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Epiphytic vegetation on Acer macrophyllum in south-western British Columbia Kenkel, Norman Charles 1980

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EPIPHYTIC VEGETATION ON ACER MACROPHYLLOM IN SOUTH-WESTERN B . S c , The U n i v e r s i t y of B r i t i s h C olumbia, 1978 A THESIS SUBMITTED IN PARTIAL FULFILLMENT OF THE REQUIREMENTS FOR THE DEGREE OF \ • MASTER OF SCIENCE i n THE FACULTY OF GRADUATE STUDIES Department of Botany We ac c e p t t h i s t h e s i s as conforming t o t h e r e g u i r e d s t a n d a r d THE UNIVERSITY OF BRITISH COLUMBIA September 1980 BRITISH COLUMBIA by NORMAN CHARLES KENKEL © Norman C h a r l e s Kenkel,1980 I n 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 t h e r e q u i r e m e n t s f o r an a d v a n c e d d e g r e e a t t h e U n i v e r s i t y o f B r i t i s h C o l u m b i a , I a g r e e t h a t t h e 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 a n d s t u d y . I f u r t h e r a g r e e t h a t p e r m i s s i o n f o r e x t e n s i v e c o p y i n g o f t h i s t h e s i s f o r s c h o l a r l y p u r p o s e s may be g r a n t e d by t h e Head o f my D e p a r t m e n t 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 u n d e r s t o o d t h a t c o p y i n g o r p u b l i c a t i o n o f t h i s t h e s i s f o r f i n a n c i a l g a i n s h a l l n o t be a l l o w e d w i t h o u t my w r i t t e n p e r m i s s i o n . D e p a r t m e n t o f . Botany T h e U n i v e r s i t y o f B r i t i s h C o l u m b i a 2075 W e s b r o o k P l a c e V a n c o u v e r , C a n a d a V6T 1W5 D a t e September 2, 1 9 8 0 i i ABSTRACT T h i s d i s s e r t a t i o n i s concerned w i t h the a n a l y s i s and d e s c r i p t i o n o f e p i p h y t i c v e g e t a t i o n on t h e l ower p o r t i o n o f the b o l e o f Acer macrophyllum a t 5 s i t e s i n s outh-western B r i t i s h Columbia.. At each s i t e , t r e e s were s e l e c t e d f o r i n t e n s i v e s a m p l i n g . I n a d d i t i o n , the v a s c u l a r v e g e t a t i o n a t each of t h e s i t e s was c h a r a c t e r i z e d . V a r i o u s a s p e c t s of t h e r e s ponse of t h e v e g e t a t i o n t o m i c r o e n v i r o n m e n t a l v a r i a t i o n were examined u s i n g m u l t i v a r i a t e methods. . Between-tree v a r i a t i o n i n t h e e p i p h y t i c v e g e t a t i o n appears t o be p a r t l y c o r r e l a t e d w i t h m i c r o e n v i r o n m e n t a l and c o r r e s p o n d i n g h a b i t a t v a r i a t i o n w i t h i n t h e f o r e s t . B e t w e e n - s i t e v a r i a t i o n i s r e l a t i v e l y pronounced as s i t e s a r e , i n g e n e r a l , d i s t i n g u i s h a b l e on t h e b a s i s of t h e i r e p i p h y t i c v e g e t a t i o n . T h i s i s l i k e l y a r e f l e c t i o n of d i f f e r e n c e s i n f o r e s t s t r u c t u r e , m i c r o e n v i r o n m e n t , and c l i m a t e between the s i t e s . . E n v i r o n m e n t a l g r a d i e n t s r e l a t e d t o c hanging h e i g h t and i n c l i n a t i o n on the b o l e can be r e c o g n i z e d . The response of the e p i p h y t i c v e g e t a t i o n t o t h e s e g r a d i e n t s was a n a l y z e d by o r d i n a t i n g data on o v e r a l l s p e c i e s performance at each of 24 h e i g h t - i n c l i n a t i o n c o m b i n a t i o n s at a s i t e . The r e s u l t s i n d i c a t e b e t w e e n - s i t e d i f f e r e n c e s i n t h e r e s ponse of t h e v e g e t a t i o n t o t h e s e g r a d i e n t s . P a t t e r n s of v a r i a t i o n i n the e p i p h y t i c v e g e t a t i o n s u ggest t h a t t h r e e major h a b i t a t s e x i s t on t h e lower b o l e : t h e t r e e base (to 1 m), the lower s i d e o f the b o l e , and i i i the upper and mid s i d e s of t h e b o l e . S p e c i e s r e l a t i o n s h i p s and h a b i t a t p r e f e r e n c e s have a l s o been examined u s i n g o r d i n a t i o n methods. P a t t e r n s of a s s o c i a t i o n g e n e r a l l y r e f l e c t h a b i t a t v a r i a t i o n on t h e b o l e . T h i s was f u r t h e r examined by a n a l y z i n g the re s p o n s e o f the i n d i v i d u a l s p e c i e s t o t h e i n c l i n a t i o n and e l e v a t i o n g r a d i e n t s . S p a t i a l n i c h e d i f f e r e n t i a t i o n i s apparent f o r many of the s p e c i e s ; however, t h e r e i s o f t e n n i c h e o v e r l a p , s u g g e s t i n g t h a t s p e c i e s may, a t l e a s t p o t e n t i a l l y , be competing f o r space on the b o l e . The p h y t o s o c i o l o g i c a l s t r u c t u r e o f the e p i p h y t i c v e g e t a t i o n was a l s o examined. C l u s t e r a n a l y s i s of the quad r a t data combined w i t h f i e l d o b s e r v a t i o n s l e d t o the r e c o g n i t i o n of 9 e p i p h y t i c community-types which show v a r y i n g degrees of s p a t i a l d i s t i n c t i v e n e s s on t h e b o l e . a n a l y s i s of the e p i p h y t i c v e g e t a t i o n on Acer ffiacrophyllum has shown i t t o be s t r u c t u r a l l y and e c o l o g i c a l l y complex. T h i s i s l i k e l y a r e f l e c t i o n of the high degree of s e n s i t i v i t y b r y o p h y t e s and l i c h e n s show t o s m a l l - s c a l e e n v i r o n m e n t a l changes. D e s p i t e t h i s c o m p l e x i t y , f a i r l y marked t r e n d s i n the v e g e t a t i o n a r e apparent which a r e b e l i e v e d t o be r e l a t e d t o a few dominant m i c r o e n v i r o n m e n t a l g r a d i e n t s o p e r a t i n g on a g i v e n t r e e . i v TABLE OF CONTENTS ABSTRACT , i i LIST OF TABLES . v i LIST OF FIGURES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . v i i i ACKNOWLEDGEMENTS . . . . . . . x i i I . .INTRODUCTION ., 1 I I . STUDY AREAS , .... 3 L o c a t i o n ............................................... . 3 C l i m a t e 5 V e g e t a t i o n At The S i t e s 11 I I I . .EPIPHYTIC VEGETATION AND THE ENVIRONMENT ............. 24 Z o n a t i o n (Complex E n v i r o n m e n t a l G r a d i e n t s ) ............. 24 S t u d i e s Of D i r e c t H a b i t a t F a c t o r s At UEL 28 IV. .THE PHOROPHYTE ACER MACROPHYLLUM ...................... 39 B o t a n i c a l R e l a t i o n s h i p s 39 Range And D i s t r i b u t i o n ........ ........................ . 39 E c o l o g i c a l R e l a t i o n s h i p s 40 Bark C h a r a c t e r i s t i c s , 42 V. _SAMPLING METHODS AND METHODS OF DATA ANALYSIS ........... 58 Methods Of Sampling 58 Methods Of Data A n a l y s i s 60 VI . .ORDINATION OF TREES BASED ON THEIR EPIPHYTIC VEGETATION 77 I n d i v i d u a l Tree O r d i n a t i o n s ............................ 77 D i s t i n g u i s h a b i l i t y Of The F i v e S i t e s ,.. . 95 V I I . .GRADIENT ANALYSIS ON THE BOLE OF ACER MACROPHYLLUM ....101 V V I I I . .EPIPHYTIC SPECIES AND SPECIES RELATIONSHIPS .116 S p e c i e s A s s o c i a t i o n s .. 116 I n d i v i d u a l S p e c i e s Response To The H e i g h t And I n c l i n a t i o n G r a d i e n t s ................................ 129 E c o l o g y Of S p e c i e s E p i p h y t i c On Acer Ma££2Ehy^!M .130 IX. . CHARACTERIZATION OF EPIPHYTIC COMMUNITIES ON ACER MACROPHYLLUM . . 1 46 C l u s t e r A n a l y s i s .146 E p i p h y t i c Communities On Acer MacrgBhvllum .172 X. .. THE DYNAMICS OF EPIPHYTIC VEGETATION ON ACER MACROPHYLLUM 182 S u c c e s s i o n a l A s p e c t s Of E p i p h y t i c V e g e t a t i o n On Acer Macrophyllum ....... 182 R o l e Of E p i p h y t e s On Acer Macrophyllum ..194 X I . . SUMMARY .199 REFERENCES 203 APPENDIX 1. C h e m i c a l F a c t o r s Of The Bark Of Acer Macrophyllum 208 APPENDIX 2. C h e c k l i s t Of S p e c i e s E p i p h y t i c On The Bole Of Acer MacrophYllum .209 APPENDIX 3. I n d i v i d u a l S p e c i e s Response To Height And I n c l i n a t i o n ...213 v i LIST OF TABLES Table 1. C l i m a t e Data f o r the 5 Study S i t e s 7 2. C l i m a t e Data ( Y e a r l y Means, 1941-1970) f o r the 5 Study S i t e s 8 3..Mean P e r c e n t Cover V a l u e s of Woody and Herbaceous V e g e t a t i o n a t the 5 Study S i t e s , 9 4..Dominance and D e n s i t y V a l u e s of Trees a t the 5 Study S i t e s , , . 10 5. Means and Standard D e v i a t i o n s o f 7 Bark Chemical F a c t o r s Over 15 Trees at t h e 5 Study S i t e s .48 6. A n a l y s i s of V a r i a n c e o f B e t w e e n - s i t e D i f f e r e n c e s i n 7 Bark Chemical F a c t o r s .....49 7..Means and Standard D e v i a t i o n s of 7 Bark Chemical F a c t o r s Over 5 Trees and 3 Samplings H e i g h t s a t the 5 Study S i t e s , , ...54 8..Means and Standard D e v i a t i o n s of 7 Bark Chemical F a c t o r s Over 5 Trees and 6 Sampling H e i g h t s a t UEL 55 9 . . A n a l y s i s of V a r i a n c e of D i f f e r e n c e s i n 7 Bark Chemical F a c t o r s Between the Upper and Lower S i d e s of the Bole (at 3 Sampling Heights) a t UEL .56 10. .Means and Standard D e v i a t i o n s of 7 Bark Chemical F a c t o r s from Young (Small) and Old (Mature) Trees a t UEL . 56 v i i 1 1 . . A n a l y s i s of V a r i a n c e o f D i f f e r e n c e s i n 7 Bark C h e m i c a l F a c t o r s Between Young (Small) and Old (Mature) Trees at UEL 56 12..General I n f o r m a t i o n on Trees Sampled at SQU .......61 13. G e n e r a l I n f o r m a t i o n on Trees Sampled a t FUR .......63 14. G e n e r a l I n f o r m a t i o n on Trees Sampled a t UEL 65 15..General I n f o r m a t i o n on Trees Sampled at PIT .......67 16..G e n e r a l I n f o r m a t i o n on Trees Sampled at BRI .69 17. Mean L o c a l Freguency o f E p i p h y t i c S p e c i e s on the ,15 Trees Sampled at SQU , 79 18..Mean L o c a l Freguency of E p i p h y t i c S p e c i e s on the 15 Trees Sampled at FUR 83 19. Mean L o c a l Freguency o f E p i p h y t i c S p e c i e s on the 15 Trees Sampled at UEL .85 20..Mean L o c a l Freguency o f E p i p h y t i c S p e c i e s on the 15 T r e e s Sampled at PIT , .89 21..Mean L o c a l Freguency o f E p i p h y t i c S p e c i e s on t h e 15 T r e e s Sampled at BRI .91 22. Mean L o c a l Freguency o f E p i p h y t i c S p e c i e s Over t h e 15 Trees Sampled a t t h e 5 Study S i t e s .99 2 3 . . M a t r i c e s o f S i m i l a r i t y Between E p i p h y t i c S p e c i e s , f o r t h e 5 Study S i t e s ^....118 2 4 . . E p i p h y t i c Biomass at 3 Sampling L e v e l s on a F a l l e n Tree L o c a t e d a t FUR ......197 v i i i LIST OF FIGURES F i g . . 1. L o c a t i o n o f Study S i t e s i n South-western B r i t i s h Columbia 6 2. F o r e s t S t r u c t u r e a t SQU .14 3. . U n d e r s t o r y V e g e t a t i o n a t SQU ........14 4. . S e t t i n g of the FUR S i t e 15 5. . Dense u n d e r s t o r y a t FUR 15 6. F o r e s t and U n d e r s t o r y S t r u c t u r e a t UEL ............ 19 7. S e t t i n g of the PIT S i t e .19 8 . . F o r e s t S t r u c t u r e a t BRI ........................... 20 9. U n d e r s t o r y S t r u c t u r e a t BRI 20 10..Setup Used t o M o n i t o r t h e Mi c r o e n v i r o n m e n t i n the F o r e s t at UEL .30 11. M i c r o e n v i r o n m e n t a l Data C o l l e c t e d from t h e S t a t i o n 1 Hygrothermograph , ......31 1 2 . . M i c r o e n v i r o n m e n t a l Data C o l l e c t e d from t h e S t a t i o n 2 Hygrothermograph .32 13. M i c r o e n v i r o n m e n t a l Data C o l l e c t e d from the S t a t i o n 3 Hygrothermograph 33 14..Setup Used t o C o l l e c t Stemflow from an Acer macrophyllum t r u n k a t UEL ..34 1 5 . . T o t a l Monthly P r e c i p i t a t i o n (June 1979-May 1980) at UEL ,., 3 5 16. .Bark R e l i e f of Acer l a c r o p h y l l u m .,. 44 i x 17. R e c i p r o c a l A v e r a g i n g O r d i n a t i o n of I n d i v i d u a l Trees a t SQU .. ...80 18. . R e c i p r o c a l Averaging O r d i n a t i o n o f I n d i v i d u a l T r ees a t FOR , 84 1 9 . . R e c i p r o c a l Averaging O r d i n a t i o n of I n d i v i d u a l T r ees a t UEL ........ .86 20. R e c i p r o c a l Averaging O r d i n a t i o n of I n d i v i d u a l Trees a t PIT , ,'.....90 2 1 . . R e c i p r o c a l Averaging O r d i n a t i o n o f I n d i v i d u a l T r e e s a t BRI , 92 2 2 . : R e c i p r o c a l Averaging O r d i n a t i o n o f I n d i v i d u a l Trees a t t h e 5 S i t e s 96 2 3 . . R e c i p r o c a l Averaging O r d i n a t i o n of t h e 24 H e i g h t -I n c l i n a t i o n C o m b i n a t i o n s , SQU 10 3 2 4 . . R e c i p r o c a l Averaging O r d i n a t i o n of t h e 24 H e i g h t -I n c l i n a t i o n C o m b i n a t i o n s , FUR ..105 2 5 . . R e c i p r o c a l Averaging O r d i n a t i o n of t h e 24 Height-I n c l i n a t i o n C o m b i n a t i o n s , UEL 107 26. R e c i p r o c a l Averaging O r d i n a t i o n of t h e 24 H e i g h t -I n c l i n a t i o n C ombinations, PIT 109 27. _ R e c i p r o c a l Averaging O r d i n a t i o n of t h e 24 H e i g h t -I n c l i n a t i o n C o m b i n a t i o n s , BRI .....111 28. O r d i n a t i o n {P-Co-A) o f Common E p i p h y t i c S p e c i e s a t SQU ... ... 120 2 9 . . O r d i n a t i o n (P-Co-A) of Common E p i p h y t i c S p e c i e s a t FUR ... „ . 122 3 0 . . O r d i n a t i o n (P-Co-A) of Common E p i p h y t i c S p e c i e s at UEL , 12 4 X 3 1 . . O r d i n a t i o n (P-Co-A) of Common E p i p h y t i c S p e c i e s a t PIT . . . . . . 1 2 5 3 2 . . O r d i n a t i o n (P-Co-A) of Common E p i p h y t i c S p e c i e s at BRI 1 2 7 3 3 . Mat o f Metaneckera m e n z i e s i i on Acer macrophyllum a t BRI . . . . 1 3 3 3 4 . . M a t of D e n d r o a l s i a a b i e t i n a on Acer macrophyllum a t BRI 1 3 3 3 5 . . C l u s t e r A n a l y s i s of Quadrats from SQU 1 4 9 3 6 . Two-dimensional D i r e c t O r d i n a t i o n of Quadrat Groupings a t SQU , . . . 1 5 0 3 7 . ..Cluster A n a l y s i s of Quadrats from FUR . . . . . . . . . . . . 1 5 4 3 8 . . T w o - d i m e n s i o n a l D i r e c t O r d i n a t i o n of Quadrat Groupings a t FUR . . 1 5 5 3 9 . . C l u s t e r A n a l y s i s of Quadrats from UEL . . . . . . . . . . . . 1 5 9 4 0 . . T w o - d i m e n s i o n a l D i r e c t O r d i n a t i o n of Quadrat Groupings a t UEL . . . 1 6 0 4 1 . . C l u s t e r A n a l y s i s of Quadrats from PIT ' . . . . . . . . . . . . . . 1 6 4 4 2 . . T w o - d i m e n s i o n a l D i r e c t O r d i n a t i o n of Quadrat Groupings a t PIT , . . . 1 6 5 4 3 . . C l u s t e r A n a l y s i s of Quadrats from BRI . . . . . . . . . . . . 1 6 9 4 4 . . T w o - d i m e n s i o n a l D i r e c t O r d i n a t i o n of Quadrat Groupings a t BRI • . . 1 7 0 4 5 . . S t r u c t u r e o f the E p i p h y t i c V e g e t a t i o n on Acer ffl§cro£hyllum a t SQU 1 8 7 4 6 . Dry Lower S i d e of t h e B o l e of Acer macro^hyllum at UEL . „ . 1 8 7 4 7 . . S t r u c t u r e o f t h e E p i p h y t i c V e g e t a t i o n on Acer x i macrophylluni a t UEL , 189 4 8. Mat of Neckera doug_la.sii on a Sma l l Tree of Acer macrophyllum a t BRI .. ...189 4 9. E p i p h y t i c S t r u c t u r e on 2 Large Trees of Acer macrophyllum a t BRI . , 190 50. „Hummocks of E p i p h y t i c B r y o p h y t e s on Acer m§ c, rPPbyllum a t BRI 190 51. . S l o u g h i n g - o f f o f E p i p h y t i c V e g e t a t i o n from Acer l ^ c r o p h y l l u m a t BRI ., 193 x i i ACKNOWLEDGEMENTS I am most g r a t e f u l t o my s u p e r v i s o r , Dr..G..E. B r a d f i e l d , f o r o f f e r i n g g u i d a n c e , c r i t i c i s m , and h e l p i n the da t a a n a l y s i s ; w i t h o u t h i s s u p p o r t t h i s t h e s i s would not have reached i t s p r e s e n t s t a g e . Many thanks t o Anna S c a g e l and C h r i s F l e t c h e r f o r p r o v i d i n g a s s i s t a n c e i n t h e f i e l d , and t o Rob Sc a g e l f o r i n f o r m a t i o n r e g a r d i n g some of the s t u d y s i t e s . I would l i k e t o thank Dr., H. Kimmins and h i s s t a f f of t e c h n i c i a n s f o r p r o v i d i n g f a c i l i t i e s and t e c h n i c a l e x p e r i t i s e f o r t h e a n a l y s i s of bark n u t r i e n t s . V a l u a b l e comments and c r i t i c i s m s r e g a r d i n g t h e ma n u s c r i p t and a n a l y s e s performed were p r o v i d e d by Dr. J..Maze, Dr. G..E. B r a d f i e l d , and T e r r y M c i n t o s h . Dave Crowe o f f e r e d v a l u a b l e a s s i s t a n c e i n c o m p u t a t i o n a l and t e c h n i c a l m a t t e r s r e l a t e d t o the computer. The f o l l o w i n g persons a i d e d i n t h e i d e n t i f i c a t i o n and v e r i f i c a t i o n o f c o l l e c t e d p l a n t m a t e r i a l : Dr._W.. B._ S c h o f i e l d , T r e v o r Goward, T e r r y M c i n t o s h , and Joop van V e l z e n . T h i s r e s e a r c h was funded by NSERC, t o whom I am g r a t e f u l . x i i i "The s u r r e n d e r t o Nature's i r r a t i o n a l , s t r a n g e l y c o n f u s e d f o r m a t i o n s produces i n us a f e e l i n g of i n n e r harmony w i t h the f o r c e s r e s p o n s i b l e f o r the s e phenomena. We soon f a l l prey t o the t e m p t a t i o n o f t h i n k i n g of them as b e i n g our own moods, our own c r e a t i o n s , and see t h e b o u n d a r i e s s e p a r a t i n g us from Nature begin t o q u i v e r and d i s s o l v e . We become a c q u a i n t e d w i t h t h a t s t a t e of mind i n which we a r e unable t o d e c i d e whether t h e images on our r e t i n a a r e t h e r e s u l t of i m p r e s s i o n s coming from w i t h o u t o r w i t h i n . Nowhere as i n t h i s e x e r c i s e can we d i s c o v e r to what e x t e n t we a r e c r e a t i v e , t o what e x t e n t our s o u l p a r t a k e s i n t h e c o n s t a n t c r e a t i o n o f t h e w o r l d . " - Hermann Hesse (1925) 1 CHAPTER 1 - INTRODUCTION A l t h o u g h f o r e s t ecosystems n o r m a l l y i n c l u d e an e p i p h y t i c component, s t u d i e s o f such ecosystems have u s u a l l y i g n o r e d t h e c o r r e s p o n d i n g e p i p h y t i c v e g e t a t i o n . T h i s i s p a r t i c u l a r l y t r u e i n n o r t h - w e s t e r n North America, even though e p i p h y t e s are o f t e n a c o n s p i c u o u s and i m p o r t a n t p a r t of the f o r e s t , ecosystems. In p a r t i c u l a r , l a r g e , e x t e n s i v e mats o f bryophyte v e g e t a t i o n are o f t e n found on t h e deciduous phorophyte Acer macrophyllum, e s p e c i a l l y i n humid e n v i r o n m e n t s . Because of i t s h i g h biomass, t h e e p i p h y t i c v e g e t a t i o n on t h i s t r e e s p e c i e s l i k e l y c o n t r i b u t e s s i g n i f i c a n t l y t o t h e t o t a l e n e r g e t i c s and p r o d u c t i v i t y of the ecosystem, and may be i m p o r t a n t i n n u t r i e n t c y c l i n g . E p i p h y t i c b r y o p h y t e and l i c h e n s p e c i e s g e n e r a l l y show a g r e a t e r s e n s i t i v i t y t o m i c r o e n v i r o n m e n t a l v a r i a t i o n t h a n does the a d j a c e n t v a s c u l a r v e g e t a t i o n . I t might be expected t h a t e p i p h y t i c v e g e t a t i o n responds t o complex m i c r o e n v i r o n m e n t a l g r a d i e n t s which a r e apparent on t h e t r e e b o l e . E p i p h y t i c v e g e t a t i o n may a l s o respond t o e n v i r o n m e n t a l v a r i a t i o n w i t h i n and between s i t e s . The re s p o n s e of e p i p h y t i c v e g e t a t i o n t o changes i n environment have o f t e n been i m p l i e d but u n t i l r e c e n t l y r a r e l y q u a n t i f i e d . O b j e c t i v e s of t h i s s t u d y a r e t o d e s c r i b e and a n a l y z e the na t u r e and s t r u c t u r e of the e p i p h y t i c v e g e t a t i o n on the lower p a r t s of the b o l e of t h e phorophyte Acer macrophyllum, and t o a n a l y s e the response of t h i s v e g e t a t i o n t o m i c r o e n v i r o n m e n t a l 2 g r a d i e n t s . W i t h i n - and b e t w e e n - s i t e v a r i a t i o n o f t h e . e p i p h y t i c v e g e t a t i o n i s a l s o s t u d i e d . An attempt i s made t o c o r r e l a t e t h i s v a r i a t i o n w i t h e n v i r o n m e n t a l f a c t o r s which a r e t h o u g h t t o i n f l u e n c e e p i p h y t i c d i s t r i b u t i o n s . A l s o , s p e c i e s i n t e r a c t i o n s , p a r t i c u l a r i l y t h e i r a s s o c i a t i o n s and i n t e r r e l a t i o n s h i p s , are a n a l y z e d and d i s c u s s e d . F i n a l l y , e p i p h y t i c community-types are d e f i n e d and c h a r a c t e r i z e d . 3 CHAPTER 2 - STUDY AREAS •ns of the major o b j e c t i v e s o f t h i s study i s t o examine the d i f f e r e n c e s i n e p i p h y t i c v e g e t a t i o n on Acer M c r o p h y l l u m between s i t e s . F i v e s i t e s were chosen f o r i n t e n s i v e s a m p l i n g , and were 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 c e s i n c l i m a t e and v a s c u l a r v e g e t a t i o n which a r e thought t o have some i n f l u e n c e on the e p i p h y t e s . . Areas were chosen o n l y . i f t h e s t a n d of t r e e s appeared t o be w e l l d e v e l o p e d , and i f the f o r e s t i t s e l f appeared not. t o have been e x t e n s i v e l y d i s t u r b e d i n r e c e n t y e a r s . Only r e a d i l y a c c e s s i b l e s i t e s were sampled i n t h e p r e s e n t s t u d y . A l l s i t e s a r e l o c a t e d w i t h i n t h e C o a s t a l Western Hemlock b i o g e o c l i m a t i c zone w i t h t h e e x c e p t i o n o f the U n i v e r s i t y Endowment Lands (UEL) s i t e , which i s l o c a t e d i n the C o a s t a l Douglas F i r zone ( K r a j i n a 1959). L o c a t i o n A l l s i t e s are l o c a t e d on t h e mainland of so u t h - w e s t e r n B r i t i s h Columbia ( F i g u r e 1). The f o l l o w i n g i s a b r i e f d e s c r i p t i o n o f each o f t h e s i t e s . The t h r e e - l e t t e r a b b r e v i a t i o n f o r each s i t e w i l l be used i n a l l subseguent d i s c u s s i o n s . Sjuamish R i v e r F l p p d p l a i n _ISO.U)_ l a t . 49°50'N l o n g . 123°13'W e l e v a t i o n = 34m.. T h i s s i t e i s l o c a t e d on the Sguamish R i v e r , about 14.5 km 4 from the mouth of t h e r i v e r a t Howe Sound. The n e a r e s t c l i m a t e s t a t i o n i s a t Sguamish, about 14.5 km south of the s i t e . . F u r r y Creek _[FUR]_ l a t . 49°35«N l o n g . 123°13«W e l e v a t i o n = 5m. L o c a t e d i n the l o w - l y i n g f l o o d p l a i n o f F u r r y Creek which j u t s i n t o t h e waters of Howe Sound, t h i s s i t e i s d i s t i n c t l y m a r i t i m e . . The n e a r e s t c l i m a t e s t a t i o n i s a t the town of B r i t t a n i a Beach 4.8 km n o r t h o f t h e s i t e . H.Q.iy.§£sity_ Endowment Lands _£0EL}_ lat..49°14'N long..123°14'W e l e v a t i o n = 30m.. Another m a r i t i m e s i t e , t h i s a r e a i s l o c a t e d above the c l i f f s o v e r l o o k i n g the S t r a i t of G e o r g i a , j u s t west o f the c i t y of Vancouver. The s i t e i s l o c a t e d on t h e F r a s e r R i v e r f l o o d p l a i n . Vancouver UBC, the n e a r e s t c l i m a t e s t a t i o n , i s l o c a t e d 2.4 km no r t h - w e s t of t h e s i t e . P i t t R i v e r F l o o d p l a i n JPIT1 l a t . .49°20"N l o n g . . 122°39«W e l e v a t i o n = 30m.. T h i s s i t e i s l o c a t e d on t h e west bank of the P i t t R i v e r (at Fox R e a c h ) , near the mouth of Munro Creek, and c l o s e t o P i t t Lake.. The a r e a l i e s a t the base o f a s t e e p mountain s l o p e which r i s e s t o the n o r t h and west. The n e a r e s t c l i m a t e s t a t i o n i s P i t t P o l d e r , about 4.0 km s o u t h - e a s t o f t h e s i t e . 5 B r i d a l K e i l F a l l s 1BRI]_ l a t . . 4 9 °11•N l o n g . .121°45«W e l e v a t i o n = 76 m.. T h i s s i t e i s l o c a t e d on t h e n o r t h - f a c i n g l o w e r s l o p e s of Cheam Peak,, a l o n g the F r a s e r R i v e r f l o o d p l a i n , near A g a s s i z . The n e a r e s t c l i m a t e s t a t i o n i s a t A g a s s i z , 8.8 km n o r t h o f t h e s i t e . C l i m a t e The moderate c l i m a t e of t h e s t u d y a r e a s i s i n f l u e n c e d by two major f a c t o r s : t h e p r o x i m i t y o f the P a c i f i c Ocean, which g i v e s t h e r e g i o n i t s d i s t i n c t l y m i l d c l i m a t e , and the Coast M o u n t a i n s , which r e a c h above 1800 m and c r e a t e an area of h i g h r a i n f a l l a l o n g the c o a s t . C l i m a t e d a t a (from Environment Canada 1970) f o r t h e s t a t i o n s p r e v i o u s l y mentioned i s g i v e n i n T a b l e s 1 and 2. Temperature d a t a f o r the s i t e s a r e s i m i l a r , a l t h o u g h t h e more m a r i t i m e s i t e s appear t o be s l i g h t l y m i l d e r i n the w i n t e r . A l s o , l o w e s t mean monthly te m p e r a t u r e s were r e c o r d e d a t SQU. The c o l d e s t mean monthly t e m p e r a t u r e o c c u r s i n January and i s above f r e e z i n g a t a l l s i t e s ; t h e warmest mean monthly temperature ( J u l y ) does not exceed 19°C. P r e c i p i t a t i o n data f o r t h e 5 s i t e s shows t h a t UEL i s t h e d r i e s t s i t e . Of the o t h e r s i t e s , BRI r e c e i v e s l e s s p r e c i p i t a t i o n than t h e o t h e r s . . The PIT s i t e has t h e h i g h e s t annual p r e c i p i t a t i o n . The t a b l e s a l s o i n d i c a t e t h a t p r e c i p i t a t i o n a t a l l s i t e s i s h i g h e s t i n t h e w i n t e r months: from 70 t o 75% o f t h e annual p r e c i p i t a t i o n o c c u r s between October and March. Figure 1. Location of the study s i t e s i n south-western B r i t i s h Columbia. E l e v a t i o n a l contours ( i n feet above sea le v e l ) are also shown. 7 Mean Monthly Temperature(°C) J F M A M J J A S 0 N D SQU 0.4 3.4 5.1 8.4 12.1 14.5 16.8 16.4 13.8 9.6 4.9 2.2 FUR 1.9 4.2 5.5 8.8 13.1 16.0 18.5 17.8 14.9 10.0 5.8 3.3 UEL 2.8 4.7 5.9 8.6 12.0 14.9 17.1 16.8 14.5 10.4 6.3 4.1 PIT 1.9 4.2 5.4 8.4 12.3 15.4 17.2 16.8 14.2 9.9 5.5 3.3 BRI 1.2 4.5 6.3 9.6 13.2 15.8 18.0 17.7 15.4 10.9 6.1 3.1 Mean Monthly Total P r e c i p i t a t i o n (mm) J F M A M J J A S 0 N D SQU 288.3 216.9 168.9 140.2 71.9 68.8 54.1 53.1 120.1 273.8 283.2 322.1 FUR 264.7 200.4 182.1 145.8 88.9 73.2 55.6 67.6 119.1 277.1 277.6 311.2 UEL 169.2 131.6 101.3 68.1 52.8 48.0 32.0 48.0 67.3 149.9 166.6 195.1 PIT 304.5 244.1 184.2 155.7 99.6 92.7 51.6 77.7 125.0 273.3 305.1 347.2 BRI 214.6 170.9 145.3 115.6 80.0 76.2 47.8 59.9 105.4 193.0 203.7 235.2 Mean Number of Days of Measureable P r e c i p i t a t i o n J F M A M J J A S 0 N D SQU 18 15 16 15 11 9 7 9 10 18 19 20 FUR 19 16 17 15 12 11 7 9 10 17 19 21 UEL 20 16 17 14 10 9 6 9 10 16 19 22 PIT 21 17 18 17 12 12 7 10 11 17 19 22 BRI 18 16 17 16 13 13 8 10 12 17 19 21 Table 1. Climate data f o r the 5 study s i t e s (from Environment Canada 1970). SQU FUR UEL PIT BRI Daily Temp. (°c) 8.9 10.0 9.8 9.6 10.2 Total Precip.(mm) 2061 2063 1230 2261 1648 Snowfall (mm) 1455 782 490 772 846 No. of days with Measureable Rain 155 165 163 176 173 No. of days with Measureable Snow 14 12 9 8 14 No. of days with Measureable Precip. 167 173 168 163 180 Table 2. Climate data (yearly means, 1941-1970) f o r the 5 study s i t e s (from Environment Canada 1970). SQU FUR UEL PIT BRI Athyrium filix-femina (L.) Roth. 48.8 31.4 0.0 0.0 9.9 Polystichura munitum (Kaulf.) Presl var. munitum 1.9 45.0 25.1 29.0 47.9 Dryopteris austriaca (Jacq.) Woynar 0.0 12.0 6.6 2.8 2.8 Acer circinatum Pursh 13.1 0.0 0.0 27.5 0.0 Sambucus racemosa L. var. arborescens (T. & G.) Gray 29.5 1.9 7.0 0.8 4.5 Rubus spectabilis Pursh 32.3 52.6 21.3 39.5 2.6 Rubus ursinus Cham. & Schlecht. 0.0 0.0 5.5 0.0 0.0 Rubus parviflorus Nutt. 22.5 0.0 16.9 0.0 4.5 Oplopanax horridus (Smith) Miq. 3.1 0.0 0.0 0.0 15.1 Symphoricarpos albus (L.) Blake 0.0 0.0 23.4 0.0 0.0 Ribes lacustre (Pers.) Poir. 0.0 0.0 0.0 0.0 4.1 Maianthemutn dilatatum (Wood) Nels. & Macbr. 6.0 7.0 0.0 0.0 4.5 Disporum smithii (L.) Desf. 12.5 0.0 0.0 0.0 0.4 Urtica dioica L. var. l y a l l i i (Wats.) Hitchc. 21.5 0.0 0.0 0.0 0.0 T i a r e l l a t r i f o l i a t a L. var. t r i f o l i a t a 4.4 5.9 1.0 0.0 0.0 Achlys t r i p h y l l a (Smith) DC. 0.0 0.0 0.0 0.0 2.7 Lactuca muralis (L.) Fresen. 1.5 0.0 1.6 0.0 0.0 Smilacina racemosa (L.) Desf. 1.9 1.2 0.0 0.0 1.9 Table 3. Mean percent cover values of woody and herbaceous vegetation at the 5 study s i t e s . SQU FUR UEL PIT BRI Acer macrophyllum 30.35 (70.0) 46.48 (30.0) 44.52 (50.0) 37.58 (62.5) 42.80 (35.0) Alnus rubra 6.77 (22.0) 6.22 (15.0) - 6.40 (16.7) 1.89 (7.5) Tsuga heterophylla 1.54 (8.0) 15.70 (45.0) 3.69 (10.0) 1.04 (12.5) 15.68 (20.0) Thuja p l i c a t a - 26.24 (10.0) 14.58 (27.5) 5.82 (8.3) 26.80 (35.0) Pseudotsuga menziesii — — 9.55 (12.5) -5.59 (2.5) Total 2 Dominance (m /ha) 38.66 94.64 72.34 50.84 92.76 Stand Density (trees/ha) 235 269 341 276 396 Table 4. Dominance (m /ha) and density (expressed as a percent, values i n brackets) of trees at the 5 study s i t e s . Total dominance and stand density are also shown. 11 P r e c i p i t a t i o n i s l o w e s t d u r i n g the warmest months (June, J u l y , and August) a t a l l s i t e s . . A n n u a l s n o w f a l l i s low at a l l s i t e s , and i s g r e a t e r a t SQU than t h e o t h e r s i t e s . A l t h o u g h the t o t a l amount of p r e c i p i t a t i o n d i f f e r s , t h e number of days of measureable p r e c i p i t a t i o n i s s i m i l a r a t a l l s i t e s , as i s i t s d i s t r i b u t i o n throughout t h e y e a r . l 6 g _ e t a t i o n at t h e S i t e s Because i t was f e l t t h a t the n a t u r e of the f o r e s t v e g e t a t i o n i s i m p o r t a n t t o t h e e p i p h y t e s because o f i t s i n f l u e n c e on the f o r e s t m i c r o c l i m a t e , an attempt was made t o c h a r a c t e r i z e the u n d e r s t o r y and t r e e v e g e t a t i o n a t each of the s i t e s . Tree d e n s i t y and dominance were a n a l y z e d u s i n g the p o i n t -c e n t e r e d g u a r t e r method as' o u t l i n e d i n P h i l l i p s (1951) and Mueller-Dombois and E l l e n b e r g (1974).. Two p a r a l l e l t r a n s e c t s were e s t a b l i s h e d , w i t h 5 p o i n t s a l o n g each t r a n s e c t , so t h a t a t o t a l of 40 t r e e s were a n a l y z e d . Two 1 meter sguare g u a d r a t s were p l a c e d near each p o i n t p o s i t i o n and the u n d e r s t o r y and shrub v e g e t a t i o n was a n a l y z e d by e s t i m a t i n g p e r c e n t c o v e r w i t h i n the g u a d r a t s . . P l a n t s which were not r e a d i l y i d e n t i f i a b l e i n t h e f i e l d were c o l l e c t e d and brought back t o the l a b o r a t o r y . Nomenclature f o r the v a s c u l a r p l a n t s f o l l o w s H i t c h c o c k and C r o n g u i s t (1973), f o r t h e mosses, S c h o f i e l d (1976), and f o r the h e p a t i c s , S t o t l e r and C r a n d a l l - S t o t l e r (1979). .Nomenclature f o r the l i c h e n s g e n e r a l l y f o l l o w s Hale and C u l b e r s o n (1970); however, i n ca s e s where r e c e n t t r e a t m e n t s are a v a i l a b l e , the c u r r e n t l y a c c e p t e d name has been used. R e s u l t s from t h e s a m p l i n g of t h e u n d e r s t o r y and shrub 12 l a y e r s a r e shown i n T a b l e 3 {only s p e c i e s which o c c u r r e d i n a t l e a s t 4 q u a d r a t s a t a g i v e n s i t e a r e i n c l u d e d ) . . Dominance and d e n s i t y v a l u e s f o r t r e e s at each of t h e s i t e s , d e r i v e d from the p o i n t - c e n t e r e d q u a r t e r a n a l y s e s , a r e shown i n T a b l e 4. The f o l l o w i n g summarizes t h e s e t a b l e s and d i s c u s s e s each of t h e s i t e s i n somewhat g r e a t e r d e t a i l . G e o l o g i c a l i n f o r m a t i o n i s t a ken from Mathews (1968). I n f o r m a t i o n on s o i l s i s from V a l e n t i n e e t a l . _ (1978) and from s o i l p i t s at each s i t e . . SQU T h i s s i t e has t h e lowest t o t a l t r e e d e n s i t y and dominance of a l l t h e s i t e s s t u d i e d * The f o r e s t i n t h i s r e g i o n i s f a i r l y e x t e n s i v e , however, w i t h few l a r g e c l e a r e d areas i n the s u r r o u n d i n g r e g i o n . The dominant t r e e a t t h e s i t e i s Acer macrophyllum ( F i g u r e 2) . Trees of t h i s s p e c i e s vary from 20 t o 25 m i n h e i g h t , w i t h an average DBH of 550 mm.. B r a n c h i n g on most of t h e s e t r e e s b e g i n s at a h e i g h t of 10-12 m above the ground.. Other t r e e s p e c i e s a t t h e s i t e i n c l u d e A l n u s r u b r a and Tsuga h e t e r o p h y l l a ; Thjaja p l i c a t a o c c u r s s p o r a d i c a l l y . Most of the l a r g e r c o n i f e r s a t t h e s i t e have been f e l l e d ; s t a n d i n g c o n i f e r s are g e n e r a l l y younger t r e e s about 10 m t a l l . . A c e r c i r c i n a t u m o c c u r s s c a t t e r e d i n t h e u n d e r s t o r y . The shrub l a y e r i s very dense, p r o b a b l y because o f t h e r e l a t i v e openness of the s i t e , and the l a c k of mature c o n i f e r s i n t h e canopy. The dominant shrub i s Rubus s p e c t a b i l i s , which forms dense t h i c k e t s t o 2.5 m h i g h ( F i g u r e 3) .. Other shrub s p e c i e s i n c l u d e Sambucus racemosa and Rubus 13 Ea.£Zi£i2£il§ I 0_pl ojaanax h o r r i d u s i s a l s o o c c a s i o n a l l y e n c o u n t e r e d . . The f e r n A t h y r i u m f e l i x - f e m i n a i s common i n many of th e more open a r e a s ; i n d r i e r r e g i o n s , P o l y s t i c h u m muni turn may occur..The herbaceous l a y e r i n c l u d e s Disporum s m i t h i i , S m i l a c i n a racemosa, Mianthemum d i l a t a t u m , U r t i c a d i o i c a v a r . l y a l l i i , D i c e n t r a f ormosa, Montia s i b i r i c a , T i a r e l l a t r i f o l i a t a , and C i r c a e a a l p i n a . F o r e s t - f l o o r b r y o p h y t e s a re not common and are g e n e r a l l y r e s t r i c t e d t o r o t t i n g wood.. S p e c i e s i n c l u d e £l§3.i21SiiJJ i n s i g _ n e , Rhyt i d i a d e l p h u s l o r e us, Rhi zo mnium 3 l a b r e s c e n s , and S t o k e s i e l l a oregana. The s i t e appears t o be h y g r i c . The s o i l i s damp even i n the summer, and s t a n d i n g water may accumulate i n the w i n t e r and s p r i n g . S o i l s i n t h e a r e a a r e f e r r o - h u m i c p o d z o l s . A s o i l p i t a t th e s i t e showed t h e s o i l l a y e r t o c o n s i s t of a l l u v i a l d e p o s i t s of sand a l t e r n a t i n g w i t h t h i n bands of c l a y , and o v e r l a i n w i t h an o r g a n i c l a y e r 15-20 cm i n dep t h . G e o l o g i c a l l y the r e g i o n i s c h a r a c t e r i z e d by r e c e n t l y d e p o s i t e d a l l u v i a l m a t e r i a l . The s i t e i s a d j a c e n t t o a g r a v e l l o g g i n g r o a d . V e g e t a t i o n i n the ar e a i s c o a t e d w i t h d u s t produced by p a s s i n g v e h i c l e s . T h i s may be an i m p o r t a n t n u t r i e n t s o u r c e f o r the e p i p h y t i c v e g e t a t i o n (Barkman 1958).. FUR T h i s s i t e has t h e h i g h e s t t o t a l t r e e dominance of a l l those s t u d i e d , but a r e l a t i v e l y low s t a n d d e n s i t y . The f o r e s t i n the a d j a c e n t r e g i o n s i s f a i r l y e x t e n s i v e , but the a r e a i m m e d i a t e l y Figure 2. Forest structure at SQU, showing Acer macrophyllum (center) and Alnus rubra ( l e f t ) . Figure 3. Understory vegetation at SQU. The dominant shrub i s Rubus s p e c t a b i l l s . Note the r e l a t i v e openness of the f o r e s t . 15 Figure 4. Setting of the FUR s i t e . The s i t e i t s e l f i s located on the coastal fl o o d p l a i n near the center of the f i g u r e . Note the regions of disturbance i n the foreground and at the far l e f t . Figure 5. An area of dense understory at FUR; dominant species include Rubus s p e c t a b i l i s and Sambucus  racemosa. Note the high density of the f o r e s t . 16 s u r r o u n d i n g the s i t e i s open: t o the west i s t h e ocean, w h i l e t h e a r e a s t o the s o u t h and e a s t o f t h e s i t e have been l a r g e l y c l e a r e d o f v e g e t a t i o n ( F i g u r e 4 ) . . The f o r e s t here i s a mature mixed c o n i f e r o u s - d e c i d u o u s s t a n d dominated by Acer macrophyllum. Thuja p l i c a t a , and Tsuga b & t e r o p h y l l a . . Specimens of JU macrophyllum are t a l l (30-35 m) and l a r g e (mean DBH of 650 mm), and t h e b o l e s are f r e e of branches f o r about t w o - t h i r d s t h e i r l e n g th..The upper branches produce a narrow c e n t r i p e t a l crown which competes w i t h t h e mature c o n i f e r s f o r l i g h t . Many of the specimens of beteropjvy 11a are younger t r e e s 5-10 m i n h e i g h t , i n some p l a c e s f o r m i n g dense stands beneath t h e upper canopy. In areas where t h e s e o c c u r , l i g h t l e v e l s may be v e r y low. P i c e a s i b c h e n s i s o c c u r s i n the s t u d y a r e a , b u t o n l y near t h e s h o r e l i n e . A l n u s r u b r a and Pseudotsuga. m e n z i e s i i are s p o r a d i c . The canopy a t the s i t e i s very dense throughout the y e a r , so t h a t l i t t l e d i r e c t l i g h t r e a c h e s t h e f o r e s t f l o o r . In consequence the u n d e r s t o r y i s g e n e r a l l y low-growing and s p a r s e ; t h e f e r n s P o l y s t i c h um munitum, D r y o p t e r i s a u s t r i a c a , and Athyrium f i l i x - f e m i n a a r e i m p o r t a n t components. I n a r e a s where s u n l i g h t r e a c h e s t h e • f o r e s t f l o o r dense s t a n d s of Rubus s p e c t a b i l i s and Sambucus racemosa (to 3 m i n h e i g h t ) o c c u r ( F i g u r e 5 ) . I n l o w - l y i n g a r e a s , t h e u n d e r s t o r y may be dominated by Sambucus racemosa, A._ f i l i x - f e m i n a , T i a r e l l a t r i f o l i a t a , Ui§Si4§mum d i l a t a t u m , and S m i l a c i n a racemosa . The f o r e s t f l o o r i s r i c h i n l i t t e r and r o t t i n g l o g s . On t h e s e l o g s , D r y o p t e r i s a u s t r i a c a and P o l y s t i c h u m munitum o f t e n o c c u r w i t h the b r y o p h y t e s £l§3iomnium i n s i g _ n e , R h y t i d i a d e lphus l o r e us, 17 L s u c o l e p i s m e n z i e s i i , P l a q i p t h e c i u m undulaturn, Hy_locomium s g l e n d e n s , Rhizomnium q l a b r e s c e n s , and S t o k e s i e l l a oreqana. S o i l s i n the area are h u m o - f e r r i c p o d z o l s . The study a r e a i t s e l f appears t o be b u i l t up of a l l u v i a l outwash from F u r r y Creek. A s o i l p i t showed the s o i l l a y e r t o c o n s i s t of a g r a v e l l y p o d z o l o v e r l a i n w i t h g r a v e l l y o r g a n i c m a t e r i a l about 30 cm deep. The nearby mountains are l a r g e l y g r a n i t i c ( J u r a s s i c t o l a t e C r e t a c e o u s ) . The f o r e s t a t t h i s s i t e i s r e l a t i v e l y dense, and t o t a l t r e e dominance i s f a i r l y h i g h (but l o w e r than at FUR or B R I ) . . The area i m m e d i a t e l y s u r r o u n d i n g the s i t e i s open o r d i s t u r b e d : t o the west l i e s the S t r a i t o f G e o r g i a , w h i l e f o r e s t i n the s u r r o u n d i n g a r e a i s c l e a r e d or e x t e n s i v e l y d i s t u r b e d . The f o r e s t c o n s i s t s of a mixed c o n i f e r o u s - d e c i d u o u s canopy dominated by Acer macrophyllum, Thuja p l i c a t a , Pseudotsuqa m e n z i e s i i , and Tsuqa h e t e r o p h y l l a (Figure 6 ) . Specimens of A. .macrophyllum are f a i r l y t a l l (20-25 m) w i t h l o n g s t r a i g h t b o l e s which branch about 15 m from the base t o form a narrow crown..Mean DBH of t h i s s p e c i e s i s 550 mm..Alnus r u b r a o c c u r s i n nearby a r e a s . In some a r e a s , a t r e e u n d e r s t o r y c o n s i s t i n g of s a p l i n g s of T._ h e t e r o p h y l l a and T._ p l i c a t a (to 10 m i n h e i g h t ) o c c u r s . The shrub l a y e r a t t h i s s i t e i s v a r i a b l e . I n more open a r e a s where d i r e c t l i g h t p e n e t r a t e s t o t h e f o r e s t f l o o r , s t a n d s of Rubus s p e c t a b i l i s , Rubus p a r y i f l o r u s , and Sambucus racemosa 18 o f t e n d e v e l o p . . Symphoricarpos aIbus may a l s o occur. .In more c l o s e d a r e a s , however, the f e r n s P o l y s t i c h u m muniturn and D r y o p t e r i s a u s t r i a c a are more common. Other shrubs which may a l s o o c c u r a t t h i s s i t e i n c l u d e Rubus u r s i n u s , Mahonia n e r v o s a , and R i b e s l a c u s t r e . Common herbs i n c l u d e Tolmiea m e n z i e s i i , T r i e n t a l i s l a t i f o l i a , Galium t r i f l o r u m , and L a c t u c a m u r a l i s . Plagipmnium i n s i g n e may a l s o occur on the f o r e s t f l o o r , and a l s o o c c u r s on r o t t i n g l o g s w i t h R h y t i d i a d e l p h u s l o r e u s , l i ^ a i o t h e c i u m undulatum, and S t p k e s i e l l a oregana. UEL appears t o be t h e d r i e s t h a b i t a t of t h o s e s t u d i e d . T h i s i s l i k e l y a r e f l e c t i o n of the lower a n n u a l p r e c i p i t a t i o n combined w i t h the r e l a t i v e l y h i g h degree of d i s t u r b a n c e o f nearby v e g e t a t i o n . S o i l s of the r e g i o n a re p r e d o m i n a n t l y humic g l e y s o l i c s . . A s o i l p i t r e v e a l e d a g r a v e l l y o r g a n i c l a y e r (15-40 cm deep) o v e r l y i n g a l a y e r of more sandy, g r a v e l l y g l e y s o l . G e o l o g i c a l l y , t h e area c o n s i s t s of Quaternary d e p o s i t s of g l a c i a l a l l u v i u m . . PIT T h i s s i t e has a low t r e e d e n s i t y and low t r e e dominance r e l a t i v e t o o t h e r s i t e s . The area s u r r o u n d i n g the st a n d i s g u i t e open ( F i g u r e 7 ) E x t e n s i v e marsh areas occur t o the s o u t h , and on the n o r t h s l o p e s t h e v e g e t a t i o n i s p o o r l y developed ( t h e t r e e s h a v i n g been r e c e n t l y f e l l e d ) . Thus, d e s p i t e t h e h i g h a n n u a l t o t a l p r e c i p i t a t i o n a t t h i s s i t e , t h e e p i p h y t i c v e g e t a t i o n i s l i k e l y s u b j e c t t o c o n s i d e r a b l e d e s i c c a t i o n ( e s p e c i a l l y d u r i n g t h e summer months) because of the openness of 19 Figure 6. Forest and understory structure at UEL. Trees shown include Tsuga heterophylla, Pseudotsuga menziesii, and Acer macrophyllum. Note the sparse understory. Figure 7. Setting of the PIT s i t e . Note the extensive open marshlands i n the background. The s i t e i t s e l f i s located at the center of the f i g u r e . Figure 8. Forest structure at BRI. The large trees are Acer macrophyllum; young trees of Thuja plicata are also shown. Figure 9 . Understory structure at BRI. Species include Polystichum munitum (center) and Oplopanax horridus (foreground). Note the high density of the forest. 21 the s u r r o u n d i n g l a n d s c a p e . The s i t e i s dominated by Acer raacrophyllum, a l t h o u g h A l n u s r u b r a also, o c c u r s and l a r g e specimens of Thuja p l i c a t a are o c c a s i o n a l l y e n c o u n t e r e d . Trees of JU macrophyllum are g e n e r a l l y 20-30 m i n h e i g h t , w i t h b r a n c h i n g b e g i n n i n g a t about 10-15 m from the base. They o f t e n form a more e x t e n s i v e , t h i c k crown than t h o s e found i n more c l o s e d c a n o p i e s (such as a t BRI and FUR).. Mean t r e e DBH i s 490 mm. The t r e e u n d e r s t o r y c o n s i s t s of t h i c k e t s of Acer c i r c i n a t u m ( t o 5 m i n h e i g h t ) and o c c a s i o n a l s a p l i n g s of T._ p l i c a t a and Tsuga h e t e r o p h y l l a (to 10 m h i g h ) . In most p l a c e s t h e canopy i s q u i t e open, a l l o w i n g f o r the development of a dense u n d e r s t o r y . Stands of Rubus s p e c t a b i l i s , up t o 3 m i n h e i g h t , o c c u r t h r o u g h o u t t h e s i t e ; o c c a s i o n a l s t a n d s o f Sambucus racemosa a l s o o c c u r . Herbaceous v e g e t a t i o n and f e r n s are b e s t developed i n a r e a s where R._ s p e c t a b i l i s t h i c k e t s a r e l e s s dense. Common s p e c i e s i n such a r e a s i n c l u d e E°iystic_hum muniturn and D r y o p t e r i s a u s t r i a c a ; T i a r e l l a t r i f o l i a t a and L a c t u c a m u r a l i s a l s o o c c u r . The moss Plagiomnium i n s i g n e o c c a s i o n a l l y o c c u r s on the f o r e s t f l o o r . . Other b r y o p h y t e s , p a r t i c u l a r l y B h y t i d i a d e l p h u s l o r e u s , Rhizomnium 9.1 a br esc ens, P l a g i o t heciujn und u l a turn, and Stoke s i e l l a oregana, o c c u r on r o t t i n g l o g s . S o i l s i n t h e r e g i o n are h u m o - f e r r i c p o d z o l i c s . . A s o i l p i t a t the s i t e showed the s o i l t o be very g r a v e l l y and r o c k y , and r i c h l y o r g a n i c . G e o l o g i c a l l y , the area appears t o be a l l u v i a l i n o r i g i n (outwash from the P i t t R i v e r ) . 22 BRI The f o r e s t a t t h i s s i t e has t h e h i g h e s t s t a n d d e n s i t y and a h i g h t o t a l t r e e dominance ( F i g u r e 8 ) . I t i s g e n e r a l l y w e l l d e v e l o p e d , a l t h o u g h t h e r e i s some d i s t u r b a n c e and c l e a r i n g ( f o r farmland) about a k i l o m e t e r away. The s i t e l i e s i n the c e n t e r o f an e x t e n s i v e f o r e s t which extends up t h e s l o p e s t o the s o u t h . The s i t e c o n s i s t s of a mixed c o n i f e r o u s - d e c i d u o u s " f o r e s t w i t h Acer macrpph^llum. Thuja p l i c a t a , and Tsug_a h e t e r o p h i l l a d o m i n a t i n g t h e canopy; Pseudotsuga m e n z i e s i i , Alnus r u b r a , and B e t u l a p a p y r i f e r a v a r . . commutata o c c u r s p o r a d i c a l l y . . A dense t r e e u n d e r s t o r y of s a p l i n g s o f T;_. h e t e r o p h y l l a and T._ p l i c a t a (to . 1 0 m i n h e i g h t ) i s found i n more open a r e a s a t the s i t e . These s a p l i n g s , which branch from about 1 m from the t r e e base, c r e a t e a d e e p l y shaded microenvironment near t h e f o r e s t f l o o r . The area i n which t h e s a m p l i n g was done has a very dense canopy of c o n i f e r s and A v macrophyllum, c r e a t i n g a d a r k , humid f o r e s t f l o o r environment. The f o r e s t f l o o r v e g e t a t i o n i s g e n e r a l l y s p a r s e , b e i n g dominated by t h e f e r n s P o l y s t i c h u m munitum and Athyrium f i l i x -f e m i n a ; D r y o p t e r i s a u s t r i a c a may a l s o o c c u r . I n more open a r e a s , s t a n d s o f Sambucus racemosa a r e o c c a s i o n a l l y e n c o u n t e r e d ; i n w e t t e r , seepage a r e a s , Oplopanax h o r r i d u s may o c c u r ( F i g u r e 9). F o r e s t - f l o o r b r y o p h y t e s are g e n e r a l l y r e s t r i c t e d t o r o t t i n g wood.. Common s p e c i e s i n c l u d e Plagiomnium i n s i ^ n e , P l a g i o t h e c i u m undulatum, Hylocomium s p l e n d e n s , S t o k e s i e l l a o reqana, S t o k e s i e l l a p r a e l o n g a v a r . . s t o k e s i i , R h y t i d i a d e l p h u s l o r e u s , i ^ c o l s s i s m e n z i e s i i , and Rhizpmnium g l a b r e s c e n s . 23 Of a l l t h e s i t e s s t u d i e d , BRI appears t o have the most humid mi c r o e n v i r o n m e n t i n t h e u n d e r s t o r y . . F a c t o r s such as the dense canopy, h i g h f o r e s t d e n s i t y , and p r o x i m i t y of t h e mountains t o the s o u t h combine t o c r e a t e a humid and c o o l f o r e s t even d u r i n g t h e summer months..It i s a l s o p o s s i b l e t h a t the s i t e r e c e i v e s more p r e c i p i t a t i o n than the A g a s s i z c l i m a t i c s t a t i o n i n d i c a t e s because of i t s c l o s e p r o x i m i t y t o t h e mountains. S o i l s i n t h e a r e a a r e h u m o - f e r r i c p o d z o l i c s . A s o i l p i t dug at t h e s i t e showed the s o i l t o c o n s i s t of an o r g a n i c l a y e r 20-30 cm deep o v e r l y i n g a g r a v e l l y , grey p o d z o l . G e o l o g i c a l l y t h e a r e a i s complex..The s i t e i t s e l f c o n s i s t s of Quaternary d e p o s i t s of F r a s e r R i v e r a l l u v i u m . The s l o p e s t o the south c o n s i s t of p r e -g r a n i t i c ( m i d - P a l e o z o i c t o T r i a s s i c ) metasediments and m e t a v o l c a n i c s . 24 CHAPTER 3 - EPIPHYTIC VEGETATION AND THE ENVIRONMENT Because of t h e i r p h y s i o l o g y and s m a l l s i z e , e p i p h y t e s ( p a r t i c u l a r i l y b r y o p h y t e s and l i c h e n s ) are g e n e r a l l y more s e n s i t i v e t o m i c r o e n v i r o n m e n t a l changes than a r e v a s c u l a r p l a n t s (Hoffman and K a z m i e r s k i 1969, S l a c k 1976, C u l b e r s o n 1955, Barkman 1958,1973). M i c r o e n v i r o n m e n t a l v a r i a t i o n i s a complex phenomenon m a n i f e s t e d by a number of f a c t o r s . E p i p h y t i c d i s t r i b u t i o n s on t r e e s might t h e r e f o r e be expected t o be c o r r e s p o n d i n g l y complex. Barkman (1958) has summarized the f a c t o r s t h a t may p o t e n t i a l l y i n f l u e n c e e p i p h y t e s and t h e i r d i s t r i b u t i o n . . More r e c e n t work has shown t h a t t h e i n f l u e n c e and i m p o r t a n c e of t h e s e f a c t o r s v a r i e s depending upon the a r e a s t u d i e d , t h e scope o f the s t u d y , and t h e t y p e of v e g e t a t i o n a n a l y z e d ( l i c h e n s or b r y o p h y t e s ) . . I n t h i s s e c t i o n , f a c t o r s thought t o be most i m p o r t a n t t o t h e d i s t r i b u t i o n and abundance of e p i p h y t e s on Acer macrophyllum are d i s c u s s e d . . T h i s i n f o r m a t i o n i s d e r i v e d from f i e l d o b s e r v a t i o n s and draws t o some e x t e n t from t h e c u r r e n t l i t e r a t u r e on t h e s u b j e c t . Z o n a t i o n JComplex M i c r o e n v i r o n m e n t a l G r a d i e n t s ^ Perhaps the most s t r i k i n g o b s e r v a t i o n t h a t can be made i n the f i e l d i s t h a t e p i p h y t i c v e g e t a t i o n appears t o be s e n s i t i v e t o two major g r a d i e n t s . . Barkman (1958) d i s c u s s e s t h e s e i n d e t a i l . V e r t i c a l z o n a t i o n (a h e i g h t g r a d i e n t ) can o f t e n be r e c o g n i z e d . D i f f e r e n c e s i n the e p i p h y t i c v e g e t a t i o n a l o n g an 25 e l e v a t i o n a l g r a d i e n t i s t h o u g h t t o r e f l e c t c o r r e s p o n d i n g i n c r e a s e s i n l i g h t i n t e n s i t y , wind, and e v a p o t r a n s p i r a t i o n as one p roceeds up the b o l e (Hosokawa et a l . . . 1964, Hosokawa and Odani 1957).. Bark f a c t o r s may a l s o change a l o n g t h i s g r a d i e n t ( B i l l i n g s and Drew 1938). I t has o f t e n been observed t h a t v e r t i c a l z o n a t i o n of e p i p h y t e s i s g r e a t e s t near the t r e e base where the m i c r o c l i m a t i c g r a d i e n t i s s t r o n g e s t (Sjogren 1961, Barkman 1 958) . H o r i z o n t a l z o n a t i o n can a l s o be r e c o g n i z e d . . D e p e n d i n g upon where t h e t r e e i s l o c a t e d , h o r i z o n t a l z o n a t i o n may be a m a n i f e s t a t i o n of one of two f a c t o r s (and l i k e l y both i n some c i r c u m s t a n c e s ) On exposed, i s o l a t e d t r e e s , and on t r e e s a t t h e f o r e s t f r i n g e , d i r e c t i o n o f e x p o sure may be an i m p o r t a n t f a c t o r . In the N o r t h e r n hemisphere, e p i p h y t e s n o r m a l l y show t h e i r b e s t development on the shaded n o r t h s i d e , where e v a p o t r a n s p i r a t i o n i s l o w e s t (Barkman 1958). . P r e v a i l i n g winds, which may blow p r e c i p i t a t i o n p r e f e r e n t i a l l y t o one s i d e of t h e b o l e , may have au o v e r r i d i n g e f f e c t , however. I n c l o s e d f o r e s t s where a dense canopy i s d e v e l o p e d , d i f f e r e n t f a c t o r s come i n t o p l a y . The e f f e c t o f e v a p o t r a n s p i r a t i o n becomes l e s s i m p o r t a n t s i n c e most of t h e i n c o m i n g l i g h t i s i n t e r c e p t e d by the f o r e s t canopy. In such s i t u a t i o n s , t r e e i n c l i n a t i o n i s f a r more i m p o r t a n t , s i n c e t h e upper s i d e of an i n c l i n e d b o l e w i l l r e c e i v e t h e b u l k of the p r e c i p i t a t i o n (Barkman 1958, P i k e e t a l . 1975, Rasmussen 1975). The l a t t e r two a u t h o r s demonstrated t h a t h o r i z o n t a l z o n a t i o n of e p i p h y t i c v e g e t a t i o n i s c o m p l e t e l y independent of a s p e c t but s t r o n g l y dependent on d i r e c t i o n of t r e e i n c l i n a t i o n i n c l o s e d f o r e s t s i t u a t i o n s . T h i s was found t o be the case i n t h e p r e s e n t 26 s t u d y . H o r i z o n t a l z o n a t i o n a l s o appears t o be g r e a t e s t on l a r g e r t r e e b o l e s . I t s h o u l d be noted t h a t t h e upper s i d e of the b o l e o f f e r s a somewhat l e s s p r e c a r i o u s h a b i t f o r t h e e s t a b l i s h m e n t of e p i p h y t i c b r y o p h y t e s ; t h i s i s e s p e c i a l l y t r u e of b a s a l l y -a t t a c h e d mat-forming s p e c i e s . 5i£§£t H a b i t a t F a c t o r s The v e r t i c a l ( e l e v a t i o n a l ) and h o r i z o n t a l ( i n c l i n a t i o n ) g r a d i e n t s a l r e a d y d i s c u s s e d a r e e n v i r o n m e n t a l l y complex, s i n c e they a r e i n f l u e n c e d by a number of e n v i r o n m e n t a l f a c t o r s of v a r y i n g i m p o r t a n c e (see W h i t t a k e r 1967). These e n v i r o n m e n t a l f a c t o r s are ' d i r e c t ' ; t h a t i s , t h e y can be measured and q u a n t i f i e d d i r e c t l y and i n d e p e n d e n t l y . The a n a l y s i s of e c o l o g i c a l g r a d i e n t s presupposes t h e complex and o f t e n s y n e r g i s t i c i n t e r a c t i o n o f d i r e c t h a b i t a t f a c t o r s . . The p h y t o s o c i o l o g i s t i s u s u a l l y most i n t e r e s t e d i n the s t u d y of complex e n v i r o n m e n t a l g r a d i e n t s t o which the s p e c i e s appear t o be r e s p o n d i n g . However, i n t e r e s t w i l l a l s o l i e i n t h e e l u c i d a t i o n of the most i m p o r t a n t f a c t o r s a c t i n g a l o n g th e g r a d i e n t i n a t t e m p t i n g t o answer s p e c i f i c q u e s t i o n s r e g a r d i n g the s e n s i t i v i t y of t h e s p e c i e s t o t h e s e f a c t o r s . D i r e c t h a b i t a t f a c t o r s can be d i v i d e d i n t o two major g r o u p s , p h y s i c a l and c h e m i c a l f a c t o r s . P h y s i c a l f a c t o r s i n c l u d e l i g h t , t e m p e r a t u r e , water, and bark d i f f e r e n c e s . The amount of l i g h t a v a i l a b l e t o e p i p h y t i c v e g e t a t i o n w i l l vary depending upon the n a t u r e of t h e canopy. In the p r e s e n t s t u d y , l i g h t may p l a y an i m p o r t a n t r o l e i n d e t e r m i n i n g e p i p h y t i c d i s t r i b u t i o n s . L i g h t 27 i n f l u e n c e s p h o t o s y n t h e t i c r a t e ( p h y s i o l o g i c a l ) as w e l l as e v a p o r a t i o n and e v a p o t r a n s p i r a t i o n r a t e s ( r a t e of d r y i n g ) . Temperature may be an i m p o r t a n t f a c t o r when comparing e p i p h y t i c v e g e t a t i o n over a wide range. I n the p r e s e n t s t u d y , i t i s p r o b a b l y not an i m p o r t a n t f a c t o r . Water as a f a c t o r i s i m p o r t a n t f o r a number of r e a s o n s . . B r y o p h y t e s and l i c h e n s , which l a c k r o o t systems, must absorb water d i r e c t l y from the atmosphere ( u s u a l l y i n the form of r a i n f a l l ) . Thus t h e amount and s e a s o n a l d i s t r i b u t i o n of p r e c i p i t a t i o n i s i m p o r t a n t t o the e p i p h y t e s . A l s o , because e p i p h y t e s grow on an a l m o s t v e r t i c a l s u b s t r a t e which does not r e t a i n o r accumulate water as r e a d i l y as s o i l , t h e e p i p h y t i c microenvironment i s p o t e n t i a l l y more x e r i c than t h a t of t h e f o r e s t f l o o r . Thus, such f a c t o r s as a t m o s p h e r i c h u m i d i t y (which a f f e c t s d e s i c c a t i o n r a t e ) , and f i e l d m o i s t u r e and w a t e r - h o l d i n g c a p a c i t y of bark a r e very i m p o r t a n t f a c t o r s i n e p i p h y t e e c o l o g y . Other bark f a c t o r s such as r e l i e f , r a t e of s c a l i n g , and hardness may a l s o be i m p o r t a n t t o the e p i p h y t i c v e g e t a t i o n . 0 C h e m i c a l f a c t o r s i n c l u d e n u t r i e n t l e v e l s and pH of t h e bark s u b s t r a t e . These f a c t o r s are thought t o be i m p o r t a n t , e s p e c i a l l y i n e x p l a i n i n g d i f f e r e n c e s i n e p i p h y t i c v e g e t a t i o n on d i f f e r e n t t r e e s p e c i e s ( J e s b e r g e r and Sheard 1973, B e a l s 1965, Barkman 1958, S j o g r e n 1961). The bark of Acer macrophyllum i s d i s c u s s e d i n d e t a i l i n t h e n e x t c h a p t e r . 28 S t u d i e s o f D i r e c t H a b i t a t F a c t o r s a t UEL The measurement of e n v i r o n m e n t a l f a c t o r s n e c e s s a r i l y i n v o l v e s much ti m e and e f f o r t , but i n o r d e r t o p r o p e r l y a n a l y z e the e c o l o g i c a l i m p o r t a n c e o f microenvironment t o e p i p h y t i c v e g e t a t i o n , d e t a i l e d a n a l y s e s a r e n e c c e s s a r y . I n t h i s s e c t i o n , e x p e r i m e n t s s e t up t o measure t e m p e r a t u r e , h u m i d i t y , and p r e c i p i t a t i o n (amount of stemflow and t h r o u g h f a l l ) f o r a f u l l year a r e d e s c r i b e d and r e s u l t s p r e s e n t e d , a l l e x p e r i m e n t s were un d e r t a k e n near the UEL s i t e ; u n f o r t u n a t e l y , o t h e r s i t e s were not s t u d i e d because they were not as r e a d i l y a c c e s s i b l e . . L i g h t , which i s d i f f i c u l t t o measure and e x t r e m e l y v a r i a b l e between ar e a s beneath a f o r e s t canopy, was not measured. Temperature and Humidity Three c l i m a t i c s t a t i o n s were e s t a b l i s h e d i n a p r o t e c t e d , f e n c e d - o f f a r e a on /the U n i v e r s i t y Endowment Lands b e l o n g i n g t o the UBC B o t a n i c a l Garden..The s i t e i s r e l a t i v e l y u n d i s t u r b e d and s i m i l a r t o t h e UEL s i t e d e s c r i b e d e a r l i e r . The t h r e e s t a t i o n s were l o c a t e d a p p r o x i m a t e l y 50 m a p a r t . at each s t a t i o n , p l a t f o r m s were b u i l t on the n o r t h s i d e of a t r e e o f Acer ffi^C-LP-EiiY. 1 iiiJSr o n e a - t the t r e e base and a n o t h e r 4.5 m up t h e t r e e . _ 0 n each p l a t f o r m was p l a c e d a Fuess hygrothermograph housed w i t h i n a w h i t e S t e v e s t o n s c r e e n ( F i g u r e 10).. Temperature and h u m i d i t y were monitored c o n t i n u o u s l y from June 1979 t o May 1980..For each day, maximum and minimum temp e r a t u r e and h u m i d i t y r e a d i n g s were r e c o r d e d . Mean d a i l y temperature and h u m i d i t y were computed by a v e r a g i n g the maximum and minimum v a l u e s . From th e s e 29 v a l u e s monthly means were computed. The t h r e e s t a t i o n s were chosen t o m o n i t o r m i c r o e n v i r o n m e n t a l c o n d i t i o n s w i t h i n t h e f o r e s t . _ S t a t i o n 1 i s about 30 m from the f o r e s t edge. S t a t i o n 2 i s l o c a t e d f u r t h e r i n the woods; S t a t i o n 3 i s i n an area s i m i l a r t o S t a t i o n 2, but t h e lower l e v e l hygrothermograph i s l o c a t e d near a r o t t i n g l o g . The Fuess hygrothermograph p r o v i d e s a c o n t i n u o u s i n k e d c h a r t of r e l a t i v e h u m i d i t y and t e m p e r a t u r e . H u m i d i t y v a l u e s were o c c a s i o n a l l y checked f o r a c c u r a c y u s i n g an Assman psychrometer; t e m p e r a t u r e was checked u s i n g a b u l b thermometer. C o t t o n (1970) d i s c u s s e s i n d e t a i l t h e e r r o r s i n h e r e n t i n measuring h u m i d i t y u s i n g a hygrothermograph. Computed monthly means o f t e m p e r a t u r e and h u m i d i t y f o r each of t h e 3 s i t e s a r e shown i n F i g u r e s 11-13.. Temperature d i f f e r e n c e s between the two l e v e l s were found to be n e g l i g i b l e and are not shown. However, d i f f e r e n c e s i n h u m i d i t y were a p p a r e n t . At a l l t h e s t a t i o n s , the h u m i d i t y was found t o be h i g h e r (by 2-5%) a t the t r e e base throughout the year. I t would appear t h a t a h u m i d i t y g r a d i e n t e x i s t s upwards from the f o r e s t f l o o r , a c o n c l u s i o n a l s o reached by G e i g e r (1966). The g r a d i e n t appears t o be s t r o n g e s t at S t a t i o n 3; t h e h i g h h u m i d i t y l e v e l s a t t h e t r e e base a t t h i s s t a t i o n p r o b a b l y r e f l e c t the p r o x i m i t y of the i n s t r u m e n t t o a r o t t i n g l o g . Humidity measures a t S t a t i o n 1 ( l o c a t e d n e a r e r the f o r e s t edge) are s l i g h t l y l o w e r than t h e o t h e r s t a t i o n s . R e l a t i v e h u m i d i t y i s h i g h throughout the y e a r , v a r y i n g from 70 - 90%. The t h r e e s t a t i o n s show the same monthly t r e n d s i n h u m i d i t y v a l u e s . O v e r a l l y e a r l y t r e n d s r e f l e c t s e a s o n a l changes Figure 10.. Setup used to monitor the micro-environment (temperature and humidity) i n the forest at UEL. Hygrothermographs are housed within the white Steveston screens. .31 J J A S O N D J F M A M Figure 11. Microenvironmental data collected from the Station 1 hygrothermographs. Bars indicate mean monthly temperature. Mean monthly humidity at the tree base ( s o l i d l i n e ) and 4.5 m up the bole (dashed l i n e ) are also shown. Data was collected from June 1979 - Hay 1980. 32 20n o LLI Dd 3 15H 1 C H < LU LU O H J J A S O N D J F M A M MOO h 8 0 •60 I LU > f-40 H LU or h20 0 Figure 12. Microenvironmental data c o l l e c t e d from the Station 2 hygrothermographs. Bars indic a t e mean monthly temperature. Mean monthly humidity at the tree base ( s o l i d l i n e ) and 4.5 m up the bole (dashed l i n e ) are also shown. Data was c o l l e c t e d from June 1979 - May 1980. 33 20- , ( J o LLI or Z> I— < cc UJ CL LLI 1CM 5H O H -5' J J A S O N D J F M A M r 1 0 0 h 4 0 H20 0 Figure 13. Microenvironmental data collected from the Station 3 hygrothermographs. Bars indicate mean monthly temperature. Mean monthly humidity at the tree base (solid line) and A.5 m up the bole (dashed line) are also shown. Data was collected from June 1979 - May 1980. o >-•60 Q 7. Ld > LLI Q: Figure 14. Setup used to c o l l e c t stemfl from an Acer macrophyllum trunk at UEL. 34 H J J A S O N D J F M A M Figure 15. T o t a l monthly p r e c i p i t a t i o n (June 1979 -May 1980) as recorded near the UEL s i t e . S o l i d l i n e i n d i c a t e s stemflow, dashed l i n e canopy t h r o u g h f a l l . 36 i n p r e c i p i t a t i o n and the n a t u r e of t h e canopy and u n d e r s t o r y . H u m i d i t y i s l o w e s t i n A p r i l , i n c r e a s i n g from May through September; t h i s i n c r e a s e can be a t t r i b u t e d t o the development of t h e u n d e r s t o r y v e g e t a t i o n ( i n c r e a s i n g e v a p o t r a n s p i r a t i o n ) and canopy ( c r e a t i n g a h u m i d i t y b u i l d u p below i t ) . . H i g h h u m i d i t y i n w i n t e r i s a t t r i b u t a b l e t o i n c r e a s e d p r e c i p i t a t i o n and c l o u d i n e s s . The drop i n h u m i d i t y i n the s p r i n g i s l i k e l y caused by t h e d e c r e a s e i n p r e c i p i t a t i o n d u r i n g t h i s t i m e . H u m i d i t y i n c r e a s e s a g a i n i n May as the canopy d e v e l o p s and the u n d e r s t o r y s p r i n g f l u s h o c c u r s . There i s an e x c e p t i o n t o t h i s t r e n d , however; the month of January 1980 shows.a s h a r p decrease i n h u m i d i t y . T h i s month was a b n o r m a l l y c o l d and c l e a r , with lower than normal p r e c i p i t a t i o n . T h i s c o u l d a c c o u n t f o r the d e c r e a s e i n h u m i d i t y . The t e m p e r a t u r e data f o r a l l t h r e e s t a t i o n s are almost i d e n t i c a l , and a r e g e n e r a l l y s i m i l a r t o data from the nearby weather s t a t i o n (UEL, T a b l e s 1-2).. The major e x c e p t i o n i s J a n u a r y 1980, which was much c o l d e r t h a n normal. T o t a l P r e c i p i t a t i o n A few meters from S t a t i o n 2, a ' t y p i c a l 1 specimen of Acer macrophyllum was chosen (mature t r e e w i t h a c e n t r i p e t a l crown, s l i g h t l y i n c l i n e d , DBH = 540 mm). A r a i n g u t t e r was e s t a b l i s h e d around the b o l e a t t h e 1.5 m l e v e l t o c o l l e c t stemflow ( F i g u r e 14). Water was c o l l e c t e d i n a l a r g e p l a s t i c c o n t a i n e r and amount r e c o r d e d a f t e r each r a i n f a l l . I n o r d e r t o compare the stemflow w i t h canopy t h r o u g h f a l l , a f u n n e l - c o n t a i n e r system was 37 e s t a b i s h e d a few meters away from t h e t r e e . The canopy above was r e l a t i v e l y open, c o n s i s t i n g o n l y o f a few branches of Acer M£rophy_llum • A g a i n , t o t a l p r e c i p i t a t i o n was r e c o r d e d . _ R e s u l t s a r e p r e s e n t e d i n F i g u r e 15.. The r e s u l t s show t h a t most of the p r e c i p i t a t i o n f e l l between September 1979 and March 1980, w i t h peaks d u r i n g December 1979 and February 1980. . Except f o r the dry summer months and e a r l y s p r i n g , stemflow i s s i g n i f i c a n t l y g r e a t e r t h a n canopy t h r o u g h f a l l . The branches and upper t r u n k c o l l e c t r a i n w a t e r which washes down t h e t r u n k . . D u r i n g the summer, when r a i n s a r e g e n e r a l l y l i g h t and i n f r e q u e n t , the e p i p h y t i c v e g e t a t i o n d r i e s out between r a i n s t o r m s . C onsequently most of the r a i n from such a storm i s t a k e n up by the e p i p h y t e s , so t h a t r e c o r d e d stemflow i s low. In the w i n t e r months, r a i n s a re heavy and o c c u r w i t h much g r e a t e r f r e q u e n c y . The e p i p h y t i c v e q e t a t i o n may remain s a t u r a t e d f o r e x t e n s i v e p e r i o d s ; c o n s e q u e n t l y t h e r a i n w a t e r c o l l e c t e d by the branches i s 'excess' which f l o w s over t h e e p i p h y t e s and i s c o l l e c t e d as stemflow.. The e p i p h y t i c environment i s c h a r a c t e r i z e d by extremes; d u r i n g t h e summer, very l i t t l e p r e c i p i t a t i o n i s a v a i l a b l e t o t h e v e g e t a t i o n on t h e l o w e r t r e e b o l e , c r e a t i n g d r o u g h t - l i k e c o n d i t i o n s . . D u r i n g the w i n t e r , however, stemflow p r o v i d e s the v e g e t a t i o n w i t h l a r g e " v o l u m e s of water. T h i s water may c o n t a i n v a l u a b l e n u t r i e n t s washed from the bark o f the branches and upper t r u n k . Many of the e p i p h y t i c s p e c i e s on Acer macrophyllum have been observed t o show h i g h e s t a n n u a l growth d u r i n g t h e 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 . Thus they appear t o be 38 p h y s i o l o g i c a l l y adapted t o growing d u r i n g p e r i o d s when water i s not a l i m i t i n g f a c t o r , and l i k e l y show a d a p t a t i o n s t o growing a t lower t e m p e r a t u r e s . I n t e r e s t i n g p h y s i o l o g i c a l e x p e r i m e n t s c o u l d be performed on t h e s e s p e c i e s t o f u r t h e r a n a l y z e t h e i r r e s p o n s e to such f a c t o r s . 39 CHAPTER H - THE PHOROPHYTE ACER MACROPHYLLUM The phorophyte s p e c i e s (or' h o s t t r e e ) i s of p r i m a r y i m p o r t a n c e i n d e t e r m i n i n g both the s u b s t r a t e and micr o e n v i r o n m e n t a v a i l a b l e t o e p i p h y t i c v e g e t a t i o n . The purpose of t h i s c h a p t e r i s t o d e s c r i b e t h e taxonomy, range and d i s t r i b u t i o n , and e c o l o g i c a l r e l a t i o n s h i p s of Acer §aeroEhv.llum. In a d d i t i o n , the bark c h a r a c t e r i s t i c s ( p h y s i c a l and ch e m i c a l ) o f the p h o r o p h y t e a re d i s c u s s e d i n some d e t a i l . B o t a n i c a l R e l a t i o n s h i p s Acer macrophyllum Pursh b e l o n g s i n the f a m i l y Aceraceae, subgenus A c e r , s e c t i o n M a c r o p h y l l a , s e r i e s M a c r o p h y l l a (Murray 1970).. Of t h e 13 s p e c i e s of Acer n a t i v e t o No r t h America, i t i s the o n l y a r b o r e a l member o f t h e subgenus Acer. Other a r b o r e a l members of t h i s subgenus (eg. . A t. p s e u d o p l a t a n u s , A.. . camp_estre, and A-_ £latanoides) occur i n Europe. JU macrophyllum i s p r o b a b l y most s i m i l a r i n i t s bark c h a r a c t e r i s t i c s and e p i p h y t i c s t r u c t u r e t o A. . p s e u d o p l a t a n u s (van V e l z e n , p e r s . comm. y . .. Range and D i s t r i b u t i o n Acer macrophyllum i s endemic t o t h e west c o a s t ' of North A m e r i c a , o c c u r r i n g from C a l i f o r n i a t o B r i t i s h Columbia. In C a l i f o r n i a , t h e s p e c i e s i s r e s t r i c t e d t o moist canyons a t h i g h e r e l e v a t i o n s (montane a r e a s ) . . I n Oregon, Washington, and B r i t i s h Columbia t h e s p e c i e s i s g e n e r a l l y r e s t r i c t e d t o mesic, n u t r i e n t -40 r i c h s i t e s west of t h e Coast M o u n t a i n s , below an e l e v a t i o n o f 1000 m ( K r a j i n a 1969). The s p e c i e s grows i n a v a r i e t y of s o i l s , from r i c h humus t o t h i n g r a v e l l y s o i l s c h a r a c t e r i s t i c of r o c k y s l o p e s , but appears t o p r e f e r c o a r s e , g r a v e l l y moist s o i l s . B est s t a n d s a r e developed on a l l u v i a l d e p o s i t s on r i v e r t e r r a c e s , b o t t o m l a n d s , and a t the f o o t o f mountains ( F o w e l l s 1965).. W h i l e the s o u t h e r n range of the s p e c i e s i s well-known (Sudworth 1967) i t s n o r t h e r n l i m i t has been debated. Many workers have suggested t h a t t h e s p e c i e s may re a c h as f a r n o r t h as the A l a s k a panhandle ( F o w e l l s 1965, H i t c h c o c k and C r o n g u i s t 1973) ; o t h e r s have suggested t h a t the n o r t h e r n l i m i t i s at 52°N a l o n g the B r i t i s h Columbia c o a s t (Hosie 1 969).. In B r i t i s h C o lumbia, the s p e c i e s i s r e s t r i c t e d t o r i p a r i a n s i t e s west of t h e Coast M o u n t a i n s , b e i n g common on the F r a s e r R i v e r d e l t a , c o a s t a l Vancouver I s l a n d , and on a l l u v i a l d e p o s i t s a l o n g t h e west c o a s t o f t h e mainland. The t r e e i s a minor component o f both t h e C o a s t a l Douglas F i r and C o a s t a l Western Hemlock b i o g e o c l i m a t i c zones ( K r a j i n a 1969). I n Oregon and p a r t s of Washington the s p e c i e s may form almost pure s t a n d s over l i m i t e d a r e a s ( F o w e l l s 1965); i n B r i t i s h C olumbia, i t t y p i c a l l y o c c u r s s c a t t e r e d i n mixed s t a n d s w i t h AInus r u b r a , Populus b r i c h o c a r p a , Pseudotsuqa m e n z i e s i i . Thuja p l i c a t a , and Tsuga b e t e r o p h y l l a ( F r a n k l i n and Dyrness 1973, Hosie 1969). E c o l o g i c a l R e l a t i o n s h i p s Acer macrophyllum grows r a p i d l y d u r i n g i t s f i r s t 40-60 . y e a r s , o f t e n a t a g r e a t e r r a t e t h a n t h e c o n i f e r o u s s p e c i e s w i t h which i t o c c u r s . .  S e e d l i n g s d e v e l o p more r a p i d l y i n more open 41 a r e a s o f h i g h e r l i g h t i n t e n s i t y . Young t r e e s are f a i r l y shade t o l e r a n t , and r e q u i r e t o p - l i g h t f o r b e s t growth (Sudworth 1967,, F o w e l l s 1965). T y p i c a l l y , the s p e c i e s forms a s h a l l o w but wide-s p r e a d i n g r o o t system. M a t u r i t y i s reached a t 150 y e a r s , but t r e e s may l i v e t o be 300 years o l d . Mature t r e e s are t y p i c a l l y 20-30 m i n h e i g h t , and may a t t a i n a diameter up t o 1.0 m a t b r e a s t h e i g h t . I n dense f o r e s t s w i t h heavy s i d e s h a d i n g , t h e t r e e i s u s u a l l y f r e e of branches f o r t w o - t h i r d s i t s l e n g t h , and s u p p o r t s a narrow but dense crown (Hosie 1969). . Trees i n open areas form b r o a d , rounded crowns, the trunk, b r a n c h i n g p r o l i f i c a l l y . Work quoted by F r a n k l i n and Dyrness (1973) s u q g e s t s t h a t the s p e c i e s i s t y p i c a l l y s u c c e s s i o n a l , o f t e n o c c u r r i n g i n ar e a s d i s t u r b e d by l o g g i n g . . In western Washington, the f o l l o w i n g s u c c e s s i o n a l sequence was note d : c o l o n i z i n g stands o f Alnus r u b r a are i n v a d e d and r e p l a c e d by Populus t r i c h o c a r p a , Acer I§£E°EhY.Iiujn, and P i c e a s i t e hens i s , which e v e n t u a l l y g i v e s r i s e t o a c l i m a x v e g e t a t i o n dominated by Tsuga h e t e r o p h y l l a and £•_„ s i t c h e n s i s . However, i n ar e a s o f s h a l l o w , s t o n y s o i l , g r o v e s of A., macrgphyllum may be found even a t the c l i m a x s t a g e . Hosie (1969) n o t e s t h a t the s p e c i e s o f t e n o c c u p i e s c l e a r i n g s l a t e r succeeded by c o n i f e r s ; s i m i l a r o b s e r v a t i o n s were made by F o w e l l s (1 965) . Buds appear on t r e e s o f t h i s s p e c i e s i n e a r l y A p r i l and soon b u r s t , w i t h f l o w e r s and f i r s t l e a v e s u s u a l l y a p p e a r i n g t o g e t h e r . By the end of A p r i l , the canopy has begun t o f i l l i n , and by mid-May i t i s dense and w e l l d e v e l o p e d , c o n s i s t i n g of l a r g e l e a v e s 30-40 cm i n l e n g t h f o r m i n g a dense canopy which 42 shades t h e u n d e r s t o r y . Seeds mature i n September or O c t o b e r , and l e a v e s b e g i n t o f a l l soon a f t e r . By the end o f October t h e t r e e s are d e v o i d of l e a v e s . Bark C h a r a c t e r i s t i c s Barkman (1958) has emphasized t h e importance of s u b s t r a t e (bark) t o t h e development o f e p i p h y t i c v e g e t a t i o n . In t h i s s e c t i o n , p h y s i c a l and c h e m i c a l f a c t o r s of the bark of Acer S a c r o p h y l l u m are d e s c r i b e d i n some d e t a i l . Emphasis i s p l a c e d upon t h o s e c h a r a c t e r i s t i c s thought t o be of importance t o the e p i p h y t i c v e g e t a t i o n on t h i s phorophyte. D i f f e r e n c e s i n bark f a c t o r s between s i t e s , and between t r e e s of d i f f e r i n g age are a n a l y z e d ; d i f f e r e n c e s w i t h c h a n g i n g h e i g h t and i n c l i n a t i o n on the b o l e a re a l s o d i s c u s s e d . P h y s i c a l F a c t o r s On young t r e e s o f Acer macrophyllum (up t o a DBH of 150 mm) the bark i s t h i n (0.5 cm or l e s s ) , grey-brown i n c o l o u r , and j u s t b e g i n n i n g t o form f i s s u r e s . As t h e t r e e matures, the bark becomes t h i c k e r and more d e e p l y f i s s u r e d . On o l d e r t r e e s (DBH of 350 mm and g r e a t e r ) t h e bark i s 3-4 cm t h i c k and g r e y i s h - b r o w n i n c o l o u r , f o r m i n g s h a l l o w (0.3-0.8 cm deep) f i s s u r e s 1.5-2.0 cm a p a r t , p a r a l l e l t o the l o n g a x i s o f t h e b o l e , and anastamosing i n a complex f a s h i o n . The bark between the f i s s u r e s o f t e n becomes l o o s e , f o r m i n g s c a l y r i d g e s e a s i l y removed from the b o l e . The bark of very o l d t r e e s (DBH of 800 mm or g r e a t e r ) i s 4-6 cm t h i c k w i t h f i s s u r e s 1.5-2.0 cm deep, t h e bark r i d g e s 43 becoming i n c r e a s i n g l y more s c a l y and e a s i l y removed. . D i f f e r e n c e s i n degree of s c a l i n e s s a r e o f t e n observed on the upper and lower s i d e s of the t r u n k . The upper s i d e forms s c a l y r i d g e s as d e s c r i b e d above; however, they are o f t e n not formed on the lower s i d e . F i g u r e 16 d i a g r a m a t i c a l l y i l l u s t r a t e s t h e bark s u b s t r a t u m . T h i s was t r a c e d from a t r e e o f DBH = 620 mm a t BRI, and i s r e p r e s e n t a t i v e of t r e e s of t h i s s i z e c l a s s ; W a t e r - h o l d i n g c a p a c i t y of bark i s d i f f i c u l t t o measure ( B i l l i n g s and Drew 1938)* Removal o f bark from the t r e e t o measure t h i s parameter c r e a t e s d i f f i c u l t i e s , s i n c e t h e i n n e r bark l a y e r s a r e n o r m a l l y not exposed to t h e environment ( p r e c i p i t a t i o n ) , whereas t h e y a r e i n e x p e r i m e n t s u n l e s s p r e c a u t i o n a r y measures a r e t a k e n . I t would seem p r e f e r a b l e t o measure water c o n t e n t of the bark t h r o u g h f i e l d s a m p l i n g , but as Barkman (1958) p o i n t s out bark water c o n t e n t i s dependent upon weather c o n d i t i o n s . I n t h e p r e s e n t s t u d y , bark c o l l e c t i o n s were made i n November 1979 a f t e r heavy r a i n s i n an attempt t o measure 'maximum water c o n t e n t * of the bark under n a t u r a l c o n d i t i o n s (which i s l i k e l y a f a i r a p p r o x i m a t i o n of w a t e r - h o l d i n g c a p a c i t y ) . Bark samples were t a k e n a t an h e i g h t of 1.5 m from t r e e s at SQU, BRI, and UEL, on bo t h the upper and lower s i d e s o f the t r e e s . DBH of t h e t r e e s sampled ranged from 510 t o 745 mm. F i v e t r e e s were sampled a t each o f the 3 s i t e s ; s i t e d i f f e r e n c e s were not apparent. On t h e upper s i d e of the b o l e , a mean water c o n t e n t of 60.4% (range 52.3-70.0%) was r e c o r d e d ( v a l u e s a re expr e s s e d as p e r c e n t water c o n t e n t of c o l l e c t e d s a m p l e s ) . T h i s v a l u e i s comparable t o t h a t found by S t e f u r e a c ( i n Barkman 1958) f o r Acer (60.7%) i n the East C a r p a t h i a n Mtns..of Europe..On the Figure 16. Bark r e l i e f of Acer macrophylluro. (a). Top view. Shaded areas are ridges, (b). Side view through area indicated by dashed l i n e i n (a). 45 lower s i d e o f the t r e e s , v a l u e s a r e much lower; a mean v a l u e of 28.4% (range 26.0-35 . 1 % ) was r e c o r d e d . The h i g h v a l u e o f bark water c o n t e n t from the upper s i d e s u g g e s t s t h a t t h e bark may be a water s o u r c e a v a i l a b l e t o the e p i p h y t e s through c a p i l l a r y a c t i o n . . On t r e e s w i t h i n a g i v e n DBH range, bark d i f f e r e n c e s between t r e e s , and on d i f f e r e n t p a r t s of the same t r e e , a re o f t e n a p p a r e n t T h e s e d i f f e r e n c e s appear t o be a r e f l e c t i o n of t h e t o t a l amount of p r e c i p i t a t i o n f a l l i n g i n the bark and the amount of time i t i s r e t a i n e d , which i n t u r n a f f e c t s t h e r a t e of bark decompostion. The bark beneath a t h i c k , w e l l - d e v e l o p e d b r y o p h y t e mat remains damp f o r l o n g p e r i o d s f o l l o w i n g a r a i n s h o w e r , and i s crumbly i n t e x t u r e and h i g h l y decomposed. F u n g a l and m i c r o b i a l a c t i v i t y a r e o f t e n i n e v i d e n c e . An a c c u m u l a t i o n of decomposed br y o p h y t e v e g e t a t i o n and bark may c r e a t e a 'humus l a y e r ' between the l i v i n g bark and the bryop h y t e mat, e s p e c i a l l y on the upper s i d e of i n c l i n e d t r u n k s . T h i s humus l a y e r may be from 1-3 cm deep..In a r e a s where t h e f e r n Polyppdium g l y c y r r h i z a o c c u r s , the r h i z o m e - r o o t system may a c t as a b i n d e r , so t h a t the humus l a y e r may become q u i t e t h i c k . I n a r e a s where a humus l a y e r does not o c c u r , the bark i s l e s s decomposed, h a r d e r , and removable o n l y w i t h d i f f i c u l t y . Bark on t h e lower s i d e o f most b o l e s i s not decomposed, r a r e l y forms f l a k y s c a l e s , and i s h a r d e r t h a n bark on the upper s i d e . . 46 C h e m i c a l F a c t o r s A l t h o u g h i t i s g e n e r a l l y acknowledged t h a t bark n u t r i e n t l e v e l s a r e i m p o r t a n t i n d e t e r m i n i n g e p i p h y t i c c o m p o s i t i o n on a g i v e n phorophyte, few d e t a i l e d s t u d i e s have been r e p o r t e d i n the l i t e r a t u r e . Barkman (1958) has summarized the l i t e r a t u r e up to t h a t t i m e ; l i t t l e work beyond t h e measurement of bark pH has taken p l a c e s i n c e . I n t h e p r e s e n t s t u d y , some n u t r i e n t s ( t o t a l n i t r o g e n , phosphor u s , . c a l c i u m , magnesium, and p o t a s s i u m ) , t o t a l ash ( e l e c t r o l y t e ) c o n c e n t r a t i o n , and pH of t h e bark of Acer §acro£hyllum were measured. A l l n u t r i e n t a n a l y s e s were performed at t h e F o r e s t E c o l o g y l a b o r a t o r y . Dept. Of F o r e s t r y , U n i v e r s i t y of B r i t i s h C o lumbia. T o t a l n i t r o g e n and phosphorus were det e r m i n e d by semi-micro K j e l d a h l u s i n g a 'Technicon' I n d u s t r i a l Atomic A n a l y z e r . C a t i o n s ( c a l c i u m , magnesium, potassium) were a n a l y z e d u s i n g a ' V a r i o n - T e c t r o n * a t o m i c a b s o r p t i o n s p e c t r o p h o t o m e t e r . . A l l n u t r i e n t v a l u e s a r e e x p r e s s e d as a p e r c e n t a g e of the weight o f t h e d r i e d bark sample. Bark pH was measured u s i n g a Radiometer pH meter. These a n a l y s e s were undertaken t o e l u c i d a t e the c h e m i c a l s t a t u s o f the e p i p h y t i c s u b s t r a t e t o determine t o what e x t e n t n u t r i e n t l e v e l s change as one proceeds up and around t h e t r e e b o l e , and t o determine n u t r i e n t d i f f e r e n c e s between t r e e s of d i f f e r e n t s i z e . R e s u l t s a r e d i s c u s s e d i n t u r n below. L S i t e D i f f e r e n c e s For each o f t h e 75 t r e e s on which e p i p h y t i c v e g e t a t i o n was 47 a n a l y z e d , a bark sample was t a k e n from the upper s i d e of the t r u n k a t a h e i g h t of 1.5 m above the b a s e . . S i n c e i t has been shown t h a t bark c h e m i s t r y may d i f f e r depending upon where th e sample i s t a k e n (Barkman 1958, Kershaw 1964), an attempt was made t o m i n i m i z e t h e s e d i f f e r e n c e s by s a m p l i n g from s i m i l a r a reas on each t r e e . R e s u l t s f o r each o f the 75 t r e e s i s shown i n Appendix 1. For each s i t e , summary d a t a (means and s t a n d a r d d e v i a t i o n s ) f o r each c h e m i c a l f a c t o r s t u d i e d were computed (Table 5 ) . The r e s u l t s suggest t h a t t h e r e a r e some d i f f e r e n c e s between bark c h e m i c a l c o m p o s i t i o n a t t h e s i t e s . The s i g n i f i c a n c e of t h e s e d i f f e r e n c e s were t e s t e d u s i n g one-way a n a l y s i s of v a r i a n c e , comparing each of the 7 c h e m i c a l f a c t o r s over the 5 s i t e s ; r e s u l t s are shown i n Table 6. S i g n i f i c a n t d i f f e r e n c e s i n bark c h e m i c a l f a c t o r s between t h e 5 s i t e s a r e a p p a r e n t T o t a l n i t r o g e n c o n t e n t of the bark i s s i g n i f i c a n t l y h i g h e r a t UEL than the o t h e r s i t e s . . B a r k phosphorus v a l u e s a t UEL a r e s i g n i f i c a n t l y h i g h e r t h a n t h o s e a t SQU and FUR, w h i l e v a l u e s a t BRI are s i g n i f i c a n t l y h i g h e r than a t SQU, FUR, and PIT. Bark c a l c i u m c o n t e n t i s s i g n i f i c a n t l y h i g h e r than a t SQU, FUR, and UEL. Magnesium l e v e l s of the bark a r e s i g n i f i c a n t l y l o w e r a t UEL than t h e o t h e r s i t e s . At SQU, bark p o t a s s i u m l e v e l s a r e s i g n i f i c a n t l y h i g h e r than a t FUR, UEL, and PIT; a l s o , v a l u e s at BRI are s i g n i f i c a n t l y h i g h e r than UEL, which has t h e l o w e s t bark p o t a s s i u m c o n t e n t . T o t a l ash c o n t e n t of the bark i s l o w e s t a t FUR and UEL; both of t h e s e s i t e s have s i g n i f i c a n t l y lower v a l u e s than SQU and BRI. Values o f bark pH a r e h i g h e s t a t SQU and BRI, and l o w e s t a t UEL. Both BRI and SQU have s i g n i f i c a n t l y h i g h e r bark pH than FUR, UEL, and PIT. A l s o , UEL has s i g n i f i c a n t l y N SQU 0.781 (0.225) FUR 0.752 (0.182) UEL 0.965 (0.111) PIT 0.768 (0.117) BRI 0.732 (0.098) P Ca 0.082 5.070 (0.017) (1.623) 0.077 4.686 (0.018) (1.006) 0.100 4.902 (0.019) (1.904) 0.087 5.837 (0.016) (2.069) 0.104 6.503 (0.019) (1.703) Mg K 0.320 0.338 (0.077) (0.158) 0.326 0.233 (0.070) (0.104) 0.198 0.143 (0.050) (0.058) 0.292 0.198 (0.057) (0.071) 0.310 0.259 (0.084) (0.193) ash pH 12.903 7.09 (1.859) (0.171) 10.392 6.69 (2.083) (0.220) 10.921 6.38 (1.901) (0.301) 11.877 6.70 (2.391) (0.246) 12.584 6.93 (2.460) (0.440) Table 5. Means and standard deviations ( i n brackets) of 7 bark chemical factors over 15 trees at each of the 5 study s i t e s . Nitrogen SQU FUR 0.247 UEL 10.645** 14.135** PIT 0.048 0.077 12.128** BRI 0.737 0.131 16.983** 0.408 Phosphorous SQU FUR 0.523 UEL 7.939** PIT 0.715 BRI 11.378** C a l c i u m SQU FUR 0.384 UEL 0.074 PIT 1.525 BRI 5.323* Magnesium SQU FUR 0.047 UEL 23.644** 25.807** PIT 1.306 1.851 13.835** BRI 0.162 0.384 19.896** 0.549 Table 6. Analysis of variance of between-site differences i n 7 bark chemical factors. F-values are shown, and significance of differences are indicated; * = 0.05, ** = 0.01. 12.539** 2.461 3.889 16.782** 0.309 6.390* 0.121 3.438 2.269 8.565** 6.650* 1.150 Potassium SQU FUR UEL PIT BRI SQU FUR UEL PIT BRI SQU FUR UEL PIT BRI 5.011* 17.350** 8.986** 2.841 Ash 10.198** 6.356* 1.703 0.164 PH 14.203** 44.748** 13.502** 2.179 3.713 0.576 0.306 1.364 6.150* 1.722 0.452 3.566 1.479 7.774** 4.476* 0.809 8.531** 0.009 9.090** 5.256* 27.179** 4.833* Table 6. continued. 51 lower b a r k pH th a n PIT and FDR. A number of o v e r a l l t r e n d s a re apparent from t h e r e s u l t s . C a l c i u m c o n t e n t and t o t a l ash c o n c e n t r a t i o n of t h e bark o f Acer macrophY_llum a r e very h i g h , and pH v a l u e s a r e near n e u t r a l ; s i m i l a r r e s u l t s have been o b t a i n e d f o r s p e c i e s o f Acer i n Europe (Barkman 1958). Bark from t r e e s a t UEL i s c h e m i c a l l y the most d i s t i n c t , h a v i n g h i g h v a l u e s of t o t a l n i t r o g e n and phosphorus, and low v a l u e s of c a l c i u m , t o t a l ash, magnesium, pota s s i u m , and bark pH.. The h i g h pH and potassi u m v a l u e s o f t r e e bark a t SQU may be a t t r i b u t a b l e t o dust i m p r e g n a t i o n from a nearby g r a v e l l o g g i n g r o a d . The two m a r i t i m e s i t e s (FUR and UEL) have the l o w e s t b a r k c a l c i u m c o n t e n t . Bark c a l c i u m c o n t e n t appears t o show a h i g h p o s i t i v e c o r r e l a t i o n w i t h t o t a l ash c o n t e n t and pH, except a t SQU, where dust i m p r e g n a t i o n may be an o v e r r i d i n g f a c t o r . The r e s u l t s would suggest t h a t s i n c e d i f f e r e n c e s i n bark c h e m i s t r y of Acer macro£hyllum between the s i t e s a r e a p p a r e n t , t h i s f a c t o r may be of some i m p o r t a n c e i n e x p l a i n i n g d i f f e r e n c e s i n e p i p h y t i c v e g e t a t i o n between the s i t e s * I t i s d i f f i c u l t t o say what i n f l u e n c e s may be r e s p o n s i b l e f o r t h e s e d i f f e r e n c e s ; s i t e s o i l c h a r a c t e r i s t i c s , d u s t i m p r e g n a t i o n , p o l l u t i o n , and p r o x i m i t y t o the ocean may a l l be i m p o r t a n t f a c t o r s . 2. H e i g h t D i f f e r e n c e s At each of t h e s i t e s , 5 t r e e s ( a l l o f which were a l s o sampled f o r t h e i r e p i p h y t i c v e g e t a t i o n ) were chosen t o a n a l y z e d i f f e r e n c e s i n bark c h e m i s t r y w i t h h e i g h t . At each t r e e , bark 52 samples were ta k e n on the upper s i d e o f t h e b o l e a t h e i g h t s of 1, 3 and 5 m above the base. A g a i n , an a t t e m p t was made t o c o l l e c t from s i m i l a r a r e a s on each of the t r e e s . For the t h r e e s a m p l i n g s h e i g h t s , means and s t a n d a r d d e v i a t i o n s were computed f o r each o f t h e 7 c h e m i c a l f a c t o r s ; r e s u l t s a r e shown i n Table 7. S i g n i f i c a n c e o f d i f f e r e n c e s i n c h e m i c a l c o m p o s i t i o n w i t h h e i g h t f o r each s i t e were not a n a l y z e d because of h i g h between-t r e e v a r i a b i l i t y i n b a r k c h e m i c a l v a l u e s . At a l l s i t e s , c a l c i u m c o n t e n t , t o t a l ash c o n t e n t , and pH decrease w i t h i n c r e a s i n g h e i g h t up t h e b o l e (an e x c e p t i o n b e i n g BRI, where bark pH t r e n d s a r e not a p p a r e n t ) . _ I n g e n e r a l , t h e o t h e r n u t r i e n t s do not show s i g n i f i c a n t h e i g h t t r e n d s a t any o f t h e s i t e s . . The r e s u l t s s u g g e s t t h a t some bark c h e m i c a l v a l u e s d e c r e a s e w i t h i n c r e a s i n g h e i g h t a l o n g the b o l e . G r e a t e s t d i f f e r e n c e s a r e between t h e base of the t r e e and h i g h e r l e v e l s . E p i p h y t i c v e g e t a t i o n may respond t o t h i s n u t r i e n t - h e i g h t g r a d i e n t , a l t h o u g h i t s h o u l d be noted t h a t between-tree d i f f e r e n c e s f o r t h e s e c h e m i c a l f a c t o r s may be l a r g e enough t o mask such an e f f e c t ( r e f e r t o s t a n d a r d d e v i a t i o n v a l u e s , T a b l e 8 ) . 3. I n c l i n a t i o n D i f f e r e n c e s At the DEL s i t e , 5 t r e e s were chosen t o a n a l y z e d i f f e r e n c e s i n bark c h e m i s t r y on the upper and lower s i d e s of the t r u n k a t d i f f e r e n t h e i g h t s . . On each t r e e , bark samples were t a k e n from t h e upper and lower s i d e s of t h e t r e e a t 1 , 3, and 5 m above t h e base. Means and s t a n d a r d d e v i a t i o n s f o r each o f the 7 c h e m i c a l 53 f a c t o r s a n a l y z e d a r e shown i n T a b l e 8. D i f f e r e n c e s i n c h e m i c a l f a c t o r s between the upper and l ower s i d e s of the b o l e are apparent..The s i g n i f i c a n c e of t h e s e d i f f e r e n c e s was t e s t e d u s i n g one-way a n a l y s i s o f v a r i a n c e , comparing the 7 c h e m i c a l f a c t o r s on the lower and upper s i d e s a t each of t h e 3 h e i g h t s . . R e s u l t s a r e shown i n T a b l e 9.. N i t r o g e n and phosphorus v a l u e s a r e s i g n i f i c a n t l y h i g h e r on the upper s i d e of the t r e e a t a l l h e i g h t s (except f o r phosphorus at t h e 5 m h e i g h t ) C a l c i u m c o n t e n t i s g r e a t e r on t h e l ower s i d e a t a l l h e i g h t s , a l t h o u g h t h e d i f f e r e n c e i s s i g n i f i c a n t o n l y a t t h e 1 m l e v e l . None o f t h e o t h e r c h e m i c a l f a c t o r d i f f e r e n c e s a r e s i g n i f i c a n t , a l t h o u g h some t r e n d s a r e a p p a r e n t . Ash c o n t e n t i s h i g h e r on t h e lower s i d e a t 1 m and 5 m, but s l i g h t l y lower at t h e 3 m l e v e l . Magnesium and p o t a s s i u m l e v e l s a r e s i m i l a r on t h e upper and lower s i d e s a t a l l h e i g h t s . No t r e n d s i n bark pH are e v i d e n t . . t 4. Tree S i z e C l a s s D i f f e r e n c e s At UEL, 8 s m a l l t r e e s ( r a n g i n g between 100 and 200 mm DBH) were s e l e c t e d f o r a n a l y s i s of bark c h e m i c a l f a c t o r s . A bark sample was taken at a l e v e l o f 1.5m above the base of each t r e e . R e s u l t a n t bark c h e m i c a l v a l u e s were compared wit h those o b t a i n e d from the t r e e s l o c a t e d a t t h e same s i t e as d e s c r i b e d e a r l i e r (see p a r t 1 above, and Appendix 1). Means and s t a n d a r d d e v i a t i o n s f o r the 7 c h e m i c a l f a c t o r s are shown i n T a b l e 10. One-way a n a l y s i s of v a r i a n c e was used t o a n a l y z e f o r d i f f e r e n c e s i n t h e s e c h e m i c a l f a c t o r s between the 2 t r e e s i z e c l a s s e s ; r e s u l t s are shown i n Table 11. C a l c i u m , magnesium, and t o t a l ash SQU ™ lm. 0.775 (0.163) 3m. 0.838 (0.297) 5m. 0.798 (0.206) P Ca 0.082 5.416 (0.010) (1.318) 0.075 4.328 (0.018) (1.146) 0.071 3.483 (0.008) (0.775) Mg K 0.329 0.284 (0.096) (0.096) 0.224 0.201 (0.052) (0.042) 0.263 0.274 (0.040) (0.107) ash pH 12.442 7.16 (1.318) (0.089) 9.736 6.69 (0.407) (0.167) 8.112 6.69 (1.293) (0.204) FUR lm. 0.688 0.073 4.868 (0.099) (0.008) (0.506) 3m. 0.628 0.074 3.616 (0.051) (0.013) (0.935) 5m. 0.667 0.075 3.330 (0.094) (0.016) (0.542) 0.336 0.263 9.832 6.74 (0.028) (0.098) (0.748) (0.125) 0.351 0.313 8.702 6.71 (0.056) (0.145) (0.370) (0.185) 0.330 0.272 8.094 6.33 (0.057) (0.094) (0.351) (0.104) UEL lm. 0.925 0.099 4.673 (0.214) (0.015) (2.232) 3m. 1.069 0.107 4.003 (0.195) (0.031) (1.708) 5m. 0.959 0.092 2.755 (0.197) (0.031) (1.368) 0.195 0.159 10.742 6.38 (0.052) (0.043) (2.301) (0.368) 0.181 0.171 9.394 6.01 (0.042) (0.060) (2.260) (0.554) 0.140 0.147 7.218 5.80 (0.049) (0.033) (2.333) (0.694) PIT lm. 0.750 (0.073) 3m. 0.883 (0.089) 5m. 0.896 (0.132) 0.086 5.424 (0.008) (1.196) 0.096 4.231 (0.009) (0.733) 0.099 3.569 (0.022) (0.334) 0.283 0.204 (0.044) (0.038) 0.301 0.245 (0.046) (0.065) 0.293 0.238 (0.068) (0.079) 10.918 6.74 (1.736) (0.055) 8.634 6.68 (0.814) (0.278) 8.396 6.57 (1.327) (0.254) BRI lm. 0.639 0.098 6.493 0.335 0.344 12.234 7.37 (0.035) (0.018) (1.264) (0.073) (0.249) (1.505) (0.390) 3m. 0.663 0.103 5.649 0.342 0.313 11.382 7.20 (0.057) (0.027) (0.558) (0.077) (0.230) (0.567) (0.362) 5m. 0.647 0.096 5.087 0.349 0.329 10.546 7.38 (0.039) (0.013) (1.192) (0.105) (0.206) (1.362) (0.223) Table 7 . Means and standard deviations ( i n brackets) of 7 bark chemical factors over 5 trees and 3 sampling heights at each of the 5 study s i t e s . Im. N P Ca Mg K ash pH upper 0.956 0.099 4.506 0.198 0.143 10.236 6.30 (0.064) (0.009) (1.249) (0.029) (0.017) (0.731) (0.170) lower 0.672 0.070 5.929 0.192 0.143 10.620 6.17 (0.095) (0.007) (1.044) (0.032) (0.020) (0.585) (0.076) 3m. upper 1.000 0.101 4.102 0.177 0.143 9.294 5.87 (0.092) (0.012) (0.653) (0.009) (0.014) (1.010) (0.179) lower 0.619 0.074 5.004 0.183 0.140 9.196 6.07 (0.062) (0.005) (0.785) (0.030) (0.216) (0.681) (0.097) 5m. upper 0.984 0.092 3.013 0.133 0.141 7.262 5.88 (0.083) (0.013) (0.984) (0.042) (0.024) (1.033) (0.225) lower 0.639 0.081 4.124 0.143 0.139 8.514 5.88 (0.078) (0.008) (0.705) (0.032) (0.020) (1.660) (0.297) Table 8. Means and standard deviations ( i n brackets) of 7 bark chemical f a c t o r s over 5 trees and 6 sampling regions at UEL. 56 lm. 3m. 5m. Nitrogen 31.709** 56.967** 46.661** Phosphorous 23.066** 19.167** 3.229 Calcium 5.891* 2.364 3.5854 Magnesium 0.116 0.109 0.266 Potassium 0.002 0.044 0.009 Ash 0.358 0.023 3.804 PH 1.179 2.791 0.000 Table 9. Analysis of variance of differences i n 7 bark chemical factors between the upper and lower sides of the bole (at 3 sampling heights) at UEL. F-values are shown, and s i g n i f i c a n c e of differences are indicated; * = 0.05, ** = 0.01. N N P Ca Mg K ash pH Old 0.965 0.100 4.902 0.198 0.143 10.921 6.38 (0.111) (0.019) (1.904) (0.050) (0.058) (1.901) (0.301) Young 1.093 0.097 2.451 0.139 0.159 7.069 6.04 (0.094) (0.013) (0.545) (0.041) (0.034) (0.996) (0.248) Table 10. Means and standard deviations ( i n brackets) of 7 bark chemical factors from young (small) and old (mature) trees at UEL. « P Ca Mg K ash pH 7.740* 0.209 12.451** 8.356** 0.471 28.245** 7.282* Table 11. Analysis of variance of differences i n 7 bark chemical factors between young (small) and old (mature) trees at UEL. F-values are shown, and s i g n i f i c a n c e of differences are indicated; * = 0.05, ** = 0.01. 57 c o n t e n t , as w e l l as bark pH, are s i g n i f i c a n t l y lower on the s m a l l e r t r e e s . T o t a l n i t r o g e n i s s i g n i f i c a n t l y h i g h e r , however. V a l u e s f o r phosphorus and p o t a s s i u m a r e s i m i l a r on s m a l l and l a r g e r t r e e s . The r e s u l t s s u g g e s t t h a t t h e bark of young t r e e s of Acer m a g r o p h y l l u m i s d i f f e r e n t from mature t r e e s not o n l y p h y s i c a l l y but c h e m i c a l l y , as w e l l . Thus, c h e m i c a l f a c t o r s may be an i m p o r t a n t c o n s i d e r a t i o n when a n a l y z i n g s u c c e s s i o n a l sequences of e p i p h y t i c v e g e t a t i o n which t a k e s p l a c e as the t r e e matures.. 58 CHAPTER 5 - SAMPLING METHODS AND METHODS OF DATA ANALYSIS I n t h i s c h a p t e r , methods used i n s a m p l i n g the e p i p h y t i c v e g e t a t i o n on Acer jnacrophyllum a re d e s c r i b e d . In a d d i t i o n , c l a s s i f i c a t o r y and o r d i n a t i o n methods used i n t h e data a n a l y s i s a r e o u t l i n e d . Methods o f Sampling G r e i g - S m i t h (1964) d i s c u s s e s t h e methods a v a i l a b l e t o the e c o l o g i s t i n e s t i m a t i n g v e g e t a t i o n performance; these i n c l u d e measures of d e n s i t y , c o v e r , and fregu e n c y f o r each s p e c i e s , o f t e n e s t i m a t e d w i t h i n s a m p l i n g u n i t s (quadrats) . .In t h e p r e s e n t s t u d y , ' l o c a l f r e q u e n c y ' ( G r e i g - S m i t h 1964) has been used i n sam p l i n g the e p i p h y t i c v e g e t a t i o n . A r e c t a n g u l a r quadrat frame measuring 10 x 20 cm was s u b d i v i d e d i n t o 50 2 x 2 cm 'quadrat u n i t s ' w i t h f i n e w i r e . L o c a l f r e q u e n c y (on a s c a l e of 0-50) o f each s p e c i e s o c c u r r i n g w i t h i n the guadrat frame ( h e n c e f o r t h r e f e r r e d to as the guadrat) was r e c o r d e d . The use of f r e g u e n c y i n s a m p l i n g v e g e t a t i o n has been d i s c u s s e d by G r e i g - S m i t h (1964) and Mueller-Dombois and E l l e n b e r g (1974). Freguency v a l u e s a re dependent upon b o t h d e n s i t y and p a t t e r n of the s p e c i e s b e i n g sampled. T h i s has some advantages i n t h a t f r e g u e n c y i n c o r p o r a t e s these two i m p o r t a n t v e g e t a t i o n a l measures; they a r e a l s o confounded, however. Frequency v a l u e s a r e a l s o dependent upon t h e shape and s i z e of the q u a d r a t used i n sampling. I n t h e p r e s e n t s t u d y , q u a d r a t s i z e 59 was chosen a f t e r c a r e f u l c o n s i d e r a t i o n of t h e n a t u r e o f t h e e p i p h y t i c v e g e t a t i o n on Acer macrophyllum; q u a d r a t s i z e s used by o t h e r workers i n s t u d y i n g e p i p h y t i c systems was a l s o c o n s i d e r e d (as r e v i e w e d by S l a c k 1976). Sampling procedures used i n the s t u d y of e p i p h y t i c v e g e t a t i o n , i n c l u d i n g s a m p l i n g s t r a t e g y and quadrat s i z e and shape, have been reviewed by Barkman (1958) and S l a c k (1976). Most workers have used p e r c e n t c o v e r e s t i m a t e s ; however, t h i s may be s u b j e c t t o a h i q h deqree of e r r o r ( G r i e q - S m i t h 1964). L o c a l f r e q u e n c y has been used here s i n c e i t i s a q u i c k , e a s y , and a c c u r a t e e s t i m a t e o f s p e c i e s performance. I t s h o u l d be emphasized t h a t l o c a l f r e q u e n c y i s not an e s t i m a t e of c o v e r ; f o r example, a s m a l l s p e c i e s e v e n l y d i s t r i b u t e d o v er the e n t i r e s a m p l i n g area w i l l have low c o v e r but h i g h l o c a l f r e q u e n c y . Quadrats were p l a c e d s y s t e m a t i c a l l y on the t r e e b o l e . S y s t e m a t i c s a m p l i n q has advantaqes over random methods i f i n t e r e s t l i e s i n v e g e t a t i o n a l mapping or i n the a n a l y s i s of e n v i r o n m e n t a l g r a d i e n t s . A t o t a l o f 6 h e i g h t s were sampled (0.5, 1, 2, 3, 4, and 5 m above the t r e e b a s e ) ; a t each h e i g h t , 4 q u a d r a t s were p l a c e d around t h e b o l e . F i r s t , a q u a d r a t was p l a c e d on the upper s i d e o f the i n c l i n e d b o l e ; o t h e r q u a d r a t s ware th e n p l a c e d a t 90° i n t e r v a l s around the t r e e . Thus a t each h e i g h t an 'upper*, ' l o w e r * , and 2 'mid' q u a d r a t s were d e f i n e d , f o r a t o t a l of 24 q u a d r a t s per t r e e . At each q u a d r a t , t h e a n q l e of the b o l e was measured u s i n g a c l i n o m e t e r . The sampling d e s i g n was such t h a t the e n t i r e b o l e (to a h e i g h t of 5 m) was e f f i c i e n t l y sampled. The d e s i g n a l s o a l l o w s f o r t h e a n a l y s i s of t h e response of the e p i p h y t i c v e g e t a t i o n t o presumed h e i g h t and 60 i n c l i n a t i o n g r a d i e n t s on the t r e e s . W i t h i n a g i v e n s i t e , t r e e s of a p p r o x i m a t e l y the same DBH and i n c l i n a t i o n , w i t h i n a r e l a t i v e l y homogeneous r e g i o n of the f o r e s t , were chosen f o r s a m p l i n g . I n t h i s way m i c r o e n v i r o n m e n t a l and h a b i t a t d i f f e r e n c e s between the e p i p h y t i c h a b i t a t s on t h e b o l e s were mi n i m i z e d . . T r e e s b r a n c h i n g at t h e base or below 10 m from t h e base were not sampled, i n o r d e r t o m i n i m i z e t h e i n f l u e n c e o f r a i n t r a c k s and s h a d i n g by l a r g e b a s a l branches. In T a b l e s 12-16, i n f o r m a t i o n r e g a r d i n g t r e e s i z e and l o c a t i o n i n the f o r e s t (nature of the s u r r o u n d i n g t r e e and shrub v e g e t a t i o n ) f o r each s i t e i s p r e s e n t e d . A l l s a m p l i n g was done d u r i n g t h e summer (June-August) of 1979. Specimens not r e a d i l y i d e n t i f i a b l e i n t h e f i e l d were brought back to the l a b o r a t o r y f o r v e r i f i c a t i o n . . Voucher specimens of a l l c o l l e c t e d e p i p h y t e s p e c i e s have been d e p o s i t e d i n the U n i v e r s i t y of B r i t i s h Columbia herbarium (UBC). Appendix 2 l i s t s a l l e p i p h y t i c s p e c i e s c o l l e c t e d and the s i t e s a t which they o c c u r . . Methods of Data A n a l y s i s As has been p o i n t e d out by Noy-Meir and W h i t t a k e r (1978), the g u e s t i o n of whether t o o r d i n a t e or c l a s s i f y e c o l o g i c a l d a t a has i n r e c e n t y e a r s l o s t much of i t s sh a r p n e s s . . I t i s now g e n e r a l l y r e c o g n i z e d t h a t the methods can be complementary r a t h e r t h a n a n t a g o n i s t i c . Indeed, t o e f f i c i e n t l y summarize t h e i n f o r m a t i o n i n a data s e t , a s t r a t e g y i n v o l v i n g both o r d i n a t i o n and c l a s s i f i c a t o r y methods may be the most u s e f u l ( O r l o c i 1978). However, the two s t r a t e g i e s do s e r v e d i f f e r e n t purposes, so t h a t 61 Stand Study DBH D i r e c t i o n Location (nature of the surrounding Tree Tree (mm) of Lean vegetation, trees and shrubs) 1 1 446 East In dense grove of Acer macrophyllum; understory of Sambucus racemosa and Rubus s p e c t a b i l i s . 2 2 495 South as above 3 3 463 East On edge of dense grove of Acer macro-phyllum; t a l l understory of _S. racemosa. 4 4 441 East Dense understory of Acer circinatum and S. racemosa; few trees i n the immediate are area. 5 5 536 East Open grove, p a r k l i k e . Dense understory of R. s p e c t a b i l i s . 6 6 470 East as above 7 7 565 North Open grove, few surrounding trees. Low understory of R. s p e c t a b i l i s and U r t i c a d i o i c a var. l y a l l i i . 8 8 593 West Open grove, few surrounding trees. Low understory of U. d i o i c a , R. s p e c t a b i l i s , R. parviflorus,some Oplopanax horridus. 9 9 600 North Open grove, few surrounding trees. Low understory dominated by R. s p e c t a b i l i s and S. racemosa. Table 12. General information on trees sampled at SQU. 62 Stand Study DBH Dir e c t i o n Location (nature of the surrounding Tree Tree (mm) of Lean vegetation, trees and shrubs) 10 10 414 South Dense stand of A. macrophyllum, Alnus rubra, and Tsuga heterophylla. Understory mainly R_. s p e c t a b i l i s . 11 11 616 South Open grove, some A. rubra and A. c i r c i n a -tum nearby. Understory dense, mostly R. s p e c t a b i l i s . 12 12 530 North F a i r l y dense grove of A. macrophyllum, some T_. heterophylla and A. rubra. Dense understory , R. s p e c t a b i l i s and R. p a r v i -f l o r u s dominant. 13 13 442 North Open grove, i n area dominated by A. macro-phyllum. Dense understory of R. spectab-i l i s . 14 14 536 North F a i r l y dense grove of A. macrophyllum and A. circinatum. Dense understory of R. s p e c t a b i l i s and S. racemosa. 15 15 537 South as above Table 12. continued. 63 Stand Tree Study Tree DBH (mm) Dir e c t i o n of Lean Location (nature of the surrounding vegetation, trees and shrubs) 1 16 815 South Dense stand of mostly Acer macrophyllum. Understory of Polystichum munitum; Sambucus racemosa, clumps of Rubus spect-i l i s i n nearby depressions. 2 17 581 South Mixed A. macrophyllum and Thuja p l i c a t a . Many young Tsuga heterophylla (to 10m) i n the area. Sparse understory of P. munitum. 3 18 863 South Dense stand of mostly A. macrophyllum. Understory of P. munitum; dense stands of S. racemosa and R. s p e c t a b i l i s nearby. 4 19 738 West More open stand of A. macrophyllum. Understory of S. racemosa and R. spect-a b i l i s , some Athyrium felix-femina. 5 20 683 West More open stand of A. macrophyllum. Understory of P. munitum, R. spectab-i l i s occasional. 6 21 785 North Mixed stand, A. macrophyllum and T. p l i c -ata. Saplings of T. heterophylla common. Sparse understory of P. munitum, some Dryopteris austriaca. 7 22 686 South as above 8 23 668 East as above Table 13. General information on trees sampled at FUR. 64 Stand Study DBH D i r e c t i o n Location (nature of the surrounding Tree Tree (mm) of Lean vegetation, trees and shrubs) 24 698 South 10 11 12 13 14 25 812 26 27 28 29 674 627 593 765 West South West West East Mixed A. macrophyllum, _T. p l i c a t a stand. Sparse understory of P_. muni turn, occas-i o n a l I), austriaca. Saplings of T. hetero-p h y l l a common i n the area. Dense stand, mostly A. macrophyllum. Sparse understory of P_. munitum, some p_. a u s t r i a c a ; R. s p e c t a b i l i s and S_. race-mosa i n nearby depressions. as above. as above Dense stand, mostly A. macrophyllum. Sparse understory of P_. munitum. More open area, mixed A. macrophyllum, T_. p l i c a t a , and T\ heterophylla. R. spect- a b i l i s and S_. racemosa i n the understory , and with P. munitum and D. austriaca. 15 30 808 South as above Table 13. continued. 65 Stand Study DBH D i r e c t i o n Location (nature of the surrounding Tree Tree (mm) of Lean vegetation, trees and shrubs) 31 625 West 5 6 7 8 9 10 32 33 34 442 609 567 35 594 36 561 37 635 38 578 39 470 40 651 East West West West South North North South South Dense grove, mostly Acer macrophyllum. Understory low and sparse, mostly Poly- stichum munitum and Dryopteris austriaca. Dense grove, mostly A. macrophyllum. Patchy understory of P_. munitum, 13. aust-r i a c a ; occasional Symphoricarpos albus and Rubus s p e c t a b i l i s . More open stand of A. macrophyllum. Open area nearby with dense R. s p e c t a b i l i s and j3. racemosa understory . as above as above as above Tree i n exposed area, at edge of grove. Dense understory of R. s p e c t a b i l i s , S_. racemosa. Galium t r i f l o r u m and bryophytes common on the forest f l o o r . as above as above Dense stand of A. macrophyllum, Thuja  p l i c a t a , and Pseudotsuga menziesii. Sparse understory of Polystichum munitum. Table 14. General information on trees sampled at UEL. 66 Stand Study DBH D i r e c t i o n Location (nature of the surrounding Tree Tree (mm) of Lean vegetation, trees and shrubs) 11 Al 614 East Similar to the above, but more open. Occasional stands of R. s p e c t a b i l i s nearby. 12 13 42 43 671 543 West South as above Dense stand of A. macrophyllum, T_. p l i c a t a , Pseudotsuga menziesii , some Tsuga hetero- p h y l l a . Sparse understory of P_. munitum,  Galium t r i f l o r u m , and JJ. austriaca. 14 44 472 South as above 15 45 638 South as above Table 14. continued. 67 Stand Study DBH D i r e c t i o n Location (nature of the surrounding T r e e T r e e (mm) of Lean vegetation, trees and shrubs) 3 4 5 7 8 46 51 52 53 498 47 591 48 470 49 520 50 542 445 449 416 54 452 West North East North East South South East F a i r l y dense stand of Acer macrophyllum. Understory dense, mostly Rubus s p e c t a b i l i s , as above as above South as above as above, but with Sambucus racemosa and Oemleria cerasiformis occasional i n the understory with R. s p e c t a b i l i s . Less dense stand of A. macrophyllum, more open area. Very dense understory of Rubus  s p e c t a b i l i s . as above Less dense stand of A. macrophyllum, with saplings of Tsuga heterophylla to 12 m. Understory of R. s p e c t a b i l i s , Dryopteris  a u s t r i a c a , and Polystichum munitum. Less dense stand of A. macrophyllum; open area with R. s p e c t a b i l i s , I), aus t r i a c a , S_. racemosa, and P_. munitum forming a dense understory . Table 15. General information on trees sampled at PIT. 68 Stand Study DBH D i r e c t i o n Location (nature of the surrounding Tree Tree (mm) of Lean vegetation, trees and shrubs) 10 55 414 East F a i r l y dense, mixed stand of A. macro-phyllum, _T. p l i c a t a (large trees) , and T_. heterophylla (saplings to 15 m). Under-story i s dense (R. s p e c t a b i l i s dominating) to sparse (P. munitum common). 11 56 626 South as above 12 57 578 East F a i r l y open area, mostly A. macrophyllum. Very dense understory of R. s p e c t a b i l i s and S_. racemosa. 13 58 478 South as above 14 59 515 South Dense stand, mixed A. macrophyllum and T_. heterophylla. Understory of P_. munitum, I), a u s t r i a c a , with occasional stands of R. s p e c t a b i l i s . 15 60 403 East as above Table 15. continued. 69 Stand Study DBH D i r e c t i o n Location (nature of the surrounding Tree Tree (mm) of Lean vegetation, trees and shrubs) 61 671 62 694 63 683 West West North 64 683 North Dense stand of Acer macrophyllum, Tsuga  heterophylla, and Thuja p l i c a t a . Conifers are generally younger (to 20 m). Sparse understory of Polystichum munitum. as above. Understorey with Athyrium  felix - f e m i n a i n nearby depressions. Dense stand, mixed A. macrophyllum and T_. p l i c a t a . A few saplings of _T. heterophy-l l a also present. Sparse understory of P_. munitum, some Oplopanax horridus. as above 5 65 737 North as above 6 66 796 West Less dense than the above areas. A. macro-phyllum, Alnus rubra, and J_. heterophylla dominate the canopy. Understory of P_. mun- itum, with stands of Rubus p a r v i f l o r u s , Rubus s p e c t a b i l i s , Sambucus racemosa, and Oplopanax horridus nearby. 7 67 580 North as above 8 9 68 542 West 69 550 West as above as above, but no 0_. horridus or R. spectab-i l i s i n the understory . S. racemosa occ-asional. Table 16. General information on trees sampled at BRI. 70 Stand Tree Study Tree DBH (mm) D i r e c t i o n of Lean Location (nature of the surrounding vegetation, trees and shrubs) 10 70 628 East Dense stand of A. macrophyllum, with saplings of T. heterophylla and T. p l i c a t a to 15 m. Very shaded. Understory sparse, mostly P. munitum. 11 71 7A1 West as above 12 72 555 West as above 13 73 782 West Less dense stand, mostly A. macrophyllum. Conifer saplings occasional. P. munitum i n the understory , with stands of R. p a r v i f l o r u s , S. racemosa, and some R. s p e c t a b i l i s i n lower areas. 1A 7A 600 West as above 15 75 6A6 North as above Table 16. continued. 71 the c h o i c e o f which method to use i s somewhat co n t e x t - d e p e n d e n t . Choice i s dependent upon the o b j e c t i v e s of the i n v e s t i g a t i o n , on the q u e s t i o n s b e i n g asked, t h e s a m p l i n g method used, and even t h e n a t u r e of t h e v e g e t a t i o n ( c o n t i n u o u s v s . . d i s c r e t e ) .. While both methods e f f i c i e n t l y summarize i n f o r m a t i o n c o n t a i n e d i n a d a t a s e t , they do so i n very d i f f e r e n t w a y s . . O r d i n a t i o n methods are most u s e f u l i n v e g e t a t i o n a l t r e n d - s e e k i n g and h y p o t h e s i s t e s t i n g , whereas a c l a s s i f i c a t o r y approach i s a p p r o p r i a t e f o r d e s c r i b i n g and c h a r a c t e r i z i n g v e g e t a t i o n a l u n i t s . t h o u g h t t o e x i s t i n the f i e l d . I n the p r e s e n t study both s t r a t e g i e s have been employed, depending upon t h e i r a p p r o p r i a t e n e s s i n d i f f e r e n t s i t u a t i o n s and the q u e s t i o n s b e i n g asked. O r d i n a t i o n Methods Most o r d i n a t i o n s t r a t e g i e s used i n p h y t o s o c i o l o g y a r e m u l t i v a r i a t e methods of component a n a l y s i s o r v a r i a t i o n s t h e r e o f . . S u c h methods e x t r a c t e i g e n v a l u e s (A) and e i g e n v e c t o r s (v) from a c r o s s - p r o d u c t s m a t r i x (R) which s a t i s f y t h e c h a r a c t e r i s t i c e g u a t i o n Rv=Av. E i g e n v a l u e s and e i g e n v e c t o r s are e x t r a c t e d i n o r d e r o f i m p o r t a n c e . The e x t r a c t e d e i g e n v e c t o r s r e p r e s e n t d i r e c t i o n a l c o s i n e s r e l a t i n g t h e s p e c i e s axes t o new component axes. These component axes are thus m a t h e m a t i c a l l y and e c o l o g i c a l l y complex. Component a n a l y s i s i s an e f f i c i e n t method of d a t a s u m m a r i z a t i o n s i n c e t h e e x t r a c t e d component a x e s , u n l i k e the o r i g i n a l s p e c i e s 72 a xes, are uncorrelated..Component a n a l y s i s i n c o r p o r a t e s a l i n e a r d e f i n i t i o n of the s t r u c t u r e of a data s e t . Thus, l i n e a r t r e n d s i n the data s e t are e f f i c i e n t l y summarized, but n o n - l i n e a r ones may go u n d e t e c t e d . . U n f o r t u n a t e l y , t h e d e t e c t i o n of n o n - l i n e a r t r e n d s i s so m a t h e m a t i c a l l y complex and so wrought with problems of d e f i n i t i o n o f a l t e r n a t i v e t y p e s of v a r i a t i o n ( G a u s s i a n or o t h e r w i s e ) t h a t l i n e a r models a r e the o n l y r e a l a l t e r n a t i v e ( O r l o c i 1978). The problem of n o n - l i n e a r i t y , which may be common i n . e c o l o g i c a l s i t u a t i o n s , can be m i n i m i z e d by r e s t r i c t i n g s a m p l i n g t o a r e l a t i v e l y narrow segment of a presumed e n v i r o n m e n t a l g r a d i e n t ( A u s t i n and Noy-Meir 1971). N o n e t h e l e s s , because th e method summarizes o n l y l i n e a r v a r i a t i o n , the e x t r a c t e d component axes cannot i n g e n e r a l be i n t e r p r e t e d as c o r r e s p o n d i n g d i r e c t l y t o e n v i r o n m e n t a l g r a d i e n t s ; however, i n many s i t u a t i o n s e x t r a c t e d axes are r e a d i l y i n t e r p r e t a b l e e c o l o g i c a l l y ( N i c h o l s 1977, O r l o c i 1978). The e v a l u a t i o n of o r d i n a t i o n t e c h i g u e s s u i t a b l e f o r p h y t o s o c i o l o g i c a l a p p l i c a t i o n s i s an ongoing stu d y . . N i c h o l s (1977) has p o i n t e d out t h a t t h e a p p r o p r i a t e n e s s of a g i v e n t e c h n i q u e i s dependent upon t h e needs of the i n v e s t i g a t o r . . T h u s , p r i n c i p a l components a n a l y s i s (PCA), which i s a u s e f u l model f o r d a t a r e d u c t i o n and h y p o t h e s i s g e n e r a t i o n , i s i l l - s u i t e d f o r the e l u c i d a t i o n of u n d e r l y i n g e n v i r o n m e n t a l g r a d i e n t s . . A u s t i n (1976), however, c o n s i d e r s t h a t d a t a r e d u c t i o n (or s ummarization) and the d e t e c t i o n of e c o l o g i c a l g r a d i e n t s to be i n s e p a r a b l e so f a r as o r d i n a t i o n e f f i c i e n c y i s c o n cerned, i f t h e r e s u l t s a r e t o be e c o l o g i c a l l y s i g n i f i c a n t . Recent work on the e v a l u a t i o n of t h e s e t e c h n i q u e s u s i n g s i m u l a t e d c o e n o c l i n e s and 73 c o e n o p l a n e s (Gauch, W h i t t a k e r , and Wentworth 1977, Fasham 1977, W h i t t a k e r and Gauch 1973), a l t h o u g h somewhat c o n f l i c t i n g , r e v e a l t h a t e n v i r o n m e n t a l g r a d i e n t s are best r e p r o d u c e d by R e c i p r o c a l A v e r a g i n g (RA) and worse by PCA. T h i s s u g g e s t s t h a t RA may be the b e s t l i n e a r component model so f a r as o r d i n a t i o n e f f i c i e n c y i s c o n c e rned (however, see comments i n O r l o c i 1978). . M u l t i v a r i a t e methods used i n t h e p r e s e n t s t u d y are d i s c u s s e d below. A l l a n a l y s e s were performed u s i n g programs developed by Dr. G. E. B r a d f i e l d . R e c i p r o c a l A v e r a g i n g (RA) T h i s e i g e n v e c t o r method was f i r s t d e s c r i b e d as a p n y t o s o c i o l o g i c a l t o o l by H i l l (1973, 1974)..While the a l g o r i t h m d i f f e r s s i g n i f i c a n t l y from PCA, m a t h e m a t i c a l l y the two methods are g u i t e s i m i l a r . . D i f f e r e n c e s l i e i n t h e d a t a a d j u s t m e n t s of the e lements of t h e e i g e n v e c t o r s ( O r l o c i 1978)..In RA, the e x t r a c t e d axes a r e c a n o n i c a l v a r i a t e s , w i t h t h e f i r s t a x i s r e p r e s e n t i n g the maximum c a n o n i c a l c o r r e l a t i o n i n the d a t a s e t . Subseguent axes summarize the r e m a i n i n g c a n o n i c a l c o r r e l a t i o n , and can be thought o f as axes which c o r r e c t f o r the f i r s t (Gauch 1977). RA has a t w o - f o l d purpose: g u a d r a t s a r e o r d i n a t e d on the b a s i s o f s p e c i e s s c o r e s and v i c e v e r s a . Thus, the a n a l y s i s produces both a s p e c i e s and g u a d r a t o r d i n a t i o n which complement one a n o t h e r . The method tends t o be s e n s i t i v e t o r a r e s p e c i e s and anomalous q u a d r a t s * I t i s t h e r e f o r e o f t e n recommended t h a t t h e s e be removed b e f o r e p e r f o r m i n g t h e a n a l y i s (Noy-Meir and W h i t t a k e r 1978). The a l g o r i t h m used i n t h e p r e s e n t study i s the same as d e s c r i b e d i n H i l l (1973), e x c e p t f o r the adjustment o f 74 t h e range of the c a n o n i c a l v a r i a t e s (see O r l o c i 1978). RA i s used here t o o r d i n a t e t r e e s (based upon t h e i r e p i p h y t i c v e g e t a t i o n ) , and as a t o o l t o d e t e c t response of the v e g e t a t i o n t o presumed m i c r o e n v i r o n m e n t a l g r a d i e n t s . P r i n c i p a l C o - o r d i n a t e s A n a l y s i s (P-Co-A) T h i s method i s e s s e n t i a l l y a d e r i v e d form of PCA a p p l i c a b l e to resemblance m a t r i c e s o t h e r than the c o r r e l a t i o n or c o v a r i a n c e . Gower (1966) showed t h a t the same r e s u l t s can be computed u s i n g a resemblance m a t r i x between i n d i v i d u a l s as a c o v a r i a n c e or c o r r e l a t i o n m a t r i x o f a t t r i b u t e s (as i n PCA), p r o v i d e d t h a t the same s t a n d a r d i z a t i o n s are used. Thus P-Co-A d i f f e r s from PCA i n the adjustment of the c r o s s - p r o d u c t s (resemblance) m a t r i x p r i o r t o t h e e x t r a c t i o n o f component axes. The advantage over PCA i s t h a t any resemblance measure thought by the i n v e s t i g a t o r t o be a p p r o p r i a t e can be used. P-Co-A was used i n t h e p r e s e n t study t o o r d i n a t e s p e c i e s i n o r d e r t o study t h e i r a s s o c i a t i o n . The s i m i l a r i t y between th e e p i p h y t i c s p e c i e s was d e f i n e d by the c o s - t h e t a f u n c t i o n e x p r e s s e d a s : C O S ( 0 ) = X | j X hi * 2 * 2 X i j and Xhj denote performance ( l o c a l frequency) of s p e c i e s i and h i n quadrat j , and n i s t h e t o t a l number of q u a d r a t s . . T h i s 75 c o e f f i c i e n t i g n o r e s the r e l a t i v e magnitudes between the s p e c i e s v e c t o r s , b e i n g concerned o n l y w i t h the a n g l e s between them. The cos t h e t a f u n c t i o n d i f f e r s from th e product-moment c o r r e l a t i o n c o e f f i c i e n t i n b e i n g based upon d e v i a t i o n from th e o r i g i n r a t h e r than t h e group mean (Anderberg 1973). C l a s s i f i c a t o r y Methods As i n o r d i n a t i o n , a number of methods of c l a s s i f i c a t i o n are of use t o t h e p h y t o s o c i o l o g i s t . . T r a d i t i o n a l methods of t h e B r a u n - B l a n g u e t s c h o o l have been a p p l i e d t o e p i p h y t i c v e g e t a t i o n i n Europe (Barkman 1958, S j o g r e n 1961) and Japan ( I w a t s u k i 1960), and are d i s c u s s e d i n d e t a i l i n Barkman (1973) and Westhoff and van der M a a r e l (1-973). I n North America, s u b j e c t i v e d e l i m i t a t i o n of e p i p h y t i c v e g e t a t i o n was used by B i l l i n g s and Drew (1938), S z c z a w i n s k i (1954), and Hoffman and K a z m i e r s k i (1969). C l u s t e r a n a l y s i s i s a n o t h e r u s e f u l t o o l i n d e l i m i t i n g v e g e t a t i o n a l u n i t s , and has been used i n e p i p h y t i c s t u d i e s by J e s b e r g e r and Sheard (1973). A number o f c l u s t e r i n g a l g o r i t h m s a r e a v a i l a b l e (Sneath and S o k a l 1973, O r l o c i 1978, and Anderberg 1973) . . I n the p r e s e n t s t u d y , th e c l u s t e r i n g a l g o r i t h m d e s c r i b e d by Ward (1963) was used to d e l i m i t and c h a r a c t e r i z e the e p i p h y t i c v e g e t a t i o n a t the 5 s i t e s . The a l g o r i t h m i s a h i e r a r c h i c a l g r o u p i n g method where f u s i o n o f groups i s dependent upon an • o b j e c t i v e f u n c t i o n ' (the sguared c e n t r o i d d i s t a n c e of groups weighted by group s i z e ) , which i s an o b j e c t i v e measure of the d e s i r a b i l i t y of group f u s i o n . . The method produces s p h e r i c a l , 76 w e l l - b a l a n c e d groups ( O r l o c i 1978, Sneath and S o k a l 1973). C l u s t e r a n a l y s i s was performed u s i n g the MIDAS s t a t i s t i c a l package (Fox and G u i r e 1976).. 77 CHAPTER 6 - ORDINATION OF TREES BASED ON THEIR EPIPHYTIC VEGETATION In t h i s c h a p t e r , d i f f e r e n c e s between t r e e s (based upon t h e i r e p i p h y t i c v e g e t a t i o n ) a t each o f t h e s i t e s are examined. An a t t empt i s made t o e x p l a i n t h e s e d i f f e r e n c e s based upon f i e l d o b s e r v a t i o n s of m i c r o h a b i t a t v a r i a t i o n between the t r e e b o l e s . A l s o , the e x t e n t t o which the s i t e s a r e d i s t i n g u i s h a b l e from one an o t h e r i n terms of t h e e p i p h y t i c v e g e t a t i o n on the i n d i v i d u a l t r e e s a r e examined. An attempt i s made t o d i s c e r n which e n v i r o n m e n t a l f a c t o r s may be r e s p o n s i b l e f o r b e t w e e n - s i t e d i f f e r e n c e s i n e p i p h y t i c v e g e t a t i o n on Acer macrophyllum. I n d i v i d u a l Tree O r d i n a t i o n s -I n an attempt t o examine i n h e r e n t v a r i a b i l i t y i n e p i p h y t i c v e g e t a t i o n between t r e e s , a mean freguency o f each of the e p i p h y t i c s p e c i e s found growing on a g i v e n t r e e was computed. T h i s i s a j u s t i f i a b l e p r o c e d u r e s i n c e each t r e e r e p r e s e n t s a unigue e c o l o g i c a l e n t i t y ( o r m i c r o s i t e ) i n terms of i t s s i z e , age, degree of i n c l i n a t i o n , and l o c a t i o n w i t h i n the f o r e s t . U s i n g c o l l e c t e d d a t a on m i c r o e n v i r o n m e n t a l v a r i a b i l i t y between the t r e e b o l e s (Tables 12-16), s p e c i f i c g u e s t i o n s r e g a r d i n g the re s p o n s e of t h e e p i p h y t i c v e g e t a t i o n t o changes i n t r e e s i z e , and d i f f e r e n c e s i n t h e microenvironment of t h e f o r e s t can be answered.. Each s i t e has been a n a l y z e d s e p a r a t e l y . _ T h e 15 t r e e s a t a 78 g i v e n s i t e were o r d i n a t e d u s i n g RA. B e f o r e th e a n a l y s e s were r u n , s p e c i e s o c c u r r i n g i n 18 or fewer (5%) o f t h e 360 g u a d r a t s at a s i t e were removed t o keep them from d o m i n a t i n g th e a n a l y s i s . . The r e s u l t s f o r each o f t h e 5 s i t e s a r e d i s c u s s e d i n t u r n below.. SQU T a b l e 17 summarizes the e p i p h y t i c s p e c i e s f r e q u e n c i e s on each o f the 15 t r e e s at t h i s s i t e ; F i g u r e 17 shows the r e s u l t a n t t r e e o r d i n a t i o n . The f i r s t component a x i s a c c o u n t s f o r 49.13% of t h e v a r i a t i o n , t h e second 22.49%. A t o t a l of 7 p o s i t i v e e i g e n v a l u e s were e x t r a c t e d from a m a t r i x of 8 e p i p h y t i c s p e c i e s . On t h e f i r s t a x i s , Neckera d o u g l a s i i , P o r e l l a cordaeana, M2JlSi2ihecium f u l q e s c e n s , and Homalia trichomanoid.es have h i g h p o s i t i v e w e i g h t i n g ; Metaneckera m e n z i e s i i i s n e g a t i v e l y w e i g h t e d . . On the second a x i s , L e p r a r i a raerabranacea has h i g h p o s i t i v e weight; the s p e c i e s M^ m e n z i e s i i , i l l t i t r i c h i a c a l i f o r n i c a , P._.cordaeana, Homalothecium f u i a e s c e n s , and H t_trichomanoid.es i s n e g a t i v e l y weighted. Trees 7, 8, and 9 are w e l l d i s t i n g u i s h e d from the o t h e r s ; They a l l have h i g h f r e g u e n c y v a l u e s of Metaneekera m e n z i e s i i , and a r e some of the l a r g e r t r e e s sampled. They a r e l o c a t e d i n a r e l a t i v e l y open, exposed grove (Table 12) . Trees 4 , 10, 12, and 14 form a r e l a t i v e l y w e l l - d i s t i n g u i s h e d group on the second a x i s . . T h e s e t r e e s show a h i g h f r e g u e n c y of L e p r a r i a membranacea, and a r e l o c a t e d i n more dense, c l o s e d stands..They are a l s o some of t h e s m a l l e r t r e e s sampled. Tree 2 , which o c c u r s toward t h e bottom of the o r d i n a t i o n , i s a s m a l l e r t r e e w i t h lower t o t a l ( l e t a n e c k e r a men z i e s i i  L e p r a r i a mem b r a na cea H o a a l o t h e c i u n f u l q e s c e n s  H e c k e c a d o u q l a s i i  C l a o p o d i ua c t i s p i f c l i u n  P o r e l l a c o r d a e a n a  I s o t h e c i um s t o l o n i f e r u m  H o a a l o t h e c i u n r u t t a l l i i  Iygodon v i r i d i s s i a u s  P o r e l l a n a v i c u l a r i s  P l a g i o a n i u a Ten o s t u n  P o l y p o d i u a q l y c y r t h i z a A p j a e t z g e r i a p u f c e s c e n s  A n t i t r i c h i a c a l i t o r n i c a  H o m a l i a t r i c h o m a n o i d e s  L e u c o l e p i s m r n z i e s i i  H y p n u a s u b i n p o n e n s  S t o k e s i e l l a p r a e l o n q a  G r a ph i s s c r i p t a  A n t i t r i c h i a c u r t i p e n d u l a  O t t h o t r i c h u m 1 y e l 1 i i H h y t i d i a d e l p h ' i s t r i q t i e t r u s 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 8.5H 6 . 2 9 2 . 9 2 8 . 6 3 2 . 3 8 6 . 6 3 2 5 . 21 2 0 . 0 0 2 1 . 0 8 5 . 2 9 12. 13 2 . 8 3 1. 50 6 . 6 7 12. 80 0 . 7 1 0 . 0 2 0 . 3 3 1 0 . 5 0 2 . 2 1 1 . 2 5 1 1 . 8 8 7 .50 3 . 2 5 1 7 . 0 0 4 . 2 1 1 3 . 9 2 2 . 0 2 12. 25 7. 13 6.H2 1 3 . 2 9 1 1 . 9 2 2 . 9 2 6 . 29 7 . 2 5 0 . 21 6 . 21 0 . 6 3 1 2 . 9 6 1 3 . 6 7 1 2 . 7 5 7. 38 1 1 . 96 1 2 . 5 0 12. 75 3 . 9 2 1 0 . 9 6 13.38 2 0 . 08 18. 21 8 . 2 5 0 . 3 8 2 . 58 1 6 . 2 5 6 . 38 14. 79 2 5 . 13 1 0 . 5 0 9 . 33 0 . 0 0 . 0 0 . 0 0 . 5 0 0 . 2 5 0 . 0 2 . 0 0 0 . 0 2 . 17 0 . 5 0 0 . 0 1 . 0 2 0 . 2 5 0 . 5 0 0 . 5<4 2. 08 5 . 6 3 5 . 7 9 2 . 5 0 2 . 8 3 5 . 8 8 0 . 0 0 . 6 7 0 . 0 1 . 17 3 . 17 3 . 0 0 0.51 1 . 6 7 2 . 50 0 . 0 0 . 0 0 . 0 0 . 0 0 . 5 0 0 . 0 0 . 0 0 . 0 0 . 0 0 . 0 0 . 6 7 0 . 0 o . o o . o b . o o . o 1. 16 0 . 0 0 . 0 0 .0 0 . 0 0 . 0 0 . 0 1. 29 3 . 1 6 0 . 5 0 0 . 3 8 0 . 0 1 .83 0 . 0 0 . 0 0 . 7 1 0 . 0 C O 0 . 5 0 0 . 2 1 0 . 0 0 . 0 0 . 0 0 . 0 0 .0 0 . 0 0 . 0 0 . 0 0 . 0 0 . 0 0 . 0 0 . 0 0 . U 6 3 . 13 2 . 9 2 1. 00 0 . 13 0. 38 0 . 0 0 . 13 0 . 0 1. 71 0 . 06 0 . 0 1.96 0 . 0 8 0 . 33 2 . 17 0 . 3 8 2 . 0 0 1 . 0 2 0 . 2 1 2 . 13 3 . 8 3 1 . 0 8 5 . 50 2. 21 1. 7 1 5 . 63 0 . 17 0 . 0 0 . 13 0 . 17 1 . 5 0 0 . 0 0 . 0 0 . 0 0 . 0 0 . 0 0 . 0 0 . 0 0 . 0 0 . 0 2. 58 2 . 7 5 1.83 6 . 9 6 2 . 6 3 2 . 00 0 . 0 0 . 0 1 . 3 3 0 . 5 8 0 . 0 0 . 0 1 . 06 0 . 6 7 0 . 0 5 . 0 8 9 . 2 9 0 . 0 0. 0 1. 29 0 . 0 0 . 79 0 . 29 0 . 0 0 . 13 0 . 0 0 . 0 1. 29 1. 75 2. 06 5. 63 8 . 0 0 3 . 0 2 6 . 33 6 . 2 5 11 . 5 0 5 . 02 3 . 92 0 . 5 8 5 . 33 0 . 5 0 9 . 21 7 . 33 6. 06 8 . 0 0 8 . 92 0 . 0 0 . 0 0 . 0 0. 0 0 . 0 0 . 0 1. 50 0. 67 0 . 0 0 .0 0 . 25 0 . 0 0 . 0 0. 17 3 . 8 3 1. 17 0 . 0 0 .0 1 .08 0 . 38 0 . 0 0. 0 0 . 0 0 . 33 0 .0 0 . 0 0 . 0 0. 02 0 . 0 0 . 29 3 . 5 8 0 . 38 0 . 0 0 . 2 1 0 . 0 0 . 3 3 0 .0 0 . 0 0 . 0 0. 17 0 . 0 0 . 0 0 . 0 0 . 6 7 0 . 0 0 . 0 0 . 0 0 . 0 0 . 0 0 . 0 0 . 0 0 . 0 0 . 0 0 . 0 0 . 0 0 . 6 3 0 . 2 1 0 . 0 0 . 0 0 . 0 0 . 2 1 0 . 0 0 . 0 0 . 0 0 . 0 0 . 0 1 . 2 9 0 . 3 8 0 . 0 3 . 2 5 0 . 0 0 . 0 0 . 75 0 . 0 0 . 0 0 . 0 0 . 96 0 . 0 0 . 0 0 . 0 0 . 0 0 . 0 0 . 0 0 . 0 0 . 0 0 . 6 3 1 .71 0 . 0 0 . 0 0 . 0 0 . 0 0. 33 0 . 0 0 . 0 0 . 0 0 . 0 0 . 21 0 . 2 5 0 . 0 1.06 0 . 0 0 . 13 0 . 0 0 . 0 1. 00 Table 17. Mean l o c a l frequency (maximum = 50) of epiphytic species on the 15 trees sampled at SQU. 80 10 4 12 7 14 5 13 15 8 11 1 6 3 9 2 •I Figure 17. Reciprocal averaging ordination of i n d i v i d u a l t (based upon t h e i r epiphytic vegetation) at SQU. 81 s p e c i e s f r e g u e n c y than th e o t h e r s . Trees 3, 5, 6, and 13, which ar e p o s i t i o n e d t o t h e r i g h t on the f i r s t a x i s , show h i g h f r e g u e n c y of Neckera d o u g l a s i i . These t r e e s a r e i n more open a r e a s or at t h e edge of g r o v e s . They a l s o tend t o be somewhat s m a l l e r t r e e s . FUR T a b l e 18 summarizes e p i p h y t i c frequency on t h e 15 t r e e s a t t h i s s i t e , and F i g u r e 18 shows the r e s u l t a n t o r d i n a t i o n . The f i r s t component a x i s accounts f o r 51.54% of the t o t a l v a r i a t i o n , the second 10.16%.. A t o t a l o f 9 p o s i t i v e e i g e n v a l u e s were e x t r a c t e d from a m a t r i x of 10 e p i p h y t i c s p e c i e s . Neckera d o u g l a s i i , I s o t h e c i u m s t o l o n i f e r u m , and D e n d r g a l s i a a b i e t i n a have h i g h p o s i t i v e weight on t h e f i r s t a x i s , w h i l e Metaneckera m e n z i e s i i , C l a o p o d i um c r i s p i f p l i u m , Zygodon v i r i d i s s i m us, P o r e l l a n a v i c u l a r i s , and P p r e l l a cprdaeana a r e a l l n e g a t i v e l y w e i g h t e d . On the second a x i s , Homalothecium f u l q e s c e n s , - cor d aean a, and N. . d o u g l a s i i a r e p o s i t i v e l y w e i g h t e d ; . men z i e s i x , P... n a v i c u l a r i s , Z. y i r i d i s s i m u s , L e p r a r i a msmbranacea, and D._ a b i e t i n a a r e weighted n e g a t i v e l y . T r e e s 1, 6, 9, 11, and 14 show a h i g h f r e g u e n c y of i s o t h e c i u m s t o l o n i f e r u m , and a r e t h u s p o s i t i o n e d t o the r i g h t bn the f i r s t a x i s . These t r e e s g e n e r a l l y occur w i t h i n dense s t a n d s (Table 1 3 ) , a l t h o u g h t r e e 14 i s l o c a t e d i n a more open a r e a . Tree 2, which i s p o s i t i o n e d toward the bottom of t h e o r d i n a t i o n , has h i g h f r e g u e n c y v a l u e s o f Zygpdon y i r i d i s s i m u s , P o r e l l a n a y i c u l a r i s , and I., s t o l o n i f erum. I t was the s m a l l e s t t r e e sampled, and i s l o c a t e d i n a very dense area of the f o r e s t . Tree 82 3, l o c a t e d a t t h e bottom l e f t of t h e o r d i n a t i o n , has a h i g h f r e g u e n c y of Metaneckera m e n z i e s i i . T h i s was the l a r g e s t t r e e sampled, and i s l o c a t e d w i t h i n a dense s t a n d o f Acer macrophyllum. The r e m a i n i n g t r e e s a r e f a i r l y s i m i l a r i n t h e i r o v e r a l l f l o r i s t i c c o m p o s i t i o n , a l t h o u g h d i f f e r e n c e s are a p p a r e n t . These t r e e s o c c u r i n both open and more dense area s o f the f o r e s t . UEL E p i p h y t i c f r e g u e n c y v a l u e s f o r each of t h e 15 t r e e s at t h i s s i t e a r e shown i n Table 19; F i g u r e 19 shows t h e r e s u l t a n t t r e e o r d i n a t i o n . The f i r s t component a x i s a c c o u n t s f o r 35.60% of the v a r i a t i o n , t h e second 25.85%..A t o t a l of 9 p o s i t i v e e i g e n v a l u e s were e x t r a c t e d from a m a t r i x of 10 e p i p h y t i c s p e c i e s . Mgianeckera m e n z i e s i i , Zyggdpn y i r i d i s s i m u s , Homalothecium n u t t a l l i i , Claoppdium c r i s p i f o l i u m , and P p r e l l a cprdaeana a l l show h i g h p o s i t i v e w e i g h t i n g on t h e f i r s t a x i s ; I s o t h e c i u m s t o l o n i f e r u m and L e p r a r i a membranacea both show n e g a t i v e w e i g h t i n g . On t h e second a x i s , P g r e l l a egrdaeana and Clagppdium c r i s p i f g l i u m show s t r o n g p o s i t i v e w e i g h t i n g , w h i l e Lj__ membranacea , Z. , y i r i d i s s i m u s , Mj_. m e n z i e s i i , and H._ n u t t a l l i i a r e n e g a t i v e l y weighted.. Trees 1, 10, 13, and 14, which o c c u r a t the lower r i g h t of the o r d i n a t i o n , a l l show a h i g h f r e g u e n c y of Metaneckera m e n z i e s i i ; t h e s e t r e e s tend t o o c c u r i n t h e denser a r e a s o f t h e f o r e s t . Trees 2, 4, 5, 6, 7, 8, and 9, which a r e p u l l e d to t h e l e f t o f the o r d i n a t i o n , have h i g h f r e g u e n c y v a l u e s of I s o t h e c i u m s t o l o n i f e r u m . These t r e e s tend t o o c c u r i n more open, exposed Wetaneckera m e n z J E s i i  L e p r a r i a memhranacea  Horcalothec ium f u 1qescens  Meckera douq l a s i i  C l a o F o d i ua c r i s p i f c l t u n  P o r e l l a cordaeana  I s o t h e c i u a s to Ion i f eriim  H c n a l o t h e c i u a n u t t a l l i i  Den d r o a l s i a a b l e t i n a  Z y j o d o n v i r i d i s s i m u s  P o c e l l a n a v i c u l a r i s  P l a q i o m n i um ven ustua  P r u l l a n i a t a r o a r i s c i  P o l y p o d i u a q l y c y r r h i z a  kpometzqcria p u t e s c e n s  L e u c o l e p i s m e n z i e s i i  Hypnua subinponens  S t o t e s i e l l a p r a e l c n q a  A n t i t r i c h i a c u r t i t e n d u l a  O r h t o t r i c h u m l y e l 1 i i L o p h o c o l e a c u s p i d a t a Table 18. Mean l o c a l 1 0 . 5 8 7 . 7 1 0 . 7 5 5 . 8 8 5 . 7 5 2 . 2 9 1 7 . 8 3 1 . OO 1 2 . 6 7 1 . 7 9 0 . 0 0 . 2 1 0 . 0 0 . 9 2 0 . 0 0 . 0 0 . 0 0 . 0 0 . 0 0 . 0 0 . 0 2 1 2 . 5 8 1 6 . 2 9 0 . 7 1 4 . 4 6 1 3 . 7 9 1 . 7 5 3 . 3 3 0 . 0 9 . 7 1 7 . 0 8 7 . 7 5 0 . 0 3 . 5 8 3 . 3 3 0 . K 6 0 . 0 0 . 0 0 . 0 0 . U 2 0 . 0 0 . U 2 3 3 1 . U 6 2 . 4 6 3 . 8 3 0 . 2 1 9 . 6 7 2 . 5 8 0 . 0 1 . 0 0 0 . 0 5 . 9 6 1 . 8 3 0 . 0 2 . 0 8 0 . 9 2 0 . 0 1 . H 6 0 . 0 0 . 0 0 . 0 0 . 0 0 . 0 4 1 8 . 5 8 9 . 2 5 2 . 4 2 U . 7 9 1 9 . 6 3 6 . 5 8 5 . 0 8 3 . 2 5 0 . 0 1 . 1 7 a . 3 3 0 . 0 0 . 2 5 2 . 0 8 0 . 0 0 . 0 o . s a 0 . 0 0 . 0 0 . 0 0 . 0 5 1 5 . 4 6 8 . 9 2 7 . 0 4 5 . 2 5 1 4 . 2 9 5 . 2 9 1 0 . 6 3 1 . 9 2 1 . 8 3 2 . 4 2 2 . 0 0 0 . 0 1 . 9 6 0 . 0 0 . 0 0 . 0 0 . 6 7 0 . 0 0 . 0 0 . 2 9 0 . 0 6 7 8 9 10 11 1 4 . 3 3 1 5 . 2 9 1 3 . 5 0 3 . 1 3 1 4 . 0 8 7 . 0 0 1 1 . 5 0 4 . 0 0 2 . 6 7 2 . 7 1 4 . 3 8 6 . 4 6 0 . 2 9 3 . 7 9 2 . 0 0 3 . 3 3 5 . 0 8 3 . 7 9 8 . 0 0 1 . 4 6 0 . 4 2 1 1 . 7 9 7 . 5 4 1 2 . 2 1 3 . 9 2 1 6 . 0 4 1 8 . 6 3 9 . 7 1 1 7 . 7 1 6 . 4 6 2 . 0 0 5 . 0 8 1 2 . 1 7 7 . 8 3 1 0 . 2 9 3 . 7 5 1 5 . 6 3 1 . 5 0 0 . 7 1 1 1 . 5 8 0 . 5 8 1 5 . 7 5 0 . 5 0 0 . 0 0 . 0 0 . 7 5 0 . 9 2 0 . 3 3 2 . 2 5 2 . 0 4 0 . 0 1 . 7 5 0 . 0 6 . 0 8 0 . 8 8 0 . 3 3 0 . 2 1 0 . 0 4 . 3 3 0 . 0 1 . 8 3 1 . 9 6 4 . 7 1 0 . 3 3 1 . 6 7 0 . 7 9 0 . 0 0 . 0 0 . 0 0 . 0 0 . 9 2 0 . 0 3 . 0 4 0 . 8 3 0 . 0 0 . 7 5 0 . 0 0 . 2 9 0 . 0 . 0 . 0 0 . 5 4 1 . 2 5 4 . 1 3 0 . 3 3 -0 . 0 2 . 9 2 0 . 5 8 0 . 0 0 . 0 0 . 0 0 . 0 0 . 0 0 . 0 0 . 0 0 . 0 0 . 0 0 . 0 0 . 0 0 . 0 0 . 0 0 . 0 0 . 0 0 . 0 0 . 0 0 . 0 0 . 0 0 . 0 2 . 0 4 0 . 0 0 . 0 0 . 0 0 . 0 0 . 0 0 . 0 0 . 0 0 . 0 0 . 0 0 . 0 0 . 0 0 . 0 4 0 . 0 0 . 1 3 0 . 5 8 0 . 0 0 . 0 0 . 0 12 6 . 1 3 6 . 5 9 5 . 8 3 9 . 7 5 9 . 9 2 8 . 5 8 6 . 0 4 6 . 2 5 8 . 6 7 0 . 5 4 2 . 5 0 0 . 0 0 . 0 1 . 2 5 1 . 7 9 0 . 0 0 . 0 0 . 0 0 . 0 0 . 2 5 0 . 0 13 1 4 . 8 3 1 0 . 7 5 1 0 . 9 2 1 6 . 0 0 5 . 6 3 6 . 5 0 4 . 2 5 0 . 5 8 5 . 2 9 0 . 9 6 2 . 2 9 0 . 0 0 . 0 2 . 4 6 0 . 0 0 . 0 0 . 0 0 . 0 0 . 3 8 0 . 0 0 . 0 14 8 . 4 2 1 3 . 2 5 2 . 4 6 1 0 . 0 0 6 . 7 9 3 . 0 4 1 3 . 5 8 0 . 4 6 5 . 3 8 0 . 1 3 0 . 5 0 0 . 0 0 . 7 9 1 . 4 6 0 . 0 0 . 0 0 . 0 0 . 0 0 . 0 0 . 0 0 . 0 15 1 3 . 9 6 5 . 7 9 1 1 . 5 8 5 . 5 0 1 6 . 4 2 8 . 9 2 3 . 6 7 1 . 0 0 1 . 0 8 4 . 4 2 0 . 7 9 0 . 0 0 . 0 2 . 5 8 0 . 0 0 . 0 0 . 0 0 . 0 0 . 0 0 . 0 0 . 0 frequency (maximum = 50) of epiphytic species on the 15 trees sampled at FUR. 84 n 10 15 8 13 12 14 Figure 18. Reciprocal averaging ordination of i n d i v i d u a l trees (based upon t h e i r epiphytic vegetation) at FUR. t l e t a n e c k e r a m e n z i e s i i  L e p r a r i a m e m b r a n a c e a  H o n a l o t h e c i u i i f u l g e s c e n s  N e c k e r a d o u g l a s i i  C l a o p o d i u m c r i s p i f o l i u m  P o r e l l a c o r d a e a n a  I s o t h e c i um s t o l o n i f e r u m  H j « a 1 o t h e c i u r c n u t t a l l i i  Z y g o d o n y i r i d i s s i m u s  P o r e l l a n a v i c u l a r i s  P l a g i omn i urn ven l i g t u n  F r u l l a n i a t a m a r i s c i  P o l y p o d i u m g l y c y r t h i 2 a  L e u c o l e p i a m e n z i e s i i  Hypnum s u b i a p o n e n s  S t o k e s i e l l a p r a e l c n g a  O c t h o t r i c h u a l y e l l i i  C l a d o n i a s u b s g u a i p s a  L o p h o c o l e a c u s p i d a t a  C o n i o c y b e f u r f u r a c c a  P a r m e l i a s u 1 c i t a  B h i z o m n i o m g l a b r e s e e n s  D i c r a n u a f u s c e s c e n s  H c t z g o r i a c o n j u g a t a 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 5 . 4 6 1 . 8 8 3 . 13 2 . 0 0 0 . 6 7 6 . 4 2 5 . 2 5 0 . 0 1 . 0 8 1 0 . 6 7 1 . 9 2 5 . 0 8 7 . 6 7 9 . 3 3 2 . 2 5 2 7 . 46 2 6 . 5 0 2 1 . 0 4 2 7 . 0 0 2 5 . 4 6 3 4 . 1 3 2 B . 8 3 3 5 . 5 8 2 9 . 13 2 7 . U6 2 0 . 7 1 1 4 . 6 3 1 7 . 17 1 5 . 17 5 . 3 3 5 . 7 9 7 . 1 7 7 . 8 3 4 . 4 2 2 . 4 2 0 . 2 5 3 . 0 U 6 . O t t 8 . 2 1 6 . 7 1 8 . 5 4 4 . 1 7 9 . 17 1 . 0 8 2 . 13 1 . 2 1 7 . 8 8 0 . 7 9 1.1)6 2 . 6 7 1 . 5 1 2 . 6 7 2 . 0 8 0 . 7 9 1 . 3 3 0 . 0 0 . 3 3 1 . 6 7 2 . 0 0 3 . 0 0 1 1 . 8 8 1 3 . 7 5 2 2 . 5 4 2 . 9 6 111. 17 8 . 3 3 1 2 . 2 9 8 . 5 0 1 1 . 3 3 1 0 . 7 1 1 2 . 7 5 8 . 5 1 1 3 . 2 9 1 0 . 5 0 2 1 . 5 8 0 . 67 3 . 5 1 5 . 7 9 C . 8 8 1 . 3 3 1 . 51 1 . 0 0 1 . 2 5 0 . 1 2 2 . 9 6 2 . 5 1 0 . 0 2 . 71 8 . 8 3 8 . 5 0 2 . 13 2 2 . 5 0 1 2 . 13 2 5 . 0 0 1 3 . 5 0 1 7 . 2 9 1 9 . 8 8 1 1 . 2 1 1 9 . 2 9 1 . 1 2 1 2 . 5 1 1 1 . 7 5 7 . 5 8 5 . 5 1 1 1 . 0 1 1 1 . 5 0 1 . 7 5 0 . 3 3 1 . 13 0 . 8 3 9 . 6 7 3 . 7 5 5 . 1 2 0 . 9 2 1 0 . 6 3 3 . 9 6 3 . 9 6 1 . 9 2 3 . 5 1 1 . 3 8 0 . 0 8 0 . 0 0 . 8 8 0 . 0 0 . 5 1 2 . 6 7 2 . 6 7 0 . 0 0 . 6 7 1 . 0 8 3 . 1 6 3 . 2 5 8 . 7 1 2 . 9 6 0 . 5 0 ' 0 . 2 5 0 . 0 0 . 0 0 . 0 0 . 0 0 . 0 1 . 0 8 0 . 0 0 . 0 0 . 0 0 . 0 0 . 0 0 . 0 0 . 0 0 . 0 0 . 6 7 2 . 8 8 1 . 1 2 2 . 0 8 2 . 0 8 0 . 0 0 . 7 1 2 . 5 0 0 . 2 5 0 . 3 3 0 . 0 0 . 0 0 . 7 5 1 . 1 3 0 . 0 0 . 2 5 1 . 17 0 . 0 1 . 2 5 2 . 2 1 2 . 9 6 1 . 2 9 3 . 5 7 1 . 5 8 1 . 0 0 1 . 9 6 1 . 5 0 3 . 5 8 2 . 1 2 C . 12 0 . 2 9 0 . 9 8 1 0 . 3 8 0 . 0 6 . 0 8 0 . 3 8 1 . 5 7 0 . 2 9 1 . 9 6 0 . 3 8 0 . 3 3 1 . 3 3 0 . 9 6 2 . 2 5 0 . 0 0 . 7 5 0 . 8 3 0 . 6 7 1 . 4 6 0 . 7 5 0 . 2 1 1 . 2 9 3 . 7 1 3 . 4 2 0 . 0 2 . 71 0 . 0 0 . 0 0 . 4 2 0 . 0 0 . 0 0 . 0 0 . 0 0 . 0 0 . 0 0 . 0 1 . 0 8 0 . 0 0 . 0 0 . 0 0 . 0 0 . 0 0 . 0 0 . 0 0 . 9 2 0 . 0 0 . 7 5 2 . 5 8 0 . 0 0 . 0 0 . 0 0 . 1 3 0 . 0 0 . 0 0 . 1 7 0 . 0 0 . 0 0 . 0 0 . 0 0 . 0 8 0 . 2 9 0 . 3 8 3 . 1 3 1 . 0 0 0 . 9 2 6 . 5 4 5 . 4 2 0 . 3 8 0 . 2 5 0 . 9 2 2 . 2 9 0 . 0 0 . 0 0 . 0 0 . 0 0 . 3 8 0 . 5 8 0 . 0 0 . 4 6 0 . 0 0 . 8 3 0 . 17 0 . 13 0 . 2 9 0 . 0 0 . 0 1 . 7 1 1 . 4 6 2 . 0 4 1 . 6 7 0 . 0 4 0 . 7 5 1 1 . 3 3 0 . 54 1 . 0 4 0 . 0 1 . 3 8 2 . 54 0 . 0 0 . 8 3 4 . 2 5 0 . 0 0 . 0 0 . 0 0 . 0 0 . 2 9 0 . 0 0 . 6 7 0 . 0 0 . 0 0 . 0 0 . 0 0 . 0 3 0 . 0 0 . 0 0 . 0 1 . 0 0 0 . 0 1 . 2 9 0 . 0 0 . 5 0 0 . 0 0 . 0 0 . 0 0 . 0 0 . 0 0 . 3 8 1 . 2 1 0 . 6 7 0 . 5 0 0 . 2 5 0 . 0 0 . 0 0 . 0 0 . 0 0 . 0 0 . 0 0 . 0 0 . 0 0 . 0 0 . 0 0 . 0 0 . 0 0 . 0 0 . 17 0 . 6 7 4 . 2 9 0 . 0 0 . 0 0 . 0 0 . 3 8 0 . 0 0 . 0 0 . 0 0 . 0 0 . 0 0 . 0 0 . 0 0 . 0 0 . 0 0 . 13 0 . 0 0 . 0 C O 0 . 0 1 . 0 4 0 . 17 0 . 0 0 . 0 2 . 3 3 0 . 1 3 0 . 0 0 . 0 0 . 0 2 . 9 6 0 . 0 0 . C 0 . 0 0 . 0 1 . 7 9 Table 19. Mean l o c a l frequency (maximum = 50) of epiphytic species on the 15 trees sampled at UEL. oo 86 n 15 14 8 12 13 10 Figure 19. Reciprocal averaging ordination of individual trees (based upon their epiphytic vegetation) at UEL. 87 r e g i o n s of the wood, except f o r t r e e 2, which i s t h e s m a l l e s t of t h o s e sampled. Trees 3 and 15, l o c a t e d toward the top r i g h t o f the o r d i n a t i o n , b o t h show a h i g h freguency of Claopodium c r i s p i f o l i u m . They a r e both f a i r l y l a r g e t r e e s l e a n i n g to a g r e a t e r degree than most of t h e o t h e r s s t u d i e d . PIT E p i p h y t i c f r e g u e n c y v a l u e s on t h e 15 t r e e s a t t h i s s i t e are shown i n T a b l e 20; F i g u r e 20 shows t h e r e s u l t a n t t r e e o r d i n a t i o n . The f i r s t component a x i s a c c o u n t s f o r 30.45% of t h e v a r i a t i o n , the second 20.48%. A t o t a l o f 9 p o s i t i v e e i g e n v a l u e s were e x t r a c t e d from a m a t r i x o f 10 e p i p h y t i c s p e c i e s . . Neckera doug_la s i i and Metaneckera m e n z i e s i i show s t r o n g p o s i t i v e w e i g h t i n g on the f i r s t a x i s , w h i l e Apometzgeria pubescens, I s o t h e c i u m s t o l o n i f e r u m , and P o r e l l a n a y i c u l a r i s are n e g a t i v e l y weighted. On t h e second a x i s , s t o l o n i f erum, P._ n a y i c u l a r i s , Claopodium c r i s p i f o l i u m , . m e n z i e s i i , and H i d o u g l a s i i a l l show s t r o n g p o s i t i v e w e i g h t i n g , w h i l e P o r e l l a cordaeana, L e p r a r i a membranacea, Homalothecium n u t t a l l i i , Homalothecium ful3. e s c e n s , and A p ometzgeria pubescens a r e n e g a t i v e l y weighted.. Tree 1, l o c a t e d a t t h e t o p l e f t of the o r d i n a t i o n , has a h i g h f r e g u e n c y of I s o t h e c i u m s t o l o n i f e r u m . Tree 11, a t t h e bottom l e f t of t h e o r d i n a t i o n , shows a h i g h f r e g u e n c y of P o r e l l a £2£<la.e-a.na. Those o c c u r r i n g a t t h e top r i g h t of the o r d i n a t i o n , i n c l u d i n g t r e e s 2, 3, 14, and 15, o c c u r i n r e l a t i v e l y dense s t a n d s w i t h i n the f o r e s t , and have high f r e g u e n c y v a l u e s of Metaneckera m e n z i e s i i or Neckera d o u g l a s i i (or sometimes b o t h ) . Tree 10 ( a g a i n , l o c a t e d w i t h i n a dense s t a n d ) , has a h i g h 88 f r e g u e n c y of M«_ m e n z i e s i i and i s p u l l e d t o the r i g h t on the f i r s t a x i s . . T r e e s 4, 6, 7, 8, 9, 12, and 13 form a c l u s t e r near the c e n t e r of t h e o r d i n a t i o n . They o c c u r i n l e s s dense a r e a s o f the f o r e s t ( w i t h the e x c e p t i o n of t r e e 4) . BRI E p i p h y t i c f r e g u e n c y v a l u e s on the 15 t r e e s a t t h i s s i t e are shown i n Table 21; F i g u r e 21 shows t h e r e s u l t a n t t r e e o r d i n a t i o n . The f i r s t component a x i s a c c o u n t s f o r 34.62% of t h e t o t a l v a r i a t i o n , t h e second 22.09%. A t o t a l o f 10 p o s i t i v e e i g e n v a l u e s were e x t r a c t e d from a data m a t r i x of 11 e p i p h y t i c s p e c i e s . _ G r a p h i s s c r i p t a , Homalothecium f u l g e s c e n s , A n t i t r i c h i a c a l i f o r n i c a , and P o r e l l a cordaeana a l l show s t r o n g p o s i t i v e w e i g h t i n g on the f i r s t a x i s , w h i l e D e n d r o a l s i a a b i e t i n a and Metaneckera m e n z i e s i i are n e g a t i v e l y weighted. On the second a x i s , Neckera d o u g l a s i i and P.. cordaeana have p o s i t i v e w e i g h t i n g s , w h i l e M._ m e n z i e s i i and G._ s c r i p t a a r e n e g a t i v e l y w e i g h t e d . Tree 6, l o c a t e d a t the f a r r i g h t of the o r d i n a t i o n , has a hig h f r e g u e n c y of G r a p h i s s c r i p t a . Tree 7 o c c u r s a t the t o p of the o r d i n a t i o n , and has h i g h f r e g u e n c y v a l u e s f o r P o r e l l a cordaeana and Neckera d o u g l a s i i . Tree 9, which i s p u l l e d toward t h e upper l e f t of the o r d i n a t i o n , shows a h i g h f r e g u e n c y of N?_. d o u g l a s i i . A H t h r e e of t h e s e t r e e s occur i n more open a r e a s w i t h i n t h e dense woods. Trees 13, 14, and 15, which a l s o occur i n the l e s s dense area s of t h e f o r e s t , are l o c a t e d near t h e ce n t e r o f t h e o r d i n a t i o n . . They, t o g e t h e r w i t h t r e e s 6 and 7, have r e l a t i v e l y h i g h f r e g u e n c y v a l u e s of Homalothecium 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 M e t a n e c k e r a m e n z i e s i i 11. 83 13.08 28. 00 19.42 22.29 9.54 9. .42 12.79 15. , 38 18. 2 1 7. 33 13.25 15.79 17, ,63 25. 25 L e p r a r i a mercbranacea 6. 00 4.25 4. 08 9.00 7.00 18.17 8. , 88 9.25 13. 71 10. 38 14. 21 13.46 14. 25 4. ,63 14. 38 Homalothecium f u l g e s c e n s 4 . 08 7. 54 3. 58 6.67 4.29 6.92 9. ,71 10.96 9. 54 12.21 9. 38 6.04 5.75 6. .88 0. 33 Neckera d o u q l a s i i 3. 08 16.67 4.29 2.79 7.00 7.00 0. . 38 10. 33 3. 75 6.58 2. 83 8.08 5.88 16. .54 19. 83 C l a o p o d i u n c r i s p i f c l i u n 11. 21 12.79 10.58 9.38 12.63 14.00 8. ,50 10.88 13. 38 0.6 3 12. 29 5.88 6. 29 6. .5 8 7. 88 P o r e l l a c o r d a e a n a 1. 13 1. 13 0.0 1.21 0. 21 0.0 0. 25 0.0 2. 33 2.29 7.92 1.71 2.75 3. 53 4. 04 I s o t h e c i u m s t o 1 on i f e r u m 8. 0« 2.42 0. 25 4.25 0.92 1.58 0. 29 1.67 1. 46 0.0 0. 50 1. 96 0.67 0. 0 0. 0 Homalothecium n u t t a l l i i 2. 96 0.50 0.0 3.92 2. 00 2. 00 2. 54 0. 42 6. 25 5. 38 1. 29 2. 42 7.96 9. 67 2.04 Zygodon v i r i d i s s i a i u s 1. 21 0.0 0.0 0.29 1.13 0. 38 0. 29 3. 38 0. 0 1.54 0.58 7. 75 3. 50 2. 54 0. 0 P o r e l l a n a v i c u l a r i s 8. 00 3.75 0. 33 1.75 1.42 0. 96 2. 92 1.71 1. 29 1.04 2. 38 0.0 1. 54 2. 50 0. 0 P l a g i c a n i u m vents tun 1. 54 1.00 0. 58 1.63 0. 13 2.08 1. 46 1.21 0. 50 0.0 0. 42 0.0 3. 38 0. 0 0.0 P r a l l a n i a t a a a r i s c i 0. 33 0.67 0.42 0.0 0. 13 0.0 0. 25 1.33 0. 25 0.17 0.0 0.0 0. 38 0. 0 0. 0 Polypodium g l y c y r r h i z a 0. 29 0.0 0. 0 0.0 0.0 0. 42 1. 54 0.42 0. 54 0.0 4. 00 0.21 0. 0 0. 71 0.0 A p o m e t z g e r i a p t i t e s c e n s 4. 38 0. 96 0. 54 5.46 0.21 0.0 5. 17 0.0 0. 67 0.0 6. 13 2. 33 3. 33 0. 0 0. 25 L u u c o l e p i s m e n z i e s i i 3. 54 1.58 2. 08 0.50 0.50 1.21 0. 0 1. 25 3. 92 2.08 0.21 0.0 1. 33 0. 0 0.0 Hypnum s u b i n p o n e n s 0. 42 0.29 0.0 0.0 2.63 0.21 2. 08 0.92 0. 0 0.25 1. 58 0. 0 2.25 1. 88 0. 0 S t o k e s i e l l a p r a e l c n g a 0.0 0.0 0. 0 0.0 0.0 0.0 0. 0 0.0 0. 0 0.0 0.0 0.50 0.0 0. 0 0. C C r a p h i s s c r i p t a 0.0 0.0 0. 0 0.0 0. 17 0.0 0. 0 0.0 0. 0 0.0 7. 33 0. 0 0.0 0. 0 0.0 O r t h o t r i c n u m l y e l l i i 0.0 0.0 0. 0 0.0 0.0 0.0 0. 0 0.0 0. 0 0. 13 0.0 0.0 0.0 0. 0 0.0 C l a d o n i a subsquaoicsa 0. 0 0.0 0.0 0. 13 0. 0 0.0 0. 0 0.0 0. 0 0.0 0.0 0.0 0.29 0. 0 0. 0 B h y t i d i a d e l p h u s t r i q u e t r u s 0. 0 0.0 0. 0 0.0 0.38 0.0 3. 67 0.0 0. 0 0.0 0.0 0.0 0.0 0. 0 0. 0 B h i z o a n i u n g l a b r e s c e n s 0. 0 0.0 0.0 0.0 0.0 0.0 0. 0 0. 0 0. 0 0.0 0.0 0. 0 0.83 0. 0 0.0 O i c r a n u a t u s c e s c e n s 0. 0 0.0 0.0 0.0 0.0 0.0 0. 0 0.0 0. 21 0.0 0.0 0. 0 0.0 0. 0 0.0 Table 20. Mean l o c a l frequency (maximum = 50) of epiphytic species on the 15 trees sampled at PIT. 90 n 6 9 14 12 10 13 15 11 Figure 20. Reciprocal averaging ordination of i n d i v i d u a l trees (based upon t h e i r epiphytic vegetation) at PIT. 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 K e t a n e c k e r a m e n z i e s i i 24.50 23.5H 29.79 33.63 27. 04 12. 33 6. 38 32. 83 19. 38 20. 83 34.50 39. 46 30. 92 22. 38 23. 96 L e o r a r i a membranacea 3.75 5.38 5. 54 4. 38 0. 17 0. 96 4.63 3.00 6.63 7. 75 3. 63 0. 58 6. 96 5.71 6. 13 Homalothecium f u l q e s c e n s 0.46 1.33 0.0 4.42 4. 46 10. 21 9. 92 1.25 2.46 1.63 4.04 0. 54 3.25 4.71 5.04 Neckera d o u q l a s i i 1.29 3.54 2. 17 0.0 1.42 1.71 12. 67 9.25 11.58 2. 04 0. 83 1. 96 1.50 3. 54 2. 13 C l a o p o J i u a c r i s p i f o l i u m 7. 50 6.67 2.08 5. 21 5. 08 3.21 8.63 3.25 0.0 3. 96 1. 33 5. 33 0. 7 5 5. 17 4. 17 P o r e l l a c o r d a e a n a 0.0 0.29 0.29 0. 17 0. 54 2.67 8. 13 0.21 0.0 0.0 2.88 0. 0 1. 50 1.04 3.54 Homalothecium n u t t a l l i i 0.54 0.17 2.88 2.92 5. 13 1. 17 1. 50 3.21 0.0 0. 0 0.0 0. 0 0. 0 0.0 0.0 D e n d r o a l s i a a b i e t i n a 4.58 6.46 11. 13 7.88 6. 71 1.29 4.67 11.46 14. 96 19. 54 6. 50 4. 04 1. 50 5.83 5. 17 Zyqodon v i r i d i s s i n u s 0.0 0.0 0. 17 0.21 0. 75 1.04 0.0 0.0 0.0 0. 25 0.0 0.08 0. 0 0.0 0.0 P o r e l l a n a v i c u l a r i s 0.21 0.75 0.0 0.0 2.00 0.42 3.29 0.0 0.0 0. 0 0.0 0.0 0. 67 0.21 0.0 Plaqioranium »enustum 0.0 0.0 0. 33 0. 13 0. 42 1.88 0. 71 0.0 0.0 0. 0 0.0 0. 0 1.00 0. 75 0.21 F r u l l a n i a t a m a r i s c i 0.0 0.0 0. 46 0.21 0. 0 0.0 0.0 0.0 0. 0 0. 38 0. 0 0.0 0.0 o . o' 0.0 P o l y p o d i u m q l y c y r r h i z a 0.67 0.0 0.0 0.0 0. 0 0.0 0.0 0.0 0.0 0.0 0.0 0. 0 0.0 0. 0 0.0 A p o m e t z q e r i a pubescens 3.92 0.0 0. 50 0.0 0. 0 0. 96 1. 71 0.29' 0.21 0. 25 3.33 0. 0 0.0 4. 13 0.0 i n t i t r i c h i a c a l i f o r n i c a 0.0 0.75 b . o 1.42 0. 92 4.03 2. 46 0. 0 0.0 0. 33 0. 0 0.0 9.50 3. 83 8.50 L e u c o l e p i s m e n z i e s i i 0.0 0.25 0.0 0.0 0. 0 0.21 0. 29 0.0 0.0 0.0 1.42 0. 0 0.0 0. 0 0. 29 Hypnum subimponens 0.0 0.0 0.0 0.0 0. 0 0. 17 1. 00 0.0 0.0 0. 0 0. 0 0. 0 0.25 0. 75 0.0 S t o k e s i e l l a p r a e l o n q a 0.0 0.0 0.0 0.0 0. 0 0. 0 0. 0 0.0 0.0 0. 0 0.0 0.75 0.0 0. 0 0.0 G r a p h i s s c r i p t a 0.0 0.67 0.88 2.7 1 5.58 16.42 0. 0 0.0 0.0 0. 0 5. 17 0. 13 2.75 9. 29 0.0 N e c k e r a pennata 0.0 0.0 0.0 0.0 0.0 0.0 0. 33 0.0 0.0 8. 38 0. 38 0. 0 0.0 0.0 0.0 O r t h o t r i c h u t n l y e l l i i 0. 17 0.0 0.0 0.0 0. 38 0. 0 0.0 0.0 0.0 0. 0 0.0 0.0 0.0 0. 0 0.0 L o p h o c o l e a c u s p i d a t a 0.0 0.0 0.0 0.0 0.0 0. 29 0.0 0.0 0.0 0. 0 0. 0 0. 0 0.0 0. 0 0.0 E h y t i d i a d e l p h u s t r i q u e t r u s 0.0 O.C 0.0 0.0 0.0 0.0 1. 25 0.0 0.0 0. 0 0.0 0. 0 0. 25 0. 0 0.0 C o n i o c y b e f u r f u r a c e a 0.0 0.0 0.0 0.0 0. 0 0.0 0. 0 0.0 0.92 0. 0 0.0 0. 0 0.0 0.0 0.0 nhizomnium q l a b r e s c e n s 0.0 0.0 0.0 0.0 0. 0 0.0 0. 0 0. 0 0.0 0. 0 0.0 0. 17 0. 50 0. 0 0.0 . Mean l o c a l frequency (maximum = 50) of epiphytic species on the 15 trees sampled at BRI. 10 15 8 2 3 1 13 11 14 12 Figure 21. Reciprocal averaging ordination of i n d i v i d u a l trees (based upon t h e i r epiphytic vegetation) at BRI. 93 ilsi3. e-& c. e- n.s. Tree 12, which i s pulled strongly to the lower l e f t of the ordination, has a very high freguency of Metaneckera menziesii. Trees occurring at the lower l e f t of the ordination (including trees 1, 2, 3, 4, 5, 8, 10, 11, and 12) tend to show high freguency of M. menziesii and Dendroalsia abietina., D i s c i s s i o n Slack (1976, 1977) has pointed out that trees may be viewed as 'islands' open to colonization by epiphytic species, comparing the s i t u a t i o n to that of island biogeography as advanced by MacAurthur and Wilson (1967). Using such an analogy, i n t e r e s t i n g guestions regarding the influence of nearby 'tree islands' on the epiphytic vegetation of a given phorophyte can be addressed. . Short-range dispersal of diaspores from nearby adjacent trees may lead to differences i n epiphytic vegetation of trees i n a small region of the forest. That i s , a given epiphytic species may be uncommon on a tree not because i t i s limit e d by the microenvironment, but because there i s no nearby diaspore source. Furthermore, a given species may be uncommon on a tree simply because another species with s i m i l a r ecological reguirements already occupies the available niche space. This i s somewhat analogous to a 'scramble' type of competition (Whittaker 1975); the species which f i r s t colonizes and becomes established may exclude p o t e n t i a l l y competing species from the habitat. Patterns of epiphytic d i s t r i b u t i o n are further complicated by aspects of succession which take place as a tree grows, making available new habitats and at the same time 94 e l i m i n a t i n g former ones.. C l e a r l y i t i s d i f f i c u l t , i f not i m p o s s i b l e , t o separate or rank these e c o l o g i c a l f a c t o r s and environmental i n f l u e n c e s . I t i s l i k e l y too t h a t these f a c t o r s act s y n e r g i s t i c a l l y , so that s p e c u l a t i o n as to which f a c t o r s are most 'important' i n e x p l a i n i n g d i f f e r e n c e s i n e p i p h y t i c composition between t r e e s may be somewhat misleading._ The o r d i n a t i o n r e s u l t s f o r each of the s i t e s suggest some d i f f e r e n c e s i n e p i p h y t i c v e g e t a t i o n on the t r e e s , d e s p i t e attempts t o minimize between-tree v a r i a t i o n . . T h i s i s to be expected, s i n c e i t i s u n l i k e l y , given the number of f a c t o r s t h a t may i n f l u e n c e e p i p h y t i c e s t a b l i s h m e n t , t o f i n d t r e e s with i d e n t i c a l e p i p h y t i c m i c r o h a b i t a t s and f l o r i s t i c composition. Nonetheless, the r e s u l t s i n Tables 17-21 suggest t h a t the t r e e s at a. given s i t e have a s i m i l a r e p i p h y t i c composition; d i f f e r e n c e s are g u a n t i t a t i v e r a t h e r than g u a l i t a t i v e . . There i s some i n d i c a t i o n at each of the s i t e s t h a t the nature of the surrounding v e g e t a t i o n may be important to e p i p h y t i c e s t a b l i s h m e n t . . D i f f e r e n c e s i n e p i p h y t i c composition between t r e e s i n more open areas and those of denser r e g i o n s are o f t e n r e c o g n i z a b l e . . The l o c a t i o n of the t r e e w i t h i n the f o r e s t i s important, s i n c e the surrounding v a s c u l a r v e g e t a t i o n ( t r e e s and shrubs) i n f l u e n c e s the microenvironment around the t r e e bole through shading and by a l t e r i n g water supply and humidity..The importance of the surrounding v a s c u l a r v e g e t a t i o n , however, i s not always c l e a r , i n d i c a t i n g t h a t other f a c t o r s (of which t r e e s i z e and degree of i n c l i n a t i o n are recognized) may a l s o be important. Furthermore, i n many cases a t r e e (or a few trees) have higher values of a given e p i p h y t i c s p e c i e s (or group of 95 s p e c i e s ) t h a n o t h e r t r e e s , but f o r no apparent reason. I t i s p o s s i b l e t h a t o t h e r f a c t o r s , such as the b i o t i c f a c t o r s d i s c u s s e d above, may i n f l u e n c e e p i p h y t i c d i s t r i b u t i o n * R e s u l t s i n Appendix 1 suggest t h a t between-tree bark c h e m i c a l d i f f e r e n c e s do not appear t o be i m p o r t a n t i n i n f l u e n c i n g e p i p h y t i c d i s t r i b u t i o n s a t a g i v e n s i t e . T h i s c o n c l u s i o n must be g u a l i f i e d , however, s i n c e a s i n g l e bark sample from a t r e e i s l i k e l y i n a d e g u a t e t o c h a r a c t e r i z e the bark c h e m i s t r y of the e n t i r e t r e e b o l e . D i s t i n g u i s h a b i l i t y o f the F i v e S i t e s I t has a l r e a d y been shown t h a t t h e 5 study s i t e s d i f f e r i n c l i m a t e ( p r i m a r i l y 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 ) and u n d e r s t o r y , as w e l l as t r e e s t a n d s t r u c t u r e , d e n s i t y , and s p e c i e s c o m p o s i t i o n . I t i s i n t e r e s t i n g t o ask t o what e x t e n t the e p i p h y t i c v e g e t a t i o n responds t o t h e s e d i f f e r e n c e s . I n an attempt t o answer t h i s , RA was used t o o r d i n a t e t h e 75 t r e e s s t u d i e d * . A s i n the p r e v i o u s s e c t i o n , a mean f r e g u e n c y of each of the e p i p h y t i c s p e c i e s found on a g i v e n t r e e (over 24 g uadrats) was computed. B e f o r e r u n n i n g the a n a l y s i s , s p e c i e s o c c u r r i n g i n fewer t h a n 90 of t h e 1800 g u a d r a t s were removed from the d a t a s e t . A t o t a l of 12 e p i p h y t i c s p e c i e s were used. The r e s u l t a n t o r d i n a t i o n i s shown i n F i g u r e 22; d i f f e r e n t symbols a r e used t o d i s t i n g u i s h t h e t r e e s from th e 5 s i t e s , and numbers r e p r e s e n t t h e s t u d y t r e e numbers (see T a b l e s 12-16). The f i r s t component a x i s a c c o u n t s f o r 30.20% of the v a r i a t i o n , the second 23.51%. E l e v e n p o s i t i v e e i g e n v a l u e s were e x t r a c t e d from the data s e t . I s o t h e c i u m s t o l o n i f e r u m , L e p r a r i a membranacea, and n 0 3 Ol3 06 " 0 0 0 2 15 0 2 o< 0 5 7 *n Oa 065 Q 5 9 2 8 Q 5 5 Q60 Q 5 0 O 7 5 Q 4 8 5 7 58(2) 23/Al o 6 8 Al8 065 0 6 ^ 0 ™ 0 72 A 2 4 P A 2 7 A30 (A&^A 56pA26 •» Cferjae A2S J U 4 3 4 5 U N 4 2 *-* • 3 2 a$39D3* Q 5 4 A 2 0 A21 Q 4 6 • 4 0 1—144 A16 As A17 Figure 22. Reciprocal averaging ordination of i n d i v i d u a l trees (based upon t h e i r epiphytic vegetation) at the 5 s i t e s . Study tree numbers are shown. Symbols code by s i t e : 0= SQU, /\> = FUR, • = UEL, Q= PIT, O = BRI. 9 7 Claop.odium c r i s p i f o l i u m show h i g h p o s i t i v e w e i g h t i n g on the f i r s t a x i s , w h i l e Metaneckera M e n z i e s i i , Homalia trichomanoid.es, i S t i i t i S i i i a c a l i f o r n i c a , and Homalothecium f u l g e s c e n s are n e g a t i v e l y weighted. On the second a x i s , H._.trichomanoides, Neckera d o u g l a s i i , and H._.fulgescens show s t r o n g p o s i t i v e w e i g h t ; M.. m e n z i e s i i and D e n d r o a l s i a a b i e t i n a a re n e g a t i v e l y we i g h t e d . In g e n e r a l , t h e r e s u l t s suggest t h a t the e p i p h y t e s respond to b e t w e e n - s i t e d i f f e r e n c e s . The t r e e s from SQU form a f a i r l y d i s t i n c t group at t h e t o p l e f t of t h e o r d i n a t i o n * However, t r e e s 7, 8, and 9 are d i s t i n g u i s h e d , o c c u r r i n g more towards the lower l e f t of the o r d i n a t i o n . These t r e e s have a l r e a d y been shown t o be somewhat unusual ( F i g u r e 17, T a b l e 17); t h e y show a h i g h e r f r e g u e n c y of Metaneckera m e n z i e s i i (and a lower f r e g u e n c y of Somalia t r i c h o m a n o i d e s ) than o t h e r t r e e s a t t h i s s i t e . T r e e s from UEL form a d i s t i n c t i v e group toward the p o s i t i v e end of the f i r s t a x i s , owing t o t h e i r h i g h f r e g u e n c i e s of I s o t h e c i u m s t o l o n i f e r u m , L e p r a r i a membranacea, and Claopodium c r i s p i f o l i u m . Trees 44, 43, 40, and 31, which o c c u r more t o t h e l e f t a l o n g the f i r s t a x i s , have h i g h e r f r e g u e n c y v a l u e s of Metaneckera m e n z i e s i i . The UEL s i t e t r e e s form the most d i s t i n c t i v e group i n the o r d i n a t i o n . T r e e s from BRI g e n e r a l l y o c c u r toward t h e lower l e f t of t h e o r d i n a t i o n , s i n c e they g e n e r a l l y show a hig h f r e g u e n c y of both Mstaneckera m e n z i e s i i and D e n d r o a l s i a a b i e t i n a . Trees 66 and 67, which have a l r e a d y been shown t o be somewhat unigue ( F i g u r e 21, Table 2 1 ) , a r e s e p a r a t e d from the r e s t o f t h i s group..These t r e e s have a h i g h e r freguency o f Homalothecium f u l g e s c e n s , and 98 i n t h e case of t r e e 67, Neckera d o u g l a s i i , which p u l l s them toward t h e c e n t e r of the o r d i n a t i o n . Trees a t PIT and FUR occur t o g e t h e r near t h e c e n t e r o f the o r d i n a t i o n ; however, t r e e s from PIT tend t o be p u l l e d f u r t h e r t o the l e f t , w h i l e t h o s e from FUR a r e more common t o the r i g h t . Of the t r e e s from the FUR s i t e , some i n t e r e s t i n g t r e n d s a r e seen. Tree 18 o c c u r s wi t h t r e e s from the BRI s i t e because of i t s h i g h f r e g u e n c y o f Metaneckera m e n z i e s i i . . T r e e s 16, 26, and 29, which have f a i r l y h i g h f r e g u e n c y v a l u e s of I s o t h e c i u m s t o l o n i f e r u m , are p u l l e d t o the r i g h t of t h e o r d i n a t i o n n e a r e r the UEL group. Tree 28 i s p o s i t i o n e d s l i g h t l y n e g a t i v e l y a l o n g the f i r s t a x i s because o f i t s h i g h e r f r e g u e n c y of Neckera d o u g l a s i i . Most o f t h e o t h e r t r e e s from FUR f a l l r o u g h l y between t h e UEL t r e e s and t r e e s from PIT. Some t r e n d s i n the t r e e s from PIT are a l s o seen. Tree 46, which has a r e l a t i v e l y h i g h freguency of I s o t h e c i u m s t o l o n i f e r u m , i s p u l l e d toward t h e lower r i g h t . . T r e e s 48 and 50 a r e p u l l e d towards the BRI group on account of t h e i r h i g h f r e g u e n c y o f Metaneckera m e n z i e s i i . Trees 47, 52, 53, 55, 59, and 60, which o c c u r t o the l e f t of t h e o r d i n a t i o n c e n t e r , g e n e r a l l y have a h i g h e r f r e g u e n c y of both Neckera d o u g l a s i i and M2S&1Qthecium f u l g e s c e n s than o t h e r t r e e s from the s i t e . T a b l e 22 summarizes e p i p h y t i c s p e c i e s f r e q u e n c i e s over the 5 s i t e s . . These r e s u l t s show t h a t most of the common s p e c i e s o c c u r at a l l of the s i t e s , but may d i f f e r w i d e l y i n t h e i r f r e q u e n c i e s . However, some s p e c i e s a r e s i t e - s p e c i f i c . Hpmalia t r i c h o m a n o i d e s , which s e r v e s t o s e p a r a t e out t r e e s from t h e SQU s i t e , i s r e s t r i c t e d t o t h a t s i t e . D e n d r o a l s i a a b i e t i n a o c c u r s o n l y a t FUR and BRI. I s o t h e c i u m s t o l o n i f e r u m , which shows h i g h SQU FUR UEL PIT BRI Metaneckera m e n z i e s i i 9 . 8 0 1 2 . 9 6 4 . 1 9 1 5 . 9 5 2 5 . 4 3 L e p r a r i a membranacea 6 . 8 0 7 . 5 1 2 3 . 7 1 1 0 . 1 1 4 . 3 4 Homalothecium f u l g e s c e n s 8 . 6 9 4 . 2 6 5 . 1 3 6 . 9 3 3 . 7 8 Neckera d o u g l a s i i 1 2 . 0 6 6 . 8 8 1 . 9 6 8 . 2 0 3 . 71 Claopodium c r i s p i f o l i u m 0 . 5 4 1 1 . 6 2 1 2 . 4 1 9 . 5 2 4 . 16 P o r e l l a cordaeana 2 . 7 6 5 . 9 8 2 . 8 0 1 . 9 0 1 . 4 2 I s o t h e c i u m s t o l o n i f e r u m 0 . 1 0 7 . 3 4 1 3 . 0 5 1 . 6 0 0 . 0 Homalothecium n u t t a l l i i 1 . 0 3 1 . 2 0 4 . 4 4 3 . 2 9 1.17 D e n d r o a l s i a a b i e t i n a 0 . 0 0 3 . 7 8 o . o o 0 . 0 0 7 . 4 5 Zygodon v i r i d i s s i m u s 0 . 1 8 2 . 2 1 2 . 0 3 1 . 5 1 0 . 1 7 P o r e l l a n a v i c u l a r i s 0 . 1 4 2 . 2 2 0 . 0 9 1 . 9 7 0 . 5 0 Plagiomnium venustum 2 . 5 8 0 . 0 7 0 . 9 9 0 . 9 3 0 . 3 6 F r u l l a n i a t a m a r i s c i ssp. n i s a u a l l e n s i s 0 . 0 0 0 . 9 1 2 . 2 8 0 . 2 6 0 . 0 7 Polypodium g l y c y r r h i z a 0 . 4 2 1 . 4 2 2 . 0 1 0 . 5 4 0 . 0 4 Apometzgeria pubescens 0 . 1 5 0 . 3 8 0 . 0 0 1 . 9 6 1 . 0 2 A n t i t r i c h i a c a l i f o r n i c a 2 . 9 5 0 . 0 0 0 . 0 0 0 . 0 0 2 . 12 Homalia t r i c h o m a n o i d e s 6 . 6 2 0 . 0 0 0 . 0 0 0 . 0 0 0 . 0 0 L e u c o l e p i s m e n z i e s i i 0 . 0 2 0 . 1 0 1 . 3 9 1 . 2 1 0 . 1 6 Hypnum subimponens 0 . 8 3 0 . 0 8 0 . 1 3 0 . 8 3 0 . 1 4 S t o k e s i e l l a p r a e l o n g a v a r . s t o k e s i i 0 . 2 9 0 . 1 4 0 . 2 8 0 . 0 3 0 . 0 5 G r a p h i s s c r i p t a 0 . 0 9 0 . 0 0 0 . 0 0 0 . 5 0 2 . 9 1 Neckera pennata 0 . 0 0 0 . 0 0 0 . 0 0 0 . 0 0 0 . 6 1 A n t i t r i c h i a c u r t i p e n d u l a 0 . 3 9 0 . 0 5 0 . 0 0 0 . 0 0 0 . 0 0 O r t h o t r i c h u m l y e l l i i 0 . 0 7 0 . 0 4 0 . 0 2 0 . 0 1 0 . 0 4 C l a d o n i a subsquamosa 0 . 0 0 0 . 0 0 1 . 4 4 0 . 0 3 0 . 0 0 Lophocolea c u s p i d a t a 0 . 0 0 0 . 0 7 0 . 5 4 0 . 0 0 0 . 0 2 R h y t i d i a d e l p h u s t r i q u e t r u s 0 . 2 4 0 . 0 0 0 . 0 0 0 . 2 7 0 . 1 0 Coniocybe f u r f u r a c e a 0 . 0 0 0 . 0 0 1 . 8 2 0 . 0 0 0 . 0 6 P a r m e l i a s u l c a t a 0 . 0 0 0 . 0 0 0 . 0 8 0 . 0 0 0 . 0 0 Rhizomnium g l a b r e s c e n s 0 . 0 0 0 . 0 0 0 . 2 7 0 . 0 6 0 . 0 4 Dicranum fusc e s c e n s 0 . 0 0 0 . 0 0 0 . 3 6 0 . 0 1 0 . 0 0 M e t z g e r i a c o n j u g a t a 0 . 0 0 0 . 0 0 0 . 3 2 0 . 0 0 0 . 0 0 Table 22. Mean l o c a l frequency (maximum = 50) of e p i -phytic species over the 15 trees sampled at each of the 5 study s i t e s . 1 0 0 f r e g u e n c y a t UEL and t o a l e s s e r e x t e n t FUR, i s r e l a t i v e l y r a r e at PIT and SQU and does not occur a t BRI. A n t i t r i c h i a c a l i f o r n i c a o c c u r s o n l y a t SQU and BRI. The r e s u l t s suggest t h a t each s i t e s u p p o r t s a d i s t i n g u i s h a b l e e p i p h y t i c v e g e t a t i o n . The SQU, UEL, and BRI s i t e s a r e the most d i s t i n c t i v e . Yet c e r t a i n t r e e s from a g i v e n s i t e are e x c e p t i o n a l i n t h a t they occur c l o s e r t o a n o t h e r s i t e -group. T h i s would suggest t h a t s i m i l a r e c o l o g i c a l h a b i t a t s are found on t r e e s from d i f f e r e n t s i t e s because of m i c r o e n v i r o n m e n t a l s i m i l a r i t i e s and d e s p i t e macroenvironmental d i f f e r e n c e s . ..This c o u l d i n p a r t e x p l a i n why PIT and FUR have ( q u a n t i t a t i v e l y ) a s i m i l a r e p i p h y t i c v e g e t a t i o n d e s p i t e d i f f e r e n c e s i n t h e i r m a c r o c l i m a t e and f o r e s t s t r u c t u r e . . F i n a l l y , i t s h o u l d be n o t e d t h a t the s i z e s of t r e e s s t u d i e d , w h i l e r e l a t i v e l y c o n s t a n t w i t h i n a s t u d y s i t e , d i f f e r e d between s i t e s . Trees sampled a t BRI and FUR tended t o be l a r g e r than t h o s e a t SQU, PIT, and UEL. I t i s therefore p o s s i b l e t h a t t r e e s i z e may be i n f l u e n c i n g t h e r e s u l t s t o some e x t e n t . 10 1 CHAPTER 7 - GRADIENT ANALYSIS ON THE BOLE OF ACER MACROPHYLLUM As was shown i n t h e p r e v i o u s c h a p t e r , between-tree d i f f e r e n c e s i n e p i p h y t i c v e g e t a t i o n a t t h e s i t e s a r e e v i d e n t . These d i f f e r e n c e s may be caused by m i c r o e n v i r o n m e n t a l v a r i a t i o n w i t h i n the f o r e s t , d i f f e r e n t i a l d i s p e r s a b i l i t y , and c o m p e t i t i o n . D e s p i t e t h e i n h e r e n t c o m p l e x i t y of the problem, however, the t r e e s sampled at a g i v e n s i t e a r e of a p p r o x i m a t e l y e g u a l s i z e , show t h e same degree of i n c l i n a t i o n , and are l o c a t e d i n s i m i l a r m i c r o e n v i r o n m e n t a l r e g i o n s w i t h i n t h e f o r e s t . Thus t h e t r e e b o l e s sampled r e p r e s e n t , s i m i l a r h a b i t a t s so f a r as the e p i p h y t i c v e g e t a t i o n i s concerned. The s a m p l i n g method employed was d e s i g n e d t o answer s p e c i f i c q u e s t i o n s r e g a r d i n g t h e response of the e p i p h y t i c v e g e t a t i o n t o changes i n h e i g h t and i n c l i n a t i o n on the t r e e b o l e . Barkman (1958) has s u g g e s t e d t h a t r e p l i c a t e s a m p l i n g may 'be a u s e f u l t e c h n i g u e i n e l i m i n a t i n g o t h e r f a c t o r s when exam i n i n g e c o l o g i c a l a m p l i t u d e s and i m p l i e d g r a d i e n t s on a t r e e . In t h i s s t u d y , the t r e e s a t a g i v e n s i t e a r e c o n s i d e r e d to be r e p l i c a t e samples; t h a t i s , g u a d r a t s a t each h e i g h t - i n c l i n a t i o n c o m b i n a t i o n on a l l 15 t r e e s a t a s i t e a r e assumed t o r e p r e s e n t e c o l o g i c a l l y e q u i v a l e n t m i c r o h a b i t a t s . Such a method of d a t a s u m m a r i z a t i o n a l l o w s f o r t h e a n a l y s i s of o v e r a l l e p i p h y t i c response t o changes i n h e i g h t and i n c l i n a t i o n w h i l e m i n i m i z i n g o t h e r s o u r c e s of between-tree v a r i a t i o n . A s i m i l a r s t r a t e g y has been used by Rasmussen ( 1 9 7 5 ) . . 1 0 2 Each s i t e was a n a l y z e d s e p a r a t e l y u s i n g RA. At each s i t e , a mean f r e g u e n c y v a l u e f o r each e p i p h y t i c s p e c i e s i n each o f 2 4 h e i g h t - i n c l i n a t i o n c o m b i n a t i o n s on the 1 5 t r e e s was computed. Rare s p e c i e s ( 5 % c o n s t a n c y or l e s s a t a s i t e ) were f i r s t removed from t h e d a t a s e t . Each of t h e 5 s i t e s a n a l y s e s a r e d i s c u s s e d i n t u r n below. SQU The r e s u l t a n t o r d i n a t i o n f o r t h i s s i t e i s shown i n F i g u r e 2 3 . A t o t a l of 8 e p i p h y t i c s p e c i e s were used i n the a n a l y s i s , and 7 p o s i t i v e e i g e n v a l u e s were e x t r a c t e d from t h e data set..The f i r s t a x i s a c c o u n t s f o r 5 7 . 0 1 % o f t h e t o t a l v a r i a t i o n , the second 2 3 . 5 1 % . . Hpmalia t r i c h g m a n o i d e s has h i g h p o s i t i v e w e i g h t i n g on t h e f i r s t a x i s ; L e p r a r i a membranacea, Neckera d o u g l a s i i , A n t i t r i c h i a c a l i f o r n i c a , Homalothecium f u l g e s c e n s , and Metaneckera m e n z i e s i i a l l have n e g a t i v e weight. On the second a x i s , L.. membranacea shows h i g h p o s i t i v e weight, w h i l e N-L . d o u c j l a s i i , A. c a l i f o r n i c a , H. f u l g e s c e n s , and Plagigmnium yenustum are n e g a t i v e l y weighted. The r e s u l t a n t o r d i n a t i o n s u g g e s t s t h a t q u a d r a t s at t h e 0.5 m and 1 m l e v e l s ( e s p e c i a l l y t h o s e on t h e mid and upper s i d e s ) a r e w e l l d i s t i n g u i s h e d from t h o s e a t h i g h e r e l e v a t i o n s . . T h e r e a l s o appears t o be l i t t l e d i s t i n c t i o n of e p i p h y t i c v e g e t a t i o n w i t h h e i g h t above an e l e v a t i o n of 1 m. The f i r s t a x i s appears t o monitor a h e i g h t g r a d i e n t , a l t h o u g h i t s e r v e s m a i n l y t o d i s t i n g u i s h t h e b a s a l q u a d r a t s from t h o s e h i g h e r up the b o l e . The second a x i s appears t o monitor an i n c l i n a t i o n g r a d i e n t . Quadrats from the upper s i d e o f t h e t r u n k o c c u r toward the J03 n •2 • 3 • 4 • 5 A4 A5 A4 •3 J • 5 •3 A2 A.5 A.5 Figure 23. Reciprocal averaging ordination of the 24 height-i n c l i n a t i o n combinations sampled on trees at SQU. Numbers are height i n meters. Symbols code for i n c l i n a t i o n : • = lower, A = mid, •= upper. 104 bottom of t h e o r d i n a t i o n , w h i l e q u a d r a t s from the lower s i d e are p u l l e d toward t h e t o p l e f t of the o r d i n a t i o n ; q u a d r a t s from th e mid s i d e g e n e r a l l y o c c u r between t h e s e . The i n c l i n a t i o n g r a d i e n t appears t o be f a i r l y s t r o n g a t a l l h e i g h t s (except at the t r e e base) Quadrats from the lower s i d e of t h e b o l e appear t o be the b e s t d i s t i n g u i s h e d . Here, t h e v e g e t a t i o n a p p e a r s to be s i m i l a r a t a l l h e i g h t s above 0.5 m; however, i t becomes more s i m i l a r t o t h a t of the mid s i d e w i t h i n c r e a s i n g e l e v a t i o n , s u g g e s t i n g t h a t t h e i n c l i n a t i o n g r a d i e n t may not be as s t r o n g a t h i g h e r e l e v a t i o n s (4 and 5 m) on the b o l e . On the upper s i d e of the t r e e , t h e v e g e t a t i o n a t e l e v a t i o n s of 2-5 m appears t o be v e r y s i m i l a r * . T h i s i s a l s o t r u e f o r t h e mid s i d e s i . On the mid and upper s i d e s of the b o l e , i n c l i n a t i o n appears t o be the p r i m a r y f o r c e i n f l u e n c i n g the e p i p h y t e s above 1 m; the same i s t r u e on the l o w e r s i d e of t h e b o l e beyond the 0.5 m h e i g h t . FUR The r e s u l t a n t o r d i n a t i o n f o r t h i s s i t e i s shown i n F i g u r e 24. A t o t a l o f 10 s p e c i e s were used i n the a n a l y s i s , and 9 p o s i t i v e e i g e n v a l u e s were e x t r a c t e d from the data s e t . The f i r s t component a x i s a c c o u n t s f o r 53.51% of the t o t a l v a r i a t i o n , the second 21.51%. On f i r s t component a x i s , Claopodium c r i s p i f o l i u m , I§2ihecium s t o Ion i f erum, and P o r e l l a cordaeana a r e p o s i t i v e l y w e i g h t e d , w h i l e L e p r a r i a membranacea, Metaneckera m e n z i e s i i , Zyggdon y i r i d i s s i m u s , Hgmalgthecium f u l g e s c e n s , Neckera d g u g l a s i i , and D e n d r o a l s i a a b i e t i n a are a l l n e g a t i v e l y w e i g h t e d . On t h e second a x i s , L*.. membranacea and M. . m e n z i e s i i are p o s i t i v e l y w e i g h t e d , w h i l e D._ a b i e t i n a , N . _ _ d o u g l a s i i , and n • 2 «5 • 3 •3 A4 A2 L2 Al A3 ».5 A1 A.5 "A3 1 • .5 A5 A5 Figure 24. Reciprocal averaging ordination of the 24 height-i n c l i n a t i o n combinations sampled on trees at FUR. Numbers are height i n meters. Symbols code for i n c l i n a t i o n : •= lower, A = mid, •= upper. 1 0 6 lis. £ i i i 3^ seen s are n e g a t i v e l y weighted. The r e s u l t s suggest t h a t t h e f i r s t a x i s m o n i t o r s a h e i g h t g r a d i e n t , t h e second an i n c l i n a t i o n g r a d i e n t . On t h e lower s i d e of the t r u n k , t h e h e i g h t g r a d i e n t i s not a p p arent beyond an e l e v a t i o n o f 1 m. Quadrats from t h e l ower s i d e of t h e b o l e ( e l e v a t i o n 2-5 m) form a t i g h t c l u s t e r a t the top l e f t of the o r d i n a t i o n . On both the upper and mid s i d e s o f the t r e e , the h e i g h t g r a d i e n t i s weak beyond an e l e v a t i o n of 2 m.. The i n c l i n a t i o n 'gradient appears t o be r e l a t i v e l y s t r o n g a t a l l h e i g h t s but i s most pronounced at e l e v a t i o n s above 1 m.. I n g e n e r a l , g u a d r a t s on t h e l o w e r s i d e of t h e b o l e are l o c a t e d toward t h e t o p of t h e o r d i n a t i o n , w h i l e t h o s e from the upper s i d e a r e l o c a t e d towards th e bottom end; the mid q u a d r a t s t e n d t o be l o c a t e d between t h e s e . The mid g u a d r a t s t e n d t o be f a i r l y s c a t t e r e d , however; some appear t o be more s i m i l a r t o t h e upper q u a d r a t s , o t h e r s t o t h e l ower ones. N o n e t h e l e s s the g e n e r a l t r e n d as i n d i c a t e d h o l d s , e x c e p t toward t h e t r e e base, where the lower and mid s i d e q u a d r a t s a r e somewhat i n t e r m i x e d . UEL The r e s u l t a n t o r d i n a t i o n f o r t h i s s i t e i s shown i n F i g u r e 25..A t o t a l of 9 p o s i t i v e e i g e n v a l u e s were e x t r a c t e d from a d a t a m a t r i x o f 10 e p i p h y t i c s p e c i e s . The f i r s t o r d i n a t i o n a x i s a c c o u n t s f o r 51.91% of the v a r i a t i o n , the second 23.49%. On the f i r s t a x i s , Claopodium c r i s p i f o l i u m has h i g h p o s i t i v e w e i g h t ; I s o t h e c i u m s t o l o n i f e r u m , L e p r a r i a membranacea, F r u l l a n i a t a m a r i s c i s s p . n i g g u a l l e n s i s , Homalothecium n u t t a l l i i , and Zyqodon y i r i d i s s i m u s a r e n e g a t i v e l y w eighted. .. On the second 107 n A3 A4 • 5 A5 • 4 • 3 • 2 •1 Al A.5 A.5 • 1 Figure 25. Reciprocal averaging ordination of the 24 height-i n c l i n a t i o n combinations sampled on trees at UEL. Numbers are height i n meters. Symbols code for i n c l i n a t i o n : •= lower, A = mid, •= upper. 108 a x i s , I . , s t o l o n i f erum, F._. t a m a r i s c i s s p . fiisguallensis, and I*. - Q.i±tta l l i i a re p o s i t i v e l y w e i g h t e d , w h i l e L._ . membranacea and Metaneclcera. m e n z i e s i i a r e n e g a t i v e l y weighted. . The r e s u l t s suggest a h e i g h t g r a d i e n t from t h e lower r i g h t ( b a s a l guadrats) t o the upper l e f t (5 m quadrat) o f t h e o r d i n a t i o n . T h i s g r a d i e n t i s s t r o n g e s t near t h e t r e e base, but becomes p r o g r e s s i v e l y weaker w i t h i n c r e a s i n g e l e v a t i o n . The second a x i s appears t o c o r r e s p o n d t o an i n c l i n a t i o n g r a d i e n t . Quadrats from t h e upper s i d e o f t h e b o l e occur a t the top end of the o r d i n a t i o n , w h i l e t h o s e from the lower s i d e are g e n e r a l l y r e s t r i c t e d t o the l o w e r l e f t of t h e o r d i n a t i o n ; q u a d r a t s from the mid s i d e s a re s c a t t e r e d between t h e s e . T h i s g r a d i e n t appears t o be s t r o n g e s t a t lower e l e v a t i o n s on the b o l e , becoming l e s s pronounced at h i g h e r e l e v a t i o n s . PIT The r e s u l t a n t o r d i n a t i o n f o r t h i s s i t e i s shown i n F i g u r e 26. Nine p o s i t i v e e i g e n v a l u e s were e x t r a c t e d from a data m a t r i x of 10 e p i p h y t i c s p e c i e s . . T h e f i r s t o r d i n a t i o n a x i s a c c o u n t s f o r 47.15% o f the t o t a l v a r i a t i o n i n t h e d a t a s e t , the second 26.13%. Claopodium c r i s p i f o l i u m and Apometzgeria pubescens show h i g h p o s i t i v e w e i g h t i n g on the f i r s t a x i s , w h i l e Neckera d o u g l a s i i , Homalothecium n u t t a l l i i , and L e p r a r i a membranacea are n e g a t i v e l y w eighted. On the second a x i s , L± membranacea and Metaneckera m e n z i e s i i show h i g h p o s i t i v e w e i g h t i n g ; N.. d o u q l a s i i i s n e g a t i v e l y weighted on t h i s a x i s . The f i r s t a x i s appears t o monitor a h e i g h t g r a d i e n t , w i t h e l e v a t i o n i n c r e a s i n g from r i g h t t o l e f t . . The g r a d i e n t i s 1 0 9 n •3 • 5 • 4 • 1 • 2 •.5 • 3 • 4 • 2 • 1 A1 A.5 • 3 • 4 A5 A2 • 2 • 1 A.5 A5 • • 4 3 • .5 • 5 I Figure 26. Reciprocal averaging ordination of the 24 height-i n c l i n a t i o n combinations sampled on trees at PIT. Numbers are heights i n meters. Symbols code f o r i n c l i n a t i o n : •= lower, A = m i d , •= upper. 110 s t r o n g e s t near the t r e e base, becoming l e s s pronounced at h i g h e r e l e v a t i o n s . The second a x i s m o n i t o r s an i n c l i n a t i o n g r a d i e n t . Quadrats from th e lower s i d e of t h e t r e e occur toward the top o f the o r d i n a t i o n , w h i l e t h o s e from the upper s i d e are l o c a t e d toward t h e bottom; mid q u a d r a t s o c c u r between t h e s e . On the l o w e r s i d e o f t h e b o l e , t h e h e i g h t g r a d i e n t , w h i l e p r e s e n t , i s weak above the 0.5 m l e v e l . Quadrats from the lower s i d e form a t i g h t c l u s t e r at t h e t o p l e f t of the o r d i n a t i o n . . T h e h e i g h t g r a d i e n t appears t o be s t r o n g e s t on the upper s i d e o f the t r u n k , a l t h o u g h i t i s almost e g u a l l y as s t r o n g on t h e mid s i d e s . The i n c l i n a t i o n g r a d i e n t i s s t r o n g a t a l l h e i g h t s , but appears t o be s t r o n g e s t at h i g h e r l e v e l s on t h e b o l e . BEI The r e s u l t a n t o r d i n a t i o n f o r t h i s s i t e i s shown i n F i g u r e 27. From a m a t r i x of 11 s p e c i e s , 10 p o s i t i v e e i g e n v a l u e s were e x t r a c t e d . The f i r s t o r d i n a t i o n a x i s a c c o u n t s f o r 41.49% of t h e t o t a l v a r i a t i o n i n the d a t a s e t , t h e second 2 8. 42%. . D e n d r p a l s i a a b i e t i n a , A n t i t r i c h i a c a l i f o r n i c a , Homalothecium n u t t a l l i i , and Neckera d o u q l a s _ i i a l l show h i g h p o s i t i v e w e i g h t i n g on t h e f i r s t a x i s , w h i l e Claopodium c r i s p i f o l i u m i s n e g a t i v e l y weighted. On t h e second a x i s , G r a p h i s s c r i p t a and L e p r a r i a membranacea show s t r o n g p o s i t i v e w e i g h t i n g , w h i l e D. a b i e t i n a , C._ c r i s p i f o l i u m , A. . c a l i f o r n i c a , P o r e l l a cordaeana, H._ n u t t a l l i i , Apometzgeria pubescens, Homalothecium f u l g e s c e n s , and N._ d o u g l a s i i a r e a l l n e g a t i v e l y weighted. The r e s u l t s suggest t h a t w h i l e the f i r s t a x i s m o n i t o r s a h e i g h t g r a d i e n t (with e l e v a t i o n i n c r e a s i n g from l e f t t o r i g h t ) , I l l n •1 • 3 • .5 A1 A.5 A.5 A5 A3 A3 A2 A4 A2 • 1 • .5 A4 A5 • 2 Figure 27. Reciprocal averaging ordination of the 24 height-i n c l i n a t i o n combinations sampled on trees at BRI. Numbers are heights i n meters. Symbols code for i n c l i n a t i o n : •= lower, A = = m i d , •= upper. 112 i t i s weakly d e v e l o p e d , and s e r v e s only t o s e p a r a t e b a s a l g u a d r a t s a t 0.5 m (which show h i g h f r e g u e n c y of Claopodium c r i s p i f p l i u m ) from t h e o t h e r s . . The second a x i s m o n i t o r s an i n c l i n a t i o n g r a d i e n t which appears t o be g u i t e s t r o n g . Quadrats from t h e l o w e r s i d e of the b o l e , which g e n e r a l l y o ccur a t the top end of the o r d i n a t i o n , a r e r e l a t i v e l y w e l l d i s t i n g u i s h e d from t h e o t h e r s * The upper s i d e g u a d r a t s occur a t the bottom end of the o r d i n a t i o n . . T h e mid s i d e g u a d r a t s are l o c a t e d t h o s e from the upper and lower s i d e s , but g e n e r a l l y occur c l o s e r t o t h o s e from the upper s i d e . Quadrats a t 5 m on the lower s i d e appear t o be c l o s e l y r e l a t e d f l o r i s t i c a l l y t o mid g u a d r a t s , p a r t i c u l a r i l y t h o s e n e a r e r t h e t r e e base. D i s c u s s i o n F or a l l 5 s i t e o r d i n a t i o n s , most of the t o t a l v a r i a t i o n i n the d a t a s e t has been summarized on the f i r s t 2 axes ( r a n g i n g from 69. 90% a t BRI t o 80. 52% a t SQU). The o r d i n a t i o n r e s u l t s from a l l s i t e s s u g g e s t t h a t the f i r s t component a x i s g e n e r a l l y c o r r e s p o n d s t o the h e i g h t g r a d i e n t on the t r e e b o l e , the second to t h e i n c l i n a t i o n g r a d i e n t . However, d i r e c t r e l a t i o n s h i p s between t h e l i n e a r , m a t h e m a t i c a l l y d e r i v e d component axes and the complex m i c r o e n v i r o n m e n t a l g r a d i e n t s c l e a r l y cannot be e x p e c t e d . C l o s e r i n s p e c t i o n of t h e s t r u c t u r e of the p o i n t s o f t h e o r d i n a t i o n o f t e n r e v e a l s a more complex n o n - l i n e a r r e s p o n s e of a g i v e n g r a d i e n t w i t h r e g a r d t o the component a x i s (at l e a s t over p a r t of i t s r a n g e ) . Such a response i s t o be e x p e c t e d because of t h e i n h e r e n t c o m p l e x i t y of the v e g e t a t i o n and t h e 113 g r a d i e n t s , and because of complex i n t e r a c t i o n s between t h e s e 2 g r a d i e n t s . N o n e t h e l e s s , the r e s u l t a n t o r d i n a t i o n s do suggest a c o r r e s p o n d e n c e between t h e h e i g h t and i n c l i n a t i o n g r a d i e n t s and t h e f i r s t and second component axes r e s p e c t i v e l y . . T h i s o b s e r v a t i o n , c o u p l e d w i t h the h i g h amount of v a r i a t i o n a c counted f o r by t h e f i r s t 2 a x e s , would suggest t h a t t h e s e g r a d i e n t s are i m p o r t a n t i n i n f l u e n c i n g e p i p h y t i c d i s t r i b u t i o n s on the b o l e . S i n c e t h e h e i g h t g r a d i e n t ( f i r s t a x i s ) a c c o u n t s f o r the most v a r i a t i o n , i t would appear t h a t t h i s g r a d i e n t i s most i n f l u e n t i a l t o t h e v e g e t a t i o n . . I t has a l r e a d y been n o t e d , however, t h a t t h e importance o f t h e h e i g h t g r a d i e n t becomes l e s s pronounced w i t h i n c r e a s i n g e l e v a t i o n . A l s o , t h e h e i g h t g r a d i e n t appears t o be most i m p o r t a n t i n d i s t i n g u i s h i n g the b a s a l v e g e t a t i o n from t h a t h i g h e r up the b o l e . I t would appear t h a t s i t e f a c t o r s may i n f l u e n c e t h e degree t o which e p i p h y t i c v e g e t a t i o n responds t o t h e h e i g h t g r a d i e n t . At s i t e s where the h u m i d i t y and l i g h t g r a d i e n t s are s t r o n g e s t (and most v a r i a b l e ) , i t might be expected t h a t the e p i p h y t i c response t o the h e i g h t g r a d i e n t would a l s o be s t r o n g . These g r a d i e n t s w i l l be s t r o n g e s t (and h u m i d i t y v a l u e s l o w e s t , f l u c t u a t i o n s g r e a t e s t ) i n a r e a s w i t h a more open canopy, and i n s m a l l e r f o r e s t s . Water l o s s ( r a t e of d e s i c c a t i o n ) might a l s o be e x p e c t e d t o be g r e a t e r i n such a r e a s . I t i s not s u r p r i s i n g , t h e n , t h a t t h e response of the e p i p h y t i c v e g e t a t i o n t o t h e h e i g h t g r a d i e n t i s s t r o n g e s t a t PIT and UEL, s i t e s with a f a i r l y open d e c i d u o u s canopy w i t h i n a s m a l l f o r e s t surrounded by open, d i s t u r b e d areas._ At FUE ( l o c a t e d w i t h i n a s m a l l f o r e s t s u r r o u n d e d by ocean and c l e a r e d a r e a s ) , the h e i g h t g r a d i e n t i s 1 1 4 f a i r l y w e l l developed though not as s t r o n g as a t PIT or UEL; t h i s may be because t h e dense mixed d e c i d u o u s - c o n i f e r o u s canopy at t h i s s i t e i n t e r c e p t s most of t h e incoming l i g h t and a l l o w s the b u i l d u p o f a humid a i r l a y e r below the canopy.. The h e i g h t g r a d i e n t i s very weak a t BRI. T h i s s i t e i s l o c a t e d w i t h i n a v e r y dense, e x t e n s i v e f o r e s t , w i t h c o n s i t e n t l y h i g h h u m i d i t y . . L i t t l e d i r e c t l i g h t i s a b l e t o p e n e t r a t e t h e dense canopy. The h e i g h t g r a d i e n t i s a l s o weak at SQU. The c o m b i n a t i o n of h i g h c l o u d c o v e r and p r e c i p i t a t i o n , a dense u n d e r s t o r y ( h i g h t r a n s p i r a t i o n r a t e ) , and s i t e l o c a t i o n , ensure a h i g h h u m i d i t y a t t h i s s i t e . A h u m i d i t y g r a d i e n t a t t h e s i t e may be d e v e l o p e d , but h i g h h u m i d i t y and r a i n f a l l may o v e r r i d e i t s i n f l u e n c e . These f a c t o r s c o u l d e x p l a i n why the e p i p h y t i c response t o e l e v a t i o n i s not s t r o n g a t t h i s s i t e . At a l l s i t e s , t h e h e i g h t g r a d i e n t appears t o be weakest on t h e l o w e r s i d e of the b o l e , which i s much d r i e r than the upper and mid s i d e s . T h i s s i d e of the b o l e r e p r e s e n t s a h a r s h environment t o which few s p e c i e s can adapt (above th e t r e e base, the l i c h e n L e p r a r i a membranacea i s dominant). Thus, a l t h o u g h d i r e c t f a c t o r s i n f l u e n c i n g the complex h e i g h t g r a d i e n t s (such as t h e l i g h t and h u m i d i t y g r a d i e n t s ) may be e g u a l l y s t r o n g around the b o l e , water s u p p l y i s a l i m i t i n g f a c t o r which has an o v e r r i d i n g i n f l u e n c e on e p i p h y t i c d i s t r i b u t i o n s on the lower s i d e o f t h e b o l e . The i n c l i n a t i o n g r a d i e n t appears t o be s t r o n g at a l l s i t e s . A l t h o u g h t h e response t o t h i s g r a d i e n t v a r i e s somewhat between s i t e s , some o v e r a l l t r e n d s are a p p a r e n t . I n g e n e r a l , lower s i d e g u a d r a t s t e n d t o form the most d i s t i n c t group; w h i l e the upper 115 and mid s i d e s a re a l s o d i s t i n c t , they appear t o be more f l o r i s t i c a l l y s i m i l a r t o one a n o t h e r . The i n c l i n a t i o n g r a d i e n t at most o f t h e s i t e s i s not as s t r o n g at and near t h e t r e e base. T h i s i s p r o b a b l y because many t r e e bases are s p l a y e d o u t , so t h a t t h e b a s a l microenvironment and h a b i t a t a r e f a i r l y s i m i l a r a l l t h e way around the t r e e b o l e . A l s o , a t some of the s i t e s ( p a r t i c u l a r i l y SQU, UEL, and BRI) t h e r e i s some s u g g e s t i o n t h a t the i n c l i n a t i o n g r a d i e n t becomes l e s s d i s t i n c t a t h i g h e r e l e v a t i o n s (4-5 m) on the b o l e . T h i s i s o f t e n observed i n t h e f i e l d , and can be a t t r i b u t e d a t l e a s t i n p a r t t o the f a c t t h a t a t h i g h e r e l e v a t i o n s the t r e e b o l e t e n d s t o become more v e r t i c a l l y o r i e n t e d , so t h a t the d i s t i n c t i o n between the upper and l o w e r s i d e s of t h e t r u n k become l e s s pronounced. 116 CHAPTER 8 - EPIPHYTIC SPECIES AND SPECIES RELATIONSHIPS I n t h e p r e v i o u s c h a p t e r , t h e e p i p h y t i c v e g e t a t i o n has been shown t o respond t o changes i n e l e v a t i o n and i n c l i n a t i o n (complex m i c r o e n v i r o n m e n t a l g r a d i e n t s ) , s u g g e s t i n g t h a t the i n d i v i d u a l e p i p h y t i c s p e c i e s may occupy d i s t i n c t h a b i t a t s on t h e t r e e b o l e . I n t h i s c h a p t e r , s p e c i e s h a b i t a t p r e f e r e n c e s and t h e i r e c o l o g y are examined. The response o f each o f t h e most common s p e c i e s t o the h e i g h t and i n c l i n a t i o n g r a d i e n t s a re examined a t each of the 5 s i t e s . The method a l l o w s f o r s p e c u l a t i o n as t o the c o m p e t i t i v e i n t e r a c t i o n s between s p e c i e s , and i n d i c a t e s n i c h e p r e f e r e n c e s and degree of n i c h e o v e r l a p f o r each s p e c i e s . S p e c i e s a s s o c i a t i o n s (used here i n t h e sense o f s p e c i e s c o - o c c u r r e n c e i n guadrats) a r e a l s o examined. F i n a l l y , each o f the common e p i p h y t i c s p e c i e s i s d i s c u s s e d w i t h r e g a r d t o i t s e c o l o g y , h a b i t a t p r e f e r e n c e s , growth-form, s i z e , h a b i t , s o c i a b i l i t y , and a s s o c i a t i o n s . S p e c i e s A s s o c i a t i o n s There a re a number o f methods a v a i l a b l e t o measure a s s o c i a t i o n between s p e c i e s , v a r y i n g from c a s u a l o b s e r v a t i o n s t o s t a t i s t i c a l a n a l y s e s r e g u i r i n g s p e c i f i c s a m p l i n g p r o c e d u r e s . I n s t u d i e s o f e p i p h y t i c v e g e t a t i o n , s p e c i e s a s s o c i a t i o n s have o f t e n been d i s c u s s e d i n d e s c r i b i n g e p i p h y t i c communities (Barkman 1958, Hoffman and K a z m i e r s k i 1969, and o t h e r s ) . S t r i n g e r and S t r i n g e r (1974) and Rasmussen (1975) used c h i - s g u a r e ( s p e c i e s 117 p a i r w i s e c omparisons u s i n g presence-absence data) t o s t a t i s t i c a l l y a n a l y z e t h e degree o f a s s o c i a t i o n between s p e c i e s . The degree of e p i p h y t i c a s s o c i a t i o n and r e l a t i o n s h i p s between s p e c i e s have been examined u s i n g m u l t i v a r i a t e methods (P-Co-A, cos t h e t a s i m i l a r i t y f u n c t i o n , as d e s c r i b e d i n C h apter 5)._Such a procedure summarizes t h e v a r i a t i o n i n the d a t a s e t and produces a s c a t t e r p l o t of s p e c i e s p o i n t s . P o s i t i o n a l r e l a t i o n s h i p s between t h e s e p o i n t s i n d i c a t e s p e c i e s r e l a t i o n s h i p s . The method does not measure the s i g n i f i c a n c e of a s s o c i a t i o n s (as does the c h i - s g u a r e method) but has advantages i n t h a t i t uses q u a n t i t a t i v e measures and summarizes t h e r e l a t i o n s h i p s between s p e c i e s i n a s i n g l e diagram which i s r e a d i l y i n t e r p r e t a b l e ( O r l o c i 1978). Because i t was f e l t t h a t s p e c i e s r e l a t i o n s h i p s may v ary between s i t e s , each of t h e 5 s t u d y s i t e s was a n a l y z e d s e p a r a t e l y . O v e r a l l s p e c i e s r e l a t i o n s h i p s were measured; f o r each a n a l y s i s , a s p e c i e s s i m i l a r i t y m a t r i x (as d e f i n e d by the c o s - t h e t a f u n c t i o n ) u s i n g data from the 15 t r e e s a t a l l s a m p l i n g p o s i t i o n s was computed. R e s u l t a n t s i m i l a r i t y m a t r i c e s f o r t h e 5 s i t e s are shown i n Table 2 3 . . S p e c i e s o c c u r r i n g i n fewer t h a n 18 g u a d r a t s (constancy of 5%) a t a g i v e n s i t e were not used i n t h e a n a l y s i s , s i n c e t h e i r o c c u r r e n c e a t the s i t e i s not h i g h enough f o r m e a n i n g f u l i n t e r p r e t a t i o n . The r e s u l t s f o r each o f t h e s i t e s a r e d i s c u s s e d i n t u r n below. SQU The r e s u l t a n t s p e c i e s o r d i n a t i o n f o r t h i s s i t e i s shown i n 118 SQU MET MEN LEP MEM 273 HOM FUL 238 162 NEC DOU 123 77 287 POR COR 179 62 383 258 PLA VEN 120 9 337 154 ANT CAL 101 8 117 157 HOM TRI 50 3 167 48 FUR MET MEN LEP MEM HOM FUL NEC DOU CLA CRI POR COR ISO STO DEN ABI ZYG VIR POR NAV 380 154 150 148 147 281 132 52 128 124 180 142 161 171 564 42 76 97 138 297 31 83 99 94 50 293 252 116 55 19 47 33 59 141 77 122 154 429 302 72 150 39 UEL MET MEN LEP MEM 337 HOM FUL 92 241 NEC DOU 35 207 190 CLA CRI 89 179 231 92 POR COR 50 109 160 107 350 ISO STO 15 394 158 131 133 HOM NUT ZYG VIR FRU TAM 86 67 306 97 145 32 100 79 93 303 78 50 26 62 45 25 3 312 94 220 24 111 361 201 54 Table 23. Matrices of s i m i l a r i t y (cos theta function, xlO 3) between epiphytic species, for each of the 5 study s i t e s . PIT MET MEN LEP MEM 396 HOM FUL 117 99 NEC DOU 101 116 173 CLA CRI 176 30 169 56 POR COR 86 23 188 245 166 ISO STO 62 14 89 74 54 109 HOM NUT 92 161 242 175 38 138 POR NAV 72 48 167 260 157 119 APO PUB 54 7 122 14 208 143 BRI MET MEN LEP MEM 229 HOM FUL 222 104 NEC DOU 102 75 121 CLA CRI 165 45 249 POR COR 82 17 186 DEN ABI 195 57 59 APO PUB 86 2 54 ANT CAL 102 2 96 GRA SCR 85 183 53 Table 23. continued. 100 211 98 141 12 97 95 326 118 21 100 0 70 88 0 4 0 25 11 0 13 120 PLA VEN HOM TRI ANTCAL NEC DOU • HOM FUL POR COR MET MEN LEP MEM Figure 28. Ordination (P-Co-A) of common epiphytic species at SQU. 121 F i g u r e 28. A t o t a l o f 8 s p e c i e s were o r d i n a t e d , and the a n a l y s i s e x t r a c t e d 7 p o s i t i v e e i g e n v a l u e s . The f i r s t a x i s a c c o u n t s f o r 21.12% o f t h e t o t a l v a r i a t i o n i n t h e data s e t , t h e second 17.74%. The r e s u l t s suggest t h a t L e p r a r i a membranacea and M t a n e c k e r a m e n z i e s i i show s t r o n g p o s i t i v e a s s o c i a t i o n ; t h e s e s p e c i e s o f t e n c o - o c c u r on t h e l o w e r s i d e of the b o l e . A n t i t r i c h i a c a l i f o r n i c a i s p o s i t i v e l y weighted on the second a x i s , and i s p o s i t i v e l y a s s o c i a t e d w i t h Neckera d o u g l a s i i . Plagiomnium yenusturn, P o r e l l a cordaeana, and Homalothecium £aiaescens show p o s i t i v e a s s o c i a t i o n w i t h one a n o t h e r ; t h e y o ccur t o g e t h e r on the upper s i d e of the b o l e . . Hgmalia t r i c h o m a n o i d e s i s a l s o a s s o c i a t e d w i t h t h i s group, and most s t r o n g l y w i t h P._ yenustum. N._ d o u g l a s i i and M. . m e n z i e s i i a l s o appear t o show some p o s i t i v e a s s o c i a t i o n w i t h t h i s group.. FUR The r e s u l t a n t o r d i n a t i o n of s p e c i e s a t t h i s s i t e i s shown i n F i g u r e 29. A t o t a l o f 10 s p e c i e s were o r d i n a t e d , and from t h e a n a l y s i s 9 p o s i t i v e e i g e n v a l u e s were e x t r a c t e d . The f i r s t a x i s a c c o u n t s f o r 19.65% of the t o t a l v a r i a n c e i n t h e data s e t , t h e second 14.50%.. The r e s u l t s suggest t h r e e f a i r l y d i s t i n c t s p e c i e s g r o u p i n g s . C l a o p o d i um c r i s p i f g l i u m , P o r e l l a cordaeana, and £°rella n a y i c u l a r i s are a l l p o s i t i v e l y a s s o c i a t e d ; t h e s e s p e c i e s t e n d t o o c c u r t o g e t h e r a t or near the t r e e base. Metaneckera m e n z i e s i i , L e p r a r i a membranacea, and Zyjjodon y i r i d i s s i m u s a re h i g h l y p o s i t i v e l y a s s o c i a t e d , and o f t e n occur t o g e t h e r on t h e 122 CLA CRI POR COR POR NAV ISO STO n HOM FUL VlEC DOU DEN ABI MET MEN LEP MEM #ZYG VIR Figure 29. Ordination (P-Co-A) of common epiphytic species at FUR. 123 d r i e r , lower s i d e of the t r e e b o l e . D e n d r o a l s i a a b i e t i n a , Neckera d o u g l a s i i , and Homalothecium f u l g e s c e n s commonly occur a t h i g h e r e l e v a t i o n s on t h e upper s i d e o f t h e b o l e , and show v a r y i n g degrees o f p o s i t i v e a s s o c i a t i o n w i t h one a n o t h e r . I s o t h e c i u m s t o l o n i f e r u m o c c u r s between t h e l a t t e r 2 g r o u p s , b e i n g p o s i t i v e l y a s s o c i a t e d w i t h n a y i c u l a r i s , N._ d o u g l a s i i , and H t f u l q e s c e n s . T h i s s p e c i e s i s most common on the upper s i d e of the b o l e j u s t above t h e t r e e base. UEL The r e s u l t a n t s p e c i e s o r d i n a t i o n f o r t h i s s i t e i s shown i n F i g u r e 30. A t o t a l of 10 s p e c i e s were o r d i n a t e d , and from t h e a n a l y s i s 9 p o s i t i v e e i g e n v a l u e s were e x t r a c t e d . The f i r s t a x i s a c c o u n t s f o r 16.96% of the t o t a l v a r i a n c e i n t h e data s e t , the second 15.93%. The r e s u l t s suggest t h a t Claopgdium c r i s p i f o l i u m and P o r e l l a c o r daeana, which a r e l a r g e l y r e s t r i c t e d to the t r e e base, a r e s t r o n g l y p o s i t i v e l y a s s o c i a t e d ; a l s o , Homalothecium fui2§scens, which i s common on the upper s i d e o f the b o l e a t lower e l e v a t i o n s , i s p o s i t i v e l y a s s o c i a t e d w i t h t h e s e b a s a l s p e c i e s . . Metaneckera m e n z i e s i i , Zyjjgdon y i r i d i s s i m u s , Homalothecium n u t t a l l i i , and L e p r a r i a membranacea , a l l of which a r e most common on t h e d r i e r , lower t o mid s i d e s of t h e b o l e , show v a r y i n g degrees of p o s i t i v e a s s o c i a t i o n . F£il!lania t a m a r i s c i s s p . n i s g u a l l e n s i s and I s o t h e c i u m s t o l o n i f e r u m show a h i g h degree of p o s i t i v e a s s o c i a t i o n . Neckera d o u g l a s i i does not show h i g h p o s i t i v e a s s o c i a t i o n w i t h any of the o t h e r s p e c i e s , but appears t o be most c l o s e l y a s s o c i a t e d w i t h 1^ s t o l o n i f e r u m 124 ZYG VIR HOM NUT LEP MEM MET MEN CLA CRI HOM FUL POR COR NEC DOU ISO STO FRU TAM Figure 30. Ordination (P-Co-A) of common epiphytic species at UEL. 125 n *APO P U B C L A C R I M E T M E N L E P M E M — I P O R C O R H O M F U L ' I S O S T O P O R N A V N E C D O U H O M N U T Figure 31. Ordination (P-Co-A) of common epiphytic species stt PIT. 126 and H. f a l b e s c e n s . PIT The r e s u l t a n t o r d i n a t i o n o f s p e c i e s at t h i s s i t e i s shown i n F i g u r e 31. A t o t a l o f 10 e p i p h y t i c s p e c i e s were o r d i n a t e d , w i t h t h e a n a l y s i s e x t r a c t i n g 9 p o s i t i v e e i g e n v a l u e s . The f i r s t component a x i s a c c o u n t s f o r 16.04% of the t o t a l v a r i a t i o n i n the data s e t , t h e second 14.85%., The r e s u l t s suggest t h r e e major groups of a s s o c i a t e d s p e c i e s . . Claopodium g r i p i f o l i u m and Appmetzqeria pubescens, which a r e most common at t h e t r e e base, show s t r o n g p o s i t i v e a s s o c i a t i o n . Metaneckera m e n z i e s i i and L e p r a r i a membranacea, which o f t e n c o - o c c u r on t h e lower s i d e of the b o l e , a r e a l s o p o s i t i v e l y a s s o c i a t e d . S p e c i e s which a r e g e n e r a l l y r e s t i c t e d t o the upper s i d e of t h e b o l e a t h i g h e r e l e v a t i o n s , i n c l u d i n g Pore11a cordaeana, Homalothecium f u l g e s c e n s , I s o t h e c i u m s t o l o n i f e r u m , P o r e l l a n a y i c u l a r i s , Neckera d o u g l a s i i , and Homalothecium n u t t a l l i i , show v a r y i n g degrees of p o s i t i v e a s s o c i a t i o n w i t h one another. BRI The r e s u l t a n t s p e c i e s o r d i n a t i o n f o r t h i s s i t e i s shown i n F i g u r e 32. A t o t a l o f 10 e p i p h y t i c s p e c i e s were o r d i n a t e d , and from the a n a l y s i s 9 p o s i t i v e e i g e n v a l u e s were e x t r a c t e d . The f i r s t component a x i s accounts f o r 15.63% of t h e t o t a l v a r i a t i o n i n t h e da t a s e t , t h e second 14.22%. L e p r a r i a membranacea and G r a p h i s s c r i p t a , two l i c h e n s common on t h e d r i e r , lower s i d e of the b o l e , show high p o s i t i v e 127 'CLACRI "APOPUB IT HOM FUL POR COR NEC DOU MET MEN DENABI *ANT CAL [LEP MEM GRA SCR Figure 32. Ordination (P-Co-A) of common epiphytic species at BRI. 128 a s s o c i a t i o n . Claopodium c r i s p i f o l i u m and Appmetzgeria pubescens, which are a l s o p o s i t i v e l y a s s o c i a t e d , are g e n e r a l l y r e s t r i c t e d to the t r e e base. A n t i t r i c h i a c a l i f o r n i c a , D e n d r o a l s i a a b i e t i n a , Neckera d o u g l a s i i , and P o r e l l a cordaeana, a l l of which are most common a t mid to higher e l e v a t i o n s on the upper s i d e of the i n c l i n e d b o l e , show varying degrees of p o s i t i v e a s s o c i a t i o n . Homalothecium f u l g e s c e n s and Metaneckera m e n z i e s i i appear to be somewhat p o s i t i v e l y a s s o c i a t e d ; the l a t t e r s p e c i e s , which i s common on the upper side of the bole and may occur on the lower s i d e , i s a l s o s l i g h t l y p o s i t i v e l y a s s o c i a t e d with the l i c h e n s L. membranacea and Graphis s c r i p t a . .H^ f u l g e s c e n s , which often occurs nearer the t r e e base, shows some degree of p o s i t i v e a s s o c i a t i o n with both A._ pubescens and C.. c r i s p i f olium. D i s c u s s i o n The r e s u l t s suggest t h a t s p e c i e s a s s o c i a t i o n s are to some extent s i m i l a r over the 5 s i t e s , although important d i f f e r e n c e s are apparent.. These d i f f e r e n c e s are l i k e l y a t t r i b u t a b l e t o the d i f f e r e n t i a l response of a given e p i p h y t i c s p e c i e s to m i c r o h a b i t a t v a r i a t i o n at each of the s i t e s . At a l l s i t e s , s p e c i e s a s s o c i a t i o n s appear to correspond t o the s p a t i a l d i s t r i b u t i o n and h a b i t a t p r e f e r e n c e s of s p e c i e s on the b o l e . I t i s important to d i s t i n g u i s h between s p e c i e s a s s o c i a t i o n s and c o m p e t i t i o n . L e p r a r i a membranacea and Metaneckera m e n z i e s i i are p o s i t i v e l y a s s o c i a t e d at most of the s i t e s , but appear to be s t r o n g l y c o m p e t i t i v e . . In d r i e r r e g i o n s , the l i c h e n L. membranacea may grow over and k i l l bryophyte s p e c i e s ; s i m i l a r 129 o b s e r v a t i o n s have been made by Barkman (1958). Yet s p e c i e s which are n e g a t i v e l y a s s o c i a t e d may a l s o be s t r o n g l y c o m p e t i t i v e ; t h e y may have come t o be n e g a t i v e l y a s s o c i a t e d t h r o u g h c o m p e t i t i v e e x c l u s i o n * Thus, no c o n c l u s i o n s c o n c e r n i n g c o m p e t i t i o n between s p e c i e s can be drawn from the a n a l y s i s of t h e i r a s s o c i a t i o n s . I n d i v i d u a l S p e c i e s Response to t h e H e i g h t and I n c l i n a t i o n G r a d i e n t s The s p e c i e s o r d i n a t i o n s have q u a n t i f i e d the a s s o c i a t i o n o f e p i p h y t i c s p e c i e s a t each s i t e . I n t h i s and the f o l l o w i n g s e c t i o n , the e c o l o g y and p r e f e r r e d habitat's of t h e more common e p i p h y t i c s p e c i e s on Acer macrophyllum a re d i s c u s s e d . The e p i p h y t i c v e g e t a t i o n has been shown t o respond t o h e i g h t and i n c l i n a t i o n g r a d i e n t s a l o n g the b o l e * The response o f the i n d i v i d u a l s p e c i e s t o t h e s e g r a d i e n t s has been examined u s i n g a t h r e e - d i m e n s i o n a l p l o t t i n g s u b r o u t i n e (UBC SCATCN) to p l o t s p e c i e s performance ( i n terms of mean s p e c i e s f r e g u e n c y ) a g a i n s t guadrat a n g l e and h e i g h t . . R e c a l l t h a t h e i g h t ( i n meters) and a n g l e ( i n d e g r e e s , measured u s i n g a c l i n o m e t e r ) were r e c o r d e d a t each gua d r a t . For the purpose of t h e s e p l o t s , g uadrat a n g l e i s a b e t t e r measure o f t h e i n c l i n a t i o n g r a d i e n t than i s o v e r a l l t r u n k i n c l i n a t i o n (upper v s . . l o w e r s i d e ) ; t r e e s may show d i f f e r i n g degrees of l e a n , and t r e e l e a n may vary w i t h h e i g h t . . For the purpose o f s u m m a r i z a t i o n , guadrat a n g l e (a c o n t i n u o u s measure) has been" c a t e g o r i z e d i n t o 5 groups: 95° and above, 92°-94°, 89°-91°, 86°-88°, and 85° and l e s s ( g u a d r a t s w i t h an a n g l e g r e a t e r than 90° a r e on the upper s i d e of the b o l e , w h i l e t h o s e w i t h an a n g l e l e s s t h a n 90° are on the lower 1 3 0 s i d e ) . . Each s i t e was a n a l y z e d s e p a r a t e l y . For each s p e c i e s , a mean l o c a l f r e g u e n c y was computed f o r each o f the 30 a n g l e -h e i g h t c o m b i n a t i o n s . Rare s p e c i e s were not a n a l y z e d s i n c e t h e i r o c c u r r e n c e i s so s p o r a d i c t h a t g e n e r a l c o n c l u s i o n s c o n c e r n i n g t h e i r d i s t r i b u t i o n cannot be made. The r e s u l t a n t d i r e c t o r d i n a t i o n s are shown i n Appendix 3' (note t h a t i n some c a s e s i t was n e c e s s a r y t o r e v e r s e the o r d e r of the g u a d r a t angle a x i s t o improve t h e l o o k of the r e s u l t a n t p l o t ) . These p l o t s c o n s i s t of h i l l s and v a l l e y s which c o r r e s p o n d t o s p e c i e s f r e g u e n c y a t d i f f e r e n t p o s i t i o n s on the t r e e . O v e r a l l t r e n d s i n s p e c i e s b e h a v i o u r at a s i t e a re summarized; however, d e t a i l s of the r e s u l t a n t p l o t s may be somewhat m i s l e a d i n g because of s a m p l i n g e r r o r o r i n s u f f i c i e n t s a m p l i n g ( e s p e c i a l l y of r a r e r s p e c i e s ) . These d i r e c t o r d i n a t i o n s d i s c u s s e d and summarized i n the f o l l o w i n g s e c t i o n . Ecolcg_y of S p e c i e s E p i p h y t i c on Acer macrophyllum I t might be expected t h a t each e p i p h y t i c s p e c i e s w i l l r espond t o the a v a i l a b l e m i c r o h a b i t a t s on a t r e e b o l e by s p e c i a l i z i n g i n i t s e c o l o g i c a l r e q u i r e m e n t s ; t h a t i s , i t w i l l occupy a s p e c i f i c n i c h e space. In t h i s s e c t i o n , i n f o r m a t i o n from the p r e v i o u s 2 s e c t i o n s and p r e v i o u s c h a p t e r s i s summarized i n a d i s c u s s i o n o f t h e e c o l o q y of t h e more common e p i p h y t i c s p e c i e s found growing on Acer macrophyllum. I n f o r m a t i o n on s p e c i e s growth form, s o c i a b i l i t y , s i z e , h a b i t , m i c r o h a b i t a t p r e f e r e n c e s on the b o l e , and a s s o c i a t i o n s are b r i e f l y summarized..High s o c i a b i l i t y as used here i m p l i e s t h a t the s p e c i e s tends t o occur i n t e r m i x e d w i t h o t h e r s p e c i e s , and t h u s d i f f e r s from the 131 d e f i n i t i o n used by the Braun-Blanguet s c h o o l of p h y t o s o c i o l o g y . Each s p e c i e s i s d i s c u s s e d below. Mosses are d i s c u s s e d f i r s t , f o l l o w e d by h e p a t i c s , l i c h e n s , and f i n a l l y v a s c u l a r p l a n t s . Mosses Metaneckera m e n z i e s i i I n m o i s t h a b i t a t s on the upper s i d e o f the b o l e , t h i s s p e c i e s may form l a r g e , e x t e n s i v e mats 8-10 cm t h i c k . I n d i v i d u a l p l a n t s a r e l a r g e , u s u a l l y 15-20 cm i n l e n g t h , w i t h branches 0.5-3 cm l o n g , and are b a s a l l y a t t a c h e d . Mats vary i n s i z e , from s m a l l e r (60-70 cm) hummocky mats t o l a r g e , monotypic mats which may be s e v e r a l meters i n l e n g t h . Such mats a r e o f t e n l o o s e l y a t t a c h e d t o t h e s u b s t r a t e * In d r i e r h a b i t a t s , and on t h e lower s i d e o f t h e t r e e b o l e , t h e s p e c i e s i s much s m a l l e r (3-4 cm) and forms s m a l l e r t u f t - l i k e c o l o n i e s . These p l a n t s a r e o f t e n h i g h l y f l a g e l l i f o r m , and s t r o n g l y a t t a c h e d t o the s u b s t r a t e . T h i s s p e c i e s shows v a r y i n g degrees of s o c i a b i l i t y depending upon h a b i t a t . On the upper s i d e of the b o l e , i t may oc c u r w i t h mats of Neckera d o u ^ l a s i i and D e n d r o a l s i a a b i e t i n a . I t has been observed t o grow over and smother out s p e c i e s which grow c l o s e l y a p p r e s s e d t o the bark (eg. . Homalothecium f u l q e s c e n s ) . . On the d r i e r p a r t s of t h e b o l e , L e p r a r i a membranacea may grow on and e v e n t u a l l y k i l l i t . C o n v e r s e l y , mats of Metaneckera m e n z i e s i i may form l a r g e c o l o n i e s which grow over and k i l l t h i s l i c h e n . 132 T h i s s p e c i e s shows d i f f e r e n t h a b i t a t p r e f e r e n c e s on t h e t r e e b o l e a t t h e 5 s i t e s (Appendix 3 ) . . A t SQU, FUR, PIT, and BRI, the s p e c i e s grows be s t on the mid t o upper s i d e s o f t h e t r u n k . . F r e g u e n c y appears t o be h i g h e s t at mid e l e v a t i o n s (1-4 m), a l t h o u g h t h i s v a r i e s between s i t e s . At most s i t e s f r e g u e n c y d e c r e a s e s a t h i g h e r e l e v a t i o n s . At UEL, the s p e c i e s shows a d e f i n i t e p r e f e r e n c e f o r the l o w e r s i d e of the t r u n k a t lower e l e v a t i o n s . T h i s i s the o n l y b r y o p h y t e s p e c i e s common on the mid and lower s i d e s of t h e b o l e , which e x p l a i n s i t s h i g h a s s o c i a t i o n w i t h L e p a r i a membranacea a t a l l t h e s i t e s . The s p e c i e s i s most common a t BRI, where i t forms l a r g e mats on the upper s i d e o f the b o l e ( F i g u r e 3 3 ) , a l t h o u g h i t a l s o o c c u r s on the mid and lower s i d e s . At a l l t h e s i t e s , t h i s s p e c i e s appears t o be most common on l a r g e t r e e s . I t i s a l s o common on t r e e s sampled i n t h e p r e s e n t s t u d y , but r a r e l y o c c u r s on s m a l l t r e e s . The s p e c i e s appears t o p r e f e r the more decomposed bark of o l d e r t r e e s , and re a c h e s i t s b e s t development on t r e e bark r i c h i n c a l c i u m (nearer the t r e e base, and a t s i t e s where bark c a l c i u m l e v e l s are high) . Necicera d o u g l a s i i T h i s i s a l a r g e p l a n t (10-20 cm l o n g , w i t h branches 1-3 cm i n l e n g t h ) of humid h a b i t a t s . . P l a n t s a r e b a s a l l y a t t a c h e d , o f t e n q u i t e l o o s e l y ( e s p e c i a l l y i f the bark i s h i g h l y decomposed). At UEL, s m a l l mats o f t h i s s p e c i e s a re found , o f t e n c o n s i s t i n g o f o n l y a few p l a n t s . . Figure 33. Large mat of Metaneckera menziesii growing on a mature tree of Acer macrophyllum at BRI. Patches of Dendroalsia a b i e t i n a are also present. Tree DBH = 820 mm. Figure 34. Large mat of Dendroalsia a b i e t i n a growing on the lower trunk of Acer macro- phyllum at BRI. Tree DBH = 740 mm. 134 T h i s s p e c i e s forms l a r g e monotypic mats. I t i s o f t e n p a r t of t h e s p e c i e s 'mosaic' on t h e b o l e , and shows s t r o n g p o s i t i v e a s s o c i a t i o n w i t h Homalgthec ium f u l g e s c e n s , P o r e l l a s s p . , Homalothecium n u t t a l l i i , D e n d r o a l s i a a b i e t i n a , and Metaneckera m e n z i e s i i . I t i s o f t e n found growing over s p e c i e s which grow c l o s e l y a ppressed t o the bar k . The s p e c i e s i s ' a l s o very common on young t r e e s i n moist h a b i t a t s (BRI, FDR, SQU) . On very o l d t r e e s , i t may be outcompeted by Metaneckera m e n z i e s i i and D e n d r o a l s i a a b i e t i n a . T h i s s p e c i e s i s most common a t h i g h e r e l e v a t i o n s (3-5 m) on the upper s i d e of the t r u n k (Appendix 3 ) . Trends a t UEL a r e not r e a d i l y a p p a r e n t , however, p r o b a b l y because t h e s p e c i e s i s r a r e at t h i s s i t e . T h i s s p e c i e s shows h i g h e s t f r e g u e n c y a t SQU and PIT (moist s i t e s w i t h a f a i r l y open, deciduous canopy), s u g g e s t i n g t h a t t h i s s p e c i e s might p r e f e r humid a r e a s w i t h h i g h e r l i g h t i n t e n s i t y . Olaopodium c r i s p i f o l i u m P l a n t s of t h i s s p e c i e s a r e g e n e r a l l y 3-4 cm l o n g , but may r e a c h 10 cm i n l e n g t h * They a r e g e n e r a l l y h i g h l y branched and form dense, i n t e r w o v e n mats. These mats are u s u a l l y 4-6 cm deep, and o f t e n grow over a humus l a y e r o f d e c a y i n g bark and e p i p h y t i c v e g e t a t i o n . T h i s s p e c i e s i s g e n e r a l l y r e s t r i c t e d t o t h e s p l a y e d - o u t t r e e base (Appendix 3)..On t r e e s w i t h a . l a r g e l e a n , the s p e c i e s may o c c u r a t h i g h e r l e v e l s , s u g g e s t i n g t h a t s u b s t r a t e a n g l e i s 135 of some importance f o r the e s t a b l i s h m e n t o f t h i s s p e c i e s . Claopodiam c r i s p i f p l i u m shows a h i g h degree of s o c i a b i l i t y . I t grows i n t e r m i x e d and showing p o s i t i v e a s s o c i a t i o n w i t h Pore11a cordaeana, Plaqiomnium yenustum, and Apometzgeria pubescens. S p e c i e s n o r m a l l y r e s t r i c t e d t o the f o r e s t f l o o r , such as Rhizcmnium g l a b r e s c e n s , Plaqiomnium i n s i q n e , and L e u c o l e p i s m e n z i e s i i , a re a l s o found growing w i t h i n mats of t h i s s p e c i e s . I s o t h e c i u m s t o l o n i f e r u m Two phases of t h i s v a r i a b l e t axon are r e c o g n i z e d i n t h i s s t u d y . . A t d r i e r s i t e s , p l a n t s a re 6-20 cm i n l e n g t h , and b a s a l l y a t t a c h e d ; t h e y form t h i n mats on the b o l e . The p l a n t base i s plumose and g i v e s r i s e t o l o n g h a i r - l i k e b r a n c h e s with s m a l l , w i d e l y s e p a r a t e d l e a v e s . T h i s phase i s common at UEL, and a l s o o c c u r s a t PIT. At UEL, the s p e c i e s shows h i g h e s t f r e g u e n c y on th e mid t o upper s i d e s of the b o l e a t h i g h e r e l e v a t i o n s (Appendix 3) . I n more humid, darker s i t e s , a plumose, d e n s e l y branched phase can be r e c o g n i z e d . P l a n t s a r e 6-10 cm i n l e n g t h and h i g h l y branched, and form s m a l l ; b a s a l l y - a t t a c h e d mats 2-4 cm t h i c k . T h i s phase i s common a t FUR, and i s most f r e q u e n t near t h e t r e e base on the upper s i d e o f the b o l e (Appendix 3 ) . . S o c i a b i l i t y and a s s o c i a t i o n of t h i s s p e c i e s i s s i t e -dependent. At UEL, Is o t h e c i u m s t o l o n i f e r m o f t e n grows i n t e r m i x e d w i t h Homalothecium f u l a g s c e n s , Neckera d o u g l a s i i , P o r e l l a c o r d a e a n a , and L e p r a r i a membranacea (which may e v e n t u a l l y grow over and k i l l i t ) . At FUR, t h e s p e c i e s forms s m a l l mats 136 a s s o c i a t e d w i t h P. cordaeana, Claopodium c r i s p i f o l i u m , and P o r e l l a n a y i c u l a r i s near t h e t r e e base, and d o u g l a s i i and S i f u l g e s c e n s f u r t h e r up t h e b o l e . Homalothecium f u l g e s c e n s P l a n t s o f t h i s s p e c i e s a r e u s u a l l y 10-20 cm i n l e n g t h , w i t h many bra n c h e s 2-5 cm long..The main stem i s u s u a l l y c l o s e l y a p p r e s s e d t o t h e s u b s t r a t e , w i t h branches a s c e n d i n g and f o r m i n g t u f t s . I f growing on more decomposed bark (or on a humus l a y e r ) , t h e mats a r e o f t e n l o o s e l y a t t a c h e d and may be 2-5 cm deep..Such mats a r e more c h a r a c t e r i s t i c of humid s i t e s . O b s e r v a t i o n s and s a m p l i n g suggest t h a t t h i s s p e c i e s i s most common i n humid a r e a s w i t h a more open canopy ( h i g h e r l i g h t l e v e l s ) . . Mats of Metaneckera m e n z i e s i i , Neckera d o u g l a s i i , and D i f i d r o a l s i a a b i e t i n a o f t e n grow over and smother t h i s s p e c i e s , e s p e c i a l l y i n more humid, dense f o r e s t s (BRI and FUR). T h i s s p e c i e s shows a h i g h degree of s o c i a b i l i t y d e s p i t e t h e f a c t t h a t i t o f t e n forms r e l a t i v e l y e x t e n s i v e mats. S p e c i e s such as P o r e l l a c o r d a e a n a , Homalothecium n u t t a l l i i , I s o t h e c i u m s t o l o n i f e r u m , and Neckera d o u g l a s i i a r e p o s i t i v e l y a s s o c i a t e d w i t h " i t . T h i s s p e c i e s o c c u r s most f r e q u e n t l y on t h e upper s i d e of the b o l e at a l l s i t e s (Appendix 3) , and appears t o be more common a t h i g h e r e l e v a t i o n s on t h e b o l e ( p a r t i c u l a r i l y a t BRI, PIT, and FUR). 137 D§ndroalsia a b i e t i n a T h i s i s a l a r g e , d e n d r o i d , p i n n a t e l y branched s p e c i e s , 4-12 cm l o n g (unbranched lower p o t i o n 2-3 cm long) ..Branches a r e 0.3-1 cm i n l e n g t h and numerous. P l a n t s form l a r g e (up t o 3 m i n l e n g t h ) pendent, d e n d r o i d , monotypic mats which a re commonly 6-10 cm t h i c k . The s p e c i e s grows by sen d i n g out 'runners'..Runners and r h i z o i d s permeate t h e bark f i s s u r e s t o form an e f f e c t i v e anchor f o r the col o n y . . R u n n e r s send up 'shoots' (an i n d i v i d u a l p i n n a t e p l a n t ) every 2-3 cm. _The r u n n e r s appear t o grow up the t r e e b o l e ( r a r e l y down), p a r e l l e l t o the t r u n k and bark f i s s u r e s T h u s the mat as a whole grows up the t r e e w i t h age. These r u n n e r s d i s i n t e g r a t e as the p i n n a t e shoots mature.. Because t h i s s p e c i e s forms l a r g e monotypic mats which e x c l u d e o t h e r s p e c i e s , i t s s o c i a b i l i t y i s low. I t i s p o s i t i v e l y a s s o c i a t e d w i t h d o u g l a s i i , A n t i t r i c h i a c a l i f o r n i c a , and Homalothecium f u l g e s c e n s , and appears t o compete w i t h t h e s e s p e c i e s . . T h i s s p e c i e s o c c u r s o n l y a t FUR and BRI, s i t e s which have a dense mixed c o n i f e r o u s - d e c i d u o u s canopy. The s p e c i e s appears t o p r e f e r h i g h h u m i d i t y and lower l i g h t l e v e l s . _ I t o f t e n forms e x t e n s i v e c o l o n i e s on l a r g e r t r e e s ( F i g u r e 3 4 ) , but i s ve r y r a r e l y e ncountered on s m a l l t r e e s . T h i s s p e c i e s i s common on the upper s i d e o f the b o l e a t hi g h e r e l e v a t i o n s , at both FUR and BRI (Appendix 3). At bo t h t h e s e s i t e s , t he s p e c i e s i s common above the 5 m h e i g h t on the b o l e . 1 3 8 S2fi3i2ihecium n u t t a l l i i T h i s i s a s m a l l p l a n t 2-5 cm i n l e n g t h , with numerous branches up t o 1 cm long..These form s m a l l ( g e n e r a l l y no l a r g e r than 10 x 10 cm), l o o s e , t h i n mats growing c l o s e l y a p p r e s s e d t o the s u b s t r a t e and a t t a c h e d by numerous r h i z o i d s . . M a t s t y p i c a l l y o c c ur on bare bark w i t h no humus a c c u m u l a t i o n , i n a r e a s not dominated by l a r g e mat-forming s p e c i e s such as Neckera d o u g l a s i i and Metaneckera m e n z i e s i i . . T h i s s p e c i e s shows a h i g h degree of s o c i a b i l i t y . . I t o f t e n o c c u r s on b a r r e n p a t c h e s of bark near mats of Neckera d o u g l a s i i , Metaneckera m e n z i e s i x , and Homalothecium f u l g e s c e n s * I t o f t e n o c c u r s w i t h H*_ f u l g e s c e n s and Zygodon v i r i d i s s i m - u s * T h i s s p e c i e s i s most common a t PIT and UEL, where i t o c c u r s a t the mid and upper s i d e s of t h e b o l e (Appendix 3 ) . Zygodon y i r i d i s s i m u s T h i s i s a s m a l l ( 0.5 - 1.5 cm i n le n g t h ) s p e c i e s which forms s m a l l , b a s a l l y - a t t a c h e d c u s h i o n s * S m a l l c o l o n i e s occur i n d r i e r a r e a s of the b o l e , and i n ar e a s between mats of Neckera d o u g l a s i i , Metaneckera m e n z i e s i i , and Homalothecium f u l g e s c e n s ( i t i s a l s o o f t e n a s s o c i a t e d w i t h t h e s e s p e c i e s ) . L e p r a r i a membranacea o f t e n grows over and k i l l s i t . I t i s most common a t FUE and UEL, and o c c u r s most commonly on the mid t o lower s i d e s a t h i g h e l e v a t i o n s (Appendix 3) . 139 Pla^ipmniurn venustum T h i s l a r g e (3-6 cm i n l e n g t h ) , b a s a l l y a t t a c h e d s p e c i e s forms t a l l , dense t u r f s . These t u r f s may be q u i t e e x t e n s i v e of c o n s i s t of o n l y a few p l a n t s . The s p e c i e s i s most f r e q u e n t on t h e upper s i d e of the b o l e a t lower e l e v a t i o n s a t SQU (Appendix 3 ) ; s i m i l a r o b s e r v a t i o n s wat o t h e r s i t e s . I t i s most common i n a r e a s where a humus l a y e r i s d e v e l o p e d . S o c i a b i l i t y o f t h i s s p e c i e s i s h i g h . I t i s t y p i c a l l y a s s o c i a t e d w i t h Claopodium c r i s p i f o l i u m , P o r e l l a c o r d a e a n a , and Appmetzgeria pubescens a t the t r e e base; i t may a l s o o c c u r s w i t h s p e c i e s which n o r m a l l y occupy t h e f o r e s t f l o o r , such as L e u c o I S E i s m e n z i e s i i , Plagipmnium i n s i g n e , and Rhizpmnium 3.1 a b r e sc e n s. A n t i t r i c h i a c a l i f o r n i c a T h i s i s a l a r g e (4-8 cm i n l e n g t h ) s p e c i e s which forms many s m a l l (to 1 cm) branches. P l a n t s form t h i c k (4-6 cm) , l o o s e , hummocky mats of b a s a l l y a t t a c h e d i n d i v i d u a l s . Such mats are g e n e r a l l y s m a l l , and o f t e n o c c u r s w i t h Neckera d o u g l a s i i and t o a l e s s e r e x t e n t Homalothecium f u l g e s c e n s . The s p e c i e s o c c u r s o n l y a t SQU and BRI, and i s most f r e g u e n t on t h e upper s i d e of the b o l e a t h i g h e r e l e v a t i o n s (Appendix 3 ) . I t appears t o be more common on l a r g e r t r e e s . The s p e c i e s a l s o o c c u r s on the l o w e r branches of t r e e s i n more open a r e a s . 140 Homalia t r i c h o m a n o i d e s P l a n t s of t h i s s p e c i e s a r e 3 - 5 cm i n l e n g t h and s i m p l y branched, t h e branches t o 1 cm i n l e n g t h . I t forms l o o s e , semi-d e n d r o i d mats of i n t e r w o v e n p l a n t s which are f a i r l y l o o s e l y a t t a c h e d t o t h e substratum (by r h i z o i d s a t the p l a n t b a s e ) . T h i s s p e c i e s o c c u r s o n l y a t SQU, and i s r e s t r i c t e d t o the s p l a y e d - o u t t r e e base (Appendix 3 ) . I t g e n e r a l l y forms monotypic mats, but n o n e t h e l e s s shows h i g h s o c i a b i l i t y . I t i s o f t e n a s s o c i a t e d w i t h Plagiomnium yenusturn, P o r e l l a c ordaeana, and Clappodium c r i s p i f o l i u m . T h i s s p e c i e s appears t o occupy t h e same area of t h e b o l e as does C._ c r i s p i f o l i u m a t the o t h e r s i t e s ; i t may be p r e f e r r e d a t SQU because o f p e r i o d i c f l o o d i n g or h i g h e r s n o w f a l l . H e p a t i c s P o r e l l a cordaeana T h i s s p e c i e s i s 3-6 cm i n l e n g t h , and forms s m a l l , l o o s e mats; o c c a s i o n a l l y , l a r g e r , dense mats a r e formed. I t may a l s o o c c u r as a few s t r a n d s growing c l o s e l y a ppressed t o t h e bark s u b s t r a t e . T h i s s p e c i e s shows a h i g h degree of s o c i a b i l i t y . I t shows hi g h p o s i t i v e a s s o c i a t i o n w i t h Neckera d o u q l a s i i , I s o t h e c i u m s t o l o n i f e r u m , P o r e l l a n a y i c u l a r i s , A n t i t r i c h i a c a l i f g r n i c a , and Clappodium c r i s p i f o l i u m . T h i s s p e c i e s shows b e t w e e n - s i t e v a r i a b i l i t y i n i t s h a b i t a t 141 p r e f e r e n c e s (Appendix 3 ) . . A t SQU and FUR, the s p e c i e s p r e f e r s t h e upper s i d e o f t h e b o l e near the t r e e base. At P I T , t h e s p e c i e s shows p r e f e r e n c e f o r t h e upper s i d e of the b o l e a t h i g h e r e l e v a t i o n s . . At UEL, i t appears t o grow on a l l p a r t s of the b o l e . The s p e c i e s i s not as common a t BRI, but te n d s t o occur near t h e t r e e base a t t h i s s i t e . P o r e l l a n a y i c u l a r i s T h i s s p e c i e s i s g e n e r a l l y more r o b u s t than P o r e l l a c o r d a eana; i n d i v i d u a l p l a n t s a re 4-10 cm i n l e n g t h . I t forms l o o s e t o clumped mats which a r e g e n e r a l l y s m a l l . S o c i a b i l i t y of the s p e c i e s i s h i g h . I t shows s t r o n g p o s i t i v e a s s o c i a t i o n w i t h cordaeana and Clagpodium c r i s p i f o l i u m a t the t r e e base. Higher up t h e b o l e , i t i s o f t e n p o s i t i v e l y a s s o c i a t e d w i t h i g m a l o t h e c i u m f u l g e s c e n s , Neckera d o u g l a s i i , and Metaneckera m e n z i e s i i i I t i s most common a t FUR and PIT, where i t o c c a s i o n a l l y forms mats up t o 15 cm i n l e n g t h . At both of t h e s e s i t e s , t h e s p e c i e s shows h i g h e s t f r e g e n c y on the upper s i d e o f t h e b o l e ; no h e i g h t p r e f e r e n c e i s i n d i c a t e d , however (Appendix 3) . Apometzqeria pubescens T h i s i s a s m a l l , t h a l l o s e h e p a t i c 1-2 cm i n l e n g t h , w i t h branches t o 0.5 cm l o n g . I t forms s m a l l , t h a l l o i d mats (to 5 cm a c r o s s , r a r e l y l a r g e r ) a t t a c h e d t o t h e s u b s t r a t e or growing amoungst, and o v e r , o t h e r e p i p h y t i c s p e c i e s ( h y p e r e p i p h y t e c f . Barkman 1958). O c c a s i o n a l l y o n l y a few s t r a n d s of the s p e c i e s 1 4 2 are seen growing i n amonngst a l a r g e mat of another s p e c i e s . S o c i a b i l i t y of t h i s s p e c i e s i s high. I t occurs most commonly at the t r e e base {Appendix 3) and shows high p o s i t i v e a s s o c i a t i o n with Clapppdium c r i s p i f o l i u m , P o r e l l a cordaeana, and o c c a s i o n a l l y Homalothecium f u l j j e s c e n s . I t o c c a s i o n a l l y occurs at higher e l e v a t i o n s on the b o l e , i n areas where t h i c k bryophyte mats are not developed. F r u l l a n i a t a m a r i s e i ssp. n i s g u a l l e n s i s T h i s s p e c i e s i s s m a l l ; i n d i v i d u a l p l a n t s are no more than 1 cm i n l e n g t h . These g e n e r a l l y form s m a l l compact mats 2 - 6 cm across which grow c l o s e l y appressed to the bark. The s p e c i e s tends to occur on r e l a t i v e l y smooth, bare bark on the upper s u r f a c e of the bole i n areas where mat-forming s p e c i e s do not occur. The s p e c i e s i s more common on s m a l l t r e e s , and at higher e l e v a t i o n s on t r e e s at dry s i t e s (UEL, see Appendix 3 ) . . I t i s r a r e or absent on l a r g e t r e e s i n humid s i t e s . . S o c i a b i l i t y of t h i s s p e c i e s i s g u i t e high. I t i s p o s i t i v e l y a s s o c i a t e d with Isothecium s t o l o n i f e r u m (at UEL), Homalothecium n u t t a l l i i , Lophocolea c u s p i d a t a , and Orthotriehum l y e l l i i . 143 L i c h e n s L e p r a r i a membranacea T h i s l e p r o s e l i c h e n c o n s i s t s of l o o s e l y a r r a n g e d a l g a l and h y p h a l c e l l s w i t h o u t a d e f i n e d t h a l l u s . I t forms t i n y c r u s t o s e c o l o n i e s (1-5 mm) on bare bark, a l t h o u g h a t d r i e r s i t e s (UEL, PIT) t h e s p e c i e s may form e x t e n s i v e p a t c h e s over the bark, and b r y o p h y t e s . . Such patches may be up t o 30 cm i n l e n g t h . Because t h i s s p e c i e s forms t i n y c o l o n i e s more or l e s s e v e n l y d i s t r i b u t e d over t h e ba r k , i t shows h i g h f r e g u e n c y when sampled, even though i t s c o v e r and biomass i s very low (see P i k e e t a l . _ 1978). T h i s s p e c i e s shows a d e f i n i t e p r e f e r e n c e f o r the lower s i d e of the i n c l i n e d b o l e (Appendix 3 ) . . A t SQU, FUR, and PIT, the s p e c i e s appears t o be more common a t h i g h e r e l e v a t i o n s , w h i l e at BRI i t p r e f e r s lower e l e v a t i o n s . At UEL (where t h e s p e c i e s shows the h i g h e s t f r e g u e n c y ) , i t o c c u r s w i t h a p p r o x i m a t e l y e g u a l f r e g u e n c y a t a l l h e i g h t s . . A t t h i s s i t e , i t i s found growing on I s o t h e c i u m s t o l o n i f e r u m , Metaneckera m e n z i e s i i , Claopodium c r i s p i f o l i u m , and Zycjodon v i r i d i s s i m u s . T h i s s p e c i e s i s o f t e n p o s i t i v e l y a s s o c i a t e d w i t h Metaneckera m e n z i e s i i and G r a p h i s s c r i p t a . Barkman (1958) has noted t h a t i n Europe t h i s s p e c i e s i s most f r e g u e n t on d r y , rough, dead ba r k , and i s a b l e t o l i v e i n areas where p r e c i p i t a t i o n i s r a r e l y a v a i l a b l e . He a l s o s t a t e s 144 t h a t the s p e c i e s may grow over and k i l l b r y o p h y t e s which occur i n h a b i t a t s where water a v a i l a b i l i t y and l i g h t l e v e l s a r e low. S i m i l a r o b s e r v a t i o n s have been made i n the p r e s e n t study. G r a p h i s s c r i p t a T h i s i s a s m a l l , c r u s t o s e s p e c i e s which o c c u r s on d r y , bare bark, where i t forms s m a l l c r u s t s on t h e bark r i d g e s . I t i s most f r e g u e n t a t BRI, where i t o c c u r s on the lower s i d e of the b o l e ; no h e i g h t p r e f e r e n c e i s i n d i c a t e d (Appendix 3 ) . . S i m i l a r o b s e r v a t i o n s were made a t t h e o t h e r s i t e s i n which t h i s s p e c i e s o c c u r r e d . I t i s a s s o c i a t e d o n l y w i t h L e p r a r i a membranacea; s o c i a b i l i t y i s low. . V a s c u l a r P l a n t s E°ilEodium g l y c y r r h i z a T h i s f e r n i s the o n l y v a s c u l a r s p e c i e s found growing on Acer macrophyllum. Leaves are 4-30 cm i n l e n g t h (depending upon m i c r o h a b i t a t and season) on a s t i p e 4-20 cm long._A c r e e p i n g rhizome f i r m l y a t t a c h e d t o the s u b s t r a t e by numerous f i n e r o o t s g i v e s r i s e t o f r o n d s e v e r y 2-10 cm. The e x t e n s i v e r o o t mat grows below . t h e br y o p h y t e mat, and accumulates dead and decomposing o r g a n i c matter (bark and e p i p h y t i c v e g e t a t i o n ) , which o f t e n forms a t h i c k (up t o 6 cm deep) 'humus l a y e r . L a r g e f r o n d s o f t h i s s p e c i e s d e v e l o p i n t h e f a l l and grow t h r o u g h o u t the w i n t e r and s p r i n g , d y i n g back d u r i n g the warm. 145 dry summer. Fronds produced d u r i n g t h e s p r i n g and e a r l y summer ar e n o r m a l l y much s m a l l e r , and may w i t h e r and d i e d u r i n g dry p e r i o d s . . S i n c e s a m p l i n g was undertaken d u r i n g t h e dry summer of 1979, most of the f r o n d s o f t h i s s p e c i e s had d i e d and f a l l e n from the b o l e , so t h a t t h e s p e c i e s was r a r e l y e n c o u n t e r e d i n g u a d r a t s . D u r i n g the w i n t e r , f r o n d s form l a r g e , pendulous mats on the b o l e . S o c i a b i l i t y o f t h i s s p e c i e s i s d i f f i c u l t t o a s s e s s because of i t s growth-form, s i z e , and h a b i t . I t u s u a l l y o c c u r s w i t h mat-f o r m i n g s p e c i e s such as Neckera d o u ^ l a s i i , Homalothecium f U l a e s c e f i s , and Metaneckera m e n z i e s i i ; a t UEL, i t commonly o c c u r s w i t h I s o t h e c i u m s t o l o n i f e r u m . 1 4 6 CHAPTER 9 - CHARACTERIZATION OF EPIPHYTIC COMMUNITIES ON ACER MACROPHYLLUM In t h i s c h a p t e r , e p i p h y t i c v e g e t a t i o n a l u n i t s on Acer macrophyllum a r e c h a r a c t e r i z e d and d e l i n e a t e d . The d e s c r i p t i o n of such u n i t s has some advantages i n t h a t i t a l l o w s f o r the summarizaton and e f f e c t i v e p r e s e n t a t i o n of a complex body o f d a t a . F u r t h e r m o r e , such a s t r a t e g y i s of use t o o t h e r s , s i n c e i t i d e n t i f i e s v e g e t a t i o n a l u n i t s which may be r e c o g n i z e d i n the f i e l d . A c l a s s i f i c a t o r y approach t o t h e st u d y of the e p i p h y t i c v e g e t a t i o n i s s t r e s s e d . C l u s t e r a n a l y s i s has been used t o d e f i n e v e g e t a t i o n a l g r o u p i n g s and t o examine the i n t e r e l a t i o n s h i p s between t h e s e g r o u p i n g s . . B a s e d upon t h e r e s u l t s of the c l u s t e r a n a l y s e s , and f i e l d o b s e r v a t i o n s , e p i p h y t i c communities on Acer macrophyllum are d e f i n e d and c h a r a c t e r i z e d . C l u s t e r A n a l y s i s The v e g e t a t i o n c f each o f the 5 s i t e s has been s u b j e c t e d t o c l u s t e r a n a l y s i s u s i n g the method o u t l i n e d i n Chapter 5 (Ward's method, u s i n g the E u c l i d e a n d i s t a n c e measure). The method d i s t i n g u i s h e s g r o u p i n g s or c l u s t e r s c o n s i s t i n g o f v e g e t a t i o n a l l y s i m i l a r g u a d r a t s . The a n a l y s e s a re meant t o be e x p l o r a t o r y ; h ypotheses c o n c e r n i n g t h e n a t u r e o f t h e v e g e t a t i o n a re t e s t e d , and t h e r e s u l t s g i v e some i n d i c a t i o n of s t r u c t u r e and i n t e r r e l a t i o n s h i p s i n h e r e n t i n the data s e t . 147 For each o f t h e 5 s i t e a n a l y s e s , a l l 360 quad r a t s were used, as were a l l t h e s p e c i e s . However, q u a d r a t s l a c k i n g any e p i p h y t i c v e g e t a t i o n were e x c l u d e d s i n c e t h e y are not c l a s s i f i a b l e . In order t o f a c i l i t a t e i n t e r p r e t a t i o n , the r e s u l t a n t c l u s t e r s were 'cut o f f at an a r b i t r a r y l e v e l . . An attempt was made t o d e f i n e t h i s l e v e l such t h a t the c l u s t e r g r o u p i n g s show r e l a t i v e l y h i g h w i t h i n - g r o u p homogeneity and between-group h e t e r o g e n e i t y ; the c r i t e r i a used are o u t l i n e d i n O s t e r l i n e t a l . . (1 978). S p a t i a l r e l a t i o n s h i p s on the t r e e b o l e of the g r o u p i n g s d e f i n e d by the c l u s t e r a n a l y s e s were a l s o examined. Mean and s t a n d a r d d e v i a t i o n v a l u e s of angl e ( i n degrees) and h e i g h t ( i n meters) were computed f o r g u a d r a t s w i t h i n each c l u s t e r . The r e s u l t s were p l o t t e d on a t w o - d i m e n s i o n a l ' d i r e c t o r d i n a t i o n ' (guadrat a n g l e v s . h e i g h t ) . T h i s d i r e c t o r d i n a t i o n r e p r e s e n t s an average (or ' s y n t h e t i c ' ) t r e e t r u n k (to an e l e v a t i o n of 5 meters)..The computed h e i g h t mean may not r e p r e s e n t t h e t r u e p r e f e r r e d l e v e l f o r a p a r t i c u l a r g r o u p i n g s i n c e s a m p l i n g was c o n f i n e d t o the f i r s t 5 meters of the t r u n k . N o n e t h e l e s s , the r e s u l t s do g i v e some i n s i g h t i n t o the s p a t i a l d i s t r i b u t i o n s and p r e f e r e n c e s of t h e groups. The c l u s t e r a n a l y s e s and d i r e c t o r d i n a t i o n r e s u l t s a re d i s c u s s e d below f o r each of the 5 s i t e s . .Each c l u s t e r group has been c h a r a c t e r i z e d by the s p e c i e s o c c u r r i n g w i t h h i g h e s t f r e g u e n c y w i t h i n g u a d r a t s b e l o n g i n g t o t h e group; o t h e r s p e c i e s o c c u r r i n g w i t h i n t h e qu a d r a t s are a l s o l i s t e d . . T h e l o c a t i o n o f each c l u s t e r g r o u p i n g on the t r e e (from t h e d i r e c t o r d i n a t i o n r e s u l t s ) are a l s o t a b u l a t e d . . F o r t h e purpose o f s u m m a r i z a t i o n , 3 148 l e v e l s of p r e f e r r e d h e i g h t ( e l e v a t i o n ) groups a r e r e c o g n i z e d : b a s a l (0-1 ra) , mid (1-3 m) , and h i g h e r (3-5 m) e l e v a t i o n s . I t s h o u l d be noted t h a t c l u s t e r g r o u p i n g s c o n s i s t i n g of fewer t h a t 10 g u a d r a t s , and those i n which t o t a l s p e c i e s f r e g u e n c y i s low, were not p l o t t e d on the d i r e c t o r d i n a t i o n s . SQU The r e s u l t a n t c l u s t e r a n a l y s i s f o r t h i s s i t e i s shown i n F i g u r e 35; t h e c o r r e s p o n d i n g d i r e c t o r d i n a t i o n i s shown i n F i g u r e 36. A t o t a l o f 9 c l u s t e r groups have been r e c o g n i z e d , and are d e s c r i b e d below. I . .Hornalia t r i c h c m a n o i d e s Other s p e c i e s : Plaqipmnium yenustum, Claopodium c r i s p i f o l i u m , £2£ella cordaeana, Homalothecium f u l q e s c e n s , R h y t i d i a d e l p h u s i£ig.ue t r us L o c a t i o n : r e s t r i c t e d t o the s p l a y e d - o u t t r e e base. I I . Quadrats w i t h low s p e c i e s f r e g u e n c i e s . S p e c i e s : Metaneckera m e n z i e s i i , L e p r a r i a membranacea I I I * Homalothecium f u l g e s c e n s Other s p e c i e s : Neckera d o u g l a s i i , P o r e l l a cordaeana, M*. m e n z i e s i i L o c a t i o n : upper s i d e of t r u n k , at mid t o h i g h e r e l e v a t i o n s . IV. Homalothecium f u l g e s c e n s - Metaneckera m e n z i e s i i Other s p e c i e s : N._ d o u g l a s i i , P.. cordaeana I (49) (59) i i v v v i v i vm (33) (23) (34) (17) (34) (39) IX (59) t-20.17 M8.11 -10.59 ^ -9.77 -5.57 •4.64 2.51 H.97 O e— x CO Ld u < I— (/) a Figure 35. Cluster analysis of quadrats from SQU. Values i n brackets represent the number of quadrat found i n each of the recognized groupings. Distance i s euclidean. 150 86 90 94 98 ANGLE (DEGREES) 102 Figure 36. Two-dimensional direct ordination of quadrat groupings at SQU (see Figure 35). Means of angle and height were computed for quadrats belonging to each grouping, and groupings thus positioned; standard deviations are indicated by l i n e s . 151 L o c a t i o n : mid t o upper s i d e s of t r u n k , at lower t o mid e l e v a t i o n s . V. Neckera d o u g l a s i i - Homalothecium f u l g e s c e n s Other s p e c i e s : P...venustum, ^ S t i t r i c h i a c a l i f o r n i c a , Homalothecium n u t t a l l i i , c o r d aeana, P o r e l l a n a v i c u l a r i s L o c a t i o n : upper s i d e of the t r u n k , at mid t o h i g h e r e l e v a t i o n s . . VI. A n t i t r i c h i a c a l i f o r n i c a Other s p e c i e s : N. . d o u g l a s i i , Hj_ f u l ^ e s c g n s L o c a t i o n : upper s i d e of the t r u n k , at h i g h e r e l e v a t i o n s . V I I . . L e p r a r i a membranacea Other s p e c i e s : G r a p h i s s c r i p t a , Zygpdon y i r i d i s s i m u s , M •.. m e n z i e s i i L o c a t i o n : lower s i d e of the t r u n k , a t mid t o h i g h e r e l e v a t i o n s . V I I I . Metaneckera m e n z i e s i i Other s p e c i e s : L. . membranacea, N^. d o u g l a s i i , H.. f u l g e s c e n s L o c a t i o n : l o w e r t o mid s i d e s o f the t r u n k , a l l e l e v a t i o n s above the base. I X . Neckera d o u g l a s i i Other s p e c i e s : P.. cordaeana, Mi_ m e n z i e s i i , f u l g e s c e n s L o c a t i o n : upper s i d e of t h e t r u n k , a t h i g h e r e l e v a t i o n s . F i g u r e 35 shows t h a t groups I and IX appear t o be the most d i s t i n c t * Group I (the b a s a l r e g i o n dominated by Homalia 1 5 2 ichomanoides) can a l s o be i d e n t i f i e d i n t h e f i e l d as a d i s t i n c t e c o l o g i c a l e n t i t y . Group I X , which i n c l u d e s g u a d r a t s sampled on l a r g e hummocks o f Neckera d o u g l a s i i , i s a l s o d i s t i n c t . T h i s group does not c l u s t e r w i t h group V, which a l s o c o n t a i n s h i g h v a l u e s of N._ d o u g l a s i i . T h i s makes sense, s i n c e a r e a s i n which l a r g e hummocky mats of N._ d o u g l a s i i o ccur (group IX) a r e d i s t i n g u i s h e d from a r e a s i n which t h i s s p e c i e s tends t o occur i n s m a l l e r patches i n t e r m i x e d w i t h o t h e r s p e c i e s (group V) . At the next l e v e l , groups VII and V I I I form a d i s t i n c t c l u s t e r . . The s p e c i e s c o r r e s p o n d i n g t o t h e s e groups, L e p r a r i a membranacea and Metaneckera m e n z i e s i i r e s p e c t i v e l y , both occur on the l o w e r t o mid s i d e s of t h e b o l e , and show a high, degree of p o s i t i v e a s s o c i a t i o n . Groups I I - V I form the ne x t c l u s t e r , and g e n e r a l l y c o n s i s t of s p e c i e s r e s t r i c t e d t o the upper s i d e o f t h e b o l e . The n a t u r e of t h e i n t e r r e l a t i o n s h i p s between the c l u s t e r s i n g e n e r a l r e f l e c t m i c r o h a b i t a t p r e f e r e n c e s of the e p i p h y t e s on the t r e e , a l t h o u g h t h e r e a re some e x c e p t i o n s ( n o t a b l y group I X ) . The r e s u l t s of the d i r e c t o r d i n a t i o n ( F i g u r e 36) suggest t h a t , w h i l e each g r o u p i n g shows a d i s t i n c t a r ea of p r e f e r e n c e on the b o l e , t h e r e i s a l s o much o v e r l a p . S p a t i a l l y , groups I and V I I a r e t h e most d i s t i n c t . . T h e o t h e r groups show a g r e a t d e a l o f o v e r l a p ( a l t h o u g h group IV appears t o p r e f e r l o w e r e l e v a t i o n s and group V I I I the lower s i d e o f t h e t r u n k ) . FUB The r e s u l t a n t c l u s t e r a n a l y s i s f o r t h i s s i t e i s shown i n 153 F i g u r e 37; the c o r r e s p o n d i n g d i r e c t o r d i n a t i o n i s shown i n F i g u r e 38. I n t o t a l , 11 c l u s t e r groups were r e c o g n i z e d , and are d e s c r i b e d below. !• I s o t h e c i u m s t o l o n i f e r u m Other s p e c i e s : Clapppdium c r i s p i f o l i u m , P o r e l l a c o rdaeana, Homalothecium f u l g e s c e n s L o c a t i o n : near the t r e e base, on t h e upper s i d e of the b o l e . I I . Claopodium c r i s p i f o l i u m - P o r e l l a cordaeana Other s p e c i e s : I., s t o l o n i f erum, Neckera d o u g l a s i i ( r a r e l y ) L o c a t i o n : s p l a y e d - o u t t r e e bases. I I I . Clappodium c r i s p i f o l i u m Other s p e c i e s : Appmetzgeria pubeseens, P o r e l l a n a y i c u l a r i s , N. . d o u g l a s i i ( o c c a s i o n a l ) , fU f u l g e s c e n s (rare) L o c a t i o n : near the t r e e base, upper s i d e of b o l e . IV. Metaneckera m e n z i e s i i - L e p r a r i a membranacea Other s p e c i e s : N._ d o u g l a s i i , P.. cordaeana, Homalothecium n u t t a l l i i , P.. n a y i c u l a r i s , F r u l l a n i a t a m a r i s c i s s p . n i s g u a l l e n s i s L o c a t i o n : mid t o l o w e r s i d e s of t r u n k , a t mid e l e v a t i o n s . V. Metaneckera m e n z i e s i i Other s p e c i e s : L._ membranacea, H._ f u l g e s c e n s ( o c c a s i o n a l ) L o c a t i o n : mid s i d e of the b o l e , at mid to h i g h e r e l e v a t i o n s . n (20) BE (48) IV (42) V (47) vr w v n i x x x i (34) (18) (25) (15) (34) (30) -24.94 -14.17 -13.23 -8.51 8.05 -5.24 -3.40 2.86 h2.59 2.28 ID CO UJ u z < h-co a re 37. Cluster analysis of quadrats from FUR. Values i n brackets represent the number of quadrats found i n each of the recognized groupings. Distance i s euclidean. 155 _ i I i u J L -rx— 4H -VJT- -x--txi-cr J u LLI 2 -V— -rv--vnr-n: O 2-Ld •n-H -1-1 1 1 1 1 1 1 1 1 1 T" 82 86 90 94 98 102 ANGLE (DEGREES) Figure 38. Two-dimensional d i r e c t ordination of quadrat groupings at FUR (see Figure 37). Means of angle and height were computed f o r quadrats belonging to each grouping, and groupings thus positioned; standard deviations are indicated by l i n e s . 1 5 6 V I . Quadrats w i t h low s p e c i e s f r e g u e n c y S p e c i e s : L. membranacea, H._. n u t t a l l i i , N. . d o u g l a s i i , Zyg.od.gn y i r i d i s s i m u s V I I . Homalothecium f u l g e s c e n s Other s p e c i e s : L._ membranacea, H.. n u t t a l l i i , Ni_ d o u g l a s i i , "kz. y i r i d i s s i m u s L o c a t i o n : upper s i d e of t h e t r u n k , a t h i g h e r e l e v a t i o n s . V I I I . L e p r a r i a membranacea Other s p e c i e s : M. m e n z i e s i i , F. t a m a r i s c i ssp. n i s g u a l l e n s i s L o c a t i o n : l ower s i d e of the t r u n k , a t a l l e l e v a t i o n s above the t r e e base. I X . Zygodon y i r i d i s s i m u s Other s p e c i e s : L._ membranacea, M.. m e n z i e s i i L o c a t i o n : l ower s i d e of the t r u n k , at h i g h e r e l e v a t i o n s . ; X. .Neckera d o u g l a s i i Other s p e c i e s : M . . m e n z i e s i i , H. f u l g e s c e n s , I A s t o l o n i f e r u m , S•. n u t t a l l i i L o c a t i o n : upper s i d e of the t r u n k , at h i g h e r e l e v a t i o n s . X I . D e n d r o a l s i a a b i e t i n a Other s p e c i e s : N. d o u g l a s i i , M;_ m e n z i e s i i L o c a t i o n : upper s i d e of the t r u n k , a t mid t o h i g h e r e l e v a t i o n s . F i g u r e 37 s u g g e s t s t h a t 3 major c l u s t e r s can be r e c o g n i z e d . 157 The f i r s t c o n s i s t s of groups I , I I , and I I I , which are g e n e r a l l y r e s t r i c t e d t o r e g i o n s a t or near the t r e e base, and so form a d i s t i n c t e c o l o g i c a l g r o u p i n g . The second major c l u s t e r c o n s i s t s of groups IV and V, which are dominated by Metaneckera m e n z i e s i i and t o a l e s s e r e x t e n t L e p r a r i a membranacea, and form a d i s t i n c t e c o l o g i c a l g r o u p i n g on the mid t o lower s i d e s of the t r u n k . W i t h i n t h e t h i r d major c l u s t e r , groups X and XI are t h e most d i s t i n c t . These a r e dominated by Neckera d o u g l a s i i and d e n d r o a l s i a a b i e t i n a r e s p e c t i v e l y , both o f which form l a r g e , hummocky, o f t e n monotypic mats on t h e t r e e bole..Groups V I I I and IX c l u s t e r t o g e t h e r ; they both o c c u r on the lower s i d e of t r e e t r u n k s . . The r e l a t i o n s h i p s between groups V I , V I I , and IX a t f i r s t appears t o be somewhat m i s l e a d i n g . However, o b s e r v a t i o n s i n t h e f i e l d c o n f i r m t h a t membranacea i s o f t e n found growing over mats of Homalothecium f u l g e s c e n s so t h a t the 2 s p e c i e s may c o - o c c u r i n g u a d r a t s . T h i s may e x p l a i n the r e l a t i o n s h i p between groups V I I I and V I I i n t h e r e s u l t s . The c l u s t e r a n a l y s i s s u g g e s t s t h a t group i n t e r r e l a t i o n s h i p s c o r r e s p o n d g u i t e w e l l t o m i c r o h a b i t a t d i f f e r e n t i a t i o n on t h e t r e e b o l e ; growth form may a l s o be i m p o r t a n t i n d i s t i n g u i s h i n g g r o u p i n g s . F i g u r e 38 s u g g e s t s t h a t groups I , I I , and I I I form a s p a t i a l l y d i s t i n c t group a t the t r e e base. Group IX (dominated D Y Zygodon y i r i d i s s i m u s ) i s a l s o s p a t i a l l y d i s t i n c t , o c c u r r i n g at h i g h e l e v a t i o n s on the lower s i d e of t h e b o l e . The o t h e r groups show v a r y i n g degrees of o v e r l a p . Group V I I I ( L e p r a r i a membranacea) i s r e l a t i v e l y d i s t i n c t ; however, i t o v e r l a p s t o some e x t e n t w i t h group IV (L. membranacea and Metaneckera 158 m e n z i e s i x ) which i n t u r n o v e r l a p s w i t h group V (M m e n z i e s i i ) . A s p e c i e s seguence i s e v i d e n t here. Groups V I I , X, and X I , a l l o f which o c c u r a t h i g h e r e l e v a t i o n s on t h e upper s i d e of the b o l e , show a h i g h degree of s p a t i a l o v e r l a p . UEL F i g u r e 39 shows the r e s u l t a n t c l u s t e r a n a l y s i s f o r t h i s s i t e ; F i g u r e 40 shows the c o r r e s p o n d i n g d i r e c t o r d i n a t i o n . A t o t a l o f 12 c l u s t e r groups have been r e c o g n i z e d , and are d e s c r i b e d below. 1• L e p r a r i a membranacea Other s p e c i e s : I s o t h e c i u m s t o l o n i f e r u m , F r u l l a n i a t a m a r i s c i s s p . S.i§_2Jiallensis, Homalothecium f u l g e s c e n s 5 L o c a t i o n : l o w e r s i d e of the t r u n k , at a l l e l e v a t i o n s above the base* I I . . L e p a r i a membranacea - Zygodon y i r i d i s s i m u s Other s p e c i e s : F._ t a m a r i s c i s s p . n i s g u a l i e n s i s , Homalothecium n u t t a l l i i L o c a t i o n : l o w e r s i d e of t r u n k , at h i g h e r e l e v a t i o n s . I I I . L e p r a r i a membranacea - Coniocybe f u r f u r a c e a L o c a t i o n : t o o few g u a d r a t s i n group. IV. Metaneckera m e n z i e s i i Other s p e c i e s : L. -membranacea, H.. f u l g e s c e n s ( o c c a s i o n a l ) , H. , n u t t a l l i i (rare) I I L / V VE VE (14) (9) (33) (14) (17) (27) vnr (62) I X (22) x xr x n (69) (16) (12) 29.74 -22.55 -9.41 -7.38 6.06 -4.34 -3.20 -2.86 -2.51 2.28 1.94 CO LU CJ z CO Q ure 39. Cluster analysis of quadrats from UEL. Values in brackets represent the number of quadrats found in each of the recognized groupings. Distance is euclidean. 160 90 94 ANGLE (DEGREES) 102 Figure AO. Two-dimensional d i r e c t ordination of quadrat groupings at UEL (see Figure 39). Means of angle and height were computed f o r quadrats belonging to each grouping, and groupings thus positioned; standard deviations are indicated by l i n e s . 161 L o c a t i o n : l o w e r t o mid e l e v a t i o n s , j u s t above the t r e e base. V. Neckera d o u g l a s i i Other s p e c i e s : I._ s t o l o n i f erum L o c a t i o n : mid s i d e s of t r u n k , a l l e l e v a t i o n s above the t r e e base. V I . Homalothecium f u l g e s c e n s Other s p e c i e s : P o r e l l a c ordaeana, L.. membranacea L o c a t i o n : upper s i d e of t h e b o l e , lower e l e v a t i o n s above t r e e base. V I I . Homalothecium n u t t a l l i i Other s p e c i e s : H._. f u lg_e sc ens , Z. y i r i d i s s i m u s , L. membranacea (occas i o n a l ) L o c a t i o n : upper s i d e of the t r u n k , a t h i g h e r e l e v a t i o n s . V I I I . I s o t h e c i u m s t o l o n i f e r u m Other s p e c i e s : L.. membranacea, H.. f u l g e s c e n s , N-_ d o u g l a s i i ( p c a s s i o n a l ) L o c a t i o n : upper s i d e of t r u n k , a t mid t o h i g h e r e l e v a t i o n s . . IX. - I s o t h e c i u m s t o l o n i f e r u m - L e p r a r i a membranacea L o c a t i o n : upper s i d e of t r u n k , at h i g h e r e l e v a t i o n s . X. .Claoppdium c r i s p i f o l i u m Other s p e c i e s : L s t o l o n i f e r u m , H.. f u l g e s c e n s L o c a t i o n : upper s i d e of the t r u n k , near t h e t r e e base.. 162 X I . Claopodium c r i s p i f o l i u m - Plac[ipmnium y e n u s t urn Other s p e c i e s : Rhizomnium q l a b r e s c e n s , L e u c o l e p i s m e n z i e s i i , Plagipmnium i n g i g n e L o c a t i o n : s p l a y e d - o u t t r e e base. X I I . Claopodium c r i s p i f o l i u m - L e p r a r i a membranacea L o c a t i o n : near the t r e e base, mid t o upper s i d e s of the b o l e . Four major c l u s t e r s a r e suggested from F i g u r e 39. Groups I , I I , and I I I a l l c l u s t e r t o g e t h e r ; each o f t h e s e show a h i g h f r e g u e n c y o f L e p r a r i a membranacea ( o f t e n i n c o m b i n a t i o n w i t h o t h e r s p e c i e s ) , and occur on the l o w e r s i d e of the t r u n k * Group IV c l u s t e r s w i t h t h e s e groups at a h i g h e r l e v e l ; i t i s dominated by Metaneckera m e n z i e s i i , which a l s o o c c u r s on t h e lower s i d e o f t r u n k s . Groups V, V I , and VII form a r e l a t i v e l y t i g h t c l u s t e r ; t h e s e groups a r e found on t h e upper s i d e of the t r u n k a t midd l e to h i g h e r e l e v a t i o n s , and the s p e c i e s t h e y c o n t a i n are g e n e r a l l y p o s i t i v e l y a s s o c i a t e d . Groups V I I I and IX form a t h i r d major c l u s t e r ; both of these groups have a h i g h f r e g u e n c y of I s o t h e c i u m s t o l o n i f e r u m . A f o u r t h c l u s t e r c o n s i s t s of groups X, X I , and X I I , a l l of which have h i g h f r e g u e n c y v a l u e s of Claopodium c r i s p i f o l i u m ( o f t e n i n c o m b i n a t i o n w i t h o t h e r s p e c i e s ) ; t h e s e groups g e n e r a l l y o c c u r on t h e s p l a y e d - o u t t r e e base. Thus t h e r e s u l t s would appear t o c o r r e s p o n d t o the m i c r o h a b i t a t d i f f e r e n c e s found on the t r e e t r u n k . . F i g u r e 40 s u g g e s t s t h a t t h e s e groups show v a r y i n g degrees of s p a t i a l o v e r l a p . . G r o u p XI shows d e f i n i t e p r e f e r e n c e f o r t h e t r e e base. Groups V I , X, and X I I , which show o v e r l a p w i t h one 163 a n o t h e r , form a s p a t i a l l y d i s t i n c t group near the t r e e base. Group IV i s a f a i r l y d i s t i n c t group which o c c u r s on the lower s i d e near t h e t r e e base. The o t h e r groups show v a r y i n g degrees of o v e r l a p w i t h one another. PIT The r e s u l t a n t c l u s t e r a n a l y s i s f o r t h i s s i t e i s shown i n F i g u r e 41; the c o r r e s p o n d i n g d i r e c t o r d i n a t i o n i s shown i n F i g u r e 42. A t o t a l of 12 c l u s t e r groups have been r e c o g n i z e d , and a r e d e s c r i b e d below. I . Claopodium c r i s p i f o l i u m Other s p e c i e s : Plagiomnium yenustum, P o r e l l a cordaeana, Apometzgeria J^ubescens r Homalothecium f u l g e s c e n s ( o c c a s i o n a l ) , Neckera d o u g l a s i i (rare) L o c a t i o n : s p l a y e d - o u t t r e e base. I I . Quadrats w i t h low s p e c i e s f r e g u e n c y S p e c i e s : Metaneckera m e n z i e s i i , L e p r a r i a membranacea, H. f u l c j e s c e n s I I I . Zygodon y i r i d i s s i m u s Other s p e c i e s : Homalothecium n u t t a l l i i , L._ membranacea L o c a t i o n : too few g u a d r a t s i n t h e group. IV. Apometzgeria pubescens Other s p e c i e s : H.. f u l g e s c e n s , c r i s p i f o l i u m , N._ d o u g l a s i i L o c a t i o n : upper s i d e of t h e t r u n k , near the t r e e base. I IE IT IV V VE V E VIE I X X (61) (29) (8) (10) (7) (33) (18) (27) (33) (59) X L (34) XI (41) -26.06 -18.19 -11.95 -11.40 -4 .69 CO LU -3.91 U z -2 .85 -2.45 CO Q -1.80 Figure 41. Cluster analysis of quadrats from PIT. Values i n brackets represent the number of quadrats found i n each of the recognized groupings. Distance i s euclidean. 165 J I I I i J I i -j \LX-- v i i — -A1-CO o: 3-LU h-LU 2 - X I " —xn-2 2-u IE —x--iv-1 1 1 1 1 1 1 1 1 1 h 82 8 6 9 0 9 4 9 8 102 ANGLE (DEGREES) Figure 42. Two-dimensional d i r e c t ordination of quadrat groupings at PIT (see Figure 41). Means of angle and height were computed for quadrats belonging to each grouping, and groupings thus positioned; standard deviations are indicated by l i n e s . 166 V. . I s o t h e c i u m s t o l o n i f e r u m - P o r e l l a cordaeana Other s p e c i e s : N . . - d o u g l a s i i , C._ c r i s p i f o l i u m L o c a t i o n : t o o few g u a d r a t s i n the group. V I . -Homalothecium f u l g e s c e n s Other s p e c i e s : N._ d o u g l a s i i , I_. s t o l o n i f erum ( o c c a s i o n a l ) , Zygodon y i r i d i s s i m u s (rare) L o c a t i o n : upper s i d e of the t r u n k , a t mid t o h i g h e r e l e v a t i o n s . V I I o Homalothecium n u t t a l l i i Other s p e c i e s : H._ f u l g e s c e n s , N.. d o u g l a s i i Location,: upper s i d e of the t r u n k , a t h i g h e r e l e v a t i o n s . . V I I I . .Neckera d o u g l a s i i - Hornalothecium f u l g e s c e n s Other s p e c i e s : P o r e l l a n a v i c u l a r i s , L.. membranacea, M. m e n z i e s i i L o c a t i o n : upper s i d e of t r u n k , a t mid t o h i g h e r e l e v a t i o n s . . I X . Neckera d o u g l a s i i Other s p e c i e s : M._ m e n z i e s i i , P.. cordaeana, FU f u l g e s c e n s L o c a t i o n : upper s i d e of t r u n k , a t mid t o h i g h e r e l e v a t i o n s . . X. Metaneckera m e n z i e s i i Other s p e c i e s : N. d o u g l a s i i L o c a t i o n : low t o mid s i d e s of t r u n k , j u s t above t h e base.. X I . L e p r a r i a membranacea Other s p e c i e s : M.. m e n z i e s i i L o c a t i o n : l ower s i d e of the t r u n k , a t mid t o h i g h e r e l e v a t i o n s . 167 X I I . L e p r a r i a membranacea - Metaneckera m e n z i e s i i Other s p e c i e s : n u t t a l l i i , H._ f u l g e s c e n s , Z ._ y i r i g i s s i m u s L o c a t i o n : l o w e r s i d e of t h e t r u n k , a t mid t o h i g h e r e l e v a t i o n s . F i g u r e 41 s u g g e s t s t h a t t h r e e d i s t i n c t c l u s t e r s can be r e c o g n i z e d . Groups X, X I , and X I I form the f i r s t c l u s t e r ; t h e s e groups t e n d t o o c c u r on t h e lower s i d e s of t r e e t r u n k s , and are dominated by Metaneckera m e n z i e s i i and L e p r a r i a membranacea. A second group c o n s i s t s o n l y of group I , t h e d i s t i n c t i v e b a s a l v e g e t a t i o n dominated by Claoppdium c r i s p i f o l i u m . A t h i r d major c l u s t e r c o n s i s t s of groups I I - I X . The groups w i t h i n t h i s c l u s t e r show a ' c h a i n i n g e f f e c t ' (Sneath and S o k a l 1973).. However, groups V I I I and IX appear t o be d i s t i n c t from t h e o t h e r s . These 2 groups c o n t a i n g u a d r a t s on l a r g e , hummocky mats of Neckera d o u g l a s i i and Homalothecium f j l i a e s c e n s , and are t h u s d i s t i n g u i s h e d . Groups I I - V I I g e n e r a l l y c o n t a i n s p e c i e s which form s m a l l e r and t h i n n e r mats on t h e upper s i d e of t h e b o l e . Group i n t e r r e l a t i o n s h i p s i n the c l u s t e r a n a l y s i s appear t o c o r r e s p o n d t o the s p a t i a l d i s t r i b u t i o n of the e p i p h y t i c s p e c i e s on the t r u n k . F i g u r e 42 s u g g e s t s t h a t groups I and IV o v e r l a p but form a s p a t i a l l y d i s t i n c t group near the t r e e base. Groups X-XII form a second u n i t i n which a t r e n d from L e p r a r i a membranacea (lower s i d e o f t h e bole) t o Metaneckera m e n z i e s i i (lower t o mid s i d e s of t h e bole) i s suggested. The o t h e r groups show a h i g h degree of s p a t i a l o v e r l a p . They a l l o c c u r on the upper s i d e of t h e b o l e , g e n e r a l l y a t h i g h e r e l e v a t i o n s . 168 BRI The r e s u l t a n t c l u s t e r a n a l y s i s f o r t h i s s i t e i s shown i n F i g u r e 4 3 ; t h e c o r r e s p o n d i n g d i r e c t o r d i n a t i o n i s shown i n F i g u r e 4 4 . A t o t a l o f 9 c l u s t e r groups have been r e c o g n i z e d , and are d i s c u s s e d below. 1- Clappgdium c r i s p i f o l i u m Other s p e c i e s : Apometzgeria pubescens, P o r e l l a c o r d a e a n a , £lagiomnium yenustum, Homalothecium f u l g e s c e n s L o c a t i o n : s p l a y e d - o u t t r e e base. I I . L e p r a r i a membranacea Other s p e c i e s : G r a p h i s s c r i p t a , Metaneckera m e n z i e s i i L o c a t i o n : l o w e r s i d e of t h e t r u n k , a t a l l e l e v a t i o n s above the t r e e base. . I I I . G r a p h i s s c r i p t a Other s p e c i e s : M. m e n z i e s i i , L^ membranacea L o c a t i o n : lower s i d e of the t r u n k , a t a l l e l e v a t i o n s above t h e t r e e base* IV. Homalothecium f u l g e s c e n s Other s p e c i e s : Homalothecium n u t t a l l i i , Neckera d o u g l a s i i , cordaeana L o c a t i o n ; upper s i d e o f t r e e t r u n k , a t a l l e l e v a t i o n s above the base. . V. A n t i t r i c h i a c a l i f o r n i c a -22.57 -10.69 8.76 - 7 3 9 -6.11 3.86 -3.54 -2.78 UJ U Z GO Q I (32) T 3C (23) (15) 3V (42) V VI (15) (22) (38) (106) (61) Figure 43. Cluster analysis of quadrats from BRI. Values i n brackets represent the number of quadrats found i n each of the recognized groupings. Distance i s euclidean. J I I I I I I I I CO on 3-IxJ h-LLI I— I CD 2-LLI n -vi-'" v--TL-- I t -IWH-—rx4— •iv-— V E — ~T 1 1 1 1 1 1 1 1 1 r 82 86 90 94 98 102 ANGLE (DEGREES) Figure 44. Two-dimensional direct ordination of quadrat groupings at BRI (see Figure 43). Means of angle and height were computed for quadrats belonging to each grouping, and groupings thus positioned; standard deviations are indicated by l i n e s . 171 Other s p e c i e s : H. . n u t t a l l i i , N«_ d o u g l a s i i , P. . cordaeana L o c a t i o n : upper s i d e of t r u n k , a t mid t o h i g h e r e l e v a t i o n s . . VI. Neckera d o u g l a s i i Other s p e c i e s : M.. m e n z i e s i i , D e n d r o a l s i a a b i e t i n a L o c a t i o n : upper s i d e of t r u n k , at mid t o hig h e l e v a t i o n s . . V I I . D e n d r o a l s i a a b i e t i n a Other s p e c i e s : M«_ m e n z i e s i i , N.. d o u g l a s i i L o c a t i o n : upper s i d e of the t r u n k , a t mid "to h i g h e r ' e l e v a t i o n s . . V I I I . .Metaneckera m e n z i e s i i Other s p e c i e s : D.. a b i e t i n a , N . . . d o u g l a s i i , H ^ f u l g e s c e n s L o c a t i o n : upper s i d e of the t r u n k , a t mid e l e v a t i o n s . I X . Metaneckera m e n z i e s i i - Neckera d o u g l a s i i Other s p e c i e s : D. . a b i e t i n a , H.. f u l g e s c e n s , A t. c a l i f or n i c a L o c a t i o n : mid t o upper s i d e s of t r u n k , at a l l e l e v a t i o n s above t h e t r e e base. Group i n t e r r e l a t i o n s h i p s can be i n f e r r e d from the s t r u c t u r e of t h e dendrogram ( F i g u r e 4 3 ) .. The most d i s t i n c t i v e c l u s t e r c o n s i s t s of groups V I I I and I X , both of which show h i g h f r e g u e n c y of Metaneckera m e n z i e s i i . T h i s s p e c i e s forms l a r g e , monotypic mats (or sometimes i n t e r m i x e d w i t h Neckera d o u g l a s i i ) , so t h a t t h e d i s t i n c t i v e n e s s of t h e s e groups i s not s u r p r i s i n g . Group V I I i s a l s o d i s t i n c t , and c o n s i s t s of g u a d r a t s h i g h i n D e n d r o a l s i a a b i e t i n a (which a l s o forms l a r g e monotypic mats). 172 The b a s a l v e g e t a t i o n dominated by Claopodium c r i s p i f o l i u m (group I) forms a t h i r d d i s t i n c t c l u s t e r . Groups I I and I I I (dominated by L e p r a r i a membranacea and G r a p h i s s c r i p t a r e s p e c t i v e l y ) , both of which occur on the l o w e r s i d e o f the t r u n k , a l s o c l u s t e r t o g e t h e r . These 2 groups i n t u r n c l u s t e r w i t h groups I V - V I , which c o n t a i n s p e c i e s which form s m a l l mats on the upper s i d e of t h e b o l e and show a h i g h degree of p o s i t i v e a s s o c i a t i o n . These r e s u l t s s u ggest t h a t the c l u s t e r s and d e f i n e d groups c o r r e s p o n d w e l l w i t h m i c r o h a b i t a t p r e f e r e n c e s of the e p i p h y t i c s p e c i e s on t h e b o l e . . The s p a t i a l r e l a t i o n s h i p s between the d e f i n e d groups ( F i g u r e 44) suggest t h a t group I occurs at t h e base and i s s p a t i a l l y d i s t i n c t . . G r o u p s I I and I I I , which o v e r l a p w i t h one a n o t h e r , t o g e t h e r form a d i s t i n c t c l u s t e r on t h e lower s i d e of the bole..The o t h e r groups, which o c c u r on the upper s i d e o f t h e t r e e above t h e base, show v a r y i n g degrees of o v e r l a p . . G r o u p V I I I appears t o p r e f e r lower e l e v a t i o n s t h a t t h e o t h e r s , however. E p i p h y t i c Communities on Acer macrophyllum A s y n u s i a l approach t o the c l a s s i f i c a t i o n of e p i p h y t i c communities has been used i n Europe (Barkman 1958, 1973, S j o g r e n 1961).. Such methods f o l l o w c l o s e l y t h e t e c h n i g u e s advanced by the B r a u n - B l a n g u e t s c h o o l o f p h y t o s o c i o l o g y (reviewed by Westhoff and van der Maarel 1973). The approach i s s u b j e c t i v e , and f o r t h i s reason has been c r i t i c i z e d (Poore 1955). As Barkman (1 958, 1 973) has p o i n t e d o u t , however, such an approach has some advantages from the s t a n d p o i n t of v e g e t a t i o n a l c h a r a c t e r i z a t i o n . While t h e methods may be s u b j e c t i v e , t h e r e s u l t s c o r r e s p o n d t o 173 v e g e t a t i o n a l u n i t s which a r e r e c o g n i z a b l e i n the f i e l d , and s e r v e t o d e s c r i b e the v e g e t a t i o n i n a thorough and manageable f a s h i o n . . I w a t s u k i (1960) used a s i m i l a r approach i n the d e l i m i t a t i o n of e p i p h y t i c communities i n Japan, but placed' g u a d r a t s s y s t e m a t i c a l l y on the t r e e b o l e . He s t r e s s e d the d i f f i c u l t y of c h a r a c t e r i z i n g e p i p h y t i c a s s o c i a t i o n s ; t h i s i s r e f l e c t e d i n the summary t a b l e s he p r e s e n t s . I n North America, e p i p h y t i c u n i o n s were d e s c r i b e d by B i l l i n g s and Drew (1938) and Hoffman and K a z m i e r s k i (1969). Most North American workers, however, have c o n c l u d e d t h a t e p i p h y t i c commmunities are not r e c o g n i z a b l e because of t h e dynamic n a t u r e o f t h e v e g e t a t i o n ( S t r i n g e r and S t r i n g e r 1974, S l a c k 1976, 1977). I n t h i s s t u d y , i t was f e l t t h a t d e s p i t e the dynamic n a t u r e of the v e g e t a t i o n , v e g e t a t i o n a l u n i t s can be r e c o g n i z e d and c h a r a c t e r i z e d . I t has a l r e a d y been shown t h a t w h i l e t h e e p i p h y t i c v e g e t a t i o n i s s t r u c t u r a l l y complex, t h e i n d i v i d u a l e p i p h y t i c s p e c i e s do show d e f i n i t e h a b i t a t p r e f e r e n c e s on t h e t r e e b o l e . F u r t h e r m o r e , r e s u l t s p r e s e n t e d i n the p r e v i o u s s e c t i o n have shown t h a t d e f i n e d v e g e t a t i o n a l g r o u p i n g s occupy d i s t i n c t r e g i o n s on the b o l e ( a l t h o u g h o v e r l a p of s p a t i a l n i c h e s i s o f t e n a p p a r e n t ) . T h i s s u g g e s t s t h a t t h e e p i p h y t i c v e g e t a t i o n of Acer macrophyllum i s c l a s s i f i a b l e d e s p i t e i t s i n h e r e n t c o m p l e x i t y . . While t h e c l u s t e r a n a l y s e s have been u s e f u l i n t h e d e l i n e a t i o n of g r o u p i n g s , t h e s e u n i t s cannot be c o n s i d e r e d t o c o r r e s p o n d t o ' n a t u r a l communities' f o r a number of r e a s o n s . The p r i m a r y problem i s r e l a t e d t o t h e s c a l e of samplin g * D i f f e r e n t 1 7 4 v e g e t a t i o n t y p e s may be d e t e c t e d i f d i f f e r e n t s i z e s of g u a d r a t s a r e u s e d . . T h i s has a number of i m p l i c a t i o n s when the data a r e s u b j e c t e d t o c l u s t e r a n a l y s i s , s i n c e the a l g o r i t h m d e t e c t s d i f f e r e n c e s i n s p e c i e s c o m p o s i t i o n and q u a n t i t i e s between g u a d r a t s ( r a t h e r than v e g e t a t i o n a l t y p e s ) . . T h u s the a l g o r i t h m may d e l i n e a t e a group on the b a s i s o f hig h f r e g u e n c y of a g i v e n s p e c i e s , and a n o t h e r group on t h e b a s i s o f lower f r e g u e n c y of the same s p e c i e s ( o f t e n i n c o m b i n a t i o n w i t h a n o t h e r s p e c i e s ) , even though one might i n t u i t i v e l y e x p e c t them t o belong t o t h e same community-type..Another problem o c c u r s i n t h e l o c a t i o n of g u a d r a t s . S y s t e m a t i c a l l y p l a c e d g u a d r a t s may occur on the •bo r d e r ' between 2 or more community-types, but t h e c l u s t e r i n g a l g o r i t h m has no way o f d e t e c t i n g t h i s and may t h e r e f o r e c o n s i d e r such g u a d r a t s t o r e p r e s e n t unigue g r o u p i n g s . . A t h i r d problem l i e s i n t h e l e v e l of ' c u t - o f f on the dendrogram (which d e f i n e s t h e number of r e c o g n i z e d g r o u p s ) . The l e v e l i s chosen somewhat a r b i t r a r i l y , and i s d i f f i c u l t t o p l a c e on a sound e c o l o g i c a l b a s i s . D e s p i t e t h e s e problems, c l u s t e r a n l a y s i s i s c o n s i d e r e d t o be u s e f u l i n t h e a n a l y s i s o f the e p i p h y t i c v e g e t a t i o n , s i n c e i t a l l o w s f o r t h e d e t e c t i o n of v e g e t a t i o n a l p a t t e r n i n g ; i t a l s o s u g g e s t s g r o u p i n g s and the i n t e r r e l a t i o n s h i p s between t h e s e g r o u p i n g s . These g r o u p i n g s can i n t u r n a i d i n the c h a r a c t e r i z a t i o n o f v e g e t a t i o n a l u n i t s which are r e c o g n i z a b l e i n t h e f i e l d . E p i p h y t i c communities have been d e f i n e d based upon the r e s u l t s of the c l u s t e r a n a l y s e s , combined w i t h f i e l d o b s e r v a t i o n s as w e l l as t h e r e s u l t s of o t h e r a n a l y s e s d e s c r i b e d i n p r e v i o u s c h a p t e r s . The more n e u t r a l term community i s used 175 here r a t h e r t h a n a s s o c i a t i o n (which a p p l i e s t o u n i t s d e r i v e d from methods of t h e Braun-Blanguet school) o r union..The l e v e l o f r e s o l u t i o n used i n the r e c o g n i t i o n of t h e s e communities i s n e c e s s a r i l y somewhat a r b i t r a r y ; however, an attempt has been made t o d e f i n e t h e s e communities t o c o r r e s p o n d t o the e p i p h y t i c a s s o c i a t i o n s d e s c r i b e d by Barkman (1958) and I w a t s u k i (1960).. Each community i s d e s c r i b e d below w i t h r e g a r d t o i t s f l o r i s t i c c o m p o s i t i o n , l o c a t i o n ( s i t e s a t which i t o c c u r s ) , and m i c r o h a b i t a t p r e f e r e n c e s on the b o l e . Communities have been named a f t e r t h e dominant s p e c i e s o c c u r r i n g i n each. 1. Hornalia t r i c h o m a n o i d e s community T h i s community-type o c c u r s o n l y a t the SQU s i t e . I t i s r e s t r i c t e d t o t r e e bases, and appears t o r e g u i r e p e r i o d i c i n u n d a t i o n o r perhaps snow c o v e r . a s s o c i a t e d s p e c i e s i n c l u d e Plagipmnium yenustum, Claopodium c r i s p i f o l i u m , and P o r e l l a c o r d a eana; P . h y t i d i a d e l p h u s t r i g u e t r u s , Stokes i e 11a p r a e l o n g a v a r . s t o k e s i i , L e u c o l e p i s m e n z i e s i i , and Apometzgeria pubescens may a l s o o c c u r o c c a s i o n a l l y . T h i s community i s a very d i s t i n c t e n t i t y on t r e e bases at t h i s s i t e , and l i k e l y r e f l e c t s a d i s t i n c t e c o l o g i c a l h a b i t a t . I t appears t o be the c l i m a x v e g e t a t i o n on t r e e b a s e s , a l t h o u g h on very o l d t r e e s i t may be overgrown t o some e x t e n t by mats o f Metaneckera m e n z i e s i i , Neckera d o u g l a s i i , and Homalothecium f u l g e s c e n s . 2. Clappodium c r i s p i f l o i u m community T h i s community-type o c c u r s a t FUR, UEL, PIT, and B R I . . I t i s l a r g e l y r e s t r i c t e d t o s p l a y e d - o u t t r e e b a s e s , a l t h o u g h i t 1 7 6 o c c a s i o n a l l y o c c u r s a t h i g h e r e l e v a t i o n s , e s p e c i a l l y on t r e e s w i t h a h i g h degree o f l e a n . A s s o c i a t e d s p e c i e s vary t o some e x t e n t from s i t e t o s i t e , and i n c l u d e Plagipmnium yenustum, Apometzgeria pubescens, Hypnum subimponens, R h y t i d i a d e l p h u s t r i g u e t r u s (SQU, P I T ) , Bhizgmnium g l a b r e s c e n s . M e t z g e r i a c o n j u g a t a (UEL), L e u c o l e p i s m e n z i e s i i (UEL), I s o t h e c i u m s t o l o n i f erum (FUR), and P o r e l l a n a y i c u l a r i s (FUR, UEL,PIT) . . T h i s community e s t a b l i s h e s on young specimens o f Acer macrophyllum and forms l a r g e e x t e n s i v e mats on t h e base of t h e t r e e as i t matures. . On o l d e r t r e e s i n which t h e base i s not s p l a y e d - o u t , t h i s community may be overgrown by mats o f Metaneckera m e n z i e s i i and Neckera d o u g l a s i i ; t h i s phenomenon i s p a r t i c u l a r i l y e v i d e n t a t BRI.. On s p l a y e d - o u t bases, a humus l a y e r i s o f t e n developed on which n o r m a l l y t e r r e s t r i a l s p e c i e s such as Plagiomnium i n s i g n e and Rhizpmnium g l a b r e s c e n s may occ u r . . At UEL, t h i s community may be overgrown by L e p r a r i a membranacea on d r i e r p a r t s of the t r e e b o l e . 3 . . L e p r a r i a membranacea community T h i s community-type i s found at a l l s i t e s , but rea c h e s i t s best development a t d r i e r s i t e s (UEL, P I T ) . I t i s l a r g e l y r e s t i c t e d t o the dry lo w e r s i d e of t h e b o l e , a t a l l e l e v a t i o n s above t h e t r e e base..At UEL and PIT, i t may a l s o occur on t h e mid t o upper s i d e s of t h e b o l e . A s s o c i a t e d s p e c i e s i n c l u d e G r a p h i s s c r i p t a , Conigcybe f u r f u r a c e a , Metaneckera m e n z i e s i i ( s m a l l t u f t s , branches h i g h l y f l a g e l l i f o r m ) , Homalothecium n u t t a l l i i , Zyggdgn y i r i d i s s i m u s , and I s o t h e c i u m s t o l o n i f e r u m (UEL). L e p r a r i a membranacea may grow over and k i l l the br y o p h y t e 177 s p e c i e s found w i t h i n t h i s community-type-E x c e p t a t UEL, t h i s community does not e s t a b l i s h on t r e e s u n t i l t h e i n c l i n a t i o n g r a d i e n t on the t r e e i s f a i r l y w e l l e s t a b l i s h e d . . A s the t r e e matures, t h e dry lower s i d e of the b o l e (bare bark) i s c o l o n i z e d by the l i c h e n s ; i n s l i g h t l y w e t t e r a r e a s , the a s s o c i a t e d b r y o p h y t e s a l s o o c c u r . In the w e t t e r r e g i o n s , the l i c h e n s may be overgrown by t h e bryophyte s p e c i e s , but i n d r i e r r e g i o n s L e p r a r i a membranacea o f t e n grows o v e r and e v e n t u a l l y k i l l s b r y o p h y t e s p e c i e s . 4. D e n d r o a l s i a a b i e t i n a community T h i s community-type o c c u r s o n l y a t BRI (where i t i s b e s t developed) and FUR..It o c c u r s at h i g h e r e l e v a t i o n s on t h e upper s i d e o f s l i g h t l y i n c l i n e d t r e e s , i n d e n s e l y shaded, humid mixed d e c i d u o u s - c o n i f e r o u s f o r e s t s . T h i s community o c c u r s on t h e same p a r t o f t h e b o l e as mats of Neckera d o u g l a s i i , Metaneckera m e n z i e s i i , A n t i t r i c h i a c a l i f o r n i c a , and o c c a s i o n a l l y i.2S§lothecium f u l g e s c e n s . I t i s d i s t i n g u i s h e d as a s e p a r a t e community s i n c e D. a b i e t i n a forms l a r g e , t h i c k , monotypic mats on the t r e e b o l e which c h a r a c t e r i s t i c a l l y show low s o c i a b i l i t y . These mats are b e s t developed at BRI, where t h e y may e x t e n d f o r 1-4 m a l o n g the upper s i d e of the b o l e . At FUR, the s p e c i e s o f t e n forms hummocky c u s h i o n s (to 1 m i n l e n g t h ) on the b o l e . . T h i s community g e n e r a l l y shows b e s t developed on v e r y l a r g e t r e e s w i t h s o f t , b r i t t l e , decomposed b a r k . 5. I s o t h e c i u m s t o l o n i f e r u m community T h i s community-type i s b e s t developed a t UEL, but a l s o 1 7 8 o c c u r s a t PIT. I t o c c u r s a t a l l e l e v a t i o n s above the t r e e base on mid t o upper s i d e s o f t h e b o l e , and i s r e s t r i c t e d t o d r i e r s i t e s (more open f o r e s t s ) . . In t h i s community, I s o t h e c i u m s t o l o n i f e r u m c o n s i s t s o f a few s h o r t , plumose, b a s a l l y a t t a c h e d branches which g i v e r i s e t o l o n g a t t e n u a t e , h a i r - l i k e branches* A s s o c i a t e d s p e c i e s i n c l u d e Homalothecium f u l g e s c e n s , Homalothecium n u t t a l l i i , Dicranum f u s c e s c e n s . P a r m e l i a s u l c a t a , P a r m e l i a s a x a t i l i s , C l a d o n i a s p e c i e s , Orth o t r i c h um l y e l l i i , P o lypodium g l y c y r r h i z a , Neckera d o u g l a s i i , P o r e l l a c o r d a e a n a , P o r e l l a n a y i c u l a r i s , and L e p r a r i a membranacea. T h i s community p e r s i s t s i n a r e a s where t h e microenvironment i s t o o d r y f o r t h e e s t a b l i s h m e n t of l a r g e mats of Metaneckera m e n z i e s i i and Neckera d o u g l a s i i . T h i s community-type may be s e r a i , o c c u r r i n g on younger t r e e s i n open f o r e s t s but g i v i n g way t o l a r g e r mat-forming s p e c i e s as t h e canopy c l o s e s i n and the e p i p h y t i c m icroenvironment becomes more humid. On v e r y exposed t r e e s near the UEL s i t e , t h e l i c h e n s P a r m e l i a s u l c a t a . P a r m e l i a s a x a t i l i s , P a r m e l i a q l a b r a t u l a , £armeliopsis ambigua, and C l a d o n i a spp. are most common, w i t h the b r y o p h y t e s I s o t h e c i u m s t o l o n i f e r u m , Hypnum c i r c i n a l e , O r t h o t r i c h u m c p n s i m i l e , and D i c r a n o w e i s i a c i r r a t a o c c u r r i n g s p o r a d i c a l l y . T h i s i s p r o b a b l y a x e r i c v e r s i o n of t h e I . s t o l o n i f e r u m community, a l t h o u g h f u r t h e r a n a l y s i s may show i t t o be a d i s t i n c t community-type. 6. . Metaneckera m e n z i e s i i community T h i s community-type o c c u r s a t a l l t h e s i t e s s t u d i e d , but shows b e s t development a t BRI. I t o c c u r s a t a l l e l e v a t i o n s above 179 the t r e e base, but a t most of the s i t e s i s most f r e g u e n t a t t h e 1-3 m l e v e l s on the b o l e . . I t may occur a t a l l i n c l i n a t i o n s on the b o l e , but a t most s i t e s p r e f e r s t h e mid t o upper s i d e s * T h i s community o f t e n o c c u r s a t t h e r e g i o n of t r a n s i t i o n between the wet upper s i d e of the b o l e and the d r i e r upper s i d e . The community dominant, Metaneckera m e n z i e s i i , o f t e n forms t h i c k , l a r g e monotypic mats which may grow over and e v e n t u a l l y k i l l o t h e r s p e c i e s . Other s p e c i e s which o c c u r w i t h i n t h i s community i n c l u d e Neckera d o u g l a s i i , A n t i t r i c h i a c a 1 i f o r n i c a , Homalotheeium f u l g e s c e n s , P o r e l l a cordaeana, and P o r e l l a n a y i c u l a r i s . T h i s community i s most common on l a r g e r t r e e s , and shows best development on l o o s e , d e c a y i n g bark. I t r a r e l y o c c u r s on s m a l l t r e e s . At BRI, Metaneckera m e n z i e s i i forms l a r g e (1-3 m) mats on the upper t o mid s i d e s of t h e b o l e which appear to compete f o r space w i t h D e n d r o a l s i a a b i e t i n a . . At FUR and PIT, mats te n d t o be s m a l l e r ( t o 0.5 m), and form hummocks on t h e t r u n k . At UEL, t h e s p e c i e s forms s m a l l mats near t h e t r e e base. T h i s community appears t o be a c l i m a x .type which, l i k e the D e n d r o a l s i a a b i e t i n a community, shows best development i n humid f o r e s t s . . H o w e v e r , i t i s a l s o t o l e r a n t of d r i e r c o n d i t i o n s . 7.-Homalothecium f u l g e s c e n s community T h i s community-type o c c u r s a t a l l the study s i t e s . I t i s t y p i c a l l y l o c a t e d on t h e upper s i d e of the b o l e , a t a l l e l e v a t i o n s above the t r e e base. I t i s most common on t r e e s i n more exposed a r e a s where l i g h t l e v e l s a re h i g h e r . S p e c i e s which occur i n t h i s cemmunity-type g e n e r a l l y grow c l o s e l y a p p r e s s e d to 180 the bark s u r f a c e , and i n c l u d e Homalothecium f u l g e s c e n s , P o r e l l a c o r d aeana, P o r e l l a n a y i c u l a r i s , Homalothecium n u t t a l l i i , and Hy.P_nu_m subimponens. The mat-forming s p e c i e s Neckera d o u g l a s i i , Metaneckera m e n z i e s i i , and A n t i t r i c h i a c a l i f o r n i c a may a l s o o c c u r as a minor component of t h i s community. The f e r n P2ll£2^iijm S i l S y r r h i z a a l s o o c c u r s here. T h i s community o c c u r s on both s m a l l and l a r g e t r e e s . However, on o l d e r t r e e s i t i s o f t e n overgrown by mat-forming s p e c i e s such as Metaneckera m e n z i e s i i , Neckera d o u g l a s i i , and D e n d r o a l s i a a b i e t i n a , e s p e c i a l l y i n more humid s i t e s . . T h i s community p e r s i s t s on l a r g e r t r e e s i n more exposed l o c a t i o n s . 8.-Neckera d o u g l a s i i community T h i s community-type o c c u r s at a l l t he study s i t e s e x c e p t UEL. I t i s l o c a t e d on the upper s i d e of the b o l e , a t a l l e l e v a t i o n s above t h e t r e e base. I t i s most common i n f a i r l y open f o r e s t s w i t h h i g h h u m i d i t y and l i g h t l e v e l s (PIT and SQU) , but a l s o o c c u r s i n more c l o s e d f o r e s t s i t u a t i o n s (BRI and FUR) . Other s p e c i e s which occur w i t h i n t h i s community-type i n c l u d e A n t i t r i c h i a c a l i f o r n i c a , Neckera pennata, and Polyppdium fliicyrrhiza.. The s p e c i e s Homalothecium f u l g e s c e n s , Metaneckera m e n z i e s i i , P o r e l l a cordaeana, and P o r e l l a n a y i c u l a r i s may be minor components of t h i s community. A l t h o u g h the Homalothecium f u l g e s c e n s and Neckera d o u g l a s i i communities tend t o occur on the same r e g i o n s on t r e e b o l e s , the two a r e w e l l d i s t i n g u i s h e d . Major s p e c i e s o f t h e N ^ _ d o u g l a s i i community form l a r g e mats which may grow over and k i l l c l o s e l y -a p p r e s s e d s p e c i e s of the H._ f u l g e s c e n s community. F u r t h e r m o r e , 1 8 1 the H . . f u l g e s c e n s community i s more common on t r e e s i n more exposed s i t u a t i o n s , w h i l e t h e N»_ d o u g l a s i i community i s b e s t d eveloped on t r e e s i n more c l o s e d a r e a s . 9 ..Zygodon y i r i d i s s i m u s community T h i s community-type forms s m a l l p a t c h e s on a r e a s of the t r e e b o l e where mat-forming bryophyte s p e c i e s do not o c c u r . T y p i c a l l y , i t i s l o c a t e d on t h e mid s i d e of t r e e b o l e s at h i g h e r e l e v a t i o n s , and may be more common above t h e 5 m h e i g h t . . I t i s most common a t DEL, PIT, and FDR, but o c c u r s o n l y o c c a s i o n a l l y a t SQU and BRI. S p e c i e s which o c c u r i n t h i s community i n c l u d e Zygodon y i r i d i s s i m u s , F r u l l a n i a t a m a r i s c i s s p . . n i s g u a l l e n s i s , Homalothecium n u t t a l l i i , O r t h o t r i c h u m l y e l l i i , and Lo p h o c o l e a c u s p i d a t a . . The s p e c i e s Homalothecium f u l g e s c e n s , L e p r a r i a membranacea, and I s o t h e c i u m s t o l o n i f e r u m (UEL) may be minor components of t h i s community. T h i s community i s most common on s m a l l e r t r e e s . I t may p e r s i s t on o l d e r t r e e s , p a r t i c u l a r i l y on the t h i n , h a rd bark found at h i g h e r e l e v a t i o n s . I t i s o f t e n overgrown by mat-forming bryophyte s p e c i e s , s u g g e s t i n g t h a t i t may be a s e r a i s t a g e . 182 CHAPTER 10 - THE DYNAMICS OF EPIPHYTIC VEGETATION ON ACER MACROPHZLLOM I n t h i s c h a p t e r , the dynamic nat u r e o f the e p i p h y t i c v e g e t a t i o n on Acer macrophyllum i s o u t l i n e d . . The r o l e and i m p o r t a n c e o f s u c c e s s i o n i s d i s c u s s e d , and f a c t o r s thought t o be i m p o r t a n t i n e x p l a i n i n g e p i p h y t i c s u c c e s s i o n a re summarized. Changes i n the e p i p h y t i c v e g e t a t i o n w i t h t r e e s i z e are d i s c u s s e d f o r 3 of t h e s i t e s . A d i s c u s s i o n of t h e r o l e of e p i p h y t i c v e g e t a t i o n c o n c l u d e s the c h a p t e r . S u c c e s s i o n a l A s p e c t s o f E p i p h y t i c V e g e t a t i o n on Acer Macrophyllum Y a r r a n t o n (1972) has suggested t h a t s u c c e s s i o n i n e p i p h y t i c systems (changes i n e p i p h y t i c c o m p o s i t i o n w i t h i n c r e a s i n g age of t h e phorophyte) i s not d i r e c t l y comparable to c l a s s i c a l C l e m e n t s i a n s u c c e s s i o n i n which a d i s t u r b e d a r e a i s c o l o n i z e d by p l a n t s which b r i n g about e n v i r o n m e n t a l changes t o t h e h a b i t a t which i n t u r n a l l o w o t h e r s p e c i e s t o i n v a d e , the p r o c e s s c o n t i n u i n g u n t i l an e q u i l i b r i u m (and c o r r e s p o n d i n g v e g e t a t i o n a l c l i m a x ) i s reached..He p o i n t s out t h a t t h e r e i s l i t t l e e v i d e n c e t o s u g g e s t t h a t the c o l o n i z i n g e p i p h y t e s t h e m s e l v e s b r i n g about e n v i r o n m e n t a l changes which a l l o w o t h e r s p e c i e s t o succeed them. R a t h e r , e n v i r o n m e n t a l changes t o t h e e p i p h y t i c h a b i t a t a r e brought about by t h e phorophyte i t s e l f as i t grows. S u b s t r a t e changes ( p h y s i c a l and c h e m i c a l a s p e c t s of t h e bark) t a k e p l a c e 183 as the t r e e matures, s i g n i f i c a n t l y a l t e r i n g the m i c r o h a b i t a t s open t o c o l o n i z a t i o n by e p i p h y t i c s p e c i e s . F u r t h e r m o r e , t h e s u r r o u n d i n g v a s c u l a r v e g e t a t i o n may a l s o p l a y an i m p o r t a n t r o l e . O f t e n t h e phorophyte becomes e s t a b l i s h e d i n more open areas w i t h i n t h e f o r e s t (or i n a d i s t u r b e d a r e a ) . . I n such a r e g i o n , t h e e p i p h y t i c m icroenvironment i s r e l a t i v e l y x e r i c and h a r s h , i m p o s i n g s e v e r e c o n s t r a i n t s on c o l o n i z i n g s p e c i e s * As t h e t r e e (and the s u r r o u n d i n g v a s c u l a r v e g e t a t i o n ) matures, the' canopy becomes more dense, c r e a t i n g an i n c r e a s i n g l y humid mi c r o e n v i r o n m e n t which a l l o w s f o r the c o l o n i z a t i o n of d i f f e r e n t e p i p h y t i c s p e c i e s . . A l s o , Barkman (1958) and J o n e s c u (1970) have p o i n t e d out t h a t t h e a s p e c t or i n c l i n a t i o n g r a d i e n t s around t h e b o l e becomes more pronounced as the t r e e i n c r e a s e s i n g i r t h . T h i s t o o can be ex p e c t e d t o b r i n g about c o r r e s p o n d i n g changes i n the e p i p h y t i c v e g e t a t i o n as t h e t r e e grows. S l a c k (1976) c o n s i d e r s changes i n bark s u b s t r a t e t o be an i m p o r t a n t f a c t o r i n d e t e r m i n i n g e p i p h y t i c s u c c e s s i o n . I t has a l r e a d y been shown t h a t the bark o f Acer Macrophyllum changes w i t h t r e e s i z e . A l s o , t h e i n c l i n a t i o n g r a d i e n t on t h i s p horophyte becomes more pronounced w i t h age; on s m a l l e r t r e e s , b r y o p h y t e mats o f t e n o c c u r over the e n t i r e b o l e , but on l a r g e r t r e e s d e f i n i t e upper and lower s i d e s a r e a p p a r e n t , w i t h b r y o p h y t e mats o c c u r r i n g o n l y on t h e upper s i d e . I t i s d i f f i c u l t t o say which of t h e s e f a c t o r s i s most i m p o r t a n t i n a c c o u n t i n g f o r changes i n t h e e p i p h y t i c v e g e t a t i o n on the t r e e as i t ages; i n f a c t , t h e s e f a c t o r s l i k e l y a c t s y n e r g i s t i c a l l y . Other f a c t o r s may a l s o be i n v o l v e d , such as changes i n canopy and b r a n c h i n g s t r u t u r e as the t r e e matures 1 8 4 which may a l t e r stemflow on the t r u n k . B i o t i c f a c t o r s such as c o m p e t i t i o n and d i s p e r s i b i l i t y a r e a l s o i m p o r t a n t i n t h e d i s c u s s i o n o f e p i p h y t i c succession-. Most s u c c e s s i o n a l s t u d i e s o f e p i p h y t i c v e g e t a t i o n have i n v o l v e d f a i r l y c a s u a l assessments of d i f f e r e n c e s i n s p e c i e s c o m p o s i t i o n on t r e e s of v a r y i n g d i a m e t e r s . . Such a s t r a t e g y assumes t h a t t h e microenvironment which t h e e p i p h y t i c v e g e t a t i o n has been s u b j e c t e d t o on the d i f f e r e n t - a g e d t r e e s has been s i m i l a r o v er t i m e , an assumption which o f t e n may not be v a l i d . However, i f a number of t r e e s a r e examined, and i f t r e e s a re s e l e c t e d from s i m i l a r a r e a s w i t h i n a mature f o r e s t , t h i s problem can be m i n i m i z e d . Such an approach has been t a k e n here. S t u d i e s of s u c c e s s i o n of e p i p h y t i c v e g e t a t i o n on Acer macrophyllum were undertaken a t BRI, UEL, and SQU. At FUR and PIT, t h e r e were u n f o r t u n a t e l y t o o few s m a l l t r e e s t o p r o p e r l y a n a l y z e s u c c e s s i o n a l seguences. At each of the s i t e s s t u d i e d , s p e c i e s c o m p o s i t i o n and s t r u c t u r e were examined and compared on s m a l l (young) , m i d - s i z e d (mature) , and l a r g e (very old) t r e e s i n an a t t e m p t t o a s s e s s changes i n e p i p h y t i c c o m p o s i t i o n and s t r u c t u r e w i t h t r e e s i z e (which i s a measure of t r e e age) . Because d i f f e r e n c e s i n s u c c e s s i o n a l seguences are apparent a t the s i t e s , each i s d i s c u s s e d s e p a r a t e l y . SQU The i n c l i n a t i o n g r a d i e n t i s p o o r l y developed on young t r e e s (DBH o f 1 0 0 - 2 0 0 mm) a t t h i s s i t e . Dominant s p e c i e s i n c l u d e Neckera d o u g l a s i i (which may form e x t e n s i v e c o l o n i e s ) , Homalpthecium f u l g e s c e n s , P o r e l l a c o r daeana, Homalothecium 185 n u t t a l l i i , and P o r e l l a n a v i c u l a r i s . Homalia t r i c h o m a n o i d e s i s common near the t r e e base ( t o an e l e v a t i o n of 0.5 m) . On s l i g h t l y o l d e r t r e e s , the i n c l i n a t o n g r a d i e n t becomes more pronounced, w i t h t h e l i c h e n L e p r a r i a membranacea o c c u r r i n g on the dry lower s i d e ; b r y o p h y t e s become i n c r e a s i n g l y r a r e on t h e lower s i d e of the t r e e as g i r t h i n c r e a s e s . . On mature t r e e s , l a r g e , hummocky mats of Metaneckera m e n z i e s i i , Neckera d o u g l a s i i , and t o a l e s s e r e x t e n t A n t i t r i c h i a c a l i f o r n i c a become more common. Homalothecium f u l g e s c e n s o c c u r s on .the upper s i d e of the b o l e between t h e s e mats. Mats of M-. m e n z i e s i i o f t e n o c c u r i n t h e r e g i o n of t r a n s i t i o n between t h e upper and lo w e r s i d e s of the b o l e . The lo w e r s i d e i s almost c o m p l e t e l y dominated by the l i c h e n s L e p r a r i a membranacea and O r a p h i s s c r i p t a ; s m a l l t u f t s o f M t m e n z i e s i i may a l s o o c c u r . Homalia t r i c h o m a n o i d e s i s the community dominant a t the t r e e base (to 1 m i n e l e v a t i o n ) , a l t h o u g h on mature t r e e s Plagipmnium yenustum, Apometzgeria pubeseens, Claopgdium c r i s p i f o l i u m , and P o r e l l a cordaeana may a l s o o c c u r . F i g u r e 45 shows the t y p i c a l s t r u c t u r e of the e p i p h y t i c v e g e t a t i o n on a mature t r e e at t h i s s i t e . On very o l d t r e e s , t h e b o l e i s o f t e n dominated by l a r g e t h i c k mats of Metaneckera m e n z i e s i i . A n t i t r i c h i a c a l i f o r n i c a a l s o appears t o be more common on o l d e r t r e e s , p a r t i c u l a r i l y on th e upper s i d e o f the b o l e a t h i g h e r e l e v a t i o n s . Polypodium H i z c y r r h i z a may occur i n the l a r g e upper branches and on t h e upper s i d e of the b o l e * 1 8 6 UEL Young trees (DBH of 100-200 mm) which occur i n more closed, shaded s i t e s support an epiphytic f l o r a which i s dominated by bryophyte species to an elevation of 2-3 m.. Isothecium stolpniferum i s the dominant species; other species include Homalothecium fulgescens, Qrthgtrichum• l y e 1 I i i , P orella n a y i c u l a r i s , F r u l l a n i a tamarisci ssp. nisgualiensis, Lophocolea cuspidata, Eadula bolanderi. Parmelia sulcata, and squamules of Cladpnia species. Claopodium c r i s p i f o l i u m and Porella cordaeana occur at the tree base (to an elevation of 0.25 m ). Above the f i r s t few meters, the epiphytic vegetation i s dominated by lichens, primarily species of Parmelia (including P..sulcata, Pj_. s a x a t i l i s , and P r glabratula ) and an unidentified species of Q.£b r p l ec hia; occasional patches of I. s t o l o n i f erum may also occur..On young trees i n more open, less shaded areas, bryophyte cover generally reaches only to about 1-1.5 m above the base..It i s again dominated by I._ s t o l o n i f erum. Above th i s elevation, epiphytic lichens predominate. The i n c l i n a t i o n gradient i s poorly developed on these trees. On mature trees, epiphytic bryophytes occur at higher elevations, reaching well into the large upper branches..As the tree increases in g i r t h , the i n c l i n a t i o n gradient becomes more pronounced. The upper side of ,the bole i s dominated by Isothecium stoloniferum, which forms extensive, thin mats, p a r t i c u l a r i l y at higher elevations. Other species occurring on the upper side of these trees include Homalothecium fulgescens, Metaneckera menziesii, Porella n a y i c u l a r i s , P o r e l l a cordaeana, and Dicranum fusee seens. .Small patches of Neckera douglasii also Figure 45. Structure of the ep i p h y t i c vege-t a t i o n on a large (DBH =610 mm) tree of Acer  macrophyllum at SQU. Dominant species on the bole are Metaneckera m e n z i e s i i , Neckera  d o u g l a s i i , and Homalothecium fulgescens. 1 Figure 46. The dry lower side of the bole of a large tree of Acer macrophyllum at UEL. The white crust i s L e p r a r i a membranacea; Isothecium  stoloniferum forms a mat to the l e f t . A small J* mat of Metaneckera menziesii occurs at the r i g h t . 188 o c c u r , but a r e n o r m a l l y only p o o r l y developed,.On d r i e r p a r t s of the b o l e , Homalotheci um n u t t a l l i i and Zygpdgn y i r i d i s s i m u s occur..The lower s i d e o f the b o l e of mature t r e e s i s dominated by l e p r a r i a membranacea; Coniocybe f u r f u r a c e a and t u f t s o f Metaneckera m e n z i e s i i may a l s o occur ( F i g u r e 46) . At the t r e e base, Claoppdium c r i s p i f o l i u m i s common, o f t e n o c c u r r i n g t o an e l e v a t i o n of 2-3 m. On ve r y o l d t r e e s , mats o f Metaneckera m e n z i e s i i t e n d t o be more common..This s p e c i e s may form e x t e n s i v e mats, e s p e c i a l l y on l o o s e , h i g h l y decomposed bark. Hcmalpthecium f u l g e s c e n s a l s o appears t o be more common on t h e s e t r e e s . The f e r n Polyppdium a l i c y r r h i z a o f t e n forms l a r g e c o l o n i e s on t h e t r u n k s of o l d i n c l i n e d t r e e s ( F i g u r e 47). The base of these t r e e s i s dominated by Olapppdium c r i s p i f o l i u m ; Plagiomnium yenusturn, Plagiomnium i n s i g n e , L e u c p l e p i s m e n z i e s i i , and Rhizomnium g l a b r e s c e n s may form e x t e n s i v e mats on s p l a y e d - o u t t r e e bases. BRI At t h i s s i t e , even young t r e e s (DBH of 100-200 mm) are c o v e r e d w i t h t h i c k mats of Neckera d o u g l a s i i ( F i g u r e 48) , P o r e l l a n a v i c u l a r i s , and o c c a s i o n a l l y Neckera pennata..Near the t r e e b a s e , Claoppdium c r i s p i f o l i u m and P o r e l l a cordaeana a re common. .In a r e a s where mats o f ls_ d o u g l a s i i do not o c c u r , and on t r e e s i n more open a r e a s , Homalothecium f u l g e s c e n s i s common. On d r i e r p a r t s of t h e b o l e . O r t h p t r i e h u m l y e l l i i and L e p r a r i a Sembranacea are o c c a s i o n a l l y e n c o u n t e r e d . Most t r e e s o f t h i s s i z e c l a s s have 90-95% b r y o p h y t e c o v e r on t h e f i r s t 5 m of the b o l e . Figure 47. Structure of the epiphytic vege-t a t i o n on a large (DBH = 645 mm.) tree of Acer  macrophyllum at UEL. Dominant epiphytes include Claoppdium c r i s p i f o l i u m , Isothecium stoloniferum, and the fern Polypodium g l y c y r r h i z a . Figure 48. Mat of Neckera d o u g l a s i i on a small (DBH = 240 mm.) tree of Acer macrophyllum at BRI. oo Figure 49. The epiphytic s t r u c t u r e on 2 large trees of Acer macrophyllum at BRI. Note the hummocky appearance of the vegetation, and barren patches on the bole. Dominant epiphytes are Metaneckera menziesii and Dendroalsia a b i e t i n a . Figure 50. Hummocks of epiphytic bryophytes on a large (DBH = 740 mm.) tree of Acer macrophyllum at BRI. Dominant species: Metaneckera m e n z i e s i i , Dendroalsia a b i e t i n a . A dislodged mat of M. menz-s i i i s shown near the center of the f i g u r e . 191 On mature t r e e s , l a r g e matted c o l o n i e s of N t d o u g l a s i i (and o c c a s i o n a l l y N.. pennata) o f t e n grow over and k i l l H L f u l g e s c e n s and 0^ l y e 1 I i i . Mats of Metaneckera m e n z i e s i i and D e n d r o a l s i a a b i e t i n a a l s o occur on these t r e e s , being most common i n more c l o s e d f o r e s t s i t u a t i o n s (Figure 49) . On very o l d t r e e s , Metaneckera m e n z i e s i i and D e n d r o a l s i a a b i e t i n a o f t e n become community dominants, forming l a r g e , t h i c k mats on the upper side of the b o l e . These mats may o c c a s i o n a l l y be sloughed o f f , g i v i n g the v e g e t a t i o n a hummocky, patched appearance (Figure 50) .. These s p e c i e s appear to e v e n t u a l l y outcompete Neckera d o u g l a s i i and Neckera pennata. In more exposed areas (where the trunk r e c e i v e s some d i r e c t s u n l i g h t ) , M«_ m e n z i e s i i and D. a b i e t i n a are o f t e n subdominants, o c c u r r i n g with N. d o u g l a s i i and Homalothecium f u l g e s c e n s . P o r e l l a n a y i c u l a r i s and N._ pennata r a r e l y occur on mature t r e e s * The i n c l i n a t i o n g r a d i e n t i s pronounced on these t r e e s ; the dry lower s i d e i s g e n e r a l l y c o l o n i z e d by L e p r a r i a membranaccea and Graphis scripta.„ T o t a l bryophyte cover on the f i r s t 5 meters v a r i e s between 50-70%, depending p r i m a r i l y on the degree of trunk i n c l i n a t i o n and l o c a t i o n of the t r e e w i t h i n the forest... D i s c u s s i o n A s u c c e s s i o n a l sequence i s apparent on the t r e e s and can be a t t r i b u t e d to changes i n the h a b i t a t s a v a i l a b l e t o the epiphytes as the t r e e grows. The c o n t i n u a l l y changing nature of the e p i p h y t i c environment appears to be r e s p o n s i b l e f o r the dynamic nature of the e p i p h y t i c v e g e t a t i o n on Acer macrophyllum. Because 192 a g i v e n t r e e b o l e r e p r e s e n t s a temporary h a b i t a t , e p i p h y t e s are c o l o n i z i n g s p e c i e s which c o n t i n u a l l y ' s e a r c h ' f o r new h a b i t a t s ( t r e e b o l e s ) w i t h i n the f o r e s t . At some of t h e s i t e s ( p a r t i c u l a r i l y SQU, FUR, and BRI) l a r g e e p i p h y t i c mats are o c c a s i o n a l l y d i s l o d g e d from t h e bark s u b s t r a t e , l e a v i n g b a r r e n a r e a s on the b o l e ( F i g u r e 5 1 ) . . T h i s s l o u g h i n g - o f f appears t o be caused by a c o m b i n a t i o n of the p r e c a r i o u s h a b i t a t , the weight of wet bryophyte mats, and winds. At BRI, mats o f Metaneckera m e n z i e s i i and D e n d r o a l s i a a b i e t i n a were c o l l e c t e d a f t e r a r a i n s t o r m , weighed, a i r d r i e d , and weighed a g a i n . V a l u e s (expressed as p e r c e n t weight of water i n t h e c o l l e c t e d sample) o f 68% and 77% were o b t a i n e d f o r t h e s e 2 s p e c i e s r e s p e c t i v e l y , showing t h a t mats are s u b s t a n t i a l l y h e a v i e r when wet. The b a r r e n p a t c h e s which r e s u l t from t h i s s l o u g h i n g - o f f , i f s m a l l , may be r e c o l o n i z e d by the same s p e c i e s as was l o s t . However, l a r g e p a t c h e s may be c o l o n i z e d by o t h e r s p e c i e s . T h i s phenomenon may i n p a r t account f o r the patchy appearance of t h e v e g e t a t i o n i n a r e a s where l a r g e mat-forming s p e c i e s a r e common..At FUR, SQU, and BRI (and perhaps PIT) t h e r e i s some e v i d e n c e t o suggest t h a t b a r r e n a r e a s c r e a t e d by f a l l i n g mats may be c o l o n i z e d by s p e c i e s which grow more c l o s e l y a p pressed t o t h e b a r k , p a r t i c u l a r i l y Homalothecium f u l g e s c e n s , Homalothecium n u t t a l l i i , and Zygodon y i r i d i s s i m u s . M at-forming s p e c i e s may e v e n t u a l l y grow over and k i l l t h e s e appressed forms, but as l o n g as bryophyte mats are o c c a s i o n a l l y sloughed o f f t h e appre s s e d forms are c o n t i n u a l l y s u p p l i e d w i t h new h a b i t a t s . T h i s s i t u a t i o n w e l l i l l u s t r a t e s t h e dynamic na t u r e o f the e p i p h y t i c v e g e t a t i o n , and emphasizes t h e i m p o r t a n c e o f the c o l o n i z a t i o n o f Figure 51. Sloughing-off of epiphytic vege-tat i o n from the bole of a large (DBH = 540 mm.) tree of Acer macrophyllum at BRI. A mat of Metaneckera menziesii has been dislodged from the substrate, taking with i t b i t s of decomposed bark. 194 temporary h a b i t a t s by t h e s e s p e c i e s . These o b s e r v a t i o n s must remain as s p e c u l a t i v e , however, u n t i l o b s e r v a t i o n s over t i m e (employing permanent guadrats) a re made. I t s h o u l d be emphasized t h a t s u c c e s s i o n i n e p i p h y t i c communities i s a complex phenomenon. I n d i v i d u a l t r e e s may vary i n t h e i r s u c c e s s i o n a l p a t t e r n s , p r i m a r i l y because o f d i f f e r e n c e s i n m i croenvironment ( l o c a t i o n of t h e phorophyte) , t r e e l e a n , and c o l o n i z a t i o n p o t e n t i a l o f the e p i p h y t e s * L o c a t i o n of the t r e e b o l e ( i n c l u d i n g between and w i t h i n - s i t e d i f f e r n c e s ) appear t o be e s p e c i a l l y i m p o r t a n t i n t h i s s t u d y . Role o f E p i p h y t e s on Acer macrophyllum Barkman (1958, and r e f e r e n c e s t h e r e i n ) has suggested t h a t e p i p h y t e s may be d e t r i m e n t a l t o t h e phorophyte i n an i n d i r e c t way, by r e t a i n i n g m o i s t u r e and promoting the breakdown and decay of o u t e r bark l a y e r s which may l e a d t o t h e e s t a b l i s h m e n t of p a r a s i t i c organisms ( b a c t e r i a and f u n g i ) and wood-damaging i n s e c t s . . O n Acer macrophyllum, t h e bark beneath a t h i c k c o v e r o f e p i p h y t i c b r y o p h y t e s i s o f t e n decayed, and an o r g a n i c l a y e r of decomposed bark and v e g e t a t i o n i s o f t e n formed. On o l d e r t r e e s at a l l s i t e s , t h e r e i s o f t e n e v i d e n c e of f u n g a l and i n s e c t a t t a c k beneath t h i c k b r y o p h y t e mats, p a r t i c u l a r i l y where an o r g a n i c l a y e r has developed.. E p i p h y t i c l i c h e n s may be an i m p o r t a n t source of n i t r o g e n i n f o r e s t communities (Forman 1975). P i k e e t a l . : (1977) found t h a t n i t r o g e n - f i x i n g l i c h e n s ( p r i m a r i l y L o b a r i a oregana) may make up 75% o f t h e t o t a l e p i p h y t i c biomass on a mature specimen o f E § e u d o t s u g a L m e n z i e s i i i n Oregon. In t h i s s t u d y , c y a n o p h i l o u s 195 l i c h e n s (mostly L... orecjana) occur i n t h e upper branches of Acer I§£E22hzi!u_m a t some s i t e s ( p a r t i c u l a i l y SQU) , s u g g e s t i n g t h a t the e p i p h y t e s may be a s o u r c e o f n i t r o g e n t o the ecosystem. S t u d i e s of the upper branch f l o r a a r e r e g u i r e d t o g u a n t i f y t h i s s o u r c e * The e p i p h y t i c v e g e t a t i o n on Acer macrophyllum i s w e l l d eveloped at a l l t h e study s i t e s , f o r m i n g c o n t i n u o u s b r y o p h y t e mats which occur w e l l i n t o t h e canopy r e g i o n ( l a r g e upper branches) ... T o t a l e p i p h y t i c biomass on t h e t r e e i s undoubtedly h i g h . . U n f o r t u n a t e l y , the p r o p e r assessment o f t o t a l biomass i n v o l v e s e x t e n s i v e s a m p l i n g of t h e v e g e t a t i o n over t h e e n t i r e b o l e combined wit h e s t i m a t i o n s of t o t a l s u r f a c e a rea on the b o l e , which i s beyond the scope of t h e p r e s e n t s t u d y . . However, d u r i n g r e c o n n a i s a n c e at t h e FUR s i t e i n March 1980, a l a r g e (DBH of 825 mm), r e c e n t l y f a l l e n t r e e was not e d . . A l t h o u g h upper branches were broken and s c a t t e r e d , and t h e i r e p i p h y t i c v e g e t a t i o n d i s l o d g e d by the f a l l , the lower p o r t i o n of the t r u n k (to about 15 m) and i t s e p i p h y t i c v e g e t a t i o n were s t i l l i n t a c t . T h i s t r e e o f f e r e d a unigue o p p o r t u n i t y t o e s t i m a t e biomass on the l o w e r b o l e , s i n c e c o l l e c t i o n s on a f a l l e n t r e e a r e e a s i l y made. The e p i p h y t i c v e g e t a t i o n was c o l l e c t e d a t 3 h e i g h t i n t e r v a l s a l o n g t h e b o l e (1-3 m, 4-6 m, and 10-12 m) . At each i n t e r v a l , t he b o l e was s t r i p p e d of a l l e p i p h y t i c v e g e t a t i o n (except f o r c r u s t o s e l i c h e n s ) . O r g a n i c l a y e r a c c u m u l a t i o n on t h e b o l e was a l s o c o l l e c t e d . No attempt was made t o d i s t i n g u i s h between t h e upper and l o w e r s i d e s of t h e b o l e when c o l l e c t i o n s were made. C o l l e c t e d m a t e r i a l from each of the 3 s i t e s was bagged s e p a r a t e l y , and brought back t o t h e l a b o r a t o r y where i t 196 was d r i e d , s o r t e d by s p e c i e s , and weighed. Diameter and h e i g h t measures a l o n g t h e b o l e were a l s o made t o e s t i m a t e t o t a l s u r f a c e a r e a . R e s u l t s from the a n a l y s i s are shown i n Table 24. A l l v a l u e s are e x p r e s s e d i n grams per meter s g u a r e , c a l c u l a t e d from e s t i m a t e s of t o t a l s u r f a c e a r e a . The r e s u l t s suggest t h a t i n d i v i d u a l s p e c i e s biomass changes a l o n g the b o l e , and t h a t t o t a l e p i p h y t i c biomass per u n i t area i n c r e a s e s w i t h e l e v a t i o n a l o n g the b o l e . A number o f f a c t o r s c o u l d e x p l a i n t h i s i n c r e a s e . Polypodium g l y c y r r h i z a c o n t r i b u t e s s u b s t a n t i a l l y t o t o t a l biomass a t h i g h e r e l e v a t i o n s , but i s f a r l e s s common near the t r e e base. A l s o , t h e i n c l i n a t i o n g r a d i e n t on the b o l e becomes l e s s pronounced a t h i g h e r e l e v a t i o n s , a l l o w i n g t h i c k b r y o p h y t e mats t o c o l o n i z e a l l s i d e s of the b o l e a t t h e s e h e i g h t s . At lower e l e v a t i o n s , t h e s e mats a r e r e s t r i c t e d t o the upper s i d e o f the b o l e . The f e r n Polypgdium g l y c y r r h i z a and mats of Metaneckera m e n z i e s i i , Neckera d o u g l a s i i , and D e n d r o a l s i a a b i e t i n a c o n t r i b u t e s u b s t a n t i a l l y t o the t o t a l e p i p h y t i c biomass. The r e s u l t s a l s o suggest t h a t a g r e a t d e a l of n o n - l i v i n g o r g a n i c matter (or humus) accumulates on t h e b o l e at a l l e l e v a t i o n s . I t s h o u l d be noted t h a t t h e bark o f t h i s t r e e was h i g h l y decomposed because of f u n g a l a t t a c k . Thus t o t a l o r g a n i c matter on t h i s t r e e may be h i g h e r than t h a t found on h e a l t h y l i v i n g t r e e s . E s t i m a t i o n of t o t a l e p i p h y t i c biomass on t h e t r e e cannot be as s e s s e d w i t h o u t s a m p l i n g the v e g e t a t i o n a t h i g h e r e l e v a t i o n s . However, based upon the d a t a c o l l e c t e d an e s t i m a t i o n of e p i p h y t i c biomass on the f i r s t 12 m o f the b o l e can be made; a 197 Level 1 2 3 Elevation on Bole l-3m 4-6m 10-12m 2 Total Surface Area (m ) 5.16 5.06 3.69 2 Biomass (g/m ) Metaneckera menziesii 62.92 63.93 91.34 Dendroalsia a b i e t i n a 4.07 23.12 24.64 Isothecium stoloniferum 8.52 - -Neckera d o u g l a s i i 27.07 56.32 85.45 Homalothecium fulgescens 3.25 15.02 20.56 Claopodium c r i s p i f o l i u m 6.22 - -P o r e l l a spp. 1.38 10.28 4.00 Polypodium g l y c y r r h i z a (leaves/stipes) 2.67 17.06 21.53 (roots/rhizomes) 6.78 106.92 87.39 2 Total L i v i n g Plant Matter (g/m ) 122.88 292.66 334.91 2 Total Non-living Organic Matter (g/m ) 64.50 116.11 124.81 Table 24. Epiphytic biomass at 3 sampling l e v e l s on a f a l l e n tree located at FUR. 198 v a l u e o f 5-7 kg of l i v i n g e p i p h y t i c v e g e t a t i o n was computed. P i k e e t a l . _ . (1977) c a l c u l a t e d a t o t a l e p i p h y t i c biomass of 17.79 kg on o l d - g r o w t h Pseudotsuga m e n z i e s i i i n Oregon. A comparable v a l u e f o r Acer macrophyllum (a much s m a l l e r t r e e than a mature specimen of P._ m e n z i e s i i ) would l i k e l y be c a l c u l a t e d i f the e p i p h y t i c v e g e t a t i o n a t h i g h e r e l e v a t i o n s was t a k e n i n t o a c count. The e p i p h y t i c v e g e t a t i o n i s undoubtedly a s i g n i f i c a n t component of the f o r e s t ecosystem. I t i s i n t e r e s t i n g t o note t h a t a l m o s t a l l the bryophyte v e g e t a t i o n a t the s t u d y s i t e s o c c u r s e p i p h y t i c a l l y . . On t h e f o r e s t f l o o r , o n l y r o t t i n g l o g s (which o c c u r o n l y o c c a s i o n a l l y ) have a w e l l developed and l u s h b r y o p h y t e v e g e t a t i o n . 199 CHAPTER 11 - SUMMARY T h i s s t u d y i s concerned w i t h t h e a n a l y s i s and d e s c r i p t i o n o f the s t r u c t u r e , c o m p o s i t i o n , and dynamics of the e p i p h y t i c v e g e t a t i o n on Acer macrophyllum i n sout h - w e s t e r n c o a s t a l B r i t i s h C o l umbia. .Data were c o l l e c t e d a t 5 s t u d y s i t e s ; a t each s i t e , 15 t r e e s o f s i m i l a r g i r t h from an e n v i r o n m e n t a l l y u n i f o r m r e g i o n w i t h i n t h e f o r e s t were s e l e c t e d f o r d e t a i l e d s t u d y . Each t r e e was sampled a t 6 l e v e l s t o an e l e v a t i o n of 5 m above the base. The e p i p h y t i c v e g e t a t i o n on Acer macrophyllum v a r i e s between t r e e s w i t h i n a s i t e , p r o b a b l y i n response t o v a r i a t i o n i n a few m i c r o e n v i r o n m e n t a l f a c t o r s . Each phorophyte e v i d e n t l y r e p r e s e n t s a unigue c o m b i n a t i o n of m i c r o h a b i t a t s so f a r as the e p i p h y t i c v e g e t a t i o n i s concerned. Other f a c t o r s such as c o m p e t i t i o n and d i s p e r s a b i l i t y may a l s o be i m p o r t a n t , a l t h o u g h the f u l l e x t e n t of t h e i r i n f l u e n c e remains unknown. B e t w e e n - s i t e d i f f e r e n c e s i n t h e e p i p h y t i c v e g e t a t i o n a r e a l s o a p p a r e n t . These d i f f e r e n c e s a r e l a r g e l y g u a n t i t a t i v e r a t h e r than g u a l i t a t i v e i n n a t u r e , w i t h s p e c i e s performance r a t h e r t h a n s p e c i e s c o m p o s i t i o n v a r y i n g between t h e s i t e s ; however, some s p e c i e s a r e s i t e s p e c i f i c . The o r d i n a t i o n r e s u l t s suggest t h a t , i n g e n e r a l , s i t e s a r e d i s t i n g u i s h a b l e on the b a s i s of t h e i r e p i p h y t i c v e g e t a t i o n ^ T h i s i s a t t r i b u t a b l e t o e n v i r o n m e n t a l d i f f e r e n c e s between the s i t e s , i n c l u d i n g f o r e s t s t r u c t u r e , bark f a c t o r s , and c l i m a t e . . N o n e l t h e l e s s , the o c c u r r e n c e of s i m i l a r e p i p h y t i c v e g e t a t i o n on t r e e s from d i f f e r e n t s i t e s s u g g e s t s t h a t 200 s i t e d i f f e r e n c e s a r e n o t a b s o l u t e . T h e r e s p o n s e o f t h e e p i p h y t i c v e g e t a t i o n t o t h e h e i g h t a n d i n c l i n a t i o n g r a d i e n t s o n t h e b o l e v a r i e s f r o m s i t e t o s i t e . I n g e n e r a l , r e s p o n s e t o t h e h e i g h t g r a d i e n t a p p e a r s s t r o n g e s t a t s i t e s i n w h i c h t h e e n v i r o n m e n t i s h a r s h e s t ( D E L , P I T , F U R ) . T h e r e s p o n s e t e n d s t o b e g r e a t e s t n e a r t h e t r e e b a s e , a n d l e s s e n s w i t h i n c r e a s i n g e l e v a t i o n u p t h e b o l e . . R e s p o n s e t o t h e i n c l i n a t i o n g r a d i e n t i s g e n e r a l l y s t r o n g a t a l l s i t e s , b u t a p p e a r s t o v a r y w i t h h e i g h t o n t h e b o l e ; a t m o s t o f t h e s i t e s , r e s p o n s e t o t h i s g r a d i e n t i s w e a k e s t a t t h e t r e e b a s e . . S t u d y o f t h e r e s p o n s e s o f i n d i v i d u a l s p e c i e s t o t h e h e i g h t a n d i n c l i n a t i o n g r a d i e n t s s h o w e d t h a t e a c h s p e c i e s o c c u p i e s a s p e c i f i c r e g i o n o n t h e b o l e , a n d t h a t t h e s e r e g i o n s a r e o f t e n c o n s i s t e n t f o r t h a t s p e c i e s o v e r a l l s t u d y s i t e s . T h i s s p a t i a l s e p a r a t i o n i s l i k e l y t h e r e s u l t o f n i c h e p a r t i t i o n i n g a t t r i b u t a b l e t o f a c t o r s s u c h a s p h y s i o l o g y a n d c o m p e t i t i o n . T h e a s s o c i a t i o n b e t w e e n s p e c i e s w a s a n a l y z e d u s i n g m u l t i v a r i a t e m e t h o d s . I n g e n e r a l , s p e c i e s a s s o c i a t i o n s a t e a c h o f t h e 5 s i t e s a r e s i m i l a r , a n d a r e t h o u g h t t o b e a r e f l e c t i o n o f h a b i t a t v a r i a t i o n o n t h e t r e e b o l e . C l u s t e r a n a l y s i s w a s u s e d t o d e f i n e d i s t i n c t g r o u p i n g s o f e p i p h y t i c v e g e t a t i o n . F o r a g i v e n s i t e , e a c h g r o u p i n g t e n d s t o o c c u p y a u n i g u e p o s i t i o n o n t h e b o l e , a l t h o u g h v a r y i n g d e g r e e s o f o v e r l a p a r e a p p a r e n t . T h e g r o u p i n g d e f i n e d b y t h e c l u s t e r a n a l y s i s , a c c o m p a n i e d b y f i e l d o b v s e r v a t i o n s , w e r e u s e d t o c h a r a c t e r i z e 9 e p i p h y t i c c o m m u n i t i e s o n A c e r m a c r o p h y l l u m . M o s t o f t h e c o m m u n i t i e s a r e f o u n d a t a l l t h e s t u d y s i t e s , b u t s o m e a r e s i t e s p e c i f i c . 20 1 The dynamic n a t u r e of t h e e p i p h y t i c v e g e t a t i o n on Acer macrophyllum 1 S apparent. . Changes i n the s t r u c t u r e and c o m p o s i t i o n of t h e e p i p h y t i c v e g e t a t i o n w i t h t r e e age and s i z e have been noted. C o l o n i z a t i o n , e s t a b l i s h m e n t , and subseguent c o m p e t i t i o n between s p e c i e s on t h e b o l e through time l e a d s t o a c o n s t a n t l y e v o l v i n g e p i p h y t i c system on the t r e e . A l t e r a t i o n s t o the s u r r o u n d i n g environment as a t r e e grows may a l s o b r i n g about changes i n i t s e p i p h y t i c v e g e t a t i o n . The s l o u g h i n g o f f of l a r g e b r y o p h y t e mats, which makes a v a i l a b l e n e w l y - c o l o n i z a b l e h a b i t a t s on the b o l e , may a l s o c o n t r i b u t e t o t h e dynamic n a t u r e o f t h e e p i p h y t i c v e g e t a t i o n . I t i s perhaps not s u r p r i s i n g t h a t t h i s d i s s e r t a t i o n has posed as many g u e s t i o n s as i t has attempted to answer. E p i p h y t i c v e g e t a t i o n i s by n a t u r e s t r u c t u r a l l y complex as a r e s u l t o f the s e n s i t i v i t y of b r y o p h y t e s t o s m a l l - s c a l e m i c r o e n v i r o n m e n t a l v a r i a t i o n . I n many c a s e s t h i s v a r i a t i o n i s d i f f i c u l t t o measure d i r e c t l y , so t h a t i n d i r e c t methods of g r a d i e n t a n a l y s i s a r e a p p r o p r i a t e . S e v e r a l d i r e c t i o n s f o r f u r t h e r work are i n d i c a t e d . F i r s t , more d e t a i l e d measurements of e n v i r o n m e n t a l v a r i a b l e s a re r e q u i r e d t o c h a r a c t e r i z e t h e e c o l o g i c a l g r a d i e n t s on the t r e e b o l e . . Second, a u t e c o l o g i c a l ( p a r t i c u l a r i l y p h y s i o l o g i c a l ) i n f o r m a t i o n i s r e q u i r e d f o r each e p i p h y t i c s p e c i e s i n o r d e r t o p r o p e r l y examine n i c h e d i f f e r e n t i a t i o n . T h i r d , t h e dynamic n a t u r e of t h e v e g e t a t i o n c o u l d be s t u d i e d by s e t t i n g up permanent g u a d r a t s on a number of t r e e s . F o u r t h , t h e st u d y c o u l d be extended t o h i g h e r l e v e l s on t h e b o l e and even i n t o the upper 202 branches, even though t h i s would i n c r e a s e d i f f i c u l t i e s i n sampling.. Such a s t r a t e g y would a l s o permit the e s t i m a t i o n of t o t a l e p i p h y t i c biomass and p r o d u c t i v i t y on t h i s phorophyte, a necessary s t e p toward g u a n t i f y i n g the importance of the e p i p h y t i c v e g e t a t i o n i n the t o t a l ecosystem. F i n a l l y , more s i t e s should be s t u d i e d i n order t o f u l l y e l u c i d a t e the dynamics, s t r u c t u r e , and compostion of the e p i p h y t i c v e g e t a t i o n on Acer macrophyllum. 203 REFERENCES Anderberg, M. R.. (1973). C l u s t e r A n a l y s i s f o r A p p l i c a t i o n s . 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E 8 2 7 1 0 . 6 1 6 7 2 0 . 7 6 6 7 3 C . 8 0 5 7 4 0 . 8 2 5 7 5 C . 6 6 0 P Ca Mg 0 . 0 6 7 3 . 5 9 6 0 . 2 2 9 0 . 0 9 3 4 . 5 3 4 0.4d9 O . C 6 9 4 . 1 2 4 0 . 1 5 9 0 . 0 9 0 2 . 864 0 . 3 14 0 . 0 9 7 3 . 7 2 0 0 . 3 9 2 0 . 0 8 5 2 . 8 2 4 0 . 2 8 e 0. 0 3 1 3. 5 7 0 0 . 4 2 8 0 . C S 5 7 . 9 0 0 0 . 2 8 2 0 . 0 9 C 4 . 8 7 8 0 . 3 1 9 0 . 0 8 4 6 . 0 8 1 0 . 3 4 0 0 . 0 9 7 5 . 7 0 5 0 . 3 0 0 0 . 0 8 8 6 . 5 7 0 0 . 2 9 9 0 . 0 6 9 5 . 7 8 4 0 . 3 0 1 0 . 0 7 4 6 . 5 9 7 0 . 3 2 7 0 . C 8 1 7 . 3 0 9 0 . 3 4 1 0. 0 7 4 3 . 8 1 9 0 . 2 5 1 0 . 0 8 2 4. 7 6 1 0 . 3 0 3 0 . 0 8 4 6.454 0 . 454 0 . 0 6 5 5 . 1 4 5 0 . 3 5 2 0 . 0 7 U 5 . 4 8 7 0 . 2 8 7 0 . 0 6 5 4 . 4 7 3 0 . 3 5 0 0 . 0 8 0 4 . 2 3 9 0 . 3 5 1 0 . 0 8 3 4 . 9 9 8 0 . 3 3 8 0 . 0 6 5 3 . 2 2 0 0 . 3 3 5 0 . 0 6 6 4 . 5 2 8 0 . 4 6 1 0 . 0 7 1 • 6 . 8 1 2 0 . 3 6 8 0 . 1 3 5 4 . 1 7 6 0 . 244 0 . C 7 4 3.366 0.224 0.064 4. 0 5 9 0 . 3 1 4 0 . C 7 9 4 . 7 4 9 0 . 2 5 7 0 . 0 7 3 3 . 6 7 8 0 . 181 0 . 1 2 2 3 . 8 8 8 0 . 2 3 2 0 . 1 1 6 5 . 8 2 9 0 . 2 6 2 0 . C 9 5 6 . 2 3 1 0 . 2 2 1 0 . 1 1 7 3 . 5 5 0 0 . 2 4 7 0 . 1 C 2 9 . 5 0 6 0 . 2 8 4 0 . 0 9 1 7 . 9 1 6 0 . 2 4 9 0 . 0 8 e 3 . 8 9 4 0 . 1 5 3 0. 1 2 4 5 . 5 1 1 0 . 1 8 9 0 . 1 3 7 2 . 3 6 4 0 . 1 6 2 0 . 0 9 1 3 . 8 3 8 0 . 1 7 3 0 . C 7 2 4 . 8 0 2 0 . 1 2 7 0 . 0 9 4 2.774 0 . 1 2 1 0 . 1 0 1 4. 6 7 7 0 . 1 6 7 0 . C 7 9 4 . 8 7 1 0 . 2 0 5 0 . 0 9 0 5 . 3 3 0 0 . 2 8 8 0 . 0 7 2 3 . 4 0 6 ' 0 . 2 0 8 0 . 0 7 S 6 . 0 6 0 0 . 3 7 1 0 . 0 8 9 5 . 2 9 1 0 . 2 S 8 0 . 0 e 2 4 . 0 0 2 0 . 3 4 6 0 . 0 6 2 1 1 . 8 8 1 0 . 3 3 5 0 . 0 9 9 7 . 2 7 3 0 . 3 4 2 O . 0 S 7 5 . 9 5 4 0 . 3 4 7 0 . 0 6 1 6.811 0 . 2 2 6 0 . 0 9 3 5 . 0 1 0 0 . 2 4 8 0 . 0 9 5 7 . 5 7 9 0 . 2 5 0 0 . 0 9 4 4 . 1 4 6 0 . 3 0 8 0 . 1 2 8 5 . 2 6 3 0 . 3 2 8 0 . 0 8 1 3 . 9 5 4 0 . 1 7 9 0 . 0 9 0 5 . 5 9 5 0 . 3 0 2 0 . 1 1 5 5 . 6 6 0 0 . 3 C 9 0 . 1 C 6 5 . 4 9 6 0 . 3 5 0 0 . 0 7 1 3 . 0 4 5 0 . 1 3 4 0 . 1 2 2 6 . 8 5 8 0 . 4 5 5 O . l i e 6 . 8 6 5 0 . 3 4 0 0 . 0 9 1 8 . 9 3 5 0 . 3 3 3 0. 1 1 0 5 . 6 2 5 0 . 2 5 6 0 . 115 6 . 1 0 3 0 . 2 0 5 0 . C 8 4 5 . 0 3 9 0 . 3 C 9 0 . 1 1 2 9 . 4 3 2 0 . 2 5 1 0 . 1 0 1 5 . 9 9 6 0 . 3 0 1 0 . I C E 9.41 I 0 . 4 1 5 0 . 1 0 0 6 . 7 7 6 0 . 3 9 5 0 . 0 8 1 6 . 2 9 7 0 . 2 3 3 0 . 0 9 1 6 . 0 0 4 0 . 3 6 7 K Ash pH 0 . 1 4 5 1 1 . 4 6 7 . 1 0 0 . 3 7 2 1 1 . 5 2 7 . 1 0 0 . 1 3 2 1 0 . 2 7 7 . 2 0 0 . 2 4 2 1 3 . 4 7 7 . 1 0 0 . 7 5 0 1 0 . 4 9 7 . 3 0 C . 4 5 4 1 2 . 1 6 7 . 1 5 C . 2 1 6 1 6 . 6 1 7 . 4 5 0 . 4 6 4 1 6 . 2 5 6 . 9 5 0 . 2 5 4 1 2 . 7 0 6 . 8 0 0 . 2 9 2 1 3 . 4 4 7 . 0 0 0 . 3 4 5 1 2 . 1 2 7 . 0 0 0 . 2 3 2 1 4 . 6 7 6 . 9 5 0 . 3 6 3 1 2 . 0 4 6 . 8 5 0 . 3 1 0 1 2 . 5 2 7 . 2 0 0 . 4 9 1 1 3 . 8 2 7 . 2 0 0 . 1 2 9 8 . 3 2 6 . 7 5 0 . 2 0 7 9 . 4 7 6 . 1 5 0 . 4 1 7 1 1 . 9 2 6 . 9 0 C . 2 3 6 9 . 8 6 6 . 7 5 0 . 1 4 2 9 . 9 0 6 . 8 5 0 . 4 0 2 8 . 8 1 6 . 5 5 0 . 3 1 1 9 . 6 8 6 . 7 0 0 . 2 2 6 1 0 . 9 1 7 . 0 0 0 . 3 7 2 7 . 0 8 6 . 6 5 0 . 2 9 7 1 1 . 0 3 6 . 8 0 C . 1 2 3 1 1 . 8 8 6 . 6 5 0 . 1 9 5 1 5 . 5 7 6 . 8 0 0 . 0 9 8 8 . 6 7 6 . 5 0 0 . 1 8 4 9 . 9 6 6 . 4 0 C . 1 5 8 1 2 . 8 2 6 . 9 0 0 . 0 9 3 8 . 2 6 6 . 0 0 0 . 1 3 5 1 2 . 4 8 6 . 6 5 0 . 3 2 3 1 2 . 2 4 6 . 6 0 0 . 1 3 6 9 . 8 5 6 . 3 5 0 . 2 2 3 1 1 . 0 5 6 . 5 0 C . 1 3 8 8 . 3 3 5 . 8 5 0 . 1 1 6 1 1 . 9 8 6 . 4 0 0 . 1 1 1 9 . 0 9 5 . 8 5 0 . 1 2 2 1 3 . 3 8 6 . 9 0 0 . 1 4 7 1 4 . 5 7 6 . 6 0 0 . 1 1 2 1 1 . 4 2 6 . 5 0 C . 1 1 9 8 . 2 9 6 . 2 5 0 . 1 1 6 1 1 . 5 1 6 . 2 0 0 . 1 3 1 1 0 . 7 7 6 . 5 0 0 . 1 2 4 1 0 . 5 9 6 . 5 5 0 . 2 3 9 1 0 . 9 5 6 . 8 0 0 . 1 4 6 7 . 9 5 6 . 8 0 0 . 1 4 5 1 1 . 5 2 6 . 9 5 0 . 2 4 5 1 1 . 2 3 6 . 6 5 0 . 3 6 3 9 . 9 3 7 . 1 0 0 . 1 8 3 1 7 . 6 2 6 . 5 5 0 . 3 0 3 1 1 . 8 8 6 . 5 5 0 . 1 5 4 1 1 . 9 2 6 . 8 5 0 . 2 3 5 1 1 . 8 2 6 . 9 0 0 . 1 6 7 1 0 . 5 7 6 . 9 0 0 . 0 8 5 1 3 . 5 2 6 . 1 0 0 . 2 2 1 1 0 . 9 8 6 . 1 5 0 . 1 4 7 1 5 . 8 4 6 . 5 0 0 . 1 5 7 9 . 6 5 6 . 8 0 0 . 1 5 5 1 2 . 7 3 6 . 6 0 0 . 2 5 3 1 1 . 9 3 7 . 1 5 0 . 6 7 2 1 2 . 0 7 6 . 7 0 0 . 2 2 0 7. 2 5 6 . 7 5 0 . 7 7 0 1 3 . 4 4 7 . 5 0 C . 1 7 6 1 3 . 0 9 7 . 2 0 0 . 1 7 4 1 4 . 8 7 6 . 5 5 0 . 3 0 3 1 1 . 5 5 6 . 1 0 0 . 1 3 7 1 1 . 6 0 7 . 2 5 C . 1 9 4 9 . 9 3 6 . 4 5 0 . 1 6 1 1 7 . 8 8 7 . 8 5 0 . 1 6 0 1 1 . 6 2 6 . 6 5 C . 1 5 8 1 5 . 8 3 7. 1 0 C . 1 4 5 1 2 . 7 7 6 . 7 5 0 . 1 9 3 1 3 . 0 7 6 . 9 0 0 . 1 6 8 1 1 . 8 6 7 . 1 0 Appendix 1. Bark chemistry of the 75 trees over the 5 study s i t e s . 209 Appendix 2. Checklist of species epiphytic on.the tree trunk of Acer macrophyllum. The study areas i n which the species was found are also given; ALL indicates that the species was found at a l l the study s i t e s . Mosses A n t i t r i c h i a c a l i f o r n i c a S u l l . & Lesq. SQU,BRI,FUR A n t i t r i c h i a curtipendula (Hedw.) B r i d . SQU Bartramia pomiformis Hedw. SQU Brachythecium asperrimum (Mitt.) S u l l . PIT,UEL Claopodium c r i s p i f o l i u m (Hook.) Ren. & Card. ALL Dendroalsia abietina (Hook.) B r i t t . BRI,FUR Dicranoweisia c i r r a t a (Hedw.) Kindb. ex Milde UEL Dicranum fuscescens Turn. UEL,PIT Dicranum tauricum Sapeh. UEL Drepanocladus uncinatus (Hedw.) Warnst. SQU,PIT Homalia trichomanoides (Hedw.) B.S.G. SQU Homalothecium fulgescens (Mitt, ex C. Muell.) Lawt. ALL Homalothecium n u t t a l l i i (Wils.) Jaeg. & Sauerb. ALL Hylocomium splendens (Hedw.) B.S.G. BRI,FUR Hypnum c i r c i n a l e Hook. UEL Hypnum subimponens Lesq. ALL Isopterygium elegans (Brid.) Lindb. UEL Isothecium stoloniferum B r i d . ALL Leucolepis menziesii (Hook.) Steere ex L. Koch BRI,UEL,FUR,PIT Metaneckera menziesii (Hook, ex Drumm.) Steere ALL 2 1 0 Mnium spinulosum B.S.G. UEL Neckera d o u g l a s i i Hook. ALL Neckera pennata Hedw. BRI Orthotrichum consimile Turn. BRI,FUR,SQU Orthotrichum l y e l l i i Hook. & Tayl. ALL Orthotrichum obtusifolium B r i d . BRI Plagiomnium venustum (Mitt.) Kop. ALL Plagiothecium denticulatum (Hedw.) B.S.G. UEL Pseudoleskea stenophylla Ren. & Card, ex Roell BRI Rhizomnium glabrescens (Kindb.) Kop. UEL,PIT,FUR Rhytidiadelphus loreus (Hedw.) Warnst. UEL,FUR Rhytidiadelphus triquetrus (Hedw.) Warnst. ALL Scleropodium caespitans (C. Muell.) L. Koch BRI,PIT S t b k e s i e l l a oregana (Sull.) Robins. ALL S t o k e s i e l l a praeldnga (Hedw.) Robins. var. s t o k e s i i (Turn.) Crum UEL,PIT Thamnobryum neckeroides (Hook.) Lawt. PIT,BRI Tort u l a r u r a l i s (Hedw.) Gaertn., Meyer, & Scherb. BRI Ulota c r i s p a (Hedw.) B r i d . var. alaskana (Card, et Ther.) BRI Zygodon y i r i d i s s i m u s (Dicks.) B r i d . ALL 211 Hepatics Apometzgeria pubescens (Schrank) Kuw. BRI,UEL,FUR,PIT F r u l l a n i a tamarisci (L.) Dum. subsp. n i s q u a l l e n s i s ( S u l l . ) Hatt. ALL Lophocolea cuspidata (Nees.) Limpr. ALL Lophocolea heterophylla (Schad.) Dum. UEL,PIT Metzgeria conjugata Lindb, UEL,BRI P o r e l l a cordaeana (Hub.) Moore ALL P o r e l l a n a y i c u l a r i s (Lehm. et Lindenb.) Lindb. ALL P o r e l l a r o e l l i i Steph. BRI Radula bolanderi Gott. ALL Radula complanata (L.) Dum. UEL,PIT Lichens Cladonia chlorophaea (Flk.) Spreng. UEL Cladonia subsquamosa Scop. (Hoffm.) UEL,PIT Collema subflaccidum Degel. FUR,BRI Coniocybe furfuracea (L.) Ach. UEL Graphis s c r i p t a (L.) Ach. ALL Lepraria membranacea (Dicks.) Vain. ALL Leptogium burnetiae Dodge BRI Lobaria pulmonaria (L.) Hoffm. SQU,BRI Ochrolechia pallescens (L.) Mass. SQU,PIT,UEL Parmelia g l a b r a t i i l a (Lamy) Nyl. UEL Parmelia s a x a t i l i s (L.) Ach. UEL Parmelia su l c a t a Tayl. UEL Parmeliopsis ambigua (Wulf.) Nyl. UEL P e l t i g e r a c o l l i n a (Ach.) Ach. UEL P e l t i g e r a h o r i z o r i t a l i s (Huds.) Baumg. FUR,BRI P e l t i g e r a membranacea (Ach.) Nyl. UEL P e l t i g e r a neopolydactyla (Gyeln.) Gyeln. BRI Pertusaria amara (Ach.) Nyl. UEL P l a t i s m a t i a glauca (L.) Culb. & Culb. UEL,PIT Ramalina farinacea (L.) Ach. UEL S t i c t a limbata (Sm.) Ach. BRI Thelotrema lepadinum Ach. UEL Vascular Plants Polypodium g l y c y r r h i z a D.C. Eat. ALL Appendix 3 Individual species response to height and i n c l i n a t i o n on the lower bole of Acer macrophyllum at each of the 5 study s i t e s . 214 S Q U H O M A L I A T R I C H O M A N O I D E S S Q U A N T I T R I C H I A C A L I F O R N I C A SQU PLAGIOMNIUM VENUSTUM 95-92-94" 89-91 8 6 - 8 8 " to 8 5 ' 1 J><** ^  SQU LEPRARIA MEMBRANACEA to 8 5 v 8 6 - 8 8 89-91 ° < < s 9 2 - 9 4 .5 2 1 " G ^ ^ 216 SQU METANECKERA MENZIESII SQU HOMALOTHECIUM FULGESCENS 2 1 7 SQU PORELLA CORDAEANA SQU NECKERA DOUGLASII FUR METANECKERA MENZIESII X 95+' 92-94 ' 89-91 8 6 - 8 8 ' to 8 5 ' 2 1 - " v G V ^ FUR LEPRARIA MEMBRANACEA .5 1 JW*^ 219 FUR HOMALOTHECIUM FULGESCENS FUR NECKERA DOUGLASII FUR DENDROALSIA ABIETINA 95+ 92-94' 89-9V 8 6 - 8 8 ' to 85 ' 1 FUR ZYGODON VIRIDISSIMUS to 85 ' v 86-88" ^ 89-91' <^s 92-94 .5 2 2 1 FUR CLAOPODIUM CRISPIFOLIUM FUR PORELLA CORDAEANA 222 FUR ISOTHECIUM STOLONIFERUM FUR PORELLA NAVICULARS UEL HOMALOTHECIUM FULGESCENS 8 6 - 8 8 to 8 5 .5 UEL METANECKERA MENZIESII to 8 5 v 8 6 - 8 8 89-91 <ss 9 2 - 9 4 95+ UEL CLAOPODIUM CRISPIFOLIUM 95+ ^ 92-94 \ 89-91 <xs 8 6 - 8 8 ^ to 8 5 1 2 G V A ^ ^ UEL LEPRARIA MEMBRANACEA to 8 5 ' ^ 8 6 - 8 8 ' \ s 89-91 ' <^ 9 2 - 9 4 95+" •5 UEL ISOTHECIUM STOLONIFERUM 95+ 92 -94 ' 89-91 8 8 ' % s 8 6 ro, to 8 5 ' 1 2 r ^ \ ^ •5 UEL ZYGODON VIRIDISSIMUS to 8 5 ' v 8 6 - 8 8 " %s 89-91 <xv 9 2 - 9 4 95+ .5 226 UEL HOMALOTHECIUM NUTTALLII UEL FRULLANIA TAMARISCI 227 UEL PORELLA CORDAEANA UEL NECKERA DOUGLASII PIT N E C K E R A DOUGLASI I 95+ ^ 92-94 \ 89-91 X 86-88' to 85' 2 1 - G ^ ^ PIT L E P R A R I A M E M B R A N A C E A to 85 ^ 86-88 \ 89-91 X 92-94 95+ .5 2 1 ~ G W ^ PIT HOMALOTHECIUM FULGESCENS X 95+' 92-94' 89-9V 86-88' to 85' .5 PIT METANECKERA MENZIESII to 85 86-88 89-91 92-94 95+ 1 ^ ^ 230 231 232 \ 233 234 BRI HOMALOTHECIUM FULGESCENS BRI NECKERA DOUGLASII 235 BRI ANTITRICHIA CALIFORNICA 95+ 92-94-89-91 ' <<^  8 6 - 8 8 " to 8 5 ' .5 2 ^0-1 : , G ^ ^ BRI GRAPHIS SCRIPTA to 8 5 v 8 6 - 8 8 ^ 89-91 <<s 9 2 - 9 4 95+ 

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