l water storaqe c a p a c i t y (Packee 1 9 7 6 ) . 2 K o p p e n ' s c l a s s i f i c a t i o n c a n be f o u n d i n S t r a h l e r <1 9 6 9 ) . 1  13  DRY DOUG LAS-FIR Subzone  WET  0-4 -  DOUGLAS-FIR Subzone  0 0-6 DRY WESTERN  HEMLOCK  0-4  Subzone  0 0-8 1 WET WESTERN  HEMLOCK  0 • 4 -j  Subzone  0 0-8 FOG WESTERN  HEMLOCK  0-4"  Subzone  ^0-  Th  Pm  Tp  Ps  Ag Aa  FIGURE 3 F r e q u e n c y d i s t r i b u t i o n of the s e v e n m o s t a b u n d a n t tree species i neach B i o g e o c l i m a t i c Subzone based on i m m a t u r e plots  plot data.  m a r k e d i n a dashed line t h a n 0.01. Tp:  The s u b s e t of u n t h i n n e d  o n l y w a s u s e d i n the c o m p u t a t i o n .  Species  h a v e a f r e q u e n c y of l e s s  T h : T. h e t e r o p h y l l a , Pm: P_. m e n z i e s i i ,  T. p l i c a t a , P s : P_. s i t c h e n s i s , Ag: A. g r a n d i s ,  Aa: A. a m a b i l i s , A r : A. r u b r a , Pc: P. c o n t o r t a .  Ar  Pc  14 each B i o g e o c l i m a t i c Subzone (except i n the A l p i n e and S u b a l p i n e The  t o t a l f o r e s t area managed by the Company i s approximately  hectares.  The program was  have y i e l d e d o b s e r v a t i o n s  s t a r t e d d u r i n g the 1930's, and  An  x  10  6  oldest plots  i n i t i a l p o o l of 730  r e g e n e r a t i o n p l o t s , w i t h over 70,000 t r e e s , was  Plots natural  available for this  study.  Tree parameters The  4 cm  f o l l o w i n g v a r i a b l e s are taken or measured f o r each t r e e at  i n DBH  (Diameter at Breast H e i g h t ,  number, s p e c i e s name, DBH,  t r e e and DBH  age  m from ground l e v e l ) :  and  0.25  the h e i g h t a r e measured on enough t r e e s to  and h e i g h t .  tree  Breast h e i g h t i s marked on  i s measured w i t h a diameter tape to the n e a r e s t  a d d i t i o n , the age the p l o t  1.4  least  stem and b u t t c h a r a c t e r i s t i c s , t r e e d e f e c t s ,  crown c l a s s , and p a t h o l o g i c a l f a c t o r s .  the cm.  In  assess  These t r e e s are chosen randomly i n each of  canopy s t r a t a : dominant, co-dominant, i n t e r m e d i a t e , and 2)  1.4  over a p e r i o d of more than 40 y e a r s .  are remeasured at f i v e - y e a r i n t e r v a l s .  1)  Zones).  the  suppressed.  P l o t parameters The  s l o p e angle, s l o p e a s p e c t , p o s i t i o n on s l o p e , and p l o t a r e a  determined.  The  f o l l o w i n g a r e c a l c u l a t e d from the t r e e d a t a : f o r e s t - t y p e ,  p l o t c o v e r , s i t e h e i g h t , s i t e age, (Mirb.) F r a n c o , 1  Zone i s a s s e s s e d ,  are  s i t e index  ( f o r Pseudotsuga m e n z i e s i i  and Tsuga h e t e r o p h y l l a (Raf.) S a r g . ) . based on the climax  s p e c i e s and p l o t  The  Biogeoclimatic  location.  For  each t r e e s p e c i e s , the number of stems and b a s a l area are c a l c u l a t e d on a per p l o t and per h e c t a r e b a s i s , f o r each DBH  E n g l i s h s p e c i e s names are g i v e n i n Appendix  .class.  A.  Between measurements  p o p u l a t i o n parameters such as ingrowth and  (realized regeneration), mortality,  t h i n n i n g are c a l c u l a t e d on a f i v e year b a s i s .  s i z e and b a s a l a r e a , and  the r a t e s of change are a l s o computed.  t r i b u t i o n o f sample p l o t s i s shown i n T a b l e  Assessment of t h e Since  large bodies  The  2.  of d a t a s i m i l a r t o t h i s one to c a r e f u l l y assess  mitations for ecological studies.  1.  The  data  a v a i l a b l e , i t i s important  assemblage  A l l changes i n t r e e  are i n c r e a s i n g l y  t h e i r merits  and  The main advantages of t h i s  lidata  are: a v a i l a b i l i t y of a d a t a s e t r i c h w i t h the e x p e r t i s e of  s e v e r a l thousand man-days i s i n v a l u a b l e to the e c o l o g i s t . It a l l o w s him lytical  to focus  on t h e o r e t i c a l i d e a s and  a s p e c t s r a t h e r than on time-consuming  on ana-  data  acquisition. 2.  The  l a r g e sample s i z e , the long range o f o b s e r v a t i o n s  t h e u n i f o r m i t y i n the f i e l d procedures assure of s t a t i s t i c a l r e l i a b i l i t y 3.  The  a high  g e o g r a p h i c a r e a sampled i s on a B i o g e o c l i m a t i c Region  1969) .  (Krajina  T h i s a l l o w s e l a b o r a t i o n of g e n e r a l i t i e s p e r t i n e n t  t o the whole r e g i o n , and  a l s o c o n c e n t r a t i o n on between-  zone v a r i a t i o n . The  level  f o r most parameters.  l e v e l - the P a c i f i c C o a s t a l Mesothermal F o r e s t  4.  and  data were o b t a i n e d  i n a form prepared v e r i f i e d and  from M a c M i l l a n  Bloedel  Limited  f o r computer a n a l y s i s , a l r e a d y  edited.  dis-  16 ""BIOGEOCLIMATIC  ZONE BIOGEOCLIMATIC SUBZONE % Total  Area  1  Coastal Douglas-fir  Coastal W e s t e r n Hemlock  !  Wet  Dry  , 9.0  5.5  PLOTS  Number o f P l o t s % cf Total  100  Sampling Period S a m p l i n g Eange (years)  1955-71 16  UNTHINNEB  of trees  Average number o f t r e e s per p l o t  Fog  Wet  +  13.0  t  40.0  —-i  2.2  TOTAL I ^  69.72  +  198 27  157 21  255 35  1946-73 27  1935-72 37  20 3  730 100  1932-72 1967-72 40 5  -+  PLOTS  Number o f P l o t s % cf Total Number  14  Dry  +  + All  .j  —I  71 11  167 26  142 22  248 38  19  4070  12964  10076  21774  1 154  57  77  70  87  3  647 100 500381  60  j  TABLE  2  D i s t r i b u t i o n o f the sample p l o t s per Biogeoclimatic Subzone. The c o m p l e t e s a m p l e c o n s i s t s o f 730 p l o t s , some o f which have been thinned f o r experimental purposes. Some analyses use t h e c o m p l e t e s a m p l e , and o t h e r s u s e t h e s u b s a m p l e c f 647 u n t h i n n e d p l o t s .  A f t e r Packee (1976). The M o u n t a i n Hemlock, Alpine, c o v e r t h e r e m a i n i n g 30.3?* a r e a . 1  2  and  Urbane  Biogeoclimatic  Zones  17 There are however some noteworthy l i m i t a t i o n s i n u s i n g  inventory-  type d a t a f o r e c o l o g i c a l a n a l y s i s : 1.  Some parameters such as h e i g h t and  age  are not s y s t e m a t i c a l l y  measured f o r each t r e e , but o n l y f o r a random subset plot.  As  a consequence, s p e c i e s w i t h a low frequency  sometimes not measured and t h i s case 2.  of  c o u l d suggest  Environmental  a significant  are  age v a r i a t i o n i n  a r t i f i c i a l p a t t e r n s of s u c c e s s i o n .  v a r i a b l e s ( m i c r o - c l i m a t e , pedology,  fauna,  e t c . ) are u s u a l l y l a c k i n g from i n v e n t o r y sampling, t h e i r absence makes i t i m p o s s i b l e to r e l a t e the s t r u c t u r e to environmental  and  forest  v a r i a t i o n between p l o t s .  k i n d of i n f o r m a t i o n i s , however, being s i v e l y i n t o the sampling  the  procedures  incorporated of M a c M i l l a n  (This  progresBloedel  Limited.) 3.  Understory  f l o r a i s not r e c o r d e d .  T h i s seems t o be the most  s e r i o u s l a c k i n the d a t a s e t s i n c e i t i s w i d e l y that understory  recognized  v e g e t a t i o n i s a b e t t e r i n d i c a t o r of  p o t e n t i a l than e a r l y s e r a i t r e e  site  composition.  METHODS  The  a n a l y s i s of Various  succession  s t u d i e s on s u c c e s s i o n i n r e l a t i o n to d i s t u r b a n c e were men-  tioned e a r l i e r .  S e v e r a l o t h e r s t u d i e s on f o r e s t s u c c e s s i o n are p u b l i s h e d  and  have reviewed t h e m a t t e r .  some authors  Harbo (1972), i n h i s t h e s i s ,  reviewed at l e n g t h t h e pre-1970 work on s u c c e s s i o n .  Shugart et_ a l . (1973)  18 used a s e t o f d i f f e r e n t i a l large f o r e s t areas.  equations  based on stand dynamics t o model  T h e i r approach takes  advantage o f t h e concept o f  r a t e o f change and g i v e s some i n s i g h t i n t o management. Reiners  (1975) a n a l y s e d  V i t o u s e k and  t h e n u t r i e n t r e t e n t i o n towards climax  l a t i o n t o t h e importance o f each n u t r i e n t t o p l a n t growth. veloped  and r e f i n e d t h e concept  B a z i l e v i t c h 1967; Odum 1969) studies. Nisbet  Whittaker  o f biomass accumulation  i n re-  They de-  (Rodin and  and they d i s c u s s e d o t h e r n u t r i e n t c y c l i n g  (1953, 1957, 1970), Odum (1969, 1971), and Drury and  (1971, 1973) have d i s c u s s e d s u c c e s s i o n a l p a t t e r n s q u i t e  throughly.  Four elements a r e e s s e n t i a l t o a complete d e f i n i t i o n o f s u c c e s s i o n . (1)  Succession  i s a p r o p e r t y - o f a system.  system c o n s i d e r e d Succession As Horn  None o f t h e elements o f t h e  s e p a r a t e l y can g i v e a v a l i d p i c t u r e o f s u c c e s s i o n . (2)  c o n s i s t s o f a change i n t h e n e t r a t e o f i n c r e a s e o f s p e c i e s .  (1974) p o i n t e d out, t h i s i s t h e c o n d i t i o n without  which one c o u l d  not p e r c e i v e s u c c e s s i o n .  (3) The c o n t r o l s over s u c c e s s i o n a r e e i t h e r  e x t r i n s i c t o t h e system:  f i r e , f l o o d i n g , c l i m a t i c changes e t c . , or i n -  trinsic:  competition, predation etc.  Finally,  convergence o f t h e system towards a r e l a t i v e l y c l i m a x , where s p e c i e s c o m p o s i t i o n s c a l e than i n e a r l i e r stages  (4) t h e r e i s a c e r t a i n steady  seems t o change over  s t a t e , the s o - c a l l e d a much longer time  of succession.  The Markov approach t o s u c c e s s i o n From t h e e s s e n t i a l c h a r a c t e r i s t i c s o f s u c c e s s i o n emerges t h e g e n e r a l concept  o f t r a n s i t i o n o f t h e f o r e s t from one " s t a t e " t o another.  Two  c o n d i t i o n s bound t h e c h o i c e o f s t a t e s : t h e i r number must be f i n i t e and they must d e s c r i b e t h e c o n d i t i o n s of t h e f o r e s t a t any time.  For the  19 study o f l a r g e r e g i o n s , Shugart e t a l . (1973) used a f i n i t e number o f c o v e r - s t a t e s or f o r e s t - t y p e s .  Waggoner and Stephens  (1970) and  Stephens  and Waggoner (1970) c l a s s i f i e d the f o r e s t i n t o f i v e types " a c c o r d i n g t o which o f the f i v e  c l a s s e s had the most stems on the t r a c t " .  Once the  f o r e s t - t y p e s are i d e n t i f i e d , r e p e a t e d o b s e r v a t i o n s at r e g u l a r time i n t e r v a l s on s e v e r a l sampling p l o t s show t r a n s i t i o n s from one type t o another d u r i n g the course of s u c c e s s i o n . MacArthur  (1958,  1961)  suggested t h a t s u c c e s s i o n c o u l d be  viewed  as a p l a n t - b y - p l a n t replacement p r o c e s s amenable t o the Markovian  approach.  T h i s approach views s t a t e t r a n s i t i o n s as a p r o b a b i l i s t i c phenomenon, where the f u t u r e o f any s i t e i s not f i x e d , but i s determined by a s e t o f p r o b a b i l i t i e s of moving t o another s t a t e over time. O l s o n and C r i s t o f o l i n i  (1966), and Horn (1974,  cession.  (1966),  1975a, 1975b, 1976)  a l l used t h i s method i n t h e i r s t u d i e s o f s u c c e s s i o n . and Noble and S l a t y e r  Anderson  have  R e c e n t l y Horn  (1976) have reviewed t h i s approach f o r p l a n t  (1975b) suc-  Mathematical treatments o f the Markov p r o c e s s are found i n  Bharucha-Reid  (1960), Kemeny and S n e l l  (1960), and H i l l i e r  and  Lieberman  (1967). As Waggoner and Stephens  (1970) p o i n t o u t , s e t s of e x t e n s i v e obser-  v a t i o n s i n time and space n e c e s s a r y f o r the v e r i f i c a t i o n of the t r a n s i t i o n p r o b a b i l i t i e s are r a r e . f o r the t a s k .  Due  However the d a t a f o r t h i s study seem s u i t a b l e  t o the absence  type c l a s s i f i c a t i o n was  of d a t a  on u n d e r s t o r y f l o r a , a f o r e s t -  used and each p l o t was  c h a r a c t e r i z e d on the  b a s i s o f the t r e e s p e c i e s w i t h the l a r g e s t number o f stems and, n a t i v e l y , w i t h the l a r g e s t b a s a l a r e a .  T h i s was  alter-  done f o r each measurement  20 on a f i v e - y e a r i n t e r v a l b a s i s and the stand-type  ( a stand of a g i v e n  f o r e s t - t y p e ) f r e q u e n c i e s were p l o t t e d a c r o s s stand age, f o r each B i o g e o c l i m a t i c Subzone i n terms o f stems and b a s a l a r e a . The  sampling  p e r i o d v a r i e s f o r each B i o g e o c l i m a t i c Subzone and  the maximum i s 40 y e a r s  (Table 2 ) .  S i n c e young and  o l d stands were  sampled, d a t a were p l o t t e d a c r o s s s t a n d age t o show v a r i a t i o n s i n s t a n d type frequency  as a f u n c t i o n of stand age r a t h e r than as a f u n c t i o n of  an a r b i t r a r y t i m e - s c a l e such as c a l e n d a r y e a r .  T h i s p e r m i t s the r e -  c o n s t r u c t i o n o f a l o n g - l i v e d ecosystem from o b s e r v a t i o n s of p l o t s different  age measured over the same p e r i o d of time.  However, t h i s approach has one  i m p l i c a t i o n that complicates  e x t r a c t i o n o f t r a n s i t i o n s from the d a t a . stands  25 and  stands, t h i s  C o n s i d e r two  70 years of age r e s p e c t i v e l y , observed  v a l s f o r 40 y e a r s .  youngest  of  I f a t r a n s i t i o n i s observed  i s recorded.  forest  at f i v e - y e a r  w i t h i n any of the  A d d i t i o n n a l l y the l a s t  s t a n d , taken at age 6 5 ,  adjacent  the  intertwo  o b s e r v a t i o n of the  can be merged w i t h the f i r s t  obser-  v a t i o n of the o l d e s t s t a n d , taken a t 70, .as an i m p l i e d t r a n s i t i o n . H i s t o r i c a l l y , most work on f o r e s t s u c c e s s i o n i n North America i s based on i m p l i e d t r a n s i t i o n s  (Drury and N i s b e t 1973) .  E c o l o g i s t s have  measured f o r e s t s o f d i f f e r e n t ages and have assumed t h a t the o l d e s t ones r e p r e s e n t e d the s t a t e towards which the young f o r e s t s were p r o g r e s s i n g . T h i s approach has been proven in short-lived  adequate i n o l d e r f o r e s t s of Europe  ecosystems.  When hundreds of stands of d i f f e r e n t t o t a l age  and  span i s i n c r e a s e d , but  ages are p o o l e d t o g e t h e r , the  i m p l i e d t r a n s i t i o n s cannot be  determined.  T h e r e f o r e , some t r a n s i t i o n s are bound t o be m i s s i n g from a t r a n s i t i o n  m a t r i x generated  from the observed  b i o l o g i c a l knowledge o f the system to  transitions  can then be used t o modify  use o f Bayes' r u l e final  However, p r i o r  and p u b l i s h e d work can c o n t r i b u t e  produce p r i o r e s t i m a t e s o f the t r a n s i t i o n s .  transitions  alone.  A subset o f the  the p r i o r e s t i m a t e s through  (see Thompson and V e r t i n s k y 1975)  t r a n s i t i o n p r o b a b i l i t y matrix.  and t o y i e l d  f i n a l t r a n s i t i o n matrix, i s simply:  rows and  - 0 total  the the  I f E i s the p r i o r e s t i m a t e s m a t r i x ,  and 0 the observed m a t r i x , the f u n c t i o n f such t h a t f [E,O]  (E t o t a l ( i )  observed  f [E,O]  = T,  the  = (E(i,j) - 0(i,j))  /  ( i ) ) f o r a l l i ' s and j ' s , where i and j r e p r e s e n t  columns r e s p e c t i v e l y .  The  same weight  t i o n s and t o the e s t i m a t e s by s e t t i n g  i s g i v e n t o the  observa-  each column t o t a l o f the e s t i m a t e s  equal t o the column t o t a l o f the o b s e r v a t i o n s .  Therefore, this  simply  makes the t r a n s i t i o n m a t r i c e s a l i t t l e more l i k e l y t o succeed i n m o d e l l i n g the d a t a . the t r a n s i t i o n s  F i g u r e 4 g i v e s an example o f the c a l c u l a t i o n f o r  i n stems i n the Dry Western Hemlock Subzone.  are documented i n Appendix  Matrices  B.  From the e c o l o g i c a l v i e w p o i n t , the meaning o f a t r a n s i t i o n p r o b a b i l i t y m a t r i x i s as f o l l o w s .  A l l observations of a given f o r e s t - t y p e ,  the P. m e n z i e s i i type f o r i n s t a n c e , r e p r e s e n t p l o t s which may  belong to  different  communities on the b a s i s of t h e i r u n d e r s t o r y v e g e t a t i o n , and  which may  have d i f f e r e n t o r i g i n s depending  Some o f these p l o t s may  on the source o f p e r t u r b a t i o n .  have the p o t e n t i a l t o remain the P_. m e n z i e s i i  t y p e , w h i l e o t h e r s might p r o g r e s s i v e l y become the T h u j a p l i c a t a Donn or  the J_. h e t e r o p h y l l a type f o r i n s t a n c e .  lities  are i m p l i c i t  T h e r e f o r e , a l l the p o s s i b i -  w i t h i n the t r a n s i t i o n m a t r i x and the observed  assumed p o s s i b i l i t i e s  and  are i n c l u d e d i n the m a t r i x i n terms o f p r o b a b i l i t i e s .  22  0 MATRIX Observations P. A. T. T. A-  menziesii 100 rubra 0 heterophylla 4 plicata 2 qrandis 0  TOTAL  106  E MATRIX Estimates  1 5 0 0 0  0 0 129 3 0  0 0 0 2 0  0 0 0 0 3  98 0 6 2 0  1 5 0 0 0  0 0 129 3 0  0 0 1 1 0  0 0 0 0 3  6  132  2  3  106  6  132  2  3  T MATRIX Transitions P. A. T. T. A.  menziesii rubra jheterophylla plicata grandis  TOTAL  533 0 48 19 0  167 83 3 0 0 0  0 0 977 23 0  0 0 0 0 200 0 800 0 0 1000  1000 1000 1000 1000 1000  FIGUBE 4 Transition probability matrix e v a l u a t i o n . The e s t i m a t e d matrix (E) i s m o d i f i e d by the observed matrix (0) t o produce the f i n a l t r a n s i t i o n probability matrix (T) u s i n g Bayes' r u l e . The t r a n s i t i o n s a r e expressed from the column s t a n d type at time t , to the row s t a n d - t y p e a t time t+1. P r o b a b i l i t i e s have been m u l t i p l i e d by 1,000 f o r p r e s e n t a t i o n i n the t a b l e . The column standtypes are the same as the row s t a n d - t y p e s .  23 T h i s makes the Markov p r o c e s s  v e r y p o w e r f u l and v e r y  Once the t r a n s i t i o n p r o b a b i l i t y m a t r i x the Markov p r o c e s s  allows  system, i f i t e x i s t s . a s t a t e of climax  general.  o f a system i s determined,  the computation of the s t e a d y - s t a t e  In other words, i f f o r e s t s u c c e s s i o n  where t h e r e  i s v i r t u a l l y no  The  Lieberman 1967)  sifying  assumptions t o the Markov  coastal f o r e s t succession  Markov p r o c e s s  (1)  The  c o u l d be  assumes,  state  (Hillier  and  : system can take o n l y a f i n i t e number of s t a t e s .  Clas-  each sample p l o t i n t o f o r e s t - t y p e s g i v e s a t h e o r e t i c a l maximum  (2)  The  t e s t e d by  Biogeoclimatic  Subzone.  i . e . they must be time-homogenous.  comparing the p r o b a b i l i t y m a t r i c e s  f i v e - y e a r p e r i o d f o r the time h o r i z o n The  A maximum of e i g h t  t r a n s i t i o n p r o b a b i l i t i e s of the system must be  f o r each time i n t e r v a l ,  (Billingsley  1961)  This  considered  i n each  An was  was  i s 8 f o r the Dry  Western Hemlock Subzone, and adapted c h i - s q u a r e  to  Biogeoclimatic  D o u g l a s - f i r Subzone, 18 f o r the Dry  Hemlock Subzone, 15 f o r the Wet Fog Western Hemlock Subzone.  the same  from f i v e - y e a r p e r i o d  number of f i v e - y e a r time p e r i o d s  Subzone, 16 f o r the Wet  matrices  This  t r e a t e d as a f i n i t e  i f i t shows the f o l l o w i n g f o u r p r o p e r t i e s  f o r e s t - t y p e s were found i n any  fir  reach  process  number o f 24 s t a t e s over the e n t i r e study a r e a .  Subzone.  i s to  t h a t the system i s t r u l y Markovian.  underlying The  the  change i n f o r e s t - t y p e s  over a long p e r i o d of t i m e , t h i s s t a t e can be p r e d i c t e d . of course,  of  DouglasWestern  5 for  the  s t a t i s t i c f o r Markov  used t o t e s t the s i m i l a r i t y o f  the  t r a n s i t i o n s f o r a l l the time p e r i o d s , f o r each subzone, i n terms of stems  24  and b a s a l a r e a .  The  expected  m a t r i x was  average of the complete sample.  Two  computed from a weighted  matrices  out of 16 i n the  D o u g l a s - f i r Subzone were s i g n i f i c a n t l y d i f f e r e n t expected of  matrix,  15 i n the Wet  subzones. although  said  Western Hemlock Subzone, and none i n the two  the d e p a r t u r e s The  remaining  i n 3 subzones out of  system must have the Markovian p r o p e r t y .  5,  s t a t e of t h e system.  A system i s  i f the c o n d i t i o n a l p r o b a b i l i t y  any f u t u r e s t a t e , g i v e n any p a s t and p r e s e n t  fits  of  s t a t e , depends o n l y on  T h i s i s an h y p o t h e s i s  I f a model based on the Markov p r o c e s s suggests  the  from homogeneity are s m a l l .  to have the Markovian p r o p e r t y  present  from  2 out o f 18 i n the Dry Western Hemlock Subzone, 1 out  So time-homogeneity i s not r i g o u r o u s  (3)  (p = 0.01)  Wet  the  t h a t w i l l be t e s t e d .  the o b s e r v a t i o n s w e l l , i t  t h a t the system might be Markovian; i f the model does not f i t  the o b s e r v a t i o n s , i t i s v e r y  l i k e l y t h a t the system i s simply not Mar-  kovian. (4)  A s e t of i n i t i a l p r o b a b i l i t i e s  probabilities  of the f o r e s t  t o be  at the o r i g i n o f the o b s e r v a t i o n s . can be taken initial  i n any  f o r a l l s t a t e s must e x i s t .  s t a t e i s t h e o r e t i c a l l y unknown  However the frequency  as r e p r e s e n t a t i v e of the p r o b a b i l i t i e s .  f r e q u e n c i e s of each stand-type  distribution  Table 3 g i v e s  f o r a l l the B i o g e o c l i m a t i c  DISCUSSION  The Markov s i m u l a t i o n S i m u l a t i o n runs were made from the t r a n s i t i o n m a t r i c e s  and  the  Sub-  zones .  RESULTS AND  The  the  25  DGUGLAS-FIK Dry Wet  STEMS Pseudotsuga m e n z i e s i i Ts.uga het er.c£hy 11a Thuja g l i c a t a A In us r u b r a Picea sitchensis Pinus contorta A.b.ies j g r a n d i s Abj.es a ma b i l l s TOTAL BASAL AREA Pseudotsuqa m e n z i e s i i Ts ucja h e t e r o p h y l l a Thuja p l i c a t a Alnus rubra Picea stichensis Pinus c c n t o r t a Abies ^ r a n d i s Abies a m a b i l i s TOTAL  WESTERN HEMLOCK Dry Wet Fog  92 0 0 4 0 4 0 0  78 8 9 5 0 0 0 0  65 26 0 9 0 0 0 0  0 67 8 4 21 0 0 0  0 33 67 0 0 0 0 0  100  1 CO  1 00  100  100  92 0 0 4 0 4 0 0  77 18 0 5 0 0 0 0  68 28 0 4 0 0 0 0  0 75 0 0 25 0 0 0  0 33 67 0 0 0 0 0  100  100  100  100  100  TABLE 3 Initial s t a n d - t y p e f r e q u e n c i e s f o r each Biogeoc l i m a t i c Subzone i n p e r c e n t a g e . Ihe s t a n d - t y p e is d e f i n e d as t h e s p e c i e s w i t h t h e a b s o l u t e maximum number o f stems or absolute maximum basal area.  26 r e s u l t s compared w i t h the o b s e r v a t i o n s . s i m u l a t i o n has  two  important f e a t u r e s .  The Markovian First,  n a t u r e o f the  the whole system  of stand-  types i s s i m u l a t e d s i m u l t a n e o u s l y and the r a t e o f change o f frequency i n each s t a n d - t y p e i s dependent on a l l o t h e r stand-type,' b e h a v i o u r . the f r e q u e n c i e s change a s y m p t o t i c a l l y t o a s t e a d y - s t a t e .  The  Secondly,  Markovian  p r o c e s s emphasises the i n t e r r e l a t i o n s h i p s between s p e c i e s r a t h e r than t h e i r frequency d i s t r i b u t i o n .  F i g u r e 5 (A t o J ) shows the s i m u l a t e d  frequency curves and the observed d a t a p o i n t s i n number o f stems and i n b a s a l a r e a a l t e r n a t i v e l y f o r each subzone. Smirnov s t a t i s t i c  (K-S t e s t ) was  o b s e r v a t i o n s and p r e d i c t i o n s . the d a t a w e l l each  used  A t w o - t a i l e d Kolmogorov-  t o t e s t the goodness o f f i t between  Most frequency curves were found t o f i t  (p = 0.05), w i t h some e x c e p t i o n s t h a t w i l l be d i s c u s s e d f o r  subzone.  Dry D o u g l a s - f i r Subzone Although  some o b s e r v a t i o n s f a l l  o f f the p r e d i c t e d curve of P_. men-  z i e s i i , none o f the curves are r e j e c t e d by the K-S of  P_. m e n z i e s i i stems dominating  test.  of  Alnus r u b r a Bong, and Pinus c o n t o r t a Dougl.  0.04  by age 75.  bilities  w h i l e P_. c o n t o r t a  by age  75.  are two major d i f f e r e n c e s i n t h i s p a t t e r n when the  are c a l c u l a t e d i n terms o f dominance by b a s a l area  r a t h e r than by number o f stems. not d e c r e a s e as f a s t :  0.92  75 ( F i g u r e  T. p l i c a t a does not dominate any stand at  e a r l y stages but i n c r e a s e s p r o g r e s s i v e l y t o 0.21 There  at age  stands  each have a p r o b a b i l i t y  i n young stands and A. r u b r a decreases t o 0.02  i n c r e a s e s t o 0.16  probability  the stand i s v e r y h i g h i n young  (0.92) and d e c l i n e s s l o w l y w i t h stand age t o r e a c h 0.61 5 A).  The  proba-  ( F i g u r e 5 B)  The p r o b a b i l i t y f o r P_. m e n z i e s i i does  at age 35 and  0.72  at age  75.  T h i s means  27  FIGURE 5 Markovian s i m u l a t i o n of s u c c e s s i o n . The results are presented a l t e r n a t i v e l y i n number of stems and i n b a s a l area f o r each subzone: A B C D E F G H I J  Cry Dry Wet "Wet Dry Dry Wet Wet Fcg Fcg  D c u g l a s - f i r Subzone (stems) D o u g l a s - f i r Subzone (basal . rea) D o u g l a s - f i r Subzone (stems) D o u g l a s - f i r Subzone (basal area) Western Hemlock Subzone (stems) Western Hemlock Subzone (basal area) Western Hemlock Subzone (ste ms) Western Hemlock Subzone (basal area) Western Hemlock Subzone (stems) Western Hemlock Subzone (basal area)  Each graph shows the observed data points with the f o l l o w i n g symbols, and the simulated curves with i d e n t i c a l l a r g e r symbols: menziesii •O heterophylla £licata A rubra .. X sitchensis f m a c r cjg h_y 11 u m X c enter t a 0 3randis (in the Wet D c u q l a s - f i r Subzone) ......+ A. a m a b i l i s (in the Wet Western Hemlock Subzone)  P. J» T. A. P. A. P. A.  I 29  CQ  CU  '9)  A3N3n03yj 3dAi-QNt)lS  STAND-TYPE FREQUENCY (STEMS)  n  0£  STAND-TYPE FREQUENCY (B. A.)  (SW31S) A0N3R03cU 3dAl-QNBlS  8) A3N3n03HJ 3 d A l - Q N d i S  STRND-TYPE FREQUENCY (STEMS)  o  35  I ^  1  1  1  1  -—I  1  1  1  CU '9) A3N3flD3cU 3dAl-QNUiS  1-  O  STAND-TYPE FREQUENCY (STEMS)  9£  CO '9) A0N3P03c!3 3dAi-QNUlS  38 t h a t t h e r e a r e 11% more P_. m e n z i e s i i s t a n d - t y p e s t h a t dominate i n terms of b a s a l a r e a t h a n i n terms o f stems a t age 75.  A t t h i s s t a n d age,  J_. p l i c a t a shows, t o t h e c o n t r a r y , a l o w e r s t a n d - t y p e f r e q u e n c y i n terms of b a s a l a r e a (0.09) t h a n i n number o f stems (0.21).  T h e r e f o r e , even  though J_. p l i c a t a i s i n c r e a s i n g i t s number o f stems due t o i t s  ability  t o r e g e n e r a t e i n t h e shade, P_. m e n z i e s i i d i s p l a y s a . b e t t e r b a s a l a r e a growth r a t e p e r stem.  A. r u b r a shows t h e same k i n d o f b e h a v i o u r i n b o t h  u n i t s o f measurement; i t s f r e q u e n c y o f dominance i s 0.04 a t age 35 and 0.02 at age 75.  Packee ( p e r s o n a l communication) b e l i e v e s t h a t A. r u b r a  can dominate more commonly on c e r t a i n s i t e s , and he argues t h a t l a c k o f s u f f i c i e n t s a m p l i n g on t h o s e s i t e s m i g h t • e x p l a i n t h e low o b s e r v e d f r e quencies.  No o t h e r t r e e s p e c i e s i n t h i s subzone have been found a b l e t o  dominate t h e s t a n d s e i t h e r i n number o f stems or b a s a l a r e a . K r a j i n a (1969) p o i n t s out t h a t P_. m e n z i e s i i i s shade t o l e r a n t i n t h i s subzone, e x c e p t on h y g r i c edatopes.  As t h e subzone i n g e n e r a l i s  x e r i c t o m e s i c , i t l e a v e s l i t t l e room f o r h y g r i c s p e c i e s t o dominate the w e t t e s t s i t e s , and t h i s i s t h e r o l e t h a t J_. p l i c a t a p l a y s .  Its  i n c r e a s e i n f r e q u e n c y w i t h s t a n d age might be a t t r i b u t e d t o i t s a b i l i t y t o r e p r o d u c e i n t h e shade on b o t h wet and d r y s i t e s .  Packee  (1976)  r e p o r t s t h a t T. p l i c a t a i s commonly found on r e l a t i v e l y d r y s i t e s ,  often  i n a s s o c i a t i o n w i t h A r b u t u s m e n z i e s i i P u r s h , but o n l y i n t h e Dry Douglasf i r Subzone. and  P. c o n t o r t a has a chance t o dominate on t h e most x e r i c  sites  K r a j i n a (1969) mentions t h a t i t would be o v e r t a k e n by shade t o l e r a n t  J_. p l i c a t a a t about 50 y e a r s i n terms o f stems.  Packee (1974) c l a s s i f i e s  P_. m e n z i e s i i and T. p l i c a t a as major c l i m a x s p e c i e s , A. r u b r a as a minor s e r a i s p e c i e s , and P. c o n t o r t a as a major s e r a i s p e c i e s .  The r e s u l t s o f  39 t h e model seem t o c o n t r a d i c t h i s c l a s s i f i c a t i o n of P_. m e n z i e s i i . A l though t h i s s p e c i e s i s dominant i n more than 90% o f the stands d i s t u r b a n c e , the p r o p o r t i o n o f P_. m e n z i e s i i s t a n d - t y p e s steadily thereafter.  after  decreases  P_. m e n z i e s i i s h o u l d be c l a s s i f i e d , on t h i s b a s i s ,  as a p i o n e e r . Long-term p r o j e c t i o n s based on the model show J_. p l i c a t a  and  P_.  c o n t o r t a t o become c l i m a x s p e c i e s (Table 4 ) .  This i s l i k e l y to cast  s e r i o u s doubts on the v a l i d i t y o f t h e model.  Indeed, i t i s argued t h a t  the d e c r e a s e o f P. m e n z i e s i i , and the c o n s e q u e n t i a l i n c r e a s e o f T. and P_. c o n t o r t a , i s an a r t e f a c t g e n e r a t e d  by a h i g h e r s p e c i e s  plicata  diversity  i n the o l d e s t p l o t s (above 55 y e a r s i n the D o u g l a s - f i r Zone) o r i g i n a t i n g m a i n l y from n a t u r a l d i s t u r b a n c e s : w i n d , f i r e , i n s e c t s , d i s e a s e p e r s o n a l communication) .  (Packee,  The younger p l o t s are n e a r l y p u r e P_. m e n z i e s i i •  T h e r e f o r e , the model i s based on b i a s e d d a t a and cannot be used f o r p r e d i c t i o n s o f the steady s t a t e .  I n the l i g h t of t h i s b i a s , Pakee's (1974)  c l a s s i f i c a t i o n mentioned e a r l i e r appears t o be e x a c t . mentions t h a t A b i e s g r a n d i s  Packee a l s o  (Dougl.) L i n d l . can be a major c l i m a x s p e c i e s  on s u i t a b l e s o i l s , but t h i s s p e c i e s d i d not dominate any o f the The  l a c k of A. g r a n d i s p l o t s i n t h i s d a t a s e t might be due t o the p a s t  sampling p r o c e d u r e s o f the Company, which d i d not f o c u s on t h i s (Packee, p e r s o n a l Wet  stands.  species  communication).  D o u g l a s - f i r Subzone Three s p e c i e s curves f a i l e d the K-S  P_. m e n z i e s i i , J_. p l i c a t a ,  t e s t of f i t i n t h i s  and A c e r macrophyllum P u r s h .  The  subzone:  latter did  not f i t w e l l because i t u s u a l l y does not c o n s t i t u t e a f o r e s t - t y p e i n t h i s area  ( w i t h two  e x c e p t i o n s i n the o r i g i n a l  d a t a ) , and was  not i n c l u d e d i n  40  EO0GLAS-FIR Wet Dry  EXPECTED TIME:  400 2 0 58 0 0 40 0 0  Pseudotsuqa m e n z i e s i i Tsucja h e t e r c r j h _ j r l l a Thuja, p l i c a t a Alnus rubra Picea sitchensis Pinus ccntcrta Abies g r a n d i s Abies a m a b i l i s  430 30 35 22 0 0 0 13 0  WESTERN HEMLOCK Foq Wet Dry  400  1000  100  0 90 10 0 0 0 0 0  0 33 0 0 0 0 0 67  0 100 0 0 0 0 0 0  TABLE 4 Expected time c f t h e o r e t i c a l s t e a d y - s t a t e and p r o b a b i l i t y d i s t r i b u t i o n o f s t a n d - t y p e s f o r each subzone a t time of steady-state i n terms o f stems.  t h e graphs.  Here F_. m e n z i e s i i dominates c l e a r l y and d e c r e a s e s s t e a d i l y  w i t h stand age from a p r o b a b i l i t y o f 0.78 years (Figure 5 C). 5 D).  at 20 y e a r s t o 0.34  at  A g a i n , the d e c r e a s e i s s m a l l e r i n b a s a l a r e a  T. h e t e r o p h y l l a has  a p r o b a b i l i t y of 0.08  o v e r t a k e s P_. m e n z i e s i i at age  at age  100 w i t h a l e v e l o f 0.38.  20, and  However P_.  (1969) s t r e s s e s t h a t P_. m e n z i e s i i a c h i e v e s a h i g h e r f o r e s t  Krajina  production  here t h a n i n the d r y subzone w h i l e J_. h e t e r o p h y l l a grows r a t h e r discrepancy  between the p r e d i c t i o n s and  z i e s i i , between age nation.  The  45 and  75  the o b s e r v a t i o n s  ( F i g u r e s 5 C and D), has  (Figure  slightly  m e n z i e s i i i s s t i l l w e l l ahead of T. h e t e r o p h y l l a i n b a s a l a r e a .  The  100  poorly.  f o r P_. men-  a twofold  o l d e s t p l o t s were f i r s t measured i n the 1930's and  explawere  l o c a t e d as a f u n c t i o n of r o a d a c c e s s i b i l i t y , i . e . i n v a l l e y bottoms, where higher'moisture observations  c o n t e n t f a v o r e d J_. p l i c a t a o v e r P_. m e n z i e s i i .  Thus t h e  show an abrupt d e c l i n e f o r F_. m e n z i e s i i a f t e r about age  T h i s i s compounded by the b i a s mentioned e a r l i e r whereby the  70.  higher  s p e c i e s d i v e r s i t y o f the o l d e s t p l o t s produces an a r t i f i c i a l d e c r e a s e of P_. m e n z i e s i i at o l d e r ages.  The  Markov model r e f l e c t s t h i s d e c r e a s e by  c o n v e r g i n g a s y m p t o t i c a l l y towards a s t e a d y - s t a t e , s t a r t i n g from a h i g h f r e q u e n c y at e a r l y s t a n d age.  T h i s r e s u l t s i n a smooth and  c o r r e s p o n d i n g c l o s e l y t o the o b s e r v a t i o n s but d e p a r t i n g  g r e a t l y i n the m i d d l e  J_. p l i c a t a i n c r e a s e s  and  late  stages,  stages.  i t s dominance i n stems w i t h s t a n d age  at a f a s t e r r a t e i n b a s a l a r e a . bility  i n the e a r l y and  steady d e c l i n e  and  even  This suggests a b e t t e r moisture a v a i l a -  a h i g h e r s o i l n u t r i e n t c o n t e n t t h a n i n the dry subzone,  a b e t t e r u p t a k e by J_. p l i c a t a t h a n by J_. h e t e r o p h y l l a .  According  and to  K r a j i n a (1969), J_. p l i c a t a needs r i c h e r s o i l s t h a n J_. h e t e r o p h y l l a , and the o l i g o t r o p h i e edatopes r e q u i r e d f o r J_. h e t e r o p h y l l a a r e v e r y r a r e i n t h i s subzone.  Packee (1976) a t t r i b u t e s t h e lower f r e q u e n c y o f T.  to moisture d e f i c i t .  plicata  The s i m u l a t i o n f a i l e d t o r e p l i c a t e t h e t h r e e peaks  observed at age 80, 85, and 90 -on t h e graph i n stems f o r T. p l i c a t a .  It  i s noteworthy t h a t P i c e a s i t c h e n s i s (Bong.) C a r r . never appears t o domin a t e i n stems i n any s t a n d , y e t i t s b a s a l a r e a dominance i n c r e a s e s d i l y w i t h t i m e , s e e m i n g l y t a k i n g advantage o f t h e m o i s t u r e .  stea-  The absence  of dominance i n t h e stem model agrees w i t h K r a j i n a ' s (1969) remark t h a t P_. s i t c h e n s i s i s v e r y r a r e i n t h i s subzone.  I t s presence i n the basal  a r e a model agrees on t h e o t h e r hand w i t h P h e l p s  1  (1973) c o n t e n t i o n  that  P_. s i t c h e n s i s may dominate on s i t e s where t h e s o i l s a r e w e l l d r a i n e d , f a i r l y r i c h i n n u t r i e n t s , and c o n t i n u o u s l y m o i s t .  As f a r as number o f  stems goes, Packee (1974) does n o t m e n t i o n P_. s i t c h e n s i s e i t h e r as a s e r a i or as a c l i m a x s p e c i e s .  A. g r a n d i s  i n c r e a s e s i t s f r e q u e n c y o f stem do-  minance from n i l at age 20 t o 0.08 by age 100, but has no chance t o dominate i n b a s a l a r e a i n t h i s a r e a , w i t h i n t h e s t u d i e d t i m e h o r i z o n . K r a j i n a (1969) showed t h a t e u t r o p h i c c o n d i t i o n s are n e c e s s a r y f o r A. g r a n dis  t o a t t a i n a good g r o w t h , w h i l e Packee (1976) argues t h a t s o i l m o i s t u r e  i s a more i m p o r t a n t  factor.  As i n t h e d r y subzone, A. r u b r a may  dominate  i n few young s t a n d s , but not i n o l d e r ones. Packee's (1974) c l a s s i f i c a t i o n f o r t h i s subzone i s : P_. m e n z i e s i i and J_. p l i c a t a a r e major c l i m a x s p e c i e s , A. g r a n d i s  i s an e d a p h i c major  c l i m a x s p e c i e s , J_. h e t e r o p h y l l a i s a m i n o r c l i m a x s p e c i e s , and A. i s a major s e r a i s p e c i e s .  rubra  The r e s u l t s agree q u a l i t a t i v e l y w i t h t h a t ,  43 w i t h t h e e x c e p t i o n o f J_. h e t e r o p h y l l a which tends t o become a major c l i m a x s p e c i e s on m o i s t s i t e s o f o l d e r s t a n d s . a r e a mid-way between t h e Wet  Kellman  (1969), working i n an  D o u g l a s - f i r Subzone and t h e Dry Western  Hemlock Subzone, found s p e c i e s f r e q u e n c y s i m i l a r t o t h e s e at age 13, and 100, w i t h an expected T. p l i c a t a - T. h e t e r o p h y l l a c l i m a x .  42,  However,  due t o t h e b i a s i n the d a t a , i t i s l i k e l y t h a t P_. m e n z i e s i i does not d e c r e a s e as much as shown h e r e , and c o n s e q u e n t l y J_. p l i c a t a and J_. h e t e rophylla  would b o t h have a lower f r e q u e n c y at h i g h e r ages; t h i s makes  t h e use o f the model f o r e x t r a p o l a t i o n u n s a f e .  The t h e o r e t i c a l s t e a d y -  s t a t e i n stems would be reached i n t h i s subzone a t about 430 y e a r s o f age (see T a b l e 4 ) , i f t h e f o r e s t were t r u l y  Markovian.  Dry Western Hemlock Subzone No curve was r e j e c t e d by t h e K-S  t e s t i n t h i s subzone, a l t h o u g h the  curves f o r P_. m e n z i e s i i and J_. h e t e r o p h y l l a do not v i s u a l l y seem t o f i t t h e o b s e r v a t i o n s : t h e t e s t i s not v e r y r o b u s t . from a h i g h f r e q u e n c y rophylla phylla  There i s a r e m a r k a b l e  shift  (0.66) o f P_. m e n z i e s i i and low f r e q u e n c y of J_. h e t e -  (0.26) at age 20 t o 0.22 a t age 10 ( F i g u r e 5 E ) .  f o r P_. m e n z i e s i i and 0.68  f o r T. h e t e r o -  This s h i f t a l s o occurs i n b a s a l area, a l -  though much more s l o w l y ( F i g u r e 5 F ) .  D i s c r e p a n c i e s between o b s e r v a t i o n s  and p r e d i c t i o n s o f f r e q u e n c i e s of T. h e t e r o p h y l l a and P_. m e n z i e s i i are l i k e l y caused by an o v e r s a m p l i n g i n t h e v a l l e y bottoms, 30 and 40 y e a r s ago, because o f b e t t e r r o a d a c c e s s i b i l i t y  (Packee, p e r s o n a l  V a l l e y m o i s t u r e overemphasized  o f T. h e t e r o p h y l l a p l o t s over  P_. m e n z i e s i i p l o t s .  S i n c e p l o t s were not sampled b e f o r e 20 y e a r s o f  T. h e t e r o p h y l l a p l o t s now observations.  frequency  communication).  age  50 y e a r s or o l d e r a r e o v e r r e p r e s e n t e d i n t h e  T h i s might s l i g h t l y exaggerate t h e upward t r e n d of  44 T_. h e t e r o p h y l l a i n the o l d e r ages, a l t h o u g h  t h e r e i s no doubt t h a t  h e t e r o p h y l l a i s t a k i n g o v e r P_. m e n z i e s i i i n terms of stems. A. r u b r a may  T.  Again  dominate young stands o n l y , and J_. p l i c a t a more f r e q u e n t l y  dominates o l d e r s t a n d s , w i t h a maximum p r o b a b i l i t y of 0.10.  Here  P_. m e n z i e s i i can be a major c l i m a x s p e c i e s , but e d a p h i c a l l y c o n t r o l l e d (Packee 1974), or e l s e a major s e r a i s p e c i e s ; J_. p l i c a t a i s a major c l i m a x s p e c i e s , and A. r u b r a i s a g a i n a major s e r a i  species.  Graphs show J_. h e t e r o p h y l l a t o become a major c l i m a x s p e c i e s , t h i s agrees w i t h Packee's c o n t e n t i o n , a l t h o u g h i n f o r m a t i o n concerning  r e s u l t s g i v e more  t h e d e f i n i t e s u c c e s s i o n t o J_. h e t e r o p h y l l a .  i s a threefold explanation for this s h i f t . sii  present  and  i s e d a p h i c a l l y c o n t r o l l e d and  (1)  The  f a c t t h a t P_. menzie-  i s c o m p e t i t i v e l y s u p e r i o r on  s i t e s f a v o r s i t s appearance j u s t a f t e r d i s t u r b a n c e .  (2)  The  xeric seedlings  of J_. h e t e r o p h y l l a are s e n s i t i v e t o heat and t h e i r e s t a b l i s h m e n t b e t t e r i n the shade of P_. m e n z i e s i i . to continue regenerating  There  succeeds  T h e r e a f t e r J_. h e t e r o p h y l l a i s a b l e  i n the shade.  (3)  U n l e s s t h e r e are  frequent  openings i n the canopy, the s e e d l i n g s u r v i v a l o f P_. m e n z i e s i i i s threatened.  K r a j i n a (1969) d e s c r i b e s P. m e n z i e s i i as a d e f i n i t e  s p e c i e s i n the subzone, and T. h e t e r o p h y l l a as a c l i m a t i c c l i m a x There were two  i s o l a t e d observations  pioneer species.  of A. g r a n d i s t h a t were not p o s s i b l e  t o s i m u l a t e and were d e l e t e d from t h e g r a p h s .  I t i s expected t h a t  the  M a r k o v i a n s t e a d y - s t a t e w i l l not appear b e f o r e 400 y e a r s , w i t h p r o b a b i l i t y d i s t r i b u t i o n of 0.90 Table 4).  f o r T. h e t e r o p h y l l a and  0.10  f o r T. p l i c a t a  (see  For the same r e a s o n s as above, l o n g term e x t r a p o l a t i o n s  c e r t a i n l y unsafe.  are  45 West Western Hemlock Subzone A l l c u r v e s i n t h i s subzone f i t t h e o b s e r v a t i o n s a c c o r d i n g t o t h e K-S t e s t .  T h i s subzone e x h i b i t s v e r y s l o w changes and no  significant  d i f f e r e n c e s between t h e e v a l u a t i o n s i n number o f stems and b a s a l a r e a ( F i g u r e 5 G and H) .  The dominance o f J_. h e t e r o p h y l l a i s p r a c t i c a l l y  c o n s t a n t w i t h i n t h e t i m e h o r i z o n at a f r e q u e n c y o f about 0.7 w h i l e Abies amabilis  (Dougl.) Forbes succeeds t o an e a r l y dominance o f  P. s i t c h e n s i s i n about 0.20 o f t h e s t a n d s . frequently  J_. p l i c a t a may dominate i n -  (0.08) i n e a r l y ages, but i s soon succeeded by A. a m a b i l i s .  No s t a n d dominated by P_. m e n z i e s i i was found h e r e and K r a j i n a  (1969)  p o i n t s out t h a t P_. m e n z i e s i i i s i n d e e d s t r o n g l y outcompeted by T. h e t e r o p h y l l a , J_. p l i c a t a , and A. a m a b i l i s .  He a l s o s t r e s s e s t h a t t h e c l i m a x  J_. h e t e r o p h y l l a has i t s b e s t p r o d u c t i o n h e r e .  The f r e q u e n c y o f s t a n d s  dominated by A. a m a b i l i s i s v e r y low i n younger s t a n d s .  Krajina  s t a t e s t h a t i t i s shade r e q u i r i n g i n mesic and d r i e r edatopes.  (1969) Macbean  (1941, i n Packee 1976) p o i n t s out t h a t i t s r e g e n e r a t i o n i s v e r y poor i n stands f o l l o w i n g c l e a r c u t t i n g , which i s the case i n t h e younger p l o t s . P_. s i t c h e n s i s might be outcompeted by A. a m a b i l i s s i n c e t h e former i s shade i n t o l e r a n t i n dense s t a n d s ( K r a j i n a 1969) , a l t h o u g h i t w i l l on f l u v i a l  persist  bottomlands where i t s growth i s b e s t (Packee 1976).  Packee (1974) a s s i g n s s p e c i e s as f o l l o w s : T. h e t e r o p h y l l a , A. amab i l i s , and J_. p l i c a t a are major c l i m a x s p e c i e s , A. r u b r a i s a major s e r a i s p e c i e s , and P_. s i t c h e n s i s an e d a p h i c minor s e r a i s p e c i e s .  Since the  changes i n f r e q u e n c y d i s t r i b u t i o n a r e so s l o w , i t would t h e o r e t i c a l l y t a k e a v e r y l o n g t i m e (about 1000 y e a r s , see T a b l e 4) t o r e a c h a s t e a d y - s t a t e .  46 Fog Western Hemlock Subzone J_. p l i c a t a and J_. h e t e r o p h y l l a s h a r e the dominance of the young stands w i t h a p r o b a b i l i t y of 0.67 stems and a l s o i n b a s a l a r e a  and 0.33  r e s p e c t i v e l y i n number o f  ( F i g u r e 5 I and J ) . Very soon J_. h e t e r o -  p h y l l a succeeds i n a l l the s t a n d s , and dominates everywhere. subzone has  the s m a l l e s t number of p l o t s (see T a b l e 2) and  p e r i o d of o b s e r v a t i o n s , and t h e d a t a do situation.  But  the  this  shortest  not r e p r e s e n t w e l l the  exact  Packee (1974) a s s i g n s T. p l i c a t a and J_. h e t e r o p h y l l a  as  major c l i m a x s p e c i e s ; the r e s u l t s agree w i t h h i s c l a s s i f i c a t i o n of h e t e r o p h y l l a , but  show J_. p l i c a t a t o be a p i o n e e r .  He a l s o a s s i g n s  T. A.  a m a b i l i s as a major c l i m a x s p e c i e s , which was  never observed i n the  stands of the study  a l s o c l a s s i f i e s P_. s i t c h e n s i s  a r e a i n t h i s subzone.  He  few  as a major s e r a i s p e c i e s and P h e l p s (1973) r e p o r t s t h a t P_. s i t c h e n s i s occurs more f r e q u e n t l y i n m i x t u r e  than i n pure s t a n d s , and t h a t the asso-  c i a t e d s p e c i e s u s u a l l y assume dominance, which the r e s u l t s seem t o confirm. I t i s o b v i o u s t h a t t h e r e are too few p l o t s i n t h i s subzone. (1969) s t a t e s t h a t P_. s i t c h e n s i s has the Wet  Krajina  i t s b e s t growth along the ocean i n  C o a s t a l Western Hemlock Subzone, which c o r r e s p o n d s t o Packee's  (1974) Fog Western Hemlock / S i t k a Spruce Subzone. by P h e l p s  (1973) and Packee (1976).  The  types i s , t h e r e f o r e , very s u r p r i s i n g .  On  This i s also supported  absence of P_. s i t c h e n s i s s t a n d the o t h e r hand, Packee (1976)  r e p o r t s t h a t t h i s s p e c i e s i s u s u a l l y a s s o c i a t e d w i t h J_. h e t e r o p h y l l a which o f t e n dominates the s t a n d .  Hence the h i g h f r e q u e n c y of J_. h e t e r o p h y l l a  s t a n d - t y p e s would r e f l e c t the p r e s e n c e o f P_. s i t c h e n s i s . The  d a t a and the model show T. p l i c a t a s t r i c t l y as a p i o n e e r  Packee (1974, 1976)  s t a t e s t h a t i t i s d e f i n i t e l y a major c l i m a x  and  species.  47 There are too few p l o t s i n the d a t a s e t t o make a b e t t e r assessment o f the s i t u a t i o n and  the e x t r a p o l a t i o n t o an e x c l u s i v e J_. h e t e r o p h y l l a  climax i s u n l i k e l y .  CONCLUSION  Forest  succession The  g e n e r a l t r e n d s of the s u c c e s s i o n  i n each subzone are c l e a r  w i t h i n the p e r i o d of o b s e r v a t i o n s , a l t h o u g h  the r a t e s o f change are  exaggerated by a c e r t a i n b i a s i n the d a t a s e t .  Over the whole study  area,  o n l y P_. m e n z i e s i i shows a l a r g e d i f f e r e n c e between i t s abundance i n stems and  i n b a s a l area.  I t s s t a n d - t y p e f r e q u e n c y i s always h i g h e r i n terms of  b a s a l a r e a t h a n i n terms of stems.  A. r u b r a always appears as a  pioneer  which may  of the stands i n a l l but the  Fog  dominate up t o 10 p e r c e n t  Western Hemlock Subzone, and plicata zone, and  i s always p r o g r e s s i v e l y outcompeted.  behaves l i k e a p i o n e e r  s p e c i e s i n t h e Wet  Western Hemlock  i s s l o w l y succeeded by A. a m a b i l i s and J_. h e t e r o p h y l l a .  J_. SubThe  d a t a show the same b e h a v i o u r i n the Fog Western Hemlock Subzone, but i n t h i s case the b e h a v i o u r i s an a r t e f a c t s i n c e T. p l i c a t a i s c l i m a x i n t h i s region.  I n o t h e r s u b z o n e s , the f r e q u e n c y o f J_. p l i c a t a s t a n d - t y p e s i n -  creases w i t h s t a n d  age.  I n the Dry D o u g l a s - f i r Subzone, the slow d e c r e a s e o f P_. m e n z i e s i i from a h i g h i n i t i a l f r e q u e n c y , and the e q u i v a l e n t i n c r e a s e of T_. p l i c a t a and P_. c o n t o r t a are i n f a c t much s m a l l e r i n terms of b a s a l a r e a . z i e s i i behaves l i k e an e f f i c i e n t p i o n e e r over the r o t a t i o n p e r i o d .  and m a i n t a i n s  P_. men-  i t s supremacy w e l l  K r a j i n a (1969) notes t h a t P_. m e n z i e s i i i s shade  48 t o l e r a n t i n t h e d r i e r c l i m a t e s , which might e x p l a i n t h e low f r e q u e n c y o f T_. p l i c a t a and P_. c o n t o r t a s t a n d - t y p e s . on t h e o t h e r hand, P_. m e n z i e s i i appears p h y l l a overtakes i t r a p i d l y .  In t h e Wet  D o u g l a s - f i r Subzone  a l s o as a p i o n e e r , but T. h e t e r o -  A large p r o p o r t i o n of the h a b i t a t s of t h i s  subzone are m o i s t and P_. m e n z i e s i i i s s h a d e - i n t o l e r a n t on t h e s e  edatopes.  Yet i t s b a s a l a r e a i s the h i g h e s t o f a l l s p e c i e s throughout t h e f o r e s t rotation.  P_. s i t c h e n s i s and J_. p l i c a t a show a b a s a l a r e a p r o g r e s s i v e l y  l a r g e r than t h e b a s a l a r e a o f T. h e t e r o p h y l l a d e s p i t e t h e i r  lower  number o f stems. P. m e n z i e s i i a l s o o c c u r s a b u n d a n t l y a t the e a r l y stages o f s u c c e s s i o n i n t h e Dry Western Hemlock Subzone but t h e number o f stems o f J_. h e t e r o p h y l l a predominates  by age 55.  Here a g a i n t h e decrease i n b a s a l a r e a o f  P_. m e n z i e s i i f o l l o w s i t s d e c r e a s e i n stems a t a much s l o w e r pace and i t s b a s a l a r e a m a i n t a i n s predominance over J_. h e t e r o p h y l l a . J_. p l i c a t a i n c r e a s e s i t s f r e q u e n c y up t o n e a r l y t e n p e r c e n t o f t h e stands by age  110.  In the Wet Western Hemlock Subzone, P_. m e n z i e s i i i s never seen t o c o n s t i tute a stand-type.  The t r e n d s observed f o r a l l s p e c i e s i n t h i s subzone  a r e s i m i l a r i n terms o f stems and b a s a l a r e a .  J_. h e t e r o p h y l l a dominates  over t h e r o t a t i o n w i t h a c o n s t a n t f r e q u e n c y of about 70 p e r c e n t .  The  P. s i t c h e n s i s s t a n d - t y p e has a h i g h e r f r e q u e n c y a t e a r l y ages, and A. bilis  i s more f r e q u e n t a f t e r 40 y e a r s .  In t h e Fog Western Hemlock  zone; t h e T. p l i c a t a s t a n d - t y p e predominates  amaSub-  a t e a r l y s t a g e s and i s l a r g e -  l y o v e r t a k e n by J_. h e t e r o p h y l l a a f t e r 35 y e a r s of age; t h i s i s an and J_. p l i c a t a s h o u l d remain up t o t h e c l i m a x s t a g e .  artifact  49 The Markov model The Markov model i s n o t s a t i s f a c t o r y f o r any subzone except t h e Wet Western Hemlock Subzone, w h i c h i s t h e one where t h e fewest occur.  changes  The model f a i l s t o f i t t h e o b s e r v a t i o n s and does not produce  realistic predictions.  I t shows what would happen i f t h e f o r e s t were  M a r k o v i a n and i t s long-term p r e d i c t i o n s a r e s u f f i c i e n t l y u n l i k e l y t o suggest, f o r t h e f o l l o w i n g r e a s o n s , t h a t f o r e s t s u c c e s s i o n i s n o t Markovian:  (1) t h e t r a n s i t i o n p r o b a b i l i t i e s were n o t found t o be en-  t i r e l y time-homogenous.  (2) The model i s much t o o g e n e r a l as f a r as  d i v e r s i t y o f communities and o r i g i n s o f p e r t u r b a t i o n a r e concerned. d i f f e r e n t model would be n e c e s s a r y type o f community,  f o r each k i n d o f d i s t u r b a n c e , each  and each k i n d o f s i t e .  allow species invasion.  A  (3) The model does n o t  T h i s c o u l d be r e c t i f i e d by making i t a m u l t i -  s t e p model w i t h as many t r a n s i t i o n p r o b a b i l i t y m a t r i c e s as l i f e - h i s t o r y strategies  i d e n t i f i e d w i t h i n the l i f e of the f o r e s t .  (4) Even i f  s u c c e s s i o n were M a r k o v i a n over t h e p e r i o d o f o b s e r v a t i o n s , t h e t r a n s i t i o n p r o b a b i l i t i e s are u n l i k e l y t o stay constant a f t e r f o r e s t m a t u r i t y .  Noble  and S l a t y e r (1976) have p o i n t e d but t h a t time homogeneity o f t r a n s i t i o n p r o b a b i l i t i e s i s c o u n t e r - i n t u i t i v e , a t l e a s t over long p e r i o d s o f t i m e . T h i s p r e c l u d e s any e x t r a p o l a t i o n or any p r e d i c t i o n o f a s t e a d y - s t a t e i f i t occurs o u t s i d e t h e p e r i o d o f o b s e r v a t i o n s . 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U n i v . o f B r i t i s h Columbia, Dept. o f Bot. L i k e n s , B. E., F. H. Bormann, N. M. Johnson, D. W. F i s h e r , and R. S. P i e r c e . 1970. E f f e c t s o f f o r e s t c u t t i n g and h e r b i c i d e • t r e a t m e n t on n u t r i e n t budgets i n t h e Hubbard Brook wat e r s h e d ecosystem. E c o l . Monogr. 40:23-47 M a c A r t h u r , R. H. 1958. A n o t e on s t a t i o n a r y age d i s t r i b u t i o n s i n s i n g l e - s p e c i e s p o p u l a t i o n s i n a community. E c o l o g y 39:146-147 M a c A r t h u r , R. H. 1961. Community. I n : P. Gray (ed.) The e n c y c l o p e d i a o f the b i o l o g i c a l s c i e n c e s , pp. 262-264. R e i n h o l d , New-York.  M o r r i s , R. F. (ed.) 1963. The dynamics o f s p r u c e budworm p o p u l a t i o n s . Men. Entomo. Soc. Can. 31:1-332 Mueller-Dombois, D. 1965. I n i t i a l the c o a s t a l D o u g l a s - f i r 38-41 i n : V. J . K r a j i n a N o r t h A m e r i c a . U n i v . Of  s t a g e s o f secondary s u c c e s s i o n i n and w e s t e r n hemlock zones, pp. (ed.) 1965. E c o l o g y o f Western B r i t i s h Columbia. Dept. o f B o t .  N o b l e , I . R. and R. 0. S l a t y e r . 1976. S u c c e s s i o n n a l m o d e l l i n g . Cont r i b u t i o n t o MAB/SCOPE c o n f e r e n c e on: "Techniques f o r s t u d y i n g dynamic changes i n t e r r e s t r i a l ecosystems." Santa B a r b a r a 1976. Odum, E. P. 1969. The s t r a t e g y o f ecosystem development. 164:262-270  Science  Odum, E. P. 1971. Fundamentals o f e c o l o g y . 3 r d ed. W. B. Saunders Co. London, XIV+574 p. O l s o n , J . S. and G. C r i s t o f o l i n i . 1966. Model s i m u l a t i o n o f Oak Ridge v e g e t a t i o n s u c c e s s i o n . Oak Ridge N a t i o n a l L a b o r a t o r y . USAFC Report ORNL 4007:106-107 Packee, E. C. 1974. The b i o g e o c l i m a t i c subzones o f Vancouver I s l a n d and t h e a d j a c e n t m a i n l a n d and i s l a n d s . M a c M i l l a n B l o e d e l L i m i t e d F o r . Res. Note. 11 p. + app. Packee, E. C. 1976. An e c o l o g i c a l approach toward y i e l d o p t i m i z a t i o n t h r o u g h s p e c i e s a l l o c a t i o n . Ph. D. thesis.. U n i v . o f M i n n e s o t a . 740 p. + app. P h e l p h s , V. H. 1973. S i t k a s p r u c e : a l i t e r a t u r e r e v i e w w i t h s p e c i a l r e f e r e n c e t o B r i t i s h Columbia. P a c i f i c F o r . Res. C e n t r e BC-X-83. V i c t o r i a . 39 p. Raup, H. M. 1967. American f o r e s t b i o l o g y . J . F o r . 65:800-803 R o d i n , L. E. and N. J . B a z i l e v i t c h . 1967. P r o d u c t i o n and m i n e r a l c y c l i n g i n t e r r e s t r i a l v e g e t a t i o n . O l i v e r and Boyd. E d i n bur.g. 288 p. S h u g a r t , H. H. J r . , T. R. Crow, and J . M. H e t t . 1973. F o r e s t succ e s s i o n models: a r a t i o n a l e and methodology f o r m o d e l l i n g f o r e s t s u c c e s s i o n o v e r l a r g e r e g i o n s . F o r e s t s c i . 19:203212. S l a t y e r , R. 0., and J . H. C o n n e l l . cession. Contribution to "Techniques f o r s t u d y i n g t r i a l ecosystems." Santa  1976. P a t t e r n s o f secondary sucMAB/SCOPE c o n f e r e n c e on: dynamic changes i n t e r r e s B a r b a r a 1976.  Stephens, G. R. and P. E. Waggoner. 1970. The f o r e s t a n t i c i p a t e d from 40 y e a r s o f n a t u r a l t r a n s i t i o n s i n mixed hardwoods. B u l l . Conn. A g r i c . . Exp. S t n . New Have. 707:1-58  S t r a h l e r , A. N. 1969. P h y s i c a l geography,. 3 r d ed. John W i l e y and Sons I n c . New Y o r k . 733 p.  53  Thompson, W. A., and I . V e r t i n s k y . 1975. A p p l i c a t i o n o f Markov chains to a n a l y s i s of s i m u l a t i o n of b i r d s f o r a g i n g . J . t h e o r . B i o l . 53:285-307 V i e r e c k , L. A. 1973. W i l d f i r e i n the t a i g a o f A l a s k a . Quat. Res. (N.Y.) 3:465-495 V i t o u s e k , P. M. and W. A. R e i n e r s . 1975. Ecosystem s u c c e s s i o n and n u t r i e n t r e t e n t i o n : a h y p o t h e s i s . B i o s c i e n c e 2 5 ( 6 ) : 376381 Waggoner, P. E. and G. R. Stephens. 1970. T r a n s i t i o n p r o b a b i l i t i e s f o r a f o r e s t . Nature 225:1160-1161 W h i t t a k e r , R. H. 1953. A c o n s i d e r a t i o n o f c l i m a x t h e o r y : t h e c l i m a x as a p o p u l a t i o n and p a t t e r n . E c o l . Monogr. 23:41-78 W h i t t a k e r , R. H. 1957. Recent e v o l u t i o n o f e c o l o g i c a l c o n c e p t s i n r e l a t i o n t o the e a s t e r n f o r e s t s o f N o r t h A m e r i c a . Am. J . Bot. 44:197-206 W h i t t a k e r , R. H. 1970. Communities London, O n t a r i o . 162 p.  and ecosystems.  MacMillan,  Analysis  and m o d e l l i n g o f i n t e r s p e c i e s  competition  d u r i n g f o r e s t secondary s u c c e s s i o n .  Pierre Bellefleur  CHAPTER I I  The  a n a l y s i s o f t r e e growth v a r i a t i o n w i t h i n d i f f e r e n t p l o t types i n Coastal  B r i t i s h Columbia.  55 ABSTRACT  R e l a t i v e abundance and r e l a t i v e b a s a l a r e a o f each major t r e e s p e c i e s were p l o t t e d a g a i n s t s t a n d age and compared w i t h s t a n d - t y p e for  f i v e B i o g e o c l i m a t i c Subzones o f B r i t i s h Columbia.  succession  Forest  data  heterogeneity  w i t h i n each subzone was b r o k e n down by c l a s s i f y i n g sample p l o t s i n t o  statis-  t i c a l l y d e f i n e d p l o t t y p e s i n which t r e e c o m p o s i t i o n was assumed t o g i v e an image o f s i t e c o n d i t i o n s and c o m p e t i t i o n regimes.  The b a s a l a r e a growth  v a r i a t i o n o f t r e e s p e c i e s was compared among p l o t types by a n a l y s i s o f v a r i a n c e and i t s c o r r e l a t i o n w i t h s t a n d age and s i t e i n d e x was t e s t e d . F i n a l l y , t h e s i t e i n d e x d i s t r i b u t i o n o f each subzone was a n a l y s e d and c o r r e l a t e d w i t h subzone c h a r a c t e r i s t i c s . The  time s e r i e s o f s p e c i e s r e l a t i v e abundance r e v e a l e d t h e same type  of species behaviour  as t h e s t a n d - t y p e  succession data o f the previous  c h a p t e r b u t gave more d e t a i l s about l e s s abundant s p e c i e s .  Two t o seven  p l o t types p e r subzone were s u f f i c i e n t t o c l a s s i f y a l l p l o t s .  Tree  s p e c i e s o c c u r r i n g i n more t h a n one p l o t type showed s i g n i f i c a n t d i f f e r e n c e s i n t h e i r b a s a l a r e a growth which c o u l d n o t be e n t i r e l y accounted f o r by s t a n d age and s i t e i n d e x .  The response o f c o - o c c u r r i n g s p e c i e s was found  to v a r y between subzones and mean subzone s i t e i n d e x was h i g h l y c o r r e l a t e d w i t h s o i l moisture d e f i c i t .  I t was concluded  t h a t t h e v a r i a t i o n i n growth  r a t e s due t o d i f f e r e n c e s i n s i t e c o n d i t i o n s and c o m p e t i t i o n regimes i s one o f t h e agents g e n e r a t i n g  succession.  56 RESUME  On a t r a c e l'abondance r e l a t i v e e t l a s u r f a c e t e r r i e r e r e l a t i v e des p r i n c i p a l e s especes a r b o r e s c e n t e s  en f o n c t i o n de l'age des s t a t i o n s e t l ' o n  a compare ces courbes avec l e s donnees de s u c c e s s i o n des s t a t i o n s - t y p e s dans c i n q sous-zones b i o g e o c l i m a t i q u e s de Colombie B r i t a n n i q u e .  L'hetero-  g e n e i t e de l a fore"t a l ' i n t e r i e u r des sous-zones a e t e r e d u i t e en c l a s s i f i a n t l e s p l a c e s - e c h a n t i l l o n s en p l a c e s - t y p e s ou l a c o m p o s i t i o n a r b o r e s cente  d o n n e r a i t une bonne i d e e des c o n d i t i o n s du s i t e e t du regime de com-  petition.  L a v a r i a t i o n dans l a c r o i s s a n c e en s u r f a c e t e r r i e r e des essences  arborescentes  a e t e comparee e n t r e l e s p l a c e s - t y p e s p a r a n a l y s e de v a r i a n c e  et s a c o r r e l a t i o n avec l'age des s t a t i o n s e t avec l ' i n d i c e de s i t e f u t testee.  E n f i n , l a d i s t r i b u t i o n de l ' i n d i c e de s i t e de chaque sous-zone  f u t analysee  e t c o r r g l e e avec l e s a t t r i b u t s de l a sous-zone.  L ' e v o l u t i o n de l'abondance r e l a t i v e des especes a r e v e l e l e meme genre de comportement que l e s donnees s u r l a s u c c e s s i o n des s t a t i o n s - t y p e s du c h a p i t r e precedent,  avec p l u s de d e t a i l s s u r l e s especes moins abondantes.  De deux a sept p l a c e s - t y p e s p a r sous-zone f u r e n t s u f f i s a n t e s pour c l a s s i f i e r t o u t e s l e s p l a c e s - e c h a n t i l l o n s . Les especes r e t r o u v e e s dans p l u s d'une p l a c e - t y p e ont montre des d i f f e r e n c e s s i g n i f i c a t i v e s dans l e u r c r o i s s a n c e en s u r f a c e t e r r i e r e i n e x p l i c a b l e s p a r seulement l'Sge des s t a t i o n s e t l ' i n d i c e de s i t e .  La reponse des especes en c o e x i s t e n c e v a r i e e n t r e l e s sous-  zones e t l ' i n d i c e de s i t e moyen e s t c o r r e l e au manque d ' h u m i d i t e du s o l . On a c o n c l u que l a v a r i a t i o n des taux de c r o i s s a n c e due aux d i f f e r e n c e s de c o n d i t i o n s du s i t e e t des regimes de c o m p e t i t i o n e s t l ' u n des agents q u i engendre l a s u c c e s s i o n .  57 INTRODUCTION  In t h e p r e v i o u s c h a p t e r , secondary l e v e l o f f o r e s t stand-types  s u c c e s s i o n was a n a l y s e d a t t h e  i n t h e C o a s t a l D o u g l a s - f i r and t h e C o a s t a l  Western Hemlock zones and subzones o f B r i t i s h Columbia.  Markov models  f a i l e d t o a d e q u a t e l y f i t t h e o b s e r v a t i o n s and i t was concluded f o r e s t s u c c e s s i o n was seemingly r e a s o n f o r t h e inadequacy  not Markovian.  that  I t appeared t h a t t h e main  o f t h e Markov approach was t h a t i t n e c e s s i t a t e d  p o o l i n g t o g e t h e r p l o t s t h a t belonged  t o d i f f e r e n t communities, s i n c e  u n d e r s t o r y v e g e t a t i o n was not a v a i l a b l e t o d i s t i n g u i s h them.  However,  v a r i a t i o n i n t r e e c o m p o s i t i o n might be s u i t a b l e t o d i s t i n g u i s h p l o t s broad c a t e g o r i e s . t o respond  S p e c i e s o c c u r r i n g - i n more than one c a t e g o r y a r e l i k e l y  and t o compete d i f f e r e n t l y .  These s e t s o f c o n d i t i o n s under  Which c o m p e t i t i o n t a k e s p l a c e w i l l be termed " c o m p e t i t i o n The  into  regimes".  o b j e c t i v e s o f t h i s c h a p t e r a r e : (1) To m o n i t o r t h e c o m p o s i t i o n  o f each subzone f o r t h e r o t a t i o n p e r i o d , i n terms o f r e l a t i v e abundance and r e l a t i v e b a s a l a r e a f o r each major t r e e s p e c i e s .  (2) To compare  t h e s e o b s e r v a t i o n s w i t h t h e s t a n d - t y p e s u c c e s s i o n d a t a mentioned above. (3)  To s e p a r a t e each subzone i n t o major c o m p e t i t i o n regimes.  (4) To  a n a l y s e t h e growth v a r i a t i o n o f each s p e c i e s among t h e d i f f e r e n t  competi-  t i o n regimes w i t h i n each subzone a t t h e l e v e l o f t h e f o r e s t s t a n d . t e s t c o r r e l a t i o n o f t r e e growth w i t h s t a n d age and s i t e i n d e x .  (5) To  (6) To  a n a l y s e s i t e index d i s t r i b u t i o n f o r each subzone and t o t e s t i t s c o r r e l a t i o n w i t h subzone c h a r a c t e r i s t i c s . Achievement o f t h e s e o b j e c t i v e s s h o u l d p e r m i t t o t e s t t h e f o l l o w i n g two hypotheses:  (1) The growth o f a g i v e n s p e c i e s i s i n f l u e n c e d by t h e  58 n a t u r e and abundance o f o t h e r s p e c i e s growing  i n t h e same s t a n d . (2)  The  d i f f e r e n c e i n net r a t e o f p o p u l a t i o n growth o f d i f f e r e n t t r e e p o p u l a t i o n s i s s u f f i c i e n t t o t r i g g e r t r a n s i t i o n from one p l o t t y p e t o a n o t h e r , hence t o g e n e r a t e  DATA AND  and  succession.  METHODS  H e t e r o g e n e i t y w i t h i n subzones The d a t a s e t used f o r t h i s study i s p a r t of t h e d a t a bank of M a c M i l l a n B l o e d e l L i m i t e d , F o r e s t r y D i v i s i o n , and was previous chapter.  d e s c r i b e d i n the  I t c o n s i s t s o f 730 Permanent Sample P l o t s  and  Spacing Assessment P l o t s , a l l l o c a t e d w i t h i n t h e C o a s t a l D o u g l a s - f i r and C o a s t a l Western Hemlock zones o f B r i t i s h Columbia. In t h e p r e v i o u s c h a p t e r , each f o r e s t p l o t was  assigned a stand-  t y p e , depending on w h i c h s p e c i e s had t h e a b s o l u t e maximum stem count and b a s a l a r e a .  That approach had t h e advantage o f c a t e g o r i z i n g t h e  whole f o r e s t i n t o d i f f e r e n t s t a t e s and p e r m i t t e d m o n i t o r i n g and s i m u l a t i o n of the s u c c e s s i o n from one s t a t e t o another through a f i n i t e - s t a t e Markov model.  However, i t c o n c e a l e d  abundance was  a l o t o f i n f o r m a t i o n about s p e c i e s whose  always t o o low t o c o n s t i t u t e a s t a n d - t y p e .  abundance o f each t r e e s p e c i e s was  was  relative  t h e r e f o r e p l o t t e d against stand  t o show i t s dynamics w i t h i n t h e v a r i o u s subzones. abundance ( i n p e r c e n t a g e )  The  The  age  species r e l a t i v e  chosen over a b s o l u t e abundance on  the  b a s i s o f the u n e q u a l t o t a l number of o b s e r v a t i o n s a t each f i v e - y e a r measurement.  The  comparison o f t h e s e r e s u l t s w i t h s t a n d - t y p e  d i s t r i b u t i o n w i l l be d i s c u s s e d  later.  frequency  59 The main g o a l i s t o f i n d i f one can d e t e c t whether the growth o f a given species i s i n d i f f e r e n t to species composition the same t i m e .  S e v e r a l cases may  occur.  i n the s t a n d a t  A s u b j e c t s p e c i e s may  cover  a  wide range o f abundance i n the s t a n d , from a u n i q u e s e e d l i n g t o a b s o l u t e predominance.  The  r e s t o f the s t a n d may  i n t u r n be d i s t r i b u t e d among  v i r t u a l l y any number o f o t h e r s p e c i e s , w i t h v a r y i n g r e l a t i v e abundance, thus c o n s t i t u t i n g s e v e r a l c o m p e t i t i o n r e g i m e s .  The d i f f e r e n c e i n r a t e  o f growth can be m o n i t o r e d  a t the l e v e l o f each i n d i v i d u a l stem, and  the l e v e l o f the s p e c i e s .  Only the l a t t e r case i s c o n s i d e r e d i n t h i s  at  chapter. Each B i o g e o c l i m a t i c Subzone as d e f i n e d by K r a j i n a (1969) and Packee (1974, 1976) conditions.  has a t h e o r e t i c a l l y homogeneous s e t of g e o c l i m a t i c  However, v a r i o u s v e g e t a t i o n p a t t e r n s r e v e a l a mosaic o f  h a b i t a t types w i t h i n each subzone (Daubenmire 1968, Daubenmire 1968).  Daubenmire and  S i n c e most s p e c i e s can occur w i t h i n s e v e r a l v e g e t a t i o n  p a t t e r n s , i t i s necessary  t o d i s t i n g u i s h t y p i c a l p a t t e r n s which might  o f f e r c o m p l e t e l y d i f f e r e n t s i t u a t i o n s from the v i e w p o i n t o f c o m p e t i t i o n . Packee (1976) has r e v i e w e d which a p p l y t o s o u t h w e s t e r n  f o u r major v e g e t a t i o n c l a s s i f i c a t i o n schemes B r i t i s h Columbia.  Rowe's (1972) c l a s s i f i c a t i o n , based on the p r e v i o u s work o f H a l l i d a y (1937), i s e s s e n t i a l l y a g e o g r a p h i c r e g i o n s o f Canada.  d e s c r i p t i o n o f the d i f f e r e n t f o r e s t  Southwestern B r i t i s h Columbia l i e s e n t i r e l y w i t h i n  t h e Coast F o r e s t R e g i o n o f S u b a l p i n e F o r e s t R e g i o n , and Rowe (1972) subdivides i t into 4 Forest Sections.  These S e c t i o n s are d e f i n e d q u i t e  a r b i t r a r i l y "from above" (Rowe 1972), i . e . f o l l o w i n g conspicuous g r a p h i c a l e n t i t i e s , f o r the purpose o f convenience,  geo-  and r e p r e s e n t broad  60 cover t y p e s o f r a t h e r s t a b l e a s s o c i a t i o n s .  Rowe (1972) mentions t h a t a  c l a s s i f i c a t i o n "from below", i . e . based on e c o l o g i c a l knowledge o f v e g e t a t i o n , would be d e s i r a b l e , b u t would r e q u i r e i n f o r m a t i o n n o t a v a i l a b l e on a l a r g e s c a l e . The S o c i e t y o f American F o r e s t e r s (1954) has d e s c r i b e d f o r e s t types and f o r e s t c o v e r t y p e s f o r Canada and t h e U n i t e d S t a t e s .  Packee  (1976) has i d e n t i f i e d 16 o f t h e s e c o v e r t y p e s r e l e v a n t t o s o u t h w e s t e r n B r i t i s h Columbia.  The c o v e r t y p e s a r e d e f i n e d on t h e b a s i s o f p r e s e n t  vegetation, regardless of the p o t e n t i a l climax.  The t y p e name i s based  on t h e s p e c i e s which c o n s t i t u t e s a t l e a s t 50% o f t h e stem c o m p o s i t i o n , o r , i f more t h a n one s p e c i e s p r e d o m i n a t e s , t h e t y p e i s g i v e n a b i n o m i a l o r t r i n o m i a l name.  The c o m p o s i t i o n o f each t y p e i s d e s c r i b e d w i t h o u t any  q u a n t i t a t i v e assessment. F r a n k l i n and Dyrness (1969, 1973) p u b l i s h e d an e c o l o g i c a l s t u d y o f the p l a n t communities o f Washington and Oregon.  Their c l a s s i f i c a t i o n i s  based on t h e zone, d e f i n e d as t h e a r e a c o v e r e d by t h e c l i m a t i c c l i m a x association.  The a s s o c i a t i o n s found i n each zone a r e d e s c r i b e d i n q u a l i -  t a t i v e terms -- r a r e , o c c a s i o n a l , common, and abundant -- based on t h e presence o f s p e c i e s .  Seven o f F r a n k l i n and D y r n e s s ' (1973) zones o c c u r  i n s o u t h w e s t e r n B r i t i s h Columbia (Packee 1976). K r a j i n a (1969) c l a s s i f i e d t h e f o r e s t s o f B r i t i s h Columbia i n t o B i o g e o c l i m a t i c Zones and Subzones.  Packee (1974) f o l l o w e d t h i s  classi-  f i c a t i o n scheme f o r t h e c o a s t a l f o r e s t s i n d e f i n i n g d e t a i l e d b o u n d a r i e s at t h e l e v e l o f t h e subzones f o r Vancouver I s l a n d and t h e a d j a c e n t mainl a n d and i s l a n d s , and r e c o g n i z e d a new subzone w i t h i n t h e C o a s t a l Western Hemlock Zone, t h e Fog S i t k a Spruce - Western Hemlock Subzone.  Packee  (1976)  61 made some a d d i t i o n a l m o d i f i c a t i o n s t o h i s c l a s s i f i c a t i o n , based on h i s f i n d i n g s t h a t m o i s t u r e d e f i c i t w i t h 200 mm c i t y was  o f s o i l water s t o r a g e capa-  a good c l i m a t i c v a r i a b l e t o d i f f e r e n t i a t e zones.  D e f i n i t i o n o f t h e c l a s s i f i c a t i o n scheme For the purpose of t h i s s t u d y , the c l a s s i f i c a t i o n scheme must be a b l e t o d i s t i n g u i s h between v e g e t a t i o n p a t t e r n s which p r e s e n t competition regimes,  different  where a c o m p e t i t i o n regime i s d e f i n e d by the number  of t r e e s p e c i e s p r e s e n t i n a p l o t and by t h e abundance of each s p e c i e s . The measure o f abundance s h o u l d be based on an index as r e p r e s e n t a t i v e as p o s s i b l e o f biomass.  The  assessment s h o u l d be made on the b a s i s of  p r e s e n t v e g e t a t i o n , w i t h o u t r e f e r e n c e t o the assumed c l i m a x , nor t o understory.  F i n a l l y , t h e method s h o u l d be q u a n t i t a t i v e and o b j e c t i v e so t h a t  p l o t s c o u l d be c a t e g o r i z e d by computer and groups be s t a t i s t i c a l l y described.  S i n c e none o f the c l a s s i f i c a t i o n schemes mentioned above s a t i s -  f i e s a l l these requirements,  a s u i t a b l e scheme was  developed.  S t r i c t l y s p e a k i n g no two p l o t s i n a subzone a r e a l i k e , and p l o t can c o n s t i t u t e a c a t e g o r y o f i t s own. as many c a t e g o r i e s as t h e r e a r e p l o t s .  This i s useless since i t y i e l d s  At the o t h e r extreme, a l l the  p l o t s can be c o n s i d e r e d s i m i l a r s i n c e they a l l belong  t o the same subzone.  Somewhere between t h e s e extremes, p l o t s w i t h s i m i l a r c o m p o s i t i o n c o n s t i t u t e a s i m i l a r c o m p e t i t i o n regime.  each  should  I t i s argued t h a t , from the  c o m p e t i t i o n v i e w p o i n t , t h e s i n g l e most i m p o r t a n t parameter r e l e v a n t t o any s p e c i e s ' growth i s the n a t u r e and abundance of c o m p e t i t o r s , assuming that environmental  a t t r i b u t e s are homogeneous w i t h i n the p l o t  boundaries.  I f t h e maximum number o f major p o t e n t i a l t r e e s p e c i e s i s 8 f o r i n s t a n c e ,  t h i s g i v e s 255 p o t e n t i a l s p e c i e s c o m b i n a t i o n s . s i n c e c e r t a i n combinations was  I n p r a c t i c e however,  of species are b i o l o g i c a l l y impossible, i t  found t h a t a maximum o f 7 groups was s u f f i c i e n t t o c o n v e n i e n t l y sub-  d i v i d e each subzone, p r o v i d e d l e s s abundant s p e c i e s were grouped t o g e t h e r . The  obvious  c h o i c e o f a measure o f abundance i s t o t a l volume p e r  s p e c i e s , but s i n c e the data s e t l a c k s t r e e height i n f o r m a t i o n f o r c e r t a i n s p e c i e s , t h e next b e s t c h o i c e i s b a s a l a r e a . was  F o r each p l o t , b a s a l a r e a  c a l c u l a t e d f o r every s p e c i e s a t each f i v e - y e a r measurement on a p e r  hectare b a s i s .  Species o c c u r r i n g i n a l l observations, with a basal area  r e p r e s e n t i n g a t l e a s t 5% o f t h e t o t a l o f each o b s e r v a t i o n a r e r e f e r r e d t o as "major s p e c i e s " and were i n c l u d e d i n t h e name o f t h e p l o t t y p e .  Species  w i t h s m a l l e r b a s a l a r e a and which do n o t occur i n a l l o b s e r v a t i o n s a r e r e f e r r e d t o as "minor s p e c i e s " .  The p r e s e n c e o f minor s p e c i e s was i n d i -  c a t e d i n t h e name o f t h e p l o t t y p e by a p l u s s i g n ( • ) i n s u f f i x .  For  a l l s p e c i e s o c c u r r i n g i n a number o f p l o t t y p e s w i t h i n one subzone, oneway  a n a l y s i s o f v a r i a n c e was used t o d e t e c t v a r i a t i o n i n growth v a r i a b l e s  among p l o t t y p e s .  The v a r i a b l e s a n a l y s e d belong t o two groups: age  a t t r i b u t e s and b a s a l a r e a a t t r i b u t e s .  The f i r s t group c o n s i s t s o f t h e  mean age o f t h e p l o t s and t h e mean s i t e i n d e x f o r P_. m e n z i e s i i and J_. h e t e r o p h y l l a . increment  The second group c o n t a i n s t h e mean f i v e - y e a r b a s a l  area  and t h e mean b a s a l a r e a o f t h e s u b j e c t s p e c i e s , t h e mean r a t i o  o f t h e two p r e v i o u s v a r i a b l e s , t h e mean t o t a l b a s a l a r e a ( a l l t r e e s p e c i e s ) , and t h e mean r a t i o o f b a s a l a r e a increment  over t o t a l b a s a l a r e a .  t e i n d e x d i s t r i b u t i o n was f u r t h e r a n a l y s e d a t t h e subzone l e v e l .  The s i -  63 RESULTS AND DISCUSSION  Dynamics o f f o r e s t The  stands  changes i n mean s p e c i e s r e l a t i v e abundance a g a i n s t s t a n d age  are p r e s e n t e d  i n F i g u r e s 6 A t o J . R e s u l t s a r e shown as stem count  p e r c e n t a g e s and b a s a l a r e a p e r c e n t a g e s .  As expected,  v e r y s i m i l a r t o t h e graphs o f t h e s t a n d - t y p e the p r e v i o u s c h a p t e r  (Figure 5).  t h e s e graphs a r e  frequencies presented i n  Stand-type was d e f i n e d as t h e s p e c i e s  w i t h t h e maximum number o f stems (or b a s a l area) i n a s t a n d . the p r e v i o u s  Therefore  s e t o f graphs ( F i g u r e 5) showed t h e p r o p o r t i o n o f stands o f  each type a t each f i v e - y e a r measurement and t h i s s e t shows t h e p r o p o r t i o n o f stems o f each s p e c i e s a t each measurement.  Obviously  i f 90% o f t h e  Stems a r e P. m e n z i e s i i a t age 35 f o r i n s t a n c e , chances a r e t h a t a h i g h p r o p o r t i o n o f t h e stands w i l l be o f t h e type P_. m e n z i e s i i .  However  s p e c i e s r e p r e s e n t i n g a low p r o p o r t i o n o f t h e subzone t o t a l stems i n t h e s p e c i e s r e l a t i v e abundance graph might never c o n s t i t u t e a s t a n d - t y p e , and would n e v e r appear i n t h e s t a n d - t y p e species behaviour  graphs.  A b r i e f description ofthe  i s g i v e n f o r each zone, and t h e r e l a t i o n t o growth  v a r i a t i o n w i l l be d i s c u s s e d  later.  D o u g l a s - f i r Zone The D r y D o u g l a s - f i r Subzone i s dominated by P_. m e n z i e s i i , b u t T. p l i c a t a i n c r e a s e s s i g n i f i c a n t l y a f t e r 70 years  ( F i g u r e s 6 A and B ) ,  a l t h o u g h t h i s t r e n d i s exaggerated f o r r e a s o n s e x p l a i n e d i n t h e p r e v i o u s chapter.  A. r u b r a appears as a p i o n e e r and n e a r l y v a n i s h e s  at approxi-  m a t e l y 60 y e a r s , w h i l e P_. c o n t o r t a and T. h e t e r o p h y l l a seem t o be  64  FIGURE 6 Mean s p e c i e s abundance a t f i v e - y e a r measurements. The res u l t s a r e p r e s e n t e d a l t e r n a t i v e l y i n number o f s t e m s and i n b a s a l area f o r each subzcne: A E C D E F G H I J  Dry Dry Wet Wet Dry Dry Wet Wet Fcq Fcg  D o u g l a s - f i r Subzone (stems) D o u g l a s - f i r Subzone ( b a s a l a r e a ) D o u g l a s - f i r Subzone (stems) D o u g l a s - f i r Subzone ( b a s a l a r e a ) W e s t e r n Hemlock Subzone (stems) W e s t e r n Hemlock Subzone ( b a s a l a r e a ) W e s t e r n Hemlock Subzone (stems) W e s t e r n Hemlock Subzone ( b a s a l a r e a ) W e s t e r n Hemlock Subzone (stems) w e s t e r n Hemlock Subzone ( b a s a l a r e a )  The s y m b o l s used F. !• T. A. JE« J• P. A.  f o r each s p e c i e s  are:  menziesii hetgPQ.phYila £ 1 i cat a rubra sitchensis  contorta grandis ( i n t h e Wet A. a m a b i l i s ( i n t h e Wet  • O & X f X ^  roacrophyllum Douglas-fir  Subzone)  W e s t e r n Hemlock  Subzcne)  4. . . . . . ,4.  i I  SPECIES R E L A T I V E B A S A L A R E A  99  67  c  n  c  o  r  -  c  D  m  s  T  r  n  c  M  '  —  30NVQNnaV 3 A H V ~ l 3 d S 3 D 3 d S  o  SPECIES R E L A T I V E B A S A L A R E A O  ^  89  P  O  C  O  J  ^  C  J  I  C  D  -  J  C  O  t  D  69  3 3 N V 0 N n a V 3AI±V13cJ S3l03dS  SPECIES R E L A T I V E B A S A L A R E A  OZ.  71  30NVaNn9V 3AI±V33d S3l03dS  72  V 3 d V "WSVa 3AI±V13d S3l03dS  73  3DNVQNnaV 3 A I 1 V 1 3 U S 3 D 3 d S  SPECIES R E L A T I V E B A S A L A R E A  PL  75 i n c r e a s i n g t o r e a c h 10% r e l a t i v e abundance by age 90.  The r e c e n t work o f  Packee (1976) d e s c r i b e s the s u c c e s s i o n from e a r l y i n v a s i o n by herbs and  shrubs up t o the t r e e s t r a t u m c l i m a x .  Although  he g i v e s no q u a n t i -  t a t i v e assessment, t h e s e r e s u l t s g e n e r a l l y agree w i t h h i s d e s c r i p t i o n . He r e c o g n i z e s  t h e i n c r e a s e o f T. p l i c a t a i n the a p p r o p r i a t e f o r e s t t y p e ,  and he p o i n t s out t h a t Quercus g a r r y a n a Pursh. may  be l o c a l l y i m p o r t a n t .  r a r e (<* 1%) The Wet  Dougl. and A r b u t u s m e n z i e s i i  These l a s t two  s p e c i e s were  i n the d a t a s e t . D o u g l a s - f i r Subzone i s a l s o the domain o f P_. m e n z i e s i i , but  J_. h e t e r o p h y l l a may at l a t e r s t a g e s  l o c a l l y be abundant at e a r l y s t a g e s , and J_. p l i c a t a  ( F i g u r e s 6 C and D) .  The  d e c l i n e of P_. m e n z i e s i i a f t e r  age 60 i s e x a g g e r a t e d f o r r e a s o n s mentioned above. e a r l y and tends t o d e c r e a s e , are few.  extremely  A. r u b r a  invades  P_. s i t c h e n s i s , A. g r a n d i s , and A. macrophyllum  Packee (1976) contends t h a t P_. s i t c h e n s i s i s s e r a i and  a c l i m a x o f P_. m e n z i e s i i -- T. h e t e r o p h y l l a and s i t e s , T. p l i c a t a -- T. h e t e r o p h y l l a -- A.  l o c a l l y on the  suggests moister  grandis.  Western Hemlock Zone J_. h e t e r o p h y l l a i s g e n e r a l l y more abundant i n the Dry Hemlock Subzone, even though P_. m e n z i e s i i may o f 0.68  ( F i g u r e s 6 E and F ) .  T. p l i c a t a i n c r e a s e s s t e a d i l y . perceptible.  Western  r e a c h a r e l a t i v e abundance  A. r u b r a i s low and d e c r e a s e s f a s t , w h i l e A. g r a n d i s and A. macrophyllum are b a r e l y  Packee (1976) r e c o g n i z e s t h a t b o t h A. r u b r a and P_. m e n z i e s i i  are e a r l y i n v a d e r s and he d e s c r i b e s the c l i m a x as m a i n l y P_. m e n z i e s i i (on d r y s i t e s ) and J_. h e t e r o p h y l l a , w i t h J_. p l i c a t a  locally.  76  I n t h e Wet Western Hemlock Subzone, T. h e t e r o p h y l l a i s t h e most abundant, A. r u b r a and P_. m e n z i e s i i a r e n o t v e r y abundant i n v a d e r s , P_. s i t c h e n s i s i s s e r a i and A. a m a b i l i s may form a l o c a l c l i m a x w i t h T. p l i c a t a and T. h e t e r o p h y l l a ( F i g u r e s 6 G and H ) . These r e s u l t s agree w i t h p a c k e e s (1976) d e s c r i p t i o n , w i t h t h e e x c e p t i o n o f P_. s i t c h e n s i s r  which he seems t o p l a c e l a t e r i n s u c c e s s i o n ( a l t h o u g h he g i v e s no t i m e scale). The Fog Western Hemlock Subzone i s n o t v e r y w e l l d e s c r i b e d by t h e d a t a s e t , s i n c e t h e r e a r e o n l y 19 o b s e r v a t i o n s , a l l between ages 35 and 60 ( F i g u r e s I and J ) .  I t shows an e a r l y i n v a s i o n by T. p l i c a t a , T. he-  t e r o p h y l l a , and P_. s i t c h e n s i s .  A f t e r 45 y e a r s , T. h e t e r o p h y l l a r e a c h e s  a r e l a t i v e abundance o f over 80%. P_. m e n z i e s i i and A. r u b r a show a r e l a t i v e abundance o f about 1%.  Packee (1976) a s s e s s e s A. r u b r a as t h e  main p i o n e e r , f o l l o w e d by e i t h e r P_. s i t c h e n s i s o r P_. s i t c h e n s i s -- T. het e r o p h y l l a (and o c c a s i o n a l l y P_. m e n z i e s i i ) , and a c l i m a x dominated by T. h e t e r o p h y l l a , l o c a l l y a s s o c i a t e d w i t h J_. p l i c a t a , A. a m a b i l i s , o r P_. s i t c h e n s i s . P l o t type c l a s s i f i c a t i o n The r e s u l t s o f t h e c l a s s i f i c a t i o n d e s c r i b e d p r e v i o u s l y a r e p r e s e n t e d f o r each subzone i n T a b l e s 5 t o 9.  The t a b l e s show t h e number o f p l o t s  i n each p l o t t y p e , a l l t h e t r e e s p e c i e s a c c o u n t i n g f o r 1% o r more o f t h e mean b a s a l a r e a , t h e mean b a s a l a r e a (and s t a n d a r d d e v i a t i o n ) and t h e r e l a t i v e b a s a l a r e a f o r each s p e c i e s . The Dry D o u g l a s - f i r Subzone i s s u b d i v i d e d i n t o f o u r p l o t types (Table 5): Pm, Pmt, PmTp*, and PmTpTht .  I n a l l p l o t t y p e s , P_. m e n z i e s i i  77  Met  Type  1) Fm  N  Species ( > U B.A.)  mean E.A. (m /h)  (s)  2  mean E.A. (%)  61  P. m e n z i e s i i  41. 6  (9.8)  99.2  2)  Pm +  34  P. m e n z i e s i i P. c e n t o r t a A. r u b r a  23.4 7.4 4.2  (13.0) (11.9) (7.1)  64.6 19.6 14.0  3)  PmT p+  23  P. m e n z i e s i i 2« pr lu bi rc aa t a £• A. g r a n d i s T. ^ - t e r g p h y l l a P. ccp.tor t a  23.8 3.7 1.3 0.3 0.7 0.7  (9.2) (3.5) (2.4) (0.6) (0.9) (1.8)  79.9 10.8 4.3 1.8 1.7 1.4  7  P. m e n z i e s i i T. p l i c a t a 1. h e t e r o p h y l l a A. r u b r a  32. 4 (14.6) 10.8 (6.2) 4.8 (2.3) 1.6 (1.1)  65.7 21.3 9.3 3.8  FmTpTh +  TABLE 5 Forest  plot  types  o f t h e Dry D o u g l a s - f i r  Subzone.  The mnemonics f o r t h e p l o t types are derived from t h e first l a t t e r o f t h e genus and s p e c i e s o f e a c h s p e c i e s o c c u r r i n g i n e a c h o b s e r v a t i o n w i t h an a b u n d a n c e c f a t least 5% c f t h e b a s a l a r e a f o r t h e o b s e r v a t i o n . A p l u s s i g n (+) i n d i c a t e s t h a t o t h e r s p e c i e s a r e p r e s e n t w i t h an abundance c f a t l e a s t 1% o f t h e b a s a l a r e a , b u t n o t n e c e s s a r i l y i n each o b s e r v a t i o n . V a l u e s i n b r a c k e t s a r e t h e s t a n d a r d dev i a t i o n s o f the basal area.  78 a c c o u n t s f o r a t l e a s t 65% o f t h e b a s a l a r e a . t h e Pm-* p l o t t y p e , and T. p l i c a t a PmTpTht p l o t t y p e s . i n PmTpTh*.  P_. c o n t o r t a  i s typical of  i s t y p i c a l o f b o t h PmTp* and  J_. h e t e r o p h y l l a  i s s l i g h t l y abundant (9.3%) o n l y  The Wet D o u g l a s - f i r Subzone has s i x p l o t types  Pro*, PmTh+, PmTp+, PmThTp+, PmThAgTp*, and ThTp* .  (Table 6 ) :  P_. m e n z i e s i i o c c u r s  i n a l l but t h e l a s t p l o t t y p e , w i t h a t l e a s t 41% o f t h e b a s a l a r e a i n each.  T. h e t e r o p h y l l a w i t h 20.5% t o 56.5% o f t h e b a s a l a r e a i s a major  s p e c i e s i n f o u r p l o t types and T_. p l i c a t a a c c o u n t s f o r a t l e a s t 14% i n the l a s t f o u r p l o t  types.  There a r e s i x p l o t t y p e s i n t h e Dry Western Hemlock (Table 7 ) :  Subzone  Th*, PmTh, PmThArt, PmThTp, ThTpt, and Pm+. P_. m e n z i e s i i i s  t h e most abundant s p e c i e s i n f o u r o u t o f s i x p l o t t y p e s , w i t h a t l e a s t 51% i n b a s a l a r e a , and J_. h e t e r o p h y l l a i s t h e most abundant i n t h e two o t h e r p l o t t y p e s , w i t h a minimum o f 75% i n b a s a l a r e a .  A. r u b r a and J_. p l i c a t a  a r e t h e o n l y o t h e r two s p e c i e s w h i c h can q u a l i f y as major s p e c i e s .  The  Wet Western Hemlock Subzone i s s u b d i v i d e d i n t o seven p l o t t y p e s , t h e h i g h e s t number o f a l l subzones (Table 8 ) . ThTp+, ThPsTpt, ThTpPm+, and ThPmt.  They a r e : Th, ThPs*, ThAa,  T. h e t e r o p h y l l a i s t h e p r e d o m i n a t i n g  major s p e c i e s i n a l l p l o t t y p e s , J_. p l i c a t a i s major i n t h r e e , and P_. menz i e s i i and P_. s i t c h e n s i s i n two. O n l y two p l o t types were f o u n d i n t h e Fog Western Hemlock Subzone (Table 9 ) : ThPs* and ThTp*.  There a r e o n l y  19 o b s e r v a t i o n s i n t h i s subzone and t h i s i s i n s u f f i c i e n t t o r e v e a l i t s f u l l diversity. both p l o t types.  T_. h e t e r o p h y l l a i s by and l a r g e t h e most abundant i n P_. s i t c h e n s i s  i s a l s o found i n b o t h .  o c c u r s i n ThPs+ o n l y , and J_. p l i c a t a i n ThTpt o n l y .  P_. m e n z i e s i i  Plct  Type  1) l?ra+  N  Species <>1S E.A.)  110  N  mean E . f i . (s) (m2/h)  mean E.A. (%)  P. m e n z i e s i i A..rubra  36. 6 (11.3) 1. 2 (3.2)  95.5 3.1  2)  PmTh+  57  P. 1• A.  menziesii heterophylla rubra  26. 7 (13.1) 8. 3 (11.8) 1. 7 (4.5)  73.9 20. 5 4.5  3)  PmTp+  38  R« T. P. A. A. 1.  menziesii plicata sitchensis grandis rubra macrophyllum  2•  heteroph y l l a  28. 4 6. 6 2. 6 1. 8 1. 4 1. 1 0. 6  73.3 13.9 3.6 3.2 2.6 2.2 1.1  (8.9) (6.6) (8.7) (6.4) (2.7) (3.0) (0.8)  4)  PmThTp+  61  P. m e n z i e s i i 2• h e t e r o p h y l l a T. p l i c a t a A. m a c r o p h y l l u m  26. 8 (17.6) 12. 6 (10.0) 8. 3 (8.5) 0. 8 (2.8)  54.4 27. 1 16.5 1.3  5)  PmThAgTp+  16  P. . m e n z i e s i i 2• h e t e r o p h y l l a A. 3 r a n d i s T. p l i c a t a A. m a c r o p h y l l u m  26. 0 (17.5) 11. 7 (11.8) (8.4) 11. 9 (4. 1) 8. 4 0. 8 (1.5)  41.0 21.5 20.0 16.5 1.2  6)  ThTp+  27  T. T. P. A.  22. 8 (19.9) 15. 6 (16.7) 7. 2 (11.5) 1. 1 (1.7)  56. 5 29.3 10.9 1.8  heterophylla plicata sitchensis rubra  TAE1E 6 Forest  plot  types  See  o f t h e Wet D o u g l a s - f i r  Table  5 f o r explanations.  Subzone.  80  Flct  Type  N  Species (>1S B.A.)  mean E.A. (m /h)  (s)  2  mean E.A. (%)  1) Th+  25  T. h e t e r o p h y l l a A. r u b r a  52.1 0.5  (11.6) (1.3)  98.1 1.0  2)  FmTh  72  P. m e n z i e s i i T. h s t e r o p . i y l l a  24.6 18.6  (14.7) (17.3)  61.6 37.0  3)  PmThAr+  27  P. m e n z i e s i i !• heterophylla A. r u b r a A. a r a n d i s  21.3 17.1 4.2 1.1  (13.5) (15.8) (3.7) (2.0)  '50.8 35.1 10.3 3.2  4)  FmThTp  48  P. m e n z i e s j i T. h e t e r o p h y l l a 1. p l i c a t a  31.1 17.6 8.7  (18.9) (12.5) (6.0)  51.5 32.4 14.7  17  T.  heterophylla plicata rubra .grandis  37.2 10.6 0.5 0.8  (10.2) (7.5) (1.2) (3.2)  75.3 21.6 1.2 1.2  P. m e n z i e s i i A. r u b r a £• j a c r o p h y l l u r a heterophylla  30.7 1.7 0.7 0.4  (14.6) (4.5) (2.5) (0.6)  92.2 5.0 1.7 1.1  5) T h T p +  16)  Pm+  38  TABLE 7 Forest  plot  t y p e s o f t h e Dry Western See  Table  Hemlock  5 f o r explanations.  Subzone.  81  Plct  Type  N  Species (>1S B. A. )  1) Th  70  J.  2) T h F s +  56  3) ThAa  mean E.A. (tnz/h)  (s)  mean E.A. (%)  heterophylla  61.6  (12.2)  97.7  1.  heterophylla P. s i t c h e n s i s rubra  34.5 28.8 3.4  (17.7) (20.7) (6.8)  52.5 41.0 5.7  65  T. heterophylla amabilis  36.4 26.8  (21.4) (21.0)  '57.4 42.0  <0 T h T p +  16  T. ibgtg£o,p,hylla. plicata A. a m a b i l i s  28.5 21.2 6.1  (16.0) (23.7) (11.9)  57.7 31.4 10.5  5) ThPsTp+  32  e ro_ghy 11a T. s i t c hensis P. p l i c a ta !• A. r u b r a  23.7 21.8 12.4 4.9  (14.0) (19.4) (7.8) (4.9)  38.2 32.3 21.2 8.3  ThTpPin +  17  T.  heterophylla _gli.cat a P. m e n z i e s i i rubra  29.2 9.7 9.2 1.3  (13.2) (6.4) (7.8) (2.1)  58.1 20.8 17.2 3.6  40  I. P. P. T.  52. 1 (14.7) 16.4 (12.5) (3.0) 1.0 (1.0) 0.6  74.4 22.0 1.5 1.0  6)  7) ThPm +  h§tero£h_ylla menziesii sitchens is plicata  TABLE 8 Forest  plct  t y p e s o'f t h e Wet Western See  Table  Hemlock  5 f o r explanations.  Subzone.  82  Plot  Type  S  Species ( > U B.A.)  mean E.A. (tn2/h)  (s)  mean E.A. (%)  1) ThEs +  12  heterophylla P. s i t c h e n s i s P. m e n z i e s i i  60.9 11.1 1.6  (8.4) (7.9) (4.9)  83.2 14.3 1.9  2) ThTp +  7  T. i s t e r ojghy 1 l a 1. p l i c a t a P. s i t c h e n s i s !• rubra  40.8 16.8 2.9 1.1  (24.7) (15.2) (4.5) (2.8)  63.6 29.4 • 5.0 1.7  TABLE 9 Forest  plct  types See  o f t h e Fcg Western  Table  Hemlock  5 f o r explanations.  Subzone.  83 There i s one i m p o r t a n t comment t o make about t h i s method.  classification  The major s p e c i e s were used t o b u i l d i t s s k e l e t o n , s i n c e , by  d e f i n i t i o n , these species occur i n a l l o b s e r v a t i o n s .  To a v o i d an  i n f i n i t e number o f c l a s s e s , minor s p e c i e s were grouped, does n o t n e c e s s a r i l y o c c u r i n each o b s e r v a t i o n .  and each one  F o r example, i n t h e  Dry D o u g l a s - f i r Subzone (see T a b l e 5 ) , t h e name o f t h e second p l o t t y p e , Pm-v, i n d i c a t e s t h a t each o b s e r v a t i o n has t o c o n t a i n P_. m e n z i e s i i , and e i t h e r P_. c o n t o r t a o r A. r u b r a , o r b o t h .  This, unfortunately, inflates  t h e s t a n d a r d d e v i a t i o n o f t h e minor s p e c i e s i n T a b l e s 5 t o 9, b u t t h e advantage o f a l i m i t e d number o f c l a s s e s f a r outweighs  this  inconvenience  I n any c a s e , minor s p e c i e s account f o r , a t most, o n l y 5% o f t h e t o t a l basal area.  A n a l y s i s o f b a s a l a r e a growth  variation  There a r e f i v e s p e c i e s t h a t o c c u r i n more t h a n one p l o t type and i n a l l p l o t s i n each c a s e , w i t h i n one or more subzones:  P_. m e n z i e s i i ,  J_. h e t e r o p h y l l a , J_. p l i c a t a , P_. s i t c h e n s i s , and A. a m a b i l i s .  S i n c e they  a r e major s p e c i e s , i . e . they o c c u r i n a l l o b s e r v a t i o n s o f t h e p l o t types where t h e y a r e f o u n d , i t i s p o s s i b l e t o s t u d y t h e v a r i a t i o n o f t h e i r b a s a l a r e a growth among v a r i o u s p l o t types as d e s c r i b e d p r e v i o u s l y . D i f f e r e n t p l o t t y p e s a r e assumed t o r e p r e s e n t d i f f e r e n t c o m p e t i t i o n regimes.  S i n c e minor s p e c i e s do n o t occur i n a l l o b s e r v a t i o n s , a n a l y s i s  of v a r i a n c e can be performed do o c c u r .  o n l y on t h e s u b s e t o f p l o t s i n which  they  T h i s e x p l a i n s t h e d i s c r e p a n c i e s i n mean b a s a l a r e a f o r t h e s e  s p e c i e s between t h e s e t o f t a b l e s d e s c r i b i n g t h e p l o t types and t h e s e t o f t a b l e s o f anova r e s u l t s  (Tables 5 t o  (Tables 11, 13, 15, 17, and 1 9 ) .  84 A l l d a t a shown i n t h i s a n a l y s i s r e p r e s e n t means f o r a l l p l o t s o f a p l o t t y p e , o r o v e r a l l means when i n d i c a t e d .  The s t a n d age i s g i v e n i n  case i t might be c o r r e l a t e d w i t h growth v a r i a b l e s ; a p o s i t i v e w i t h growth increment  could o v e r r i d e the treatment  effect.  correlation  Site indices  are mentioned f o r P_. m e n z i e s i i and T. h e t e r o p h y l l a , wherever b o t h s p e c i e s o c c u r ; s i t e i n d e x i s used as a g e n e r a l i n d i c a t i o n o f s i t e p r o d u c t i v i t y and c o u l d a l s o o v e r r i d e t h e e f f e c t o f t h e t r e a t m e n t t h e f o r e s t i s immature, t h e f i v e - y e a r increment  (plot type).  i n b a s a l a r e a s h o u l d be  p r o p o r t i o n a l t o b a s a l a r e a , so a r a t i o o f t h e f i v e - y e a r increment b a s a l a r e a i s a l s o g i v e n (as a p e r c e n t a g e ) .  Since  over  This percent f i v e - y e a r i n -  crement i s t h e most c r i t i c a l v a r i a b l e , s i n c e i t i s independent o f t h e abundance o f t h e s p e c i e s , and i s r e a s o n a b l y l i n e a r over t h e p e r i o d o f time c o n s i d e r e d i n t h i s s t u d y .  A s i g n i f i c a n t d i f f e r e n c e i n t h e b a s a l area  i t s e l f among p l o t t y p e s would be i n d i c a t i v e o f t h e f i t n e s s o f t h e s p e c i e s to  each p l o t t y p e .  increment  F i n a l l y the r a t i o  ( i n percent) of the b a s a l area  o f a s p e c i e s (DBA) over t h e t o t a l b a s a l a r e a ( a l l s p e c i e s )  i n d i c a t e s a r a t e o f change o f a s p e c i e s over t h e whole community. The r e s u l t s o f t h i s a n a l y s i s a r e d i s c u s s e d s e p a r a t e l y f o r each subzone.  When t h e r e i s a s i g n i f i c a n t d i f f e r e n c e among t r e a t m e n t s  (plot  t y p e s ) , t h e extremes a r e g i v e n , o t h e r w i s e t h e o v e r a l l mean i s used.  Where  age a t t r i b u t e s v a r y s i g n i f i c a n t l y , t h e i r c o r r e l a t i o n w i t h b a s a l a r e a growth a t t r i b u t e s i s g i v e n , i f r e l e v a n t .  I t i s assumed t h a t s i g n i f i c a n t  d i f f e r e n c e s i n growth a t t r i b u t e s a r e due t o t r e a t m e n t s , i . e . d i f f e r e n c e i n c o m p e t i t i o n r e g i m e s , o n l y when t h e r e i s no s i g n i f i c a n t d i f f e r e n c e i n age a t t r i b u t e s o r no growth a t t r i b u t e s .  s i g n i f i c a n t c o r r e l a t i o n between age a t t r i b u t e s and  85 S i n c e minor s p e c i e s occur on fewer p l o t types t h a n major s p e c i e s , and  i n fewer o b s e r v a t i o n s , v e r y few s i g n i f i c a n t d i f f e r e n c e s among p l o t  types were found f o r e i t h e r t h e i r age a t t r i b u t e s o r growth a t t r i b u t e s . For minor s p e c i e s , o n l y r e s u l t s w i t h some r e l e v a n c e t o s u c c e s s i o n  will  be d i s c u s s e d . Dry D o u g l a s - f i r Subzone  Major s p e c i e s  (Table 10)  Four p l o t t y p e s c o n s t i t u t e t h i s subzone, and P_.' m e n z i e s i i i n a l l o f them (Table 5 and 1 0 ) .  occurs  Stand age ranges from 46.0 t o 57.9  y e a r s , and P_. m e n z i e s i i s i t e index has an o v e r a l l mean o f 25.9 m.  The  f i v e - y e a r b a s a l a r e a increment o f P_. m e n z i e s i i shows no s i g n i f i c a n t d i f f e r e n c e among p l o t t y p e s , i t s b a s a l a r e a shows a s i g n i f i c a n t  diffe-  r e n c e (23.4 - 41.6 m /h); and t h e r a t i o s o f these two v a r i a b l e s v a r y 2  s i g n i f i c a n t l y from 6.4% t o 14.6%. significant correlation  (p =  The p e r c e n t r a t e o f i n c r e a s e shows no  0.05) w i t h age or w i t h b a s a l a r e a .  Assuming  t h a t t h e d i f f e r e n c e i s due t o t h e c o m p e t i t i o n r e g i m e , t h e d a t a show t h a t the r a t e o f i n c r e a s e types  (DBA) o f P_. m e n z i e s i i i s t h e s m a l l e s t i n t h e p l o t  (Pm, PmTpt) where P_. m e n z i e s i i i s t h e most abundant s p e c i e s , and t h e  g r e a t e s t i n the p l o t types decrease.  (Pm+, PmTpTh+) where A. r u b r a shows i t h i g h e s t  T h i s s u g g e s t s t h a t P_. m e n z i e s i i growth i s f a v o u r e d by t h e  opening o f t h e f o r e s t when t h e m o r t a l i t y o f A. r u b r a becomes h i g h , 40 o r 50 y e a r s .  after  As P_. m e n z i e s i i t a k e s over A. r u b r a , P_. c o n t o r t a and  J_. p l i c a t a i n c r e a s e c o n c u r r e n t l y , thus p r e v e n t i n g P_. m e n z i e s i i from b e i n g the a b s o l u t e dominant, except i n t h e Pm p l o t t y p e .  86  Plot  Type  Stand Age (years)  Pm SI 50 (m)  Th Total DBA/ S I 50 DBA BA DBA/BA BA T o t BA (m) (m /h/5y) (mz/h) (%/5y) (mZ/h) (%/5y) 2  P. m e n z i e s i i Pm Pm + PmTp + PmTpTh+  46. C 50. 0 50. 9 57. 9  26.6 24. 8 26. 0 24.4  Overall  48. 6  25. 9  F-ratic  3.1  **  0.9 NS  PmTp + D 2) PmTpTh+  50. 9 57. 9  26. 0 24.4  Overall  52. 5  25. 6  F-ratic  1.4 NS  0.5 NS  1) 2) 3) «*)  J>  -  -  —  -  2.0 3.6 1.8 3.7  4 1,6 23., 4 2 3, -3 32. 4  6.4 14.6 8.1 12.7  41.9 35. 8 30. 6 49.7  6.3 10.4 6.5 8.8  2.5  32. 9  9.3  38. 6  7.6  0.7 NS  26. 6  2.6  9.5  ***  0.8 NS  1.2 2.8  3. 7 10. 8  53.6 29. 1  30. 6 49.7  4.4 5.9  1.6  5. 4  47.9  35. 0  4.7  9.0  15. 2  ** *  *  plicata  —  —  -  ***  TABLE  10  ***  1• 5 NS  One-way analysis o f v a r i a n c e o f t h e major s p e c i e s d i f f e r e n t p l o t t y p e s o f t h e Cry D o u g l a s - f i r Subzone.  9. 4  ***  0.7 NS  across  Data r e p r e s e n t means f o r a l l o b s e r v a t i o n s o f a particular plot type. C h a r a c t e r i s t i c s o f plot types are given i n Table 5. Fm = P. m e n z i e s i i . Th = T. h e t e r o p h y l l a . «SI 50' - s i t e i n d e x a t base age 50. 'DBA = D e l t a BA = first difference i n b a s a l a r e a between two o b s e r v a t i o n s a t 5 y e a r s i n t e r v a l . 'BA' •= b a s a l area of t h e s u b j e c t s p e c i e s . ' T o t a l EA* = t o t a l b a s a l area of a l l the s p e c i e s i n each o b s e r v a t i o n . 1  P r o b a b i l i t y l e v e l s a r e as f o l l o w s : * = p<0.10, ** = p<0.05, *** - p<o.01, NS = n o t s i g n i f i c a n t .  87 J_. p l i c a t a o c c u r s  i n two p l o t types where s t a n d age averages  52.5 y e a r s , and g_. m e n z i e s i i s i t e i n d e x , 25.6 m. varies significantly area  The f i v e - y e a r increment  (1.2 - 2.8 m /h/5y), but i s p r o p o r t i o n a l t o b a s a l 2  (3.7 - 10.8 m / h ) , and t h e i r r a t i o s 2  a r e not s i g n i f i c a n t l y  The v e r y h i g h r a t e o f i n c r e a s e o f T. p l i c a t a  (47.9%/5y) i n d i c a t e s a  g r a d u a l s u c c e s s i o n o f T. p l i e a t a over P_. m e n z i e s i i , r e s u l t i n g s i t i o n from t h e Pm p l o t t y p e t o PmTp+. i n the stand-type graphs o f  different.  i n a tran-  The same c o n c l u s i o n was r e a c h e d  succession data presented  i n the previous chapter.  The  s p e c i e s r e l a t i v e abundance a c r o s s age (see F i g u r e s 6 A and B)  show i n f a c t t h a t J_. p l i c a t a i n c r e a s e s a t t h e d e t r i m e n t  o f P_. m e n z i e s i i .  In some s t a n d s , t h e t r a n s i t i o n goes from Pm t o Pm+ where P_. c o n t o r t a may r e a c h a r e l a t i v e abundance o f 20%. the s u c c e s s i o n d a t a  t h i s t r e n d i s a l s o i n agreement w i t h  ( p r e v i o u s c h a p t e r ) , and w i t h t h e graph o f s p e c i e s  r e l a t i v e abundance a c r o s s age ( F i g u r e s 6 A and B ) .  Minor species  (Table  11)  A. r u b r a shows a s i g n i f i c a n t d i f f e r e n c e i n r a t e o f i n c r e a s e over t o t a l basal area p = 0.1).  (-0.5 - 1.6%/5y) c o r r e l a t e d w i t h s t a n d age ( r =-0.98,  This f a l l i n the r e l a t i v e basal area r a t e of increase  t h e p i o n e e r r o l e o f A. r u b r a i n t h e community. l a t i v e t o t h e community becomes n e g a t i v e  confirms  I t s rate of increase r e -  (-0.5%/5y) i n PmTpt, where P_.  m e n z i e s i i a t t a i n s 6.5%/5y and T. p l i c a t a , 4.4%/5y.  P_. c o n t o r t a i s found  more a b u n d a n t l y i n t h e p l o t type w i t h o u t J_. p l i c a t a  (Pm+) t h a n i n t h e one  with t h i s species  b a s i c requirements f o r  (PmTpt).  T h i s suggests d i f f e r e n t  t h e s e s p e c i e s , and K r a j i n a (1969) p o i n t s out t h a t T. p l i c a t a p r e f e r s e u t r o p h i c s o i l s and h y g r i c c o n d i t i o n s , whereas P_. c o n t o r t a cannot t o l e r a t e  88  Plct  Type  Stand Age (years)  Pm SI 50 (m)  Th S I 50 DBA BA (m) (m2/h/5y) (m2/h)  Total DBA/BA BA <%/5y) (mZ/h)  DBA/ T o t BA (%/5y)  1.6 -0.5 0.3  A.  rubra  1) 2) 3)  Pm + FmTp+ PmTpTh+  46. C 61. 1 57. 9  26. 8 29. 5 24, 4  -  0.4 -0. 1 0.2  7.6 3. 4 1.6  -5.1 -2.7 -6.6  34.7 37.8 49. 7  G verc.ll  52. 3  27. 0  -  0.2  5. 3  -4.8  38.5  ***  5. 7  1.8 NS  2.5  2. 9  *  0.0 NS  3.7  2.7  0.6 -0. 1  14. 8 4. 2  7. 4 1.8  36. 8 50. 1  1.4 -0.1  0.4  12. 8  6.3  39.3  .1.1  1.2 NS  2.5 NS  0.5 NS  7. C  1.0 NS  -0. 1 -0.9  1. 2 4.8  1.2 -9.5  36. S 49.7  -0. 1 -0.8  -0.4  2. 4  -2.6  41.4  -0.3  F-ratio  £.  contorta  D 2)  Pm + PmTp +  55. 0 68. 8  21.9 30. 5  Overall  57. 6  23. 5  F-ratio  3. 6  8.4  I'. D 2)  *  ***  PmTp + PmIpTh+  55. 0 57. 9  27. 7 24. 4  Overall  56. 0  26. 5  F-ratio  0. 2 NS  1.9 NS  —  —  —  —  *  **  0.8  *  **  t e ro_phy 1 l a  —  -  -  1. 1 NS  27. 0  ** *  0.3 NS  3. 3  *  TABLE 11 Cne-way a n a l y s i s o f v a r i a n c e o f t h e minor species d i f f e r e n t p l c t t y p e s o f t h e Dry D o u g l a s - f i r Subzone.  across  Data represent means f o r a l l occurrences of the subject species i n a given p l c t type. C h a r a c t e r i s t i c s of plot types a r e g i v e n i n T a b l e 5. F o r a b b r e v i a t i o n s , s e e T a b l e 10.  0.4 NS  89 e u t r o p h i c s o i l s and r e q u i r e s d r i e r c o n d i t i o n s . as a minor s p e c i e s h e r e a l t h o u g h type.  J_. h e t e r o p h y l l a i s a n a l y s e d  i t i s a major one i n t h e PmTpTh* p l o t  No s i g n i f i c a n t d i f f e r e n c e s were found between t h e two p l o t t y p e s ,  except,  o f c o u r s e , t h a t J_. h e t e r o p h y l l a i s more abundant i n t h e p l o t  t y p e where i t i s a major s p e c i e s .  F i g u r e s 6 A and B show a d e c r e a s i n g  p r o p o r t i o n o f .A. r u b r a b a s a l a r e a , p r e v i o u s l y observed i n t h e s u c c e s s i o n d a t a , and a low and s t a b l e r e l a t i v e abundance o f F_. c o n t o r t a and J_. heterophylla.  Wet D o u g l a s - f i r Subzone Major s p e c i e s  (Table 12)  P_. m e n z i e s i i i s found i n 5 out o f 6 p l o t types w i t h i n which age r a n g e s from 40.9 t o 71.3 y e a r s , P_. m e n z i e s i i s i t e i n d e x 26.7  stand  averages  m., and J_. h e t e r o p h y l l a s i t e i n d e x v a r i e s from 18.3 t o 27.4 m.  The  f i v e - y e a r b a s a l a r e a increment has an o v e r a l l mean o f 2.3 m /h/5y, b a s a l 2  a r e a ranges from 26.0 t o 36.5 m /h, and t h e r a t e o f i n c r e a s e shows no 2  s i g n i f i c a n t d i f f e r e n c e among p l o t t y p e s , w i t h an o v e r a l l mean o f 10.6%/5y. In a d d i t i o n , t h e r a t e o f b a s a l a r e a i n c r e a s e as a r a t i o o f t h e whole community shows no s i g n i f i c a n t d i f f e r e n c e .  The s i t u a t i o n i s s i m i l a r f o r  T. h e t e r o p h y l l a , b u t h e r e b a s a l area increment shows a s i g n i f i c a n t ence (0.02 - 2.5 m /h/5y) as w e l l as t h e b a s a l a r e a 2  differ-  (8.3 - 22.8 m / h ) , y e t 2  t h e i r r a t i o i s n o t s i g n i f i c a n t l y d i f f e r e n t and has an o v e r a l l mean o f 5.9%/5y.  On t h e o t h e r hand, t h e r a t i o o f b a s a l a r e a increment over t o t a l  b a s a l a r e a i s s i g n i f i c a n t and J_. h e t e r o p h y l l a r e a c h e s t h e h i g h e s t  rate  of i n c r e a s e i n t h e ThTp/- p l o t t y p e , t h e o n l y one where t h e r e i s no P_. menz i e s i i . suggesting  mutual s i t e i n c o m p a t i b i l i t y .  90  Stand Age (years)  Pm SI 50  menziesii Pm + PmTh + PmTp + PmThTp+ PmThAgTp+  46. 0 40.9 57. 0 61. 1 71. 3  26. 6 27.5 25. 2 26. 2 29.5  23.9  1 8. 3 22. 4 27.4  2. 5 2.4 2.6 1. 7 1.9  36. 5 26.7 28. 4 26. 8 26. 0  9.1 13.5 10.5 10.7 . 9.4  38. 4 37. 1 42. 4 48. 8 59. 1  8.4 8.8 7.3 4.8 3.3  Overall  51. 1  26. 7  23. 4  2. 3  30. 8  10.6  42. 1  7.3  F-ratio  16.9  ***  1.9 NS  ***  4.2  0. 5 NS  ***  8. 6  0.8 NS  11.8  ***  1.6 NS  40. 9 61. 1 71.3 55. 6  27. 5 26. 2 29. 5 21.3  23. 9 22. 4 27. 4 22.9  0.6 0.02 0. 5 2.5  8. 3 12. 6 11.7 22. 8  7.2 3.2 1.5 11.9  37. 1 48.8 59. 1 47. 2  2. 2 1.1 1.0 8. 1  Overall  54. 0  27. 1  23. 4  0.7  12. 7  5.9  45.4  2.7  F-ratio  12. 9  ***  1.5 NS  2. 6  6.3  7. 8  ***  0.6 NS  8. 2  7.6  57. 0 61.1 71.3 55. 6  25. 2 26. 2 29.5 21.3  18.3 22. 4 27.4 22.9  1.5 1.2 1.3 1.4  6.6 8. 3 8. 4 15. 6  40.0 22. 8 15.9 10.9  42. 4 48. 8 59. 1 47. 2  3.6 3.3 2.5 3.1  Overall  60. 1  26. 3  23. 1  1.3  9. 2  24. 4  48. 0  3.3  F-ratic  2. 1 NS  2.0 NS  3.4  **  0.2 NS  4. 9  3.3  3. 1  0.2 NS  TABLE  12  Plct  P. 1) 2) 3) <0 5)  1-  Type  (ID)  Tctal DEA/ Th DBA EA DBA/BA BA T o t BA s i 5«: (%/5y) (m) (m2/h/5y) (mz/h) (%/5y) (m /h) 2  heterc£hxlla  1) PmTh + 2) PmThTp+ 3) PmTh AgTp + 4) ThTp +  *  ***  ** *  ***  2. . p l i c a t a PmTp + D 2) PmThTp+ 3) PmThAgTp+ 4) ThTp +  ** *  **  **  One-way a n a l y s i s o f v a r i a n c e o f t h e m a j c r species across d i f f e r e n t p l o t t y p e s o f t h e Wet D o u g l a s - f i r Subzone. Data represent means f o r a l l o b s e r v a t i o n s o f a p a r t i c u l a r p l c t type. C h a r a c t e r i s t i c s of plot types are given i n Table 6. F o r a b b r e v i a t i o n s , s e e T a b l e 10.  J_. p l i c a t a has a v e r y s i g n i f i c a n t d i f f e r e n c e i n r a t e o f growth among p l o t t y p e s , from 10.9 t o 40.0%/5Y.  I t s lowest r a t e o f i n c r e a s e i s  i n t h e ThTp* p l o t t y p e , e x a c t l y where T. h e t e r o p h y l l a e x h i b i t s i t s h i g h e s t r a t e of increase.  The h i g h e s t r a t e o f i n c r e a s e f o r J_. p l i c a t a  appears  i n t h e PmTp+ p l o t t y p e , where P_. m e n z i e s i i i s t h e most abundant among a l l p l o t types i n w h i c h t h e s e two s p e c i e s r o p h y l l a i s p r a c t i c a l l y absent.  c o e x i s t , and i n which J_. h e t e -  Moreover, t h e r e i s a s i g n i f i c a n t  corre-  l a t i o n o f 0.99 (p = 0.05) between t h e r a t e o f i n c r e a s e o f J_. p l i c a t a and t h e r e l a t i v e abundance (% BA, T a b l e 6 ) , o f P_. m e n z i e s i i i n t h e 3 p l o t types where t h e s e s p e c i e s  c o - o c c u r (PmTpt, PmThTp+, PmThAgTp+), and t h e  r a t e o f i n c r e a s e i s c o n s i s t e n t l y 2 t o 4 times h i g h e r f o r J_. p l i c a t a than f o r P_. m e n z i e s i i . favour  These o b s e r v a t i o n s  i n d i c a t e t h a t t h e c o n d i t i o n s which  P_. m e n z i e s i i do n o t f a v o u r J_. h e t e r o p h y l l a , and t h a t J_. p l i c a t a has  some p o t e n t i a l t o succeed P_. m e n z i e s i i , a t l e a s t l o c a l l y , where J_. h e t e r o phylla  i s infrequent.  T h i s can a l s o be observed i n t h e graph o f t h e  s p e c i e s r e l a t i v e abundance (see F i g u r e s r e v e a l e d by t h e s u c c e s s i o n  6 C and D ) , and t h i s t r e n d was  data of the previous  chapter.  Minor S p e c i e s (Table 13) No s i g n i f i c a n t d i f f e r e n c e s were found i n r a t e s o f i n c r e a s e o f minor species.  A. r u b r a d e s e r v e s a comment.  The s t a n d  age v a r i e s g r e a t l y among  p l o t t y p e s , and i s n e g a t i v e l y c o r r e l a t e d w i t h t h e r a t e o f i n c r e a s e i n b a s a l a r e a ( r = -0.92, p = 0.1). A l t h o u g h t h e d i f f e r e n c e i n r a t e o f i n c r e a s e i n b a s a l a r e a i s n o t s i g n i f i c a n t , i t i s noteworthy t h a t i t shows s u c c e s s i v e l y an i n c r e a s e time.  (5.6%/5Y) and t h e n a d e c r e a s e (-6.4%/5Y) w i t h  This suggests t h a t the pioneer  r o l e o f A. r u b r a observed i n t h e  92  Pm S I 50 (m)  Th Total S I 50 DBA BA DBA/BA BA (m) (m^/h/Sy) (m /h) (%/5y) {m2/h)  DBA/ T o t BA (%/5y)  42.4 38. 6 70. 8 79. 2  28.6 31. 4 29. 1  - i 29. 0 18. 3 20. 3  -0.05 0.5 -0.4 -0.2  4. 6 6. 9 4. 1 2. 5  6.2 5. 6 -10. 7 -6.4  0.4 1.4 -0.6 -0.5  Overall  53. 5  29. 4  22.5  -0.02  4. 6  0.7  45. 3.  0.3  F-ratic  23. 1  1.2 NS  7.0  ***  1.4 NS  1.9 NS  1.4 NS  7. 5  ** *  2.1 NS  PmTp + ThTp +  77. 5 83. 6  28. 2  18. 3 20. 0  3. 2 1.7  25. 0 17. 7  12.2 6.7  67. 9 60.0  4.4 2.4  Overall  82. 0  28. 2  19.6  2.1  19. 6  8.2  62. 1  3.0  F-ratio  0. 9 NS  1.0 NS  1.0 NS  0.7 NS  0. 6 NS  0.9 NS  Plct  A.  Type  Stand Age (years)  2  rubra  1) Pm* 2) PmTh + 3) PmTp + 4) ThTp +  ***  —  39.4 40. 3 49. 5 60.8  P. s i t c h e n s i s D 2)  —  —  0. 3 NS  A. g r a n d i s D 2)  1  of  -  PmTp + PmThAgTp+  65. 0 71. 3  31.0 2S.5  27.4  0.7 1.1  11. 5 11. 9  7.8 14.2  51.8 59. 1  1.2 2. 1  Overall  69. 5  29. 9  27. 4  1.0  11. 8  12.5  57. 1  1.8  F-ratio  0. 5 NS  0. 3 NS  -  1.4 NS  1.6 NS  1.7 NS  M i s s i n g v a l u e s f o r F i r o r Hemlock the species i n the plot type.  T a b l e 13...  Site  0. 0 NS  1.4 NS  I n d e x a r e due t o t h e a b s e n c e  93 (Cont'd)  Plot  Type  Stand Age (years)  Pm S I 50 (m)  Th Total DBA/ S I 50 DBA EA DBA/BA BA T o t BA (m) <mVh/5y) (m^/h) (%/5y) (ra^/h) (%/5y)  A.  macrophyllum  1) 2) 3)  PmTp + PmTpTh+ PmThAgTp+  65. 6 69. 1 67.5  29.7 25. 8 33. 5  23.7 36.6  0.4 0. 1 0.2  5.0 4. 7 3.0  10.0 29.0 7.9  49.4 48.2 58. 5  0.8 0.5 0.4  Overall  67. 6  28. 5  26.0  0.2  4.5  18.7  50. 4  0.6  22. 7  0.8 NS  0. 2 NS  0. 4 NS  0.6 NS  F-ratio  0. 1 NS  3.9  **  -  ***  TABU  0.8 NS  13  One-way a n a l y s i s o f v a r i a n c e o f t h e minor species across d i f f e r e n t p l o t t y p e s o f t h e Het D o u g l a s - f i r Subzone. Data represent means f o r a l l occurrences of the subject species i n a given plot type. C h a r a c t e r i s t i c s of p l o t types a r e g i v e n i n T a b l e 6. F o r a b b r e v i a t i o n s , s e e T a b l e 10.  94 Dry D o u g l a s - f i r Subzone i s s i m i l a r i n the Wet  D o u g l a s - f i r Subzone.  The  graph of s p e c i e s r e l a t i v e abundance agrees w e l l w i t h t h i s view  (Figures  6 C and D), and  P_. s i t c h e n -  the s u c c e s s i o n  d a t a showed the same b e h a v i o u r .  s i s , A. g r a n d i s , and A. macrophyllum do not show s i g n i f i c a n t d i f f e r e n c e i n any of t h e growth v a r i a b l e s .  Dry Western Hemlock Subzone Major s p e c i e s  (Table  14)  J_. h e t e r o p h y l l a i s the most i m p o r t a n t s p e c i e s o c c u r s i n 5 out of 6 p l o t t y p e s . z i e s i i s i t e i n d e x (26.3 28.0  m)  - 39.6  m),  Stand age  m /h/5y) and b a s a l a r e a (17.1  and  are c o r r e l a t e d ( r - 0.94,  2  - 67.6  y ) , P_. men-  - 52.1  age,  m /h) 2  also vary  or s i t e i n d e x .  The  significantly, shows any  signi-  p e r c e n t r a t e of  i n c r e a s e i s h i g h l y s i g n i f i c a n t l y d i f f e r e n t among p l o t t y p e s , w i t h highest values  -  B a s a l a r e a increment (0.9 -  p = 0.05), y e t n e i t h e r one  f i c a n t c o r r e l a t i o n w i t h stand  and  and J_. h e t e r o p h y l l a s i t e i n d e x (24.3  are a l l s i g n i f i c a n t l y d i f f e r e n t .  4.3  (37.8  i n t h i s subzone  the  i n the two p l o t t y p e s where J_. p l i c a t a i s absent and  F_.  m e n z i e s i i p r e s e n t (PmTh, PrnThArf) , and the s m a l l e s t v a l u e s where J_. het e r o p h y l l a i s e i t h e r f o r m i n g p u r e s t a n d s (Th*) abundant (PmThTp, ThTp*). much c o m p e t i t i o n  of where T. p l i c a t a i s  T h i s i n d i c a t e s t h a t P_. m e n z i e s i i does not o f f e r  t o J_. h e t e r o p h y l l a , and t h a t J_. h e t e r o p h y l l a and T.  c a t a compete s t r o n g l y w i t h T_.  pli-  heterophylla.  A l l v a r i a b l e s f o r F_. m e n z i e s i i are s i g n i f i c a n t l y d i f f e r e n t among p l o t types.  The mean s t a n d  age goes from 33.2  t o 67.6  area increment i s n e g a t i v e l y c o r r e l a t e d w i t h stand  age  years.  The  basal  (r =-0.96, p =  0.05)  95  Plct  Type  Stand Age (years)  Pm SI 50 (m)  Th SI 50 DBA EA (m) (mZ/h/Sy) (m /h)  Tctal DBA/ DBA/BA BA T o t BA (%/5y) (a^/h) (%/5y)  56. C 45. 4 37. 8 67.6 49. 7  39.6 30. 6 32. 1 26.3 27. 4  27. 4 25.5 28.0 24. 3 26.9  4. 3 2. 2 1.2 0. 9 3.0  52. 1 18. 6 17. 1 17. 6 37. 2  9.1 21. 9 14.9 6.2 9.3  53. 1 43. 9 44. 2 56. 2 . 4*9.4  8.9 6.4 4.0 2.2 6.8  51.7  29.6  2 6.0  2. 1  24. 2  14.1  49. 3  5.3  9.6  6.9  2. 9  ***  ***  **  32. 2  6.8  5. 0  5.4  2  1 • JlSie rp^hy 11a 1) Th + 2) PmTh 3) PmThAr+ <*) PmThTp 5) ThTp + Overall F-ratio  11.2  ***  ** *  ***  ***  P. m e n z i e s i i D  2) 3)  PmTh PmThAr+ PmThTp Pm +  45. 4 37. 8 67. 6 33. 2  30. 32. 26. 27.  Overall  47.5  29.0  F-ratio  18.8  10.0  ***  6 1 3 2  ** *  25. 5 28. 0 24. 3  3.3 3.6 1.2 5. 2  24. 6 21.3 31. 1 30. 7  20.1 21.3 7.3 22.3  43. 9 44.2 58. 2 33. 5  13.2 11.2 2.6 20.9  25.5  3.2  27. 1  17.4  45.5  11.7  6. 5  3. 5  7. 4  12. 0  15.1  12. 1 9.5  58. 2 49. 4  1. 8 2.2  11.4  55. 9  1.9  0.3 NS  4. 1  0.3 NS  3. 7  **  ***  **  * **  ** *  ***  T . jilicata D  2)  PmThTp ThTp +  67. 6 49. 7  26.3 27. 4  24. 3 26. 9  0.8 1.0  8. 7 10. 6  Overall  62. 9  26.3' ,  25. 2  0.8  9. 2  8.7  0.0 NS  0.3 NS  1. 2 NS  F-ratio  ***  0. 2 NS  TABIE  **  14  One-way a n a l y s i s o f v a r i a n c e o f t h e rcajcr species across d i f f e r e n t p l o t t y p e s c f t h e Dry W e s t e r n Hemlock S u t z o n e . Data represent means f o r a l l o b s e r v a t i o n s o f a p a r t i c u l a r p l c t type. C h a r a c t e r i s t i c s o f p l o t types a r e g i v e n i n Table 7. F o r a b r e v i a t i o n s , see T a b l e 10.  96 and shows i t s l o w e s t v a l u e (1.2 m /h/5y) i n t h e o l d e s t p l o t type (PmTh 2  Tp).  The p e r c e n t r a t e o f i n c r e a s e i s a l s o the lowest i n the o l d e s t  p l o t type.  However, t h i s p l o t t y p e  (PmThTp) i s a l s o the o n l y P_. men-  z i e s i i p l o t t y p e w i t h a l a r g e p r o p o r t i o n of T_. p l i c a t a J_. p l i c a t a i s a t i t s b e s t r a t e o f i n c r e a s e (12.1%/5y).  (14.7%), I t seems  and apparent  i n the o l d e r p l o t s t h a t the c o n d i t i o n s f a v o u r a r a p i d b a s a l a r e a growth f o r J_. p l i c a t a r e f l e c t i n g b o t h a l a r g e diameter  increment  and good rege-  n e r a t i o n o f t h i s s p e c i e s , w h i l e P_. m e n z i e s i i grows much slower than i n other p l o t types.  The  consequences can be seen on the graph of s p e c i e s  r e l a t i v e abundance f o r t h e Dry Western Hemlock Subzone ( F i g u r e s 6 E  and  F). M i n o r s p e c i e s (Table  15)  A. r u b r a and A_. g r a n d i s are minor s p e c i e s i n the Dry Western Hemlock Subzone (Table 15).  Both b a s a l a r e a and b a s a l a r e a  over b a s a l a r e a are s i g n i f i c a n t l y d i f f e r e n t f o r A. r u b r a .  increment Even though  s t a n d age i s not s i g n i f i c a n t l y d i f f e r e n t among p l o t t y p e s , t h e r e i s a s i g n i f i c a n t n e g a t i v e c o r r e l a t i o n between s t a n d age and b a s a l a r e a (r =-0.97, p = 0.05).  Moreover, t h e two o l d e s t p l o t types show a v e r y  h i g h m o r t a l i t y f o r A. r u b r a i n d i c a t e d by a r a t e o f i n c r e a s e o f -31.6%/5Y i n t h e Th* p l o t t y p e , and -73.4%/5y i n t h e PmTpt. the p i o n e e r behaviour  This again r e f l e c t s  o f A. r u b r a whose r e l a t i v e abundance i s d e c r e a s i n g  c o n s t a n t l y when p l o t t e d a g a i n s t age  ( F i g u r e s 6 E and F ) , as p r e v i o u s l y  shown i n the s t a n d - t y p e s u c c e s s i o n d a t a .  A. g r a n d i s covers a v e r y s m a l l  b a s a l a r e a i n the PmThArt p l o t t y p e  2  (2.5 m / h ) , and s l i g h t l y more i n  PmTp+ (6.6 m /h); t h i s d i f f e r e n c e i s not 2  significant.  97  P l o t Tyre  A.  Stand Age (years)  Fro SI 50 (m)  Th SI 50 DBA BA (m) (m2/h/5y) {m2/h)  Total DBA/ DBA/BA BA Tot BA (%/5y) (mz/h) (%/5y)  rubra  D  Th + 2) PmThAr+ 3) T h T p + 4) Pm + Overall F-ratio  —  50. 0 38, 3 51.3 24. 0  32.3 27. 4 33.5  39.0  32.4  29. 7 28.0 26. 7  -0. 8 -0.1 -1.0 0.6  3. 0 4. 9 2. 1 12. 9  -31.6 4.9 -73. 4 4.0  55. 3 44. 1 46.7 34. 5  28.0  -0.2  5.5  -8.0  44.3  -  -1.7 0.8 -2.4 1.9 0.3  1.9 NS  1.0 NS  0.5 NS  0.9 NS  12. 1 ** *  6.8 ***  PmThAr+ PmTp +  49. 2 50. 0  29. 1 —  27.8 30. 5  0.5 0.7  2. 5 6. 6  14.6 5. 3  49.2 61.6  2.0 1.1  Overall  49. 3  29. 1  28. 3  0.5  3.0  13.3  51. 0  1.8  F-ratic  0. 0 NS  0.7 ***  0. 1 NS  2. 4 NS  0.6 NS  0.2 NS  1. 4 NS  1.5 NS  A . grandis  D  2)  —  -  0.4 NS  TAEIE 15 One-vay a n a l y s i s of v a r i a n c e of the minor species acrcss d i f f e r e n t p l o t types of the Dry Western Hemlock Subzone. Data represent means f o r a l l o c c u r r e n c e s of the s u b j e c t s p e c i e s i n a given p l c t type. C h a r a c t e r i s t i c s of p l o t types are given i n Table 7. For a b b r e v i a t i o n s , see Table 10.  98 Wet Western Hemlock Subzone Major s p e c i e s  (Table 16)  T_. h e t e r o p h y l l a i s found i n a l l o f t h e 7 p l o t t y p e s , and accounts f o r w e l l over h a l f t h e t o t a l b a s a l a r e a , except o n l y 38.2% (Table 8 ) .  i n ThPsTp* where i t i s  The stand age v a r i e s from 42.8 t o 60.6 y e a r s , and  the T. h e t e r o p h y l l a s i t e i n d e x , from 21.5 t o 29.9 m. worth mentioning  The o n l y  correlation  i n d i c a t e s a slowly d i m i n i s h i n g percent r a t e of increase  w i t h s t a n d age ( r = -0.70, p - . 0 . 1 ) .  T. h e t e r o p h y l l a b a s a l a r e a  increment  as a r a t i o o f t o t a l b a s a l a r e a has an o v e r a l l mean o f 4.8%/5y, b u t as a r a t i o o f J_. h e t e r o p h y l l a b a s a l a r e a , i t v a r i e s among p l o t t y p e s .  I t has  i t s h i g h e s t r a t e o f i n c r e a s e (13.7%/5y) i n t h e ThPst p l o t t y p e , where P_. s i t c h e n s i s a l s o r e a c h e s i t s h i g h e s t v a l u e .  This high r a t e of increase  f o r b o t h s p e c i e s i s p r o b a b l y due t o t h e youth o f t h i s p l o t t y p e , and t o h i g h f i t n e s s t o s i t e c o n d i t i o n s , b u t i t might a l s o r e v e a l a l a c k o f i n t e n s e c o m p e t i t i o n between J_. h e t e r o p h y l l a and P_. s i t c h e n s i s .  Among  5 p l o t t y p e s , Th, ThAa, ThTpt, ThPsTpt, and ThTpPm+, t h e r a t e o f i n c r e a s e o f T. h e t e r o p h y l l a i s v e r y s t a b l e ( c i r c a 7.5%/5y), t h e lowest r a t e o f i n c r e a s e (3.5%/5y) i s found i n t h e ThPm+ p l o t t y p e , where P_. m e n z i e s i i i s t h e most abundant.  T h i s i n d i c a t e s e i t h e r mutual s i t e  incompatibility  or s t r o n g c o m p e t i t i o n between t h e s e two s p e c i e s , and t h i s h y p o t h e s i s i s r e i n f o r c e d by t h e o b s e r v a t i o n t h a t P_. m e n z i e s i i shows i t s lowest r a t e o f i n c r e a s e (3.0%/5y) i n t h i s same p l o t t y p e , and i t s h i g h e s t  (14.2%/5y) i n  the ThTpPm+, where J_. h e t e r o p h y l l a i s s i g n i f i c a n t l y l e s s abundant (see Table 8 ) .  99  P l c t Type  Stand Pm Age SI 50 (years) (m)  Th Total DBA, SI 50 DBA BA DBA/BA BA Tot ] (m) (m2/h/5y) (m^/h) (%/5y) (m2/h) <%/5  heterophylla 1) 2) 3) <0 5) 6) 7)  Th ThPs + ThAa ThTp + ThPsTp+ ThTpPm+ ThEm +  54.6 42., 8 57. 1 60. 6 43. 3 47.6 59. 3  Overall  52. 2  •-  —  -  -  —  29.0 28. 3 26. 5 21.5 26. 1 29.9 29. 8  3.2 3.0 2.7 1.3 1.6 1.6 1.6  61.6 34. 5 36. 4 28. 5 23. 6 29. 2 52. 1  6.1 13.7 7.3 7.9 8.6 7.4 3.5  63. 0 67. 2 63.5 56. C 62. 9 49.4 70.8  6.0 6.4 5.0 3.6 2.7 4.4 2.2  27.7  2.5  41. 9  7.9  63. 8  4.8  7.3  2.0  32.4  2.6  ***  3. 6  1.7 NS  0.8 1.7 0.6  21.2 12. 4 9. 7  10.5 12.4 2.6  56. 0 62. 8 49.5  2.3 3.3 1.4  1.2  13. 8  9.4  57. 7  2.6  3.6  3. 5  3.5  6.2  —  ***  -  60. 6 43. 3 47. 6  —  -—  21.5 26. 1 29. 9  Overall  48.7  -  26.0  F-ratio  5.4  —  F-ratic  ***  *  ***  **  £• £licata  D  ThTp + 2) ThPsTp+ 3) ThTpPm +  £•  ***  .-  8. 6  ***  **  **  **  2. 1 NS  1.5 NS  menziesii  ThTpPm+ 2) ThPm +  47.6 59. 3  -—  29.9 29.8  1. 1 0.5  9.2 16.4  14.2 3.0  49.5 70.7  2.2 0.7  Overall  55. 8  -  29.8  0.6  14. 2  6.4  64. 4  1.2  F-ratic  3.5  -  0.0 NS  1.2 NS  4. 8  3.8  26. 8  3.4  D  Table 16...  *  **  *  ***  *  100  (Cont'd)  Stand Age (years)  Pm SI 50 (m)  1) ThPs + 2) ThPsTp+  42. 8 43. 3  —  28. 4 26. 1  3. 9 3.3  28. 8 21.8  17.9 15.3  67. 2 62. 8  6.9 5.1  Overall  43. 0  -  27. 5  3.6  26. 3  17.0  65.6  6.3  F-ratio  0. 0 NS  --  4. 6 **  0.7 NS  2. 4 NS  0.9 NS  Plot  Type  Th Total SI 50 DBA EA DBA/BA EA (m) (n)2/h/5y) (m^/h) (%/5y) (m /h) z  DBA/ Tot BA {%/5y)  P. s i t c h e n s i s  •  0. 9 NS  TABLE 16 One-way a n a l y s i s of v a r i a n c e of the major species across d i f f e r e n t p l o t types of the Wet Western Hemlock Subzone. Data represent means f o r a l l o b s e r v a t i o n s of a p a r t i c u l a r p l o t type. C h a r a c t e r i s t i c s of p l o t types are given i n Table 8. For a b r e v i a t i o n s , see Table 10.  1.2 NS  101 J_. p l i c a t a o c c u r s age goes from 43.3 21.5  t o 29.9  m.  as a major s p e c i e s i n 3 p l o t t y p e s , where s t a n d  t o 60.6  y e a r s , and J_. h e t e r o p h y l l a s i t e i n d e x , from  B a s a l a r e a r a t e of i n c r e a s e , b a s a l a r e a , and  r a t e o f i n c r e a s e a l l v a r y s i g n i f i c a n t l y among p l o t t y p e s . s i g n i f i c a n t c o r r e l a t i o n between any  of t h e s e v a r i a b l e s .  percent  There i s no Total basal  area and J_. p l i c a t a i n c r e m e n t over t o t a l b a s a l a r e a do not v a r y ficantly.  The  lowest b a s a l a r e a r a t e of i n c r e a s e  signi-  (2.6%/5y) f o r T.  pli-  c a t a i s . found i n the ThTpPmt p l o t t y p e , the o n l y p l o t type where P_. menz i e s i i c o e x i s t s w i t h J_. p l i c a t a , and where P_. m e n z i e s i i a c h i e v e s r a t e of increase  (14.2%/5y).  i t s best  T h i s can be i n t e r p r e t e d as a s u p e r i o r com-  p e t i t i v e a b i l i t y o f P_. m e n z i e s i i over J_. p l i c a t a i n t h i s p l o t t y p e , by b e t t e r r e s p o n s e of P_. m e n z i e s i i t o the s i t e c o n d i t i o n s .  or  P_. s i t c h e n s i s  i s found i n two p l o t t y p e s , but none of the growth v a r i a b l e s r e f l e c t  any  significant difference. There i s a s t r o n g predominance of J_. h e t e r o p h y l l a over a l l p l o t types.  T. h e t e r o p h y l l a can e i t h e r form t h e c l i m a x by i t s e l f or by  c i a t i o n w i t h A. a m a b i l i s or T_. p l i c a t a .  asso-  T h i s i s a l s o what i s suggested  by t h e graph of s p e c i e s r e l a t i v e abundance a g a i n s t s t a n d age  (Figures  6 G and H), where T_. h e t e r o p h y l l a accounts f o r 60 t o 70% of the t o t a l b a s a l a r e a at a l l ages.  P_. s i t c h e n s i s and A.  a m a b i l i s f l u c t u a t e around the  l e v e l , and P_. m e n z i e s i i , J_. p l i c a t a and A. r u b r a , around the 5% The  s u c c e s s i o n d a t a o f the p r e v i o u s  chapter  ages.  level.  showed much the same, w i t h  emphasis on the p o s s i b i l i t y of A. a m a b i l i s t a k i n g over the low stand-types at o l d e r stand  15%  frequency  102 Minor species  (Table  17)  A. r u b r a appears a g a i n as a minor s p e c i e s , and i t s b a s a l a r e a and b a s a l a r e a i n c r e m e n t d i s p l a y no s i g n i f i c a n t d i f f e r e n c e among p l o t  types.  Although i t s b a s a l area i s s l i g h t l y l a r g e r i n o l d e r p l o t types, i t s r a t e o f i n c r e a s e becomes n e g a t i v e  (-2.1%/5y), and A. r u b r a i s deemed t o  be outcompeted by s e r a i and c l i m a x s p e c i e s , as i n a l l p r e v i o u s l y c o n s i dered subzones.  I t s b e h a v i o u r i s shown i n F i g u r e s 6 G and H.  A_. amabi-  l i s i s a major s p e c i e s i n ThAa, but a minor one i n ThTp*; f o r t h i s r e a son i t i s d i s c u s s e d as a minor s p e c i e s .  O n l y t h e J_. h e t e r o p h y l l a s i t e  i n d e x shows a s i g n i f i c a n t d i f f e r e n c e between t h e two p l o t t y p e s , but no s i g n i f i c a n t c o r r e l a t i o n w i t h o t h e r v a r i a b l e s can be e s t a b l i s h e d .  It  was found t h a t A. a m a b i l i s o c c u p i e s 42.0% o f t h e t o t a l b a s a l a r e a i n t h e ThAa p l o t t y p e (Table 8 ) , and c o n s t i t u t e s a c l i m a x w i t h T. h e t e r o p h y l l a . Packee (1976) p o i n t s out t h a t A. a m a b i l i s w i l l become a c l i m a x dominant i n t h e c o l d e r p o r t i o n o f t h e subzone, p r o v i d e d no major d i s t u r b a n c e o c c u r s , b u t w i l l be o f l e s s e r i m p o r t a n c e i n more m a r i t i m e (lower e l e v a t i o n ) p o r t i o n s o f t h e subzone.  Fog Western''Hemlock Major s p e c i e s (Table  Subzone 18)  T. h e t e r o p h y l l a i s t h e o n l y s p e c i e s found i n a l l o b s e r v a t i o n s . A l l v a r i a b l e s show s i g n i f i c a n t d i f f e r e n c e s between t h e two p l o t t y p e s , but t h e r e a r e t o o few o b s e r v a t i o n s t o d e t e c t any s i g n i f i c a n t  correlations.  T. h e t e r o p h y l l a has a r a t e o f i n c r e a s e o f 0.3%/5y i n t h e ThPs* p l o t and 12.8%/5y i n t h e ThTpt p l o t t y p e .  type,  T h i s i n d i c a t e s t h a t T. h e t e r o p h y l l a  103  Plot  Type  Stand Pm Age SI 50 (years) (m)  Th Total DBA/ SI 50 DBA BA DBA/BA BA Tot BA (ro) (m*/h/5y) (m^/h) (%/5y) (m2/h) (%/Sy)  A. rubra  Overall  41. 0  -— -  F-ratio  10.2 ***  —  10.5 ***  0.5 NS  1.6 NS  57. 1 53. 3  — —  26. 4 19.8  2.1 1.4  26. 8 16. 3  9.2 12.8  6 3. 5 69. 2  3.6 4.0  25. 9  2. 1  25. 9  9.5  64. 0  3.6  7.0 ***  0.7 NS  1.4 NS  1.1 NS  0.3 NS  0. 1 NS  1) ThPs* 2) IhPsTp+ 3) ThTpl?ai +  46. 0 40. 0 26. 7  -  27. 9 25.6 35. 1  0.3 0.6 0.6  9. 1 7. 9 3. 7  -2. 1 6.7 14.9  67. 9 60.1 40.8  0.7 1.? 1.7  27. 8  0.5  7. 9  3.8  61. 1  1.0  2.4 NS  8. 7 ***  0.8 NS  A. a m a b i l i s  D  ThAa 2) ThTp + Overall  56. 8  F-ratio  0.2 NS  -  TABLE 17 One-way a n a l y s i s of v a r i a n c e of the minor s p e c i e s across d i f f e r e n t p l o t t y p e s of the Wet Western Hemlock Subzone. Data represent means f o r a l l occurrences o f the s u b j e c t s p e c i e s i n a given p l o t type. C h a r a c t e r i s t i c s of p l o t types are given i n Table 8. For a b b r e v i a t i o n s , see Table 10.  104  Plct  Type  Stand Age (years)  Pm SI 50 (m)  Th Total DBA/ SI 50 DBA EA DBA/BA BA Tot BA (m) (m2/h/5y) (m2/h) (%/5y) (m*/h) (%/5y)  5• h g t e r g p h ^ l l a 51.7 43. 6  -—  ?9. 2  0. 2 3. 3  6C. 9 40. 8  0.3 12.8  74. 0 61. 8  0.3 5.6  Overall  48.7  -  33.7  1.3  53. 5  4.9  69. 5  2.2  F-ratio  12.2 ** *  20. 0 ** *  13. 6  6. 8  18.0  8. 0 **  1) ThPs + 2) ThTp +  —  -  35.3  ***  **  ***  16. 1  TABLE 18 One-way a n a l y s i s of v a r i a n c e of major s p e c i e s on p l c t types of the Fog Western Hemlock Subzone.  different  Data represent means f o r a l l o b s e r v a t i o n s o f a p a r t i c u l a r p l o t t y p e . C h a r a c t e r i s t i c s of p l c t types are g i v e n i n Table 9. For a b r e v i a t i c n s , see Table 10.  105 might outcompete J_. p l i c a t a , and P_. s i t c h e n s i s might l a t e r i n t e r f e r e w i t h t h e p r o g r e s s i o n of J_. h e t e r o p h y l l a .  S i n c e J_. p l i c a t a was  found  o n l y i n the ThTp+ p l o t t y p e , i t i s i m p o s s i b l e t o compare i t s p e r f o r mance, but the graph of s p e c i e s r e l a t i v e abundance ( F i g u r e 6)  indi-  c a t e s t h a t the h i g h r a t e o f i n c r e a s e of T_. h e t e r o p h y l l a a l l o w s i t t o o v e r t a k e T. p l i c a t a l a t e r .  T. p l i c a t a t h e n f a l l s t o the l e v e l of  10%  r e l a t i v e abundance ( F i g u r e s 6 I and J ) , and P_. s i t c h e n s i s i n c r e a s e s s l i g h t l y t o r e a c h a l e v e l under 10%. merely t r a c e s c h e n s i s was  (<2%).  The  P_. m e n z i e s i i and A. r u b r a  are  s t a n d - t y p e d a t a showed t h a t i n f a c t P_.  never abundant enough t o c o n s t i t u t e a s t a n d - t y p e and  J_. h e t e r o p h y l l a o v e r t a k e s  T. p l i c a t a by age  45.  I n the p r e v i o u s  sitthat chapter,  the u n l i k e l i n e s s of the r a r i t y of J_. p l i c a t a was  d i s c u s s e d and was  attri-  buted t o i n s u f f i c i e n t s a m p l i n g i n t h i s subzone.  The  climax  s p e c i e s as s t a t e d by Packee (1976) was  Minor species  (Table  r o l e of major  agreed upon.  19)  P_. s i t c h e n s i s i s c o n s i d e r e d g i v e n f o r A. a m a b i l i s i n the Wet  a minor s p e c i e s f o r the same r e a s o n Western Hemlock Subzone.  Its basal  a r e a i s s i g n i f i c a n t l y l a r g e r i n ThPst where i t i s a major s p e c i e s , 13.3  m /h, 2  a g a i n s t 5.1  m /h 2  i n ThTp+ where i t i s a minor s p e c i e s .  However,  i t s r a t e o f i n c r e a s e i s s m a l l e r , though not s i g n i f i c a n t l y i n the ThPs* p l o t t y p e , where J_. h e t e r o p h y l l a i s more abundant.  This r e f l e c t s  gonism between J_. h e t e r o p h y l l a and P_. s i t c h e n s i s .  F i g u r e s 6 I and  antaJ  i n d i c a t e t h a t the p r o p o r t i o n of i t s b a s a l a r e a over a l l the p l o t s o f subzone f l u c t u a t e s v e r y l i t t l e around t h e 10% d a t a showed t h a t P. s i t c h e n s i s was  level.  The  stand-type  never the most abundant s p e c i e s i n  the  106  Plct  Type  Stand Pm Age SI 50 (years) (m)  Th Total SI 50 DBA BA DBA/BA BA (m) ( m V h / S y ) (m /h) l%/5y) (m^/h) 2  DEA/ Tot BA (%/5y)  P. s i t c h e n s i s 52. 0  ao. c  -—  36. 9 31.2  0.8 1.0  13. 3 5. 1  6.0 11.7  75. 7 60. a  1.0 1.7  Overall  48.6  -  35.3  0.8  10. 9  7.6  71.3  1.2  F-ratio  23. 5 ** *  10.0 ***  0. 1 NS  5. 0 **  2.2 NS  1) ThPs + 2) ThTp +  -  -  8. a **  TABIE 19 One-way a n a l y s i s of v a r i a n c e of the minor s p e c i e s across d i f f e r e n t p l o t types of the Fcg Western Hemlock Subzcne. Data represent means f o r a l l occurrences o f the s u b j e c t s p e c i e s i n a given p l c t type. C h a r a c t e r i s t i c s of p l c t types are given i n Table 9. For a b b r e v i a t i o n s , see Table 10.  0.8 NS  107 any  stand.  S i t e index v a r i a t i o n S i t e i n d e x v a r i a t i o n was never s i g n i f i c a n t l y c o r r e l a t e d w i t h b a s a l a r e a growth.  A l t h o u g h s i t e i n d e x o f even-aged stands i s con-  s i d e r e d an e x p r e s s i o n o f s i t e q u a l i t y  ( C u r t i s et_ al_. 1974) , i t s  e v a l u a t i o n t a k e s o n l y age and h e i g h t i n t o account.  The absence o f  c o r r e l a t i o n between s i t e i n d e x and b a s a l a r e a growth does n o t i n v a l i date s i t e i n d e x as a measure o f s i t e p r o d u c t i v i t y s i n c e h e i g h t i s as i m p o r t a n t as b a s a l a r e a i n t h e computation  of p r o d u c t i v i t y .  I t seems  r a t h e r t o s u g g e s t , as i s g e n e r a l l y a c c e p t e d , t h a t b a s a l a r e a growth and h e i g h t growth a r e c o n t r o l l e d by d i f f e r e n t s i t e f a c t o r s .  Perhaps  h e i g h t growth i s more s e n s i t i v e t o p h y s i c o - c h e m i c a l s i t e f a c t o r s w h i l e b a s a l a r e a growth i s more s e n s i t i v e t o b i o t i c f a c t o r s such as c o m p o s i t i o n and d e n s i t y o f v e g e t a t i o n . The d i s t r i b u t i o n o f s i t e i n d i c e s i n 10 f e e t (3.03 m) c l a s s e s , a t age 50, a r e g i v e n p e r subzone, f o r P_. m e n z i e s i i and J_. h e t e r o p h y l l a ( F i g u r e 7 and 8), and t h e subzone means and s t a n d a r d d e v i a t i o n s a r e l i s t e d ( T a b l e 20).  There i s a s i g n i f i c a n t d i f f e r e n c e (p = 0.01) among t h e  subzone means f o r P_. m e n z i e s i i and J_. h e t e r o p h y l l a s i t e i n d i c e s , showing an i n c r e a s e i n s i t e i n d e x from t h e d r i e s t t o t h e m o i s t e s t subzone. Packee (1976) demonstrated  t h a t t h e mean annual m o i s t u r e d e f i c i t w i t h  200 mm o f s o i l water s t o r a g e c a p a c i t y was t h e most s u i t a b l e v a r i a b l e f o r d i f f e r e n t i a t i n g subzones.  Moisture d e f i c i t  (Table 20) has a  s i g n i f i c a n t c o r r e l a t i o n w i t h P. m e n z i e s i i s i t e i n d e x ( r = 0.95, p = 0.05), and w i t h T. h e t e r o p h y l l a s i t e i n d e x ( r = 0.82, p = 0.1).  This s t r o n g l y  108  FIGURE 7 Site index d i s t r i b u t i o n p e r 1 0 f e e t ( 3 . 0 3 m) c l a s s e s f o r P. m e n z i e s i i a t age 5 0 . The c o m p u t a t i o n i s b a s e d on a regression curve developed by MacMillan Bloedel Limited (1 9 7 5 I n t e r n a l R e p o r t ) .  DRY  WET  DOUGLAS-FIR  5 j  .5  4 -  .4  3 --  .3  2 --  .2  1  .1 + 0 20  40  60  80 100 120 340 160  DOUGLflS-FIR  I "KT 20 40 60 1  +  80 100 120 140 160  FOG WESTERN HEMLOCK  WET WESTERN HEMLOCK  DRY WESTERN HEMLOCK .5  5 j  .5  T  T  .4 +  4 3 --  .3 +  .3 +  2 •-  .2 +  .2 +  1 --  .1 +  1+  0. 20  40  60  80 100 120 1 40 160 R  20  menziesii  40  60 SITE  80 100 120 140 160 INDEX  (50)  •f-r-f I I I I I 1 I 1 I 20 40 60 80 100 120 140 160  110  FIGURE 8 S i t e index d i s t r i b u t i o n per 10 f e e t ( 3 . 0 3 to) c l a s s e s f o r T. h e t e r o p h y l l a at age 50,. The computation i s based cn a r e g r e s s i o n curve developed by KacMillan Dloedel Limited ( 1 9 7 5 Internal Report).  D R Y  D O U G L R S - F I R  WET  j  .5  A-•  .4  3 -•  .3  5  2  -  1  -  20  2  4 0 GO  D R Y  5  -  .1  + + -+-+-  i rpr  0  80 100 1 20  W E S T E R N  D O U G L R S - F I R  1 40  160  20 4 0 SO  H E M L O C K  WET  .5  T  i i T  1  80 100 120 1 4 0 160  W E S T E R N  H E M L O C K  F O G  .5  T  .4 +  .4 +  3 +  .3 +  .3  2 +  .2  .2  1 +  .1 +  tl  d 20  4 0 6 0 9 0 100 120 140 160 T.  S I T E  I N D E X  +  4-f-f  20 4 0 6 0 8 0 100 120 140 160  heterophylla  H E M L O C K  T  4 +  I  W E S T E R N  ( 5 0 )  2 0 4 0 6 0 8 0 100 1 2 0 140  160  112  SUBZONE  Pro SITE INDEX n mean s (m)  Dry Douglas- • f i r Subzone  71  Th SITE INDEX n mean s (m)  25. 9 (5.6)  10  25. 3 (5.6)  134  143  27.1  (6.4)  74  23. 9 (6.6)  93  26.2  (4.8)  62  28. 0 (5.0)  27  Set  Dcuglas-• f i r Subzone  Dry  Western Hemlock Subzone  82  29.1  (6. 2)  96  Wet Western Hemlock Subzone  36  34.2  (5.2)  229  2  38.1  (2.2)  19  Fog  MD mean (mm)  Western Hemlock Subzone  33.7  (4.8)  TABLE 20 Mean s i t e subzcne.  indices  and  mean annual moisture d e f i c i t per  S i t e i n d i c e s f o r P. m e n z i e s i i and T. h e t e r o p h y l l a a t age 50 (MacMillan B l o e d e l L i m i t e d 1975 I n t e r n a l Report). MC i s the mean annual moisture d e f i c i t with 200 mm o f s o i l water storage c a p a c i t y (Packee 1976). Values i n b r a c k e t s a r e t h e standard d e v i a t i o n s o f s i t e i n d i c e s .  4  113 suggests t h a t m o i s t u r e a v a i l a b i l i t y i s one o f t h e main d e t e r m i n a n t s i n h e i g h t growth f o r P_. m e n z i e s i i and J_. h e t e r o p h y l l a , and l i k e l y f o r t h e other species i n t h i s a n a l y s i s .  CONCLUSION  B i o g e o c l i m a t i c Subzones can be o b j e c t i v e l y s u b d i v i d e d  into plot  types which a r e s t a t i s t i c a l l y d e f i n e d on t h e b a s i s o f p r e s e n t vegetation.  canopy  D i f f e r e n c e s i n p l o t types a r e assumed t o modify t h e  dynamics o f c o m p e t i t i o n and t h e b a s a l a r e a growth performance o f species.  Q u a n t i t a t i v e d i f f e r e n c e s among p l o t t y p e s were found i n t h e  r a t e o f b a s a l a r e a growth o f s p e c i e s which cannot be s o l e l y a t t r i b u t e d t o s i t e index as a measure o f p r o d u c t i v i t y nor t o s i t e age.  Results  of a n a l y s i s o f v a r i a n c e a r e p a r t i c u l a r l y c o n c l u s i v e f o r t h e m a j o r s p e c i e s , P_. m e n z i e s i i , J_. h e t e r o p h y l l a , J_. p l i c a t a , and P_. s i t c h e n s i s , and f o r two minor s p e c i e s , P_. c o n t o r t a and A. r u b r a .  No s i g n i f i c a n t  e f f e c t o f P_. m e n z i e s i i and J_. h e t e r o p h y l l a s i t e index on b a s a l growth c o u l d be d e t e c t e d  at the plot l e v e l .  area  Significant differences i n  s i t e i n d e x appear a t t h e subzone l e v e l and seem t o r e f l e c t t h e s o i l m o i s t u r e regime. B i o t i c and a b i o t i c s i t e f a c t o r s v a r y g r e a t l y w i t h i n one B i o g e o c l i m a t i c Subzone.  The d a t a d i d n o t a l l o w t e s t i n g f o r e x a c t s i t e f a c t o r s  t h a t f a v o r t h e growth o f a s p e c i e s w h i l e i n h i b i t i n g t h e growth o f a n o t h e r . At e a r l y stages  o f secondary s u c c e s s i o n , s p e c i e s i n v a s i o n and p a r t i -  c u l a r l y , species establishment  a r e c o n t r o l l e d by a b i o t i c s i t e c o n d i t i o n s .  114 L a t e r on, t r e e c o m p o s i t i o n  c r e a t e s a s i t u a t i o n where s p e c i e s , j u s t  cause they grow, have t o compete f o r r e s o u r c e s .  Therefore,  s i t i o n i s an image o f b o t h a b i o t i c s i t e f a c t o r s  a l l o w i n g or not  t r e e compo-  presence o f v a r i o u s s p e c i e s , and b i o t i c components a l l o w i n g or t h e i r coexistence.  The  i n f e r e n c e s on s u c c e s s i o n drawn from  be-  the  not  these  r e s u l t s agree w i t h t h e s p e c i e s r e l a t i v e abundance observed throughout the r o t a t i o n p e r i o d and w i t h the s t a n d - t y p e previous  chapter.  s u c c e s s i o n d a t a o f the  Moreover, s p e c i e s performance might v a r y from  B i o g e o c l i m a t i c Subzone t o a n o t h e r , w i t h i n s i m i l a r p l o t t y p e s . p r e s e n c e o f P_. m e n z i e s i i i n the Wet seems t o c o r r e s p o n d o b s e r v a t i o n was  The  The  D o u g l a s - f i r Subzone, f o r i n s t a n c e ,  w i t h a poor growth o f -J_. h e t e r o p h y l l a .  No  such  made i n the Dry Western Hemlock Subzone, whereas the  o p p o s i t e f o r T. h e t e r o p h y l l a was zone.  one  found i n the Wet  Western Hemlock  r e l a t i o n s h i p s between t h e s e r e s u l t s suggest t h a t the  Sub-  overall  f o r e s t s u c c e s s i o n observed and m o d e l l e d a t the subzone l e v e l i s p a r t l y due  t o the dynamics o f i n t e r s p e c i e s c o m p e t i t i o n observed at the p l o t  level. T h i s s t u d y has brought f o r w a r d  some e v i d e n c e t h a t b a s a l  growth of a s p e c i e s v a r i e s a c c o r d i n g t o t r e e c o m p o s i t i o n by p l o t t y p e s .  I t was  o f t h e v a r i a t i o n due  area  as c h a r a c t e r i z e d  not meant t o a s s e s s the r e l a t i v e c o n t r i b u t i o n  t o a b i o t i c f a c t o r s w i t h t h a t due  however, i t i s v e r y l i k e l y t h a t b o t h are e q u a l l y  to  competition;  important.  115 LITERATURE CITED  C u r t i s , R.O., D.J. DeMars, and F.R. Herman. 1974. Which dependent v a r i a b l e i n s i t e i n d e x -- h e i g h t -- age r e g r e s s i o n s ? F o r e s t S c i . 20: 74-87. Daubenmire, R. 1968. P l a n t communities.  Harper § Row. New York. 300 p.  Daubenmire, R. and J.B. Daubenmire. 1968. F o r e s t v e g e t a t i o n o f e a s t e r n Washington and n o r t h e r n Idaho. Wash. S t a t e U n i v . Agr. Exp. S t a . B u l l . # 60. 104 p. F r a n k l i n , J . F . , and C.T. Dyrness. 1969. V e g e t a t i o n o f Oregon and Washington. U.S.D.A. F o r . Res. Pap. PNW-80. P o r t l a n d , Oregon. 216 p. F r a n k l i n , J . F . , and C.T. Dyrness. 1973. N a t u r a l v e g e t a t i o n o f Oregon and Washington. U.S.D.A. F o r . Res. Serv. Gen. Tech. Rept. PNW-8. 417 p. H a l l i d a y , W.E.D. 1937. A f o r e s t c l a s s i f i c a t i o n Serv. B u l l . 89.  f o r Canada. Can. F o r .  K r a j i n a , V . J . 1969. E c o l o g y o f f o r e s t t r e e s i n B r i t i s h Columbia. E c o l . Western N o r t h Amer. 2:1-147. U n i v . o f B r i t i s h Columbia. Dept. o f B o t . Packee, E.C. 1974. The B i o g e o c l i m a t i c Subzones o f Vancouver I s l a n d and t h e a d j a c e n t m a i n l a n d and i s l a n d s . M a c M i l l a n B l o e d e l L i m i t e d F o r . Res. Notes. 11 p. + app. Packee, E.C. 1976. An e c o l o g i c a l approach toward y i e l d o p t i m i z a t i o n t h r o u g h s p e c i e s a l l o c a t i o n . Ph.D. t h e s i s . U n i v . o f M i n n e s o t a . 740 p. * app. Rowe, J.S. 1972. F o r e s t r e g i o n s o f Canada. Can. F o r . Serv. P u b l . 1300. x • 172 p. S o c i e t y o f American F o r e s t e r s . 1954. F o r e s t cover types o f N o r t h America ( e x c l u s i v e o f M e x i c o ) . Soc. Amer. F o r . Washington, D.C. 67 p.  A n a l y s i s and m o d e l l i n g of i n t e r s p e c i e s c o m p e t i t i o n d u r i n g f o r e s t secondary s u c c e s s i o n .  Pierre  Bellefleur  CHAPTER I I I  The r e l a t i o n s h i p s between m u l t i - s p e c i e s c o m p e t i t i o n and s i n g l e t r e e r e p l a c e m e n t .  117 ABSTRACT  The  e f f e c t o f i n t e r s p e c i e s c o m p e t i t i o n was  tree basis.  The  examined on a s i n g l e  d a t a c o n s i s t e d o f over 2,000 o b s e r v a t i o n s from  12  Permanent Sample P l o t s where the c o o r d i n a t e s o f each t r e e were known. I n d i c e s o f c o m p e t i t i o n r e p r e s e n t i n g h o r i z o n t a l and v e r t i c a l f o r e s t s t r u c t u r e were computed f o r each t r e e . diameter  increment  R e g r e s s i o n models o f y e a r l y  were b u i l t t o e v a l u a t e the c o n t r i b u t i o n o f  diameter,  age, s i t e i n d e x , subzone l o c a t i o n , s e v e r a l c o m p e t i t i o n i n d i c e s and a c t i o n s o f some o f t h e s e t e r m s , f o r P_. m e n z i e s i i , T. p l i c a t a , T. h e t e r o p h y l l a .  inter-  and  The most s i g n i f i c a n t v a r i a b l e s a f f e c t i n g t r e e g r o w t h ,  m o r t a l i t y , and r e g e n e r a t i o n , were d e t e r m i n e d by a n a l y s i s o f v a r i a n c e . The r e s u l t s o f t h e r e g r e s s i o n models showed t h a t e s t i m a t e s based on p r e s e n t s i t e c o n d i t i o n s were s i g n i f i c a n t o n l y when used a l o n e , w i t h out v a r i a b l e s i n d i c a t i v e o f the p a s t h i s t o r y o f the t r e e .  I t was  t h a t the r e l a t i o n s h i p between the c o m p e t i t i o n regime and the s t a t e o f a t r e e seems t o be cause and e f f e c t a p p l i e d over the l i f e - s p a n of the t r e e .  The most p o w e r f u l  found  present entire  i n d i c a t o r s o f the impact o f  c o m p e t i t i o n were found i n the t r e e i t s e l f , and were e v a l u a t e d by i t s diameter  and  long-term  diameter  increment  i n comparison w i t h the whole  population.  M o r t a l i t y and r e g e n e r a t i o n of each s p e c i e s were found t o  v a r y through  time i n r e s p o n s e t o the immediate neighborhood o f the i n -  d i v i d u a l t r e e ; t h i s seems t o be the mechanism which generates a t the p o p u l a t i o n  level.  succession  118  RESUME  On a examine l ' e f f e t de l a c o m p e t i t i o n de  l'arbre.  Les donnees forment p l u s de 2,000 o b s e r v a t i o n s  de 12 p a r c e l l e s permanentes ou l ' o n c o n n a i t tige.  i n t e r s p e c i f i q u e au n i v e a u provenant  l e s coordonnees de ehaque  On a c a l c u l e des i n d i c e s de c o m p e t i t i o n  t e n a n t compte de l a  s t r u c t u r e h o r i z o n t a l e e t v e r t i c a l e de l a f o r e t pour chaque a r b r e .  On  a c o n s t r u i t des modeles de r e g r e s s i o n de 1'accroissement annuel en d i a metre pour e v a l u e r  l a c o n t r i b u t i o n du d i a m e t r e , de l ' S g e , de l ' i n d i c e de  s i t e , de l a l o c a t i o n de l a sous-zone, de p l u s i e u r s i n d i c e s de  competition  et des i n t e r a c t i o n s de quelques-uns de ces termes pour P_. m e n z i e s i i , J_. p l i c a t a e t J_. h e t e r o p h y l l a .  On a d e t e r m i n e l e s v a r i a b l e s l e s p l u s s i -  g n i f i c a t i v e s pour l a c r o i s s a n c e ,  l a m o r t a l i t e et l a regeneration par  a n a l y s e de v a r i a n c e . Les r e s u l t a t s des modeles de r e g r e s s i o n o n t montre que l e s p r e d i c t i o n s basees s u r l e s c o n d i t i o n s  a c t u e l l e s du s i t e s o n t s i g n i f i c a t i v e s  seulement s i u t i l i s e e s s e u l e s , sans 1 ' i n c l u s i o n de v a r i a b l e s r e f l e t a n t l e passe de l ' a r b r e .  On a t r o u v e que l a r e l a t i o n e n t r e  l e regime de compe-  t i t i o n e t l ' e t a t a c t u e l de l ' a r b r e en e s t une de cause a e f f e t d u r a n t l a v i e e n t i e r e de l ' a r b r e . les meilleures  C'est dans l ' a r b r e lui-meme que l ' o n a t r o u v e  i n d i c a t i o n s de 1'impact de l a c o m p e t i t i o n  qui est revele  par son d i a m e t r e e t son a c c r o i s s e m e n t en d i a m e t r e en comparaison de l a population.  On a t r o u v e que l a m o r t a l i t e e t l a r e g e n e r a t i o n  espece v a r i e n t s e l o n l e v o i s i n a g e que  immediat de chaque a r b r e ;  ce s o i t l a l e mecanisme q u i engendre l a s u c c e s s i o n  population.  de chaque i l semble  au n i v e a u de l a  119 INTRODUCTION  The  e f f e c t of i n t e r s p e c i e s c o m p e t i t i o n on s u c c e s s i o n i s o f t e n  t a k e n f o r g r a n t e d , on the b a s i s o f b i o l o g i c a l common sense (Dansereau 1957,  Horn 1974), and many c o n c l u s i o n s about i t s importance are based  on s p e c u l a t i o n ( M i l l e r 1967). c o m p e t i t i o n obscures  The  l a c k o f knowledge about i n t e r s p e c i e s  the mechanisms which l e a d t o the i n h i b i t i o n o f  growth as p o p u l a t i o n d e n s i t y i n c r e a s e s (Stewart and L e v i n 1973) . t i t i o n , as a p r o c e s s  o f p l a n t p o p u l a t i o n dynamics, has been  by more obvious p r o c e s s e s ,  Compe-  concealed  l i k e s u c c e s s i o n , and has t h e r e f o r e been ne-  g l e c t e d by i n v e s t i g a t o r s ( P i c k e t t 1976).  Fluctuations i n population -  d e n s i t y s h o u l d be e x p l a i n e d by p r o c e s s e s  a c t i n g at the community l e v e l  (Decker 1959).  The  attempt t o e l u c i d a t e t h e mechanism o f s u c c e s s i o n  at the p h y s i o l o g i c a l l e v e l o f the p l a n t r e p r e s e n t s a s t e p below the p o p u l a t i o n l e v e l and  leaves p a r t l y unexplained  the events observed  in  the community. The  importance o f i n t e r s p e c i e s c o m p e t i t i o n i n p o p u l a t i o n dynamics  has been s t r e s s e d by many i n v e s t i g a t o r s , , y e t s t a t i s t i c a l evidence i s l a c k i n g t o c o n f i r m t h e h y p o t h e s i s o f u n d e r l y i n g mechanisms by which c o m p e t i t i o n would l e a d t o s u c c e s s i o n .  This hypothesis requires a  demonstrated m o d i f i c a t i o n of t h e response o f an i n d i v i d u a l p l a n t t o the presence of d i f f e r e n t competitors  i n i t s immediate neighborhood.  o v e r , i t s h o u l d be shown t h a t p a r t i c u l a r combinations  More-  o f p l a n t s can  inhibit  the growth o f a s p e c i f i c p l a n t and induce i t s m o r t a l i t y . T h i s c h a p t e r attempts  t o t e s t the f o l l o w i n g hypotheses f o r a f o r e s t  community o f C o a s t a l B r i t i s h Columbia. (1)  The g r o w t h , the  suppression,  120 and t h e r e g e n e r a t i o n  o f a s i n g l e t r e e a r e r e l a t e d t o t h e f o r e s t compo-  s i t i o n i n i t s immediate n e i g h b o r h o o d . (2) The d e c r e a s e i n r a t e o f growth of a t r e e i s p r o g r e s s i v e and can be used t o p r e d i c t i t s m o r t a l i t y . (3) The  r e l a t i o n s h i p between r a t e o f growth and f o r e s t c o m p o s i t i o n  specific.  i s species-  (4) The r e p l a c e m e n t o f dead t r e e s by t r e e s o f t h e same o r  d i f f e r e n t s p e c i e s can be p r e d i c t e d by t h e neighborhood c o m p o s i t i o n .  (5)  Dead t r e e s a r e f r e q u e n t l y r e p l a c e d by t r e e s o f o t h e r s p e c i e s and t h i s mechanism g e n e r a t e s t h e s u c c e s s i o n observed a t t h e l e v e l o f t h e f o r e s t stand.  DESCRIPTION OF THE DATA  The  d a t a c o n s i s t s o f a s e t o f 12 Permanent Sample P l o t s from t h e  d a t a bank o f M a c M i l l a n  Bloedel Limited, Forestry D i v i s i o n .  The p l o t s  b e l o n g t o t h e f o u r major B i o g e o c l i m a t i c Subzones o f C o a s t a l  British  Columbia; two p l o t s a r e i n t h e Dry D o u g l a s - f i r Subzone, s i x i n t h e Wet D o u g l a s - f i r Subzone, t h r e e i n t h e D r y Western Hemlock Subzone, and one p l o t i s i n t h e Wet Western Hemlock Subzone. 0.04 h e c t a r e  and t h r e e , 0.08 h e c t a r e .  Nine p l o t s have an a r e a o f  P l o t parameters were measured  t h r e e o r f o u r times a t f i v e - y e a r i n t e r v a l s .  T h e i r f o r e s t d e n s i t y ranges  from 1,317 t o 1,947 stems p e r h e c t a r e , and t h e s i t e index  (base age 50)  v a r i e s from 14 t o 38 m f o r P_. m e n z i e s i i , and from 12 t o 33 f o r J_. heterophylla.  The age o f t h e p l o t s ranges from 15 y e a r s a t t h e f i r s t mea-  surement t o 114 y e a r s a t t h e l a s t measurement. parameters, described  Standard  inventory-type  i n Chapter I , were measured f o r each t r e e .  In  121 a d d i t i o n , the p o s i t i o n of each t r e e was  c a l c u l a t e d and r e c o r d e d on stem  maps. S i n c e the main g o a l of t h i s s t u d y i s the a n a l y s i s of f o r e s t i n t e r species competition, diversity.  The  sample p l o t s were chosen on the b a s i s o f t r e e  number of t r e e s p e c i e s p e r p l o t v a r i e s from t h r e e t o s i x ;  a t o t a l of n i n e s p e c i e s were found: P_. m e n z i e s i i , T_. p l i c a t a , T_. p h y l l a , A. r u b r a , A. g r a n d i s , and monticola  THE  species  hetero-  l e s s a b u n d a n t l y , A. macrophyllum, P i n u s  D o u g l . , Cornus n u t t a l l i i Audubon, and Prunus e m a r g i n a t a Dougl.  CHOICE OF AN APPROACH  L i t e r a t u r e Review There a r e a v a r i e t y o f d e t e r m i n i s t i c models f o r s i n g l e s p e c i e s : P i n u s t a e d a L.  ( C l u t t e r 1963), P. m e n z i e s i i  G o u l d i n g 1972,  B e l l a 1971,  M i t c h e l l 1971,  ( M i t c h e l l 1969), P_. c o n t o r t a models use  (Newnham 1964,  Paille  A r n e y 1972), P i c e a  (Lee 1967), T. h e t e r o p h y l l a  glauca  ( L i n 1969). These  e i t h e r a t r e e - d i s t a n c e dependent or t r e e - d i s t a n c e  approach (Munro 1973), and  1970,  they a l l deal with i n t r a s p e c i e s  independant competition.  The  main f e a t u r e common t o t h e s e models i s the concept of "zone of i n f l u e n -  ce"  ( K r a j i c e k et a l . 1 9 6 1 ,  V e z i n a 1963,  Opie 1968).  The  zone o f i n f l u e n c e  o f a t r e e i s d e f i n e d as an a r e a on the ground r e p r e s e n t i n g p r o j e c t i o n of t h e crown or of the r o o t s . h o r i z o n t a l extent  1972,  vertical  I t i s , t h e r e f o r e , the assumed  t o which a t r e e can g a t h e r l i g h t , water and n u t r i e n t s .  P e r t i n e n t r e v i e w s of f o r e s t stand s i m u l a t i o n m o d e l l i n g (Jaquette  the  Honer 1972,  F r a n k l i n et al_. 1972,  are numerous  Smith 1973,  Munro 1973).  122 Plant p h y s i o l o g i c a l modelling et_ al_. . 1975), a l t h o u g h  (Hesketh and Jones 1976, M c K i n i o n  e x t r e m e l y r i c h i n d e t a i l s about t h e mechanics o f  a p l a n t , r e v e a l l i t t l e about p l a n t t o p l a n t i n t e r a c t i o n , and even l e s s about a m u l t i - s p e c i e s s i t u a t i o n .  A g r i c u l t u r a l plant modelling  i s also  concerned p r i m a r i l y w i t h m o n o c u l t u r e s ( S t e r n 1965, Mead 1967). There a r e s e v e r a l models concerned w i t h f o r e s t m u l t i - s p e c i e s modelling 1968,  (Nelson  1965, Duncan e t al_. 1967, Waggoner and R e i f s n y d e r  B o t k i n e t a l . 1970, W h i t t a k e r  e t al_. 1974, S t o u t e t a l . 1975).  In  t h e s e , t h e i n v e s t i g a t o r i s u s u a l l y f a c e d w i t h a number o f parameters varying together  t o d e t e r m i n e , a t any i n s t a n t , p a r t o f t h e b e h a v i o u r o f  a group o f s p e c i e s .  M u l t i p l e r e g r e s s i o n techniques  u s e d , and have p r o v e n t o be q u i t e p o w e r f u l .  are t h e r e f o r e  widely  However, m u l t i - s p e c i e s  models a r e m o s t l y d e v e l o p e d a t t h e l e v e l o f t h e whole s t a n d , u s i n g a t r e e - d i s t a n c e independent approach.  T h i s approach i s s u f f i c i e n t f o r  growth and y i e l d s t u d i e s , but i n a d e q u a t e t o examine p l a n t t o p l a n t  inter-  action. In view o f t h e o b j e c t i v e s o f t h i s s t u d y , a t r e e - d i s t a n c e dependent approach seems t o be n e c e s s a r y t o i n v e s t i g a t e t h e r e s p o n s e o f a s i n g l e p l a n t t o a number o f b i o t i c p a r a m e t e r s .  M u l t i p l e r e g r e s s i o n and a n a l y s i s  of v a r i a n c e can t h e n be a p p l i e d t o e v a l u a t e t h e v a r i a b i l i t y and r e l a t i v e importance of v a r i o u s parameters. Methods H e i g h t growth and d i a m e t e r growth show d i f f e r e n t p h y s i o l o g i c a l r e s ponses.  The l a t t e r i s more s e n s i t i v e t o t h e d e n s i t y o f t h e f o r e s t  (Kramer and K o z l o w s k i  1960) and i s o f t h e g r e a t e s t i n t e r e s t f o r  123 competition studies.  The h y p o t h e s i s t h a t the r a t e o f growth o f a  s i n g l e t r e e i s r e l a t e d t o c o m p e t i t i o n from d i f f e r e n t s p e c i e s i n i t s neighborhood i m p l i e s a p r e c i s e measurement of c o m p e t i t i o n due  t o each.  Two  main types o f c o m p e t i t i o n i n d e x are found i n the f o r e s t l i t e r a t u r e .  The  f i r s t type i s based on i n d i v i d u a l t r e e c o m p e t i t i o n and u s u a l l y  evaluates i n t r a s p e c i e s competition.  The  second t y p e . d e a l s w i t h i n t e r -  s p e c i e s c o m p e t i t i o n , but i s g e n e r a l l y c a l c u l a t e d a t the s p e c i e s For t h i s s t u d y , an i n d e x o f c o m p e t i t i o n based on s i n g l e t r e e s  level.  was  d e r i v e d from the i d e a o f i n t r a s p e c i e s c o m p e t i t i o n i n d i c e s by e x t e n t i o n o f the concept from one t o s e v e r a l s p e c i e s . p r e s e n t e d by B e l l a (1969) and Moore et_ al_.  The  c l a s s i c a l approach i s  (1973).  I f t h e s u b j e c t t r e e i s denoted S and i t s d i a m e t e r a zone o f diameter  ZS, p r o p o r t i o n a l t o DS,  f l u e n c e of S (Figure 9 A).  there exists  d e f i n e d as the zone o f i n -  S i m i l a r l y , each c o m p e t i t o r j of s p e c i e s i ,  denoted C ( i , j ) , has a d i a m e t e r ZC(i,j).  DS,  When ZS i s o v e r l a p p e d  D C ( i , j ) and a zone o f i n f l u e n c e o f  by Z C ( i , j ) , i t i s assumed t h a t S and C  ( i , j ) compete f o r the same r e s o u r c e s w i t h i n the a r e a o f o v e r l a p 0 The  diameter  summation o f o v e r l a p o f t r e e s o f s p e c i e s 1 i s Sum  (i,j).  (0(1,j)), for  j = l . . . n , where n i s t h e number o f c o m p e t i t o r s o f s p e c i e s 1 w i t h s u b j e c t t r e e S. i s Sum  The r a t i o o f t h e a r e a o f o v e r l a p o f s p e c i e s 1 t o the a r e a o f S ( 0 ( 1 , j ) ) / A S , f o r j = l . . . n , where AS i s the a r e a o f the zone o f  i n f l u e n c e o f S. Sum  The r a t i o o f the o v e r l a p due  to a l l species i s t h e r e f o r e  ( 0 ( i , j ) ) / A S , f o r j = l . . . n and i = l...m, where m i s the number o f  s p e c i e s competing w i t h S.  The  c o m p u t a t i o n o f the a r e a o f o v e r l a p  adapted f o r m u l t i - s p e c i e s from Arney  (1972).  was  124  FIGURE  9  A. Geometrical representation of the areas of overlap b e t w e e n a s u b j e c t t r e e a n d i t s c o m p e t i t o r s . DS = DBH of the subject t r e e . ZS = d i a m e t e r o f t h e z o n e o f i n f l u e n c e o f t h e s u b j e c t t r e e . C C ( i , j ) - DBH o f t h e j t h t r e e o f the ith competing s p e c i e s . Z C ( i , j ) = diameter of the zone of i n f l u e n c e of the j t h t r e e cf the i t h competing species. C(i,j) = area of o v e r l a p between t h e j t h t r e e of the i t h c o m p e t i n g s p e c i e s and t h e s u b j e c t t r e e . R e f e r t o t e x t for formulae. B. Geometrical r e p r e s e n t a t i o n of the h e i g h t r a t i o of the competing t r e e s over the s u b j e c t t r e e . S subject tree. <i/1) 1th tree of the i t h c o m p e t i n g s p e c i e s . HS = h e i g h t of t h e s u b j e c t t r e e . HC(j) = height cf the jth tree. Refer to t e x t f c r formulae. c  =  125  126 The p o t e n t i a l a r e a of o v e r l a p due t o unknown c o m p e t i t o r s l o c a t e d o u t s i d e the p l o t b o r d e r s _et_ al_. 1977).  c r e a t e s a b i a s (Monserud and Ek 1974,  The method o f m i r r o r image from t h e b o r d e r was  Martin used, w i t h  the r e f l e c t i o n l i n e p a s s i n g through t h e b o r d e r , and the c a l c u l a t e d l a p was weighted  i n p r o p o r t i o n t o t h e d i s t a n c e o f t h e s u b j e c t t r e e from  each of t h e two c l o s e s t b o r d e r s . t h i s procedure  over-  S i n c e sample p l o t s are r e c t a n g u l a r ,  performed s a t i s f a c t o r i l y when compared w i t h e v a l u a t i o n  u s i n g d i s t a n c e and s i z e o f t r e e s o u t s i d e t h e b o r d e r s . A s i m p l e i n d e x o f v e r t i c a l c o m p e t i t i o n was h e i g h t o f t h e s u b j e c t t r e e i s denoted HS, HC(j)  (Figure 9 B).  height.  The  also calculated.  and the h e i g h t of a c o m p e t i t o r  No s p e c i e s d i s t i n c t i o n was  made f o r t h e c o m p e t i t o r s '  average h e i g h t of t h e c o m p e t i t o r s i s Sum(HC(j))/n, f o r  j = l . . . n and t h e h e i g h t r a t i o of c o m p e t i t o r s over s u b j e c t t r e e i s (HC(j))/n/HS, f o r j = l . . . n .  under t h e i r shade ( i n d e x >1), The DBH  ( i n d e x < 1 ) or i s  and i n what p r o p o r t i o n .  (diameter a t b r e a s t h e i g h t ) o f each t r e e was measured a t  f i v e - y e a r i n t e r v a l s and t h e average y e a r l y DBH age o f each t r e e was  s t a t u s o f t h e t r e e was The  increment was  calculated.  e v a l u a t e d from r e g r e s s i o n e q u a t i o n s based e i t h e r  on measured age, f o r canopy t r e e s , or on DBH,  l i v e , or dead.  Sum  The p u r p o s e o f t h i s i n d e x i s t o i n d i c a t e  whether the s u b j e c t t r e e i s t a l l e r than i t s c o m p e t i t o r s  The  The  r e c o r d e d as i n g r o w t h  f o r ingrowth t r e e s . (DBH <4  The  cm at l a s t measurement),  subzone t o which t h e p l o t belongs was  r e c o r d e d as a  presence-absence f a c t o r . To e v a l u a t e the i n f l u e n c e of t h e presence  of n d i f f e r e n t  species  on t h e d i a m e t e r growth o f a s u b j e c t t r e e , r e g r e s s i o n e q u a t i o n s o f the  127  f o l l o w i n g form were b u i l t : INCREMENT  ( i , j ) = f(Sum (0(1,1), Sum (0(2,1))... Sum ( Q ( n , i ) ) )  f o r each s u b j e c t t r e e i o f each s p e c i e s j . Other p r e d i c t o r s such as DBH  2  and DBH/age were a l s o used i n some models.  The purpose o f t h e  e x e r c i s e was n o t t o r e a c h a h i g h c o e f f i c i e n t o f d e t e r m i n a t i o n  ( R ) , but 2  t o determine t h e c o n t r i b u t i o n o f v a r i o u s p r e d i c t o r s i n t h e e q u a t i o n . P r e d i c t o r c o n t r i b u t i o n was t e s t e d by a n a l y s i s o f v a r i a n c e o f t h e a d d i t i o n a l sum o f squares due t o t h e p r e d i c t o r .  F i n a l l y , the s t a t i s t i c a l  s i g n i f i c a n c e o f i n t e r a c t i o n s between p r e d i c t o r " s p e c i e s o v e r l a p  ratio"  and p r e d i c t o r "subzone" were t e s t e d .  RESULTS AND DISCUSSION  Regression  models  To f i n d out t h e u s e f u l n e s s o f d i s t i n g u i s h i n g between t h e o v e r l a p r a t i o due t o each competing s p e c i e s , as opposed t o t h e t o t a l o v e r l a p two s i m p l e r e g r e s s i o n models were b u i l t 1 pools a l l competitor separates  (Table 21, Model 1 and 2 ) .  ratio, Model  s p e c i e s i n t o o v e r a l l o v e r l a p (SUMOR); Model 2  o v e r l a p s by c o m p e t i t o r  s p e c i e s (0PM, OTP, etc.).  Both models  i n c l u d e DBH, age, and subzone l o c a t i o n as a d d i t i o n a l independent v a r i a b l e s . The a n a l y s i s o f v a r i a n c e  (Table 22, Model 2 v e r s u s Model 1) c o n f i r m s t h e  s i g n i f i c a n c e o f a d d i t i o n a l sum o f squares due t o a d d i t i o n a l f a c t o r s c o n s i d e r e d i n Model 2, w i t h t h e e x c e p t i o n o f J_. p l i c a t a model.  It i s ,  t h e r e f o r e , u s e f u l t o know e x a c t l y which s p e c i e s i s competing a g a i n s t P_. m e n z i e s i i and T_. h e t e r o p h y l l a .  T_. p l i c a t a appears l e s s s e n s i t i v e t o  128  1)  Y =  ( K , DBH, E  2) Y =  Y =  Y =  (Pm) =  2  2  ( K , DBH, E  2  (Pm) =  (Ip)  = 0.508  (lp)  - 0.513  OEM, O T P ,  0.630  OTH)  OAR, OAM,  DDF, WDF,  DWH,  (Th) = 0 . 4 3 0 WDF, DWH,  WWH)  B  WDF,  DWH,  (Th) = 0 . 4 2 5  OTP,  (Tp) = 0 . 5 1 0  B  (Th) = 0. 4 1 0  DDF,  = 0.510  SUMOB*HR, OEM,  0.655  DSH, WWH)  C T H , OAG,  OEM, O T P , C T H ,  0.655  AGE,  (lp)  OPM, O T P ,  0.656  AGE,  (Pm) =  SUMOE, D E F , WDF,  0.f>4 5  AGE,  (Pm) =  ( K , DBH, E  5)  2  ( K , DBH, R  4) Y =  (Pm) =  ( K , DBH, A G E , WWH) E R  3)  2  AGE,  OTH, DDF,  WWH)  (Th) = 0. 4 2 5  B  (Tp) = 0 . 1 8 6  (Th) = 0 . 4 1 3  6) Y = ( K ,  DBH, A G E , OEM, O T P , C T H , DDF, WDF, DWH, WWH, OPM *DDF, GTF*DDF OPM*WBF, OTP*WDF, OTH*W C F , CPM*DWH, OTP*DWIl, OTH*DWH, OPK*WWH, CTP*WWH, CTH*WWH) B R  7)  Y =  2  (Pm) = ' 0 . 6 6 4  (Tp) = 0 . 5 0 8  ( K , DBH, D B H , DEH/AGE, DDE, WDF, DWH, WWH) B 2  E  2  (Pm) = 0. 7 6 5  (Th) =  SUMOE, OEM,  (Tp) = 0 . 6 8 4  0.427  OTP, OTH,  (Th) =  0.506  FSITE,  HSTTE,  129 (Cont'd)  TABLE  21  Regression models used in this study. R i s given for three subject species: P. m e n z i e s i i , T. p l i c a t a , and %• h e t e r c p h y l l a r e s p e c t i v e l y . V a r i a b l e names a r e as follows: 2  AGE: b r e a s t age c f t h e t r e e ( y e a r s ) E: v e c t o r o f r e g r e s s i o n c o e f f i c i e n t s DBH: diameter at breast height (mm) DEE: C r y D o u g l a s - f i r S u b z o n e ( 0 o r 1) DWH: D r y W e s t e r n H e m l c c k S u b z o n e ( 0 o r 1) F S I T E : s i t e i n d e x f o r P. m e n z i e s i i , (age 50) (m) H S I T E : s i t e i n d e x f o r T. h e t e r o p h y l l a , ( a g e 50) (m) HE: h e i g h t ratio K: t h e c o n s t a n t 1 GAG: o v e r l a p r a t i o due t o A. g r a n d i s CAM: o v e r l a p r a t i o due t o A. m a c r o p h y l l u m CAR: o v e r l a p r a t i o d u e t o A. r u b r a CPM: o v e r l a p r a t i o d u e t o P. m e n z i e s i i OTH: o v e r l a p r a t i o due t c T. h e t e r o p h y l l a OTP: o v e r l a p r a t i o due t o T. plicata SUMOB: t o t a l o v e r l a p r a t i o ( a l l s p e c i e s ) WDF: Wet D o u g l a s - f i r S u b z o n e ( 0 o r 1) WWH: Wet W e s t e r n H e m l c c k S u b z o n e ( 0 o r 1) Y: a v e r a g e y e a r l y d i a m e t e r i n c r e m e n t i n the l a s t f i v e years (mm)  130 Model  Source  MODEL 2 v e r s u s  df  MS  F-ratio  MODEL 1 4. 04 ***  P.  Additional Error  Regression  5 657  12. 15 3.01  T. p l i c a t a  Additional Error  Regression  5 377  4.10 5. 16  0.80  NS  1'  additional Error  Regression  4 400  4.58 1. 29  3.55  **#  menziesii  Addit i c n a l Regression Error  2 660  26.92 3.01  8.94  ***  plicata  Additional Error  Regression  2 380  4.82 5. 15  0.93  NS  heterophylla  Additional Error  Regression  2 402  6. 44 1.29  4.99  ***  Additional Error  Regression  1 659  1. 05 3.01  0.35  NS  T. p _ l i c a t a  Additicnal Error  Regression  1 379  0.17 5. 16  0.03  NS  T . l>2lsro_p_h_y_ 1 l a  Additional Error  Regression  1 40 1  0. 12 1.30  0.09  NS  hgte^irophylla  MODEL 3 P.  MODEL 4 P.  v e r s u s MODEL 1  v e r s u s MODEL 3  menziesii  Table 22...  131 (Cont'd)  Modal  df  MS  F-ratic  4 660 4 .380  3 4 . 75 3.01 24.61 5. 15  1 1 .54 * * *  Regression  3 402  3.51 1.29  2 . 7 2 ***  Additional Error  Regression  11 649  4.62 2.98  1.55 NS  T. J 2 l i c a t a  Additional Error  Regression  11 369  0.78 5.32  0. 15 NS  T. h e t e r o p h y l l a  Additional Error  Regression  8 394  0.31 1.32  0 . 2 3 NS  Additional Error  Regression  4 656  158.7 2.06  77.03  T. p l i c a t a  Additional Error  Regression  4 376  177.7 3.36  5 1 . 6 8 ***  T. h e t e r o p h y l l a  Additional Error  Regression  4 398  18.49. 1.12  1 6 . 5 1 ***  MODEL P..  3 versus  menziesii  T. p l i c a t a  2»  heterophylla  MODEL 6 v e r s u s P.  menziesii  MODEL 7 v e r s u s P.  menziesii  Source  MCEEL 5 Additional Error Additional Error Additional Error  Regression Regression  4.78 ***  MODEL 3  MODEL 3 ***  T A B L E 22 A n a l y s i s o f v a r i a n c e t a b l e on r e g r e s s i o n racdels. The analysis tests t h e s i g n i f i c a n c e of the v a r i a t i o n accounted f o r by t h e f i r s t m o d e l o v e r a n d a b o v e t h a t accounted f o r by t h e s e c o n d m o d e l .  132 t h i s l e v e l o f d e t a i l i n t h i s model.  The l a r g e number o f p r e d i c t o r s i n  the models, and t h e low o c c u r r e n c e o f some s p e c i e s made t h e s o l u t i o n o f the models p o s s i b l e o n l y f o r t h r e e s p e c i e s : P_. m e n z i e s i i , J_. h e t e r o p h y l l a , and J_. p l i c a t a .  Model 3 (Table 21) shows t h a t i t i s p o s s i b l e t o d e l e t e  the low f r e q u e n c y s p e c i e s as p r e d i c t o r s i n Model 2, and s t i l l o b t a i n a more p o w e r f u l  model than Model 1.  Model 4 t e s t s an agglomerate i n d e x  of c o m p e t i t i o n , d e f i n e d as t o t a l o v e r l a p r a t i o times t h e h e i g h t The u n d e r l y i n g h y p o t h e s i s  ratio.  i s t h a t t h e average y e a r l y increment s h o u l d be  i n v e r s e l y p r o p o r t i o n a l t o t h e t o t a l o v e r l a p r a t i o , as w e l l as t o t h e h e i g h t r a t i o , s i n c e t h e o v e r l a p on b o t h t h e h o r i z o n t a l and t h e v e r t i c a l p l a n e o f t h e crown i s assumed d e t r i m e n t a l t o d i a m e t e r i n c r e m e n t . of v a r i a n c e shows t h a t t h i s p r e d i c t o r does n o t add s i g n i f i c a n t  Analysis  information  (Table 22, Model 4 v e r s u s Model 3 ) . The n e c e s s i t y o f i n c l u d i n g t h e B i o g e o c l i m a t i c Subzone from which each o b s e r v a t i o n came was t e s t e d by removing t h i s i n f o r m a t i o n from Model 3 (Table 21, Model 5 ) .  The a n a l y s i s o f v a r i a n c e s u p p o r t s  the hypothesis  t h a t t h e a d d i t i o n a l i n f o r m a t i o n p r o v i d e d by t h e subzone l o c a t i o n i s highly significant  (Table 22, Model 3 v e r s u s Model 5 ) .  Model 6 was  d e r i v e d from Model 3 t o t e s t a p o s s i b l e i n t e r a c t i o n between t h e o v e r l a p r a t i o s and t h e B i o g e o c l i m a t i c Subzones.  I t was h y p o t h e s i z e d  t h a t P_. men-  z i e s i i , T_. p l i c a t a , and T_. h e t e r o p h y l l a might have a t o t a l l y d i f f e r e n t impact as c o m p e t i t o r s  from one subzone t o another (Table 21, Model 6 ) .  The a n a l y s i s o f v a r i a n c e i n d i c a t e s , however, t h a t t h e s e i n t e r a c t i o n s a r e not s i g n i f i c a n t  (Table 22, Model 6 v e r s u s Model 3 ) .  Some p r e d i c t o r s were  added t o Model 3 t o t e s t t h e i r s i g n i f i c a n c e . DBH was i n c l u d e d as a 2  133 r e f l e c t i o n o f t h e g e o m e t r i c i n c r e a s e o f b a s a l a r e a ; DBH/Age as an i n d i c a t o r o f t h e average growth over t h e l i f e o f t h e t r e e ; P_. m e n z i e s i i and J_. h e t e r o p h y l l a s i t e i n d i c e s , as i n d i c a t o r o f s i t e p r o d u c t i v i t y ; and f i n a l l y t h e t o t a l o v e r l a p r a t i o was r e i n t r o d u c e d i n t h e model t o r e p r e sent t h e r e s i d u a l b i t s o f i n f o r m a t i o n due t o c o m p e t i t o r s  other  than  P_. m e n z i e s i i , T. p l i c a t a , and T., h e t e r o p h y l l a (Table 21, Model 7 ) . expected, ficant  t h e i n c l u s i o n o f t h e s e f o u r p r e d i c t o r s was v e r y h i g h l y s i g n i -  (Table 22, Model 7 v e r s u s Model 3 ) .  multiple correlation coefficients for  As  T h i s model g i v e s h i g h  (R = 0.87 f o r P_. m e n z i e s i i , R = 0.83  J_. p l i c a t a , and R = 0.71 f o r J_. h e t e r o p h y l l a ) , and i s w e l l s u i t e d t o  e s t i m a t e t h e y e a r l y DBH increment f o r these s p e c i e s over a l a r g e d i v e r s i t y of s i t u a t i o n s .  I n t e r e s t i n g l y enough, p r e d i c t o r s l i k e p a r t i a l and  t o t a l o v e r l a p s , and subzone l o c a t i o n a r e n o t s i g n i f i c a n t i n t h i s model (Appendix C, Model 7 ) , w h i l e they were s i g n i f i c a n t i n models where DBH and DBH/Age were n o t i n t r o d u c e d as p r e d i c t o r s . f i c a n t i n only h a l f o f the cases. by DBH  2  S i t e i n d i c e s were s i g n i -  The h i g h e s t p r e d i c t i v e power,  and DBH/Age, has a c l e a r b i o l o g i c a l meaning.  p r o p o r t i o n a l t o b a s a l a r e a and r e p r e s e n t s t r e e over i t s e n t i r e l i f e s p a n .  2  DBH  the cumulative  2  achieved  i s directly  growth o f t h e  DBH/Age g i v e s t h e average DBH increment  over t h e l i f e o f t h e t r e e and r e v e a l s t h e h i s t o r y o f i t s f a i l u r e s o r successes.  The p r e d i c t o r s c a r r y so much o f t h e p a s t growth h i s t o r y o f  the t r e e that other p r e d i c t o r s r e p r e s e n t i n g only present i n s i g n i f i c a n t i n comparison. in  conditions are  When t h e s t r o n g p r e d i c t o r s a r e n o t i n c l u d e d  t h e model, weak p r e d i c t o r s become s i g n i f i c a n t s i n c e they d e s c r i b e t h e  present regime.  c o n d i t i o n s t h r o u g h subzone l o c a t i o n , s i t e i n d e x , and c o m p e t i t i o n  134 M o r t a l i t y and r e g e n e r a t i o n a n a l y s i s . A l l dependent v a r i a b l e s mentioned above were s u b m i t t e d analyses  t o one-way  of v a r i a n c e t o t e s t f o r p o s s i b l e d i f f e r e n c e s among s p e c i e s  and  among s t a t u s (ingrowth,, l i v e , dead) o f stems w i t h i n each s p e c i e s . u s e f u l types of i n d i c a t o r s were found.  Two  M o r t a l i t y i n d i c a t o r s are v a r i a b l e s  t h a t show s i g n i f i c a n t d i f f e r e n c e s between l i v e and dead stems of the same age  and  s p e c i e s ; s i n c e some measurements were made j u s t b e f o r e  of t r e e s , i t i s p o s s i b l e t o compare each v a r i a b l e , DBH  the death  for instance,  between l i v e and dead stems and t o p r e d i c t the p r o b a b i l i t y of m o r t a l i t y of a l i v e stem whose v a l u e f o r t h a t v a r i a b l e approaches the average v a l u e o f dead stems.  R e g e n e r a t i o n i n d i c a t o r s are c o m p e t i t i o n  indices  t h a t show s i g n i f i c a n t d i f f e r e n c e s between s p e c i e s i n the c a t e g o r y ingrowth  stems; t h e y i n d i c a t e the c o n d i t i o n s under w h i c h a g i v e n  does and does not  of  the  species  regenerate.  Mortality indicators m e n z i e s i i i s the o n l y s p e c i e s whose dead stems show a  DBH  s i g n i f i c a n t l y s m a l l e r than the average f o r l i v e stems (Table 23). o v e r l a p r a t i o due  t o J_. p l i c a t a i s s i g n i f i c a n t l y s m a l l e r on dead stems  t h a n on l i v e ones w h i l e t h e o v e r l a p r a t i o due s i g n i f i c a n t l y l a r g e r on dead stems.  t o T. h e t e r o p h y l l a i s  This i n d i c a t e s that a surrounding  J_. h e t e r o p h y l l a i s g e n e r a l l y a s s o c i a t e d w i t h the s u p p r e s s i o n P_. m e n z i e s i i stems. preceding  The  The  average y e a r l y DBH  and death of  increment over the f i v e y e a r s  death i s s i g n i f i c a n t l y s m a l l e r , i n d i c a t i n g a p r o g r e s s i v e  r e d u c t i o n before death.  The  of  growth  average growth r a t e over the t o t a l l i f e s p a n  of the t r e e , DBH/Age, i s a l s o s i g n i f i c a n t l y s m a l l e r f o r dead stems, which s t r o n g l y s u g g e s t s a l o n g and p r o g r e s s i v e a c c u m u l a t i o n of the e f f e c t s of  135 INDICATOR  STATUS  Pm  Tp  Th  Aq  Ar  YINC  Live Dead F-ratio  2.7 .93 11 ***.  2.5 0.1 2.1 NS  1. 8 0.9 8.1***  1.8  . 84 -.5 4.0***  DBH  Live Dead F-ratio  234 175 12***  178 178 0.0 NS  165 182 1.1 NS  274 266 0. 1 NS  244 200 0.5 NS  DEH/AGE  Live Dead F-ratio  3.8 2.5 11***  2.9 2.2 0.5 NS  2.5 2.4 0.2 NS  4.8 4.8 0.0 NS  4.0 2.3 4.4 **  OFM  Live Dead F-ratio  . 36 . 36 0.0 NS  ,.49 ,. 51 0.0 NS  .42 .63 3.9 * *  .25 .67 1.8 NS  . 17 . 07 0.2 NS  OTP  Live Dead F-ratio  . 18 .04 3.7 **  „ 30 28 0.0 NS  . 20 .17 0.1 NS  . 05 .01 0.7 NS  .02 . 11 2.2 NS  OTH  Live Dead F-ratio  .18 .40 4.6 **  . 16 0.0 0.6 NS  .18 .10 1.4 NS  -  . 10 . 23 1.2 NS  Live Dead F-ratio  . 94 1.1 1.5 NS  1.6 2.7 2.4 NS  1.3 1.9 10***  1.1 2.5 12***  . 95 1.5 3.8 *  SIZES  TAELE  -  23  One-way a n a l y s i s of variance of m o r t a l i t y i n d i c a t o r s between l i v e a n d d e a d s t e m s . R e f e r t o T a b l e 21 f o r d e f i n i t i o n o f i n d i c a t o r s . Pm = P_. m e n z i e s i i , Tp = T. p i i c a t a Th = T. h e t e r o p h y l l a , Ag=A • g r a n d i s A r = A.. r u b r a . t  t  136 t h e neighborhood  competitors.  No m o r t a l i t y i n d i c a t o r shows any s t a t i s t i c a l s i g n i f i c a n c e i n the case o f X-  plicata.  However, t h e r e were o n l y f o u r dead J_. p l i c a t a stems  out of 377 o b s e r v a t i o n s .  The  low number o f o b s e r v a t i o n s i n t h i s c l a s s  i n d i c a t e s c l e a r l y t h a t t h e m o r t a l i t y i n J_. p l i c a t a o c c u r s P_. m e n z i e s i i , s i n c e the average age o f T. p l i c a t a i s not  l a t e r than i n significantly  lower than P_. m e n z i e s i i . Three i n d i c a t o r s are s i g n i f i c a n t f o r T. h e t e r o p h y l l a . y e a r l y increment  The  average  i n the f i v e y e a r s p r e c e d i n g death i s o n l y h a l f o f the  v a l u e f o r l i v e stems.  The  o v e r l a p r a t i o due t o P. m e n z i e s i i i s s i g n i f i -  c a n t l y l a r g e r on dead stems.  The h e i g h t r a t i o o f the c o m p e t i t o r s  s i g n i f i c a n t l y h i g h e r around d y i n g stems.  i s also  T h e r e f o r e stems which a r e over-  lapped and are s h o r t e r than the average, and w i t h a DBH  increment  smaller  than the average, d i e . The h e i g h t r a t i o i s the o n l y v a l i d i n d i c a t o r f o r A. g r a n d i s . t h e o v e r l a p r a t i o due  t o P_. m e n z i e s i i , a l t h o u g h not s t a t i s t i c a l l y  Yet signi-  f i c a n t , i s an i n d i c a t i o n t h a t P_. m e n z i e s i i o v e r l a p i s c o r r e l a t e d w i t h m o r t a l i t y i n A.  grandis.  The dead stems o f A. r u b r a show t h a t the average DBH  increment  over  t h e i r e n t i r e l i f e s p a n , DBH/Age, i s s i g n i f i c a n t l y s m a l l e r than f o r l i v e stems; t h i s i n d i c a t e s t h a t the c o m p e t i t i o n e f f e c t o f s u r r o u n d i n g was  a c t i n g f o r a long t i m e .  average DBH  increment  on the average, 1.5  stems  In the f i v e years p r e c e d i n g m o r t a l i t y , the  becomes n i l .  The  c o m p e t i t o r s around dead stems a r e ,  times as t a l l , as opposed t o 0.95  around l i v e stems.  137 Regeneration i n d i c a t o r s One-way a n a l y s i s o f v a r i a n c e among s p e c i e s i n d i c a t e s t h a t A. r u b r a regenerates  a new stem o n l y when t h e t o t a l o v e r l a p r a t i o i s near zero  (Table 2 4 ) .  T h i s c o n f i r m s t h e p i o n e e r r o l e o f A. r u b r a which was a l r e a d y  demonstrated i n t h e two p r e v i o u s c h a p t e r s . i n d i c a t e s that the competitors  The h e i g h t r a t i o f u r t h e r  a r e s h o r t e r , as would be expected  during  e a r l y stages of succession. P_. m e n z i e s i i a l s o r e q u i r e s low t o t a l o v e r l a p r a t i o t o grow a new stem.  The o v e r l a p r a t i o due t o P_. m e n z i e s i i , J_. h e t e r o p h y l l a , and J_. p l i -  cata, respectively, r e f l e c t s a g a i n s t P_. m e n z i e s i i .  t h e o r d e r i n which t h e s e s p e c i e s w i l l  compete  The h e i g h t r a t i o l a r g e r than 1 means t h a t o t h e r  stems were p r e s e n t b e f o r e or c o n c u r r e n t l y w i t h P_. m e n z i e s i i ; i t i s o n l y l o g i c a l t o suggest t h a t A. r u b r a was p r e c e d i n g i t . The next l e s s t o l e r a n t s p e c i e s i n r e g a r d t o t o t a l o v e r l a p i s T_. heterophylla.  Y e t t h e o v e r l a p r a t i o due t o P_. m e n z i e s i i suggests  t h i s l a t t e r s p e c i e s was p r e s e n t f i r s t and surrounds J_. h e t e r o p h y l l a .  that  t h e new stems o f  The h e i g h t r a t i o o f 2.0 i n d i c a t e s t h e head s t a r t o f  e a r l y i n v a d e r s , e i t h e r p r e c e d i n g o r growing f a s t e r than T_. h e t e r o p h y l l a . J_. p l i c a t a i s l e s s abundant as a neighbor p h y l l a , and w i l l p l a y i t s r o l e  o f t h e new stems o f J_. h e t e r o -  later.  Next i n o v e r l a p t o l e r a n c e i s A. g r a n d i s , which o c c u r s o n l y i n t h e Dry D o u g l a s - f i r Subzone. and no c o - o c c u r r e n c e i n t h e sample.  P_. m e n z i e s i i i s t h e r e f o r e i t s main  w i t h J_. p l i c a t a n o r w i t h T. h e t e r o p h y l l a  competitor was  The h e i g h t r a t i o c l a s s i f i e s A. g r a n d i s as a l a t e  l i k e l y t o succeed P_. m e n z i e s i i l o c a l l y .  observed  invader  138  INDICATOR  Pm  IP  Th  Ag  Ar  F- r a t i o  SDMOR  .53  .94  .76  . 93  . 02  20 .0 ***  OPM  .37  . 46  .45  . 93  .001  10 . 5 ***  OTP  . 18  .38  .16  .02  9 .7 ***  OTI1  . 32  .25  . 26  -  HR  1.2  2.2  2.0  1.7  .002 ' 2.9 ** .85  50 .0 ***  TABLE 24 One-way a n a l y s i s of v a r i a n c e of r e g e n e r a t i o n i n d i c a t o r s between s p e c i e s . Refer t o Table 21 f o r d e f i n i t i o n c f i n d i c a t o r s . Ingrowth data only were used i n t h i s a n a l y s i s . Pm= P.. m e n z i e s i i . Tp = T_• p l i c a t a . Th = T.. h e t e r o p h y l l a , Ag = A.. grand i s Ar = A.. rubra . t  139 The most t o l e r a n t r e g e n e r a t o r i n r e g a r d t o o v e r l a p i s J_. p l i c a t a which can r e g e n e r a t e even when 94% o f i t s zone o f i n f l u e n c e i s overlapped.  The most s e v e r e c o m p e t i t o r on a new  stem o f J_. p l i c a t a i s  P_. m e n z i e s i i , f o l l o w e d by T.- p l i c a t a and f i n a l l y J_. h e t e r o p h y l l a .  The  v e r y h i g h h e i g h t r a t i o f o r J_. p l i c a t a i n d i c a t e s t h a t a l l c o m p e t i t o r s a r e , on t h e average,  2.2  times as t a l l as t h e i n g r o w t h o f T. p l i c a t a .  This  h e i g h t r a t i o i s t h e l a r g e s t of a l l s p e c i e s , which suggests t h a t J_. p l i c a t a i s t h e s p e c i e s a b l e t o r e g e n e r a t e the l a t e s t i n the s t a n d .  This i s  an i n d i c a t i o n o f a v e r y h i g h shade t o l e r a n c e , and t h e r e f o r e , o f the presence  of J_. p l i c a t a i n t h e o l d e r v e g e t a t i o n .  t a t o t o l e r a t e a broad spectrum  The  c a p a c i t y o f T_- p l i c a -  of moisture conditions i s also a s e l e c t i v e  advantage f o r r e g e n e r a t i o n under dense c o v e r .  Succession trends A t y p i c a l dead stem o f P_. m e n z i e s i i has a s m a l l e r DBH average stem; i t s l i f e average DBH i t s DBH  increment  increment  than the  i s s m a l l e r t h a n l i v e stems;  i n t h e f i v e y e a r s p r e c e d i n g death i s v e r y s m a l l ; i t s  most s e v e r e c o m p e t i t o r s are J_. h e t e r o p h y l l a and P_. m e n z i e s i i stems, and t h e competing stems are t a l l e r . l i g h t exposure  P_. m e n z i e s i i i n g r o w t h r e q u i r e s good sun-  as i n d i c a t e d by i t s low t o l e r a n c e t o t o t a l o v e r l a p r a t i o ,  which makes i t a t y p i c a l p i o n e e r t o be succeeded species.  The r e q u i r e m e n t  by more s h a d e - t o l e r a n t  f o r good s u n l i g h t exposure  further  suggests  tolerance to d r i e r s i t e s . For A. r u b r a , the t y p i c a l dead stem has a l i f e average DBH s m a l l e r than l i v e stems; the DBH  increment  increment  i s h i g h l y reduced d u r i n g the  f i v e y e a r s p r e c e d i n g death and the dead stems are much s h o r t e r t h a n t h e  140 average.  The  slightly  ingrowth  stem does not t o l e r a t e any o v e r l a p and  s h o r t e r t h a n the s u r r o u n d i n g  stems.  Therefore,  i s only  among the sample  p l o t s , A. r u b r a . i s an e a r l y i n v a d e r which i s r a p i d l y r e p l a c e d by or c l i m a x s p e c i e s . I t was  I t competes w i t h o t h e r p i o n e e r s  serai  such as P_. m e n z i e s i i .  shown, i n Chapter I ( F i g u r e 5 ) , t h a t A. r u b r a can h o l d out P_.  m e n z i e s i i i n a s m a l l p r o p o r t i o n of the stands (< 5 % ) , u n t i l The  dead stems of T. h e t e r o p h y l l a do not show a l i f e average  increment any  s m a l l e r than o t h e r stems; t h e i r DBH  increment  m o r t a l i t y i s v e r y r e d u c e d ; t h e i r most s e v e r e c o m p e t i t o r s stems, and ingrowth  60.  DBH  preceding  are F_. m e n z i e s i i  the dead stems can be much s h o r t e r t h a n t h e i r c o m p e t i t o r s .  The  can t o l e r a t e a l a r g e amount of o v e r l a p , u s u a l l y p r o v i d e d by stems  of P_. m e n z i e s i i and  o l d e r T. h e t e r o p h y l l a stems, and grows i n deep shade,  w i t h high surrounding species  about age  competitors.  T. h e t e r o p h y l l a i s t h e r e f o r e a s e r a i  l i k e l y t o r e m a i n i n the c l i m a x v e g e t a t i o n , and  i s p r e c e d e d , on  t h e s e sample p l o t s , by A. r u b r a or _P. m e n z i e s i i , or b o t h . can a l s o be p r e s e n t  as a p i o n e e r  J_. h e t e r o p h y l l a  i f c o n d i t i o n s are u n s u i t a b l e f o r , or  t h e r e i s no seed s o u r c e of P. m e n z i e s i i . The  dead stems of A. g r a n d i s , on the sample p l o t s , have o n l y  one  c h a r a c t e r i s t i c w h i c h d i s t i n g u i s h e s them from the average l i v e stem: they are v e r y much s h o r t e r t h a n the s u r r o u n d i n g  stems.  The  ingrowth  can  t o l e r a t e a l a r g e amount of o v e r l a p , a l l coming from P_. m e n z i e s i i i n t h i s c a s e , and from stems which are much t a l l e r .  A. g r a n d i s was  found o n l y  i n the Dry D o u g l a s - f i r Subzone among the sample p l o t s and was l o c a l l y w i t h P_. m e n z i e s i i i n the o l d e r v e g e t a t i o n .  found  141 W i t h i n - t h e sample, t h e r e were o n l y f o u r dead stems o f J_. p l i c a t a and t h e y showed no s i g n i f i c a n t c h a r a c t e r i s t i c  (Tables 2 3 ) . Y e t t h i s  low m o r t a l i t y on p l o t s 114 y e a r s o l d i s i t s e l f an i n d i c a t i o n t h a t T. p l i c a t a w i l l p e r s i s t d u r i n g l a t e r s t a g e s o f s u c c e s s i o n .  The i n g r o w t h  shows a v e r y h i g h t o l e r a n c e t o o v e r l a p (Table 24); i t s main c o m p e t i t o r s are P_. m e n z i e s i i and o t h e r stems o f J_. p l i c a t a ; t h e h e i g h t o f t h e average c o m p e t i t o r c a n be v e r y much h i g h e r than t h e i n g r o w t h .  J_. p l i c a t a seems  t h e most shade t o l e r a n t among t h e f i v e s p e c i e s a n a l y s e d a t t h e stem l e v e l and i t o c c u p i e s a p l a c e i n t h e o l d e r v e g e t a t i o n i n p l o t s dominated by P_. m e n z i e s i i or J_. h e t e r o p h y l l a .  CONCLUSION There i s s t r o n g evidence t h a t t h e growth o f a s i n g l e stem i s a f f e c t e d by f o r e s t c o m p o s i t i o n i n i t s immediate neighborhood. growth increment  Diameter  i s a r e s u l t o f s i t e c o n d i t i o n s and c o m p e t i t i o n  b o t h p a s t and p r e s e n t .  regimes,  The c o n t r i b u t i o n o f p r e s e n t s i t e c o n d i t i o n s was  s t u d i e d through t r e e c o m p o s i t i o n , subzone l o c a t i o n , and s i t e i n d e x .  Pre-  sent c o m p e t i t i o n regime was e s t i m a t e d by c o m p e t i t i o n i n d i c e s w h i c h took i n t o account  t h e h o r i z o n t a l d i s t r i b u t i o n o f t h e crowns and r o o t s and t h e  v e r t i c a l d i s t r i b u t i o n o f t h e crowns o f a l l t r e e s p e c i e s .  I t was found  t h a t t h r e e s p e c i e s - P. m e n z i e s i i , J_. h e t e r o p h y l l a , and J_. p l i c a t a - were most i n d i c a t i v e o f c o m p e t i t i o n from crown and r o o t o v e r l a p s i n c e they r e p r e s e n t e d 92% o f t h e t o t a l stem abundance i n t h e sample p l o t s .  Cumu-  l a t i v e e f f e c t s o f p a s t s i t e c o n d i t i o n s and p a s t c o m p e t i t i o n regimes over  142 the l i f e s p a n o f a t r e e were r e f l e c t e d by DBH, DBH , and DBH/Age, w h i c h 2  were t h e b e s t p r e d i c t o r s f o r d i a m e t e r  increment.  E s t i m a t e s based on  p r e s e n t c o n d i t i o n s were found s i g n i f i c a n t o n l y when used a l o n e , the p r e d i c t o r s DBH  2  without  and DBH/Age.  No m a t t e r how s m a l l t h e c o m p e t i t i o n i n d i c e s were, and t h e r e f o r e sometimes s t a t i s t i c a l l y n o n - s i g n i f i c a n t , i t was t h e everyday impact c r e a t e d by d e t r i m e n t a l c o m p e t i t i o n w h i c h , i n t h e long r u n , cumulated i n terms o f s m a l l DBH and s m a l l DBH i n c r e m e n t .  Although  subzone l o c a t i o n  and o v e r l a p r a t i o s were s i g n i f i c a n t , i n t h e absence o f s t r o n g e r p r e d i c t o r s , t h e i r i n t e r a c t i o n was n o t s i g n i f i c a n t .  T h i s i n d i c a t e s t h a t t h e mechanism  of c o m p e t i t i o n might be t h e same i n a l l subzones, and t h a t d i f f e r e n c e s i n v e g e t a t i o n between subzones would be due t o o t h e r f a c t o r s , such as s o i l and c l i m a t e o f t h e subzone r e g u l a t i n g t h e a v a i l a b i l i t y o f s o l a r r a d i a t i o n , w a t e r , and n u t r i e n t s . R e g r e s s i o n models r e v e a l e d t h a t DBH, DBH , and DBH/Age were t h e 2  best p r e d i c t o r s of present diameter  increment;  the a n a l y s i s of m o r t a l i t y  showed t h a t a h i g h c o m p e t i t i o n i n d e x , a DBH below average, and a diameter increment  below average were good i n d i c a t o r s o f m o r t a l i t y .  are s i m i l a r t o those o f Monserud (1976) who found t h a t DBH, increment,  These r e s u l t s diameter  and c o m p e t i t i o n index were t h e b e s t v a r i a b l e s t o d i s t i n g u i s h  between l i v e and dead stems, a l t h o u g h t h e m o r t a l i t y f u n c t i o n he d e r i v e d from them was not s p e c i e s - s p e c i f i c .  M o r t a l i t y and r e g e n e r a t i o n i n d i c a t o r s  were s t r o n g l y c o r r e l a t e d w i t h f o r e s t c o m p o s i t i o n and s t r u c t u r e  (geometric  p o s i t i o n o f each t r e e and d i s t r i b u t i o n s o f DBH and h e i g h t ) , and were species-specific.  P i o n e e r and s e r a i s p e c i e s c o u l d be r e c o g n i z e d on  143 the b a s i s o f t h e i r t o l e r a n c e t o f o r e s t c o m p o s i t i o n and s t r u c t u r e i n t h e i r surroundings.  The  c o r r e l a t i o n between h i g h c o m p e t i t i o n i n d i c e s  and m o r t a l i t y , and between low c o m p e t i t i o n i n d i c e s and r e g e n e r a t i o n i n a s p e c i e s - s p e c i f i c manner p o i n t s out a mechanism more l i k e l y dependent on the l o c a l c o m p e t i t i o n regime around each stem than on s i t e f a c t o r s . S t a r t i n g from an assumed equal seed d i s t r i b u t i o n , s i t e c o n d i t i o n s a l l o w o n l y some s p e c i e s t o grow a t f i r s t , and s i n c e c o m p e t i t i o n i s v e r y severe on t h e s e e a r l y i n v a d e r s , t h e i r d e n s i t y decreases multaneously,  quickly. S i -  shade c o n d i t i o n s ( s e t by f o r e s t c o m p o s i t i o n and s t r u c t u r e )  d e t e r m i n e p r o b a b i l i t i e s o f r e g e n e r a t i o n o f these s p e c i e s and i n v a s i o n by other s p e c i e s .  T h i s mechanism a p p l i e s t o the lowest l e v e l o f the f o r e s t  p o p u l a t i o n , a s i n g l e t r e e , and i t s e f f e c t s produce s u c c e s s i o n as can  be  observed  A-  at the p l o t l e v e l and a t the B i o g e o c l i m a t i c Subzone l e v e l .  b i o t i c c h a r a c t e r i s t i c s o f the subzone d e t e r m i n e f o r e s t c o m p o s i t i o n which c o m p e t i t i o n shapes the t r e n d o f s u c c e s s i o n by a mechanism dent o f the subzone.  from  indepen-  I t i s , t h e r e f o r e , u n n e c e s s a r y t o i n v o k e more com-  p l e x e x p l a n a t i o n s t o l i n k t o g e t h e r s i g n i f i c a n t i n t e r a c t i o n s from the s i n g l e t r e e t o the e n t i r e subzone.  144 LITERATURE CITED  Arney, J.D. 1972. Computer s i m u l a t i o n o f D o u g l a s - f i r t r e e and stand growth. Can. F o r . S e r . Pac. F o r . Res. Cen. I n t . Rep. BC-27. 79 p. B e l l a , I.E. 1969. C o m p e t i t i v e i n f l u e n c e - z o n e o v e r l a p : a c o m p e t i t i o n model f o r i n d i v i d u a l t r e e s . Can. Dept. F i s h . F o r . B i monthly Res. Notes 25: 24-25. B e l l a , I.E. 1971. A new c o m p e t i t i o n model f o r i n d i v i d u a l t r e e s . F o r . S c i . 17: 364-372. B o t k i n , D.B., J . F . J a n a k , and J.R. W a l l i s . 1970. The r a t i o n a l , l i m i t a t i o n s and assumptions o f a N o r t h e a s t F o r e s t Growth S i m u l a t o r . I.B.M. R e s e a r c h Report #RC 3188. Yorktown H e i g h t s , New York. 39 p. C l u t t e r , J . L . 1963. Compatable growth and y i e l d models f o r L o b l o l l y pine. F o r . S c i . 9: 354-371. Dansereau, P. 1957. Biogeography: An e c o l o g i c a l p e r s p e c t i v e . P r e s s , New Y o r k . 394 p. Decker, J.P. 1959. A system f o r a n a l y s i s o f f o r e s t s u c c e s s i o n . S c i . 5: 154-157.  Ronald For.  Duncan, W.B., R.S. Loomis, W.A. W i l l i a m s , and R. Hanau. 1967. A model f o r s i m u l a t i n g p h o t o s y n t h e s i s i n p l a n t communities. H i l g a r d i a 38: 181-205. F r a n k l i n , J . F . , L . J . Dempster, and R.H. Waring. 1972. ( e d . ) . Research on c o n i f e r o u s f o r e s t ecosystems - a symposium. U.S.D.A. F o r e s t S e r v i c e . P o r t l a n d , Oregon. 322 p. G o u l d i n g , C.J. 1972. S i m u l a t i o n t e c h n i q u e s f o r a s t o c h a s t i c model o f the growth o f D o u g l a s - f i r . Ph.D. t h e s i s . F a c u l t y o f F o r e s t r y , U.B.C. 234 p. Hesketh, J.D., and J.W. J o n e s . 1976. Some comments on computer t o r s f o r p l a n t s . E c o l . Model. 2: 235-247  simula-  Honer, T.G. 1972. A team approach t o s i m u l a t o r r e s e a r c h and development w i t h i n t h e Canadian F o r e s t r y S e r v i c e , pages 109-114 i n : P r o c e e d i n g s : t r e e growth s i m u l a t i o n workshop. T.G. Honer, ed. F o r . Man. I n s t . Rep. FMR-25. Ottawa. 116 p.  145 Jaquette,  D.L. 1972. M a t h e m a t i c a l models f o r c o n t r o l l i n g growing b i o l o g i c a l p o p u l a t i o n s : a s u r v e y . O p e r a t i o n R e s e a r c h . 20: 1142-1151.  K r a j i c e k , J.E., K.A. Brinkman, and S.F. G i n g r i c h . 1961. Crown c o m p e t i t i o n a measure o f d e n s i t y . F o r . S c i . 7: 35-42. Lee, J.Y. 1967. Stand models f o r l o d g e p o l e p i n e and l i m i t s t o t h e i r a p p l i c a t i o n . Ph.D. t h e s i s . F a c u l t y o f F o r e s t r y , U.B.C. 182 p. M a r t i n , G.L., A.R. Ek, and R.A. Monserud. 1977. C o n t r o l o f p l o t edge b i a s i n f o r e s t stand growth s i m u l a t i o n models. Can. J . F o r . Res. 7 : 100-105. M c K i n i o n , J.M., J.W. J o n e s , and J.D. Hesketh. 1975. A system o f growth e q u a t i o n s f o r t h e c o n t i n u o u s s i m u l a t i o n o f p l a n t growth. T r a n s , of t h e ASAE. 18: 975-984. Mead, R. 1968. Measurement o f c o m p e t i t i o n between i n d i v i d u a l p l a n t s i n a population. J . E c o l . 56: 35-45. M i l l e r , R.S. 1967. P a t t e r n and p r o c e s s i n c o m p e t i t i o n , pages 1-74 i n : Advances i n e c o l o g i c a l r e s e a r c h . J.B., C r a g g , ed. Academic P r e s s . London and New York. 311 p. M i t c h e l l , K.J. 1969. S i m u l a t i o n o f t h e growth o f even-aged stands o f w h i t e s p r u c e . . B u l l . No. 75. Y a l e U n i v . Sch. F o r . New Haven, C o n n e c t i c u t . 48 p. M i t c h e l l , K.J. 1971. D e s c r i p t i o n and growth s i m u l a t i o n o f D o u g l a s - f i r s t a n d s . Can. F o r . Ser. P.P.R.C. I n t . Rep. BC-25. Monserud, R.A. 1976. S i m u l a t i o n o f f o r e s t t r e e m o r t a l i t y . 22: 438-444.  Forest S c i .  Monserud, R.A. and A.R. Ek. 1974. P l o t edge b i a s i n f o r e s t stand s i m u l a t i o n models. Can. J . F o r . Res. 4: 419-423.  growth  Moore, J.A., C A . B u d e l s k y , and R.C. S c h l e s i n g e r . 1973. A new i n d e x r e p r e s e n t i n g i n d i v i d u a l t r e e c o m p e t i t i v e s t a t u s . Can. J . F o r . Res. 3: 495-500. Munro, D.D. 1973. M o d e l l i n g f o r managed s t a n d s . p r o j e c t #65-6872. 22 p.  B.C.F.S. Report on  N e l s o n , T.C. 1965. Growth models f o r stands o f mixed s p e c i e s P r o c . Soc. Am. F o r e s t e r s M e e t i n g 1964: 229-231.  composition.  Newnham, R.M. 1964. The development o f stand model f o r D o u g l a s - f i r . Ph.D. t h e s i s . F a c u l t y o f F o r e s t r y , U.B.C. 201 p.  146 i  O p i e , J . E . 1968. P r e d i c t a b i l i t y o f i n d i v i d u a l t r e e growth u s i n g v a r i o u s d e f i n i t i o n s o f competing b a s a l a r e a . For. S c i . 14: 314-323. P a i l l e , G. 1970. D e s c r i p t i o n and p r e d i c t i o n o f m o r t a l i t y i n some c o a s t a l D o u g l a s - f i r s t a n d s . Ph.D. t h e s i s . F a c u l t y o f F o r e s t r y , U.B.C. 300 p. P i c k e t t , S.T.A. 1976. S u c c e s s i o n : an e v o l u t i o n a r y i n t e r p r e t a t i o n . Amer. N a t u r . 110: 107-119. Smith, S. 1973. A r e v i e w and e v a l u a t i o n o f m a t h e m a t i c a l programming and computer s i m u l a t i o n a p p l i e d t o whole f o r e s t s and i n d i v i d u a l f o r e s t stands. Report t o t h e P r o d u c t i v i t y Committee o f t h e B.C.F.S. U n p u b l i s h e d m a n u s c r i p t . 49 p. S t e r n , W.R. 1965. The e f f e c t o f d e n s i t y on t h e performance o f i n d i v i d u a l p l a n t s i n s u b t e r r a n e a n c l o v e r swards. A u s t . J . A g r i c . Res. 16: 541-555. S t e w a r t , F.M. and B.R. L e v i n . 1973. P a r t i t i o n i n g o f r e s o u r c e s and t h e outcome o f i n t e r s p e c i f i c c o m p e t i t i o n : a model and some g e n e r a l c o n s i d e r a t i o n s . Am. N a t . 107: 171-198. S t o u t , B.B., J.M. Deschenes, and L'.F. Ohmann. 1975. M u l t i - s p e c i e s models o f a deciduous f o r e s t . E c o l . 56: 226-231. V e z i n a , P.E. 1963. More about t h e "crown c o m p e t i t i o n Chron. 39:. 313-317.  f a c t o r . " For.  Waggoner, P.E. and W.E. R e i f s n y d e r . 1968. S i m u l a t i o n o f t h e t e m p e r a t u r e , h u m i d i t y and e v a p o r a t i o n p r o f i l e s i n a l e a f canopy. J.Appl. Meteor. 7: 400-409. Whittaker,  R.H., F.H. Bormann, G.E. L i k e n s , and T.G. Siccama. 1974. The Hubbard Brook ecosystem s t u d y : f o r e s t biomass and production. E c o l . Monogr. 44: 233-252.  A n a l y s i s and m o d e l l i n g o f i n t e r s p e c i e s c o m p e t i t i o n d u r i n g f o r e s t secondary s u c c e s s i o n .  Pierre Bellefleur  CHAPTER IV  S y n t h e s i s and c o n c l u s i o n .  148  The p e r c e p t i o n o f s u c c e s s i o n a t the B i o g e o c l i m a t i c Subzone l e v e l r e q u i r e d o b s e r v a t i o n s over a l o n g p e r i o d o f t i m e . r e s o l u t i o n was  The l e v e l o f  r a t h e r broad and the o b s e r v a t i o n s r e v e a l e d  r a t h e r than d e t a i l s .  trends  P i o n e e r and s e r a i r o l e s o f s p e c i e s c o u l d be  i d e n t i f i e d i n each subzone, a l t h o u g h the r a t e s o f change might have been exaggerated  due  to u n e q u a l sampling  i n t e n s i t y over space.  models were u n a b l e t o d u p l i c a t e the observed c o m p o s i t i o n i n adequate d e t a i l .  Markov  changes i n t r e e s p e c i e s  The major problems t h a t were u n s o l v e d  at t h i s l e v e l were l i n k e d w i t h the v a r i a b i l i t y i n t h e k i n d s o f d i s t u r bance w h i c h i n i t i a t e d s u c c e s s i o n , i n the types o f communities, and i n the k i n d s of s i t e s , and were f u r t h e r l i n k e d w i t h t h e p r o b a b i l i t y o f species invasion.  T h e r e f o r e , t h i s l e v e l of i n t e r p r e t a t i o n appeared  e s s e n t i a l l y g l o b a l and d e s c r i p t i v e and d i d not suggest any p o p u l a t i o n dynamic mechanisms.  I t s main v a l u e was  specific  the o v e r v i e w  provided  f o r each subzone and the comparison o f p a t t e r n s of s u c c e s s i o n among them. Observations immediately communities.  a t the p l o t l e v e l made the community s t r u c t u r e  o b v i o u s , no m a t t e r what scheme was Tree c o m p o s i t i o n was  t i e s s i n c e i t was  used t o d i s c r i m i n a t e between communi-  the o n l y p o s s i b l e way  d a t a on u n d e r s t o r y v e g e t a t i o n .  used t o c l a s s i f y  t o do so i n the absence of  I n a d d i t i o n , t h i s way  of d e f i n i n g  communities o f f e r e d the advantage o f s i m p l i c i t y and f i e l d The  practicability.  growth of any g i v e n s p e c i e s c o u l d be c l e a r l y seen t o v a r y from  one  community t o a n o t h e r ; t h i s performance appeared to be s u b z o n e - s p e c i f i c . Trends i n s p e c i e s s u c c e s s i o n c o u l d be i n f e r r e d o n l y i n d i r e c t l y a t t h i s  149  l e v e l , but  they c o i n c i d e d c l o s e l y w i t h those observed at  B i o g e o c l i m a t i c Subzone l e v e l .  The  the  long-term overview provided  the B i o g e o c l i m a t i c Subzone l e v e l was,  by  however, l o s t a t the p l o t l e v e l .  On the o t h e r hand, some mechanism o f s p e c i e s replacement through e i t h e r f a c i l i t a t i o n or i n h i b i t i o n emerged more or l e s s c l e a r l y , growth was  a f f e c t e d by t r e e c o m p o s i t i o n w h i c h , i n t u r n , was  by s i t e f a c t o r s and by i n t r a - and l e v e l o f i n t e r p r e t a t i o n was  affected  interspecies competition.  s u p e r i o r t o the B i o g e o c l i m a t i c  since  The  plot  Subzone  l e v e l i n i t s a b i l i t y t o r e v e a l the s t r u c t u r e of communities and r o l e they p l a y i n p r o m o t i n g s p e c i e s Unfortunately, f a c t o r s , i t was  due  replacement.  to the absence of a p p r o p r i a t e  d a t a on  site  not p o s s i b l e to t e s t whether or not a b i o t i c f a c t o r s  such as m i c r o c l i m a t e ,  s o i l heterogeneity,  and  l o c a l topography  a more i m p o r t a n t r o l e t h a n p l a n t t o p l a n t i n t e r a c t i o n s .  played  I t seemed t h a t  t h i s problem c o u l d be s o l v e d e i t h e r by f i e l d e x p e r i m e n t a t i o n observations  the  or  by  a t a l e v e l of i n t e r p r e t a t i o n where s i t e f a c t o r s c o u l d  be  k e p t r e l a t i v e l y homogeneous. With present inventory techniques of v e g e t a t i o n sample p l o t s had  sampling,  to be chosen t o be r e l a t i v e l y homogeneous t o  t y p i c a l communities and  t o maximize d i f f e r e n c e s between them.  o f f e r e d the i n v a l u a b l e advantage of e n s u r i n g t h e s i t e f a c t o r s w i t h i n any  represent This  a c e r t a i n c o n s t a n c y of  sample p l o t and made i t r e a s o n a b l e t o assume  t h a t a l l t r e e s of a p l o t were s u b j e c t t o the same a b i o t i c c o n d i t i o n s . I t was  shown t h a t s u p p r e s s i o n  and m o r t a l i t y of t r e e s was  dependent upon the c o m p o s i t i o n of the s u r r o u n d i n g  trees.  strongly  Dead stems  150  showed a h i s t o r y o f s u b - s t a n d a r d c o m p e t i t i o n from i t s n e i g h b o r s  growth which was  correlated with  s u g g e s t i n g t h a t the a c c u m u l a t i o n  of  d e t r i m e n t a l e f f e c t s produced a s t r e s s w h i c h , i n the l o n g r u n , l e d to below-average growth.  The c o n d i t i o n s f o r r e g e n e r a t i o n were a l s o  determined by the n e i g h b o r i n g v e g e t a t i o n and t h o s e c o n d i t i o n s w h i c h were a s s o c i a t e d w i t h the m o r t a l i t y o f a t r e e of a g i v e n s p e c i e s c o u l d be a s s o c i a t e d w i t h the r e g e n e r a t i o n of a n o t h e r o f i n t e r p r e t a t i o n , i t was  species.  At t h i s  a l s o p o s s i b l e t o show t h a t the b e s t  level  growth  p r e d i c t o r s r e f l e c t e d the past h i s t o r y o f the t r e e , w h i c h i s , not s u r p r i s i n g l y , a non-Markovian c o n c l u s i o n .  T h i s g e n e r a l mechanism o f  s e l e c t i v e s u p p r e s s i o n and s e l e c t i v e replacement o f stems seemed, f u r t h e r m o r e , the same from one subzone t o the o t h e r .  The d i f f e r e n c e s  i n v e g e t a t i o n between subzones s h o u l d then be due t o o t h e r  factors,  such as the a v a i l a b i l i t y o f s o l a r r a d i a t i o n , w a t e r , and n u t r i e n t s . The  i n t e r p r e t a t i o n a t t h e i n d i v i d u a l t r e e l e v e l was  w h i c h suggested w h i c h was  the o n l y  one  a mechanism, b r o a d l y d e s c r i b e d as i n t e r - t r e e c o m p e t i t i o n ,  a b l e t o account f o r changes i n the net r a t e of change of  p o p u l a t i o n s through m o r t a l i t y and r e g e n e r a t i o n .  T h i s mechanism i s  r e s p o n s i b l e f o r the r e p e a t a b l e sequence o f dominant s p e c i e s observed the two h i g h e r l e v e l s of i n t e r p r e t a t i o n .  Whether c o m p e t i t i o n can  q u a l i f i e d as a "mechanism" i s d e b a t a b l e .  I f one l o o k s a t i t from a  p h y s i o l o g i c a l v i e w p o i n t , concepts  at  be  such as n u t r i e n t c y c l i n g , i o n exchange  c a p a c i t y , and a l l e l o p a t h i c substances  would suggest more hypotheses  on t h e c h e m i c a l mechanics o f i n h i b i t i o n and f a c i l i t a t i o n .  This,  151  however, i s beyond the scope o f t h i s study w h i c h meant t o i n v e s t i g a t e t h e f o r e s t from the p o p u l a t i o n dynamics v i e w p o i n t .  From t h i s v i e w ,  c o m p e t i t i o n i s indeed a mechanism s i n c e i t accounts  f o r p a r t o f the  f o r c e s b e h i n d m o r t a l i t y and r e g e n e r a t i o n o f s p e c i e s .  I t was  not  p o s s i b l e to demonstrate t h a t f a c i l i t a t i o n mechanisms r a t h e r than i n h i b i t o r y mechanisms such as c o m e p t i t i o n a r e n e c e s s a r y secondary s u c c e s s i o n .  to e x p l a i n  152 APPENDIX A Species names used  i n the a n a l y s e s ( a f t e r  CODE EOTANICAL NAME  K r a j i n a 1969)  ENGLISH NAME  Aa  Jbies amabilis  A9"  Abies g r a n d i s (Dougl.)  Am  Acer macrophyllum  Ar  Alnus r u b r a Bcng.  Red  Arbutus m e n z i e s i i Pursh  P a c i f i c madrona  Corn us n u t t a l l i i  Audubon  Western f l o w e r i n g dcqwood  Ps  Picea s i t c h e n s i s  (Bcnq.) Carr  Sitka  Pc  Pinus c o n t o r t a Pinus m c n t i c c l a  (Dougl.)  Porbes Lindl.  Pursh  Douql.  Pseudotsu,ga  Douql.  menziesii  Grand f i r Broadleaf maple alder  spruce  Lcdgepcle pine Western white pine  Prunus emarcjinajra Dougl. Pm  Amabilis f i r  Bitter  cherry  (Mirb. ) Franco D c u g l a s - f i r  puercus garryana Dougl.  Garry oak  Tp  Thuja p l i c a t a Donn  Western redcedar  Th  Tsu<ja h e t e r o p h y l l a  (Raf.) Sarg.  Western hemlcck  153 IPPJIDIX  B  T r a n s i t i o n m a t r i c e s used i n the Markov models. Bows and columns r e p r e s e n t stand types i n the order of the s p e c i e s l i s t . O b s e r v a t i o n s and estimates are counts. Transitions are p r o b a b i l i t i e s of moving from the column standtype t o the row stand-type i n a time i n t e r v a l of five years,. The t r a n s i t i o n matrix has been mult i p l i e d hy 103.  SPECIES'. THUJA PLICATA ALNUS RUBRA PSEUDOTSUGA MENZIESII PINUS CONTORTA BASAL AREA  STEMS  OBSERVATIONS:  9 0 0 0  0 3 0 0  1 0 0.0 103 0 0 9  1 0 0 0  0 4 0 0  0 1 111 0  0 0 0 8  9  3  104  9  1  4  112  8  9 0 0 0  1 5 2 0 0 95 0 4  0 0 0 9  1 0 0 0  0 3 0 2 0 106 3 1  0 0 0 8  9  3  9  1  4  8  ESTIMATES'.  104  112  TRANSITIONS'.  1000 0 0 0  115 885 0 0  30 0 0 0 950 0 20 1000  1000 1000 1000 1000  DO 400 0 500 0 0 0 100  0 0 15 0 0 970 15 1000  1000 1000 1000 1000  1. DRY DOUGLAS*FIR SUBZONE.  155 ; 5 3 3 S 3 3 ! : : i I I I = S 3 ! 3 I 5 3 2 S r J 3 3 5 S 5 3 S r 3  SPECIES: PSEUDOTSUGA MENZIESII TSUGA HETEROPHYLLA THUJA PLICATA ALNUS RUBRA ABIES GRANDIS ACER MACROPHYLLUM PICEA SITCHENSIS BASAL AREA  STEMS  OBSERVATIONS: 211 5 2 0 0 0 0  3 53 2 0 0 0 0  0 1 38 0 1 0 0  0 0 0 3 0 0 0  1 0 1 0 3 0 0  0 0 0 0 0 2 0  0 0 0 0 0 0 1  248 1 1 0 0 0 0  0 42 0 0 0 0 0  0 1 20 0 0 0 0  0 0 0 3 0 0 0  0 0 0 0 2 0 0  0 0 0 0 0 1 0  0 0 0 0 0 0 7  218  58  40  3  5  2  1  250  42  21  3  2  1  7  ST MATES: 180 30 8 0 0 0 0  3 53 2 0 0 0 0  0 1 24 0 15 0 0  0 2 0 2 0 0 0  0 0 1 0 4 0 0  0 0 0 0 0 2 0  0 0 0 0 0 0 1  228 1 21 0 0 0 0  0 29 0 0 0 0 13  0 1 20 0 0 0 0  3 0 0 0 0 0 0  0 0 0 0 2 0 0  0 0 0 0 0 1 0  0 0 0 0 0 0 7  218  58  40  3  5  2  1  250  42  21  3  2  1  7  100 0 0 0 0 0 200 0 0 0 0 0 700 0 0 0 1000 0 0 0 1000  952 4 44 0 0 0 0  0 850 0 0 0 0 150  0 50 950 0 0 0 0  RANSITIONS: 896 80 24 0 0 0 0  52 914 34 0 0 0 0  0 25 775 0 200 0 0  0 250 0 750 0 0 0  1000 1000 1000 1000 1000 1000 1000  500 0 0 0 0 0 0 0 0 0 0 0 500 0 0 0 0 1000 0 0 0 1000 0 0 0 0 0 1000  1000 1000 1000 1000 1000 1000 1000 3 2 2 3 3 3 3 3 3 = 3 = 3 = ;: = 3 3 3 3 . 3 3 3 3 3 2 3 2 3 2 3 3 3 3  2. WET DOUGLASnFIR SUBZONE.  SPECIES:: PSEUDOTSUGA MENZIESII ALNUS RUBRA TSUGA HETEROPHYLLA THUJA PLICATA ABIES GRANDIS  STEMS  BASAL AREA  OBSERVATIONS'.  100 0 2 0  1 0 5 0 0 129 0 3 0 0  0 0 0 2 0  0 0 0 0 3  145 0 5 1 0  0 3 0 0 0  2 0 89 0 0  0 0 0 1 0  0 0 0 0 4  106  6 132  2  3  151  3  91  1  4  2 0  0 1 5 0 0 129 0 3 0 0  0 0 1 1 0  0 0 0 0 3  145 0 5 1 0  0 2 0 0 1  4 0 87 0 0  0 0 0 1 0  4 0 0 0 0  106  6 132  2  3  151  3  91  1  4  ESTIMATES:  98 0 6  TRANSITIONS'.  0 0 933 167 0 0 0 0 0 833 0 48 0 977 200 0 23 800 0 19 0 0 0 0 1000  960 0 32 0 500 0 800 0 0 0 33 0 968 0 0 7 0 0 1000 0 0 200 0 0 500  1000 1000 1000 1000 1000  1000 1000 1000 1000 1000  333233333223332222333332333332333332233233233333233333333333333  3. DRY WESTERN HEMLOCK SUBZONE.  SPECIES'. TSUGA HETEROPHYLLA THUJA PLICATA ABIES AMABILIS PICEA SITCHENSIS ALNUS RUBRA BASAL AREA  STEMS  OBSERVATIONS: 249 0 0 1 0  0 10 0 0 0  0 0 39 0 0  1 1 0 21 0  0 0 0 0 4  234 0 0 3 0  0 13 0 1 0  0 1 34 0 0  0 0 0 33 0  0 0 0 0 4  250  10  39  23  4  237  14  35  33  4  ESTIMATES: 249 0 0 1 0  0 6 4 0 0  0 0 39 0 0  1 1 5 16 0  1 0 0 0 3  234 0 0 3 0  0 13 0 1 0  4 1 30 0 0  0 0 20 13 0  0 0 0 0 4  250  10  39  23  4  237  14  35  33  4  0 0 800 0 200 1000 0 0 0 0  43 43 100 814 0  100 0 0 0 900  987 0 0 13 0  0 929 0 71 0  50 29 921 0 0  UNSITIONS: 996 0 0 4 0  1000 1000 1000 1000 1000  0 0 0 0 300 0 700 0 0 1000  1000 1000 1000 1000 1000  4. WET WESTERN HEMLOCK SUBZONE.  SPECIES'. TSUGA HETEROPHYLLA THUJA PLICATA  STEMS  BASAL AREA  OBSERVATIONS'.  17 0  0 3  17 0  0 3  17  3  17  3  ESTIMATES'.  17 0  3 0  17 0  3 0  17  3  17  3  TRANSITIONS'.  1000 550 0 450  1000 550 0 450  1000 1000  1000 1000  5. FOG WESTERN HEMLOCK SUBZONE.  APPENDIX  159  C  P a r t i a l r e g r e s s i o n c o e f f i c i e n t s (B) and F - r a t i o s f o r Model 5 and Model 7_ In a l l cases F(0.05) = 5.02 and F(0.01) = 7,88  MODEL 5 Y = K  + DBH + AGE + OPM + OTP + OTH  F. m e n z i e s i i E: F:  4.7 253  .014 628  2-3 44  .019 310  1- h e t e r o p h y l l a E: F:  2.7 152  APPENDIX C.  -.075 -- 65 454 25  0.26 3-3  R2 = 0.486  1- p l i c a t a E: F:  0.631  .009 176  -.044 -. 30 2- 5 97  -.58 11  R2 = 0.413  -.032 -. 42 142 18  df - 1, 664 .083 -670 df = 1, 384 .290 1. 1 df = 1, 405  0.085 -. 32 0-6 5. 1  160  (Cont'd) MODEL  7  Y = K  + DBH + EBH + DBH +SUMOR+ OPM + OTP + OTH /AGE + FSITE+HSITE+ CDF + WDF + DWH + WWH 2  P. m e n z i e s i i D: F:  -.33 -.03 0.42 1.2  .004 -.03 5.03 1.8  -.001 -.25 7.0 .38  T. p l i c a t a B: F:  1.80 -.09 4.6 4.1  0.017 -.12 26 6.3  T. h e t e r o p h y l l a B: F:  .079 -.09 .04 19  .009 .059 8.9 7.2  -.002 0.27 17 .22  P.* ~ 0.765  df = 1, 656  1-04 -.28 0. 14 -. 29 52 9 5. 4 . 13 -57  -. 19 0. 40 2.3 1.0  B  df=1.  2  = 0-684  1- 1 1- 4 219 7. 3 H  2  -. 27 -1.1 1. 9 3.9  = 0.506  -.002 .9 1 -. 19 14 16 9 -81  -- 06 -.46 0. 16 6. 1  0-07  -.03  -32  0. 10  376  0. 18 -. 11 -. 6 0. 58 .43 1. 1  --02 .007  df = 1, 398 -.36 1. 1 4.0 .33  -. 03  -.34  .05  3.9  

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