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Relation of the reproductive biology of plants to the structure and function of four plant communities Pojar, Jim 1974

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C- I THE RELATION OF THE REPRODUCTIVE BIOLOGY OF PLANTS TO THE STRUCTURE AND FUNCTION OF FOUR PLANT COMMUNITIES by JIM POJAR B . S c , U n i v e r s i t y of Minnesota, 1969 M.Sc. , U n i v e r s i t y of Minnesota, 1970 A THESIS SUBMITTED IN.PARTIAL FULFILMENT OF THE REQUIREMENTS FOR THE DEGREE OF DOCTOR OF PHILOSOPHY i n the Department of Botany We accept t h i s t h e s i s as conforming to the r e q u i r e d standard THE UNIVERSITY OF BRITISH COLUMBIA In presenting th is thes is in p a r t i a l fu l f i lment of the requirements fn an advanced degree at the Un ivers i ty of B r i t i s h Columbia, I a g r e e that the L ibrary sha l l make it f ree ly ava i lab le for reference and s t udy I fur ther agree that permission for extensive copying of th is t h e s i s for scho lar ly purposes may be granted by the Head of my Department or by his representat ives . It is understood that copying or p u b l i c a t i o n of th is thes is fo r f i n a n c i a l gain sha l l not be allowed without my writ ten pe rm i ss i on . Department of "\j> The Univers i ty of B r i t i s h Columbia Vancouver 8, Canada Date °\LaAX \ , V H *r Abstract F o u r p l a n t c o m m u n i t i e s o f s o u t h w e s t e r n B r i t i s h C o l u m b i a were s t u d i e d i n an a t t e m p t t o a n s w e r t h e f o l l o w i n g r e l a t e d q u e s t i o n s : (1) do c o m m u n i t i e s o f h a r s h p h y s i c a l e n v i r o n m e n t s e x h i b i t any c h a r a c t e r i s t i c p h y t o s o c i o l o g i c a l f e a t u r e s ? (2) a r e t h e r e any c o r r e l a t i o n s b e t w e e n e n v i r o n m e n t a l h a r s h n e s s and c e r t a i n s y n e c o l o g i c a l p r o p e r t i e s o f s u c h c o m m u n i t i e s ? (3) a r e s p e c i e s o f s u c h c o m m u n i t i e s s e l e c t e d f o r r e p r o d u c t i v e s p e c i a l i z a t i o n s t h a t t e n d t o r e d u c e t h e i r g e n e t i c v a r i a b i l i t y ? The f o u r c o m m u n i t i e s ( r e p r e s e n t i n g t h r e e t y p e s o f h e r b a c e o u s o r s e m i - s h r u b b y v e g e t a t i o n ) w e r e a s a l t m a r s h , two c o a s t a l sphagnum b o g s , and a s u b a l p i n e meadow. I n a n s w e r t o t h e f i r s t two q u e s t i o n s , t h e f i n d i n g s o f t h i s i n v e s t i g a t i o n i n d i c a t e t h a t : ( a ) s p e c i e s p o p u l a t i o n s t r u c t u r e becomes more a g g r e g a t e d as e n v i r o n m e n t a l h e t e r o g e n e i t y and p h y s i c a l s t r e s s i n c r e a s e , and l e s s a g g r e g a t e d as s u c c e s s i o n p r o c e e d s and i n t e r -s p e c i f i c c o m p e t i t i o n i n c r e a s e s . (b) i n t e r s p e c i f i c a s s o c i a t i o n and c o r r e l a t i o n , b o t h n e g a t i v e and p o s i t i v e , i n c r e a s e as e n v i r o n m e n t a l h e t e r o g e n e i t y a n d c o m p e t i t i o n i n c r e a s e . ( c ) l e v e l s o f p o l y p l o i d y w i t h i n c o m m u n i t i e s a p p e a r t o be c o r r e l a t e d w i t h e n v i r o n m e n t a l r i g o r ( b r o a d l y d e f i n e d ) . (d) the most abundant s p e c i e s w i t h i n a community are the most v a r i a b l e and presumably have the l a r g e s t niches ; niche s i z e and p o p u l a t i o n v a r i a b i l i t y decrease as i n t e r -s p e c i f i c competition i n c r e a s e s . (e) w i t h i n a community, e c o l o g i c a l d i s t i n c t i v e n e s s reduces i n t e r s p e c i f i c c o m p e t i t i o n ; communities under the l e a s t s t r e s s ( e s p e c i a l l y seasonal s t r e s s ) have the most e c o l o g i c a l l y d i s s i m i l a r 1 s p e c i e s . ( f ) dominance decreases as s p e c i e s d i v e r s i t y i n c r e a s e s , and species d i v e r s i t y i s roughly c o r r e l a t e d w i t h o v e r a l l environmental s e v e r i t y . In answer to the l a s t q u e s t i o n : (a) a l l f o u r communities are dominated by predominantly o u t c r o s s i n g s p e c i e s ; there i s no major s h i f t t o s e l f -p o l l i n a t i o n or apomixis i n any of the communities. (b) an index of p o t e n t i a l recombination was d e v i s e d , embodying a number of aspects of r e p r o d u c t i v e b i o l o g y , a c c o r d i n g to which there i s no s i g n i f i c a n t d i f f e r e n c e i n p o t e n t i a l recombination, on the average, between s p e c i e s of the f o u r d i f f e r e n t communities. Pl a n t communities and t h e i r c o n s t i t u e n t s p e c i e s both respond to e v o l u t i o n a r y f o r c e s , but more or l e s s independently, at d i f f e r e n t r a t e s , and o f t e n i n d i f f e r e n t or even op p o s i t e ways. Environmental s t r e s s has a powerful e f f e c t on the s t r u c t u r e and f u n c t i o n of p l a n t communities, but i n an e v o l u t i o n a r y sense there i s l i t t l e d i f f e r e n c e between normal (mesic, zonal) environments and extreme or azo n a l environments to an i n d i v i d u a l s p e c i e s . D i f f e r e n t s e l e c t i o n p r e s s u r e s have been o p e r a t i n g i n s a l t marshes, sphagnum bogs, and subalpine meadows, but the present study i n d i c a t e s t h a t , on the average, the r e s u l t a n t e v o l u t i o n a r y s t r a t e g i e s of the s p e c i e s of these communities are e q u i v a l e n t . TABLE OF CONTENTS Section Page I Introduction 1 II Description 5 A. Sampling methods 5 B. Sampling r e s u l t s 7 C. Vegetation of the four communities 10 S a l t marsh 10 Sphagnum bogs 14 Subalpine meadow 19 III Theory and Results 23 A. Pop u l a t i o n s t r u c t u r e of i n d i v i d u a l species (D/d index of aggregation) 23 B. I n t e r s p e c i f i c r e l a t i o n s h i p s 30 A s s o c i a t i o n 30 X 2 and Cole's index of a s s o c i a t i o n 30 Species c o n s t e l l a t i o n s 33 Corre latdon x: 40 C. Chromosome numbers and p o l y p l o i d y 51 D. Flowering phenology 6 9 E. P o l l i n a t i o n ecology 7 3 F. D i s p e r s a l ecology 115 G. Vapiability^'and-v'niche--w-id-th. 12 7 H. Niche d i f f e r e n t i a t i o n 136 I. Dominance, d i v e r s i t y , and s t a b i l i t y 147 J. Index of p o t e n t i a l recombination 159 v i . Section Page IV Summary, D i s c u s s i o n , and Conclusions 190 V L i t e r a t u r e Cited 202 Appendix 1. Species l i s t s 227 Appendix 2. Summary of some s t a t i s t i c s 234 Appendix 3. Summary of reproductive biology of each species 288 v i i . , LIST OF TABLES TABLE Page 1 Summary of vegetation sampling 6 2 Mean number of species per quadrat f o r the various quadrat s i z e s 8 3 Frequency, mean cover, and importance values of the vascular p l a n t species of the S a l t Marsh 10 4 Frequency, mean cover, and importance values of the vasc u l a r o p l a n t species of Wade's Bog 15 5 Frequency, mean cover, and importance values of the vascu l a r p l a n t species of Ogg's Bog 16 6 Frequency, mean cover, and importance values of the vascu l a r p l a n t species of B l a c k w a l l Meadow 21 7 D/d index of aggregation 2 5 8 Weighted average community D/d values 29 9 Summary of species i n t e r a c t i o n s 4 7 10 Chromosome numbers, p o l y p l o i d y , and importance values of species of the four study communities.... 60 11 Summary of l e v e l s of p o l y p l o i d y 6 6 12 Community mode of p o l l i n a t i o n as percentage of the f l o r a and vegetation 7 3 13 Outline of diaspore types 116 14 Percentages of diaspore types 117 15 Percentages of d i s p e r s a l methods; f l o r a / v e g e t a t i o n . 121 16 Morphological v a r i a t i o n i n nine grass species 131 17 E c o l o g i c a l u n i t characters 138 v i i i , TABLE Page 18 Number of s p e c i e s , two i n d i c e s of dominance, and an index of d i v e r s i t y f o r the f o u r study communities.. 149 19 Index o f P o t e n t i a l Recombination 175 20 Average community I.P.R.'s 183 21 Combinations of opposing r e g u l a t o r y f a c t o r s 185 22 R e s u l t s and i n d i c a t i o n s 191 LIST OF FIGURES Figure Page 1 M o d i f i e d s p e c i e s - a r e a curves •• 9 2 S a l t Marsh 12 3 S a l t Marsh 12 4 Deschampsia c e s p i t o s a 13 5 Wade's Bog. i 13 6 B l a c k w a l l Meadow 2 0 7 B l a c k w a l l Meadow 20 8 S a l t Marsh - s p e c i e s c o n s t e l l a t i o n 33 9 Wade's Bog - sp e c i e s c o n s t e l l a t i o n 35 10 Ogg's Bog - sp e c i e s c o n s t e l l a t i o n 36 11 B l a c k w a l l Meadow - s p e c i e s c o n s t e l l a t i o n 38 12 Frequency d i s t r i b u t i o n s of c o r r e l a t i o n c o e f f i c i e n t s 49 13 .Number:, of .var i a b l e p a i r s vs. Ar 49 14 Deschampsia c e s p i t o s a , n - 13 53 15 F e s t u c a r u b r a , n = 21 53 16 T r i g l o c h i n maritimum, n - 48 53 17 S a l i c o r n i a v i r g i n i c a , n = 18 53 18 P l a n t a g o m a r i t i m a , n - 6 53 Figure Page 19 J u n a u s b a l t i c u s 3 n = 40 53 20 C a v e x l y n g b y e i 3 n = 36 53 21 G l a u x m a v i t i m a 3 n = 15 53 22 P o t e n t i l l a p a c i f i c a 3 n - 14 53 23 A g v o s t i s e x a v a t a 3 n - - 14. 53 24 S t e l l a v i a h u m i f u s a 3 n = 13 53 25 T v i f o l i u m w o v m s k j o l d i i 3 n - 16 53 26 S c i v p u s c e v n u u s 3 n = 30 5 3 27 P u c c i n e l l i a p u m i l a 3 n = 21 53 28 S p e r g u l a r i a c a n a d e n s i s 3 n = 18 53 29 H o r d e u m b r a c h y a n t h e v u m 3 n - 14 53 30 L i l a e o p s i s o c c i d e n t a H s 3 n = 22 53 31 Myrica. g a l e 3 n - 48 54 32 A p a v g i d i u m b o v e a l e 3 n - 9 54 33 C a v e x o b n u p t a 3 n = 37 54 34 C a v e x p l u v i f l o v a 3 n - 26 54 35 A g v o s t i s a e q u i v a l v i s 3 n = 7 54 36 S a n g u i s o v b a o f f i c i n a l i s 3 n - 14 54 37 Ledum g v o e n l a n d i c u m 3 n = 13 54 38 V a c c i n i u m o x y c o c c u s 3 n = 24..• 54 39 D v o s e v a v o t u n d i f ' o l i a 3 n - 10 • 54 40 K a l m i a p o l i f o l i a 3 n = 12 54 41 Empetvum n i g v u m 3 n = 13 54 42 T v i e n t a l i s a v c t i c a 3 n = c a . ~42-44 54 43 C a v e x c a n e sc ens 3 n = 28 54 44 T o f i e l d i a g l u t i n o s a 3 n = 15 54 45 L i n n a e a b o v e a l i s 3 n = 16 54 Figure 46 R h y n c h o s p o r a a l b a 3 n - 13 47 V l a n t a g o m a o r o o a r p a 3 n - 12 48 G a u l t h e r i a s h a l l o n 3 n = 44 49 G e n t i a n a s o e p t r u m , nv - 13 50 C a l a m a g r o s t i s n u t k a e n s i s 3 n = 14 51 M a i a n t h e m u m d i l a t a t u m 3 n = 18 52 S a i r p u s c e s p i t o s u s 3 n = c a . 52 53 C o p t i s a s p l e n i f o l i a 3 n - 9 . . . . 54 C o p t i s t r i f o l i a 3 n - 9 55 J u n o u s s u p i n i f ' o r m i s 3 n = c a . 56 56 G e n t i a n a d o u g l a s i a n a 3 n = 13 57 V a c c i n i u m o v a t u m 3 n - 1 2 . . . . 58 V a o o i n i u m v i t i s - i d a e a 3 n = 12 59 V a o o i n i u m u l i g i n o s u m 3 n = 24 60 N e p h r o p h y l l i d i u m o r i s t a - g a l l i 3 n 61 E r i o p h o r u m p o l y s t a c h i o n 3 n = 30 62 C a r e x p a u o i f l o r a 3 n - c a . 37 63 V a l e r i a n a s i t o h e n s i s 3 n = c a . 48 64 L u p i n u s l a t i f o l i u s 3 n = c a . 48 65 F e s t u c a v i r i d u l a 3 n - 14 66 E r i g e r o n p e r e g r i n u s 3 n - 9 . . . 67 Anemone o c o i d e n t a l i s 3 2n - 16 68 E r y t h r o n i u m g r a n d i f l o r u m , 2n - 24 69 V o t e n t i l l a f l a b e l l i f o l i a 3 n - 14 70 V a o o i n i u m s o o p a r i u m 3 n = 12 71 C l a y t o n i a l a n o e o l a t a 3 2n = 16 72 A r e n a r i a o a p i l l a r i s 3 n - 11 F i g u r e 73 A n t e n n a v i a l a n a t a , n - 14.. 74 V e r o n i c a c u s i c k i i , n = 36.. 75 A g o s e r i s a u r a n t i a c a , n - 18 76 P h l e u m a l p i n u m 3 n = 1 4 . . . . 77 A r n i c a l a t i f o l i a 3 n = 19.. 78 L u z u l a h i t c h c o e k i i , n - 12 79' T h a l i c t r u m o c c i d e n t a l e 3 n - 28 80 A c h i l l e a m i l l e f o l i u m 3 n - 27 81 T r i s e t u m s p i c a t u m 3 n = 14... 82 E l y m u s g l a u c u s 3 n = 14 83 S i l e n e p a r r y i 3 n = 24 84 A r n i c a m o l l i s , n = c a . 38... 85 P e n s t e m o n p r o c e r u s 3 n = 8... 86 P o a c u s i c k i i 3 n - 14 87 S e n e c i o i n t e g e r r i m u s 3 n = 20 88 E i e r a c i u m g r a c i l e 3 n - 9.. 89 L u z u l a s p i c a t a 3 n = 1 2 . . . . 90 Sedum l a n c e o l a t u m 3 n = 8.. 91 C a s t i l l e j a m i n i a t a 3 n = 12 92 P e d i c u l a r i s b r a c t e o s a 3 n - 8 93 P h l o x d i f f u s a , n - 7 94 P o t e n t i l l a d i v e r s i f o l i a , n - c a . 95 C a r e x s p e c t a b i l i s ; n = c a . 42 96 E p i l o b i u m a l p i n u m , n = 1 8 . . . . 97 D e l p h i n i u m n u t t a l l i a n u m , n = 16 98 C a s t i l l e j a p a r v i f l o r a , n = 12 99 R a n u n c u l u s e s c h s c h o l t z i i , n - 16 x i i . Figure Page 100 S i b b a l d i a p r o c u m b e n s 3 n - 7 58 101 J u n o u s d r u m m o n d i i , n - c a . 60 58 102 E y d r o p h y l l u m f e n d l e r i 3 n = 18 58 103 S e n e c i o t r i a n g u l a r i s 3 n - 20 58 104 V a o o i n i u m d e l i c i o s u m 3 n - 24 58 105 M i t e l l a p e n t a n d r a 3 n - 7 58 106 L u e t k e a p e c t i n a t a , n - 9 58 107 P e d i c u l a r i s r a c e m o s a , n - 8 58 108 P h y l l o d o c e e m p e t r i f o r m i s 3 n = 24 58 109 V e r a t r u m v i r i d e 3 n - 16 58 110 V e r o n i c a w o r m s k j o l d i i 3 n - 9 58 111 F lower ing phenology 7 0 112 S p e r g u l a r i a c a n a d e n s i s , s e l f - p o l l i n a t i n g f l o w e r . . . . 75 113 D r o s e r a r o t u n d i f o l i a 3 s e l f - p o l l i n a t i n g f lower 75 114 P o t e n t i l l a f l a b e l l i f o l i a , bowl-shaped blossom 77 115 P l a n t a g o m a r i t i m a , s t r o n g l y protogynous, anemophil -ous f lowers 77 116a S a l i c o r n i a v i r g i n i c a 3 f lowers i n female s t a g e . . . . . . 82 116b S a l i c o r n i a v i r g i n i c a , f lowers i n male stage 82 117 J u n c u s b a l t i c u s , s t r o n g l y protogynous, anemophilous f lowers 8 3 118 S c i r p u s c e s p i t o s u s , s t r o n g l y protogynous, anemo-p h i l o u s f lowers 8 3 119a T h a l i c t r u m o c c i d e n t a l e , male f lowers 86 119b T h a l i c t r u m o c c i d e n t a l e , female f lowers 86 120 S a n g u i s o r b a o f f i c i n a l i s , f l y - p o l l i n a t e d f l o w e r s . . . . 87 121 T r i e n t a l i s a r c t i c a , f l y - p o l l i n a t e d f lowers 87 x i i i . F i g u r e Page 122 Coptis tvifolia, f l y - p o l l i n a t e d f lower 89 123 Veratrum viride , f l y - p o l l i n a t e d f lowers 89 124 Nephrophyllidium crista-galli, c a r r i o n f l y - p o l l i -nated f lower 91 125 Lysiehitum americanum, m e p h i t i c , c a r r i o n f l y - p o l l i -nated f lowers 91 126 Veronica c u s i o k i i , f l owers p o l l i n a t e d by s y r p h i d f l i e s 92 127 Valeriana sitchensis , "cornucopian" f lowers 92 128 Apargidium boreale , "cornucopian" f lowers 94 129 Erigeron p e r e g r i n u s , "cornucopian" f lowers 94 130 Glaux m a r i t i m a , a n t - p o l l i n a t e d f lowers 96 131 Delphinium n u t t a l i i a n u m , bombophilous f lowers 96 132a Gentiana sceptrum, view i n t o i n t e r i o r o f a bombo-p h i l o u s f lower 98 132b Gentiana s c e p t r u m , c l o sed f lowers i n r a i n y weather. 98 133 Lupinus latifolius, bombophilous f lowers w i t h p i s t o n mechanism of p o l l e n p r e s e n t a t i o n 100 134 Pedicularis b r a c t e o s a , bombophilous f lowers w i t h short-beaked galeas 10 0 135 Pedicularis r a c e m o s a , bombophilous f lowers w i t h t w i s t e d , long-beaked galeas 10 2 136 Pedicularis g r o e n l a n d i c a , bombophilous f lowers w i t h extremely long-beaked galeas 10 2 137 Gentiana douglasiana, whi te f lowers w i t h b lue nec tar guides 104 138 Vaccinium ovatum, u r c e o l a t e , l i g h t - p i n k f l o w e r s . . . . 104 Figure Page 139 V a c o i n i u m o x y c o c c u s }convergent f l o r a l e v o l u t i o n . . . . 106 140 D'ode oath eon j e f f r ^ y i 141a S i l e n e p a r r y i (day) 108 141b S i l e n e p a r r y i (n igh t ) 108 142 A g o s e r i s a u r a n t i a c a , b u t t e r f l y - p o l l i n a t e d f l o w e r s . . HO 143 Phlox d i f f u s a , b u t t e r f l y - p o l l i n a t e d f lowers 110 144 Castilleja mini at a, hummingb i rd -po l l ina ted f l o w e r s . 112 145 Anemone o o c i d e n t a l i s , w ind-d i spe r sed f r u i t s 112 146 Empetrum n i g r u m , i n b l a c k - b e r r i e d f r u i t 120 147 P l a n t a g o macrooarpa , f r u i t i n g sp ike 120 148 Carex lyngbyei , f r u i t i n g sp ike of t h i c k - w a l l e d p e r i g y n i a 123 149 Coptis a s p l e n i f o l i a , . f o l l i c l e s adapted f o r s p l a s h -cup d i s p e r s a l 123 150 I . V . v s . C V . f o r n ine spec ies of grasses 133 151 S t rength of i n t e r s p e c i f i c compe t i t i on v s . average e c o l o g i c a l d i s t i n c t i v e n e s s 146 152 Dominance - d i v e r s i t y curves 148 153 D . I . , N v s . H ' , X . 150 XV. Acknowiedgements I thank Dr. K.I. Beamish for her supervision, of this project-, and for reading, the thesis throughout, i t s production,, keeping, a c r i t i c a l eye and lo g i c a l r e i n on i t s developments Discussions with Drs. R, Cruden, R. Foreman, J. Maze, G. Person, P, Raven, W, Schofield, G. Scudder, and R, Taylor were helpful. Thanks are extended to Dr. G. Eaton and Mrs. D,. lauriente for writing computer programs,, and to H.E. Mill i r o n , Canada Dept. of Agriculture, for identifying some bumble bees. I much appreciated the use of equipment, belonging, to Drs. R. Foreman, V. Krajina, C. Marchant, and G. Scudder, and the housing and l o c a l guidance provided i n Tbfino by Mr. A. Guppy. My brother,, Jerry, did good work as f i e l d assistant in 1971, and took most of the photographs i n the thesis;. The f i e l d work was done with the cooperation of the National and Historic Parks Branch, Department of Indian Affairs and Northern Development-, Canada, and the Brit i s h Columbia Department of Recreation and Conservation, Parks Branch. The research was supported by the Committ.ee on Research, University of Brit i s h Columbia, Grant 219554 to Dr. K.I.. Beamish, by a Grant.-in-Aid from the Society of the Sigma Xi, by a Univ. of B r i t i s h Columbia Graduate fellowship, and by the Department, of. Botany, Univ. of Brit i s h Columbia.. I. INTRODUCTION 1 In t ima t ions of i n t e r r e l a t i o n s and c o r r e l a t i o n s between the r ep roduc t ive b i o l o g y of a s i n g l e spec ies and the type o f community i t grows i n have been s u r f a c i n g i n the recent gnomic l i t e r a t u r e of e v o l u t i o n , eco logy , and sy s t ema t i c s . As the f i e l d s o f taxonomy, eco logy , p o p u l a t i o n b i o l o g y , biogeography, and e v o l u t i o n a r y b i o l o g y , fo rmer ly separate mainstreams of whole organism b i o l o g y , impinge more and more upon one another , c e r t a i n m u l t i d i s c i p l i n a r y ques t ions are be ing posed. For example, i n v e s t i g a t i o n s by S a l i s b u r y (1942) , Grant (1958) , C a r l q u i s t (1966) , Mosquin (1966) , R o l l i n s (1967) , Ornduff (1969) , Wel l s (1969) , Whitehead (1969) , Kevan (1970) , Baker , Cruden, and Baker (1971) , Baker (1972) , and S a v i l e (1972) have d e a l t , e i t h e r d i r e c t l y or i n c i d e n t a l l y , w i t h the r e l a t i o n s h i p between c e r t a i n fea tures of the r ep roduc t ive b i o l o g y of angiosperms and the nature o f the p l a n t community. Other s t ud i e s have sought to i n t e g r a t e r ep roduc t i ve and p o p u l a t i o n b i o l o g y ( e g . , L e v i n and Anderson 19 70; McNaughton and Wolf 19 70; Bradshaw 1971, 19 72; Mosquin 1971; B e a t t i e , Breed love , and E h r l i c h 1973; and a number of papers by D . A . L e v i n and by^Levin d aM wH^Wv^Kerster, E c o l o g i c a l fea tures e i t h e r found or to be expected i n c e r t a i n types o f vege t a t i on have been e l u c i d a t e d by Gre ig -Smi th (19 64) , Kershaw (1964) , Smith and Cottam (1967) , Odum (1969) , Byer (1970), Mcin tosh (1970) , and McNaughton and Wolf (1970). Furthermore, Baker (1966a) , Harper (1967) , Langford and B u e l l (1969) , Mcintosh (19 70) , and Whi t t ake r and Woodwell (1972) have commented (wi th somewhat d i f f e r e n t i n t e r p r e t a t i o n s ) on p r o p e r t i e s 2 o f c o o r d i n a t i o n , i n t e r d e p e n d e n c e , and h o m e o s t a s i s i n p l a n t c o m m u n i t i e s , p r o p e r t i e s t h a t h a v e i m p o r t a n t e c o l o g i c a l and e v o l u t i o n a r y i m p l i c a t i o n s f o r b o t h t h e c o m m u n i t y and i t s s p e c i e s . M o s t o f t h e a b o v e p a p e r s c o n t r i b u t e d i n d i v i d u a l l y t o t h e i n i t i a l s t i m u l u s f o r t h i s s t u d y , and c o l l e c t i v e l y t o t h e r e a l i z a t i o n t h a t w h a t was n e e d e d was a s y n t h e t i c a p p r o a c h . T h e r e f o r e , t h e i n v e s t i g a t i o n h a s b e e n a d d r e s s e d t o t h r e e r e l a t e d q u e s t i o n s : (1) Do p l a n t c o m m u n i t i e s o f h a r s h p h y s i c a l e n v i r o n m e n t s e x h i b i t a n y c h a r a c t e r i s t i c " p h y t o s o c i o l o g i e a l f e a t u r e s ? ( 2 ) A r e t h e r e a n y c o r r e l a t i o n s b e t w e e n e n v i r o n m e n t a l h a r s h n e s s and c e r t a i n s y n e c o l o g i c a l p r o p e r t i e s o f s u c h c o m m u n i t i e s ? ( 3 ) A r e s p e c i e s o f s u c h c o m m u n i t i e s s e l e c t e d f o r r e p r o -d u c t i v e s p e c i a l i z a t i o n s t h a t ( a c c o r d i n g t o e s t a b l i s h e d e v o l u t i o n -a r y t h e o r y ) t e n d t o r e d u c e g e n e t i c v a r i a b i l i t y ? F o u r c o m m u n i t i e s r e p r e s e n t i n g t h r e e t y p e s o f h e r b a c e o u s o r s e m i - s h r u b b y v e g e t a t i o n ( s a l t m a r s h , sphagnum b o g , s u b a l p i n e meadow) u s u a l l y t h o u g h t o f a s o c c u r r i n g i n e x t r e m e p h y s i c a l e n v i r o n m e n t s w ere c h o s e n as s t u d y a r e a s , a n d t h e i r v e g e t a t i o n d e s c r i b e d by some o f t h e s t a n d a r d m e t h o d s o f d e s c r i p t i v e p l a n t e c o l o g y . The f o l l o w i n g c o n c e p t s o r d i s c i p l i n e s w e r e t h e n b r o u g h t t o b e a r upon t h e f i r s t t w o q u e s t i o n s : ( 1 ) s p e c i e s p o p u l a t i o n s t r u c t u r e ( 2 ) i n t e r s p e c i f i c r e l a t i o n s h i p s w i t h i n c o m m u n i t i e s a. ) a s s o c i a t i o n b. ) c o r r e l a t i o n ( 3 ) c o m m u n i t y l e v e l s o f p o l y p l o i d y ( 4 ) c o mmunity p a t t e r n s o f f l o w e r i n g p h e n o l o g y , p o l l i n a t i o n 3 eco logy , and d i s p e r s a l ecology (5) the theory of the n iche and c o r o l l a r i e s d e a l i n g w i t h n iche s i z e , p o p u l a t i o n v a r i a b i l i t y , and n iche d i f f e r e n t i a t i o n (6) dominance, d i v e r s i t y , and s t a b i l i t y . Regarding the t h i r d q u e s t i o n , Mosquin (19 66) has recommended t ha t " I f we wish to d i s c o v e r whether o r not d i f f e r e n t f l o r i s t i c or e c o l o g i c a l zones have s i g n i f i c a n t l y d i f f e r e n t l e v e l s of gene t i c v a r i a b i l i t y . . . then the r ep roduc t i ve f a c t o r s i n each spec ies of a r e g i o n or zone must f i r s t be i d e n t i f i e d and e v a l u a t e d . . . " The same l o g i c a p p l i e s to vege t a t i on types or i n d i v i d u a l communities. There fo re , i n a t tempt ing to answer the t h i r d q u e s t i o n , d e t a i l s of the s p e c i e s ' b reeding systems have been worked out and spec ies and community l e v e l s of p o t e n t i a l recombina t ion assessed. When I f i r s t s t a r t e d the i n v e s t i g a t i o n , I b e l i e v e d ( p a r t l y fo r the sake of argument) t h a t , i n order o f i n c r e a s i n g ha r sh -ness or r i g o r of the p h y s i c a l environment, the study communities should have been ranked: suba lp ine meadow, sphagnum bogs, s a l t marsh. Wi th t h i s r ank ing i n mind I expected c e r t a i n r e s u l t s . Some of the expec ta t ions were my own, others were e i t h e r s t a ted or i m p l i e d i n the l i t e r a t u r e . The i n i t i a l expec ta t ions are o u t l i n e d below ( d e t a i l s w i l l be g iven i n the appropr i a t e s ec t ions of the t h e s i s ) : (1) Species popu la t ions should be more aggregated as envi ronmenta l he te rogene i ty and p h y s i c a l s t r e s s i n c r e a s e , l e s s so as success ion proceeds and i n t e r s p e c i f i c compe t i t i on i n c r e a s e s . (2) The s t rengths of i n t e r s p e c i f i c a s s o c i a t i o n and c o r r e l a t i o n should inc rease as p h y s i c a l s t r e s s , environmental 4 h e t e r o g e n e i t y , and i n t e r s p e c i f i c c o m p e t i t i o n i n c r e a s e . ( 3 ) L e v e l s o f p o l y p l o i d y s h o u l d be c o r r e l a t e d more w i t h t h e h i s t o r i c a l t h a n t h e p h y s i c a l a s p e c t s o f e n v i r o n m e n t a l r i g o r . ( 4 ) The c o m m u n i t i e s u n d e r t h e most s t r e s s s h o u l d h a v e t h e l e a s t i n t e r s p e c i f i c c o m p e t i t i o n f o r f l o w e r i n g t i m e , p o l l i n a t i o n v e c t o r s , a n d d i s p e r s a l a g e n t s . ( 5 ) a.) The most a b u n d a n t s p e c i e s w i t h i n a c o m m u n i t y s h o u l d be t h e most v a r i a b l e ( h a v e t h e l a r g e s t n i c h e ) . b. ) A v e r a g e w i t h i n - c o m m u n i t y n i c h e s i z e and p o p u l a t i o n v a r i a b i l i t y s h o u l d d e c r e a s e w i t h i n c r e a s i n g c o m p e t i t i o n and l o w e r s t r e s s . c. ) W i t h i n a c o m m u n i t y , e c o l o g i c a l d i s t i n c t i v e n e s s s h o u l d r e d u c e i n t e r s p e c i f i c c o m p e t i t i o n ; t h e c o m m u n i t i e s u n d e r t h e l e a s t s t r e s s s h o u l d h a v e t h e most e c o l o g i c a l l y d i s s i m i l a r s p e c i e s . ( 6 ) S p e c i e s d i v e r s i t y w i l l be g r e a t e s t , and d o m i n a n c e o f t h e c o m m u n i t y by r e l a t i v e l y few s p e c i e s w e a k e s t , i n t h e c o m m u n i t i e s o f t h e most b e n i g n p h y s i c a l e n v i r o n m e n t s . ( 7 ) The most d i v e r s e c o m m u n i t i e s w i l l be t h e m o s t s t a b l e . ( 8 ) C o m m u n i t i e s o f r i g o r o u s p h y s i c a l e n v i r o n m e n t s w i l l be composed o f s p e c i e s w i t h r e p r o d u c t i v e s p e c i a l i z a t i o n s t e n d i n g t o w a r d g e n e t i c u n i f o r m i t y . F i n a l l y , I s h o u l d a d d t h a t , i n t h e f o l l o w i n g e x p o s i t i o n , c o m p a r i s o n s h a v e u s u a l l y b e e n c o n f i n e d t o t h e f o u r c o m m u n i t i e s u n d e r s t u d y , i n a s m u c h as t h e r e i s l i t t l e o r no p r e c e d e n t f o r much o f t h e i n v e s t i g a t i o n . II. DESCRIPTION 5 A. M e t h o d s o f v e g e t a t i o n s a m p l i n g . F o u r s i t e s w e r e s a m p l e d d u r i n g t h e s p r i n g a n d summer o f 19 71. A s a l t m a r s h and two sphagnum b o g s ( l a b e l l e d Wade's Bog and Ogg's Bog) w e r e c h o s e n i n t h e v i c i n i t y o f T o f i n o , on t h e w e s t c o a s t o f V a n c o u v e r I s l a n d , B r i t i s h C o l u m b i a . B o t h bogs a r e l o c a t e d i n P a c i f i c R i m N a t i o n a l P a r k . A s u b a l p i n e meadow s i t e ( B l a c k w a l l Meadow) was c h o s e n i n M a n n i n g P r o v i n c i a l P a r k , p a r t o f t h e e x t e n s i v e meadow v e g e t a t i o n t h a t s t r e t c h e s n o r t h o f B l a c k w a l l P e a k f o r a b o u t 15 m i l e s t o N i c o m e n L a k e . The v e g e t a t i o n o f a p a r t i c u l a r s i t e i s h e r e a f t e r r e f e r r e d t o as a p l a n t c o m m u n i t y . No i m p l i c a t i o n as t o a c o m m u n i t y ' s o b j e c t i v e e x i s t e n c e as a d i s c r e t e v e g e t a t i o n a l u n i t i s i n t e n d e d , i n v i e w o f t h e w i d e s p r e a d c o n t r o v e r s y o v e r t h e c o m m u n i t y c o n c e p t . S i m i l a r l y , g r o u p i n g s o f s p e c i e s w i t h i n a c o mmunity may be t e r m e d a s s o c i a t i o n s , b u t w i t h t h e same r e s e r v a t i o n s . A l l c o m m u n i t i e s w e r e s a m p l e d w i t h q u a d r a t s l o c a t e d by 2 r andom number p a i r s . C e n t r a l l y n e s t e d w i t h i n e a c h 1 m q u a d r a t , 2 2 a 50K-50 cm ( 0 . 2 5 m ) and a 10x10 cm ( 0 . 0 1 m ) q u a d r a t w e r e a l s o u s e d . P r e s e n c e a n d c o v e r e s t i m a t e s w e r e r e c o r d e d f o r e a c h v a s c u l a r p l a n t s p e c i e s i n e a c h q u a d r a t . An i m p o r t a n c e v a l u e ( I . V . ) f o r e a c h s p e c i e s was c a l c u l a t e d a s t h e sum o f r e l a t i v e f r e q u e n c y and r e l a t i v e c o v e r ( K u r a m o t o and B l i s s 1 9 7 0 ) . I n a d d i t i o n , e a c h c o m m u n i t y was s a m p l e d by a c r i s s - c r o s s o f b e l t t r a n s e c t s 30.5 cm ( 1 f t ) w i d e . S p e c i e s o c c u r r e n c e i n c o n t i g u o u s 3 0.5 cm s q u a r e q u a d r a t s was r e c o r d e d a l o n g t h e s e t r a n s e c t s . The 6 sampling scheme i s summarized i n Table 1. TABLE 1. Summary of v e g e t a t i o n sampling. Dimensions of Number Length and Sum of sampling area of number of t r a n s e c t S i t e (m) a quadrats t r a n s e c t s (m) le n g t h (m) S a l t Marsh 244x61 70 183 (2) 457.5 30.5 (3) Wade's Bog 122x61 50 122 (1) 244 61 (2) Ogg's Bog 76x23 77 79.3 (1) 217 53x23 b 46 (1) 23 (4) B l a c k w a l l 122x61 50 122 (1) 244 Meadow 61 (1) aThe corresponding areas are a l l 8000-12000 m (0.8-1.2 ha). DTwo r e c t a n g u l a r areas at an angle to one another, with a common corner. A complete s p e c i e s l i s t f o r each s i t e can be found i n Appendix 1. Voucher specimens of each s p e c i e s are on f i l e i n the Herbarium o f the U n i v e r s i t y o f B r i t i s h Columbia. A l l s p e c i e s names and a u t h o r i t i e s are as i n Hi t c h c o c k et a l . (1955-1969), except where noted. B. Sampling r e s u l t s . 7 The number o f . s p e c i e s per quadrat f o r a l l quadrat s i z e s i s l i s t e d i n Table 2. An i n t e r e s t i n g fea ture o f these data i s tha t 2 at the sma l l e s t quadrat s i z e (0.01 m ) , the mean number of spec ies i s about the same f o r a l l four communities. This suggests tha t the lower l i m i t of the number o f species tha t can be packed i n t o a givensspace_isaapproximate.ly-.the--. same:: f o r the s a l t marsh, both sphagnum bogs, and the subalp ine meadow. The g rea te r o v e r a l l " c a r r y i n g capac i t y " of the suba lp ine meadow and bogs i s a f u n c t i o n of a g rea te r degree of .change i n species compos-i t i o n as quadrat s i z e i n c r e a s e s . Th i s change r e f l e c t s i n par t the g rea te r h a b i t a t and micro topographic he te rogene i ty o f the meadow and bogs. The s i t u a t i o n i s analogous (on a much sma l l e r s c a l e ) to the inc rease i n between-habi ta t or be ta species d i v e r s i t y tha t r e s u l t s from an inc reased change i n spec ies compos i t ion a long environmental g rad ien t s (Whi t taker 1969, 1970a, 1972). The mod i f i ed spec i e s - a r ea curves o f F igure 1 i n d i c a t e tha t 2 the 1 m quadrats a c c u r a t e l y es t imate the t o t a l spec ies compos i t ion o f the communit ies , s ince the curves l e v e l o f f 2 between the 0.45 and 1 m quadrat s i z e s . As quadrat s i z e i n c r e a s e s , the number of d i f f e r e n t species added w i t h s i z e becomes p r o g r e s s i v e l y lower . Spec ies -a rea curves u s u a l l y p l o t 8 TABLE 2. Mean number of species per quadrat f o r the various 2 quadrat s i z e s . The 1.00, 0.25, and 0.01 m quadrats 2 were randomly l o c a t e d ; the 0.45 and 0.09 m quadrats are t r a n s e c t segments. l x l 1.5x0.3 0.5x0.5 0.3x0.3 0.1x0.1 1.00 0.45 0.25 0.09 0.01 S a l t Marsh x = 7\ 5 6.5 6.1 4.7 4.1 Wade's Bog 11. 5 11.2 9.5 7.6 4.7 Ogg's Bog 14. 4 13. 5 11.1 7.7 4.5 B l a c k w a l l 15.6 15.2 12 .1 8.8 4.6 Meadow Quadrat dimensions (m) Quadrat area Cm ) the t o t a l "number of species v s . area (Cain 1938 ; Kershaw 1 9 6 4 ) ; I have chosen to p l o t average number of species vs. area as a more accurate i n d i c a t i o n of the comparative community taxonomic d i v e r s i t y . F i g . 1. M o d i f i e d s p e c i e s - a r e a c u r v e s . C. D e s c r i p t i o n o f communities. 10 S a l t marsh The f l o r a of the marsh i s sma l l (18 spec ies ) but v a s c u l a r p l an t cover averages about 8 8%. The vege t a t i on i s dominated ( i n the present d i s c u s s i o n , importance value i s taken to be a measure o f dominance) by grasses and g r a s s - l i k e herbs ( F i g s . 2 & 3 ) . The dominant species i n the s a l t marsh i s Desoh amp si a oespitosa ( F i g . 4) , which has the h ighes t average cover of any s p e c i e s , 28.1% (Table 3 ) . Trigloohin maritimum i s the commonest spec ies (100% frequency) but w i t h an average cover of 6.8% i s not as concent ra ted as Desohampsia. Sub-dominant species are F e s t u o a r u b r a v a r . l i t t o r a l i s , S a l i o o r n i a v i r g i n i o a 3 P l a n t a g o m a r i t i m a , J u n c u s b a l t i c u s , C a r e x l y n g b y e i , and G l a u x m a r i t i m a (Table 3 ) . TABLE 3. Frequency, mean cove r , and importance va lues o f the v a s c u l a r p l a n t spec ies of the Sa l t2Marsh . The values were c a l c u l a t e d from da£a from 1 m quadra ts ; values for the 0.25 and 0.01 m quadrats were a l s o c a l c u l a t e d but are not g iven here s i n c e they agree w e l l w i t h the f i g u r e s below. Species Frequency Mean cover Importance value (acronym) (%) (%) (I.V.) D e s o h a m p s i a o e s p i t o s a 85.7 28.1 38.6 (DCS) F e s t u o a r u b r a (FRU) 70.0 19.2 24.5 T r i g l o o h i n m a r i t i m u m 100.0 6.8 21.0 (TMA) TABLE 3. (Continued) 11 Species (acronym) Frequency Mean cover (%) (%) Importance value ( I . V . ) S a l i c o r n i a v i r g i n i c a 67. 1 11. 7 17 . 8 (SPA) P l a n t a g o m a r i t i m a (PMA) 61. 4 12. 6 16. 9 J u n c u s b a l t i c u s (JBA) 50. 0 17 . 9 16. 8 Carex lyngby.ei..(CLY) 74. 3 5. 3 14. 3 Glaux m a r i t i m a (GMA) 62. 8 7. 8 13. 9 Pot e n t i l l a p a c i f i c a (PPA) 27 . 1 11. 9 7. 2 A g v o s t i s e x a r a t a (AEX) 24. 3 14. 3 7. 1 S t e l l a r i a h u m i f u s a (SHU) 38. 6 2. 0 6 . 0 T r i f o l i u m w o r m s k j o l d i i 15. 7 8. 3 3 . 5 (TWO) S c i r p u s o e r n u u s (SCE) 24 . 3 0. 5 3. 3 P u e o i n e l l i a p u m i l a (PPU) 18 . 6 1. 2 2. 7 S p e r g u l a r i a c a n a d e n s i s 14. 3 0. 7 2. 0 (SCA) D i s t i e h l i s s p i o a t a (DSP) 10. 0 4. 6 1. 8 H o r d e u m b r a c h y a n t h e r u m 7. 1 10. 7 1. 8 (HBR) L i l a e o p s i s o c c i d e n t a l i s 2. 8 0. 7 0. 4 (LOC) T o t a l p l a n t cove r : 88.3% I know of no such d e s c r i p t i o n o f s a l t marsh vege t a t i on of the no r th P a c i f i c Nor th American coas t . Chapman (19 60) and MacDonald (1969) g ive cu r so ry reviews o f western Nor th American s a l t marshes. Hanson (19 61) has desc r ibed s a l t marsh v e g e t a t i o n a long the coas t o f western A l a s k a ; Ca lde r and T a y l o r (19 68) g i v e spec ies l i s t s and v e g e t a t i o n notes f o r the s a l t marshes o f the Queen C h a r l o t t e I s l a n d s . Johannessen (1961, 1964) and F r a n k l i n and Dyrness (1969) l i s t key species and g ive b r i e f e c o l o g i c a l resume's of s a l t marshes i n Washington and Oregon. 12 cu F i g . 2. S a l t Marsh, mid-May, 1971. F i g . 3. T i p of S a l t Marsh, e a r l y May, 1971, from 20 m up a S i t k a spruce. L i g h t - c o l o r e d t u f t s to the l e f t of the bleached l o g are o f Desohampsia oespitosa; dark green masses are o f Junaus b a l t i c u s . A long the margins of the mud f l a t s are c i r c u l a r clumps of Puooinellia p u m i l a 3 S a l i o o r n i a v i r g i n i o a 3 and T r i g l o o h i n m a r i t i m u m . 13a/ F i g . 4. Desohampsia oespitosa, dominant s p e c i e s of the S a l t Marsh. F i g . 5. View from i n t e r i o r of Wade's Bog, e a r l y May, 1971. Stunted t r e e s are mostly Pinus oontovta; l i g h t - c o l o r e d sedge leaves belong mainly to Cavex obnupta. 14 C a l i f o r n i a ' s s a l t marshes have been more i n t e n s i v e l y s t u d i e d , most no tab ly by Purer (1942) , Hinde (1954) , Vogl (1966) , and Barbour and Davis (1970). By i n t e r p o l a t i o n , the Tof ino marsh seems s i m i l a r t o o ther h i g h s a l i n i t y s a l t marshes a long the nor th P a c i f i c coas t of Nor th Amer ica . U n l i k e s a l t marshes of eas te rn North America and the southern C a l i f o r n i a c o a s t , there i s no Spartina here to form the lowermost zone of v e g e t a t i o n . In the Tof ino a r e a , Cavex lyngbyei i s the commonest species at the lowermost l e v e l s , e s p e c i a l l y a long the banks o f dra inage channels . At the mud f l a t margins of the marsh, Salicornia virginica, Triglochin maritimum, and Puccinellia pumila form l a r g e , more or l e s s c i r c u l a r clumps 0.3 to 3.0 m i n diameter (F igure 3D.'' Johannessen (19 64) main ta ins tha t such clumps i n d i c a t e tha t the marsh i s expanding r a p i d l y . Sphagnum bogs Both bogs a r e , f o r the most p a r t , dominated by the same s p e c i e s , but to v a r y i n g degrees ( c f . Tables 4 and 5 ) . In g e n e r a l , the v e g e t a t i o n o f Ogg's Bog has a h igher p r o p o r t i o n o f woody spec ies than Wade's Bog (45% v s . 28%). Most n o t i c e a b l e are the inc reased dominances of Myrica gale ( I . V . of 36.1 v s . 4 . 9 ) , T h u j a p l i c a t a (16.2 v s . 3 . 4 ) , L i n n a e a b o r e a l i s (4.0 v s . 1 .2 ) , and Gaultheria shallon (3.3 v s . 0.2) i n Ogg's Bog. Vascu l a r p l a n t cover i s about 5 3% i n Ogg's Bog and 6 3% i n Wade's Bog. Bryophyte ground cove r , due p r i m a r i l y to Sphagnum s p p . , i s 60-70% and f a i r l y cont inuous i n both bogs, so tha t t o t a l p l an t 15 TABLE 4. Frequency, mean cove r , and importance va lues of the v a s c u l a r p l an t species of Wade's Bog. Species Frequency Mean cover Importance va lue (acronym) (%) (%) ( I . V . ) C a r e x p l u r i f l o r a (CPL) 96. 0 14. 3 30. 1 A p a r g i d i u m b o r e a l e (ABO) 92. 0 13. 2 27 . 2 A g r o s t i s a e q u i v a l v i s 98. 0 4. 8 15 . 9 (AAE) C a r e x o b n u p t a (GOB) 80 . 0 7. 0 15 . 9 S a n g u i s o r b a o f f i c i n a l i s 84. 0 5. 9 15 . 1 (SMI) K a l m i a p o l i f o l i a (KPO) 98. 0 3 . 6 14. 0 V a c c i n i u m o x y c o c c u s (VOX) 98. 0 3 . 1 13. 3 C a r e x c a n e s c e n s (CCA) 48. 0 10. 1 11. . 9 D r o s e r a r o t u n d i f o l i a 88. 0 2. 5 11. , 2 (DRO) Ledum g r o e n l a n d i c u m (LGR) 70. 0 2. 8 9. ,1 T r i e n t a l i s a r c t i c a (TAR) 96. 0 0. 4 8. , 9 E m p e t r u m n i g r u m (END 26. , 0 7. 1 5. , 2 M y r i c a g a l e (MGA) 28 . , 0 5. , 7 4. , 9 T o f i e l d i a g l u t i n o s a (TGL) 48 . , 0 0. , 5 4, . 6 T h u j a p l i c a t a (TPL) 22. , 0 4. , 3 3 . .4 P i n u s c o n t o r t a (PCO) 20. . 0 4. . 7 3 . . 2 G e n t i a n a d o u g l a s i a n a 14. . 0 0. .1 1, .2 (GDO) L i n n a e a b o r e a l i s (LBO) 12. . 0 1. ,1 1. . 2 M a i a n t h e m u m d i l a t a t u m 10, .0 0, .5 0, . 9 (MDI) R h y n c h o s p o r a a l b a (RAL) 6, . 0 2, . 5 0, . 7 V a c c i n i u m v i t i s - i d a e a 4, . 0 0, .5 0 . 4 (VVI) S c i r p u s c e s p i t o s u s (SCS) 2, . 0 5. . 0 0 . 3 J u n c u s s u p i n i f o r m i s (JOR) 2 . 0 1, . 0 0 . 2 B l e c h n u m s p i c a n t (BSP) 2. . 0 0 .5 0 . 2 V a c c i n i u m u l i g i n o s u m 2 . 0 0 . 5 0 . 2 (VUL) G a u l t h e r i a s h a l l o n (GSH) 2 . 0 0 .3 0 . 2 G e n t i a n a s c e p t r u m (GSC) 2 . 0 0 . 3 0 . 2 C o p t i s a s p l e n i f o l i a (CAS) 2 . 0 0 .1 0 . 2 T o t a l p l an t cover : 63.1% 16 TABLE 5. Frequency, mean cover , and importance va lues of the v a s c u l a r p l a n t species of Ogg's Bog. Species Frequency Mean cover Importance va lue (acronym) (%) (%) ( I . V . ) Myvioa g a l e (MGA) 88 . 3 18. 1 36. 1 A p a v g i d i u m b o v e a l e (ABO) 77 . 9 8. 9 18. 4 T h u j a p l i c a t a (TPL) 70. 1 8. 6 16 . 2 C a v e x o b n u p t a (COB) 76. 6 5. 8 13. 7 C a v e x p l u v i f l o v a (CPL) 85. 7 3. 5 11. 6 A g v o s t i s a e q u i v a l v i s 79. 2 3. 5 10 . 7 (AAE) S a n g u i s o v b a o f f i c i n a l i s 93. 5 1. 6 9. 3 (SMI) Ledum g v o e n l a n d i o u m (LGR) 76. 6 1. 9 8. 1 V a o o i n i u m o x y o o o o u s (VOX) 81. 8 1. 2 7 . 5 D r o s e v a v o t u n d i f o l i a 76. 6 0. 6 6 . 1 (DRO) K a l m i a p o l i f o l i a (KPO) 57 . 1 1. 8 5 . 8 Empetvum n i g v u m (END 37 . 7 4. 1 5 . 5 T v i e n t a l i s a v c t i o a (TAR) 74. 0 0. 2 5 . 4 C a v e x o a n e s o e n s (CCA) 41. 5 2. ,7 5 .  0 T o f i e l d i a g l u t i n o s a (TGL) 61. 0 0. ,4 4 . , 7 L i n n a e a b o v e a l i s (LBO) 45 . ,4 1. , 0 4. , 0 R h y n o h o s p o v a a l b a (RAL) 23. .4 5. . 2 3 . , 9 P l a n t a g o m a c v o o a v p a (PMC) 37. ,7 1. , 7 3 . , 8 G a u l t h e v i a s h a l l o n (GSH) 37 . ,7 0. . 9 3 . . 3 B l e o h n u m s p i c a n t (BSP) 23. .4 1. . 0 2. . 6 G e n t i a n a s o e p t v u m (GSC) 33. . 8 0, .4 2 , . 5 C a l a m a g v o s t i s n u t k a e n s i s 18. . 2 2. . 3 2. . 0 (CNU) . 0 M a i a n t h e m u m d i l a t a t u m 27 , . 3 0, .2 2, (MDI) S c i v p u s o e s p i t o s u s (SCS) 15. .6 1 . 9 1 . 6 C o p t i s a s p l e n i f o l i a (CAS) 14 . 3 1 . 5 1 . 4 C o p t i s t v i f o l i a (CTR) 16 .9 0 .7 1 . 4 J u n o u s s u p i n i f o v m i s (JOR) 7 . 8 3 . 6 1 . 1 D e s o h a m p s i a o e s p i t o s a 9 .1 1 . 8 0 . 9 (DCS) 0 P i n u s o o n t o v t a (PCO) 7 . 8 2 .1 . 8 L y c o p o d i u m o l a v a t u m ( L C D 6 .5 1 . 3 0 . 6 G e n t i a n a d o u g l a s i a n a 7 . 8 0 . 3 0 . 6 (GDO) 0 V a o o i n i u m o v a t u m (VOV) 6 . 5 1 . 0 . 6 V a o o i n i u m v i t i s - i d a e a 5 . 2 0 . 6 0 .4 (VVI) 0 'Cornus- u n a l a s o h k e . n s i s 3 . 9 1 . 5 . 4 (CUN) 17 TABLE 5. CContinued) Species Frequency (acronym) (%) Mean cover (%) Importance value ( I . V . ) Vaccinium uliginosum 3.9 0.9 0 . 3 (VUL) 0 . 3 Juniperus communis (JCO) 2 . 6 3.0 Nephrophyllidium crista- 2 . 6 2.0 0 . 3 galli (FCG) 0 . 2 Lycopodium inundatum 2.6 1.1 (LIN) 0.1 Eriophorum polystachion 1.3 2.0 (EPO) Cavex pauciflora (CPA) 1.3 2.0 0.1 Lysichitum americanum 1.3 0.3 0.1 (LAM) T o t a l p l an t cover : 5 3.4% cover exceedstlO0%. Evergreen shrubs and h a l f - s h r u b s , cyperaceous spec ies and the sphagnum moss g ive both bogs t h e i r c h a r a c t e r i s t i c physiognomy ( F i g . 5 ) . Wade (1965) has p r e v i o u s l y c l a s s i f i e d the vege t a t i on of Wade's Bog. The sampling area i n t h i s study would f a l l most ly w i t h i n the Oxycoccus - Sphagnum papillosum and Carex pluriflora a s s o c i a t i o n s as mapped by Wade (1965, F i g 6 ) . Ogg's Bog con ta ins more of the Myrica gale and Vaccinium vitis-idaea v a r i a n t s and both sampling areas have very l i t t l e of the Scirpus - Sphagnum mendocinum a s s o c i a t i o n . Rigg (1925, 1940) , Osvald (1933) , Hansen (1947) , and Heusser (1960) have desc r ibed the vege t a t i on and sketched the h i s t o r y of a number o f sphagnum bogs o f no r th P a c i f i c Nor th Amer ica . A p p l i c a t i o n o f genera l p r i n c i p l e s o f bog development 18 o u t l i n e d by Gorham (1957) and Heinselman (1963) to the d e s c r i p -t i o n s of the above authors and to my own and Wade's observa t ions suggests tha t the two study bogs, and bogs i n genera l i n the T o f i n o - U c l u e l e t a r ea , are s u c c e s s i o n a l l y j u v e n i l e . The very shal low peat depths (averaging no more than 1 m) support t h i s sugges t ion , as does the y o u t h f u l age o f Wade's Bog, e s t a b l i s h e d as approximately 400190 years by rad ioca rbon d a t i n g (Wade 1965). The bogs probably have been formed by p a l u d i f i c a t i o n (swamping) o f p o o r l y d ra ined c o a s t a l f o r e s t , r a t h e r than by g r a d u a l , c e n t r i p e t a l f i l l i n g - i n o f water bod ie s . Wade (19 65) cons idered the recent format ion o f a h ighe r l i p o f land now covered by S i t k a spruce (Piaea sitchensis) and the format ion of an u n d e r l y i n g hardpan to be the l i k e l i e s t b a r r i e r s to the drainage of the c o a s t a l t e r r a c e upon which the bogs are perched. Success ion i n the bogs appears to be toward development o f a h i g h moor or r a i s e d bog o f sphagnum moss, sedges , and e r icaceous shrubs w i t h f u r t h e r bogaexpansion at the expense o f the surrounding wet f o r e s t . Of the two bogs, Wade's Bog seems to be more advanced i n t h i s succes s ion . The average peat depth i n Wade's Bog i s 1 m (Wade 19 65) ; i n Ogg's Bog, 0.5 m. Average t r e e cover i s a l s o l e s s i n Wade's Bog, as are the I . V . ' s o f species such as L i n n a e a b o v e a l i s C o r n u s u n a l a s c h k e n s i s 3 G a u l -t h e r i a s h a l l o n 3 and L y a o p o d i u m a l a v a t u m , which are more t y p i c a l o f f o r e s t undergrowth than sphagnum bogs. Furthermore, the dominat ion of Ogg's Bog by Myriaa gale (Table 5) i s very s i g n i f i c a n t , s ince Myriaa grows p o o r l y i n h i g h l y a c i d i c h i g h moor c o n d i t i o n s ( K r a j i n a , pe r sona l communication). Subalpine meadow 19 The f l o r a of B l a c k w a l l Meadow i s the r i c h e s t of the four communit ies , w i t h 45 spec ies present i n the sample. The v e g e t a t i o n i s co-dominated by three s p e c i e s : Valeriana sitch-e n s i s ( I . V . of 2 4 . 9 ) , F e s t u o a v i r i d u l a ( 2 4 . 3 ) , and L u p i n u s l a t i f o l i u s ( 2 1 . 8 ) . E r i g e r o n p e r e g r i n u s . Anemone o c c i d e n t a l i s m and Potentilla flabellifolia are secondary co-dominants (Table 6) . At the he igh t of the shor t growing season, the community c o n s i s t s :of -.a,, lushc mixture „of _ showy-flowered forbscand more inconspicuous g ra s se s , sedges, and wood rushes ( F i g s . 6 S 7 ) . Vege ta t i on cover approximates 93%; the bare s o i l areas are due main ly to the a c t i v i t i e s of a sma l l pocket gopher tha t tunne l s below the snow dur ing the w i n t e r , j u s t beneath the s o i l su r face . In con t r a s t to many o ther mountainous a reas , the subalpine vege t a t i on o f nor th P a c i f i c Nor th America has been l i t t l e s tud ied by p l an t e c o l o g i s t s u n t i l recen t yea r s . Fonda and B l i s s (1969) and Kuramoto and B l i s s (1970) have desc r ibed communities i n the suba lp ine of the Olympic Mountains of Washington. B r i n k (1959, 1964), Arche r (1963), and Brooke, al. (1970) have s t ud i ed the suba lp ine v e g e t a t i o n of the southwestern Coast Range of B r i t i s h Columbia. Eady (1971) d i scussed the a l p i n e - s u b a l p i n e zone o f B ig White Mounta in , i n the Okanagan Highland of southern B r i t i s h Columbia. Douglas (1972) has desc r ibed i n d e t a i l the suba lp ine p lan t communities of the western Nor th Cascades, Washington. Comparison o f these s tud ie s leads me to conclude tha t the B l a c k w a l l Meadow vege ta t i on most c l o s e l y resembles the 20 ou F i g . 6. B l a c k w a l l Meadow, e a r l y August , 19 72. F i g . 7. B l a c k w a l l Meadow, e a r l y Augus t , 19 72. In both p i c t u r e s , the whi te c o l o r i s p r i m a r i l y due to i n f l o r e s c e n c e s o f V a l e r i a n a sitchensis and ^mop-tops" or seed heads of Anemone Occidentalis ; the b l u e , to L u p i n u s l a t i f o l i u s ; the y e l l o w , to P o t e n t i l l a f l a b e l l i f o l i a 3 A r n i c a l a t i f o l i a 3 and A r n i c a m o l l i s . 21 d r i e r V a l e r i a n a s i t c h e n s i s - C a s t i l l e j a e l m e r i a s s o c i a t i o n of Eady (1971) , w i t h some a f f i n i t i e s to the mois te r V. sitchensis - Veratrum viride a s s o c i a t i o n of Douglas (1972). Th i s i n t e r -mediate c o n d i t i o n . i s to be expected , s ince B l a c k w a l l Meadow i s s i t u a t e d on the gen t l e west s lope of a nor th - sou th r i d g e a long the phys iog raph ic break between the east and west f l a n k s of the Cascade Range i n the Manning Park a rea . TABLE 6. Frequency, mean cover , and importance va lues o f the v a s c u l a r p l an t spec ies of B l a c k w a l l Meadow. Species Frequency Mean cover Importance va lue (acronym) (%) <%) ( I . V . ) V a l e r i a n a s i t c h e n s i s 76.0 24.6 24.9 (VSI) F e s t u c a v i r i d u l a (FVI) 100.0 16.7 24.3 L u p i n u s l a t i f o l i u s (LLA) 96.0 14.6 21.8 E r i g e r o n p e r e g r i n u s (EPE) 86.0 7.5 12.4 Anemone o c c i d e n t a l i s 80.0 8.0 11.9 (AOC) P o t e n t i l l a f l a b e l l i f o l i a 90.0 4.8 10.4 (PFL) E r y t h r o n i u m g r a n d i f l o r u m 7 0.0 2.0 7.0 (EGR) V a c c i n i u m s c o p a r i u m (VSC) 42.0 9.3 6.9 C l a y t o n i a l a n c e o l a t a 82.0 1.5 6.5 (CLA) A r e n a r i a c a p i l l a r i s (ACA) 72.0 2.2 6.3 A n t e n n a r i a l a n a t a (ALA) 54.0 4.8 6.2 V e r o n i c a c u s i c k i i (VCU) 54.0 3.1 5.3 A g o s e r i s a u r a n t i a c a (AAU) 60.0 1.5 4.8 P h l e u m a l p i n u m (PAL) 64.0 1.0 4.8 A r n i c a l a t i f o l i a (ALF) 50.0 2.7 4.7 L u z u l a h i t c h c o c k i i (LHI) 56.0 1.8 4.6 T h a l i c t r u m o c c i d e n t a l e 14.0 18.6 3.7 (TOO A c h i l l e a m i l l e f o l i u m 42.0 1.7 3.5 (AMI) T r i s e t u m s p i c a t u m (TSP) 44.0 0.8 3.2 22 TABLE 6. (Continued) Species Frequency Mean cover Importance va lue (acronym) (%) (%> ( I . V . ) C a r e x r o s s i i (CRO) E l y m u s g l a u o u s (EGL) S i l e n e p a r r y i (SPA) A r n i c a m o l l i s (AMO) P e n s t e m o n p r o c e r u s (PPR) P o a c u s i c k i i (PEP) S e n e c i o i n t e g e r r i m u s (SIN) E i e r a c i u m g r a c i l e (HGR) L u z u l a s p i c a t a (LSP) Sedum l a n c e o l a t u m (SLA) C a s t i l l e j a m i n i a t a (CMI) P e d i c u l a r i s b r a c t e o s a (PBR) P h l o x d i f f u s a (PDI) P o t e n t i l l a d i v e r si f o l i a (PDV) C a r e x s p e c t a b i l i s (CSP) E p i l o b i u m a l p i n u m (EAL) D e l p h i n i u m n u t t a l l i a n u m (DNU) C a s t i l l e j a p a r v i f l o r a (CAL) R a n u n c u l u s e s c h s c h o l t z i i (RES) S i b b a l d i a p r o c u m b e n s (SPI M i c r o s t e r i s g r a c i l i s (MGR) J u n c u s d r u m m o n d i i (JDR) H y d r o p h y l l u m f e n d l e r i (HFE) S e n e c i o t r i a n g u l a r i s (STR) V a c c i n i u m d e l i c i o s u m (VDE) S e l a g i n e l l a w a l l a c e i (SWA) T o t a l p l a n t cover : 9 3.3% 44. 0 0 . 5 2.8 10 . 0 17 . 6 2.5 28.0 1.5 2.2 22.0 2.8 2.1 24. 0 2.3 2.1 26.0 1.0 1.9 24. 0 1.4 1.9 20.0 1.9 1.7 20.0 0.4 1.4 18. 0 0 . 5 1.2 16 . 0 1.1 1.2 12. 0 1.0 0.9 .-8:0 3.8 0.8 " 8 o 2.4 0.7 1 4v0 8.5 0.6 8.0 0 . 3 0.5 6.0 2.0 0.5 6 . 0 0.8 0.4 6.0 0.6 0.4 ) 4.0 1.3 0. 3 4.0 0.7 0.3 2.0 3.0 0.2 2.0 3 . 0 0.2 2.0 2.0 0.2 2.0 2.0 0.2 2.0 0.5 0.1 I I I . THEORY AND RESULTS 23 A . P o p u l a t i o n s t r u c t u r e of i n d i v i d u a l s p e c i e s : ,D/d index o f aggrega t ion . The d i s t r i b u t i o n o f i n d i v i d u a l s of the same species i n a p a r t i c u l a r p l a n t community g e n e r a l l y i s non-random or aggregated (Gre ig -Smi th 1964; Kershaw 1964) , even i n apparen t ly homo-geneous v e g e t a t i o n . An aggregated p o p u l a t i o n s t r u c t u r e can r e s u l t from environmental he te rogene i ty o r mosa ic i sm, i n t e r -s p e c i f i c i n t e r a c t i o n s , and spec ies morphology (vege t a t i ve apomixis or v i c i n i s m i n seed d i s p e r s a l can l ead to clumped d i s t r i b u t i o n s ) . The non-randomness can take the form of a clumped ("contagious") d i s t r i b u t i o n of i n d i v i d u a l s , or an even ( " r egu la r " ) d i s t r i b u t i o n (Kershaw 1964). One measure of aggregat ion i s the D/d index of McGinnies ( i n C u r t i s and Mcin tosh 1950). I have c a l c u l a t e d t h i s index f o r each species i n the present study from presence-absence da ta f o r 'l-i.^-m- 'and" 0; 9-m segments o f the 0.3-m wide b e l t t r a n s e c t s , a f t e r the method o f Smith and Cottam (1967). The a c t u a l d e n s i t y (D) was c a l c u l a t e d by c o n s i d e r i n g each 0.3-m square w i t h i n each 1.5- or 0.9-m segment to be a p o t e n t i a l i n d i v i d u a l ; t h u s , the maximum d e n s i t y p o s s i b l e per 1.5-m segment was 5, and per 0.9-m segment 3. Frequency va lues were computed as the percentage o f a l l p o s s i b l e 1.5- or 0.9-m segments occupied by a p a r t i c u l a r s p e c i e s . The expected d e n s i t y (d) va lues cou ld then be determined from a b i n o m i a l curve (see Gre ig -Smi th 1964, Table 6 ) . The d va lue thus obta ined was the d e n s i t y (number o f 0.3-m 24 quadrats occupied per segment) t ha t would be expected i f the p o p u l a t i o n were a random one. U s u a l l y the expected dens i t y was l e s s than the a c t u a l d e n s i t y , g i v i n g a D/d value g rea te r than 1 and i n d i c a t i n g aggregat ion (Table 7 ) . The s i z e o f the D/d value g ives some i n d i c a t i o n of the type and degree of aggreg-a t i o n . A D/d grea te r than 1 i n d i c a t e s a contagious d i s t r i b u t i o n ; a D/d l e s s than 1 i n d i c a t e s a r e g u l a r d i s t r i b u t i o n . The on ly species to show markedly r e g u l a r d i s t r i b u t i o n s (both v i a 0.9-m segments) were T v i g l o c h i n m a v i t i m u m and F e s t u o a v i r i d u l a , the commonest spec ies i n the s a l t marsh and suba lp ine meadow, r e s p e c t i v e l y . U n f o r t u n a t e l y , there i s no way to determine the s i g n i f i c a n c e o f the D/d index ' d e v i a t i o n from u n i t y (Beals 1968). I t has been suggested (Gre ig -Smi th 1964) tha t success ion i n vege t a t i on i s accompanied by an inc rease i n the s i z e of spec ies aggregat ions concomitant w i t h a decrease i n the i n t e n s i t y o f aggrega t ion . One would expec t , t h e n , e a r l y s u c c e s s i o n a l vege t a t i on to be composed of spec ies w i t h , on the average, h ighe r D/d values than spec ies o f more advanced s u c c e s s i o n a l or c l imax communities. Regular d i s t r i b u t i o n s r e f l e c t e d by lower D / d ' s are sugges t ive o f a n e g a t i v e , probably compe t i t i ve i n t e r -a c t i o n between s p e c i e s , and would be expected i n more s t a b l e , c l imax communities (Beals 19 68) . To compare the average degree of non-randomness i n the study communities I have used the r a t i o o f the sum of observed d e n s i t i e s to the sum of expected d e n s i t i e s ( i . e . , Ed , / _ d ) , as recommended by C u r t i s and Mcin tosh (1950). Both observed and expected d e n s i t i e s are the same as those used i n the c a l c u l a t i o n of the D/d index . Note tha t t h i s r a t i o i s weighted i n favor of 25 the more abundant s p e c i e s , which i s an a t t r a c t i v e f ea tu re . R a t i o s fo r both segment s i z e s f o r a l l four communities are presented i n Table 8. TABLE 7. D/d index of aggrega t ion . Species D/d (0.9-m segments) D/d (1.5-m segments) S a l t Marsh D e s o h a m p s i a o e s p i t o s a F e s t u o a r u b r a T r i g l o o h i n m a r i t i m u m S a l i o o r n i a v i r g i n i o a P l a n t a g o m a r i t i m a J u n o u s b a l t i o u s G l a u x m a r i t i m a P o t e n t i l l a p a o i f i o a A g r o s t i s e x a r a t a S t e l l a r i a h u m i f u s a T r i f o l i u m w o r m s k j o l d i i S c i r p u s c e r n u u s P u o o i n e l l i a p u m i l a S p e r g u l a r i a c a n a d e n s i s D i s t i o h l i s s p i c a t a H o r d e u m b r a o h y a n t h e r u m L i l a e o p s i s o c o i d e n t a l i s 1.80 1.98 0. 77 1. 87 1. 2. 1. 1. 1, 1. 2. 1. 60 22 93 67 78 86 11 62 1. 55 72 53 08 1.39 mean 65 77 11 52 , 03 ,46 ,53 , 07 ,42 ,46 ,83 1.90 1.93 2.26 3.97 3.10 1.88 C a r e x p l u r i f l o r a A p a r g i d i u m b o r e a l e A g r o s t i s a e q u i v a l v i s C a r e x o b n u p t a S a n g u i s o r b a o f f i c i n a l i s K a l m i a p o l i f o l i a V a o o i n i u m o x y o o o o u s C a r e x c a n e s o e n s D r o s e r a r o t u n d i f o l i a Ledum g r o e n l a n d i o u m - 1. 76 mean = 2 .77 - 2.53 range: 1.11 • g 1.00 1. 31 1.29 1.61 0.92 1. 21 1.23 1.67 1.13 1.53 1.13 1.38 0.98 1. 24 1.47 1.62 1.03 1.38 1.29 1.74 TABLE 7. (Continued) 26 Species D/d (0.9-m segments) D/d (1.5-m segments) T r i e n t a l i s a r c t i o a 1 .16 1 . 53 E m p e t r u m n i g r u m 1 .63 1 .93 M y r i o a g a l e 1 .67 2 .19 T o f i e l d i a g l u t i n o s a 1 .15 1 .29 T h u j a p l i c a t a 1 . 63 1 . 81 P i n u s e o n t o r t a 1 . 39 1 . 82 G e n t i a n a d o u g l a s i a n a 1 .28 1 .29 L i n n a e a b o r e a l i s 1 .96 1 . 97 M a i a n t h e m u m d i l a t a t u m 1 .50 1 .60 R h y n o h o s p o r a a l b a 1 . 57 2 . 71 J u n o u s s u p i n i f o r m i s 2 . 33 2 .67 C o p t i s t r i f o l i a 1 .0 0 1 .11 mean = 1.35 mean = 1 range: 0. 92 - 2.33 range: 1. 11 Ogg's Bog M y r i o a g a l e 0. 96 1. 18 A p a r g i d i u m b o r e a l e 1. 20 1. 71 T h u j a p l i o a t a 1. 35 1. 81 C a r e x o b n u p t a 1. 50 2. 02 Carex p l u r i f l o r a 1. 10 1. 47 A g r o s t i s a e q u i v a l v i s 1. ,30 1. 62 S a n g u i s o r b a o f f i c i n a l i s 1. 13 1. ,47 Ledum g r o e n l a n d i c u m 1. ,26 1. 65 V a o o i n i u m o x y o o c o u s 1. ,43 1. , 83 D r o s e r a r o t u n d i f o l i a 1. ,38 1. ,79 K a l m i a p o l i f o l i a 1. . 27 1. ,60 E m p e t r u m n i g r u m 1. ,75 2. ,16 T r i e n t a l i s a r c t i o a 1. ,42 2. , 07 C a r e x c a n e s c e n s 1. ,41 1. ,69 T o f i e l d i a g l u t i n o s a 1. ,25 1. ,53 L i n n a e a b o r e a l i s 1. , 53 2. ,02 R h y n o h o s p o r a a l b a 2. .02 2. .85 P l a n t a g o m a c r o c a r p a 1. .75 2. .14 G a u l t h e r i a s h a l l o n 1. , 3 6 1. ,70 B l e c h n u m s p i o a n t 1. .37 1. .60 G e n t i a n a s o e p t r u m 1, .39 1. .40 C a l a m a g r o s t i s n u t k a e n s i s 1, .71 2, . 08 M a i a n t h e m u m d i l a t a t u m 1. .45 1, .77 S o i r p u s c e s p i t o s u s 1, . 59 1, .92 C o p t i s a s p l e n i f o l i a 1, . 98 2, .73 C o p t i s t r i f o l i a 1, .86 2, .07 J u n o u s s u p i n i f o r m i s 2, . 07 2, .90 D e s o h a m p s i a o e s p i t o s a 1, .33 1, . 94 TABLE 7. (Continued) 27 Species D/d (0.9-m segments) D/d (1.5-m segments) P i n u s c o n t o r t a L y c o p o d i u m c l a v a t u m G e n t i a n a d o u g l a s i a n a V a o o i n i u m o v a t u m V a o o i n i u m v i t i s - i d a e a V a o o i n i u m u l i g i n o s u m J u n i p e r u s c o m m u n i s 1.43 1.79 1.64 1.28 2.04 1.90 1.28 63 76 13 mean 1.50 range: 0.9 6 - 2.0 7 B l a c k w a l l Meadow 1. 31 2. 58 1. 94 1.68 mean = 1.88 range: 1.18 - 2.9 0 V a l e r i a n a s i t c h e n s i s 1. 80 2. 05 F e s t u c a v i r i d u l a 0. 63 1. 15 L u p i n u s l a t i f o l i u s 1. 12 1. 36 E r i g e r o n p e r e g r i n u s 1. 03 1. 46 Anemone o o c i d e n t a l i s 1. 30 1. 68 P o t e n t i l l a f l a b e l l i f o l i a 0. 97 1. 37 E r y t h r o n i u m g r a n d i f l o r u m 1. 19 1. 53 V a o o i n i u m s c o p a r i u m 1. 71 2. 29 C l a y t o n i a l a n c e o l a t a 1. 28 1. 82 A r e n a r i a o a p i l l a r i s 1. 55 2. 28 A n t e n n a r i a l a n a t a 1. 52 2. 04 V e r o n i c a c u s i c k i i 1. 37 1. 86 A g o s e r i s a u r a n t i a c a 1. 06 1. ,16 P h l e u m a l p i n u m 1. .01 1. 08 A r n i c a l a t i f o l i a 1. ,30 1. , 37 L u z u l a h i t c h c o c k i i 1. ,32 1. ,67 T h a l i c t r u m o c c i d e n t a l e 1. ,88 2. , 74 A c h i l l e a m i l l e f o l i u m 1. , 35 1. , 68 T r i s e t u m s p i c a t u m 1. .15 1. , 29 C a r e x r o s s i i 1. .29 1. ,42 E l y m u s g l a u c u s 1, .93 3. . 09 S i l e n e p a r r y i 1, .23 1, .25 A r n i c a m o l l i s 1. .60 2, . 53 P o a c u s i c k i i 1. . 01 1, .11 S e n e c i o i n t e g e r r i m u s 1 .30 1, . 53 H i e r a c i u m g r a c i l e 1. .70 1. .96 L u z u l a s p i c a t a 1 .16 1 . 24 Sedum l a n c e o l a t u m 1 .25 1 .48 C a s t i l l e j a m i n i a t a 1 .25 1 .37 P e n s t e m o n p r o c e r u s 1. . 55 2 .07 P e d i c u l a r i s b r a c t e o s a 1 . 58 1 . 52 P o t e n t i l l a d i v e r s i f o l i a 1 .40 1 . 53 TABLE 7. (Continued) 28 Species D/d (0.9-m segments) D/d (1.5-m segments) E p i l o b i u m a l p i n u m 1.69 1.65 R a n u n c u l u s e s c h s c h o l t s i i 1.31 1.62 S i b b a l d i a p r o c u m b e n s 1.62 2.08 M i o r o s t e r i s g r a c i l i s 2.00 2.08 S e n e c i o t r i a n g u l a r i s 1.65 2.28 V a c c i n i u m d e l i c i o s u m 1.90 3.07 S e l a g i n e l l a w a l l a c e i 2.06 1.79 V e r a t r u m v i r i d e 1.69 2.13 mean = 1.4 2 mean = 1.7 7 range: 0.6 3 - 2.0 6 range: 1.08 - 3.0 9 Wade's Bog has the l e a s t aggregated v e g e t a t i o n (Table 8 ) . Th i s i s expected , s ince t h i s bog appears to be nearest the c l imax s t a t e f o r the c o a s t a l sphagnum bog community t ype . At the o ther extreme, the S a l t Marsh has by f a r the h ighes t average D/d v a l u e . Perhaps t h i s i s because the r i g o r o u s p h y s i c a l environment of the s a l t marsh imposes f a i r l y d i s c r e t e h a b i t a t zona t ion (promoting aggregat ion) and p laces a premium on mere s u r v i v a l , d i m i n i s h i n g i n t e r s p e c i f i c compe t i t i ve e f f e c t s , e s p e c i a l l y i n the p ioneer mud f l a t v e g e t a t i o n ( c f . C l a rke and Hannon 1970, 1971). I t cou ld a l s o be due i n par t t o the morphology o f the marsh s p e c i e s , many o f which have ex tens ive vege t a t i ve spread. Ogg's Bog has r e l a t i v e l y s t r o n g l y aggregated v e g e t a t i o n , w h i l e tha t of B l a c k w a l l Meadow i s on ly weakly aggregated. Both communities have d i v e r s e , m o s a i c - l i k e m i c r o -topograph ies . The fac t tha t Ogg's Bog has a h igher average D/d 29 than B l a c k w a l l Meadow r e f l e c t s , I t h i n k , a much h igher degree of i n t e r s p e c i f i c compe t i t i on i n the suba lp ine meadow (see Sec t . I I I - B ) and probable advanced s u c c e s s i o n a l ' s t a t u s . TABLE 8. Weighted average community D/d v a l u e s . a 0.9-m segments, 1.5-m segments, S i t e r a t i o = r a t i o = S a l t Marsh 1.39 1.97 Wade's Bog 1.12 1.44 Ogg's Bog 1.25 1.69 B l a c k w a l l Meadow 1.14 1.53 A s i m p l e , unweighted average was a l s o computed f o r each community, and the r e s u l t s were e q u i v a l e n t . However, i n a l l cases the weighted average was l e s s than the unweighted, i n d i c a t i n g tha t the r a r e r spec ies had h igher D / d ' s (were more aggregated) , which seems reasonable . C lose r examinat ion o f Table 8 r e v e a l s tha t a l l four communities e x h i b i t more in tense aggrega t ion at 1.5-m i n t e r v a l s , as would be expected merely from the inc rease i n i n t e r v a l l eng th from 0.9 m. However, the change i n segment s i z e does not a f f e c t a l l s i t e s e q u a l l y . In p a r t i c u l a r , the s a l t marsh species show a compara t ive ly g rea te r inc rease i n aggrega t ion at the 1.5-m l e v e l . T h i s may be i n d i c a t i v e of a secondary sca l e of p a t t e r n i n the S a l t Marsh. That i s , i n d i v i d u a l s o f the same spec ies tend to occur toge ther w i t h i n a r a d i u s of at l e a s t 0.9 m i n a l l communit ies; i n Ogg's Bog and the subalp ine meadow, and e s p e c i a l l y i n the s a l t marsh, there i s a tendency fo r the 30 i n d i v i d u a l s to form l a r g e r clumps. Th i s i s i n agreement w i t h B r e r e t o n ' s (19 71) f i n d i n g s t h a t , at l e a s t i n s a l t marsh s u c c e s s i o n , spec ies are i n i t i a l l y randomly d i s t r i b u t e d but l a t e r become more aggregated and e v e n t u a l l y the aggregat ions inc rease i n s i z e . B. I n t e r s p e c i f i c r e l a t i o n s h i p s . A s s o c i a t i o n I n t e r s p e c i f i c a s s o c i a t i o n can be detec ted by c o n s t r u c t i o n 2 of a 2x2 cont ingency t a b l e and c a l c u l a t i o n of x va lues based on j o i n t occurrence of p a r t i c u l a r spec ies p a i r s i n sample quadrats (Kershaw 1964). T h i s has been done f o r a l l p o s s i b l e species p a i r s i n each community, p rov ided each spec ies occur red 2 i n at l e a s t f i v e sampling u n i t s (see Appendix 2 ) . The x va lue shows whether the d i f f e r e n c e between the observed and expected number of quadrats o f co-occurrence i s s i g n i f i c a n t o r no t . The 2 s i g n of the x va lue i n d i c a t e s whether the a s s o c i a t i o n i s p o s i t i v e or n e g a t i v e . 2 Since c a l c u l a t i o n o f x ± s based on q u a l i t a t i v e presence/ absence da t a , the type and l e v e l of a s s o c i a t i o n i s dependent on 2 quadrat s i z e (Gre ig -Smi th 1964; Kershaw 19 64) . Therefore x values have been c a l c u l a t e d f o r f i v e d i f f e r e n t quadrat s i z e s the three random quadrat s i z e s and the 1.5- and 0.9-m t r ansec t segments. I t i s hoped tha t t h i s approach w i l l more v a l i d l y detect t rends o f a s s o c i a t i o n and i n d i c a t e s ca l e s o f p a t t e r n i n the communit ies. 31 2 In most cases , the r e s u l t s o f the x t e s t s are c o n s i s t e n t throughout the d i f f e r e n t quadrat s i z e s . Occas iona l changes i n s i g n from one quadrat s i z e to another may be viewed as e f f ec t s o f quadrat s i z e and/or number. C o l e ' s index of i n t e r s p e c i f i c a s s o c i a t i o n (Cole 1949; H u r l b e r t 19 69) was a l s o determined fo r a l l spec ies p a i r s . C o l e ' s 2 index g ives e s s e n t i a l l y the same i n f o r m a t i o n as a x value but reduces the values to a range from +1 to - 1 . These r e s u l t s are a l so presented i n Appendix 2. A s s o c i a t i o n as a s t a t i s t i c can suggest p o s s i b l e causes of s p e c i e s ' d i s t r i b u t i o n a l p a t t e r n s . H i g h l y nega t ive a s s o c i a t i o n s may i n d i c a t e d i s s i m i l a r h a b i t a t requirements o r compe t i t i ve e x c l u s i o n or a l l e l o p a t h y . H i g h l y p o s i t i v e a s s o c i a t i o n s may i n d i c a t e s i m i l a r h a b i t a t requi rements , absence of s t rong c o m p e t i t i o n , or environmental m o d i f i c a t i o n by one species to the advantage of another (Kershaw 1964; Smith and Cottam 1967; Gooda l l 1970). Byer (1970) main ta ins tha t s t rong p o s i t i v e and negat ive a s s o c i a t i o n i s c h a r a c t e r i s t i c o f the vege t a t i on o f heterogene'ous h a b i t a t s , and of extreme h a b i t a t s i n which s m a l l environmental d i f f e r e n c e s may be c r i t i c a l . Fur thermore, i t has been suggested (Gre ig -Smi th 1964; Kershaw 1964) tha t success ion i s accompanied by a decrease i n i n t e r a c t i o n between s p e c i e s . 2 t h i s should be r e f l e c t e d i n l e s s he te rogene i ty of x va lues i n more s t a b l e or s u c c e s s i o n a l l y advanced vege t a t i on the converse should a l s o h o l d . A s s o c i a t i o n - S a l t Marsh 32 I n t e r s p e c i f i c a s s o c i a t i o n i n the s a l t marsh i s marked, as can be seen i n Appendix 2 and F i g . 8. F i g . 8 i l l u s t r a t e s , the two main spec ies groupings . The aggregat ion dominated by D e s c h a m p s i a c e s p i t o s a , F e s t u c a r u b r a , J u n c u s b a l t i c u s , and Glaux maritima occurs on the h i g h e r , densely vegetated l e v e l s o f the marsh, whereas the group dominated by Salicornia v i r g i n i c a 3 C a r e x l y n g b y e i , and P l a n t a g o m a r i t i m a i s more c h a r a c t e r i s t i c of the lower l e v e l mud f l a t s . Desohampsia, C a r e x , P l a n t a g o , S a l i c o r n i a , S t e l l a r i a h u m i f u s a , and S c i r p u s cernuus e x h i b i t moderate p o s i t i v e a s s o c i a t i o n w i t h some species of both groupings . Triglochin maritimum i s a more or l e s s ub iqu i tous spec ies i n t h i s marsh, o c c u r r i n g so f r equen t ly as to f a l l i n n e i t h e r g rouping . There are o c c a s i o n a l i n c o n s i s t e n c i e s i n the r e s u l t s o f the 2 X t e s t s . For example, i n the species p a i r Carex lyngbyei* Plantago m a r i t i m a , s t rong p o s i t i v e a s s o c i a t i o n i s i n d i c a t e d by quadrat s i z e s l x l , 0 . 5 x 0 . 5 , and 1.5x0.3 m (Appendix 2 ) . At the l e v e l of the 0.3x0.3 m quadra ts , however, s t rong nega t ive a s s o c i a t i o n i s i n d i c a t e d . Perhaps t h i s i s i n d i c a t i v e o f compe t i t i on tha t was masked i n the l a r g e r quadrats but showed up i n the sma l l e r quadrat . In c o n t r a s t , the p a i r Juncus balticus Scirpus cernuus e x h i b i t s s i g n i f i c a n t nega t ive a s s o c i a t i o n v i a l x l m and 0 .5x0.5 m quadrats but s t rong p o s i t i v e a s s o c i a t i o n v i a 0.3x0.3 m quadrats (Appendix 2 ) . In t h i s case , the l a rge number of co-occurrences i n the 0.3x0.3 m quadrats may have been r e q u i r e d t o manifest a p o s i t i v e a s s o c i a t i o n on ly m i l d l y 33<v F i g . 8. S a l t Marsh spec ies c o n s t e l l a t i o n . The e l l i p s e s are shaded rough ly p r o p o r t i o n a l to the species importance v a l u e . Each l i n e represen ts a l e v e l of s i g n i f i c a n t p o s i t i v e a s s o c i a t i o n . That i s to say: there are three l i n e s i f , fo r one quadrat s i z e , P = 0 .005; two l i n e s i f P = 0 .01 ; one l i n e i f P = 0 .05. Since there are f i v e d i f f e r e n t quadrat s i z e s ( three random quadrats p lus two t r a n s e c t segments), 15 l i n e s are the maximum p o s s i b l e . The diagram does not i n d i c a t e negat ive a s s o c i a t i o n . A E X - Agrostis exarata C L Y - Carex lyngbyei D C S - Desohampsia cespitosa D S P - Distichlis spicata FRU - Festuca rubra G M A - Glaux maritima H B R - Hordeum braohgantherum J B A - Juncus balticus L O C - Lilaeopsis occidentalis P M A - Plantago maritima P P A - Potentilla pacifica P P U - Puccinellia pumila S C A - Spergularia canadensis S C E - Scirpus cernuus S H U - Stellaria humifusa S P A - Salicornia virginica T M A - Trigloohin maritimum T W O - Trifolium wormskjoldii 34 i n d i c a t e d at the 1.5x0.3 m l e v e l and missed e n t i r e l y by the random quadra ts . A s s o c i a t i o n - Sphagnum bogs As was po in ted out e a r l i e r i n Sec t . I I - C , the two sphagnum bogs are qu i t e s i m i l a r i n f l o r a and v e g e t a t i o n . Th i s s i m i l a r i t y i s borne out i n F i g s . 9 and 10. Both bogs are dominated by a f a i r l y l a rge c o n s t e l l a t i o n o f species tha t i nc ludes Cavex p l u r i f l o r a , C. o b n u p t a , A p a r g i d i u m . b o r e a l e , V a o o i n i u m o x y o o o o u s , A g r o s t i s a e q u i v a l v i s , K a l m i a p o l i f o l i a , Ledum g r o e n l a n d i o u m 3 D r o s e r a r o t u n d i f o l i a , T r i e n t a l i s a r c t i o a , and T o f i e l d i a glutinosa as important s p e c i e s . This aggregat ion inco rpora t e s both the O x y o o o o u s - Sphagnum p a p i l l o s u m and Ledum - Sphagnum capillaoeum a s s o c i a t i o n s o f Wade (1965). Ogg's Bog inc ludes more of the spec ies group dominated by T h u j a p l i c a t a 3 E m p e t r u m n i g r u m , and L i n n a e a b o r e a l i s than does Wade's Bog. This i s an a s s o c i a t i o n o f h i g h , f a i r l y dry hummocks and conta ins bog f o r e s t elements such as Thuja, Linnaea, Pinus c o n t o r t a , M a i a n t h e m u m d i l a t a t u m , C o p t i s a s p l e n i f o l i a , B l e c h n u m spicant, and Gaultheria shallon. Ogg's Bog a l s o con ta ins two a s s o c i a t i o n s tha t are unimportant i n the sample area of Wade's Bog. Myrioa gale dominates a shrubby a s s o c i a t i o n of l a r g e extent i n Ogg's Bog. Al though i t i s a n i t r o g e n - f i x i n g spec ies (Bond 1951, 1967; Rodr iguez-Bar rueca 19 68) , Myrioa grows so densely as to have negat ive or weakly p o s i t i v e a s s o c i a t i o n s w i t h most of the other bog species (see Appendix 2 ) . Another group of spec ies tha t i s f a i r l y common i n Ogg's Bog i s dominated by 3 5 o-F i g . .9. Wade's Bog, species c o n s t e l l a t i o n . A A E - Agrostis aequivalvis A B O - Apargidium boreale C C A - Carex canescens C O B - Carex obnupta C P L - Carex pluriflora D R O - Drosera rotundifolia ENI - Empetrum nigrum G D O - Gentiana douglasiana K P O - Kalmia polifolia L G R - Ledum groenlandicum L B O - Linnaea borealis M D I - V aianthemum dilatatum M G A - V y r i c a gale P C O - Pinus contorta R A L - Rhynchospora alba S M I - Sanguisorba officinali T P L - Thuja plicata T G L - Tofieldia glutinosa T A R - Trientalis arctica V O X - teccinium oxycoccus [CPU K P O k L G R G D O P C O COB SMI C C A 3 6 ox F i g . 10. Ogg 1s Bog, s p e c i e s c o n s t e l l a t i o n . 3 U 37 C a r e x o a n e s c e n s 3 P l a n t a g o m a c r o c a r p a , R h y n c h o s p o r a a l b a , G e n t i a n a s c e p t r u m , J u n c u s s u p i n i f o r m i s , and S c i r p u s c e s p i t o s u s and grows i n areas of sha l low peat tha t are under s tanding water f o r much of the year . As suggested i n Sec t . I I - C , Ogg's Bog i s probably i n an e a r l i e r stage of success ion than Wade's Bog. P e r u s a l o f Appendix 2 and F i g s . 9 and 10 i n d i c a t e s tha t Ogg's Bog i s much more heterogeneous i n i n t e r s p e c i f i c a s s o c i a t i o n than i s Wade's 2 Bog; i . e . , there are more s i g n i f i c a n t x va lues (both p o s i t i v e and nega t ive) per spec ies and a h igher average abso lu te va lue 2 of these x ' s i - n Ogg's Bog than i n Wade's Bog (Table 9 ) . The g rea te r he te rogene i ty (and a l s o the g rea te r number of spec ies ) r e f l e c t s the g rea te r v a r i e t y of m i c r o h a b i t a t s a v a i l a b l e i n Ogg's Bog, and a l s o a f f i rms the sugges t ion of Gre ig -Smi th (19 64) and Kershaw (1964) tha t success ion i s accompanied by a decrease i n species i n t e r a c t i o n s . A s s o c i a t i o n - Subalpine meadow There i s a l s o s t rong i n t e r s p e c i f i c a s s o c i a t i o n i n B l a c k w a l l Meadow (Appendix 2, F i g . 1 1 ) . Four main spec ies groupings are apparent ( F i g . 1 1 ) . There i s a l a r g e number of spec ies of low importance tha t tend t o occur on dry m i c r o s i t e s w i t h i n the meadow, g e n e r a l l y where the s o i l i s sha l low and/or very w e l l d r a i n e d . This aggregat ion i s dominated by Antennaria l a n a t a and A r e n a r i a c a p i l l a r i s . P e n s t e m o n p r o c e r u s , S e n e c i o i n t e g e r r i m u s , A g o s e r i s a u r a n t i a c a , A c h i l l e a m i l l e f o l i u m , Seolum l a n c e o l a t u m , A r n i c a m o l l i s , and C a s t i l l e g a m i n i a t a are important 3 8 cu F i g . 11 . Blackwall Meadow, species cons t e l l a t i o n . 39 f o r b s , and Carex r o s s i i 3 L u z u l a s p i c a t a 3 T r i s e t u m s p i c a t u m , and Toa cusiekii important graminoids i n t h i s a s s o c i a t i o n . In the study meadow the few s o i l pockets tha t remain moist throughout the growing season support a l u s h a s s o c i a t i o n o f p l a n t s dominated by T h a l i c t r u m o c c i d e n t a l e and Elymus g l a u o u s . Other spec ies f requen t ing these moist s i t e s are Veratrum v i r i d e 3 S e n e c i o t r i a n g u l a r i s 3 R a n u n c u l u s e s c h s c h o l t z i i 3 and E p i l o b i u m a l p i n u m . The meadow vege ta t i on i s dominated by spec ies growing i n more or l e s s mesic h a b i t a t s . The a s s o c i a t i o n dominated by F e s t u c a v i r i d u t a 3 E r i g e r o n p e r e g r i n u s 3 E r y t h r o n i u m g r a n d i f l o r u m , and Veronica cusiekii appears to occur on the dry-mesic s i t e s . The group dominated by V a l e r i a n a s i t c h e n s i s 3 L u p i n u s l a t i f o l i u s 3 Anemone Occidentalis3 and P o t e n t i l t a f l a b e l l i f o l i a seems, on the o ther hand, to favor mois t -mes ic h a b i t a t s , a l though V a c c i n i u m s c o p a r i u m and E i e r a c i u m g r a c i l e form s t rong b r idges of p o s i t i v e a s s o c i a t i o n to d r y - s i t e species ( F i g . 11) . In an e c o l o g i c a l study o f the a l p i n e l a r c h (.Larix lyallii) i n the-r-Eacif ie:; Northwest , Arno and Habeck (1972 ) g ive a l i s t o f 7 5 i n d i c a t o r spec ies of the unders tory vege t a t i on a s s o c i a t e d w i t h a l p i n e l a r c h , w i t h 25 spec ies each as i n d i c a t o r s o f x e r i c , mes ic , and h y d r i c c o n d i t i o n s . The d i s p o s i t i o n o f many o f the species i n F i g . 11 agrees w i t h tha t presented by these au thor s , and my judgements of the s o i l mois ture preferences of most of the more than 2 0 spec ies tha t B l a c k w a l l Meadow has i n common w i t h t h e i r l i s t of i n d i c a t o r s agree w i t h t h e i r assessments. An extremely i n t e r e s t i n g aspect o f a s s o c i a t i o n i n the meadow i n v o l v e s C a s t i l l e j a m i n i a t a and P e d i c u l a r i s b r a c t e o s a . 40 both o f which are roo t hemiparas i tes ( K u i j t 1969). Castilleja has very s t rong p o s i t i v e a s s o c i a t i o n w i t h Arnica m o l l i s , and s e c o n d a r i l y w i t h L u z u l a s p i c a t a and P e n s t e m o n p r o c e r u s . P e d i c u -laris co-occurs s i g n i f i c a n t l y w i t h Vaccinium scoparium and Luzula hitchcockii. These a s s o c i a t i o n phenomena are probably due i n great par t to h o s t - p a r a s i t e co-occur rence . C o r r e l a t i o n The d e t e c t i o n of a s s o c i a t i o n i s based on the mere presence or absence of s p e c i e s . The q u a n t i t a t i v e r e l a t i o n s h i p s between species are best de tec ted by a c o r r e l a t i o n c o e f f i c i e n t , r a t h e r thansa measure of a s s o c i a t i o n . For each p o s s i b l e v a r i a b l e p a i r of spec ies I have c a l c u l a t e d an r , or product-moment c o r r e l a t i o n c o e f f i c i e n t o f cover v a l u e s , i n the manner of Soka l and R o h l f (1969). A t - t e s t (Soka l and R o h l f 1969) of the s i g n i f i c a n c e o f each r was a l s o computed (Appendix 2 ) . Norma l i t y i s an assumption of r. Therefore at l e a s t f i v e c o i n c i d e n t presences are r e q u i r e d f o r the c a l c u l a t i o n o f the c o e f f i c i e n t , so as to avo id exceeding the l i m i t s of d e v i a t i o n from n o r m a l i t y set by Sokal and Sneath (19 63) . Trends i n c o r r e l a t i o n depend on the sample quadrat s i z e (Gre ig -Smi th 1964; Kershaw 19 64) and changes r e l a t e d to v a r i a t i o n i n quadrat s i z e can y i e l d i n f o r m a t i o n about the nature and causes of i n t e r s p e c i f i c a s s o c i a t i o n . The causes o f c o r r e l a t i o n are e s s e n t i a l l y the same as those of a s s o c i a t i o n . However, these causa l f a c t o r s do not n e c e s s a r i l y make s i m i l a r c o n t r i b u t i o n s to a s s o c i a t i o n and c o r r e l a t i o n . C o r r e l a t i o n - S a l t Marsh 41 The most abundant spec ies of the h igh marsh had p re -dominantly negat ive c o r r e l a t i o n s w i t h o ther s p e c i e s , but the dominant spec ies o f the low marsh had about the same number o f t o t a l p o s i t i v e and nega t ive c o r r e l a t i o n s . Th i s suggests both tha t there i s more in tense compe t i t i on i n the more or l e s s c o n t i n u o u s l y vegetated h i g h marsh meadow, and t h a t , i n the more extreme c o n d i t i o n s of the low l e v e l mud f l a t s , spec ies such as S a l i c o r n i a v i r g i n i c a 3 P l a n t a g o m a r i t i m a , and C a r e x lyngbyei may p o s i t i v e l y i n f l u e n c e the es tab l i shment and s u r v i v a l o f o ther p ioneer s p e c i e s . 2 In g e n e r a l , va lues of x and C o l e ' s c o e f f i c i e n t o f a s s o c i a t i o n agree w i t h the r va lues over the whole community, 2 c o r r e l a t i o n s between r ' s and x ' s are s i g n i f i c a n t l y p o s i t i v e (P<0.01) f o r most quadrat s i z e s . D i s p a r i t i e s do o c c u r , however. For example, the species p a i r s Triglochin maritimum*Juncus b a l t i c u s s F e s t u c a r u b r a ^ A g r o s t i s e x a r a t a , J u n c u s b a l t i c u s * A g r o s t i s e x a r a t a , and G l a u x m a r i t i m a ^ S t e l l a r i a h u m i f u s a a l l have s i g n i f i c a n t l y p o s i t i v e x va lues but s i g n i f i c a n t l y negat ive r ' s . Festuca rubra i s a p a r t i c u l a r l y " in s t ruc t i ve species -in " this r ega rd . At almost a l l quadrat s i z e s , i t co-occurs s i g n i f i c a n t l y w i t h D e s c h a m p s i a c e s p i t o s a 3 J u n c u s b a l t i c u s 3 P o t e n t i l l a p a c i f i c a 3 and Agrostis e x a r a t a 3 yet has s t rong negat ive c o r r e l a t i o n s w i t h a l l of these s p e c i e s , and the c o r r e l a t i o n s become i n c r e a s i n g l y negat ive w i t h decreas ing quadrat s i z e . E v i d e n t l y , a l though these spec ies co-occur s i g n i f i c a n t l y , the r e s u l t a n t compe t i t i ve i n t e r a c t i o n s l ead to negat ive c o r r e l a t i o n s . 42 Conve r se ly , the species p a i r s Triglochin maritimumx S p e r g u l a r i a c a n a d e n s i s and C a r e x lyngby e i x T r i f o l i u m wormsk-2 joldii have s i g n i f i c a n t l y negat ive x va lues but s i g n i f i c a n t l y p o s i t i v e r ' s . I n these cases , the spec ies do not f r equen t ly co -occu r , but when they do they perform w e l l toge ther . Spergularia canadensis i s almost e x c l u s i v e l y a mud f l a t s p e c i e s , w h i l e Triglochin maritimum i s the commonest species i n the marsh and occurs throughout i t . When Triglochin does grow on the mud f l a t s , i t i s o f t en accompanied by Spergularia, perhaps because the l o c a l t i d a l seed d i s p e r s a l of the annual Spergularia ( S a l i s b u r y 19 58) tends to concentra te i t s subsequent e s t a b l i s h -ment around clumps o f e x i s t i n g v e g e t a t i o n such as Triglochin. The case of C a r e x l y n g b y e i x T r i f o l i u m w o r m s k j o l d i i i s more d i f f i c u l t to e x p l a i n . The nega t ive a s s o c i a t i o n cum p o s i t i v e c o r r e l a t i o n may be due to n iche d i s s i m i l a r i t y (see Sec t . I I -H) combined w i t h a s t i m u l a t i o n of the performance o f Carex lyngbyei by the n i t r o g e n f i x a t i o n of Trifolium wormskjoldii. A f i n a l po in t o f i n t e r e s t i s tha t Distichlis spicata i s the on ly spec ies to have a p o s i t i v e c o r r e l a t i o n w i t h bare mud. Accord ing to Adams (1963) , Vogl (1966) , and R e d f i e l d (1972), Distichlis i s a species of h igher marsh l e v e l s ' a l o n g the A t l a n t i c and C a l i f o r n i a n c o a s t s . Both i n the study marsh and i n o the r s a l t marshes i n the v i c i n i t y , I have observed Distichlis to be an in f requent spec ies tha t when present u s u a l l y grows at the v e g e t a t i o n margins on low mud f l a t s . Perhaps, s i nce D. spicata i s near the nor.thern l i m i t of i t s range i n the Tof ino a r e a , i t occurs on what would normal ly be unusual s i t e s ( c f . Stebbins and Major 1965). C o r r e l a t i o n - Sphagnum bogs 43 Species pa t te rns o f c o r r e l a t i o n w i t h i n each bog are u n p r e d i c t a b l e . Some species p a i r s e x h i b i t the same c o r r e l a t i o n i n both bogs; e g . , Carex o b n u p t a x Ledum g r o e n l a n d i c u m and V a c c i n i u m oxy.coccus * D r o s e r a r o t u n d i f o l i a have p o s i t i v e r ' s kiid2Aptargidium..xd:o!reaXexLe.dum.. g r o e n l a n d i c u m and A p a r g i d i u m b o r e a l e x-Sanguisorba officinalis have negat ive r ' s i n both Wade's Bog and Ogg's Bog. Other species p a i r s change; e g . , r f o r Carex obnupta*Sanguis orb a officinalis changes from negat ive to p o s i t i v e , and tha t fo r K a l m i a p o l i f o l i a x D r o s e r a r o t u n d i f o l i a from p o s i t i v e to n e g a t i v e , i n Wade's Bog as opposed to Ogg's Bog. However, the commonest behavior i s fo r r t o change i n s t r eng th but not i n s i g n , o r to change a sma l l amount i n s i g n , from one bog to another . D i f f e r e n t c o r r e l a t i o n s i n each bog fo r a p a r t i c u l a r spec ies p a i r would be expected i f s ( a s pos tu la t ed ) Wade's Bog i s s u c c e s s i o n a l l y more mature than Ogg's Bog, and i f spec ies i n t e r a c t i o n s do change w i t h s u c c e s s i o n , as G r e i g -Smith (1964) and Kershaw (1964) m a i n t a i n . Each i n d i v i d u a l case has i n t e r e s t i n g f e a t u r e s , but i t i s not f e a s i b l e to d i s cus s the c o r r e l a t i o n behavior of a l l p o s s i b l e species p a i r s . A good example of the type o f in fo rm-a t i o n tha t can be obta ined i s a f forded by the species p a i r M y r i c a g a l e x S a n g u i s o r b a o f f i c i n a l i s . In Wade's Bog, M y r i c a gale i s s t r o n g l y p o s i t i v e l y c o r r e l a t e d w i t h Sanguisorba offici-nalis at the 1 m 2 ( r =.+0.74, P<0.01) and 0.25 m 2 (r = +0.99, P<0.001) quadrat s i z e s . Furthermore, i n Wade's Bog, 6 7% of the i n t e r s p e c i f i c c o r r e l a t i o n s o f Myrica are n e g a t i v e , and 44 Sanguisorba i s the o n l y spec ies w i t h a s i g n i f i c a n t l y p o s i t i v e c o r r e l a t i o n w i t h Myrioa. In c o n t r a s t , i n Ogg's Bog, r f o r MyrioaxSanguisorba changes from +0.40 to +0.10 to -0 .28 i n the 2 1, 0 .25 , and 0.01 m quadrat s i z e s , r e s p e c t i v e l y . My e x p l a n a t i o n f o r t h i s behavior i s t ha t i n e a r l y s u c c e s s i o n a l s t ages , the n i t r o g e n - f i x i n g a c t i v i t y of M. gale b e n e f i c i a l l y o f f s e t s the negat ive e f f ec t s of i t s dense, v i g o r o u s , shrubby growth. Consequent ly , many o ther spec ies are ab le to compete on f a i r l y equal f o o t i n g w i t h Myrioa. As success ion p rogresses , Myrioa's compe t i t i ve a b i l i t y a s se r t s dominance to the extent tha t on ly Sanguisorba i s ab le to perform s u c c e s s f u l l y i n compe t i t i on w i t h i t . The dec iduous , a roma t i c , h i g h l y o i l y leaves of M. gale suggest tha t a l l e l o p a t h y may a l s o be i n v o l v e d here (wet, spongy Sphagnum would be an i d e a l medium f o r a w a t e r - s o l u b l e , a l l e l o -p a t h i c c h e m i c a l ) . Another i n t e r e s t i n g aspect of i n t e r s p e c i f i c c o r r e l a t i o n i n v o l v e s comparisons between d i f f e r e n t growth forms. In both bogs, about 77% of a l l c o r r e l a t i o n c o e f f i c i e n t s between a l l g r a s s , sedge, and rush spec ies are nega t ive . Only about 57% of a l l r's between a l l shrubby spec ies ( E r i c a c e a e , Empetrum nigrum, M y r i o a g a l e , L i n n a e a b o r e a l i s ) are nega t ive . The shrubby spec ies appear to be competing l e s s a c t i v e l y w i t h each o ther than the grasses and g r a s s - l i k e s p e c i e s ; the grea te r v a r i e t y of v e g e t a t i v e and r ep roduc t i ve cha rac t e r s i n the shrubs may r e f l e c t an inc reased n iche d i v e r s i f i c a t i o n and s p e c i a l i z a t i o n tha t reduces compe t i t i on between shrubby spec ies (see Sec t . I I I - H ) . C o r r e l a t i o n - B l a c k w a l l Meadow 45 I n t e r s p e c i f i c c o r r e l a t i o n , both p o s i t i v e and n e g a t i v e , i s s t ronges t i n the subalp ine meadow (Appendix 2 , Table 9 ) . Th i s i s not s u r p r i s i n g ; the h igh d i v e r s i t y and d e n s i t y of the meadow v e g e t a t i o n , the compressed growing season, and the heavy f l o r a l f l u s h should a l l c o n t r i b u t e to the s t rong i n t e r s p e c i f i c compe t i t i on tha t leads to s t rong c o r r e l a t i o n . The c o r r e l a t i o n pa t te rns o f the three co-dominant species of B l a c k w a l l Meadow are i n t e r e s t i n g . 71% of a l l c o r r e l a t i o n s w i t h V a l e r i a n a s i t e h e n s i s are n e g a t i v e ; w i t h F e s t u o a v i r i d u l a , only 31%; w i t h Lupinus l a t i f o l i u s , about 52%. Valeriana i s a r o b u s t , s t r o n g l y rhizomatous t a l l fo rb w i t h l a r g e l e a v e s . I t has the h ighes t average cover (25%) o f a l l the spec ies i n the meadow, and i t c l e a r l y dominates most species w i t h which i t c l o s e l y c o - o c c u r s . Festuoa i s a medium-height, nar row- leafed bunchgrass. The low percentage of nega t ive c o r r e l a t i o n s w i t h Festuoa i s due i n par t to i t s l a c k o f v e g e t a t i v e r e p r o d u c t i o n . A l s o , s ince i t i s a g r a s s , i t should not compete as i n t e n s e l y w i t h the showy-flowered forbs tha t c o n s t i t u t e the bu lk o f the meadow v e g e t a t i o n , as i t does w i t h o ther grasses or as the forbs do w i t h themselves . Lupinus, though a l a r g e , densely robus t s p e c i e s , has n e a r l y equal numbers o f p o s i t i v e and nega t ive c o r r e l a t i o n s . A g a i n , as w i t h Myrioa gale i n the sphagnum bogs, i t may be tha t Lupinus ' dominat ing q u a l i t i e s are tempered by the b e n e f i c i a l e f f e c t s of i t s n i t r o g e n f i x a t i o n . Only 4/13 or 31% of the r ' s w i t h the h e m i p a r a s i t i c C a s t i l l e j a m i n i a t a are p o s i t i v e ( P e d i c u l a r i s b r a o t e o s a , the 46 o ther h e m i p a r a s i t i c s p e c i e s , has too few c o r r e l a t i o n c o e f f i c i e n t s to pronounce upon). C a s t i l l e j a 1 s on ly p o s i t i v e v of any s t r eng th (r = +0.44) i s w i t h Lupinus latifolius ; n i t r o g e n - f i x a t i o n can be i m p l i c a t e d i n t h i s c o r r e l a t i o n . Thus, a l though Castilleja has some very p o s i t i v e i n t e r s p e c i f i c a s s o c i a t i o n s (see para-graphs on a s s o c i a t i o n i n the subalp ine meadow), co-occurrence w i t h i t depresses the performance of i t s a s s o c i a t e d s p e c i e s , which one might s a f e l y presume are the host p l a n t s i n most cases . C o r r e l a t i o n s between the meadow r e p r e s e n t a t i v e s of the Compositae and between a l l spec ies of g r a s se s , sedges, and wood rushes show d i f f e r e n t p a t t e r n s . 67% of a l l c o r r e l a t i o n s between Compositae are p o s i t i v e , compared to only 45% between the graminoid spec i e s . A g a i n , t h i s d i f f e r e n c e cou ld be due to g rea te r n iche s p e c i a l i z a t i o n i n the spec ies of Compositae, s p e c i a l i z a t i o n tha t a l l o w s them to c o e x i s t more s u c c e s s f u l l y than the graminoids (see Sec t . I I I - H ) . O v e r a l l pa t te rns of a s s o c i a t i o n and c o r r e l a t i o n . A s s o c i a t i o n The S a l t Marsh has by f a r the h ighes t average abso lu te 2 2 va lue of a l l p o s s i b l e x va lues (|x | ) as w e l l as the h ighes t percentage of s i g n i f i c a n t i n t e r s p e c i f i c a s s o c i a t i o n s (Table 9 ) . Strong environmental s t r e s s ope ra t ing w i t h i n a heterogeneous h a b i t a t produces s t rong m i c r o s i t e s p e c i f i c i t y , u s u a l l y fo r e i t h e r the upper marsh meadow or the lower mud f l a t s , and i s TABLE 9. Summary o f species i n t e r a c t i o n s . 47 Community % s i g n i f i c a n t x2 | X 2 I (mean | x2 I ) °"° s i g n i f i c a n t \v\ fo r a l l p o s s i b l e . r ' s i n t e r a c t i o n s S a l t Marsh 97.5 23.3 10.6 0.29 Wade's Bog 35.5 3.8 17.3 0.26 Ogg's Bog 82.0 5.2 11.1 0.24 B l a c k w a l l 84.3 4.4 14.3 0.33 Meadow probably r e s p o n s i b l e f o r these h i g h v a l u e s . Wade's Bog has the lowest |x2| and by fa r the lowest percentage of s i g n i f i c a n t x 2 , s . These low f i g u r e s are probably due to the low h a b i t a t he te ro -gene i ty and r e l a t i v e l y advanced s u c c e s s i o n a l s ta te of t h i s bog. Ogg's Bog has much s t ronger i n t e r s p e c i f i c a s s o c i a t i o n than Wade's Bog, conver se ly due to a much g rea te r h a b i t a t he te ro -gene i ty (pronounced hummock-hollow microtopography, bog f o r e s t i s l a n d s , v a r i a b l e peat depth) and an e a r l i e r s u c c e s s i o n a l s t a t u s . B l a c k w a l l Meadow has a h i g h p r o p o r t i o n of s i g n i f i c a n t X 2 ' s and an in te rmedia te lx 2 l i~ • -u -r • -•- ^ - i • A 5 which I i n t e r p r e t as r e s u l t i n g from f a i r l y s t rong m i c r o s i t e s p e c i f i c i t y b l u r r e d by a h igh degree o f i n t e r s p e c i f i c compe t i t i on and (perhaps) toned-down by r e l a t i v e s u c c e s s i o n a l m a t u r i t y . C o r r e l a t i o n 48 I f spec ies d i s t r i b u t i o n were a complete continuum, there should be a l l degrees of p o s i t i v e and nega t ive c o r r e l a t i o n w i t h i n a g iven p l a n t community. C i rcumneu t ra l r '-s should p re -dominate because the p r o b a b i l i t y of a g iven va lue of r decreases as a f u n c t i o n of the extremeness of r (Byer 1970). A frequency curve of the va lues of r should be near normal w i t h a peak near zero and t a i l s con t i nuous ly f a l l i n g on both s ides (Byer 1970). F igure 12a-d i n d i c a t e s tha t t h i s i s so o n ly f o r the suba lp ine meadow, the curves f o r the two sphagnum bogs and the s a l t marsh being skewed s l i g h t l y to the l e f t of z e r o ; i . e . , there are more negat ive than p o s i t i v e i n t e r s p e c i f i c c o r r e l a t i o n s i n the l a s t three communities. Furthermore, frequency d i s t r i b u t i o n s of s h i f t s of g iven magnitudes i n v values w i t h r e d u c t i o n i n quadrat s i z e ( F i g . 13a-d) i n d i c a t e t h a t , i n g e n e r a l , p o s i t i v e c o r r e l a t i o n d imin i shes w i t h decreas ing quadrat s i z e . P o s i t i v e c o r r e l a t i o n should be reduced a t c l o s e r q u a r t e r s , both because of more in tense compe t i t i on and a l s o r e d u c t i o n of w i th in -quad ra t he te rogene i ty (Gre ig -Smi th 1964; Kershaw 1964; Byer 1970). The means of the abso lu te va lues o f a l l c o e f f i c i e n t s o f c o r r e l a t i o n ( | r | ) f o r each community are a l s o g iven i n Table 9. As H u r l b e r t (1969) p o i n t s o u t , c o r r e l a t i o n c o e f f i c i e n t s are probably more v a l i d i n d i c a t o r s of i n t e r s p e c i f i c compe t i t i on than are measures o f a s s o c i a t i o n . The suba lp ine meadow spec ies e x h i b i t the h ighes t | r | i n d i c a t i v e , I t h i n k , o f r e l a t i v e l y s t ronger i n t e r s p e c i f i c compe t i t i on i n the meadow. The low \v\ F i g . 12. F r e q u e n c i e s o f r v a l u e s f o r t h e t h r e e F i g . 1 3 . F r e q u e n c i e s o f s h i f t s o f g i v e n m a g n i t u d e s r a n d o m q u a d r a t s i z e s . i n r v a l u e s w i t h r e d u c t i o n i n q u a d r a t s i z e . 50 of the sphagnum bogs i s probably a consequence of a low degree o f c o m p e t i t i o n . The in te rmed ia te va lue of \~r\ f o r the s a l t marsh may be i n t e r p r e t e d as r ep resen t ing an in te rmedia te l e v e l of compe t i t i on between species of the marsh, where the vege t a t i on i s f a i r l y continuous but there are (among other t h ings ) fewer s p e c i e s , a longer growing season, and much l e s s r e l i a n c e on i n s e c t p o l l i n a t o r s than i n the subalp ine meadow. For a l l four communit ies , f u r t h e r c o r r e l a t i o n s between r-'s and both x 2 ' s a n < i C o l e ' s c o e f f i c i e n t s are p o s i t i v e ( u s u a l l y s i g n i f i c a n t l y ) fo r a l l quadrat s i z e s . O v e r a l l , these c o r r e l a t i o n s are s t ronges t at the sma l l e s t quadrat l e v e l s , presumably because the sma l l quadrats can detec t the a s s o c i a t i o n pa t te rns tha t are on a s m a l l enough s ca l e to be comparable to the c o r r e l a t i o n p a t t e r n s . In summary, the pa t te rns o f i n t e r s p e c i f i c a s s o c i a t i o n and c o r r e l a t i o n may be i n t e r p r e t e d as i n d i c a t i n g an i n t e r p l a y o f environmenta l ( p h y s i c a l ) and compe t i t i ve ( b i o l o g i c a l ) f a c t o r s . Th i s i n t e r p r e t a t i o n i m p l i e s tha t the s t r e s s of the p h y s i c a l environment i s h ighes t i n the s a l t marsh, in te rmedia te i n the bogs, and lowest i n the subalpine meadow. In c o n t r a s t , i n t e r -s p e c i f i c compe t i t i on i s s t ronges t i n the suba lp ine meadow, o f medium s t r eng th i n the s a l t marsh, and weakest i n the sphagnum bogs. 51 C. Chromosome numbers and p o l y p l o i d y . Recent s tud ies i n p l an t cytogeography have been much concerned w i t h the r e l a t i o n s h i p of angiosperm p o l y p l o i d y to environment. The hypothes is tha t p o l y p l o i d s are p h y s i o l o g i c a l l y favored over d i p l o i d s i n extreme environments (Hagerup 19 31; Love and Love 1949, 19 57; Mooney and Johnson 1965) has been much d i spu ted (Bowden 1940; Gustaf fson 1948; Johnson and Packer 1965; Johnson et al. 1965; Favarger 1967; Stebbins 1950, 1971b). A.umore accepted view i s tha t p o l y p l o i d s have been a t a s e l e c t i v e advantage i n p h y s i c a l environments c h a r a c t e r i z e d by f requent , d r a s t i c , i r r e g u l a r l y r e c u r r e n t d i s tu rbances (Johnson and Packer 1965; Stebbins 1971b) and (or) sharp e c o l o g i c a l g rad ien t s ( B e l l 19 64) , presumably because the great gene t i c v a r i a b i l i t y r e s u l t i n g from h y b r i d i z a t i o n and subsequent p o l y -p l o i d i z a t i o n g ives the p o l y p l o i d s a b e t t e r chance of s u r v i v a l than comparable d i p l o i d s . I t i s a l s o b e l i e v e d tha t most p o l y -p l o i d s have been d i f f e r e n t i a l l y succes s fu l i n p o s t g l a c i a l r e c o l o n i z a t i o n o f bare ground, not n e c e s s a r i l y because o f b e t t e r p o l y p l o i d c o l o n i z i n g a b i l i t y , but because c o n d i t i o n s at the margins of the i c e sheet and on r e c e n t l y uncovered ground a l lowed format ion and es tab l i shment of p o l y p l o i d d e r i v a t i v e s w i t h new genotypes (Stebbins 1950; Johnson et al. 1965). P o l y p l o i d y would s t a b i l i z e the s e l e c t i v e l y favored genotypes by reduc ing gene t ic recombina t ion and e l i m i n a t i n g the s t e r i l i t y tha t i s o f t en the fa te o f d i p l o i d h y b r i d s (Mosquin 1966; Stebbins 1971b). Furthermore, i n t e r - or p o s t - g l a c i a l immigra t ion o f d i p l o i d species may not 'have had s u f f i c i e n t t ime to reduce 52 the p o l y p l o i d frequency (Reese 1961). I t appears tha t e n v i r o n -mental and h i s t o r i c a l exp lana t ions are more va luab l e than those based on i n t r i n s i c p h y s i o l o g i c a l p r o p e r t i e s o f p o l y p l o i d s . Most o f the p e r t i n e n t s tud ie s have used p o l y p l o i d f requencies c a l c u l a t e d from f l o r a s o f va r ious geograph ica l a reas . Most (see , however, P i g n a t t i 1960; F u n a b i k i 1960, 1967) have ignored the r e l a t i v e importance of p o l y p l o i d spec ies i n the v e g e t a t i o n , understandably so , s ince the presence o f a spec ies i s o f more phytogeographic s i g n i f i c a n c e than i t s abundance. N e v e r t h e l e s s , i t would be i n t e r e s t i n g to assess the r o l e o f p o l y p l o i d y i n q u i t e d i f f e r e n t v e g e t a t i o n types w i t h i n roughly the same geographic a rea . Data are presented here f o r the percentage o f angiosperm p o l y p l o i d y i n both the f l o r a and v e g e t a t i o n of the four communities i n the present s tudy. Chromosome numbers were determined p r i m a r i l y from f lower-bud m a t e r i a l , a l though a few r o o t - t i p squashes were a l s o made. Flower buds were c o l l e c t e d from f i e l d popu la t ions and f i x e d i n 3:1 e t h y l a l c o h o l and a c e t i c a c i d . M e i o t i c counts were made from microsporocy tes squashed i n i r o n haematoxy l in . Root t i p s were c o l l e c t e d i n the f i e l d , p r e t r ea t ed w i t h 8 -hyd roxyqu ino l i ne , f i x e d i n 3:1 e t h y l a l c o h o l and a c e t i c a c i d , and a l s o squashed i n i r o n haematoxyl in . Camera l u c i d a drawings of the va r ious chromosome complements are presented i n F igures 14-110. The r e s u l t s are t a b u l a t e d i n Table 10. The species are arranged i n order of decreas ing importance v a l u e . A l l counts made by the author are from m a t e r i a l c o l l e c t e d at the r e s p e c t i v e s i t e s . Chromosome numbers marked w i t h an a s t e r i s k are from t axa F i g . 14. D e s c h a m p s i a o e s p i t o s a 3 n - 13. F i g . 15. F e s t u c a r u b r a , n = 21. F i g . 16. T r i g l o c h i n m a r i t i m u m 3 n = 48 F i g . 17. S a l i c o r n i a v i r g i n i c a 3 n = 18 F i g . 18. P l a n t a g o m a r i t i m a 3 n = 6 • F i g . 19. J u n c u s b a l t i c u s 3 n = 40. F i g . 20. C a r e x l y n g b y e i 3 n = 36. F i g . 21. G l a u x m a r i t i m a , n - 15. F i g . 2 2., P o t e n t i l l a p a c i f i c a , n - 14. F i g . 23. A g r o s t i s e x a r a t a , n = 14 . F i g . 24. S t e l l a r i a h u m i f u s a , n - 13. F i g . 25. T r i f o l i u m w o r m s k j o l d i i 3 n = 16 . F i g . 26. S c i r p u s c e r n u u s 3 n = 30. F i g . 27. P u c c i n e l l i a p u m i l a 3 n - 21. F i g - 28. S p e r g u l a r i a c a n a d e n s i s 3 n - 18. F i g . 29. H o r d e u m b r a c h y a n t h e r u m 3 n - 14. F i g . 30 . L i l a e o p s i s o c c i d e n t a l i s 3 n - 22. 53 b • 9 % • • i 16 17 • 4 • a 1 18 • 19 •••••V 20 21 • 22 5 4 o u F i g - 31. M y r i c a g a l e , n - 48 F i g . 32. A p a r g i d i u m b o r e d l e , n — i 3 F i g . 33. C a r e x o b n u p t a , n - 37 F i g . 34. C a r e x p l u r i f l o r a , n = 26 F i g . 35. A g r o s t i s a e q u i v a l v i s , n = 7 F i g . 36. S a n g u i s o r b a o f f i c i n a l i s , n = 14 F i g . 37. Ledum g r o e n l a n d i c u m . n = 13 F i g . 38. V a c c i n i u m o x y c o c c u s , n = 24 F i g . 39. D r o s e r a r o t u n d i f o l i a , n = 10 F i g . 40 . K a l m i a p o l i f o l i a , n - 12 F i g . 41. E m p e t r u m n i g r u m , n - 13 F i g - 42 . T r i e n t a l i s a r c t i c a , n = c a . 42-44 F i g . 43 . C a r e x c a n e s c e n s , n - 28 F i g . 44. T o f i e l d i a g l u t i n o s a , n - 15 F i g . 45. L i n n a e a b o r e a l i s , n = 16 F i g . 46. R h y n c h o s p o r a a l b a , n = 13 F i g . 47 . P l a n t a g o m a c r o c a r p a , n - 12 F i g . 48. G a u l t h e r i a s h a l l o n , n - 44 F i g . 49 . G e n t i a n a s c e p t r u m , n = 13 F i g . 50. C a l a m a g r o s t i s n u t k a e n s i s , n — 14 0 I * 45 • •• *•_•*/ •••• 4 6 4 9 - A 47 •SA 4 8 Zum<L 50 5 5 CL/ F i g . 51. M a i a n t h e m u m d i l a t a t u m , n = 18. F i g . 52 . S c i r p u s c e s p i t o s u s 3 n - c a . 52. F i g . 53 . C o p t i s a s p l e n i f o l i a , n = 9 . F i g . 54. C o p t i s t r i f o l i a , n - 9 • F i g . 55 . J u n c u s s u p i n i f o r m i s , n = ca . 56 F i g . 56 . G e n t i a n a d o u g l a s i a n a . n = 13. F i g . 57. V a c c i n i u m o v a t u m , n - 12 • F i g - 58. V a c c i n i u m v i t i s - i d a e a 3 n = 12. F i g . 59 . V a c c i n i u m u l i g i n o s u m , n = 24. F i g . 60. N e p h r o p h y l l i d i u m c r i s t a - g a l l i , n = c a . 51. F i g . 61 . •Er wphorum L p 6 l y > s t a c h i o h 3 n - 30 F i g - 62 . C a r e x p a u c i f l o r a 3 n - ca . 37. 5Sb 60 61 6 2 5 6ox F i g . 63 . V a l e r i a n a s i t c h e n s i s 3 n - c a . 48. F i g . 64. L u p i n u s l a t i f o l i u s 3 n - c a . 48. F i g . 65. F e s t u c a v i r i d u l a , n - 14. F i g . 66. E r i g e r o n p e r e g r i n u s 3 n - 9. F i g . 67. Anemone o c c i d e n t a l i s 3 2n = 16. F i g . 68. E r y t h r o n i u m g r a n d i f l o r u m 3 2n = 24. F i g . 69 . P o t e n t i l l a f l a b e l l i f o l i a 3 n = 14. F i g . 70. V a c c i n i u m s c o p a r i u m 3 n - 12 . F i g . 71. C l a y t o n i a l a n c e o l a t a , 2n = 16. F i g . 12. A r e n a r i a c a p i l l a r i s 3 n - 11. F i g . 73. A n t e n n a r i a l a n a t a , n - 14 • F i g . 74. V e r o n i c a c u s i c k i i 3 n - 36 • F i g . 75. A g o s e r i s a u r a n t i a c a 3 n - 18. F i g . 76. F h l e u m a l p i n u m , n - 14. F i g . 77. A r n i c a l a t i f o l i a 3 n - 19. Stb 75 77 F i g . 78. L u z u l a h i t c h c o c k i i , n - 12. F i g . 79. T h a l i c t r u m o c c i d e n t a l e , n = F i g . 80 . A c h i l l e a m i l l e f o l i u m , n = 27 F i g - 81. T r i s e t u m s p i c a t u m , n = 14. F i g . 82 . E l y m u s g l a u c u s , n = 14. F i g . 83. S i l e n e p a r r y i , n = 24. F i g . 84. A r n i c a m o l l i s , n = ca . 38 . F i g . 85. P e n s t e m o n p r o c e r u s , n = 8. F i g . 86. P o a c u s i c k i i , n - 14. F i g . 87. S e n e c i o i n t e g e r r i m u s , n = 20 F i g . 88. E i e r a c i u m g r a c i l e , n - 9. F i g . 89. L u z u l a s p i c a t a , n - 12. F i g . 90. Sedum l a n c e o l a t u m , n - 8. F i g . 91. C a s t i l l e j a m i n i a t a , n - 12. F i g . 92. P e d i c u l a r i s b r a c t e o s a , n = 8 F i g - . 93. P h l o x d i f f u s a , n = 7. 94. P o t e n t i l l a d i v e r s i f o l i a 3 n - c a . 95. C a r e x s p e c t a b i l i s 3 n - c a . 42. 96. E p i l o b i u m a l p i n u m 3 n - 18. 97. D e l p h i n i u m n u t t a l l i a n u m 3 n - 16. 98. C a s t i l l e j a p a r v i f l o r a 3 n - 12. 99. R a n u n c u l u s e s c h s c h o l t z i i 3 n - 16. 100. S i b b a l d i a p r o c u m b e n s 3 n = 7. 101. J u n c u s d r u m m o n d i i 3 n c a . 60. 102. H y d r o p h y l l u m f e n d l e r i , n = 18. 103. S e n e c i o t r i a n g u l a r i s 3 n - 20. 104. V a c c i n i u m d e l i c i o s u m 3 n - 24. 105. M i t e l l a p e n t a n d r a 3 n = 7. 106. L u e t k e a p e c t i n a t a 3 n = 9. 107. P e d i c u l a r i s r a c e m o s a 3 n = 8. 108. 109. 110. P h y l l o d o c e e m p e t r i f o r m i s 3 V e r a t r u m v i r i d e 3 n - 16. 7eroniea w o r m s k j o l d i i 3 n n - 24 = 9. 59 f o r which no number has been repor ted p r e v i o u s l y . Each species has been ass igned a b a s i c chromosome number obta ined o r i n f e r r e d from the l i t e r a t u r e , e s p e c i a l l y D a r l i n g t o n and Wyl ie (1955) , subsequent IOBP Repor t s , and Tay lo r and M u l l i g a n (1968). B a s i c numbers which are themselves probably o f p o l y p l o i d o r i g i n ( e g . , x = 12 f o r many E r i c a c e a e ; x = 15 fo r T o f i e l d i a ; x = 10 f o r A r n i c a ) have been r e t a i n e d here as d i p l o i d . For each s i t e , percentages of p o l y p l o i d y i n both the f l o r a and v e g e t a t i o n have been c a l c u l a t e d and are l i s t e d at the bases o f the cor responding t ab l e s and i n Table 11. In view of the e x c e p t i o n a l cy to logy of the Cyperaceae and Juncaceae (Nordensk io ld 19 51; Davies 19 56; Stebbins 1971b), a b a s i c number of 10 has been a r b i t r a r i l y chosen for Carex, Soiryus, and Junous. This i s in tended as a compromise. Both H e i l b o r n (1939) and Wahl (1940) cons idered x = 7 to be the o r i g i n a l b a s i c number of the genus C a r e x , a l though Wahl a l s o de tec ted s e r i e s based on x = 5, 6, and 8. Love et al. (1957) proposed x = 5 as the pr imary b a s i c number of both Carex and J u n o u s , w h i l e Snogerup (1963) mainta ined t ha t i n Junous the pr imary b a s i c number can be as h igh as x = 25. The aneup lo id numbers i n Carex, Scirpus, and Junous have probably a r i s e n through a combinat ion o f t rue p o l y p l o i d y and p a r t i a l agmato-p l o i d y , or endonuclear p o l y p l o i d y . At any r a t e , the chromosome numbers of the above genera i n t h i s study are h i g h enough to be cons idered p o l y p l o i d even i f the -basic number i s as h igh as x = 20. The r e s u l t s i n d i c a t e tha t l e v e l s of p o l y p l o i d y i n these four communities are f a i r l y h i g h , and tha t the l e v e l w i t h i n a 60 TABLE 10. Chromosome numbers, p o l y p l o i d y , and importance va lues of -species of the four study communit ies. Species Chromosome Bas i c No. , n N o . , x P o l y -p l o i d Importance va lue ( I . V . ) S a l t Marsh D e s o h a m p s i a 13 7 + 38.6 c e s p i t o sa 24. 5 F e s t u c a r u b r a 21 7 + T r i g l o c h i n 48 6 . + 21. 0 m a r i t i m u m 17 . 8 S a l i c o r n i a 18 9 + v i r g i n i c a 16.9 P l a n t a g o m a r i t i m a 6 6 — J u n c u s b a l t i c u s 40 10 + 16 . 8 C a r e x lyngbyei 36 10 + 14. 3 G l a u x m a r i t i m a 15 15 - 13. 9 P o t e n t i l l a 14 7 + 7. 2 p a c i f i c a 7 . 1 A g r o s t i s e x a r a t a 14 7 + S t e l l a r i a h u m i f u s a 13 13 — 6 . 0 T r i f o l i u m wormsk- 16 8 + 3 . 5 g o l d i i S c i r p u s c e r n u u s 30 10 + 3.3 P u c c i n e l l i a p u m i l a 21 7 + 2. 7 S p e r g u l a r i a 18 9 + 2 . 0 c a n a d e n s i s 1.8 D i s t i c h l i s s p i c a t a 2 0 a 5 H o r d e u m b r a c h y - 14 7 + 1. 8 a n t h e r u m L i l a e o p s i s 22 11 + 0.4 o c c i d e n t a l i s b 0.1 O e n a n t h e s a r m e n t o s a 22 D 11 + P l a n t a g o m a c r o c a r p a 12 6 + 0.1 17/20 or 85% of f l o r a Sum of p o l y p l o i d i s p o l y p l o i d I . V . ' s / 2 = 81.5% of v e g e t a t i o n i s p o l y p l o i d Wade's Bog C a r e x p l u r i f l o r a 26 10 + 30.1 A p a r g i d i u m b o r e a l e 9 9 - 27.2 A g r o s t i s a e q u i - 7 7 - 15.9 v a l v i s C a r e x o b n u p t a 37, c a . 38 10 + 15.9 TABLE 10. (Continued) 61 Chromosome Bas i c P o l y - Import ance Species No. , n No. , x p l o i d va lue ( I . V . ) S a n g u i s o r b a 14 7 + 15. 1 o f f i c i n a l i s 14. 0 K a t m i a p o l i f o l i a 12 12 -V a o o i n i u m o x y o o o o u s 24 12 + 13. 3 C a r e x c a n e s o e n s 28 10 + 11. 9 D r o s e r a r o t u n d i - 10 10 - 11. 2 fo lia 1 Ledum g r o e n l a n d i o u m 13 13 - 9. T r i e n t a l i s a r c t i o a c a . 42-44 11(?) + 8 . 9 E m p e t r u m n i g r u m 13 13 — 5 . 2 M y r i o a g a l e 48 8 + 4. 9 T o f i e I d i a 15 15 — 4 . 6 g l u t i n o sa 13 G e n t i a n a 13 — 1. 2 d o u g l a s i a n a L i n n a e a b o r e a l i s 16 8 + 1. 2 M a i a n t h e m u m 18 9 + 1. 0 d i l a t a t u m R h y n o h o s p o r a a l b a 13 13 - 0. 7 V a o o i n i u m v i t i s - 12 12 — 0 . 4 i d a e a S c i r p u s o e s p i t o s u s c a . 5 2 10 + 0. 3 J u n o u s s u p i n i f o r m i s c a . 5 6 10 + 0 . 2 V a o o i n i u m 24 12 + 0. 2 u l i g i n o s u m 0. G a u l t h e r i a s h a t t o n 44 11 + 2 G e n t i a n a s o e p t r u m 13* 13 - 0 . 2 C o p t i s a s p l e n i - 9 9 - 0 .  2 f o l i a 0. ,1 C o p t i s t r i f o l i a 9 9 -V a o o i n i u m o v a t u m 12 12 0 . , 1 13/27 or 48 .1% of Sum of p o l y p l o i d f l o r a i s I . V . ' s / 2 = = 51.6% p o l y p l o i d of v e g e t a t i o n i s p o l y p l o i d Ogg's Bo g M y r i o a gate 48 8 + 36 , .1 A p a r g i d i u m b o r e a t e 9 9 - 18 , . 4 C a r e x o b n u p t a 37 10 + 13. . 7 C a r e x p l u r i f l o r a 26 10 + 11 . 6 A g r o s t i s a e q u i - 7 7 — 10 . 7 v a l v i s TABLE 10. (Continued) 62 Species Chromosome No. , n Bas i c No. , x P o l y -p l o i d Importance value ( I . V . ) S a n g u i s o r b a 14 7 + 9 . 3 o f f i c i n a l i s Ledum g r o e n l a n d i o u m 13 13 - 8.1 V a o o i n i u m o x y o o o o u s 24 12 + 7.5 D r o s e r a r o t u n d i - 10 10 - 6.1 f o l i a K a l m i a p o l i f o l i a 12 12 - 5.8 E m p e t r u m n i g r u m 13 13 - 5.5 T r i e n t a l i s a r c t i o a c a . 42-44 11(?) + 5.4 C a r e x c a n e s c e n s 28 10 + 5.0 To f i e I d i a 15 15 - 4.7 g l u t i n o s a 4.0 L i n n a e a b o r e a l i s 16 8 R h y n o h o s p o r a a l b a 13 13 - 3.9 P l a n t a g o m a c r o c a r p a 12 6 + 3.8 G a u l t h e r i a s h a l l o n 44 11 + 3.3 G e n t i a n a s c e p t r u m 13* 13 - 2 . 5 C a l a m a g r o s t i s 14 7 + 2.0 n u t k a e n s i s M a i a n t h e m u m 18 9 + 2 . 0 d i l a t a t u m S c i r p u s c e s p i t o s u s ca . 52 10 + 1.6 C o p t i s a s p l e n i - 9 9 - 1.4 fo lia C o p t i s t r i f o l i a 9 9 - 1.4 J u n c u s s u p i n i f o r m i s c a . 56 10 + 1.1 D e s o h a m p s i a 13 7 + 0.9 o e s p i t o s a 0.6 G e n t i a n a 13 13 -d o u g l a s i a n a V a o o i n i u m o v a t u m 12 12 - 0 . 6 V a o o i n i u m v i t i s - 12 12 - 0.4 i d a e a C o r n u s u n a l a s o h - 22 11 + 0.4 k e n s i s V a o o i n i u m 24 12 + 0.3 u l i g i n o s u m N e p h r o p h y l l i d i u m ca . 51 17 + 0.3 o r i s t a - g a l l i E r i o p h o r u m 30 10 + 0.2 poly s t a c h i o n C a r e x p a u o i f l o r a c a . 3 7 d 10 + 0.2 Ly s i o h i t u m 14 d 14(?) - 0.1 a m e r i c a n u m TABLE 10 (Continued) 63 Species Chromosome Bas ic N o . , n N o . , x P o l y -p l o i d Importance value ( I . V . ) Habenaria saccata Goody era oblongi-fo l i a Junous effusus Juncus ensif olius 21 15 c 40< 20 ( d 21 15 10 10 22/39 or 56.4% of f l o r a i s p o l y p l o i d + + 0.1 0.1 0.1 0.1 Sum of p o l y p l o i d I .V. ' s / 2 = 54.5% o f vege t a t i on i s p o l y p l o i d B l a c k w a l l Meadow Valeriana c a . 48 8 + 24. 9 sitchensis Festuca viridula 14 7 + 24. 3 Lupinus latifolius c a . 48 12 + 21. 8 Erigeron 9 9 ' - 12. 4 peregrinus 11. Anemone 2n = 16 '8 - 9 occidentalis ( root t i p ) Potentilla 14 7 + 10. 4 f l a b e l l i f o l i a Erythronium 2n = 24 12 - 7. 0 grandiflorum (p re^meio t ic m i t o s i s ) Vaccinium •12* 12 - 6. 9 scoparium Claytonia 2n = 16 8 - 6 . 5 lanceolata ( p r e - m e i o t i c m i t o s i s ) Arenaria 11 11 - 6. 3 capillaris Antennaria lanata 14* 7 + 6. 2 Veronica cusickii 3 6* 9 + 5. 3 Agoseris 18 9 + 4. 8 aurantiaea Phleum alpinum 14 7 + 4. 8 Arnica l a t i f o l i a 19 10 + 4. 7 Luzula hitch- 12* 6 + 4. 6 cockii^ Thalictrum 2 8* 7 + 3. 7 occidentale AchiIlea 27 9 + 3. 5 mi Ilefolium Trisetum spicatum 14 7 + 3. 2 Carex rossii Not Not counted counted TABLE 10. (Continued) 64 Chromosome B a s i c P o l y - Importance Species N o . , n N o . , x p l o i d va lue ( I . V . ) E l y m u s g l a u c u s 14 7 + 2.5 S i l e n e p a r r y i 24 12 + 2.2 A r n i c a m o l l i s c a . 3 8 10 + 2.0 Pens.temon p r o c e r u s 8 8 - 2.0 P o a c u s i c k i i 14 7 + 1.9 S e n e c i o 20 10 + 1.8 i n t e g e r r i m u s E i e r a c i u m g r a c i l e 9 9 - 1.7 L u z u l a s p i c a t a 12 6 + 1.4 Sedum l a n c e o l a t u m 8 8 - 1.2 C a s t i l l e j a m i n i a t a 12 12 - 1.2 P e d i c u l a r i s 8 8 - 0.9 b r a c t e o s a P h l o x d i f f u s a 7 7 - 0 . 8 P o t e n t i l l a c a . 70 7 + 0.7 d i v e r s i f o l i a C a r e x s p e c t a b i l i s ca . 42 10 + 0.6 E p i l o b i u m a l p i n u m 18 9 + 0.5 D e I p h i n i u m 16* 8 + 0.5 n u t t a l l i a n u m C a s t i l l e j a 12 12 - 0.4 p a r v i f l o r a R a n u n c u l u s 16 8 + 0.4 e s c h s c h o l t z i i S i b b a l d i a 7 7 — 0.3 p r o o u m b e n s J u n o u s d r u m m o n d i i c a . 6 0 10 + 0.2 H y d r o p h y I l u m 18 9 + 0.2 f e n d l e r i S e n e c i o 20 10 + 0.2 t r i a n g u l a r i s V a o o i n i u m 24* 12 + 0.2 d e l i c i o s u m M i t e l l a p e n t a n d r a 7 7 - 0.1 L u e t k e a p e o t i n a t a 9 9 - 0.1 P e d i c u l a r i s 8 8 - 0.1 r a o e m o s a P h y l l o d o c e 24 12 + 0.1 empetrif'or mis f S a x i f r a g a 1 9 r 10 + 0.1 o c c i d e n t a l i s 8 g T r o l l i u s laxus 8 - . 0.1 V e r a t r u m v i r i d e 16 8 + 0.1 TABLE 10. (Concluded) 65 Species Chromosome No. , n Bas ic No. , x P o l y - Importance p l o i d va lue ( I . V . ) V e r o n i c a wormsk- 9 9 0.1 j o l d i i 31/50 or 62 . 0% Sum of p o l y p l o i d of f l o r a i s I . V . ' s / 2 = 70.3% p o l y p l o i d of v e g e t a t i o n i s p o l y p l o i d h S t e b b i n s and Love (1941). B e l l and Constance (1957); T a y l o r and M u l l i g a n (1968). ^ A f t e r Ca lder and Tay lo r (1968). As r epor ted i n Tay lo r and M u l l i g a n (1968). ^ A f t e r Hamet-Aht i (1971). Krause and Beamish ( in p r e s s ) . g P a c k e r (1964). p a r t i c u l a r area i s not d r a s t i c a l l y d i f f e r e n t whether computed as a percentage of the f l o r a or v e g e t a t i o n . Of the th ree vege t a t i on t y p e s c s t u d i e d , the s a l t marsh has the h ighes t l e v e l of p o l y p l o i d y (about 80%). The sphagnum bog v e g e t a t i o n has the lowest l e v e l (about 50%) and the suba lp ine meadow has an in te rmedia te l e v e l of about 65% (Tables 10 & 11) . Note tha t i f Carex and Seirpus are l e f t out of the c a l c u l a t i o n s , the p o l y p l o i d y l e v e l s fo r the bogs are d i s p r o p o r t i o n a t e l y lowered , i n c r e a s i n g the d i f f e r e n c e between l e v e l s i n the bogs and the other three s i t e s . Since a l l s i t e s are at e s s e n t i a l l y the same l a t i t u d e and were a l l covered by the P l e i s t o c e n e i c e sheet (Heusser 1960), d i f f e r e n c e s i n l e v e l s of p o l y p l o i d y cannot be exp la ined s a t i s f a c t o r i l y by d i f f e r e n t i a l e f f e c t s o f g l a c i a t i o n or 66 TABLE 11. Summary of l e v e l s of p o l y p l o i d y . No. of % . .polyploidy % p o l y p l o i d y S i t e spec ies ( f l o r a ) (vege ta t ion) S a l t Marsh 20 85.0 81.5 Wade's Bog 27 48.1 51. 6 Ogg's Bog 39 56.4 54. 5 B l a c k w a l l 50 62 . 0 70.3 Meadow p o s t g l a c i a l r e c o l o n i z a t i o n . R e c o l o n i z a t i o n of a l l s i t e s probably proceeded p r i m a r i l y from the area south o f the g l a c i a l boundary i n Washington, a l though the Tof ino area could conce ivab ly have been reached by c o a s t a l immigrants from r e f u g i a i n the Queen C h a r l o t t e I s l ands and P a c i f i c c o a s t a l A l a s k a (Heusser 1960; S c h o f i e l d 1969; Randhawa and Beamish 1972). Exp lana t ions based on v a r y i n g degrees o f average e n v i r o n -mental "harshness" , whether i n a c l i m a t i c or edaphic sense, are a l s o u n s a t i s f a c t o r y . Most impor tan t , comparisons o f measure-ments or es t imates of p h y s i c a l parameters among the four s i t e s would have l i t t l e meaning because of the d i s p a r i t y of t h e i r p h y s i c a l environments , assuming tha t such measurements would , i f comparable, have any f i n a l meaning (see Sect . I I I - J ) . However, c o r r e l a t i o n s w i t h environmenta l r i g o r can be made i f " r i g o r " i s def ined i n genera l terms and p a r t i t i o n e d i n t o s e v e r a l a spec t s . In l i n e w i t h the reasoning of Stebbins (1971b) and Johnson et al. (1965), l e v e l s o f p o l y p l o i d y can be r e l a t e d to the type and degree o f environmental d i s t u rbance . 67 In a d d i t i o n to average c o n d i t i o n s of the environmenta l complex such as c l i m a t i c means and n u t r i e n t l e v e l s , e s t i m a t i o n of environmental r i g o r must i n c l u d e the r e l a t i v e ampli tudes o f environmental f l u c t u a t i o n s and.-:ther , irr.eguiarity: or u n p r e d i c t a b i l i t y of these f l u c t u a t i o n s (S lobodk in and Sanders 19 69; Whi t t aker 19 72) . Regular environmenta l f l u c t u a t i o n s such as t i d a l f l o o d i n g and d i u r n a l o r seasonal temperature v a r i a t i o n s should not d i f f e r e n t i a l l y a f f e c t l e v e l s of p o l y p l o i d y , s ince p e r e n n i a l d i p l o i d s should be able to accommodate them as w e l l as comparable p o l y p l o i d s . However, l onge r - t e rm, more u n p r e d i c t -able d i s tu rbances ( shor t of long- te rm c l i m a t i c changes such as warming or c o o l i n g t rends) cou ld s e l e c t i v e l y favor p o l y p l o i d s . I would c l a s s the r a p i d and unp red i c t ab l e changes i n mobi le substratum and topography, c h a r a c t e r i s t i c of s a l t marshes, as f l u c t u a t i o n s of the l a t t e r type . Changes i n drainage and sedimenta t ion pa t te rns f r equen t ly occur i n s a l t marshes and are accompanied by simultaneous e r o s i o n and a c c r e t i o n of mud f l a t s and marsh (Johannessen 19 64; R e d f i e l d 1965, 1972). In a d d i t i o n , s a l t marsh vege t a t i on has been subject to e u s t a t i c r i s e and f a l l i n sea l e v e l r e l a t e d to P l e i s t o c e n e g l a c i a t i o n and de-g l a c i a t i o n (Cooper 1958, 1967; Heusser 1960). Such phys iograph ic changes would be accompanied by both r a p i d es tab l i shment and e l i m i n a t i o n of popu la t ions o f marsh species i n newly a v a i l a b l e or swamped s i t e s , r e s p e c t i v e l y . Subalpine meadows have exper ienced the i n t e r g l a c i a l advance and r e t r e a t of a l p i n e g l a c i e r s , and frequent but unp red i c t ab l e f i r e s (Douglas and B a l l a r d 1971) , l a t e snow packs , summer f r e e z e s , and s o i l d i s turbances by marmots and pocket gophers 68 a l l events tha t may be accompanied by c y c l e s o f e r o s i o n and es tabl i shment o f meadow v e g e t a t i o n i n new, d i s t u r b e d h a b i t a t s . These d i s tu rbances are s i m i l a r , i n type i f not degree, to those of the s a l t marsh. In c o n t r a s t , sphagnum bogs i n t h i s area have no s i m i l a r d i s t u r b a n c e s . Even the r e g u l a r hummock-ho l low c y c l e s of bogs (Gorham 1957; Lawrence 1958) are apparen t ly s e l f -gene ra t ed by the bog s p e c i e s , do not r e s u l t i n any d r a s t i c e r o s i o n , and are more or l e s s p r e d i c t a b l e and s e l f - c o n t a i n e d . I t appears , t hen , tha t the d i f f e r e n t l e v e l s of p o l y p l o i d y i n these three vege t a t i on types are best exp la ined by d i f f e r e n t degrees of environmental i n s t a b i l i t y . H i s t o r i c a l , m i g r a t i o n a l f a c t o r s have s u r e l y been a major cause o f the r e l a t i v e l y h i g h l e v e l of p o l y p l o i d y i n the o v e r a l l geographic a r ea , but have had minimal e f f e c t on d i f f e r e n c e s w i t h i n the a rea . Exp lana t i ons based on i n t r i n s i c p h y s i o l o g i c a l p r o p e r t i e s of p o l y p l o i d s tha t favor them i n extreme environments are t h e o r e t i c a l l y and p r a c t i c a l l y i n a p p r o p r i a t e . Environmenta l i n s t a b i l i t y or u n p r e d i c t a b i l i t y c o u l d , however, r e s u l t i n h igher l e v e l s o f p o l y p l o i d y both because such u n p r e d i c t a b i l i t y i m p l i e s c o n d i t i o n s (newly a v a i l a b l e d i s t u r b e d h a b i t a t s , r a p i d f l u c t u a t i o n s i n p o p u l a t i o n s i z e ) f avorab le f o r h y b r i d i z a t i o n , h y b r i d e s t ab l i shmen t , and es tabl i shment o f a l l o p o l y p l o i d d e r i v a t i v e s , and because the i n c r e a s e d , s t a b i l i z e d gene t i c v a r i a b i l i t y of the a l l o p o l y p l o i d -spec ies would p l ace them at a s e l e c t i v e advantage i n an unpred ic t ab l e environment. D. Flowering phenology. 69 One o f t e n - n e g l e c t e d aspect of p l a n t synecology i s r e p r o d u c t i v e phenology. A l l s p e c i e s t h a t are o u t c r o s s e d to any extent w i l l compete f o r p o l l i n a t i n g agents, whether the agents be b i o t i c or a b i o t i c . The s p e c i e s a l s o w i l l be competing f o r water, l i g h t , and n u t r i e n t s d u r i n g the growing season as they marshal resources f o r the r e p r o d u c t i v e e f f o r t . Phenology should r e v e a l a spectrum of peak f l o w e r i n g times f o r the species o f a p a r t i c u l a r community, a spectrum r e s u l t i n g from competition and an e v o l u t i o n toward niche d i f f e r e n t i a t i o n ( c f . Mosquin 1971). Fig u r e HlA-DJ d e p i c t s the f l o w e r i n g phenologies of a l l the angiospermous s p e c i e s of the s a l t marsh, bogs, and subalpine meadow. Each community was canvassed dur i n g the f l o w e r i n g season at l e a s t t w i c e , and o f t e n t h r e e to f o u r times per week. Each area was t r a v e r s e d and f l o w e r i n g behavior noted along a network of t r a n s e c t s . During the onset and c e s s a t i o n of flower-i n g , rough estimates were made of the p r o p o r t i o n of a p a r t i c u l a r s p e c i e s p o p u l a t i o n t h a t was i n flower. The h o r i z o n t a l bars i n F i g u r e 111A-D are tapered_at. both-, e n d s , p r o p o r t i o n a l to the r a p i d i t y with which the m a j o r i t y o f a g i v e n s p e c i e s p o p u l a t i o n commences and terminates f l o w e r i n g , but the p o p u l a t i o n dynamics probably would be more a c c u r a t e l y represented by more or l e s s normal, b e l l - s h a p e d curves. I t should be emphasized t h a t the blooming p e r i o d i s o n l y one phenophase of many, such as emergence or germination, stem or culm p r o d u c t i o n , formation of u n r i p e seeds and f r u i t s , d i s p e r s a l of r i p e seeds and f r u i t s , y e l l o w i n g of l e a v e s , and death or p a r t i a l dieback, t h a t could Fig. 111. Flowering phenology. 70 b Triglochin maritimum Carex lyngbyei Glaux maritima Stellaria humifusa Deschampsia cespitosa Juncus balticus Plantago maritima Puccinellia pumila Potentilla pacifica Trifolium wormskjoldii Scirpus cernuus Festuca rubra Spergularia canadensis Agrostis exarata Hordeum brachyantherum Lilaeopsis occidentalis Distichlis spicata Salicornia virginica Myrica gale Empetrum nigrum Coptis asplenifolia Carex pluriflora Scirpus cespitosus Coptis trifolia Carex obnupta Kalmia polifolia Gentiana douglasiana Apargidum boreale Trientalis arctica Vaccinium oxycoccus Carex canescens Vaccinium uliginosum Vaccinium vitis-idaea Ledum groenlandicum Agrostis aeguivalvis Tofieldia glutinosa Juncus supiniformis Rhynchospora alba Sanguisorba officinalis Linnaea borealis Drosera rotundifolia Gentiana sceptrum A S a l t M a r s h x = 4 6 d a y s B W a d e ' s B o g x = 3 2 d a y s —i 1 r 10 20 30 APRIL 10 20 MAY __~r 31 —i 1 1-10 20 30 JUNE T" 10 20 JULY 31 10 20 AUGUST —i— 10 31 20 SEPTEMBER Myrica gale Empetrum nigrum Plantago macrocarpa Coptis asplenifolia Eriophorum polystachion Scirpus cespitosus Carex pluriflora Coptis t r i f o l i a Carex obnupta Kalmia polifolia Vaccinium ova turn Apargidium boreale Trientalis arctica Vaccinium oxycoccus Carex canescens Vaccinium uliginosum Vaccinium vitis-idaea Nephrophyllidium crista-galli Carex pauciflora Maianthemum dilatatum Ledum groenlandicum Gentiana douglasiana Agrostis aequivalvis Tofieldia glutinosa Gaultheria shallon Juncus supiniformis Cornus unalas$ch'ensis Rhynohospora alba Desohampsia cespitosa Sanguisorba officinalis Linnaea borealis Drosera rotundifolia Calamagrostis nutkaensis Gentiana sceptrum 's Bog 27 days -J O Q —I ' 1 1 T 10 20 30 10 20 APRIL MAY 31 ^ 1 r 10 20 30 JUNE i 1— 10 20 JULY 31 i r~ 10 20 AUGUST ~I ' r~ 31 10 20 SEPTEMBER 70 Anemone occldentalis Erythronium grandiflorum Claytonia lanceolata Luzula hitchcockii Vaccinium scoparium Phlox diffusa Antennaria lanata Potentilla f l a b e l l i f o l i a Sibbaldia procumbens Vaccinium deliciosum Microsteris gracilis Poa cusickii Ranunculus eschscholtzii Luzula spicata Thalictrum occidentale Carex rossii Senecio integerrimus Hydrophyllum fendleri Lupinus latifolius Epilobium alpinum Potentilla diversifolia Festuca viridula Valeriana sitchensis Arenaria capillaris Castilleja miniata Penstemon procerus Pedicularis bracteosa Delphinium nuttallianum Erigeron peregrinus Veronica cusickii Castilleja parviflora Phleum alpinum Veratrum viride Carex spectabilis Agoseris aurantiaca Juncus drummondii Trisetum spicatum Elymus glaucus Arnica l a t i f o l i a Hieracium gracile Sedum lanceolatum Arnica mollis Achillea millefolium Senecio triangularis Silene parryi Blackwall Meadow 23 days -| 1 1 r-10 20 30 10 ~l 1 « 1 ' ' 1 ' 1 1 1 r 31 10 20 30 10 20 31 10 20 31 10 20 20 APRIL MAY JUNE JULY AUGUST SEPTEMBER 71 be represented i n a complete phenodynamic s t r i p ( L i e t h 1970). F igu re 111A-D confirms the ca sua l impress ion t h a t , w i t h i n a g iven p l an t community, species f l o w e r i n g t imes form a sequence of ove r l app ing i n t e r v a l s o r , more a c c u r a t e l y , ove r l app ing cu rves . Analogous p h e n o l o g i c a l g rad ien t s have been repor ted by Mowbray and Oost ing (1968) and Mosquin (1971). The average blooming p e r i o d l eng th f o r species o f the S a l t Marsh, Wade's Bog, Ogg's Bog, and B l a c k w a l l Meadow i s 4-6, 32, 27, and 23 days , r e s p e c t i v e l y . These lengths r e f l e c t both the number of species per community and the l eng th o f the growing season. The number of angiospermous species i n each of these s i t e s i s , i n o r d e r , 18, 24, 30, and 45 showing an inve r se r e l a t i o n s h i p between the number of spec ies per community and the average l e n g t h of a s p e c i e s ' blooming p e r i o d . The f i r s t th ree s i t e s a l l have about the same long growing season; approximate ly a 5 1/2 month p e r i o d from the beginning o f A p r i l to the middle of September. B l a c k w a l l Meadow, on the other hand, has a growing season compressed i n t o 9-10 weeks from l a t e June to e a r l y September, a t l e a s t i n l a t e snow- l i e y e a r s , as were 1971 and 1972. The short growing season, h i g h number of s p e c i e s , d e n s i t y of f l o w e r i n g i n d i v i d u a l s , and: percentage. ;.of . b i o t i c a l l y -p o l l i n a t e d s p e c i e s , and the consequent s i g n i f i c a n t i n t e r s p e c i f i c over lap of f l o w e r i n g per iods i n the subalp ine meadow suggest tha t meadow spec ies have evolved i n an environment i n t e n s e l y compe t i t i ve f o r animal ( e s p e c i a l l y i n s e c t ) p o l l i n a t o r s , much more so than a s a l t marsh or bog environment. S e l e c t i o n i n such h i g h l y compe t i t i ve c o n d i t i o n s would be f o r f l o r a l s p e c i a l i z a t i o n s 72 tha t would inc rease a f l o w e r ' s a t t r a c t i v e n e s s to animal p o l l i n -a to rs and the p o l l i n a t o r ' s constancy to the f l o w e r . There cou ld a l s o be s e l e c t i o n f o r autogamy ( c f . L e v i n 1972c')-, bu.i;at the expense of long term v a r i a b i l i t y . Thus, the b rea th t ak ing d i s p l a y o f showy f lowers of many forms, c o l o r s , and odors tha t i s c h a r a c t e r i s t i c of l u s h subalp ine meadows i s l o g i c a l i n an e v o l u t i o n a r y con tex t . One might i n t e r p r e t the longer average f l o w e r i n g per iods of the s a l t marsh spec ies as a r e s u l t i n par t of the "pre-ponderance of w i n d - p o l l i n a t e d species i n the marsh. T h e o r e t i c a l l y , a longer blooming season would be of advantage to an anemo-p h i l o u s spec ies s ince wind i s a much l e s s r e l i a b l e p o l l i n a t i n g agent than most animals and a longer f l o w e r i n g p e r i o d would inc rease the chances of succes s fu l p o l l i n a t i o n . However, c a l c u l a t i o n s r e v e a l no s i g n i f i c a n t d i f f e r e n c e , e i t h e r w i t h i n one community or over a l l communit ies , between l eng th o f blooming t imes fo r anemophilous v s . entomophilous spec i e s . There i s , though, a d e f i n i t e tendency f o r autogamous spec ies such as Drosera r o t u n d i f o l i a , Spergularia canadensis, Elymus g.laucus 3 and Hordeum brachy antherum to have shor te r than average an thes i s t i m e s , which i s what one would expec t , s ince autogamy ensures succes s fu l p o l l i n a t i o n . E . P o l l i n a t i o n eco logy . 73 The f o l l o w i n g summary of the p o l l i n a t i o n ecology of the study communities i s based on two summers of f i e l d observa t ions i n 1971 and 1972, and on observa t ions and in fe rences c u l l e d from the l a rge l i t e r a t u r e on the sub jec t . During the growing season I v i s i t e d each of the study areas u s u a l l y two or three times a week to study f l o r a l b i o l o g y and observe and c o l l e c t f lower v i s i t o r s . Many a d d i t i o n a l observa t ions were made w h i l e I was doing the quadrat and t r an sec t p h y t o s o c i o l o g i c a l sampling on o ther occas ions . Table 12 summarizes the o v e r a l l p o l l i n a t i o n scheme i n each of the four sample s i t e s . Each species has been c l a s sed as being p o l l i n a t e d predominant ly by e i t h e r wind (anemophi ly) , i n s e c t s ( en tomophi ly ) , or b i r d s ( o r n i t h o p h i l y ) none are w a t e r - p o l l i n a t e d . The p o l l i n a t i o n mechanisms of- the i n d i v i d u a l species are d i scussed i n d e t a i l i n Appendix 3. TABLE 12. Community mode of p o l l i n a t i o n as percentage o f the f l o r a and v e g e t a t i o n . P o l l i n a t i o n B l a c k w a l l mechanism S a l t Marsh Wade's Bog Ogg's Bog Meadow Anemophily 67%/83.4% a 36/42.6 40/48.2 25/25 Entomophily 33/16.6 64/57.4 60/51.8 72 .7 /74 .4 O r n i t h o p h i l y 2 .3 /0 .6 a% f l o r a / % vege t a t i on (determined from importance v a l u e s ) . 74 C l e a r l y , anemophily i s the major mode of p o l l i n a t i o n i n the s a l t marsh. Entomophily predominates i n the suba lp ine meadow, w h i l e both bogs have more of a balance between i n s e c t and wind p o l l i n a t i o n . The s i t u a t i o n i n the s a l t marsh i s not as c l e a r - c u t as i t seems, however. During both summers of f i e l d work I have observed bumble bee (Bombus terricola occi-dentalis Grne. ) p o l l e n fo rag ing on s i x t y p i c a l l y anemophilous s a l t marsh s p e c i e s : D e s o h a m p s i a o e s p i t o s a , F e s t u o a r u b r a v a r . l i t t o r a l i s , A g r o s t i s e x a r a t a , P l a n t a g o m a r i t i m a , J u n o u s b a l t i o u s , and Salioornia virginica (Pojar 1973b). In g e n e r a l , bumble bees are the most important animal p o l l i n a t i n g vec to r at a l l four s i t e s . D i p t e r a are extremely impor tan t , p a r t i c u l a r l y Syrph idae , Muscidae, and Bombylidae. L e p i d o p t e r a , e s p e c i a l l y b u t t e r f l i e s and sk ippe r s (Rhopalocera) , are a l s o of major s i g n i f i c a n c e i n the suba lp ine meadow, but i t i s s t range tha t there are very few b u t t e r f l i e s i n the Tof ino area . I t i s a l s o noteworthy tha t none of the nine spec ies (.Puccinellia p u m i l a , S p e r g u l a r i a c a n a d e n s i s ( F i g . 112) , H o r d e u m b r a o h y a n t h e r u m , D r o s e r a r o t u n d i f o l i a ( F i g . 113) , E l y m u s g l a u c u s , E p i l o b i u m a l p i n u m , M i o r o s t e r i s g r a c i l i s , and S i b b a l d i a prooumbens) t ha t are f u l l y or predominant ly autogamous ( s e l f - p o l l i n a t i n g ) are dominant elements i n t h e i r communities. From q u a l i t a t i v e es t imates of p o l l i n a t o r d e n s i t y and a c t i v i t y I f e e l t ha t i n a l l of these communities the i n s e c t s are the l i m i t i n g f a c t o r i n the r e p r o d u c t i o n of many entomo-p h i l o u s s p e c i e s . That i s , I b e l i e v e tha t there i s compe t i t i on among f lowers f o r p o l l i n a t o r s r a t h e r than among i n s e c t s f o r 75a, F i g . 112. Spergularia canadensis; chasmogamous, s e l f -p o l l i n a t i n g f l o w e r . I n d i v i d u a l p l an t s o f ten have both chasmogamous and cle is togamous f l o w e r s . F i g . 113. Drosera-rotundpfoli'a; s h o r t - l i v e d , . chasmogamous , s e l f - p o l l i n a t i n g f l o w e r . Two cleis togamous f lowers can be seen j u s t above the open f l o w e r . 76 nec ta r and p o l l e n . This seems p a r t i c u l a r l y t rue i n B l a c k w a l l Meadow, which has a l a rge number of entomophilous species and an extremely h i g h d e n s i t y of s imul taneous ly-b looming f lowers (see F i g s . 6 8 7 ) . Mosquin (1971) concluded t h a t , at l e a s t dur ing midsummer, the f l o r a o f a mountain v a l l e y near Banff competed s t r o n g l y f o r p o l l i n a t o r s , and some spec ies were unsuccess fu l i n the c o m p e t i t i o n . Hocking (19 68) and Kevan (1970, 1972) have noted a r e l i a n c e of f lowers on p o l l i n a t i n g i n s e c t s i n h i g h a r c t i c v e g e t a t i o n , w h i c h , i n d e n s i t y and showiness of f lowers and compressed growing season, i s somewhat s i m i l a r to suba lp ine meadow v e g e t a t i o n . Undoubtedly, i n t e r s p e c i f i c compe t i t i on has p layed a major r o l e i n the e v o l u t i o n o f showy f l o w e r s , as w e l l as p r e s su r ing some species i n t o the escapism of autogamy ( L e v i n 197 2 c ) . Another p o s s i b l e advantage of the showy f lowers of some subalp ine spec ies has been suggested by Hocking and S h a r p l i n (1965) and Kevan (1970). They have found tha t the i n t r a f l o r a l temperatures of l a r g e showy f lowers are g e n e r a l l y above the ambient i n the a r c t i c , and under optimum c o n d i t i o n s the temperatures i n f lowers shaped l i k e p a r a b o l i c r e f l e c t o r s can exceed the ambient by 5 ° ' t o 10° C ( B l i s s 1971). In B l a c k w a l l Meadow, bowl-shaped f lowers l i k e those of Potentilla diversi-f o l i a , P. f l a b e l l i f o l i a ( F i g . 114)., R a n u n c u l u s e s c h s c h o l t z i i 3 and Anemone occidentalis serve as basking s i t e s f o r the va r ious d ip t e rans tha t are the p r i n c i p a l p o l l i n a t o r s of these s p e c i e s . Th i s f l ower bask ing i s probably most important t o the i n s e c t s du r ing e a r l y morning i n the mountains, when the sun i s up but the a i r temperature s t i l l low. Kevan (197 0) has suggested tha t 77 F i g . 114. Potentilla flabellifolia. S l i g h t l y protogynous f l o w e r ; nec ta r sec re ted as a t h i n , s h i n i n g f i l m on the b l a c k i s h - p u r p l e d i s c j u s t i n s i d e the f i l amen t bases . Bowl-shaped blossomrserves as bask ing s i t e f o r i n s e c t s . F i g . 115. Plantago maritima. S t rong ly protogynous, anemo-p h i l o u s flowers, borne i n a dense, a c r o p e t a l l y -f l o w e r i n g s p i k e . Note the e longate stigmas and w e l l - e x s e r t e d , v e r s a t i l e an thers . 78 the h igher i n t r a f l o r a l temperatures i n gene ra l may a l s o be important fo r p o l l e n tube growth, f e r t i l i z a t i o n , and p o s s i b l y seed development. A t h e o r e t i c a l aspect o f i n t e r s p e c i f i c compe t i t i on f o r p o l l i n a t o r s has been exp lored i n models by L e v i n and Anderson (1970) and Straw (1972). Both models have e s s e n t i a l l y the same i n i t i a l assumptions: (1) two randomly i n t e r m i x e d , s imul taneous ly f l o w e r i n g , s e l f - i n c o m p a t i b l e spec ies w i t h f lowers s u f f i c i e n t l y s i m i l a r t o a t t r a c t the same p o l l i n a t o r s ; (2) a s i n g l e p o l l i n a t o r spec ies to s e r v i c e both p l an t s p e c i e s ; (3) a d e f i c i t o f p o l l i n a t o r s r e l a t i v e to the number of f l o w e r s . Then, i f the r a t e of r e p r o d u c t i o n o f each f lower species 'depends on i t s success i n the compe t i t i on fo r p o l l i n a t o r s , the frequency o f a spec ies i n subsequent generat ions w i l l be p r o p o r t i o n a l to the degree of p o l l i n a t o r constancy to tha t spec ies , and the l e s s favored species e v e n t u a l l y should be e l i m i n a t e d . I f p o l l i n a t o r constancy i s d e n s i t y dependent ( c f . L e v i n and K e r s t e r 1969a), the m i n o r i t y spec ies w i l l be at an inc reased disadvantage and i t s compe t i t i ve e x c l u s i o n should be a c c e l e r a t e d (Straw 1972). The f i r s t two requirements f o r t h i s type of compe t i t i ve e x c l u s i o n r a r e l y , i f a t a l l , e x i s t i n nature (Crosswhi te and Crosswhi te 19 7 0 ; ;Macior" 1971; Straw 1972). In the study communit ies, assumption (3) seems to be v a l i d , e s p e c i a l l y f o r the suba lp ine meadow. In the meadow, there are two spec ies p a i r s , A r n i c a l a t i f o l i a v s . A. m o l l i s and S e n e c i o i n t e g e r r i m u s v s . S. triangularis, t ha t have s i m i l a r f lowers and p o l l i n a t o r s and are a l l s e l f - i n c o m p a t i b l e . However, they do not r e l y on a s i n g l e p o l l i n a t o r spec ies but r a t h e r are s e r v i c e d by a v a r i e t y of 79 Hymenoptera, D i p t e r a , and L e p i d o p t e r a ; they are "cornucopian" f lowers i n the sense of Mosquin (1971). Nor are these spec ies randomly i n t e rmixed A r n i c a m o l l i s and S e n e c i o i n t e g e r r i m u s g e n e r a l l y occur on d r i e r s i t e s w i t h i n the meadow than t h e i r congeners. Fur thermore, S. integerrimus f lowers much e a r l i e r i n the season than the o ther three s p e c i e s , which are more or l e s s s imul taneous ly l a t e - f l o w e r i n g . In the study communit ies, these spec ies p a i r s are the c l o s e s t approaches to the t h e o r e t i c a l assumptions, and c l e a r l y the approaches are q u i t e remote. N e v e r t h e l e s s , i t i s safe t o say tha t avoidance of i n t e r s p e c i f i c compe t i t i on f o r p o l l i n a t o r s , by s h i f t i n g of f l o w e r i n g p e r i o d and/or h a b i t a t preference and/or p o l l i n a t i n g agent , has been i n s t rumen ta l i n the e v o l u t i o n of p l a n t species i n g e n e r a l . In p a r t i c u l a r , i t i s r e f l e c t e d i n the s p a t i a l d i s t r i b u t i o n s and phenology o f the spec ies o f the study a reas , and moreover i s much more apparent and presumably p lays a much more important r o l e i n the suba lp ine meadow than i n the s a l t marsh or bogs. Types o f p o l l i n a t i o n Gross f l o r a l morphology should be regarded as r e s u l t i n g from adapta t ions fo r f e r t i l i z a t i o n from f lowers of d i f f e r e n t i n d i v i d u a l s of the same spec ies (Darwin 1876, 1877; Whitehouse 1959). The except ions to t h i s gene ra l r u l e ( e g . , as occur i n s e l f - f e r t i l i z i n g spec ies ) are g e n e r a l l y regarded as secondary adapta t ions f o r the sake of g rea te r c e r t a i n t y o f seed p roduc t ion of a more or l e s s uni form genotype (Stebbins 19 50, 1957a; Grant 19 71)...The .adaptive nature .of t h e ' f l o w e r must be 80 apprec ia t ed i n a d i s c u s s i o n of p o l l i n a t i o n eco logy , but the t empta t ion to specu la te on the adapt ive func t ions of va r ious f l o r a l s t r u c t u r e s tha t defy l o g i c a l e v o l u t i o n a r y i n t e r p r e t a t i o n should be r e s i s t e d . The i n t e r p r e t a t i o n of the f lower as a f u n c t i o n a l r e p r o d u c t i v e u n i t has l e d to the d e s c r i p t i o n of morpho log ica l c a t e g o r i e s f o r f lower forms r e l a t e d to t h e i r p o l l i n a t i o n ecology t hus , we have "bee f l o w e r s " , " f l y f l o w e r s " , "bee t le f l o w e r s " , and the l i k e . Crosswhite and Crosswhi te (1966) and Macior (1971) have po in t ed out the danger o f such a t y p o l o g i c a l approach, f o r many p l a n t spec ies u t i l i z e a wide v a r i e t y o f p o l l i n a t o r s and are not r e s t r i c t e d to one p a r t i c u l a r v e c t o r . This danger should be kept i n mind dur ing the f o l l o w i n g d i s c u s s i o n , s i nce I s h a l l be r e f e r r i n g to "bumble bee f l o w e r s " , e t c . , w h i l e o u t l i n i n g the p o l l i n a t i o n mechanisms c h a r a c t e r i s t i c o f c e r t a i n types of blossoms. C e r t a i n combinat ions of p o s i t i v e l y c o r r e l a t e d charac te r s or fea tures make up a p a r t i c u l a r syndrome ( F a e g r i and van der P i j l 19 71) corresponding to each of the f o l l o w i n g p o l l i n a t i o n s t r a t e g i e s . The o u t l i n e i s tha t o f F a e g r i and van der P i j l (1971); the examples are from the study communities. Anemophily Wind p o l l i n a t i o n or anemophily i s the dominant type o f a b i o t i c p o l l i n a t i o n i n p l a n t s , and i s the only type t ha t occurs i n the study communit ies , there being no w a t e r - p o l l i n a t e d s p e c i e s . The syndrome of anemophily i n c l u d e s the f o l l o w i n g 81 fea tures (Whitehead 19 69; F a e g r i and van der P i j l 19 71; P roc to r and Yeo 1973): the f lowers tend to be o f s m a l l s i z e , reduced and inconsp i cuous , to l a c k nectar and odor , and to be c l u s t e r e d i n dense i n f l o r e s c e n c e s ; the anthers have abundant, l i g h t , dry p o l l e n , and the stigmas have an expanded surface a rea . Anemo-p h i l o u s spec ies are f r equen t ly u n i s e x u a l , perhaps because s e l f -p o l l i n a t i o n i n an he rmaphrod i t i c , w i n d - p o l l i n a t e d f lower would be i n e v i t a b l e w i t h such a h i g h i nc idence of p o l l e n per u n i t area i n the immediate v i c i n i t y of the anthers ( F a e g r i and van der P i j l 1971). Then t o o , when p o l l e n i s the i n s e c t a t t r a c t a n t , the e v o l u t i o n o f u n i s e x u a l f lowers should tend toward anemo-p h i l y , s i nce entomophilous p l an t s would su f f e r a r e d u c t i o n i n the number of i n s e c t v i s i t s to female f lowers (Kaplan and Mulcahy 1971). U n i s e x u a l f lowers are found i n such wind-p o l l i n a t e d spec ies as M y r i c a g a l e , E m p e t r u m n i g r u m , C a r e x spp., and Thalictrum occidentale. I f an anemophilous spec ies has hermaphrodi t ic f l o w e r s , these are f r equen t ly s t r o n g l y dichogamous e g . , P l a n t a g o m a r i t i m a ( F i g . 115) and P. m a c r o c a r p a , S a l i c o r n i a v i r g i n i c a ( F i g . 116a S b ) , T r i g l o c h i n m a r i t i m u m , J u n c u s spp. ( F i g . 117) , L u z u l a s p p . , and S c i r p u s c e s p i t o s u s ( F i g . 118) . The genus Thalictrum p rov ides e x c e l l e n t examples of these t r ends . Kaplan and Mulcahy (19 71) showed tha t the d i o e c i o u s and p o l y -gamous spec ies of Thalictrum are i n gene ra l the most anemo-p h i l o u s , w h i l e hermaphrodite species are the most entomophilous. Fur thermore, the hermaphrodite Thalictrum species are d i c h o -gamous (Faeg r i and van der P i j l 1971). F i n a l l y , as an e c o l o g i c a l c o r o l l a r y , wind p o l l i n a t i o n most o f t en predominates i n open v e g e t a t i o n w i t h clumped species d i s t r i b u t i o n s (Whitehead 19 69) . C O F i g . 116a. S a l i c o r n i a v i r g i n i c a ; protogynous F i g - 116b. S a l i c o r n i a v i r g i n i c a ; f lowers f l o w e r s , here i n female stage i n male stage (anthers (st igmas r e c e p t i v e ) . ex se r t ed , shedding p o l l e n ) . F i g . 117. J u n o u s b a l t i o u s ; s t r o n g l y F i g . 118 protogynous , anemophilous f l o w e r s . CO CO 8 Seivpus oespitosus ; s t r o n g l y protogynous , anemophilous f lowers u n i t e d i n a s e v e r a l -f lowered , s o l i t a r y , t e r m i n a l s p i k e l e t . Male stage i n mid-foreground; female stage behind and to the l e f t . 84 Most of the s a l t marsh spec ies are e x c e l l e n t examples o f anemophiles , and the marsh i t s e l f i s a predominant ly wind-p o l l i n a t e d community. However-, as mentioned be fo re , s i x : t y p i c a l l y anemophilous s a l t marsh species are a l s o v i s i t e d by p o l l e n - f o r a g i n g bumble bees. Pojar (1973b) has d i scussed the p o s s i b l e s i g n i f i c a n c e o f t h i s f o r t u i t o u s entomophi ly . The s i t u a t i o n i s advantageous to the p l a n t s , s i n c e : t h e e f f i c i e n c y of wind p o l l i n a t i o n must be c o n s i d e r a b l y reduced i n the humid oceanic c l i m a t e o f the Tof ino a rea . The bumble bees seem to have responded to a p a u c i t y of p o l l e n - r i c h entomophilous f lowers by s h i f t i n g t h e i r p o l l e n - g a t h e r i n g a c t i v i t i e s to spec ies t h a t , i n most o ther c i r cums tances , would be ignored . Anemophily i s now g e n e r a l l y cons idered to be a d e r i v e d c o n d i t i o n i n angiosperms (Whitehead 1969; Kugle r 1970; Stebbins 1970a; F a e g r i and van der P i j l 1971). Apparent r e v e r s i o n s from wind p o l l i n a t i o n to secondary entomophily have occur red i n the t r o p i c a l sedge Dichromena oiliata (Leppik 1955; Baker 1963), i n c e r t a i n t r o p i c a l r a i n f o r e s t grasses (Soderstrom and Calderon 1971), inr ' the geniis -.Salix, and e x t e n s i v e l y i n the f a m i l y Moraceae (Stebbins 1970a). Other observers have noted p o l l e n -fo rag ing v i s i t s by honey bees (Bogdan 19 62) and hover f l i e s ( C l i f f o r d 1964) to grass f l o w e r s , and by honey bees to Plantago lanceolata ( C l i f f o r d 1962). In c o n t r a s t , adapt ive s h i f t s from i n s e c t to wind p o l l i n a t i o n are a l s o apparent i n some groups. The genera Plantago and Thalictrum both c o n t a i n i n s e c t - and w i n d - p o l l i n a t e d s p e c i e s , and the anemophily e v i d e n t l y i s de r i ved and of f a i r l y recen t o r i g i n (S tebbins-1970a; F a e g r i and van der P i j l 1971; Kaplan 85 and Mulcahy 1971). In the study communties, Plantago maritima, P. m a c r o c a r p a , and T h a l i c t r u m o o c i d e n t a l e ( F i g . 119a & b) are a l l predominant ly w i n d - p o l l i n a t e d . Thalictrum (Ranunculaceae) and Sanguisorba (Rosaceae) are two genera tha t belong to over -whelmingly entomophilous f a m i l i e s , but never the less c o n t a i n some anemophilous species (Knuth 1906-1909; Stebbins 1970a). Sanguisorba officinalis ( F i g . 120) , a t a l l p e r e n n i a l herb o f the sphagnum bogs, has apetalous f lowers w i t h lobed stigmas and the f lowers are aggregated i n a dense i n f l o r e s c e n c e . But the deep maroon-purple f lowers are markedly n e c t a r i f e r o u s , have s t i c k y (not powdery) orange p o l l e n , and are p o l l i n a t e d by d i p t e r a n s . S. officinalis represents a c o n d i t i o n in te rmedia te between anemophily and entomophi ly , and the d i r e c t i o n of the adap t ive s h i f t can o n ly be presumed, a l though the m a j o r i t y o f Sanguisorba spec ies are w i n d - p o l l i n a t e d (Stebbins 1970a). F l y p o l l i n a t i o n (myophily) There i s great v a r i a t i o n i n the p o l l i n a t i o n methods employed by D i p t e r a . There are many u n s p e c i a l i z e d f l i e s , o f sma l l s i z e and w i t h shor t probosces , t ha t are g e n e r a l l y r e s t r i c t e d - , to more " p r i m i t i v e " f lowers w i t h e a s i l y a c c e s s i b l e nec ta r . Blossoms c h a r a c t e r i s t i c a l l y p o l l i n a t e d by these s m a l l , u n s p e c i a l i z e d f l i e s form a f a i r l y d i s t i n c t type of f l y f l o w e r , a l though they are a l s o v i s i t e d by many sma l l hymenopterans (Kugle r 1955). The syndrome of t h i s type of myophily i n c l u d e s r e g u l a r , s i m p l e , g e n e r a l l y l i g h t but d u l l - c o l o r e d f lowers w i t h l i t t l e or no depth e f f e c t . The nec ta r i s very a c c e s s i b l e , the oo CD F i g . 119a. Thalictvum occidentale . Male F i g . 119b. Thaliotrum o c c i d e n t a l e . Female f l o w e r s . f lowers (stigmas a l ready w i t h e r e d ) . Th i s i s a d i o e c i o u s , anemophilous spec i e s . Note the elongate s t igmas , the e longa te , pendent stamens, and the reduced, inconspicuous f lowers which are ape t a lous , w i t h g r een i sh -wh i t e , caducous sepals ( f a l l e n o f f i n female f l o w e r s ) . 87a, Fig. 120. S a n g u i s o r b a . o f f i o i n a l i s ; flowers apetalous, sepals maroon to deep maroon purple; the s t i c k y , orange pollen i s often shed i n bud. Fig. 121. T r i e n t a l i s a r c t i o a ; the white petals form a shallowly bowl-shaped star; the thick, fleshy, stamen-bearing r i n g i s a t t r a c t i v e to f l i e s . <rrb 88 f lowers have no s t rong odor , and the sexua l organs are w e l l -exposed. Examples are the f lowers of Potentilla flabellifolia ( F i g . 114) , T r i e n t a l i s a r o t i o a ( F i g . 121) , S t e l l a r i a h u m i f u s a , C o p t i s . a s p l e n i f o l i a and C. t r i f o l i a ( F i g . 122) , and V e r a t r u m v i r i d e ( F i g . 123). In the s a l t marsh, P o t e n t i l l a p a o i f i o a i s p o l l i n a t e d p r i m a r i l y by bumble bees and bee f l i e s , w h i l e the subalp ine meadow spec ies P. diversifolia and P. flabellifolia are v i s i t e d on ly r a r e l y by bumble bees ( sma l l f l i e s and syrph ids are t h e i r most frequent p o l l i n a t o r s ) . Potentilla paoifioa i s , bes ides Trifolium wormskgoldii , the on ly showy f l o w e r i n the s a l t marsh. In the suba lp ine meadow there are many showy entomophilous ( i n c l u d i n g bombophilous) f l o w e r s . Since the f lowers of a l l three Potentilla species are very s i m i l a r , the d i f f e r e n c e i n p o l l i n a t o r s i s p robably due i n pa r t to a s h i f t i n g of the bumble bees ' and bee f l i e s ' a t t e n t i o n s to more h i g h l y s p e c i a l i z e d , more rewarding f lowers as an o p t i m a l e f f i c i e n c y response to p o l l i n a t o r compe t i t i on i n the suba lp ine meadow. In the s a l t marsh, the i n s e c t s have to take whatever i s a v a i l a b l e , w h i l e i n the suba lp ine meadow there i s a wea l th of f lowers to choose from. A d i f f e r e n t type of f l y . f l o w e r (sapromyophilous) a t t r a c t s f l i e s ( u s u a l l y c a r r i o n - and d u n g - f l i e s ) w i t h f o u l odors resembl ing tha t of decaying p r o t e i n . Sapromyophilous blossoms are g e n e r a l l y r a d i a l and f r e q u e n t l y the p e r i a n t h pa r t s have f i l i f o r m h a i r s or o ther appendages ( e g . , Menyanthes trifoliata). D u l l , p u r p l i s h or brownish f l o r a l c o l o r s are o f t en found i n a s s o c i a t i o n w i t h the odor of p u t r e f a c t i o n . Examples of sapro-myophilous spec ies i n the study communities are Nephrophyllidium 89cv F i g . 122. Coptis trifolia. The sepals are whi te and p e t a l o i d , w h i l e the p e t a l s are about h a l f the l eng th of the s e p a l s , f l e s h y , hol lowed and n e c t a r i f e r o u s at the t i p s , and shaped l i k e t h i c k , woolen m i t t e n s . F i g . 12 3. Veratrum viride. Weakly protandrous f lowers w i t h y e l l o w - g r e e n to deep green t epa l s tha t have n e c t a r i e s at t h e i r bases . 90 o r i s t a - g a l l i 3 L y s i a h i t u m a m e r i c a n u m 3 A n t e n n a r i a l a n a t a , and perhaps Sanguisorba officinalis. A l l of these species have f lowers tha t f i t the syndrome i n some, but not a l l , p a r t i c u l a r s Nephrophyllidium orista-galli ( F i g . 124) has w h i t e , s h o r t -t u b u l a r , c o p i o u s l y n e c t a r i f e r o u s f lowers w i t h f r i n g e d c o r o l l a l obes . The f lowers have (to me) a s t rong sour odor of mildewed laundry and the p e t a l s de l iquesce w i t h i n a few days o f an thes i s The f lowers are v i s i t e d e n t h u s i a s t i c a l l y by l a r g e and s m a l l muscid f l i e s . The f lower of Lysiahitum amerioanum ( F i g . 125) emits a powerful skunky odor , and f l i e s as w e l l as numerous bugs and bee t l e s are a t t r a c t e d to the b r i g h t y e l l o w spathes and f l e s h y , g r e e n i s h - y e l l o w spadices , o f t en c r a w l i n g about the f lowers by the hundreds. Antennaria lanata, a d ioec ious spec ies has d i r t y g r e e n i s h - w h i t e , s t r o n g l y n e c t a r i f e r o u s f lowers tha t s m e l l of bad cheese or d i r t y socks . The f lowers are v i s i t e d by s m a l l muscid f l i e s and o c c a s i o n a l l y by s y r p h i d s . The deep maroon-purple , h i g h l y n e c t a r i f e r o u s f lowers of Sanguisorba officinalis ( F i g . 120) are p o l l i n a t e d by sma l l muscid f l i e s , m a i n l y . The p u r p l i s h c o l o r suggests tha t the f lowers should a l s o have a f o u l s m e l l , but I cou ld de tec t none. The w a s p - l i k e Syrphidae or h o v e r f l i e s are more s p e c i a l i z e d D i p t e r a . V e r o n i c a c u s i c k i i ( F i g . 126) and V. w o r m s k j o l d i i are two spec ies i n B l a c k w a l l Meadow tha t seem to be p o l l i n a t e d almost e x c l u s i v e l y by syrphids ( c f . P roc to r and Yeo 197 3 ) . The b l u e - v i o l e t f lowers o f both species are qu i t e s i m i l a r , w i t h a shor t c o r o l l a tube tha t s to res and conceals nec tar sec re ted by a d i s c below the ovary . The consp icuous ly exser ted s t y l e i s d i r e c t e d o b l i q u e l y downward, and the two stamens 91o/ F i g . 124. Nephrophyllidium o r i s t a - g a l l i , a d i s t y l o u s s p e c i e s . A l o n g - s t y l e d f lower i s p i c t u r e d here . Note the copious nectar and the erose-undula te membranes on the margins and midnerves o f the c o r o l l a l obes . F i g . 125. Lysichitum ameriaanum has meph i t i c f lowers w i t h a t h i c k f l e s h y spadix subtended by a b r i g h t y e l l o w spathe. ID F i g . 126. V e r o n i c a c u s i c k i i . Note the c l e a n , F i g . 127. V a l e r i a n a s i t c h e n s i s has s h o r t -spare l i n e s of the f l o r a l t u b u l a r f lowers aggregated i n a r c h i t e c t u r e . heads. 93 d ive rge l a t e r a l l y . As Knuth (19 06-19 09) p o i n t s o u t , the f lowers are admirably s u i t e d f o r v i s i t s from h o v e r f l i e s t h a t , i n a l i g h t i n g on the lower c o r o l l a l o b e , f i r s t touch the st igma w i t h t h e i r v e n t r a l su r faces . As the h o v e r f l y s e t t l e s , i t s e i ze s the t h i n bases of the f i l a m e n t s , drawing them together and dus t ing i t s unders ide w i t h a f r e s h load of p o l l e n . Bombylidae or bee f l i e s are h i g h l y s p e c i a l i z e d D i p t e r a and most o f the spec ies have l o n g , s l e n d e r , r i g i d probosces s u i t e d f o r nec ta r feeding at l a r g e , t u b u l a r f lowers (P roc to r and Yeo 1973). Bee f l i . e s are common p o l l i n a t o r s o f Valeriana sitohensis ( F i g . 127) and the showy-flowered Compositae l i k e ATpargidium"- b.ore ale., (Fig . -v l28 ) , Erigeron peregrinus ( F i g . 129) , and-both of the Arnica and Senecio species tha t occur i n B l a c k w a l l Meadow. These spec ies a l l have heads o f s h o r t - t u b u l a r f l ower s . They a l l produce so.-".much nectar tha t i t r i s e s to the top of the f l o r a l tube and i s thus a c c e s s i b l e to both l o n g -and shor t - tongued i n s e c t s . P r e d i c t a b l y , the f lowers are v i s i t e d by a wide range of i n s e c t p o l l i n a t o r s : bumble bees , bee f l i e s , h o v e r f l i e s , s m a l l muscid f l i e s , shor t - tongued bees, and b u t t e r f l i e s and s k i p p e r s . An adapt ive aspect of such a spectrum of p o l l i n a t o r s i s the l i k e l i h o o d t ha t between-plant f l i g h t s w i l l be encouraged and o u t c r o s s i n g thus promoted. I n d i v i d u a l i n s e c t s tend to v i s i t a l l o f the rewarding f lowers w i t h i n a p a r t i c u l a r head before f l y i n g on to another head. A l a r g e number and v a r i e t y of p o l l i n a t o r s would decrease the average number of rewarding f lowers pea?.""head and force i n s e c t s to v i s i t more p l a n t s . Th i s would be a r e a l advantage t o spec ies w i t h aggregated f l o w e r s , e s p e c i a l l y those t h a t , l i k e Valeriana 94c F i g . 1 2 8 . Apargidium boreale. The f lowers are a l l l i g u l a t e and zygomorphic, and the head or cap i tu lum i s c a p i t a t e (see Leppik 1 9 6 0 ) . F i g . 1 2 9 . Erigeron peregrinus. The ye l low-orange d i s c f lowers are s te reomorphic , the l i g h t p ink ray f lowers are zygomorphic, and the cap i tu lum i s ac t inomorph ic . 95 s i t c h e n s i s , are s e l f - c o m p a t i b l e and s u s c e p t i b l e to geitonogamy ( s u c c e s s f u l p o l l i n a t i o n between two f lowers on the same p l a n t ) . Ant p o l l i n a t i o n (myrmecophily) Ants (Hymenoptera, Formicidae) are nea r -ub iqu i tous i n s e c t s f r equen t ly found i n the v i c i n i t y o f f l o w e r s , but are more than l i k e l y nec tar t h i eves r a t h e r than l e g i t i m a t e p o l l i n a t o r s (Faegr i and van der P i j l 19 71; P r o c t o r and Yeo 197 3) . Since ants are u s u a l l y s m a l l and have smooth, hard b o d i e s , they are p o o r l y s u i t e d fo r p i c k i n g up and t r a n s p o r t i n g p o l l e n . True myrmecophily i s d i f f i c u l t to e s t a b l i s h , but I have seen ants p o l l i n a t i n g Glaux maritima ( F i g . 130) i n the s a l t marsh, and i n t h i s am cor robora ted by s i m i l a r observa t ions by Dahl and Hadac ( repor ted i n Faegr i .„and van der P i j l 1971) i n Norway. Bumble bee p o l l i n a t i o n (bombophily) Bumble bees (Hymenoptera, Bombidae, Bombus) are among the few i n s e c t s w i t h the s i z e , s t r e n g t h , and i n t e l l i g e n c e to u t i l i z e the most compl ica ted bee f l o w e r s . T h e i r s t r eng th and the l eng th o f t h e i r mouthparts enable them to take nec ta r tha t i s g e n e r a l l y concealed i n f l o r a l tubes or spurs and of ten ba r r i caded by f l o r a l pa r t s tha t must be pushed as ide to ga in the nec t a r . H i g h l y s p e c i a l i z e d bumble bee f lowers tend to be zygomorphic w i t h great depth e f f e c t , and mechan ica l ly s t rong w i t h good l a n d i n g p l a t f o r m s . Flower c o l o r i s g e n e r a l l y b r i g h t y e l l o w or b l u e , and v i s u a l or mechanical nec tar guides are 96<v F i g . 130. Glaux m a r i t i m a . A low-growing s a l t marsh spec ies w i t h s m a l l , w h i t e , myrmecophilous f l o w e r s . F i g . 131. Delphinium n u t t a l l i a n u m . Bombophilous f l o w e r s . Note the zygomorphy, deep b lue c o l o r , l and ing p l a t f o r m , and nec ta r spur of the f l o w e r . 97 of ten present . Nectar and sexua l organs u s u a l l y are w e l l concealed and f lower odors are f r e s h and sweet. T y p i c a l bumble bee f lowers i n t h i s i n v e s t i g a t i o n are Delphinium nuttallianum, Lupinus latifolius, Gentiana sceptrum, Trifolium wormskjoldii, Pedicularis bracteosa, and Castilleja parviflora v a r . albida. Delphinium, Gentiana, Trifolium, and Castilleja a l l have f lowers w i t h f a i r l y long n e c t a r - c o n t a i n i n g f l o r a l tubes or spurs . Delphinium nuttalli'anum ( F i g . 131) has a s i n g l e spur up to 2 0 mm long i n each deep blue f l o w e r . The spur i s formed from processes o f the two upper p e t a l s and i s enclosed i n the upper s e p a l , which i s i t s e l f spur red . The a n t e r i o r , u p w a r d l y - f l a r e d pa r t s of the two upper p e t a l s bar the entrance to the spur and, toge ther w i t h the s p u r ' s l e n g t h , deny access to shor t - tongued i n s e c t s . Fur the r d e s c r i p t i o n o f the i n t r i c a t e f l o r a l mechanism of D. nuttallianum can be found i n Appendix 3. Gentiana sceptrum has l a r g e , deep - tubu la r , b lue (of ten s t reaked or mot t led w i t h green , e s p e c i a l l y i n s i d e ) f lowers tha t s m e l l s t r o n g l y of v a n i l l a or coumarin ( F i g . 132a). The c o r o l l a tube i s 30-40 mm long w i t h an entrance 10-15 mm broad ; du r ing d u l l weather the c o r o l l a c lo se s up ( F i g . 132b). Nectar i s secre ted at the base of the ova ry , around the gynophore. A t about i t s middle the c o r o l l a tube c o n t r a c t s somewhat and, together w i t h the ep ipe ta lous stamens, l o o s e l y envelops the s t i p i t a t e p i s t i l . The f lowers are s t r o n g l y pro tandrous ; the e x t r o r s e l y - d e h i s c e n t anthers enclose the immature s t y l e w h i c h , as i t matures, e longates and bears the two u l t i m a t e l y - r e f l e x e d s t i g m a t i c lobes above the an the r s . Bumble bees c r awl i n t o the f lowers and probe i n t o the bottom, c o n s t r i c t e d h a l f o f the 98cv F i g . 132a. Gentiana seeptrum. A view of the deep c o r o l l a tube. F i g . 132b. Gentiana seeptrum. The flowers are c l o s e d due to o v e r c a s t , r a i n y weather. 99 c o r o l l a fo r nec t a r . The head of Trifolium wormskjoldii i s made up of numerous, s m a l l , p ink to r ed -pu rp l e f lowers t h a t , because of the d i f f i c u l t y of access to the n e c t a r , are p o l l i n a t e d almost e x c l u s i v e l y by bumble bees. The c o r o l l a i s connate t o the f i l amen t tube f o r nea r ly the e n t i r e l eng th of the stamens, so tha t the lower pa r t of the c o r o l l a forms a narrow, s t i f f tube. The consequence i s tha t i n s e c t v i s i t o r s can put on ly t h e i r heads i n s i d e the f l o w e r , and a f a i r l y long p robosc i s i s r e q u i r e d to reach the bottom of the c o r o l l a tube. The fused p e t a l s of Castilleja parviflora form a t rue n e c t a r i f e r o u s tube. The c o r o l l a lobes are reduced so tha t the lower l i p i s represented by three t e e th w h i l e the upper l i p forms a s m a l l hood i n c l u d i n g the anthers and most o f the s l i g h t l y exser ted s t y l e . The a t t r a c t i v e f u n c t i o n i n Castilleja has been assumed by showy b r a c t s , which i n C. parviflora va r . albida are creamy whi te to p i n k i s h . L u p i n u s l a t i f o l i u s and P e d i c u l a r i s b r a c t e o s a both have g u l l e t - t y p e (Faeg r i and van der P i j l 1971) bumble bee blossoms, but they d i f f e r s t r i k i n g l y i n t h e i r p o l l i n a t i o n mechanisms. The b r i g h t blue pap i l ionaceous f lowers of L. latifolius ( F i g . 13 3) are n e c t a r l e s s but have a marked sweet f r agrance . The two lower , innermost p e t a l s are connate a long t h e i r adjacent margins and toge ther form the k e e l tha t envelops the 10 stamens. The anthers of the f i v e outer stamens dehisce before an thes i s and t h e i r p o l l e n i s s to red i n the ho l low cone c o n s t i t u t e d by the t i p o f the k e e l . Under the weight o f a bumble bee p o l l i n a t o r , the f i v e inne r stamens' ac t as p i s t o n s , ex t rud ing a 100 «, Fig. 133. L u p i n u s l a t i f o l i u s . Note the orange pollen at the t i p of the keel, pushed out by the piston mechanism of the flower. Fig. 134. P e d i o u l a r i s b v a o t e o s a . The galea i s short-beaked and helmet-shaped, the style well exserted. 101 s t r i n g of p o l l e n from the k e e l apex ( F i g . 133) and d e p o s i t i n g i t on the v i s i t o r ' s unde r s ide ; i . e . , s t e r n o t r i b i c a l l y . The st igma a l s o prot rudes at a l a t e r s tage , so tha t c r o s s i n g can be e f f ec t ed (Knuth 1906-1909). The genus Pedioularis e x h i b i t s a s t r i k i n g s e r i e s of both p h e n o l o g i c a l and f l o r a l morpho log ica l coadapta t ions w i t h bumble bees, the genus' major p o l l i n a t o r s ( L i 1951; Sprague 1962 ; Macior 1968a S b , 1969 , 1970a). Pedioularis brc&te.ce<x ( F i g . 134) , the on ly one of th ree Pedioularis species i n the genera l area to occur i n B l a c k w a l l Meadow, bears sp ikes o f y e l l o w i s h , o d o r l e s s , n e c t a r i f e r o u s f l o w e r s . The upper l i p o f the fused c o r o l l a forms a beakless hood or ga lea tha t enc loses the four stamens; the c a p i t a t e st igma i s exser ted a few m i l l i -meters beyond the ga lea t i p . The f lowers are v i s i t e d by l a r g e bumble bees t h a t , a f t e r g a i n i n g a f o o t h o l d on the lower c o r o l l a l i p , push t h e i r probosces and heads i n t o the c o r o l l a tube i n search of nec ta r sec re ted by a u n i l a t e r a l s w e l l i n g on the lower s ide of the ovary . P o l l e n i s thus depos i ted on the back o f the bumble bees; i . e . , n o t o t r i b i c a l l y . Pedioularis raoemosa ( F i g . 135) , a spec ies more c h a r a c t e r i s t i c a l l y o f suba lp ine f o r e s t and f o r e s t c l e a r i n g s , and P. groenlandioa ( F i g . 136) , much commoner i n wet seepage areas and f l u s h e s , are the other two Pedioularis species i n the v i c i n i t y of B l a c k w a l l Meadow. The s t r u c t u r e of the f lowers of these three spec ies i s markedly d i f f e r e n t , as i s the p o l l i n a t i n g behavior of t h e i r bumble bee v i s i t o r s (Sprague 1962; Macior 1968a,1970a; F a e g r i and van der P i j l 1971). Since the three spec ies a l s o have staggered peak f l o w e r i n g t imes , they are i s o l a t e d e c o l o g i c a l l y , e t h o l o g i c a l l y , and p h e n o l o g i c a l l y . Fig. 135. P e d i o u l a r i s r a o e m o s a . The galea i s long-beaked, twisted l i k e a s i c k l e . H o ro ? Fig. 136. P e d i o u l a r i s g r o e n l a n d i o a . The galea i s extremely long-beaked and extends l i k e an elephant's trunk. \0%b 103 Other spec ies i n the study communities tha t are p o l l i n a t e d p r i m a r i l y by bumble bees are Erythronium grandiflorum, Gentiana d o u g l a s i a n a 3 H y d r o p h y l l u m f e n d l e r i , and V a c c i n i u m d e l i c i o s u m , V. o v a t u m , V. o x y c o c c u s , V. s o o p a r i u m , V. u l i g i n o s u m } and V. vitis-idaea. None of these spec ies except f o r V. oxy coccus have p a r t i c u l a r l y s p e c i a l i z e d bumble bee f lowers and are a c c e s s i b l e to o ther i n s e c t s ; n e v e r t h e l e s s , I have observed bumble bees to be t h e i r most numerous and constant p o l l i n a t o r s . Though they are not fused , the b r i g h t y e l l o w t e p a l s o f Erythronium grandiflorum do form a concealed nectar chamber. The t epa l s are r e f l e x e d above, but at t h e i r bases come together to form a shor t tube t ha t i s sea led at the top by a p r o t r u d i n g c o l l a r - l i k e r i n g of b a s a l s w e l l i n g s on the outer th ree p e r i a n t h p a r t s . Narrow grooves i n the middle o f the three outer t e p a l s furrow through t h i s c o l l a r and are covered by the f i l amen t s the grooves serve as.passages fo r the p o l l i n a t o r ' s p r o b o s c i s . The n e c t a r i e s are s i t u a t e d at the base of the t e p a l s and f i l l the b a s a l chamber w i t h nectar tha t i s prevented from t r i c k l i n g out ( the f lowers droop a t an thes i s ) by the c o l l a r (Knuth 1906-1909) as w e l l as surface t e n s i o n . Gentiana douglasiana, w i t h i t s s m a l l e r , w h i t e , t u b u l a r -campanulate, moderately n e c t a r i f e r o u s , f a i n t l y f r ag ran t f l o w e r s , i s c l e a r l y d i f f e r e n t from i t s bog congener, G. sceptrum. The c o r o l l a tube i s about 12 mm l o n g , w i t h about a 5 mm o r i f i c e . The c o r o l l a i s w h i t i s h to g r e e n i s h - w h i t e , w i t h b lue nec ta r guides dot ted on the lobes ( F i g . 137) . The s t i g m a t i c lobes and anthers are borne a t about the same h e i g h t , but are remote from one another . Nectar i s sec re ted by glands at the base of 104cu F i g . 1 3 7 . Gentiana douglasiana. The flowers are moderately protandrous and have white c o r o l l a lobes dotted w i t h blue nectar guides. F i g . 1 3 8 . Vaccinium ovatum. Note the exserted s t y l e e n c i r c l e d by a r i n g of stamens. lOHb 105 the s e s s i l e ovary . V i s i t i n g bumble bees (the on ly v i s i t o r s to G. douglasiana t h a t I observed, and they were not f requent) work the f lowers wi thout c r a w l i n g down i n t o the c o r o l l a tube , as they do i n G e n t i a n a s c e p t r u m . Hydrophyllum fendleri has a w h i t e , campanulate, sympetalous c o r o l l a 7-10 mm l o n g . Both s t y l e and stamens are e x s e r t e d , and each f i l a m e n t i s f l anked by a p a i r of c i l i a t e , l i n e a r , c o r o l l a appendages. Nectar i s sec re ted a t the base of the ova ry , s to red and concealed i n a c a v i t y of the p e t a l s , and r i s e & i n the narrow chambers running between the p a i r of l o n g i t u d i n a l c o r o l l a appendages f l a n k i n g the m i d r i b of each p e t a l . A l l the above species of Vaccinium except f o r V. oxy-coccus have s m a l l , whi te to p ink f lowers w i t h u r n - or b e l l -shaped, sympetalous c o r o l l a s ( F i g . 138) . The s l i g h t l y exse r ted s t y l e i s c l o s e l y e n c i r c l e d by 10 shor t e r stamens w i t h t e r m i n a l pores . Nectar i s secre ted at the base of the s t y l e and an i n s e c t must push i t s tongue between the c i r c l e o f stamens to reach i t , and i n so doing d i s lodges p o l l e n from the anthers of the g e n e r a l l y pendent f l o w e r s . The f lower of Vaccinium oxycoccus ( E r i c a c e a e ) , w i t h i t s four r e f l e x e d p e t a l s and r i n g o f e igh t stamens e n c i r c l i n g the exser ted s t y l e ( F i g . 139) , bears a remarkable resemblance to a Dodecatheon (Pr imulaceae) f lower ( F i g . 140). Macior (1964, 1970b) has made d e t a i l e d obse rva t ions on the p o l l i n a t i o n ecology o f Dodecatheon. P o l l i n a t i o n i s accomplished by bumble bees tha t hang i n v e r t e d from the cone o f connate anthers and w i n g - v i b r a t e p o l l e n onto t h e i r bod i e s . I have observed p o l l i n a t i o n of V. h-1 o cn P Fig. 139. Vaooinium oxyoooous (Ericaceae). Fig. 140. Dodecatheon jeffreyi (Primulaceae). In both flowers, note the relexed, f l a r e d petals, and the style exserted from the enveloping cylinder of stamens. 107 oxycoccus by bumble bees i n the sphagnum bogs, and the mechanism agrees c l o s e l y w i t h tha t of Dodecatheon as desc r ibed by M a c i o r . The f lowers d i f f e r i n tha t those of Dodecatheon are n e c t a r l e s s but f ragran t w h i l e those of V. oxycoccus have a r i n g of s m a l l n e c t a r i e s at the base of the s t y l e j u s t i n s i d e the stamens but have no p e r c e p t i b l e odor. Convergent e v o l u t i o n must have been i n v o l v e d he re , and i n the occurrence o f s t r i k i n g l y s i m i l a r f lower form i n Solanum and Lycopersicon (Solanaceae) . Moth p o l l i n a t i o n (pha laenophi ly ) Moth p o l l i n a t i o n i s we l l -deve loped i n on ly o f the species i n the present s tudy , S i l e n e p a r r y i ( F i g . 14 la £ b ) . S i l e n e parryi f i t s almost p e r f e c t l y the moth p o l l i n a t i o n syndrome o u t l i n e d i n F a e g r i and van der P i j l (1971). The whi te f l o w e r s , c l o sed and appearing w i l t e d i n the dayt ime, open at n i g h t and dur ing an thes i s emit a heavy-sweet , pe rvas ive perfume. The h o r i z o n t a l blossoms are v i s i t e d by n o c t u r n a l hawk moths ( L e p i d o p t e r a , Heteroneura , Sphingidae) tha t hover i n f ron t of the f lowers wi thout a l i g h t i n g (these observa t ions cor robora ted by A . R . Kruckeberg , pe r sona l communication). The lobed p e t a l s and f r i n g e d ep ipe t a lous appendages o f S. parryi r e f l e c t the s e n s i t i v i t y of moths to d i s s e c t e d o u t l i n e s ( F a e g r i and van der P i j l 1971). The f lowers are abundantly n e c t a r i f e r o u s but the nectar i s secre ted at the base of the ovary and i s concealed by a f l o r a l tube about 11 mm l o n g . Th i s tube , formed by a syn-sepa lous , b l a d d e r - l i k e c a l y x tha t holds the long claws of the f ree pe t a l s f i r m l y t o g e t h e r , i s e a s i l y a c c e s s i b l e to the long 1 0 8 c v Fig. 141a. S i l e n e p a r r y i . The flowers as they appear i n mid-day. Fig. 141b. S i l e n e p a r r y i . Night. Note the dissected outline and the horizontal bearing of the flower. l < A b 109 sphing icL p r o b o s c i s . B u t t e r f l y p o l l i n a t i o n (psychoph i ly ) B u t t e r f l i e s and sk ippers ( L e p i d o p t e r a , Rhopalocera) form an important c l a s s o f p o l l i n a t o r s i n B l a c k w a l l Meadow. They are p a r t i c u l a r l y common v i s i t o r s to f lowers of Compositae such as A r n i c a l a t i f o l i a and A. m o l l i s , S e n e c i o i n t e g e r r i m u s and S. t r i a n g u l a r i s , E r i g e r o n p e r e g r i n u s , and e s p e c i a l l y A g o s e r i s aurantiaca. They a l s o s t r o n g l y favor the blossoms o f Phlox d i f f u s a and V a l e r i a n a s i t c h e n s i s . B u t t e r f l y blossoms are g e n e r a l l y e r e c t , r a d i a l , and f a i r l y f l a t , as most p o l l i n a t i n g b u t t e r f l i e s a l i g h t on t h e i r f lowers r a the r than hover i n f ron t of them. B u t t e r f l y f lowers have ample nec tar i n tubes or spurs and they a l s o tend to be v i v i d l y c o l o r e d . B e h a v i o r a l s tud ie s on b u t t e r f l y c o l o r pe rcep t ion and preference have found tha t b u t t e r f l i e s show peak response to the orange red and b lue reg ions of the spectrum ( U s e 1928 ; Swihart and Swihart 1970 ; L e v i n 1972a). A g o s e r i s a u r a n t i a c a and P h l o x d i f f u s a have probably the best developed b u t t e r f l y f lowers i n the meadow. Agoseris aurantiaca (Tig. 14-2) has b r i l l i a n t burnt-orange f l o w e r s ; Phlox'diffusa ( F i g . 143) d i s p l a y s in tense mauve t o pa le blue blooms. Hummingbird p o l l i n a t i o n The on ly predominant ly hummingb i rd -po l l ina ted f lower i n t h i s study i s Castilleja miniata. Th is spec ies i s i n c l u d e d as 110 CO F i g . 142. Agosevis auvantiaoa. The burn t -orange , l i g u l a t e f lowers are aggregated i n a c a p i t a t e cap i tu lum. F i g . 143. Phlox diffusa. The sa lve r fo rm c o r o l l a s have wide-sp read ing , h o r i z o n t a l l and ing ..platforms and i n c l u d e the anthers and s t igma. nob I l l a confirmed hummingbird f lower i n Grant and Gran t ' s (19 68) monograph on hummingbird p o l l i n a t i o n . In B l a c k w a l l Meadow, Castilleja miniata i s p o l l i n a t e d by the Rufous hummingbird (Selasphorus rufus). The b r i l l i a n t s c a r l e t to deep r e d , odor le s s i n f l o r e s c e n c e s o f C. miniata ( F i g . 144) c o n s i s t of b r i g h t l y co lo r ed b rac t s t ha t . enve lop l o n g , g reen i sh 20-40 mm t u b u l a r c o r o l l a s . The l eng th of the c o r o l l a tube corresponds to the 17-21 mm b i l l p lus e x t e n s i b l e tongue l eng th of the Rufous hummingbird (Grant and Gran t -1968) . In c o n t r a s t , C. parviflora v a r . albida, the other Castilleja spec ies i n the subalp ine meadow, has a 12-18 mm long c o r o l l a tube and i s p o l l i n a t e d by bumble bees. In p o l l i n a t i n g C. miniata, the hummingbirds probe the f lowers f o r the abundant nec t a r t ha t i s sec re ted at the base o f the c o r o l l a tube. In so d o i n g , they r e c e i v e p o l l e n on the top of the head or upper b i l l base from the anthers tha t are enclosed i n the b e a k l i k e upper l i p ( g a l e a ) . At the same time p o l l e n may be t r a n s f e r r e d to the s l i g h t l y exser ted s t y l e . S tud ies of hummingbird d i s p e r s a l of p o l l e n l a b e l l e d w i t h r a d i o a c t i v e i o d i n e i n d i c a t e tha t hummingbirds are' extremely e f f i c i e n t vectors . , at l e a s t w i t h i n l o c a l popu la t ions ( S c h l i s i n g and Turp in 1971). The prevalence of red as the predominant c o l o r o f n o r t h -western American hummingbird f lowers has provoked an i n t e r e s t i n g hypo thes i s . Grant (1966)..suggested tha t t h i s convergence i n c o l o r i n species of many d i f f e r e n t f a m i l i e s and genera i s not n e c e s s a r i l y due to hummingbird preference f o r r e d , but i n s t e a d i s r e l a t e d to the f ac t t h a t , wh i l e hummingbirds pe rce ive r e d , H H F i g . 144. Castilleja miniata has l o n g - F i g . 145. Anemone o o o i d e n t a l i s , i n f r u i t . The t u b u l a r , g reen i sh c o r o l l a s achenes are t i pped w i t h l o n g , s i nuous , amidst f l ame-red b r a c t s . s i l ky -p lumose s t y l e s . I l i b 113 bees do no t . Th i s be ing so , a common f l o r a l c o l o r would be s e l e c t i v e l y advantageous to both the mig ra to ry hummingbirds and t h e i r f lowers i n tha t i t would f a c i l i t a t e qu ick p o l l i n a t o r r e c o g n i t i o n o f f lowers and would reduce compe t i t i on from bee-p o l l i n a t e d s p e c i e s . Such f l o r a l mimicry has been mentioned by Macior (1971) and i s c o n s i s t e n t w i t h theory (Straw 1972). Furthermore, as Raven (1972) .po in t s o u t , the h i g h ene rge t i c requirements of hummingbirds are best s a t i s f i e d by a f lower w i t h abundant n e c t a r , no odor (hummingbirds respond on ly s e c o n d a r i l y to odor , u n l i k e i n s e c t s (Grant and Grant 1968) ) , and a c o l o r s i g n a l d i s t i n g u i s h a b l e by b i r d s but not conspicuous to i n s e c t s tha t cou ld dep le te the supply of much-needed n e c t a r ; tha t i s to say , such a f lower would be the prototype o f a hummingbird f l o w e r . I m p l i c a t i o n s As has been mentioned be fo re , the ma jo r i t y of the- s a l t marsh p l an t s are anemophilous, sphagnum bog p l an t s are more e q u a l l y anemophilous and entomophi lous , and subalpine meadow p lan t s are p r i m a r i l y entomophilous. There are cor responding d i f f e r ences i n the p ropor t ions of showy-flowered spec ies i n the communities. N e v e r t h e l e s s , the bu lk of the spec ies and vege t a t i on i n a l l four s i t e s i s predominantly o u t c r o s s i n g (see prev ious d i s c u s s i o n and Sec t . I I I - J and Appendix 3 ) , as most of the s e l f - c o m p a t i b l e species (eg. , K a l m i a polif'olia, Ledum g r o e n l a n d i c u m , V a c c i n i u m s p p . , E r y t h r o n i u m g r a n d i f l o r u m , D e l p h i n i u m n u t t a l l i a n u m , P h l e u m a l p i n u m , C a r e x s p p . , J u n c u s spp. 114 have f l o r a l b i o l o g i e s promoting o u t c r o s s i n g . There i s no major s h i f t to s e l f - p o l l i n a t i o n or apomixis i n any of the communities Mosquin (19 66) t h e o r i z e d t h a t . s p e c i e s of harsh p h y s i c a l environments w i l l tend to have r e p r o d u c t i v e s p e c i a l i z a t i o n s tha t reduce -. the amount of gene t ic v a r i a b i l i t y , sugges t ing tha t gene t ic u n i f o r m i t y and p r e s e r v a t i o n of shor t - t e rm f i t n e s s may a c t u a l l y be adapt ive i n such environments. One obvious r e p r o d u c t i v e s p e c i a l i z a t i o n tending toward gene t i c u n i f o r m i t y would i n v o l v e r educ ing the amount of outbreeding i n a species p o p u l a t i o n by a s h i f t to s e l f - f e r t i l i z a t i o n or apomix i s . Kevan (1970, 1972) and S a v i l e (1972) i n d i c a t e d no pronounced t rend toward inb reed ing i n p l a n t spec ies of the harsh A r c t i c t undra . My observa t ions l i k e w i s e show no such t rend i n any of the three vege t a t i on types I have s t u d i e d . A l l three e x i s t i n p h y s i c a l environments tha t must be cons idered "harsh" i n at l e a s t some r e s p e c t s . But i f Mosquin ' s hypothes i s i s to be t e s t ed by my r e s u l t s a more i n c l u s i v e e v a l u a t i o n of t h e . s p e c i e s recombina t ion systems, of which p o l l i n a t i o n and o u t c r o s s i n g mechanisms are but one aspec t , w i l l be r e q u i r e d (see Sec t . I I I - J ) . F. D i s p e r s a l eco logy . 115 Along w i t h p o l l e n d i s p e r s a l , the o ther v e h i c l e of gene f low (apart from vege t a t i ve d i s p e r s a l ) a v a i l a b l e to f l o w e r i n g p l an t s i s r e p r o d u c t i o n by seed. As Stebbins (1971a) has po in ted ou t , to be s u c c e s s f u l such r ep roduc t ion r e q u i r e s an i n t e g r a t i o n of d i f f e r e n t func t ions and a c o o r d i n a t i o n between morpho log ica l s t ruc tu rescand p h y s i o l o g i c a l processes such as f r u i t r i p e n i n g , seed dormancy, and s e e d l i n g growth. S a l i s b u r y (1942) , Stebbins (1950, 1971a), P i j l (1969) and Baker (1972) have emphasized the e c o l o g i c a l consequences of the d i s p e r s a l system and the c o r r e l a t i o n s tha t may be made between d i s p e r s a l type and h a b i t a t . The above authors and C a r l q u i s t (1966) , Janzen (1969, 1971a), and Harper , L o v e l l , and Moore (1970) have o u t l i n e d some of the adapt ive compromises between seed s i z e , seed number, and d i s p e r s a l agent tha t ensure s u c c e s s f u l r e p r o d u c t i o n i n p a r t i c u l a r h a b i t a t s . The f o l l o w i n g d i s c u s s i o n centers on the d iaspore morph-ology and mode of d i s p e r s a l o f the angiosperm spec ies o f the four study s i t e s , and touches on some of the e c o l o g i c a l i m p l i c a t i o n s at the community l e v e l . In many cases , the a c t u a l mode(s) of d iaspore t r a n s p o r t does (do) not f o l l o w from diaspore morphology. In these cases I have t r i e d to make reasonable conjectures tha t r e l y h e a v i l y on pub l i shed accounts , i n c l u d i n g Kerner (1896) , R i d l e y (1930) , P i j l (1969) , and Stebbins (1971a). The propagule type and mode of d i s p e r s a l f o r each species are g iven i n Appendix 3. Trends i n d i s p e r s a l systems w i t h i n 116 each community are summarized i n Tables 14 and 15. Table 14 i s based on a morpho log ica l c l a s s i f i c a t i o n of d iaspore types s l i g h t l y modi f i ed from F r e n k e l (1970) and o u t l i n e d i n Table 13 TABLE 13. O u t l i n e o f d iaspore t ypes . Diaspore type D e s c r i p t i o n Auxochore Cyclochore Pterochore Pogonochore Desmochore Sarcochore Sporochore M i c r o s c l e r o c h o r e Megasclerochore Barochore B a l l o c h o r e No d i s a r t i c u l a t i o n from parent p l a n t before d iaspore i s depos i ted a t s i t e of fu r the r development. Diaspore very voluminous i n r e l a t i o n to a c t u a l r ep roduc t i ve p a r t . Diaspore w i t h s c a r i o u s , w i n g l i k e , or saccate appendages. Diaspore w i t h l o n g , h a i r l i k e , or plumose appendages. Diaspore w i t h s h o r t , s t i f f , s p i n y , g l andu la r or hooked appendages adher ing to rough su r faces . Diaspore wi thou t appendage but w i t h j u i c y or f l e s h y outer l a y e r s . Diaspore l i g h t enough to be c a r r i e d by breeze (0.001-0.049 mg). Diaspore wi thout appendage, too heavy to be c a r r i e d by breeze (0.050-0.499 mg). Diaspore wi thout appendage, too heavy to be c a r r i e d by breeze (0.500-999.0 mg). Diaspore wi thout appendage and very heavy (1000.0+ mg). Parent p l a n t has mechanism f o r d iaspore e x p u l s i o n . Table 14 gives the percentages of each propagule type i n the f l o r a o f each s i t e . Note tha t the ca t ego r i e s are not e x c l u s i v e ; e g . , the i ndeh i scen t capsule of Plantago maorooarpa ( F i g . 147) i s a megasclerochore , w h i l e the seed, w i t h i t s 117 muci lag inous seed coa t , would be a desmochore when l i b e r a t e d and wet ted . Presumably both hydrochory and adhesive ep i zoo -chory are e f f e c t i v e means of d i s p e r s a l i n t h i s s p e c i e s . TABLE 14. Percentages of d iaspore t y p e s . 1 Diaspore type S a l t Marsh Wade's Bog (%) (%) Ogg's Bog B l a c k w a l l (%) Meadow (%) Auxochore 4.0 2.9 Cyclochore 11.1 Pterochore 16.0 11.4 17.8 Pogonochore 5.6 4.0 8.6 26.7 Desmochore 38.9 8.0 14.7 22.2 Sarcochore 24. 0 2 5.7 4.5 Sporochore 5.6 16.0 11.4 2.2 M i c r o s c l e r o c h o r e 33.3 20.0 22.9 28.9 Megasclerochore 50.0 28.0 35.0 26.7 B a l l o c h o r e 4.5 "'"There are no barochores i n any of the communities. The on ly species tha t may have an auxochorous d iaspore i s Vaooinium o x y o o o o u s . The f r u i t s of t h i s c ranber ry can f r equen t ly be found l y i n g i n t a c t on a bed o f Sphagnum moss, having over -win te red uneaten and s t i l l a t tached to the parent p l a n t . The seeds cou ld conce ivab ly germinate in situ as the be r ry decomposes the f o l l o w i n g summer but t h i s i s q u e s t i o n a b l e . The s a l t marsh has the only two cyc lochorous s p e c i e s : G l a u x m a r i t i m a and S a l i o o r n i a v i r g i n i o a . In G l a u x , the seeds adhere to the spongy p l a c e n t a . The spongy p e r i a n t h o f S a l i o o r n i a i s accrescent to the i n d e h i s c e n t u t r i c l e . Both of these compound 118 d i s p e r s a l u n i t s are bouyant and probably are d i spe r sed f o r r e l a t i v e l y shor t d i s t ances by the t i d e s . In S a l i o o r n i a , e n t i r e segments of the f l e s h y stems (see F i g . 116) tha t break o f f and can f l o a t i n seawater fo r up to th ree months (Dalby 1963). cou ld a l s o f u n c t i o n as cyc lochorous d i a spo re s . There are a number of pterochorous spec ies i n the sphagnum bogs and the suba lp ine meadow, but none i n the s a l t marsh. D r o s e r a r o t u n d i f o l i a , T o f i e l d i a g l u t i n o s a , C a s t i l l e j a m i n i a t a , and C. parviflora have l o o s e l y t e s t a t e seeds; Myrioa gale, S a n g u i s o r b a o f f i c i n a l i s , A r e n a r i a c a p i l l a r i s , V e r o n i c a c u s i c k i i P e d i o u l a r i s b r a c t e o s a , and V e r a t r u m v i r i d e have winged seeds or f r u i t s ; D e l p h i n i u m n u t t a l l i a n u m and P e n s t e m o n p r o c e r u s have q u i t e s i m i l a r , s h i n y - b l a c k , wing-angled seeds w i t h somewhat l o o s e , puckered, r e t i c u l a t e t e s t a s . Pogonochores are represented p r i m a r i l y by the pappose f r u i t s of the Compositae. The achene of Valeriana sitchensis , f i t t e d w i t h the p e r s i s t e n t , p a p p u s - l i k e c a l y x , i s s i m i l a r to the Compositae pogonochore. The c l u s t e r of pogonochores o f Anemone occidentalis ( F i g . 145) puts on a superb d i s p l a y of numerous v i l l o u s achenes t i p p e d w i t h l o n g , s i l k y - p l u m o s e s t y l e s the ":mop tops" or "tow-headed babies" of suba lp ine meadows Other pogonochores are the plumose-per ianthed n u t l e t s of E r i o p h o r u m p o l y s t a c h i o n , the comose seeds of E p i l o b i u m a l p i n u m , the t a i l e d seeds of Junous drummondii , and the awned f r u i t s of D e s o h a m p s i a o e s p i t o s a . I have c l a s s e d the var ious ly-appendaged propagules of the grasses D e s o h a m p s i a o e s p i t o s a , F e s t u o a r u b r a , E o r d e u m b r a c h y -a n t h e r u m , C a l a m a g r o s t i s n u t k a e n s i s , P h l e u m a l p i n u m , T r i s e t u m 119 s p i c a t u m 3 E l y m u s g l a u o u s , and P o a c u s i c k i i as desmochores because they can e a s i l y adhere to rough-sur faced animals and be ep izoochorous ly d i spe r sed ( R i d l e y 1930; P i j l . 1 9 6 9 ; Stebbins 1971a). The legume p lus s p i n y , adherent c a l y x of Tvifolium wormskholdii and the capsule p lus a t t ached , s t i f f - c i l i a t e c a l y x of Eydrophyllum fendleri are a l s o desmochores. The g l a n d u l a r , i ndeh i scen t capsule of Linnaea borealis , the g landular -pubescent seeds of Spergularia c a n a d e n s i s , and the muci laginous-when-wetted seeds o f Plantago macrocarpa 3 P. m a r i t i m a , and M i c r o s t e r i s g r a c i l i s are examples of s t i c k y desmochores. The beaked p e r i g y n i a of Carex canescens have a l so been c l a s s e d desmochores, as have the achenes of Ranunculus eschscholtzii and Thalictrum occidentale , which are beset w i t h p e r s i s t e n t , s l i g h t l y curved s t y l e s . Sarcochores are represented by the b e r r i e s of a l l V a c c i n i u m s p e c i e s , o f E m p e t r u m n i g r u m ( F i g . 146) , G a u l t h e r i a s h a l l o n , M a i a n t h e m u m d i l a t a t u m , and L y s i a h i t u m a m e r i c a n u m , and by the drupe of Cornus u n a l a s a h k e n s i s . The s a l t marsh has no sarcochorous species and the suba lp ine meadow has on ly two (.Vaccinium d e l i c i o s u m and V. s c o p a r i u m ) , w h i l e the f l o r a of both bogs i s 2 5% sarcochorous . Only a few spec ies have seeds l i g h t enough to be c l a s s e d sporochores : they are J u n c u s b a l t i c u s 3 J. d r u m m o n d i i 3 J. s u p i n i f o r m i s j D r o s e r a r o t u n d i f o l i a 3 K a l m i a p o l i f o l i a 3 and Ledum •groenlandicum. Mic ro -" and megasclerochores are common i n a l l the communities. The on ly b a l l o c h o r e s are found i n B l a c k w a l l Meadow. The seeds of Lupinus latifolius are b a l l i s t i c a l l y d i spe r sed by an e x p l o s i o n of the r i p e legume and subsequent 120cv F i g . 146. Empetrum nigrum. The b l a c k be r ry i s a sarcochorous propagule . F i g . 147. Plantago maorooarpa. The f r u i t i n g sp ike c o n s i s t s of somewhat i n f l a t e d , i ndeh i scen t capsu les . 121 s p i r a l t o r s i o n o f the pod va lves ( R i d l e y 1930). In Claytonia lanoeolata, the mature, e rec t capsule s p l i t s i n t o three va lves tha t f i r s t spread ou t , c r a d l i n g the 3 ( u s u a l l y ) - 6 o v o i d , p o l i s h e d , b l ack seeds. As the va lves d r y , they p inch inwards u n t i l t h e i r pressure i s s u f f i c i e n t to e j ec t one or more of the cont iguous seeds ( R i d l e y 1930). Table 15 con ta ins a summary of the percentages of s i x major modes of d i s p e r s a l i n both the f l o r a and vege t a t i on of a l l four communities. Due to the d i f f i c u l t y of d i r e c t o b s e r v a t i o n , most of the d i s p e r s a l types have been i n f e r r e d , but i t should be repeated tha t one cannot n e c e s s a r i l y deduce d i s p e r s a l method from d iaspore morphology; Most o f the species employ more than one mode of d i s p e r s a l , so the t o t a l s o f the percentages o f va r ious d i s p e r s a l methods f o r each community exceed 100%. In cases where i t was doub t fu l which of two a l t e r n a t i v e methods are u t i l i z e d by a p a r t i c u l a r s p e c i e s , both a l t e r n a t i v e s were counted. TABLE 15. Percentages o f d i s p e r s a l methods; f l o r a / v e g e t a t i o n . D i s p e r s a l S a l t Marsh Wade's Bog Ogg's Bog B l a c k w a l l method (%) (%) (%) Meadow (%) Autochory 4/14 Hydrochory 50/U0 44/48 43/51 7/1 Anemochory 61/70 52/63 51/59 91/92 Endozoochory 24/10 26/10 4/3 Epizoochory (mud) 100/100 48/55 46/55 Epizoochory (adhesion) 39/53 8/6 17/8 23/11 122 A few genera l conc lus ions can be drawn from Table 15. A b i o t i c d i s p e r s a l methods are very important i n a l l four communities. P r e d i c t a b l y , spec ies of the wetland communities (bog and s a l t marsh) r e l y much more on water d i s p e r s a l than the subalpine meadow s p e c i e s , which are predominant ly w i n d - d i s p e r s e d . Many of the s a l t marsh and bog spec ies are hydrochorous merely because they grow i n wet areas t h e i r propagules are not p a r t i c u l a r l y adapted f o r f l o t a t i o n . However, the somewhat i n f l a t e d , i ndeh i scen t capsules of Plantago macrocarpa ( F i g . 147) , the spongy d iaspores of Salicornia virginica, the t h i c k -w a l l e d p e r i g y n i a of C a r e x lyngbyei ( F i g . 148) and C. o b n u p t a , the corky mericarps of Lilaeopsis oooidentalis , and the c o r k y , winged f r u i t s of M y r i c a gale and S a n g u i s o r b a o f f i c i n a l i s are a l l w e l l adapted f o r bouyancy and water d i s p e r s a l . Splash-cup d i s p e r s a l (Brodie 1951; S a v i l e 1953) i s a unique type of s h o r t - d i s t a n c e hydrochory employed by Coptis asplenifolia ( F i g . 149) , probably by C. trifolia, and perhaps by Gentiana douglasiana. The smooth seeds are e j ec ted from the f l a r e d l i p s of the open f r u i t s by f a l l i n g water drops tha t score d i r e c t h i t s . The predominance o f wind d i s p e r s a l i n B l a c k w a l l Meadow i s r e f l e c t e d i n the l a r g e number of pterochorous and pogonochorous spec i e s . Pterochores and pogonochores are o b v i o u s l y morpho-l o g i c a l l y adapted f o r anemochory; most o f the mic ro - and mega-sc le rochores i n the meadow are a l s o anemochorous, but i n a l e s s obvious way. The f r u i t i n g s t a l k s o f many suba lp ine meadow species remain e rec t above the f i r s t encrusted snows o f e a r l y w i n t e r . The•frequent , s t rong mountain winds must o f ten j o s t l e 123a, F i g . 148. Carex lyngbyei , f r u i t i n g s p i k e . Note the plump, t h i c k - w a l l e d p e r i g y n i a . F i g . 149. Coptis asplenif'olia has f r u i t i n g f o l l i c l e s adapted fo r sp lash-cup d i s p e r s a l . 124 seeds loose from t h e i r f r u i t s and blow them f o r r e l a t i v e l y long d i s t ances across the hardened surface before the heavy snows set i n . This type of d i s p e r s a l cou ld augment the r e l a t i v e l y l o c a l d i s s e m i n a t i o n of seeds by the censer mechanism (as i n P e d i c u l a r i s b r a c t e o s a , C a s t i l l e j a m i n i a t a and C. p a r v i f l o r a , and Erythronium g r a n d i f l o r u m ) , and cou ld conce ivab ly account f o r movement o f great d i s t ances from r i dge top to r i dge top even f o r such heavy, unappendaged seeds as those of E. grandiflorum, L u p i n u s l a t i f o l i u s , or H y d r o p h y l l u m f e n d l e r i . S a v i l e (1972) cons iders a s i m i l a r mode of d i s p e r s a l to be of prime importance to A r c t i c s p e c i e s . B i o t i c d i s p e r s a l i n genera l i s most important i n the s a l t marsh, of in te rmedia te importance i n the sphagnum bogs, and l e a s t important i n the subalpine meadow. B i o t i c d i s p e r s a l i n the s a l t marsh i s predominant ly ep izoochorous , and the t r anspo r t i s p r i m a r i l y i n mud tha t adheres to the feet and plumage o f water fowl and the feet and h a i r of g r az ing animals ( R i d l e y 1930). Transpor t by adhesion of desmochores to animals a l s o p lays an important r o l e i n marsh seed d i s p e r s a l . D i s p e r s a l v i a animal i n g e s t i o n of f l e s h y f r u i t s (endozoochory) i s common i n the sphagnum bogs, but the sarcochorous spec ies are minor elements of the bog vege t a t i on (Table 15) . B i o t i c d i s p e r s a l i n the subalp ine meadow i s p r i m a r i l y by adhesive ep izoochory , but s i m i l a r l y the desmochores belong to subordinate spec i e s . In summary, b i o t i c d i s p e r s a l i s much more p reva len t i n the s a l t marsh and bogs than i n the suba lp ine meadow, where most of the species are w i n d - d i s p e r s e d . What i s the s i g n i f i c a n c e of t h i s genera l d i f f e r e n c e i n community d i s p e r s a l pa t t e rns? 125 Stebbins (1971a) main ta ins tha t animal d i s p e r s a l i s more e f f i c i e n t than wind d i s p e r s a l across long d i s t ances because an ima l s , e s p e c i a l l y migra to ry a n i m a l s , are more p r e d i c t a b l e i n t h e i r movements and more s e l e c t i v e i n h a b i t a t - t o - h a b i t a t t r a n s -por t than i s w ind . The l i k e l i h o o d tha t seeds w i l l be d i spe r sed when r i p e and t r anspor t ed to favorab le h a b i t a t s s i m i l a r to those occupied by the parent p l a n t s i s g rea te r i n an imal d i s p e r s a l . None of the three vege t a t i on types are ex tens ive or continuous i n nor thwestern North Amer ica . S a l t marshes and c o a s t a l sphagnum bogs occur i n i s o l a t e d patches a long the nor th P a c i f i c coas t . In view of the extreme i m p r o b a b i l i t y and l i k e l y i n e f f i c a c y of long d i s t ance p o l l i n a t i o n .(cf. E h r l i c h 5 a n d Raven 19 69; End le r 1973) , gene f low between popu la t ions of marsh and bog species must be p r i m a r i l y v i a long d i s t ance seed d i s p e r s a l by an imals . Subalpine meadows, though f a r from being a continuous or dominant element of the t o t a l v e g e t a t i o n , are much more ex tens ive i n the c o r d i l l e r a o f P a c i f i c North America than are s a l t marshes and bogs a long the coas t . Mountain meadows cou ld ac t as s tepping stones f o r a sequence of r e l a t i v e l y s h o r t , wind-d i spe r sed hops, and i n t h i s s i t u a t i o n i n t e r p o p u l a t i o n gene f low i s probably not as dependent on long d i s t ance seed d i s p e r s a l . Furthermore, gene f low v i a p o l l i n a t i n g i n s e c t s i s probably more e f f i c i e n t i n the meadows, not on ly because i n s e c t p o l l i n a t i o n i s much more common but a l s o because e f f e c t i v e long d i s t ance p o l l i n a t i o n i s mediated more f r equen t ly by i n s e c t s than wind ( E h r l i c h and Raven 1969; Janzen 1971b). Thus i t appears tha t the two methods of gene f low i n p l a n t s , p o l l i n a t i o n and d i s p e r s a l , ac t i n concer t and compensation i n ma in t a in ing what one must 126 assume is an optimum or near-optimum rate of gene exchange within the species of the community types. G. V a r i a b i l i t y and n iche w i d t h . 127 Consider an n -d imens iona l hyperspace a b s t r a c t l y cons t ruc ted along coord ina tes corresponding to a l l v a r i a b l e s r e l e v a n t to the l i f e o f a s p e c i e s . Hutchinson (1965) def ines the s p e c i e s ' n iche as tha t hypervolume w i t h i n the hyperspace, "every p o i n t o f which corresponds to a set of values of the v a r i a b l e s p e r m i t t i n g the organism to e x i s t . " Al though a n iche d e s c r i p t i o n i s based to a great extent on the p h y s i c a l parameters of a s p e c i e s ' e x i s t e n c e , i t remains incomplete wi thout i n c l u s i o n of i t s b i o t i c components. As Major (19 58) has w r i t t e n , " . . . a s a matter of f a c t , no p h y s i o l o g i c a l data known to the w r i t e r have been able to e x p l a i n why a p a r t i c u l a r p l a n t grows n a t u r a l l y where i t does wi thout appea l ing to compe t i t ion as a genera l term r e f e r r i n g to the i n t e r r e l a t i o n s o f p l a n t s . " Such c o n s i d e r a t i o n s have prompted Hutchinson (1957, 1965) to d i s t i n g u i s h the "fundamental n iche" ( tha t c o n s t i t u t e d by a s p e c i e s ' hypervolume i f no compet i tors are present) from the " r e a l i z e d n i c h e " , which r e s u l t s from i n t e r s p e c i f i c c o m p e t i t i o n . Compet i t ion has been def ined as the " a c t i v e demand of the same spec ies p o p u l a t i o n ( i n t r a s p e c i f i c ) or members of two or more species at the same t r o p h i c l e v e l ( i n t e r s p e c i f i c ) f o r a common resource tha t i s a c t u a l l y o r p o t e n t i a l l y l i m i t i n g " ( M i l l e r 1967). Or , i n the words of Clements, Weaver and Hanson (1929), " . . . w h e n the immediate supply o f a s i n g l e necessary f a c t o r f a l l s below the combined demands of the p l an t s compe t i t i on b e g i n s . " The s i t u a t i o n i s p o t e n t i a l l y f a i r l y s imple i n green p l a n t s . They compete f o r the common resources : l i g h t , 128 wa te r , m i n e r a l n u t r i e n t s , and (sometimes) p o l l i n a t o r s and d i s p e r s a l agents . The n iche concept and compe t i t i on theory have been n e a t l y combined i n the s o - c a l l e d "compe t i t i ve e x c l u s i o n p r i n c i p l e " (Cole I960; Hard in 1960; Pa t ten 1961; DeBach 1966) tha t s t a tes tha t no two species can c o - e x i s t i n d e f i n i t e l y i f t h e i r n iches are i d e n t i c a l . Though the p r i n c i p l e of compe t i t i ve e x c l u s i o n i s h i g h l y c o n t r o v e r s i a l (at l e a s t s y n t a c t i c a l l y ) , a common sense c o r o l l a r y i s tha t compe t i t i on promotes n iche d i f f e r e n t i -a t i o n (Whi t taker 1967, 1970a; Mcin tosh 1970). Species w i l l tend to evolve away from d i r e c t compe t i t i on where one or more spec ies i s at a s e l e c t i v e d isadvantage . Recent e c o l o g i c a l theory (Dobzhansky 1950; Odum 1969; S lobodk in and Sanders 1969; Baker 1970) has i t tha t n iche s p e c i a l i z a t i o n of species i n " so f t " and/or p r e d i c t a b l e p h y s i c a l environments w i l l be more h i g h l y developed than i n harsh and/or unp red ic t ab l e environments. Benninghoff (19 69) c a l l s the f i r s t type o f species "pauc ive r san t " ; the second, " m u l t i v e r s a n t " . Pauc iversan t species are s a i d to have narrower n iches and t h i s i s p robably t r u e , s i n c e communities of pauc ive r san t species are more d i v e r s e (Baker 1970) and the inc reased i n t e r s p e c i f i c compe t i t i on accompanied by resource s p e c i a l i z a t i o n should reduce the s i z e of both the r e a l i z e d and fundamental n i c h e . M u l t i v e r s a n t spec ies are b e l i e v e d to have l a r g e n iches tha t are op t ima l i n u n c e r t a i n environments (Lev ins 1968). Dominance can be def ined as "the a p p r o p r i a t i o n of p o t e n t i a l n iche space of c e r t a i n subordinate spec ies by o ther dominant spec ies" (McNaughton and Wolf 1970). As w i t h c o m p e t i t i o n , 129 dominance i s best manifested w i t h i n a t r o p h i c l e v e l . There are two aspects to a d i s c u s s i o n of dominance and the n i c h e : the s i t u a t i o n as i t e x i s t s w i t h i n a p a r t i c u l a r community, and any pa t te rns tha t may e x i s t between d i f f e r e n t communities. The f o l l o w i n g d i s c u s s i o n owes much to the papers of Mcin tosh (1970) and McNaughton and Wolf (1970). W i t h i n a community, the more abundant, dominant species w i l l exper ience a h i g h degree of i n t r a s p e c i f i c c o m p e t i t i o n . Th i s w i l l tend to generate i n d i v i d u a l homozygosity and p o p u l a t i o n he t e rogene i ty . Less abundant, s c a t t e r e d spec ies w i l l exper ience inc reased i n t e r s p e c i f i c c o m p e t i t i o n ; t h i s w i l l l e ad to i n d i v i d u a l h e t e r o z y g o s i t y and p o p u l a t i o n homogeneity. In e i t h e r case , the degree of i n d i v i d u a l or p o p u l a t i o n v a r i a b i l i t y w i l l depend on the r e l a t i v e amounts of inb reed ing and the s t r eng th of s e l e c t i o n . Evidence tha t i n t r a s p e c i f i c compe t i t i on crea tes g rea t e r i n t r a p o p u l a t i o n a l v a r i a b i l i t y w i t h i n the competing p l a n t species than does i n t e r s p e c i f i c compe t i t i on comes from the work o f J a i n (1969) and J a i n and M a r s h a l l (1967). They found t h a t , i n Avena, u s ing the degree of ^genet ic • p61ymorphi:smaa-s .measured i n terms of genotypic f requencies of marker l o c i , pure stands of two spec ies showed more i n t r a s p e c i f i c v a r i a t i o n than mixed, s tands . E v i d e n t l y i n t e r s p e c i f i c compe t i t i on r e s u l t s i n t i g h t e r n iche s p e c i a l i z a t i o n and reduces b io type d i v e r s i t y . Moreover, compe t i t i on a s i d e , the more abundant, dominant spec ies should have g rea te r v a r i a b i l i t y i n par t because t h e i r l a r g e r popu la t ions are l i k e l y to c o n t a i n more b i o t y p e s , and i f they have broader l i m i t s of t o l e r ance they w i l l a l s o have 130 g rea te r phenotypic v a r i a b i l i t y than subordinate s p e c i e s . This phenotypic- v a r i a b i l i t y i s l i k e l y to have a l a r g e gene t ic component (Bradshaw 1972). W i t h i n a community, t hen , the dominant spec ies should have l a r g e r n iches (Levins 196 8; McNaughton and Wolf 1970).and concomi tan t ly g rea t e r p o p u l a t i o n he te rogene i ty and morpho log ica l v a r i a b i l i t y (Van Valen ,196 5 ;'• Van Valen et al. 1970) than subordinate s p e c i e s . To t e s t t h i s hypothes is i t i s necessary to have a v a l i d measure o f n iche wid th or s i z e . McNaughton and W o l f ' s (1970) measure s i m p l i f i e s to zero i f there i s on ly one community f o r each s p e c i e s , as i s the case i n t h i s s tudy. So I must use L e v i n s ' (19 68) measure: l o g B = - E p i l o g p ± where p^ i s the p r o p o r t i o n o f the spec ies i n community i , and B i s a measure of n iche s i z e . I f there i s on ly one community f o r each s p e c i e s , the n iche s i z e of a p a r t i c u l a r spec ies w i l l merely be i t s p r o p o r t i o n of the t o t a l importance of a l l spec ies i n i t s community; i . e . , i n the f o l l o w i n g examples, n iche s i z e w i l l be approximated by importance v a l u e s . To i n v e s t i g a t e the r e l a t i o n s h i p between n iche s i z e and morpho log ica l v a r i a b i l i t y , popu la t ions o f n ine species of grasses tha t grow i n the study communities were sampled and scored f o r four phene t ic c h a r a c t e r s . The charac te r s were p l a n t h e i g h t , i n f l o r e s c e n c e l e n g t h , f l a g l e a f l e n g t h , and the number of s p i k e l e t s per i n f l o r e s c e n c e . These charac te r s were chosen i n par t because of precedent ( J a i n and M a r s h a l l 1967) and ease o f measurement, and p a r t l y because the f i r s t and t h i r d are 131 vege t a t i ve and the second and f o u r t h presumably are r e p r o d u c t i v e c h a r a c t e r s . F l a g l e a f l eng th may not be as i n c i d e n t a l a cha rac te r as i t seems, s ince Carr and Wardlaw (19 65) have demonstrated t ha t as much as 50% o f the carbon f i x e d by the f l a g l e a f goes to f r u i t p r o d u c t i o n . Table 16 summarizes the s t a t i s t i c s . The c o e f f i c i e n t of v a r i a t i o n (CV) i s s imply the s tandard d e v i a t i o n expressed as a percentage of the mean; v i z . , CV = s x 100/ Y (Soka l and Roh l f 1969). This s t a t i s t i c may be used to compare v a r i a b i l i t y i n popu la t i ons having w i d e l y d i f f e r e n t means of m e r i s t i c c h a r a c t e r s . TABLE 16. M o r p h o l o g i c a l v a r i a t i o n i n n ine grass s p e c i e s . C o e f f i c i e n t s of v a r i a t i o n fo r p l a n t he igh t ( C V i ) , i n f l o r e s c e n c e l eng th ( C V 2 ) , f l a g l e a f l eng th ( C V 3 ) , and number of s p i k e l e t s per i n f l o r e s c e n c e (CVi+K Importance Sample CV l CV 2 CV 3 CV it ECV Species Value s i z e P u e o i n e l l i a 2.7 35 0. 29 0. 17 0. 26 0. 28 1. 00 p u m i l a A g r o s t i s 7.2 69 0. 22 0. 26 0. 37 0. 45 1. 30 e x a r a t a F e s t u o a r u b r a 24. 5 61 0. 28 0. 30 0. 39 0. 49 1. 46 Des c h a m p s i a 38 . 6 55 0. 26 0. 28 0. 56 0. 52 1. 63 o e s p i t o s a A g r o s t i s 15 . 9 103 0. 18 0. 23 0. 32 0 . 39 1. 11 a e q u i v a l v i s P o a c u s i o k i i 1.9 64 0. 18 0. 20 0. 21 0. 20 0. 80 T r i s etum 3 . 2 60 0. 17 0. 18 0. 31 0. 23 0. 89 s p i o a t u m P h l e u m a l p i n u m 4.8 66 0. 22 0. 19 0. 34 0. 28 1. 03 F e s t u o a 24. 3 53 0. 16 0. 20 0. 48 0. 36 1. 20 v i r i d u l a 132 F igure 15 0 i l l u s t r a t e s the r e l a t i o n s h i p between abundance and v a r i a b i l i t y of four species of grasses from the s a l t marsh and four from the suba lp ine meadow (.Agrostis aequivalvis i s the on ly grass i n the sphagnum bogs) . The sum of the c o e f f i c i e n t s of v a r i a t i o n f o r a l l four charac te r s ( E C V i - i t ) has been p l o t t e d aga ins t the l o g of importance value f o r each s p e c i e s . C l e a r l y , the most abundant spec ies are a l s o the most v a r i a b l e , as was p r e d i c t e d from theory . Niche s i z e comparisons between communities are a l s o i n f o r m a t i v e , though h i g h l y s p e c u l a t i v e . F o l l o w i n g McNaughton and W o l f ' s (197 0) l o g i c , whereby the t o t a l amount of n iche space a v a i l a b l e to the p lan t s i n a g iven community i s approximated by the sum of i t s i n d i v i d u a l s p e c i e s ' impor tances , i t i s c l e a r from Tables 2-5 tha t t h i s p l a n t " c a r r y i n g c a p a c i t y " i s about the same for a l l four communit ies, p rov ided sphagnum moss i s i n c l u d e d i n the t o t a l of bog v e g e t a t i o n cove r . This being so , the average n iche s i z e should decrease from S a l t Marsh to Wade's Bog to Ogg's Bog to B l a c k w a l l Meadow, s ince the number of species inc reases i n tha t o rde r . As more species are added to a p l an t community, i n t e r s p e c i f i c compe t i t i on and n iche s p e c i a l i z a t i o n should i n c r e a s e , r e s u l t i n g i n narrower p h y s i o l o g i c a l l i m i t s o f t o l e r ance and sma l l e r n i c h e s , both fundamental and r e a l i z e d . There i s some evidence f o r the hypothes i s tha t spec ies o f harsh environments have l a r g e r fundamental n i c h e s . Typha latifolia i s a w i d e l y d i s t r i b u t e d spec ies tha t i s u s u a l l y much more abundant than T. a n g u s t i f o l i a , a spec ies g e n e r a l l y r e s t r i c t e d to s a l i n e h a b i t a t s (Smith 1967). Experiments on s a l t CO CO 8 F i g . 15'p). Log of importance value v s . the sum of c o e f f i c i e n t s of v a r i a t i o n f o r four morpho log ica l c h a r a c t e r s . FVI - F e s t u c a v i r i d u l a ; PAL - P h l e u m a l p i n u m ; TSP - T r i s e t u m s p i c a t u m ; PEP - Poa c u s i c k i i ; DCS - D e s c h a m p s i a c e s p i t o s a FRU - F e s t u c a r u b r a ; AEX - A g r o s t i s e x a r a t a ; PPU - P u c c i n e l l i a p u m i l a ; BM - mean o f suba lp ine meadow grasses ; AAE - A g r o s t i s a e q u i v a l v i s ; SM -mean o f s a l t marsh g rasses . 133 h Hf l lVA 33NVlcJ0dWI 134 t o l e r ance ( M c M i l l a n 19 59) i n d i c a t e , however, tha t T. angusti-folia can s u r v i v e i n both f r e sh and s a l t wa te r , whereas T. latifolia can occupy on ly f r e sh water s i t e s . Thus, T. angusti-folia, a l though i t has broader l i m i t s of t o l e r a n c e , i s r e s t r i c t e d i n abundance by i t s poorer compe t i t ive a b i l i t y (McNaughton and Wolf 1970). C o n n e l l ' s (19 61) work has y i e l d e d s i m i l a r r e s u l t s and i n t e r p r e t a t i o n s (see C o n n e l l 1972) f o r competing species of ba rnac les and other i n t e r t i d a l i n v e r t e b r a t e s . So the dominant s a l t marsh and bog spec ies may be viewed as broad-n iched but r e s t r i c t e d to t h e i r r e s p e c t i v e h a b i t a t s by r e l a t i v e l y poor compe t i t i ve a b i l i t y . Th i s has been the t r a d i t i o n a l view o f bog spec ies (Gorham 1953, 1957; Heinselman 1963) and evidence tha t many s a l t marsh spec ies can grow as w e l l in, fresh.'water as in. is a l t water c(if ; not better.) : has been accumulat ing ( M c M i l l a n 1959; Adams 1963; S t a l t e r and Batson 1969; Barbour 1970; Barbour and Davis 1970; C la rke and Hannon 197 0; Phleger 1971; Wa i se l 1972). In con junc t ion w i t h the above ev idence , note tha t ( F i g . 150) grasses o f B l a c k w a l l Meadow are l e s s v a r i a b l e than grasses of comparable importance value i n the S a l t Marsh. U n f o r t u n a t e l y , there i s on l y one grass species i n the sphagnum bogs, Agrostis aequivalvis, but i f i t i s taken to be r e p r e s e n t a t i v e i t appears tha t v a r i a b i l i t y i s , on the average, l e a s t i n suba lp ine meadow grasses (see dot ted l i n e through SM, AAE, and BM i n F i g . 150) . Th i s would be expected i f indeed average n iche s i z e decreases from s a l t marsh to sphagnum bog to subalp ine meadow. V a r i a b i l i t y i n popu la t ions of p l an t spec ies i s profoundly a f f ec t ed by the s p e c i e s ' breeding systems, which have so f a r 135 been over looked i n t h i s d i s c u s s i o n . T h e o r e t i c a l l y , predominant s e l f - f e r t i l i z a t i o n should reduce p o p u l a t i o n . v a r i a b i l i t y (Stebbins 1957a) and theory has i n many cases been borne out ( e g . , A t s a t t and Strong 197 0; S o l b r i g 1972). However, some inb reed ing species have mainta ined a h i g h l e v e l of p o p u l a t i o n v a r i a b i l i t y , presumably through o c c a s i o n a l i n t e r - and i n t r a p o p u l a t i o n a l o u t c r o s s i n g between s t r o n g l y homozygous b io types ( A l l a r d 1965; A l l a r d , J a i n and Workman 1967; J a i n and M a r s h a l l 1967; R o l l i n s 1967; J a i n , M a r s h a l l and Wu 1970). Of the nine spec ies of g ra s ses , four (Deschampsia cespitosa, A g r o s t i s e x a r a t a , T r i s e t u m s p i c a t u m , and F e s t u c a r u b r a ) are s e l f - i n c o m p a t i b l e and n e c e s s a r i l y s t r o n g l y ou tc rossed . Agrostis aequivalviSj F e s t u c a v i r i d u l a , and P h l e u m a l p i n u m are at l e a s t p a r t i a l l y s e l f - c o m p a t i b l e and though w i n d - p o l l i n a t e d probably moderately i n b r e d . Puccinellia pumila i s s e l f - c o m p a t i b l e and p a r t i a l l y cleis togamous w h i l e Poa cusickii i s agamospermous; both must be h i g h l y i n b r e d . Table 16 i n d i c a t e s tha t the c o e f f i c i e n t s of v a r i a t i o n f o r a l l four charac te r s and the t o t a l CV average h igher f o r the four s e l f - i n c o m p a t i b l e species than the other f i v e s p e c i e s , but the d i f f e r e n c e i n means i s i n no case s i g n i f i c a n t accord ing to a t - t e s t (P > 0 .05 ) . A l s o , Poa cusickii i s o v e r a l l the l e a s t v a r i a b l e s p e c i e s . Low w i t h i n -p o p u l a t i o n v a r i a b i l i t y i s to be expected i n agamospermous species (Gustafsson 1946-47) . H. Niche d i f f e r e n t i a t i o n . 136 Numerica l taxonomy o f f e r s an approach to the study of n iche d i f f e r e n t i a t i o n w i t h i n p l an t communities. Assuming tha t q u a n t i t a t i v e or q u a l i t a t i v e morpho log ica l and b e h a v i o r a l charac te r s are o f e c o l o g i c a l s i g n i f i c a n c e i n the l i f e o f p l a n t s , i t should be p o s s i b l e to quan t i fy the e c o l o g i c a l s i m i l a r i t i e s or d i s s i m i l a r i t i e s of a group of spec ies tha t c h a r a c t e r i s t i c a l l y grow toge the r . For example, a Festuca spec ies i s p h e n e t i c a l l y more l i k e a Deschampsia than a P o t e n t i l l a , but i s a Potentilla more l i k e a R a n u n c u l u s , an A n e m o n e , or an A r n i c a , e c o l o g i c a l l y speaking? Taxonomica l ly , these ques t ions are easy to answer, and the e c o l o g i c a l answers should be s i m i l a r , s i n c e a spec ies should be an e c o l o g i c a l u n i t as w e l l as a t axon . But an e c o l o g i c a l s i m i l a r i t y a n a l y s i s cou ld o f f e r i n t e r e s t i n g and perhaps s u r p r i s i n g i n s i g h t s . What spec ies i n the suba lp ine meadow i s e c o l o g i c a l l y most s i m i l a r t o Thalictrum occidentalel Does Gentiana douglasiana f u n c t i o n more l i k e Gentiana sceptrum or Trientalis arctica i n the sphagnum bogs? I w i l l t r y to answer these and s i m i l a r ques t ions by what amounts to a p a r t i a l d e s c r i p t i o n of each s p e c i e s ' n i c h e , n e c e s s a r i l y us ing on ly those charac te r s tha t are e a s i l y measured or observed and un fo r tuna t e ly o m i t t i n g p h y s i o l o g i c a l n iche components. The approach has been neo-Adansonian whereby equal weight i s g iven to a l l cha rac te r s used i n the a n a l y s i s . A s i m i l a r i t y measure fo r mixed q u a n t i t a t i v e and q u a l i t a t i v e a t t r i b u t e s (Anderson 1971) has been used. Anderson 's measure of s i m i l a r i t y i s as f o l l o w s . 137 I f a t t r i b u t e k i s q u a n t i t a t i v e and sca led to have approxi -mately u n i t range , l e t . f e = x i k x j k I f a t t r i b u t e A: i s q u a l i t a t i v e , l e t s = 0 w h e n *ih * * j k 13 k 0.5 when x ^ = x T h e n 1 m S . . = - Z S . , 7 13 m 13k where S . . i s the s i m i l a r i t y between o p e r a t i o n a l taxonomic 13 u n i t s (OTU's) . . and m the t o t a l number of a t t r i b u t e s . The d i s t ance d . . between OTU's . . i s then computed as 13 13 ^ d . . = (s . . + s . . - 2s . . ) 1 / 2 . 13 i i 33 13 The OTU's f o r each community are i t s c o n s t i t u e n t s p e c i e s . A t o t a l of 32 u n i t charac te r s were used to measure s i m i l a r i t y between OTU's. A u n i t cha rac te r i s def ined by Soka l and Sneath (19 63) as a "taxonomic cha rac te r o f two or more s t a t e s , which w i t h i n the study at hand cannot be subd iv ided l o g i c a l l y , except f o r s u b d i v i s i o n brought about by changes i n the method of c o d i n g " . Each u n i t charac te r has at l e a s t two s t a t e s . I have t r i e d to choose independent charac te r s but fo r the sake of completeness some redundancy was unavo idab le . The u n i t charac te r s are o u t l i n e d i n Table 17 and ( i f necessary) exp l a ined i n the f o l l o w i n g paragraphs. The l i f e - f o r m c l a s s i f i c a t i o n i s adopted from Raunkiaer (.1934). Therophytes are annuals i n which the renewal bud i s w i t h i n the seed coa t . Geophytes have perennat ing buds covered by s o i l , whereas the buds of hemicryptophytes are at or s l i g h t l y embedded i n the s o i l su r f ace . Chamaephytes are TABLE 17. E c o l o g i c a l u n i t c h a r a c t e r s . 138 U n i t charac te r Character s t a t e s Number o f s t a tes 1. l i f e - f o r m therophyte geophyte hemicryptophyte chamaephyte nanophanerophyte 5 2. organ of perennat ion seed only corm, t u b e r , or bulb b a s a l bud caudex rhizome bud stem bud 6 3. r oo t system taproot f a s c i c l e d f i b r o u s 3 4. stem form e rec t decumbent or matted acaulescent 3 5. stem cove r ing glabrous or s l i g h t l y pubescent moderately to densely pubescent , tomentose, v i l l o u s , e t c . g landular -pubescent g l andu la r 4 6. l e a f ( l e a f l e t ) s i z e l e p t o p h y l l nanophy l l m i c r o p h y l l mesophyl l macrophyl l 5 7. g r a s s , sedge, or rush l e a f w id th (at wides t p o i n t ) l e s s than 4 mm grea te r than 4 mm does not apply 3 8. l e a f form more or l e s s p lanar t e r e t e or i n v o l u t e 2 TABLE 17. (Continued) 139 U n i t charac te r Charac ter s t a t e s Number of s t a t e s 9. l e a f d i s p l a y b a s a l r o s e t t e h o r i z o n t a l (0-15 ) i n one plane h o r i z o n t a l i n s e v e r a l planes angled Q v e r t i c a l (70 or more) 5 10. l e a f margin e n t i r e - s e r r a t e l o b e d - i n c i s e d dissected-compound 3 11. l e a f p e r s i s t e n c e deciduous evergreen 2 12. l e a f t ex tu re membranous cor iaceous ( l e a t h e r y ) c a r t i l a g i n o u s f l e s h y or succu len t 4 13. l e a f cove r ing glabrous or s l i g h t l y pubescent moderately to densely pubescent , tomentose, v i l l o u s , e t c . g landular -pubescent g l andu la r 4 14. growth form s i n g l e , unbranched f r e e l y branched, rhizomatous or spreading ce sp i to se or clump-forming 3 15. vege t a t i ve propagat ion rhizome s t o l o n v i v i p a r y none 4 16. temporal s e p a r a t i o n homogamy 6 of sexua l func t ions weak dichogamy moderate dichogamy s t rong dichogamy monoecy d ioecy TABLE 17. (Continued) 140 U n i t cha rac t e r Charac ter s t a tes Number of s t a tes 17. p o l l i n a t i o n predominant ly s e l f - 12 mechanism p o l l i n a t i o n or c le i s togamy anemophily by muscid f l i e s by s y r p h i d f l i e s by bee f l i e s by s m a l l , s h o r t -tongued bees by bumble bees by b u t t e r f l i e s by hawk moths by ants by bee t l e s by hummingbirds 18. f lower c o l o r f lowers inconspicuous 10 g reen i sh whi te p ink orange red lavender purp le b lue y e l l o w 19. f lower n e c t a r i f e r y f a i n t 4 moderate s t rong none 20. f lower odor f a i n t 4 moderate s t rong none 21. f lower type amorphic 6 haplomorphic ac t inomorphic pleomorphic s tereomorphic zygomorpaic TABLE 17. (Concluded) 141 U n i t cha rac te r Character s t a t e s Number of s t a t e s 22* propagule.-type auxochore cyc lochore p terochore pogonochore desmochore sarcochore sporochore mic rosc l e rochore megasclerochore b a l l o c h o r e 10 23. d i s p e r s a l mechanism anemochory hydrochory epizoochory endozoochory autochory 5 24. p l a n t s ca rn ivorous +•/- 2 25. p l a n t s root" •„ p a r a s i t e s . . •_.. - . + /-i 2 26. p l a n t s ^ - f i x i n g + /- 2 27. es t imate of degree of vege t a t i ve p ropaga t ion 0.2 0.4 0.6 0.8 1.0 5 28. average he igh t of f.lower or i n f l . n l 29. average wid th of f l o w e r o r i n f l . n 2 30. average l eng th of f l ower or i n f l . n 3 31. t ime of f l o w e r i n g n 4 32. l eng th of f l o w e r i n g n 5 5 T o t a l 124 + In 1 142 p r o s t r a t e p l a n t s or low shrubs w i t h buds above the s o i l , but not over 2 5 cm above. Nanophanerophytes bear t h e i r buds between 0.25 and 2 m above the su r f ace . The l i f e - f o r m g e n e r a l l y f o l l o w s from the organ of pe renna t ion , but not n e c e s s a r i l y . For i n s t a n c e , Junous balticus i s rhizomatous but i s c l a s s e d as a geophyte (Clapham, T u t i n and Warburg 1962). Hemicryptophytes may perennate by means o f a b a s a l bud, a rhizome bud, or a caudex. The caudex i s understood here as the woody, p e r s i s t e n t base of an o therwise annual herbaceous stem, as i n Castitleja m i n i a t a . The l e a f or l e a f l e t s i z e c l a s s e s are a l s o taken from Raunkiaer (1934). H i s c l a s s i f i c a t i o n i s as f o l l o w s : 2 l e p t o p h y l l s - area s m a l l e r than 2 5 mm 2 nanophyl l s - 25 - 225 mm m i c r o p h y l l s - 225 - 2,025 mm2 mesophylls - 2,025 - 18,225 mm2 macrophyl l s - 18,2 25 - 164,025 mm2 The f u r t h e r d i s t i n c t i o n between graminoid leaves wider or narrower than 4 mm f o l l o w s Knight (1965). The t y p o l o g i c a l c l a s s i f i c a t i o n of f lowers i s tha t of Leppik (1957, 1968a S b ) , who desc r ibed them as succes s ive l e v e l s i n the genera l t r end of f l o r a l e v o l u t i o n . Whether L e p p i k ' s phylogeny i s v a l i d or not i s not p e r t i n e n t he re ; the f l o r a l types seem to be e c o l o g i c a l types as w e l l , i n genera l e x p l o i t i n g d i f f e r e n t groups of animal p o l l i n a t o r s . The s i x types a re : amorphic , haplomorphic , ac t i nomorph ic , p leomorphic , s te reomorphic , and zygomorphic. Amorphic f lowers are supposedly p r i m i t i v e c l u s t e r s of d i s c o l o r e d leaves wi thout 143 p a r t i c u l a r form. Haplomorphic types are c h a r a c t e r i z e d by many separate f lower pa r t s f r equen t ly s p i r a l l y arranged. A c t i n o -morphic types c o n s i s t of po lype ta lous f lowers w i t h t h e i r par t s f l a t t e n e d i n t o more or l e s s one p lane . Pleomorphic f lowers are s i m i l a r to ac t inomorphic f lowers but have c e r t a i n symmetr ica l numerate pa t t e rns of p a r t s ; e g . , t r i - , t e t r a - , or pentamery. Stereomorphic f lowers are t h r ee -d imens iona l and u s u a l l y have some s o r t of f l o r a l tube . Zygomorphic types are the h i g h l y s p e c i a l i z e d f lowers w i t h b i l a t e r a l symmetry and f r equen t ly concealed n e c t a r . Species of Compositae, subfamily T u b i f l o r a e must be scored p o s i t i v e fo r both zygomorphic and s tereomorphic f l o w e r s , and, as the cap i tu lum i s probably the u n i t o f i n s e c t p e r c e p t i o n , a l s o scored p o s i t i v e f o r , say , actinomorphy i n the case of A r n i c a spp. , or pleomorphy i n A c h i l l e a m i l l e f o l i u m . Observat ions of f l ower c o l o r and odor are n e c e s s a r i l y human and s u b j e c t i v e . However, animals (most i m p o r t a n t l y i n s e c t s ) seem to respond to the same smel ls as man, but t h e i r sense of s m e l l i s g e n e r a l l y keener , e s p e c i a l l y f o r scents tha t s i g n a l the presence of food or s exua l pa r tners (Free 19 7 0a; Kugler. 1970.; :Faegr i and van der P i j l 1971; F r i s c h 1971). S i m i l a r l y , the v i s u a l range of the spectrum i n the most important animal p o l l i n a t o r s does not d i f f e r much from man's , a l though there i s a s h i f t towards shor t e r wavelengths ( F a e g r i and van der P i j l 1971). Bees can d i s t i n g u i s h four c o l o r groups: y e l l o w , b l u e - g r e e n , b l u e , and u l t r a v i o l e t , but not red ( F a e g r i and van der P i j l 1971). However,- f lowers could not be scored f o r the presence o f u l t r a v i o l e t nec ta r guides , which are i n v i s i b l e to humans but appear to be f a i r l y common i n some angiospermous 144 groups (Daumer 1958; Lindauer 1967; E i s n e r et al. 1969; Ornduff and Mosquin 1970). The scheme of propagule types i s a simple m o r p h o l o g i c a l c l a s s i f i c a t i o n adopted from F r e n k e l (1970) and o u t l i n e d p r e v i o u s l y i n Table 13. Undoubtedly, separate c a t e g o r i e s f o r propagule types and d i s p e r s a l mechanisms i n t r o d u c e some redundancy i n t o the a n a l y s i s , but f r e q u e n t l y the a c t u a l mode of d i s p e r s a l cannot be i n f e r r e d from d i a s p o r e morphology. The only c a r n i v o r o u s s p e c i e s i n t h i s study i s Drosera rotundif'olia. Pedioularis braoteosa, Castilleja miniata, and C. parviflora are the only documented r o o t p a r a s i t e s ( K u i j t 1969). Trifolium wormskjoldiiLupinus latifolius, and Myrioa gale are the three s p e c i e s w i t h n i t r o g e n - f i x i n g r o o t nodules. Character s t a t e s were assigned to each OTU ( s p e c i e s ) of each community, and the e c o l o g i c a l d i s t a n c e (.d) c a l c u l a t e d f o r a l l p o s s i b l e species p a i r s w i t h i n a community. These d's are a l l presented as p a r t of Appendix 3, but some p o i n t s of g e n e r a l i n t e r e s t are d i s c u s s e d below. Ranges of values f o r d (0<_d<_l) a r e : S a l t Marsh 0.25 (DCSxppu) 0.62 (TW0*SCA) Wade's Bog 0.15 (RALxSCS) 0.63 (COBxVVI) Ogg's Bog 0.14 (RALxSCS) 0.63 (COBxVVI) B l a c k w a l l 0.19 (VSCxVDE) 0.62 (PDIxVVD) Meadow The most e c o l o g i c a l l y d i s t i n c t i v e s p e c i e s ( i . e . , the s p e c i e s with the h i g h e s t average e c o l o g i c a l d i s t a n c e , d) are Spergularia canadensis i n the s a l t marsh, Vaooinium vitis-idaea i n both bogs, and Veratrum viride i n the s u b a l p i n e meadow. 145 The average e c o l o g i c a l d i s t a n c e (d) b e tween•a i i - s p e c i e s . o f a g i v e n community i s 0 .46 , 0 .54, 0 .52 , and 0.49 fo r the S a l t Marsh, Wade's Bog, Ogg's Bog, and B l a c k w a l l Meadow, r e s p e c t i v e l y . That i s to" s ay , s a l t marsh spec ies a r e , on the average, the most e c o l o g i c a l l y equ iva l en t and sphagnum bog spec ies the most e c o l o g i c a l l y d i s t i n c t i v e , accord ing to t h i s a n a l y s i s . I have t r i e d to f i t these community d's i n t o the genera l scheme of t h i s i n v e s t i g a t i o n i n F i g . 151. To get some i n d i c a t i o n o f the r e l a t i v e s t rengths o f i n t e r s p e c i f i c compe t i t i on w i t h i n the d i f f e r e n t communit ies , I have c a l c u l a t e d f o r each the product of average vascu l a r p l a n t cover (C) t imes the absolu te value of the average community c o r r e l a t i o n c o e f f i c i e n t ( | r | ) t imes the community species d i v e r s i t y (# ' ) (see Sec t . I I I - I ) . I have p l o t t e d t h i s product aga ins t the average community e c o l o g i c a l d i f f e r e n c e or d i s t i n c t i v e n e s s (d ) . My i n t e r p r e t a t i o n of F i g . 151 i s tha t i t r epresen ts a p o r t i o n o f a p o t e n t i a l area upon which a l l v e g e t a t i o n types (or s t r a t a the reof ) i n the wor ld cou ld be p l o t t e d , i f subjec ted to s i m i l a r a n a l y s i s . The upper l e f t of t h i s f i g u r e ( s t rong e c o l o g i c a l s i m i l a r i t y , s t rong i n t e r s p e c i f i c compe t i t ion ) might represen t the s i t u a t i o n i n a s t ra tum of t r o p i c a l r a i n f o r e s t v e g e t a t i o n or a c h a p a r r a l shrub community; the lower r i g h t ( e c o l o g i c a l d i s s i m i l a r i t y , weak compet i t ion) by , f o r example, sphagnum bogs and Sonoran d e s e r t ; the lower l e f t ( e c o l o g i c a l s i m i l a r i t y , weak compet i t ion) by h i g h s a l i n i t y s a l t marshes, c o l d deser t s ( e g . , Great Bas in) and a r c t i c and a l p i n e t und ra ; the upper r i g h t ( e c o l o g i c a l d i s s i m i l a r i t y , s t rong compet i t ion) by t a l l grass p r a i r i e . 146 cu F i g . 151. Strength of i n t e r s p e c i f i c competition vs. average e c o l o g i c a l d i s t i n c t i v e n e s s . 100 95 90 85 80 4-75 70 65 60 55 50 45 40 35 30 chaparral shrubs? rain forest stratum? » Blackwall Meadow t a l l grass prairie? M Salt Marsh Great Basin desert? Sonoran desert? Wade's Bog Ogg's Bog H h H h 0.44 0.45 .0.46 0.47 0.48 0.49 0.50 0.51 0.52 0.53 0.54 0.55 0.56 0.57 0.58 ^» d (AVERAGE ECOLOGICAL DISTINCTIVENESS) 147 Fur ther a n a l y s i s o f the d's i n Appendix 2 cor robora tes some o f the s p e c u l a t i o n s made i n the d i s c u s s i o n ( i n Sec t . I I I - B ) on i n t e r s p e c i f i c c o r r e l a t i o n . In the bogs, d between a l l grasses and g r a s s - l i k e spec ies i s about 0 .34; between a l l shrubs , 0 .45. In the suba lp ine meadow, d f o r a l l graminoids i s 0 .35 ; f o r Compositae, 0 .39. Thus, as suggested p r e v i o u s l y , there i s g rea te r niche d i f f e r e n t i a t i o n among the shrubs i n the bogs and the meadow composites than among the graminoid s p e c i e s , and t h i s apparen t ly r e s u l t s i n s t ronger compe t i t i on among grasses and g r a s s - l i k e p l a n t s . One f i n a l p o i n t : i f v i s a measure of i n t e r s p e c i f i c c o m p e t i t i o n , and d of e c o l o g i c a l s i m i l a r i t y , and, f u r t h e r , i f the most d i s s i m i l a r spec ies compete the l e a s t (and i f the converse i s t r u e ) ; then there should be a p o s i t i v e c o r r e l a t i o n between r and d, f o r a g iven community. Such i s the case fo r a l l four communities. For a l l quadrat s i z e s , t h i s new r i s p o s i t i v e , though u s u a l l y weakly so. I t s s t r eng th inc reases i f the communities are subd iv ided i n t o a s s o c i a t i o n s ; e g . , i n the s a l t marsh, i f the spec ies are put i n t o two groups (h igh marsh v s ; mud f l a t s ) and the r computed w i t h i n these two groups, the v i s more p o s i t i v e than i f a l l spec ies are grouped toge the r . Th i s makes sense, s ince the e f f e c t s of i n t e r s p e c i f i c compe t i t i on w i l l be r e f l e c t e d more r o b u s t l y by c o r r e l a t i o n c o e f f i c i e n t s between spec ies t ha t c h a r a c t e r i s t i c a l l y grow together i n a s s o c i a t i o n s , than between spec ies of d i f f e r e n t a s s o c i a t i o n s . 147 «-I . Dominance, d i v e r s i t y , and s t a b i l i t y . P l a n t communities are u s u a l l y mixtures of unequa l ly abundant species tha t form a p r o g r e s s i o n from dominant through in te rmed ia te to r a r e s p e c i e s . W i t h i n a g iven community i t i s p o s s i b l e to es t imate the s u b d i v i s i o n o f n iche space by assuming tha t the importance values of the species c o n s t i t u t i n g the community are express ions of t h e i r r e l a t i v e n iche s i z e s . I f the species are then arranged i n a sequence from most to l e a s t important and the s p e c i e s ' p o s i t i o n s i n t h i s sequence are then p l o t t e d aga ins t the l o g of t h e i r r e s p e c t i v e importance v a l u e s , a curve of c h a r a c t e r i s t i c genera l form r e s u l t s (Whi t taker 1965, 1969, 1970a). This has been done f o r each o f the four study communities and the curves are presented i n F i g . 15 2A-D. Note tha t the curves are roughly s h a l l o w l y s igmoid and tha t the s lope decreases i n order from A to D i n the f i g u r e . The s igmoid shape r e f l e c t s the f ac t t ha t each community has a few dominant spec ies and a few r a re s p e c i e s , p lus a l a r g e number of spec ies of in te rmedia te abundance. Compet i t ion theory holds tha t species tend to evolve toward n iche d i f f e r e n t i a t i o n and r e d u c t i o n of i n t e r s p e c i f i c c o m p e t i t i o n , and the r e s u l t a n t - d i v i s i o n of n iche space i s manifested i n the forms of such dominance -d ive r s i t y cu rves . The steepness of the curve f o r the f l o r i s t i c a l l y poor s a l t marsh agrees w i t h W h i t t a k e r ' s obse rva t ions tha t steep s lopes are d e r i v e d from samples o f low d i v e r s i t y communities of r i g o r o u s p h y s i c a l environments. The gradua l moderation of the s lope found i n the curves f o r the bogs and the suba lp ine meadow i s c o n s i s t e n t w i t h the ' i g . 15 2. Dominance-diversity c u r v e s , f o r the four study communities. 149 i n c r e a s i n g d i v e r s i t y of these communit ies. The more equal s u b d i v i s i o n of n iche space i n the communi-t i e s of h ighe r d i v e r s i t y i s a l s o i n d i c a t e d by a community index of dominance, e i t h e r the DI of McNaughton ( i n McNaughton and Wolf 1970) or the A of Simpson (1949) . DI = 100(y „/Y) where y-^  2 i - s sum of the importance values o f the two most abundant spec ies in . the community and Y i s the t o t a l importance n 2 value of a l l spec ies i n the community; A. = ETT where TT i s the ^ 1 n n importance value of the nth spec ies i n the community. In e i t h e r case , the h ighe r the dominance i n d e x , the g rea t e r the c o n c e n t r a t i o n of abundance i n the fewer s p e c i e s . Ind ices of dominance fo r the four communities are l i s t e d i n Table 18. The two i n d i c e s g ive very s i m i l a r r e s u l t s and are l i n e a r l y r e l a t e d i n t h i s ins tance ( F i g . 153) . TABLE 18. Number of s p e c i e s , two i n d i c e s of dominance, and an index of d i v e r s i t y fo r the four study communities. N = number of spec ies sampled; DI = McNaughton's dominance i n d e x ; X = Simpson's dominance i n d e x ; H ' = the Shannon-Wiener index of d i v e r s i t y . Community N DI XxlO H ' S a l t Marsh 18 31.6 10.1 2.50 Wade's Bog 28 28. 7 8.2 2. 71 Ogg's Bog 41 27.2 7.7 3.03 B l a c k w a l l 45 24. 6 6.3 3.13 Meadow 150 a, Fig . 153. DI (McNaughton1s index of dominance), N (number of species i n a community) vs. H' (an index of d i v e r s i t y ) , A. (Simpson's dominance index). I 1 1 1 1 1 } 1 \ 1 1 1 1.0 1.4 1.8 2.2 2.6 3.0 3.2 H' 0.0 0.2 0.4 0.6 0.8 1.0 1.1 X 151 The matter of d i v e r s i t y r e q u i r e s f u r t he r comment. Species d i v e r s i t y i s a concept vague enough and of s u f f i c i e n t l y broad a p p l i c a t i o n tha t i t can be (and has been) v a r i o u s l y def ined ( c f . H u r l b e r t 1971). D i v e r s i t y i s o f ten equated w i t h s imple spec ies r i c h n e s s ; i . e . , the number of spec ies present i n a g iven a rea . However, as s t r i c t l y d e f i n e d , species d i v e r s i t y i s a f u n c t i o n of the numbers of species present ( spec ies r i c h n e s s ) and the evenness w i t h which the t o t a l number of i n d i v i d u a l s (or t o t a l biomass) i n a community i s d i s t r i b u t e d among these spec ies ( spec ies e q u i t a b i l i t y ) . D i v e r s i t y and r i c h n e s s are u s u a l l y p o s i t i v e l y c o r r e l a t e d , but not n e c e s s a r i l y so (Johnson and Raven 1970; H u r l b e r t 1971). In the four study communit ies, the number of spec ies per community i s l i n e a r l y r e l a t e d to the spec ies d i v e r s i t y o f these communities ( F i g . 153) . D i v e r s i t y can be c a l c u l a t e d by a number of formulas (Mcintosh 1967a; L loyd et al. 1968; H u r l b e r t 1971; Whi t t aker 1972). The most commonly used i s the Shannon-Wiener i n f o r m a t i o n i n d e x , H ' = - p ^ l o g p ^ , where H ' i s the species d i v e r s i t y and p^ i s the p r o p o r t i o n of i n d i v i d u a l s (or biomass) i n the i - t h s p e c i e s . Th i s f u n c t i o n i s d e r i v e d from in fo rma t ion theory accord ing to the l o g i c t h a t , s i nce d i v e r s i t y i s a f u n c t i o n of the number of p o s s i b l e i n t e r a c t i o n s i n a system and the degree to which they are s t r u c t u r e d (Johnson and Raven 1970), d i v e r s i t y should inc rease as the number of spec ies inc reases and as the d i s t r i b u t i o n o f i n d i v i d u a l s i n t o spec ies becomes more even. The concept of d i v e r s i t y has proven most u s e f u l i n i n t e r p r e t a t i o n s of l a r g e - s c a l e p o p u l a t i o n a l pa t te rns i n na ture . For example, spec ies d i v e r s i t y o f both f l o r a s and faunas has 152 repea ted ly been observed to inc rease i n a g rad ien t from c o l d c l ima te s toward the warm t r o p i c s and from h i g h e l e v a t i o n s downward ( F i s c h e r 1960; MacArthur 1965; P ianka 1966; Baker 1970). Rough p o s i t i v e c o r r e l a t i o n s have been made between the area of i s l a n d s and the d i v e r s i t y of t h e i r b i o t a (MacArthur and Wi l son 1967; Johnson et al. 1968; Johnson and Raven 1970, 1973; S i m b e r l o f f 1970). Pa t te rns of d i v e r s i t y have been s tud i ed i n r e l a t i o n to w i t h i n - and between-habi ta t environmenta l he t e ro -gene i ty (Johnson et al. 1968; Whi t t aker 1970a, 1972) and as adjuncts to vege t a t i on c l a s s i f i c a t i o n s w i t h i n c e r t a i n geograph ica l areas (Whi t taker 1965; Monk 1967; A u c l a i r and Goff 1971; d e l Mora l 1973). More s p e c i a l i z e d i n v e s t i g a t i o n s have revea led both d i r e c t . (ednnell and Or ias 1964; MacArthur 1969; Singh and M i s r a 1969) and i nve r se (McNaughton 1968; Margalef 1969; Whi t taker 1972) c o r r e l a t i o n s between d i v e r s i t y and p r o d u c t i v i t y . In p l an t communit ies , attempts to produce c o n s i s t e n t c o r r e l a t i o n s between d i v e r s i t y and a number of environmental f a c t o r s such as mois ture (Monk 1967; A u c l a i r and Goff 1971; Whi t taker 1972) , a l t i t u d e (Whi t taker and N i e r i n g 1965; Daubenmire 1970), s o i l f e r t i l i t y and pH (Loucks 1962; Monk 1967), have not been s u c c e s s f u l . D i v e r s i t y i s g e n e r a l l y reduced by a i r p o l l u t i o n (Gordon and Gorham 1963; G i l b e r t 1965; Skye 1968; Nash 1972), gamma i r r a d i a t i o n (Woodwell 1967; Woodwell and Whi t t ake r 1968) , and ove rg raz ing (Whi t taker 1972), but Harper (19 69) has demonstrated tha t l i g h t or moderate g r a z i n g may a c t u a l l y inc rease d i v e r s i t y . D i v e r s i t y o f t en inc reases w i t h success ion (Margalef 1963; Monk 1967; Odum 1969; Reiners et al. 1971) , but i n some cases 153 decreases from l a t e s u c c e s s i o n a l stages to the c l imax (Loucks 1970; A u c l a i r and Goff 1971). Reiners et al. (1971) fo l lowed changes i n d i v e r s i t y dur ing success ion on g l a c i a l moraines of known age i n G l a c i e r Bay, A l a s k a . They found tha t an i n i t i a l r a p i d inc rease i n d i v e r s i t y dur ing the f i r s t 10 0 years was fo l l owed by a more g radua l inc rease to a maximum i n the muskeg steady s ta te (c l imax) at 200 years p lus (up to 1500 y e a r s ? ) . Success ion at G l a c i e r Bay proceeds from bare ground to shrub t h i c k e t s to a l d e r and cottonwood f o r e s t s t o S i t k a spruce and hemlock f o r e s t s and e v e n t u a l l y v i a p a l u d i f i c a t i o n to muskeg. Inasmuch as I i m p l i c a t e d p a l u d i f i c a t i o n of c o a s t a l f o r e s t i n the format ion o f the Tof ino area sphagnum bogs, one would expect tha t Wade's Bog, the most s u c c e s s i o n a l l y advanced, would have a h i g h e r d i v e r s i t y than Ogg's Bog. However, such i s not the case (Table 18 ) . There i s l i t t l e agreement as to the causes of d i f f e r e n c e s and g rad ien t s i n species d i v e r s i t y . Attempts have been made to e x p l a i n pa t te rns of d i v e r s i t y i n terms o f t ime a v a i l a b l e f o r e v o l u t i o n (Sanders 1969; Baker 1970), s p a t i a l he te rogene i ty of the p h y s i c a l environment (Ashton 1969; MacArthur 1969; Richards 1969; Whi t t aker 1972), i n t e r s p e c i f i c compe t i t i on (Dobzhansky 1950; M i l l e r 1969; Whi t t aker 1969) i n c l u d i n g a l l e l o p a t h y '.(Whittaker 1970b; Whi t t aker and Feeny 1971) , p r eda t i on pressure (Paine 1966; Spight 1967; Harper 1969; Janzen 1970) , hos t -p a r a s i t e i n t e r a c t i o n s (Barbehenn 1969), c l i m a t i c s t a b i l i t y or environmental p r e d i c t a b i l i t y (Sanders 19 68; S lobodk in and Sanders 1969), p r o d u c t i v i t y (Conne l l and Or ias 1964; McNaughton 1968; Singh and M i s r a 1969) , r e l a t i v e r a t e s of 154 of s p e c i a t i o n (Simpson 1964, 1969; S t e h l i et al. 1969), and va r ious combinations of the above (see P ianka 1966; Baker 1970; and Johnson and Raven 1970 fo r genera l d i s c u s s i o n s ) . This b r ings us to the ques t ion of the r e l a t i o n s h i p between d i v e r s i t y and s t a b i l i t y . As used he re , s t a b i l i t y does not r e f e r to the envi ronmenta l s t a b i l i t y o f the p rev ious paragraph, but i s to be understood r a t h e r as the s t a b i l i t y through time of a p l a n t community type . More p r e c i s e l y , the s t a b i l i t y of a community may be def ined as i t s r e s i s t a n c e to e x t e r n a l p e r t u r b -a t ions and consequent p e r s i s t e n c e i n time (Odum 1969; Pres ton 1969). Communities of g rea te r d i v e r s i t y are then s a i d to be more s t ab l e (Hutchinson 1959; Odum 1969; Whi t taker and Woodwell 1972; see Woodwell and Smith 1969). Given t h i s , and the f a c t tha t each o f the four study communities has a d i f f e r e n t species d i v e r s i t y , can I v a l i d l y c l a i m t h a t , f o r example, the s a l t marsh i s the l e a s t s t a b l e , and the subalpine meadow the most s t ab l e o f these communities? I t i s important to s p e c i f y the time s ca l e i n v o l v e d . In most d i s c u s s i o n s of d i v e r s i t y and s t a b i l i t y , a long- te rm ( e v o l u t i o n a r y ) view r a the r than a sho r t - t e rm ( s u c c e s s i o n a l ) view i s at l e a s t i m p l i c i t . Thus, we are d e a l i n g w i t h the p e r s i s t e n c e of a community type i n e v o l u t i o n a r y t i m e ; s u c c e s s i o n a l t rends are subl imated (McCullough 1970). When one speaks of the s t a b i l i t y of a community, one must i n c l u d e the s u c c e s s i o n a l phases of tha t community. For example, the e v o l u t i o n a r y future of the s a l t marsh community type i n v o l v e s both the p ioneer mud f l a t stages and the advanced h igh marsh, as w e l l as the degene ra t ive , eroded stages of the marsh ( c f . 155 R e d f i e l d 1972); heather meadows i n England ( B a r c l a y - E s t r u p 1970, 1971; B a r c l a y - E s t r u p and Gimingham 1969) and sugar maple f o r e s t s i n Wiscons in (Loucks 1970) evolve as systems o f seres c y c l e d by p e r i o d i c , random pe r tu rba t i ons ( c f . Watt 1947). The e v o l u t i o n a r y consequence of the proposed d i r e c t r e l a t i o n s h i p between d i v e r s i t y and s t a b i l i t y should be a p o t e n t i a l l y se l f -augment ing inc rease i n d i v e r s i t y (Hutchinson 1959; Whi t t aker 1969; Whi t t ake r and Woodwell 1972); i . e . , i f d i v e r s i t y inc reases s t a b i l i t y , there should be s e l e c t i o n f o r i n c r e a s e d d i v e r s i t y , which i n t u r n confers g rea te r s t a b i l i t y , e t c . Such a s e l e c t i v e mechanism r e q u i r e s tha t the p l a n t community i t s e l f be a u n i t of e v o l u t i o n (Whi t taker and Woodwell 1972). Th i s i s t h e o r e t i c a l l y f e a s i b l e , as to be a s e l e c t i v e uni t ' an e n t i t y need on ly have v a r i a t i o n , r e p r o d u c t i o n , and h e r i t a b i l i t y (Lewontin 1970). Genes, c e l l s , organs , organisms, p o p u l a t i o n s , spec ies , communit ies , and ecosystems f u l f i l l these requirements and thus a l l can evolve (Lewontin 1970). H e r i t a b i l i t y w i l l be g r e a t e r , and the r a t e of e v o l u t i o n f a s t e r , i n those e n t i t i e s w i t h the t i g h t e s t i n t e r n a l o r g a n i -z a t i o n (Lewontin 1970; Stebbins and Lewontin 1972). The c loseness of the o r g a n i z a t i o n decreases con t inuous ly i n the p r o g r e s s i o n : gene, c e l l , o rgan , organism, p o p u l a t i o n , s p e c i e s , community, ecosystem (Baker 1966a); or " . . . c h a n c e p lays a grea ter r o l e at the ecosystem end of the p rog re s s ion" (Langford and B u e l l 1969). A p l an t community may be viewed as a more or l e s s i n t e g r a t e d assemblage of spec ies r e s u l t i n g from " n a t u r a l s e l e c t i o n ope ra t i ng between groups o f organisms and ad jus t i ng t h e i r mutual s t r a t e g i e s to permit i n c r e a s i n g d i v e r s i t y and more e f f i c i e n t environmenta l e x p l o i t a t i o n . . . " (Harper 19 69) . Thus, a community has c h a r a c t e r i s t i c s such as growth, m a t u r i t y , homeostas is , and energy f l u x tha t correspond to those o f o ther b i o l o g i c a l e n t i t i e s . R e l a t i o n s h i p s such as h e r b i v o r e -p l a n t ( E h r l i c h and Raven 1964; Breedlove and E h r l i c h 1968; Janzen 1969, 1970; B e a t t i e , Breed love , and E h r l i c h 1973) , p a r a s i t e - h o s t (Person 1959; Chabora and P imen te l 1970), p reda tor -p rey ( H o l l i n g 196 5 ) , and p o l l i n a t o r - p l a n t i n t e r a c t i o n s ( F a e g r i and van der P i j l 1971) , symbioses (Janzen 1966; Henry 19 1967; Sco t t 1969), and p o s s i b l e synergisms (Baker , Cruden, and Baker 1971; Po ja r 1973b) w i l l by gene t ic feedback and p o p u l a t i o n r e g u l a t i o n inc rease the complexi ty and i n t e g r a t i o n o f the ecosystem, i n c r e a s i n g i t s homeostasis and presumably i t s s t a b i l i t y (Brock 1967; P imente l 1968; c f . H a i r s t o n et al. 1960 ; Murdoch 1966 ;•* S lobodk in et al. 1967 , and E h r l i c h and B i r c h 1967). Note tha t t h i s does not r e q u i r e an organismic (Clements 19 36) concept of the p l an t community, nor does i t s t r i c t l y conform to the n o t i o n of a community as merely a f o r t u i t o u s assemblage of i n d i v i d u a l spec ies (Gleason 1926, 1939). Ra ther , t h i s approach appropr ia t e s elements of both t r a d i t i o n a l l y opposed ( c f . Whi t t ake r 1962, 19 67; Daubenmire 19 66; Mcin tosh 1967b, 1970, 1972; Langford and B u e l l 1969) schools of synecology. Species do evolve toward n iche and h a b i t a t d i f f e r -e n t i a t i o n , r e d u c t i o n o f c o m p e t i t i o n , and i n d i v i d u a l i t y o f d i s t r i b u t i o n (Whi t taker 1967, 1969, inter alia). However, superimposed on the spec ies e v o l u t i o n i s the h igher order 157 e v o l u t i o n of the community toward inc reased homeostasis (Odum 1969). I n t e r s p e c i f i c compe t i t i on c o n t i n u a l l y a p p l i e s a d i v i s i v e force to aggregat ions of s p e c i e s ; t h i s i s countered by the cohesive or c e n t r i p e t a l fo rce of s e l e c t i o n f o r community homeostasis and s t a b i l i t y . Now, a l l t h i s begs the q u e s t i o n , Does inc reased d i v e r s i t y really i nc rease s t a b i l i t y ? I can accept the argument tha t g rea te r d i v e r s i t y w i l l inc rease community s t a b i l i t y i n the face of a b i o l o g i c a l p e r t u r b a t i o n . For example, a monoculture (say a Midwestern c o r n f i e l d ) would be most s u s c e p t i b l e to an outbreak of a v i r u l e n t pathogen or p a r a s i t e or an h e r b i v o r e epidemic . Fur thermore, the more d i v e r s e a community i s , the b e t t e r i t should accommodate l e s s c a t a s t r o p h i c , commonplace occurrences such as death and replacement o f i n d i v i d u a l s , windthrow, d i s tu rbance by g r a z i n g or burrowing a n i m a l s , and en t ry of new t a x a . On the other hand, I t h i n k tha t p h y s i c a l f a c t o r s tha t cou ld d i s r u p t a community ( f i r e , g l a c i a t i o n , drought , r i s e and f a l l of the water t a b l e , c l e a r - c u t t i n g , p o l l u t i o n , b u l l d o z e r s , e t c . ) would act more i n d i s c r i m i n a t e l y , r e g a r d l e s s of community d i v e r s i t i e s . P l a n t communities have been shown to be s e n s i t i v e to the e f f ec t s of i o n i z i n g r a d i a t i o n (Woodwell 1967, 1970; Woodwell and Whi t t aker 1968), p e s t i c i d e s (Cant lon 1969; Mosser et al. 1972) , and e u t r o p h i c a t i o n (Hurd et al. 1971), as w e l l as to more heavy-handed treatments such as c l e a r - c u t t i n g and h e r b i c i d e a p p l i c a t i o n (Bormann et al. 1968; L ikens et al. 1970). The mechanisms of r ecovery from such d i s tu rbances have on ly begun to be s t ud i ed (L ikens et al. 1969; L ikens and Bormann 1972 158 Marks and Bormann 19 72) . The s tud ies have been done e i t h e r wi thou t the r e l a t i o n s h i p between d i v e r s i t y and s t a b i l i t y i n mind, or they are too e q u i v o c a l ( c f . Rosenzweig 19 71 and M c A l l i s t e r et al. 1972) fo r g e n e r a l i z a t i o n . Most o ther data o f fe red as evidence are l a r g e l y phy togeograph ica l and n e c e s s a r i l y anecdo ta l (see MacArthur and Wi l son 1967; S i m b e r l o f f 19 70; MacArthur 19 72; Diamond 19 73) . A recen t experiment (Hurd et al. 1971) more d i r e c t l y apropos the problem i n d i c a t e d t h a t , at l e a s t a t the l e v e l of pr imary producers ( p l a n t s ) , s t a b i l i t y was p o s i t i v e l y c o r r e l a t e d w i t h d i v e r s i t y . However, these r e s u l t s have been quest ioned ( c f . Harger et al. 1972; H o l t et al. 1972) , and a n o t - a l t o g e t h e r -comparable experiment by H a i r s t o n et al. (19 68) concluded tha t " . . . m u c h more exper imenta l and o b s e r v a t i o n a l work i s necessary before the nature of any f u n c t i o n a l r e l a t i o n s h i p between d i v e r s i t y and s t a b i l i t y can be c la imed w i t h conf idence" I agree. 159 J . Index o f p o t e n t i a l r ecombina t ion . The v a r i e t y of p l a n t gene t i c systems i n nature r e f l e c t s t h e i r s u s c e p t i b i l i t y to h e r e d i t a b l e v a r i a t i o n , a d a p t a t i o n , and n a t u r a l s e l e c t i o n ( D a r l i n g t o n 19 39; Grant 1958). That the d i v e r s i t y of these systems i s not random suggests tha t c o r r e l a t i o n s e x i s t between c e r t a i n k inds o f r ep roduc t ive s t r a t e g i e s and p a r t i c u l a r k inds o f gene t ic systems. The nonrandom v a r i a t i o n manifests i t s e l f i n a number of r ep roduc t i ve methods tha t embody a c h a r a c t e r i s t i c combinat ion or syndrome o f p o s i t i v e l y c o r r e l a t e d c h a r a c t e r s , m o r p h o l o g i c a l , p h y s i o -l o g i c a l , c y t o l o g i c a l , and e c o l o g i c a l (Ornduff 1969). For i n s t a n c e , herbaceous spec ies tha t are w i n d - p o l l i n a t e d and wind-d i spe r sed tend to have: reduced, inconspicuous f l o w e r s , o f ten u n i s e x u a l o r , - ' i f h e r maphrod i t i c , s t r o n g l y dichogamous ; f lowers aggregated i n t i g h t , many-flowered i n f l o r e s c e n c e s ; anthers exser ted and w i t h c o p i o u s , d r y , l i g h t ' p o l l e n ; exser ted stigmas w i t h a l a rge surface a r ea ; s m a l l , numerous propagules of ten beset w i t h winged, h a i r l i k e , or plumose appendages; and l a r g e , clumped popu la t ions occupying open h a b i t a t s ( P i j l 19 69; Whitehead 1969; F a e g r i and van der P i j l 1971). As another , l e s s i n c l u s i v e example, morpho log ica l dimorphism of f l o r a l pa r t s ( i . e . , d i s t y l y ) and d i a l l e l i c s e l f - i n c o m p a t i b i l i t y are two independent fea tures o f breeding systems g e n e r a l l y found toge ther presumably becauise they produce, i n combina t ion , an inc reased e f f i c i e n c y of c r o s s - p o l l i n a t i o n and c r o s s -f e r t i l i z a t i o n ( V u i l l e u m i e r 1967). I t i s p o s s i b l e to i n v e s t i g a t e the gene t ic systems o f 160 p l a n t s i n an e v o l u t i o n a r y c o n t e x t , keeping i n mind tha t these systems f u n c t i o n p r i m a r i l y i n ba l anc ing constancy and v a r i a -b i l i t y i n r ep roduc t ion (Stebbins 19 50; Grant 19 50) . The e f f i c i e n c y of t h i s compromise between immediate f i t n e s s and long-range f l e x i b i l i t y i s best eva lua ted by c o n s i d e r a t i o n of the c o n t r o l of r ecombina t ion . R e l a t i v e m u t a t i o n a l r a t e s o f h ighe r p l a n t spec ies are too p o o r l y known to assess m u t a t i o n a l c o n t r i b u t i o n s to gene t i c v a r i a b i l i t y , so i t i s necessary i n t h i s i n v e s t i g a t i o n to assume tha t the c h a r a c t e r i s t i c mutat ion ra tes of s e x u a l l y reproducing h ighe r p l a n t s are approximate ly the same, or at l e a s t of the same order of magnitude. The p o t e n t i a l performance o f d i f f e r e n t recombinat ion systems i n the genera t ion and maintenance of gene t ic v a r i a b l i t y can then be compared. In the f o l l o w i n g d i s c u s s i o n I have o u t l i n e d a scheme to evalua te the recombinat ion p o t e n t i a l of each species i n the study communities. Many o f the ideas are modi f ied from papers by F r y x e l l (1957) , Grant (1958) , Baker (1959) , C a r l q u i s t (1966) , Mosquin (1966) , and Ornduff (1969). The approach i n v o l v e s n u m e r i c a l l y s c a l i n g va r ious c y t o l o g i c a l , m o r p h o l o g i c a l , and e c o l o g i c a l components of the gene t i c system and combining values f o r a l l components i n a f i n a l Index of P o t e n t i a l Recombination ( I . P . R . ) fo r each s p e c i e s . W i t h i n a g iven component ( e g . , l e v e l of p l o i d y ) , there i s u s u a l l y a number of s t a t e s ( e g . , o c t o p l o i d and above, h e x a p l o i d , t e t r a p l o i d , d i p l o i d ) tha t have^been.- arranged ' in,.order;.6.f' i n c r e a s i n g p o t e n t i a l r ecombina t ion . 1. Length of gene ra t i on . 161 "The recombinat ion system regu la t e s the genera t ion of v a r i a b i l i t y by r e s t r i c t i n g the types o f gametes produced and the types o f zygotes formed" (Grant 1958). This r e g u l a t i o n i s imposed dur ing each success ive sexua l gene ra t ion . The genera t ion l eng th o f d i f f e r e n t p l a n t spec ies i s h i g h l y v a r i a b l e , so the amount of recombinat ion generated per u n i t t ime per spec ies w i l l be a f u n c t i o n of the genera t ion l e n g t h . A l l o ther t h ings be ing e q u a l , annuals or s h o r t - l i v e d p e r e n n i a l s should r e a l i z e more recombinat ion per u n i t time than l o n g - l i v e d p e r e n n i a l s and woody p l a n t s . A l s o , l engthy l i f e c y c l e s cou ld r e s u l t i n c r o s s i n g between parents and o f f s p r i n g and thus inc rease inbreed ing (Mosquin 1966). 1 - woody p l an t s 2 - l o n g - l i v e d herbaceous pe renn ia l s 3 - s h o r t - l i v e d herbaceous pe renn i a l s 4 - annuals 2. B a s i c chromosome number. Independent assortment of the chromosomes at meios i s w i l l recombine genes borne on separate chromosomes. The grea te r the number of chromosomes, the g rea te r the p o t e n t i a l recombinat ion (Grant 1958, 19 71; Stebbins 19 71b) . Al though the number of p o s s i b l e chromosome combinations inc reases e x p o n e n t i a l l y w i t h h a p l o i d chromosome number, I have chosen to reduce the p o s s i b i l i t i e s to a much s m a l l e r s c a l e , namely tha t def ined by 162 x (bas ic chromosome number)/2. The range of the sca l e i n t h i s study would be 3 (x = 6 f o r T r i g l o o h i n m a r i t i m u m and P l a n t a g o m a o r o o a r p a and P. m a r i t i m a ) to 8.5 (x = 17 fo r N e p h r o -p h y l l i d i u m o r i s t a - g a l l i ) . 3. R e l a t i v e chromosome l e n g t h . Recombination o f l i n k e d genes i s promoted by a h igh chiasma frequency. I l a c k the data to c a l c u l a t e a recombina t ion index (Stebbins 1950) f o r each s p e c i e s , but w i l l use r e l a t i v e chromosome l eng th (based on camera l u c i d a drawings ( F i g s . 14-110) of microsporocyte m e i o t i c chromosomes) as an express ion of c rossover potential::,.--since the. number of chiasmata tends to inc rease w i t h chromosome l eng th (Swanson 1957; Stebbins 1971b). Q u a l i t a t i v e es t imates of chromosome leng th have been sca led from 1 to 7. 1 - e g . , J u n o u s spp., C a r e x spp. 3 L u p i n u s l a t i f o l i u s . 2 - e g . , V a o o i n i u m s p p . , G a u l t h e r i a s h a l l o n , V a l e r i a n a s i t c h e n s i s 3 V e r o n i c a c u s i c k i i , E p i l o b i u m a l p i n u m . 3 - e g . , Ledum g r o e n l a n d i c u m 3 L i n n a e a b o r e a l i s , G l a u x m a r i t i m a , S p e r g u l a r i a c a n a d e n s i s 3 C a s t i l l e j a m i n i a t a . 4 - e g . , S a l i o o r n i a v i r g i n i c a 3 S a n g u i s o r b a o f f i c i n a l i s 3 A r n i c a m o l l i s 3 P h l o x d i f f u s a . 5 - e g . , P l a n t a g o m a r i t i m a 3 P u o c i n e l l i a p u m i l a 3 A p a r g i d i u m b o r e a l e 3 G e n t i a n a d o u g l a s i a n a 3 S i l e n e p a r r y i . 6 - e g . , D e s o h a m p s i a o e s p i t o s a , G e n t i a n a s c e p t r u m 3 F e s t u o a v i r i d u l a 3 C l a y t o n i a l a n c e o l a t a , S e n e c i o t r i a n g u l a r i s . 7 - e g . , M a i a n t h e m u m d i l a t a t u m , E l y m u s g l a u o u s . 4 . L e v e l of p l o i d y . 16 3 P o l y p l o i d y i s cons idered to promote and preserve pheno-t y p i c u n i f o r m i t y i n popu la t ions wh i l e r e t a r d i n g species e v o l u t i o n a r y change (Stebbins 1950, 1971b; Mosquin 1966; De Wet 1971a). The d i s r u p t i v e e f f e c t s of muta t ion , r ecombina t ion , and s e l e c t i o n tend to be buf fe red by polysomic i n h e r i t a n c e (Dawson 1962; Stebbins 1971b). Presumably the b u f f e r i n g e f f e c t inc reases w i t h h ighe r p l o i d y l e v e l s . P o l y h a p l o i d y ( f u n c t i o n a l hap lo idy r e s u l t i n g from a r e v e r s a l o f p o l y p l o i d y ) i s qu i t e p o s s i b l e i n f l o w e r i n g p l a n t s ( c f . Raven and Thompson 1964; Jones 1970; Ornduff 1970a; Stebbins 1970b; De Wet 1971b; Anderson 1972), but i s not r e a l l y important i n t h i s a n a l y s i s , s ince the p l o i d y s ta tus quo i s under c o n s i d e r a t i o n , not i t s mode of o r i g i n . 1 - o c t o p l o i d and up 2 - h e x a p l o i d 3 - t e t r a p l o i d 5 - d i p l o i d The breeding system of f l o w e r i n g p l a n t s , through a v a r i e t y o f morpho log ica l and p h y s i o l o g i c a l mechanisms, c o n t r o l s the amount of o u t c r o s s i n g i n spec ies popu la t ions and consequently e x e r c i s e s a powerful c o n t r o l <over the amount of gene t i c v a r i a b i l i t y present i n a p o p u l a t i o n . The most obvious o f these mechanisms w i l l be d i scussed under headings 5-12. 5. Separa t ion of s exua l func t ions i n t ime . 164 Dichogamy i s the asynchronous matura t ion of s t igma and anther . I t i n c l u d e s both protandry ( p o l l e n a v a i l a b l e before st igma i s mature) and protogyny (s t igma r e c e p t i v e before the p o l l e n i s shed) . Homogamy i s the oppos i te c o n d i t i o n , w i t h both sexua l func t ions o c c u r r i n g at the same t ime . The g rea te r the degree o f dichogamy, the h i g h e r the p r o b a b i l i t y o f out -c r o s s i n g (Mosquin 1966; Kug le r 1970; F a e g r i and van der P i j l 1971). 1 - homogamy 2 - moderate dichogamy 4 - s t rong dichogamy ( i nc ludes d ioecy) 6. Separa t ion of sexua l func t ions i n space. Herkogamy ( F a e g r i and van der P i j l 19 71) i s the s p a t i a l s epa ra t ion o f anthers and s t igma w i t h i n the same f l o w e r . Monoecy i s the c o n d i t i o n of s epa ra t ion of the sexes i n d i f f e r e n t f lowers of the same p l a n t ; d ioecy i s the sepa ra t ion of the sexes on d i f f e r e n t p l a n t s . Dioecy may be cons idered the u l t i m a t e i n morpho log ica l adap ta t ion fo r o u t c r o s s i n g . C l e a r l y , o u t c r o s s i n g and p o p u l a t i o n v a r i a b i l i t y w i l l be promoted by p rog re s s ive s p e c i a l i z a t i o n toward d ioecy (Grant 1958; Baker 1959; Mosquin 1966; C a r l q u i s t 1966). 1 - hermaphrodi te , sexua l organs adjacent ( e g . , Drosera r o t u n d i f o l i a , S p e r g u l a r i a canadensis') 2 - herkogamic hermaphrodite ( e g . , Kalmia polifolia, 165 P l a n t a g o m a c r o o a r p a ) 3 - monoecy ( e g . , C a r e x o b n u p t a , C a r e x p l u r i f l o r a ) 4 - p a r t i a l d ioecy ( e g . , . T h a l i o t r u m o o o i d e n t a l e ) 5 - s t r i c t (?-).-:dioecy ( e g . , Myrioa g a l e , A n t e n n a r i a l a n a t a ) Many spec ies of Compositae have u n i s e x u a l f lowers ( u s u a l l y p i s t i l l a t e ray f l o r e t s ) mixed w i t h a m a j o r i t y of hermaphrodite f lowers i n the head. Such asteraceous spec ies w i l l be c l a s sed as in t e rmed ia te between ca t ego r i e s 1 and 2 above. 7. H e t e r o s t y l y . Species having f lowers w i t h two or more d i s t i n c t stamen: s t y l e l eng th r a t i o s i n d i f f e r e n t p l an t s are termed h e t e r o s t y l o u s . I n d i v i d u a l s having f lowers w i t h long s t y l e s and shor t stamens may e x i s t i n the same p o p u l a t i o n as those having f lowers w i t h shor t s t y l e s and long stamens (Darwin 1877; Whitehouse 1959; K u g l e r 1970; F a e g r i and van der P i j l 1971). H e t e r o s t y l y o f t en accompanies i n c o m p a t i b i l i t y systems (Pandey 19 60) such tha t int ramorph s e l f - s t e r i l i t y e x i s t s ; e g . , between a shor t s t y l e and long anthers (from a s h o r t - s t y l e d f l o w e r ) . Seed set thus g e n e r a l l y occurs as a r e s u l t of " l e g i t i m a t e " p o l l i n a t i o n when two d i f f e r e n t f l o r a l morphs are c ros sed . As a h i g h l y s p e c i a l i z e d form of o u t c r o s s i n g (Crowe 1964; V u i l l e u m i e r 1967) , h e t e r o s t y l y would be expected to i n c r e a s e v a r i a b i l i t y w i t h i n a spec ies p o p u l a t i o n (Mosquin 1966; Ornduff 19 69) . N e v e r t h e l e s s , I a s s i g n a r e l a t i v e l y low value to h e t e r o s t y l y i n accordance w i t h observa t ions (Mulcahy and Cappore l lo 1970; Ornduff 1970b & c) tha t h e t e r o s t y l y per se i s on ly moderately e f f i c i e n t i n 166 reduc ing i l l e g i t i m a t e p o l l i n a t i o n . 1 - homostyly 3 - h e t e r o s t y l y (the on ly example i n t h i s study i s N e p h r o p h y l l i d i u m o r i s t a - g a l l i ) 8. Sexual r e p r o d u c t i o n . Reproduct ion i n h igher p l a n t s u s u a l l y has two components: s exua l and nonsexual . Sexual and nonsexual methods are combined i n a v a r i e t y of ways by p l a n t s p e c i e s , and there appears to be an i n v e r s e c o r r e l a t i o n between opposing methods ( S a l i s b u r y 1942). Ob l iga te apomixis sensu lato (both vege t a t i ve r e p r o d u c t i o n and agamospermy) i s r a re (Gustafsson 1946-47) . Intermediacy between o b l i g a t e sexua l r e p r o d u c t i o n (as i n many annuals) and o b l i g a t e apomixis i s by f a r the commonest c o n d i t i o n i n f l o w e r i n g p l an t s (Grant 1971). Th i s in te rmediacy may be viewed as a mixed s t r a t egy combining the promotion of recombina t ion v i a sexua l r e p r o d u c t i o n w i t h the pe rpe tua t ion and r a p i d propaga t ion o f favorab le gene combinations v i a nonsexual r e p r o d u c t i o n ( S a l i s b u r y 1942; Stebbins 1950, 1957a, 1958; G a d g i l and S o l b r i g 1972 ) . The g rea te r the degree of apomix i s , the l e s s the gene t i c recombinat ion w i t h i n the pure l i n e . As a c o r o l l a r y , one would expect a p o s i t i v e c o r r e l a t i o n between the degree of sexua l r ep roduc t ion and the extent of s p e c i a t i o n w i t h i n t axa (Stebbins 1957a; Baker 1959; Ornduff 1969). Such a c o r r e l a t i o n has been demonstrated by Wel l s (1969) i n c o n t r a s t i n g the s p e c i a t i o n w i t h i n c rown-sprout ing v s . o b l i g a t e l y - s e e d i n g s ec t i ons of 167 Arctostaphylos and Ceanothus i n the C a l i f o r n i a c h a p a r r a l . As an a s i d e , i t should be noted tha t h e t e r o z y g o s i t y as a r e s u l t of sporad ic o u t c r o s s i n g w i l l be preserved by apomixis i n con t r a s t to autogamy, which w i l l g r a d u a l l y r e - e s t a b l i s h homozygosity a f t e r a bu r s t of segregat ions (Grant 1958; R o l l i n s 1967; F a e g r i and van der P i j l 1971). 1 - o b l i g a t e apomixis (the on ly p o s s i b l e candidate here i s P o a c u s i c k i i ) 5 - w h o l l y sexua l r e p r o d u c t i o n ( e g . , Microsteris gracilis, S p e r g u l a r i a c a n a d e n s i s ) 9. Mode of p o l l i n a t i o n . The amount of recombina t ion r e a l i z e d per genera t ion i s a l s o a f u n c t i o n of the amount of gene d i s p e r s a l v i a both p o l l i n a t i o n and d iaspore d i s p e r s a l mechanisms. P o p u l a t i o n s t r u c t u r e s being e q u a l , r ecombina t ion due to p o l l e n d i s p e r s a l should be p r o p o r t i o n a l to the randomness of behavior and d i s t ance of p o l l e n t r anspo r t by the p o l l i n a t i o n v e c t o r . C l e a r l y , automatic s e l f - p o l l i n a t i o n or c le i s togamy represent the extreme of l e a s t p o t e n t i a l r ecombina t ion v i a p o l l i n a t i o n . At the other extreme, wind p o l l i n a t i o n or anemophily combines the bes t chances f o r longixdistaneeppollen" t r a n s p o r t v w i t h t h e l e a s t non-randomness (Whitehead 1969), a l though v i c i n i s m i n wind p o l l i n a t i o n i s marked ( C o l w e l l 1951; Whitehead 1969). B i o t i c c r o s s - p o l l i n a t i o n l i e s somewhere between these two extremes: the p o t e n t i a l f o r long d i s t ance gamete d i s p e r s a l i s o f t en tempered by nonrandom p o l l i n a t o r behavior due to s t rong 168 f lower constancy, as i n bees (Free 19 7 0b; F a e g r i and van der P i j l 1971). My rank ing of b i o t i c p o l l i n a t i o n vec tors i s somewhat a r b i t r a r y . Of these v e c t o r s , hummingbirds (see S c h l i s i n g and Turp in 19 71) and hawkmoths (Janzen 19 71b) probably have the best chances f o r long d i s t ance p o l l e n d i s p e r s a l , but hummingbirds seem to be more random, l e s s constant i n t h e i r p o l l i n a t i n g a c t i v i t i e s (Grant and Grant 1968; pe r sona l o b s e r v a t i o n s ) . Bumble ..bees , b u t t e r f l i e s and s k i p p e r s , s m a l l bees ( m e g a c h i l i d , h a l i c t i d ) , s y r p h i d and c a r r i o n f l i e s , and sma l l muscid f l i e s seem (from the l i t e r a t u r e and my own obse rva t ions ) to decrease , i n tha t o rde r , i n p o t e n t i a l f o r long d i s t ance p o l l i n a t i o n , wh i l e f lower constancy and nonrandom p o l l i n a t i n g behav ior seem to decrease from bees to b u t t e r f l i e s to f l i e s , i n genera l ( c f . , inter alia, Grant 1950; Free 1966, 1970a S b ; L e v i n and K e r s t e r 1967, 1968, 1969a £ b , 1970, 1971; Lev in 1969, 1970a; Stephen, Bohar t , and Torch io 1969; F a e g r i and van der P i j l 1971; P r o c t o r and Yeo 1973). Geitonogamy (see component 12) a l s o inc reases nonrandom mat ing . F e r t i l i z a t i o n v i a one mode of p o l l i n a t i o n does not preclude u t i l i z a t i o n o f another . Hagerup (19 50, 19 57) has demonstrated both entomo-p h i l y and anemophily i n Calluna and Arbutus, and Po ja r (1973b) has shown tha t some t y p i c a l l y anemophilous s a l t marsh species are a l s o p o l l i n a t e d by bumble bees. Moreover, many entomo-p h i l o u s f lowers are s e r v i c e d ' b y a f a i r l y wide v a r i e t y of i n s e c t s (Crosswhi te and Crosswhite 1966; Macior 1971), i n con t r a s t to the extreme coadapta t ions tha t capture the head l ines of p o l l i n a t i o n ecology l i t e r a t u r e . 169 1 - automatic s e l f - p o l l i n a t i o n ( e g . , Drosera votundifolia, S p e r g u l a r i a c a n a d e n s i s ) 2 - f a c u l t a t i v e s e l f - p o l l i n a t i o n ( e g . , Glaux maritima, S i b b a l d i a p r o c u m b e n s ) 3 - entomophi ly , p r i m a r i l y by s m a l l muscids ( e g . , P o t e n t i l l a f l a b e l l i f o l i a ) 4- - en tomophi ly , by s y r p h i d s , b u t t e r f l i e s , or sma l l bees ( e g . , V e r o n i c a c u s i c k i i , A g o s e r i s a u r a n t i a c a , P e n s t e m o n p r o c e r u s , r e s p e c t i v e l y ) 5 - p o l l i n a t i o n p r i m a r i l y by bumble bees or hawk: moths ( e g . , D e l p h i n i u m n u t a l l i a n u m or S i l e n e p a r r y i ) 6 - o r n i t h o p h i l y by hummingbirds (Castillej'a m i n i a t a ) or a combinat ion o f anemophily and entomophily (Plantago m a r i t i m a ) 7 - anemophily ( e g . , T r i g l o o h i n m a r i t i m u m ) 10. Cleis togamy v s . chasmogamy. C l e i s t o g a m i c f lowers represent the u l t i m a t e i n s e l f -p o l l i n a t i o n and s e l f - f e r t i l i z a t i o n , s ince the f lowers s e l f and set seed wi thout undergoing an thes i s (Uphof 19 38; F a e g r i and van der P i j l 1971). Ornduff (1969) has de sc r ibed the c o r r e l a t i o n s between showiness of f l o r a l charac te rs and inc idence of c r o s s -p o l l i n a t i o n , and between f l o r a l inconspicuousness and s e l f -p o l l i n a t i o n . Some species have i n d i v i d u a l s w i t h e i t h e r chasmogamous or c le is togamous f l o w e r s , as i n Lithospermum c a r o l i n i e n s e ( L e v i n 1972d); S p e r g u l a r i a c a n a d e n s i s and D r o s e r a rotundifolia o f ten bear chasmogamous and cleis togamous f lowers 170 on the same p l a n t . 1 - c le is togamy . 2 - p a r t i a l c le i s togamy ( e g . , Drosera rotundifolia, P u c o i n e l l i a p u m i l a ) 3 - inconspicuous chasmogamous f lowers ( e g . , Stellaria h u m i f u s a ) or i n f l o r e s c e n c e s ( e g . , H i e r a c i u m g r a c i l e ) 4 - conspicuous f lowers or i n f l o r e s c e n c e s 11. C o m p a t i b i l i t y . I n c o m p a t i b i l i t y mechanisms, though seldom complete and of ten s u s c e p t i b l e to temporary breakdown (Lewis 19 54; Grant 1958; Crowe 1964; Baker 1966b), s t r o n g l y favor o u t c r o s s i n g (East 1940; Bateman 1952; F r y x e l l 1957; Mosquin 1966). 1 - f u l l y s e l f - c o m p a t i b l e ( e g . , G l a u x m a r i t i m a , S o i r p u s c e r n u u s ) 3 - moderately s e l f - c o m p a t i b l e ( e g . , Kalmia p o l i f o l i a ) 5 - moderately s e l f - i n c o m p a t i b l e ( e g . , Potentilla pacifica) 7- - predominant ly s e l f - incompatible-,--(-eg. , Festuca rubra, E r i g e r o n p e r e g r i n u s ) 12. Chances of geitonogamy. P o l l i n a t i o n between two f lowers on the same p l a n t i s c a l l e d geitonogamy. G e n e t i c a l l y , geitonogamy i s equ iva l en t to autogamy, or p o l l i n a t i o n w i t h i n one f lower ( F a e g r i and van der P i j l 1971). Geitonogamy i s p o s s i b l e on ly i f the spec ies has more than one f lower per p l a n t , and i f i t i s s e l f - c o m p a t i b l e . 171 Chances of geitonogamy w i l l be heightened i f the p l an t bears numerous, c l o s e l y spaced, more or l e s s s imul taneous ly blooming f lowers i n the i n f l o r e s c e n c e , s ince p o l l i n a t o r s , e s p e c i a l l y Hymenoptera, tend to v i s i t many f lowers of the same p l a n t before moving on to the next p l a n t (Free 197Oa; :.Levin 1970a). 1 - chances of geitonogamy h i g h ( e g . , Valeriana sitohensis) 3 - chances of geitonogamy n i l ( e g . , Anemone o o o i d e n t a l i s 3 T r i e n t a l i s a r o t i o a ) 13. D i s p e r s i b i l i t y . " In terms of i t s gene t i c r e s u l t s , the d i s p e r s a l o f one seed i s p o t e n t i a l l y e q u i v a l e n t to the d i s p e r s a l to a s i m i l a r d i s t ance o f thousands o f p o l l e n g r a i n s " (Grant 1958). Good d iaspore d i s p e r s a l mechanisms can compensate f o r poor p o l l e n d i s p e r s a l . Long d i s t ance d i s p e r s a l i s e s p e c i a l l y important i n m a i n t a i n i n g v a r i a b i l i t y i n spec ies whose popu la t ions are r e l a t i v e l y s m a l l , w i d e l y spaced, and not components o f a major, more or? ' less continuous vege t a t i on cover , as i s the case fo r mos t fo f r the ; spec i e s i n t h i s s tudy. 1 - low d i s p e r s i b i l i t y ( e g . , C a r e x o b n u p t a ) 5 - h i g h d i s p e r s i b i l i t y ( e g . , Kalmia p o l i f o l i a ) 14. P o p u l a t i o n s i z e and s t r u c t u r e . Simply as a matter of p r o b a b i l i t y , l a rge popu la t ions w i l l have more gene t i c v a r i a b i l i t y than sma l l p o p u l a t i o n s . An e x t e n s i v e , continuous p o p u l a t i o n w i l l p robably have more 172 b io types and more o u t c r o s s i n g between these b io types than a s m a l l , l o c a l p o p u l a t i o n , g iven comparable breeding systems. The D/d values tha t have been c a l c u l a t e d f o r each species (Sec t i on I I I - A ) are u s e f u l here to es t imate the p o p u l a t i o n s t r u c t u r e w i t h i n the communities, s ince the l a r g e r the value of D / d , the more clumped the p o p u l a t i o n s t r u c t u r e . 1 - p o p u l a t i o n of s m a l l s i z e , clumped s t r u c t u r e ( e g . , E l y m u s g l a u c u s 3 L i l a e o p s i s o c c i d e n t a l - i s 3 Coptis a s p l e n i f o l i a ) 2 - s m a l l , r e g u l a r (eg. , Poa cusickii) or moderate, clumped ( e g . , T h a l i c t r u m o c c i d e n t a l e ) 3 - moderate, r e g u l a r ( e g . , A g o s e v i s a u r a n t i a c a , P h l e u m a l p i n u m ) 4 - l a r g e , clumped ( e g . , Valeriana sitchensis) 5 - l a r g e , r e g u l a r ( e g . , F e s t u c a v i r i d u l a , T r i g l o c h i n m a r i t i m u m ) 15. E c o t y p i c v a r i a t i o n . D i s c o n t i n u o u s , h a b i t a t - c o r r e l a t e d , h e r e d i t a b l e v a r i a t i o n w i l l i nc rease the p o t e n t i a l recombina t ion and adapt ive v e r s a t i l i t y of a spec ies i f gene f low between the l o c a l v a r i a n t s occurs o f ten enough to ma in ta in s p e c i f i c coherence but not f r equen t ly enough to swamp the v a r i a n t s (Clausen 19 53; Clausen and Hiesey 1958). E c o t y p i c v a r i a t i o n depends a great dea l on e c o l o g i c a l d i s c o n t i n u i t i e s between ecotypes ; c l i n a l v a r i a t i o n w i l l r e s u l t from ranges r e s t r i c t e d to a p a r t i c u l a r k i n d of h a b i t a t , as i n Plantago maritima w i t h i n the s a l t marsh h a b i t a t (Gregor 1946) , or from a broad range continuous a long environmenta l g r a d i e n t s , as i n Betula glandulosa. I t i s probably safe to p r e d i c t e c o t y p i c v a r i a t i o n i n any wide- rang ing spec ies w i t h a wide e c o l o g i c a l ampl i tude , e s p e c i a l l y i f t ha t spec ies occupies a range of d i s c r e t e h a b i t a t s ( c f . C lausen , Keck, and Hiesey 1941; M c M i l l a n 1959; Mooney and B i l l i n g s 1961; H e s l o p - H a r r i s o n 1964; McNaughton 1966; Bradshaw 1972). 1 - apparent ly no e c o t y p i c v a r i a t i o n ( e g . , Plantago m a o r o o a r p a , V a o o i n i u m s o o p a r i u m ) 3 - moderate e c o t y p i c v a r i a t i o n ( e g . , Junous baltious, E r y t h r o n i u m g r a n d i f l o r u m ) 5 - marked e c o t y p i c v a r i a t i o n ( e g . , Achillea millefolium, D e s o h a m p s i a o e s p i t o s a ) 16. C r o s s a b i l i t y b a r r i e r s and e x t e r n a l i s o l a t i n g mechanisms. An important b a r r i e r to gene recombinat ion i s i n t e r s p e c i f i h y b r i d s t e r i l i t y , whether gen ie , chromosomal, mechan ica l , or e t h o l o g i c a l (Grant 1963). I n t e r f e r t i l i t y between r e l a t e d spec ie can augment the recombinat ion tha t takes p lace w i t h i n a s e l f -i n c o m p a t i b l e , o u t c r o s s i n g species (Anderson and Stebbins 19 54; Stebbins 19 59, 19 69) . H y b r i d i z a t i o n can a l s o compensate f o r the l o s s of r ecombina t iona l p o t e n t i a l due to predominant s e l f -f e r t i l i z a t i o n , as i n Elymus glaucus (Snyder 1950, 1951; Stebbins 1957b; Grant 1971) or Hordeum brachyantherum ( M i t c h e l l and W i l t o n 1964). In c o n t r a s t , Grant (1958, 1971) has po in ted out tha t i n many inb reed ing spec ies recombinat ion i s f u r t h e r r e s t r i c t e d by h y b r i d s t e r i l i t y , as i s l i k e l y ' 174 the case w i t h Spergularia canadensis (see R a t t e r 1965). 1 - r ep roduc t ive i s o l a t i o n (eg. , Silene -parryi (Kruckeberg 1955, 1961)) . 3 - o c c a s i o n a l h y b r i d i z a t i o n ( e g . , Erigeron peregrinus , probably) 5 - frequent h y b r i d i z a t i o n ( e g . , Hordeum brachy an the rum) The l i m i t s of the index ( I . P . R . ) w i t h n = 10 as :a h y p o t h e t i c a l b a s i c chromosome number a re : 18.5 - 7 8 .0 . The r e s u l t s of the a n a l y s i s of recombina t ion systems are summarized f o r each spec ies i n Table 19. Table 20 l i s t s the unweighted and weighted average I . P . R . ' s fo r each community; the l a t t e r means take i n t o account the importance va lue of each spec ies and thus i n d i c a t e the mean I . P . R . of the community v e g e t a t i o n , whereas the unweighted mean I . P . R . i s an average of the community f l o r a . Species of the s a l t marsh have, on the average, the lowest values of I . P . R . Those of the two sphagnum bogs have in te rmed ia te v a l u e s , and suba lp ine meadow spec ies have the h ighes t average I . P . R . However, i n no case i s the d i f f e r e n c e between any o f the means s t a t i s t i c a l l y s i g n i f i c a n t ( t - t e s t , P >>0.05). There are some other i n t e r e s t i n g o b s e r v a t i o n s . Species tha t appear to be predominant ly autogamous have an average I . P . R . of 4 0 . 3 , compared w i t h an average fo r a l l spec ies of 47 .0 . The inbreeders thus have more r e s t r i c t e d recombina t ion systems than the ou tbreeders , a cco rd ing to t h i s a n a l y s i s . Autogamous s p e c i e s , because of t h e i r r e s t r i c t e d recombina t ion 175 TABLE 19. Index of P o t e n t i a l Recombination ( I . P . R . ) . f e n e r a t i o n l eng th . . 2 B a s i c chromosome number/2. 3 R e l a t i v e chromo-some l e n g t h . ' 'Leve l of p l o i d y . 5Dichogamy. 6 S p a t i a l s epa ra t i on of s exua l organs. 7 H e t e r o s t y l y . 8 S e x u a l r e p r o d u c t i o n . 9Mode o f p o l l i n a t i o n . 1 0 C l e i s t o g a m y . 1 f o m p a t i b l i t y . 1 2 Gei tonogamy. 1 3 D i s p e r s i b i l i t y . 1 ^ P o p u l a t i o n s i z e and s t r u c t u r e . 1 5 E c o t y p i c v a r i a t i o n . 1 6 H y b r i d i z a t i o n . 0 • a Species I 2 3 5 6 - . • - - -• •. • - S a l t Marsh Des champ si d~ cesp it os.d 2 3.5 6 3 2 2 F e s t u c a r u b r a 2 3.5 6 2 2 2 T r i g l o c h i n - m a r i t i m u m 2 3 3 1 3 1 S a l i c o r n i a virgih'icd 2 4.5 4 3 3 1 P l a n t a g o m a r i t i m a 2 3 5 5 2 . 5 2 J u n c u s b a l t i c u s 2 5 1 1 3 2 C a r e x lyngbyei 2 5 1 1 3 3 G l a u x m a r i t i m a 2 7 . 5 3 5 1 1 P o t e n t i l l a p a c i f i c a 2 3.5 4 3 2 1.5 A g r o s t i s e x a r a t a 2 3.5 6 3 1.5 1.5 S t e l l a r i a h u m i f u s a 2.5 6 . 5 4 5 1.5 1.5 T r i f o l i u m w o r m s k j o l d i i 2 4 3 3 3 1.5 S c i r p u s c e r n u u s 3.5 5 2 2 2.5 1 P u c c i n e l l i a p u m i l a 2.5 3.5 5 2 1 1 S p e r g u l a r i a c a n a d e n s i s 4 4.5 3 3 1 1 D i s t i c h l i s s p i c a t a 2 2.5 3 1 3 5 H o r d e u m b r a c h y a n t h e r u m 2 3.5 5 3 1 1 L i l a e o p s i s o c c i d e n t a l i s 2 5.5 4 3 1 1 Wade * s Bog C a r e x p l u r i f l o r a 2 5 1 3 3 3 Apargidium'' b o r e a l e 2 4.5 5 5 3 1.5 A g r o s t i s a e q u i v a l v i s 2 3.5 5 5 1.5 1 C a r e x o b n u p t a 2 5 1 1.5 3 3 S a n g u i s o r b a o f f i c i n a l i s 2 3.5 4 3 1 1 K a l m i a p o l i f o l i a 1 6 3 5 1.5 2 V a c c i n i u m oxy c o c c u s 1.5 6 2 3 1.5 1.5 C a r e x c a n e s c e n s 2 5 1 2 3 3 D r o s e r a r o t u n d i f o l i a 3 5 3 5 1 1 Ledum g r o e n l a n d i c u m 1 6.5 3 5 1.5 2 T r i e n t a l i s a r c t i c a 2.5 11 1 1 1 2 E m p e t r u m n i g r u m 1 6 . 5 3 5 3 5 M y r i c a g a l e 1 4 2 1 3 5 T o f i e l d i a g l u t i n o s a 2 7.5 4 5 1.5 2 G e n t i a n a d o u g l a s i a n a 4 6.5 5 5 2 1.5 L i n n a e a b o r e a l i s 1.5 4 3 3 1.5 1 TABLE 19. (Continued) 176 1 6 7 8 9 10 1 1 1 2 13 Ik 15 16 E=IPR-1 S a l t Marsh :•.. ~? 5 -~ a -s6 • . -P3 7 3 3 4 5 3 58.5 r.. • -. 2;5 6 3 7 3 2 3 4 2 51.0 I 3.5 . 7 3 2 2 3 5 2 1 42. 5 I 4 6 3 2 2 3 4 1.5 1 45.0 l 5 6 3 1 2 3 4 2 1 47.5 I 2 6 3 1 2 4 3 3 3 42.0 I 2.5 7 3 1 2 2 3 1.5 2 40. 0 l 3 2.5 3 1 2 3 2 3 1 41.0 i 3 4 4 5 2.5 2 2 3 2 44 . 5 l 3 6 3 7 3 3 2 4 2 51.5 l 3 3 3 1 2 3 3 2 1 42.0 i 3 5 4 7 3 2 2 4 1 48. 5 I 5 4 2 . 5 1 2 2 3 3 1 40 . 5 l 5 3 2 2 2 2 2 2 2 38 . 0 I 5 1 1.5 1 2 4 1 2 1 36.0 I 2 7 3 7 3 2 1 2 1 45 . 5 I 3.5 3.5 2 1 2 2 1 4 5 40 . 5 I 3 3 3 1 2 2 1 2 1 35.5 range: 35.5_- 58.5 unweighted x = 4 3.8 weighted x = 47.2 Wade's Bog 1 2.5 7 3 1 2 2 4 1 3 43. 5 1 5 4 4 7 3 5 5 2 1 58.0 1 4 7 3 3 2 3 5 1 2 49. 0 1 2.5 7 3 1 2 2 4 1 2 41. 0 1 4.5 4 3.5 2 1 3.5 5 3;5 4 46 . 5 1 4 5 4 3 2 5 3 4 2 51.5 1 2.5 5 4 2 2 4 3 2.5 3 44. 5 1 3.5 7 3 1 2 2 3 3 2 43.5 1 5 1.5 2 1 2.5 4 5 2 4 43.5 1 . 5 5 4 2 1 5 4 3 3 52.0 1 3 3 4 7 3 2 5 2 2.5 51. 0 1 5 7 3 7 3 4 3 4 1 61. 5 1 5 7 3 7 3 3.5 2 3.5 1 52.0 1 4 4 4 2 1 4 4 4 1 51. 0 1 5 5 4 2 1.5 3 4 1 1 51.5 1 2.5 4.5 4 7 3 4 2 3.5 1 46.5 177 TABLE 19 (cont inued) Species 1 2 3 4 5 6 Wade's Bog (cont inued) M a i a n t h e m u m d i l a t a t u m 2 4. 5 7 3 2 2 R h y n c h o s p o r a a l b a 2 6.5 1 5 3 1 V a o o i n i u m v i t i s - i d a e a 1.5 6 2 5 1 1 S o i v p u s o e s p i t o s u s 2 5 1 1 3 1 J u n o u s s u p i n i f o r m i s 2 5 1 1 3 1. 5 V a c c i n i u m u l i g i n o s u m 1 6 2 3 1 1 G a u l t h e r i a s h a l l o n 1 5 . 5 2 1 1. 5 1 G e n t i a n a s c e p t r u m 2 6.5 6 5 3 2 C o p t i s a s p l e n i f o l i a 2 4.5 3 5 2 1.5 Ogg' 1 s Bog M y r i c a g a l e 1 4 2 1 3 5 A p a r g i d i u m b o r e a l e 2 4.5 5 5 3 1.5 C a r e x o b n u p t a 2 5 1 1.5 3 3 C a r e x p l u r i f l o r a 2 5 1 3 3 3 A g r o s t i s a e q u i v a l v i s 2 3.5 5 5 1.5 1 S a n g u i s o r b a o f f i c i n a l i s 2 3.5 4 3 1 1 Ledum g r o e n l a n d i c u m 1 6.5 3 5 1.5 2 V a c c i n i u m oxy c o c c u s 1.5 6 2 3 1.5 1.5 D r o s e r a r o t u n d i f o l i a 3 5 3 5 1 1 K a l m i a p o l i f o l i a 1 6 3 5 1.5 2 E m p e t r u m n i g r u m 1 6.5 3 5 3 5 T r i e n t a l i s a r c t i c a 2 . 5 11 1 1 1 2 C a r e x c a n e s c e n s 2 5 1 2 3 3 T o f i e l d i a g l u t i n o s a 2 7 . 5 4 5 1.5 2 L i n n a e a b o r e a l i s 1.5 4 3 3 1.5 1 R h y n a h o s p o r a a l b a 2 6.5 1 5 3 1 P l a n t a g o m a c r o c a r p a 2 3 5 3 3 2 G a u l t h e r i a s h a l l o n 1 5.5 2 1 1.5 1 G e n t i a n a s c e p t r u m 2 6.5 6 5 3 2 C a l a m a g r o s t i s n u t k a e n s i s 2 3.5 6 3 2 2 M a i a n t h e m u m d i l a t a t u m 2 4.5 7 3 2 2 S c i r p u s c e s p i t o s u s 2 5 1 1 3 1 C o p t i s a s p l e n i f o l i a 2 4.5 3 5 2 1.5 C o p t i s t r i f o l i a 2 4.5 3 5 2 1. 5 J u n c u s s u p i n i f o r m i s 2 5 1 1 3 1.5 TABLE 19. (Continued) 178 1 o I I 1 2 1 3 1 it 1 5 1 6 1 6 S = IPR l Wade's Bog (continued) 1 3 3.5 4 7 3 4 1 3 1 51.0 1 3 7 3 1 2 2 2 2 1 42.5 1 2.5 5 4 2 2 4 2 3 1 43 . 0 1 4.5 7 3 1 1.5 2 2 3.5 1 39. 5 1 2 7 3 1 2 4 1 1 2 37.5 1 5 5 4 2 2 4 1 4 2 44. 0 1 5 5 4 1 1 4 1 2 1 37.0 1 5 5 4 2 2 4 3 1 1 52.5 1 3 3 3.5 3 1.5 2.5 1 2 1 39 . 5 range : 36. 0 - 61.5 unweighted x = 47. 0 weighted x = 48 . 5 Ogg ' s Bog 1 5 7 3 7 3 3.5 4 3.5 1 54.0 1 5 4 4 7 3 5 5 2 1 58 . 0 1 2 . 5 7 3 1 2 2 4 1 2 41. 0 1 2.5 7 3 1 2 2 4 1 3 43.5 1 4 7 3 3 2 3 5 1 2 49. 0 1 4.5 4 3.5 2 1 3.5 5 3.5 4 46.5 1 5 5 4 2 1 5 4 3 3 52.0 1 2.5 5 4 2 2 4 3 2.5 3 44. 5 1 5 1.5 2 1 2.5 4 5 2 4 43 . 5 1 4 5 4 3 2 5 3 4 2 51.5 1 5 7 3 7 3 4 3 4 1 61. 5 1 3 3 4 7 3 2 4 2 2.5 50 . 0 1 3.5 7 3 1 2 2 3 3 2 43. 5 1 4 4 4 2 1 4 3 4 1 50.0 1 2.5 4.5 4 7 3 4 3 3 . 5 1 47.5 1 3 7 3 1 2 2 2 2 1 42.5 1 5 7 3 1 2 3.5 3 1 1 45.5 1 5 5 4 1 1 4 2 2 1 38.0 1 5 5 4 2 2 4 3 1 1 52.5 1 4 7 3 7 3 2.5 2 2 2 52.0 1 3 3 . 5 4 7 3 4 2 3 1 52.0 1 4.5 7 3 1 1.5 2 2 3.5 1 39 . 5 1 3 3. 3.5 3 1.5 2.5 2 2 1 40.5 1 3 3 4 3 2.5 2 2 3 1 42.5 1 2 7 3 1 2 4 2 1 2 37.5 TABLE 19. (cont inued) 179 Species 1 2 3 5 6 Ogg's Bog (continued) D e s c h a m p s i a ce s p i t o s a 2 3.5 6 3 2 2 G e n t i a n a d o u g l a s i a n a 4 6.5 5 5 2 1.5 V a c c i n i u m o v a t u m 1 6 2 5 1 1 V a c c i n i u m v i t i s - i d a e a 1.5 6 2 5 1 1 C o r n u s u n a l a s c h k e n s i s 1.5 5.5 3 3 1.5 1.5 V a c c i n i u m u l i g i n o s u m 1 6 2 3 1 1 E e p h r o p h y l l i d i u m c r i s t a - g a H i 2 8.5 1 2 2 2 E r i o p h o r u m p o l y s t a c h i o n 2 5 2 2 3 3 C a r e x p a u c i f l o r a 2 5 1 1.5 2 3 B l a c k w a l l Meadow V a l e r i a n a s i t c h e n s i s 2 4 2 1 2 2 F e s t u c a v i r i d u l a 2 3 . 5 6 3 1.5 1.5 L u p i n u s l a t i f o l i u s 2 6 1 1 1 1 E r i g e r o n p e r e g r i n u s 2 4.5 4 5 3 1.5 Anemone o c c i d e n t a l i s 2 4 4 5 2 2 P o t e n t i l l a f l a b e l l i f o l i a 2 3 . 5 2 3 2 1.5 E r y t h r o n i u m g r a n d i f l o r u m 3 6 7 5 1 1.5 V a c c i n i u m s c o p a r i u m 1 6 2 5 1 1 C l a y t o n i a l a n c e o l a t a 3 4 6 5 2 2 A r e n a r i a c a p i l l a r i s 2 5.5 4 5 2 2 A n t e n n a r i a l a n a t a 2 3.5" 5 3 3 5 V e r o n i c a c u s i c k i i 2 4.5 2 1 2 2 A g o s e r i s a u r a n t i a c a 2 4.5 4 3 3 1 P h l e u m a l p i n u m 2 3.5 5 3 2 2 A r n i c a l a t i f o l i a 2 5 4 3 3 1.5 L u z u l a h i t c h c o c k i i 2 3 3 3 3 2 T h a l i c t r u m o c c i d e n t a l e 2 3.5 2 1 3 4 A c h i l l e a m i l l e f o l i u m 2 4.5 4 2 3 1.5 T r i s e t u m s p i c a t u m 2 3 . 5 5 3 2 2 C a r e x r o s s i i 2 5 1 2 2 3 E l y m u s g l a u c u s 2 3.5 7 3 1 1 S i l e n e p a r r y i 2 6 5 3 3 2 A r n i c a m o l l i s 2 5 4 1 3 1. 5 P o a e p i l i s 2 3.5 3 3 3 5 S e n e c i o i n t e g e r r i m u s 2 5 5 3 3 1.5 180 TABLE 19. (cont inued) 1 6 7 8 9 1 0 I I 1 2 1 3 l >t 1 5 1 6 Z = IPR l Ogg's Bog (cont inued) 1 5 6 3 7 3 2 . 5 1 5 3 55.0 1 5 5 4 2 1.5 3 1 1 1 49. 5 1 5 5 4 2 1 4 2 1 1 41. 0 1 2.5 5 4 2 2 4 2 3 1 43.0 1 2.5 4 4 7 3 4 1 2.5 3 48.0 1 5 5 4 2 2 4 1 4 2 44.0 3 3.5' 3.5 4 2 2 2 1 2 1 41. 5 1 2 7 3 1 2 5 1 2 3 44. 0 1 3 7 3 1 2 3 1 2 1 . 38.5 range: 37.0 _ 61.5 unweight ed x = 46.6 weij jhted x = 49 . 8 B l a c k w a l l Meadow 1 4 4 4 2 1 5 4 3 2 43. 0 1 5 7 3 3 2 2 5 1 3 49 . 5 1 5 5 4 7 3 3 5 4 5 54. 0 1 4 4 4 7 3 5 5 4 3 60.0 1 5 3 4 2 3 5 5 2 1 50.0 1 4 4 4 6 2 2 5 1 2 45. 0 1 5 5 4 2 3 2 5 3 2 55 . 5 1 5 5 4 3 2 4 4 1 1 46.0 1 5 4 4 2 2.5 2 5 5 1 53.5 1 5 4 4 7 3 4 4 4 4 60.5 1 4 4 3 7 3 5 4 1 3 56.5 1 4 4 4 3 2 3 4 2 1 41. 5 1 5 4 4 3 5 3 3 1 5 3 . 5 1 4 7 3 1 1 4 3 5 2 48.5 1 4 4 4 7 3 5 2 4 3 55.5 1 2 7 3 6 2 2 2 1 1 43.0 1 3 7 3 5 3 2 1 3 2 45.5 1 4 4 4 7 3 5 2 5 4 56.0 1 5 7 3 7 3 4 2 5 3 57. 5 1 5 7 3 1 2 2 2 3 2 43.0 1 5 3 2 1 2 2 1 3 5 42.5 1 5 6 4 2 2 3 2 1 1 48 . 0 1 4 4 4 7 3 5 2 2 3 51.5 1 1 7 3 1 3 2 1 2 4 44. 5 1 5 4 4 7 3 5 2 3.5 2 56.0 TABLE 19. (Continued) 181 Species B l a c k w a l l Meadow (cont inued) H i e r a o i u m g r a c i l e 2 4.5 5 5 3 1 L u z u l a s p i a a t a 2 3 2 3 3 2 Sedum l a n c e o l a t u m 2 4 4 5 1 2 C a s t i l l e j a m i n i a t a 2 6 3 5 1 2 P e n s t e m o n p r o c e r u s 1.5 4 3 5 2 1 P e d i o u l a r i s b r a c t e o s a 2 4 4 . 5 1 2 P h l o x d i f f u s a 1.5 3. 5 4 5 1 1 P o t e n t i l l a d i v e r s i f o l i a 2 3.5 2 1 2 1.5 C a r e x s p e c t a b i l i s 2 5 2 1 3 3 E p i l o b i u m a l p i n u m 2 4.5 2 3 1 1 D e l p h i n i u m n u t t a l l i a n u m 2 4 4 3 2.5 1 C a s t i l l e j a p a r v i f l o r a 2 6 3 5 1 2 R a n u n c u l u s e s c h s c h o l t z i i 2 4 5 3 2 1.5 S i b b a l d i a p r o c u m b e n s 2 3.5 2 5 1 1. 5 M i c r o s t e r i s g r a c i l i s 4 4 4 5 1 1 J u n o u s d r u m m o n d i i 2 5 1 1 2. 5 2 E y d r o p h y l l u m f e n d l e r i 2 4.5 4 3 2 2 S e n e c i o t r i a n g u l a r i s 2 5 6 3 3 1. 5 V a c c i n i u m d e l i c i o s u m 1 6 2 3 1 1 TABLE 19. (Concluded) 182 1 o I l 1 2 1 3 1 "t 1 5 1 6 1 6 Z = I P R l 1 4 4 3 7 3 5 1 4 3 55.5 1 5 7 3 1 2 2 2 3 1 42. 0 1 4 5 4 7 3 4 1 3 3 53.0 1 5 6 4 7 3 5 2 4 4 60 . 0 1 4 4 4 2 1 4 1 2 3 42. 5 1 5 5 4 7 3 3 2 3 . 5 1 52.5 1 5 5 4 7 3 2 1 3 1 48.0 1 5 4 4 5 2 2 1 3.5 4 43.5 1 3 7 3 1 2 1 1 3 3 40 . 0 1 3 2.5 3 1 2.5 5 1 4 3 39 . 5 1 5 5 4 3 2.5 4 1 3 4 49 . 0 1 5 5 4 7 3 5 2 3 3 •57.0 1 5 3 4 2 2 2 1 4 2 43.5 1 3 2 3 2 2 2 1 3 1 35. 0 1 4 2.5 3.5 1 2.5 4 1 3 1 43.5 1 4 7 3 1 2-..5 4 1 2.5 1 40.5 1 4 5 4 3 '2 2 1 2 1 42. 5 1 5 4 4 7 3 5 1 3 . 5 1 55.0 1 5 5 4 3 2 4 1 1 1 41. 0 range: 3 5.0_- 6 0.5 unweighted x = 48.6 weighted x = 50.6 'Arranged i n order of dec reas ing importance v a l u e . 183 systems, might be expected to have l e s s v a r i a b l e popu la t ions than comparable o u t c r o s s i n g spec ies (Stebbins 1957a; Grant 1958). However, a l a rge body of recent evidence suggests tha t some inb reed ing spec ies have mainta ined a h i g h l e v e l o f p o p u l a t i o n v a r i a b i l i t y presumably through o c c a s i o n a l o u t c r o s s i n g between s t r o n g l y homozygous b io types ( A l l a r d 1965; Kannenberg and A l l a r d 1967; J a i n and M a r s h a l l 1967; R o l l i n s 1967; A l l a r d , J a i n and Workman 1968; J a i n 1969; Kondo 1972, inter alia). Species of Cyperaceae, Gramineae, Juncaceae, and L i l i a c e a e have average I . P . R . ' s of 41 .4 , 4 8 . 3 , 4 0 . 2 , and 5 2 . 5 , r e s p e c t i v e l y . Average I . P . R . ' s fo r r e p r e s e n t a t i v e s of some common nor th temperate d ico ty ledonous f a m i l i e s a re : Caryo-phy l l aceae ( 4 5 . 4 ) ; Compositae ( 5 5 . 1 ) ; E r i c a c e a e , i n c l u d i n g Empetrum nigrum ( 4 6 . 2 ) ; Ranunculaceae ( 4 5 . 1 ) ; Rosaceae ( 4 2 . 9 ) ; Sc rophula r iaceae ( 5 0 . 7 ) . The phy logene t i c s i g n i f i c a n c e o f these f i g u r e s w i l l not be specula ted on. TABLE 20. Average community I . P . R . ' s . Community x , unweighted x , weighted 1 S a l t Marsh Wade's Bog Ogg's Bog B l a c k w a l l Meadow 43.8 47.0 46 . 6 48.6 47.2 48.5 49.8 50.6 Weighted by m u l t i p l y i n g the unweighted I . P . R . f o r each species by i t s corresponding I . V . and d i v i d i n g the community sum o f these products by the average I . V . fo r tha t community. 184 The most s t r i k i n g g e n e r a l i z a t i o n tha t emerges from t h i s a n a l y s i s i s tha t the d i f f e r e n t f a c t o r s i n a s p e c i e s ' recombina t ion system f r equen t ly work i n o p p o s i t i o n to one another but a r r i v e at an e v o l u t i o n a r y compromise between f i t n e s s and f l e x i b i l i t y . This compromise i s u s u a l l y d i f f e r e n t f o r d i f f e r e n t species and tends to be c o r r e l a t e d w i t h the s p e c i e s ' e c o l o g i c a l s t r a t egy and the type o f vege t a t i on of which i t i s a c o n s t i t u e n t . Some examples of the i n t e r p l a y o f opposing f a c t o r s are g iven i n Table 21. The s i t u a t i o n i n d i f f e r e n t species i s i n s t r u c t i v e . For example, the e r icaceous shrub Kalmia polifolia has a long genera t ion t ime , moderate vege ta t ive r ep roduc t ion v i a shor t rhizomes and t i l l e r i n g , and i s p a r t i a l l y s e l f - c o m p a t i b l e ; but i t i s d i p l o i d , has a h igh b a s i c chromosome number, showy f lowers tha t are h i g h l y ou tc ros sed , and minute , l i g h t seeds w i t h good d i s p e r s i b i l i t y . Spergularia canadensis , though autogamous (most o f i t s f lowers are c le is togamous) and a t e t r a p l o i d w i t h f a i r l y s m a l l chromosomes and clumped p o p u l a t i o n s , i s an annual tha t u s u a l l y has a few chasmogamous f lowers on each p l a n t , and has s m a l l , g l andu la r -pubescen t , s l i g h t l y -winged seeds and l a rge p o p u l a t i o n s . Even Poa cusickii v a r . epilis , though i t appears to reproduce p r i m a r i l y by agamospermy, has l a rge chromosomes and i s d ioec ious and wind-p o l l i n a t e d , so tha t whenever t h i s Poa happens to reproduce s e x u a l l y , i t i s l i k e l y to r e l ea se a l a rge amount o f r ecombina t iona l v a r i a b i l i t y (Clausen 1954, 1961). 185 TABLE. 21. Combinations of opposing r e g u l a t o r y f a c t o r s . Fac tors promoting v s . f a c t o r s r e s t r i c t i n g recombinat ion Examples shor t gene ra t ions , good seed d i s -p e r s a l , l a rge popu la t ions v s . autogamy, clumped popu la t ions d ioecy or s t rong dichogamy, anemo-p h i l y v s . h igh p o l y p l o i d y , s m a l l chromosomes l a rge chromosomes, s e l f - i n c o m p a t i -b i l i t y , o u t c r o s s i n g vs.. p o l y p l o i d y , vege t a t i ve r ep roduc t ion Spergularia canadensis, M i c r o s t e r i s g r a c i l i s T r i g l o c h i n maritimum, Juncus b a l t i c u s , Myrica gale, Thalictrum occiden-t a l e many Gramineae and Compositae showy f l o w e r s , s e l f - i n c o m p a t i b i l i t y , Lupinus l a t i f o l i u s , Arnica h igh b a s i c numbers, f r e q u e n t ' i n t e r -s p e c i f i c h y b r i d i z a t i o n , e c o t y p i c d i f f e r e n t i a t i o n v s . p o l y p l o i d y , sma l l chromosomes d i p l o i d y , h i g h b a s i c chromosome number v s . s e l f - c o m p a t i b i l i t y r e l a t i v e l y inconspicuous f lowers ' h igh b a s i c number, s e l f - i n c o m p a t i -b i l i t y v s . h i g h p o l y p l o i d y , s m a l l chromosomes h i g h b a s i c number v s . long genera t ion time l a rge chromosomes, anemophily, frequent h y b r i d i z a t i o n v s . p o l y p l o i d y , i nb reed ing d i o e c y , wind p o l l i n a t i o n v s . low b a s i c numbers, p o l y p l o i d y , ex tens ive vege ta t ive r ep roduc t ion mon^eey,, ^ dieta^gagrjf,;; wind; - p p l l i r t : ^nafiLOBi HPS . . . s p a l l ' Ghrompsome^Sr, good d i s p e r s a l , h y b r i d i z a t i o n v s . autogamy, p o l y p l o i d y , sma l l chromosomes l a t i f o l i a , Arnica mollis Glaux maritima, S t e l l a r i a humifusa, T o f i e l d i a g l u t i -nosa, Drosera r o t u n d i f o l i a T r i e n t a l i s a r c t i c a , Lupinus l a t i f o l i u s E r i c a c e a e , Empetrum nigrum Elymus glaucus, Hordeum brachy an the rum D i s t i c h l i s spicata Carex lyngbyei, C. obnupta, C. p l u r i f l o r a Epilobium alpinum TABLE 21. (Continued) 186 Fac tors promoting v s . f a c to r s r e s t r i c t i n g recombinat ion , Examples l a rge chromosomes, d i p l o i d y , dichogamy, anemophily v s . low b a s i c number, s e l f -c o m p a t i b i l i t y good d i s p e r s a l , h y b r i d i z a t i o n v s . autogamy, p o l y p l o i d y , s m a l l chromosomes showy f l o w e r s , w e l l - d e v e l o p e d entomophi ly , good d i s p e r s a l v s . s e l f - c o m p a t i b i l i t y l a rge chromosomes, showy, out -crossed f l o w e r s , e c o t y p i c d i f f e r e n t i a t i o n v s . s e l f - c o m p a t i -b i l i t y , poor d i s p e r s a l P l a n t a g o m a r i t i m a E p i l o b i u m a l p i n u m V a l e r i a n a s i t o h e n s i s 3 D e l p h i n i u m n u t t a l l i a n u m , Er icaceae C l a y t o n i a l a n c e o l a t a , E r y t h r o n i u m g r a n d i f l o r u m l a rge chromosomes, d i p l o i d y , showy, Gentiana d o u g l a s i a n a 3 entomophilous f l o w e r s , good \G. soeptrum, Anemone d i s p e r s a l v s . s e l f - c o m p a t i b i l i t y , ocoidentalis no h y b r i d i z a t i o n , l i t t l e or no e c o t y p i c d i f f e r e n t i a t i o n In summary, t h i s a n a l y s i s has shown tha t there are d i f f e r ences i n the recombinat ion p o t e n t i a l s of d i f f e r e n t spec ies but tha t these d i f f e r e n c e s are apparent ly not g rea t . The g e n e r a l i z a t i o n tha t autogamous species have more r e s t r i c t e d recombina t ion systems than comparable xenogamous or o u t c r o s s i n g spec ies seems v a l i d . However, spec ies w i t h r e s t r i c t e d recombi -n a t i o n p o t e n t i a l do not dominate the vege t a t i on of any o f the study communit ies; indeed , they are u s u a l l y very minor elements ( c f . Tables 3, 4 , 5, 6 w i t h Table Table 19) . Furthermore, no 187 s i g n i f i c a n t d i f f e r e n c e was found between l e v e l s of p o t e n t i a l recombinat ion w i t h i n any of the communities. This f i n d i n g i s at odds w i t h Mosquin 's (1966) t h e s i s tha t species of harsh p h y s i c a l environments have r ep roduc t i ve s p e c i a l i z a t i o n s fo r reduc ing gene t i c v a r i a b i l i t y ; i . e . , c l o sed recombina t ion systems. Of course , i t i s d i f f i c u l t t o decide which of the four communities has the harshest p h y s i c a l environment. The c l ima te of the Tof ino area may be c l a s s e d as warm, temperate , and r a i n y ; tha t of the subalp ine meadow as c o n t i n e n t a l , c o l d , and humid but summer dry ( a f t e r K r a j i n a 19 65) . The o v e r a l l c l i m a t e of the subalp ine meadow might thus be cons idered harsher . But there are l o c a l microenvi ronmenta l c o m p l i c a t i o n s , The s a l t marsh i s subjec ted to great ranges i n d a i l y temperature , and the p l a n t s are p e r i o d i c a l l y baked by the sun and f looded by s a l t water (Chapman 1960, 19 64) . Dur ing the growing season, p l an t s i n the suba lp ine meadow are exposed to great d i u r n a l temperature f l u c t u a t i o n bo'thaabpveaand below ground (Kuramoto and B l i s s 197 0; B a l l a r d 1972),and may a l s o experience mois ture s t r e s s on s h a l l o w , w e l l - d r a i n e d s o i l s (Eady 1971). Only the c o a s t a l sphagnum bog has a t r u l y equable c l i m a t e , but i t s o v e r a l l p h y s i c a l environment, c h a r a c t e r i z e d by a low n u t r i e n t s t a tus and a wate r logged , p o o r l y oxygenated subs t ra te (Gorham 1957 ; Smal l 19 7 2a .. 8 b),,. .must .be. . .considered .compara t ive ly harsh Furthermore, as was po in ted out i n the s e c t i o n on l e v e l s of p o l y p l o i d y , environmenta l r i g o r i n c l u d e s r e l a t i v e ampli tude of environmental f l u c t u a t i o n s and the i r r e g u l a r i t y of these f l u c t u a t i o n s , as w e l l as average c o n d i t i o n s of the e n v i r o n -188 mental complex such as c l i m a t i c means and n u t r i e n t l e v e l s . The d i f f e r e n t l e v e l s of p o l y p l o i d y i n the three vege t a t i on types seemed to be best exp l a ined by d i f f e r e n t degrees of e n v i r o n -mental i n s t a b i l i t y . However, the l o g i c of Sec t . I I I - C does not apply to the f i n d i n g s of the I . P . R . , of which p o l y p l o i d y i s but one aspec t . D i f f e r e n t s e l e c t i o n pressures have been ope ra t i ng i n s a l t marshes, sphagnum bogs, and suba lp ine meadows, and d i f f e r e n t types of spec ies s t r a t e g i e s and community fea tures have evolved as a r e s u l t ('see s ec t . I V ) . A l l four communities have harsh environments , i n at l e a s t some r e s p e c t s . But there i s no i n d i c a t i o n tha t the d i f f e r e n t types of s e l e c t i o n d i f f e r i n o v e r a l l s e v e r i t y , a l though one ( tha t o f the suba lp ine meadow) may be caused more by b i o t i c f a c t o r s than another ( tha t of the s a l t marsh). I t i s not s u r p r i s i n g t ha t the I . P . R . ' s f o r the four communities are not s i g n i f i c a n t l y d i f f e r e n t . What i s more, t h i s a n a l y s i s says no th ing d i r e c t l y about the a c t u a l l e v e l s of gene t ic v a r i a b i l i t y w i t h i n the spec ies p o p u l a t i o n s . To get some measure of t h i s i t would be necessary to study enzyme polymorphisms or seed p r o t e i n v a r i a b i l i t y or some such molecu la r approach. But even i f one community had more spec ies w i t h more h e t e r o z y g o s i t y than the other communit ies , one s t i l l cou ld not ma in ta in tha t tha t community had b e t t e r adapted spec ies than the o t h e r s , s ince spec ies adaptedness can be achieved e i t h e r by i n d i v i d u a l a d a p t a b i l i t y (a homeostat ic genotype) or by gene t i c a d a p t a b i l i t y ( d i v e r s i t y of genotypes) (Dobzhansky 1968; c f . Gooch and Schopf 1972; L e v i n t o n 1973). Bradshaw (1971) puts the problem i n proper p e r s p e c t i v e : "There i s l i t t l e d i f f e r e n c e i n essence between 189 normal s i t u a t i o n s and extreme environments from an e v o l u t i o n a r y po in t of v i ew" . N e v e r t h e l e s s , i t would be extremely i n t e r e s t i n g to subjec t other predominant ly herbaceous v e g e t a t i o n types to s i m i l a r a n a l y s i s . Would, say , the extremely d i v e r s e , t a l l g r a s s p r a i r i e s of the Midwest or the c o a s t a l p r a i r i e s of Texas have h ighe r average I . P . R . ' s than the study communities? Would a r c t i c tundra or the d i s t u r b e d , weedy C e n t r a l V a l l e y g r a s s l and of C a l i f o r n i a have lower a v e r a g e . I . P . R . ' s ? What about o ther community comparisons; e g . , Great B a s i n v s . Sonoran d e s e r t s , C a l i f o r n i a c h a p a r r a l v s . A u s t r a l i a n thorn scrub? Sure ly here i s a tremendous f i e l d fo r fu ture i n v e s t i g a t i o n . Summary, Discussion, and Conclusions. 190 The f i n d i n g s of the present i n v e s t i g a t i o n are best summarized and con t ras t ed i n a balance sheet (Table 22) . General i n d i c a t i o n s are tha t i n t e r s p e c i f i c compe t i t ion increases from sphagnum bogs to s a l t marsh to suba lp ine meadow, w h i l e the s t r e s s of the p h y s i c a l environment inc reases from sphagnum bogs to subalp ine meadow to s a l t marsh. These i n d i c a t i o n s are not w h o l l y c o n s i s t e n t , but s e v e r a l genera l t rends are ev ident i n Table 22. A more s p e c i f i c summary f o l l o w s : 1. The vege t a t i on o f a s a l t marsh, two sphagnum bogs, and a suba lp ine meadow were desc r ibed by means o f t ab l e s of importance values and by modi f ied species c o n s t e l l a t i o n s 2. The p o p u l a t i o n s t r u c t u r e of the i n d i v i d u a l spec ies has been assessed w i t h a D/d index of aggrega t ion . Aggrega-t i o n increases as environmental he te rogene i ty and p h y s i c a l s t r e s s i n c r e a s e , and decreases as success ion proceeds and i n t e r s p e c i f i c compe t i t i on i n c r e a s e s . 3. Ind ices of a s s o c i a t i o n and c o r r e l a t i o n have been used to s t a t i s t i c a l l y assess i n t e r s p e c i f i c r e l a t i o n s h i p s . I n t e r s p e c i f i c a s s o c i a t i o n and c o r r e l a t i o n , both p o s i t i v e and n e g a t i v e , inc rease w i t h i n c r e a s i n g environmenta l he te rogene i ty and c o m p e t i t i o n . 4. Chromosome counts were made fo r most of the s p e c i e s , and l e v e l s of p o l y p l o i d y fo r both the f l o r a and vege t a t i on of a l l four communities were e s t a b l i s h e d . Leve l s of po ly p l o i d y appear to be c o r r e l a t e d w i t h environmenta l r i g o r TABLE 22. Resu l t s and i n d i c a t i o n s from var ious aspects of the i n v e s t i g a t i o n ; a l l i n d i c a t i o n s are r e l a t i v e . Community Spec i e s - a r ea curves Community d e s c r i p t i o n s Popu la t i on s t r uc tu r e (D/d index) S a l t Marsh Wade's Bog Ogg's Bog B l a c k w a l l Meadow co >. cu M-l CO •H cu CO Cl) & U CU O > •H •H TJ >i >, +-> rG •H ft O cu rtj ft bO rtf o O ft o bO -H a o •H >, o u •H u S rd O >, rrj +-> +-> cu +-> •H g o cu r -4 h igh s a l i n i t y c o a s t a l s a l t marsh, mainly i n r a p i d expansion and a c c r e t i o n c o a s t a l sphagnum bog at or approaching c l imax c o a s t a l sphagnum bog, f a i r l y e a r l y i n success ion l u s h , more or l e s s mes ic , Cascadian suba lp ine meadow; c l imax (?) species most aggregated; s t rong h a b i t a t zona t ion ; harsh p h y s i c a l environment; moderate compe t i t i on l e a s t aggrega t ion; weak i n t e r -s p e c i f i c compe t i t i on ; success-i o n a l ma tur i ty s t rong aggrega t ion ; micro topo-graphic mosaicism; weak compet-i t i o n ; s u c c e s s i o n a l youth moderate aggrega t ion ; m ic ro -topographic mosaicism; s t rong compe t i t i on ; s u c c e s s i o n a l ma tu r i ty Community A s s o c i a t i o n C o r r e l a t i o n Sa l t . Marsh Wade's Bog Ogg's Bog B l a c k w a l l Meadow heterogeneous moderate environment; compe t i t i on t i g h t m i c r o s i t e s p e c i f i c i t y g rea te s t p h y s i c a l s t r e s s +/- homogeneous weak environment; compe t i t i on loose m i c r o s i t e s p e c i f i c i t y i n t e rmed ia t e s t r e s s heterogeneous weak environment; compe t i t i on . t igh t m i c r o s i t e s p e c i f i c i t y - i n t e rmed ia te s t r e s s heterogeneous s t rong environment; compe t i t i on t i g h t m i c r o s i t e s p e c i f i c i t y lowest p h y s i c a l s t r e s s Levels of F lower ing P o l l i n a t i o n p o l y p l o i d y phenology ecology most p o l y -p l o i d y ; g rea tes t " r i g o r " ( h i s t o r i c a l and p h y s i c a l ) l e a s t p o l y -p l o i d y ; l e a s t r i g o r l e a s t p o l y -p l o i d y ; l e a s t r i g o r much p o l y -p l o i d y ; moderate-strong r i g o r CD CO rd CD P . O CD T 3 T 3 O •r-i U CD ft hO u o I—I 4 H M H O -H M | CD rH a) ca0| -rd & CD > weak i n t e r s p e c i f i c compet i t ion f o r p o l l i n a t i o n v e c t o r s ; p r i m a r i l y a b i o t i c p o l l i n a t i o n moderate compe t i t i on both b i o t i c and a b i o t i c p o l l i n a t i o n moderate compe t i t i on both b i o t i c and a b i o t i c p o l l i n a t i o n in tense c o m p e t i t i o n ; predominantly b i o t i c p o l l i n a t i o n DO o an 3 M OP pj pj fD pu OP ft H P) O -• CD rt ft x cn -• o t, cn s; pj tD pj H O to H OP So sh o o rt ft p f l cn ft cn tr ex, H H i cn O H - O 4 CD H ' O 4 rt H - O 4 rt H - H - O O rt H -CO 3 H' fu cn 3 H - 4 cn 3 H - 4 0 cn 3 4 4 cn >d OP 3 r V T j OP 3 O *d OP 3 0 rtW OP O •d CD 1 P) CD 1 pj 3 CD 1 pJ 3 H - CD 1 ft 3 CD 4 ft 4 O 4 ft 4 OP 4 O J 4 OP O 4 ft H.rjq 4 cn p . p- O cn H - H - cn H - H - cn H - cn cn P) cn H 3 pj cn H O pi cn H o pj cn >d o P) H rt ^ 0 H <+ •< O 1—1 rt CD O H P) fD PJ 3 p. 3 pj 4 3 3 PJ rt 3 t r u 3 tr>d CD o tr H - O H - CD O H - (D 4 O P) fD o (D H - r+ (C 0 rt fD O rt H - fD h-1 rt O O H - rt H - rt H - 3 H - H rt O H- rt H- rt PJ P) rt O H - 3 O H - O H - 4 OP H - OP O v . . O O H - fD 0 •< 3 3 H 3 3 ^ rt cn average n iche s i z e decreases + to  i n t e r s p e c i f i c compe t i t i on inc reases  average species v a r i a b i l i t y decreases cn cn cD 3 rt p- o o 3 O ft H ' H (D H O 4 OP P) OP PJ 4 H - rt O H - O fl) O rt P) I 3 "< H cn 4 o 3 CD o CD O 3 H *d ^  • CD rt H > rt H -O 3 rt 4 O 3 OP O O 3 •d fD fD O rt cn OP cn H -o pj s: H fD PJ ft X - H -cn rt H -3 O rt I rt -H -O 3 •d O 3 CD O O H PJ < CD 3 CD CD O rt cn OP H - 01 H rt O P-s: CD PJ ft W H -cn rt H -3 O rt I cn s! cn cn >0 CD H- rt CD PJ 3 4 O X H - O H - I H 3 H i 3 P) OP H - O 4 O ft H - (D CD rt O 0 4 ^ 0 O P ) H 3 rt O O •d CD H i O P CD H-rt H - Cn O H - 3 *d P) rt rt fD H • CD O 4 H -I CD cn O 3 index of dominance decreases spec ies d i v e r s i t y inc reases ^ C s t r e s s of p h y s i c a l environment decreases  s t a b i l i t y inc reases (?????) 2 H -O tr CD rt tr CD o 4 S i H -O tr CD ft H -H i H I CD 4 CD 3 rt H -PJ rt H -O 3 PJ O 3 0> ft 3 H -cn 3-rt P) pj 3 tr o H - CD rt £61 ft < ft) 4 cn H -rt 194 s e n s u l a t o . 5. The f o l l o w i n g aspects of species r ep roduc t ive b i o l o g y were s t u d i e d : a . f l o w e r i n g phenology b . f l o r a l b i o l o g y and p o l l i n a t i o n ecology c . d i s p e r s a l ecology d. c o m p a t i b i l i t y A l l four communities are dominated by o u t c r o s s i n g s p e c i e s . 6. The theory of the niche and va r ious c o r o l l a r i e s concern-i n g c o m p e t i t i o n , dominance, and v a r i a b i l i t y were d i s cus sed . The most abundant species (at l e a s t of grasses) are the most v a r i a b l e and presumably have the l a r g e s t n i c h e s . Niche s i z e and p o p u l a t i o n v a r i a b i l i t y decrease as i n t e r s p e c i f i c compe t i t i on i n c r e a s e s . 7. A numer ica l taxonomic approximat ion of each s p e c i e s ' n iche was at tempted. E c o l o g i c a l d i s s i m i l a r i t y reduces i n t e r s p e c i f i c c o m p e t i t i o n . 8. The not ions of d i v e r s i t y and s t a b i l i t y were i n v e s t i g a t e d . 9. An index of p o t e n t i a l recombina t ion was d e v i s e d , accord ing to which there i s no s i g n i f i c a n t d i f f e r e n c e i n p o t e n t i a l r e combina t i on , on the average, between spec ies of the four d i f f e r e n t communities. Fur ther b r i e f summaries of the f i n d i n g s and i n t e r p r e t a t i o n s o f t h i s i n v e s t i g a t i o n as they apply to each community type would be u s e f u l and are o u t l i n e d - b e l o w . 195 S a l t marsh Only a few species can s u r v i v e the s t r i n g e n t p h y s i c a l and chemica l c o n d i t i o n s of a h igh s a l i n i t y s a l t marsh. The marsh vege t a t i on i s dominated by the s t i l l 'fewer species tha t can not on ly s u r v i v e but a l so t h r i v e . Tide l e v e l s e x e r c i s e s t rong c o n t r o l over the v e r t i c a l d i s t r i b u t i o n s of s a l t marsh p l a n t s . The h a b i t a t zona t ion and m i c r o s i t e s p e c i f i c i t y promote aggregated popu la t ions and inc rease the s t r eng th o f i n t e r s p e c i f i c a s s o c i a -t i o n . Strong a s s o c i a t i o n and gross morpho log ica l and f u n c t i o n a l s i m i l a r i t i e s among marsh species r e s u l t i n s t rong i n t e r s p e c i f i c c o m p e t i t i o n . However, the harsh p h y s i c o - c h e m i c a l environment, by p l a c i n g a premium on s u r v i v a l and l i m i t i n g spec ies d i v e r s i t y , tends to counterac t the e f f e c t s o f compe t i t i on and d imin i shes the s t reng th o f i n t e r s p e c i f i c c o r r e l a t i o n . The phys iog raph ic i n s t a b i l i t y inheren t i n the c o a s t a l s a l t marsh environment has s e l e c t e d fo r a l l o p o l y p l o i d y i n most of the marsh s p e c i e s . The long growing season and low number of species i n the community i s r e f l e c t e d i n the long average f l o w e r i n g per iods of s a l t marsh s p e c i e s . The marsh i s dominated by p e r e n n i a l , hemicrypto-p h y t i c g rasses , sedges, rushes , and g r a s s - l i k e f o r b s ; t h i s growth form dominance i s r e f l e c t e d i n the predominant wind p o l l i n a t i o n . Vegetatiy . e . j a sexua l r ep roduc t ion i s common and e x t e n s i v e , and s e l f - c o m p a t i b i l i t y i s common, but the f l o r a l and p o l l i n a t i o n b i o l o g y of the spec ies i s such tha t the m a j o r i t y are outcrossed to some ex ten t . E f f e c t i v e long d i s t ance seed d i s p e r s a l i s p robably p r i m a r i l y b i o t i c . D i s p e r s a l by wind and water i s more e f f e c t i v e over shor t d i s t a n c e s . The dominant s a l t marsh 196 s p e c i e s have l a r g e niches and v a r i a b l e p o p u l a t i o n s . Most of the s p e c i e s have wide (though l o c a l ) d i s t r i b u t i o n s ; many probably have ecotypes and a few h y b r i d i z e with c l o s e l y r e l a t e d s p e c i e s or s u b s p e c i f i c taxa. Sphagnum bogs The low n u t r i e n t l e v e l s and c o l d , waterlogged, p o o r l y oxygenated s u b s t r a t e of a c o a s t a l sphagnum bog c o n s t i t u t e a severe p h y s i c o - c h e m i c a l environment, but the equable macro-c l i m a t e and the long term p h y s i o g r a p h i c s t a b i l i t y have c o n t r i b u t e d to the r e l a t i v e l y h i g h s p e c i e s d i v e r s i t y and r e l a t i v e l y low p o l y p l o i d y l e v e l s of the two study bogs. The nature of a sphagnum bog, which i s e s s e n t i a l l y a community of v a s c u l a r p l a n t s e p i p h y t i c upon mosses, s i g n i f i e s a mosaic of microtopography, water, and n u t r i e n t c o n d i t i o n s , a l l c o n t r o l l e d p r i m a r i l y by the moss s u b s t r a t e . T h i s p a t t e r n i n g r e s u l t s i n aggregated p o p u l a t i o n s and marked i n t e r s p e c i f i c a s s o c i a t i o n i n e a r l y s u c c e s s i o n a l stages. However, s i n c e a v a s c u l a r p l a n t i n a sphagnum bog e x i s t s more i n terms of Sphagnum spp. than i n terms of other v a s c u l a r p l a n t s , i n t e r s p e c i f i c c o m p e t i t i o n i s much l e s s of a f a c t o r than i n e i t h e r the s a l t marsh or the s u b a l p i n e meadow, and c o r r e l a t i o n tends to be weak. The great e c o l o g i c a l d i f f e r e n c e s among the bog s p e c i e s f u r t h e r reduce co m p e t i t i o n . The s p e c i e s are more or l e s s e q u a l l y anemophilous or entomophilous. As with the s a l t marsh, long d i s t a n c e seed d i s p e r s a l i s probably p r i m a r i l y zoochorous, with anemochory and hydrochory more important over short d i s t a n c e s . V e g e t a t i v e 197 r ep roduc t ion i s common, but n e i t h e r as common nor ex tens ive as i n the s a l t marsh. More than 7 0% of the spec ies o f both bogs are at l e a s t p a r t i a l l y s e l f - c o m p a t i b l e , but t h e i r f l o r a l and p o l l i n a t i o n b i o l o g y promote o u t c r o s s i n g . The dominant bog spec ies probably have f a i r l y l a rge n iches and v a r i a b l e p o p u l a t i o n s , but apparen t ly are r e l a t i v e l y , poor competi tors . ' Many of the spec ies range throughout the b o r e a l and s u b a r c t i c nor the rn hemisphere, but there i s a conspicuous P a c i f i c Northwestern American element i n the bog f l o r a . Ecotypels p r o b a b l y " a r e common, w h i l e i n t e r s p e c i f i c h y b r i d i z a t i o n i s apparent ly r e l a t i v e l y uncommon. Subalpine meadow The suba lp ine meadow has the most f avorab le o v e r a l l p h y s i c a l environment dur ing the growing season, and probably even dur ing the w i n t e r . Fac tors f a v o r i n g the e v o l u t i o n o f a l u s h , d i v e r s e p l a n t community i n an presumably unfavorable environment have been deep, w e l l - a e r a t e d s o i l , abundant mo i s tu r e , adequate n u t r i e n t s , and the h igh s o l a r r a d i a t i o n input and warm daytime temperatures dur ing the growing season, at l e a s t i n the mesic s i t e s tha t predominate i n the study meadow. H y d r i c and x e r i c s i t e s a l s o occur f r e q u e n t l y ; t h e i r d i s t r i b u t i o n i s s t r o n g l y c o r r e l a t e d w i t h micro topographic pa t te rns tha t c o n t r o l snow accumula t ion , water and n u t r i e n t r e l a t i o n s , and so- i l depth and development. The mosaic of m ic rohab i t a t s has l e d to moderately aggregated popu la t ions of s i g n i f i c a n t l y a s s o c i a t e d s p e c i e s . St rong a s s o c i a t i o n combined w i t h l u s h , t h i c k l y - g r o w i n g v e g e t a t i o n , h i g h spec ies d i v e r s i t y , 198 a shor t growing season, and a preponderance of showy-f lowered, entomophilous forbs produces in tense i n t e r s p e c i f i c c o m p e t i t i o n , which r e s u l t s i n very s h o r t , s taggered f l o w e r i n g per iods and s t rong c o r r e l a t i o n . Al though most of the spec ies are i n s e c t -p o l l i n a t e d , seed d i s p e r s a l (both s h o r t - and l o n g - d i s t a n c e ) i s most l i k e l y p r i m a r i l y by wind.' As i n the s a l t marsh, long- te rm phys iograph ic i n s t a b i l i t y has been i n s t r u m e n t a l i n s e l e c t i o n f o r a l l o p o l y p l o i d y i n a h igh percentage of the meadow f l o r a . Vege ta t ive r e p r o d u c t i o n i s f a i r l y common but not e x t e n s i v e . Almost 50% of the species are predominant ly s e l f - i n c o m p a t i b l e , and the m a j o r i t y are ou tc rossed . Subalpine meadow species probably have r e l a t i v e l y s m a l l , s p e c i a l i z e d n iches and popu la t ions tha t are not as v a r i a b l e as but have b e t t e r compe t i t i ve a b i l i t y than those of comparable s a l t marsh and sphagnum bog s p e c i e s . There are a few w i d e - r a n g i n g , a r c t i c -a l p i n e spec ies but the b u l k r o f t h e meadow f l o r a i s . widespread i n the c o r d i l l e r a of western North Amer ica . Both e c o t y p i c v a r i a t i o n and i n t e r s p e c i f i c h y b r i d i z a t i o n ^probably are r e l a t i v e l y common. My conc lus ions are best framed as answers to the three b a s i c ques t ions posed i n the I n t r o d u c t i o n . (1) Do p l an t communities of harsh p h y s i c a l environments e x h i b i t any c h a r a c t e r i s t i c p h y t o s o c i o l o g i c a l fea tures? Y e s , i f they have heterogeneous microtopographies (most d o ) , such communities w i l l have clumped spec ies popu la t ions and e x h i b i t s t rong i n t e r s p e c i f i c a s s o c i a t i o n and c o r r e l a t i o n . A l s o , l i f e - f o r m d i v e r s i t y w i l l be reduced i n communities where c o n d i t i o n s fo r growth are unfavorable f o r a major p o r t i o n of 199 each year ( e g . , a r c t i c and a l p i n e t und ra ) . An environment tha t i nc ludes c o n d i t i o n s tha t are severe but never the less w i t h i n the e c o l o g i c a l amplitude o f adapted species throughout most o f the year w i l l evolve many l i f e - f o r m s ( e g . , the Sonoran d e s e r t ) . (2) Are there any c o r r e l a t i o n s between environmenta l harshness and c e r t a i n s y n e c o l o g i c a l p r o p e r t i e s of such communities? Yes: (a) l e v e l s of p o l y p l o i d y w i t h i n the p l a n t communities i n t h i s i n v e s t i g a t i o n seem to be c o r r e l a t e d w i t h the degree of long- te rm phys iog raph ic i n s t a b i l i t y of the environment . (b) i f envi ronmenta l r i g o r i nc ludes a shortened growing season and i f the community i s p r i m a r i l y b i o t i c a l l y p o l l i n a t e d , i n t e r s p e c i f i c compe t i t i on f o r p o l l i n a t o r s w i l l i n c r e a s e , f l o w e r i n g times w i l l evolve d i f f e r e n t peaks , and there w i l l be s e l e c t i o n f o r e i t h e r showy, s p e c i a l i z e d f lowers or reduced, autogamous f l o w e r s . P ropo r t i ons of b i o t i c v s . a b i o t i c p o l l i n a t i o n and seed d i s p e r s a l are r e l a t e d only s e c o n d a r i l y to envi ronmenta l harshness ; they are e s s e n t i a l l y s ide e f f ec t s of s e l e c t i o n for an optimum growth form. I f hemic ryp tophy t i c g ra s ses , sedges , and rushes are best adapted f o r a c e r t a i n environment, wind p o l l i n a t i o n w i l l p r e v a i l ; i f herbaceous vege t a t i on i s f avo red , b i o t i c p o l l i n a t i o n w i l l predomi-nate . Seed d i s p e r s a l w i l l c l o s e l y depend on the r e l a t i v e a v a i l a b i l i t y o f b i o t i c and a b i o t i c vec to r s such as mammals, migra tory and r e s i d e n t b i r d s , w ind , and water . There i s no a priori reason f o r one or the other mode o f p o l l i n a t i o n or d i s p e r s a l to p r e v a i l i n severe environments. 200 (c) n iche s i z e (at l e a s t w i t h respec t to p h y s i c a l parameters) and p o p u l a t i o n v a r i a b i l i t y inc rease as envi ronmenta l harshness inc reases and i n t e r s p e c i f i c compe t i t i on decreases . (d) dominance o f the community by r e l a t i v e l y few species inc reases as harshness i n c r e a s e s . (e) spec ies d i v e r s i t y i s a good i n d i c a t o r of o v e r a l l e n v i r o n -mental s e v e r i t y and the s e l e c t i v e m i l i e u w i t h i n a p l a n t community. However, t h i s i s t rue on ly i n e x t e r n a l p e r s p e c t i v e . A s a l t marsh has a more r i g o r o u s e n v i r o n -ment than a maple-basswood f o r e s t , but i n which community i s Salioornia v irg m i c a more l i k e l y to su rv ive? L o w - d i v e r s i t y communities of severe p h y s i c a l environments are not n e c e s s a r i l y l e s s s t a b l e than any other communities (3) Are spec ies of such communities s e l e c t e d fo r r e p r o d u c t i v e s p e c i a l i z a t i o n s tha t ( accord ing to e s t a b l i s h e d e v o l u t i o n a r y theory) tend to reduce gene t i c v a r i a b i l i t y ? No, there i s l i t t l e evidence tha t t h i s i s so i n the four study communities. A l l four are dominated by o u t c r o s s i n g s p e c i e s ; there i s no pronounced t rend toward autogamy or apo-m i x i s (one might p r e d i c t tha t autogamous species w i l l evolve i n any undis turbed n a t u r a l p l a n t community, but w i l l not dominate such a community). Fur thermore, there i s no s i g n i f i c a n t d i f f e r e n c e i n p o t e n t i a l r e combina t i on , on the average, between the spec ies of the four d i f f e r e n t communities. The reason f o r the absence of d i f f e r e n c e s i s r e l a t e d to the l a r g e r problem of the genera t ion and maintenance o f v a r i a b i l i t y i n . ' popu la t ions and i t s r e l a t i o n to developmental 201 homeostasis and e v o l u t i o n a r y f l e x i b i l i t y . Why are 25 t o 50% of a l lozyme l o c i polymorphic i n a v a r i e t y of organisms, why are 10 to 15% of a i n d i v i d u a l ' s l o c i he te rozygous , and why i s there not a g rea te r range of v a r i a b i l i t y from organism to organism] ( c f . inter alia Gooch and Schopf 1972 ; Stebbins and Lewontin 1972; Lev in ton 1973)? Presumably, these l e v e l s of gene t ic v a r i a b i l i t y represent an e q u i l i b r i u m value adjusted by n a t u r a l s e l e c t i o n . The e q u i l i b r i u m can be mainta ined by a v a r i e t y of adap ta t ions . The d i f f e r e n t s t r a t e g i e s and adapta t ions of the species of the study communities r e f l e c t d i f f e r e n t types of s e l e c t i o n inheren t i n t h e i r community types . From an e v o l u t i o n a r y po in t of v i ew, there i s l i t t l e or no i n d i c a t i o n tha t the d i f f e r e n t types of s e l e c t i o n d i f f e r i n o v e r a l l s e v e r i t y , and the average l e v e l s of p o t e n t i a l recombina t ion probably represent some so r t o f e q u i l i b r i u m v a l u e . However, t h i s g e n e r a l i z a t i o n can be v a l i d a t e d on ly by s tudy ing o ther comparable communities a long s i m i l a r l i n e s . V. LITERATURE CITED. 202 Adams, D .A. 1963. Fac tors i n f l u e n c i n g v a s c u l a r p l a n t zona t ion i n Nor th C a r o l i n a s a l t marshes. Ecology 44: 445-456. A l l a r d , R.W. 1965. 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