STATISTICAL ANALYSIS OF TREE GROWTH AND SOME ENVIRONMENTAL FACTORS OF PLANT COMMUNITIES IN A SELECTED AREA OF THE COASTAL WESTERN HEMLOCK ZONE by SLAVOJ EIS D i p l . For. Eng., Prague Tech. Univ., 19^8 A THESIS SUBMITTED IN PARTIAL FULFILMENT OF THE REQUIREMENTS FOR THE DEGREE OF DOCTOR OF PHILOSOPHY i n the Department of BIOLOGY AND BOTANY 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 standard THE UNIVERSITY OF BRITISH COLUMBIA November, 1961 In p r e s e n t i n g t h i s t h e s i s i n p a r t i a l f u l f i l m e n t o f the requirements f o r an advanced degree a t the U n i v e r s i t y o f B r i t i s h Columbia, I agree t h a t the L i b r a r y s h a l l make i t f r e e l y a v a i l a b l e f o r r e f e r e n c e and study. I f u r t h e r agree t h a t p e r m i s s i o n f o r e x t e n s i v e copying of t h i s t h e s i s f o r s c h o l a r l y purposes may be granted by the Head o f my Department o r by h i s . r e p r e s e n t a t i v e s . I t i s understood t h a t copying or p u b l i c a t i o n o f t h i s t h e s i s f o r f i n a n c i a l g a i n s h a l l not be a llowed without my w r i t t e n p e r m i s s i o n . Department o f B i o l o g y and Botany The U n i v e r s i t y of B r i t i s h Columbia, Vancouver Canada. Date A p r i l 10, 1962 GRADUATE STUDIES F i e l d of Study: Forest Ecology Forest Synecology Forest Autecology Plant Physiology Taxonomy of Higher Plants Other Studies: S i l v i c u l t u r e Biometry S o i l Genesis S o i l Chemistry S o i l & Plant Relations V.J. Krajina V.J. Krajina D.J. Wort T.M.C. Taylor P.G. Haddock; J.C. Sawyer C.A. Rowles J.S. Clark J.D. Beaton The U n i v e r s i t y of B r i t i s h Columbia FACULTY OF GRADUATE STUDIES PROGRAMME OF THE FINAL ORAL EXAMINATION for the Degree of DOCTOR OF PHILOSOPHY of SLAVOJ EIS D i p l . For. Eng.(Technical U n i v e r s i t y , Prague,) 1948 WEDNESDAY, MARCH 28th, 1962, at 2:00 P.M. IN ROOM 2211, BIOLOGICAL SCIENCES BUILDING COMMITTEE IN CHARGE Chairman F.H. Soward J.E. BIER R.F. SCAGEL P.G. HADDOCK W.B. SCHOFIELD S.W. NASH T.M.C. TAYLOR' C.A. ROWLES R.W. WELLWOOD D.J. WORT External Examiner: Dr. R.T. Coupland Department of Plant Ecology Uni v e r s i t y of Saskatchewan STATISTICAL ANALYSIS OF TREE GROWTH AND SOME ENVIRONMENTAL FACTORS OF PLANT COMMUNITIES IN A SELECTED AREA OF THE COASTAL WESTERN HEMLOCK ZONE ABSTRACT The climate, s i t e p r o d u c t i v i t y and environmental c h a r a c t e r i s t i c s of the associations were s t a t i s t i -c a l l y evaluated using c o r r e l a t i o n and regression analyses. The purpose of the study was to assess the degree to which the p r o d u c t i v i t y and the plant community are influenced by i n d i v i d u a l environmen-t a l factors as well as by groups of f a c t o r s . It was found that almost a l l the stands i n v e s t i -gated were severely a f f e c t e d by f i r e and that most stands i n lower a l t i t u d e s have developed following destruction of the previous stands by f i r e s . The 'history of major f i r e s was traced back at least 500 years. The pattern of ecosystem f o r e s t communities has been used as a basis for the separation of b i o l o g i -c a l l y equivalent f o r e s t habitats. Microclimates of seven of the most important as-sociations were studied i n d e t a i l over a period of twelve months. It i s concluded that topography i s the primary f a c t o r i n f l u e n c i n g s o i l and water con-d i t i o n s within a given macroclimatic region. This r e s u l t s i n the development of a c e r t a i n microclimate and an accompanying a s s o c i a t i o n . The greatest differences among the plant communi-t i e s were i n temperature maxima and relative-humidity minima. Temperature means and minima, humidity means and maxima and r a i n f a l l a l l only d i f f e r e d substan-t i a l l y between the two subzones. Forest stand s t a t i s t i c s were compared with conven-t i o n a l stand tables. Site-index curves for Douglas-f i r , western hemlock, red cedar, amabilis f i r and spruce indicate differences between associations, and show t y p i c a l trends which r e f l e c t s i t e q u a l i t y . It was concluded that a set of physiographic c h a r a c t e r i s t i c s i s t y p i c a l f or each a s s o c i a t i o n as well as for each prod u c t i v i t y c l a s s . However, wide standard deviations and large overlaps i n d i c a t e that s i m i l a r physiographic locales may be occupied by d i f f e r e n t associations and by stands of d i f f e r e n t productivity. Topographical features were found to be more c l o s e l y correlated with plant communities than with pr o d u c t i v i t y . Many s i g n i f i c a n t c o r r e l a t i o n s between s i t e index and sixteen environmental factors were found within i n d i v i d u a l associations. General trends i n the s i t e index-environmental factor r e l a t i o n s h i p s were also studied. These investigations have shown that i t i s pos-s i b l e to use many combinations of environmental factors for an estimation of f o r e s t p r o d u c t i v i t y and of plant community. It was found, however, that due to high c o r r e l a t i o n s among environmental f a c t o r s , only two or three c h a r a c t e r i s t i c s need to be used for estimation of either p r o d u c t i v i t y or plant com-munity with an accuracy approaching cases i n which many environmental, factors were considered. Almost a l l of the v a r i a b i l i t y of the plant com-munities studied can be accounted for by differences i n the s o i l and moisture regime. ' Similar c o r r e l a t i o n of s i t e index with s o i l and moisture was found to be s u b s t a n t i a l l y lower. Seepage water and s o i l permea-b i l i t y were found to be the two most important charac t e r i s t i c s of both plant community and s i t e index. i i ABSTRACT A study of p r o d u c t i v i t y and environment of f o r e s t p l a n t communities was c a r r i e d out i n a s e l e c t e d area of the C o a s t a l western hemlock zone. This study i s a p a r t of the composite e c o l o g i c a l p r o j e c t on t h i s zone, which i n c l u d e s i n v e s t i g a t i o n s of s o i l s and v e g e t a t i o n by George Lesko and L a s z l o O r l o c i r e s p e c t i v e l y . In the p r e s e n t i n v e s t i g a t i o n , c l i m a t e , s i t e p r o d u c t i v i t y and environmental c h a r a c t e r i s t i c s of the a s s o c i a -t i o n s were s t a t i s t i c a l l y e v a l u a t e d u s i n g c o r r e l a t i o n and r e g r e s s i o n a n a l y s e s . The purpose of the study was to assess the degree t o which the p r o d u c t i v i t y and the p l a n t community are i n f l u e n c e d by i n d i v i d u a l environmental f a c t o r s as w e l l as by groups of f a c t o r s . I t was found that almost a l l the stands i n v e s t i g a t e d were s e v e r e l y a f f e c t e d by f i r e and t h a t most stands i n lower a l t i t u d e s have developed f o l l o w i n g d e s t r u c t i o n of the p r e v i o u s stands by f i r e s . The h i s t o r y of major f i r e s was t r a c e d back at l e a s t 500 y e a r s . The p a t t e r n of ecosystem f o r e s t communities has been used as a b a s i s f o r the s e p a r a t i o n of b i o l o g i c a l l y e q u i v a l e n t f o r e s t h a b i t a t s . M i c r o c l i m a t e s of seven of the most important a s s o c i a t i o n s were s t u d i e d i n d e t a i l over a p e r i o d of twelve i i i months. I t was' concluded t h a t topography i s the primary f a c t o r i n f l u e n c i n g s o i l and water c o n d i t i o n s w i t h i n a given m a c r o c l i m a t i c r e g i o n . T h i s r e s u l t s i n the development of a c e r t a i n m i c r o c l i m a t e and an accompanying a s s o c i a t i o n . The g r e a t e s t d i f f e r e n c e s among the p l a n t communi-t i e s were i n temperature maxima and r e l a t i v e - h u m i d i t y minima. Temperature means and minima, humidity means and maxima and r a i n f a l l a l l d i f f e r e d s u b s t a n t i a l l y only between the two subzones. F o r e s t stand s t a t i s t i c s were compared w i t h c o n v e n t i o n a l stand t a b l e s . S i t e - i n d e x curves f o r D o u g l a s - f i r , western hemlock, western r e d cedar, a m a b i l i s f i r and S i t k a spruce i n d i c a t e d i f f e r e n c e s between a s s o c i a t i o n s , and show t y p i c a l trends which r e f l e c t s i t e q u a l i t y . I t was concluded t h a t a set of p h y s i o g r a p h i c c h a r a c t e r -i s t i c s i s t y p i c a l f o r each a s s o c i a t i o n as w e l l as f o r each p r o d u c t i v i t y c l a s s . However, wide standard d e v i a t i o n s and l a r g e o v e r l a p s i n d i c a t e t h a t s i m i l a r p h y s i o g r a p h i c l o c a l e s may be occupied by d i f f e r e n t a s s o c i a t i o n s and by stands of d i f f e r e n t p r o d u c t i v i t y . T o p o g r a p h i c a l f e a t u r e s were found to be more c l o s e l y c o r r e l a t e d w i t h p l a n t communi-t i e s than w i t h p r o d u c t i v i t y . Many s i g n i f i c a n t c o r r e l a t i o n s between s i t e index and s i x t e e n environmental f a c t o r s were found w i t h i n i n d i v i d u a l a s s o c i a t i o n s . General trends i n the s i t e index - environmental i v f a c t o r r e l a t i o n s h i p s were a l s o s t u d i e d . The r e s u l t s of the i n v e s t i g a t i o n s have shown t h a t i t i s p o s s i b l e t o use many combinations of environmental f a c t o r s f o r an e s t i m a t i o n of f o r e s t p r o d u c t i v i t y and of p l a n t com-munity. However, i t was found t h a t , due t o h i g h c o r r e l a t i o n s among environmental f a c t o r s , only two or three c h a r a c t e r i s t i c s need be used f o r e s t i m a t i o n of e i t h e r p r o d u c t i v i t y or p l a n t community w i t h an accuracy approaching cases i n which many environmental f a c t o r s were c o n s i d e r e d . Almost a l l of the v a r i a b i l i t y of the p l a n t communities s t u d i e d can be accounted f o r by d i f f e r e n c e s i n the s o i l and moisture regime. S i m i l a r c o r r e l a t i o n of s i t e index w i t h s o i l and moisture was found t o be s u b s t a n t i a l l y lower. Seepage water 'and s o i l p e r m e a b i l i t y were found t o be the two most important c h a r a c t e r i s t i c s of both p l a n t community and s i t e index. V TABLE OF CONTENTS Page INTRODUCTION 1 REGIONAL SETTING AND HISTORY 7 R e l i e f 7 Geology 10 G l a c i a l H i s t o r y 13 Climate i n General 15 F o r e s t S o i l s 19 F o r e s t Composition 26 Recent H i s t o r y 29 METHODS OF FIELD WORK 35 General Data on P l a n t Community and Environment . . . 35 C l i m a t i c Measurements 4l D e s c r i p t i o n of C l i m a t i c S t a t i o n s 45 ANALYSIS OF THE DATA 49 Mathematical Approach 49 The Climate 67 Temperature 67 P r e c i p i t a t i o n 78 R e l a t i v e Humidity 83 S i t e Index on Age 88 Environment . . . . . . . . . . . . 100 P l a n t Communities 148 v i TABLE OP CONTENTS (continued) Page Communities of the D r i e r Subzone 158 G a u l t h e r i a A s s o c i a t i o n 158 Moss A s s o c i a t i o n l6l Polystichum A s s o c i a t i o n 165 Communities of the Wetter Subzone 168 Vaccinium - S a l a l A s s o c i a t i o n 168 Vaccinium - Moss A s s o c i a t i o n 171 Blechnum A s s o c i a t i o n 172 Vaccinium - L y s i c h i t u m A s s o c i a t i o n 175 Ribes - Oplopanax A s s o c i a t i o n 177 M u l t i p l e Regression A n a l y s i s 180 Conclusions 186 Summary 192 BIBLIOGRAPHY 199 APPENDICES 216 v i i LIST OF FIGURES Figure To Follow Page 1. Map of the region studied ' . . 7 2. Vancouver, g e o l o g i c a l map 10 3. Summary of general m e t e o r l o g i c a l data f o r the region 17 4. Years of stand establishment i n d i c a t i n g f i r e h i s t o r y 32 5. Temperature maxima, means and minima i n the s h e l t e r 71 6. Temperature maxima and minima 6 f e e t above the ground and of the ground surface 72 7. Average weekly p r e c i p i t a t i o n i n inches . . . . 78 8. Weekly average cumulative p r e c i p i t a t i o n . . . 78 9. ) Hygrothermograph record f o r s e l e c t e d three 10. j 11. ) weeks 83 12. R e l a t i v e humidity means and minima i n the s h e l t e r 85 13. Average weekly evaporation from atmometers . . 85 14. Cumulative average weekly evaporation from atmometers 85 15. Average s i t e i n d i c e s of a l l commercial t r e e species 91 16. S i t e index curves of D o u g l a s - f i r 92 17. S i t e index curves of western hemlock 92 v i i i LIST OF FIGURES (continued) F i g u r e To Follow Page 18. S i t e index curves of r e d cedar 92 19. S i t e index curves of balsam and S i t k a spruce . 92 20. Comparison of s i t e index curves of immature D o u g l a s - f i r 97 21. D i s t r i b u t i o n of s i t e i n d i c e s by means, standard d e v i a t i o n s and standard e r r o r s . . 98 22. A l t i t u d e and aspect of a l l p l o t s analyzed . . 105 23. A l t i t u d e and aspect of p l o t s i n i n d i v i d u a l communities 106 24. Aspect and a l t i t u d e 107 25. Slope and shape of contours 108, 26. Shape of p r o f i l e and p o s i t i o n on slope . . . . 116 27. Wind exposure and parent m a t e r i a l 120 28. Stoniness and s o i l depth 125 29. Ground water and s o i l moisture 128 30. S o i l p e r m e a b i l i t y and t h i c k n e s s of organic matter 132 31. P o d z o l i s a t i o n and a l t i t u d e 137 32. Changes i n b a s a l area and volume of t r e e s p e c i e s s i n c e the establishment of the stand . . . . 160 33. Change In the number of t r e e s per acre and i n mean diameter 160 34. Regression a n a l y s i s of s i t e index l8l i x LIST OF FIGURES (continued) F i g u r e To Follow Page 35. Regression a n a l y s i s of p l a n t communities . '. . . 182 36. Regression a n a l y s i s of ecosystem p l a n t communities i n d r i e r subzone 183 3-7. Regression a n a l y s i s of ecosystem p l a n t communities i n wetter subzone 184 X LIST OF TABLES Table Page 1. D e s c r i p t i o n of M i c r o c l i m a t i c S t a t i o n s 47 2. S i t e I n d i c e s of I n d i v i d u a l Tree Species . . . . 93 3. C o r r e l a t i o n C o e f f i c i e n t s , S i t e Index on Age . . 97 4. Summary of E x i s t i n g E c o l o g i c a l C l a s s i f i c a t i o n s on the C o a s t a l F o r e s t s of North America . . . 101 5. Means, Standard D e v i a t i o n s , Range and C o r r e l a t i o n 103 6. Comparison of the Nomenclature of the Present Work and C l a s s i f i c a t i o n s of O r l o c i (l96l) and Lesko (1961) 150 7. S o i l P r o p e r t i e s 151 8. S o i l Subgroups - 153 9. Constant Dominant and Character Species . . . . 155 x i ACKNOWLEDGEMENTS The author wishes t o extend h i s g r a t i t u d e to Dr. V. J . K r a j i n a f o r the o r g a n i z a t i o n of t h i s study and f o r h i s guidance, and to the other members of h i s committee: Dr. G. S. A l l e n , Dr. J . S. C l a r k , Dr. P. G. Haddock, Dr. J . W. Ker, Dr. T. M. C. T a y l o r and Dr. D. J . Wort f o r t h e i r h e l p . A s p e c i a l word of a p p r e c i a t i o n i s extended t o Dr. H. Dempster, Dr. T. E. H u l l , Dr. S. W. Nash, Dr. J . G. H. Smith and Mr. R. D o b e l l f o r t h e i r help w i t h s t a t i s t i c a l problems, t o Dr. B. G. G r i f f i t h , Dr. J.D. Chapman and Mr. R. Schmidt f o r h e l p f u l suggestions on c l i m a t o l o g i c a l measurement; to Dr. J . W. Ker and Dr. J . H. G. Smith f o r t h e i r c o o p e r a t i o n i n a n a l y s i s of f o r e s t mensuration data; t o Dr. J . E. Armstrong and Dr. J . S. C l a r k f o r t h e i r comments on geology and s o i l s of the r e g i o n ; t o Dr. P. G. Haddock, Dr. G. E. Rouse and Dr. W. B. S c h o f i e l d f o r t h e i r c r i t i c a l a d vice on the manuscript. The author a l s o wishes t o thank Mr. J . O r l o c i and Mr. G. Lesko f o r t h e i r c o o p e r a t i o n d u r i n g the f i e l d w o r k and Mr. T. V. Berry, Commissioner of the Vancouver Water Board f o r a s s i s t a n c e i n p r o v i d i n g access i n t o the area of the Greater Vancouver Water D i s t r i c t . x i i F i n a n c i a l support f o r the i n v e s t i g a t i o n was given by: N a t i o n a l Research C o u n c i l , MacMillan, B l o e d e l and Powell R i v e r Co., B. C. Sugar R e f i n i n g Co., Greater Vancouver Water D i s t r i c t , Dr. Leon J . Koerner, Mr. W. J . Van Dusen and the F a c u l t y of F o r e s t r y , U.B.C. Th i s support, without which the author could not have completed the study, i s g r a t e f u l l y acknowledged. CHAPTER I INTRODUCTION Since the time when c l a s s i f i c a t i o n of f o r e s t s i t e s became a u s e f u l t o o l i n f o r e s t management, f o r e s t e r s have most f r e q u e n t l y expressed s i t e p r o d u c t i v i t y by the volume or h e i g h t of t r e e s at c e r t a i n ages. With more i n t e n s i v e f o r e s t management, these methods have been r e f i n e d and stand-a r d i z e d and many f o r e s t e r s (e.g." Mayer, 1953) have concluded t h a t height-age curves and " S i t e Index" are the most u s e f u l measures of f o r e s t p r o d u c t i v i t y . However, methods r e l y i n g only on c o n v e n t i o n a l " S i t e Index" curves have s e v e r a l shortcomings: 1. D i f f i c u l t y may be encountered i n c l a s s i f y i n g d e f o r e s t e d areas, and areas which, due t o d i s t u r b -ance or age, do not bear the most p r o d u c t i v e s p e c i e s . A c t u a l and p o t e n t i a l p r o d u c t i v i t y of a s i t e t h e r e f o r e may be d i f f e r e n t . 2. In the c l a s s i f i c a t i o n of s i t e from a e r i a l photo-graphs the method i s not as u s e f u l as are p h y s i o -g r a p h i c f e a t u r e s . 3. Conventional s i t e index curves, which by t h e i r nature can be only averages from a l a r g e area, may not be s u i t a b l e f o r s p e c i f i c l o c a l c o n d i t i o n s . 4. S i t e index curves may be changed by v a r i a t i o n i n the composition of p l a n t cover, e s p e c i a l l y i n i t s t r e e l a y e r . 2 5. Tree h e i g h t i s only a sum of a l l the i n f l u e n c e s under which the t r e e grew. I t does not e x p l a i n the causes of d i f f e r e n c e s i n t r e e growth. As a r e s u l t of these l i m i t a t i o n s , c o n s i d e r a b l e r e s e a r c h has been done on a l t e r n a t e approaches t o the study of s i t e . E c o l o g i s t s o f f e r one method i n the study of s o i l , p h y s i o g r a p h i c and c l i m a t i c f a c t o r s as they a c t upon v e g e t a t i o n , of which t r e e s are considered only a p a r t . Some of these f a c t o r s , humidity, s o i l moisture, r a d i a t i o n , are f a c t o r s t h a t d i r e c t l y i n f l u e n c e the v e g e t a t i o n ; other f a c t o r s , such as a l t i t u d e , degree and d i r e c t i o n of slope, b i o t i c f a c t o r s and competitors, do so i n d i r e c t l y through t h e i r a c t i o n on d i r e c t f a c t o r s . Thus the s i t e q u a l i t y i s the r e s u l t of the i n t e r a c t i o n of many v a r y i n g i n f l u e n c e s . I t d e f i e s an attempt t o p r e s c r i b e p r e c i s e l i m i t s t o i t s component p a r t s . Since s i t e q u a l i t y i s d i r e c t l y r e l a t e d t o s i t e f a c t o r s , d e t e r m i n a t i o n of s i t e q u a l i t y n e c e s s i t a t e s e v a l u a t i o n of these f a c t o r s . Number of methods accomplishing t h i s has been developed and are i n use. One method uses p l a n t communities t o i d e n t i f y the s i t e . I t i s based on the f a c t t h a t s p e c i f i c p l a n t s forming the f o r e s t v e g e t a t i o n occur i n d e f i n i t e e c o l o g i c a l h a b i t a t s , p r o v i d i n g t h a t e q u i -l i b r i u m has been reached. U s i n g p l a n t communities I t i s p o s s i b l e t o develop a c l a s s i f i c a t i o n of f o r e s t h a b i t a t s t h a t are i n d i c a t i v e of s i t e q u a l i t y . 3 The study of the i n f l u e n c e of h a b i t a t f a c t o r s on h a b i t a t c l i m a t e s , s o i l s , v e g e t a t i o n and f o r e s t p r o d u c t i v i t y and t h e i r use i n s i t e c l a s s i f i c a t i o n i s r e l a t i v e l y r e c e n t . E x c e l l e n t reviews of m i c r o c l i m a t i c l i t e r a t u r e are by B l i s s , 1956; Cantlon, 1953; Geiger, 1957; Wolfe, 1949, and of eco-l o g i c a l l i t e r a t u r e by K r a j i n a , i960 (2). In Germany, Kraus (1911) was the f i r s t t o p u b l i s h i n the f i e l d of m i c r o c l i m a t o l o g y i n h i s work "Boden und Klima auf k l e i n s t e m Raum". In the U n i t e d S t a t e s e c o l o g i s t s c o r r e l a t e d p l a n t communities w i t h m e t e o r o l o g i c a l measurements of l o c a l areas as e a r l y as 1899 (Cowles, 1899). Since t h i s time study of m i c r o c l i m a t e , s o i l , and v e g e t a t i o n has developed along two l i n e s . The f i r s t , the economic l i n e , i s r e p r e s e n t e d by i n v e s t i g a t i o n s of the Weather Bureau i n a g r i c u l t u r a l meteorology ( B a t c h e l o r and West, 1915; Cox, 1910, 1922; Smith, 1920) and the study of f o r e s t f i r e weather (Alexander, 1930; Gast and S t i c k e l , 1929, Hawley, 1926; Hayes, 1941; M i t c h e l l , 1929; S t i c k e l , 1931). The second, the e c o l o g i c a l l i n e , i s r e p r e s e n t e d by the r e s e a r c h of b o t a n i s t s emphasizing topography (Aikman, 1941; Burnes, 1953; Cantlon, 1953; Harshburger, 1919; H i l l s , 1952; Morozov, 1926, 1928; P i e r c e , 1934; Pogrebniak, 1929, 1944; Potzger, 1939; Young, 1920), s o i l s Daubenmire, 1936, 1943, 1947, 1952; Graham, 1939; Larsen, 1929; McMinn, 1957), m e t e o r o l o g i c a l f a c t o r s (Burnes, 1953; 4 F u l l e r , 1912; H i l l s , 1952; Huffaker, 1942; Hough, 1945; L i v i n g s t o n , 1938; Thornthwaite, 1940; V a a r t a j a , 1954), and the environmental responses i n p l a n t s and p l a n t communities (Braun-Blanquet, 1928; Cain, 1947; Clements, 1905, 1909; Daubenmire, 1947; Du R i e t z , 1921; Heimburger, 194l; L u d i , 1921; Sisam, 1938; Weaver and Clements, 1929), and ecosystem which encompasses both e c o t o p i c as w e l l as b i o c e n o t i c approaches ( C u r t i s , 1955, 1957; Daubenmire, 1952; Dansereau, 1957; E l l e n b e r g , 1939; Hartmann, 1932, 1933; K r a j i n a , 1933, 1959, I960 (2); Odum, 1953; Oosting, 1956; Sukachev, 1955, 1958 and o t h e r s ) . In North America many s t u d i e s have r e l a t e d the growth of t r e e s t o environmental f a c t o r s . To s o i l s (Carmean, 1955; F o r r i s t a l e t a l , 1953; G e s s e l , 1949; G r i f f i t h , I960; H a n z l i k , 191k; Heimburger, 194l; H i l l , Arnst and Bond, 1948; H i l l s , 1952; Husch and L y f o r d , 1956; Isaac and Hopkins, 1937; Lowry and Youngberg, 1955; Lutz and Chandler, 1955; Peech et a l , 1947; Spurr, 1952; Stout, 1952; Tamm, 1950; T a r r a n t , 1948, 1949, 1950; Warren and Matheson, 1949; Wilde, 1958; W i t t i c h , i960), t o p l a n t communities or p l a n t i n d i c a t o r s (Becking, 1954; Rowe, 1956; Schmidt, 1954; S c o t t , 1957; S o c i e t y of American F o r e s t e r s , 1954; Sisam, 1938; S p i l s b u r y and Smith, 19^7; Tourney, 1947; Westveld, 1954), to c l i m a t e (Carmean, 1955; Grasovsky, 1929; G r i f f i t h , i960; H i l l s , 1952; Isaac, 1946; Jemison, 1934; Kramer and Decker, 1944; Lemmon, 1955; Logan, 1959; Schmidt, 1954, 1955; S c o t t and Duncan, 1959; Spurr, 1955; Trapp, 1938), or topography (Bajzak, i960; Chase, 1959; Choate, 1958; H i l l s , 1952, 1959; J a r v i s , 1958; Losee, 1942; Lutz and Copraso, 1958; Spurr, 1948; S t a r r , 1955; Tarran, 1950; T a r r a n t , 1950; Washington Agr. Exp. S t a t i o n C i r c . No. 2J1 - 1955). The data f o r the present study were c o l l e c t e d i n the environmental complex of c o o l wet c o n i f e r o u s f o r e s t s a long the P a c i f i c coast of B r i t i s h Columbia. The study was designed as a p a r a l l e l work to i n v e s t i g a t i o n s of O r l o c i , who analyzed the p l a n t communities, and Lesko, who analyzed the s o i l s . I t u t i l i z e s p l a n t com-munitie s i n the sense of ecosystem u n i t s of K r a j i n a (1959). The s p e c i f i c o b j e c t i v e s of the present study were: In a s e l e c t e d area 1. To analyze the growth i n heighth, diameter, b a s a l area and volume of t r e e s p e c i e s p r e s e n t i n the more important p l a n t communities. 2. To c o l l e c t and analyze data on p r e c i p i t a t i o n , r e l a t i v e humidity, temperature and i t s s t r a t i f i -c a t i o n , s o i l moisture and temperature v a r i a t i o n d u r i n g a twelve month p e r i o d from nine micro-c l i m a t i c s t a t i o n s , e i g h t l o c a t e d i n s e l e c t e d u n i f o r m p l a n t communities, and one o u t s i d e the f o r e s t . 3. To determine the l o c a l importance and i n f l u e n c e of e l e v a t i o n , slope, aspect, shape of contours, 6 shape of p r o f i l e , p o s i t i o n on slope, wind exposure, parent m a t e r i a l , depth of solum, s t o n i n e s s , mois-tu r e regime, and s o i l forming processes, as measured by t h i c k n e s s of H and Ae h o r i z o n s , on composition of v e g e t a t i o n and f o r e s t p r o d u c t i v i t y as measured by s i t e index. The study i s documented w i t h r e p r e s e n t a t i v e maps, diagrams, c h a r t s , t a b l e s p o r t r a y i n g the area and c o n d i t i o n s being a n a l y z e d . I t u t i l i z e s new as w e l l as c o n v e n t i o n a l kinds of diagrams to show sequences, s i m i l a r i t i e s and d i f f e r e n c e s observed. CHAPTER I I REGIONAL SETTING AND HISTORY R e l i e f The area under study ( F i g u r e 1. Map) i s l o c a t e d on the southern f r i n g e of the c o a s t a l mountain range between A l o u e t t e Lake and Howe Sound i n a l t i t u d e s below 3,000 f e e t . I t i s the southwestern p a r t of the Vancouver F o r e s t d i s t r i c t of the B. C. F o r e s t S e r v i c e . The mountains, r i s i n g t o 5,000 f e e t e l e v a t i o n w i t h i n a few mil e s from the sea, are separated i n t o three mountain b l o c k s by two lo n g U-shaped v a l l e y s ( P i t t R i v e r and Indian Arm) w i t h f l o o r s s e v e r a l hundred f e e t below sea l e v e l . The s t r i k i n g f e a t u r e of these b l o c k s i s the approximately uniform a l t i t u d e of t h e i r peaks and r i d g e s . T h i s f e a t u r e i s pr o b a b l y evidence of a former, u p l i f t e d , w e l l developed e r o s i o n s u r f a c e , out of which the mountains have subsequently been carved. Another th e o r y (Armstrong, 195^0 suggests t h a t l a v a i s s u e d from open f i s s u r e s i n v a s t q u a n t i t i e s , thereby r e t a i n i n g i t s heat and f l u i d i t y , and t h a t i t came to r e s t over a ve r y e x t e n s i v e area w i t h an almost h o r i z o n t a l s u r f a c e . Some of the summits are ve r y sharp, while others are f l a t - t o p p e d . Below them are the even-topped connecting r i d g e s and spurs and long, g e n t l y concave o f t e n t e r r a c e d s l o p e s . S t i l l lower are s t e e p - s i d e d v a l l e y s whose bottoms 7 8 as a r u l e have been eroded by g l a c i e r s d u r i n g the l a s t , the Sumas g l a c i a t i o n . Seymour Ridge, f o r example, which occupies the area between Seymour V a l l e y and Indian Arm, has -at i t s s o u t h e r l y end p l a t e a u - l i k e t e r r a c e s at 3,200, 3,850 and 4,050 f e e t . Small l a k e s occupy the bottoms of c i r q u e s cut i n the t e r r a c e f l o o r s . An i n t e r e s t i n g f e a t u r e of the main v a l l e y s i s the low g r a d i e n t of t h e i r axes. Seymour Creek V a l l e y , f o r example, r i s e s an average of 60 f e e t per mile over a d i s -tance of 21 m i l e s . C h a r a c t e r i s t i c a l l y , the t r i b u t a r i e s of these main s o u t h - f l o w i n g streams are steep and t o r r e n t i a l . Some of them occupy hanging v a l l e y s from which they c a t a r a c t i n t o the main streams through canyons. T h e i r headwaters however, have r e l a t i v e l y g e n t l e s l o p e s . In a d d i t i o n , there i s a younger s e r i e s of streams occupying V-shaped v a l l e y s and descending sl o p e s i n a s u c c e s s i o n of foaming r a p i d s and c a t a r a c t s . The upper reaches of the v a l l e y s u s u a l l y have a number of t e r r a c e - l i k e steps p r o b a b l y due to the c u t t i n g of su c c e s s i v e c i r q u e s by a r e c e d i n g v a l l e y g l a c i e r , or t o the confluence of t r i b u t a r y g l a c i e r s at the p o i n t where the v a l l e y s narrow. The v a l l e y edges i n many cases have been notched by ve r y steep s i d e d canyons; In others the streams cascade over them. At the summit or near i t there i s o f t e n a l e v e l , meadow-like area where a stream has i t s source m a small lake (e.g. Seymour Creek). Others, l i k e Lynn Creek, flow from l a k e s which l i e i n steep s i d e d c i r q u e s , many hundred f e e t below the thin-edged d i v i d e s , which g e n e r a l l y are not much lower than the summits on e i t h e r s i d e . When the g l a c i e r r e t r e a t e d , the main v a l l e y s contained f j o r d s i n which l a k e s formed as u p l i f t p r o g r e s s e d . These l a k e s were l a t e r d r a i n e d by the c u t t i n g of p o s t g l a c i a l canyons through the rock and d r i f t b a r r i e r s . The e x i s t e n c e of these rock b a r r i e r s near the mouth of v a l l e y s seems to be a r e s u l t of t h i n n i n g and b r e a k i n g up of the i c e sheet as i t emerged from the v a l l e y w a l l s , near the margin of the range. G e n e r a l l y the t e r r a i n i s notable f o r extremely rugged cpests, p r e c i p i t o u s slopes and deep v a l l e y s . In p l a c e s the c l i f f s r i s e f o r s e v e r a l hundreds of f e e t and peaks, almost 5,000 f e e t high, are commonly not more than 3 m i l e s from the sea shore. L a n d s l i d e s have been f r e q u e n t . In many p l a c e s t u r b u l e n t water has swept down s u f f i c i e n t m a t e r i a l t o b u i l d up steep a l l u v i a l cones. Deeply grooved, s t r i a t e d and p o l i s h e d s u r f a c e s of r o c k s , c i r q u e s , hanging v a l l e y s , roche moutonne'es and other g l a c i a l topographic f e a t u r e s i n d i c a t e t h a t tne r e g i o n has been l i t t l e a l t e r e d by the a c t i o n of atmospheric agencies s i n c e the r e t r e a t of I c e . The steeper slopes of the mountains are u s u a l l y bare, or covered w i t h stunted t r e e s . With l e s s e n i n g of the 10 d e c l i v i t y , the f o r e s t growth i n c r e a s e s u n t i l the g e n t l e r slopes and v a l l e y s are densely covered by growth. Avalanches have l e f t o c c a s i o n a l great s c a r s on the f o r e s t e d s l o p e s . T e r r a c e s from B u r r a r d I n l e t n o r t h along Capilano, Seymour and Lynn Creek, t o e l e v a t i o n s of almost 1,000 f e e t , r e p r e s e n t r a i s e d marine d e l t a s of former streams. The o v e r a l l topography of t h i s area has been much subdued by exte n s i v e f i l l i n g of the lower v a l l e y s by marine and a l l u v i a l d e p o s i t s . For more d e t a i l e d i n f o r m a t i o n about the p h y s i c a l geography of the r e g i o n , a map i s p r o v i d e d ( F i g u r e l ) . I t a l s o shows I p c a t i o n s of a l l the p l o t s analysed. References: Armstrong, 1954, 1956, 1957; G r i f f i t h , 1959. A e r i a l photographs, g e o g r a p h i c a l and g e o l o g i c a l maps of B r i t i s h Columbia. Geology "The c l a y s and s i l t s of the Vancouver area are composed c h i e f l y of rock f l o u r produced by mechanical a b r a s i o n of g l a c i e r s and l e s s e r extent by chemical decomposition of the ro c k . The sands are mainly quartz, but co n t a i n i n a d d i t i o n many f e l d s p a r s and rock fragments" (Armstrong, 1954). Varved s i l t s and c l a y s are found as g l a c i a l l a k e d e p o s i t s i n l a y e r s from a f r a c t i o n of an i n c h t o s e v e r a l inches t h i c k . Stony s i l t s and c l a y e y s i l t s are, t o a gre a t extent, g l a c i o - m a r i n e d e p o s i t s exposed d u r i n g u p l i f t of the l a n d . Glacio-marine d e p o s i t s are marine d r i f t stones r TERTIARY MIOCENE OR LATER L E G E N D ( A r m s t r o n g 1 9 5 4 , 1 9 5 6 ) U 0 OS z u u Basaltic flows,dykes,and sills, minor tuffs OL IGOCENE OR MIOCENE Kl TSILA NO FORMA TION conglomerate, sandstone, shale E O C E N E BURRARD FORMATION sandstone, shale, conglomerate, minor tuff and basalt V r TR U-5 o l U E 5 £ IASSIC(?)AND/OR LATER G A M B I E R G R O U P Tuff, breccia, agglomerate, andesite, slate, argillite, arkose, quartzite, greywacke, conglomerate, minor dacite, trachyte, and basalt TR IASSIC(?)AND/OR EARLIER B O W E N I S L A N D G R O U P Andesitic and basaltic lavas and pyroclastic rocks, cherty tuff, quartzite, argillite, slate, schists, minor limestone 2 a, 2 b B i -in Bh II. in Hb I M V . M H, - V , M 2A Hornfels, meta-andesite, recrystallized tuff, argillaceous quartzite, horndlende-feldspar gneiss, minor recrystallized lime-stone and cherty lime-silicate rock 2B Banded hornblende-feldspar gneiss, hornblende-btotite-feldspar gneiss, hornblende biotite-quartz schist, diontic gneiss, granitoid gneiss, hybrid diorite and granitic rock PLUTONIC ROCKS ( The sequence of these rocks is not an age sequence) Plutonic rocks in which BIOTITE forms SO to 90 per cent and Hornblende IO to 50 per cent of mafic mineral content, Bh j granite, Bh Q ( granodionte, Bh [jj, quartz diorite Plutonic rocks in which BIOTITE and HORNBLENDE each form about SO per cent of mafic mineral content, BH J J / granodionte, BHQ J , quartz diorite Plutonic rocks in which HORNBLENDE forms SO to 90 per cent and Biotite IO to 50 percent of mafic mineral content, Hbn;, granodionte, HbjR quartz diorite Plutonic rocks in which HORNBLENDE forms 90 per cent or more and Biotite IO per cent or less of mafic mineral content, H j , granite, H]j ( granodionte, H [jj, quartz diorite, H jy, diorite, H y, quartz gabbro and gabbro Heavily drift-covered area To fo l l ow page 10 11 t r a n s p o r t e d by, f l o a t i n g i c e and f i n e m a t e r i a l s c a r r i e d by water. G l a c i a l t i l l denotes unsorted mixtures of sand, s i l t , c l a y and stony m a t e r i a l d e p o s i t e d e i t h e r d i r e c t l y beneath the g l a c i a l i c e as a r e s u l t of mechanical a b r a s i o n , or as l a t e r a l and t e r m i n a l moraines r e s u l t i n g from d e p o s i t i o n of g l a c i e r t r a n s p o r t e d m a t e r i a l . Outwashes are sediments d e p o s i t e d by streams which i s s u e d from g l a c i e r s ; these d e p o s i t s c o n s i s t of interbedded sand and g r a v e l d e p o s i t e d i n d e l t a s , f l o o d p l a i n s and channels (Armstrong, 1954). Sedimentary and v o l c a n i c rocks are i n f r e q u e n t i n the area under study (Armstrong 1954, 1957). See g e o l o g i c a l map F i g u r e 2. P r e g r a n i t i c rocks form outcrops i n Lynn Creek, H o l l y b u r n and Horseshoe Bay. The exposed rocks are g r e a t l y metamorphosed forming on summits of the mountains mainly c h l o r i t e , epidote and a l b i t e and, on lower s l o p e s , l a y e r s of f e l d s p a r - r i c h or h o r n b l e n d e - r i c h m a t e r i a l . The Gambier group, i n a l l except the Mt. Brunswick area, c o n s i s t s c h i e f l y of p y r o c l a s t i c rocks and l a v a s w i t h minor interbedded sedimentary m a t e r i a l . In g e n e r a l these rocks are l i t t l e a l t e r e d but i n p l a c e s they c o n t a i n c h l o r i t e and epidote and i n other p l a c e s some of the v o l c a n i c rocks have been changed to resemble d i o r i t e . At the base of the o v e r - l y i n g Gambler rocks (3 i n F i g u r e 2) i s a b a s a l conglom-erate c o n s i s t i n g of angular to rounded boulders and fragments g e n e r a l l y l e s s than 2 f e e t i n diameter embedded i n a matrix 12 of r o ck d e t r i t u s . Boulders are of o l d e r p l u t o n i c o r i g i n whereas subangular fragments are p a r t l y of v o l c a n i c o r i g i n and p a r t l y of t a l u s from higher e l e v a t i o n s . The matrix c o n s i s t s of small angular and subangular fragments of the u n d e r l y i n g rock, which i s predominantly g r a n i t i c . The con-glomerate grades upward i n t o a normal v o l c a n i c b r e c c i a (Armstrong, 1957). Along B u r r a r d I n l e t , the g e n t l y d i p p i n g B u r r a r d formation r e s t s on the eroded s u r f a c e of p l u t o n i c r o c k s . The beds are of c o n t i n e n t a l o r i g i n . From the p l u t o n i c rocks, which cover most of the map area, hornblende and b i o t i t e are the only important mafic m i n e r a l s , and a l l the rocks f a l l n a t u r a l l y i n t o the f o u r f o l d f a c i e s d i v i s i o n (Bh, BH, HB, and H) o u t l i n e d i n the legend. For example, hornblende g r a n i t e (H^), g r a n o d i o r i t e (H-^), e t c . , are more c l o s e l y a s s o c i a t e d than the d i f f e r e n t v a r i e t i e s of g r a n i t e , such as hornblende g r a n i t e (H^), b i o t i t e - h o r n b l e n d e g r a n i t e (Bh-^), e t c . Normally, the r a t i o of hornblende to b i o t i t e i n the p l u t o n i c rocks i n c r e a s e s near the exposed areas of o l d e r v o l c a n i c and sedimentary s t r a t a , i n d i c a t i n g the profound i n f l u e n c e of these o l d e r formations on the composition of the p l u t o n i c r o c k s . References: Armstrong, 195^, 1956, 1957. 13 G l a c i a l H i s t o r y The area under study was s u b j e c t e d t o f o u r g l a c i a t i o n s . Three were p r o b a b l y major, namely Seymour, Semiamu and Vashon and covered the r e g i o n completely while the f o u r t h , Sumas, pro b a b l y g l a c i a t e d v a l l e y s o nly. The Seymour and Vashon g l a c i a t i o n s reached i c e sheet p r o p o r t i o n s d u r i n g t h e i r maxima, at which time they were p r o b a b l y 7,500 f e e t or more t h i c k over the v a l l e y . The i c e moved g e n e r a l l y i n a s o u t h e r l y d i r e c t i o n . "Present l a n d f e a t u r e s have r e s u l t e d predominantly from the l a s t or Sumas g l a c i a t i o n which b u r i e d evidence of the e a r l i e r g l a c i a l a c t i v i t y . Radio-carbon-age determinations from wood from the base of C a p i l a n o Sumas t i l l p l a c e s t h i s l a s t g l a c i a t i o n about 11,250 + 1000 years o l d . S i m i l a r l y , wood from g l a c i o - m a r i n e d e p o s i t s from Whatcom d e p o s i t s date i t as 11,350 +200 years o l d " (Armstrong, 1954). During each g l a c i a t i o n the l a n d was depressed i n r e l a t i o n t o the sea, and i n the case of the Vashon g l a c i a t i o n t h i s amounted to at l e a s t 1,000 f e e t . During the r e t r e a t of the Vashon i c e , l a r g e l y by wasting, the i c e masses p r e v i o u s l y r e s t i n g on the sea f l o o r t h i n n e d and f l o a t e d f r e e , l e a v i n g glacio-marine stony c l a y d e p o s i t s c o n t a i n i n g marine s h e l l s and numerous stones i n the s a l t water,. L a t e r , these were e l e v a t e d above sea l e v e l . For example, above the present a l t i t u d e of 500 f e e t i n the most e a s t e r n p a r t of the area, Haney outwash 14 was de p o s i t e d d u r i n g a r e c e s s i o n a l stage. D u r i n g post-Vashon time Sumas i c e advanced westward i n t o the E r a s e r Lowland towards the sea and de p o s i t e d Whatcom gl a c i o - m a r i n e d e p o s i t s i n f r o n t of and beneath the i c e . Among the most obvious marks of g l a c i a l a c t i v i t y are the " e r r a t i c s " , boulders t r a n s p o r t e d by i c e to t h e i r p r e s e n t l o c a t i o n s . In the area s t u d i e d , g l a c i a l t i l l under-l i e s most of the t e r r a i n . T h i s t i l l o f t e n d i s p l a y s a p a t t e r n of l o n g s t r e a m l i n e r i d g e s o r • " d r u m l i n o i d s " , which, w i t h i n t e r v e n i n g "grooves" r e c o r d the d i r e c t i o n of movement of the l a s t r a p i d l y moving i c e sheet. Meltwater d r a i n i n g from the i c e u s u a l l y f o l l o w e d the edge of the i c e tongues along the v a l l e y w a l l s , r a t h e r than i n the centre of the v a l l e y f l o o r s which, at the time, were plugged by i c e . In v a l l e y s d r a i n i n g towards the Ice sheet the water became ponded t o form i c e dammed l a k e s . Many of the channels cut by escaping meltwater were emptied a f t e r the m e l t i n g of the i c e sheet and are now e i t h e r dry or occu-p i e d by smal l streams. Others unable t o remove the d e b r i s f a l l i n g i n t o them from t h e i r w a l l s or washed m by t r i b u t a r y brooks have been p a r t l y plugged t o form chains of l a k e s , such as some of the lak e s at U. B. C. F o r e s t . Coarse sediment c a r r i e d by meltwater i n the form of sand and g r a v e l c r e a t e d outwash p l a i n s or t e r r a c e s , producing r a t h e r w e l l d r a i n e d s o i l s . 15 Within the ice-dammed lakes, s i l t and clay from the g l a c i a l waters were deposited l o c a l l y in great volumes, to form lacustrine deposits. Along the lake margins, terraces of sand and gravel were l a i d down, mainly near the mouth of the drain channels. Most of the area south of the Coastal Mountains i s covered with a mantle of surface deposits as much as 500 feet or more thick. These consist l a r g e l y of r i v e r deposits, g l a c i a l d r i f t , i n t e r g l a c i a l sediments and some small areas of peat. References: Armstrong, 1954, 1956, 1957. Climate i n General The area under study as a climatic region corresp'onds with Koeppen's Cfb and mild Dfb and Trevartha's Cbf and mild Dbf. As a bioclim a t i c region i t l i e s within a l t i t u d i n a l range of Coastal Western Hemlock Zone (Krajina, 1959) which i s a subdivision of Coast Forest (B. C. Atlas of Resources, 1956; Halliday, 1937; Rowe, 1959; Weaver and Clements, 1938) or Coastal Belt (Whitford and Craig, 1918). The location of the area i s such that the character-i s t i c s of the climatic elements combine to produce a pre-dominantly marine-type climate with cool summers and mild winters. The climate generally can be classed as mild, e s p e c i a l l y when one considers the northerly la t i t u d e in which 16 the area i s l o c a t e d . D e v a s t a t i n g storms such as b l i z z a r d s , c l o u d b u r s t s and f l o o d s occur i n f r e q u e n t l y and g e n e r a l l y do not cause widespread damage. There are three main c l i m a t i c c o n t r o l s which have a d e f i n i t e i n f l u e n c e on the c l i m a t e of southern B r i t i s h Columbia: (a) the t e r r a i n , (b) the P a c i f i c Ocean and (c) the semipermanent h i g h and low p r e s s u r e r e g i o n s l o c a t e d over the North P a c i f i c Ocean. These c l i m a t i c i n f l u e n c e s combine to produce e n t i r e l y d i f f e r e n t c o n d i t i o n s w i t h i n s h o r t d i s t a n c e s . The P a c i f i c Ocean forms the western boundaries of B r i t i s h Columbia, but the r e g i o n s t u d i e d i s separated from I t by Vancouver I s l a n d and the c o a s t a l trough. The seasonal change i n the s u r f a c e temperature of the ocean i s f a r l e s s than the seasonal change i n the temperature of the l a n d ; thus the ocean i s warmer i n the w i n t e r and c o o l e r i n the summer than the a d j o i n i n g land s u r f a c e s . The average temperature of the water'along the coast and i n the S t r a i t of Juan de Fuca ranges from 45° F. i n January t o 53° P. i n J u l y . However, some of the shallow bays and p r o t e c t e d coves are 5 to 10° F. warmer d u r i n g the summer ( C l i m a t o l o g i c a l data, Washington, 1959). The semipermanent h i g h and low p r e s s u r e areas over the North P a c i f i c Ocean s t r o n g l y i n f l u e n c e the c l i m a t e of the Vancouver a r e a . These two pressure systems b r i n g a flow of 17 a i r from over the ocean to t h i s r e g i o n . The a i r c i r c u l a t e s i n a clockwise d i r e c t i o n around the semipermanent h i g h pressure c e l l and i n a counterclockwise d i r e c t i o n around the semi-permanent low p r e s s u r e c e l l . The semipermanent low p r e s s u r e becomes v e r y weak and moves n o r t h of the A l e u t i a n I s l a n d s d u r i n g the summer. At the same time the semipermanent h i g h p r e s s u r e i n t e n s i f i e s and spreads over most of the North P a c i f i c Ocean. A clockwise c i r c u l a t i o n of a i r around t h i s h i g h p r e s s u r e r e g i o n b r i n g s a n o r t h w e s t e r l y flow of a i r from over the North P a c i f i c and Gulf of A l a s k a on shore. T h i s a i r i s c o o l and r e l a t i v e l y dry, and as a consequence, summer i s the season of l i g h t e s t p r e c i p i t a t i o n . The A l e u t i a n low p r e s s u r e area i n t e n s i f i e s and moves southward i n the f a l l , r e a c h i n g i t s maximum i n t e n s i t y i n mid-winter, while the P a c i f i c h i g h p r e s s u r e area moves southward and becomes r a t h e r weak at t h i s season of the y e a r . A c i r c u l a t i o n of a i r around these two p r e s s u r e systems b r i n g s a southwesterly flow of warm and moist a i r on shore. T h i s a i r i s warmer than the l a n d s u r f a c e , thus c o o l i n g and condensation take p l a c e w i t h the onshore movement r e s u l t i n g i n a r a i n y season d u r i n g the l a t e f a l l and w i n t e r months. The average monthly hours of b r i g h t sunshine r e c o r d e d at Vancouver C i t y o bservatory range from 36 i n December t o 282 i n J u l y ( F i g u r e 3). The number of days i n which measurable p r e c i p i t a t i o n f a l l s i s approximately 155 S u m m a r y o f G e n e r a M e t e o r o l o g i c a l To follow page 17 F i g 3 D a t a f o r t h e R e g i o n C o q u i t l a m Lake U B C F o r e s t Mosqu i t o C r e e k D J D J D F r e q u e n c y of Wrnds V a n c o u v e r A i r p o r t H o u r s of B r i g h t Sunsh ine V a n c o u v e r C i t y 18 (Vancouver C i t y ) . Damaging h a i l s t o r m s occur r a r e l y i n t h i s a r e a. November, December, and January are the w e t t e s t months, and June, J u l y and August-are the d r i e s t ( F i g u r e 3). Cloudy mornings w i t h no r a i n and sunny afternoons are charac-t e r i s t i c of the weather d u r i n g the l a t t e r h a l f of the summer. The r e l a t i v e humidity ranges from an average of 85$ at 4 p.m. i n January t o an average of 50-55$ at 4 p.m. i n J u l y . The r e l a t i v e humidity o c c a s i o n a l l y drops to 25$ d u r i n g p e r i o d s of s t r o n g e a s t e r l y winds. The h i g h e s t temperature i n summer and lowest i n w i n t e r u s u a l l y occur w i t h e a s t e r l y winds. The average mean temperature ranges from 50° F. (Vancouver C i t y ) t o about 43° F. at Seymour Mountain Ranger S t a t i o n ( s t a t i o n at subalpine b o r d e r ) . The y e a r l y extreme maxima range from 80° F. to 85° F. and extreme minima from 15° F. to 10° F. r e s p e c t i v e l y . (The minimum temperatures from -2° F. to 5° F. have been recorded.) The average J u l y maximum temperature ranges from 75° P. i n the lower e l e v a t i o n s t o 650 F. i n the higher e l e v a t i o n s . The J u l y minimum temperature i s u s u a l l y i n the mid-40 !s. Temperature and p r e c i p i t a t i o n measurements have been l i m i t e d t o e l e v a t i o n s below 1,500 f e e t other than f o r a few snow course measurements. The average annual p r e c i p i -t a t i o n ranges from p r o b a b l y 65 or 70 inches to w e l l over 150 inches at the upper a l t i t u d i n a l l i m i t s of the area 19 studied (3,000 f e e t ) . The average annual s n o w f a l l ranges from 10 inches i n the lower e l e v a t i o n s to more than 300 inches. Snow depth i n higher e l e v a t i o n s may exceed 5 f e e t . Snow at higher e l e v a t i o n s begins i n December and continues u n t i l l a t e s p r i n g w i t h snow depths i n c r e a s i n g u n t i l the middle of March. At higher e l e v a t i o n s the snow remains on the ground u n t i l A p r i l . M e l t i n g snow f u r n i s h e s a continuous supply of water almost throughout the summer. P r a c t i c a l l y a l l of the area under study i s covered w i t h timber. Timber production, water-shed p r o t e c t i o n and r e c r e a t i o n comprise the major land uses. Most of the higher area i s i n a c c e s s i b l e from the time snow begins t o accumulate u n t i l s p r i n g . References: B.C. A t l a s of Resources, 1956; Canada, Dept. of Transport, C l i m a t i c Summaries and Reports; Chapman, 1952; G r i f f i t h , I960; K r a j i n a , 1959. Forest S o i l s Under a given set of c l i m a t i c and b i o l o g i c condi-t i o n s , v a r i a t i o n of the s o i l i s c o n t r o l l e d by the i n t e r a c t i o n of the t e x t u r e and stoniness of the parent m a t e r i a l , the slope of the ground surface and the moisture regime i n the ground. Parent m a t e r i a l s of any g e o l o g i c a l o r i g i n normally vary from place to place and w i l l thus give r i s e t o se v e r a l d i f f e r e n t kinds of s o i l . 20 G l a c i a l t i l l i s the most widespread earth m a t e r i a l i n the area s t u d i e d . U s u a l l y i t Is of stony, sandy loam texture hut commonly a l s o stony loam and stony c l a y loam t i l l s are found, often interbedded w i t h compact and c o n c r e t e - l i k e l a y e r s of t i l l r e f e r r e d to as "hardpan". Most s o i l s on t i l l s are stony or g r a v e l l y and of sandy loam to loam t e x t u r e . The compact t i l l forming the substratum of such s o i l s e f f e c t i v e l y prevents water from moving downward so that s o i l s i n low places are subject to f l o o d i n g during the winter and those on higher ground are not as dry i n summer as could be expected from t h e i r t e x t u r e . These unmodified t i l l s o i l s are found on only outside the areas of marine submergence. In the areas that had been sub-merged the t i l l often forms the substratum of the s o i l but the solum i t s e l f i s developed from marine sediments derived from the t i l l . Gravels and sands deposited by g l a c i a l streams form f l a t t e r r a c e s of u s u a l l y dry s o i l s . The most extensive g l a c l o -f l u v i a l deposits occur j u s t above the marine deposits where major v a l l e y s lead from the mountains on to the lowland. The r i v e r t e r r a c e s are found along the v a l l e y sides but u s u a l l y they are not extensive. The d e l t a t e r r a c e s are outside the r i v e r v a l l e y s but adjacent to them. Most of the d e l t a and r i v e r t e r r a c e deposits are e x c e s s i v e l y drained loamy sands and g r a v e l l y loamy sands and u n d e r l a i n by sands and g r a v e l s (Figures 1 and 2 ) . 21 Bottomlands b o r d e r i n g the r i v e r s and d e l t a s at the r i v e r mouths are b u i l t of g r a v e l and sand, but many of them bear a s u r f a c e l a y e r of loamy, s i l t y or c l a y e y a l l u v i u m or swampy org a n i c m a t e r i a l . A l l u v i a l s o i l s a s s o c i a t e d w i t h s m a l l e r streams are p r i n c i p a l l y g r a v e l l y . L a r g e r areas covered by f i n e r m a t e r i a l are found on the f l o o d p l a i n s and d e l t a s of b i g g e r streams. (e.g. Seymour R i v e r ) . In s p r i n g many of the bottom lands are s u b j e c t to f l o o d i n g , but i n summer the coarse t e x t u r e d a l l u v i a l s o i l s are e x c e e d i n g l y dry and the f i n e r t e x t u r e d s o i l s which r e s t upon the coarse substratum are d r i e r than would be expected from t h e i r t e x t u r e (Armstrong, 1957). A l l u v i a l fans b u i l t by streams f l o w i n g from steep mountainside g u l l i e s are formed by e x c e e d i n g l y stony or grave sandy loams or c o n s i s t almost e n t i r e l y of stones. In some p l a c e s they are dry but elsewhere water flows on the ground s u r f a c e . O c c a s i o n a l l y along the base of the slopes or on the lower marginal p a r t s of some fans and i n de p r e s s i o n s , sands and loams are found washed out from c o a r s e r s o i l s on the s l o p e s . These f i n e t e x t u r e d d e p o s i t s commonly c o n s i s t of a l t e r n a t i n g l a y e r s of loamy or c l a y e y m a t e r i a l and sand and do not c o n t a i n l a r g e r stones (Armstrong, 1956). S o i l s are the r e s u l t of the combination of c l i m a t e , l i v i n g organisms and s o i l moisture o p e r a t i n g on the parent 22 m a t e r i a l over a p e r i o d of time. Since these f a c t o r s d i f f e r from place to place so do the s o i l forming processes and the s o i l s developed. At higher e l e v a t i o n s under the i n f l u e n c e of cool c l i m a t e , greater p r e c i p i t a t i o n and raw humus, podzols develop w i t h Brown-Podzolic and peat as a s s o c i a t e d s o i l s of l o c a l Importance. In mid a l t i t u d e s the p r i n c i p a l s o i l groups are Reddish-Brown, Brown-Podzolic and Podzols and a s s o c i a t e d w i t h these i n l e s s w e l l drained p o s i t i o n s are muck, peat and g l e i z o l i c s o i l s . At lower e l e v a t i o n s the most important s o i l group i s the Concretionary Reddish-Brown. A l l u v i a l s o i l s occur on the d e l t a s and f l o o d p l a i n s of most of the r i v e r s . Recently a survey was completed (Holland et a l , 1959) of P i t t Meadows M u n i c i p a l i t y i n the v i c i n i t y of the U. B. C. Fo r e s t . I t appears that the Alderwood Sandy Loam i s c l o s e l y r e l a t e d t o the m i d - a l t i t u d e s o i l s and i s c l a s s i f i e d as "belong-in g to the Brown-Podzolic group. I t has a compact and hard parent m a t e r i a l composed of g l a c i a l t i l l which i s impervious to water. In the area where the t i l l i s close to the surface the r o o t i n g zone i s r e s t r i c t e d and summer droughts are frequent. In the area under study mainly the a g r i c u l t u r a l s o i l s were i n v e s t i g a t e d and the general region was described as Concretionary-Brown. These s o i l s have a r e l a t i v e l y t h i n organic l a y e r on the surface (Ao) derived mainly from coniferous vegetation and mosses. A^ horizon i s formed by a t h i n l a y e r of mull (0.5 to 2 Inches t h i c k ) . A c c i s a 23 concretionary horizon w i t h a r e l a t i v e l y high content of organic matter. B i s dark r e d d i s h brown to y e l l o w i s h brown or strong brown. I t i s h i g h l y concretionary and of high p o r o s i t y and p e r m e a b i l i t y . Free oxides of Fe are u s u a l l y concentrated In t h i s region and the base exchange c a p a c i t y i s g e n e r a l l y low i n r e l a t i o n to c l a y content. B-C i s the lower t r a n s i t i o n a l p a r t of the p r o f i l e . C horizon -parent m a t e r i a l i s often dense and of low p o r o s i t y and per-m e a b i l i t y . As a consequence i n t e r n a l s o i l drainage i s f r e q u e n t l y r e s t r i c t e d and l a r g e volumes of water move l a t e r -a l l y over these impervious horizons. Lesko (1961) described s i x s o i l subgroups and d i v i d e d each i n t o s e v e r a l s o i l types. 1. Subaqueous S o i l s - s o i l s covered permanently by water, having only A and C h o r i z o n . 2. Organic s o i l s . a. Sphagnum peat, water saturated undecomposed Sphagna. b. P i t c h Peat Anmoor, peat decomposed on the surface and converted Into black muck. c. Spring Line P i t c h y Anmoor, black muck under-l a i n by permanently waterlogged g l e y h o r i z o n . 3. G l e y o s o l i c S o i l s . a. O r t h i c Dark Grey G l e y s o l , t h i n 0 horizon u n d e r l a i n by dark A^ horizon over gleyed l a y e r . 2 4 b. Orth i c G l e y s o l , t h i c k ( l - 6 inches) 0 horizon over t h i n Ah horizon u n d e r l a i n by s t r o n g l y gleyed l a y e r . 4 . Regosolic s o i l s . a. A l l u v i a l Regosal, new a l l u v i a l d e p o s i t s . b. A c i d L i t h o s o l , embrionic s o i l s of a c i d rock outcrop. c. E l u v i a t e d A c i d L i t h o s o l s , s o i l s w i t h C and A e horizons developed on a c i d parent rock. 5. B r u n i s o l i c S o i l s . a. Degraded Concretionary Brown. S o i l s w i t h 0 horizon and t h i n but continuous A e horizons w i t h grey c o n c r e t i o n s . B concretionary, r e d d i s h brown to pale brown. M o t t l i n g absent. b. Orth i c Brown P o d z o l i c , medium to strong a c i d t h i c k 0 h o r i z o n . A^ t h i n or l a c k i n g . A e horizon g e n e r a l l y absent or t h i n . B horizon i s brown t o y e l l o w i s h brown, medium to s t r o n g l y a c i d , w i t h low base s a t u r a t i o n w i t h no n o t i c e a b l e accumulation of c l a y or *ses-q u i o x i d e s . S l i g h t m o t t l i n g u s u a l l y present. c. Modal A c i d Dark Brown. S o i l s w i t h g r e y i s h brown to black A^ ho r i z o n , low i n base satur-a t i o n . Brownish B horizon i s low i n base s a t u r a t i o n and f r e e of m o t t l i n g . 25 6. P o d z o l i c S o i l s . a. Gleyed Podzol has organic 0 horizon over e l u v i a l A e horizon on i l l u v i a l B hor i z o n , which con-t a i n s organic matter and sesquioxides. M o t t l i n g i n a l l mineral h o r i z o n s . b. Orterde Podzol. S i m i l a r t o Gleyed Podzol but without m o t t l i n g . Accumulation of organic matter i n B horizon does not reach 10 per cent. c. Minimal Podzol. Organic surface horizon (o) , t h i n l i g h t colored Ae ho r i z o n , and an i l l u v i a l B ho r i z o n , which contains accumula-t i o n of organic matter and sesquioxides. D i s t i n c t Bh horizon i s absent. d. Orterde Humic Podzol contains moderately t h i c k 0 h o r i z o n , a d i s t i n c t a c i d A e horizon and a f r i a b l e u s u a l l y t h i c k Bh hor i z o n , c o n t a i n i n g over 10 per cent of organic matter and i r o n . This i s u n d e r l a i n by a f r i a b l e Bhf h o r i z o n . e. Humic Podzol. S i m i l a r to Orterde Humic Podzol but B^ horizon i s t h i n n e r than 3 inches. References: Armstrong, 1954, 1956, 1957. B. C. A t l a s of Resources (1956); F o r r i s t a l et a l (1953 - Washington); G r i f f i t h (19.60 - U. B. C. Research F o r e s t ) ; H i l l et a l (1948 -Washington); K e l l y and S p i l l s b u r y (1939)* Rowles, Farstad and L a i r d (1956 - Lower Fraser R i v e r V a l l e y ; Lesko (1961). 26 Forest Composition In the "Forests of B r i t i s h Columbia" Whitford and Cra i g (1918) c l a s s i f y the area under study as belonging to the "Coastal B e l t " . Under that term they mean a broader and c l i m a t i c a l l y l e s s uniform region than the Coastal Western Hemlock Zone ( K r a j i n a , 1959). The l a t t e r i n c l u d e s only the wetter p a r t of the Coastal B e l t , but without the subalpine f o r e s t . W i t h i n the Coastal B e l t , Whitford and C r a i g recog-nize f i v e f o r e s t types. Because of the broader meaning of the term, only four are important i n the area under study. The D o u g l a s - f i r - Red cedar type, the Red cedar - Western Hemlock type, the Western hemlock - Balsam type and the Hemlock - S i t k a spruce type. Their d e s c r i p t i o n , though o l d , deserves to be repeated. They describe the f o r e s t s as they e x i s t e d before the large scale logging and i t can be assumed that that was the f o r e s t as i t e x i s t e d here over hundreds of years, d i s t u r b e d only by n a t u r a l causes. They wrote: 'Local s o i l and topographic c o n d i t i o n s , which vary so g r e a t l y i n a mountainous region such as t h i s cause so many m o d i f i c a t i o n s i n the f o r e s t growth that i t i s impossible, except i n a general way to i n d i c a t e the d i s t r i b u t i o n of each type. D o u g l a s - f i r - Red cedar type they described: In general i t may be s a i d that t h i s type occurs i n regions where the annual p r e c i p i t a t i o n i s l e s s than 75 inches not more than 5 percent of which i s m the form of snow. D o u g l a s - f i r t h r i v e s best on deep, r i c h , w e l l drained s o i l s , but i t w i l l grow on steep rocky 27 s i t e s where the supply of s o i l moisture i s not s u f f i c i e n t f o r cedar or hemlock. Red cedar t h r i v e s best i n the more moist s i t u a t i o n s , but u s u a l l y grows wherever D o u g l a s - f i r does and maintains i t s v i g o r on higher and l e s s p r o p i t i o u s s i t e s . Western hemlock occurs almost everywhere i n c r e a s -i n g i n prominence at the higher e l e v a t i o n s or on l e s s favourable s i t e s . I t i s u s u a l l y of b e t t e r q u a l i t y on higher s i t u a t i o n s , being on the lowlands, more subject to defects though of l a r g e r s i z e . The two species of balsam are as a r u l e confined to v i r g i n stands, to e i t h e r the damper or the higher s i t e s ; the lowland f i r to the former and the a m a b i l i s f i r to the l a t t e r . S i t k a spruce occurs In t h i s type only on the well-watered lands along the v a l l e y bottoms or close to the shore and i s seldom found at more than 1000 f e e t above sea l e v e l . Western white pine i s a t y p i c a l species of t h i s type, but seldom forms over 5 percent of the stand. I t occupies rocky k n o l l s or edges of openings i n the f o r e s t . Cottonwood occurs i n the same s i t e s as S i t k a spruce and i s t y p i c a l l y a pioneer species on a l l u v i a l s o i l s , g r a d u a l l y being replaced by c o n i f e r s . . . . G enerally speaking the n a t u r a l reproduction of the f i r and cedar i s being accomplished s a t i s f a c t o r i l y except where f i r e s occur repeatedly. In order to secure reproduction of these species a f t e r l o g g i n g , s l a s h burning has been found necessary, to remove not only the r e s u l t i n g d e b r i s but the hemlock and balsam reproduction, which owing to the shade-enduring c h a r a c t e r i s t i c s of these species u s u a l l y becomes e s t a b l i s h e d under the mature stands. Red cedar - Western hemlock type they c h a r a c t e r i z e as f o l l o w s : As D o u g l a s - f i r disappears from the stands i n the north or at higher a l t i t u d e s , Red cedar becomes a pre-dominant species w i t h Western hemlock as second i n importance. In the southern p o r t i o n of c o a s t a l b e l t t h i s zone Is u s u a l l y at an a l t i t u d e of from 1500 f e e t t o 3000 f e e t above the sea. The c l i m a t i c c o n d i t i o n s of t h i s type are more severe than those of the Douglas f i r - Red cedar type. Though the temperature i s only s l i g h t l y lower, the p r e c i p i t a t i o n i s heavier ranging from 90 Inches t o over 120 inches and averaging about 106 inches per annum. The percentage of snow a l s o i s much higher. Red cedar i s the most important species w i t h Western hemlock i n the second and Balsam i n the t h i r d p l a c e . S i t k a spruce forms only a minute p o r t i o n of any stand. Yellow cypress 28 a t t a i n s i t s best i n d i v i d u a l development i n t h i s type, but as a r u l e i t i s c o n f i n e d t o l e s s a c c e s s i b l e upper l i m i t s of t h i s t y pe. Western hemlock - Balsam type occupies a c l i m a t i c zone somewhat l e s s f a v o u r a b l e than t h a t of Red cedar -Western hemlock type. I t occurs e i t h e r i n h i g h e r a l t i -tudes or on more exposed or wetter s i t e s . Though not always p r e s e n t i n southern p o r t i o n of the p r o v i n c e , i t i s found there i n some l o c a l i t i e s above the Cedar - Hemlock type at e l e v a t i o n s 1500 f e e t t o 3500 f e e t extending i n some cases as h i g h as 4000 f e e t depending on the topo-graphy. ... Where t h i s type occurs the t o t a l p r e c i p i t a t i o n and the percentage of s n o w f a l l are g e n e r a l l y h i g h e r than i n the p r e v i o u s l y d i s c u s s e d types or e l s e the temperature i s lower.... Western hemlock and Balsam are predominating s p e c i e s . The composition of the stand i s approximately as f o l l o w s : Hemlock 50$, Balsam 30$, Red cedar 15$, Yellow cedar 5$. . . . L i t t l e damage has been done by f i r e and the f o r e s t s are s t i l l a w a i t i n g development. Western hemlock - S i t k a spruce type: T h i s type i s t y p i c a l l y a lowland type, seldom o c c u r r i n g i n a l t i t u d e s of more than 1000 f e e t above sea l e v e l , u s u a l l y below 500 f e e t . T h i s type i s found m the damper s i t u a t i o n a long the v a l l e y bottoms i n both Douglas f i r - Red cedar type and f u r t h e r n o r t h i n Red cedar -Western hemlock type, t h e r e f o r e w i t h i n t h i s range the r e l a t i v e p r e c i p i t a t i o n a l s o v a r i e s w i d e l y . In t h i s type the western hemlock Is the most frequent but the S i t k a spruce most v a l u a b l e s p e c i e s . A s s o c i a t e d w i t h these are Red cedar, A m a b i l i s f i r and Cottonwood. The f o u r f o r e s t types d e s c r i b e d are e x c e l l e n t d e s c r i p t i o n s of the mature f o r e s t s of the p a s t . The Douglas-f i r - Red cedar type, though i t a l s o i n c l u d e s the f o r e s t s of the e a s t e r n p a r t of Vancouver I s l a n d ( C o a s t a l D o u g l a s - f i r Zone - K r a j i n a , 1959) d e s c r i b e s the composition of the stands i n t h i s area e x c l u d i n g t h e i r f i n a l stage which, due to frequent f i r e s , d i d not develop. Red cedar - Western hemlock f o r e s t type d e s c r i b e s the f i n a l stage i n d r i e r as w e l l as wetter subzone up to the a l t i t u d e of almost 3000 f e e t . 29 Western hemlock - Balsam type i n the area under study i s of l i m i t e d occurrence, being more frequent i n hig h e r a l t i t u d e s . Hemlock - S i t k a spruce type p i c t u r e s the f o r e s t s on the a l l u v i a l f l o o d p l a i n s . D e s c r i p t i o n s of the f o r e s t s and the given a l t i -t u d i n a l ranges agree w i t h r e s u l t s of the p r e s e n t study per-f e c t l y ; the range of p r e c i p i t a t i o n d i s a g r e e s w i t h the prese n t study as w e l l as w i t h the d e s c r i p t i o n given by W h i t f o r d and C r a i g . Therefore one must assume t h a t e i t h e r t h e i r a l t i t u d -i n a l range and d e s c r i p t i o n s of f o r e s t stands or t h e i r p r e c i p i t a t i o n data are wrong. W h i t f o r d and C r a i g had the g r e a t e s t o p p o r t u n i t y to study the f o r e s t s as they saw them. They c o u l d measure or estimate the a l t i t u d e . But before the p u b l i c a t i o n of t h e i r book i n 1918 only three m e t e o r o l o g i -c a l s t a t i o n s — V i c t o r i a ( e s t a b l i s h e d 1887, a l t i t u d e 228 f e e t ) , Vancouver (1911, a l t i t u d e 45 f e e t ) , and Nanaimo (1914, a l t i t u d e 125 f e e t ) — e x i s t e d on the coast of B r i t i s h Columbia. Recent H i s t o r y I t i s g e n e r a l l y agreed t h a t g e o g r a p h i c a l l y , c l i m a t e i s the most e f f e c t i v e f a c t o r d etermining the c h a r a c t e r of f o r e s t s . A p a r t i c u l a r c l i m a t i c f a c t o r may determine the com-p o s i t i o n of a f o r e s t i n a d i r e c t way produ c i n g c o n d i t i o n s which a f f e c t the p h y s i o l o g y of a s p e c i e s or i t may accomplish a s i m i l a r e f f e c t by i n d i r e c t means. "In t h i s r e g i o n the most e f f e c t i v e d i r e c t c l i m a t i c c o n t r o l i s the temperature and 30 l e n g t h of growing season as i t decreases w i t h i n c r e a s e of a l t i t u d e and e l i m i n a t e s lowland s p e c i e s i n a constant a l t i -t u d i n a l o r d e r . . . . P r e c i p i t a t i o n although i t a f f e c t s the v i g o r of f o r e s t t r e e s p e c i e s a great d e a l , does not seem t o have an important d i r e c t e f f e c t on t h e i r l o c a l d i s t r i b u t i o n mainly because t h i s r e g i o n has a comparatively h i g h p r e c i p i t a t i o n (Schmidt, 195t7). K r a j i n a (unpublished) d i s a g r e e s s t a t i n g : "The d i s t r i b u t i o n of some t r e e s (Abies g r a n d i s , Abies a m a b i l i s , Arbutus m e n z i e s i i , Chamaecyparis n o o t k a t e n s i s , Tsuga mertensiana and many others as Acer macrophyllum, Prunus emarginata e t c . ) i s g r e a t l y i n f l u e n c e d by the p r e c i p i t a t i o n d i s t r i b u t i o n . " The d i f f e r e n c e s i n o p i n i o n are ve r y s i g n i f i c a n t . V i g o r of each s p e c i e s as w e l l as r e p r o d u c t i o n or e l i m i n a t i o n from the h a b i t a t i s the r e s u l t of a l l normal and abnormal c o n d i t i o n s e x i s t i n g i n the h a b i t a t . Temperature, l e n g t h of growing season, snow depth, p r e c i p i t a t i o n , i n s o l a t i o n and other environmental c o n d i t i o n s are dependent on macroclimate and topography. They a l l are h i g h l y i n t e r c o r r e l a t e d . I t i s q u i t e p o s s i b l e t h a t the e f f e c t t h a t we r e l a t e t o any of these f a c t o r s i s i n r e a l i t y the e f f e c t of another one or a group of f a c t o r s c o r r e l a t e d w i t h i t . How great i s the i n d i v i d u a l i n f l u e n c e of each of them and each event i n the h i s t o r y of the stand i s onl y a matter of o p i n i o n u n t i l data p e r m i t t i n g the a n a l y s i s are c o l l e c t e d . 31 In s p i t e of the presented r e s e r v a t i o n s i t appears from the a n a l y s i s of c l i m a t i c data t h a t p r e c i p i t a t i o n has a v e r y important i n d i r e c t e f f e c t on the d i s t r i b u t i o n of f o r e s t t r e e s p e c i e s through i t s e f f e c t on f o r e s t f i r e s . The season of minimum r a i n f a l l c o i n c i d e s w i t h maximum sunshine and temperature d u r i n g summer months ( F i g u r e 3, Appendices 1, 2, 3, 4). Low p r e c i p i t a t i o n and h i g h temperature account f o r h i g h l y inflammable f o r e s t l i t t e r . Past f i r e s may have been caused by the a c t i v i t i e s of Indians although l i g h t n i n g storms are more probable s i n c e the f i r e s i n c e r t a i n years e v i d e n t l y seem to have been wide-spread. (The most re c e n t c r i t i c a l l i g h t n i n g storm i n Vancouver F o r e s t D i s t r i c t occurred i n J u l y 19^1 when a t o t a l of 240 f o r e s t f i r e s were i g n i t e d . ) The i n c r e a s e of white p o p u l a t i o n brought other causes of f o r e s t f i r e s ; p i o n e e r la n d c l e a r i n g , c a r e l e s s n e s s of hunters and p r o s p e c t o r s , camping, smoking, r a i l w a y c o n s t r u c t i o n and t r a n s p o r t , r a i l w a y l o g g i n g and other minor causes. F i r e s seem to be the most e f f e c t i v e i n d i r e c t environmental f a c t o r o p e r a t i v e i n the p a s t . The p r e s e n t study r e v e a l e d t h a t o n l y i n h i g h e l e v a t i o n s and i n wet pockets i n the v a l l e y s were t r u l y a l l aged stands found. These are com-posed of shade t o l e r a n t s p e c i e s o n l y and are the o l d e s t stands i n the a r e a . Probably these stands have not been s u b j e c t t o f i r e damage f o r over 500 y e a r s . In the absence of f i r e f i v e 32 to s i x c e n t u r i e s are r e q u i r e d f o r the development of a mature climax f o r e s t which a c c o r d i n g to p o l l e n p r o f i l e s would i n d i c a t e t h a t f i r e s have been widespread and frequent down through the ages (Munger, 1940j Hansen, 1947). The m a j o r i t y of the p l o t s s t u d i e d c o n t a i n t r e e l a y e r s of almost u n i f o r m age. I t seems l o g i c a l t o assume t h a t the o l d e s t l a y e r o r i g i n a t e d a f t e r a complete d e s t r u c t i o n of the p r e v i o u s stand and subsequent l a y e r s a f t e r d i s t u r b a n c e s of l e s s e r i n t e n s i t y , when only some of the t r e e s were destroyed and opened the stand s u f f i c i e n t l y f o r subsequent r e g e n e r a t i o n . Judging from the present and g i v i n g due allowance f o r wind-, snow and I n s e c t damage, a great m a j o r i t y of the stands s t u d i e d o r i g i n a t e d a f t e r f i r e s . F i r e s a l s o have been the most e f f e c t i v e s e l e c t i v e f a c t o r , f a v o u r i n g l i g h t demanding s p e c i e s , those w i t h e a r l y drought-and h e a t - r e s i s t a n t s e e d l i n g s ( D o u g l a s - f i r and p i n e s ) , those able to withstand the damage, as w e l l as those whose seed could t r a v e l over c o n s i d e r a b l e d i s t a n c e s i n t o burnt-over are a s . Species r e a d i l y destroyed and those w i t h heavy seed were a f f e c t e d a d v e r s e l y ( H a n z l i k , 1914; Munger, 1913; Schmidt, 1957). Seed bed c o n d i t i o n a l s o produced an important s e l e c t i v e c o n t r o l . Where D o u g l a s - f i r grows i n the study area i t com-monly occurs i n the upper canopy and i s always of f a i r l y u n i f o r m age. Because of i t s shade i n t o l e r a n c e and i n a b i l i t y t o c o l o n i z e deep humus l a y e r s , i t i s l i k e l y t h a t the m a j o r i t y To follow page 32 j 1 J 33 of stands c o n t a i n i n g D o u g l a s - f i r o r i g i n a t e d on areas denuded by f i r e . In the absence of d i s t u r b a n c e , more s h a d e - t o l e r a n t s p e c i e s r e p l a c e D o u g l a s - f i r and c o l o n i z e the h a b i t a t per-manently. In order t o obt a i n at l e a s t some i d e a of the extent and frequency of f i r e s i n the s t u d i e d area, the age of a l l the t r e e l a y e r s was p l o t t e d i n F i g u r e 4. These data i n d i c a t e that the f i r e s were more of l o c a l than r e g i o n a l extent but a l s o t hat most of the r e g i o n was at one time or another s e v e r e l y damaged by them. A l s o i t shows t h a t f i r e s o ccurred p e r i o d i c a l l y , damaging f o r e s t s i n c e r t a i n years much more s e v e r e l y than i n other s . A l l o w i n g c e r t a i n amount of time f o r the r e -establishment of the f o r e s t a f t e r f i r e , i t i s p o s s i b l e from F i g u r e 4 to conclude that i n the l860's there was a ve r y e x t e n s i v e f i r e i n the U. B. C. Research F o r e s t . The graph a l s o shows two small f i r e s around 1830 and 1800 and three more e x t e n s i v e ones around 1770, 1660, and 1550. L i k e w i s e , a study of data from other l o c a l i t i e s i n d i c a t e s t h a t f i r e s were of frequent occurrence throughout the r e g i o n . Coquitlam V a l l e y was d i s t u r b e d around 1890, i860, 1790, 1690 and 1540. Mount Seymour was s e v e r e l y burned i n 1890, 1840, 1690 w i t h p o s s i b l y a few s m a l l e r f i r e s between. In Vancouver and v i c i n i t y f i r e s occurred around 1880 and 1840. 34 As new f i r e s , l o g g i n g and other d i s t u r b a n c e s cover the area, the pas t i s more and more d i f f i c u l t t o r e c o n s t r u c t . The w r i t e r t h e r e f o r e does not c l a i m any great accuracy f o r these f i g u r e s . I t i s q u i t e probable t h a t some of the suggested f i r e s were damages of another k i n d or t h a t the accumulation of data i n a c e r t a i n year occurred by chance. These data are i n gen e r a l agreement w i t h dates of major f i r e s a l r e a d y e s t a b l i s h e d from other sources; f o r example, a t U. B. C. Research F o r e s t f i r e s are known t o have occurred i n 1868, 1840, and 1780, and at Seymour Mountain i n 1900. CHAPTER I I I METHODS OF FIELD WORK The f i e l d work on the p r o j e c t extended over a p e r i o d of 27 months begi n n i n g May, 1958. In summer, 1958, a f t e r g e n e r a l reconnaissance work w i t h Dr. K r a j i n a , 68 o n e - f i f t h acre p l o t s were analyzed and the t o t a l by the end of summer, 1959 reached 178. In each p l o t the g e n e r a l topography, such as e l e v a t i o n , s l o p e , aspect, shape of contour, shape of p r o f i l e , p o s i t i o n on sl o p e , and wind exposure were d e s c r i b e d t o assess t h e i r r e l a t i v e importance on the composition of the p l a n t community and the p r o d u c t i v i t y of f o r e s t t r e e s . V e g e t a t i o n was analyzed i n the f o l l o w i n g way: 1. The cover of f o u r v e g e t a t i o n l a y e r s was estimated i n p e r c e n t . A - t r e e s , B-shrubs, C-herbs, D-mosses and l i c h e n s . 2. A l l p l a n t s w i t h i n t h e i r r e s p e c t i v e l a y e r s were l i s t e d , w i t h numerical d e s c r i p t i o n g i v i n g t h e i r s p e c i e s s i g n i f i c a n c e , s o c i a b i l i t y a n d / v i g o r , a c c o r d i n g t o the method of Braun-Blanquet (1928) and m o d i f i e d by K r a j i n a (1933). Species s i g n i f i c a n c e as w e l l as s o c i a b i l i t y were given 11 grades i n a l o g a r i t h m i c a l s c a l e so t h a t seldom-occurring s p e c i e s could be more a c c u r a t e l y r e g i s t e r e d . Species 35 36 s i g n i f i c a n c e : + s o l i t a r y , w i t h very small dominance 1. seldom, w i t h small dominance 2. v e r y s c a t t e r e d , w i t h s m a l l dominance 3. s c a t t e r e d , w i t h s m a l l dominance 4. f r e q u e n t , cover 5-10$ 5. frequent, cover 10-20$ 6. any number, cover 20-33$ 7. any number, cover 33-50$ 8. any number, cover 50-75$ 9. any number above 75$ "but l e s s than complete dominance 10. complete dominance. S o c i a b i l i t y : + i n d i v i d u a l , s o c i a b i l i t y none 1. groups up to 4 x 4 cm (3 sq. inches) 2. groups up t© 25 x 25 cm. (l sq. foot} 3. groups up to 50 x 50 cm. (4 sq. f e e t ) 4. 1/3-2/3 m2 (4-7 sq. f e e t ) 6. 2-10 m2 (20-100 sq. f e e t ) 7. 10-50 m2 (100-500 sq. f e e t ) 8. 50-200 m2 (500-2000 sq. f e e t ) 9. 200-500 m2 (2000-5000 sq. f e e t ) 10. above 500 m.2 V i g o r of s p e c i e s was given 4 grades: 0 germinating but not s u r v i v i n g 1. f e e b l e but able to s u r v i v e 2. s t r o n g but not r e a c h i n g maximum v i g o r 3. w i t h maximum v i g o r and development found i n the s p e c i e s . V e g e t a t i o n was d e s c r i b e d and analyzed by Mr. O r l o c i . S o i l was d e s c r i b e d from a r e p r e s e n t a t i v e s o i l pro-f i l e . For t h a t purpose a s o i l p i t , sometimes two, was dug i n the sample p l o t . Terminology of the U. S. Department of A g r i c u l t u r e S o i l Survey Manual (1951) and the F o r e s t S o i l Committee of the D o u g l a s - f i r r e g i o n was used f o r d e s c r i p t i o n . Depth of solum, t h i c k n e s s of h o r i z o n s , c o l o r , t e x t u r e s t r u c t u r e , c o n s i s t e n c y , s o i l moisture, p e r m e a b i l i t y , parent m a t e r i a l , s t o n i n e s s and humus were d e s c r i b e d . D e t a i l s of s o i l d e s c r i p t i o n w i l l be presented l a t e r . The depth and d i s t r i b u t i o n of r o o t s were noted i n each s o i l p i t . A s o i l sample was c o l l e c t e d from each d i s t i n g u i s h a b l e h o r i z o n f o r f u r t h e r a n a l y s i s . The pH of a l l the samples and a chemical a n a l y s i s of r e p r e s e n t a t i v e s o i l s were undertaken. S o i l s were d e s c r i b e d , and samples c o l l e c t e d , and l a t e r analyzed by Mr. Lesko. On a l l the examined p l o t s i n a d d i t i o n to p l a n t com-munity seventeen other v a r i a b l e s were taken i n t o c o n s i d e r a t i o n f o r the a n a l y s i s of the g e n e r a l environment and i t s i n f l u e n c e on s i t e p r o d u c t i v i t y . The w r i t e r r e a l i z e s f u l l y the l i m i t -a t i o n s of the use of only seventeen v a r i a b l e s . There are many more f a c t o r s known to be i n f l u e n c i n g the s i t e p r o d u c t i v i t y and many more s t i l l w i l l be found i n the f u t u r e . The seventeen v a r i a b l e s were s e l e c t e d f o r d e f i n i t e reasons: T o p o g r a p h i c a l f a c t o r s are r e c o g n i z a b l e from a e r i a l photo-graphs; p l a n t a s s o c i a t i o n , s o i l and moisture c o n d i t i o n s t o gether w i t h t o p o g r a p h i c a l f e a t u r e s are e a s i l y and f a i r l y a c c u r a t e l y r e c o g n i z a b l e i n the f i e l d . Genetic v a r i a t i o n , m i c r o c l i m a t e or h i s t o r y of the p l o t , or any other v a r i a b l e whi cou l d not be measured at a l l or estimated w i t h i n a reasonable time on every p l o t , and hence could not be used f o r product-i v i t y assessment, were not c o n s i d e r e d . The seventeen s e l e c t e d v a r i a b l e s were: 38 A. Topo g r a p h i c a l f e a t u r e s X 1. Mi c r ot op ography: 1 2 simple complex ( r i d g e s , humps) X 2. Average Slope: 0 1 2 3 4 0$ 0-0.5$ 0.6-2.0$ 7 8 5 6 10-15$ 16-30$ 31-50$ 50-100$ 2.1-5$ 5.1-9$ 9 more than 100$ X 3. E l e v a t i o n i n hundreds of f e e t . X 4. Azimuth r e a d i n g i n tens of degrees. X 5. Shape of contours ( h o r i z o n t a l l i n e s of the e a r t h s u r f a c e ) i n a r b i t r a r y s c a l e of ten grades: 0 extremely convex 1 v e r y convex 2 moderately convex 3 s l i g h t l y convex 4 almost s t r a i g h t , v e r y s l i g h t l y convex 5 almost s t r a i g h t , v e r y s l i g h t l y concave 6 s l i g h t l y concave 7 moderately concave 8 v e r y concave 9 extremely concave X 6. Shape of p r o f i l e ( v e r t i c a l l i n e s of the e a r t h surface) In f i v e grades: 1 v e r y convex 2 moderately convex 3 s t r a i g h t 4 moderately concave 5 v e r y concave X 7. P o s i t i o n on slope i n ten grades: 0 peak, r i d g e s l o p i n g t o s e v e r a l d i r e c t i o n s 1 j u s t below the peak or r i d g e s l o p i n g to one d i r e c t i o n 2 f u r t h e r from the peak or edge of the t e r r a c e 3 upper slope 4 upper p a r t of the 'mid slope 5 lower p a r t of the mid slope 6 lower slope 39 7 s l o p e s near the bottom of d e p r e s s i o n 8 g e n t l y s l o p i n g ground near the d e p r e s s i o n 9 f l a t bottom of the v a l l e y or the d e p r e s s i o n i t s e l f X 8. Wind exposure i n ten grades: 0 extremely p r o t e c t e d 1 v e r y p r o t e c t e d 2 moderately p r o t e c t e d 3 s l i g h t l y p r o t e c t e d 4 v e r y s l i g h t l y p r o t e c t e d 5 v e r y s l i g h t l y exposed 6 s l i g h t l y exposed 7 moderately exposed 8 v e r y exposed 9 extremely exposed B. S o i l and Water regime X 9. S o i l parent m a t e r i a l i n nine groups: 1 r o c k outcrop 5 a l l u v i a l g r a v e l 2 g l a c i a l t i l l 6 a l l u v i a l sands 3 g l a c i a l outwash 7 a l l u v i a l loam 4 l o c a l outwash 8 l a c u s t r i n e d e p o s i t s 9 organic d e p o s i t s X 10. Depth of the s o i l grouped by 6 inches 0 0- 6" 5 30-36" 1 6-12" 6 36-42-"-2 12-18" 7 42-48" 3 18-24" 8 48-60" 4 24-30" 9 more than 60" X 11. Stoniness i n p e r c e n t s of volumes of stones X 12. Presence of seepage or ground water 1 never, except immediately a f t e r the r a i n 2 seldom and f o r short p e r i o d s 3 c ommon 4 f r e q u e n t and f o r c o n s i d e r a b l e time 5 always X 13. S o i l moisture at the time of excavation of the s o i l p i t 1 dry 2 s l i g h t l y moist 3 moist 4 wet 5 water -saturated X 14. S o i l p e r m e a b i l i t y 1 e x c e s s i v e , extremely r a p i d 2 w e l l permeable, movement of water r a p i d 3 moderately permeable 4 s l o w l y permeable 5 not permeable 4o X 15. Thickness of organic h o r i z o n s (L, F and H combined) 0 0" 5 4- 5" 1 0-1" 6 5- 7" 2 1-2" 7 7- 9" 3 2-3" 8 9-12" 4 3-4" 9 more than 12" X 16. Thickness of Ae l a y e r 0 none 1 broken, t h i n 2 broken, more than 0.5 inches t h i c k 3 continuous up t o 0.5 inches t h i c k 4 continuous 0.5-1 i n c h 5 continuous 1.0-1.5 inches 6 continuous 1.5-2.0 inches 7 continuous 2.0-3.0 inches 8 continuous 3.0-5.0 inches 9 continuous more than 5 inches C. S i t e index as p r o d u c t i v i t y measure P r o d u c t i v i t y of the s i t e expressed by s i t e Index of the most important s p e c i e s on the p l o t was co n s i d e r e d a dependent v a r i a b l e Y. I t was c a l c u l a t e d from the f i e l d data a f t e r the f i e l d work was te r m i n a t e d . Trees above the diameter of 3 inches were t a l l i e d a c c o r d i n g t o the s p e c i f i c a t i o n s of the B. C. F o r e s t S e r v i c e , Surveys D i v i s i o n , Sampling Manual (1954-1957). Diameter, t r e e c l a s s , q u a l i t y c l a s s , crown c l a s s and type of v i s i b l e damage of a l l i n d i v i d u a l t r e e s were re c o r d e d . The age and height of s e v e r a l dominants and codominants of each s p e c i e s were measured and the age of a l l d i s t i n c t secondary crown l a y e r s were a l s o r e c o r d e d . A l s o a l l stumps and snags were measured t o permit of an estimate of p r o d u c t i v i t y from the p r e v i o u s stand. 41 I t Is important t o note t h a t the summer of 1958 was e x c e p t i o n a l l y warm and dry and t h a t the p l o t s No. 1-68 as f a r as d e s c r i p t i o n of s o i l moisture i s concerned were d e s c r i b e d as d r i e r than they are i n normal y e a r s . The summer 1959 i n which t h i s p a r t of the f i e l d work ended was almost average ( F i g u r e 3). C l i m a t i c measurements In May, 1959 a t o t a l of nine m e t e o r o l o g i c a l s t a t i o n s were e s t a b l i s h e d i n the U. B. C. Research F o r e s t t o study the m i c r o c l i m a t e i n the seven most important p l a n t communities i n the r e g i o n . One s t a t i o n was e s t a b l i s h e d i n the Vaccinium-S a l a l Vaccinium-Moss t r a n s i t i o n (without hygrothermograph) and one o u t s i d e the f o r e s t t o study and compare c o n d i t i o n s i n the d e f o r e s t e d area. In w i n t e r , where snow cover became e x c e p t i o n a l l y high, the snow around the instruments was trampled down or the instruments e l e v a t e d above the snow l e v e l . Where necessary, e x i t s a l s o were trampled down l e a d i n g t o lower ground t o minimize the p r o b a b i l i t y of abnormally low temperatures w i t h i n the a r t i f i c i a l l y c r e a t e d shallow b a s i n s around the instruments. A Stevenson's screen of approximately standard dimensions was i n s t a l l e d i n each s t a t i o n , on the ground, because the aim was to study the m i c r o c l i m a t e . Each screen housed the R. Fuess-type hygrothermograph of I d e n t i c a l d e sign 42 and at the b e g i n n i n g of the study a l s o S i x-type max-min. thermometers. Wet and dry bulb thermometers were i n s t a l l e d to s t a n d a r d i z e the hygrothermographs. The max.min. thermo-meter soon was used elsewhere, because the d i f f e r e n c e between i t s r e a d i n g and thermograph was c o n s t a n t . T h i s d i f f e r e n c e d i d not change d u r i n g the whole p e r i o d of study. The wet-and-dry bulb thermometer was removed because of i t s u s e l e s s n e s s without a fan and because the l a r g e c o n t a i n e r of water, con-nected w i t h the bulb by a short wick t r a n s m i t t e d s t o r e d energy t o the bulb d u r i n g p e r i o d s of h i g h humidity. Instead, a s l i n g psychrometer was p e r i o d i c a l l y used. L a t e r i t was found t h a t almost every week the humidity reached 100 per cent at a l l s t a t i o n s . T h i s p o i n t p r o v i d e d a most u s e f u l means f o r a d j u s t -ment and comparison of r e a d i n g s . Only o c c a s i o n a l checks w i t h a s l i n g psychorometer were necessary s i n c e instruments gener-a l l y agreed w i t h psychrometer r e a d i n g s . A l l instruments used were c a l i b r a t e d before use i n the f i e l d . Hygrothermographs i n completely s a t u r a t e d atmosphere were c a l i b r a t e d by the method recommended and d e s c r i b e d by the manufacturer; atmometers were c a l i b r a t e d by the manufacturer and t h e i r c o e f f i c i e n t w r i t t e n on each bulb; f i b r e g l a s s s o i l - u n i t s were c a l i b r a t e d by the manufacturer f o r temperature. Thermometers were checked and compared at three p o i n t s by submerging them i n a mixture of water and i c e , and water of approximately 60 and 100° F. 43 Atmometers were rechecked a f t e r the f i r s t summer and cleaned. A l l instruments were again c a l i b r a t e d at the end of the f i e l d work and readings c o r r e c t e d f o r o c c a s i o n a l d r i f t s . D u ring the f i e l d work thermometers and thermographs were checked c o n s t a n t l y a g a i n s t each other, by p l a c i n g them a l l t o g e t h e r I n t o the screen f o r a few hours. Agreement of temperature readings by thermometer was always v e r y h i g h and thermograph d i f f e r e n c e s were constant e s p e c i a l l y d u r i n g p e r i o d s of cloudy and r a i n y weather. To compare data on temperature between p l o t s , a spare max.-min. thermometer was used and p l a c e d p e r i o d i c a l l y w i t h one.of the thermometers on the p l o t . From these prechecks, in-use, and f i n a l checks, i t i s b e l i e v e d t h a t temperature measurements of a l l instruments are w i t h i n 1/2° F. of t r u e v a l u e s . The only problem w i t h the hygrothermograph was expansion of c h a r t s d u r i n g humid p e r i o d s and shrinkage away from the drum f l a n g e d u r i n g succeeding dry p e r i o d s . T h i s could have caused a d i s c r e p a n c y of about 1 ° F. i n tempera-tu r e and up t o 2$ i n humidity r e a d i n g . Such d i s c r e p a n c i e s were unavoidable when instruments were not checked d a i l y . D uring the w i n t e r , snow depth was measured at s e v e r a l p l a c e s i n each p l o t and average readings f o r a p l o t r e c o r d e d . These readings p r o v i d e d u s e f u l i n f o r m a t i o n not only about snow accumulation, s e t t l i n g and m e l t i n g , but a l s o about the i n t e r r e l a t i o n s h i p between temperature and snow cover. 44 Outside the screen at each s t a t i o n were 6 L i v i n g s t o n white bulb atmometers t© p r o v i d e the data on ev a p o r a t i o n , humidity of the a i r and i t s movement. F i v e of them were p l a c e d at random p o s i t i o n s 9 inches from the ground and one was p l a c e d above the shrub v e g e t a t i o n . Even i f t h e i r r e a d i n g s have no d i r e c t b e a r i n g on t r a n s p i r a t i o n of p l a n t s or evapor-a t i o n from the s o i l , t h e i r main value i s f o r comparison of r e l a t i v e humidity near the ground between d i f f e r e n t s t a t i o n s . Atmometers had to be removed d u r i n g the w i n t e r . Three n o n - s h e l t e r e d Six-type max.-min. thermometers were used on each s t a t i o n . One p l a c e d on the northern s i d e of a t r e e about 7 f e e t h i g h , and two on the ground w i t h t h e i r bulbs j u s t covered w i t h a t h i n l a y e r of l i t t e r . These pro-v i d e d maximum and minimum temperatures of the ground or humus s u r f a c e . E i g h t r a i n gauges i n each p l o t were p l a c e d at random t o e l i m i n a t e l o c a l e f f e c t s . These p r o v i d e d not o n l y data on r e l a t i v e p r e c i p i t a t i o n r e a c h i n g the ground but a l s o an e s t i -mate of the r e l a t i v e d e n s i t y of the canopy. During the wint e r r a i n gauges were e l e v a t e d above the snow l a y e r and s a l t was added so t h a t snow co u l d r e a d i l y be measured i n e q u i v a l e n t amounts of water. At each of the e i g h t s t a t i o n s three s e t s of Coleman f i b r e g l a s s u n i t s were I n s t a l l e d t o o b t a i n s o i l moisture and temperature d a t a . The u n i t s , the manufacturer claims, are 45 durable and a c c u r a t e . They c o n t a i n a t h e r m i s t e r thus p e r m i t t i n g s o i l temperature measurements t o he taken w i t h each s o i l moisture r e a d i n g . Procedures d e s c r i b e d by the manufacturer f o r t h e i r i n s t a l l a t i o n , c a l i b r a t i o n and measurement of mois-tu r e and temperature were f o l l o w e d . The r e s u l t s of s o i l temperature and s o i l moisture study, which s t i l l r e q u i r e s more work, w i l l be a t o p i c of a separate paper. D e s c r i p t i o n of c l i m a t i c s t a t i o n s A l l s t a t i o n s were s i t u a t e d In the U. B. C. Research F o r e s t . The aim was t o study the m i c r o c l i m a t e In the.most important u n i f o r m p l a n t communities. Because c e r t a i n p l a n t communities occur predominantly i n high e r e l e v a t i o n s and i n wetter h a b i t a t s and others i n lower e l e v a t i o n s and d r i e r h a b i t a t s , the s t a t i o n s were s i t u a t e d i n two t r a c t s . The upper t r a c t s above P l a c i d and Gwendoline Lakes i n c l u d e d f i v e s t a t i o n s , one a c o n t r o l s t a t i o n i n the open, the other f o u r under the f o r e s t cover. At lower e l e v a t i o n s , southwest of Blaney Lake, there were f o u r s t a t i o n s , a l l i n the f o r e s t . T h i s s e t - o f p l o t s l i e s approximately halfway between Loon Lake camp and A. E. Marc's farm, where m e t e o r o l o g i c a l measurements are^taken d a i l y . I t should be p o s s i b l e t o use these s t a t i o n s as r e f e r e n c e p o i n t s . Loon Lake camp s t a t i o n i s a standard m e t e o r o l o g i c a l s t a t i o n w i t h hygrothermograph, max.-min. thermometer i n the s h e l t e r and a r a i n gauge. I t 46 i s s i t u a t e d on the northern slope f a c i n g the lake at an e l e v a t i o n of approximately 1180 f e e t , about 3/4 of a m i l e e x a c t l y n o r t h from Blaney Lake t r a c t p l o t s . Marc's farm i s a standard Department of Transport m e t e o r o l o g i c a l s t a t i o n . I t i s s i t u a t e d S on a g e n t l e s o u t h e r l y slope at an e l e v a t i o n of about 550 f e e t . I t i s approximately one mile S20E from Blaney Lake T r a c t . Table 1. D e s c r i p t i o n of the m i c r o c l i m a t i c s t a t i o n s . S t a t i o n -P l o t No. A s s o c i a -t i o n A l t i t u d e Wind exposure Sun exposure Slope Azimuth Shape of contours Shape of p r o f i l e S o i l depth S t o c k i n g Stand P l a c i d Lake T r a c t - Wetter Subzone S t a t i o n s C o n t r o l 1710 SW, S, SE, N Sunrise to 4 p.m. 0-60$ a l l convex convex none 5$ regener-a t i o n I.-108 Vaccinium-Moss 1820 Pro-t e c t e d Sunrise t o 10 a .m. 30$ 360° concave s t r a i g h t 48" 90$ mature II.-52 Vaccinium-S a l a l 1810 ~ NW, N, NE, E Sunrise t o 4 p.m. 0-25$ i4o-250 convex convex 5-14" 60$ mature III.-49 Blechnum 1780 NE, E, SE, S .Sunrise to 1 p.m. 30$ 80° concave s t r a i g h t 10-24" 80$ mature IV.-54 Vacc.-Moss V a c c . - S a l a l T r a n s i t i o n 1720 E, SE Sunrise to 3 p.m. 0-5$ 120° convex s t r a i g h t 10-24" 90$ younger mature Table 1. (continued) S t a t i o n -P l o t No. A s s o c i a -t i o n A l t i t u d e Wind exposure Sun exposure Slope Azimuth Shape of contours Shape of p r o f i l e S o i l depth S t o c k i n g Stand Blaney Lake T r a c t - D r i e r Subzone S t a t i o n s V.-44 Moss 950 W, E 8 a.m. to 4 p.m. 20$ 210° s t r a i g h t concave 30-45" 95$ mature vi.-104 S a l a l 1040 S,SW,W, NW,N,NE 11 a.m. to sunset 10$ 260 convex convex 2-14" 5$ o l d e r immature VII.-42 P o l y s t i c h u m 920 W, NW, W 11 a.m. to sunset 12$ 330° concave concave 24-44" 60$ mature VIII.-43 Vaccinium L y s i c h i t u m 940 W, E 9 a.m. to 4 p.m. 0$ 27° (o) concave concave 3-12" 50$ mature 00 CHAPTER IV ANALYSIS OF THE DATA Mathematical approach Without exceptions the purpose of any s t a t i s t i c a l study i s t o f u r n i s h a b a s i s f o r g e n e r a l i z a t i o n . In s t a t i s -t i c a l terms i t Is t o p r o v i d e i n f o r m a t i o n about the u n i v e r s e , while a n a l y z i n g o n l y an unbiased sample. A c e r t a i n group of o b j e c t s i s examined and from t h e i r p r o p e r t i e s , are i n f e r r e d the p r o p e r t i e s of other o b j e c t s of the same k i n d . With r e s p e c t t o the m a t e r i a l sampled, i t has to be assumed t h a t there i s a l a r g e u n i v e r s e of items s u b j e c t 'to more or l e s s u n i f o r m c o n d i t i o n s and t h a t throughout the u n i v e r s e the i n d i v i d u a l items v a r y among themselves i n response t o the same causes w i t h about the same v a r i a b i l i t y . With r e s p e c t t o the s e l e c t i o n of the sample the value s must be s e l e c t e d so th a t ( l ) the s u c c e s s i v e items i n the sample are not s e l e c t e d from d i f f e r e n t p o r t i o n s of the u n i v e r s e i n r e g u l a r order, but are p i c k e d at random, so t h a t the chance of the occurrence of any p a r t i c u l a r value i s the same i n each s u c c e s s i v e observ-a t i o n i n the sample, (2) there i s no r e l a t i o n between the s i z e of s u c c e s s i v e o b s e r v a t i o n s , that i s , t h a t the chances of a hi g h o b s e r v a t i o n b e i n g f o l l o w e d by another h i g h o b s e r v a t i o n are the same as of a low or medium, (3) the sample i s not 49 s e l e c t e d e n t i r e l y from one p o r t i o n of the u n i v e r s e hut t h a t o b s e r v a t i o n s are s c a t t e r e d throughout the u n i v e r s e p u r e l y by chance. In " s t r a t i f i e d samples" where the items are s e l e c t e d t o r e p r e s e n t d i f f e r e n t p o r t i o n s of the u n i v e r s e , e.g. i n t h i s study the a s s o c i a t i o n s , the d i s p e r s i o n of samples through the sampled p o r t i o n must a l s o be by chance. In the f o l l o w i n g a n a l y s i s , c o n d i t i o n ( l ) i s f u l -f i l l e d o nly i f the study i s c o n s i d e r e d l o c a l and i t s l i m i t -a t i o n s r e c o g n i z e d and e x t r a p o l a t i o n s performed w i t h great c a r e . C o n d i t i o n (2) i s f u l f i l l e d . C o n d i t i o n (3) r e q u i r e s an e x p l a n a t i o n concerning the l o c a t i o n of the p l o t s . Con-c e n t r a t i o n of the p l o t s i n c e r t a i n areas occurred because of b e t t e r a c c e s s i b i l i t y . However, t h i s b r i n g s a c e r t a i n amount of b i a s i n t o the a n a l y s i s . Roads were c o n s t r u c t e d i n t o areas b e a r i n g b e t t e r timber more of t e n than i n t o areas where the timber was of low q u a l i t y or i n s m a l l q u a n t i t i e s . At lower e l e v a t i o n s other uses of the l a n d have r e p l a c e d the f o r e s t and a c e r t a i n p o r t i o n of the area sampled i s r e p r e s e n t e d by n o n - r e p r e s e n t a t i v e remains. I t i s q u i t e probable t h a t the averages c a l c u l a t e d from samples from lower a l t i t u d e s are d i f f e r e n t than they would be i f the samples c o u l d have been taken a l s o from areas now used as farm l a n d . But the w r i t e r f e e l s t h a t i n the area under study the farm land w i l l never be r e t u r n e d t o f o r e s t p r o d u c t i o n . R e a l i z i n g the above m o d i f i c a t i o n s of c o n d i t i o n s ( l ) and (3), the a n a l y s i s should b r i n g v e r y u s e f u l r e s u l t s . 51 Before d i s c u s s i n g the que s t i o n of how r e l i a b l e a s t a t i s t i c a l average must be, i t i s necessary to c o n s i d e r the meaning of " r e l i a b l e " . I f , f o r example, s i t e index i s con-s i d e r e d as a measure of p r o d u c t i v i t y , i t i s obvious t h a t a p e r f e c t l y r e l i a b l e sample would be one whose average would agree e x a c t l y w i t h the average s i t e index of the a s s o c i a t i o n s t u d i e d . But i f we are i n t e r e s t e d t o know the s i t e index w i t h i n ten f e e t , then f o r t h a t purpose the sample would be s u f f i c i e n t l y r e l i a b l e i f i t s average i s almost c e r t a i n to come w i t h i n ten f e e t of the t r u e average. We need to know how r e l i a b l e i s our sample, whether i t s a t i s f i e s the r e q u i r e d accuracy, or how much f a i t h can be given t o the p a r t i c u l a r average t h a t we a l r e a d y have. About s i x t y - e i g h t per cent of the sample averages l i e w i t h i n one standard d e v i a t i o n on each sid e of the mean of the sample. (The average obtained might be any of those i n a normal d i s t r i b u t i o n . ) The degree of confidence which can be p l a c e d i n a given average can be estimated by computing the estimate of the standard d e v i a t i o n of s i m i l a r averages, computed from random samples of the same number of items drawn from the same u n i v e r s e . T h i s a f f o r d s a u s e f u l check on the d e p e n d a b i l i t y of r e s u l t s without r e p e a t i n g the f i e l d work and doing s e r i e s of new samples. The standard d e v i a t i o n of the averages or the standard e r r o r of the mean may be c a l c u l a t e d by d i v i d i n g the 52 estimated, standard d e v i a t i o n by the square r o o t of a number of measurements i n the sample. I t has been shown that the means of s u c c e s s i v e random samples are d i s t r i b u t e d i n a manner c l o s e to a normal curve, even i f the d i s t r i b u t i o n of the o r i g i n a l o b s e r v a t i o n s i s f a r from normal ( K e n d a l l , 1959). Where the sample s i z e Is l a r g e enough (25 or more) the i n t e r v a l M + w i l l i n c l u d e the t r u e mean i n s i x t y - e i g h t per cent of a l l such samples. The I n t e r v a l M + 2 w i l l i n c l u d e the true mean i n n i n e t y - f i v e per cent of such samples. These confidence i n t e r v a l s i n d i c a t e the degree of confidence we can p l a c e i n s t a t i s t i c s d e r i v e d from t h a t sample as an approximation of the parameters of the u n i v e r s e . When the sample s i z e i s s m a l l e r than t w e n t y - f i v e o b s e r v a t i o n s the d i s t r i b u t i o n o f , s u c c e s s i v e parameters i s somewhat d i f f e r e n t from the normal d i s t r i b u t i o n . The p r o p o r t i o n of samples i n which the s t a t e d confidence i n t e r v a l w i l l i n c l u d e the t r u e mean i s s m a l l e r . The s m a l l e r the num-ber of o b s e r v a t i o n s , the more s e r i o u s i s the d i f f e r e n c e . The most important value of standard e r r o r l i e s i n the p o s s i b i l i t y of u s i n g i t f o r -an e s t i m a t i o n of the d e p e n d a b i l i t y of our r e s u l t s u s i n g samples of d i f f e r e n t s i z e s . In a sample of t w e n t y - f i v e p l o t s we can say t h a t there i s s i x t y - e i g h t per cent of p r o b a b i l i t y t h a t the t r u e parameter l i e s w i t h i n one standard e r r o r of our sample para-meter and n i n e t y - f i v e per cent p r o b a b i l i t y t h a t i t l i e s w i t h i n 53 two standard e r r o r s around the mean. In samples of f o u r o b s e r v a t i o n s , however, on l y s i x t y per cent l i e w i t h i n one and e i g h t y - s i x per cent w i t h i n two standard e r r o r s from the mean. I f we analyze our r e l a t i o n s g r a p h i c a l l y , then an exact mathematical l i n e or e s p e c i a l l y a complicated curve has a d e f i n i t e advantage over a f r e e hand method only when there i s a good l o g i c a l b a s i s f o r a d e f i n i t e type of r e l a t i o n and the mathematical formula i s the e x p r e s s i o n of the r e a l nature of the r e l a t i o n s h i p . In other cases the mathematical curve i s no more r e l i a b l e than the f r e e hand curve. But i n d e f i n i t e r e l a t i o n s i t can be used to p r o v i d e a "law" to s t a t e the nature of the r e l a t i o n s . Since the number of o b s e r v a t i o n s u s u a l l y d i f f e r s a l ong the a x i s r e p r e s e n t i n g the independent v a r i a b l e , i t may be much more r e l i a b l e i n the c e n t r a l p a r t s where the b u l k of o b s e r v a t i o n s occur. T h i s i s v e r y s e r i o u s i n complex curves -as i n the graph r e p r e s e n t i n g the b a s a l area or the volume of the stand where a s i n g l e extreme o b s e r v a t i o n may have a m a t e r i a l e f f e c t on the shape of the end p o r t i o n . Only those p o r t i o n s of the curve where there are enough o b s e r v a t i o n s can be regarded as s t a t i s t i c a l l y j u s t i f i e d , end p o r t i o n s of the curve are rough approximations only, w i t h a l e s s e r degree of c o n f i d e n c e . I t should be noted t h a t these e x t r a p o l a t i o n s beyond the range of observed data, however l o g i c a l they may look, are not based on s t a t i s t i c a l evidence, and t h e i r 54 reasonableness r e s t s i n the realm of l o g i c s r a t h e r than s t a t i s t i c s . T h erefore, i n t h i s work, a l l the p o i n t s r e p r e s e n t -i n g the frequences have been l e f t i n on the graphs, so t h a t the reader may determine f o r h i m s e l f the value of the w r i t e r ' s I n t e r p r e t a t i o n s . When the dependent v a r i a b l e i s estimated from one or a set of independent v a r i a b l e s the estimated values of the dependent v a r i a b l e i n many cases w i l l not be i n expected p r o p o r t i o n s of the independent v a r i a b l e . These d i f f e r e n c e s are o b v i o u s l y due to r e s i d u a l v a r i a t i o n i n the dependent v a r i a b l e which were u n r e l a t e d t o changes i n the p a r t i c u l a r set of independent v a r i a b l e s used i n the a n a l y s i s . T h i s p r o p o r t i o n c a l l e d " r e s i d u a l v a r i a n c e " g i v e s an estimate of v a r i a b i l i t y of the dependent v a r i a b l e which i s due t o unknown causes and not accounted f o r . When the same c o n d i t i o n s p r e v a i l as those under which the f i e l d data of the samples were c o l l e c t e d , I t should be p o s s i b l e t o estimate from the independent v a r i a b l e s the p r o d u c t i v i t y of the f o r e s t s i t e s . To a c t u a l l y measure the p r o d u c t i v i t y might be im p o s s i b l e i n cases where the de-s i r e d s p e c i e s are m i s s i n g , i n young stands or i n d e f o r e s t e d l a n d , and i f we have t o do the assessment of immature stands from a e r i a l photographs where we cannot measure the age and we have t o assess the p r o d u c t i v i t y mainly from p h y s i o g r a p h i c f e a t u r e s . Here the knowledge of r e s i d u a l v a r i a n c e allows one t o estimate how c l o s e l y the new estimates are l i k e l y t o 55 approximate the true but unknown y i e l d s . In i n s t a n c e s where our new o b s e r v a t i o n s of the independent v a r i a b l e s came from -a s i m i l a r but not i d e n t i c a l u n i v e r s e , as m case of t h i s study beyond the area where the b a s i c data were c o l l e c t e d , the r e s i d u a l v a r i a n c e does not give more than a c l u e or i n d i c a t i o n as to what the d i f f e r e n c e s may be i f the same c o r r e l a t i o n s are a p p l i e d to data obtained under new c o n d i t i o n s . As s t a t e d above, i n most r e l a t i o n s , e s p e c i a l l y b i o l o g i c a l ones, only p a r t of the v a r i a t i o n m the dependent v a r i a b l e can be e x p l a i n e d by the r e l a t i o n to the independent v a r i a b l e s , and the remaining causes are c a l l e d r e s i d u a l v a r i a n c e . In our study, p a r t of the v a r i a t i o n i n the depend-ent v a r i a b l e , the h e i g h t growth of the t r e e s , i s e x p l a i n e d by the p l a n t community, p a r t by physiography, p a r t by s o i l c o n d i t i o n s , and a l l these i n f l u e n c e s are l a r g e l y i n t e r - r e l a t e d , and p a r t i s not e x p l a i n e d by any measured v a r i a b l e at a l l . I t may be due t o chance f a c t o r s or a g e n e t l c a l v a r i a t i o n or many other known or unknown causes. One of the main p a r t s of t h i s study, p r o b a b l y the most important one, was t o determine what p r o p o r t i o n of the v a r i a t i o n i n the dependent v a r i a b l e can be e x p l a i n e d by the p a r t i c u l a r independent v a r i a b l e or group of v a r i a b l e s considered, a c c o r d i n g to r e l a t i o n s observed, and what p r o p o r t i o n of the v a r i a b i l i t y i n the dependent var-i a b l e i s not accounted f o r . 56 Measurement of the r e l a t i v e importance of the r e l a t i o n between v a r i a b l e s c a l l s f o r a d i f f e r e n t k i n d of s t a t i s t i c a l constant than the standard e r r o r of e s t i m a t e . Some measure showing what p r o p o r t i o n of the o r i g i n a l v a r i a -t i o n has been accounted f o r , i s needed. The r e g r e s s i o n l i n e separates each o r i g i n a l value i n t o two p a r t s , the estimated value and the r e s i d u a l . I f the o r i g i n a l v a r i a t i o n i n the estimated value i s given by i t s standard d e v i a t i o n squared and the unexplained v a r i a t i o n i n standard e r r o r of estimate squared, then the d i f f e r e n c e Is the l o g i c a l measure of the amount of v a r i a t i o n accounted f o r by the r e g r e s s i o n l i n e . I f we determine how l a r g e t h i s estimated v a r i a n c e i s compared t o the o r i g i n a l v a r i a n c e , we get the p r o p o r t i o n of v a r i a t i o n i n the dependent v a r i a b l e accounted f o r by the v a r i a t i o n i n the independent v a r i a b l e , a c c o r d i n g t o the mathematically-f i t t e d , s t r a i g h t - l i n e r e l a t i o n s h i p . The square r o o t of t h i s p r o p o r t i o n i s c a l l e d the c o r r e l a t i o n c o e f f i c i e n t . The c o r r e l a t i o n c o e f f i c i e n t s p r o v i d e a d e f i n i t e mathematical technique by which an i n v e s t i g a t o r can determine the way i n which the v a l u e s of one v a r i a b l e d i f f e r as the v a l u e s of another r e l a t e d v a r i a b l e d i f f e r . I t a f f o r d s a b a s i s f o r e s t i m a t i n g v a l u e s of the dependent v a r i a b l e from given v a l u e s of the independent v a r i a b l e by e x t r a p o l a t i n g from cases i n which t h i s c o r r e l a t i o n was determined f o r s i m i l a r cases w i t h i n the same u n i v e r s e . Whether such e s t -imated v a l u e s f o r cases not i n c l u d e d i n the o r i g i n a l study 57 can Toe expected t o agree w i t h the true values depends on two c o n s i d e r a t i o n s . 1. The meaning of a given r e l a t i o n w i t h regard s o l e l y t o the p a r t i c u l a r cases from which i t was drawn. 2. The d e p e n d a b i l i t y of the c a l c u l a t e d r e l a t i o n s t o rep r e s e n t the t r u e r e l a t i o n s e x i s t i n g i n the u n i v e r s e . The symbol r r e p r e s e n t s the c o r r e l a t i o n c o e f f i c i e n t where the r e l a t i o n s h i p between two v a r i a b l e s i s found or assumed t o be a s t r a i g h t l i n e . I f t h i s l i n e has a p o s i t i v e s lope, so t h a t as X (the va l u e s of the independent v a r i a b l e ) i n c r e a s e s the values of Y (the estimated value of the depend-ent v a r i a b l e ) a l s o i n c r e a s e , the c o r r e l a t i o n i s s a i d t o be p o s i t i v e . I f the l i n e has a negative slope the c o r r e l a t i o n i s n e g a t i v e . The c o e f f i c i e n t of c o r r e l a t i o n takes the same si g n as the constant b of the corresponding l i n e a r e q u a t i o n . In the case of the per cent of slope i n t h i s study, while the X may be con s i d e r e d drawn at random from a s t a b l e u n i v e r s e i t s f u n c t i o n does not f o l l o w a b i v a r i a t e normal d i s t r i b u t i o n (see the s c a l e on F i g u r e 25). The c o r r e l a t i o n c o e f f i c i e n t t h e r e f o r e must be regarded as an estimate of c o r r e l a t i o n s i n the u n i v e r s e of valu e s s c a l e d the same way. Where both X and Y are assumed t o be composed of simple (elements of equal v a r i a b i l i t y as i n the case of s t r a i g h t l i n e r e l a t i o n s , a l l of which are present i n Y but 2 some of which are l a c k i n g i n X, then r measures the 58 p r o p o r t i o n of the v a r i a b i l i t y of a l l the elements i n Y which are a l s o present i n X. For t h a t reason i n cases when the dependent v a r i a b l e i s known to be p a r t l y r e l a t e d to the 2 independent v a r i a b l e r i s c a l l e d the c o e f f i c i e n t of determ-i n a t i o n and i t i s the measure of the percentage t o which the va r i a n c e i n Y i s determined by the v a r i a n c e i n X. While other parameters, means, standard d e v i a t i o n s , standard e r r o r , standard e r r o r of estimate are c a l c u l a t e d i n the same k i n d of u n i t s as the o r i g i n a l data, the coef-f i c i e n t of d e t e r m i n a t i o n ( r ), since i t i s a r a t i o , i s p u r e l y an a r b i t r a r y mathematical measure. The c o e f f i c i e n t of r e g r e s s i o n measures the slope of the r e g r e s s i o n l i n e . T h i s means t h a t i t shows the average number of u n i t i n c r e a s e or decrease i n the dependent v a r i a b l e which occur w i t h i n c r e a s e of a s p e c i f i c u n i t i n the independent v a r i a b l e . T h e r e f o r e , i t s s i z e depends not only on the r e l a t i o n between the v a r i a b l e s , but a l s o on the u n i t s i n which they are s t a t e d (the dependent v a r i a b l e , the s i t e index i n feet,, the independent ones i n a r b i t r a r y u n i t s , each of i t s own k i n d ) . In t h i s study, as w i l l be shown l a t e r , the d i f f e r e n c e s i n the he i g h t growth of t r e e s and the composition of the p l a n t community are due t o a number of b a s i c f a c t o r s . They are the combined r e s u l t s of 17 d e s c r i b e d v a r i a b l e s and pro b a b l y many others, both known and unknown, which could not be measured. 59 These are d e a l t w i t h i n terms of m u l t i p l e r e g r e s s i o n r e l a t i o n -s h i p s . T h i s p a r t of the work was approached i n t h i s manner because c o n d i t i o n s under which the t r e e s grew or the p l a n t community formed, were completely beyond any c o n t r o l , some changing i n time independent of the others, others remaining constant over a p e r i o d of time but changing from p l a c e to p l a c e , and a l l to a c e r t a i n degree interdependent. S y m b o l i c a l l y we can r e p r e s e n t t h i s r e l a t i o n by the equation Y = a + b-^ X-^ + Xi^K.^ + ....... tojyX]y[ where Y r e p r e s e n t s the dependent v a r i a b l e , X^, X 2 .... X^ r e p r e s e n t the independent v a r i a b l e s , b^, bg, .... b ^ are the constants dependent on the r e l a t i o n s h i p s and measured i n the u n i t s of the o r i g i n a l s c a l e . G r a p h i c a l l y t h i s equation can be r e p r e s e n t e d by a s e r i e s of simple l i n e a r r e g r e s s i o n r e l a t i o n s , s i m i l a r t o F i g u r e s 24 t o 31, r e p r e s e n t e d by a simple s t r a i g h t l i n e of the best f i t . The b constants are the net r e g r e s s i o n c o e f f i c i e n t s because they show the r e l a t i o n of the s i n g l e independent v a r i a b l e e x c l u d i n g the a s s o c i a t e d i n f l u e n c e s of a l l the other independent v a r i a b l e s . But they a s c r i b e t o the independent v a r i a b l e not only the v a r i a t i o n i n the dependent v a r i a b l e which i s d i r e c t l y due to each of them but a l s o the v a r i a t i o n which i s due to such other independent v a r i a b l e s c o r r e l a t e d w i t h them which have not' 6 0 been s e p a r a t e l y c o n s i d e r e d i n the study. For example, i f there i s any p a r t of g e n e t i c a l v a r i a t i o n which was not considered, a s s o c i a t e d e i t h e r w i t h p l a n t community or topo-graphy, the r e g r e s s i o n c o e f f i c i e n t w i l l be l a r g e r because " i t w i l l i n c l u d e t h a t p a r t of g e n e t i c a l v a r i a t i o n which i s a s s o c i a t e d w i t h i t . I f we examine the data presented on the f o l l o w i n g pages we f i n d t h a t the h e i g h t growth of t r e e s i s f a i r l y c l o s e l y r e l a t e d to X^ v a r i a t i o n ( p l a n t community) but t h a t i t has no d e f i n i t e r e l a t i o n t o Xg (microtopography). The r e g r e s s i o n c o e f f i c i e n t b™. shows the average change of Y YX 1 w i t h u n i t changes i n X^, the r e g r e s s i o n c o e f f i c i e n t b^.^ shows the average change of Y w i t h u n i t changes of Xg and so on. I f we now c o n s i d e r i n our example the e f f e c t of X^ and Xg ( l o c a l p o s i t i o n on slope) on the v a r i a b i l i t y of Y, we w i l l f i n d a d i f f e r e n t s i t u a t i o n . S e p a r a t e l y each of them has a v e r y l a r g e r e g r e s s i o n c o e f f i c i e n t but combined t h i s e f f e c t i s o n l y s l i g h t l y l a r g e r than of the v a r i a b l e X^ alone because they are s i g n i f i c a n t l y h i g h l y c o r r e l a t e d and the v a r i a b i l i t y of Xg i s a c t u a l l y to a g r e a t extent i n -cluded i n the v a r i a b i l i t y i n X^. T h e r e f o r e , knowing the net r e g r e s s i o n of Y on X^ and Xg we can c o r r e c t the Y values t o e l i m i n a t e t h a t p a r t of t h e i r v a r i a t i o n which i s due to Xg and then r e l a t e the remaining f l u c t u a t i o n to X^. We can do t h a t by s u b t r a c t i n g the b-,Xn v a l u e s from Y. 6 1 Because p r o d u c t i v i t y changes i n d i f f e r e n t p l a n t communities, on d i f f e r e n t topography and d i f f e r e n t s o i l s , i t i s i n s u f f i c i e n t t o use a s i n g l e f a c t o r approach. T h i s i s because there i s a very h i g h i n t e r r e l a t i o n between the p l a n t community, the s o i l and the topography, as l o g i c a l l y can be expected. Therefore the d i f f e r e n c e i n he i g h t growth which appears to be d i r e c t l y a s s o c i a t e d w i t h d i f f e r e n c e s i n s o i l or p l a n t community, may r e f l e c t i n p a r t the d i f f e r e n c e s due to topography. In a d d i t i o n , the d i f f e r e n c e s i n he i g h t growth due to topography w i l l r e f l e c t i n p a r t the d i f f e r e n c e s which are a c t u a l l y due to p r o p e r t i e s of s o i l s . The qu e s t i o n then remains: how much of the p r o d u c t i v i t y of f o r e s t s i t e s can be e x p l a i n e d by the topography, how much by the proper-t i e s of s o i l s , how much by the p l a n t communities, how much by each v a r i a b l e s e p a r a t e l y ? Because a l l these v a r i a b l e s are h i g h l y c o r r e l a t e d i n d i c a t e s t h a t t h e i r e f f e c t s are mixed. F i t t i n g a s t r a i g h t l i n e to the data of each v a r i a b l e , and s o l v i n g each equation f o r constants a and b, and s o l v i n g the set of equations f o r a l l the v a r i a b l e s , i l l u s t r a t e s the extent t o which one independent v a r i a b l e may r e a l l y i n f l u e n c e the dependent v a r i a b l e , though I t s I n f l u e n c e may be concealed by the presence of other v a r i a b l e s . For t h i s reason a l s o , because two v a r i a b l e s show no c o r r e l a t i o n does not mean w i t h a b s o l u t e c e r t a i n t y t h a t they are not a s s o c i a t e d w i t h each o t h e r . The l a c k of c o r r e l a t i o n i n s t r a i g h t l i n e r e l a t i o n s h i p s can be concealed by compensating i n f l u e n c e s of one or more 6 2 other v a r i a b l e s . The procedure of working out a set of seventeen equations f o r seventeen unknown constants without the help of an e l e c t r o n i c computer would be almost i m p o s s i b l e . An e l e c t r o n i c computer can perform a l l the c a l c u l a t i o n s and s o l v e equations f o r any number of v a r i a b l e s w i t h i n the scope of i t s memory i f a s u i t a b l e set of i n s t r u c t i o n s e x i s t s . In t h i s study, assuming l i n e a r r e l a t i o n s , mathematically deter-mined equations f o r seventeen unknowns give an estimate of p r o d u c t i v i t y i n such a way that the standard d e v i a t i o n of r e s i d u a l v a r i a t i o n i s the s m a l l e s t t h a t can be obtained. The r e l a t i v e importance of a l l v a r i a b l e s considered, when combined, may be measured by d i v i d i n g the standard d e v i a t i o n of the estimated values squared by that of the o r i g i n a l v a l u e s . T h i s r a t i o , the c o e f f i c i e n t of m u l t i p l e cor-r e l a t i o n measures the combined importance of s e v e r a l independent f a c t o r s as a means of e x p l a i n i n g the d i f f e r e n c e s i n the dependent v a r i a b l e . I f the r e s i d u a l v a r i a t i o n i n each case i s compared w i t h the o r i g i n a l v a r i a t i o n i t i s e v i d e n t t h a t the c o r r e l a t i o n i n c r e a s e s as the standard e r r o r decreases. As s t a t e d above, the p a r t i a l c o r r e l a t i o n c o e f f i c i e n t s measure the c o r r e l a t i o n between the dependent f a c t o r and each of the s e v e r a l independent f a c t o r s e l i m i n a t i n g any l i n e a r tendency of the remaining independent f a c t o r s to obscure the r e l a t i o n s . Thus, i n the p r e s e n t study, where 63 the p r o d u c t i v i t y of f o r e s t s i t e s measured by s i t e index was c o r r e l a t e d w i t h a number of independent v a r i a b l e s , the p a r t i a l c o r r e l a t i o n of s i t e index with, f o r example, shape of contours, while h o l d i n g constant a l l the other v a r i a b l e s , I n d i c a t e s what the average c o r r e l a t i o n would p r o b a b l y be between s i t e index and shape of contours i n p l a c e s where a l l the p l o t s i n the sample would have the same slope, e l e v a t i o n , aspect, p o s i t i o n on slope and a l l the other v a r i a b l e s . A s i m i l a r i n t e r p r e t a t i o n was made f o r a l l p o s s i b l e combinations of the v a r i a b l e s . Even when the number of o b s e r v a t i o n s was i n s u f f i c i e n t t o permit such subgroups being formed, the par-t i a l c o r r e l a t i o n c o e f f i c i e n t I n d i c a t e d the probable average c o r r e l a t i o n In these subgroups, i f computed from a l a r g e r sample from the same u n i v e r s e . From the examination of the raw data i t may appear t h a t there i s no c o r r e l a t i o n between c e r t a i n v a r i a b l e s , because such a p o s i t i v e r e l a t i o n may be hidden by another negative f a c t o r a s s o c i a t e d w i t h i t . Or i n the opposite case, the c o r r e l a t i o n between c e r t a i n v a r i a b l e s may appear high, because both of them are c o r r e l a t e d w i t h another h i g h l y c o r r e l a t e d v a r i a b l e . From c o u n t l e s s examples i n t h i s study e.g. In V a c c i n i u m - S a l a l community w i t h decreased s t o n i -ness the s i t e index decreases very s i g n i f i c a n t l y . But the decrease of s t o n i n e s s i s a s s o c i a t e d w i t h outcrop s o i l s which c o n s i s t of shallow organic d e p o s i t s . Therefore, the decrease 64 of t r e e height i s o b v i o u s l y not the r e s u l t of decrease of s t o n i n e s s , but the r e s u l t of shallow s o i l p r o f i l e s , which dry out d u r i n g the summer. Th i s simple example, which does not need mathematical a n a l y s i s t o be n o t i c e d , i n d i c a t e s t h a t to d i s c a r d a l l f a c t o r s which by themselves do not have a s i g n i -f i c a n t c o r r e l a t i o n , and t o use i n d i v i d u a l l y o n l y those which have the h i g h e s t simple c o r r e l a t i o n , w o u l d be m i s l e a d i n g . I t c o u l d r e s u l t i n d i s c a r d i n g as i n s i g n i f i c a n t the t r u l y important f a c t o r s , and t h e i r e f f e c t would be wrongly a s s o c i a t e d w i t h other f a c t o r s . L o g i c a l examination of v a r i a b l e s , or a s p l i t t i n g of l a r g e groups of data i n t o sev-e r a l groups, i n t h i s study a s s o c i a t i o n s , a n a l y z i n g each p l a n t community s e p a r a t e l y and then a l l communities together, should p r o v i d e more t r u s t w o r t h y r e s u l t s . The t e s t whether a given independent v a r i a b l e may r e a l l y be r e l a t e d to the dependent v a r i a b l e , even i f i t shows no apparent c o r r e l a t i o n i s whether t h a t independent v a r i a b l e i s c o r r e l a t e d w i t h other independent v a r i a b l e s which i n t u r n are c o r r e l a t e d w i t h the dependent one. That p a r t i a l c o r r e l a t i o n c o e f f i c i e n t s are sub j e c t t o f l u c t u a t i o n due to sampling j u s t as a l l other parameters, should ,be s t r e s s e d . The lower the m u l t i p l e c o r r e l a t i o n and the sm a l l e r the sample, the l a r g e r would be the v a r i a t i o n of s u c c e s s i v e samples. For the reasons e x p l a i n e d , we cannot be a b s o l u t e l y c e r t a i n of the tr u e c o r r e l a t i o n s e x i s t i n g i n the u n i v e r s e 65 on the b a s i s of the c o r r e l a t i o n s shown i n our sample, but we can estimate the minimum value w i t h a given chance of being wrong, f o r example, t h a t our statement w i l l be wrong i n one out of twenty o b s e r v a t i o n s on samples taken from the same u n i v e r s e . In a sample of ten measurements there i s s t i l l a p r o b a b i l i t y of one out of twenty t h a t we s h a l l get a c o r r e l a t i o n c o e f f i c i e n t as h i g h as .60 from t h e ' u n i v e r s e where the t r u e c o r r e l a t i o n i s zero, and from the u n i v e r s e where the t r u e c o r r e l a t i o n i s .50 as h i g h as .81. The r e l i a b i l i t y of c o r r e l a t i o n c o e f f i c i e n t s v a r i e s not on l y w i t h the degree of c o r r e l a t i o n and the s i z e of the sample, but a l s o w i t h the number of independent v a r i a b l e s . The g r e a t e r the number of independent v a r i a b l e s used and the s m a l l e r the number of cases i n each sample, the g r e a t e r are the chances t h a t our o b s e r v a t i o n s w i l l be - o u t s i d e the f i v e per cent l i m i t . But, i f only a few independent v a r i a b l e s are chosen i n the m u l t i p l e c o r r e l a t i o n study, there i s a much l a r g e r p o s s i b i l i t y of the c o r r e l a t i o n c o e f f i c i e n t s b e i n g e r r o n e o u s l y h i g h . T h i s would happen i f a l a r g e number of independent v a r i a b l e s were c o n s i d e r e d and only those were r e t a i n e d which showed the h i g h e s t c o r r e l a t i o n w i t h the dependent v a r i a b l e . Therefore, v a r i a b l e s should be grouped more on a l o g i c a l b a s i s than on a p r o p o r t i o n a l s i g n i f i c a n c e of t h e i r r e g r e s s i o n c o e f f i c i e n t . In t h i s study the independent v a r i a b l e s were a l l r e t a i n e d i n the f i r s t p a r t , and then grouped i n t o 66 physic-graphical f a c t o r s and s o i l f a c t o r s , while the p l a n t community remained as an i n d i v i d u a l v a r i a b l e i n both c a l -c u l a t i o n s . While i t i s r e a l i z e d t h a t the mathematical a n a l y s i s Is of a s s i s t a n c e and p r o v i d e s us w i t h r e l i a b l e g e n e r a l inform-a t i o n about the data at hand, i t must be remembered t h a t t h i s procedure can p r o v i d e wrong i n f o r m a t i o n about any i n d i v i d u a l case. I t may happen t h a t the s i t e index of a p a r t i c u l a r p l a c e may be b e t t e r or worse than the a n a l y s i s of the s i t e f a c t o r s i n d i c a t e s . For example, measurable v a r i a b l e s may i n d i c a t e a good s i t e q u a l i t y while one f a c t o r which may not even have been d e t e c t e d determines poor growth. Therefore, f o r any e s t i m a t i o n of the p r o d u c t i v i t y , l o c a l knowledge and good judgment are e s s e n t i a l . E x t r a p o l a t i o n s o u t s i d e the r e g i o n where data were c o l l e c t e d can be done only when a l l t h e i r l i m i t a t i o n s are r e a l i z e d and checked. G e n e r a l l y i t can be s a i d though, t h a t s i t e q u a l i t y i s f a i r l y uniform, w i t h i n a c e r t a i n combination of topographic and c l i m a t i c f a c t o r s , because these f a c t o r s determine the v a r i a t i o n of the l o c a l environment. The same Is a l s o t r u e f o r the p l a n t community i f i t i s c o n s i d e r e d as an i n d i c a t o r of the p r o d u c t i v i t y . For adequate i n t e r p r e t a t i o n of v e g e t a t i o n i n any r e g i o n , i t i s necessary t o o b t a i n a broad p e r s p e c t i v e based upon a n a l y s i s of the l o c a l h a b i t a t f a c t o r s . 67 Ecosystem s t r a t i f i c a t i o n was used i n the f o l l o w i n g a n a l y s i s and p l o t s were p l a c e d i n t o a s s o c i a t i o n s on the b a s i s of g r e a t e s t s i m i l a r i t i e s i n both t h e i r f l o r i s t i c s t r u c t u r e ( i n c l u s i v e t r e e s ) and ecotope ( K r a j i n a , 1959). References: Bajzak, I960; B a r n e t t , 1937; Coons, 1957; C o r n i s h , 19^0; E z e k i e l and Pox, 1959; K e n d a l l , 19^9; Moroney, 195^; Nedler, 195^; Smith, 1957, W i l k i n s o n , 1957; Yates, 1933. The Climate To prevent unwise use of the pre s e n t e d graphs and t a b l e s , c e r t a i n c h a r a c t e r i s t i c s of mountain c l i m a t e s i n regard to both temperature and p r e c i p i t a t i o n should be noted. A l l the graphs and t a b l e s presented c e r t a i n pos-s i b l e e r r o r s i n a s t a t i s t i c a l sense, because o n l y one p l o t i n each a s s o c i a t i o n was s t u d i e d and number of instruments was not gr e a t , t h e r e f o r e t h e i r l o c a t i o n may have i n f l u e n c e d the r e a d i n g s . The data r e p r e s e n t o n l y f i f t y - t h r e e weeks of measurements from June 29th, 1959 t o J u l y 3rd, i 9 6 0 . Temperature That temperature decreases w i t h i n c r e a s i n g a l t i -tude i s a g e n e r a l l y accepted phenomenon. The accepted value of the average l a p s e r a t e on mountains of the temperate zone i s u s u a l l y taken as 3.3° P. per 1,000 f e e t r i s e , though of course there i s c o n s i d e r a b l e v a r i a t i o n w i t h season and between d i f f e r e n t r e g i o n s . In the mountains of the Western 68 U n i t e d S t a t e s (Baker, 1944) the r a t e averages 3-5° E. per 1,000 f e e t i n J u l y and 2.9° F. i n January. But temperature g r a d i e n t s f r e q u e n t l y depart from t h i s average and temper-ature i n v e r s i o n s are common. Sometimes the i n v e r s i o n s are v e r y l o c a l and occur o n l y d u r i n g a few b r i g h t summer n i g h t s but sometimes they are frequent and i n v o l v e c o n s i d e r a b l e a r e a s . When the a i r , due to r a d i a t i o n from ground s u r f a c e s , i s c o oled d u r i n g the ni g h t i t s d e n s i t y i n c r e a s e s and i n calm weather there i s a creep of c o l d a i r down the slop e s t o c o l -l e c t i n en c l o s e d d e p r e s s i o n s . The c l e a r e r the sky, the more r a p i d the c o o l i n g of the ground; the calmer the atmosphere, the s t e a d i e r the descent of co o l e d a i r . E f f e c t of these " c o l d l a k e s " i s most prominent i n wi n t e r f o r i n summer the v a l l e y bottoms may be so much heated d u r i n g the day t h a t they r e t a i n the warm a i r f a r i n t o the short n i g h t . In l a t e f a l l , w i n t e r and e a r l y s p r i n g i t i s not unusual t o f i n d the depr e s s i o n s f i l l e d w i t h c o l d f o g while the slopes are b r i g h t w i t h the sun s h i n i n g from c l e a r blue sky. I t i s ev i d e n t that there i s no constant r e l a t i o n s h i p between temperature and a l t i t u d e . The u s u a l l y accepted average of 3.3° F. drop of temperature f o r 1,000 f e e t of e l e v a t i o n i s merely a mean value which seldom occurs. The summits are u s u a l l y c o l d e r than v a l l e y s , but d u r i n g b r i g h t weather the v a l l e y s are abnormally warm and d u r i n g s t i l l n i g h t s abnormally c o l d . Therefore a i r temperature g r a d i e n t 69 i s steeper'by day than by n i g h t , i n summer than i n w i n t e r . Thickness of the atmosphere above the p l a c e of o b s e r v a t i o n decrease w i t h i n c r e a s i n g a l t i t u d e . But f a r more r a p i d than the decrease i n t h i c k n e s s of the atmosphere i s the decrease i n l i q u i d and s o l i d i m p u r i t i e s . In consequence, d u r i n g the day the incoming s o l a r r a d i a t i o n i n c r e a s e s , as the l o s s e s due t o i n t e r c e p t i o n of the atmosphere decrease. I t i s espec-i a l l y the u l t r a v i o l e t end of the spectrum t h a t i s i n t e r c e p t e d by the denser atmosphere, smoke, dust and moisture being the c h i e f o b s t a c l e s . The sun rays pass through the c l e a r a i r without much h e a t i n g e f f e c t t h e r e f o r e the a i r temperature may be r e l a t i v e l y low, while s o l i d o b j e c t s on which they f a l l may be g r e a t l y heated. During the n i g h t the outgoing r a d i a t i o n of the heat h e l d i n the ground i n c r e a s e s as the counter-r a d i a t i o n of the a i r masses decreases w i t h a l t i t u d e . The m i c r o c l i m a t e of h i g h l e v e l s i s consequently not only more extreme i n i t s h i g h e r heat r e c e p t i o n by day but a l s o i n i t s g r e a t e r heat l o s s by n i g h t . The c o o l i n g as w e l l as the h e a t i n g of the atmosphere s t a r t s e s s e n t i a l l y from the ground, which a c t s as a condensor, s t o r i n g and r e l e a s i n g the r a d i a t i o n energy of the sun. Temperature regime of a s t a t i o n i s the r e s u l t of i t s r a d i a t i o n b alance. The c l i m a t e of the f o r e s t can be understood o n l y by f o c u s i n g a t t e n t i o n on the crown s u r f a c e , where the m e t e o r o l o g i c a l p r o c e s s e s occur. R a d i a t i o n of the sun and sky-i s i n t e r c e p t e d by the crowns of t r e e s , consequently only a l i m i t e d amount of d i r e c t r a d i a t i o n reaches the f o r e s t f l o o r . Trapp (1938) measured by means of p h o t o c e l l s t h a t about 80 percent of the i n c i d e n t r a d i a t i o n was caught i n the crown space on sunny days. Other workers have found t h a t f o r a d e f i n i t e p l a c e on the f o r e s t f l o o r the r e l a t i v e amount of the r a d i a t i o n r e c e i v e d Is f a i r l y independent of the p r e v a i l i n g weather. What f r a c t i o n of the o u t s i d e l i g h t p e n e t r a t e s to the f o r e s t f l o o r depends to a g r e a t extent on the k i n d of woods, the age of the stand and i t s d e n s i t y , and the height of t r e e s i n the crown canopy. As a r e s u l t of d i f f e r e n c e i n a b s o r p t i o n of the l e a v e s t o v a r i o u s wave l e n g t h bands the crown space a c t s not only to weaken, but a l s o to f i l t e r the r a d i a t i o n . Orange and r e d wave l e n g t h are absorbed more than green, blue and v i o l e t . Comparative o b s e r v a t i o n s (Geiger, 1957) showed t h a t the i l l u m i n a t i o n a f f o r d s an important h a b i t a t f a c t o r f o r the ground v e g e t a t i o n . With i l l u m i n a t i o n below 16 per cent (European l a t i t u d e s 40-50 degrees) the f o r e s t f l o o r remains bare. Between 16-22 degrees mosses appear, above 22, blue-b e r r i e s are found, and at about 30 per cent, the f i r s t regen-e r a t i o n of spruce. There are a l s o d i f f e r e n c e s between areas w i t h i n the same stand. Trapp (1938) has determined and mapped the d i s t r i b u t i o n of i l l u m i n a t i o n throughout a stand by means of thousands of separate measurements. He s t a t e d t h a t : " S p e c i a l s i g n i f i c a n c e i s atta c h e d t o these maps In th a t they c o i n c i d e c l o s e l y w i t h v e g e t a t i o n maps." That h i g h c o r r e l a t i o n s e x i s t between the p l a n t community and the d e n s i t y of the stand, e s p e c i a l l y i f we c o n s i d e r the p l a n t community at the l e v e l of s u b a s s o c i a t i o n or v a r i a t i o n , i s obvious, because l i g h t Is one of the main f a c t o r s i n i t s development. At the l e v e l of a s s o c i a t i o n , topography and water c o n d i t i o n s are i n f l u e n c i n g the d e n s i t y of the t r e e cover as w e l l as the development of the v e g e t a t i o n . The r a d i a t i o n r e l a t i o n s h i p s determine the temperature r e l a t i o n s h i p s . In the f o r e s t , the crown l a y e r forms the "outer a c t i v e s u r f a c e " (Geiger., 1957) on which the t o t a l temperature regime i s dependent. The outgoing r a d i a t i o n d u r i n g the n i g h t proceeds f i r s t e x c l u s i v e l y from t h i s outer s u r f a c e , t h e r e f o r e n o c t u r n a l c o o l i n g i n a f o r e s t stand i s a f u n c t i o n of i t s composition and d e n s i t y . Below the crown l a y e r almost u n i f o r m temperatures p r e v a i l at a l l l e v e l s throughout the n i g h t . Not u n t i l the sun i s f a i r l y h i g h i n the sky does the- crown space begin t o warm up, wh i l e the f o r e s t f l o o r s t i l l remains c o o l . Two hours or more a f t e r s u n r i s e the temperature of the f o r e s t f l o o r begins t o i n c r e a s e . The st r o n g h e a t i n g of the crown canopy produces a vigo r o u s t u r b u l e n c e i n the t r e e t o p s . About midday the h i g h e s t temperature and the most u n s e t t l e d temperature c o n d i t i o n s 72 are i n the crown space. Below, the temperature as w e l l as the d i s q u i e t d e creases. The lowest l a y e r s of the stand atmosphere show amazing u n i f o r m i t y of temperature. During e a r l y a f t e r n o o n hours there i s a p e r i o d of s t a b l e condi-t i o n s when i n p u t and output are p r a c t i c a l l y equal and the af t e r n o o n f a l l has not y e t begun. C o o l i n g i n the a f t e r n o o n hours i s more uniform, because the c o l d a i r i s c o n s t a n t l y s i n k i n g down from the crown layer--. The morning h e a t i n g has to overcome the s t a b i l i t y of the n o c t u r n a l temperature s t r a t i f i c a t i o n . By n i g h t time temperature d i f f e r e n c e s are not g r e a t . I f the crown canopy i s u n i f o r m l y and s u f f i c i e n t l y dense, the c o o l a i r may remain above i t . But these d i f f e r -ences cannot amount to more than a few tenths of a degree. I f the canopy i s not u n i f o r m l y dense and the c o o l i n g s u f f i c i e n t l y deep, the c o o l a i r s i n k s through the canopy w i t h the r e s u l t t h a t the lowest temperatures are on the f o r e s t f l o o r . Prom the graphs ( F i g u r e s 5 and 6, Appendices 5 and 6) i t may be seen t h a t low summer maxima and f a i r l y h i g h w i n t e r minima were ge n e r a l and t h a t even on the c o n t r o l p l o t the d i f f e r e n c e s between weekly maxima and minima were l e s s than 50° F. T h i s i s t y p i c a l f o r the maritime c l i m a t e which p r e v a i l e d most of the time, when the modifying i n f l u e n c e of the sea was c a r r i e d by the onshore winds onto the mainland p r o d u c i n g a m i l d c l i m a t e . However, the i n f l u e n c e of c o n t i n e n t a l i c follow page 7 2 . 73 c l i m a t e cannot "be e n t i r e l y n e g l e c t e d . The h i g h e s t temper-atures were rec o r d e d from J u l y 6th t o August 3rd when e a s t e r l y winds p r e v a i l e d . S i m i l a r l y under the i n f l u e n c e o f ' e a s t e r l y winds i n the week of November 9th t o the 16th o c c u r r e d the f i r s t severe drop of the temperature ( c o n t r o l t o 14° P.). E a s t e r l y winds oc c u r r e d f o r p e r i o d s of s e v e r a l days from December 28th t o January 25th and from February 18th to February 29th, c o i n c i d i n g again w i t h the lowest temperatures. Spring, from March 25th t o May 9th, had v e r y changeable weather - c o n d i t i o n s . Heavy r a i n s from w e s t e r l y winds a l t e r -nated w i t h p e r i o d s of sunshine and c o l d n i g h t under the i n f l u e n c e of e a s t e r l i e s . E a s t e r l y winds a l s o were q u i t e frequent d u r i n g the month of June, c o i n c i d i n g w i t h c l e a r weather. Comparing hygrothermograph r e c o r d s ( F i g u r e 5, Appendix 5) on temperature i n the s h e l t e r i t i s noteworthy t h a t the d i f f e r e n c e of mean temperature between the two groups of p l o t s was approximately 2° F., which agreed c l o s e l y w i t h the accepted value of 3.3° P. decrease per 1000 f e e t of a l t i t u d e . Another i n t e r e s t i n g f a c t was t h a t the mean temper-a t u r e s between d i f f e r e n t communities of the same group and even on the c o n t r o l s t a t i o n o u t s i d e the f o r e s t seldom d i f f e r e d . The p l a n t communities of dry s i t e s on s e v e r a l occasions were found t o have a 1° F. hig h e r mean temperature than the r e s t of the p l o t s i n t h e i r group. 74 Maximum and minimum temperatures ( F i g u r e 6, Appendix 6) d i f f e r e d from s t a t i o n to s t a t i o n , being i n f l u e n c e d by topography, d e n s i t y of the t r e e cover and the shrub and ground v e g e t a t i o n . L o g i c a l l y the more p r o t e c t i o n the s t a t i o n s r e c e i v e d from these f a c t o r s , the l e s s severe were the extremes. That the g r e a t e s t d i f f e r e n c e between maxima and minima occurred d u r i n g c l e a r weather i s obvious. The u p p e r ' p l o t s had a s l i g h t l y wider range of weekly extremes than the lower p l o t s . On the c o n t r o l s t a t i o n i n summer, the c l o s e r to the ground the measurements were taken the g r e a t e r was the d i f f e r -ence between maxima and minima. With i n c r e a s e of the d e n s i t y of the stand, however, t h i s t r e n d was r e v e r s e d . Under a c l o s e d canopy the c l o s e r to the ground the narrower was the range. Summer minima i n a l l the a s s o c i a t i o n s of the same group were not f a r a p a r t and the d i f f e r e n c e s In the range were mainly due t o d i f f e r e n c e s i n maxima observed. Winter d i f f e r e n c e s i n both extremes were g e n e r a l l y not g r e a t . Winter minima i n S a l a l were about 2° F. h i g h e r than i n the other three s t a t i o n s . T h i s e f f e c t of c o l d a i r drainage was g r e a t e s t i n Vaccinium - L y s i c h i t u m (2-3° F.) and s l i g h t l y l e s s (1-2° F.) i n P o l y s t i c h u m and Moss. Data on temperature minima from the screen seemingly d i s a g r e e w i t h statements j u s t made. In P o l y s t i c h u m and Vaccinium - L y s i c h i t u m 75 a s s o c i a t i o n the screen was standing among the dense ground vegetation which d i d not permit the cool a i r to reach the instruments. The maximum-minimum thermometer three f e e t above the screen recorded on s e v e r a l occasions minima 5° P. lower than the thermometer w i t h i n the screen. (Compare Figures 5 and 6.), In higher a l t i t u d e p l o t s the e f f e c t of c o l d a i r drainage was not detected and Vaccinium - S a l a l s t a t i o n had u s u a l l y lower minima than the other p l o t s . An exception was the c o n t r o l s t a t i o n ; t h i s was due t o i t s l a c k of tree cover. The dotted l i n e on Figure 6 represents the temper-atures at the ground sur f a c e . I t shows on the c o n t r o l s t a t i o n very wide range of temperatures w i t h maxima reaching up to 127° F. and minima as low as 15° P. Under the canopy of t r e e s i n the d i f f e r e n t a s s o c i a t i o n s the temperature range was reduced depending on the d e n s i t y of the stand, topo-graphy and water regime of the s o i l s urface. F i r s t f r o s t i n the f a l l occurred on a l l the p l o t s at the same date, November 4th, during the e a r l y morning hours, at which time the temperature f e l l to approximately 30° F. on the upper p l o t s , and j u s t below 32° F. on lower p l o t s and a f t e r t h i s date at a height of s i x f e e t above the ground f r e e z i n g temperatures were recorded on a l l the p l o t s every week u n t i l March 21st. The l a s t f r e e z i n g temperature 76 recorded on the lower p l o t s was on A p r i l l6th and the upper p l o t s on A p r i l 22. The le n g t h of the f r o s t - f r e e p e r i o d was 195 days on upper p l o t s and 201 days on the lower p l o t s . The measurements i n the screen among the vegetation i n Polystichum and Vaccinium-Lysichitum a s s o c i a t i o n s were only 33°F. on A p r i l l6th. The f i r s t snow was recorded on November l6th, 9.5 inches on the upper p l o t s and 3.5 on the lower ones. A f t e r t h i s date snow f e l l q u i t e f r e q u e n t l y , but d i d not l a s t . Between January 8th and 11th, 32 inches of snow f e l l on the upper p l o t s and 20 inches on the lower p l o t s . This snow cover l a s t e d f o r e i g h t weeks and during t h i s p e r i o d most of the p r e c i p i t a t i o n recorded was i n the form of snow. However, the t o t a l snow depth was never higher than on January the 11th. Prom the middle of March u n t i l the l a s t s n o w f a l l , on A p r i l l8th, there was snow on the ground on se v e r a l occasions but I t always melted w i t h i n a day or two a f t e r i t f e l l . Last snow on the ground was recorded on A p r i l 25th covering l e s s than 10 per cent of Vaccinium - Moss and Blechnum p l o t . Within the two groups of p l o t s no n o t i c e a b l e d i f f e r e n c e i n sn o w f a l l or snow depth was detected. However, when the snow melted, i t disappeared e a r l i e r on sunny than on the shady s i t u a t i o n s . Vegetative p e r i o d may be defined as the p e r i o d between, i n s p r i n g the temperature at which most seeds germinate, and buds break dormancy and i n f a l l , the temperature at which growth ceases. I f a mean temperature of 43°P. and above i s taken 77 as standard then the upper p l o t s had a v e g e t a t i v e p e r i o d of twenty-four weeks and lower p l o t s p r o b a b l y twenty-seven or twenty-eight weeks. Growing season i s even more l o o s e l y d e f i n e d . I t i s the p e r i o d between the l a s t k i l l i n g f r o s t i n s p r i n g and the f i r s t k i l l i n g f r o s t i n autumn. But there i s l i t t l e agreement among e c o l o g i s t s on what i s a " k i l l i n g f r o s t . " Some w r i t e r s f o r convenience, c o n s i d e r i t t o be 3 2 ° F. and r e f e r t o i t as the f r o s t f r e e p e r i o d . Others c o n s i d e r 2 6 ° F. (Connor, 1 9 ^ 9 ) a k i l l i n g f r o s t which, of course, g i v e s a longer growing season. An estimate of the growing season from c h r o n o l o g i c a l events depends on what s p e c i e s of p l a n t s i t i s based and can v a r y w i d e l y . Some data were c o l l e c t e d which may serve as an approximation of the beginning of growth i n s p r i n g . Opening of the Vaccinium buds and the f i r s t L y s i c h i t u m l e a v e s t o r e a c h a h e i g h t of two inches were recorded on March 2 8 t h on the lower p l o t s . No d i f f e r e n c e s i n development of the v e g e t a t i o n was n o t i c e a b l e among a l l f o u r p l o t s of t h i s group. The v e g e t a t i o n on the upper p l o t s a t t a i n e d the same stage of development about s i x days l a t e r . On the l 8 t h of A p r i l 0 on the lower p l o t s and on the 2 5 t h on upper p l o t s the f i r s t opening of hemlock buds were re c o r d e d . On the 2 5 t h of A p r i l on the lower p l o t s the a c t i v i t y of the cambium of D o u g l a s - f i r s t a r t e d as evidenced by the ease at which the bark p e e l e d . 78 References: B l i s s , 1924; B r i g g s , Lyman and Shantz, 1917; Hoare, 1938; Karman, 1937; Powell, 1936; Richardson, 1931; Schmidt, 1935; Sutton, 1934, 1936, 1937. P r e c i p i t a t i o n Although r a i n f a l l increases w i t h a l t i t u d e i n the mountains, the r a t e of increase v a r i e s so much that no c a l c u l a t e d average value has any s i g n i f i c a n c e . U s u a l l y p r e c i p i t a t i o n continues to increase from the base to the c r e s t of the mountains. The c o r r e l a t i o n of p r e c i p i t a t i o n and e l e v a t i o n i s modified by three f a c t o r s : approach e f f e c t , r a i n shadow, and what may be c a l l e d a "canyon e f f e c t " . When a mountain range l i e s athwart the wind the a i r masses are forced upward. The c o o l i n g e f f e c t so produced r e s u l t s i n the increase of r a i n f a l l w i t h increased a l t i t u d e . This e f f e c t f i r s t becomes noted some distance t o the wind-ward of the mountains, e s p e c i a l l y i f they are steep and high. The heaviest p r e c i p i t a t i o n i n any one r a i n occurs i n the area where the clouds f i r s t begin t o deposit r a i n , since the temperature there i s highest and t h e r e f o r e f o r any given ascent and c o o l i n g the condensation i s greater than at higher l e v e l s where temperatures are lower. On the lee s i d e s , mountains have a r a i n shadow or zone where p r e c i p i t a t i o n i s reduced since the r a i n - b e a r i n g winds lose water i n t h e i r passage over the mountains. Within t h i s e n t i r e zone, r a i n f a l l u s u a l l y decreases w i t h distance from the mountain c r e s t and the a l t i t u d i n a l e f f e c t s are obscured. The windward edge of the r a i n shadow may c o i n c i d e To follow page 7 8 . 79 w i t h the c r e s t of the mountain or may be p a r t way down the lee side thus f u r t h e r obscuring the a l t i t u d i n a l r e l a t i o n s of the lee slopes. R a i n f a l l recorded i n the deep v a l l e y s may be f a r heavier than i s c h a r a c t e r i s t i c f o r the e l e v a t i o n . E x c l u d i n g approach e f f e c t , such r a i n f a l l i s s t r o n g l y i n f l u e n c e d by the major surrounding r i d g e s that have much higher a l t i t u d e f o r i t i s these that f o r c e the r a i n masses to r i s e . The d i s t r i b u t i o n p a t t e r n shown i n Figures 7 and 8 (Appendix 7) i n d i c a t e that there i s a decided increase i n p r e c i p i t a t i o n northward corresponding roughly w i t h the increase In a l t i t u d e . The increase i s probably not gradual, since i t i s i n f l u e n c e d by the l o c a l topography. Lower a l t i t u d e p l o t s above Goose Lake, which are open from the west, appear to have the same, or even s l i g h t l y higher, p r e c i p i t a t i o n than the s h e l t e r e d Loon Lake s t a t i o n . W ithin the two groups of p l o t s i t can be assumed that the t o t a l amount of p r e c i p i t a t i o n r e c e i v e d on each p l o t at the l e v e l above the canopy of t r e e s was the same. Thus we can say that while the upper p l o t s r e c e i v e d 166 inches, the p r e c i p i t a t i o n at Loon Lake was 106 inches, on the lower p l o t s 109, and on Marc's farm 83 inches. (The 109 inches f o r the lower p l o t s i s the cumulative p r e c i p i t a t i o n of one can standing f r e e i n S a l a l a s s o c i a t i o n , which w i t h the exception of strong winds r e c e i v e d unobstructed r a i n f a l l . ) 80 . Rain i n the f o r e s t f i r s t wets the crowns of t r e e s . I f the r a i n i s l i g h t and of short d u r a t i o n , most of i t may he r e t a i n e d by the canopy. As soon as the crown gets thoroughly wet the water i s passed on. Part of i t i s conducted by twigs and branches to the trunk and runs down to the ground. The remaining f a l l s d i r e c t l y to the ground. Therefore, the e r r o r of measurements can be q u i t e l a r g e , since no attempt was made t o assess the amount of water conducted along the trunk. The p o r t i o n which drops through the crowns i s unevenly d i s t r i b u t e d w i t h i n the f o r e s t depending on the d e n s i t y of the canopy and the angle of the branches. I f we assume th a t w i t h i n both groups of p l o t s the amount of p r e c i p i t a t i o n which f e l l onto the canopy of the t r e e s i s the same then the d i f f e r e n c e s i n p r e c i p i t a t i o n are ob v i o u s l y due to the d i f f e r e n t d e n s i t y and p r o p o r t i o n of d i f f e r e n t tree species i n the canopy. The d i f f e r e n c e s i n r a i n f a l l presented on Figures 7 and 8 by t h e i r weekly and cumulative value i n per cents amount t o : Upper p l o t s Lower p l o t s C o n t r o l 100 per cent C o n t r o l can 100 per cent Vaccinium S a l a l 98.0 per cent S a l a l 93-5 per cent Vaccinium Moss 90.0 per cent Moss 87.5 per cent Blechnum 90.5 per cent Polystichum 90.0 per cent Vaccinium L y s i c h i t u m 98.0 per cent As may be expected, the l i g h t e r the r a i n and the higher the temperature, the greater were the p r o p o r t i o n a l l o s s e s of water i n the canopy. In winter there i s almost no l o s s of water due t o r e t e n t i o n . Losses which occur during that 81 time are the r e t e n t i o n of snow. These l o s s e s however are only temporary, since at the low-winter temperatures eva-p o r a t i o n i s low and the snow f i n a l l y f a l l s t o the ground. I t was c a l c u l a t e d that from .24 inches of r a i n f a l l on J u l y 27th i n Moss a s s o c i a t i o n 63 per cent, i n Polystichum 50 per cent, i n S a l a l 20 per cent, and i n L y s i c h i t u m 4 per cent was r e t a i n e d by the crowns. The same r a i n i n the upper group of p l o t s amounted to .49 inches. In Vaccinium -Moss 21 per cent, i n Vaccinium - S a l a l 11 and Blechnum 16 per cent were l o s t . In December l o s s e s during the r a i n of 2.11 inches amounted t o : i n Moss 5 per cent, i n Polystichum 3.5, S a l a l 2 and Vaccinium - L y s i c h i t u m 1.5 per cent. Rains of v a r y i n g i n t e n s i t y and d u r a t i o n occurred during the p e r i o d of t h i s study. These v a r i e d from d r i z z l e when the clouds were forming low, to heavy downpours, thunderstorms and h a i l s t o r m s on summer afternoons and snow during the w i n t e r . Even i f the r a i n was not f a l l i n g , l a r g e amounts of water were often deposited on the vegetation from low clouds and through condensation. Although no data on fog were c o l l e c t e d i n t h i s study i t was noted on s e v e r a l occasions that while there was only a dense fog or low clouds outside the f o r e s t , heavy drops of water were f a l l i n g t o the ground from the canopy and t r a c e s of water were noted i n the raingauges. In the w r i t e r ' s o p i n i o n , although t h i s " o c c u l t " p r e c i p i t a t i o n may not often reach the ground i n 82 measurable q u a n t i t i e s , i t may account f o r s e v e r a l inches of r a i n f a l l at the canopy l e v e l . Figures 7 and 8 are condensed to present a general p i c t u r e of a l l the p l a n t communities on one page so that d i f f e r e n c e s can be seen r e a d i l y . D e t a i l s of weekly measurements are given i n t a b l e form i n Appendix 7. I n t e r p r e t a t i o n of weekly p r e c i p i t a t i o n from these must be done w i t h care. Since, i f i t r a i n e d during the day when data were c o l l e c t e d , the lower p l o t s have a p r o p o r t i o n a l l y higher reading f o r the preceding week and lower f o r the f o l l o w i n g as compared w i t h the upper p l o t s . The d i f f e r e n c e i s the amount of r a i n which f e l l during the time the ,data were c o l l e c t e d (about eight hours). As t y p i c a l f o r t h i s r e g i o n , the greater p o r t i o n of the p r e c i p i t a t i o n f e l l i n w i n t e r . On the upper p l o t s , during the three months from November l 6 t h to February 15th the t o t a l p r e c i p i t a t i o n was 60.5 Inches. In the same time the lower p l o t s r e c e i v e d 43.0 inches. During a three month p e r i o d from May 31st to August 31st, t o t a l p r e c i p i t a t i o n on the upper p l o t s amounted to only 16.0 inches and on the lower p l o t s t o 9.5 inches. A p e r i o d from J u l y 6th t o August 5th was almost r a i n l e s s . The p r e c i p i t a t i o n of .49 inches on upper p l o t s and .24 inches on lower p l o t s was a l l recorded during t h i s period.. 83 The graphs show that the m a j o r i t y of the r a i n s occur over a lar g e area, and increase w i t h a l t i t u d e . Summer r a i n s , however, are of more l o c a l occurrence and even lower a l t i -tudes o c c a s i o n a l l y may r e c e i v e more r a i n than higher a l t i -tudes only a few miles d i s t a n t . References: Bennett, 1934; Brunt, 1939; Hartman, 1952; Humpreys, 1940; K i t t r e d g e , 19^8; Kroch, 19^0; Sutton, 1939; Wexler, 1936; Yamamoto, 1937. R e l a t i v e Humidity R e l a t i v e humidity i s governed p r i n c i p a l l y by the temperature, wind and t r a n s p i r a t i o n of the vegetation and d i r e c t evaporation from the ground. The r e s t r i c t e d a i r movement i n the trunk space r e t a i n s the water vapor so that high humidity i s the most c h a r a c t e r i s t i c feature of the f o r e s t m i c r o c l i m a t e . Before sunrise humidity i s high i n a l l l a y e r s and when dew i s p r e c i p i t a t e d , complete s a t u r a t i o n r e s u l t s . Part of the dew i s deposited i n the crown l a y e r , decreasing downward i n t o the stand. As the sun gets higher, the wind i n c r e a s e s , mixing the outside and the f o r e s t a i r . While the f o r e s t f l o o r p l a y s only a small p a r t i n respect to temper-ature i t i s very important f o r the t r a n s f e r of the water vapor. Temperature maximum of the f o r e s t f l o o r was always low, the humidity maximum i s w e l l developed e s p e c i a l l y when the f o r e s t f l o o r has a p l a n t cover. i g . 9- E x a m p l e of S u m m e r H y g r o t h e r m o g r a p h R e c o r d s To f o l l o w p a g e 8 3 . i g . 1 0 . E x a m p l e of F a l l Hy g r o t h e r mo g r a p h R e c o r d s irteanoiaaf To f o l l o w p a g e 8 3 F i g . 11. E x a m p l e of W i n t e r H y g r o t h e r m o g r a p h R e c o r d 84 The d a i l y minimum of r e l a t i v e humidity c o i n c i d e s w i t h the temperature maximum, which occurs at about 2:00 p.m. I t appears from the data that the a c t u a l amount of water vapor i n the a i r during calm weather, below the f o r e s t canopy changes only vary s l i g h t l y . I t reaches a p o i n t of complete or almost complete s a t u r a t i o n s e v e r a l times a week. R e l a t i v e h u m i d i t i e s below t h i s p o i n t , where the measurements are not c o l l e c t e d among a dense ground vege t a t i o n , are a f u n c t i o n of the temperature e x i s t i n g at that time, more than of any other i n f l u e n c e . Close to the saturated s o i l the r e l a t i v e h u m i d i t i e s are always high. This i s e s p e c i a l l y so among the dense i n t e n s i v e l y t r a n s p i r i n g ground v e g e t a t i o n , which a l s o gives p r o t e c t i o n from the mixing of d i f f e r e n t l a y e r s of the a i r . To i l l u s t r a t e t h i s statement three weekly records were s e l e c t e d and shown on Figures 9, 10, and 1 1 . Reference to these f i g u r e s shows the coincidence of tempera-ture maxima w i t h r e l a t i v e humidity minima. I t i s i n t e r e s t i n g to compare i n d i v i d u a l a s s o c i a t i o n s . As the heating on the c o n t r o l s t a t i o n reached 90° F. i n Figure 9 the r e l a t i v e h u m i d i t i e s f e l l to about 33 percent. During c l e a r n i g h t s , as temperatures dropped close to 50° F. the r e l a t i v e humidity increased to approximately 90 per cent. Under the canopy of t r e e s d i f f e r e n c e s i n temperature were l e s s , e s p e c i a l l y the c o o l i n g during the night and t h e r e f o r e the h u m i d i t i e s increased only s l i g h t l y . Therefore 85 mean r e l a t i v e h u m i d i t i e s f o r d r i e r a s s o c i a t i o n s were lower than f o r the s t a t i o n outside the f o r e s t . The graphs a l s o show that greater temperature as w e l l as humidity extremes occurred on higher p l o t s , probably due more to the cleaner atmosphere than to the d i f f e r e n c e i n a l t i t u d e . In Polystichum and Vaccinium - L y s i c h i t u m under p r o t e c t i o n of ground vegetation the temperatures changed l e s s than i n other communities. Wet ground surface, t r a n s p i r a t i o n and r e s -t r i c t e d a i r movement account f o r high h u m i d i t i e s . In Figure 10 t y p i c a l f a l l or s p r i n g c o n d i t i o n s are represented. The f i r s t few days, except f o r short sunny p e r i o d on Tuesday, there was a l i g h t but continuous r a i n . The temperatures as w e l l as the h u m i d i t i e s remained f a i r l y constant. Contrary to general o p i n i o n , i t was found that the r e l a t i v e humidity during a r a i n i s not 100 per cent but u s u a l l y only 95 per cent. One hundred per cent r e l a t i v e humidity occurred only when there was an a c t u a l condensation due to drop of temperature as on Sunday or when the clouds were so low during the r a i n that there was a l s o a conden-s a t i o n of water i n a d d i t i o n to r a i n . The f i r s t case i s more common than the second. Figure 11 represents a few winter days. Monday and Saturday there was a l i g h t s n o w f a l l . Tuesday and F r i d a y were cloudy w i t h only a few sunny p e r i o d s , Wednesday and Thursday were c l e a r . m fo foliow page 8 5 86 Figure 12 (Appendix 8) p i c t u r e s weekly means (top of the bar) and minima (bottom of the bar) of r e l a t i v e h u m i d i t i e s i n i n d i v i d u a l p l o t s . Maxima are not represented because i n a l l the s t a t i o n s i n a l l the weeks values reached close to s a t u r a t i o n . While the hourly values r e f l e c t mainly temperature changes, the weekly values are f a r more dependent on absolute amount of water vapor content In the a i r and are of greater value i n comparing the p l a n t communities. Figure 12 shows the i n f l u e n c e of s o i l moisture and abundance of ground vegetation i n Polystichum and Vaccinium - L y s i c h i t u m as compared w i t h dry G a u l t h e r i a or intermediate Moss. As the v e g e t a t i o n d i e s i n f a l l the d i f f e r e n c e s become dependent only on the p r o t e c t i o n against a i r mixing which i t s t i l l o f f e r s . S i m i l a r , but l e s s obvious, are the d i f f e r e n c e s between higher a l t i t u d e s t a t i o n s . Again they are comparable w i t h d e n s i t y of the v e g e t a t i o n . Figures 13 and 14 (Appendix 9) present the measure-ment of r e l a t i v e h u m i d i t i e s u s i n g atmometers. They show the r e l a t i v e h u m i d i t i e s at two l e v e l s i n d i c a t i n g decrease of r e l a t i v e humidity w i t h height. This trend, though general, i s reversed during the hot c l o u d l e s s days i n the c o n t r o l s t a t i o n where high temperatures of the ground r e s u l t e d i n low r e l a t i v e h u m i d i t i e s . 87 Wind was not i n c l u d e d i n the present study, but i t s i n f l u e n c e should not be f o r g o t t e n i n any study of micro-c l i m a t e . The b u f f l e a c t i o n of the stand causes a l a g of wind for c e from the top downward accompanied by a r e d u c t i o n of i t s i n t e n s i t y . "The r e d u c t i o n of the wind speed i s p r i n c i p a l l y i n the crown space. From the lower l i m i t s of the crown down to only a few f e e t from the ground p r e v a i l s an a s t o n i s h i n g l y uniform a i r movement. Close t o the ground there i s another r e d u c t i o n b r i n g i n g the speed on the ground to zero." (Geiger, 1957.) In a m u l t i - l a y e r e d stand the p e n e t r a t i o n of wind i s much slower than i n an evenaged f o r e s t . The higher a l t i t u d e p l o t s - as compared w i t h the lower a l t i t u d e p l o t s , had: 1. Mean weekly temperature approximately 2° F. lower; 2. D a i l y range of temperatures s u b s t a n t i a l l y greater; 3. F r o s t f r e e p e r i o d at l e a s t three weeks shorter and consequently growing season s h o r t e r . 4. P r e c i p i t a t i o n of 166 inches as compared w i t h 109 inches on lower p l o t s . 5. P e r i o d between the f i r s t s n o w f a l l and the time the l a s t snow melted almost 6 weeks longer. 6. R e l a t i v e h u m i d i t i e s during the day lower, but dur-i n g the night u s u a l l y higher. References: Best, 1935; Cammerer, 1937; Cummings, 19^0; G r i f f i t h , 1933; H a r r i s and Robinson, 1916; L e i g h l y , 1937; Lowry, 1956; M i l l a r , 1937; Penman, 1955; Ramdas, 1938; Ronke, 19^9; Rohwer, 1931, 1933; Stam, Kratz and White, 1952; Staple and Lehane, 19^0; Thut, 1938, 1939; Veihmayer, 1938; Wilson, 1939. S i t e Index on Age In a d d i t i o n t o d i f f i c u l t i e s described b r i e f l y i n the i n t r o d u c t i o n concerning the assessment of p r o d u c t i v i t y i n f o r e s t r y by the use of s i t e index or height-over-age curves, there are a l s o many known f a c t o r s e f f e c t i n g the height growth w i t h i n the same b a s i c environmental c o n d i t i o n s . Under s i m i l a r environmental c o n d i t i o n s tree height may d i f f e r g r e a t l y and s i m i l a r growth may occur i n very d i f f e r e n t f o r e s t h a b i t a t s , due to i n f l u e n c e of compensating f a c t o r s . S i t e index, there-f o r e , i n d i c a t e s only i n a c c u r a t e l y the a c t u a l environmental c o n d i t i o n s e x i s t i n g i n the stand. S i t e index i s an expression of e x i s t i n g p r o d u c t i v i t y of f o r e s t stands and may be changed according to the dynamic changes of primary and secondary succession. These changes may be g r e a t l y a f f e c t e d and speeded by f o r e s t management or f i r e . (Haddock and Smith, 1956; Meyer, 1953.) S i t e index i s , t h e r e f o r e , only one of many t o o l s , which should be a p p l i e d by anybody, who wishes to c a r r y out the e c o l o g i c a l c l a s s i f i c a t i o n of f o r e s t s . ( K r a j i n a , unpub-l i s h e d .) 89 The s e n s i t i v i t y of height t o i n c i d e n t s i n the h i s t o r y of the stand, e s p e c i a l l y when change of stand density i s in v o l v e d , was noted by many e a r l y I n v e s t i g a t o r s . The only data a v a i l a b l e concerning the i n f l u e n c e of stand d e n s i t y on the height growth of D o u g l a s - f i r are of Steele (1955) c o l l e c t e d at Wind Riv e r Experiment S t a t i o n i n the state of Washington. I t was found i n young stands of D o u g l a s - f i r that as a r e s u l t of removing twenty per cent of the ba s a l area of the stand from suppressed and intermediate crown c l a s s e s , the height growth of remaining trees s i g n i f i c a n t l y increased. Spacing experiments (Isaac, 1937; E v e r s o l e , 1955; Reukema, 1959) i n d i c a t e that increased d e n s i t y of the stand has a r e t a r d i n g i n f l u e n c e on the average height growth. Eversole even concluded t h a t "the a n a l y s i s casts doubt on the use of the height of the average dominant and codominant tr e e s as a true index of s i t e q u a l i t y i n young stands." Lorenz and Spaeth (1947) a f f i r m that s i t e index curves may not give a r e l i a b l e b a s i s f o r p r e d i c t i n g the growth of coniferous p l a n t a t i o n s i n I l l i n o i s , but they s t a t e d that "density of the stand has a l i t t l e e f f e c t on the height growth." Parker (1942) working i n immature stands of lodgepole pine i n A l b e r t a found th a t height of dominants c o r r e l a t e d w i t h d e n s i t y as w e l l as wi t h age i s a good measure of s i t e q u a l i t y . Lynch (1958) worked out c o r r e c t i o n s f o r extremes i n d e n s i t y In second-growth ponderosa pine stands. I t i s a l s o a recognized f a c t t h a t s i t e index of any species i s i n f l u e n c e d by the type of 90 stand mixture and ground v e g e t a t i o n . E f f e c t of t h i s may s t i l l act i n time when the vegetation changed or the species forming former mixture disappeared from the canopy ( K r a j i n a , unpublished). P r o p o r t i o n of dominant and codominant crown c l a s s e s i s d i f f i c u l t to define adequately and height of these may be averaged f o r diameter i n one of se v e r a l ways g i v i n g d i f f e r e n t r e s u l t s (Ker, 1952). Current growth i n height i s an important but often neglected check on t o t a l height and age i n d i c a t i n g a p o s s i b l e presence of any s u b s t a n t i a l l y l i m i t i n g f a c t o r s (Ker and Smith, 1957). Another weakness of the conventional s i t e index curves i s that they are based on age (Spurr, 1952). Age i s measured w i t h d i f f i c u l t y and w i t h considerable expenditure of time. Above a l l , measurements are l e s s p r e c i s e than d e s i r a b l e (Stoate and Cr o s s i n , 1959). D e r i v a t i o n of the t o t a l age, dat i n g back to the o r i g i n of the t r e e , r e q u i r e s c o r r e c t i o n f o r the height of boring, which v a r i e s w i t h the height of borin g , s i t e q u a l i t y and the methods of establishment of the stand. Further, measurement of the height of t r e e s i s not ov e r l y accurate, e s p e c i a l l y i n dense stands and on d i f f i c u l t mountainous t e r r a i n . E r r o r s can be qui t e l a r g e . A l s o , d i f f -erent samples from the same stand do not give i d e n t i c a l r e s u l t s . The smaller the samples the greater t h e i r standard 91 d e v i a t i o n and standard e r r o r . Chapman and Demeritt (1936) j u s t i f i a b l y c r i t i c i z e d the s i t e index curves: "In no case w i l l the average curve show a c c u r a t e l y the progress of height growth f o r any one tree or stand. As the successive average height on age are found from the t o t a l number of dominant trees at each age and since t h i s number c o n s t a n t l y diminishes each successive average excludes some of the slower growing t r e e s found i n the preceding average." Smith, Ker and Heger (i960) s t a t e d that an average of two of the ten t a l l e s t t r e e s on a p l o t , represent-i n g each 10-year-age c l a s s were f i n a l l y c l a s s e d as codominants, and only one tree of the 132 s t u d i e d grew out of what appeared to be an i n i t i a l l y codominant height c l a s s . Warrack (1952) suggested that f i f t e e n per cent of the dominants decreased i n crown c l a s s between ages nineteen and t h i r t y - n i n e i n the unthinned stand at Cowichan Lake. S i t e index i s not the answer to every problem. Smith and Ker (1959) analysed volume as i n f l u e n c e d by s i x independent v a r i a b l e s , maximum height, s i t e index, t o t a l age number of tre e s per acre, b a s a l area per acre and average stand diameter, and found that s i t e index gave the poorest estimate of e x i s t i n g volume per acre. Maximum height and basal area were the most important. However, an estimate of s i t e q u a l i t y i s e s s e n t i a l i n p r e d i c t i o n of growth. 20 X 2.0 T O THE INCH 3^9-10 K E U F F E L a F S S E B C O * « D E IN U.S * __ . _ • • F i a 15 f i g . 1 P A v e r a g e S i t e I n d i c e s of al l C o m m e r c i a l T r e e S p e c i e s P r e s e n t w i t h i n I n d i v i d u a l C o m m u n i t i e s . J L II ILtu II F I , ,, H A 1 CJ I 1 .. B I J..&L 11 LlL 11: A Hm I G a u l t h e r i o Cy I i ; S I , r -.. PI I Jl I 1 I... . ,1 S i i i • Mi.. « « « « « • * ^ 1 M o s I ' • . I. - • ' - 11 w. 11 0 .. i l l M i i ] h t 1 1 P o l y s t i c h u m , 1 . . . JL I 1 II 1 I , j , jl , , l I -I I i ,1 I 1 ,, 1 [r'u t J L . IL V a c c , - G a u l t h . '• I I , 1 I ,, 1 I c , 1: 1 , 1 I 1 . 1 I 1 11 I I 1 , 1 : -1 1 1 i • • J 1, 1 1 • j 1. t.tl t 11 ,*Mi . II j.l?..t I L l f H i i V a c c - M o s s . 1 1 1 ., 1 I 1 i i 1 1 , 1 . i t 1 . 1 I 1 . 1 1 1 .. 1. 1 1 , 1 1 1 II I I - . . II II I L • I I . II 1 , , , 1 , " . 1 . . i 1 , L II 1 1 B l e c h n u m 1 I 1 1 I 1 . 1 I . „ . I . .. 1 I : II ... I I . 11 I ,1 1 « Xmm . m i l l L. V a c c . - L y s . > I 1 .. 1 JL : I I I 1 mm mm • *— 1 1 1 1 1 1 1 0 0 0 0 0 0 m o in if) o in 1 I 1 tt M l R i b e s - O p l o p . 1 I 1 ,, 1 I 1 j. IL . l 1 1 1 — 1 1 l . i i . 1 I . . 1 1 . 1 . . . I . F - D o u g l a s - f i r , H = h e m l o c k . c e d a r , H m = m o u n t a i n h e m l o c k . — — — • — — C o t = c o t t o n w o o d , wi C y = y e l l o w c e d a r , S = S i t k a s p r u c e , PI = l o d g e p o l e p i n e , P w = w h i t e p i n e . -D = a l d e r , M b = b r o a d l e a f m a p l e . ( S t a n d a r d a b b r e v i a t i o n s of B. C . F o r e s t S e r v i c e . ) _ 1 1 i •a 03 •D 92 Only when we r e a l i z e a l l the l i m i t a t i o n s i n v o l v e d i n the use of s i t e index we can proceed to the a n a l y s i s of the data c o l l e c t e d i n t h i s study. S i t e index of a l l s p e c i e s was c a l c u l a t e d u s i n g the t a b l e s and graphs i n the F o r e s t r y Hand Book f o r B r i t i s h Columbia 1959. Tables f o r D o u g l a s - f i r are those of McArdle, Meyer and Bruce (194-9) and f o r hemlock, cedar, balsam and spruce of Barnes (194-9) • In the f o l l o w i n g a n a l y s i s the change i n s i t e index w i t h i n i n d i v i d u a l communi-t i e s i s c o r r e l a t e d t o the age of t r e e s . Means, standard d e v i a t i o n and standard e r r o r s are presented i n Table 2. Curves i n F i g u r e s 16 t o 19 do not n e c e s s a r i l y r e p r e s e n t the r e a l growth of t r e e s p e c i e s i n each a s s o c i a t i o n . Because the s i t e i n d i c e s of p l o t s i n each a s s o c i a t i o n were c a l c u l a t e d w i t h graphs and t a b l e s noted, the curves show mainly the d i f f e r e n c e s between our samples and the t a b l e s and graphs used. They show a l s o t h a t there are d i f f e r e n c e s i n the height-growth curves i n i n d i v i d u a l communities as l o g i c a l l y can be expected. The f a c t t h a t the stands b e a r i n g timber of h i g h e s t q u a l i t y were logged f i r s t and now support o n l y immature stands must a l s o be c o n s i d e r e d . T h i s may account f o r p a r t of the decrease i n the height growth i n mature timbers at lower a l t i t u d e s . The most -serious d i f f i c u l t y , however, was found when a n a l y s i s of balsam, cedar, and S i t k a spruce had to be based on s i t e - i n d e x curves c o n s t r u c t e d f o r hemlock, because s p e c i a l curves f o r those s p e c i e s do not e x i s t as y e t . 180 160 140 120 100 8 0 60 4 0 20 P l a n t R e p r s s C o m p a r i s o n o f S i t e i n d e x C u n -ves o f D o u g l a s - F i r ( M c A r d l e , M e y e r a n d B r u c e , 1 9 4 9 ) w i t h He ight G r o w t h m I n d . v i d u a l P l a n t C o 5 0 1 0 0 A g e 2 0 0 2 5 0 m m u n i t i es 3 0 0 ID 3 5 0 o o cv o o o CD O 10 o o cv 93 Table 2. S i t e i n d i c e s of i n d i v i d u a l t r e e species i n d i f f e r e n t p l a n t communities g i v i n g means, and standard e r r o r s of the mean. standard d e v i a t i o n s F H C B D S PW S a l a l 96.8 19.6 4.9 90.5 18.8 4.7 84.0 20.9 5.3 -Moss 143.0 13.5 2.8 118.3 14.7 3.0 97.6 16.8 3.5 Polystichum 162.6 14.1 3.0-129.9 16.5 3.1 114.8 20.0 3.9 103.1 12.5 3.1 Vaccinium -S a l a l 71.9 6.4 3.4 57.9 11.6 4.0 57.4 17.8 6.2 77.5 16.1 6.6 Vaccinium -Moss 115.4 14.5 6.5 104.4 15.3 3.5 97.0 14.7 3.1 92.6 22.9 4.9 -Blechnum 131.0 23.1 7.9 121.0 24.2 4.9 117.4 21.6 4.4 115.4 21.0 4.2 Vaccinium -Ly s i c h l t u m 95.9 22.5 7.1 103.6 17.1 5.3 83.7 24.8 7.8 Ribes -Oplopanax 111.1 23.4 7.8 93.9 21.3 7.1 84.2 19.4 6.2 88.7 139.3 5.1 26.5 1.7 8.9 S i t e index was c a l c u l a t e d from the average t o t a l height of dominant and co-dominant or the highest t r e e s o c c u r r i n g on the p l o t . With t h i s i n mind, the curves (Figures 16 to 19) should he s t u d i e d . I t becomes immediately obvious that there are d i f f e r e n c e s between the t a b l e s and graphs used and the c o l l e c t e d data. D i f f e r e n t p l a n t communities d i f f e r , as can be expected, not only by the absolute value of the t r e e growth but a l s o by the d i s t r i b u t i o n of the growth during the l i f e of the stand (compare the signs and values of c o r r e l a t i o n c o e f f i c i e n t s e.g. f o r D o u g l a s - f i r , Polystichum versus Vac-cinium - Moss, S a l a l versus Vaccinium - S a l a l and low-a l t i t u d e communities versus h i g h - a l t i t u d e communities). In S a l a l the growth i s b e t t e r i n immature stands but i t l e v e l s o f f e a r l y . In Vaccinium - S a l a l immature growth i s slow, the grand p e r i o d of growth i s reached l a t e r and the stand keeps i n c r e a s i n g i t s height at a time when growth i n S a l a l has already stopped. In low a l t i t u d e communities where mature stands a l s o e x i s t e d , most of the c o r r e l a t i o n c o e f f i c i e n t s f o r hemlock and cedar have a negative value, i n h i g h - a l t i t u d e communities they have a p o s i t i v e value i n d i c a t i n g a d i f f e r e n t shape of the growth curve. Because the d i s t r i b u t i o n i s approximately e q u a l l y on both sides of zero, I f these curves were averaged f o r a l l the communities they would approximate the accepted height c l a s s e s . Taking i n t o c o n s i d e r a t i o n that D o u g l a s - f i r and cedar are predominantly l o w - a l t i t u d e species, we have to c o r r e c t the statement and say that the growth of 95 both species i n immature stands i s b e t t e r than average f o r B r i t i s h Columbia, but that the s i t e index of mature stands i s probably underestimated because of the d e t e r i o r a t i o n at m a t u r i t y . Almost a l l negative values f o r hemlock can be explained i n two ways. In lower a l t i t u d e s hemlock was often found only below the dominant crown c l a s s and then e i t h e r i t had to be used as such or not at a l l . This could have r e s u l t e d i n a f a i r l y l a r g e d i f f e r e n c e . The shape of the height - over-age curve i s d i f f e r e n t f o r t r e e s of d i f f e r e n t crown c l a s s and the shape of curve changes w i t h the p r o p o r t i o n of the stand sampled (Smith, Ker and Heger, i960). On a l l p l o t s , hemlock probably ends i t s height growth i n t h i s region e a r l i e r than i n other c o l d e r p a r t s of the coast of B r i t i s h Columbia where hemlock grows longer on good s i t e s i n low a l t i t u d e s . Balsam i n higher a l t i t u d e s grows w e l l i n young stands but increment i n height i n mature f o r e s t s i s slow. In the f l o o d - p l a i n community, Ribes - Oplopanax, a l l data i n accepted curves concerning the height growth of hemlock, cedar and balsam, and to a l e s s e r degree of spruce, are very i n a c c u r a t e . The growth curves there show steady growth of a l l the t r e e species much longer i n t o the m a t u r i t y than i n any other a s s o c i a t i o n and a l l c a l c u l a t i o n s of s i t e index based on conventional curves underestimate the p r o d u c t i v i t y of these s i t e s . White pine , which was found only i n the Vaccinium - S a l a l a s s o c i a t i o n i n numbers p e r m i t t i n g a n a l y s i s , 96 grows w e l l when young, but stops soon a f t e r i t reaches about 150 years and u s u a l l y d i e s soon t h e r e a f t e r . Alder was found to f i t almost p e r f e c t l y the shape of accepted curves. Table, 3 compares c o r r e l a t i o n c o e f f i c i e n t s of s i t e index and age of i n d i v i d u a l tree species o c c u r r i n g i n each a s s o c i a t i o n . Moss, the most common community at lower a l t i t u d e s , appears t o be w e l l represented by the average curves f o r B r i t i s h Columbia. This I n d i c a t e s the random sampling used i n c o n s t r u c t i o n of these curves. Height curves as the c o r r e l a t i o n c o e f f i c i e n t s v e r i f y , are averages constructed f o r d i f f e r e n t height c l a s s e s . That s e v e r a l stands reached the same height at the same age or at matu r i t y does not mean that the height was i d e n t i c a l at a l l stages of the development. One may have grown f a s t soon a f t e r i t s establishment, the other a f t e r slow i n i t i a l growth may have caught up w i t h i t i n i t s younger mature stage. S i t e index curves are by t h e i r nature averages of an area f o r which they were constructed, t h e r e f o r e , i f we d i v i d e the f o r e s t i n t o d i f f e r e n t h a b i t a t s , we cannot expect that the height at the same age w i l l be the same, n e i t h e r can we expect that the height growth f o l l o w e d the same mathematical curve. For p r a c t i c a l purpose i t has often been assumed tha t the shape of the s i t e index curve i s the same f o r a good s i t e as f o r a poor s i t e . This approximation i s g e n e r a l l y accepted as one g i v i n g good r e s u l t s under average 97 Table 3. C o r r e l a t i o n c o e f f i c i e n t s , S i t e index on age f o r tr e e species. P H C B D S PW S a l a l -.23 - . 4 8 * - .61 Moss -.01 -.09 -.08 Polystichum - . 4 6 ' -.22 - .11 .06 Vaccinium -S a l a l .21 -.53 .80* .33 Vaccinium -Moss .14 * -.57 .46 - .20 Blechnum .04 * -.53 .07 -.22 Vaccinium -Ly s i c h i t u m -.45 .25 - . 4 6 Ribes -Oplopanax .44 .58* * .67* .03 .34 * s i g n i f i c a n t t o 5$ l e v e l . To follow page 9 7 1 8 0 r 160-140 120-100-8 0 60-4 0 C o m p a r i s o n of S i t e Index C u r v e s ( M c A r d l e , M e y e r a n d B r u c e , 1 9 4 9 ) w i t h Height o v e r A g e C u r v e s in D i f f e r e n t P l a n t C o m m u n i t i e s D o u g l a s F i r 20-P o l y s t i c h u m P o l y s t &> M o s s B l e c h n u m P o l y s t & M o s s BI e c n n u m VGCC -MOSS S o ' a I M o s s B i e c n n u m & V a c c - M o s s S a I ai V a c c - S a l a l V a c c - M o s s S a l a l V a c c - S a i a l V a c c S a i a I S i t e Index C u r v e s F u l l L i n e s F i g 2 0 2 0 4 0 A g e 8 0 100 98 c o n d i t i o n s without being t r u e . L a t e l y , however, new methods of c a l c u l a t i n g height-over-age curves give a d i f f e r e n t shape of the curve f o r each s i t e index (Smith, Ker and Heger, i960). The exact shape of s i t e - i n d e x curves cannot be derived by standard anamorphic methods from data c o l l e c t e d on tempor-ary sample p l o t s . •The curves i n Figures 16 t o 19 were constructed by p l o t t i n g s i t e - i n d i c e s over age f o r each a s s o c i a t i o n . In Figure 20 heights of i n d i v i d u a l t r e e s c o r r e c t e d t o the value of the nearest s i t e - i n d e x c l a s s were p l o t t e d over age i n the system of re c t a n g u l a r co-ordinates. Because of the enormous amount of work i n v o l v e d i t was done only f o r immature Douglas-f i r to i l l u s t r a t e i n more d e t a i l the d i f f e r e n c e s i n height-growth curves i n d i f f e r e n t communities. A b e t t e r approach to the problem would be to analyze the s i t e index over age as the w r i t e r attempted (Table 3), hut only t o the l e v e l of c o r r e l a t i o n c o e f f i c i e n t s , or to use a more accurate method of ana l y z i n g f o r r e g r e s s i o n c o e f f i c i e n t s height of dominant and codominant t r e e s over s i t e index (Ker, 1957; B r i t i s h F o r e s t r y Commission, 1928). Due t o e m p i r i c a l s e l e c t i o n of the p l o t s , p o r t i o n of the stand samples, c l a s s e s of tre e s sampled and methods of a n a l y s i s , p a r t of the v a r i a t i o n could have been introduced i n t o the r e s u l t s . Stem a n a l y s i s would provide a very u s e f u l check of the curves presented. The presented t a b l e and • 99 graph (presenting means, one and two standard d e v i a t i o n s around the mean and standard e r r o r (Figure 21, Table l ) are s e l f - e x p l a n a t o r y . The data show i n most cases t h a t we can a t t a c h t o them a high degree of confidence. Exceptions are D o u g l a s - f i r i n Vaccinium Moss and Blechnum a s s o c i a t i o n s , where D o u g l a s - f i r occurs r a r e l y i n mature stands, the confidence that we can a t t a c h t o f i g u r e s i n the t a b l e i s a l s o not high. S i t k a spruce growth was analyzed i n Ribes - Oplopanex and s i t e index ranged from 99 t o 171 f e e t . Arguments against the use of height-age curves are based mainly on the incompleteness w i t h which growth i n height expresses p r o d u c t i v i t y . No approach can be designed at the present time to give a t o t a l measure and the best one i s only a poor estimate of the present or past y i e l d s , yet we can f i n d no good s u b s t i t u t e f o r height-age curves i n p r e d i c t i n g f u t u r e growth (Smith and Ker, 1959). S i t e index i s a d i r e c t measurement of p r o d u c t i v i t y of t r e e species grown n a t u r a l l y on c e r t a i n s i t e s and pre-sumably s u i t a b l e f o r them, the r e f o r e no i n d i r e c t approach can give b e t t e r r e s u l t s . S u c c e s s f u l a p p l i c a t i o n i n f o r e s t r y of any other c l a s s i f i c a t i o n system independent of the height 100 growth depends on the degree to which such a system can be c o r r e l a t e d w i t h s i t e index growth. Every approach to c l a s s i f i c a t i o n i n f o r e s t r y must r e a l i z e the n e c e s s i t y of easy and accurate c o r r e l a t i o n of u n i t s w i t h i n and between reg i o n s . S i t e index f u l f i l s t h i s need e x c e p t i o n a l l y w e l l i f the reference age i s standardized. "The greatest advantage of the height-age approach i s i t s s i m p l i c i t y and the p o s s i b i l i t y t o recognize any reasonable number of q u a l i t y c l a s s e s and the ease of conversion to any u n i t of measurement. Height-age curves can be developed w i t h a nominal amount of f i e l d work f o r a s i n g l e species or a group of spe c i e s . These can be used to provide an index of q u a l i t y w i t h i n any f o r e s t s t r a t a , g i v i n g i n d i v i d u a l or average estimates f o r any s i z e of u n i t or d e s i r e d degree of p r e c i s i o n (Smith, Ker, and Heger, i960). A n a l y s i s of the Environment In the f o l l o w i n g a n a l y s i s p r o d u c t i v i t y of the s i t e , expressed by s i t e index of the most important species on the p l o t , was considered dependent v a r i a b l e . Where D o u g l a s - f i r was present on the p l o t and the h a b i t a t was considered s u i t -able f o r i t s growth, the s i t e index of the p l o t was based mainly on t h i s species even i f i t was present i n small numbers. This may increase the e r r o r i n estimate of s i t e index of D o u g l a s - f i r . In other communities hemlock and Table 4. Summary of e c o l o g i c a l c l a s s i f i c a t i o n s on the coast of B r i t i s h Columbia. F i g u r e s are means and standard d e v i a t i o n s f o r D o u g l a s - f i r i n communities where i t o c c u r s . * Present S p i l s b u r y and Smith Becking K r a j i n a - S p i l s b u r y Schmidt M u e l l e r -study 19^ 7 1954 unpublished 195^ Dombois Co a s t a l Douglas- t h e s i s 1959 f i r zone C o a s t a l D o u g l a s - f i r zone S a l a l 100 + 23 Moss 143 + 19 P o l y s t i c h . 163 + 13 Vacc. S a l a l 72 + 6 Vacc. Moss 121 + 23 Blechnum 134 + 23 G a u l t h e r i a 127 + 18 P o l . - Gaulth. 151 + 15 P o l y s t i c h . 161 + 14 Gaulth. - Usnea 93 + 12 -P •H CD £ M £ -P 05 CD ?-t CD > p s o rH — U rH CD T3 > C <> O CO O CO O O •H CD O H CO rH O rH O co 0 . O CO & rH CO 0 O CO . cO CO O rH CO •H ft co PM > CO > S pq > r4 O Organic matter tons/acre T o t a l exchange c a p a c i t y equivalents/100 sq.meters Exchangeable c a t i o n s m l b s / a c r e A v a i l a b l e P l b s / a c r e 75 Ca Mg K 195* 125 85* 143 184 64 195 358 185 100 .200 14695* 1797 8440 21306 4816 10580 210 712 170 840 507 2022 1734 34o 542 90 287 522 370 904 206 416 187 173 312 104 524 79 112 11 29 92 4 155 D i s t r i b u t i o n of chemical p r o p e r t i e s i n ho r i z o n s H o r i -pH (means) zon 0 3.8 3.8 3.4 3.5 3.5 3.6 4.6 -A 4.0 4.0 4.4 3.5 3.7 3.9 - 4.8 B 5.1 5.5 5.4 4.5 5.2 5.1 - (c)5.2 Organic matter % 0 52 23 39 70 58 63 100 -A 1 2 2 30 1 4 - 20 B 47 75 59 - 48 33 - (c) 80 Exchange c a p a c i t y fo 0 20 8 13 48 34 27 100 -A 2 2 2 52 5 2 - 43 B 78 90 85 - 61 71 - (c) 57 Ca % 0 99 94 42 53 97 100 100 -A 1 4 18 47 3 0 -B 0 2 40 - 0 0 - (c) 87 H U l h-1 Table 7. (Continued) s s X o 0 s 3 P> CO •H •H •H •H -H c P C C ^ ! CO rH CO •H rH •H •H O co ft CO >5 O CO O CQ o O -H CD O rH ra rH O rH O CQ CD O CQ rQ rH CO o o CO CO CO O rH CO >a •H ft CO S £> CO s> s PQ t> P i Pi o Mg % 0 51 10 i 9 52 54 40 100 A 1 7 7 48 2 8 - 14 B 48 83 74 - 44 52 - (c) 86 K % 0 59 23 12 68 54 32 100 -A 1 5 3 32 8 7 - 11 B 40 72 82 - 38 61 - (c) 89 P % 0 5 6 4 45 30 70 100 -A t r . 4 1 55 2 4 - 8 B 95 90 95 - 68 89 - (c) 92 s i n g l e measurement. M Ul ro < -0 GOOD OOJOJVJ I vo OJ CAVJ1 H M - O r - 1 ! - 1 C O O H M r—1 r—1 C O M -pr vo oo ro OOOJ -pr o s ro r - 1 M h- 1 h- 1 I—• I—1 1—1 h- 1 H H H (J - p r V J l S C A S VO H 1 CA o ro vji S V D H M O CAVJ1 - p r V O S H 4=" ( B O W O C O H -<1 CO CO O 1 l_i |_i |_i M H H t—1 V D O H H VQ OJ CA S O W OJ vo o cr vo ro o vovji ro • H H H P r - 1 M ro CA vovo ro vo vo ro oo ro OM i c o o o OVJI ro OVJI M r-1 l - 1 M VO VJl VJl E l u v i a l A c i d L i t h o s o l Degraded C o n c r e t i o n a r y Brown Orterde Podzol Orterde Humic Podzol Humic Podzol Minimal Podzol O r t h i c Brown P o d z o l i c Modal A c i d Dark Brown Gley Podzol O r t h i c G l e y s o l P i t c h y Peat Anmoor O r t h i c Dark Grey G l e y o s o l A l l u v i a l Regosol o si t-< < «coro-J O CO O CO 0 O -H CD O rH O rH 0 co CD O CO X? rH O CO CO CO O rH CO >3 •H ft PM > co > s PQ >^ cn 0 Pseudotsuga m e n z i e s i i Thuja p l i c a t a Tsuga h e t e r o p h y l l a Abies a m a b i l i s P i c e a s i t c h e n s i s Chamaecyparis n o o t k a t e n s i s Pinus m o n t i c o l a Populus t r i c h o c a r p a Acer c i r c i n a t u m Sorbus s i t c h e n s i s Cornus n u t t a l l i i Sambucus pubens Ribes bracteosum Oplopanax h o r r i d u s M e n z i e s i a f e r r u g i n e a Mahonia nervosa G a u l t h e r i a s h a l l o n Rubus s p e c t a b i l i s Vaccinium alaskaense Vaccinium p a r v i f o l i u m H p l o d i s c u s d i s c o l o r Chimaphila m e n z i e s i i T r i Hum ova turn Linnaea b o r e a l i s L i s t e r a cordata L i s t e r a c a u r i n a Streptopus roseus Cornus canadensis T i a r e l l a t r i f o l i a t a T i a r e l l a u n i f o l i a t a Osmorhiza c h i l e n s i s C i r c a e a a l p i n a Goodyera o b l o n g i f o l i a L y s i c h i t u m americanum 5/2 5/2 5/2 5/2 5/2 5/2 5/2 5/2 5/2 5/2 5/2 5/2 5/2 5/2 5/2 5/2 5/2 5/2 5/2 5/2 5/2 5/2 2/3 5/3 5/1 5/2 2/3 5/2 5/2 5/2 5/2 1/3 2/3 5/2 V 5 4/5 5/4 5/2 4/2 5/2 5/2 5/3 5/3 5/2 5/2 5/2 5/2 5/2 5/2 5/2 5/2 5/5 5/3 3/3 3/3 5/3 5/2 5/2 5/2 5/2 5/4 5/2 5/3 5/2 5/3 156 Table 9. (continued) S S s s 0 X o 3 -P CO •H •H •rH •H -H C -P C c C ,2 CO rH CQ •H rH •H •H O CQ a 03 ra >» O 03 O CQ o O >H CD O rH m rH O rH O CQ CD O CQ P rH 03 o o 03 05 03 O rH CO >5 •H ft CO OH > CO PH > ^ O Rubud pedatus Maianthemum d i l a t a t u m Tolmiea m e n z i e s i i Hemitomes congestum Veratrum v i r i d e V i o l a g l a b e l l a S m i l a c i n a s t e l l a t a T r i s e t u m cernuum Ciraa l a t i f o l i a Poa p a l u s t r i s Equisetum t e l m a t e i a B o y k i n i a e l a t a T h e l y p t e r i s p h e g o p t e r i s D r y o p t e r i s a u s t r i a c a P o l y s t i c h u m munitum P t e r i d i u m a q u i l i n u m Blechnum s p i c a n t Athyrium f i l i x -femina Gymnocarpium d r y o p t e r i s P l a g i o t h e c i u m undulatum R h y t i d i a d e l p h u s l o r e u s Mnium punctatum R h y t i d i a d e l p h u s squarosus R h y t i d i o p s i s r o b u s t a Eurhynchium s t o k e s i i P e l l i a sp. Mnium i n s i g n e Conocephalum conicum Sphagnum squarrosum Sphagnum p a p i l l o s u m 1/3 5/3 5/1 5/2 5/3 5/2 5/1 5/2 5/3 5/2 5/3 2/3 5/2 5/3 5/2 5/2 5/2 5/2 5/2 5/2 5/2 5/4 5/2 5/2 5/2 5/2 5/2 5/2 5/2 5/2 5/2 5/2 5/2 5/2 5/2 5/2 5/2 5/2 5/2 5/2 5/2 5/2 5/3 5/3 5/3 5/4 5/3 5/2 5/4 4/3 5/2 5/3 3/3 3/3 5/3 5/5 2/3 5/2 5/2 5/3 5/2 5/4 5/2 157 Table 9. (Concluded) 5/ constant 4/ subconstant 3/ common 2/ i n f r e q u e n t /5 P l a n t e x c l u s i v e l y r e s t r i c t e d to c e r t a i n v e g e t a t i o n u n i t . /4 P l a n t w i t h s t r o n g p r e f e r e n c e f o r a s p e c i f i c v e g e t a t i o n u n i t , but i n f r e q u e n t l y o c c u r r i n g a l s o i n other u n i t s . /3 P l a n t o c c u r r i n g f r e q u e n t l y i n s e v e r a l u n i t s but w i t h optimum d e f i n i t e l y i n a s p e c i f i c u n i t . /2 P l a n t s p e c i e s without a d e f i n i t e p r e f e r e n c e . / l P l a n t rare or a c c i d e n t a l , w i t h d e f i n i t e optimum o u t s i d e the cons i d e r e d v e g e t a t i o n u n i t . Communities of the D r i e r Subzone 158 1. G a u l t h e r i a a s s o c i a t i o n G a u l t h e r i a a s s o c i a t i o n i s the d r i e s t f o r e s t com-munity i n the r e g i o n . I t occurs t y p i c a l l y on exposed peaks or r i d g e s and on upper slopes at e l e v a t i o n s below 1400 f e e t . The most t y p i c a l f e a t u r e of the environment of t h i s community i s the shallow outcrop s o i l s on r i d g e s . These s o i l s are formed by org a n i c accumulation on a s o l i d rock, u s u a l l y smoothed by r e c e n t g l a c i a l a c t i v i t y . Below the r i d g e the s o i l s are c o n s i d e r a b l y deeper (averaging two f e e t ) but because of the h i g h percentage of stones, sandy t e x t u r e , h i g h permea-b i l i t y , and steepness of the slo p e , these s i t e s are as dry as those on r i d g e s d u r i n g the r a i n l e s s summer months. Because of t h e i r h i g h l o c a l p o s i t i o n on the slope s i t e s of t h i s com-munity do not r e c e i v e any a d d i t i o n a l supply of water by seepage, and a l l the moisture p r e s e n t i s the d i r e c t r e s u l t of the p r e c i p i t a t i o n . R a i n f a l l here i s no lower than i n other a s s o c i a t i o n s , t h e r e f o r e i t must be the g r e a t e r l o s s of water by r u n - o f f which accounts f o r the dryness. The small amount of water r e t a i n e d by the s o i l s of t h i s a s s o c i a t i o n i s f u r t h e r reduced by higher t r a n s p i r a t i o n and e v a p o r a t i o n . The e f f e c t of t h i s l a t t e r i n f l u e n c e can be seen on southern and southwestern s l o p e s , where t h i s a s s o c i a t i o n was found on deeper s o i l s and i n a lower p o s i t i o n on the slope and on l e s s convex r e l i e f . Dry raw humus t h i c k l y covers the s o i l on the f l a t tops as w e l l as on the sl o p e s , 159 and Is one of the important causes of p o d z o l i s a t i o n . I t i s i n t e r e s t i n g t o note t h a t the g r e a t e s t p o d z o l i s a t i o n i n t h i s community was not on the f l a t tops, but on the slopes w i t h more concave r e l i e f . In the S a l a l a s s o c i a t i o n i t appears t h a t Douglas-f i r , hemlock and cedar become e s t a b l i s h e d at approximately the same time i n s u f f i c i e n t numbers to p r o v i d e f o r f u l l s t o c k i n g of the stands of any composition. D o u g l a s - f i r , being the f a s t e s t growing, c o n t r i b u t e s most of the b a s a l area and volume i n Immature and o l d e r immature stands. White pine and a l d e r form an i n s i g n i f i c a n t p o r t i o n of the stand and were absent i n the m a j o r i t y of analyzed p l o t s . S a l i x , Rhamnus, Prunus and Cornus, a l l f a i r l y common i n v e r y young stands, disappear or remain only i n openings as soon as the canopy of D o u g l a s - f i r and hemlock c l o s e s . Taxus, i f i t gets e s t a b l i s h e d i n these h a b i t a t s , remains an unimportant p a r t of the stand. The occurrence of an e x c e p t i o n a l l y dry year e l i m i n -ates most t r e e s of a l l s p e c i e s from p l a c e s where s o i l i s formed by o n l y a v e r y shallow l a y e r of organic matter above s o l i d rock. Here and t h e r e , an o c c a s i o n a l t r e e remains sta n d i n g , w i t h i t s r o o t s p e n e t r a t i n g i n t o the cracks i n the r o c k s . T h i s g e n e r a l e l i m i n a t i o n of t r e e s from these shallow s o i l s happens u s u a l l y when the t r e e s are only a few f e e t h i g h . 160 By t h i s time the seed t r e e s , which survived f i r e by being i n more s h e l t e r e d p l a c e s , are u s u a l l y damaged by wind or fungal i n f e c t i o n s . I f seed i s present, t h i s short time c y c l e i s repeated p e r i o d i c a l l y , covering the openings w i t h d i f f e r e n t kinds of woody v e g e t a t i o n . I n t e n s i t y of the summer drought and depth of the s o i l decide how ,far these openings w i l l extend. Even i f the canopy i s already closed, there does not seem t o be any e l i m i n a t i o n of tr e e s i n normally wet years. In e x c e p t i o n a l l y dry years hemlock, due to i t s shallow root system and lower drought r e s i s t a n c e , i s the f i r s t t o s u f f e r and i t s numbers decrease more r a p i d l y than those of Douglas-f i r or cedar. At the age of approximately 30-40 years of age, stands i n the S a l a l a s s o c i a t i o n seem to be composed p r i m a r i l y of three species; D o u g l a s - f i r , hemlock and cedar. Develop-ment of the stands and changes i n t h e i r composition are presented i n g r a p h i c a l form i n Figure 32. The probable height f o r any age can be read i n Figures 16 to 20. At the age of about 200 years the stand s t a r t s to break up, a l l o w i n g more l i g h t to reach the ground, and regeneration of hemlock and cedar w i t h an o c c a s i o n a l Douglas-f i r takes p l a c e . I t i s not unusual at t h i s stage t o f i n d a very dense regeneration of pure hemlock i n t h i c k e t s , where the competition i s so intense that a l l the trees are stagnant. I t seems that i n most cases, snow damage ends the l i f e of . C h a n g e i n t 1 6 1 t h i s growth. On b e t t e r s i t e s , even i n S a l a l a s s o c i a t i o n , we u s u a l l y f i n d r e g e n e r a t i o n of s e v e r a l s p e c i e s , and the competi-t i o n l e s s severe. Because hemlock and D o u g l a s - f i r are p r o b a b l y s h o r t -l i v e d i n t h i s a s s o c i a t i o n , owing to t h e i r i n a b i l i t y to regenerate the crown, the l a r g e s t t r e e s , at l e a s t i n diameter i n mature stand, w i l l be cedars. Those found, however, were of v e r y low q u a l i t y , and w i t h dead tops . Among them was found an a l l - a g e d canopy of hemlock w i t h a lower p r o p o r t i o n of cedar and i n f r e q u e n t D o u g l a s - f i r . K r a j i n a e x p l a i n s frequent occurrence of cedar by the e f f e c t of "... parent m a t e r i a l (rocks) which have a s t r o n g i n f l u e n c e upon r a t h e r shallow s o i l s ( f r e q u e n t l y mostly o r g a n i c ) . Because rocks of t h i s r e g i o n (quartz d i o r i t e s , d i o r i t e s , monzonites) are r i c h i n p l a g i o c l a s e f e l d s p a r s , they permit the establishment of Thuja p l i c a t a t h a t r e q u i r e s r e l a t i v e l y v e r y g r e a t q u a n t i t i e s of c a l c i u m and magnesium.... Western hemlock e a s i l y regener-a t i n g e s p e c i a l l y there where the decaying c o n i f e r o u s wood i s c o v e r i n g the f o r e s t f l o o r , would always o b t a i n i n a l l aged stands a great chance to become dominant. Western r e d cedar w i l l h a r d l y grow i n h e i g h t here, being g r e a t l y a f f e c t e d by dieback." 2. Moss a s s o c i a t i o n The Moss a s s o c i a t i o n i s the most common p l a n t community and from the monoclimax p o i n t of view i t can be co n s i d e r e d a c l i m a t i c climax community of the d r i e r subzone. 162 I t i s a mesic community o c c u r r i n g on g e n t l e lower and middle slopes at lower a l t i t u d e s . Contours and p r o f i l e are u s u a l l y s t r a i g h t , which suggests t h a t though the seepage may e x i s t i n s p r i n g and a f t e r the r a i n , there Is no concen-t r a t i o n of l a t e r a l l y moving water. S o i l s are u s u a l l y moist a l l the time, except d u r i n g l o n g - l a s t i n g summer droughts. Parent m a t e r i a l i s g l a c i a l t i l l , and, l e s s commonly, a l l u v i a l sands and loams. T y p i c a l f o r t h i s a s s o c i a t i o n i s the accumulation of org a n i c matter i n the form of dry raw humus. Where raw humus occurs, p o d z o l i s a t i o n i s st r o n g and s i t e index u s u a l l y low. Wind exposure i s g e n e r a l l y h i g h . Prom the s t a t i s t i c a l a n a l y s i s p r e s e n t e d i n Table 4 and g r a p h i c a l a n a l y s i s i n F i g u r e s 23 t o 31? i t can be seen t h a t t h i s a s s o c i a t i o n i s i n every r e s p e c t h a l f way between the dry a s s o c i a t i o n s , S a l a l and Mahonia, and the moist 'Poly-stichum a s s o c i a t i o n . The growth of t r e e s i s moderately h i g h ( D o u g l a s - f i r , mean 142 f e e t , s.d. 15 f e e t ) . The shape of contours, through i t s e f f e c t on s o i l depth and s o i l moisture, has the g r e a t e s t i n f l u e n c e on the p r o d u c t i v i t y of these s i t e s . Steeper slopes support stands of lower q u a l i t y . On southern and southwestern exposures, t h i s a s s o c i a t i o n extends a l s o onto areas of concave r e l i e f . Here on deep s o i l s seepage occurs q u i t e f r e q u e n t l y . In t h i s a s s o c i a t i o n , as i n the p r e c e d i n g one, the most important d i r e c t f a c t o r i n f l u e n c i n g the t r e e growth i s s t i l l the s o i l water regime. 163 T h i s a s s o c i a t i o n does not have any s i g n i f i c a n t s p e c i e s among the ground v e g e t a t i o n , hut con t a i n s elements of both the dry S a l a l and moist Polystichum a s s o c i a t i o n s . The d i f f e r e n c e In sp e c i e s s i g n i f i c a n c e i s only q u a n t i t a t i v e . Since these h a b i t a t s are g e n e r a l l y without seepage, cover and v i g o r of the hy d r o p h y t i c elements of the v e g e t a t i o n are g r e a t l y reduced even In openings, compared w i t h the Polystichum a s s o c i a t i o n . Stand composition and growth can be r e a d i l y seen i n F i g u r e s 32b and 33. I t appears t h a t hemlock i s more important i n t h i s than i n other a s s o c i a t i o n s . T h i s c o u l d have happened because of the b i a s e d s e l e c t i o n of the p l o t s . They were s e l e c t e d i n such a way th a t the ground v e g e t a t i o n was mainly composed of mosses. K r a j i n a (unpublished) s t a t e s : "... p a r t l y because of h i g h s t o c k i n g i n these stands, but a l s o mainly because the raw humus development t h a t i s i n t h i s C o a s t a l Western Hemlock Zone g r e a t l y promoted here, supports mosses ( P l a g i o t h e c i u m undulatum, R h y t i d i a d e l p h u s l o r e u s , Eurhynchium oreganum, Hylocomlum splendens, and Dicranum fuscescens) which are the raw humus b u i l d e r s . These v i g o r o u s l y growing mosses t h a t do e l i m i n a t e by t h e i r competition many herbs are the main reason of a r e l a t i v e l y poor development of herbaceous l a y e r . " A l s o i t i s very important t o note t h a t stands of the Moss a s s o c i a t i o n have the g r e a t e s t b a s a l area and volume. I f we use the b a s a l area and volume as a measure of stand d e n s i t y , these stands have the h i g h e s t s t o c k i n g of a l l the communities s t u d i e d . The h i g h e r the d e n s i t y , the more the shade t o l e r a n t s p e c i e s are favoured. Rowe (1956) speaking about t r a n s i t i o n of f o r e s t m Manitoba from p o p l a r - to p o p l a r - s p r u c e - t o spruce p o p l a r - to spruce s t a t e s t h a t percentage of cover c o n t r i b u t e d by mosses r i s e s a b r u p t l y as mixed stands change t o spruce, due to i n c r e a s i n g shade. Only s p e c u l a t i o n s can be made r e g a r d i n g the presence of non-commercial s p e c i e s i n the v e r y young stands. On 26 p l o t s only two almost dead t r e e s of Prunus and one of S a l i x , B e t u l a and Taxus were found. I f the p r e v i o u s stands on these p l o t s were as dense as the p r e s e n t ones, there was no seed of these non-commercial s p e c i e s p r e s e n t . Prom the o b s e r v a t i o n of newly d e f o r e s t e d areas these s p e c i e s appear i n the d e f o r e s t e d area v e r y soon a f t e r l o g g i n g or f i r e . T h erefore i t seems l o g i c a l t h a t they disappeared from the stand when the canopy c l o s e d , w i t h the r e s t of the v e g e t a t i o n . Remains of dead a l d e r s i n d i c a t e t h a t , i n v e r y young stands of t h i s a s s o c i a t i o n , a l d e r i s q u i t e common. Because only one mature p l o t of Moss a s s o c i a t i o n was analysed, i t i s very d i f f i c u l t t o make any p r e d i c t i o n s about the probable stand development. D o u g l a s - f i r i n t h i s a s s o c i a t i o n seems to be f a i r l y l o n g - l i v e d . Culmination of the f i r s t g e n e r a t i o n of hemlock p r o b a b l y occurs at about 250 years of age when mature t r e e s become v i c t i m s of f u n g a l . i n f e c t i o n and d i e , opening the canopy. New r e g e n e r a t i o n of 165 hemlock and l e s s f requent cedar w i l l s t a r t . There w i l l a l s o be more fre q u e n t ground v e g e t a t i o n c o n t a i n i n g elements of both dry S a l a l a s s o c i a t i o n and moist P o l y s t i c h u m e s p e c i a l l y i n p l a c e s where m i n e r a l s o i l w i l l be exposed. 3. P o l y s t i c h u m a s s o c i a t i o n The P o l y s t i c h u m a s s o c i a t i o n develops i n lower a l t i -tudes on lower g e n t l e r s l o p e s , u s u a l l y below the Moss assoc-i a t i o n , where concave r e l i e f concentrates the seepage water moving over impervious h o r i z o n s of compacted b l u i s h - g r a y hardpan ( o r t s t e i n ' — ^ ' K r a j i n a ) or impervious l a y e r s of c l a y . The only exceptions are a few p l o t s on steeper slopes and s t r a i g h t or even convex contours below the r i v e r t e r r a c e s , where water seeps to the s u r f a c e and e i t h e r flows down i n sma l l s t r e a m l e t s or disappears again i n the permeable s o i l m a t e r i a l a few f e e t below. T h i s p l a n t community, b e i n g c o n d i t i o n e d by g r e a t e r e f f e c t of seepage water, i s completely independent of aspect and i n s o l a t i o n . The permanent seepage s u p p l i e s not only a d d i t i o n a l water d u r i n g the dry summer months, but a l s o a c e r t a i n amount of d i s s o l v e d minerals needed f o r the growth of t r e e s . S o i l s are u s u a l l y deep (mean depth 39 i n c h e s , s.d. 9.5 inches) and v e r y permeable and t h e r e f o r e a e r a t i o n of the r o o t zone i s not impeded. Because of h i g h s o i l moisture and u s u a l l y s h e l t e r e d p o s i t i o n , o rganic m a t e r i a l decomposes s u f f i c i e n t l y w e l l to prevent any great accumulation. The r e s u l t of t h i s decomposition i s a d u f f mull 166 humus, under which l e a c h i n g seldom occurs. Greater accumul-a t i o n of o r g a n i c matter i n t h i s a s s o c i a t i o n was found only i n p l a c e s which were concave and v e r y wet. T h i s a s s o c i a t i o n has the h i g h e s t p r o d u c t i v i t y i n the whole r e g i o n ( S . I . mean l6 l f e e t , s.d. 16 f e e t ) hut due to low s t o c k i n g the volume i s u s u a l l y w e l l below the pos-s i b l e f i g u r e . I f the P o l y s t i c h u m a s s o c i a t i o n s t a r t s a f t e r the complete d e s t r u c t i o n of the p r e v i o u s stand, as i s the most common case, the ground i s f i r s t covered by dense growth of f e r n s and herbs and p r o b a b l y by the second year by shrubs such as Rubus, Sambucus, Cornus, Rhamnus, Vaccinium and Acer. With the shrubs i t i s not uncommon to f i n d a l d e r and some-times cottonwood and b r o a d l e a f maple. I f the seed of commer-c i a l s p e c i e s , e s p e c i a l l y s h a d e - i n t o l e r a n t D o u g l a s - f i r , does not a r r i v e soon a f t e r the d i s t u r b a n c e , the chances of good s t o c k i n g of the next f o r e s t stand are r a t h e r poor. Large patches d e n s e l y covered by P o l y s t i c h u m and other f e r n s are u s u a l l y without t r e e s . I t i s not only because of the e f f e c t of d i r e c t shading but a l s o mechanical damage. Large and heavy l e a v e s of f e r n s , as they d i e d u r i n g f a l l and winter, cover the ground so densely t h a t a l l the young s e e d l i n g s are e i t h e r broken or " s u f f o c a t e d . " Trees are u s u a l l y l o c a t e d on s l i g h t l y e l e v a t e d ground where v i g o r of f e r n s i s lower and s e e d l i n g s i n t h e i r youngest stage get the necessary minimum of l i g h t . I f these p l a c e s are a l r e a d y covered by 167 shrubs, v i n e maple or a l d e r , there may be no r e g e n e r a t i o n p o s s i b l e f o r many years t o come. I f the seed of t r e e s comes immediately a f t e r the d i s t u r b a n c e , at l e a s t some s e e d l i n g s s u r v i v e the competition of f e r n s and shrubs. Even i n v e r y young stands of Polystichum, the number of commercial t r e e s i s very s m a l l . But growth both i n d i a -meter and height of those t r e e s which do s u r v i v e , e s p e c i a l l y i f they stand on s l i g h t l y e l e v a t e d and b e t t e r a e r a t e d ground, i s v e r y r a p i d due t o a permanent supply of seepage water r i c h i n m i n e r a l n u t r i e n t s . The r e s u l t a n t volume per acre i n P o l y s t i c h u m stands i s u s u a l l y h i g h . The e v o l u t i o n of stands i n t h i s a s s o c i a t i o n i s pre-sented i n F i g u r e s 32b,32e and 33. E i r i n t h i s a s s o c i a t i o n -w i l l p r o b a b l y s t a r t to d e c l i n e e a r l i e r than cedar, around 500 or 600 years of age and i t s d e c l i n e w i l l be much sharper. Because f i r w i l l not regenerate under the canopy of the e x i s t -i n g t r e e s and i n competition w i t h f e r n s and shrubs" i t w i l l u l t i m a t e l y disappear from the stand. Cedar w i l l grow i n r o t a t i o n of about 800 y e a r s , hemlock about 400 and a l d e r about 100 y e a r s . T h e r e f o r e , the climax type of f o r e s t i n t h i s p l a n t community w i l l have cedar i n the dominant c l a s s w i t h i n f r e q u e n t hemlock. The o l d e s t cedars w i l l have diameters up t o 100 inches whereas hemlock w i l l r a r e l y be over 40 i n c h e s . The a l l - a g e d canopy below the dominant c l a s s w i l l be formed by hemlock and cedar w i t h some a l d e r i n the w e t t e s t p l a c e s and o c c a s i o n a l balsam. Hemlock w i l l be the most numerous. 168 Commercial value of these over-mature stands w i l l he f a r below t h e i r value when D o u g l a s - f i r was present i n large numbers and the stand was healthy i n i t s younger mature stage. Communities of the Wetter Subzone Communities of the d r i e r subzone, where the new stand u s u a l l y s t a r t s a f t e r the complete d e s t r u c t i o n of the ol d , c h a r a c t e r i s t i c a l l y have a uniform t r e e canopy. In the wetter subzone f o r e s t s , due to greater p r e c i p i t a t i o n and cooler c l i m a t e , a l a r g e r p r o p o r t i o n of the sampled stands were mature and appeared a l l aged. But f i r e at these a l t i t u d e s i s a l s o very common as scars on trees and charcoal i n the humus l a y e r i n d i c a t e . Most of them, however, are l e s s severe and only of l o c a l extent, burning mainly dry raw humus and l i t t e r without causing a great deal of d i r e c t damage to the stand. Roots on the surface are damaged as the surface l a y e r of humus i s destroyed but only.a few i n d i v i d u a l s are seve r e l y damaged. I t appears that the stand was only l o c a l l y completely destroyed by f i r e . Very probably f i r e caused only the primary or p a r t i a l damage and the remaining t r e e s were then k i l l e d by wind, i n s e c t s , f r o s t damage or f u n g i . There-f o r e , u n i f o r m i t y of age and hence of f o r e s t physiognomy i n these a l t i t u d e stands i s l e s s common. 4. Vaccinium - G a u l t h e r i a a s s o c i a t i o n S i m i l a r to the low a l t i t u d e G a u l t h e r i a a s s o c i a t i o n , t h i s community occurs on the wind exposed peaks and ri d g e s 169 adjacent slopes, at a l t i t u d e s u s u a l l y between 1,000 and 2,500 f e e t . I t s most s i g n i f i c a n t feature i s the very shallow out-crop s o i l . On the ri d g e s and peaks l i e l a r g e f l a t boulders, covered only by a t h i n l a y e r of organic m a t e r i a l overgrown by mosses and low growth of Vaccinium and S a l a l . I f tr e e s become e s t a b l i s h e d here, t h e i r growth i s very slow and they u s u a l l y p e r i s h i n the f i r s t dry year. In depressions between the boulders and r i d g e s accumulation of organic m a t e r i a l Is great e r . Below the r i d g e s and covered by raw humus l a y e r , a shallow mineral s o i l i s common (mean s o i l depth 12 inches s.d. 7 inches) on which the tr e e s are able to s u r v i v e , but growth i s slow ( s i t e index, hemlock, 70 f e e t , s.d. 8.4). Occasion-a l l y on southern slopes where t h i s a s s o c i a t i o n extends lower on stony s o i l s of g l a c i a l t i l l o r i g i n , the s i t e index may exceed 80 f e e t . Although t h i s a s s o c i a t i o n occurs m higher a l t i t u d e s which have considerable r a i n f a l l , the a v a i l a b i l i t y of water during the growing season i s probably the most important f a c t o r l i m i t i n g t r e e growth. In Vaccinium - G a u l t h e r i a only mature stands were found. Some of them s t i l l r e t a i n e d a small p o r t i o n of shade-i n t o l e r a n t D o u g l a s - f i r and white p i n e . These t r e e s must have s t a r t e d e i t h e r a f t e r a complete or almost complete d e s t r u c t i o n of the previous f o r e s t or some of them regenerated around openings which In t h i s a s s o c i a t i o n are numerous. Since no, young pines or D o u g l a s - f i r s were found during t h i s study, and, t h e r e f o r e , the f i r s t e x p l a n a t i o n appears more l o g i c a l . In the S a l a l a s s o c i a t i o n these openings are u s u a l l y on a v e r y shallow ( o f t e n l e s s than 1 inch) organic s o i l , o v e r l y i n g s o l i d r ock. In such s i t e s a l l the r e g e n e r a t i o n of y e l l o w cedar, hemlock and r e d cedar i s k i l l e d p e r i o d i c a l l y d u r i n g the extreme summer drought, hut w i t h i n a year, among the dry remains, r e g e n e r a t i o n of the same sp e c i e s s t a r t s a new short c y c l e . In t h i s a s s o c i a t i o n the subalpme s p e c i e s , Abies a m a b i l i s , Chamaecyparis n o o t k a t e n s i s and Tsuga mertensiana meet w i t h s p e c i e s from lower e l e v a t i o n s . Hemlock i s p r o b a b l y the most important s p e c i e s i n the young stands, f o l l o w e d by D o u g l a s - f i r , white p i n e , cedar, balsam and y e l l o w cedar. From the remnants of white pine and D o u g l a s - f i r found on the p l o t s i t can be s t a t e d t h a t i n young stands these two s p e c i e s form a f a i r l y s i g n i f i c a n t p r o p o r t i o n of the b a s a l area as w e l l as of the volume. Yellow cedar too seems to be more frequent i n young stands. Stand h i s t o r y and p r o p o r t i o n s of the s p e c i e s are presented on graphs i n F i g u r e 32c and 33. When the stands of t h i s community re a c h about 400 y e a r s , i t i s l i k e l y t h a t white pine and l a t e r D o u g l a s - f i r w i l l be completely e l i m i n -ated and the stand w i l l be composed of only hemlock and cedar w i t h a s m a l l p r o p o r t i o n of balsam and yellow cedar. 171 5. Vaccinium - Moss a s s o c i a t i o n This a s s o c i a t i o n occurs throughout a wide range of a l t i t u d e s but i t i s commonest at e l e v a t i o n s above one thousand f e e t (mean a l t i t u d e 1335 f e e t ) . At lower e l e v a t i o n s t h i s community Is frequent i n deep, cool mountain v a l l e y s where the growing season i s much shorter than i n the corresponding a l t i t u d e s outside the mountains. The microclimate and grow-i n g c o n d i t i o n s i n these v a l l e y s are probably s i m i l a r to s i t u a t i o n s s e v e r a l hundred fe e t higher on the mountain slopes. In s p i t e of the f a c t that a greater number of the p l o t s were on southern exposures, the la r g e standard d e v i a t i o n (Figures 23 and 24) i n d i c a t e s that t h i s a s s o c i a t i o n i s probably e q u a l l y common on a l l aspects. T y p i c a l l y t h i s community i s found on steep slopes and on s t r a i g h t contours and p r o f i l e s . I t s occurrence on mid-slopes i s most common. Wind exposure i s moderate. T h i s a s s o c i a t i o n i s r e l a t i v e l y e q u a l l y f r e -quent on a l l parent m a t e r i a l s and i t s more frequent l o c a t i o n on g l a c i a l t i l l (Figure 27) i s due to the f a c t that most of the area under study i s covered by g l a c i a l mantle. Consider-i n g the high a l t i t u d e and steepness of the slope, the s o i l s are very deep (average almost 3 f e e t ) and not too stony. Ground water i s common u n t i l l a t e s p r i n g , e s p e c i a l l y on long slopes, and f o r a long time a f t e r each r a i n , but d r i e s out e v e n t u a l l y during the r a i n l e s s summer monthsi S o i l s were found to be not too permeable and always moist. Accumulation 172 of organic m a t e r i a l was u s u a l l y very high (mean almost 6 inches) hut p o d z o l i s a t i o n not too severe. S i t e index i s low due to g e n e r a l l y high a l t i t u d e s . Vaccinium - Moss i s the commonest a s s o c i a t i o n at h i g h e r - e l e v a t i o n s i n t h i s zone. Here Douglas f i r i s r a r e , seldom c o n s t i t u t i n g a s i g n i f i c a n t p a r t of the f o r e s t . Ev,en young stands are composed mainly of hemlock and cedar. But i f D o u g l a s - f i r occurs, i t i s u s u a l l y the t a l l e s t of a l l the t r e e s present. Balsam i s not frequent i n f u l l y stocked young stands and seems to increase i n importance i n mature stands only as the canopy s t a r t s to hreak up. At higher a l t i t u d e s , there may he an o c c a s i o n a l mountain hemlock and yellow cedar; at lower a l t i t u d e s , an o c c a s i o n a l vine maple and Taxus. Stands u s u a l l y have good s t o c k i n g from the young-est stage. E l i m i n a t i o n of t r e e s occurs mainly i n the lower canopy and progresses r a t h e r r a p i d l y . Therefore we can assume that the l i g h t i s the l i m i t i n g f a c t o r , more important than root competition or water r e l a t i o n s . Changes o c c u r r i n g i n the stands can be followed on Figures 32c, 32f and 33. A f t e r the f i n a l disappearance of D o u g l a s - f i r the stand w i l l be composed mainly of hemlock w i t h lower p r o p o r t i o n of cedar and balsam. 6. Blechnum a s s o c i a t i o n The Blechnum a s s o c i a t i o n i s a t y p i c a l p l a n t com-munity of higher a l t i t u d e s but being one t h a t i s dependent on the permanent seepage water close to the s o i l surface, 1 7 3 i t a l s o occurs i n the co l d shaded v a l l e y s i n the mountains. I t i s e q u a l l y frequent on a l l the aspects. The slope i s u s u a l l y moderate. The shape of contour i s t y p i c a l l y concave conc e n t r a t i n g the seepage water, but shape of p r o f i l e was found both concave and s t r a i g h t . As w i t h the Polystichum, the Blechnum a s s o c i a t i o n i s commonest on the lower p o s i t i o n on slope, e s p e c i a l l y at lower a l t i t u d e s but at high a l t i -tudes la r g e standard d e v i a t i o n i n d i c a t e s that i t can occur anywhere except on the r i d g e . This community was found u s u a l l y on s o i l s w i t h lower p e r m e a b i l i t y or where impermeable s t r a t a were close to the surfac e . Therefore the s o i l s were u s u a l l y shallow. In s i t u a t i o n s where t h i s a s s o c i a t i o n occurred on ledges of s o l i d rock, the s o i l m a t e r i a l was e i t h e r a l a y e r of organic matter (black muck) or a very shallow mantle of g l a c i a l t i l l covered e i t h e r by bl a c k muck or raw humus, depending on the c o n f i g u r a t i o n of the t e r r a i n . This p l a n t community was u s u a l l y s h e l t e r e d from high winds. Accumulation of organic m a t e r i a l and the r e s u l t a n t p o d z o l i s a t i o n was moderate but thic k n e s s of the A e l a y e r v a r i e d c o n s i d e r a b l y . P r o d u c t i v i t y of t h i s a s s o c i a t i o n was found to be higher than any other high a l t i t u d e p l a n t community st u d i e d . Blechnum a s s o c i a t i o n Is i n many respects s i m i l a r t o Vaccinium - Moss, from which i t i s often not r e a d i l y d i s t i n g u i s h a b l e . Being a high a l t i t u d e community, t h i s a s s o c i a t i o n contains Douglas-fir,. only r a r e l y , even i n young stands. 174 As can Toe seen from the graph (Figure 32c), hemlock and cedar are the most important species at any age of the stand. As i n the Vaccinium - Moss a s s o c i a t i o n , balsam i n the Blechnum a s s o c i a t i o n i s infrequent i n young stands but appears In greater numbers as the stand opens at m a t u r i t y . Because both of these communities u s u a l l y regenerate to hemlock"and cedar, balsam could have been e l i m i n a t e d from dense immature stands because of i t s slower growth. In the mature stands studied balsam often was younger than the other t r e e s , suggesting i t s l a t e r a r r i v a l . In very young stands, probably one would f i n d a very good s t o c k i n g of hemlock and cedar. Infrequent seed years and heavy seed may account f o r scarce regeneration of balsam (Schmidt, 1957). At lower a l t i t u d e s , where o c c a s i o n a l l y t h i s a s s o c i a t i o n may be found, e i t h e r due to higher p r e c i p i t a t i o n i n mountain v a l l e y s (Seymour Dam 144 i n c h e s ) , or on slopes where seepage water moves cl o s e to the surface, one may encounter o c c a s i o n a l D o u g l a s - f i r , more commonly a l d e r and sometimes a broadleaf maple. Vine maple i s l o c a l l y present i n l a r g e numbers i n young stands, Taxus i s infrequent but p e r s i s t s to the m a t u r i t y . At the age of about 30 years the stand s t a r t s to close and e l i m i n a t e the slower growing s p e c i e s . D o u g l a s - f i r i f present w i l l be the t a l l e s t t r e e , but normally hemlock w i l l form the dominant c l a s s i n immature stands. Hemlock w i l l be the most important species i n a l l the other l a y e r s as w e l l , but i n those cedar or balsam 175 may be a l s o quite frequent. In closed young stands, competi-t i o n appears to a f f e c t balsam more severely than other species, probably because i t has the slowest I n i t i a l growth. The development of the stands can be f o l l o w e d on Figures 32d and 33. At m a t u r i t y as the stand allows more l i g h t to reach the f o r e s t f l o o r , new regeneration of shade t o l e r a n t species s t a r t s , and from t h i s stage, as i n the Vaccinium - Moss a s s o c i a t i o n , a few stunted t r e e s occur which w i l l never have any commercial value. At lower a l t i t u d e s such stand w i l l give the impression of a t r u l y a l l - a g e d f o r e s t w i t h cedar and hem-l o c k e q u a l l y important i n a l l l a y e r s . Cedar u s u a l l y reaches greater age and diameter. In higher a l t i t u d e s cedar i s Infrequent and the stands are composed almost e n t i r e l y of hemlock and balsam. 7 . Vaccinium - L y s i c h i t u m a s s o c i a t i o n This a s s o c i a t i o n develops i n two d i f f e r e n t h a b i t a t s ; i n p o o r l y drained depressions or on gentle slopes w i t h con-cave r e l i e f where impervious horizons are so close to the surface that seepage water permanently saturates the whole s o i l p r o f i l e . The s o i l i n depressions i s formed by deep organic deposits which have g r a d u a l l y f i l l e d up former small l a k e s ; on slopes the l a y e r of organic m a t e r i a l i s u s u a l l y only a few inches t h i c k , being u n d e r l a i n by shallow g l a c i a l t i l l or superimposed d i r e c t l y on s o l i d rock or an impervious gley h o r i z o n . Because t h i s p l a n t community depends on l o c a l 176 topographic c o n d i t i o n s , i t i s e q u a l l y common at both high and low a l t i t u d e s . Slope i s very gentle or none, r e l i e f i s concave, aspect has no s i g n i f i c a n c e . Depth of s o i l above the permanent water t a b l e v a r i e s w i t h season but i s always very shallow. Trees grow only on humps of organic m a t e r i a l which are s u f f i c i e n t l y elevated to provide aerated rhizosphere. Stoniness depends on the o r i g i n of the s o i l m a t e r i a l . On slope p l o t s a high degree of stoniness was not uncommon. No stones occurred i n depressions. P o d z o l i s a t i o n was r a r e l y d e t e c t a b l e . P r o d u c t i v i t y of t h i s a s s o c i a t i o n was g e n e r a l l y low. Because the root zone i s l i m i t e d and tr e e s grow mainly on humps, s t o c k i n g r a r e l y exceeds f i f t y per cent. Since t h i s community occurs on a very wide range of a l t i t u d e s , a l t i t u d e was found to have the highest c o r r e l a t i o n w i t h p r o d u c t i v i t y , probably due to the d i f f e r e n c e s i n the le n g t h of growing season, temperature and r a i n f a l l . P i r e seldom damages the Vaccinium - L y s i c h i t u m a s s o c i a t i o n because t h i s community occurs i n depressions and because a prog r e s s i n g ground f i r e stops as i t reaches the wet organic deposits overgrown by r i c h hygrophytic v e g e t a t i o n . Therefore, unless destroyed by some other means, these stands are l i k e l y t o be the only a l l - a g e d stands found. Stocking i s g e n e r a l l y very low. The water t a b l e i s very high and roots of the tr e e s are g e n e r a l l y i n s e c u r e l y anchored. The t a l l e s t and heaviest t r e e s are e a s i l y windthrown, l i f t i n g up masses of organic m a t e r i a l and often knocking down s e v e r a l t r e e s standing near by. New regeneration s t a r t s on these upturned humps, while overturned t r e e s add to the accumulation of organic m a t e r i a l . The larg e areas flooded f o r a long p e r i o d a f t e r each r a i n , Sphagna and L y s i c h i t u m dominate and t r e e s are absent. Figures 32d and 3^ represent probable development of stands i n t h i s p l a n t community. In a s e l f p e rpetuating f o r e s t at lower a l t i t u d e s i n t h i s a s s o c i a t i o n , cedar w i l l form the dominant crown c l a s s . Hemlock and cedar, w i t h o c c a s i o n a l spruce, balsam and a l d e r , w i l l form a l l other l a y e r s i n probably a constant p r o p o r t i o n . D o u g l a s - f i r may o c c a s i o n a l l y regenerate, because the stands are f a i r l y open. Only those t r e e s which are on very la r g e humps w i t h a s o l i d support w i l l reach m a t u r i t y and larg e s i z e . In higher a l t i t u d e s there w i l l be a greater p r o p o r t i o n of hemlock and balsam and the p r o p o r t i o n of cedar w i l l decrease correspondingly. 8 . Ribes - Oplopanax a s s o c i a t i o n Ribes - Oplopanax a s s o c i a t i o n occurs only on the a l l u v i a l deposits of l a r g e r streams where the r i v e r meanders through the v a l l e y f l o o r . In s p r i n g the ground i s u s u a l l y flooded and new l a y e r s of sand and s i l t are deposited. During the ve g e t a t i v e p e r i o d these s i t e s are normally w e l l above the water t a b l e of the r i v e r . In the area under study t h i s a s s o c i a t i o n was found w e l l developed only i n Seymour v a l l e y . The s t a t i s t i c a l a n a l y s i s i s the r e f o r e r a t h e r biased as f a r as the environmental c o n d i t i o n s are concerned. The 178 a l t i t u d e f o r example i s very uniform (700 + 50 f e e t ) . In t h i s a s s o c i a t i o n the slope was always found very gentle and the contours and p r o f i l e u s u a l l y concave. Because of the p o s i t i o n on the v a l l e y f l o o r the wind exposure i s extremely low. S o i l s are deep, of f i n e loamy-sand texture on the surface w i t h coarse sands at depth, u n d e r l a i n by loose, coarse g r a v e l s . Ground water i s always present at the l e v e l of the r i v e r , u s u a l l y at the depth of four or f i v e f e e t . Because of the great p e r m e a b i l i t y of these sandy s o i l s , t h e i r upper l a y e r s are much d r i e r during the summer than would be expected from t h e i r p o s i t i o n . Decomposition of organic m a t e r i a l i s r a p i d and accumulation of humus i s absent. Very young s o i l s , u s u a l l y s t i l l under Influence of f l o o d s , show no signs of p o d z o l i s a t i o n . S i t k a spruce i s the most important tr e e species i n t h i s a s s o c i a t i o n . P r o d u c t i v i t y of these s i t e s had the highest c o r r e l a t i o n w i t h s o i l p e r m e a b i l i t y and s o i l moisture. The small area i n which t h i s community was found had a very uniform environment so that the small q u a n t i t a t i v e d i f f e r e n c e s between p l o t s could not y i e l d s t a t i s t i c a l r e s u l t s of any major importance. In c o n t r a s t to the other communities, the Ribes -Oplopanax a s s o c i a t i o n develops on recent a l l u v i a l d e p o s i t s , probably not more than a few hundred years o l d . I t Is pre-ceded by pure a l d e r stands on coarse g r a v e l d e p o s i t s , often not more than a few inches above the summer water l e v e l of the r i v e r . During the f o l l o w i n g years sand and loam are deposited, 179 depending on the speed of the moving f l o o d water. Organic d e b r i s are a l s o caught among the standing a l d e r s and the s o i l i s b u i l t up. At f i r s t , t r e e s of spruce, hemlock, cedar and balsam appear. They are u s u a l l y destroyed during the next f l o o d , but new trees appear annually. As the deposits increase and the r i v e r cuts i t s bed deeper, the periods during which these s i t e s are submerged become sh o r t e r , u n t i l f i n a l l y the trees s u r v i v e . Spruce w i l l soon reach the canopy of a l d e r and penetrate i t . L i g h t i s not a l i m i t i n g f a c t o r , because t h i s community never covers continuous l a r g e areas, and being i n t e r r u p t e d normally by o l d arms of the r i v e r or by the r i v e r i t s e l f , r e c e i v e s a d d i t i o n a l side l i g h t and l i g h t r e f l e c t e d from the water. Because t h i s a s s o c i a t i o n normally i s preceded by pure a l d e r stands i t probably does not e x i s t i n stands younger than about f i f t y years, unless the o l d stand was destroyed, i n which case a l l the tree species and many shrubs may s t a r t at the same time. Under these c o n d i t i o n s , D o u g l a s - f i r " may be a l s o present i n the stand and p r o p o r t i o n of a l d e r would be much lower. The probable development of the stand i n the Ribes - Oplopanax a s s o c i a t i o n i s shown by Figures 32d and 33. S i t k a spruce i s of very high q u a l i t y i n t h i s a s s o c i a -t i o n and deserves s p e c i a l n o t i c e . Almost 500 year o l d t r e e s , though w i t h dead tops u s u a l l y show no sign of decay anywhere except a few f e e t below the top. 180 Below the open spruce canopy i n mature f o r e s t s u s u a l l y an a l l - a g e d or m u l t i - l a y e r e d growth composed of shade-t o l e r a n t hemlock, balsam and cedar. Spruce was not found to regenerate i n t h i s a s s o c i a t i o n , t h e r e f o r e i t can be assumed that at the age of about 700 years, spruce would disappear from the stand. A f t e r that the stands w i l l be formed by a l l three species, hemlock, cedar, and balsam, hemlock being the most numerous. M u l t i p l e Regression A n a l y s i s In the f o l l o w i n g a n a l y s i s an attempt was made t o assess the degree of accuracy In e s t i m a t i n g the p r o d u c t i v i t y as expressed by height over age curves by u s i n g p l a n t commun-i t y and the environmental f a c t o r s . For that purpose the independent v a r i a b l e s were used i n f i v e d i f f e r e n t groups: 1. The p l a n t community and a l l the seventeen v a r i a b l e s measured. These probably i n c l u d e a l l that can be measured or estimated on each p l o t without a great expendi-ture of work or time. 2. P l a n t community and land form features together, e x c l u d i n g s o i l and moisture regime. 3. S o i l and moisture regime, l e a v i n g out p l a n t community and land form. 4 . P l a n t community alone. 5. Land form alone. 181 In t h i s p a r t of the a n a l y s i s the s c a l i n g of s e v e r a l v a r i a b l e s was changed, so that a s t r a i g h t l i n e would represent best the r e l a t i o n s h i p between the dependent and independent v a r i a b l e s . This s c a l i n g i s based on the assumption that each v a r i a b l e v a r i e s independently of other v a r i a b l e s . There-f o r e , f o r example, p l a n t communities of the wetter subzone, as a f u n c t i o n of s o i l moisture, w i l l have a f o l l o w i n g sequence, from dry to wet; Vaccinium - S a l a l , Vaccinium - Moss, Blechnum,Vaccinium - L y s i c h i t u m . The same communities, as a f u n c t i o n of s o i l depth, l o g i c a l l y w i l l have a d i f f e r e n t sequence; Vaccinium - Ly s i c h i t u m , Vaccinium - S a l a l , Blechnum, Vaccinium - Moss, and so on f o r each v a r i a b l e . By r e g r e s s i o n a n a l y s i s was c a l c u l a t e d : 1. Degree of v a r i a b i l i t y i n s i t e index accounted f o r by each of the f i v e groups of the independent v a r i a b l e s . 2. P r o p o r t i o n of v a r i a b i l i t y i n s i t e index a s s o c i a t e d w i t h each i n d i v i d u a l v a r i a b l e , l e a v i n g out the e f f e c t of a l l remaining v a r i a b l e s . ' 3 . Percentage of sum squares removed by r e g r e s s i o n f o r the two main groups of v a r i a b l e s , the land form f e a t u r e s , d i s t i n g u i s h a b l e on a e r i a l photographs, and s o i l and moisture f a c t o r s which appear to have the greatest e f f e c t on product-i v i t y and together w i t h land form are e a s i l y recognizable i n the f i e l d . This was done by g r a d u a l l y removing the f a c t o r having the l a r g e s t negative or the smallest p o s i t i v e F i g 34 To f o l l o w p a g e 181 P e r c e n t a g e o f V a r i a n c e in o f a n d S i n g l e V a r i a b l e s S i t e I n d e x A c c o u n t e d f o r by G r o u p s 1 0 0 °/o T o t a l V a r i a b i l i t y Is-in — a i_ o > o •o cy + J c -J o o u o n a L O > o o m io "O c o "O c o cy c o c n E E o u m cy E en o E x> c o o LO o c o E o c o S i n g l e V a r i a b l e s T o p o g r a p h i c So i l a n d M o i s t u r e o. o l_ en o a o +J o L. U 6) O. O in cy C Q. Crf Cy + J LO o C L X •o o CD Q. in < Cy c c o in G r o u p s of V a r i a b l e s 0 0 o 0 o 0 Q O o o o a> ro lO ro ro a. o cn O a. o o !_ O cy a O cy > o E cy rr CD > o E Cf Cy i_ rj m o a x Cy c cy > o E cy cr o cy Q. m a cy > o E cy cr o a. cy a. a sz in cy •a D co CM m i_ o c o o Ci> C L a .c m ro CM cy a. O m c o c o •»-> in O Q. cy i_ cn cy T3 •a c 3 O cn 0 0 0 0 0 0 0 o 0 0 0 o 0 0 0 o o o 0 o o 0 0 0 0 0 0 o 0 0 m 0) G) ro o tO o r- <-<- r- ro CD CM ro CM r- ro <£> T — * — CM CM x— CM CM <— CM CM co iD iD ro 182 regression c o e f f i c i e n t . In that way the factor was omitted, the omission of which gave the smallest decrease in the percentage of v a r i a b i l i t y i n si t e index accounted f o r by remaining variables. A l l three re s u l t s are presented i n Figure 34. By comparing the upper and lower part of the graph, one can note the v a r i a b i l i t y associated with each i n d i v i d u a l variable, and the e f f e c t of i t s removal on the remaining proportion of the v a r i a b i l i t y in s i t e index accounted f o r . It can be concluded from the re s u l t s that some of the variables have a high i n d i v i d u a l correlation with s i t e index, but when combined with other variables, t h e i r e f f e c t i s i n s i g n i f i c a n t . This e f f e c t Is already included i n the eff e c t of other variables with which that p a r t i c u l a r variable i s correlated. There-fore, by removal of t h i s single variable, the percentage of the remaining accountable v a r i a b i l i t y i n s i t e index does not decrease. V a r i a b i l i t y of ground water, for example, i s already contained in the succeeding variables so that the removal of the ef f e c t of ground water does not change the t o t a l v a r i a b i l i t y accounted f o r . It can be concluded that, among the topographical features, p o s i t i o n on slope, shape of contours, a l t i t u d e , shape of p r o f i l e and aspect account for 39 per cent of the t o t a l v a r i a b i l i t y . A l l the remaining variables account for only one additional per cent of the v a r i a b i l i t y and, therefore, can be omitted in p r a c t i c a l considerations of s i t e F i g 3 5 . To f o l l o w page 182 P e r c e n t a g e o f V a r i a n c e in P l a n t C o m m u n i t i e s A c c o u n t e d f o r by G r o u p s o f a n d S i n g l e V a r i a b l e s 1 0 0 °/o T o t a 1 V a n a b i l i t y 0 0 o 0 00 O CD r-o in 0 CD lO n iD a o > 0 0 D ro in > n i_ o t— E (_ X3 E o CD nt en ZJ re o C o a u — o CD CD i_ c Z3 X) /-> >> +-» /— in t_ o O o O E O X E i_ o> i_ o XI "O o > c c o — •a o CD — o o o t- l/l I/) _l CO ro co ro S i n g l e V a r i a b l e s T o p o g r a p h i c So i l a n d M o i s t u r e CD a < > CD O " CD" a. in ft) L. rap 1" r ° i i_ in O slo ntou IOSL Bod a l/l c o o u u. CD +-» 'OtO| o l/l CD CD c o u 'OtO| c TJ o 6) i_ CD " a " 3 ' CD TJ Q u CL CD -t-» -»-» Q. c As| o CD +J in o O .C As| CO LO < CL CO 1 O o !_ — c CD +-* CD -*-> th tio a E O E m CL o in CD CD u +J c o c c c" N " o ' - CD o T> CT1 f_ o o L D l/l LO CL O CL G r o u p s of V a r i a b l e s 0 0 o o o o 0 o o 0 0 o 0 0 0 ro ro ro ro C\J C\J O in LO m LO L O L O GO CD N i_ m o CD CD CD in exp hy C L O op i_ Z3 exp o C L o in m o CD o l_ x> Q C L >•— c c SD C O o »*-O on o o CD > ve oto p O CD ness de i on o o o C L a -> CD £ E u O CD in shap Re CD Cd mi sz in ste alt po shap o o o o 0 0 o o o o o o o o 0 D o 0 0 o o 0 0 o 0 o 0 0 o 0 0 o o OJ CO ro ro LO OJ CO ro CO T— ro OJ ro CD lO C Z3 o 183 index s t u d i e s . In the same way, when s o i l and water are considered, one needs t o apply o n l y s o i l moisture, t h i c k n e s s of humus l a y e r , s o i l p e r m e a b i l i t y and parent m a t e r i a l and can omit other f a c t o r s without any s i g n i f i c a n t l o s s of accuracy. Both these r e l a t i o n s h i p s are con s i d e r e d v e r y important f o r s i m p l i f y i n g aspects of f i e l d work such as mapping and making f i e l d assessments more economical. S i m i l a r a n a l y s i s was done, u s i n g the p l a n t com-munity as a dependent v a r i a b l e and the s i t e index as an independent one. In other r e s p e c t s the groups of independent v a r i a b l e s remained the same. The r e s u l t of the a n a l y s i s i s t a b u l a t e d as the p r e v i o u s one and i s presented on F i g u r e 35. I t i s p o s s i b l e t o conclude t h a t from among the land form f e a t u r e s , shape of contours, p o s i t i o n on slope, a l t i -tude and steepness of slope c o n t a i n a l l the v a r i a b i l i t y which was accounted f o r and the a d d i t i o n a l f o u r f a c t o r s d i d not add any accuracy t o the r e s u l t s . I t i s necessary t o r e -emphasize the b i a s contained i n the measurements of aspect. I t i s v e r y probable t h a t aspect p l a y s g r e a t e r r o l e than t h i s a n a l y s i s i n d i c a t e s . From s o i l and water regime, o n l y three f a c t o r s appear t o be r e a l l y important: ground water, s o i l permeabil-i t y and s o i l m oisture. When combined, these three f a c t o r s account f o r J6 per cent of the v a r i a b i l i t y i n p l a n t F i g 3 6 To follow page 183 P e r c e n t a g e o f V a r i a n c e in P l a n t C o m m u n i t i e s ( E c o s y s t e m U n i t s ) of t h e D r i e r S u b z o n e A c c o u n t e d f o r by G r o u p s a n d S i n g l e V a r i a b l e s co ui Cy n o £_ o > o cy +-> c 3 o u u o o o o .CO cy E en cy i_ cy o E n c o o CO ro o •o c o •o c o X cy "O c CO CM r-cy c o n c a S i n g l e F a c t o r s T o p o g r a p h i c ro G r o u p s o f F a c t o r s co ro 0 a o O o 0 o 0 D o 0 01 0> CO LO o Is- cO 10 CO If) cy Ul cy C L cy a o o — o ~ cy > ui +J i_ J Z ui c o ZP C L o ui O o u Q. O !_ c a cn o X O ui 4— 4-cy do c ul cy o O o c Cl' o — a cy T J L cy C L a c o 1/1 cy c o — o -*-» .c x: 2 0_ i/i to to S o i l a n d M o i s t u r e o 0 o o o 0 o o co ,_ ro CM CM LO m o o cD cy ul CO a " l_- cy ^~ o a. o 0 cy L. >1 £1 o Ul Ul c o 4— o o 0 L. cy o 0 Z> C L o t— Ul o O L_ c 4— o u C L cn o E CM C L cn o X O 4— H— cy fc) C L ul Ul o O ul Ul XI O c cy r M i C c o +-> U cy ZJ "O rot 1 t 1 o C L cy cy C L cy Q . c o c u Ul cy +-> o D o - O). Ul — — — O +-» £_ < < a. to to to to o LO CM 0> CM cy +-> a E ro CM n o . cy. E cy C L 0 0 o o o t— <-CO CD CO Ul Ul cy l_ c cy c o o •(-' Ul E J Z C L cy cy u •o > c o o E cn — cy i_ or O ui 184 a s s o c i a t i o n . A l l a d d i t i o n a l f a c t o r s add only 2 per cent to the t o t a l v a r i a b i l i t y e x p l a i n e d . S i g n i f i c a n t d i s c o v e r y i s t h a t s o i l and moisture regime e x p l a i n a l l the v a r i a b i l i t y i n p l a n t community which c o u l d be accounted f o r by a l l the seventeen v a r i a b l e s . T o p o g r a p h i c a l f e a t u r e s or s i t e index need not be taken i n t o c o n s i d e r a t i o n ; t h e i r v a r i a b i l i t y i s a l r e a d y i n c l u d e d i n v a r i a b i l i t y of s o i l and water. Importance of water was r e c o g n i z e d i n e a r l i e r l i t e r a t u r e (Baker, 1950; Daubenmire, 1947; McMinn, i960). T h i s study gave the e a r l i e r suggestions mathematical support. F i n a l l y , s i m i l a r a n a l y s i s was done w i t h a l l the a s s o c i a t i o n s i n c l u d e d i n the wetter and the d r i e r subzone s e p a r a t e l y . Because the wetter subzone occurs i n the area under study u s u a l l y at higher and the d r i e r subzone at lower e l e v a t i o n s , a l t i t u d e l o s t i t s s i g n i f i c a n c e f o r assessment of p l a n t community w i t h i n both subzones. In the d r i e r subzone ( F i g u r e 36) t o t a l v a r i a b i l i t y accounted f o r i n the dependent v a r i a b l e was 84 per cent. S o i l and moisture regime accounted f o r 8 l per cent; s i t e index and la n d form combined, f o r 73 per cent and l a n d form alone f o r 72 per cent. Only three l a n d form f e a t u r e s were important. They were shape of p r o f i l e , shape of contours, steepness of s l o p e . From s o i l and moisture regime ground water, s o i l moisture, p o d z o l i z a t i o n and s o i l p e r m e a b i l i t y accounted f o r 79 out of 8 l per cent. P e r c e n t a g e of o f t h e W e t t e r V a r i a b l e s o o GO CO o oo in CD n 0 a o i_ lO 0 o > o LO T — ID rt L. o E »*— CD <_ E o TJ *f— CP cn •»-» CD c t_ TJ 3 o C u o u CD o 1_ 3 cv +-> TJ >» c — o — E o o i_ ex E o TJ TJ > C c o D — TJ a — CD -»-> — + J o O O h- CO 1 0 _ J F i g 3 7 To follow page 184 V a r i a n c e i n P l a n t C o m m u n i t i e s ( E c o s y s t e m U n i t s ) S u b z o n e A c c o u n t e d f o r by G r o u p s a n d S i n g l e S i n g l e F a c t o r s T o p o g r a p h i c S o i l a n d M o i s t u r e x • Wn TJ C CD •»-> CO CO CD TJ 3 SI a o !_ cn O C L O -»-> o (_ o o o 0 o 0 o CO OJ ro OJ L O u CD C L I/) < CM a i/) o CD CD tour — a tour CD Of o tour L. Of u> con 3 con tn o C L con O c a i/i »*- o **-X • CD" wi O o CD C on C L CD — CD TJ CD C L C L C CD a t/i O — -t-> o SI CO CO a. CO 0 0 0 o o 0 o 0 0 o OJ 0 o a o 0 o o OJ o 1^-o o ro LO — CM CM >> o Is- <_ — OJ (_ CD i_ CD -t-» CD CD n c n (_ o O o 3 o CD E -I- 1 SL +-> E +-> Ul E ul WI CD +-> O j ~ N " - C L " CD TJ _ u. O E TJ per C c O c C r- CD N o toi L. TJ — CO o toi " O " O o l_ o c CO 0 _ C L CO O 0 1 CO G r o u p s o f F a c t o r s L O OJ x CD •TJ-C CD •«-> CO o 0 0 0 in o o o «— to 5 * — 5 0 1 L O rj> in m CD CD C L O CD ope U) L. 3 itu d C L a CD I-3 u> o I_ C L Ul onto +-> i_ U) O c o o cn O po w> o C L X U) *— o CD O CD CD o c > +-> C o o o u a CD CD E L. CJ T J CD C L a O C L C CD O U) a CD — ~" +-> sz o CL 2 < $ CO co a. CO o 0 0 o o o oo oo oo U) U) CD a c u c CD o •*-» c 1-> o o U) E o M CD — AO nt o CD N E L. T J CD o O CC C L C L ro CO OJ CO C L CD T J O 0 0 CD *-> a E c a cn L. o co CD 3 o E o CO CD o 5 TJ C 3 o 185 In the wetter subzone (Figure 37) t o t a l v a r i a b i l i t y e xplained was 88 per cent. S o i l and moisture regime accounted f o r 84 per cent; s i t e index and land form f o r 66 per cent and land form alone f o r 6l.5 per cent. Shape of contours, p o s i t i o n on slope, shape of p r o f i l e and steepness of slope accounted f o r 6l per cent, which was p r a c t i c a l l y the t o t a l v a r i a b i l i t y explained by a l l the land form f e a t u r e s . From s o i l and moisture regime s o i l p e r m e a b i l i t y , ground water, s o i l moisture and accumulation of organic m a t e r i a l accounted f o r 82 out of the t o t a l of 84 per cent. When each subzone was t r e a t e d s e p a r a t e l y there was a s u b s t a n t i a l improvement i n the t o t a l explained v a r i a b i l i t y . This suggests that the two sub-zones are d i f f e r e n t groups of data and that d i v i s i o n i n t o subzones was j u s t i f i e d ( K r a j i n a , 1959)• References: Bajzak, i960; Barnes, 1949; G r i f f i t h , i960; P a c i f i c Northwest Forest and Range Experimental S t a t i o n , i960; Smith and Bajzak, 1961. CHAPTER V CONCLUSIONS From the a n a l y t i c a l p a r t of t h i s study i t i s evident that there are h i g h c o r r e l a t i o n s among land form, parent m a t e r i a l , s o i l forming processes, v e g e t a t i o n and t r e e growth; t h e r e f o r e , f o r f o r e s t c l a s s i f i c a t i o n i t i s p o s s i b l e to use any one or any combination o f i t h e s e environmental f a c t o r s and a r r i v e at s a t i s f a c t o r y r e s u l t s . The success w i l l depend on the worker's a b i l i t y f o r t h e i r i n t e r p r e t a t i o n . I f the accur-acy i n a l l p a r t s of the p r e s e n t work i s accepted as the same, one can see t h a t i n the c l a s s i f i c a t i o n which uses a l l seventeen v a r i a b l e s , 67 per cent of v a r i a b i l i t y i n s i t e index can be accounted f o r ; u s i n g .vegetation and l a n d form without s o i l and moisture c h a r a c t e r i s t i c s 65 per cent; s o i l and moisture o n l y 55 per cent; p l a n t community 62 per cent; and la n d form alone 40 per cent. These r e s u l t s are p r o b a b l y much highe r than a p p l i c a t i o n of t h i s method to g e n e r a l f i e l d work could achieve, because the p l o t s used m t h i s study were s e l e c t e d t o f a l l Into d e f i n i t e u n i t s a c c o r d i n g t o t h e i r p l a n t community, and t r a n s i t i o n s were not c o n s i d e r e d . T r a n s i t i o n s and mosaics cannot be omitted i n p r o d u c t i v i t y assessment i n f o r e s t work, s i n c e i n the w r i t e r ' s o p i n i o n they may cover l a r g e areas. K r a j i n a (unpublished) c o n s i d e r s t r a n s i t i o n s 186 g e o g r a p h i c a l l y very narrow. They may he degraded v a r i a t i o n s of one community or b e t t e r v a r i a t i o n of another, or perhaps an a s s o c i a t i o n that needs to be separated and i n t e r p o l a t e d i n the s u c c e s s i o n a l sequence. Doubtless any approach, i n the hands of an exper-ienced worker, w i l l give good and u s e f u l r e s u l t s . Which approach i s the best f o r a p a r t i c u l a r f o r e s t area w i l l depend on the i n t e n s i t y of the f o r e s t management, the accuracy r e q u i r e d , a c c e s s i b i l i t y of the area, q u a l i f i e d labour and the means a v a i l a b l e . A l l approaches w i l l have merits as w e l l as l i m i t a t i o n s . I f we consider, f o r example, the vegetation w i t h a l l i t s l a y e r s : stand d e n s i t y being the same, s i t e s having d i f f e r e n t environmental c o n d i t i o n s support d i f f e r e n t vegeta-t i o n . The vegetation r e f l e c t s the environmental c o n d i t i o n s above the ground as w e l l as i n the rhizosphere. But because the trees occupy d i f f e r e n t volumes of a i r and s o i l , the a s s o c i a t e d p l a n t s i n d i c a t e only a p a r t of the tree environ-ment, except during the f i r s t stages of the tree growth. However, the concept of p l a n t communities i s very u s e f u l , because there u s u a l l y e x i s t s a good c o r r e l a t i o n between d i f f e r e n t l a y e r s , at l e a s t under average c o n d i t i o n s . Ground vege t a t i o n appears to r e a c t mainly to moisture. Therefore, on dry sandy and dry clayey s o i l s , on which the p l a n t cover may be almost i d e n t i c a l , the t r e e s may d i f f e r g r e a t l y i n t h e i r v i g o r , reaching w i t h t h e i r roots i n t o the deep moist l a y e r s 188 i n sandy s o i l s and remaining close t o the surface i n c l a y s o i l s . Hence, p e r f e c t agreement between ground vegetation and t r e e growth cannot be expected except i n a general way. S p i l s b u r y and Smith (19^7) described t h e i r vegetation concept of f o r e s t c l a s s i f i c a t i o n . " B i o l o g i c a l concept of s i t e index i s based on the assumption that the n a t u r a l v e g e t a t i o n , a f t e r a p e r i o d of competition approaches an e q u i l i b r i u m w i t h the complex of growth f a c t o r s . S p e c i f i c p l a n t communities (defined as possessing u n i f o r m i t y of the dominant species of the l e s s e r vegetation) are the r e s u l t of the same growth f a c t o r s that c h a r a c t e r i z e d i f f e r e n t s i t e s . These p l a n t communities when c o r r e l a t e d w i t h the volume or height of the e x i s t i n g stand, serve as an independent b a s i s f o r c l a s s i f y i n g s i t e s i n the term of growth c a p a c i t y f o r any species of tr e e s indigenous to those s i t e s . Each p l a n t community i s a q u a l i t y c l a s s and i s c a l l e d a f o r e s t s i t e type." Braun-Blanquet recognizes a l s o t h a t "... a given p l a n t community may occur i n many l o c a l i t i e s . But i t e x i s t s u s u a l l y i n one or a few w e l l defined and e c o l o g i c a l l y c h a r a c t e r i s t i c h a b i t a t s . . . . the e f f e c t i v e e x t e r n a l f a c t o r s are numerous and t h e i r combination manyfold and overlapping so frequent...." Therefore, i t cannot be expected that a d i s t r i -b u t i o n of p l a n t communities, s o i l types or tre e growth w i l l show p e r f e c t c o r r e l a t i o n w i t h gradient i n the i n t e n s i t y of any p a r t i c u l a r f a c t o r , as compensatory i n f l u e n c e s i n the environment and v a r i a b l e e c o l o g i c a l t o l e r a n c e s w i l l tend to conceal many of these r e l a t i o n s h i p s . 189 To r e j e c t the value of the ground vegetation i n c l a s s i f i c a t i o n of f o r e s t p r o d u c t i v i t y would be a f a i l u r e to recognize the a b i l i t y of p l a n t s t o grow according to t h e i r a d a p t a b i l i t y i n d i f f e r e n t e c o l o g i c a l h a b i t a t s . Also there i s no doubt that the p l a n t communities are s i g n i f i c a n t l y r e l a t e d t o the growth of tre e s and p r o d u c t i v i t y of f o r e s t s o i l i n general. They a l l are products of the same b a s i c f a c t o r s , climate and substratum as modified by land form. Turnover of organic matter, k i n d of humus, degree of l e a c h i n g , s o i l depth, depth of root p e n e t r a t i o n , ground water, s o i l moisture, mineral n u t r i e n t s and a l l the other f a c t o r s are r e l a t e d to c e r t a i n combinations of c l i m a t e , land form and substratum. For t y per cent of the v a r i a b i l i t y i n s i t e index was accounted f o r by topography and 55 per cent by s o i l and water regime. These groups of f a c t o r s have l i m i t a t i o n s s i m i l a r to the ve g e t a t i o n ; g e n e r a l l y they give u s e f u l r e s u l t s , but i n any p a r t i c u l a r case may f a i l to provide an estimate of d e s i r a b l e accuracy. Lesko (1961) d i v i d e d each a s s o c i a t i o n i n t o s e v e r a l subgroups according to the s o i l c h a r a c t e r i s t i c s . From h i s work i t appears that vegetation i s only l o o s e l y r e l a t e d to s o i l s . Surface c h a r a c t e r i s t i c s and vegetation give only an estimate of the p r o p e r t i e s of s o i l . Hence use of s o i l and water regime f o r estimation of f o r e s t h a b i t a t s and s i t e p r o d u c t i v i t y i s l i m i t e d by the extent to which one can examine the a c t u a l p r o p e r t i e s of the s o i l s and s o i l moisture (Figure 7). 190 I t i s ha r d l y probable that we s h a l l ever evolve a system of c l a s s i f i c a t i o n that w i l l be completely s u f f i c i e n t . The problem r e s o l v e s i t s e l f i n t o s e l e c t i n g one which best meets the requirements of the problem at hand. Of greatest p r a c t i c a l importance i s that the c l a s s i -f i c a t i o n be i n t e r p r e t a b l e on a i r photographs and be usable and a p p l i c a b l e on a broad as w e l l as on a d e t a i l e d l e v e l . Therefore, f o r p r a c t i c a l purposes, the c l a s s i f i c a t i o n can use best the p h y s i c a l f e a t u r e s of s i t e which can be i n t e r -p reted from topography and from the elements of vegetation only those which can be a l s o r e a d i l y observed. Swamps and a l l u v i a l s i t e s , r i d g e s and v a l l e y f l o o r s can be e a s i l y d i s -t i n g u i s h e d , but many others need a p r e l i m i n a r y study and con-stant checking on the ground. Ecology of f o r e s t communities, t h e i r s u c c e s s i o n a l development, cannot be studi e d any other way than by a n a l y t i c a l and s y n t h e t i c a l e c o l o g i c a l study, that must be done d i r e c t l y on the ground. For any f o r e s t d i s t r i c t , t h e r e f o r e , i t w i l l be necessary to evaluate the r e l a t i o n s h i p s of the p l a n t communities and s o i l s t o topography. These w i l l have to be described i n d e t a i l i f one wishes to make the best use of the a e r i a l photographs. Using s i t e s based on physiographic features i s a very good b a s i s to b u i l d on, and very valuable f o r f o r e s t management i n general. The b a s i c p r i n c i p l e s are simple and p r a c t i c a l . I t s p a t t e r n can be seen, and o b j e c t i v e l y mea-sured. Hence, r e s u l t s of d i f f e r e n t workers i n d i f f e r e n t 191 r e g i o n s should be comparable. Corresponding f e a t u r e s of eco-c l i m a t e , s o i l s , moisture and v e g e t a t i o n may be r e a d i l y entered on t h i s p h y s i o g r a p h i c framework i f g r e a t e r d e t a i l i s needed. Topographic s i t e s are c l o s e l y r e l a t e d t o p o t e n t i a l p r o d u c t i -v i t y of the f o r e s t stands. The method i s a p p l i c a b l e under a wide v a r i e t y of f o r e s t e d and n o n - f o r e s t e d c o n d i t i o n s , and can be used by any k i n d of f o r e s t or l a n d management. Another que s t i o n s t i l l a r i s e s . How r e l i a b l e are the data from one l o c a l i t y f o r work i n a l a r g e region? Does a given p l a n t community correspond w i t h the p r o d u c t i v i t y t o the same degree everywhere i t occurs, and does i t d e s c r i b e e x a c t l y the same h a b i t a t ? As macroclimate changes, the topography has a d i f f e r e n t e f f e c t on v e g e t a t i o n and growth of t r e e s . In the p r e s e n t study there are no data from a l a r g e r e g i o n , but one can use a l t i t u d e as analogous t o l a t i t u d e . In a l l communities except P o l y s t i c h u m w i t h i n c r e a s e i n a l t i t u d e s i t e index decreases. I t reaches s i g n i f i c a n t l e v e l ;in Blechnum (-.56, .01) and Vaccinium - L y s i c h i t u m (-.75? .05)? two edaphic communities, frequent i n wide a l t i t u d i o n a l range. T h e r e f o r e , both understanding and great c a u t i o n are needed when a p p l y i n g data on p l a n t communities from one area to another. CHAPTER VI SUMMARY From the study of environment and tre e growth, c a r r i e d out i n the southwestern part of the Vancouver f o r e s t d i s t r i c t , i t was concluded t h a t : 1. In the past, f i r e s had heen so e f f e c t i v e and so frequent that the succession of vegetation i n the d r i e r subzone of the region studied seldom progressed beyond the stage i n which pioneer t r e e species formed a s u b s t a n t i a l p a r t of the stand. In the wetter subzone, f i r e s , though not absent, have been l e s s severe (Figure 4 ) . 2. C l i m a t i c f a c t o r s a) Mean temperatures (9 inches above the ground i n the s h e l t e r ) among the a s s o c i a t i o n s of e i t h e r the wetter or the d r i e r subzone, v a r i e d seldom more than 1° F. Their i n f l u e n c e on the d i s t r i b u t i o n of vegetation or r a t e of growth i s therefore considered i n s i g n i f i c a n t . b) Temperature maxima had much wider range than minima. Both are i n f l u e n c e d by the temperature of the s o i l s urface, which, i n t u r n , i s c o n t r o l l e d by the d e n s i t y of the canopy, v e g e t a t i o n , k i n d of the surface s o i l l a y e r s and t h e i r moisture content. (Figures 5 and 6.) In the f o r e s t , the denser the canopy, and the c l o s e r to the ground, the measurements were taken, the narrower was the range between temperature maxima and minima. Outside the f o r e s t , 192 193 the c l o s e r to the ground the wider was the range. c) Extremes of temperatures c o i n c i d e d w i t h baro-metric pressure maxima and e a s t e r l y winds. d) Forest cover and ground vegetation o f f e r s a very e f f e c t i v e p r o t e c t i o n against f r o s t . e) Dense f o r e s t canopy may account f o r substan-t i a l water l o s s even i n zones of high p r e c i p i t a t i o n . f ) R e l a t i v e humidity of the a i r i s a f u n c t i o n of the temperature at the time of the measurement. (Figures 9 t o 11.) R e l a t i v e h u m i d i t i e s every week reached a poin t of s a t u r a t i o n . During the r a i n , unless the clouds were low and condensation took place as w e l l the r e l a t i v e h u m i d i t i e s were close to 95 per cent. 3. Tree growth a) D i f f e r e n c e s i n t r e e growth e x i s t among i n d i -v i d u a l p l a n t communities, not only i n the absolute values, but a l s o i n the d i s t r i b u t i o n of the growth. (Table 3.) Generally i n communities of the d r i e r subzone the growth was more r a p i d i n immature stands, but l e v e l l e d o f f soon a f t e r . In wetter subzone communities, a f t e r slow r a t e i n young f o r e s t s , growth p e r s i s t e d long i n t o m a t u r i t y . b) Accepted height-over-age curves underrate g r e a t l y the growth i n f l o o d p l a i n communities. (Figures 16 t o 19.) c) Growth of D o u g l a s - f i r i n immature stands i s underrated by standard height-over-age curves. The younger the stand and the lower the s i t e p r o d u c t i v i t y , the greater i s the d i f f e r e n c e . d) Chance p l a y s an important r o l e i n the range of s i t e i n d i c e s i n i n d i v i d u a l a s s o c i a t i o n s . ( F i g u r e 21.) 4. The e f f e c t of the environment on s i t e index a) Microtopography had v e r y l i t t l e value f o r e s t i m a t i o n of t r e e growth. b) Steepness of slope between 0.5 and 50 per cent had very l i t t l e i n f l u e n c e on s i t e index. Steeper slopes and areas of no measurable slope supported stands of poor growth ( F i g u r e 25). c) At a l t i t u d e s below 1200 f e e t s i t e index de-creased o n l y s l i g h t l y w i t h i n c r e a s e d e l e v a t i o n . At h i g h e r a l t i t u d e s the decrease was more r a p i d ( F i g u r e s 23 and 24). d) Southwestern aspects supported stands of best growth, n o r t h e a s t e r n aspects of lowest growth ( F i g u r e s 23 and 24) . e) With i n c r e a s e i n c o n c a v i t y of contours s i t e index i n c r e a s e d ( F i g u r e 25). f ) Change of shape of p r o f i l e from concave to s t r a i g h t c o i n c i d e d w i t h only a s l i g h t decrease i n s i t e index. From s t r a i g h t t o convex the decrease was r a p i d ( F i g u r e 26). g) Lower p o s i t i o n s on slope, w i t h the e x c e p t i o n of f l a t , i m p e r f e c t l y d r a i n e d b a s i n s , supported stands of h i g h e r growth (Figure 26). h) Greatest p r o d u c t i v i t y was found on s i t e s moderately exposed to winds. Great as w e l l as low wind 195 exposure supported stands of lower growth (Figure 27). i ) P r o d u c t i v i t y decreased p r o g r e s s i v e l y from s o i l s of a l l u v i a l o r i g i n to s o i l s of g l a c i a l t i l l to outcrop s o i l s to s o i l s of organic o r i g i n (Figure 27). j ) P r o d u c t i v i t y increased very s t e e p l y w i t h increase i n s o i l depth up to 28 inches. Greater depth had no e f f e c t on s i t e index (Figure 28). k) P r o p o r t i o n of stones had no i n f l u e n c e on s i t e index. P l o t s w i t h low percentage of stones included best stands as w e l l as poorest stands on saturated s o i l s of organic o r i g i n and impervious l a c u s t r i n e c l a y s (Figure 28). l ) With increase of seepage and s o i l moisture, s i t e index increased, but i n saturated s o i l s p r o d u c t i v i t y was a l s o very low (Figure 29). m) S i t e Index increased w i t h increase of permea-b i l i t y and highest p r o d u c t i v i t y was found on very permeable s o i l s . Extreme p e r m e a b i l i t y , however, r e s u l t e d i n very dry s i t e s w i t h low s i t e index (Figure 30). n) P r o d u c t i v i t y increased w i t h decrease of t h i c k n e s s of organic m a t e r i a l , except i n dry p l a n t communi-t i e s (Figure 30). o) With increased p o d z o l i s a t i o n s i t e index decreased (Figure 31). 5. a) Increase i n t h i c k n e s s of organic matter was found c o r r e l a t e d w i t h increased p r o d u c t i v i t y i n a l l dry communities. In moist and wet communities t h i s c o r r e l a t i o n was n e g a t i v e . Growth of t r e e s depends on the water h o l d i n g c a p a c i t y of organic matter i n former, hut appears t o have a damaging e f f e c t , impending a e r a t i o n i n l a t t e r . While c o n t r o l l e d f i r e i s d e t r i m e n t a l on dry s i t e s , i t may cause l i t t l e damage on moist s i t e s . b) While hemlock can grow on o r g a n i c m a t e r i a l , i t s growth i s b e t t e r on m i n e r a l s o i l s . c) P r o d u c t i v i t y of D o u g l a s - f i r i s h i g h e s t on the t r a n s i t i o n of Moss and P o l y s t i c h u m a s s o c i a t i o n , or on d r i e r P o l y s t i c h u m s i t e s . S i t e s w i t h best v i g o r of Polystichum a p p a r e n t l y are too wet f o r best growth of D o u g l a s - f i r . There e s p e c i a l l y the v i g o r of cedar i s at i t s b e s t . d) In the wetter subzone communities, hemlock and cedar have the h i g h e s t s i t e index on the t r a n s i t i o n between Vaccinium - Moss and Blechnum a s s o c i a t i o n . e) In the dry communities, the b e n e f i c i a l e f f e c t of the ( humus l a y e r on growth through i t s w a t e r - h o l d i n g c a p a c i t y exceeds the d e t r i m e n t a l e f f e c t of reduced p r o d u c t i -v i t y through i n c r e a s e d p o d z o l i s a t i o n . f ) Dry communities on southern and western aspects occupy a lower p o s i t i o n on the slope and extend f a r t h e r on to deeper s o i l s than on n o r t h and east a s p e c t s . P r o d u c t i v i t y of these s i t e s i s g r e a t e r , suggesting t h a t l e s s e r v e g e t a t i o n may r e f l e c t dry s u r f a c e s o i l c o n d i t i o n s , while deep-rooted t r e e s may s t i l l f i n d a v a i l a b l e water at g r e a t e r depth. 197 6. B a s a l area and volume a) Hemlock appears t o be ve r y s h o r t - l i v e d o i n the area under study. I t i s the most abundant s p e c i e s i n young stands i n a l l except dry p l a n t communities, but i t i s l i m i t e d to lower canopies i n mature f o r e s t s , and i t s p r o p o r t i o n of b a s a l area and volume of the e n t i r e stand i s u s u a l l y not g r e a t . Older t r e e s s u f f e r from a t t a c k by pathogens ( F i g u r e s 32 and 33). b) In the d r i e r subzone, D o u g l a s - f i r , i n younger mature stands, and cedar i n o l d e r f o r e s t s , are forming the g r e a t e s t p r o p o r t i o n of timber ( F i g u r e s 32 and 33). c) A l l s p e c i e s are l o n g e r - l i v e d i n the Wetter than i n the D r i e r Subzone. 7. M u l t i p l e r e g r e s s i o n a n a l y s i s a) Due t o h i g h i n t e r r e l a t i o n s among a l l the v a r i a b l e s considered, some v a r i a b l e s having h i g h I n d i v i d u a l c o r r e l a t i o n w i t h s i t e index, when combined, account f o r onl y a v e r y small p a r t of v a r i a b i l i t y i n s i t e index ( F i g u r e 34). I t i s p o s s i b l e t o omit s e v e r a l v a r i a b l e s from c o n s i d e r a t i o n without any l o s s of accuracy. b) Land form alone accounts f o r 40 per cent of v a r i a b i l i t y i n s i t e index. P l a n t community- alone accounts f o r 50 per cent; p l a n t community and l a n d form combined f o r 60 per cent; s o i l and moisture regime f o r 55 per cent. A l l seventeen v a r i a b l e s accounted f o r 6j per cent of the t o t a l v a r i a b i l i t y i n s i t e index. 198 c) S o i l and moisture regime accounts f o r p r a c t i -c a l l y a l l the v a r i a b i l i t y accounted f o r i n the p l a n t community - t o t a l 78 per cent ( F i g u r e 35); s i t e index and lan d form combined, f o r 66 per cent; land form alone f o r 54 per cent. d) Three v a r i a b l e s out of seventeen, i . e . , ground water, s o i l p e r m e a b i l i t y , and s o i l moisture account f o r 76 per cent out of the 80 per cent of v a r i a b i l i t y i n p l a n t community accounted f o r . Ground water alone accounted f o r 72 per cent. e) D i v i s i o n of the zone i n t o two subzones i s s t a t i s t i c a l l y j u s t i f i e d ( F i g u r e s 36 and 37). 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Cooling i n the lower atmosphere and the structure of polar continental a i r . U. S. Monthly Weather Rev. 64: 122-136. Whitford, H. N. and R. D. Craig. 1918. Forests of B r i t i s h Columbia. Ottawa. 486 pp. Wilde, S. A. 1958. Forest s o i l s . The Ronald Press Co., New York. 538 pp. Wilkinson, G. N. 1957. The analysis of covariance with incomplete data. Biometrics 13: 363-372. Wilson, J . D. 1939* Evaporation studies I I I . Ten Years of evaporation at Wooster as measured with black and white atmometers. Ohio Agr. Exp. Sta. Bimo. Bui. 24, 11-25. Wittich, Walter, i960. C l a s s i f i c a t i o n , mapping and interpretation of s o i l s for for e s t r y purposes. F i f t h World Forestry Congress, Seattle, Washington. 9 pp. Wolfe, J. N. et a l . 1949. Microclimates and macroclimate of Neotoma, a small v a l l e y in central Ohio. B u l l . Ohio. "Blolog. Survey 8, No. 1. Yamamoto, J . 1937. On the rate of condensation of dew. Geophys. Mag. [Tokyo] 11: 91-96. Yates, F. 1933. Tae analysis of r e p l i c a t e d experiments when the f i e l d r e s u l t s are incomplete. Emp. J . Exp. Agric. 1: 129-142. Young, F. D. 1920. E f f e c t of topography on temperature d i s t r i b u t i o n in Southern C a l i f o r n i a . Monthly Weather Rev. 48 : 462-463. Extremes, Annual and Monthly Mean Temperatures for the year 1958 and 1959 and Averages for the Period shown. ( °F) APPENDIX 1 J F M A M J J A S O N D Annual mean Coquitlam Lake 1958 Extr. maxima 49 50 56 66 86 88 89 88 79 66 54 54 Monthly mean temp. ' 39 42 41 47 57 63 69 64 55 49 39 39 50 Extr. minima 27 30 24 32 36 46 50 50 32 34 24 26 1959 Extr. maxima 46 50 50 68 80 78 86 76 70 66 66 48 Monthly mean temp. 35 36 39 45 50 55 63 58 54 50 39 38 47 Extr. minima 8 26 28 31 32 40 48 42 38 24 18 29 20 years averages 33 35 39 45 52 57 61 61 57 49 41 37 47 U.B.C. Forest 1958 Extr. maxima 54 58 65 67 86 91 98 89 85 69 56 55 Monthly mean temp. 41 45 • 44 49 60 64 70 66 58 51 41 40 52 Extr. minima 28 29 28 40 39 48 49 50 37 33 22 24 1959 Extr. maxima C 51 53 56 71 88 82 92 80 76 64 62 57 Monthly mean temp. 42 38 41 47 52 59 64 60 55 49 40 38 49 Extr. minima 7 24 28 31 42 42 45 45 38 34 13 25 10 years averages 32 36 39 45 53 57 61 61 57 48 40 36 47 Mosquito Creek 1958 Extr. maxima 49 53 59 66 85 88 91 87 81 68 53 50 Monthly mean temp. 40 43 41 46 58 63 69 65 56 50 39 40 51 Extr. minima 31 31 30 33 37 48 48 49 36 32 24 26 1959 Extr. maxima 48 52 51 67 81 81 88 77 71 64 58 48 Monthly mean temp. 35 36 39 45 50 57 64 59 54 48 39 37 47 Extr. minima 8 25 28 32 33 39 45 41 40 33 17 25 6 years averages 34 35 38 44 52 55 61 60 56 48 40 37 47 Monthly and Annual Total Precipitation for the year 1958 and 1959 and Averages for the Period shown. APPENDIX 2 J F M A M J J A S O N D Annual Coquitlam Lake 1958 28.69 14. 67 4.11 7.75 7.58 2. 45 0.00 4. 15 5. 60 14. 02 16. 32 20. 88 120. 82 1959 15.62 10. 79 16. 98 18.36 4.26 6. 28 1.97 4. 00 15. 25 12. 23 19.81 17.59 143. 18 41 years average 19.86 15. 34 14.46 9. 19 6.55 4. 56 2.90 3. 20 7.06 15. 08 17.53 22.40 138. 13 U.B.C. Forest 1958 15.76 8. 60 3.46 5.94 3.44 1. 91 0.00 2. 36 3. 48 11. 49 10. 85 13.31 80.59 1959 11.50 8. 38 10.47 11.56 5.65 5. 16 1.91 2. 56 9. 37 7. 73 12. 63 10.02 96. 95 10 years average 13.07 10. 48 9.77 6.16 3.97 4. 27 2. 87 3. 22 3.76 8. 43 11.80 13.97 91.77 Mosquito Creek 1958 23.29 11. 58 6.00 7.78 2.35 1. 92 0.07 3. 42 4. 94 11. 15 13.80 16.58 102. 87 1959 12.51 11. 80 13.53 9.70 4.01 7. 37 1.67 1. 82 11.05 6. 86 14. 11 11.96 106.39 6 years average 11.80 9; 74 10. 67 6. 88 3. 35 5. 93 2.72 2. 82 6.63 10. 56 15.43 17.11 103. 64 APPENDIX 3 Monthly and Annual Hours of Bright Sunshine for the years 1958 and 1959 J F M A M J J A S O N D Annual Total Vancouver City 1958 23 38 132 197 309 221 365 287 164 " 115 51 11 1912 1959 44 56 77 183 236 220 332 219 129 93 72 32 1693 13 years average 46 79 126 167 238 219 282 254 177 109 53 36 1786 Annual Percentage Frequency of Winds APPENDIX 4 N NE E SE S SW W NW Calm Vancouver Airport 3 6 32 19 6 6 11 15 2 ro i—j —a Co •8 oo OJ J> c i VD 00 O 4*- 4s- cn OJ oo 4s->J> to oo Ci J> >J> cn O -vl OJ 4* Cn c i 4> cn vi ^1-^4*. O OJ I-*• 4^ Cn cn 4^ - ^ Ci 4s- Cn cn OJ H * oo 4*- 4*- Cn ro vo 4^ 4^ cn Ci OJ OJ ro 4* Cn Ci ro OJ cn 4*- cn Ui ro ro vo 4*. cn vi OJ i—1 ro 4 S Cn Ci Ul H * K 4^ cn oi 4S- i— Ci 4S- cn Ci 4S- O O 4s- cn c i 4^ OJ oo £>• Cn cn Oi ro oo 4^ - cn cn oi ro oo 4^ Cn Cn cn ro oo ro 4S-Cn VI Cn c i cn ci 4s- Cn < ro Cn vl 4s O Cn oi OJ 4s 4>- cn Vl oo c i ro Cn cn c i t—1 Ci OJ 4^ cn ci co Ci oo 4^ cn Ci vi 4^ ro 4* cn fvt Cn vi oo 4^ . cn ci 00 00 Ci 4>- cn vo. vj vl O 4^ - cn d Ci Ci Cl > 4^ Cn vo Cn vo O Cn vi Ci VO 00 4* cn oo Ci V0 4s-4^ Cn vj Ci V] Ci ro vi 4^ Ci 00 Ci 4*. VI 4s Ci VI VD OJ Ci ro o 4S- Ci VO oo cn oo cn c i v) ro oo cn 4^ oi oo rfv Cn VI oo oo o 4^ Ci 00 CnciOO 4^cnvj vioji-^ O U I K vjvocn 4^ Ci vi vi o Cn 4> ci vi vo ro 4> 4^- Cn oi J> oo oo •I 4^ Cn vi Cn 4> J> 4s- cn c i Cn4i.cn 4*- Cn ci 4^ - 4> VO 4>- Cn Ci 4s- *> ro There was no shelter on this plot 4*. Cn cn ro o ci 4s- cn cn 4* Cn Cn 0 J o Cn 4 S Cn cn OJ 1— OJ 4S- Cn cn Cn OJ oo 4* Cn cn 4* OJ vo 4^ Cn cn vl OJ cn 4S- Cn cn Ci OJ Ci 4> Cn Ci 4^ 4 s OJ J> Cn Ci 4 S OJ 4^ Cn Ci cn4i.r0 4* cn c i 4S- O 4S- Cn Ci 4S- OJ 4S-4s- Cn ci cn ro 4s-4^ cn c i vo OJ )-»• 4S- cn Ci oo OJ o 4s- Cn c i 00 4^ OJ 4^ Cn Oi vj OJ O Cn cn Ci O ^ K 4^ cn Ci VD 4>- i— cn oi Ci vi Cn d Ci Ci cn ci cn ci Ci OJ Cn cn c i i—^ vj cn 4S- Cn Ci VO V] J> Cn cn ci ro vi 4^ Cn cn ci O vi cn JiUlOl 00 00 VO 4 S cn Ci oo oo vo 4s- Cl V! oo o vo ci oo VI O o cn ci vi O 4* VI Cn oi vi ro J> cn Cl vi O O O K iMn OI Ci Cl Cl 4^ -CiOO CnCiVi Ji oi N 4*- Cn vj V04^0 >-•• 4> vo viooo Vidro 4^ cn ci CnciVi cncivi CnCiVi 4 s Cn Ci 4* Cn Ci VOOOCi K O * . i—ojcn w ^ K vo vo vo vicncn 4> cn Ci oo oo Cn J> cn vi vo vo ro Cn ci V] O ro OJ Cn ci v] ro OJ i— 4i cn ci vo vo oo 4> cn a vj cn OJ Control Vaccinium moss Vaccinium-salal Blechnum Vacc. moss Vacc. salal Transition Moss Salal Polystichum Vaccinium Lysichitum ro oo OJOJ 4A OJ--J OJ OJOJ J> 4^oo ro o < o o w o ro OJ ro ro OJ 4> ro OJ cn ro oo 4^ N W * . ro OJ cn OJ 4=- to OJ cn ojrfi.cn OJ 4> cn OJ 4> ai OJ 4> cn OJ 4* d *o 4p>. OJ oo -o. 4* CTI cn 4> -g 4* cn v j r » r o oo oo -o. c n O ^ J S IVD ^ rowo> vo ai 4i- o i M w K W O D VO OO w w ^ OJ OJ 4> ro OJ 4i- roojrfi- OJ OJ 4i. ro OJ 4*. OJ 4* OJ OJ 4> u> 4*- cn 4?. J> cn 4i. 4^ cn OJ J> 4^ 4* 4^ OI O r f ^ o O ^ J O O 10 tn R vo cn 4=. ^ 00 00 K t J i * . -o o to o to 00 01 w ^ ro CN cu o ^ j c n * N in roooro M W ^ ro OJ cn ro OJ 4^ ro OJ 4> OJ OJ cn t o u ^ OJ 4* M u ^ O J ^ U I 4i.4i.cn OJ 4=- cn w ^ o i 4^ J> cn vo 4i- 10 S O ~o. Cn OJ 10 4> Cn O 0 0 O O O i S i o i O r o vo vo 00 U I I » H > i-> Cl OJ vo v] Cn w w K 00 Cn ro OJ OJ ro OJ J> ro OJ 4> N c« *• OJ OJ 4> ro OJ 4> ro OJ w w *> OJ 4^ 4* OJ 4* 01 0j4i.cn OJ 4^- 4i.4i.cn vo 4* 00 m ui u 00 4* >-* vo4i.ro 0 0 0 0 0 o w w ~o vo vo I D M ^ cn OJ VO voo i ro vo c\ ro OJ ^ 00 i-* t-* There was no shelter on this plot OJOJ 4> OJ OJ cn OJ OJ 4^ OJ OJ 4^ OJ OJ cn ro OJ 4^ OJ 4* OJ OJ 4^ OJ 4* cn o> 4^ cn 4i.4i.cn OJ J> on 4i. cn cn O o ro K O O O n-^-jtji i-^^jrfi. h ^ i o H OJ 00 00 vo ^ ro O O O M cn OJ w i o u i 0101- ' 4> 4=- O OJ o m OJOJ 4^ OJ OJ cn rooj4^ OJ OJ 4i. 0j4i.cn rooj j> O010J K K I O i c c i o i o - J o> O o !->• ro ~j vj OJ OJ cn OJ OJ 4^ cn vo ON 0 J OJ 4^ 0 J OJ 4i OJ ~ J Ol OJ 0 J 4> OJ 00 4* OJ OJ 4=> 4> 00 4*-OJ 4> Cn OJ 0 J 4 i . c n OJ O O t o w * -4* VD 0> OJ 4A 00 O to ro OJ 4> ro ro ro OJ OJ 4> O W S OJ OJ * » OJ VD vj roojrfi- ro OJ 4^ OJ OJ 4=-cn 00 4*- ^ N i - OJ vo 00 0 J 4 i . c n vi cn ro OJ 4* cn VD ON 1— 4^ 4^ Cn O O O 4*- 4^ Cn OJ 00 4^ 4* 4=- Cn 4>. vo cn 4* 4> Cn oj 00 ro 4>- 4* On O 0 0 H 4i- 4> Cn ro vo ro J> cn K 0 0 O OJ 4> cn U l ^ M O J 4 i - c n 00 cn i-* OJ 4*- 4* 00 cn 00 4* 4^ On OJ vo Cn 4>- 4* on cn vo 4* 4> 4* on o Control Vaccinium moss Vaccinium-"salal Blechnum Vacc. moss Vacc. salal Transition Moss Salal Polystichum Vaccinium Lysichitum CD a* to 00 ro vo ro ro ro cn cu 4*. cn ro cu a ro ro 4*- H ^ ro 4^- rocwJ> oo oo 4*. O J co 4i O J O J 4^- H-* ro OO ^ ro oo ro ro oo i-* ro oo roooo oo a ro ro vo o oiooi— ooocn O I W H K U T I - I— ai CO o cn cu a oo vo V I vo ro 4>- vo ro covjyj ww* CUCOJ> ro ro OJ ^ ro cu ro ro oo ro cu oo oo oo cu coco4> ww^ ro ro oo ro ro cu roroco ro ro cu OJ vo oo •->• J> ro oo-vo po oisw h-oooj oo ro a R W - J ro a to nino cn OO I-» 4> vo *^ oivon UJ H ojJ>cn oo oo roojoo i - * ro oo rorocu rococo O J O J O J cu oo 4^. OJOJ>J> rorooj rorocu rorocu rorocu cnoro n-J>ro ooooo -ooocn ^ oo cn -o. oo cn ^ cn co ro a ro p^cnpo oo ro cu vo ui vo H cu - J ro cu cu 4s- ro cu 4^ roroco i — ro co rorooj P O O J O J O J O J O J w w 4> O J O J O J rorocu rorocu rorocu rorocu J>00Ci V O O J O OiV0J> VI VJ ^ V] oo VI i— 00 OOlfJl to a I— i — cn oo NOOK O J V D O cnvoo MMO There was no shelter on this plot cu4i.cn co oo 4^ P O O J O J rorocu rocuoo O J O J O J O J oo O J O J 4* O J oo 4^ rorooo rooooj rocuoo rorooo oo 4^ K - J V O vorooo ro vo vo W K O I O ^ O O N O I M O J O O O J cnoooo cn vo 4* cnocu vo ^ oo cnvoro O J 4^ cn W O J rocuoo rorocu roojoj roojoj OJOJ4> O J O J * cu oo 4^. ro O J 4^ rocuoj rocuoo rorooo soioi 00 cn vorooo 1—00 ro vo vo 4=> 00 cu vi ro MN*- 00 a a cnoo m o w 01—0 4s- vo 00 4> 4i cn O a 4s 00 00 cn cu 00 00 O J 00 oo O oo 00 ro O J cu 4* O VD ro O J O J cn ro 00 cu cu 4i 4^ 00 ro 00 00 4> 4* 00 *>• cu O J 4> Cn 00 00 ro cu O J SOOl ro 00 00 vo o ro co 00 00 O 1- ro ro 00 00 O J O H Co 4iCn coco* O J O J O J rooooo rocuoo 000000 0000* O J O J * 00 cu 4^. rocuro rocucu 000000 roojoo a ro oj--)* KWM UI O M V I to V I ro cn vo cn 00 a 00 4>. 0000* 00O00 00 1— ro HKH V I o I— O Control Vaccinium moss Vaccinium-salal Blechnum Vacc. moss Vacc. salal Transition Moss Salal Polystichum Vaccinium Lysichitum ro v) 4A cn v i 4^ cn v i ON * . oo i — i — cn 4A Cn oi ^ f oi C l ^ ^ i — O OJ to o 4A 4* cn o oo oo 4^ u i i-> v ] O OJ Cn v i vo OJ ro ro C l 4=- Cn d i — ro Cn J> cn cn OJ l - ' V I OJ 4^ c i VD 00 0 J oo 4^ cn V O O l * . OJ 4> Cn OJ i-> Ifa OJ 4A 4A 00 O 4A 00 4A V ] cn v i ro OJ 4> cn V | Ol VD OJ 4^ cn o i o i V I OJ 4A 4 i v i cn oo OJ 4A ON VI oo Cn OJ 4* Cn 00 00 Ol ro cn OJ 4* Cn OJ OJ 4A t-* VO v } OJ OJ 4^ O ON V I OJ OJ 4A OJ 4^ ON O Ol V I OJ 4^ Cn to Cn ON V? °4 £ S ?! 4* Cn J A C n o i 4^ On cn o J 4 A C n OJ 4=- 4*- O J 4 A O i O J 4 A C n OJ 4A On O J O J J A oo oo 4»- OJ 4=- On O i l m e n >-* i-* v i i-»vioJ i —OJ ro vo vo d cn OJ O Oi v i ON cn v i cn o vo oo vo vo vo O cn o i — on vo 4^ cn oi ON 4=- ro 4* cn ^ O 4=-rf* Cn l - O N O 4 A C n o i 4i. cn on oJ4^-Cn OJOJ4A OJ 4A cn OJ4A4 ^ OJ 4A Cn OJOJ4A OJOJ4A OJ 4* On r o r o i - ' H O M vo ON 4>- OJ 10 JA v i c n o o v i 4*. vo o o v i c n O O O - J O C n o 4A On OJ *• ON f-* o OJ OJ 4*-VO VO OJ OJ cn H V O P OJ OJ JA oo oo 4^ cn ON vo Oi Cn 4^ cn oi vo ON 00 Cn cn o i O ON OJ Cn cn OI o i ro 4A Cn ON 4A OJ cn 4^ Cn OJ OJ o V* oi cn OJ OJ JA cn ON V I OJ to 4A4* Cn OJVO OJ 4A4A cn O J 0 0 Cn 4*4* cn envo 4A 4A*»Cn Civo 4A 4^ On o i OJ 4^ 4» 4^ On v i JA Cn o 4^ Cn oi cn 4A OJ 4>- cn ON On 4^ I-* 4 i on on 4A OJ VO 4* Oi ON 4*- OJ 4^ On cn Oi OJ vo 4* On on oo OJ oo 4A 4* Cn OJ vo Ol 4> 4A Cn OJ vo 00 4A 4A Cn cn vo Cn 4» Cn Ol VO 4A OJ 4^ cn o i OJ OJ oo 4>- cn ON OJ OJ OJ 4A Cn 00 OJ l — OJ 4^ vo OJ oo 4^ 4^ - Ol OJ vo 4A OJ 4A Ol vo 00 Cn OJ 4^ Ol V J V I o 4A rfi Oi ro oo o . 4A Cn ) ON 00 o o 4 i . c n VD Ol OJ 4 i 4 i . c n ON to 4=* 4* On to Oi ro 4* 4* ON to vo o 4 i Cn ON 4 i 4^ Cn OJ vo vo 4 i rfi cn 4 i vo oo 0 J 4 i . c n 4^ ro OJ 4A cn OJ ro OJ oo *• cn OJ 4A 4 i Ol h-" VO OJ OJ 4^ to oo OJ OJ OJ 4* H-1 oo OJ OJ OJ 4* OJ oo OJ OJ oo 4i-4A oo OJ oo 4A Cn OJ v i oo OJ 4A ON OJ V I o OJ 4A Cn cn v i v i OJ 4^ cn ON v i o i oo 4> cn cn o oo oo 4> cn 4A O 4 i OJ 4^ Cn 0 0 to OJ oo 4A cn v i to ro O Control Vaccinium moss Vaccimurn-salal Blechnum Vacc. moss Vacc. * salal Transition Moss Salal Polystichum Vaccinium Lysichitum APPENDIX 6 Weekly maxima and minima temperature at 6 feet and at ground surface Vacc-moss Control Vaccinium Vaccinium Blechnum Vacc-salal Moss Salal Polystichum Lysichitum moss salal Transition c I n IT! TV v* vT vn vii i July 6 76 44 66 42 69 43 67 43 68 44 68 45 82 46 68 45 69 45 112 46 58 47 71 46 56 46 64 45 64 47 83 48 67 48 63 49 13 83 43 72 44 78 44 71 45 78 44 75 48 90 48 75 46 75 47 44 44 61 46 78 45 63 47 70 47 67 48 88 53 70 50 67 50 20 90 49 77 50 83 50 78 51 81 50 82 46 83 52 79 52 79 52 ' 126 48 67 51 82 51 63 50 74 51 79 53 88 55 73 52 70 52 27 88 44 77 47 88 49 77 48 80 46 82 47 84 49 80 49 80 48 127 47 68 50 84 49 63 50 75 50 74 51 89 50 77 53 76 53 Aug. 3 95 45 79 45 85 47 82 46 84 46 82 49 85 47 82 48 83 47 121 39 68 45 80 41 63 45 78 44 77 49 85 49 74 49 70 52 10 79 46 67 46 69 47 69 48 71 47 73 48 73 47 72 47 75 47 114 44 60 49 72 47 59 49 67 48 67 48 75 49 65 50 66 52 17 76 50 62 48 66 49 64 49 77 49 82 47 79 51 77 50 78 50 108 49 56 49 70 49 58 49 65 50 66 51 71 52 65 52 65 54 24 76 48 65 46 68 46 68 47 69 46 70 47 77 48 68 47 71 47 92 44 57 49 67 46 57 48 66 47 64 48 68 49 65 50 66 50 31 74 43 60 45 64 44 68 46 64 45 70 47 68 47 65 47 66 46 82 43 54 48 63 45 55 48 63 46 61 47 65 49 60 48 62 51 Sept. 7 78 42 62 44 67 47 68 44 68 45 67 47 69 46 64 46 65 47 78 43 56 46 65 45 54 47 63 46 61 47 64 49 60 47 63 50 14 78 41 62 43 66 40 67 42 67 41 66 45 66 42 64 43 65 43 90 40 57 45 65 42 55 45 54 43 62 45 62 46 60 44 60 48 21 71 42 57 42 58 42 61 54 61 48 65 42 62 45 59 46 58 45 79 41 51 48 59 46 53 47 57 45 57 47 58 49 58 47 58 49 28 67 39 53 40 58 39 56 40 58 39 57 41 57 42 57 41 56 40 74 38 50 45 56 40 49 44 55 41 56 42 57 45 56 43 55 44 ro ro ro Appendix 6 (continued) c i n in ry_ y_ yj yn vm Oct. 5 65 41 53 40 56 40 57 49 58 40 57 42 57 43 56 41 55 42 71 40 49 43 55 " 42 49 43 56 43 55 44 55 44 54 44 54 45 12 60 32 50 43 51 33 51 36 54 33 54 36 53 38 51 37 52 36 71 32 47 39 52 36 47 40 51 37 52 40 52 40 50 40 51 43 19 70 36 54 40 59 39 56 41 59 39 54 38 56 42 55 40 53 40 72 36 49 43 52 40 49 42 44 51 53 42 53 43 51 42 52 44 26 59 36 53 40 53 39 53 41 56 41 57 41 55 42 56 41 55 42 55 38 52 43 53 41 52 43 55 43 56 44 53 44 54 44 54 45 Nov. 2 29 33 50 35 52 34 42 36 53 34 55 46 55 38 56 36 52 35 60 32 49 38 50 37 50 39 51 37 54 49 52 40 50 40 51 41 9 57 28 50 30 48 29 48 30 51 29 48 31 51 31 50 30 50 30 53 30 48 33 47 33 45 35 47 32 53 33 48 35 47 33 47 36 16 47 13 46 18 48 18 44 17 51 16 50 18 55 19 53 , 17 46 16 53 21 42 28 46 27 40 32 45 29 54 29 44 28 52 30 47 32 23 49 24 46 21 46 20 46 24 49 25 47 23 48 24 47 22 46 24 48 25 41 30 43 29 41 32 45 30 48 31 46 30 45 31 44 33 30 59 29 49 31 50 30 47 31 52 30 43 30 52 31 52 31 52 30 55 28 46 34 48 33 45 36 50 33 51 34 51 35 50 34 46 35 Dec. 7 50 28 47 29 57 29 46 30 47 29 47 30 47 31 46 30 50 30 48 30 42 32 43 31 42 34 45 33 46 37 45 33 46 32 44 34 14 44 27 43 29 44 28 44 30 45 29 47 30 46 33 47 30 46 27 42 31 39 33 40 32 40 32 42 33 47 32 45 33 45 32 44 33 21 58 27 47 30 51 29 51 31 48 30 56 31 46 32 51 31 50 31 47 30 43 31 44 31 42 34 44 31 50 34 47 34 46 33 45 34 28 45 25 43 29 42 26 43 30 45 29 47 30 45 30 44 30 44 29 40 29 37 32 40 32 39 34 42 33 44 33 43 33 41 31 41 33 Jan. 4 35 18 35 23 35 21 33 24 60 34 24 36 25 33 24 34 24 33 23 33 30 33 28 33 31 . > ^ - X * W e e k l y l O X IO T O T H E C M . KEUFFEL a Easts CO. 3 5 9 - 1 4 G M A D E IN U . S . A . f o l l o w p a g e F i d -ii A v e r a g e W e e k l y E v a p o r a t i o n f r o m A t m o m e t e r s . S i x F e e t A b o v e t h e G r o u n d - A b o v e t h e L i n e , N i n e I n c h e s A b o v e t h e G r o u n d - B e l o w t h e L i n e . C o n t r o l B l e c h n u m G a u l t h e r i a llil V a c c .- M o s s , V a c c . - G a u l t h . T r a n s i t i o n P o l y s t i c h u m • lul 1 m m = 1 0 c m * 1 Hi Hrm r H m ^ Jm-lUl o e f f i c V a c c - G a u l t h . M o s s i _ _ _ „ — - J ^ - i — -V a c c . - L y s . ||||I..IH..I Hill e n t s of A t m o m e t e r s 7 9 P e r i o d s : J u n e 2 9 t o N o v e m b e r 9 A p r i l 11 t o J u l y 3 . Cumulative Average Weekly S i x rTeerp[£^=J-- ! q n d N i n e E v a p o r a t i o n f r o m Atm ome te r s 1 4 . 359-10 A v e r a g e F i g . 1 5 . t e n d i c e s of al l C o m m e r c i a l T r e e S p e c i e s P r e s e n t w i t h i n I n d i v i d u a l C o m m u n i t i e s . H i ' „ d ( I ' B 1 H m | G a u l t h e r i a C y ' I -' I »]!: «»•»»# M o s s i I i I I I i — Pw C o t I j I Mb 1 • i I . . I . . I - . I J l .111 I I , V. j • i !: t I I P o l y s t i c h u m i I i I I B B Ida i i V a c c . i I ft* G a u l t h . i .. i 1 *?, ' .sta. t . 1 4 ... ... « fflSL V a c c . - M o s s I . . I . , I , » .£ ' s 1 «... »»..» i « t « i . si t i m i i . I JiLL i B l e c h n u m 1 i , i | — 1 i I i _ t » * i t i . I . ' ' ' J L _ _ _ J L V a c c . - L y s . i 1 . i l . . i i I R i b e s - O p l o p i l l i l l i l l I , I I I O O O m o io . I i o o o m o in I i i I I i I i C = c e d a r , H m = m o u n t a i n h e m l o c k , F = D o u g l a s - f i r , H = h e m l o c k , C y = y e l l o w c e d a r , S = S i t k a s p r u c e , PI = l o d g e p o l e p i n e , P w = w h i t e p i n e , D C o t = c o t t o n w o o d , = a l d e r , M b = b r o a d l e a f m a p l e , of B . C . F o r e s t S e r v i c e . ) ( S t a n d a r d a b b r e v i a t i o n s J nttz 180 160 140 120 100 8 0 6 0 4 0 2 0 P l a n t R e p r e s e 5 0 C o m p a r i s o n o f S i t e I n d e x C u r v e s o f D o u g l a s - F i r ( M c A r d l e , M e y e r a n d B r u c e , 1 9 4 9 ) w i t h H e i g h t G r o w t h in I n d i v i d u a l P l a n t C o m m u n i t i e s . 1 0 0 A g e 2 0 0 2 5 0 3 0 0 3 5 C P l a n t C o m m u n i t i e s R e p r e s e n t e d by M e a n s P l a n t C o m m u n i t i e s R e p r e s e n t e d by M e a n s . 160 140 120 1 0 0 8 0 6 0 4 0 2 0 ( B a r n e s G. 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