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Some plant-mediated processes in the maritime wetlands of south-western British Columbia Ogwang, Bob Humphrey 1979

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SOME PLANT-MEDIATED PROCESSES IN THE MARITIME WETLANDS OF SOUTH-WESTERN BRITISH COLUMBIA  by  BOB HUMPHREY OGWANG . S c . ( A g r . ) , Makerere U n i v e r s i t y , Kampala, 1972 M . S c , Makerere U n i v e r s i t y , Kampala, 1975  A THESIS SUBMITTED IN PARTIAL FULFILLMENT OF THE REQUIREMENTS FOR THE DEGREE OF ,  DOCTOR OF PHILOSOPHY in  THE FACULTY OF GRADUATE STUDIES (Department o f P l a n t S c i e n c e )  We a c c e p t t h i s t h e s i s as conforming t o the r e q u i r e d s t a n d a r d  THE UNIVERSITY OF BRITISH COLUMBIA J u n e , 1979 fc)  Bob Humphrey Ogwang  In presenting this thesis in partial  fulfilment of the requirements for  an advanced degree at the University of B r i t i s h Columbia, I agree that the Library shall make i t freely available for reference and study. I further agree that permission for extensive copying of this thesis for scholarly purposes may by his representatives.  be granted by the Head of my Department or  It is understood  that copying or publication  of this thesis for financial gain shall not be allowed without written permission.  Department of The University of B r i t i s h Columbia 2075 W e s b r o o k P l a c e V a n c o u v e r , Canada V6T 1W5  my  ii ABSTRACT  The l a n d s c a p e s o f B r i t i s h C o l u m b i a , p r o m i n e n t l y m o d i f i e d by g l a c i a t i o n , p r e s e n t many l a r g e and v a r i e d w e t l a n d s .  These w e t l a n d s  have not been w e l l d e l i n e a t e d nor c l a s s i f i e d a l t h o u g h t h e y are b e i n g r a p i d l y m o d i f i e d f o r r e s i d e n t i a l , a g r i c u l t u r a l and i n d u s t r i a l ments.  Some f e d e r a l and p r o v i n c i a l a g e n c i e s are c u r r e n t l y  i n v e n t o r y and c l a s s i f i c a t i o n based l a r g e l y on s o i l p r o f i l e  develop-  undertaking characteristics.  To complement these e f f o r t s , p a r t i c u l a r l y f o r management p u r p o s e s ,  this  s t u d y was undertaken i n which p r e d o m i n a n t l y p l a n t - m e d i a t e d p r o c e s s e s were examined.  The i n v e s t i g a t i o n s were l i m i t e d to the m a r i t i m e marshes  o f south w e s t e r n B r i t i s h Columbia w i t h s t u d y s i t e s l o c a t e d i n the  Pitt,  Brunswick and Iona marshes. E s t i m a t e s o f p r o d u c t i v i t y were o b t a i n e d from s i n g l e and s e q u e n t i a l h a r v e s t i n g o f the a e r i a l v e g e t a t i o n . s p e c i e s and between s i t e s .  Peak s t a n d i n g crops v a r i e d between  S p e c i e s d i f f e r e n c e s were a t t r i b u t e d t o p l a n t  c h a r a c t e r i s t i c s such as p h o t o s y n t h e t i c canopy development and shoot configuration.  Peak s t a n d i n g crops were a l s o r e l a t e d t o e n v i r o n m e n t a l  v a r i a b l e s such as c l i m a t e , w a t e r r e g i m e , s a l i n i t y and s u b s t r a t e  nutrient  status. Data from s e q u e n t i a l h a r v e s t i n g r e v e a l e d t h a t most emergents e x p e r i e n c e d a r a p i d growth i n the s p r i n g and e a r l y summer d e c l i n i n g w i t h the o n s e t o f c o l d weather i n the f a l l .  Time o f peak p r o d u c t i o n  differed  markedly between s p e c i e s depending on presence o r absence o f o v e r w i n t e r e d p h o t o s y n t h e t i c s h o o t s , time o f shoot emergence and s e a s o n a l  i i i shoot m o r t a l i t y r a t e s . S t u d i e s o f belowground organs showed t h a t r o o t s and rhizomes may comprise up t o 85 p e r c e n t o f the t o t a l phytomass o f emergent v e g e t a t i o n emphasizing the importance o f t h i s f r a c t i o n i n w e t l a n d f u n c t i o n s  and  processes. The main r o u t e s o f d i s p o s i t i o n o f the emergents were as the g r a z i n g r o u t e , a c c u m u l a t i o n r o u t e and the d e t r i t a l G r a z i n g was r e l a t i v e l y unimportant i n the marshes.  identified route. Any g r a z i n g  o f the l i v i n g v e g e t a t i o n was c a r r i e d out l a r g e l y by g a s t r o p o d s , worms, i n s e c t s and r e s i d e n t and m i g r a n t w a t e r f o w l .  earth-  Minimal g r a z i n g o f  the marsh v e g e t a t i o n appeared to be r e l a t e d to u n f a v o u r a b l e w e t l a n d c o n d i t i o n s , h i g h l e v e l s o f s t r u c t u r a l c o n s t i t u e n t s and low l e v e l s n i t r o g e n i n the p l a n t s . age.  of  Q u a l i t y o f the v e g e t a t i o n d e c l i n e d s h a r p l y w i t h  Low ash l e v e l s and h i g h p h e n o l i c c o n t e n t were a l s o i m p l i c a t e d i n  the minimal g r a z i n g o f the P i t t marsh v e g e t a t i o n .  T o t a l energy c o n t e n t  appeared t o be unimportant i n t h i s r e g a r d . O r g a n i c m a t t e r a c c u m u l a t i o n was a d i s t i n c t f e a t u r e o f the marshes studied.  There was more o r g a n i c m a t t e r a c c u m u l a t i o n i n the P i t t than i n  the Brunswick marsh.  A c c u m u l a t i o n a l s o seemed to be more u n i f o r m o v e r  l a r g e areas i n the P i t t marsh than i n the t i d a l marshes. Data from o l d growth samples i n d i c a t e d t h a t a l a r g e p o r t i o n o f  the  phytomass produced i n t h e marshes e n t e r s t h e d e t r i t a l pathway v i a decomposition.  F a c t o r s a f f e c t i n g d e c o m p o s i t i o n r a t e s were d i s c e r n e d  l a r g e l y from l i t t e r bag t r i a l s and i n v i t r o d e c o m p o s i t i o n s t u d i e s . F r a g m e n t a t i o n o f l i t t e r by p h y s i c a l f o r c e s g e n e r a l l y preceded  biological  iv degradation.  Such comminution was more marked i n the F r a s e r d e l t a  marshes where t i d a l  and f r e s h e t a c t i v i t i e s are predominant.  was a s i g n i f i c a n t f a c t o r a f f e c t i n g d i s a p p e a r a n c e r a t e s .  Temperature  The r a t e s were  g e n e r a l l y lower i n the " c o o l e r " P i t t marsh than i n the "warmer" Brunswick marsh.  Low s o i l  temperatures t o g e t h e r w i t h low oxygen t e n s i o n s  were r e s p o n s i b l e f o r the r e l a t i v e l y low d e c o m p o s i t i o n r a t e s i n b u r i e d l i t t e r samples.  Decomposition r a t e s a l s o r e f l e c t e d the chemical com-  p o s i t i o n o f the emergent v e g e t a t i o n .  Less f i b r o u s s p e c i e s such as Carex  l y n g b y e i were more r e a d i l y degraded than more f i b r o u s s p e c i e s such as Carex s i t c h e n s i s . L e a c h i n g o f r e a d i l y degradable p l a n t m a t e r i a l s o c c u r r e d i n q u a n t i t i e s both i n l i v i n g and dead v e g e t a t i o n .  significant  Leaching losses i n  shoots averaged 64 mg/g l e a f d r y m a t t e r i n 4 d a y s .  living  V a r i a t i o n s i n stomatal  number, shape and d i s t r i b u t i o n were i m p l i c a t e d i n the p o s s i b l e mechanisms c o n t r o l l i n g l e a c h i n g l o s s e s i n l i v i n g emergent v e g e t a t i o n .  In dead s h o o t s ,  dry w e i g h t l o s s e s o f up to 50 p e r c e n t were r e c o r d e d o v e r a f o u r month period.  Such l o s s e s were a t t r i b u t e d m a i n l y t o l e a c h i n g .  High  initial  l o s s e s i n the l i t t e r bag and i n v i t r o d e c o m p o s i t i o n t r i a l s were a l s o suggestive of leaching.  V  TABLE OF CONTENTS Page 1.  INTRODUCTION  1  2.  REVIEW OF RELEVANT LITERATURE  5  2.1  Definitions  5  2.2  Wetland C l a s s i f i c a t i o n  6  2.3  A d a p t a t i o n o f Emergent S p e c i e s t o the Wetland Environment  7  2.4  D i s t r i b u t i o n o f Wetland F l o r a  9  2.5  P r o d u c t i v i t y o f Emergent V e g e t a t i o n  10  2.6  The Animal F a c t o r i n Wetlands  12  2.7  The D i s p o s i t i o n o f Wetland V e g e t a t i o n  14  2.7.1  The g r a z i n g pathway  14  2.7.2  D e t r i t a l pathway  18  2.7.3  A c c u m u l a t i o n pathway  20  3.  GENERAL DESCRIPTION OF THE STUDY AREAS, SUBSTRATES AND SPECIES  22  3.1  T i d a l Marshes o f the F r a s e r Foreshore  22  3.2  Fresh Water Marshes - P i t t Meadows  3.3  Upland S i t e s  31  3.4  A t t r i b u t e s o f Some o f the S i t e S u b s t r a t e s  34  3.4.1  M a t e r i a l s and methods  34  3.4.2  O b s e r v a t i o n s and r e s u l t s  35  3.4.3  Discussion  35  3.5  D e s c r i p t i o n o f the I n d i v i d u a l P l a n t S p e c i e s 3.5.1 3.5.2  Some taxonomic f e a t u r e s o f the p r i n c i p a l species studied Some p l a n t c h a r a c t e r i s t i c s o f the p r i n c i p a l species studied  . .  28  37  38 39  vi Page 3.5.3  4.  Some gross m o r p h o l o g i c a l f e a t u r e s  of  the s t a n d i n g shoots  40  3.5.3.1  M a t e r i a l s and methods  40  3.5.3.2  O b s e r v a t i o n s and r e s u l t s  41  3.5.3.3  Discussion  43  PRODUCTIVITY OF EMERGENT VEGETATION  44  4.1  Peak S t a n d i n g Crop Y i e l d s  44  4.1.1  M a t e r i a l s and methods  44  4.1.2  Results  46  4.1.3  Discussion  4.2  4.3  4.4  4.5  .  48  Seasonal Changes i n Dry M a t t e r P r o d u c t i o n  51  4.2.1  M a t e r i a l s and methods  52  4.2.2  O b s e r v a t i o n s and r e s u l t s  52  4.2.3  Discussion  56  Year t o Year V a r i a t i o n i n S p r i n g S t a n d i n g Crops  . . .  59  4.3.1  M a t e r i a l s and methods  60  4.3.2  Results  60  4.3.3  Discussion  60  Q u a n t i t a t i v e E s t i m a t e s o f Dead Phytomass  62  4.4.1  M a t e r i a l s and methods  63  4.4.2  O b s e r v a t i o n s and r e s u l t s  63  4.4.3  Discussion  66  Belowground Phytomass  68  4.5.1  M a t e r i a l s and methods  68  4.5.2  O b s e r v a t i o n s and r e s u l t s  69  4.5.3  Discussion  ^  7  vii  4.6  5.  C a l o r i c Content o f Some Emergent S p e c i e s  75  4.6.1  M a t e r i a l s and methods  75  4.6.2  O b s e r v a t i o n s and r e s u l t s  76  4.6.3  Discussion  76  DISPOSITION OF EMERGENT VEGETATION  78  5.1  G r a z i n g o f Emergent Wetland V e g e t a t i o n  79  5.2  A c c u m u l a t i o n o f Emergent V e g e t a t i o n i n the  5.3  Substrate  80  Decomposition o f Emergent V e g e t a t i o n  85  5.3.1  Decomposition s t u d i e s u s i n g l i t t e r bags . . . .  85  5.3.1.1  M a t e r i a l s and methods  86  5.3.1.2  O b s e r v a t i o n s and r e s u l t s  87  5.3.1.3  Discussion  91  5.3.2  In v i t r o d e c o m p o s i t i o n o f  Emergent  Vegetation  6.  95  5.3.2.1  M a t e r i a l s and methods  96  5.3.2.2  O b s e r v a t i o n s and r e s u l t s  97  5.3.2.3  Discussion  1 0 2  PLANT FACTORS LIMITING DEGRADATION OF EMERGENT VEGETATION 6.1  1 0 4  N e u t r a l and A c i d D e t e r g e n t F i b r e 6.1.1  M a t e r i a l s and methods  6.1.2  Results  6.1.3  Discussion  1 0 6  1 0 6  106 .  113  viii Page 6.2  6.3  6.4  6.5  7.  Lignin  113  6.2.1  M a t e r i a l s and methods  114  6.2.2  O b s e r v a t i o n s and r e s u l t s  115  6.2.3  Discussion  116  Cuticle  124  6.3.1  M a t e r i a l s and methods  126  6.3.2  O b s e r v a t i o n s and r e s u l t s  126  6.3.3  Discussion  129  Silica  152  6.4.1  M a t e r i a l s and methods  152  6.4.2  O b s e r v a t i o n s and r e s u l t s  152  6.4.3  Discussion  154  P h e n o l i c Compounds  154  6.5.1  M a t e r i a l s and methods  155  6.5.2  O b s e r v a t i o n s and r e s u l t s  156  6.5.3  Discussion  156  NUTRIENTS IN EMERGENT VEGETATION 7.1  N u t r i e n t C o n c e n t r a t i o n s i n the S t a n d i n g Crops 7.1.1  7.1.2  T o t a l ash  158 . . . .  159 159  7.1.1.1  M a t e r i a l s and methods  160  7.1.1.2  O b s e r v a t i o n s and r e s u l t s  160  7.1.1.3  Discussion  160  N i t r o g e n and s u l f u r  163  7.1.2.1  M a t e r i a l s and methods  164  7.1.2.2  O b s e r v a t i o n s and r e s u l t s  164  7.1.2.3  Discussion  168  Page 7.1.3  Response o f some emergents to f e r t i l i z e r nitrogen  7.2  8.  168  7.1.3.1  M a t e r i a l s and methods  169  7.1.3.2  O b s e r v a t i o n s and r e s u l t s  171  7.1.3.3  Discussion  182  L e a c h i n g from Shoots o f Emergent V e g e t a t i o n  184  7.2.1  M a t e r i a l s and methods  185  7.2.2  O b s e r v a t i o n s and r e s u l t s  186  7.2.3  Discussion  188  GENERAL DISCUSSION AND RECOMMENDATIONS  . .  196  8.1  P r o d u c t i v i t y o f Emergent V e g e t a t i o n  197  8.2  D i s p o s i t i o n o f Emergent V e g e t a t i o n  202  8.3  Proximate Chemical Components o f Emergent V e g e t a t i o n as a F a c t o r i n the Wetland System BIBLIOGRAPHY  . . . .  APPENDIX I.  II.  III.  IV.  V.  207 214 230  % o r g a n i c m a t t e r decomposed i n l i t t e r b a g s , where bags were p l a c e d on the s u b s t r a t e surface  230  Analysis of variance of % organic matter decomposed i n l i t t e r b a g s , where bags were p l a c e d on the s u b s t r a t e s u r f a c e  231  % o r g a n i c m a t t e r decomposed i n l i t t e r b a g s , where bags were p l a c e d 15 cm below the surface  232  Analysis of variance of % organic matter decomposed i n l i t t e r b a g s , where bags were p l a c e d 15 cm below the s u r f a c e  233  In v i t r o d e c o m p o s i t i o n o f o v e r w i n t e r e d shoots from w e t l a n d and c o n t r o l s p e c i e s ; e x p r e s s e d as % o r g a n i c m a t t e r l o s s  234  X  Page  VI. VII.  VIII.  Analysis of variance of % organic matter l o s s i n v i t r o ; o v e r w i n t e r e d shoots  235  In v i t r o d e c o m p o s i t i o n o f young shoots from w e t l a n d and c o n t r o l s p e c i e s ; e x p r e s s e d as % o r g a n i c m a t t e r l o s s  236  A n a l y s i s of variance of % organic matter l o s s i n v i t r o , young shoots  237  xi LIST OF TABLES  Table 3.1  3.2  4.1  4.2  4.3  4.4 4.5  4.6  4.7  Page E l e c t r i c a l C o n d u c t i v i t y , pH, % O r g a n i c M a t t e r , and A v a i l a b l e Major Elements i n the top 10 cm of the S o i l P r o f i l e o f some o f the Study S i t e s  36  Some Gross M o r p h o l o g i c a l F e a t u r e s o f S t a n d i n g Shoots of S e l e c t e d S p e c i e s from P i t t and Brunswick marshes, October 1977  42  E s t i m a t e s of Peak S t a n d i n g Crop Y i e l d s (Dry M a t t e r i n g/m^ as averaged from two meter square q u a d r a t s ) on Brunswick and Iona marshes and i n a r a b l e l a n d s a t A l a k s e n and Colony Farm  47  E s t i m a t e s o f Peak S t a n d i n g Crop Y i e l d s (Dry M a t t e r i n grams as averaged from two meter square q u a d r a t s ) f o r s i x s p e c i e s of the P i t t marsh, October 1977  47  2  Seasonal Changes i n the S t a n d i n g Crops (g/m Dry M a t t e r ) o f f i v e s p e c i e s from the F r a s e r d e l t a marshes and A r a b l e l a n d s , Summer 1976  53  Seasonal Changes i n S t a n d i n g Crops (g/m Dry M a t t e r ) o f f o u r s p e c i e s from the P i t t marsh, 1977  53  S p r i n g S t a n d i n g Crop E s t i m a t e s o f e i g h t s p e c i e s from from t h r e e l o c a t i o n s (g/m^ Dry M a t t e r as averaged from two meter square q u a d r a t s )  61  2  Dry M a t t e r Y i e l d s (g/m ) o f s e l e c t e d s p e c i e s from and nearby A r a b l e Lands, 2 Dry M a t t e r Y i e l d s (g/m ) o f f i v e s p e c i e s from the  o f New Growth and Old Growth the F r a s e r d e l t a marshes Summer 1976  64  o f New Growth and O l d Growth P i t t marsh, 1977  65  2 4.8 4.9  4.10  Dry M a t t e r Y i e l d s (g/m ) o f Old Growth f o r some s p e c i e s , W i n t e r o f 1977/78  65  Belowground Phytomass ( d r y w t . b a s i s ) o f s e l e c t e d s p e c i e s from Brunswick marsh and P i t t o l d f i e l d , November 1977  70  R a t i o o f Belowground t o Aboveground Phytomass o f s e l e c t e d s p e c i e s from Brunswick marsh, P i t t marsh and P i t t o l d f i e l d , November 1977  72  xii Table 4.11  4.12  5.1  5.2 5.3 5.4 6.1 6.2 6.3 6.4  Page Percent of Readily Hydrolyzable carbohydrates ( d r y w t . b a s i s ) i n Belowground Phytomass o f s e l e c t e d s p e c i e s from Brunswick marsh, P i t t marsh and P i t t o l d f i e l d , November 1977  73  Seasonal Changes i n Energy Content ( K c a l / g ) o f S t a n d i n g Crop o f some Emergents from s e v e r a l l o c a t i o n s , 1977  77  the  Summary o f the Main E f f e c t s o f L i t t e r Bag Decomposition where Bags were p l a c e d on the Substrate Surface  88  Summary o f the Main E f f e c t s o f L i t t e r Bag S t u d i e s , where Bags were p l a c e d 15 cm Below the S u r f a c e  92  Summary o f the Main E f f e c t s o f In V i t r o S t u d i e s , O v e r w i n t e r e d Shoots  9 8  Summary o f the Main E f f e c t s o f In V i t r o S t u d i e s , Young Shoots Seasonal Changes i n N e u t r a l Detergent (as % Dry M a t t e r ) , Summer 1976  Fibre  Seasonal Changes i n N e u t r a l D e t e r g e n t (as % Dry M a t t e r ) , W i n t e r 1977-1978  Fibre  99 107 110  Seasonal Changes i n A c i d D e t e r g e n t F i b r e (as % Dry M a t t e r ) , Summer 1976  HI  Seasonal Changes i n A c i d D e t e r g e n t F i b r e (as % Dry M a t t e r ) , 1977, 1978  1 1  6.5  Seasonal Changes i n L i g n i n (as % Dry M a t t e r ) , 1976  6.6  Seasonal Changes i n L i g n i n (as % Dry M a t t e r ) , 1977 - 1978 H i s t o l o g i c a l P a r t i t i o n i n g o f L i g n i f i e d Leaf T i s s u e s i n Transverse sections  6.7 6.8 6.9  . . . .  2  117  US H9  H i s t o l o g i c a l P a r t i t i o n i n g o f L i g n i f i e d Stem T i s s u e s i n Transverse sections  '20  A n a t o m i c a l Component Measurement on Leaves Transverse sections  12'  in  A n a t o m i c a l Component Measurements on Stems i n Transverse sections Seasonal Changes i n C u t i n (as % Dry M a t t e r ) , Summer 1976 Seasonal Changes i n C u t i n (as % Dry M a t t e r ) , 1977 - 1978 S i l i c a (as % Dry Weight) i n the S t a n d i n g Crops of some s p e c i e s samples on 19 October 1977 . . . Average C o n c e n t r a t i o n o f T o t a l Phenols i n the Leaves H a r v e s t e d on 10 May 1978 Seasonal Changes i n T o t a l Ash (as % Dry Wt.) o f S e l e c t e d s p e c i e s from s e v e r a l s i t e s , 1976 . . . . 2 Seasonal Changes i n T o t a l Ash (as % and as g/m Dry M a t t e r i n the s t a n d i n g c r o p ) o f s e l e c t e d s p e c i e s from s e v e r a l s i t e s , 1977 - 1978 Seasonal Changes i n N i t r o g e n (as % D r y . Wt.) o f s e l e c t e d s p e c i e s from s e v e r a l s i t e s , 1976 . . . . Seasonal Changes i n N i t r o g e n (as % Dry Wt. and g/m i n Dry M a t t e r o f s t a n d i n g c r o p ) o f s e l e c t e d s p e c i e s from s e v e r a l s i t e s , 1977 2  Seasonal Changes i n S u l f u r ( p a r t s per m i l l i o n , Dry Wt.) o f s e l e c t e d p l a n t s p e c i e s from s e v e r a l s i t e s , 1977 E f f e c t o f two sources o f N i t r o g e n F e r t i l i z e r on Dry M a t t e r P r o d u c t i o n (g/m ) 2  E f f e c t o f M a t u r i t y Stage on Dry M a t t e r (g/m )  Production  2  E f f e c t o f N i t r o g e n A p p l i c a t i o n on the N Content o f the Shoots a t s e v e r a l s t a g e s o f growth . . . . Apparent Recovery of two N i t r o g e n o u s F e r t i l i z e r s a t 12 weeks o f Regrowth .,  xiv Table 7.10  7.11 7.12  Page Summary o f the A n a l y s i s o f V a r i a n c e o f the C a r r y Over E f f e c t o f N i t r o g e n A p p l i e d i n 1976 on 1977 s t a n d i n g , c r o p s  181  T o t a l Leachate (mg/g Leaf Dry Weight) from selected species  187  E s t i m a t e s o f Stomatal Number observed under 50 x M a g n i f i c a t i o n f o r s e v e r a l Wetland s p e c i e s  193  XV  LIST OF FIGURES  Figure  Page  3.1  Map showing L o c a t i o n o f the Study Areas  23-24  3.2  Photographs showing Emergent Communities i n the Brunswick marsh (Summer 1977)  26-27  3.3  Photographs showing Emergent S p e c i e s i n the marsh, ( S p r i n g 1978)  29-30  3.4  Photographs showing L o l i u m perenne - Agropyron repens s t a n d a t A l a k s e n dyked a r a b l e o l d f i e l d  .  32-33  4.1  Photographs showing V a r i a t i o n s i n Communities w i t h V a r i a b l e Water Depth . .  49-50  4.2  Photographs showing c o n t r a s t s i n Timing o f Shoot Death, Iona marsh  54-55  4.3  Photographs showing O l d e r O v e r w i n t e r e d F l o w e r i n g Shoots and New Shoots o f Carex s i t c h e n s i s i n P i t t marsh ( S p r i n g 1976)  57-58  5.1  A c c u m u l a t i o n o f O r g a n i c M a t t e r i n the P i t t marsh (Summer 1976)  81-82  5.2  A c c u m u l a t i o n o f O r g a n i c M a t t e r i n the Brunswick marsh  83-84  5.3  Decomposition i n L i t t e r Bags P l a c e d on the Substrate Surface  5.4  In V i t r o Decomposition o f O v e r w i n t e r e d and Young SFooti . . '.  100-101  6.1  Seasonal Changes i n NDF  108-109  6.2  Scanning E l e c t r o n Photomicrographs o f A d a x i a l S u r f a c e s o f Carex s i t c h e n s i s ( P i t t )  6.3 6.4  Pitt  Leaf 130-132  Scanning E l e c t r o n Photomicrographs o f Shoot Surfaces of S c i r p u s acutus ( P i t t ) Scanning E l e c t r o n Photomicrographs o f A d a x i a l S u r f a c e s o f Equisetum f l u v i a t i l e ( P i t t )  133-135 Leaf 136-138  xvi  Figure 6.5 6.6 6.7 6.8 7.1  7.2 7.3  7.4  Page Scanning E l e c t r o n Photomicrographs o f A d a x i a l S u r f a c e s o f Carex l y n g b y e i ( B r u n s w i c k )  Leaf  Scanning E l e c t r o n Photomicrographs o f A d a x i a l S u r f a c e s o f F e s t u c a a r u n d i n a c e a (Brunswick)  Leaf  Scanning E l e c t r o n Photomicrographs o f A d a x i a l S u r f a c e s o f Typha l a t i f o l i a ( B r u n s w i c k )  Leaf  Scanning E l e c t r o n Photomicrographs o f A d a x i a l Surfaces of Dactyl i s glomerata (Alaksen)  Leaf  139-141 142-144 145-147 148-150  E f f e c t s o f M a t u r i t y and F e r t i l i z e r N i t r o g e n on Dry Matter Production of P h a l a r i s arundinacea in a U n i v e r s i t y of B r i t i s h Columbia o l d f i e l d  . . .174-175  E f f e c t s o f M a t u r i t y and F e r t i l i z e r N i t r o g e n on Dry M a t t e r P r o d u c t i o n of Carex l y n g b y e i i n Iona marsh  176-177  R a t i o o f I n o r g a n i c t o Organic M a t t e r Leached from the Shoots o f 3 Emergents and 2 A r a b l e o l d f i e l d Species  189-190  P e r c e n t o f S t a n d i n g Crop Ash Recovered i n the Leachate  191-192  xvi i  A C K N O W L E D G E M E N T S  I w i s h t o acknowledge the guidance and c o n s t r u c t i v e  criticisms  g i v e n to me by my s u p e r v i s o r P r o f e s s o r V. C. B r i n k throughout the research  project.  S u g g e s t i o n s made by the Committee members, Dean W. D. K i t t s , Dr. R. M. T a i t (Animal S c i e n c e ) , Dr. V. C. Runeckles (Chairman P l a n t S c i e n c e Department) and Dr. A. J . Renney ( P l a n t S c i e n c e ) , i n w r i t i n g up the t h e s i s are h i g h l y a p p r e c i a t e d . Many thanks to Dr. G. W. Eaton f o r h i s a d v i c e on s t a t i s t i c a l Technical  analyses.  a s s i s t a n c e by I . D e r i c s , A. H e r a r t h , A. Hoda ( P l a n t  S c i e n c e ) , B. v o n S p i n d l e r ( S o i l S c i e n c e ) and G. G a l z y (Animal S c i e n c e ) i s g r a t e f u l l y acknowledged.  S p e c i a l thanks t o Dr. A. R. Forbes and  Mr. Cho Kai ( A g r i c u l t u r e Canada, Vancouver) f o r t h e i r a s s i s t a n c e w i t h the e l e c t r o n m i c r o s c o p e . My s i n c e r e thanks a l s o go t o Miss J u d i t h Johnson f o r h e r a s s i s t a n c e d u r i n g the p r e p a r a t i o n o f the m a n u s c r i p t . F i n a l l y I w i s h t o g r a t e f u l l y acknowledge the f i n a n c i a l  aid provided  by the Canadian I n t e r n a t i o n a l Development Agency f o r my s t u d i e s Canada.  in  1 1.  INTRODUCTION  The terms " m a r s h e s " , "swamps", " b o g s " , have been used f o r c e n t u r i e s but o n l y r e c e n t l y have t h e r e been any attempts to group them under a s i n g l e term: w e t l a n d .  The need to do t h i s has grown o u t o f a d e s i r e  t o understand and d e s c r i b e the c h a r a c t e r i s t i c s and v a l u e s o f a l l  types  o f l a n d , as w e l l as to w i s e l y and e f f e c t i v e l y manage w e t l a n d e c o s y s t e m s . However, a s i n g l e , i n d i s p u t a b l e and e c o l o g i c a l l y sound d e f i n i t i o n w e t l a n d would not s a t i s f y a l l  interested disciplines.  Moreover,  i s a g r a d a t i o n between dry and wet environments and boundaries can o n l y be a r b i t r a r y .  there  imposed  Consequently, only a generalized d e f i n i t i o n  be g i v e n here t o s e r v e as a frame o f r e f e r e n c e f o r the s t u d i e s in this thesis.  for  will  reported  Wetland may be r e g a r d e d as l a n d where the w a t e r t a b l e  is  a t , near o r above the l a n d s u r f a c e l o n g enough each y e a r to promote the f o r m a t i o n o f h y d r i c s o i l s and to s u p p o r t the growth o f h y d r o p h y t e s . "permanent" o r y e a r long open w a t e r i s c o n s i d e r e d a q u a t i c h a b i t a t ,  If then  the upper l i m i t o f w e t l a n d i s determined by: (1)  the change from p r e d o m i n a n t l y hydrophytes t o p r e d o m i n a n t l y mesophytes o r x e r o p h y t e s ;  (2)  the change from p r e d o m i n a n t l y h y d r i c t o n o n - h y d r i c s o i l s ;  (3)  the change from l a n d t h a t i s f l o o d e d a t some time to  land  which i s never f l o o d e d d u r i n g y e a r s o f normal p r e c i p i t a t i o n . W e t l a n d s , by t h i s d e f i n i t i o n , range from s u b - a q u a t i c t o x e r i c e n v i r o n m e n t s , from c o a s t a l s a l t marshes t o i n t e r i o r s l o u g h s and to bogs. They o c c u r on azonal f r e s h l y d e p o s i t e d sediments and on o l d ombrogenous p e a t s ; and t h e i r d i s t r i b u t i o n ranges from t r o p i c t o a r c t i c  latitudes,  2 and from l o w l a n d t o a l p i n e z o n e s .  Wetland p l a n t communities a r e commonly  a s s o c i a t e d w i t h r e l a t i v e l y s t a g n a n t w a t e r bodies  ( e . g . l a k e s and swamps),  as w e l l as streams and s h o r e l i n e s where water movements are s u b s t a n t i a l . There are many b i o g e o c h e m i c a l f a c t o r s a t t e n d a n t on areas o f w e t l a n d v e g e t a t i o n , but i t i s i m p o r t a n t t o o b s e r v e t h a t catchment b a s i n s w i t h s t a n d i n g w a t e r are g e n e r a l l y f i l l i n g , i n o r g a n i c sediments and s o l u b l e s . of l o c a l o r i g i n .  i n v a r y i n g d e g r e e , w i t h o r g a n i c and  The s m a l l e r b a s i n s o f t e n r e c e i v e m a t e r i a l  The sediments and s o l u b l e s o f r i v e r i n e and c o a s t a l  w a t e r s may, on the o t h e r hand, be i m p o r t e d f r o n a n d / o r e x p o r t e d t o  large  areas w i t h w i d e l y d i f f e r i n g p a r e n t m a t e r i a l s . The economic and e c o l o g i c importance o f w e t l a n d s i s r e f l e c t e d i n t h e i r diversified functions.  The e a r l y occupancy by man o f some o f the l a r g e s t  d e l t a i c areas o f the w o r l d , e . g . the Ganges, N i l e , Rhine and T i g r i s Euphrates d e l t a s i s common r e c o r d .  B i o l o g i c a l l y , some w e t l a n d systems  are known t o be among the most p r o d u c t i v e ecosystems and they have been i n t e n s i v e l y e x p l o i t e d by man.  Some o f the w o r l d ' s g r e a t e s t c e n t r e s  of  human p o p u l a t i o n , i n d u s t r y , and a g r i c u l t u r e a r e found on m o d i f i e d w e t l a n d s . Wetland v e g e t a t i o n i s a l s o used by man f o r f u e l , food and p u l p .  Despite  t h e i r i m p o r t a n c e , i t i s perhaps a s t o n i s h i n g t h a t , as a s u b j e c t o f s c i e n t i f i c i n q u i r y , w e t l a n d systems have been accorded s i g n i f i c a n t  attention  only recently. H i s t o r y shows t h a t m o d i f i c a t i o n o f wetlands by man has been going on f o r c e n t u r i e s and s t i l l  c o n t i n u e s a t a . r a p i d pace.  c o n s t r u c t i o n , d y k i n g , i r r i g a t i o n , waste d i s p o s a l , o i l  Drainage, canal and gas e x p l o r a t i o n ,  a g r i c u l t u r a l and i n d u s t r i a l e x p l o i t a t i o n a r e but some o f the man r e l a t e d  3  a c t i v i t i e s a f f e c t i n g on w e t l a n d s i n v a r i o u s p a r t s o f the w o r l d .  So  r a p i d are the e x p l o i t a t i o n s , m o d i f i c a t i o n s and a l i e n a t i o n s o f w e t l a n d s t h a t i f t h e i r n a t u r a l f u n c t i o n s are t o be s t u d i e d a t a l l , t h e y must be s t u d i e d now. There are e x t e n s i v e areas o f w e t l a n d i n B r i t i s h Columbia which have not y e t been a d e q u a t e l y mapped o r d e s c r i b e d .  Large areas o f wet meadow  o c c u r on the c o m p a r a t i v e l y u n i f o r m s u r f a c e s o f the i n t e r i o r p l a t e a u x , a l o n g the margins o f r i v e r s and l a k e s , and a t the head o f v i r t u a l l y i n l e t s along the f i o r d c o a s t .  all  Much o f the w e t l a n d i s a r e s u l t o f the  i n t e r r u p t i o n o f d r a i n a g e p a t t e r n s e f f e c t e d by r e c e n t and complete g l a c i a t i o n s o f the P r o v i n c e . In B r i t i s h Columbia t o o , d e s p i t e the c o m p a r a t i v e l y r e c e n t occupancy o f the l a n d by w h i t e man, e x p l o i t a t i o n i s p r o c e e d i n g r a p i d l y w i t h c o m p a r a t i v e l y l i t t l e knowledge o f w e t l a n d d i s t r i b u t i o n , p r o c e s s e s and f u n c t i o n s .  ecological  I t i s t o be e x p e c t e d t h a t an i n v e n t o r y and  c l a s s i f i c a t i o n of wetlands should r e c e i v e f i r s t a t t e n t i o n .  So v a r i e d  however are the w e t l a n d s o f B r i t i s h Columbia i n terms o f d i s t r i b u t i o n , n a t u r e and u s e , t h a t i n v e n t o r y i s p r o c e e d i n g s l o w l y and h a l t i n g l y . A s s i s t a n c e would be accorded the i n v e n t o r y i f t h e r e was a b e t t e r unders t a n d i n g o f the f u n c t i o n s o f , and the p r o c e s s e s a t work i n , the w e t l a n d systems.  The work r e p o r t e d here was undertaken to a i d i n , o r perhaps  might even be s a i d to i n i t i a t e a b e t t e r u n d e r s t a n d i n g o f the r o l e p l a y i n these f u n c t i o n s and p r o c e s s e s .  Such e f f o r t s would be o f  plants value  not o n l y f o r i n v e n t o r y p u r p o s e s , but a l s o f o r proper management, use and c o n s e r v a t i o n o f the w e t l a n d s .  it  4  There are s e v e r a l ways o f a s s e s s i n g the r o l e p l a n t s p l a y wetland systems.  In B r i t i s h C o l u m b i a , the q u a n t i t i e s o f  in  plant  m a t e r i a l produced i n w e t l a n d systems are known o n l y from s c a t t e r e d s o u r c e s and are o f t e n p o o r l y d e t e r m i n e d . m a t e r i a l has been o n l y t h i n l y a s s e s s e d .  The q u a l i t y o f the p l a n t Very l i t t l e i s known about  the d i s p o s i t i o n o f the w e t l a n d p l a n t s - whether through g r a z i n g , o x i d a t i o n , accumulation or t r a n s p o r t a t i o n to other systems. b a s i c approach o f the i n q u i r y t h e r e f o r e c e n t e r e d on these  The  deficient  areas w i t h the i n v e s t i g a t i o n s l i m i t e d to the emergent p l a n t communities of south western B r i t i s h Columbia.  The t e c h n i q u e s used were r a t h e r  crude and s i m p l e , l a r g e l y i n d i c a t i v e o f the c o m p a r a t i v e y o u t h f u l n e s s o f w e t l a n d s t u d i e s which o f t e n l a c k s o p h i s t i c a t i o n and are u s u a l l y , best, semi-quantitative.  I t i s hoped t h a t t h i s i n q u i r y w i l l  at  constitute  p a r t o f a broader s t u d y o f B r i t i s h C o l u m b i a ' s w e t l a n d s y s t e m s .  5 2.  2.1  REVIEW OF RELEVANT LITERATURE  Definitions  The term " w e t l a n d " can be used t o d e s c r i b e a wide v a r i e t y o f highly contrasting landscapes.  A common f e a t u r e o f w e t l a n d s i s  that  they have a h i g h w a t e r t a b l e f o r a s u b s t a n t i a l p a r t o f the y e a r .  Their  s u b s t r a t e s are h i g h l y v a r i a b l e , r a n g i n g i n m a t e r i a l s t h a t are almost 100 p e r c e n t o r g a n i c t o almost 100 p e r c e n t m i n e r a l m a t t e r and a l l p o s s i b l e c o m b i n a t i o n s i n between.  the  The w a t e r a s s o c i a t e d w i t h w e t l a n d s  may be f r e s h o r s a l i n e w i t h i n f i n i t e c o m b i n a t i o n s between the two extremes.  I t i s t h e r e f o r e not s u r p r i s i n g , as has been p r e v i o u s l y s t a t e d ,  t h a t v a r i a t i o n s i n d e f i n i t i o n and concept o f w e t l a n d e x i s t i n the literature.  The d e f i n i t i o n g i v e n i n the i n t r o d u c t o r y statement and  r e p o r t e d here was s u p p o r t e d by Cowardin e t aj_. ( 1 9 7 6 ) .  It  conveniently  combines both e d a p h i c and v e g e t a t i o n a l f e a t u r e s o f w e t l a n d .  Some workers  emphasize o n l y one o r the o t h e r as a b a s i s f o r t h e i r d e f i n i t i o n . i n s t a n c e , w e t l a n d s are d e f i n e d by S j o r s (1948) and the N a t i o n a l  For Soil  Survey Committee o f Canada (1970) as areas where wet s o i l s are p r e v a l e n t , having a w a t e r t a b l e near o r above m i n e r a l s o i l , as i n d i c a t e d by g l e y i n g i n the m i n e r a l s o i l  horizon.  Mornsjo (1969) g i v e s a s i m i l a r  definition  but adds t h a t wetlands have a v e g e t a t i o n adapted to p e r i o d i c w a t e r l o g g i n g . He a l s o s t a t e s t h a t the s o i l s o f w e t l a n d s are l a r g e l y peat and when m i n e r o g e n i c they may be g l e y i s h s o i l s o f v a r i o u s k i n d s .  Terminology  w e t l a n d s o i l s o f North America has been d e s c r i b e d by M c K i n z i e  (1974).  for  6 Concomitant w i t h the v a r i e t y o f d e f i n i t i o n s are t h e numerous shades  of  meaning a t t a c h e d t o terms such as swamp, bog, p e a t , meadow and marsh which a r e commonly used t o d e s c r i b e the w e t l a n d s .  There i s no doubt  t h a t many o f these terms can be u s e f u l l y employed to d i s t i n g u i s h and i m p o r t a n t d i f f e r e n c e s among h i g h l y complex e c o l o g i c a l  real  situations.  F o r a complete e x p l a n a t i o n o f the s p e c i f i c d i f f e r e n c e s o r s i m i l a r i t i e s between w e t l a n d terms such as ombrogeneous, o m b r o t r o p h i c ,  ombrophilous  and s o l i g e n e o u s w e t l a n d s and bog, moor, swamp and f e n , the r e a d e r  is  r e f e r r e d to H o t c h k i s s and S t e w a r t ( 1 9 4 7 ) , Penfound ( 1 9 5 2 ) , Heinselman (1963) and Z o l t a i e t al_. ( 1 9 7 5 ) .  2.2  Wetland C l a s s i f i c a t i o n  N a t i o n a l and r e g i o n a l systems o f c l a s s i f i c a t i o n have been developed f o r w e t l a n d i n many p a r t s o f the w o r l d t o s e r v e a number o f o b j e c t i v e s . In g e n e r a l , most systems group w e t l a n d s a c c o r d i n g t o e x t e r n a l o r i n t e r n a l features.  The e x t e r n a l f e a t u r e s may be s u b d i v i d e d i n t o those s t r e s s i n g  the b i o t i c o r a b i o t i c e l e m e n t s .  The b i o t i c s u b d i v i s i o n s emphasize  f e a t u r e s o f p l a n t physiogonomy, dominance o r f l o r i s t i c s P o l l e t t and B r i d g e w a t e r 1973, W h i t t a k e r 1962).  (Penfound 1967,  The a b i o t i c  character-  i s t i c s are emphasized i n a l a n d f o r m approach where the s u r f a c e form o f w e t l a n d s (Adams and Z o l t a i 1969) are used to d i f f e r e n t i a t e types.  different  Most o f the i n t e r n a l p r o p e r t i e s are based on s o i l type and  n u t r i e n t s t a t u s ( S j o r s 1959, Heinselman 1963).  A comprehensive  h i e r a r c h i a l approach o f t h i s k i n d i s the b a s i s f o r the  recently  proposed c l a s s i f i c a t i o n systems o f Z o l t a i e t al_. (1975) f o r Canada,  7 and Cowardin e_t aj_. (1976) f o r the U n i t e d S t a t e s .  T a k i n g , f o r example,  the Z o l t a i ejt aj_. c l a s s i f i c a t i o n , i t i d e n t i f i e s 5 b a s i c w e t l a n d c l a s s e s i  n  L e v e l 1 (marsh, swamp, f e n , bog and s h a l l o w open w a t e r ) .  Each c l a s s  i s d i f f e r e n t i a t e d on the b a s i s o f s o i l t y p e , water regime, water c h e m i s t r y , i n t e r n a l d r a i n a g e c h a r a c t e r i s t i c s , s u r f a c e morphology and dominant forms o f v e g e t a t i o n s .  Each c l a s s i s s u b d i v i d e d i n L e v e l 2 a c c o r d i n g  s u r f a c e morphology o f the w e t l a n d ( f o r bogs and f e n s ) , features waters).  life to  hydrotopographic  ( f o r marshes and swamps) and a d j o i n i n g l a n d ( f o r s h a l l o w open L e v e l s 3 and 4 s t r e s s v e g e t a t i o n types and the s p e c i a l i z e d  needs o f v a r i o u s d i s c i p l i n e s r e s p e c t i v e l y .  In a d d i t i o n t o t h e Z o l t a i  e t a]_. s y s t e m , t h e r e p r o b a b l y e x i s t many o t h e r systems l i k e  that  r e p o r t e d by H i l t o n (1975) f o r the i n t e r i o r o f B r i t i s h C o l u m b i a , which are being used i n v a r i o u s p a r t s o f Canada.  In most c a s e s , such  r e g i o n a l systems are s e n s i t i v e to d i f f e r e n c e s t h a t a n a t i o n a l system cannot r e f l e c t so t h a t they s e r v e a b e t t e r purpose f o r r e s e a r c h and management.  intensive  Taxons f o r B r i t i s h Columbia w e t l a n d s , i t may  be o b s e r v e d , are not w e l l e s t a b l i s h e d and tend to be h i g h l y d e s c r i p t i v e o n l y weakly r e f l e c t i n g fundamental p r o c e s s e s a s s o c i a t e d w i t h t h e i r occurrence.  2.3  A d a p t a t i o n o f Emergent S p e c i e s t o the Wetland Environment  Wetland s u b s t r a t e s may be s i m p l y and c o n v e n i e n t l y d e f i n e d as s u b s t r a t e s t h a t a r e more o r l e s s permanently s a t u r a t e d o r submerged. The U . S . D . A . S o i l Survey S t a f f (1968) proposed a s a t i s f a c t o r y c l a s s i f i c a t i o n o f w e t l a n d s o i l s i n North A m e r i c a .  8 The o u t s t a n d i n g f e a t u r e s o f t h e s e s o i l s are the a c c u m u l a t i o n o f p l a n t r e s i d u e s i n the s u r f a c e h o r i z o n , the presence o f a permanently reduced h o r i z o n below i t , p r e v a i l i n g a n a e r o b i c c o n d i t i o n s and g e n e r a l l y low pH.  These f e a t u r e s o f t e n p r e s e n t s t r e s s c o n d i t i o n s t o the p l a n t s  growing, i n wetland s u b s t r a t e s .  Through e v o l u t i o n , w e t l a n d p l a n t s have  developed s e v e r a l a d a p t i v e mechanisms t h a t e n a b l e them t o "ward  off"  t o x i c r e d u c t i o n p r o d u c t s , t o accumulate n u t r i e n t s f o r use d u r i n g u n f a v o u r a b l e c o n d i t i o n s , t o grow i n an oxygen d e f i c i e n t medium and t o s u r v i v e low pH c o n d i t i o n s . The a n a t o m i c a l and m o r p h o l o g i c a l a d a p t a t i o n s found i n p l a n t s a s s o c i a t e d w i t h w a t e r l o g g e d and a n a e r o b i c environments are w e l l and were summarized by A r b e r ( 1 9 2 0 ) .  known  In p a r t i c u l a r the development o f  lacunae and l a r g e i n t e r c e l l u l a r spaces i s f r e q u e n t i n such p l a n t s . A r b e r (1920) demonstrated t h a t such m o r p h o l o g i c a l f e a t u r e s are e s p e c i a l l y developed i n p l a n t s o f s t a g n a n t w a t e r whereas they may not be p r e s e n t a t all  i n s i t u a t i o n s where w a t e r f l o w i s f a s t and oxygen s u p p l y i s  S i f t o n (1945) and S c h o l a n d e r e t aJL  adequate.  (1955) concluded t h a t the r o o t s and  rhizomes o f marsh p l a n t s r e c e i v e t h e i r oxygen from a e r i a l p a r t s through gas spaces c o n n e c t i n g t h e s e o r g a n s . C o u l t and V a l l a n c e (1958) o b s e r v e d t h a t most w e t l a n d p l a n t s do r e l y upon a i r spaces f o r oxygen s u p p l y but t h a t under a n a e r o b i c  conditions  some are a b l e t o reduce t h e i r oxygen demand. I t would appear t h a t r e d u c i n g c o n d i t i o n s may cause an a c c u m u l a t i o n o f t o x i c compounds around the r o o t s and rhizomes o f w e t l a n d p l a n t s hence c a u s i n g i n j u r y t o these o r g a n s .  Ruther (1955) suggested t h a t a  f l u c t u a t i n g w a t e r t a b l e may s e r v e t o remove such t o x i n s .  B a r l e t t (1961)  9  r e p o r t e d t h a t some r e s i s t a n c e t o w a t e r l o g g i n g i s l i n k e d w i t h the c a p a c i t y o f the r o o t s o f w e t l a n d p l a n t s to o x i d i z e the r h i z o s p h e r e , presumably by oxygen t r a n s l o c a t i o n from the s h o o t .  I n e v i t a b l y some o f the oxygen con-  t a i n e d w i t h i n the s u b a e r i a l p a r t s o f such p l a n t s must l e a k i n t o the s u r r o u n d i n g medium and i t i s p o s s i b l e t h a t t h i s l o c a l r a i s i n g o f oxygen p o t e n t i a l c o u l d be o f v a l u e i n r e d u c i n g t o x i c i t y . The r o o t s and rhizomes o f semi-submerged p l a n t s a p p a r e n t l y can r e s p i r e a n a e r o b i c a l l y f o r l o n g p e r i o d s o f time w i t h o u t i n j u r y ( L a i n g 1940). McMannon and C r a w f o r d (1971) c o n s i d e r e d t h a t m o r p h o l o g i c a l  adaptations  o f w e t l a n d p l a n t s were n o t i n themselves adequate t o a c c o u n t f o r to w a t e r l o g g i n g .  tolerance  They showed t h a t lowered oxygen t e n s i o n s had a d i r e c t  e f f e c t upon g l y c o l y t i c and r e s p i r a t o r y m e t a b o l i s m .  They concluded  that  i n s p e c i e s which are i n t o l e r a n t o f f l o o d i n g , g l y c o l y s i s becomes a c c e l e r a t e d and e t h a n o l i s produced under a n a e r o b i c c o n d i t i o n s .  Flood  t o l e r a n t s p e c i e s however have a m e t a b o l i c s w i t c h which d i v e r t s from p r o d u c i n g e t h a n o l to m a l a t e .  O t h e r a d a p t a t i o n s o f p l a n t s to the  w e t l a n d environment have been reviewed by C a n n e l l  2.4  glycolysis  (1977).  D i s t r i b u t i o n o f Wetland F l o r a  In marked c o n t r a s t to many b e t t e r - k n o w n t e r r e s t r i a l p l a n t c o m m u n i t i e s , w e t l a n d v e g e t a t i o n t y p i c a l l y l a c k s f l o r i s t i c d i v e r s i t y and i s dominated by a few g r a s s e s , sedges o r r u s h e s .  often  The same genera and  f r e q u e n t l y the same s p e c i e s may be e n c o u n t e r e d r e p e a t e d l y i n w i d e l y separated geographical regions  (Chapman 1960, J e f f r i e s  r a n g i n g from t r o p i c t o a r c t i c l a t i t u d e s . found wherever w e t l a n d o c c u r s .  1 9 7 7 ) , some  Indeed some w e t l a n d s p e c i e s  are  10 A n o t h e r s t r i k i n g f e a t u r e i s t h a t monotypic communities dominate l a r g e a r e a s .  occasionally  Many members o f the genus Carex o f t e n form dense  monotypic stands along the borders o f l a k e s , streams and bogs.  Floating  sedge mats f r e q u e n t l y invade s m a l l ponds and may f i n a l l y o v e r s p r e a d them c o m p l e t e l y as "sedge meadows", some o f which l a t e r e v o l v e i n t o sphagnum bogs. C o n s i d e r a b l e s p e c i e s d i v e r s i t y may be encountered i n some wetlands such as b r a c k i s h marshes.  The b i o t i c and p h y s i c a l f a c t o r s r e l a t e d to  such f l o r i s t i c d i v e r s i t y i n c l u d e p l a n t c o m p e t i t i o n (Weaver and Clements 1938), t i d e e l e v a t i o n (Adams 1963), w a t e r regime ( H a r r i s and M a r s h a l l 1963, M i l l a r 1969, Mornjo 1969, Jeglum 1971), w a t e r c h e m i s t r y ( S c u l t h o r p e 1 9 6 7 ) , s a l i n i t y (Dodd and Coupland 1966, McNaughton 1966, Mooring e t aJL  1971,  Shea 1 9 7 2 ) , and m i n e r a l n u t r i e n t s (Saebo 1969).  2.5  P r o d u c t i v i t y o f Emergent V e g e t a t i o n  A l a r g e body o f l i t e r a t u r e e x i s t s c o n c e r n i n g s a l t marsh, b r a c k i s h marsh and f r e s h w a t e r marsh p r o d u c t i v i t y e s t i m a t e s .  An e x h a u s t i v e summary  o f the p r o d u c t i o n l i t e r a t u r e would go f a r beyond the scope o f t h i s  study  hence o n l y a few r e l e v a n t f e a t u r e s are r e v i e w e d . The p r i m a r y p r o d u c t i o n o f t i d a l w e t l a n d s has been p u r p o r t e d to be very h i g h (Penfound 1956, Westlake 1963, Odum 1971) and K i r b y and G o s s e l i n k (1976) have r e c e n t l y demonstrated t h a t s a l i n e and b r a c k i s h w e t l a n d p r i m a r y p r o d u c t i o n may be even h i g h e r than p r e v i o u s l y s u s p e c t e d . I t s h o u l d be n o t e d , however, t h a t p r o d u c t i o n can be v e r y low i n swamps and a few o t h e r w e t l a n d types (Muc 1971, Haag 1974).  saline  n B e r n a r d (1973) noted t h a t aboveground s t a n d i n g c r o p o f Carex s p . (sedges) were l o w e r i n g e n e r a l than those o f o t h e r w e t l a n d s p e c i e s such as Typha (Boyd 1970 a , Boyd and Hess 1970), Phragmites  (Pearsall  and Gorham 1956) and G l y c e r i a (Westlake 1971).  These s p e c i e s commonly  have aboveground s t a n d i n g crops o v e r 1,000 g/m  whereas most Carex  wetlands do not reach t h a t  figure.  A l t h o u g h no attempt i s made t o summarize a v a i l a b l e i n f o r m a t i o n on the p r i m a r y p r o d u c t i o n o f w e t l a n d s , a scan through the l i t e r a t u r e shows c o n s i d e r a b l e v a r i a t i o n i n s t a n d i n g crops between d i f f e r e n t systems even w i t h i n a g i v e n c l i m a t i c a r e a .  V a r i a t i o n s i n p r o d u c t i v i t y have been  a t t r i b u t e d l a r g e l y t o unique e n v i r o n m e n t a l f a c t o r s t o which the w e t l a n d s p e c i e s are s u b j e c t e d .  The g e n e r a l l y h i g h p r o d u c t i v i t y o f t i d a l marshes  may be a t t r i b u t e d t o s e v e r a l f a c t o r s .  Odum (1961) s t r e s s e s h i g h n u t r i e n t  s t a t u s as a major f a c t o r ; t i d a l a c t i o n o f t e n s u p p l y i n g l a r g e q u a n t i t i e s o f n u t r i e n t s and oxygen w h i l e the marsh a c t s as a " t r a p " f o r these components.  Reader (1978) a l s o showed t h a t the a v a i l a b i l i t y o f m i n e r a l  n u t r i e n t s i n w e t l a n d s u b s t r a t e s may, i n the m a i n , be r e s p o n s i b l e v a r i a t i o n s i n s t a n d i n g crops o f d i f f e r e n t  for  stands.  The h i g h e r p r i m a r y p r o d u c t i v i t y a s s o c i a t e d w i t h reed swamps ( e . g . Typha and Phragmites s t a n d s ) compared t o Carex wetlands has been a t t r i b u t e d to h i g h e r s i l t a t i o n r a t e s ( B e r n a r d 1973), the i n c r e a s e d presumably i n c r e a s i n g the n u t r i e n t i n p u t .  siltation  Water d e p t h , d u r a t i o n and  r e g u l a r i t y o f i n u n d a t i o n have a l s o been r e l a t e d t o the s u p p l y o f (Gorham 1957, V a l i e l a e t al_. 1975).  nutrients  12 B e r n a r d (1973) compared the p r o d u c t i v i t y o f Carex w e t l a n d s  from  v a r i o u s l a t i t u d e s and a l t i t u d e s and found t h a t those a t h i g h l a t i t u d e s and h i g h e l e v a t i o n s had s t a n d i n g crops l e s s than 300 g/m  while  a t lower and more s o u t h e r l y s i t e s produced o v e r 1,000 g/m .  those  Gorham  (1974) c o n t i n u e d a n a l y z i n g such r e l a t i o n s h i p s and c o r r e l a t e d s t a n d i n g crop w i t h summer t e m p e r a t u r e , p a r t i c u l a r l y the h i g h e s t monthly mean temperature.  S i m i l a r l a t i t u d i n a l e f f e c t s on s t a n d i n g c r o p have been  r e p o r t e d by Keefe ( 1 9 7 2 ) , Cooper ( 1 9 7 4 ) , H a t c h e r and Mann ( 1 9 7 5 ) .  The  n o r t h - s o u t h g r a d i e n t i n w e t l a n d p r o d u c t i o n appears t o be c l o s e l y c o r r e l a t e d w i t h those f a c t o r s which measurements o f l a t i t u d e  integrate,  e s p e c i a l l y t e m p e r a t u r e and s u n l i g h t (Bray and Gorham 1964, Fogg 1973). However, Nixon and O v i a t t (1973) c a u t i o n t h a t the apparent d e c l i n e  in  p r o d u c t i o n a t h i g h e r a l t i t u d e s and l a t i t u d e s i s n e i t h e r as sharp nor as c l e a r as o f t e n i m p l i e d i n the l i t e r a t u r e .  2.6  The Animal F a c t o r i n Wetlands  A l t h o u g h the work r e p o r t e d i n t h i s t h e s i s emphasized p l a n t p r o c e s s e s , the animal f a c t o r cannot be i g n o r e d i n view o f t h e i r i n t e r r e l a t i o n s h i p s . Animals f u n c t i o n i n w e t l a n d systems i n much the same way as they do i n o t h e r ecosystems.  They f u n c t i o n as g r a z e r s ( S m a l l e y 1959, McLean and  T i s d a l e 1960, T e a l 1962).  Considerable q u a n t i t i e s o f wetland vegetation  may be g r a z e d e s p e c i a l l y by i n s e c t h e r b i v o r e s ( S m a l l e y 1960).  Many  animals a l s o f u n c t i o n i n p o l l i n a t i o n and d i s p e r s a l o f w e t l a n d p l a n t s . T h e i r r o l e i n comminution, s u b s t r a t e t u r n o v e r and d e t r i t a l was emphasized by MacFadyen  (1961).  formations  13 An i n t r o d u c t o r y statement on the e x t e n t and v a l u e o f the w e t l a n d s o f B r i t i s h Columbia was g i v e n a t a symposium h e l d i n D e l t a o f B r i t i s h Columbia Wetland Seminar, 1975).  (Proceedings  Some o f the wetlands  p r o v i d e s h e l t e r and food f o r d i f f e r e n t c a t e g o r i e s o f r e s i d e n t and m i g r a t o r y b i r d s ( B a r n a r d 1975, Burgess 1970).  I t i s now b e l i e v e d ,  a l t h o u g h not y e t documented, t h a t i n i n d i r e c t ways, the B r i t i s h Columbia c o a s t a l emergent communities p l a y a s i g n i f i c a n t r o l e i n the f e e d i n g salmon w h i l e some o f them a c t as egg beds f o r o t h e r f i s h e s .  of  The  v e g e t a t i o n i s a l s o u t i l i z e d to v a r y i n g degrees by l a r g e u n g u l a t e s  such  as d e e r , moose, e l k , beaver and m u s k r a t . The i n f l u e n c e o f human a c t i v i t y on w e t l a n d systems cannot be o v e r emphasized.  The s u b j e c t i s too d i v e r s e and c o n t r o v e r s i a l t o  d e t a i l e d treatment i n a t r e a t i s e o f t h i s k i n d . few human a c t i v i t i e s w i l l  be c i t e d h e r e .  receive  Consequently, only a  C a n a l i z a t i o n , whether  for  gas o r o i l e x p l o r a t i o n , i s f r e q u e n t l y accompanied by f r e s h e n i n g water areas o r b r i n g i n g s a l t i n t o f r e s h water a r e a s , thus the c o m p o s i t i o n o f the v e g e t a t i o n t h e r e i n .  salt  changing  Drainage can change  w e t l a n d i n t o m o d i f i e d h y d r i c communities where d r a i n a g e i s  imperfect  o r t o t e r r e s t r i a l communities o r f a r m l a n d s where d r a i n a g e i s more o r l e s s complete.  In some w e t l a n d s , sewage e f f l u e n t s may be s i g n i f i c a n t ,  c o n t r i b u t i n g a v a r i e t y of n u t r i e n t s .  The n u t r i e n t s may promote  l u x u r i a n t growth o f v e g e t a t i o n a l t h o u g h t o x i c f r a c t i o n s may i n o t h e r s i t u a t i o n s eliminate other species  ( V a l i e l a a n d Teal  1976).  Wetlands i n B r i t i s h C o l u m b i a , a l t h o u g h e x t e n s i v e , have been a l i e n a t e d f o r a m u l t i t u d e o f purposes and w i t h a s t o n i s h i n g ( N o r t h c o t e 1974).  rapidity  S i n c e the days o f f i r s t dyke c o n s t r u c t i o n i n the  14  1870's much o f the w e t l a n d has been o c c u p i e d by s u b u r b i a and i n d u s t r y and now human a c t i v i t i e s o f many k i n d s are e x t e n d i n g a t an i n c r e a s i n g l y rapid rate.  Becker (1971) and Hoos and Packman (1974) have g e n e r a l l y  r e v i e w e d the a c t i v i t i e s i n s p e c i f i c c o n t e x t s and i n d i c a t e d t h e i r p a t t e r n s o f change.  current  The n a t u r e o f the problem was a l s o e x t e n s i v e l y  d i s c u s s e d a t the B. C. Wetland Seminar ( 1 9 7 5 ) . Wetland p l a n t s are o f t e n h a r v e s t e d by man and conserved f o r a l t h o u g h the f o r a g e i s o f t e n o f low n u t r i t i o n a l q u a l i t y .  forage  Other d i r e c t  uses o f w e t l a n d p l a n t s by man, such as c r a f t , m e d i c i n e , f u e l and p u l p , have been v a r i o u s l y r e v i e w e d i n E s t u a r i n e P r o c e s s e s , V o l . 1 ( 1 9 7 6 ) .  2.7  The D i s p o s i t i o n o f Wetland V e g e t a t i o n  I t i s w i d e l y a c c e p t e d t h a t energy e n t e r s most ecosystems through the p r o c e s s o f p h o t o s y n t h e s i s which u l t i m a t e l y leads t o a b u i l d - u p of plant m a t e r i a l .  T h i s m a t e r i a l may be consumed by h e r b i v o r e s o r  it  may d i e and pass through what i s termed the "decomposer" food c h a i n . In most ecosystems the f a t e o f m a t e r i a l e n t e r i n g t h i s pathway i s t o be broken down and r e s p i r e d by t h e r e s i d e n t b i o t a u n t i l dissipated.  i t is  completely  However, many w e t l a n d s have a decomposer food c h a i n which  i s i m p a i r e d as a r e s u l t o f extreme p h y s i c a l c o n d i t i o n s such as wetness and a n a e r o b o s i s l e a d i n g t o a c c u m u l a t i o n o f undecomposed p l a n t m a t e r i a l .  2.7.1  The g r a z i n g pathway  G r a z i n g o f w e t l a n d v e g e t a t i o n was b r i e f l y d i s c u s s e d under s e c t i o n 2.6.  The g r a z e r s o f l i v i n g v e g e t a t i o n range from l a r g e n a t i v e  ungulates  15 such as deer o r d o m e s t i c l i v e s t o c k to s m a l l f a u n a l communities such as a r t h r o p o d s .  A l t h o u g h some w e t l a n d s a r e i n t e n s i v e l y g r a z e d ,  it  appears t h a t i n many w e t l a n d s y s t e m s , e s p e c i a l l y c o a s t a l marshes, g r a z i n g removes o n l y a s m a l l f r a c t i o n o f t h e i r p r i m a r y p r o d u c t i o n . S m a l l e y (1959) found d i r e c t g r a z i n g i n a marsh system t o be l e s s than 5 p e r c e n t .  Teal (1962) r e p o r t e d t h a t the major energy f l o w  between a u t o t r o p h i c and h e t e r o t r o p h i c l e v e l s on a w e t l a n d was by way o f the d e t r i t a l food c h a i n r a t h e r than the g r a z i n g food c h a i n .  In  G e o r g i a e s t u a r i e s dominated by S p a r t i n a a l t e r n i f l o r a , Odum and de l a Cruz (1967) found o r g a n i c m a t t e r to be the c h i e f l i n k  between  p r i m a r y and secondary p r o d u c t i o n because the g r a s s was o n l y m i n i m a l l y g r a z e d w h i l e i t was  living.  The reasons f o r the m i n i m a l g r a z i n g o f some w e t l a n d emergent communities have s c a r c e l y been e x p l o r e d .  From s t u d i e s o f o t h e r  e c o s y s t e m s , the main p l a n t f a c t o r s a f f e c t i n g g r a z i n g use o f v e g e t a t i o n are now more o r l e s s w e l l  living  defined.  M a r t z ejt aj_. (1967) acknowledged t h a t the chemical of plants affects t h e i r p a l a t a b i l i t y .  composition  Heady (1964) reviewed s e v e r a l  papers i n which the i n v e s t i g a t o r s concluded t h a t t o t a l n u t r i t i v e v a l u e was the b e s t i n d i c a t o r o f p a l a t a b i l i t y .  The m a t e r i a l s s e l e c t e d were  u s u a l l y h i g h e r i n g r o s s energy (Cook e_t al_. 1956), n i t r o g e n (Heady 1964), sugars and s o l u b l e c a r b o h y d r a t e s ( R e i d e t al_. 1967) and lower i n wall constituents  cell  ( R e i d et_ al_. 1967) compared to the m a t e r i a l r e j e c t e d .  However, animal p r e f e r e n c e s cannot e a s i l y be a t t r i b u t e d t o s i m p l e c o n s t i t u e n t s such as these and the l i t e r a t u r e on t h i s s u b j e c t i s  plant rather  16 confusing.  F o r i n s t a n c e , R e i d e t al_. (1967) noted s i g n i f i c a n t  positive  c o r r e l a t i o n s between p r e f e r e n c e r a t i n g and s o l u b l e c a r b o h y d r a t e in orchardgrass. in t a l l  fescue.  content  R e i d and Jung (1965) d i d not f i n d any such c o r r e l a t i o n s B l a n d and Dent (1964) compared the p r e f e r e n c e s  of  c a t t l e amongst 14 s t r a i n s o f o r c h a r d g r a s s a t s e v e r a l l o c a t i o n s .  A t one  s i t e , p r e f e r e n c e s were most c o r r e l a t e d w i t h p e r c e n t t o t a l sugars a l t h o u g h not w i t h s u c r o s e c o n t e n t .  At a l l other l o c a t i o n s , t o t a l  c o n t e n t and p r e f e r e n c e were not r e l a t e d .  A r n o l d and H i l l  sugar  (1972) s t a t e d  t h a t i t i s h i g h l y u n l i k e l y t h a t an animal c o u l d g i v e an i n t e g r a t e d response t o s o l u b l e c a r b o h y d r a t e s .  What t h i s f r a c t i o n i n c l u d e s  depends  not o n l y on the p a r t i c u l a r c a r b o h y d r a t e p r e s e n t i n the p l a n t under c o n s i d e r a t i o n but a l s o on the methods by which they are e x t r a c t e d and determined. A s u b s t a n t i a l l i t e r a t u r e has been a c c u m u l a t i n g t o i m p l i c a t e many p l a n t secondary s u b s t a n c e s as a n t i b i o t i c agents i n e c o l o g i c a l a c t i o n s between p l a n t s and t h e i r a s s o c i a t e d b i o t a .  inter-  In terms o f  plant-  h e r b i v o r e i n t e r a c t i o n s , secondary substances t h a t have been shown e i t h e r t o have a n e g a t i v e e f f e c t on h e r b i v o r e f i t n e s s  (e.g. increased m o r t a l i t y ,  lower growth r a t e s ) o r t o have d e t e r r e n t e f f e c t on h e r b i v o r e g r a z i n g i n c l u d e a l k a l o i d s (Parmer and B r i n k 1976), e s t r o g e n i c compounds  (Biely  and K i t t s 1964), cyanogenic g l y c o s i d e s (Jones 1 9 7 2 ) , t a n n i n and o t h e r p h e n o l i c compounds (Feeny 1970, D o n n e l l y and Anthony 1970).  Although  i n o t h e r i n v e s t i g a t i o n s some o f t h e s e s u b s t a n c e s have been found t o e x h i b i t no e f f e c t on h e r b i v o r e g r a z i n g p a t t e r n s , i t i s r e a s o n a b l e  to  assume t h a t secondary substances must o f f e r some form of defense to the  17 plant.  I f they d i d n o t , then t h e m e t a b o l i c c o s t s a s s o c i a t e d w i t h  t h e i r p r o d u c t i o n s h o u l d cause the e l i m i n a t i o n o f genotypes  producing  t h e s e substances from t h e p l a n t p o p u l a t i o n . Morphological  c h a r a c t e r i s t i c s o f p l a n t s seem t o be a s s o c i a t e d  some cases w i t h t h e i r a c c e p t a b i l i t y t o h e r b i v o r e s .  Craigmiles et a l .  (1964) r e c o r d e d a low but s i g n i f i c a n t c o r r e l a t i o n between l e a f and p a l a t a b i l i t y i n t a l l f e s c u e .  in  texture  Judas H e c a r t (1965) a l s o r e p o r t e d a  p o s i t i v e r e l a t i o n s h i p between l e a f f l e x i b i l i t y and p a l a t a b i l i t y i n the same g r a s s .  A b s o l u t e s i z e o f the t r a n s v e r s e s e c t i o n o f the v a s c u l a r  bundles was s t r o n g l y r e l a t e d to f l e x i b i l i t y which a l s o a f f e c t e d ability.  accept-  A c c o r d i n g t o Heady ( 1 9 6 4 ) , p r e f e r e n c e f o r s p e c i f i c p l a n t s may  a l s o be r e l a t e d to the presence o f awns, s p i n e s , h a i r i n e s s ,  stickiness  and t e x t u r e . A v a i l a b i l i t y o f p l a n t s t o h e r b i v o r e s can be a f f e c t e d by the e n v i r o n m e n t a l c o n d i t i o n s o f the h a b i t a t .  P l a n t communities growing  i n a c c e s s i b l e areas a r e not l i k e l y t o be g r a z e d to any c o n s i d e r a b l e  in degree.  The importance o f t o p o g r a p h i c a l and p h y s i c a l f e a t u r e s o f the h a b i t a t  in  r e l a t i o n t o a v a i l a b i l i t y of p l a n t s t o h e r b i v o r e s was emphasized by Hercus  (1961).  The e x t e n t to which each o f the above p l a n t f a c t o r s c o n t r i b u t e s  to  a v a i l a b i l i t y and a c c e p t a b i l i t y o f w e t l a n d p l a n t s by h e r b i v o r e s has h a r d l y been e x p l o r e d .  Odum e t al_. (1972) c o n c l u d e d t h a t the l a r g e amounts o f  s t r u c t u r a l t i s s u e s ( l i g n i n and c e l l u l o s e ) i n many c o a s t a l emergent s p e c i e s make them u n p a l a b l e to g r a z e r s .  H a r r i s o n and Mann (1975) observed t h a t  the h i g h C : N r a t i o o f a q u a t i c e e l g r a s s ( Z o s t e r a s p . ) , g r e a t e r than 20 : 1, made i t a v e r y poor d i r e c t f o o d s o u r c e (17 :1 b e i n g the maximum f o r an adequate d i e t , R u s s e l l - Hunter 1970).  18  2.7.2  Detrital  pathway  A l a r g e p r o p o r t i o n o f the t o t a l m a t t e r produced i n w e t l a n d systems may pass through the d e t r i t a l pathway; the term d e t r i t u s b e i n g w i d e l y a c c e p t e d as meaning n o n - l i v i n g p l a n t o r animal remains and the associated microflora.  D e t r i t a l p r o c e s s e s i n v o l v e the breakdown o f  dead p l a n t m a t e r i a l by v a r i o u s p h y s i c a l , chemical and b i o l o g i c a l  forces  into progressively smaller pieces. Wave a c t i o n , t i d a l  c u r r e n t s and f r e e z i n g and thawing would c e r t a i n l y  be i m p o r t a n t i n d e t a c h i n g and f r a g m e n t i n g l a r g e p i e c e s o f w e t l a n d p l a n t s . H a r r i s o n and Mann (1975) observed t h a t m i c r o b i a l a c t i v i t y and l e a c h i n g r a t e s were i n c r e a s e d as mechanical a c t i o n reduced the s i z e o f (Zostera sp.) leaves.  eelgrass  Small p a r t i c l e s u s u a l l y have h i g h e r s u r f a c e a r e a  f o r c o l o n i z a t i o n by m i c r o o r g a n i s m s . Upon death o f the p l a n t , t h e r e are r a p i d chemical changes, i n which s o l u b i l i z a t i o n and a u t o l y s i s may be o f some i m p o r t a n c e .  Odum e t a l .  (1972) have summarized these d e g r a d a t i o n p r o c e s s e s f o r marsh v e g e t a t i o n . The m a t e r i a l l e a c h e d i s i n the form o f v e r y l a b i l e compounds  (sugars,  s t a r c h e s , o r g a n i c a c i d s , e t c . ) and appears t o be r e a d i l y and r a p i d l y u t i l i z e d by marsh organisms ( G a l l a g h e r e t al_. 1976).  Once the o r g a n i c  compounds e n t e r i n t o s o l u t i o n , t h e r e i s a r a p i d i n c r e a s e i n the a s s o c i a t e d b a c t e r i a and f u n g i as the v a r i o u s p l a n t components become available for degradation. Except f o r the h i g h energy i n t e r t i d a l marshes, i t appears biological  d e g r a d a t i o n i s the main agent i n p l a n t  fragmentation  that  19 ( B u r k h o l d e r and B r o n s i d e 1957, G o s s e n l i n k and K i r b y 1974).  Biological  d e g r a d a t i o n i n v o l v e s a wide range o f organisms which s u b j e c t the dead v e g e t a t i o n t o a whole s u c c e s s i o n o f p r o c e s s e s such as comminution, m i x i n g w i t h m i n e r a l m a t t e r and changes i n the p h y s i c a l s t r u c t u r e o f the organic debris. The r o l e o f i n v e r t e b r a t e d e t r i t o v o r e s i n the mechanical o f dead v e g e t a t i o n was emphasized by Fenchel ( 1 9 7 0 ) .  breakdown  He noted t h a t  the  a c t i v i t y o f the i n v e r t e b r a t e s c o n t r i b u t e d more t o community r e s p i r a t i o n than t o the m e t a b o l i c a c t i v i t y o f the i n v e r t e b r a t e s t h e m s e l v e s .  It  is  a l s o known t h a t f e c a l m a t e r i a l from t h e s e i n v e r t e b r a t e s p r o v i d e s a l a r g e s u r f a c e a r e a f o r m i c r o b i a l c o l o n i z a t i o n which i n t u r n enhances  the  d e c o m p o s i t i o n o f p a r t i c u l a t e o r g a n i c m a t t e r i n the e n v i r o n m e n t .  A t the  same time r e c o l o n i z e d f e c a l m a t t e r can be u t i l i z e d by " d e p o s i t "  feeding  i n v e r t e b r a t e s t h e r e b y enhancing t h e i r food s u p p l y (Hargrave 1975). Engelman (1961, 1968) d i s c u s s e d the importance o f d i g e s t i o n and e g e s t i o n i n s o i l a r t h r o p o d communities and p r e s e n t e d a community model having a w e l l i n t e g r a t e d d e t r i t a l component t o emphasize the r e c u p e r a t i v e n a t u r e o f d e t r i t a l food c h a i n s i n which the t r a n s f e r o f m a t t e r and energy i s p r i m a r i l y through s u c c e s s i v e consumption o f the egested m a t e r i a l . M i c r o b i a l d e c o m p o s i t i o n o f w e t l a n d p l a n t s i s by f a r the most complex d e g r a d a t i o n mechanism.  As a decomposer m i c r o f l o r a begins t o  colonize  the dead p l a n t , i t p l a y s a dual r o l e as a f o o d s o u r c e f o r many d e t r i t o v o r e s and as an agent f o r the b i o g e o c h e m i c a l r e c y c l i n g o f elements i n the e c o s y s t e m .  Both b a c t e r i a and f u n g i p l a y an i m p o r t a n t r o l e i n the  degradation of plant m a t e r i a l .  M o r r i s o n e t al_. (1977) have shown t h a t  20  the i n i t i a l s u r f a c e m i c r o f l o r a i s t y p i c a l l y dominated by b a c t e r i a , and, i n t i m e , d i l u t e d by f u n g i , a l g a e and o t h e r more complex o r g a n i s m s . H e t e r o t r o p h i c a c t i v i t y can be a p p r e c i a b l y i n f l u e n c e d by m i c r o f l o r a l s u c c e s s i o n , p a r t i c u l a r l y d u r i n g major s h i t s i n type and number o f organisms.  As the m i c r o b i a l - d e t r i t a l complex matures and protozoans  and m i c r o i n v e r t e b r a t e s appear, m i n e r a l i z a t i o n r a t e s o f ,  f o r example,  phosphorus ( B a r s d a t e e t al_. 1972) and carbon (Fenchel 1970) i n c r e a s e significantly. I t appears t h a t the p r o c e s s e s a s s o c i a t e d w i t h b i o l o g i c a l  degradation  i n v a r i a b l y r e s u l t i n a p r o t e i n e n r i c h m e n t o f the o r g a n i c d e t r i t u s presumably by c o n v e r s i o n o f low p r o t e i n p l a n t t i s s u e t o high m i c r o b i a l biomass.  protein  Odum and de l a C r u z ( 1 9 6 7 ) , Kaushik and Hynes  de l a Cruz and G a b r i e l  (1971),  (1974) and de l a Cruz (1975) r e p o r t e d an ash f r e e  crude p r o t e i n range o f 5 t o 24 p e r c e n t o f p a r t i a l l y decomposed and p a r ticulate detritus.  The d e g r a d a t i o n o f p l a n t m a t e r i a l t o s u b p a r t i c u l a t e  forms t o g e t h e r w i t h the p r o t e i n enrichment are g e n e r a l l y c o n s i d e r e d to be the main l i n k i n the food c h a i n between w e t l a n d f l o r a and t h e i r  associated  and f r e q u e n t l y abundant secondary consumers ( B u r k h o l d e r and B o r n s i d e 1957, Odum and de l a Cruz 1967, de l a Cruz 1975).  Odum (1971) c o n s i d e r e d  m i c r o o r g a n i s m s t h e p r i m a r y consumers i n such d e t r i t u s - b a s e d s y s t e m s .  2.7.3  A c c u m u l a t i o n pathway  A c c u m u l a t i o n o f dead v e g e t a t i o n appears t o be a common f e a t u r e  of  some wetlands e s p e c i a l l y where c o n d i t i o n s do not f a v o u r r a p i d decomposi t i o n , t r a n s p o r t a t i o n t o o t h e r h a b i t a t s o r where o x i d a t i o n p r o c e s s e s such as f i r e are uncommon.  I f d e c o m p o s i t i o n and/or t r a n s p o r t a t i o n r a t e  21 f a i l s t o keep pace w i t h dry m a t t e r p r o d u c t i o n , then peat and s i m i l a r o r g a n i c m a t t e r w i l l be formed. accumulation w i l l  The r a t e o f peat f o r m a t i o n and  depend upon the r a t i o o f dry m a t t e r p r o d u c t i o n and  removal.  Peat a c c u m u l a t i o n i n any system i s a slow and c o m p l i c a t e d  process.  Walker (1970) gave an average f i g u r e t o be i n t h e o r d e r o f  20 t o 80 cm i n 1,000 y e a r s .  Cameron (1970) has accumulated some data  on peat f o r m a t i o n i n North A m e r i c a .  He r e p o r t e d bog growth v a l u e s o f  the o r d e r o f 100 t o 200 cm i n 1,000 y e a r s i n some w e t l a n d s o f Canada and the U n i t e d S t a t e s .  A c o n s i d e r a b l e amount o f energy from p r i m a r y  p r o d u c t i o n remains s t o r e d up i n the peat and p e a t - l i k e m a t e r i a l s . T h i s s t o r a g e o f r e s e r v e energy by w e t l a n d systems i s o f  considerable  importance s i n c e such " f o s s i l " energy can be tapped by man and r e l e a s e d i n combustion.  22 3.  GENERAL DESCRIPTION OF THE STUDY AREAS, SUBSTRATES AND SPECIES  B r i t i s h C o l u m b i a ' s wetlands c o n s t i t u t e an i m p o r t a n t percentage o f the p r o v i n c i a l l a n d base.  D i f f e r e n t forms o f w e t l a n d are  encountered throughout the P r o v i n c e depending on e l e v a t i o n , c l i m a t e , s o i l t y p e , n u t r i e n t l e v e l s , water t u r b i d i t y , t e m p e r a t u r e , and g e n e r a l h y d r o l o g i c regime o f the w a t e r s h e d s .  circulation  In 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 , they range from b r a c k i s h c o a s t a l marshes and i n t e r tidal  lands t o f r e s h water meadows and f i e l d d e p r e s s i o n s .  " B e f o r e the  advent o f w h i t e man, much o f the lower F r a s e r v a l l e y was w e t l a n d . " ( N o r t h c o t e , 1974).  Dykes have g r e a t l y reduced the w e t l a n d a r e a s ;  w i t h o u t d y k i n g , t h e r e i s l i t t l e doubt they s h o u l d s t i l l  be n e a r l y as  wet as those areas which are now l y i n g o u t s i d e of the d y k i n g s y s t e m s . The s i t e s chosen f o r study ( F i g u r e 3.1) a l t h o u g h not  truly  r e p r e s e n t a t i v e , are t y p i c a l l y r e l a t e d to wetlands of the e a s t c o a s t o f Vancouver I s l a n d and a l s o to the c o a s t a l w e t l a n d s o f Washington and Oregon.  3.1  T i d a l Marshes o f the F r a s e r  Foreshore  On the b a s i s o f s e v e r a l s t u d i e s commissioned by the F e d e r a l Government (Hoos and Packman, 1 9 7 4 ) , the F r a s e r d e l t a was proposed to be comprised o f the a l l u v i a l lowlands l y i n g west o f New Westminster and between the North Arm o f the F r a s e r r i v e r and Boundary Bay.  This  2 area i s e s t i m a t e d t o be a p p r o x i m a t e l y 337 km  and almost a l l o f i t  e i t h e r d y k e d , o r above the i n f l u e n c e o f the t i d e .  is  I t s h o u l d be noted  however, t h a t l a r g e areas o f the a l l u v i u m o f " r a i s e d " and low l e v e l  F i g u r e 3.1:  Map showing L o c a t i o n o f the Study A r e a s .  I SITED STATES O l AMERICA  ,  I2J CO  4 ;  25 l a n d b e l o n g i n g to the F r a s e r system a l s o o c c u r s e a s t o f New Westminster and t h a t the system i s t i d a l as f a r as H a r r i s o n r i v e r and l a k e . T i d a l marshes e x i s t a l o n g the seaward edge o f the F r a s e r d e l t a , from the Vancouver mainland j u s t n o r t h o f Sea I s l a n d to the Tsawassen causeway.  In the main arm o f the F r a s e r , above Westham I s l a n d ,  tidal  marshes cover most o f Duck, B a r b e r and Woodward I s l a n d s , as w e l l Ladner marsh.  as  A few narrow f r i n g e s o f t i d a l marsh remain upstream  o f Ladner i n Deas, C r e s c e n t and o t h e r s l o u g h s .  The c o a s t l i n e o f  Boundary Bay a l s o s u p p o r t s a f r i n g e o f t i d a l marsh from Beach Grove t o C r e s c e n t Beach.  The t o t a l t i d a l marsh a r e a of the F r a s e r r i v e r -  f o r e s h o r e i s e s t i m a t e d to be around 27 km  (Yamanaka, 1975).  The c l i m a t e o f t i d a l marshes f a l l w i t h i n the g e n e r a l  category  o f the west c o a s t marine t y p e , w i t h m i l d w i n t e r s (mean J a n u a r y temperature 2-7°  C ) , warm summers (mean J u l y temperature 16° C) and  annual average p r e c i p i t a t i o n o f about 1,000 mm. An e x c e l l e n t summary o f the geology o f the F r a s e r r i v e r d e l t a  is  g i v e n by L u t e r n a u e r (Hoos and Packman, 1974). Our study s i t e s were l o c a t e d a t Brunswick P o i n t and Iona I s l a n d . The v e g e t a t i o n o f Brunswick P o i n t and Iona I s l a n d i s o f b r a c k i s h t i d a l marshes.  representative  Both s i t e s a r e s i t u a t e d on the  interface  o f f r e s h water from the F r a s e r r i v e r , and the s a l t w a t e r wedges from the S t r a i t o f G e o r g i a .  Hence the v e g e t a t i o n not o n l y e x h i b i t s a  h o r i z o n t a l z o n a t i o n which i s m a i n l y i n f l u e n c e d by t i d a l  exposure,  but a l s o a g r a d a t i o n from b r a c k i s h t o marine water ( F i g u r e  3.2).  The major v e g e t a t i o n types have been d e s c r i b e d i n g e n e r a l terms by Burgess ( 1 9 7 0 ) , Forbes ( 1 9 7 2 ) , McLaren ( 1 9 7 2 ) , Hoos and Packman ( 1 9 7 4 ) ,  26  Figure 3.2:  Photographs showing Emergent Communities i n the Brunswick marsh (Summer 1 9 7 7 ) .  Top photo:  Carex l y n g b y e i i n f l o w e r .  Note t h a t  f l o w e r i n g time was c o n s p i c u o u s l y  related  to r e l a t i v e e l e v a t i o n s o f t h e s u b s t r a t e ; e a r l i e s t f l o w e r i n g o c c u r r e d on t h e  slightly  elevated substrates. Bottom photo:  Carex l y n g b y e i i n f o r e g r o u n d ; f r e s h e t and a s s o c i a t e d s i l t  deposit.  channel  photographs for page 27 are missing  28 Yamanaka (1975) and Moody ( 1 9 7 8 ) . m a r i t i m u s L.,  Common dominants are S c i r p u s  and Carex l y n g b y e i Horneum.  Other s p e c i e s common to  the a r e a , but which u s u a l l y o c c u r i n p a t c h e s , i n c l u d e T r i g l o c h i n • m a r i t i m a L.,  Typha l a t i f o l i a L.,  Juncus b a l t i c u s W i l l d . , S c i r p u s  v a l i d u s V a h l . and S a l i c o r n i a v i r g i n i c a  L.  D e s c r i p t i o n s o f the v e r t e b r a t e and i n v e r t e b r a t e fauna of w e t l a n d s a r e being assembled by Westwater Research C e n t r e  the  (University  of B r i t i s h C o l u m b i a ) , by The Canadian W i l d l i f e S e r v i c e ( A l a k s e n ) and by the P a c i f i c Environment I n s t i t u t e ( F i s h e r i e s and Management S e r v i c e , West V a n c o u v e r ) .  3.2  Fresh Water Marshes - P i t t Meadows  P i t t Meadows are about 45 km e a s t o f the c i t y o f Vancouver. g r e a t e r p a r t o f the l a n d i s dyked a g a i n s t f l o o d s from the P i t t , and F r a s e r r i v e r s .  A Alouette  The c l i m a t e , s o i l s , v e g e t a t i o n and fauna o f the a r e a  were e x t e n s i v e l y d e s c r i b e d by Barnard ( 1 9 7 5 ) . B r i e f l y , the s o i l s a r e a c i d i c g l e y s o l s having s i l t y c l a y loam to c l a y loam p a r e n t m a t e r i a l .  The w a t e r t a b l e r i s e s w i t h  considerable  freedom d u r i n g the wet months and i s high through May and J u n e , when the F r a s e r r i v e r f r e s h e t p e a k s .  The v e g e t a t i o n o c c u r s i n stands o f  both p u r i t y and c o n s i d e r a b l e d i v e r s i t y ( F i g u r e 3 . 3 ) . s p e c i e s i n c l u d e P h a l a r i s a r u n d i n a c e a L.,  The dominant  C a l a m a g r o s t i s canadensis  ( M i c h x . ) B e a v . , Carex r o s t r a t a S t o k e s , S c i r p u s acutus M u h l . , Juncus e f f u s u s L.  and Equisetum spp.  29  Figure 3.3:  Photographs showing Emergent S p e c i e s i n the P i t t marsh, S p r i n g 1978.  Top photo:  Calamagrostis canadensis i n foreground; Carex s i t c h e r i s i s , S c i r p u s c y p e r i n u s  in  midground. Bottom photo:  Emergent communities o u t s i d e d y k e , w i t h P h a l a r i s a r u n d i n a c e a on dyke s l o p e s .  30  31 3.3  Upland S i t e s  A few d r y l a n d s i t e s were s t u d i e d f o r comparison w i t h the w e t l a n d habitats.  Most o f them were l o c a t e d on areas sometimes d e s i g n a t e d as  "old f i e l d "  i.e.  a r a b l e l a n d t h a t has been l e f t r e l a t i v e l y unmanaged  f o r a few y e a r s . U n i v e r s i t y o f B r i t i s h Columbia Farm i s l o c a t e d on g l a c i a l and outwash about 100 meters above sea l e v e l . maritime.  till  The c l i m a t e i s humid-  The s o i l s are w e l l d r a i n e d , s l i g h t l y a c i d i c and, a t one  time, supported climax coniferous f o r e s t .  The f i e l d s have been  f r e q u e n t l y plowed. C o l o n y Farm i s about 15 km e a s t o f the c i t y o f Vancouver.  It  i s a P r o v i n c i a l Government d a i r y f a r m , w i t h major h e c t a r a g e e s t a b l i s h e d t o hay and p a s t u r e .  The D a c t y l i s g l o m e r a t a s i t e chosen f o r t h i s  study  i s i n t e n s i v e l y managed and r e c e i v e s f e r t i l i z e r and manure a n n u a l l y . The P h a l a r i s a r u n d i n a c e a s i t e chosen f o r the study i s l o c a t e d on mixed f i n e and coarse s o i l s which are r a r e l y d i s t u r b e d , e x c e p t f o r s p r i n g and f a l l  occasional  f i r i n g o f the dead p l a n t m a t e r i a l .  A l a k s e n N a t i o n a l W i l d l i f e Refuge Farm i s on a l l u v i u m s u b s t r a t e of the F r a s e r d e l t a f o r e s h o r e , a s u b s t r a t e s i m i l a r to t h a t o f Brunswick and Iona marshes.  The a r e a i s w e l l dyked and managed p r i m a r i l y f o r w a t e r f o w l .  Most o f i t i s e s t a b l i s h e d to p a s t u r e g r a s s e s and legumes such as Phleum p r a t e n s e L.  ( t i m o t h y ) , L o l i u m perenne L.  T r i f o l i u m repens L.  (white c l o v e r )  ( p e r e n n i a l rye g r a s s ) , and  (Figure 3.4).  32  F i g u r e 3.4:  Photographs showing Loliurn perenne - Agropyron repens s t a n d a t A l a k s e n dyked a r a b l e o l d f i e l d .  As a r e s u l t  o f g r a z i n g o f top and rhizome by n a t i v e geese and widgeon i n one s e a s o n , a l m o s t a l l and r e p l a c e d by A g r o p y r o n .  the L o l i u m was removed  33  34 3.4  A t t r i b u t e s o f Some o f the S i t e S u b s t r a t e s  I t has been i n d i c a t e d t h a t a g r e a t d i v e r s i t y e x i s t s , o f t e n o v e r v e r y s h o r t d i s t a n c e s , i n the p h y s i c a l , chemical and b i o l o g i c a l o f B r i t i s h Columbia w e t l a n d s .  nature  R a t h e r than r e l y e x c l u s i v e l y on s u b -  j e c t i v e s i t e d e s c r i p t i o n s , we f e l t t h a t a p r e s e n t a t i o n o f s u b s t r a t e d e s c r i p t i o n i n semi q u a n t i t a t i v e terms would a l s o be u s e f u l f o r purpose o f our s t u d y .  the  I t ' i s t o be. r e i t e r a t e d t h a t o u r i n v e s t i g a t i o n s  c e n t e r e d l a r g e l y on p l a n t mediated p r o c e s s e s and not  classification  o f the w e t l a n d s .  3.4.1  M a t e r i a l s and methods  A n a l y s e s were done on s u b s t r a t e samples c o l l e c t e d from some o f the study s i t e s .  In most cases up t o t h r e e s o i l  each s i t e and composited to make a sample.  cores were t a k e n from  The s o i l samples were  d r i e d a t 60° C and p u l v e r i z e d i n a m o r t a r w i t h a p e s t l e .  Organic  m a t t e r was determined by t h e W a l k l e y - B l a c k p r o c e d u r e ( A l l i s o n 1965). The pH was measured i n a 1:3 s o i l - w a t e r s l u r r y p r e p a r e d by m i x i n g 40 g o f s o i l w i t h 120 ml o f d i s t i l l e d w a t e r .  A f t e r s h a k i n g f o r one  hour, r e a d i n g s were taken u s i n g a Beckman pH meter.  Electrical  c o n d u c t i v i t y , a r e f l e c t i o n of t o t a l s o l u t e s i n the s o i l  solution,  was measured w i t h a c o n d u c t i v i t y meter ( r a d i o m e t e r type CDM 2e) w i t h the r e a d i n g s e x p r e s s e d i n m i l l i m h o s / c m . same as f o r pH.  S o i l p r e p a r a t i o n was t h e  P o t a s s i u m , c a l c i u m , phosphorus and magnesium were  35  measured u s i n g methods o u t l i n e d i n the Morgan S o i l T e s t i n g System (Lunt e t al_. 1958).  3.4.2  Results  T a b l e 3 g i v e s crude e s t i m a t e s o f some o f the e d a p h i c v a r i a b l e s measured.  The t a b l e shows a wide range o f v a r i a b i l i t y i n the f a c t o r s  examined.  3.4.3  Discussion  Except f o r P i t t marsh, most s i t e s g e n e r a l l y have a t l e a s t medium l e v e l s o f m i n e r a l c o n s t i t u e n t s i n the s u b s t r a t e s .  The low m i n e r a l  l e v e l s i n the P i t t marsh can be a t t r i b u t e d to l e a c h i n g l o s s e s .  In  areas c o n s t a n t l y f l o o d e d l e a c h i n g and removal o f i o n i c m a t e r i a l s waterways l e a v e r e l a t i v e l y o l i g o t r o p h i c c o n d i t i o n s .  in  In the F r a s e r  d e l t a marshes, t i d a l f l u s h i n g b r i n g s i n s o l u t e s from the sea thus confounding such l o s s e s .  Low i o n i c l e v e l s i n a r a b l e s i t e s  are-related  t o uptake by t h e c u l t i v a t e d p l a n t s p e c i e s . O r g a n i c m a t t e r i s g e n e r a l l y much h i g h e r i n w e t l a n d s compared to arable "dry" lands.  T h i s i s more p a r t i c u l a r l y so i n the P i t t marsh.  High o r g a n i c m a t t e r c o n t e n t would be a r e f l e c t i o n o f l o n g term a c c u m u l a t i o n o f phytomass i n the w e t l a n d s .  A t the t i d a l marshes,  much o f the phytomass i s removed through t i d a l a c t i o n ; o r g a n i c m a t t e r t e n d i n g t o accumulate near the dykes where t i d a l a c t i o n i s  least.  36 Table 3.1  E l e c t r i c a l Conductivity (E.C.), pH, % Organic Matter (O.M.), and Available Major Elements i n the top 10 cm of the S o i l P r o f i l e of Some of the Study Sites  Site  E.C. (mmhos/cm)  pH  % O.M.  P  K  Ca  Mg  Brunswick marsh  0.4  6.7  10.2  med  med  med  med  Iona marsh  0.5  6.6  10.6  med  med  med  med  P i t t marsh  0.4  4.8  51.3  high  low  low  low  Alaksen  0.1  5.8  9.1  med  low  med  med  U.B.C.  0.1  5.9  4.2  med  low  med  med  Colony Farm ( s i t e 1)  0.9  4.5  6.0  med  med  high  high  Colony Farm ( s i t e 2)  0.1  4.8  10.6  med  low  med  med  Site 1  Dactylis glomerata s i t e  Site 2  Phalaris arundinacea s i t e  37 Because n i t r o g e n c o n t e n t i s dependent on the o r g a n i c m a t t e r c o n t e n t o f the s o i l  (Jackson 1958), i t s h o u l d e x h i b i t the same t r e n d as  organic matter.  S i m i l a r l y s o i l phosphorus, w i t h 45 - 50 p e r c e n t  g e n e r a l l y c o n s i d e r e d to be o r g a n i c , would r e f l e c t o r g a n i c m a t t e r . l e v e l s . Some phosphorus may o f course be l o s t v i a o v e r f l o w of water from the wetlands. The i n f l u e n c e o f s a l i n e marine water i n the t i d a l marshes accounts f o r the h i g h e r pH a t the marshes w h i l e m i c r o b i a l a c t i v i t y may be a f a c t o r i n t h e more a c i d i c c o n d i t i o n s o f the P i t t marsh.  3.5  D e s c r i p t i o n o f the I n d i v i d u a l P l a n t S p e c i e s S t u d i e d  In a r e c e n t paper, Bernard and Gorham: (1978) emphasized the need t o study the l i f e h i s t o r i e s o f w e t l a n d s p e c i e s f o r they have a profound i n f l u e n c e on the p r o d u c t i o n p r o c e s s e s o f i n d i v i d u a l s and, i n t u r n , on those o f the community.  "We see n a t u r a l h i s t o r y t h e r e f o r e as an i n t e g r a l  p a r t o f the q u a n t i t a t i v e ecosystem e c o l o g y . "  Bernard and Gorham c o n -  s i d e r e d two p a r t i c u l a r a s p e c t s of sedge l i f e h i s t o r i e s as (a)  critical:  the v e r y c o n s i d e r a b l e green s t a n d i n g crop i n w i n t e r and (b) the  v e r y h i g h shoot m o r t a l i t y a s s o c i a t e d w i t h some sedge s p e c i e s a t t a i n i n g t h e i r "normal" l i f e span.  Our contemporaneous  a l t h o u g h b r o a d e r i n s c o p e , are s i m i l a r l y d i r e c t e d .  before  studies,  P r e s e n t e d below  are d e s c r i p t i o n s i n semi, q u a n t i t a t i v e terms o f some g r o s s m o r p h o l o g i c a l , taxonomic and h a b i t a t f e a t u r e s o f the p r i n c i p a l s p e c i e s we s e l e c t e d s t u d y from 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 .  Other features are  t o i n the balance o f the t e x t where r e l e v a n t .  for  referred  38 3.5.1  Some Taxondmic f e a t u r e s . a n d h a b i t a t s o f t h e p r i n c i p a l s p e c i e s  Species  Family  Habitat  studied*  Distribution  Equisetum f l u v i a t i l e (Scouring rush)  Equisetaceae  bogs and standing water  Alaska to Pennsylvania  Scirpus acutus (Hardstern bulrush)  Cyperaceae  usually standing water, up to lm. deep  Widespread i n temperate North America  Scirpus (cyperinus?) (Wool-grass)  Cyperaceae  shallow standing water  Canada to Florida  Carex sitchensis (Sitka sedge)  Cyperaceae  shallow standing water  Alaska to California  Calamagrostis canadensis (Bluejoint)  Graminaea  water margins & land short flooded  Alaska to Quebec to C a l i f o r n i a  Phalaris arundinacea (Reed canary grass)  Graminaea  water margins & land short flooded  Circumboreal, Alaska to California  Juncus effusus (Common rush)  Juncaceae  tide f l a t s & most old f i e l d s  Circumboreal, Alaska to C a l i fornia, Europe  Typha l a t i f o l i a (Common c a t - t a i l )  Typhaceae  shallow slow moving fresh water  Alaska to Mexico, Erasia, North Africa  Carex lyngbyei (Lyngby's sedge)  Cyperacea  brackish water, intertidal  Circumboreal along sea coasts  Dactylis glomerata (Orchard grass)  Gramineae  arable land & old f i e l d s  Introduced to North America, native to Eurasia & North Africa  Lolium perenne Gramineae (Perennial rye grass)  arable land & old f i e l d s  Introduced to North America, native to Eurasia  Gramineae  arable land & old f i e l d s  Introduced to North America, native to Eurasia  Agropyron repens (Quack grass) *  Nomenclature adopted from Hitchcock et a l . (1969) and Hitchcock and Cronquist (1973).  39 3.5.2  Some p l a n t c h a r a c t e r i s t i c s o f t h e p r i n c i p a l s p e c i e s  Species  Standing shoot description  studied  Standing shoot in winter  Root & Rhizome description  Equisetum f l u v i a t i l e  terete,hollow  shoot bases rarely green  rhizomes pithy, thick, very extensive  Scirpus acutus  terete, pithy, tall  shoot bases rarely green  rhizomes thick, pithy  Scirpus cyperinus  triangular, pithy, hollow tendency to tufting  dead  rhizomes short, pithy  Carex sitchensis  triangular, hollow,blades 3 ranked  dead except tips  rhizomes extensive  terete, hollow, blades 2 ranked  dead  fine rhizomes, lacunae  terete,hollow t a l l , blades 2 ranked  dead  rhizomes thick, extensive lacunae  Juncus effusus  tubular, caespitose, nearly bladeless  green & dead  rhizomes short, pithy  Typha l a t i f o l i a  erect, t a l l , spongy  dead  rhizomes extensive, thick, pithy  Carex lyngbyei  triangular, blades somewhat succulent  green & dead  roots & rhizomes f i n e , pithy  Dactylis glomerata  caespitose, blades  dead  roots fibrous  Lolium perenne  caespitose, blades thin, 2 ranked  dead  roots fibrous  Agropyron repens  blades thin, 2 ranked  dead  rhizomes s o l i d , extensive  Calamagrostis canadensis  Phalaris arundinacea  40 3.5.3  Some gross m o r p h o l o g i c a l f e a t u r e s of the s t a n d i n g shoots  In t h e w e t l a n d e n v i r o n m e n t , s t r a t e g i e s " a d o p t e d " by d i f f e r e n t s p e c i e s a r e many, undoubtedly to meet v a r i a t i o n s i n the p h y s i c a l  conditions.  D i f f e r e n c e s i n shoot h e i g h t i n r e l a t i o n t o w a t e r depth i s an apparent adaptation.  Phenological  differences  i n time o f shoot emergence, time o f  f l o w e r i n g and time o f shoot death may a l l changes.  be r e l a t e d to e n v i r o n m e n t a l  Some a d a p t i v e f e a t u r e s o f the i n d i v i d u a l w e t l a n d s p e c i e s were  p r e s e n t e d under S e c t i o n 3 . 5 . 1 , some a r e i n c o r p o r a t e d below w h i l e  others  appear i n the b a l a n c e o f t h e t e x t when r e l e v a n t .  3.5.3.1  M a t e r i a l s and methods  At what was deemed t o be a g e n e r a l peak f o r s t a n d i n g crops 1 9 7 7 ) , f o u r 0.25m  (October  q u a d r a t samples were h a r v e s t e d f o r each s p e c i e s .  w e i g h t s were o b t a i n e d from t h e h a r v e s t from two q u a d r a t s .  Dry  From t h e o t h e r  two q u a d r a t s , average shoot h e i g h t s , numbers, volumes and p h o t o s y n t h e t i c a r e a s were d e t e r m i n e d .  Shoot volumes were e s t i m a t e d by w a t e r d i s p l a c e -  ment and volume/weight r a t i o s were computed.  For s p e c i e s l i k e Juncus  e f f u s u s w i t h t u b u l a r s h o o t s , s u r f a c e a r e a s were c r u d e l y e s t i m a t e d u s i n g the 2 II rh f o r m u l a f o r a c y l i n d e r , w h i l e those o f s p e c i e s l i k e S c i r p u s c y p e r i n u s w i t h t r i a n g u l a r c r o s s s e c t i o n s , the %nal f o r m u l a f o r a r e g u l a r p r i s m was used (Where r = r a d i u s o f a c y l i n d e r , h = h e i g h t o f  the  c y l i n d e r , n = number o f s i d e s o f a p r i s m , 1 = s l a n t h e i g h t and a = l e n g t h o f one s i d e o f the p r i s m b a s e ) .  A r e a / w e i g h t r a t i o s were then computed.  41 3.5.3.2  O b s e r v a t i o n s and r e s u l t s  T a b l e 3.2 shows some o f the g r o s s m o r p h o l o g i c a l d a t a from s e l e c t e d s p e c i e s from P i t t October 1977.  collected  (P) and Brunswick (B) marshes i n  For the P i t t marsh s p e c i e s , the t a b l e proceeds  v e r y wet t o l e s s m o i s t s i t e s .  D e s p i t e the wide range o f  from  variability  between s p e c i e s , some c h a r a c t e r i s t i c t r e n d s may be d i s c e r n e d a l o n g t h i s moisture gradient. Dry m a t t e r y i e l d s o f apparent peak s t a n d i n g crops p a r a l l e l e d the w a t e r depth g r a d i e n t .  roughly  Quadrat y i e l d s o f Juncus  were not easy t o determine because o f i t s c a e s p i t o s e n a t u r e .  effusus Typha  l a t i f o l i a y i e l d e d s l i g h t l y l e s s dry m a t t e r than P h a l a r i s a r u n d i n a c e a , the h i g h e s t y i e l d i n g s p e c i e s from t h e P i t t marsh. Equisetum f l u v i a t i l e and S c i r p u s acutus shoots growing i n the w e t t e s t s i t e s had the h i g h e s t volume/weight r a t i o s .  These r a t i o s were  s i m i l a r t o t h a t o f Typha l a t i f o l i a from Brunswick m a r s h . No d i s c e r n i b l e t r e n d s c o u l d be d e t e c t e d i n the a r e a / w e i g h t o f the shoots from d i f f e r e n t  ratios  species.  A l t h o u g h t h e r e was c o n s i d e r a b l e s p e c i e s v a r i a t i o n , shoot d e n s i t y appeared to i n c r e a s e w i t h d e c r e a s i n g water d e p t h . produced 23 shoots p e r 0.25m d e n s i t y o f 934.  Scirpus acutus  whereas Juncus e f f u s u s had a shoot  The l o w e s t shoot d e n s i t y was r e c o r d e d i n Typha  l a t i f o l i a from the Brunswick marsh. In the P i t t marsh, average shoot h e i g h t ranged from 0.8m i n Equisetum f l u v i a t i l e and Juncus e f f u s u s to 1.6m i n P h a l a r i s a r u n d i n a c e a . Typha l a t i f o l i a produced much t a l l e r shoots than the s p e c i e s from P i t t marsh.  42 Table 3.2  Some gross morphological features of standing shoots of selected species from P i t t (P) and Brunswick (B) marshes, October 1977.  Species  Site  Dry wt g/0.25m  Ratio volume/wt  Ratio area/wt  # shoots per 0.25m  Average height(m)  2  Equisetum f l .  P  56  17  126  66  0.8  Scirpus a.  P  79  10  71  23  1.1  Scirpus cyp.  P  275  8 '  84  114  Carex s i t .  P  213  6  118  78  1.1  Calamagrostis c.  P  316  4  73  114  1.3  Juncus e f f .  P  290  8  98  934  0.8  Phalaris ar.  P  482  5  67  163  1.6  Typha l a t .  B  426  13  83  15  2.7  1.0  43 3.5.3.3  Discussion  Morphological  c h a r a c t e r i s t i c s such as shoot h e i g h t ,  photosynthetic  a r e a and shoot volume can be o f c o n s i d e r a b l e v a l u e i n t h e u n d e r s t a n d i n g o f p r o d u c t i o n p r o c e s s e s and a d a p t a t i o n o f w e t l a n d s p e c i e s to t h e i r e n v i r o n ment.  Dry m a t t e r y i e l d s a t time o f peak s t a n d i n g c r o p r o u g h l y  w a t e r depth g r a d i e n t .  paralleled  However the s t a n d i n g c r o p a t any one time does not  n e c e s s a r i l y r e f l e c t the seasonal p r o d u c t i v i t y o f a g i v e n s p e c i e s . s p e c i e s are known t o extend the l e n g t h o f t h e i r  Some  ' g r o w i n g ' season i n t o  w i n t e r , m a i n t a i n i n g p h o t o s y n t h e t i c a l l y a c t i v e surface f o r very long p e r i o d s . Moreover, peak s t a n d i n g c r o p does not t a k e i n t o account any shoot m o r t a l i t y d u r i n g the growing s e a s o n . E x t e n s i v e development o f a i r c a v i t i e s , l a c u n a e and p i t h y t i s s u e i n the r o o t s and a e r i a l shoots i s c h a r a c t e r i s t i c o f p l a n t s growing under w a t e r logged c o n d i t i o n s .  These f e a t u r e s a r e r e f l e c t e d i n t h e h i g h volume/weight  r a t i o s r e c o r d e d i n some o f the s p e c i e s examined.  In b r a c k i s h o r  saline  h a b i t a t s , s u c c u l e n c e appears t o be an added a d a p t i v e f e a t u r e t o the h i g h e r levels of  solute.  No d i s c e r n i b l e t r e n d s were d e t e c t e d i n the a r e a / w e i g h t r a t i o s o f the shoots from d i f f e r e n t s p e c i e s .  There a r e o f c o u r s e o b v i o u s  a s s o c i a t e d w i t h l e a f a r e a measurements.  difficulties  Some shoots a r e open, some are  t e r e t e while others are v i r t u a l l y b l a d e l e s s . Shoot d e n s i t y o f t h e emergents appeared t o d e c l i n e w i t h water d e p t h .  increasing  Such a d e c l i n e i n shoot number i s o f t e n accompanied by  d e c r e a s e d dry m a t t e r p r o d u c t i o n .  44 4.  PRODUCTIVITY OF EMERGENT VEGETATION  I t was beyond the scope o f t h i s study t o p r e s e n t a d e t a i l e d i n v e s t i g a t i o n o f the p r i m a r y p r o d u c t i o n p r o c e s s e s o f the wetlands B r i t i s h Columbia.  of  R a t h e r , our approach was t o e s t a b l i s h some b a s e l i n e  d a t a which would a i d i n e a r l y management and f u t u r e i n v e s t i g a t i o n s the w e t l a n d s .  of  Our a d m i t t e d l y crude and s i m p l e approach e n a b l e d us t o  sample a f a i r l y l a r g e number o f p l a n t communities c o n s i d e r i n g the l i m i t a t i o n s o f t i m e , space and f u n d s .  4.1  Peak S t a n d i n g Crop Y i e l d s  The p r i m a r y p r o d u c t i o n o f w e t l a n d s may be o b t a i n e d by s e v e r a l methods:  (1)  measuring peak s t a n d i n g c r o p ;  minimum s t a n d i n g c r o p ; h a r v e s t s and (5)  (3)  (2)  d i s a p p e a r a n c e methods;  gaseous exchange.  maximum minus (4) m u l t i p l e  The peak s t a n d i n g c r o p method i s  w i d e l y used ( W e s t l a k e , 1963) and has t h e advantages o f being r e l a t i v e l y cheap, r a p i d and u s e f u l i n comparison t o d i f f e r e n t p l a n t c o m m u n i t i e s . We c o n s i d e r e d the method t o be s u i t a b l e f o r the purposes o f our probes i n t o p r o c e s s e s o p e r a t i v e i n B r i t i s h C o l u m b i a ' s w e t l a n d s , as on these wetlands i s s t i l l  very scanty.  information  We a l s o d i r e c t e d major  a t t e n t i o n t o s i n g l e c r o p h a r v e s t s , because o f t h e l i m i t a t i o n s o f  time  and the t e c h n i c a l d i f f i c u l t i e s a s s o c i a t e d w i t h the o t h e r methods.  4.1.1  M a t e r i a l s and methods  In most w e t l a n d 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 , the emergent v e g e t a t i o n i s q u i t e s h a r p l y zoned; each zone i s r e a d i l y c h a r a c t e r i z e d  45 by one o r r a r e l y two dominant p l a n t s p e c i e s , each s p e c i e s e x i s t i n g a l m o s t pure s t a n d s .  in  A c c o r d i n g l y , samples o f each s p e c i e s were t a k e n ,  more o r l e s s c e n t r a l l y from a zone (pure s t a n d ) .  The f o l l o w i n g were  t h e s p e c i e s chosen f o r s a m p l i n g : (a)  From the P i t t marsh: S c i r p u s acutus M u h l . * (hardstem b u l r u s h ) Equisetum f l u v i a t i l e L. Juncus e f f u s u s L.  (scouring rush)  (common r u s h )  P h a l a r i s a r u n d i n a c e a L.  (reed c a n a r y g r a s s )  The o r d e r o f the s p e c i e s l i s t i n g f o l l o w s a g r a d a t i o n from the w e t t e s t zones w i t h s t a n d i n g water a l l  season ( t o p ) t o the l e a s t wet  zones where s t a n d i n g water i s found f o r o n l y s h o r t p e r i o d s a l t h o u g h the s u b s t r a t e i s r a r e l y d r y ( b o t t o m ) . (b)  From Brunswick P o i n t marsh: Carex l y n g b y e i Horneum ( L y n g b y ' s sedge) Typha l a t i f o l i a L.  (common c a t - t a i l )  F e s t u c a a r u n d i n a c e a Schreb ( t a l l  fescue)  The s p e c i e s a r e l i s t e d i n o r d e r o f d e c r e a s i n g t i d a l  inundation,  Carex l y n g b y e i i s i n u n d a t e d by t i d e s f o r the l o n g e s t p e r i o d , w h i l e Festuca arundinacea i s only i n f r e q u e n t l y subjected to t i d a l (c)  waters.  From Iona I s l a n d marsh: Carex l y n g b y e i Horneum ( L y n g b y ' s sedge) Iona I s l a n d marsh i s s i m i l a r t o t h a t o f Brunswick P o i n t w i t h the  e x c e p t i o n t h a t i t i s much i n f l u e n c e d by sewage d i s p o s a l and o t h e r man mediated d i s t u r b a n c e .  46 (d)  From A l a k s e n ( N a t i o n a l W i l d l i f e Refuge Farm): L o l i u m perenne L.  (perennial  D a c t y l i s g l o m e r a t a L. Agropyron repens L.  ryegrass)  (orchard grass) Beauv.  (quack g r a s s )  L o l i u m perenne and D a c t y l i s g l o m e r a t a , commonly used as hay and p a s t u r e , were i n c l u d e d f o r c o m p a r i s o n .  M i g r a n t and r e s i d e n t  birds  g r a z e d t h e s i t e so s e l e c t i v e l y t h a t t h e dominant L o l i u m d i s a p p e a r e d a l m o s t c o m p l e t e l y from the sward i n the f i r s t y e a r o f the s t u d y . (e)  From Colony Farm ( P r o v i n c i a l Government Farm): P h a l a r i s a r u n d i n a c e a L. D a c t y l i s g l o m e r a t a L.  (reed canarygrass) (orchard grass)  To e s t i m a t e peak s t a n d i n g c r o p y i e l d s , two samples were t a k e n f o r each s p e c i e s u s i n g one meter square q u a d r a t s .  The s a m p l i n g frame was  t o s s e d i n t o the s t a n d and a d j u s t e d so t h a t a t l e a s t two meter d i s t a n c e was m a i n t a i n e d between t h e edges o f a d j a c e n t q u a d r a t s .  Green p h o t o -  s y n t h e t i c a l l y a c t i v e shoots were c u t a t ground l e v e l , p l a c e d i n bags, t r a n s p o r t e d t o the U n i v e r s i t y o f B r i t i s h Columbia campus, d r i e d i n a t u n n e l d r i e r a t 60°C and weighed.  4.1.2  Results  C o n s i d e r a b l e v a r i a t i o n i n peak s t a n d i n g c r o p e s t i m a t e s were r e c o r d e d a t the t i d a l and a r a b l e s i t e s ( T a b l e 4 . 1 ) .  For the t i d a l  marsh s i t e s , Carex l y n g b y e i produced the l e a s t d r y m a t t e r as compared t o Typha l a t i f o l i a and F e s t u c a a r u n d i n a c e a .  Carex l y n g b y e i  generally  47 Table 4.1  Estimates of peak standing crop y i e l d s (dry matter i n g/m , as averaged from two meter square quadrats on Brunswick and Iona marshes and i n arable lands at Alaksen and Colony Farm)  Location  Species  Brunswick marsh  Carex lyngbyei  October 1977  September 1976  424  745  1704  Typha l a t i f o l i a Festuca arundinacea  1125  Iona  Carex lyngbyei  689  Alaksen  Lolium perenne  655  Colony Farm  Phalaris arundinacea  Table 4.2  311  1055  Estimates of peak standing crop y i e l d s (dry matter i n grams as averaged from two meter quadrats) f o r s i x species of the P i t t marsh, October 1977 Species  , 2 g/m  Scirpus acutus  316  Equisetum f l u v i a t i l e  2 2  Scirpus cyperinus Carex sitchensis  4  1100 852  Calamagrostis canadensis  1264  Phalaris arundinacea  1928  48 t h r i v e s a t lower t i d e l e v e l s , w h i l e the o t h e r two s p e c i e s a r e f r e q u e n t l y found a t h i g h e r t i d e l e v e l s .  From the a r a b l e s i t e s , P h a l a r i s  arundinacea  had a h i g h e r peak s t a n d i n g c r o p (1055 g/m ) than L o l i u m perenne (483 2 g/m  average ) . A general t r e n d of i n c r e a s i n g s t a n d i n g crop y i e l d s from more h y d r i c  t o l e s s h y d r i c h a b i t a t s was noted f o r t h e s p e c i e s sampled from the marsh ( T a b l e 4 . 2 ) .  Pitt  Equisetum f l u v i a t i l e produced t h e l e a s t d r y m a t t e r  2 (224 g/m ) w h i l e P h a l a r i s a r u n d i n a c e a produced the h i g h e s t y i e l d (1928 g/m ). 2  4.1.3  Discussion  From T a b l e 4 . 1 , i t can be seen t h a t peak y i e l d s f o r Carex l y n g b y e i o f the Brunswick and Iona marshes a r e lower than those f o r  Festuca  a r u n d i n a c e a , the common s p e c i e s o f the zone n e a r e r the dyke and t h e high t i d e l e v e l .  Typha l a t i f o l i a o c c u p i e s a s p e c i a l h a b i t a t a l o n g the  f o r e s h o r e , o c c u r r i n g m a i n l y where g r a v i t a t i o n a l water appears t o through the dykes from nearby a g r i c u l t u r a l l a n d s .  inflow  S u b s t r a t e and water  l e v e l t h e r e f o r e appear to be major y i e l d d e t e r m i n a n t s ( F i g u r e 4 . 1 ) . These o b s e r v a t i o n s a r e supported by peak s t a n d i n g c r o p y i e l d s g i v e n by Yamanaka (1975) f o r the F r a s e r d e l t a marshes i n c l u d i n g Brunswick and Iona marshes.  Yamanaka noted t h a t f o r a g i v e n marsh, t h e r e was a r o u g h l y  l i n e a r d e c r e a s e i n peak s t a n d i n g c r o p y i e l d s w i t h i n c r e a s i n g d i s t a n c e seaward from the d y k e s . The d a t a o b t a i n e d from the P i t t marsh (Table 4 . 2 ) , a l s o t h a t as the marsh z o n a t i o n grades towards the near a q u a t i c  indicate  habitat,  49  Figure 4.1:  Photographs showing V a r i a t i o n s i n Communities w i t h V a r i a b l e Water Depth.  Top photo:  P i t t marsh, s p r i n g 1978  Bottom photo:  Brunswick marsh, s p r i n g 1978 (Douglas log flotsam in foreground often destructive of plant cover).  fir  locally  So  51 s p e c i e s by s p e c i e s , peak s t a n d i n g c r o p y i e l d s d e c l i n e .  The change  i n v a l u e i s so marked t h a t d e s p i t e the c r u d i t y of the peak h a r v e s t t e c h n i q u e , i t may be i n f e r r e d t h a t the g r a d a t i o n i s  valid.  Data from peak y i e l d q u a d r a t s can be u s e f u l f o r broad comp a r a t i v e purposes.  However, such e s t i m a t e s appear t o be too c o n -  s e r v a t i v e o f t e n i g n o r i n g l o s s e s from s e n e s c e n c e , decay, a b r a s i o n or grazing.  I t i s a l s o p o s s i b l e , as w i l l be demonstrated i n  later  d i s c u s s i o n s , t o ml^ie&eJ^gifeSfcy t h e p r e c i s e time o f maximum dry matter production.  4.2  •  '  Seasonal Changes i n Dry M a t t e r  Production  I t was q u i t e apparent v e r y e a r l y i n t h i s s t u d y t h a t the growth and development p a t t e r n s o f the v a r i o u s p l a n t s p e c i e s under i n v e s t i g a t i o n were v e r y d i f f e r e n t .  Because of t h e s e d i f f e r e n t i a l  growth p a t t e r n s , we  a n t i c i p a t e d t h a t d a t a from s i n g l e date h a r v e s t s would v e r y l i k e l y m i s r e p r e s e n t a c t u a l dry m a t t e r p r o d u c t i o n by the s p e c i e s .  A l t h o u g h the  approach o f s e q u e n t i a l s a m p l i n g has i t s weaknesses, the t e c h n i q u e  is  s u p e r i o r t o the s i n g l e h a r v e s t method i n e s t i m a t i n g t r u e dry m a t t e r p r o d u c t i o n because i t t a k e s i n t o a c c o u n t such d i f f e r e n c e s i n s p e c i e s growing p a t t e r n s .  A c c o r d i n g l y , we d e c i d e d t o c o l l e c t s t a n d i n g c r o p  data a t i n t e r v a l s o f s e v e r a l months t o supplement the peak s t a n d i n g crop data p r e s e n t e d i n S e c t i o n 4 . 1 .  52 4.2.1  M a t e r i a l s and methods  The m a t e r i a l s and methods were s i m i l a r to those d e s c r i b e d under Section 4.1.  4.2.2  O b s e r v a t i o n s and r e s u l t s  The seasonal changes i n dry m a t t e r of s t a n d i n g crops o f s e v e r a l s p e c i e s from the F r a s e r d e l t a marshes and a r a b l e l a n d s a r e p r e s e n t e d i n Table 4 . 3 .  The t a b l e shows t h a t most s p e c i e s e x p e r i e n c e d a r a p i d  growth i n the s p r i n g and e a r l y summer months but t h a t time o f peak d r y matter production d i f f e r e d with species.  Carex l y n g b y e i had peak  s t a n d i n g c r o p p r o b a b l y around J u l y o r August d e c l i n i n g i n September, w h i l e F e s t u c a a r u n d i n a c e a extended i t s peak y i e l d t o a much l a t e r d a t e . S i m i l a r t r e n d s were a p p a r e n t f o r the a r a b l e s p e c i e s ,  Phalaris  a r u n d i n a c e a behaving much T i k e F e s t u c a a r u n d i n a c e a . The s e a s o n a l changes i n s t a n d i n g c r o p y i e l d s of s e v e r a l  plant  s p e c i e s sampled from t h e P i t t V a l l e y marsh i n May and October 1977 are presented i n Table 4 . 4 . October y i e l d s f o r a l l  May y i e l d s were c o n s i d e r a b l y l o w e r than  s p e c i e s examined.  The t r e n d o f d e c r e a s i n g d r y  m a t t e r p r o d u c t i o n w i t h i n c r e a s i n g h y d r i c c o n d i t i o n s were d i s c e r n e d e s p e c i a l l y i n the October samples. I t appears t h a t the seasonal l i f e h i s t o r i e s o f p l a n t s p e c i e s wetlands have a profound i n f l u e n c e on t h e i r p r o d u c t i o n p r o c e s s e s . o f t h e s e l i f e h i s t o r y e v e n t s were r e c o r d e d i n our s t u d i e s .  in Some  In g e n e r a l ,  t i m i n g o f shoot death appeared t o v a r y w i t h s p e c i e s ( F i g u r e 4 . 2 ) .  53 T a b l e 4.3  S e a s o n a l changes i n the s t a n d i n g crops (g/m  dry matter)  of f i v e s p e c i e s from t h e F r a s e r d e l t a marshes and a r a b l e l a n d s , Summer 1976.  May 18-23  Species  Location  June 5-7  July 5-9  Sept. 16-21  Iona marsh  Carex l y n g b y e i  351  872  689  B r u n s w i c k marsh  Carex l y n g b y e i  661  900  745  844  1125  Festuca arundinacea  -  787  Colony Farm Alaksen arable  field  T a b l e 4.4  Phalaris arundinacea L o l i u m perenne  520 -  773  Dactylis glomerata  520  844  S e a s o n a l changes i n s t a n d i n g c r o p s (g/m s p e c i e s from the P i t t marsh,  Species  May  714  1055  688  665  dry matter) o f f o u r  1977.  1977  October  Scirpus cyperinus  200  1100  Carex s i t c h e n s i s  165  852  Calamagrostis canadensis  149  1264  P h a l a r i s arundinacea  507  1928  1977  54  Figure 4.2:  Photographs showing C o n t r a s t s i n T i m i n g o f Shoot Death, Iona marsh.  Top photo:  brown Carex l y n g b y e i green Elymus y a n c o u v e r i e n s i s ,  Bottom photo:  l i v e and dead shoots o f Juncus i n mid w i n t e r  (Pitt)  effusus  56  The number o f Carex l y n g b y e i shoots d y i n g seemed to be minimal f r e s h e t time i n June and J u l y .  around  In September and O c t o b e r , d r a m a t i c death  o f shoots was observed and appeared to be r e l a t e d t o the advent o f w a t e r from s t o r m s .  salt  On the o t h e r hand, F e s t u c a a r u n d i n a c e a , a coarse grass  e s t a b l i s h e d a t f a i r l y h i g h t i d e l e v e l s , u s u a l l y remained green w e l l the autumn.  Most o f the c u r r e n t s e a s o n ' s shoots o f the s p e c i e s  were dead by l a t e f a l l  into  studied  u s u a l l y b e f o r e the advent o f f r e e z i n g t e m p e r a t u r e s .  D u r i n g w i n t e r , new shoots o f some marsh s p e c i e s emerged from the s u b s t r a t e t o h e i g h t s r a n g i n g from a few m i l l i m e t e r s t o 50 mm o r more. V a r i a t i o n s i n p h e n o l o g i c a l p a t t e r n s o f development were a l s o noted i n the P i t t marsh emergents.  Carex s i t c h e n s i s was i n f u l l  o f S c i r p u s acutus had emerged from the s u b s t r a t e .  f l o w e r b e f o r e shoots  C o n s i d e r a b l e development  o f new p h o t o s y n t h e t i c shoots o f Carex s i t c h e n s i s and Juncus e f f u s u s p l a c e d u r i n g the w i n t e r months.  In s p r i n g , a k i n d o f " h i g h l i n e "  took  could  be seen a c r o s s Carex s i t c h e n s i s s t a n d s d e l i n e a t i n g the o v e r w i n t e r e d m a t e r i a l s from green shoots o f the c u r r e n t season ( F i g u r e 4 . 3 ) .  4.2.3  Discussion  Seasonal t r e n d s i n s t a n d i n g crop were n o t so e a s i l y d i s c e r n i b l e  partly  because the samples were n o t c o l l e c t e d f r e q u e n t l y enough i n any one y e a r . But i n g e n e r a l , dry m a t t e r y i e l d s s t a r t e d o f f a t a low l e v e l i n the s p r i n g , g r a d u a l l y i n c r e a s e d , r e a c h i n g a peak i n mid season f o r s p e c i e s l i k e Carex l y n g b y e i and l a t e r i n the season f o r s p e c i e s l i k e a r u n d i n a c e a and F e s t u c a a r u n d i n a c e a .  Phalaris  These f i n d i n g s are i n g e n e r a l  57  Figure 4.3:  Photographs Showing O l d e r O v e r w i n t e r e d F l o w e r i n g Shoots and New Shoots o f Carex s i t c h e n s i s i n P i t t marsh (Spring 1976).  59  agreement w i t h those o f Barnard (1975) and Moody (1978) who r e p o r t e d J u l y and August t o be the p e r i o d o f peak dry m a t t e r p r o d u c t i o n  for  most common s p e c i e s o f the P i t t and F r a s e r d e l t a f o r e s h o r e marshes respectively.  However, our r e s u l t s show t h a t some Important s p e c i e s  from the same marshes may reach peak y i e l d s much l a t e r than A u g u s t . From our o b s e r v a t i o n s , i t appears t h a t i n n a t e d i f f e r e n c e s s p e c i e s l i f e h i s t o r y and p h e n o l o g i c a l  in  development c o u l d be v e r y  i m p o r t a n t i n d e t e r m i n i n g the s e a s o n a l p a t t e r n s o f dry m a t t e r p r o d u c t i o n by t h e emergent c o m m u n i t i e s . A l t h o u g h s e a s o n a l t r e n d s i n d r y m a t t e r p r o d u c t i o n may be s p e c i e s c h a r a c t e r i s t i c , such t r e n d s may be c o n s i d e r a b l y a l t e r e d by t h e many u n p r e d i c t a b l e events i n the w e t l a n d e n v i r o n m e n t .  Species y i e l d  p a t t e r n s c o u l d be s i g n i f i c a n t l y a l t e r e d by e r r a t i c changes i n water l e v e l s a s s o c i a t e d w i t h heavy r a i n s i n the P i t t marsh o r by h i g h  tides  b r i n g i n g i n s a l i n e water o f v a r y i n g d a t e and volume i n t h e Brunswick marsh.  Such e r r a t i c changes are not uncommon i n the w e t l a n d s  (Barnard 1975, Moody 197,8). that yearly differences  studied  I t i s t h e r e f o r e r e a s o n a b l e t o assume  i n dry m a t t e r p r o d u c t i o n e x i s t even w i t h i n  the same s t a n d .  4.3  Year t o Year V a r i a t i o n i n S p r i n g S t a n d i n g Crops  Quadrat samples f o r e s t i m a t e s o f s t a n d i n g crops were g e n e r a l l y taken from s i t e s h i g h l y u n i f o r m i n s t a n d and s u b s t r a t e .  M o r e o v e r , most  stands sampled were a s s o c i a t e d w i t h sharp e c o t o n e s ; i n o t h e r w o r d s , t h e r e was l i t t l e i n t e r g r a d a t i o n from zone t o zone.  Given t h e s t a n d  60 p u r i t y and our s t r a t i f i c a t i o n u s i n g mid-zone s i t i n g , one would e x p e c t l i t t l e y e a r t o y e a r v a r i a t i o n i n samples o b t a i n e d from a s p e c i f i c d a t e . We t e s t e d t h i s h y p o t h e s i s by sampling on a p p r o x i m a t e l y the same date over a t h r e e y e a r p e r i o d i n the same general  4.3.1  locations.  M a t e r i a l s and methods  The m a t e r i a l s and methods were s i m i l a r to those d e s c r i b e d Section 4.1.  Sampling was undertaken a t a p p r o x i m a t e l y the same date  i n May of 1976, 1977 and 1978, and i n the same g e n e r a l  4.3.2  in  locations.  Results  Large s p e c i e s d i f f e r e n c e s i n s p r i n g s t a n d i n g c r o p can be seen 2 from T a b l e 4 . 5 .  The s t a n d i n g c r o p y i e l d s ranged from 127 g/m 2  S c i r p u s c y p e r i n u s t o 561 g/m were a l s o e v i d e n t .  i n Dactyl i s glomerata.  Location  The a r a b l e s p e c i e s from A l a k s e n had h i g h e r  in differences spring  s t a n d i n g crops than the s p e c i e s from the P i t t and Brunswick marshes. However, f o r each s p e c i e s t h e r e was v e r y l i t t l e v a r i a t i o n i n s t a n d i n g c r o p over the t h r e e y e a r p e r i o d . 4.3.3  Discussion  The d a t a from T a b l e 4.5 c o n f i r m our o r i g i n a l  surmise t h a t  little  y e a r t o y e a r v a r i a t i o n i s t o be expected from samples t a k e n from the same s i t e on the same date a l t h o u g h between s p e c i e s and between  site  61 T a b l e 4.5  S p r i n g s t a n d i n g c r o p e s t i m a t e s of e i g h t s p e c i e s from t h r e e 2 l o c a t i o n s (g/m  d r y m a t t e r as averaged from two meter square  quadrats).  Location  B r u n s w i c k marsh  P i t t marsh  Species  May 1976  May 1977  May 1978  Carex l y n g b y e i  661  361  348  Typha l a t i f o l i a  -  381  401  Scirpus cyperinus  -  200  127  168  165  178  154  149  180  -  507  480  520  561  -  487  Carex s i t c h e n s i s Calamagros t i s canadensis P h a l a r i s arundinacea Alaksen o l d field  D a c t y l i s glomerata L o l i u m perenne  540  62 v a r i a t i o n s can be v e r y l a r g e .  The h i g h 1976 s t a n d i n g c r o p v a l u e  for  Carex l y n g b y e i can be a t t r i b u t e d i n p a r t t o i n a d e q u a t e s e p a r a t i o n o f green m a t e r i a l s from the o l d g r o w t h . The low w i t h i n s i t e v a r i a t i o n i n s t a n d i n g c r o p i s p r o b a b l y t o the r a t h e r u n i f o r m m a r i t i m e temperatures o f the c o a s t ,  related  especially  i n s p r i n g , which s h o u l d have a moderating e f f e c t on marsh water tempera t u r e hence s t i m u l a t i n g u n i f o r m g r o w t h . F u r t h e r s t u d i e s a r e n e c e s s a r y t o determine i f the s i t u a t i o n t r u e f o r o t h e r seasons o f t h e y e a r .  holds  The l a t t e r p a r t o f the y e a r i s  often  a s s o c i a t e d w i t h s u b s t a n t i a l and h i g h l y v a r i a b l e changes i n terms o f c l i m a t e , time o f f r e s h e t , magnitude o f f r e s h e t e t c . annual d i f f e r e n c e s may be of a v e r y d i f f e r e n t  4.4  In t h i s c a s e , the  order.  Q u a n t i t a t i v e E s t i m a t e s o f Dead Phytomass  R e c o g n i z i n g the u s e f u l n e s s o f dead phytomass e s t i m a t e s p a r t i c u l a r l y w i t h r e g a r d t o shoot m o r t a l i t y , net p r i m a r y p r o d u c t i o n and d e t r i t a l p r o c e s s e s , p a r t i t i o n i n g o f green and dead shoots was u n d e r t a k e n .  The  dead shoot e s t i m a t e s i n c l u d e d combined f r a c t i o n s o f dead s t a n d i n g c r o p , s u r f a c e l i t t e r and d u f f .  Such e s t i m a t e s a r e undoubtedly crude i n view  o f the l a r g e v a r i a t i o n s t o be expected i n the dead components but s h o u l d be noted t h a t s t u d i e s o f " o l d growth" i n the wetlands o f western B r i t i s h Columbia a r e s t i l l o n l y i n t h e i r y o u t h f u l  it  south  stages.  63 4.4.1  M a t e r i a l s and methods  The m a t e r i a l s and methods were s i m i l a r to those d e s c r i b e d p r e v i o u s s e c t i o n s f o r green s t a n d i n g c r o p .  in  Combined s t a n d i n g and  s u r f a c e l i t t e r and d u f f were c o l l e c t e d from d u p l i c a t e s q u a r e - q u a d r a t s  of  2 0.25m  size.  In the p r e s e n t a t i o n , the combined l i t t e r  fractions  a r e d e s i g n a t e d as o l d g r o w t h . 4.4.2  O b s e r v a t i o n s and r e s u l t s  T a b l e 4.6 shows t h a t o l d growth was p r e s e n t i n a l l sampled from the t i d a l marshes and nearby a r a b l e l a n d s the summer months.  the s p e c i e s throughout  The amount o f o l d growth i n F e s t u c a a r u n d i n a c e a  s t a n d s d e c l i n e d from May t o September.  In Carex l y n g b y e i s t a n d s ,  growth y i e l d s d e c l i n e d between May and J u l y and then i n c r e a s e d September.  The h i g h e s t o l d growth y i e l d s were r e c o r d e d i n  old  in  Festuca  arundinacea. At the d r i e r upland s i t e s , s e a s o n a l dead biomass changes were s i m i l a r to those o f Carex l y n g b y e i , t h e amount o f o l d growth  declining  from May to J u l y and then i n c r e a s i n g i n September.  arundinacea  Phalaris  accumulated more dead m a t e r i a l than L o l i u m perenne o r D a c t y l i s g l o m e r a t a . Old growth y i e l d s o f f i v e s p e c i e s sampled from the P i t t marsh i n May and October 1977 are g i v e n i n T a b l e 4 . 7 .  Except f o r Carex s i t c h e n s i s ,  t h e r e was a d e c l i n e i n o l d growth y i e l d s from May to O c t o b e r .  No d i s -  c e r n i b l e r e l a t i o n s h i p was d e t e c t e d between o l d growth a c c u m u l a t i o n and seasonal p e r i o d i c i t y o f f l o o d i n g .  However, e x a m i n a t i o n of the  soil  64 Table 4.6  Dry matter y i e l d s (g/m ) of new growth (NG) and o l d growth  (OG)  of selected species from the Fraser delta marshes and nearby arable lands, Summer 1976.  Location  Species  Iona marsh  Carex lyngbyei  Brunswick marsh  Carex lyngbyei  Festuca arundinacea  Colony Farm  Alaksen old f i e l d  II  it  Phalaris arundinacea  Lolium perenne  Dactylis glomerata  May 18-23  June 5-7  July 5-9  Sept. 16-21  NG  351  872  689  OG  201  151  301  NG  661  900  745  OG  27  24  35  NG  787  844  1125  OG  731  520  366  NG  520  714  1055  OG  1267  408  576  NG  773  688  665  OG  13  18  24  NG  520  844  OG  7  6  65  T a b l e 4.7  2 Dry m a t t e r y i e l d s (g/m ) o f new growth  (NG) and o l d growth  (OG)  o f f i v e s p e c i e s from t h e P i t t marsh, 1977.  Species  May  Scirpus acutus  Scirpus cyperinus  Carex  sitchensis  Calamagrostis canadensis  P h a l a r i s arundinacea  October  NG  *  316  OG  *  312  NG  200  1100  OG  691  330  NG  165  852  OG  453  644  NG  149  1264  OG  428  150  NG  507  1928  OG  1126  200  * under water  T a b l e 4.8  Dry m a t t e r y i e l d s (g/m ) of o l d growth f o r some s p e c i e s , 2  W i n t e r o f 1977/78.  Location  Brunswick marsh  Pitt  marsh  Alaksen o l d field  Species  Nov. 15 1977  Mar. 3 1978  % Loss Between Nov. & March  Carex l y n g b y e i  758  384  49.3  Typha l a t i f o l i a  3576  2814  21.3  Scirpus cyperinus  1260  1172  7.0  Carex s i t c h e n s i s  1230  1177  4.3  Calamagrostis canadensis  1177  1012  14.0  624  414  33.6  Agropyron repens  66  p r o f i l e showed marked f i b r o u s peat a c c u m u l a t i o n i n the w e t t e s t zones w h i l e the d r i e r s u b s t r a t e s were m a i n l y a l l u v i a l  silt.  In the w i n t e r o f 1977/78, dead biomass changes were f o l l o w e d the Brunswick and P i t t marshes and on the A l a k s e n quasi o l d The data a r e p r e s e n t e d i n T a b l e 4 . 8 .  in  field.  Measurable l o s s e s were r e c o r d e d  i n the w i n t e r d e s p i t e the many weeks o f f r e e z i n g weather which must have had a r e s t r a i n i n g e f f e c t on some a s p e c t s o f the l o s s p r o c e s s . Losses from the warmeY t i d a l marsh and a r a b l e s i t e s were h i g h e r than those from the c o l d e r P i t t marsh s i t e s .  4.4.3  Discussion  The o l d growth d a t a p r e s e n t e d , a l t h o u g h c r u d e , p o r t r a y a few t r e n d s t h a t a r e worthy o f m e n t i o n . The g e n e r a l d e c l i n e i n o l d growth y i e l d s as the season p r o g r e s s e s i s r e l a t e d i n p a r t to i n c r e a s e d d e c o m p o s i t i o n r a t e s as temperature r i s e s from s p r i n g t o summer. Decomposition appears to be p a r t i c u l a r l y a c t i v e between May and J u l y . Old growth i n c r e a s e s i n September and October (see T a b l e s 4.6 and 4.7) would be r e l a t e d t o i n c r e a s e d shoot m o r t a l i t y which takes p l a c e  towards  the end of the growing s e a s o n . A t the t i d a l marsh s i t e s , lower o l d growth v a l u e s were r e c o r d e d f o r Brunswick P o i n t compared t o Iona I s l a n d .  T i d e and f r e s h e t w a t e r s  a r e v e r y a c t i v e i n the Brunswick marsh w i t h the r e s u l t t h a t much o f dead shoot m a t e r i a l i s e x p o r t e d from the s i t e as i t f o r m s .  the  By c o n t r a s t ,  the waters o f Iona marsh a r e g e n e r a l l y l e s s t u r b u l e n t and dead shoots accumulate f o r l o n g e r  periods.  67 F e s t u c a a r u n d i n a c e a accumulated more o l d growth than Carex l y n g b y e i because o f i t s e s t a b l i s h m e n t and h i g h e r t i d e l e v e l s so t h a t i t i s o n l y o c c a s i o n a l l y s u b j e c t e d t o t i d e and storm w a t e r . T h i s g r a s s i s a l s o c o a r s e and h i g h l y f i b r o u s so t h a t i t rather  degrades  slowly.  Death and d e g r a d a t i o n o f t h e shoots o f the g r a s s e s from t h e upland s i t e s o c c u r r e d throughout the s a m p l i n g p e r i o d but a t no time i n summer was t h e r e any marked o l d growth a c c u m u l a t i o n .  The high temperatures  in  t h e s e s i t e s undoubtedly encourage more m i c r o b i a l a c t i v i t y and comminution by s o i l o r g a n i s m s .  P h a l a r i s a r u n d i n a c e a had h i g h e r o l d growth y i e l d s  because i t i s more f i b r o u s than L o l i u m perenne and D a c t y l i s g l o m e r a t a . From the high dead phytomass e s t i m a t e s and low percentage r e c o r d e d a t the P i t t marsh s i t e s  losses  (Tables 4.7 and 4 . 8 ) , i t appears t h a t  d e c o m p o s i t i o n r a t e s a r e much s l o w e r a t t h e s e s i t e s compared t o the marsh and a r a b l e s i t e s .  tidal  Slower d e c o m p o s i t i o n r a t e s a t the P i t t marsh  may be r e l a t e d t o many f a c t o r s among which a r e absence o f t i d a l  action  hence l e s s f r a g m e n t a t i o n and lower mean monthly temperatures hence l e s s m i c r o b i a l a c t i v i t y and l e s s o x i d a t i o n . I t s h o u l d be emphasized a t t h i s p o i n t t h a t the study of dynamics i s a complex one.  Satchel!  litter  (1967) o f f e r e d a condensed r e v i e w  of l i t t e r i n t e r f a c e o f animate and i n a n i m a t e m a t t e r and i t s  relevance  t o agronomy, p o l l u t i o n and o t h e r ecosystem p r o c e s s e s .  He p o i n t e d out  t h a t l i t t e r p r o c e s s e s a r e o f t e n complex and p r o l o n g e d ,  initiating  f r e q u e n t l y b e f o r e death a t r a t e s which depend on the p l a n t s u b s t r a t e as w e l l as the c h a r a c t e r i s t i c s o f the environment.  The meaning o f  68 " l i t t e r " i t s e l f i s o b s c u r e (Rodin and B a z i l e v i c h 1961) and the same c r i t e r i a * cannot be used i n a l l  h a b i t a t s so t h a t any d e f i n i t i o n  must be r e g a r d e d as a r b i t r a r y .  I t i s c l e a r nonetheless that the  litter  4.5  item c o n s t i t u t e s an i m p o r t a n t p r o c e s s i n these w e t l a n d s .  Belowground Phytomass  I t appears t h a t the phytomass ( r o o t and rhizome)  belowground  comprises a l a r g e and major p a r t o f the t o t a l phytomass o f a g i v e n a r e a o f w e t l a n d ( G a l l a g h e r 1974).  The belowground f r a c t i o n  c e r t a i n l y much l a r g e r than t h a t commonly found i n w e l l s u b s t r a t e s such as a r a b l e l a n d s .  A somewhat s i m i l a r  is  drained  fractionation  has been r e c o r d e d i n the phytomass o f h i g h l a t i t u d e and high a l t i t u d e zones (Rodin and B a z i l e v i c h 1 9 6 7 ) .  I t i s t o be noted t h a t phytomass  p r o d u c t i o n s t u d i e s i n w e t l a n d s have tended to i g n o r e fractions  belowground  (de l a Cruz and Hackney 1977) presumably because o f  the  d i f f i c u l t i e s o f w o r k i n g i n the 'mud and w a t e r ' and a l s o because of the d i f f i c u l t y i n s e p a r a t i n g l i v i n g from dead p l a n t m a t e r i a l .  In view  o f the importance o f r o o t s and rhizomes p a r t i c u l a r l y as energy s t o r a g e o r g a n s , attempts were made t o determine y i e l d s and (2)  the amount o f  (1)  belowground phytomass  ' a v a i l a b l e ' or r e a d i l y hydrolyzable  c a r b o h y d r a t e s i n the belowground o r g a n s .  4.5.1  M a t e r i a l s and methods  2 Aboveground s t a n d i n g shoots were h a r v e s t e d from 0.25m i n November 1977.  quadrats  Roots and rhizomes were sampled from the same  69 q u a d r a t s by t a k i n g c o r e s w i t h a p l u g g e r t o a depth of 30 cm. p l u g g e r c o r e s had a diameter o f 8.5 cm. each q u a d r a t .  The  Two c o r e s were taken from  Each c o r e was c u t i n t o two 15 cm s e c t i o n s i n t h e  f i e l d , bagged and t r a n s p o r t e d t o the U n i v e r s i t y o f B r i t i s h Columbia P l a n t S c i e n c e F i e l d Lab where they were washed i n a s p e c i a l l y d e s i g n e d r o o t washing machine employing water j e t s and s i e v e s .  Successful  s e p a r a t i o n o f l i v i n g and dead m a t e r i a l s c o u l d not be a c h i e v e d w i t h c o n s i s t e n c e hence the two f r a c t i o n s were combined, d r i e d a t 60 G and weighed.  R e s u l t s a r e r e p o r t e d as belowground d r y m a t t e r per  0.25m . 2  ' A v a i l a b l e ' o r r e a d i l y h y d r o l y z a b l e c a r b o h y d r a t e s were e s t i m a t e d by the p h e n o l - s u l p h u r i c a c i d method d e s c r i b e d by B a r n e t t  (1954);  absorbance was read a t 480 nm w i t h a P e r k i n - E l m e r double beam spectrophotometer.  4.5.2  O b s e r v a t i o n s and r e s u l t s  D e s p i t e the d i f f i c u l t y i n s e p a r a t i n g l i v i n g from dead belowground phytomass i t was apparent t h a t most o f the m a t e r i a l i n c l u d e d was l i v i n g o r near l i v i n g .  F u r t h e r m o r e , d e s p i t e the l a t e n e s s o f  the  h a r v e s t , aboveground dry m a t t e r y i e l d s determined p r o b a b l y p r o v i d e d a crude e s t i m a t e o f peak s t a n d i n g c r o p s . The data g i v e n i n T a b l e 4.9 show t h a t most o f the  belowground  phytomass tended t o be c o n c e n t r a t e d i n the upper ( 0 - 1 5 cm) h o r i z o n s o f the s u b s t r a t e . Carex s i t c h e n s i s had the h i g h e s t t o t a l belowground phytomass  70 Table 4.9  Belowground phytomass  (dry wt.  basis)  of  f r o m B r u n s w i c k m a r s h , P i t t marsh and P i t t November  selected old  species  field,  1977.  Belowground phytomass by c o r e  0 - 1 5  15 -  cm  Location  Species  Brunswick marsh  Scirpus  it  Pitt  marsh  ii  g/0.25m  americanus  30  depth*  Total  cm  %  g/0.25m  721  84  139  16  860  2  2  %  Carex  lyngbyei  1127  89  146  11  1273  Typha  latifolia  1418  85  248  15  1666  1080  58  786  42  1866  1862  88  248  12  2110  1252  64  717  36  1969  Scirpus Carex  cyperinus  sitchensis  II  Calamagrostis  II  Juncus  effusus  320  94  21  6  596  Lolium  perenne  302  100  0  0  302  Pitt old field  * values are averages of  canadensis  two  samples  71 w h i l e L o l i u m perenne, a d r y l a n d s p e c i e s , had the l o w e s t v a l u e . Roots and rhizome w e i g h t s o f Juncus e f f u s u s and S c i r p u s americanus were lower than those o f o t h e r wetland s p e c i e s . Except i n L o l i u m perenne and S c i r p u s a m e r i c a n u s , t o t a l phytomass exceeded aboveground s t a n d i n g phytomass i n a l l examined ( T a b l e 4 . 1 0 ) .  belowground  the s p e c i e s  The L o l i u m perenne s t a n d had been g r a z e d  p r i o r t o sampling w h i l e the shoots o f S c i r p u s americanus had been a l m o s t c o m p l e t e l y washed o f f by t i d e s .  The r a t i o s o f belowground  to  aboveground phytomass were i n the range o f 7:1 f o r a l l w e t l a n d s p e c i e s e x c e p t Juncus e f f u s u s and Typha l a t i f o l i a . Percentage e s t i m a t e s o f  ' a v a i l a b l e ' carbohydrates i n  organs a r e g i v e n i n T a b l e 4 . 1 1 .  belowground  These e s t i m a t e s were g e n e r a l l y h i g h e r  i n the upper than i n the lower s e c t i o n s . In n o t i n g the r a t h e r anomalous data f o r Juncus e f f u s u s , i t  should  be r e c a l l e d t h a t under our c o n d i t i o n s , t h i s s p e c i e s i s c a e s p i t o s e and remains v i r t u a l l y green i n w i n t e r growing m a i n l y i n a r a b l e o l d  fields.  In t h e s e r e s p e c t s , Juncus e f f u s u s i s d i f f e r e n t from the o t h e r w e t l a n d s p e c i e s examined.  4.5.3  Discussion  A l t h o u g h l i v i n g and dead p l a n t m a t e r i a l s c o u l d not be s e p a r a t e d , our data appear t o s u p p o r t G a l l a g h e r ' s (1974) o b s e r v a t i o n t h a t belowground phytomass o f w e t l a n d s i t e s o f t e n comprises a v e r y l a r g e o f the t o t a l phytomass.  fraction  The belowground v a l u e s r e c o r d e d are a l s o  g e n e r a l l y much g r e a t e r than those r e p o r t e d f o r g r a s s l a n d s . ejt al_. (1963) r e p o r t e d 500 - 1200 g/m  Ovington  i n c e n t r a l M i n n e s o t a , Dahlman  72 T a b l e 4.10  R a t i o o f belowground t o aboveground phytomass o f s e l e c t e d s p e c i e s from B r u n s w i c k marsh, P i t t marsh and P i t t o l d f i e l d , November 1977.  Location  Species  Belowground phytomass g/0.25m 2  Aboveground standing phytomass g/0.25m 2  Brunswick marsh  Pitt marsh  Pitt old field  Scirpus americanus  Ratio of belowground to aboveground phytomass  860  Carex lyngbyei  1273  189  Typha latifolia  1666  894  Scirpus cyperinus  1866  315  Carex sitchensis  2110  294  Calamagrostis canadensis  1969  294  Juncus effusus  341  596  Lolium perenne  302  <1  0.6  73 T a b l e 4.11  Percent of r e a d i l y h y d r o l y z a b l e carbohydrates  ( d r y wt  basis)  i n belowground phytomass o f s e l e c t e d s p e c i e s from B r u n s w i c k marsh, P i t t marsh and P i t t o l d f i e l d , November  Location  Species  1977.  % Readily hydrolyzable c a r b o h y d r a t e s i n belowground phytomass*  0-15  15-30  cm  cm  B r u n s w i c k marsh  S c i r p u s americanus  14.1  12.2  !!  11  Carex l y n g b y e i  30.8  10.1  tl  II  Typha l a t i f o l i a  25.8  18.3  P i t t marsh  Scirpus  24.3  14.3  II  Carex s i t c h e n s i s  26.2  13.8  II  Calamagrostis  20.3  13.1  II  Juncus e f f u s u s  18.6  19.2  Pitt old field  L o l i u m perenne  13.9  -  cyperinus  * V a l u e s a r e averages o f two  canadensis  samples  -  74 and Kucera (1965) r e p o r t e d 1400 - 1900 g/m  2  in Missouri, while  2 W i e g e r t and McGinnis (.1975) r e p o r t e d 278 - 525 g/m  i n South C a r o l i n a .  Our belowground v a l u e s a r e somewhat h i g h e r than t h o s e r e p o r t e d by Bernard and MacDonald (1974) f o r a f r e s h w a t e r Carex r o s t r a t a w e t l a n d but lower than those g i v e n by Broome ejt al_. (1975) and de l a Cruz and Hackney (1977) f o r some s a l t marshes i n e a s t e r n U n i t e d S t a t e s .  These 2  workers r e p o r t e d belowground phytomass range of 7000 - 10000 g/m the s a l t marshes they s t u d i e d .  for  The lower v a l u e s o b s e r v e d f o r S c i r p u s  americanus c o u l d be a s s o c i a t e d w i t h s p e c i a l f e a t u r e s o f the environment as i n the case o f Juncus e f f u s u s .  S c i r p u s americanus i s found seawards  from Carex l y n g b y e i and i n our s i t e the stands a r e s u b j e c t t o f r e q u e n t silt  coverage. Our belowground/aboveground phytomass r a t i o s a r e between those g i v e n  by McNaughton (1966) and T y l e r (1971) but are not as h i g h as those g i v e n by W i e l g o l a s k i  (1972) f o r some a r c t i c communities.  Much o f the p l a n t m a t e r i a l s from the lower h o r i z o n s of o u r c o r e s appeared t o be dead and low i n s t o r a g e t i s s u e which p r o b a b l y accounted f o r t h e i r low l e v e l s o f h y d r o l y z a b l e c a r b o h y d r a t e s . The s i g n i f i c a n c e o f the h i g h belowground phytomass r e c o r d e d here appears t o l i e i n the a b i l i t y o f many emergent s p e c i e s t o s t o r e l a r g e energy r e s e r v e s i n underground o r g a n s .  M i s s Kathy Kennedy  (unpublished  w o r k ) , a f e l l o w s t u d e n t a t the U n i v e r s i t y of B r i t i s h C o l u m b i a , examined the " f o o d " r e s e r v e s of a number o f w e t l a n d s p e c i e s on t h e e a s t c o a s t o f Vancouver I s l a n d u s i n g c o r e s and an e t i o l a t i o n t e c h n i q u e (Marx 1 9 6 3 ) . She found up t o 550 days were r e q u i r e d to exhaust the belowground r e s e r v e s o f w e t l a n d s p e c i e s w h i l e those from a r a b l e g r a s s l a n d s were  75 exhausted i n o n l y 30 d a y s .  I t may w e l l be t h a t w e t l a n d s p e c i e s have  e v o l v e d a " s t r a t e g y " o f l a r g e energy s t o r a g e belowground to meet t h e many e n v i r o n m e n t a l s t r e s s e s t o which they are f r e q u e n t l y s u b j e c t e d . The r e s e r v e s may a l s o a i d i n e a r l y e s t a b l i s h m e n t a t the b e g i n n i n g o f the growing season (Mooney and B i l l i n g s 1960, Fonda and B l i s s  4.6  1966).  C a l o r i c Content o f Some Emergent S p e c i e s  I t appears t h a t s t a n d i n g crop e s t i m a t e s s h o u l d be supplemented w i t h energy d e t e r m i n a t i o n s so t h a t p r o d u c t i v i t y v a l u e s can be c o n v e n i e n t l y e x p r e s s e d i n these t e r m s .  Q u a n t i t a t i v e l y , energy i s  i n the o v e r a l l s u b j e c t o f ecosystem f u n c t i o n s . 'available'  important  While i t i s t r u e t h a t  or ' d i g e s t i b l e ' energy i s more i m p o r t a n t i n t h i s r e g a r d ,  knowledge o f the g r o s s energy i n s t a n d i n g c r o p s can be u s e f u l i n an e x p l o r a t o r y study o f the k i n d r e p o r t e d i n t h i s  especially  thesis.  From numerous r e p o r t s i n the l i t e r a t u r e , i t appears t h a t t h e r e ' i s l i t t l e c a l o r i c v a r i a t i o n i n a l a r g e number o f w e t l a n d and t e r r e s t r i a l p l a n t communities i r r e s p e c t i v e o f s p e c i e s , s i t e o r s t a g e o f m a t u r i t y (Boyd 1968, 1969a, 1970b; de l a Cruz 1975, G o l l e y 1961). A n a l y s e s o f the energy v a l u e s o f some lower mainland communities were done t o determine whether they conform t o t h e s e e s t a b l i s h e d t r e n d s .  4.6.1  M a t e r i a l s and methods  C a l o r i c v a l u e s were determined i n some ground samples u s i n g a P a r r A d i a b a t i c Bomb C a l o r i m e t e r a c c o r d i n g to methods d e s c r i b e d i n P a r r T e c h n i c a l Manual No. 3 1 .  76 4.6.2  O b s e r v a t i o n s and r e s u l t s  No major energy changes were r e c o r d e d i n a l l the two s a m p l i n g dates (Table 4 . 1 2 ) . fell  the s p e c i e s  On the whole the c a l o r i c v a l u e s  w i t h i n a narrow range o f 4.4 K c a l / g o f dry m a t t e r .  s l i g h t f l u c t u a t i o n s were r e c o r d e d .  during  Only v e r y  Calamagrostis canadensis,  Juncus  e f f u s u s and Carex l y n g b y e i had h i g h e r c a l o r i c v a l u e s i n May compared to October.  The r e v e r s e was t r u e f o r S c i r p u s a c u t u s , Typha  and D a c t y l i s g l o m e r a t a .  latifolia  Energy v a l u e s f o r P h a l a r i s a r u n d i n a c e a and  S c i r p u s c y p e r i n u s remained c o n s t a n t .  4.6.3  Discussion  In a l a r g e number o f macrophytes the gross energy l e v e l has been found t o v a r y o n l y s l i g h t l y w i t h s p e c i e s , age o r s i t e .  For example,  Boyd (1968) r e p o r t e d an average 4 . 3 Kcal/gm f o r v a r i o u s a q u a t i c macrophytes.  De l a Cruz (1975) found the c a l o r i c c o n t e n t o f S p a r t i n a  c y n o s u r o i d e s and S c i r p u s americanus t o range between 4.2 - 4.6 K c a l / g . S q u i r e s and Good (1974) gave a s e a s o n a l average o f 3.9 K c a l / g  in  S p a r t i n a a l term" f l o r a . The c a l o r i c v a l u e s o b t a i n e d i n t h e s t u d y r e p o r t e d here compare w e l l w i t h those i n the l i t e r a t u r e f o r a l m o s t any k i n d of p l a n t m a t e r i a l , the g e n e r a l range being from 4.0 t o 4.6 K c a l / g o f dry m a t t e r . S i n c e t h e r e i s l i t t l e seasonal d i f f e r e n c e  in c a l o r i c values,  it  can be concluded t h a t the c a l o r i c s t a n d i n g c r o p i s m e r e l y a f u n c t i o n of dry matter production.  Organisms u t i l i z i n g the w e t l a n d p l a n t s as a  food source consume an amount o f t o t a l energy t h a t i s r o u g h l y p r o p o r t i o n a l t o the q u a n t i t y o f d r y m a t t e r i n t a k e .  77 Table 4.12  Seasonal changes i n energy content (Kcal/g) of the standing crop of some emergents from several locations,  Location  Species  P i t t marsh  Calamagrostis  ii  ii  ii  1977.  May  October  4.6 *  4.4  Phalaris arundinacea  4.4  4.4  II  Scirpus acutus  4.4  4.7  II  it  Scirpus cyperinus  4.5  4.5  ii  ii  Juncus effusus  4.6  4.2  Brunswick marsh  Carex lyngbyei  4.5  4.4  II  Typha l a t i f o l i a  4.2  4.4  Dactylis  4.3  4.4  II  Alaksen o l d f i e l d  canadensis  glomerata  Data are averages of two samples.  78 5.  DISPOSITION OF EMERGENT VEGETATION  As a r e s u l t o f the p h o t o s y n t h e t i c p r o c e s s i n which r a d i a n t energy i s t r a n s f o r m e d i n t o chemical e n e r g y , the p l a n t m a t e r i a l produced may o c c u r as l i v i n g m a t t e r o r as dead m a t t e r .  The d i s p o s i t i o n i n the b i o -  sphere o f the phytomass thus formed may t a k e s e v e r a l r o u t e s . n a t u r a l c o n d i t i o n s , t h e major r o u t e s o f "return" f o r communication purposes a r e : (2)  (1)  the a c c u m u l a t i o n r o u t e , and (3)  Under  commonly i d e n t i f i e d  the g r a z i n g - b r o w s i n g r o u t e , the d e t r i t a l  route.  In g r a z i n g and b r o w s i n g , p r e d o m i n a n t l y l i v i n g phytomass i s consumed, u s u a l l y i n s i t u , by v a r i o u s k i n d s o f h e r b i v o r e s r a n g i n g from l a r g e ungulates to very small i n v e r t e b r a t e s . A c c u m u l a t i o n i n v o l v e s i n c o r p o r a t i o n o f dead phytomass i n t o t h e s u b s t r a t e as l i g n i t e , c o a l , p e t r o l e u m , peat and p e a t - l i k e m a t e r i a l s . The d e t r i t a l r o u t e o f t e n commences w i t h comminution o r fragment a t i o n o f dead phytomass by e n e r g e t i c p r o c e s s e s such as t r a m p l i n g , w i n d , t i d a l a c t i v i t y and r u n n i n g w a t e r .  During f r a g m e n t a t i o n ,  large  p l a n t s u r f a c e s a r e exposed t o the a c t i o n o f the wide a r r a y o f decomposer organisms.  The p a r t i c u l a t e m a t t e r r e s u l t i n g from t h e s e p r o c e s s e s may  e i t h e r remain i n s i t u o r i t may be e x p o r t e d to o t h e r h a b i t a t s by the same e n e r g e t i c f o r c e s which b r i n g about f r a g m e n t a t i o n . No sharp d i v i s i o n s can be drawn between g r a z i n g , a c c u m u l a t i o n and d e t r i t a l systems.  What c o n s t i t u t e s dead t i s s u e i s a m a t t e r o f c o n -  t r o v e r s y and death may come from " n o r m a l " p h y s i o l o g i c a l p r o c e s s e s o r from o t h e r causes such as f u n g a l i n f e c t i o n s .  D e s p i t e these a m b i g u i t i e s ,  we c o n s i d e r e d i d e n t i f i c a t i o n o f the t h r e e r o u t e s o f p l a n t relevant to studies of wetland processes.  disposition  79 5.1  G r a z i n g o f Emergent V e g e t a t i o n  P a r t o f the energy from emergent v e g e t a t i o n would be expected t o be c h a n n e l l e d through the c l a s s i c a l  ' g r a z i n g ' food c h a i n .  The s u p p l y  o f food d i r e c t l y to a n i m a l s g r a z i n g the l i v i n g p l a n t t i s s u e s appear t o v a r y i n importance from w e t l a n d t o w e t l a n d as do the g r a z e r s t h e m s e l v e s . Our f i n d i n g s , based l a r g e l y on o b s e r v a t i o n s , showed g r a z i n g t o be minimal on the F r a s e r d e l t a t i d a l marshes.  Some o f the green shoots  of Carex l y n g b y e i were s p a r i n g l y n i p p e d by widgeon and o t h e r n a t i v e geese.  Much o f the g r a z i n g e s p e c i a l l y by w a t e r f o w l appeared t o take  place in winter.  Burgess (1970) and Burton (1977) r e p o r t e d s i m i l a r  heavy g r a z i n g o f S c i r p u s americanus i n the w i n t e r months.  local  Other h e r -  b i v o r e s r a n g i n g from i n s e c t s t o earthworms and shrimps were a l s o found i n the t i d a l marshes.  Most o f the s p e c i e s o b s e r v e d were not  identified  and t h e i r r o l e s i n the marshes have not been documented. D e s c r i p t i o n o f the v e r t e b r a t e and i n v e r t e b r a t e fauna o f the F r a s e r d e l t a marshes a r e c u r r e n t l y b e i n g assembled by the Canadian W i l d l i f e S e r v i c e ( A l a k s e n ) , Westwater Research C e n t r e ( U n i v e r s i t y o f B r i t i s h Columbia) and the P a c i f i c Environment I n s t i t u t e (North V a n c o u v e r ) . G r a z i n g by lower and h i g h e r a n i m a l s a l s o appeared t o be minimal t h e P i t t marsh.  in  Numerous s m a l l a n i m a l s were observed i n t h e marsh.  Some p o l l e n c o l l e c t i n g i n s e c t s were a l s o found i n l a r g e numbers.  Many  r e s i d e n t and m i g r a n t b i r d s were f r e q u e n t l y s i g h t e d i n the marsh a l t h o u g h they appear t o f e e d more on n e i g h b o u r i n g a g r i c u l t u r a l l a n d s ( B a r n a r d 1975). In c o n t a s t t o the wetland s p e c i e s , marked g r a z i n g by w a t e r f o w l , g a s t r o p o d s and i n s e c t s was noted i n p l a n t s of the nearby a g r i c u l t u r a l  old  80  fields.  The p a s t u r e s a t A l a k s e n a r e p r i m a r i l y managed f o r  waterfowl  w h i l e those a t Colony Farm a r e f r e q u e n t l y g r a z e d by d a i r y cows.  5.2  A c c u m u l a t i o n o f Emergent V e g e t a t i o n i n the S u b s t r a t e  Some r e f e r e n c e has a l r e a d y been made under S e c t i o n 4.4 t o the a c c u m u l a t i o n o f phytomass i n the s i t e s s t u d i e d . In the t i d a l marshes, e a r l y s p r i n g e x a m i n a t i o n showed t h a t water movements o v e r t h e p l a n t c o v e r had l e d t o s e e m i n g l y c a p r i c i o u s removal o f dead p l a n t m a t e r i a l .  C l o s e t o c h a n n e l s , the c o v e r had been swept  c l e a n o f dead shoots w h i l e i n areas where storm and t i d a l a c t i o n s were l e s s v i g o r o u s a c c u m u l a t i o n o f dead fragements o c c u r r e d .  Comminution,  a c c u m u l a t i o n and e x p o r t was o b v i o u s l y v a r i a b l e even o v e r s h o r t d i s t a n c e s . Examination o f the s u b s t r a t e a l o n g the c h a n n e l s showed some r e c o g n i z a b l e r o o t and shoot a c c u m u l a t i o n s a l t h o u g h a g a i n the d i s t r i b u t i o n and thickness of accumulation v a r i e d g r e a t l y . In the P i t t marsh, e x a m i n a t i o n o f the s o i l p r o f i l e showed marked f i b r o u s peat a c c u m u l a t i o n i n the w e t t e s t z o n e s . consisted mainly of a l l u v i a l s i l t  The d r i e r  substrates  deposits.  A c c u m u l a t i o n o f o r g a n i c m a t t e r appears then t o be c h a r a c t e r i s t i c o f both the f r e s h w a t e r ( F i g u r e 5.1) and b r a c k i s h t i d a l marshes 5.2).  (Figure  Even a t the Brunswick marsh where a s u b s t a n t i a l p o r t i o n o f the  l i t t e r i s e x p o r t e d by t i d a l a c t i o n , c o n s i d e r a b l e o r g a n i c m a t t e r a c c u m u l a t i o n s a r e encountered i n some a r e a s .  81  Figure 5.1:  A c c u m u l a t i o n o f O r g a n i c M a t t e r i n the P i t t marsh (Summer 1976).  Old Growth V i s i b l e on t o p ; A c c u m u l a t i o n  S u b s t r a t e P r o f i l e o v e r 1 m deep.  in  82  83  Figure 5.2:  A c c u m u l a t i o n o f O r g a n i c M a t t e r i n the Brunswick marsh.  Top photo:  o v e r w i n t e r e d l i v i n g " s p i k e s " and dead shoots o f Carex l y n g b y e i ; most o f o.fn. has been washed away by w i n t e r storm and t i d e .  Bottom photo:  l o c a l i z e d accumulation of Zostera maritima, Carex l y n g b y e i , e t c . , about 1 m deep.  85 5.3  Decomposition o f Emergent V e g e t a t i o n  In many s t a b l e o r s t e a d y s t a t e ecosystems such as those i n many g r a s s l a n d s , the phytomass produced i n a season u s u a l l y undergoes more o r l e s s complete d e g r a d a t i o n through o x i d a t i o n , f i r e and/or g r a z i n g . In w e t l a n d systems o p p o r t u n i t y f o r d e g r a d a t i o n by these p r o c e s s e s o f t e n so markedly reduced t h a t phytomass i n v a r i o u s s t a t e s accumulation i s encountered.  is  of  Some of the phytomass undergoes d e g -  r a d a t i o n o r breakdown t o p a r t i c u l a t e forms t h a t can be termed d e t r i t u s . Odum and de l a Cruz (1963) d e f i n e d the term d e t r i t u s as dead p a r t i c u l a t e o r g a n i c m a t t e r p l u s i t s a s s o c i a t e d m i c r o f l o r a and f a u n a .  The d e g r a d a t i o n  ( o r d e c o m p o s i t i o n o r decay) o f p l a n t m a t e r i a l to p a r t i c u l a t e forms  is  a complex, c o n t i n u o u s p r o c e s s i n v o l v i n g numerous b i o t i c and a b i o t i c e v e n t s which can be approached i n many d i f f e r e n t ways.  We c o n s i d e r e d  r a t e and l o c a t i o n o f the d e c o m p o s i t i o n p r o c e s s t o be i m p o r t a n t v a r i a b l e s in c h a r a c t e r i z i n g wetland s i t e s . investigations: (2)  (1)  We employed two t e c h n i q u e s i n our  the ' l i t t e r bag' t e c h n i q u e (Kormondy 1 9 6 8 ) , and  the i n v i t r o o r g a n i c m a t t e r l o s s t e c h n i q u e ( B u r k h o l d e r and B o r n s i d e  1957).  5.3.1  Decomposition s t u d i e s u s i n g l i t t e r bags  Decomposition s t u d i e s have been examined i n a number o f e n v i r o n ments i n c l u d i n g t e r r e s t r i a l  ( L a t t e r and Cragg 1967), s a l t marsh (de  l a Cruz and G a b r i e l 1974) and stream (Boyd 1970a) u s i n g the so c a l l e d l i t t e r bag method.  In t h i s , as i n many s i m i l a r s t u d i e s , i t was assumed  86 t h a t changes i n w e i g h t o f the decomposing p l a n t s i n l i t t e r bags would be s i m i l a r t o changes i n t h e s e m a t e r i a l s o u t s i d e the bags.  5.3.1.1  M a t e r i a l s and methods  F i e l d d e c o m p o s i t i o n o f p l a n t m a t e r i a l was determined by means o f the ' l i t t e r b a g  1  method f r e q u e n t l y employed i n t h i s type of  study.  Samples o f P h a l a r i s a r u n d i n a c e a , Carex s i t c h e n s i s , S c i r p u s a c u t u s , Juncus e f f u s u s  ( a l l from P i t t m a r s h ) ; Carex l y n g b y e i (from Brunswick  m a r s h ) ; and D a c t y l i s g l o m e r a t a (from A l a k s e n ) were h a r v e s t e d and chopped i n t o a p p r o x i m a t e l y 7 cm segments on 9 A u g u s t , 1977.  Natural  decomposition  o f c u r r e n t y e a r ' s s t a n d i n g c r o p g e n e r a l l y proceeds a t an a p p r e c i a b l e r a t e from t h e b e g i n n i n g o f autumn when most shoots d i e .  The m a t e r i a l s  c o l l e c t e d from t h i s study were a t a l a t e s t a g e of m a t u r i t y and hence presumed t o be p h y s i o l o g i c a l l y dead o r c l o s e t o death ready t o go through the d e c o m p o s i t i o n phase.  Known w e i g h t s o f shoot m a t e r i a l were e n c l o s e d  i n 15 x 20 cm n y l o n bags w i t h 3 mm mesh. plastic labels.  The bags were i d e n t i f i e d u s i n g  The bags (24 f o r each s p e c i e s ) were grouped i n t o t h r e e ;  one group t o be taken t o Brunswick marsh, a n o t h e r t o A l a k s e n and the f i n a l group t o P i t t m a r s h .  On 10 A u g u s t , 1977, t h e y were t a k e n t o these  t h r e e l o c a t i o n s and l o o s e l y p l a c e d on the s u r f a c e o f the s u b s t r a t e . Two bags per s p e c i e s were removed from each l o c a l i t y a f t e r 74 days exposure i n the f i e l d  (23 O c t o b e r , 1977).  A s i m i l a r c o l l e c t i o n was  made on 5 J a n u a r y , 1978 ( a f t e r 148 days) and the e x p e r i m e n t was t e r m i n a t e d on 1 J u n e , 1978 ( a f t e r 294 d a y s ) .  87  In the l a b o r a t o r y , the bags were opened and the samples c l e a n e d o f sand.  V i s i b l e i n s e c t s and o t h e r i n v e r t e b r a t e s were a l s o removed.  The  samples were d r i e d to c o n s t a n t w e i g h t , weighed and ashed. Weight l o s s e s due to l e a c h i n g , f r a g m e n t a t i o n by m i c r o b i a l  activity,  escape o f p a r t i c l e s from the b a g s , e t c . , were i n t e r p r e t e d as d e c o m p o s i t i o n rates. To assess the magnitude o f d e c o m p o s i t i o n r a t e s below the s u b s t r a t e s u r f a c e , a n o t h e r e x p e r i m e n t was c a r r i e d o u t on dead v e g e t a t i o n . e x p e r i m e n t i n v o l v e d three s p e c i e s : and D a c t y l i s g l o m e r a t a .  The  P h a l a r i s a r u n d i n a c e a , Carex l y n g b y e i  The samples were h a r v e s t e d , t r e a t e d as d e s c r i b e d  above, taken to the t h r e e l o c a t i o n s and b u r i e d a p p r o x i m a t e l y 15 cm deep i n the s u b s t r a t e on 24 O c t o b e r , 1977.  H a l f o f the bags (two f o r each  s p e c i e s ) were r e t r i e v e d a f t e r 73 days (5 J a n u a r y , 1978) and the r e s t were c o l l e c t e d on 1 J u n e , 1978 ( a f t e r 146 d a y s ) .  5.3.1.2  O b s e r v a t i o n s and r e s u l t s  R e s u l t s of d e c o m p o s i t i o n i n l i t t e r bags are g i v e n i n Appendices I and III.  A n a l y s e s o f v a r i a n c e are p r e s e n t e d i n Appendices  I I and IV.  The f i r s t 74 days o f i n s i t u s u r f a c e d e c o m p o s i t i o n w i t n e s s e d a r a p i d l o s s o f o r g a n i c m a t t e r by a l l  the s p e c i e s s t u d i e d ( F i g u r e 5 . 3 ) .  The l o s s  was s l i g h t a f t e r t h i s p e r i o d u n t i l 5 J a n u a r y , 1978 (148 days) when s t a r t e d to i n c r e a s e a g a i n .  it  The percentages o f o r g a n i c m a t t e r decomposed  t o October and t o January were s i m i l a r a v e r a g i n g 24.4% and 26.5% r e s p e c t i v e l y b u t by 1 J u n e , 1978 up t o 54.1% o f the o r i g i n a l m a t t e r had decomposed (Table  5.1).  organic  88 T a b l e 5.1  Summary o f t h e Main E f f e c t s o f L i t t e r Bag D e c o m p o s i t i o n , Where Bags were P l a c e d on t h e S u b s t r a t e S u r f a c e .  % organic matter decomposed  Main E f f e c t  Time  Location  Species  74 day d e c o m p o s i t i o n  24.4 a *  148 day d e c o m p o s i t i o n  26.5 a  294 day d e c o m p o s i t i o n  54.1 b  Brunswick marsh  36.1 a  P i t t marsh  34.2 a  Alaksen o l d f i e l d  34.7 a  Carex  20.7 a  sitchensis  Juncus e f f u s u s  31.5 b  Scirpus acutus  32.7 b  Phalaris  33.4 b  arundinacea  Carex l y n g b y e i  39.4 c  Dactylis  52.4 d  glomerata  * f o r each main e f f e c t , means f o l l o w e d by t h e same l e t t e r s a r e not s i g n i f i c a n t l y d i f f e r e n t (P < 0.01) by Newman-Keul's m u l t i p l e range t e s t . The mean f o r each main e f f e c t i s an average of a l l o b s e r v a t i o n s on t h a t e f f e c t i r r e s p e c t i v e o f the o t h e r f a c t o r s .  Decomposition i n L i t t e r Bags P l a c e d on the Substrate Surface.  Carex  sitchensis  O-O  Scirpus  Q-a  Phalaris  m—m  Juncus  acutus arundinacea effusus  Carex l y n g b y e i Dactyl i s  glomerata  91 The amount o f o r g a n i c m a t t e r decomposed v a r i e d w i t h s p e c i e s . The l o w e s t v a l u e s were r e c o r d e d f o r the s p e c i e s from P i t t marsh f o l l o w e d by Carex l y n g b y e i (Brunswick marsh) and D a c t y l i s (Alaksen o l d f i e l d ) .  D a c t y l i s g l o m e r a t a l o s t 50% o f i t s  glomerata original  w e i g h t i n about 187 days w h i l e Carex l y n g b y e i shoots took 234 days t o l o s e t h i s amount ( F i g u r e 5 . 3 ) .  By the end o f the e x p e r i m e n t a l  p e r i o d (1 J u n e , 1978) most o f t h e shoots were d e v o i d o f l e a v e s and d r y w e i g h t l o s s e s had reached v a l u e s as h i g h as 83.3%. Appendix I I shows t h a t t h e r e were s i g n i f i c a n t  interactions  (P < 0.01) i n terms o f t i m e x l o c a t i o n and time x s p e c i e s . The changes i n o r g a n i c m a t t e r l o s s e s w i t h time f o r b u r i e d samples p a r a l l e l e d those p l a c e d a t the s o i l s u r f a c e (Table 5 . 2 ) .  However by  comparing T a b l e s 5.1 and 5 . 2 , t h r e e major d i f f e r e n c e s i n the p a t t e r n s o f w e i g h t l o s s were d i s c e r n e d .  F i r s t l y , the a b s o l u t e  decomposition  l o s s e s were much l e s s i n b u r i e d samples compared to those p l a c e d on the s o i l s u r f a c e .  S e c o n d l y , w h i l e d e c o m p o s i t i o n r a t e s o f samples  p l a c e d on the s o i l s u r f a c e d i d not v a r y w i t h s i t e s , b u r i e d samples decomposed much f a s t e r a t A l a k s e n o l d f i e l d s i t e than those a t marsh and Brunswick marsh s i t e s .  F i n a l l y , t h e amount o f  Pitt  organic  m a t t e r decomposed v a r i e d w i t h s p e c i e s f o r s u r f a c e samples but the p a t t e r n was s i m i l a r f o r b u r i e d samples i r r e s p e c t i v e of  5.3.1.3  species.  Discussion  I t has been r e p o r t e d t h a t i n l i t t e r bag s t u d i e s ,  significant  l o s s e s may o c c u r as p l a n t fragments escape through the bags (Kormondy 1968).  The i n i t i a l r a p i d l o s s of o r g a n i c m a t t e r r e p o r t e d i n t h e s e  92 T a b l e 5.2  Summary o f t h e Main E f f e c t s o f L i t t e r Bag S t u d i e s , Where Bags were P l a c e d 15 cm below t h e S u r f a c e .  % organic matter decomposed  Main E f f e c t  Time  73 day d e c o m p o s i t i o n 146 day d e c o m p o s i t i o n  Location  B r u n s w i c k marsh P i t t marsh  Species  9.3 a * 21.9 b  12.1 a 9.7a  Alaksen o l d f i e l d  24.9 b  P h a l a r i s arundinacea  15.6 a  Carex l y n g b y e i  14.0 a  D a c t y l i s glomerata  17.1 a  * f o r each main e f f e c t , means f o l l o w e d by t h e same l e t t e r a r e n o t s i g n i f i c a n t l y d i f f e r e n t (P < .01) by Newman-Keul's m u l t i p l e range t e s t . The mean f o r each main e f f e c t i s an average o f a l l o b s e r v a t i o n s on t h a t e f f e c t i r r e s p e c t i v e o f the o t h e r f a c t o r s .  93  s t u d i e s can t h e r e f o r e be a t t r i b u t e d both t o d e c o m p o s i t i o n as w e l l p a r t i c l e l o s s from the bags.  Ignoring possible p a r t i c l e losses  as  through  the bags, the i n i t i a l h i g h s o l u b i l i z a t i o n l o s s e s i n d i c a t e a h i g h r a t e o f d i s s o l v e d o r g a n i c m a t t e r p r o d u c t i o n by the p l a n t s p e c i e s . The major d i f f e r e n c e s  i n d e c o m p o s i t i o n l o s s e s can be a t t r i b u t e d  to v a r i a t i o n s i n e n v i r o n m e n t a l and p l a n t c h a r a c t e r i s t i c s .  Among  the e n v i r o n m e n t a l f a c t o r s , t e m p e r a t u r e appeared t o p l a y a s i g n i f i c a n t role.  The seasonal t r e n d s i n d e c o m p o s i t i o n r a t e s were c o r r e l a t e d  w i t h changes i n ambient t e m p e r a t u r e .  Decomposition took p l a c e  d u r i n g the c o l d w i n t e r i n c r e a s i n g w i t h the advent o f s p r i n g .  slowly By June  the l e a v e s had c o m p l e t e l y d i s i n t e g r a t e d l e a v i n g behind hard stems t h a t resembled o l d growth from the p r e c e d i n g y e a r .  Lower s o i l  temperatures were a l s o p a r t l y r e s p o n s i b l e f o r the lower  decomposition  l o s s e s r e c o r d e d i n b u r i e d bags compared to those p l a c e d on the s u b strate surface. The lower d e c o m p o s i t i o n r a t e s r e c o r d e d f o r b u r i e d samples can a l s o be a t t r i b u t e d t o o t h e r f a c t o r s .  S u r f a c e samples tend to be  more a c c e s s i b l e t o d e t r i t o v o r e s than b u r i e d ones.  Furthermore,  the s u r f a c e l a y e r o f the s u b s t r a t e o f t e n undergoes more a e r o b i c r e s p i r a t i o n and f e r m e n t a t i o n .  Below the s u r f a c e , the l a r g e l y a n a e r o b i c  d e c o m p o s i t i o n i s much s l o w e r and i s c a r r i e d out by the " l e s s  efficient"  o b l i g a t e and f a c u l t a t i v e a n a e r o b e s .  signif-  For s u r f a c e s a m p l e s , no  i c a n t d i f f e r e n c e was found i n d e c o m p o s i t i o n l o s s e s a t the t h r e e h a b i t a t s a l t h o u g h the v a l u e s were s l i g h t l y h i g h e r i n Brunswick marsh than i n the P i t t marsh and A l a k s e n o l d f i e l d  (Table 5 . 1 ) .  The s l i g h t l y  r a t e s a t the A l a k s e n o l d f i e l d c o u l d be r e l a t e d to m o i s t u r e  lower  deficiency  94 i n the d r y l a n d w h i l e the lower r a t e s a t the P i t t marsh may be a t t r i b u t e d t o the c o l d o l i g o t r o p h i c n a t u r e o f the marsh. The above f i n d i n g s show t h a t t e m p e r a t u r e , m o i s t u r e and oxygen a v a i l a b i l i t y a r e the main e n v i r o n m e n t a l f a c t o r s i n f l u e n c i n g decomp o s i t i o n r a t e s i n the wetlands o f south western B r i t i s h C o l u m b i a . In g e n e r a l p l a n t m a t e r i a l s exposed t o warm m o i s t and a e r o b i c c o n d i t i o n s decompose more r a p i d l y than those s u b j e c t e d t o which a r e c o l d , a n a e r o b i c and d r y .  Tidal  action also  conditions increases  degradation r a t e s . In a d d i t i o n t o d i f f e r e n c e s which o c c u r r e d due t o e n v i r o n m e n t , some o f the observed v a r i a t i o n i n d e c o m p o s i t i o n l o s s e s c o u l d be a t t r i b u t e d to innate species d i f f e r e n c e s .  Woody p l a n t s  decompose  more s l o w l y than herbaceous, and the more s u c c u l e n t herbaceous f a s t e r than the more f i b r o u s .  Godshak and Wetzel  (1978) r e p o r t e d a  h i g h n e g a t i v e c o r r e l a t i o n between decay r a t e s and t o t a l f i b r e i n f i v e s p e c i e s o f a q u a t i c macrophytes.  species  content  Moody (1978) observed a  r a p i d l o s s o f f l e s h y p a r t s o f S a l i c o r n i a m a r i t i m u s and T r i g l o c h l i n m a r i t i m a i n the F r a s e r d e l t a t i d a l marshes.  Percentage l o s s e s from  l i t t e r bags a f t e r 103 days were 4 6 , 52, 85 and 92 f o r Carex l y n g b y e i , S c i r p u s m a r i t i m a , S a l i c o r n i a m a r i t i m u s and T r i g l o c h l i n m a r i t i m a respectively.  These d i f f e r e n c e s were due no doubt t o v a r i a t i o n s  chemical c o m p o s i t i o n o f the s p e c i e s Moody s t u d i e d .  in  Decomposition  d i f f e r e n c e s r e p o r t e d i n our s t u d i e s c o u l d s i m i l a r l y be a t t r i b u t e d t o s p e c i e s v a r i a t i o n s i n s t r u c t u r a l components.  In our l i t t e r bag s t u d i e s ,  we observed t h a t the l e a v e s had c o m p l e t e l y d i s i n t e g r a t e d by June l e a v i n g behind o n l y hard s t e m s .  A p p a r e n t l y t h e r e l a t i v e l y s o f t l e a v e s w i t h low  95 f i b r e c o n t e n t succumbed f i r s t t o d e c o m p o s i t i o n p r o c e s s e s w h i l e h i g h l y f i b r o u s stems f o l l o w e d much l a t e r .  the  P i t t marsh s p e c i e s  g e n e r a l l y took l o n g e r t o decompose presumably because o f t h e i r  high  f i b r e content. The above s p e c i e s d i f f e r e n c e s were noted i n s u r f a c e samples but not i n b u r i e d ones (Table 5 . 2 ) .  T h i s may be a f u n c t i o n o f  scale  s i n c e much l e s s d e c o m p o s i t i o n o c c u r r e d i n the b u r i e d bags.  I t would  appear t h a t under w e t l a n d c o n d i t i o n s , p a r t l y undecomposed p l a n t m a t e r i a l o v e r l a i n by dead v e g e t a t i o n from subsequent y e a r s degrades a t a v e r y slow r a t e i r r e s p e c t i v e o f s p e c i e s w h i l e s u r f a c e m a t e r i a l s degrade a t r a t e s dependent on s p e c i e s and e n v i r o n m e n t a l  5.3.2  conditions.  In v i t r o d e c o m p o s i t i o n of emergent v e g e t a t i o n  In e a r l i e r s e c t i o n s , i t was noted t h a t p l a n t m a t e r i a l s from wetlands may, as they are produced o r a f t e r they a r e p r o d u c e d , be a l t e r e d f o l l o w i n g one o r a l l  pathways o f t e n c l a s s i f i e d b r o a d l y as  accumulation, d e t r i t a l or g r a z i n g .  I t was f u r t h e r p o i n t e d o u t t h a t ,  t o v a r y i n g d e g r e e s , p r o c e s s e s o f comminution and b i o t i c may be v e r y i n v o l v e d .  activity  Much can be and has been l e a r n e d from f i e l d  o b s e r v a t i o n of these processes.  S t a n d a r d i z e d i n v i t r o s t u d i e s may  a l s o p r o v i d e u s e f u l i n f o r m a t i o n a l t h o u g h the use o f the i n d o o r l a b o r a t o r y i s not w i t h o u t i t s a s p e c t s o f a r t i f i c i a l i t y and time constraints.  Almost e n d l e s s s o p h i s t i c a t i o n can be e n v i s a g e d  in  p o s s i b l e l a b o r a t o r y s t u d i e s o f the d e g r a d a t i o n of w e t l a n d v e g e t a t i o n . We chose a s i m p l e t e c h n i q u e developed l a r g e l y by B u r k h o l d e r and  96 B o r n s i d e (1957) which seemed t o meet the q u a s i s u r v e y n a t u r e o f our investigations.  5.3.2.1  M a t e r i a l s and methods  O v e r w i n t e r e d m a t e r i a l s were c o l l e c t e d i n March, 1978, d r i e d and p u l v e r i z e d i n a W i l e y m i l l .  1.5 g o f p l a n t m a t e r i a l were  p l a c e d i n each of a s e r i e s o f 125 ml f l a s k s .  One s e t o f samples  were i n c u b a t e d w i t h 70 ml o f i n o c u l u m from P i t t marsh and the o t h e r s e t w i t h 70 ml of inoculum from Brunswick marsh.  The inoculum was  p r e p a r e d by f i l t e r i n g a s u s p e n s i o n o f marsh mud i n the s u r r o u n d i n g water.  5 ml a l i q u o t s o f " H y s o l " (10 mg/ml), a " c o m p l e t e " f e r t i l i z e r  supplement of high water s o l u b i l i t y , were added to h a l f o f the f l a s k s c o n t a i n i n g each inoculum source and 5 ml d i s t i l l e d water t o the o t h e r half.  C o n t r o l s were a l s o p r e p a r e d by i n c u b a t i n g s t e r i l i z e d  a r u n d i n a c e a samples w i t h the i n o c u l u m .  Phalaris  The c o n t r o l s were used to  demonstrate the e x t e n t of s o l u b i l i z a t i o n l o s s e s i n the absence of microbial All  activity. t r e a t m e n t s c o n t a i n e d two r e p l i c a t i o n s .  The f l a s k s were p l a c e d  on a mechanical s h a k e r , a e r a t e d o c c a s i o n a l l y and i n c u b a t e d a t 25° C i n the dark t o p r e v e n t p h o t o s y n t h e s i s . A f t e r 21 days o f i n c u b a t i o n one s e t of f l a s k s was removed, f i l t e r e d and the r e s i d u e t r a n s f e r r e d to t a r e d c r u c i b l e s . then oven d r i e d , weighed and ashed a t 550°C. was t r e a t e d s i m i l a r l y a f t e r 42 d a y s .  They were  The o t h e r s e t o f samples  Decomposition l o s s e s a f t e r 21  and 42 days a r e p r e s e n t e d on percentage o r g a n i c m a t t e r b a s i s .  97 In May, 1978, young v e g e t a t i v e shoots were c o l l e c t e d , and ground.  dried  The ground samples were t r e a t e d i n e x a c t l y the same  way as the o v e r w i n t e r e d m a t e r i a l s .  5.3.2.2  O b s e r v a t i o n s and r e s u l t s  Data from the i n v i t r o d e c o m p o s i t i o n s t u d i e s a r e p r e s e n t e d i n T a b l e s 5.3 and 5.4 and Appendices V t o V I I . In both o v e r w i n t e r e d and young s h o o t s , t h e main t r e a t m e n t e f f e c t s were h i g h l y s i g n i f i c a n t ( P < 0.01) respectively.  ( T a b l e s 5.3 and 5.4)  There were a l s o many s i g n i f i c a n t  interactions  e s p e c i a l l y f o r overwintered m a t e r i a l s . The percentage o f o r g a n i c m a t t e r l o s s a f t e r 42 days was h i g h e r than the amount l o s t i n 21 days o f i n c u b a t i o n .  Figure  5.4  i n d i c a t e s t h a t l o s s i n o r g a n i c m a t t e r was r a p i d d u r i n g the f i r s t 21 days a f t e r which f u r t h e r d e c o m p o s i t i o n took p l a c e a t a r e l a t i v e l y slower r a t e . Decomposition proceeded a t a f a s t e r r a t e w i t h P i t t marsh inoculum than w i t h Brunswick marsh i n o c u l u m . The a d d i t i o n o f Hysol t o both s o u r c e s o f inoculum i n c r e a s e d the p e r c e n t a g e o f o r g a n i c m a t t e r decomposed. The l o w e s t o r g a n i c m a t t e r l o s s e s were r e c o r d e d i n the s t e r i l e controls.  Of the u n s t e r i l i z e d samples, Carex s i t c h e n s i s and P h a l a r i s  a r u n d i n a c e a had the l o w e s t d e c o m p o s i t i o n v a l u e s w h i l e Carex l y n g b y e i had the h i g h e s t and D a c t y l i s g l o m e r a t a was i n t e r m e d i a t e . A major d i f f e r e n c e i n the p a t t e r n of d e c o m p o s i t i o n between young and o v e r w i n t e r e d m a t e r i a l s was the e x t r e m e l y h i g h v a l u e s r e p o r t e d f o r the former compared w i t h the l a t t e r .  98 T a b l e 5.3  Summary o f t h e Main E f f e c t s o f I n V i t r o S t u d i e s ; Overwintered shoots.  % organic matter decomposed  Main E f f e c t  Time  Source o f inoculum  Additive  Species  21 day d e c o m p o s i t i o n  13.6 a  42 day d e c o m p o s i t i o n  18.6 b  Brunswick marsh  15.3 a  P i t t marsh  16.9 b  No H y s o l  15.5 a  Hysol  16.8 b  Control Phalaris Carex  (sterile) arundinacea  sitchensis  Dactylis  glomerata  Carex l y n g b y e i  10.0 a 13.4 b 13.6 b 19.5 c 24.0 d  * f o r each main e f f e c t , means f o l l o w e d by t h e same l e t t e r a r e n o t s i g n i f i c a n t l y d i f f e r e n t (P<0.01) by Newman-Keul's m u l t i p l e range t e s t . The mean f o r each main e f f e c t i s an average o f a l l o b s e r v a t i o n s on t h a t e f f e c t i r r e s p e c t i v e o f the o t h e r f a c t o r s .  99 T a b l e 5.4  Summary o f t h e M a i n E f f e c t s o f I n V i t r o  Studies;  Young Shoots.  % organic matter decomposed  Main E f f e c t  Time  Source o f inoculum  Additive  Species  21 day d e c o m p o s i t i o n  54.4 a *  42 day d e c o m p o s i t i o n  58.1 b  Brunswick marsh  55.6 a  P i t t marsh  56.9 b  No H y s o l  54.4 a  Hysol  57.0 b  Control Carex  (sterile)  sitchensis  29.9 a 49.6 b  Phalaris  arundinacea  63.4 c  Dactylis  glomerata  67.8 d  Carex l y n g b y e i  70.4 e  * f o r each main e f f e c t , means f o l l o w e d by t h e same l e t t e r a r e n o t s i g n i f i c a n t l y d i f f e r e n t (P < 0.01) by Newman-Keul's m u l t i p l e range t e s t . The mean f o r each main e f f e c t i s an average o f a l l o b s e r v a t i o n s on t h a t e f f e c t i r r e s p e c t i v e o f the o t h e r f a c t o r s .  100  F i g u r e 5.4:  In V i t r o Decomposition o f O v e r w i n t e r e d and Young S h o o t s .  O^O  Control Carex  o-a  (Sterilized) sitchensis  Phalaris Carex  arundinacea  lyngbyei  Dactyl i s  glomerata  young shoots  21  42 Time  0  elapsed  (days)  102 5.3.2.3  Discussion  Loss o f o r g a n i c m a t t e r i n the s h a k i n g f l a s k s p r o b a b l y t a k e s p l a c e through d i f f u s i o n o f m e t a b o l i c p r o d u c t s such as C 0  2  and Nh^.  Changes i n percentage o r g a n i c m a t t e r decomposed under l a b o r a t o r y c o n d i t i o n s p a r a l l e l e d t h o s e i n the f i e l d s .  The t r e n d s were s i m i l a r  to those r e p o r t e d by B u r k h o l d e r and B o r n s i d e ( 1 9 5 7 ) .  The h i g h  l o s s e s c o u l d be a t t r i b u t e d m a i n l y t o d i s s o l u t i o n o f s o l u b l e f r a c t i o n s s i n c e even i n the absence o f m i c r o b i a l a c t i v i t y  initial  plant  (sterilized  samples) the magnitude o f o r g a n i c l o s s was r e l a t i v e l y h i g h , a v e r a g i n g about 10% i n o v e r w i n t e r e d m a t e r i a l s and 30% i n young s h o o t s . A l t h o u g h d i f f e r e n c e s a r e bound t o o c c u r between i n v i t r o and f i e l d o b s e r v a t i o n s , c e r t a i n a s p e c t s o f d e c o m p o s i t i o n i n n a t u r e can be e x p l a i n e d through l a b o r a t o r y s t u d i e s .  The e x t e n t o f  decomposition  t h a t a p l a n t undergoes i n v o l v e s a number o f f a c t o r s i n c l u d i n g the time c o n s i d e r e d , t e m p e r a t u r e , the n a t u r e o f the decomposer o r g a n i s m s , the a v a i l a b i l i t y o f n u t r i e n t s and the presence o f n a t u r a l i n h i b i t o r s the medium.  in  In our s t u d i e s , p l a n t samples t r e a t e d w i t h P i t t marsh  inoculum degraded f a s t e r than those t r e a t e d w i t h Brunswick marsh inoculum a l t h o u g h a c t i v i t y d i f f e r e n c e s were not g r e a t (Tables 5.3 and 5 . 4 ) . M i c r o b i a l a c t i v i t y would appear t o p l a y a more s i g n i f i c a n t r o l e i n the o l i g o t r o p h i c f r e s h water marsh than i n the F r a s e r b r a c k i s h marshes. The tendency f o r somewhat h i g h e r d e c o m p o s i t i o n r a t e s a t the Brunswick marsh would then be r e l a t e d more t o t i d a l a c t i o n than t o m i c r o b i a l degradation. The a d d i t i o n o f Hysol s i g n i f i c a n t l y i n c r e a s e d d e c o m p o s i t i o n r a t e i n both young and o v e r w i n t e r e d shoots ( T a b l e s 5.3 and 5 . 4 ) .  This  103 increase very l i k e l y i s r e l a t e d to a v a i l a b i l i t y of i n o r g a n i c supplied in Hysol.  nutrients  The Hysol used had the f o l l o w i n g c o m p o s i t i o n :  20%N, 20%P, 20%K, 0.04%Mn, 0.03%Fe, 0.002%Cu, O.OOUMb and 0.04%B. In n a t u r e , the i n o r g a n i c r e q u i r e m e n t s o f the microbes a r e p r o b a b l y s u p p l i e d by n u t r i e n t s i n the mud and s u r r o u n d i n g water r a t h e r than from dead undecomposed v e g e t a t i o n .  Young shoots would be expected  t o have h i g h p r o t e i n c o n t e n t and t h e i r p o s i t i v e response t o Hysol i n d i c a t e s t h a t n i t r o g e n was not the f a c t o r l i m i t i n g d e c o m p o s i t i o n the f l a s k s .  in  I t i s p o s s i b l e t h a t any o r a l l o f the t r a c e elements p l u s  the o t h e r m a c r o n u t r i e n t s c o u l d have accounted f o r t h i s r e s p o n s e . V a r i a t i o n i n s p e c i e s d e c o m p o s i t i o n i n the f l a s k s was s i m i l a r t o t h a t i n the f i e l d , Carex l y n g b y e i d e g r a d i n g the f a s t e s t w h i l e P i t t marsh s p e c i e s degraded the l e a s t .  the  Such v a r i a t i o n s can be a t t r i b u t e d  mainly to d i f f e r e n c e s i n s t r u c t u r a l composition.  Indeed the importance  o f the s t r u c t u r a l components i n t h i s r e g a r d i s i l l u s t r a t e d by t h e much h i g h e r d e c o m p o s i t i o n r a t e s r e p o r t e d f o r the young l o w - f i b r e  shoots.  104 6.  PLANT FACTORS LIMITING DEGRADATION OF EMERGENT VEGETATION  Much o f the e x a m i n a t i o n o f the w e t l a n d v e g e t a t i o n t o t h i s r e l a t e s t o g r o s s p r o c e s s e s o f dry m a t t e r p r o d u c t i o n , i . e .  point  how much  d r y m a t t e r i s produced, when i t i s p r o d u c e d , where i t goes and under what e n v i r o n m e n t a l c o n d i t i o n s .  In an e a r l i e r s e c t i o n i t was shown  t h a t energy d i f f e r e n c e s , as measured c a l o r i m e t r i c a l l y , i n the w e t l a n d s p e c i e s s t u d i e d are s l i g h t .  These o b s e r v a t i o n s s u p p o r t those o f  Boyd (1968, 1969a, 1970b) t h a t l i v i n g o r dead p l a n t m a t e r i a l  'moving'  i n t o g r a z i n g , d e t r i t a l or a c c u m u l a t i o n pathways have about the same c a l o r i c values r e g a r d l e s s of s p e c i e s , stage of m a t u r i t y or ibility'.  'digest-  B e s i d e s h a b i t a t f a c t o r s , d e g r a d a b i l i t y i n the broad sense  appears then t o be a m a t t e r o f c h e m i s t r y and p h y s i c s o f the p l a n t r a t h e r than i t s t o t a l c a l o r i c  content.  S i n c e most p r o t e i n s , s u g a r s , s t a r c h e s and l i p i d s a r e r e a d i l y d e g r a d a b l e , the f i b r o u s components o f p l a n t c e l l w a l l s would seem to p l a y a more i m p o r t a n t r o l e i n l i m i t i n g d e g r a d a b i l i t y of the p l a n t s . These components have e v o l v e d through g e o l o g i c a l  time and appear to  p r o t e c t l i v i n g p l a n t s from the p h y s i c a l elements o f the s o i l c l i m a t e and from b i o l o g i c a l  and  elements such as h e r b i v o r e s and decomposers.  Even i n dead p l a n t m a t e r i a l s t h e s e p r o t e c t i v e mechanisms may c o n t i n u e to e x e r c i s e an i n f l u e n c e on the r o u t e s taken i n d e g r a d a t i o n . Some o f the p r o t e c t i v e chemical and p h y s i c a l elements developed by p l a n t s have been w e l l d e l i n e a t e d i n mesic and x e r i c environments but c o m p a r a t i v e l y l i t t l e a t t e n t i o n has been accorded these mechanisms i n p l a n t s of wetland h a b i t a t s .  T h i s s e c t i o n i s devoted p r i m a r i l y t o  105 the e x a m i n a t i o n o f some o f t h e s e mechanisms i n r e l a t i o n t o the emergent p l a n t communities o f m a r i t i m e south w e s t e r n B r i t i s h C o l u m b i a . Our a n a l y t i c a l approach was s l i g h t l y d i f f e r e n t from the c o n v e n t i o n a l proximate scheme o f a n a l y s i s because o f the l a t t e r ' s especially in ecological  studies.  limitations  The p r o x i m a t e scheme was o r i g i n a l l y  developed on the premise t h a t crude f i b r e r e p r e s e n t e d the  indigestible  p o r t i o n w h i l e the n i t r o g e n f r e e e x t r a c t r e p r e s e n t e d the d i g e s t i b l e c a r b o h y d r a t e p o r t i o n o f the p l a n t .  That t h i s premise i s not always  t r u e was r e c o g n i z e d s e v e r a l y e a r s ago.  In a d d i t i o n t o the f a c t  that  crude f i b r e can have equal d e g r a d a b i l i t y as n i t r o g e n f r e e e x t r a c t (Crampton and Maynard 1 9 3 8 ) , a c o n s i d e r a b l e p a r t of the  indigestible  l i g n i n i s o f t e n found i n the n i t r o g e n f r e e e x t r a c t which i s  supposed  t o r e p r e s e n t a v a i l a b l e c a r b o h y d r a t e s (Norman 1935, P h i l l i p s  1940).  The use o f crude f i b r e and n i t r o g e n f r e e e x t r a c t has been p r e s e r v e d l a r g e l y f o r d a t a comparisons and because crude f i b r e i s  often  correlated negatively with n u t r i t i v e value. The development o f p l a n t c e l l w a l l f r a c t i o n a t i o n  procedures  (Van S o e s t 1963, Van S o e s t and Wine 1967) was an attempt t o overcome the i n c o n s i s t e n c i e s i n the p r o x i m a t e scheme o f a n a l y s i s .  The Van  S o e s t s p r o c e d u r e s , which we a d o p t e d , d i v i d e p l a n t dry m a t t e r 1  two p a r t s :  into  c e l l contents, l a r g e l y soluble carbohydrates, proteins,  o r g a n i c a c i d s and l i p i d s , a r e a l m o s t c o m p l e t e l y degradable 1965, Van S o e s t and Moore 1965) w h i l e the c e l l w a l l  (Jarrige  degradability  i s v a r i a b l e depending on the e x t e n t o f l i g n i f i c a t i o n , s i 1 i f i c a t i o n , etc.  Some o f the p l a n t p h y s i c a l f a c t o r s l i k e l y t o a f f e c t  degradation  p a t t e r n s were a l s o examined e s p e c i a l l y w i t h r e f e r e n c e t o t h e d e v e l o p ment and d i s t r i b u t i o n o f l i g n i f i e d t i s s u e s and the n a t u r e o f cuticular  surfaces.  the  106 6.1  6.1.1  N e u t r a l and A c i d D e t e r g e n t  Fibre  M a t e r i a l s and methods  C e l l w a l l c o n s t i t u e n t s were a n a l y z e d as f i b r e i n s o l u b l e n e u t r a l s o l u t i o n and as f i b r e i n s o l u b l e i n a c i d d e t e r g e n t (Goering and Van S o e s t 1970).  in  solution  N e u t r a l d e t e r g e n t f i b r e (NDF) c o n s i s t s  l a r g e l y o f c e l l u l o s e , h e m i c e l l u l o s e and l i g n i n w h i l e l i g n i n and c e l l u l o s e a r e combined i n a c i d d e t e r g e n t f i b r e (ADF)  6.1.2  (Van Soest 1963).  Results  D e s p i t e the l a r g e i n t e r s p e c i f i c v a r i a t i o n s , NDF l e v e l s  generally  i n c r e a s e d as the season p r o g r e s s e d (Tables 6.1 and 6.2 and F i g u r e 6 . 1 ) . In 1976, the l o w e s t NDF v a l u e was 44.6% f o r L o l i u m perenne c o l l e c t e d i n May and the h i g h e s t was 76.1% f o r Festuca a r u n d i n a c e a h a r v e s t e d i n September.  L o l i u m perenne i s a good q u a l i t y  pasture  s p e c i e s whereas F e s t u c a a r u n d i n a c e a i s a v e r y c o a r s e g r a s s found m a i n l y i n the f r i n g e s o f the d y k e s .  A s u b s t a n t i a l i n c r e a s e i n NDF was  r e c o r d e d i n the w i n t e r months (Table 6 . 2 ) . Changes i n ADF f o l l o w e d s i m i l a r t r e n d s as f o r NDF w i t h May samples having lower v a l u e s than those c o l l e c t e d towards the end o f growing season (Tables 6.3 and 6 . 4 ) . had the h i g h e s t ADF c o n t e n t .  Overwintered plant m a t e r i a l s  Carex l y n g b y e i and Juncus  effusus  g e n e r a l l y had lower ADF percentages compared t o the o t h e r examined.  the  species  Juncus e f f u s u s o f t e n remains p a r t l y green d u r i n g w i n t e r .  The low ADF v a l u e s f o r Carex l y n g b y e i c o u l d be an i n h e r e n t c h a r a c t e r i s t i c of t h i s  species.  107  T a b l e 6.1  Seasonal Changes i n N e u t r a l D e t e r g e n t F i b r e (as % Dry M a t t e r ) , Summer 1976.  Location  Species  May  July  Sept.  P i t t marsh  Calamagrostis canadensis  62.7*  65.5  69.0  II  Carex s i t c h e n s i s  66.9  68.9  69.1  Brunswick marsh  Carex l y n g b y e i  60.9  57.4  62.7  II  Festuca arundinacea  62.1  72.3  76.1  L o l i u m perenne  44.6  53.7  68.7  II  II  Alaksen o l d f i e l d  * V a l u e s a r e averages of two  samples.  108  Figure 6.1:  Seasonal Changes i n NDF.  CKO *  Calamagrostis canadensis Carex s i t c h e n s i s  (Pitt)  />r-A  Carex l y n g b y e i  OO  Festuca arundinacea L o l i u m perenne  (Pitt)  (Brunswick) (Brunswick)  (Alaksen)  MONTHS  no T a b l e 6.2  S e a s o n a l Changes i n N e u t r a l D e t e r g e n t F i b r e (as % Dry M a t t e r ) , W i n t e r 1977 - 1978.  Location  Species  19 Oct./77  4 Mar./78  P i t t marsh  Calamagrostis canadensis  73.0*  77.0  II  II  Phalaris  70.1  80.4  it  II  Carex s i t c h e n s i s  69.7  75.9  II  II  Scirpus cyperinus  70.7  84.5  II  II  Scirpus acutus  73.6  81.8  II  II  Juncus e f f u s u s  75.7  74.9  Brunswick marsh  Carex l y n g b y e i  67.9  84.9  it  Typha l a t i f o l i a  70.9  82.1  Dactylis  71.0  80.0  II  Alaksen o l d f i e l d  arundinacea  glomerata  * V a l u e s a r e averages o f two  samples.  Ill  T a b l e 6.3  S e a s o n a l Changes i n A c i d Detergent F i b r e (as % Dry M a t t e r ) , Summer 1976.  Location  Species  P i t t marsh  Calamagrostis  Brunswick marsh it  II  Alaksen o l d f i e l d  May  July  Sept  39.0*  41.2  43.3  Carex l y n g b y e i  28.9  31.8  34.9  Festuca  38.5  43.9  51.2  28.3  38.4  47.2  canadensis  arundinacea  L o l i u m perenne (+ Agropyron repens)  * V a l u e s a r e averages o f two  samples.  112 T a b l e 6.4  S e a s o n a l Changes i n A c i d D e t e r g e n t F i b r e (as % Dry M a t t e r ) , 1977, 1978.  Location  Species  14 May 1977  19 Oct. 1977  4 Mar. 1978  P i t t marsh  Calamagrostis canadensis  34.3*  46.3  49.6  .,  P h a l a r i s arundinacea  29.7  44.7  55.1  Carex s i t c h e n s i s  34.9  44.1  46.0  Scirpus cyperinus  31.0  49.9  55.9  Scirpus acutus  33.8  48.4  51.1  Juncus e f f u s u s  26.5  36.2  39.0  B r u n s w i c k marsh  Carex l y n g b y e i  27.8  35.3  43.1  II  Typha l a t i f o l i a  30.2  46.1  53.3  D a c t y l i s glomerata  34.1  41.8  51.0  .. M  II  Alaksen o l d f i e l d  * V a l u e s a r e averages o f two  samples.  113  6.1.3  Discussion  Due t o inadequate number o f s a m p l e s , no s t a t i s t i c a l a n a l y s i s was done. However, the d a t a p r e s e n t e d showed a d i s t i n c t t r e n d o f i n c r e a s i n g NDF and ADF as the season p r o g r e s s e d . f a l l and w i n t e r months.  The i n c r e a s e was e s p e c i a l l y n o t a b l e i n  the  S i n c e the shoots were dead and t h e r e f o r e m e t a b o l -  i c a l l y inactive, this f a l l  i n c r e a s e was p r o b a b l y l i n k e d t o a decrease  o t h e r more s o l u b l e components r a t h e r than an a c t u a l i n c r e a s e .  in  Significant  l o s s o f s o l u b l e m a t e r i a l s may o c c u r through l e a c h i n g and d e c o m p o s i t i o n  in  w i n t e r (see Table 4 . 8 ) . The s i g n i f i c a n c e o f n e u t r a l and a c i d d e t e r g e n t f i b r e s l i e s i n d e g r a d a b i l i t y by h e r n i v o r e s and d e t r i t o v o r e s .  their  The r e s u l t s r e p o r t e d here  show t h a t the r a t e and e x t e n t o f d e g r a d a t i o n o f the p l a n t m a t e r i a l s would vary with s p e c i e s .  F o r e x a m p l e , Carex l y n g b y e i , whole o r p a r t s , w i t h  NDF and ADF v a l u e s would be degraded f a s t e r than the more f i b r o u s  lower  Festuca  arundinacea.  6.2  Lignin  Lignin probably plays several roles in p l a n t t i s s u e s .  It is  possible  t h a t i t may have e v o l v e d as a d e t o x i f i c a t i o n p r o d u c t thus o f f e r i n g s u r v i v a l v a l u e to p l a n t s  ( N e i s h 1960).  L i g n i n p l a y s a major r o l e g i v i n g s t r e n g t h  and r i g i d i t y t o the p l a n t (Fahn 1967) and i s e s s e n t i a l f o r development o f e r e c t t e r r e s t r i a l p l a n t s ( N e i s h 1965).  Blum (1968) showed l i g n i f i c a t i o n  t o be a s s o c i a t e d w i t h i n s e c t r e s i s t a n c e i n sorghums. L i g n i n i s h i g h l y r e s i s t a n t to d e c o m p o s i t i o n and i s the p r i n c i p a l f a c t o r l i m i t i n g a v a i l a b i l i t y o f c a r b o y h d r a t e s i n the p l a n t c e l l  wall  114 t o rumen m i c r o b e s .  Of a l l  the p l a n t compounds t h a t can be r e a d i l y  measured by chemical means, l i g n i n appears t o g i v e the b e s t w i t h d i g e s t i b i l i t y ( H a r t l e y and Jones  correlation  1976).  I t i s g e n e r a l l y b e l i e v e d t h a t the a b i l i t y of c e r t a i n p l a n t s  to  r e s i s t d i g e s t i o n and d e c o m p o s i t i o n may not o n l y be r e l a t e d t o t o t a l l i g n i n c o n t e n t but a l s o to the p o s i t i o n and e x t e n t o f the  lignified  t i s s u e s , a f e a t u r e which i s not r e a d i l y p e r c e i v e d i n o r d i n a r y chemical analysis.  A c c o r d i n g l y , l i g n i n was examined not o n l y by chemical  a n a l y s i s but a l s o by h i s t o l o g i c a l  studies of i t s d i s t r i b u t i o n w i t h i n  different plant tissues.  6.2.1  M a t e r i a l s and methods  Total  l i g n i n c o n t e n t was determined by the permanganate o x i d a t i o n  o f a c i d d e t e r g e n t f i b r e ( G o e r i n g and Van S o e s t 1970). For h i s t o l o g i c a l  s t u d i e s , shoots o f P h a l a r i s a r u n d i n a c e a from  P i t t Meadows and Carex l y n g b y e i from Brunswick P o i n t were on 27 May, 9 J u l y and 17 September, 1976.  collected  On each s a m p l i n g d a t e ,  the shoots s e l e c t e d were c o n s i d e r e d r e p r e s e n t a t i v e o f the s t a n d . Each Carex l y n g b y e i shoot had an average o f 5 l e a v e s and the one from the bottom was chosen f o r s e c t i o n i n g .  third  For P h a l a r i s  a r u n d i n a c e a , the f i f t h l e a f from an average o f e i g h t was s e l e c t e d . Stem s e c t i o n s were o b t a i n e d from the base o f these s h o o t s . The samples were taken t o the l a b where 15-20 micron s e c t i o n s were c u t u s i n g a L a b - L i n e / H o o k e r p l a n t microtome ( L a b - L i n e Inc., I l l i n o i s ) .  Instruments  Temporary s e c t i o n s were p r e p a r e d and s t a i n e d w i t h  acid phloroglucinol  (Johansen 1 9 4 0 ) .  115 H i s t o l o g i c a l o b s e r v a t i o n s were made w i t h a l i g h t m i c r o s c o p e . Images were p r o j e c t e d on a s c r e e n by means o f a p r o j e c t i o n tube on a compound m i c r o s c o p e .  The c r o s s - s e c t i o n a l areas o f the a n a t o m i c a l  components were measured by a p l a n i m e t e r and e x p r e s s e d as a p e r c e n t a g e o f the t o t a l  6.2.2  area.  O b s e r v a t i o n s and r e s u l t s  Seasonal changes i n l i g n i n c o n t e n t a r e g i v e n i n Tables 6.5 and 6 . 6 . As was r e p o r t e d f o r f i b r o u s c o n s t i t u e n t s , l i g n i n i n the p l a n t s r e g i s t e r e d a s t e a d y i n c r e a s e as the season p r o g r e s s e d w i t h o v e r w i n t e r e d m a t e r i a l s having the h i g h e s t v a l u e s . S p e c i e s v a r i a t i o n i n l i g n i n c o n t e n t was e v i d e n t .  Except f o r  Carex l y n g b y e i and Juncus e f f u s u s , w e t l a n d s p e c i e s g e n e r a l l y had h i g h e r l i g n i n v a l u e s than the d r y l a n d s p e c i e s D a c t y l i s g l o m e r a t a and L o l i u m perenne. T a b l e s 6.7 and 6.8 show the r e a c t i o n o f l e a f and stem t i s s u e s to a c i d p h l o r o g l u c i n o l  f o r Carex l y n g b y e i and P h a l a r i s a r u n d i n a c e a .  There was p r o g r e s s i v e 1 i g n i f i c a t i o n o f the l e a f t i s s u e s w i t h time (Table 6 . 7 ) .  V a s c u l a r bundles were the f i r s t t o be l i g n i f i e d  by the s u r r o u n d i n g bundle sheath c e l l s .  Other s i t e s o f  followed  1ignification  were t o be found above and below the bundle e l e m e n t s , the l a r g e s t zone o c c u r r i n g below the mid v e i n .  The i n t e n s i t y o f  lignification  was h i g h e s t i n the sclerenchyma c e l l s a s s o c i a t e d w i t h major b u n d l e s . In g e n e r a l , Carex l e a f t i s s u e s were l e s s i n t e n s e l y l i g n i f i e d those o f  Phalaris.  than  116 The p a t t e r n o f l i g n i f i c a t i o n i n the stem t i s s u e was s i m i l a r t o t h a t i n the l e a v e s (Table 6 . 8 ) . between Carex and P h a l a r i s stems.  However t h e r e was a marked d i f f e r e n c e The e p i d e r m i s and parenchyma o f  Carex remained v i r t u a l l y u n l i g n i f i e d w h i l e those of P h a l a r i s became i n c r e a s i n g l y l i g n i f i e d as the stems matured. T a b l e s 6.9 and 6.10 show the a n a t o m i c a l measurements f o r and stems r e s p e c t i v e l y .  The v a r i a t i o n i n c r o s s s e c t i o n areas  the s i z e o f the stem s e c t i o n e d .  Both t a b l e s show absence o f  leaves reflects inter-  c e l l u l a r c a v i t i e s i n P h a l a r i s w h i l e Carex had a t l e a s t 1.8% r i s i n g a h i g h v a l u e o f 9.4% i n the stems by September.  Seasonal changes  to in  % v a s c u l a r bundles were not n o t i c e a b l e and both s p e c i e s m a i n t a i n e d similar values.  However, the p r o p o r t i o n of v a s c u l a r bundles was t w i c e  as h i g h i n the stems as i n the l e a v e s .  There was a g e n e r a l  i n sclerenchyma t i s s u e w i t h age o f the p l a n t s . sclerenchyma percentages than the stems.  increase  The l e a v e s had lower  The h i g h e s t stem s c l e r -  enchyma v a l u e was 24.1% f o r P h a l a r i s compared to o n l y 9.4% f o r C a r e x . P e r c e n t parenchymatous t i s s u e g e n e r a l l y d e c l i n e d r e f l e c t i n g increased proportion of t o t a l l i g n i f i e d  6.2.3  the  tissues.  Discussion  P r o g r e s s i v e 1 i g n i f i c a t i o n i s g e n e r a l l y c o n s i d e r e d t o be the major cause o f the d e c l i n e i n d i g e s t i b i l i t y as a herbage m a t u r e s .  The h i g h  l i g n i n v a l u e s r e c o r d e d towards the end o f the growing season would make the emergents poor q u a l i t y f o r a g e a t t h i s s t a g e .  In the  fall  and w i n t e r , l i g n i n l e v e l s i n some w e t l a n d p l a n t s were as h i g h as  117  T a b l e 6.5  S e a s o n a l Changes i n L i g n i n (as % Dry M a t t e r ) , 1976.  Location  Species  May  July  Sept.  P i t t marsh  Calamagrostis canadensis  3. 3*  7. 5  11.0  Brunswick marsh  Carex l y n g b y e i  3. 9  5. 4  6.6  II  Festuca arundinacea  2. 9  9. 4  11.9  L o l i u m perenne (+ Agropyron r e p e n s )  2. 8  5. 9  8.0  II  Alaksen o l d f i e l d  * V a l u e s a r e averages o f two  samples.  118 T a b l e 6.6  S e a s o n a l Changes i n L i g n i n (as % Dry M a t t e r ) 1977 - 1978.  Location  Species  14 May 1977  19 Oct. 1977  4 Mar. 1978  P i t t marsh  Calamagrostis canadensis  4.4*  11.4  14.7  P h a l a r i s arundinacea  2.7  10.6  13.8  Carex s i t c h e n s i s  4.9  10.5  13.1  Scirpus cyperinus  7.0  15.0  18.2  Scirpus acutus  3.5  13.1  15.9  ..  Juncus e f f u s u s  2.4  4.2  6.4  Brunswick marsh  Carex l y n g b y e i  3.3  7.3  11.7  II  Typha l a t i f o l i a  3.7  14.1  16.8  D a c t y l i s glomerata  3.1  6.5  10.4  „ „  ••  II  Alaksen o l d f i e l d  * V a l u e s a r e averages o f two **  samples.  March samples were taken from dead o v e r w i n t e r e d p l a n t s e x c e p t f o r Carex s i t c h e n s i s , Juncus e f f u s u s and Carex l y n g b y e i .  119 T a b l e 6.7  H i s t o l o g i c a l P a r t i t i o n i n g of L i g n i f i e d L e a f T i s s u e s i n Transverse Sections.  Staining  Intensity  Ranking*  Carex l y n g b y e i  Phalaris  arundinacea Date  Date Leaf Tissue  27/5  9/7  17/9  27/5  9/7  i;  Epidermis  0  0  0  0  0  0  Parenchyma  0  0  0  0  0  I  Sclerenchyma  1  1  2  2  3  4  Bundle  Sheath  2  2  3  3  4  4  Minor  Bundles  2  3  3  2  3  4  Major  Bundles  2  3  3  4  4  4  *  U s i n g a c i d i f i e d p h l o r o g l u c i n o l r e a c t i o n t o determine l e a f t i s s u e , the r a n k i n g was as f o l l o w s : 0 1 2 3 4  = = = = =  no s t a i n i n g very l i g h t s t a i n i n g mild staining strong staining very strong s t a i n i n g  lignified  120  T a b l e 6.8  H i s t o l o g i c a l P a r t i t i o n i n g o f L i g n i f i e d Stem T i s s u e s i n Transverse Sections.  Staining  Intensity  Ranking* P h a l a r i s arundinacea  Carex l y n g b y e i  Date  Date Stem T i s s u e  27/5  9/7  17/9  27/5  9/7  17/9  Epidermis  0  0  0  1  2  3  Parenchyma  0  0  0  1  1  0-2  Sclerenchyma  2  2  3  2  3  4  Bundle Sheath  3  3  4  2  4  4  V a s c u l a r Bundles  3  3  4  4  4  4  * U s i n g a c i d i f i e d p h l o r o g l u c i n o l r e a c t i o n t o determine l i g n i f i e d stem t i s s u e , the r a n k i n g was as f o l l o w s : 0 1 2 3 4  = = = = =  no s t a i n i n g very l i g h t s t a i n i n g mild staining strong staining very strong s t a i n i n g  121  T a b l e 6.9  A n a t o m i c a l Component Measurement on Leaves i n Transverse  Sections.  Carex l y n g b y e i  P h a l a r i s arundinacea  Date  Date  27/5  9/7  32.0  30.0  28.3  % intercellular cavities  3.2  6.4  7.3  % vascular bundles  4.8  6.7  %  1.1  Mean t o t a l c r o s s s e c t i o n a r e a (cm )  sclerenchyma  % total tissues  17/9  27/5  9/7  17/9  62.5  93.3  83.1  7.8  6.0  6.0  6.2  2.4  3.2  5.0  5.6  6.5  5.9  9.1  11.0  11.0  11.6  12.7  94.1  90.9  89.0  89.0  88.4  87.3  lignified  % parenchyma (largely lignified)  122  T a b l e 6.10  A n a t o m i c a l Component Measurements on Stems i n Transverse  Sections.  Carex l y n g b y e i  Phalaris  Date  mean t o t a l c r o s s s e c t i o n a l area (cm ) * 2  % intercellular cavities % vascular %  bundles  sclerenchyma  % total tissues  lignified  % parenchyma  *  arundinacea  D  a  t  e  27/5  9/7  17/9  27/5  9/7  17/9  47.4  68.2  99.6  229.0  202.2  206.5  1.8  7.0  9.4  —  —  13.1  13.3  13.6  11.6  11.2  12.6  5.9  6.7  9.4  19.0  19.2  24.1  19.0  20.0  23.0  30.6  30.4  36.7  81.0  80.0  77.0  69.4  69.6  63.3  The means were o b t a i n e d from a t l e a s t 6 s e c t i o n s images were p r o j e c t e d a t 50 x m a g n i f i c a t i o n .  123 18.2% (see T a b l e 6 . 6 ) .  A t t h i s s t a g e such a p l a n t would be o f  l i t t l e v a l u e t o most h e r b i v o r e s .  Decomposition by s o i l m i c r o -  organisms c o u l d a l s o be c u r t a i l e d .  Minderman (1968) noted t h a t  the p r o p o r t i o n i n g o f l i g n i n i n l i t t e r fragments tends t o d i c t a t e the shape o f the l o n g term d e c o m p o s i t i o n c u r v e once the more components have been removed.  L o l i u m perenne, D a c t y l i s  labile  glomerata  and Carex l y n g b y e i w o u l d , presumably, degrade f a s t e r than the o t h e r s p e c i e s on a c c o u n t o f t h e i r r e l a t i v e l y low l i g n i n v a l u e s .  The low  l i g n i n l e v e l s i n Juncus e f f u s u s throughout the y e a r can be a t t r i b u t e d i n p a r t t o i t s tendency t o r e t a i n green shoots and t o d e v e l o p new shoots even i n the w i n t e r months. Shenk and E l l i o t  (1971) o b s e r v e d l a r g e v a r i a t i o n s among g r a s s e s  and legumes i n r e l a t i v e amounts and arrangements o f v a s c u l a r b u n d l e s , l i g n i f i e d w a l l s and o t h e r a n a t o m i c a l s t r u c t u r e s .  Schank e t al_. (1973)  r e p o r t e d t h a t the percentage of v a s c u l a r bundles i n stem c r o s s  sections  o f Hemarthrias s p . was i n v e r s e l y r e l a t e d to i n v i t r o o r g a n i c m a t t e r digestibility.  W i l k i n s (1972) c a l c u l a t e d c r o s s s e c t i o n a l areas o f  s c l e r e n c h y m a , v a s c u l a r t i s s u e and n o n - v a s c u l a r t i s s u e i n temperate g r a s s e s and r e p o r t e d s i g n i f i c a n t n e g a t i v e c o r r e l a t i o n s between p o t e n t i a l d i g e s t i b i l i t y and l i g n i f i e d t i s s u e .  Regal  (1960) and Hanna e t a l .  (1976) found t h a t v a s c u l a r b u n d l e s , c u t i n i z e d e p i d e r m i s , and s c l e r enchyma passed through the a n i m a l ' s d i g e s t i v e t r a c t u n d i g e s t e d . Other r e p o r t s have shown t h a t sclerenchyma and o t h e r l i g n i f i e d  tissues  a r e u s u a l l y not degraded ( A k i n e t al_. 1973, Baker and H a r r i s 1947, D r a p a l a e t aJL 1947).  D i f f e r e n c e s i n the ease o f d i g e s t i b i l i t y o f  t i s s u e types suggest t h a t the amounts o f s l o w l y d i g e s t i b l e as w e l l as n o n - d i g e s t i b l e l i g n i f i e d t i s s u e s c o u l d a f f e c t the r a t e o f  digestion  124 as w e l l as d e c o m p o s i t i o n o f p l a n t m a t e r i a l s . Our s t u d i e s showed t h a t l i g n i f i e d t i s s u e was c o n f i n e d t o the v a s c u l a r bundles i n the e a r l y stages o f g r o w t h .  chiefly  Lignification  then s p r e a d g r a d u a l l y t o o t h e r t i s s u e s as t h e season p r o g r e s s e d . p a t t e r n o f 1 i g n i f i c a t i o n p a r a l l e l e d the seasonal changes i n  This  lignin  determined by chemical means. The i n t e n s i t y of s t a i n i n g of the v a r i o u s t i s s u e s was s i m i l a r f o r both Carex and P h a l a r i s but the percentage o f sclerenchyma t i s s u e was much h i g h e r i n the l a t t e r than the f o r m e r .  Carex a l s o had l o o s e  parenchyma arrangement w i t h numerous i n t e r c e l l u l a r c a v i t i e s whereas P h a l a r i s was a s s o c i a t e d w i t h c l o s e l y packed c e l l s w i t h l e s s surface.  internal  These f e a t u r e s might be expected t o f a v o u r Carex r a t h e r  than P h a l a r i s i n d i g e s t i o n and d e c o m p o s i t i o n .  6.3  Cuticle  The n a t u r a l p r o t e c t i v e c o v e r i n g o f the l e a v e s o f h i g h e r p l a n t s c o n s i s t s o f a l a y e r o f n o n - l i v i n g c u t i c l e a s s o c i a t e d w i t h the t h i c k e n e d o u t e r w a l l s o f the e p i d e r m i s .  I t i s made up o f a spongy framework o f  c u t i n formed from p o l y m e r i z e d a c i d s w i t h wax embedded i n them ( E g l i n t o n and Hamilton 1967). Marked v a r i a t i o n s o c c u r i n the t h i c k n e s s of the c u t i c l e and i n the degree o f wax f o r m a t i o n between l e a v e s o f d i f f e r e n t  species,  between d i f f e r e n t aged l e a v e s of one s p e c i e s and between the upper and lower l e a f s u r f a c e s .  C u t i c u l a r t h i c k n e s s p r o b a b l y depends on  g e n e t i c as w e l l as e n v i r o n m e n t a l  factors.  •  125  P h y s i o l o g i c a l l y , the c u t i c l e p r o t e c t s t h e p l a n t from i n v a d i n g organisms and p r o b a b l y reduces t r a n s p i r a t i o n . An o u t s t a n d i n g p r o p e r t y o f c u t i c l e i s i t s chemical which makes i t e x t r e m e l y r e s i s t a n t to b i o l o g i c a l  stability  degradation.  The r e s i s t a n c e of c u t i n i z e d m a t e r i a l s t o b a c t e r i a l  decomposition  may be e v i d e n c e d by the p e r s i s t e n c e i n n a t u r e o f p o l l e n g r a i n s which c o n t a i n much c u t i n o v e r l o n g p e r i o d s o f g e o l o g i c a l  time.  I t has been suggested t h a t herbage consumed by g r a z i n g h e r b i v o r e s i s degraded i n i t i a l l y by p h y s i c a l removal o f the c u t i c l e and b r e a k i n g o f f i b r e s thus c r e a t i n g f r a c t u r e s and entry  sites for microbial  enzymes c a p a b l e o f d i g e s t i n g the s t r u c t u r a l c a r b o h y d r a t e s  (Monson  and Burton 1972, Baker and H a r r i s 1947, Monson e t al_. 1 9 7 2 ) . Heinen (1961) has demonstrated the e x i s t e n c e of a c u t i n a s e system i n c e r t a i n m i c r o o r g a n i s m s which e n a b l e s them to u t i l i z e as a carbon s o u r c e under a e r o b i c c o n d i t i o n s .  However under a n a e r o b i c  c o n d i t i o n s , the c u t i c l e may be p r e s e r v e d almost (Harris  cutin  indefinitely  1956).  I t i s g e n e r a l l y known t h a t p l a n t m a t e r i a l f i n a l l y d i s a p p e a r s d u r i n g d e c o m p o s i t i o n even under w e t l a n d c o n d i t i o n s , s u g g e s t i n g t h a t small but d i s c e r n i b l e changes i n the l e a f s u r f a c e s o c c u r d u r i n g the transformation.  Over a s h o r t p e r i o d o f t i m e , such changes a r e  t o be beyond the r e s o l u t i o n o f l i g h t m i c r o s c o p y .  likely  The s c a n n i n g  e l e c t r o n m i c r o s c o p e appeared t o be u s e f u l f o r d e t e c t i n g t h e s e changes since i t permits observations at d i f f e r e n t m a g n i f i c a t i o n s of s u r f a c e s t r u c t u r e o f the s h o o t s .  the  126 6.3.1  M a t e r i a l s and methods  T o t a l c u t i n c o n t e n t was e s t i m a t e d by d i g e s t i n g KMnO l i g n i n r e s i d u e w i t h 72 p e r c e n t H S 0 2  4  ( G o e r i n g and Van Soest 1970).  Cutin  was then c a l c u l a t e d as l o s s i n w e i g h t upon a s h i n g . To s t u d y the n a t u r e o f c u t i c u l a r s u r f a c e s , l i v e and dead s h o o t m a t e r i a l s were c o l l e c t e d on 10 May, 1978.  They were a i r d r i e d ,  c a r e f u l l y t r i m m e d , mounted on aluminum s t u d s and c o a t e d under vacuum w i t h g o l d p a l l a d u m , then o b s e r v e d and photographed.  S e v e r a l random  samples o f each shoot were o b s e r v e d under t h e m i c r o s c o p e and p h o t o graphed.  6.3.2  Only s i n g l e photomicrographs a r e p r e s e n t e d i n t h e t h e s i s .  O b s e r v a t i o n s and r e s u l t s  Seasonal changes i n c u t i n c o n t e n t o f the emergent s p e c i e s s t u d i e d a r e p r e s e n t e d i n T a b l e s 6.11 and 6 . 1 2 .  The t a b l e s show  t h a t c u t i n l e v e l s were g e n e r a l l y l o w , r a n g i n g from 0.3% to 2.2%. There was some v a r i a b i l i t y i n c u t i n l e v e l s between s p e c i e s . The l o w e s t v a l u e s were found i n P h a l a r i s a r u n d i n a c e a w h i l e S c i r p u s c y p e r i n u s , Carex l y n g b y e i and Typha l a t i f o l i a c o n t a i n e d h i g h e r percentages. The t a b l e s a l s o show a r e l a t i v e l y c o n s i s t e n t i n c r e a s e i n  cutin  c o n t e n t from May to September and October f o r most s p e c i e s s t u d i e d . However, t h e r e was a d e c l i n e i n o v e r w i n t e r e d m a t e r i a l s , Carex s i t c h e n s i s and S c i r p u s acutus being the o n l y e x c e p t i o n s .  127  T a b l e 6.11  S e a s o n a l Changes i n C u t i n (as % Dry M a t t e r ) , Summer, 1976.  May  July  Sept.  Location  Species  18-21  6-9  16-21  P i t t marsh  Calamagrostis canadensis  0.9*  1.2  1.4  !!  P h a l a r i s arundinacea  0.6  0.8  0.9  Brunswick marsh  Carex l y n g b y e i  1.3  1.1  1.3  Alaksen old f i e l d  L o l i u m perenne  0.7  1.0  1.1  II  * V a l u e s a r e averages o f two  samples.  128  T a b l e 6.12  S e a s o n a l Changes i n C u t i n (as % Dry M a t t e r ) , 1977-1978.  14 May 1977  19 Oct. 1977  4 Mar. 1978  Location  Species  P i t t marsh  Calamagrostis canadensis  0.8*  1.8  1.0  P h a l a r i s arundinacea  0.3  0.5  0.3  Carex s i t c h e n s i s  0.8  1.0  1.1  Scirpus cyperinus  1.5  2.2  2.1  Scirpus acutus  0.7  1.0  1.0  Juncus e f f u s u s  0.9  0.9  0.8  Carex l y n g b y e i  1.1  1.8  0.8  Typha l a t i f o l i a  1.1  1.7  1.6  D a c t y l i s glomerata  0.8  1.0  0.6  Brunswick marsh  Alaksen old f i e l d  *  V a l u e s a r e averages o f two  samples.  129 Scanning e l e c t r o n micrographs of l e a f o r stem s u r f a c e s of s p e c i e s s t u d i e d a r e shown i n F i g u r e s 6.2 to 6 . 8 .  the  I t i s p o s s i b l e and  most l i k e l y t h a t the presence o f s i l t d e p o s i t s on the s u r f a c e s obscured many f e a t u r e s t h a t would be o f i n t e r e s t i n t h i s These s i l t d e p o s i t s were q u i t e prominent i n the m a t e r i a l s  study. collected  from Brunswick marsh where the p l a n t s a r e f r e q u e n t l y s u b j e c t e d t o tidal action.  D e s p i t e these a n o m a l i e s , s e v e r a l f e a t u r e s  pertinent  t o d e g r a d a t i o n were d i s c e r n e d . A l t h o u g h not shown i n the p h o t o g r a p h s , most s p e c i e s had s e r r a t e d l e a f edges.  Of a l l  the s p e c i e s examined, o n l y Carex s i t c h e n s i s and  F e s t u c a a r u n d i n a c e a had t r i c h o m e s ( F i g u r e s 6.2 and 6 . 6 ) . t r i c h o m e s were g l a n d u l a r i n Carex s i t c h e n s i s ; s t o u t  These  sharp-pointed  and n o n - g l a n d u l a r i n F e s t u c a . By comparing top and bottom p h o t o g r a p h s , i t was observed t h a t v e r y l i t t l e w e a t h e r i n g o f the s u r f a c e s took p l a c e on s p e c i e s from the P i t t marsh and A l a k s e n o l d f i e l d  ( F i g u r e s 6 . 2 , 6.3 and 6.8)  e x c e p t f o r Equisetum whose s u r f a c e s t r u c t u r e was c o m p l e t e l y  lost  o v e r the w i n t e r months ( F i g u r e 6 . 4 ) .  the  C u t i c u l a r surfaces of  Brunswick marsh s p e c i e s were h i g h l y abraded d u r i n g the w i n t e r 6.5 and 6.6) a l t h o u g h t o a l e s s e r degree i n Typha l a t i f o l i a  (Figures  (Figure  6.7).  6.3.3  Di s c u s s i o n  Low percentages o f c u t i n were r e c o r d e d i n t h i s study which i n d i c a t e t h a t c u t i n c o n t e n t j j e r s_e p r o b a b l y p l a y s a minor r o l e d e p r e s s i n g d e g r a d a b i l i t y i n the d e t r i t a l and g r a z i n g pathways.  in  130  Figure 6.2:  Scanning E l e c t r o n Photomicrographs of A d a x i a l S u r f a c e s o f Carex s i t c h e n s i s  A.  (x 50)  Top photo:  Leaf  (Pitt).  young p h o t o s y n t h e t i c blade showing glandular trichomes.  B.  (x 400)  Bottom photo:  o v e r w i n t e r e d blade showing l i t t l e  Top photo:  young p h o t o s y n t h e t i c  Bottom photo:  overwintered blade  blade  erosion  133  Figure 6.3:  Scanning E l e c t r o n Photomicrographs o f Shoot S u r f a c e s o f S c i r p u s acutus  A.  B.  (x 50)  (x 400)  (Pitt).  Top photo:  young p h o t o s y n t h e t i c  shoot  Bottom photo:  o v e r w i n t e r e d shoot showing l i t t l e  Top photo:  young p h o t o s y n t h e t i c  Bottom photo:  overwintered blade  blade  erosion  136  Figure 6.4:  Scanning E l e c t r o n Photomicrographs of A d a x i a l S u r f a c e s o f Equisetum f l u v i a t i l e  A.  B.  (x 50)  (x 400)  Leaf  (Pitt).  Top photo:  young p h o t o s y n t h e t i c  blade  Bottom photo:  o v e r w i n t e r e d blade showing s e v e r e e r o s i o n  Top photo:  young p h o t o s y n t h e t i c  Bottom photo:  overwintered blade  blade  139  Figure 6.5:  Scanning e l e c t r o n photomicrographs of A d a x i a l S u r f a c e s o f Carex l y n g b y e i  A.  (x 50)  Leaf  (Brunswick).  Top photo:  young p h o t o s y n t h e t i c  blade  Bottom photo:  o v e r w i n t e r e d blade showing severe e r o s i o n and d e p o s i t s o f s i l t , diatom s h e l l s , e t c .  B.  (x 400)  Top photo:  young p h o t o s y n t h e t i c b l a d e  Bottom photo:  o v e r w i n t e r e d blade  142  Figure 6.6:  Scanning E l e c t r o n Photomicrographs o f A d a x i a l  Leaf  Surfaces of Festuca arundinacea (Brunswick).  A.  B.  (x 50)  (x 400)  Top photo:  young p h o t o s y n t h e t i c  blade  Bottom photo:  o v e r w i n t e r e d blade showing a l m o s t severe e r o s i o n  Top photo:  young p h o t o s y n t h e t i c  Bottom photo:  overwintered blade  blade  145  Figure 6.7:  Scanning E l e c t r o n Photomicrographs o f A d a x i a l S u r f a c e s o f Typha l a t i f o l i a  A.  B.  (x 50)  (x 400)  Leaf  (Brunswick).  Top photo:  young p h o t o s y n t h e t i c  blade  Bottom photo:  o v e r w i n t e r e d b l a d e showing c u t i c u l a r e r o s i o n .  Top photo:  young p h o t o s y n t h e t i c  Bottom photo:  o v e r w i n t e r e d blade  blade  6  148  F i g u r e 6.8:  Scanning E l e c t r o n Photomicrographs o f A d a x i a l  Leaf  S u r f a c e s o f D a c t y l i s glomerata ( A l a k s e n ) .  A.  B.  (x 50)  (x 400)  Top photo:  young p h o t o s y n t h e t i c  blade  Bottom photo:  o v e r w i n t e r e d b l a d e showing c u t i c u l a r e r o s i o n .  Top photo:  young p h o t o s y n t h e t i c  Bottom photo:  o v e r w i n t e r e d blade  blade  151 I t a p p e a r s , however, t h a t l i k e t h e f i b r o u s f r a c t i o n s , c u t i c u l a r m a t e r i a l g e n e r a l l y i n c r e a s e s as p l a n t s age.  The d e c l i n e i n c u t i n c o n t e n t over  the w i n t e r months p r o b a b l y r e f l e c t e d l o s s e s due t o w e a t h e r i n g and a b r a s i o n o f the p l a n t s u r f a c e s . A l t h o u g h s e r r a t e d l e a f edges would o f f e r some p r o t e c t i o n from g r a z i n g , i t appears from t h i s study t h a t few w e t l a n d s p e c i e s have a well  developed t r i c h o m e system f o r defense i n t h i s r e g a r d .  There i s  no doubt t h a t the p r i c k l y t r i c h o m e s possessed by F e s t u c a a r u n d i n a c e a might d e t e r c e r t a i n c l a s s e s o f h e r b i v o r e s from f e e d i n g on the p l a n t s . G l a n d u l a r t r i c h o m e s such as those found i n Carex s i t c h e n s i s  (Figure  c o u l d produce t o x i n s and/or r e p e l l e n t s which a r e o b j e c t i o n a b l e potential grazers.  6.2)  to  S i m i l a r r o l e s o f t r i c h o m e s i n p l a n t defense have  been reviewed by L e v i n  (1973).  The r e s u l t s a l s o showed v a r i a b l e s u r f a c e changes a few months a f t e r senescence and death o f the a e r i a l  shoots.  Minimal  surface  changes were r e c o r d e d i n the P i t t marsh s p e c i e s , e x c e p t f o r E q u i s e t u m , i n d i c a t i n g l i t t l e d e g r a d a t i o n o f the s h o o t s .  The f a s t d e g r a d a t i o n o f  Equisetum r e f l e c t e d the n o n - f i b r o u s n a t u r e of t h i s s p e c i e s . a l s o appeared to be minimal but u n i f o r m i n the o l d f i e l d  Degradation  species.  The Brunswick marsh s p e c i e s s u f f e r e d f a r more a b r a s i o n than the marsh o r o l d f i e l d s p e c i e s .  C u t i c u l a r and epidermal removal was  presumably a c c o m p l i s h e d e a s i l y through t i d a l marsh.  However, t a l l  Pitt  a c t i v i t y i n the b r a c k i s h  r o b u s t s p e c i e s growing a t h i g h e r  substrate  e l e v a t i o n s may s t a n d e r e c t throughout the w i n t e r months and remain r e l a t i v e l y undegraded u n t i l t o the s u b s t r a t e s u r f a c e . (Figure 6.7).  the summer when most o f the shoots Typha l a t i f o l i a was a good example  fall  152 6.4  Silica  A l t h o u g h i t has been e s t a b l i s h e d t h a t s i l i c a i s m e t a b o l i z e d by many s p e c i e s o f p l a n t s , i t may i n some i n s t a n c e s be regarded as no more than s o i l c o n t a m i n a t i o n .  Uptake o f s i l i c a by p l a n t s depends  both on the a v a i l a b i l i t y o f s i l i c a i n the s o i l and on the c h a r a c t e r i s t i c o f the p l a n t s p e c i e s  (Jones e t a]_. 1 9 6 3 ) .  Many members o f  the  grass f a m i l y are a c t i v e c u m u l a t o r s o f s i l i c a (Jones and Handreck 1 9 6 7 ) . S i l i c a appears t o f u n c t i o n i n the manner of l i g n i n by adding s t r u c t u r a l s t r e n g t h to the p l a n t .  But i t has a l s o been suggested  that in c e r t a i n species, c e l l wall  s i l i c a may, l i k e l i g n i n ,  limit  m i c r o b i a l d e g r a d a t i o n o f the s t r u c t u r a l c a r b o h y d r a t e s (Van S o e s t and Jones 1 9 6 8 ) .  High l e v e l s o f s i l i c a have a l s o been a s s o c i a t e d  with urinary c a l c u l i  6.4.1  incidence i n c a t t l e (Parker 1957).  M a t e r i a l s and methods  S i l i c a was o b t a i n e d on some s e l e c t e d samples as t h e ash r e m a i n i n g a f t e r permanganate l i g n i n ash was l e a c h e d w i t h 48% HBr f o r one hour ( G o e r i n g and Van S o e s t 1 9 7 0 ) .  6.4.2  Results  T a b l e 6.13 shows t h a t most s p e c i e s d i d not d e p o s i t high l e v e l s of s i l i c a .  The o n l y s p e c i e s w i t h s i l i c a l e v e l s above 2% were P h a l a r i s  a r u n d i n a c e a and Carex l y n g b y e i .  T a b l e 6.13  Silica  (as % Dry Weight) i n the S t a n d i n g Crops of  Some S p e c i e s Sampled on 19 October,  1977.  Location  Species  P i t t marsh  Calamagrostis canadensis  1.3*  "  "  P h a l a r i s arundinacea  2.5  "  "  Carex s i t c h e n s i s  0.9  "  "  Scirpus cyperinus  1.0  "  "  S c i r p u s acutus  0.7  "  "  Juncus e f f u s u s  0.8  Brunswick marsh  Carex l y n g b y e i  2.8  "  Typha l a t i f o l i a  1.4  D a c t y l i s glomerata  1.9  "  Alaksen old f i e l d  * V a l u e s a r e averages o f two  % Silica  samples.  154 6.4.3  Discussion  S i l i c a has been r e p o r t e d to be a n u t r i t i o n a l problem i n the N o r t h e r n G r e a t P l a i n s of North America where some o f the range g r a s s e s c o n t a i n more than 2% s o l u b l e s i l i c a  (Bezeau e t al_. 1966).  P h a l a r i s a r u n d i n a c e a and Carex l y n g b y e i were the o n l y w i t h a t o t a l s i l i c a c o n t e n t above 2%.  species  There i s a p o s s i b i l i t y  t h a t some o f the v a l u e s were e l e v a t e d due to s o i l  contamination  p a r t i c u l a r l y i n Carex l y n g b y e i which e x p e r i e n c e s f r e q u e n t action.  tidal  I t appears from the r e s u l t s t h a t s i l i c a l e v e l s i n the  emergent communities a r e f a r too low t o be a l i m i t i n g f a c t o r t h e i r d e g r a d a t i o n , whether by g r a z e r s o r by d e t r i t o v o r e s .  in  Brink  e t al_. (1961) r e p o r t e d t h a t w i t h t h e e x c e p t i o n of a few s p e c i e s such as E q u i s e t u m , the s i l i c a c o n t e n t o f w e t l a n d s p e c i e s i n  British  Columbia i s too low t o be a n u t r i t i o n a l concern i n u n g u l a t e s .  6.5  P h e n o l i c Compounds  B e s i d e s the s t r u c t u r a l components d i s c u s s e d i n the p r e c e d i n g s e c t i o n s , i t appears t h a t t h e r e a r e s o l u b l e c o n s t i t u e n t s which a l s o o f f e r some form of p r o t e c t i o n t o the p l a n t .  Some o f the s o -  c a l l e d secondary p l a n t substances a r e known t o possess t o x i c o r r e p e l l e n t c h a r a c t e r i s t i c s which may r e n d e r p l a n t s u n p a l a t a b l e t o herbivores.  The same compounds may a l s o r e t a r d o r  inhibit  m i c r o b i a l a c t i v i t y i n the s o i l hence r e d u c i n g d e c o m p o s i t i o n r a t e s .  155 We a s s e s s e d the t o t a l p h e n o l i c c o n t e n t o f some o f the emergent s p e c i e s because p h e n o l i c compounds appear to be one of the most w i d e s p r e a d secondary p l a n t m e t a b o l i t e s known.  The g e n e r a l r o l e  p h e n o l i c compounds i n p l a n t s has not y e t been w e l l  of  documented.  Some o f them have been i m p l i c a t e d i n a l l e l o p a t h y (Van Sumere 1960) w h i l e o t h e r s have been shown t o be r e s p o n s i b l e f o r o f c e r t a i n f o r a g e p l a n t s (Burns e t al_. 1976).  The r o l e i n  a c c u m u l a t i v e and g r a z i n g pathways has not been w e l l  6.5.1  unpalatability detrital,  documented.  M a t e r i a l s and methods  Young p l a n t s tend t o have h i g h e r c o n c e n t r a t i o n s of  secondary  compounds than mature ones w i t h the l e a v e s c o n t a i n i n g more than the stems (Parmar and B r i n k 1976).  Young l e a f samples were  therefore  c o l l e c t e d on 10 May, 1978 when peak p h e n o l i c c o n c e n t r a t i o n s were e x p e c t e d i n the p l a n t s . A f t e r s e p a r a t i o n , the l e a v e s were i m m e d i a t e l y submerged i n l i q u i d n i t r o g e n and taken t o the l a b where they were f r e e z e d r i e d . D r i e d samples were ground i n a W i l e y m i l l t o pass through a 1 mm s c r e e n . 2 g o f sample were e x t r a c t e d w i t h 80% methanol as d e s c r i b e d by Burns et_ al_. (1976) and t o t a l p h e n o l i c c o n t e n t was d e t e r m i n e d u s i n g the F o l i n - D e n n i s r e a g e n t and c h l o r o g e n i c a c i d as the s t a n d a r d ( R o s e n b l a t t and P e l u s o 1941).  156 6.5.2  O b s e r v a t i o n s and r e s u l t s  Total  p h e n o l i c c o n c e n t r a t i o n s i n the l e a v e s o f p l a n t s from the  Brunswick marsh and A l a k s e n o l d f i e l d were s i m i l a r , a v e r a g i n g 20 mg/g o f l e a f dry w e i g h t (Table 6 . 1 4 ) .  The s p e c i e s from the P i t t marsh  showed c o n s i d e r a b l e v a r i a t i o n i n p h e n o l i c c o n t e n t .  Scirpus cyperinus  r e g i s t e r e d 59.5 mg/g, the h i g h e s t v a l u e , w h i l e Juncus e f f u s u s had the l o w e s t l e a f c o n c e n t r a t i o n o f 10.8 mg/g.  6.5.3  Discussion  I t i s p r o b a b l e t h a t q u a n t i f i c a t i o n o f t o t a l phenols by the procedure d e s c r i b e d here c o u l d go a l o n g way i n e x p l a i n i n g v a r i a t i o n s i n a c c e p t a b i l i t y o f the p l a n t s by g r a z i n g h e r b i v o r e s as w e l l as the r a t e s o f m i c r o b i a l d e c o m p o s i t i o n i n the  field.  Burns e t al_. (1967) and L a n g i l l e and McKee (1968) r e p o r t e d a t a n n i n c o n t e n t range o f 1.5 t o 3.8% i n c r o w n v e t c h .  The t a n n i n v a l u e s  were determined by a method s i m i l a r t o t h a t used i n our s t u d i e s . The workers c o n c l u d e d t h a t these t a n n i n l e v e l s were too low t o i n f l u e n c e p a l a t a b i l i t y of crownvetch.  A l t h o u g h t h e r e were no d i r e c t l y  comparable d a t a t o s u p p o r t o u r s , i t a p p e a r s , from the r e p o r t s o f above w o r k e r s , t h a t t o t a l p h e n o l i c l e v e l s i n most s p e c i e s  the  sampled  were not o f s u f f i c i e n t magnitude t o s i g n i f i c a n t l y i n f l u e n c e animal response o r p l a n t decay. clarify this  aspect.  However, f u r t h e r work i s recommended t o  157  T a b l e 6.14  Average C o n c e n t r a t i o n o f T o t a l P h e n o l s i n the Leaves H a r v e s t e d on 10 May, 1978.  Phenolic  Content  Location  Species  P i t t marsh  Calamagrostis canadensis  33.8*  "  "  P h a l a r i s arundinacea  18.9  "  "  Carex s i t c h e n s i s  26.3  "  "  Scirpus cyperinus  59.4  "  "  Scirpus acutus  29.5  "  "  Juncus e f f u s u s  10.8  Carex l y n g b y e i  19.8  Typha l a t i f o l i a  19.1  D a c t y l i s glomerata  20.0  B r u n s w i c k marsh " Alaksen old f i e l d  *  V a l u e s a r e averages o f two  mg / gm d r y weight  samples.  158 7.  NUTRIENTS IN EMERGENT VEGETATION  N u t r i e n t t r a n s f e r s i n p l a n t communities have s e v e r a l  aspects  t h a t deserve s p e c i a l a t t e n t i o n w i t h r e s p e c t t o n u t r i e n t c y c l i n g wetland systems.  in  The major s o u r c e s o f n u t r i e n t s t o w e t l a n d p l a n t s  i n c l u d e water ( p r e c i p i t a t i o n , s u r f a c e w a t e r , ground w a t e r ) , a i r and the s u b s t r a t e .  N u t r i e n t s accumulated i n the p l a n t s may be r e t u r n e d  to the environment t h r o u g h :  (1)  l e a c h i n g o f aboveground s t a n d i n g  crops (and a l s o through g u t t a t i o n v i a s a l t g l a n d s i n p l a n t s o f and b r a c k i s h a r e a s ) , (3)  (2)  saline  r e l e a s e v i a d e c o m p o s i t i o n ( d e t r i t u s ) and  t r a n s l o c a t i o n to belowground s t r u c t u r e s where they a r e s t o r e d o r  r e l e a s e d d u r i n g death and d e c o m p o s i t i o n . A full  i n v e s t i g a t i o n o f these i n t e r r e l a t i o n s h i p s would go f a r  beyond the scope o f t h i s t r e a t i s e .  C o n s e q u e n t l y , o n l y a few a s p e c t s  o f n u t r i e n t c y c l i n g were examined as p a r t o f the many p l a n t mediated p r o c e s s e s i n the wetlands o f south western B r i t i s h C o l u m b i a .  The  major a s p e c t s d i s c u s s e d under t h i s s e c t i o n i n c l u d e n u t r i e n t c o n c e n t r a t i o n i n the s t a n d i n g crops and l e a c h i n g l o s s e s from the p l a n t s . The r e l e a s e o f n u t r i e n t s v i a d e c o m p o s i t i o n has- been l a r g e l y d i s c u s s e d under S e c t i o n 5 and i s not covered h e r e . Our d a t a were o b t a i n e d s o l e l y from aboveground s t a n d i n g shoots but i t s h o u l d be p o i n t e d out t h a t s t u d i e s o f belowground organs  (roots  and r h i z o m e s ) r e q u i r e s i m i l a r a t t e n t i o n e s p e c i a l l y i n view o f  their  large dry matter y i e l d s  growth  (Table 4 . 9 ) .  Moreover, the p e r e n n i a l  h a b i t o f many w e t l a n d p l a n t s p l a c e s a s i g n i f i c a n t importance on n u t r i e n t r e s e r v e s belowground.  A s p r i n g d e p l e t i o n and f a l l  recharge  159 o f n u t r i e n t s i n the r o o t s and rhizomes might be expected as has been shown i n o t h e r s t u d i e s  7.1  ( K l o p a t e k 1975).  N u t r i e n t C o n c e n t r a t i o n i n the S t a n d i n g Crops  T i s s u e n u t r i e n t l e v e l s have not been w i d e l y e x p l o r e d i n emergent communities o f B r i t i s h Columbia a l t h o u g h a l a r g e body o f  literature  e x i s t s f o r wetlands o f o t h e r r e g i o n s (Keefe 1972, Dykyjova 1973, Hutchinson 1975).  From r e p o r t s on o t h e r w e t l a n d s , d i f f e r e n c e s among  observed n u t r i e n t l e v e l s i n emergent communities are a t t r i b u t e d t o a d d i t i v e e f f e c t s of s p e c i e s (Boyd 1970a, Mason and B r y a n t 1975), fertility  (Boyd and Hess 1970, Wali ejt al_. 1972) and seasonal  (Boyd 1969).  site  trends  Our n u t r i e n t s t u d i e s f o c u s s e d l a r g e l y on t o t a l a s h ,  n i t r o g e n and s u l p h u r .  7.1.1  Total  ash  L a b o r a t o r y a n a l y s i s f o r t o t a l ash i s g e n e r a l l y i n d i c a t i v e o f amount o f m i n e r a l n u t r i e n t s p r e s e n t i n p l a n t s .  the  However, ash v a l u e s  o f t e n i n c l u d e e x t r a n e o u s m a t e r i a l of n o n - p l a n t o r i g i n .  The p r o p o r t i o n  of e x t r a n e o u s m a t e r i a l i s l i k e l y t o be s i g n i f i c a n t i n w e t l a n d which a r e p e r i o d i c a l l y covered w i t h s e d i m e n t - l a d e n w a t e r .  species  Ash  d e t e r m i n a t i o n i s t h e r e f o r e u s e f u l not o n l y f o r e s t i m a t i n g t o t a l  mineral  c o n t e n t o f the p l a n t s but a l s o f o r c o r r e c t i n g o r g a n i c m a t t e r v a l u e s .  160  7.1.1.1  M a t e r i a l s and methods  Dry ground m a t e r i a l s were p r e p a r e d from samples used i n the s t a n d i n g c r o p e s t i m a t i o n s r e p o r t e d i n the p r e v i o u s s e c t i o n s .  These were a n a l y z e d  f o r ash by combustion a t 550° C.  7.1.1.2  O b s e r v a t i o n s and r e s u l t s  Seasonal t r e n d s i n ash c o n t e n t o f s e l e c t e d s p e c i e s are g i v e n Table 7.1 f o r 1976, and T a b l e 7.2 f o r 1977/78. a s t e a d y d e c l i n e i n % ash w i t h t i m e .  in  In both y e a r s t h e r e was  For each s a m p l i n g d a t e , the  Pitt  marsh s p e c i e s g e n e r a l l y had lower ash percentages than those from the t i d a l marshes and a r a b l e o l d f i e l d s .  C a l c u l a t e d ash l e v e l s ( i n g/m  dry  m a t t e r ) i n the s t a n d i n g crops (Table 7.2) d i d n o t show a s i m i l a r and consistent decline.  In most cases ash l e v e l s i n c r e a s e d between May and  O c t o b e r , b u t i n the w i n t e r , a g e n e r a l d e c l i n e was noted f o r some s p e c i e s and an i n c r e a s e i n o t h e r s .  7.1.1.3  Discussion  Due to i n s u f f i c i e n t s a m p l i n g , no s t a t i s t i c a l a n a l y s i s was done on the data.  However, a general t r e n d of i n c r e a s i n g ash c o n t e n t w i t h age o f the  p l a n t s was r e c o r d e d .  Such d e c l i n e s would be a t t r i b u t e d p a r t l y to d e c r e a s e d  m i n e r a l uptake d u r i n g e l a b o r a t i o n o f s t r u c t u r a l c a r b o h y d r a t e s .  The h i g h ash  v a l u e s a s s o c i a t e d w i t h Brunswick marsh s p e c i e s may be a r e s u l t o f  silt  d e p o s i t s on the p l a n t s from t i d e s a l t h o u g h they c o u l d a l s o r e f l e c t the i n n a t e c h a r a c t e r i s t i c s o f the p l a n t s .  Moody ( 1978 ) observed t h a t  washing o f p l a n t m a t e r i a l s from Brunswick marsh d i d n o t change %  161 Table 7.1  Seasonal Changes i n Total Ash (as % Dry Wt.) of Selected Species from Several Sites, 1976.  Location  Species  May  July  Sept.  P i t t marsh  Calamagrostis canadensis  6.5*  5.7  4.8  Iona marsh  Carex lyngbyei  9.0  6.2  4.4  Brunswick marsh  Carex lyngbyei  12.0  9.7  7.7  Festuca arundinacea  9.5  6.2  5.9  Lolium perenne  7.0  5.9  5.3  10.5  8.3  II  it  Alaksen o l d f i e l d II  II  i t  Dactylis glomerata  * Values are averages of two samples.  —  T a b l e 7.2  Seasonal Changes i n T o t a l Ash (as % and as g/m  d r y m a t t e r i n t h e s t a n d i n g crop)  of S e l e c t e d S p e c i e s from S e v e r a l S i t e s , 1977 / 1978.  Location  Species  May 1977  Oct. 1977 g/m  %  g/m  7.6  5.4  52.1  2  P i t t marsh  C a l a m a g r o s t i s canadensis  5.1*  March 1978  2  %  g/m  2  4.6  46.6  it  II  P h a l a r i s arundinacea  6.1  30.9  5.2  102.0  —  —  ii  II  Carex s i t c h e n s i s  5.1  8.4  3.6  30.7  3.2  37.7  II  II  Scirpus cyperinus  6.0  12.0  3.7  40.7  2.8  32.8  II  II  S c i r p u s acutus  —  —  2.8  8.8  —  —  Carex l y n g b y e i  10.7  38.6  7.2  30.5  12.6  48.4  Typha l a t i f o l i a  11.1  42.3  5.3  126.4  5.3  115.8  8.7  48.8  7.5  21.8  6.9  26.2  Brunswick marsh ii  II  Alaksen o l d f i e l d  Dactylis  glomerata  * V a l u e s a r e averages o f two samples.  163 ash s i g n i f i c a n t l y .  Low ash percentages r e p o r t e d f o r P i t t marsh  s p e c i e s p r o b a b l y r e f l e c t low m i n e r a l uptake by p l a n t s growing the o l i g o t r o p h i c  in  habitat.  Ash uptake per u n i t a r e a (Table 7.2) i s i n t e r e s t i n g i n t h a t p a r a l l e l s t o t a l dry m a t t e r p r o d u c t i o n and i t seems t o i n d i c a t e  it  that  the w e t l a n d p l a n t s accumulate a f a i r l y l a r g e amount of m i n e r a l nutrients in t h e i r standing crops.  7.1.2  N i t r o g e n and s u l f u r  F i x e d n i t r o g e n i n w e t l a n d h a b i t a t s appears t o f r e q u e n t l y dry m a t t e r p r o d u c t i o n and a d d i t i o n o f f e r t i l i z e r n i t r o g e n  limit  often  r e s u l t s i n d r a m a t i c y i e l d i n c r e a s e s ( T y l e r 1967, S t e w a r t e t al_. 1973, Haag 1974, V a l i e l a and Teal 1974).  On the o t h e r hand, w e t l a n d sub-  s t r a t e s , p a r t i c u l a r l y those w i t h high o r g a n i c m a t t e r c o n t e n t ,  tend  to possess l a r g e amounts o f t o t a l o r g a n i c n i t r o g e n ( S a n f o r d and L a n c a s t e r 1962).  When o x i d a t i o n o f these s u b s t r a t e s o c c u r s ,  through d r a i n a g e , much o f the n i t r o g e n becomes p o t e n t i a l l y to plants  e.g.  available  (Ponnamperuma 1972, N i c h o l l s and MacCrimmon 1974).  The  c o n c e n t r a t i o n o f n i t r o g e n i n the s t a n d i n g c r o p o f some emergent s p e c i e s was determined as p a r t o f the n i t r o g e n c y c l e i n w e t l a n d s . S u l f u r , l i k e ~ n i t r o g e n , i s t o be found i n c o n s i d e r a b l e amounts i n the p r o t e i n - e n z y m e complexes o f a l l  plants.  Presence of  aromatic  s u l f u r gases was q u i t e e v i d e n t i n some w e t l a n d s u b s t r a t e s i n our s t u d y a r e a s , and s i n c e l i t e r a t u r e on s u l f u r l e v e l s i n w e t l a n d p l a n t s seems t o be s c a n t y , a n a l y s i s f o r t h i s component was c a r r i e d out on a few w e t l a n d s p e c i e s .  164 7.1.2.1  M a t e r i a l s and methods  Total  n i t r o g e n was determined on dry ground samples by the  s e m i - m i c r o K j e l d a h l procedure o f Nelson and Sommers ( 1 9 7 3 ) .  Sulfur  was a n a l y z e d by the t u r b i d i m e t r i c procedure developed by B a r d s l e y and L a n c a s t e r ( 1 9 6 5 ) .  7.1.2.2  A l l samples were o b t a i n e d from green s t a n d i n g s h o o t s .  O b s e r v a t i o n s and r e s u l t s  Seasonal changes i n n i t r o g e n c o n t e n t of the s t a n d i n g crops a r e g i v e n i n T a b l e s 7.3 and 7 . 4 .  There was a general d e c l i n e i n t o t a l N  as t h e season p r o g r e s s e d d u r i n g 1976 and 1977.  The h i g h e s t N c o n t e n t  was o b t a i n e d i n May (1.88% i n 1976 and 2.6% i n 1977) and the  lowest  (0.6%) i n September o r October r e s p e c t i v e l y . N percentages o b t a i n e d i n May 1977 were on average h i g h e r than those o b t a i n e d d u r i n g the same p e r i o d i n 1976, p r o b a b l y  implying  annual v a r i a t i o n i n uptake and l e v e l s i n the s u b s t r a t e . Tables 7.3 and 7.4 a l s o show c o n s i d e r a b l e s p e c i e s v a r i a t i o n terms o f N.  in  The emergent s p e c i e s g e n e r a l l y had s i m i l a r o r even  h i g h e r n i t r o g e n l e v e l s than the t e r r e s t r i a l  species.  C a l c u l a t e d n i t r o g e n l e v e l s per u n i t a r e a (g/m ) g e n e r a l l y  reflected  standing crop y i e l d s . I t i s a p p a r e n t from T a b l e 7.5 t h a t s u l f u r l e v e l s f o l l o w e d  the  same t r e n d as n i t r o g e n , the v a l u e s d e c l i n i n g from May t o O c t o b e r .  It  i s not c l e a r , why the s u l f u r c o n t e n t i n Carex l y n g b y e i , the o n l y t r u l y b r a c k i s h marsh s p e c i e s , i n c r e a s e d d u r i n g the same p e r i o d .  165 T a b l e 7.3  S e a s o n a l Changes i n N i t r o g e n (% Dry Wt.) of S e l e c t e d S p e c i e s from S e v e r a l S i t e s , 1976.  July  Sept.  1.8*  0.8  0.6  Carex l y n g b y e i  1.4  1.0  0.7  Carex l y n g b y e i  1.3  1.1  0.9  Festuca arundinacea  1. 3  0.8  0.8  L o l i u m perenne  1.1  0.6  0.6  D a c t y l i s glomerata  1.3  0.8  May  Location  Species  P i t t marsh  Calamagrostis canadensis  Iona marsh Brunswick marsh  Alaksen old f i e l d  * V a l u e s a r e averages o f two  samples.  166  T a b l e 7.4  S e a s o n a l Changes i n N i t r o g e n (% Dry Wt.  and g/m  i n Dry  M a t t e r of S t a n d i n g Crop) o f S e l e c t e d P l a n t S p e c i e s Several Sites,  from  1977.  May  Location  Species  P i t t marsh  Calamagrostis  canadensis  October  %  , 2 g/m  %  , 2 g/m  1.8*  2.7  0.6  15.6  2.6  13.2  0.8  15.7  ii  II  Phalaris  II  II  Carex s i t c h e n s i s  1.7  1.8  0.7  6.0  it  II  Scirpus cyperinus  1.9  3.8  0.7  7.7  II  II  i S c i r p u s acutus  -  -  0.6  1.9  Carex l y n g b y e i  2.3  8.3  0.8  3.4  Typha l a t i f o l i a  2.1  8.0  0.6  14.3  L o l i u m perenne  2.0  11.2  0.8  2.3  Brunswick marsh II  Alaksen old f i e l d  arundinacea  * V a l u e s a r e averages o f two  samples.  167 T a b l e 7.5  S e a s o n a l Changes i n S u l f u r ( p a r t s per m i l l i o n , Dry Wt.) of  S e l e c t e d P l a n t S p e c i e s from S e v e r a l S i t e s , 1977.  Location  Species  May 10  Oct. 16  P i t t marsh  Calamagrostis canadensis  920*  490  II  II  P h a l a r i s arundinacea  1400  770  II  II  Scirpus cyperinus  1620  810  II  II  Scirpus acutus  1300  335  II  II  Juncus e f f u s u s  1700  740  Carex l y n g b y e i  770  1280  Typha l a t i f o l i a  880  500  L o l i u m perenne  1440  290  Brunswick marsh  Alaksen old f i e l d  * V a l u e s a r e averages o f two  samples.  168 7.1.2.3  Discussion  T i s s u e c o n c e n t r a t i o n s o f N, P, K and S n o r m a l l y f o l l o w the same t r e n d , t y p i c a l l y d e c l i n i n g from s p r i n g t o f a l l Dykjova 1973).  (Boyd 1969, 1970a,  Our r e s u l t s g e n e r a l l y c o n f i r m e d t h i s t r e n d .  The  seasonal d e c l i n e i n N and S may be a t t r i b u t e d , among o t h e r f a c t o r s , t o decreased uptake f o r aboveground p r o d u c t i o n , t r a n s l o c a t i o n to s t o r a g e t i s s u e s belowground, and to l e a c h i n g of n u t r i e n t s from the plants. Species d i f f e r e n c e s  i n % N and S were p r o b a b l y a r e f l e c t i o n  i n n a t e s p e c i e s c h a r a c t e r i s t i c s and s i t e f e r t i l i t y .  of  The amount o f  n i t r o g e n accrued i n the s t a n d i n g c r o p (g/m ) g e n e r a l l y  paralleled  s t a n d i n g c r o p dry m a t t e r p r o d u c t i o n .  7.1.3  Response o f some m a r i t i m e emergents t o f e r t i l i z e r  nitrogen  The n u t r i e n t dynamics o f marsh s o i l s a r e g e n e r a l l y q u i t e from t h e i r t e r r e s t r i a l c o u n t e r p a r t s .  The anaenobic s o i l  different  maintains  reduced compounds and i o n s such as NH4+, h^S, Mn++, Fe++ and CH^ i n s t e a d o f t h e i r o x i d i z e d c o u n t e r p a r t s NO^, S0^~, M n C0  2  + + + +  , Fe  + + +  and  ( H a r t e r 1966). Among t h e n u t r i e n t e l e m e n t s , n i t r o g e n appears t o be c r i t i c a l  many components and p r o c e s s e s i n w e t l a n d s .  for  S i g n i f i c a n t response to  a p p l i e d n i t r o g e n i n terms o f d r y m a t t e r p r o d u c t i o n has been r e p o r t e d f o r s a l t marshes ( S t e w a r t e t al_. 1973, V a l i e l a and T e a l 1974) and o t h e r wetlands ( T y l e r 1967, Haag 1974).  V a l i e l a and Teal  (1974)  suggested t h a t n i t r o g e n i s one o f the most l i m i t i n g f a c t o r s i n marsh  169  p r o d u c t i v i t y , more so than i s phosphorus.  L i k e the o t h e r n u t r i e n t  components, reduced forms o f N such as NH^  (Pesek 1964) a r e o f t e n  more predominant i n w e t l a n d s u b s t r a t e s than the o x i d i z e d forms ( e . g . NOg).  The n i t r a t e forms a r e l o s t e i t h e r through  leaching  ( P a t r i c k and Mahaptra 1968) o r through d e n i t r i f i c a t i o n v i a  nitrate  t o n i t r o g e n gas (Taha e t al_. 1967, Keeney 1 9 7 3 ) . We examined the response o f some w e t l a n d s p e c i e s to f e r t i l i z e r n i t r o g e n p a r t l y because o f our i n t e r e s t i n n i t r o g e n c y c l i n g  in  w e t l a n d s , and a l s o because o f the r e c e n t i n t e r e s t i n the use o f n i t r o g e n f e r t i l i z e r s to enhance p l a n t e s t a b l i s h m e n t i n d i s t u r b e d wetland areas.  The main o b j e c t i v e s o f the study were t o determine  whether a d d i t i o n o f n i t r o g e n r e s u l t e d i n changes i n d r y m a t t e r p r o d u c t i o n and n i t r o g e n c o n t e n t o f the p l a n t s , whether t h e r e was any d i f f e r e n c e i n response between NH^ and NO^ s o u r c e s and whether t h e r e was a " c a r r y - o v e r " e f f e c t to the f o l l o w i n g y e a r .  7.1.3.1  M a t e r i a l s and methods  T h i s t r i a l was undertaken a t seven s i t e s : (2)  Iona marsh,  arundinacea s i t e ) , (6)  (3)  Brunswick marsh,  (5)  (4)  (1)  P i t t marsh,  Colony Farm ( P h a l a r i s  Colony Farm ( D a c t y l i s g l o m e r a t a  U n i v e r s i t y of B. C. Farm,  (7)  A l a k s e n Farm.  site),  S i t e (1) r e p -  r e s e n t e d a f r e s h water marsh, (2) and (3) were b r a c k i s h marshes and the r e s t were a r a b l e o l d  fields.  170  Areas measuring 18 by 8 meters o f r e l a t i v e l y pure stands were earmarked f o r the s t u d y .  On June 12 and 1 3 , 1976, when most o f  w e t l a n d s u b s t r a t e s were wet but w i t h no s t a n d i n g w a t e r ,  the  standing  shoots were c l i p p e d a t ground l e v e l and the p l o t s were c l e a n e d up as much as p o s s i b l e by r a k i n g . as 336 kg/ha each o f (NH ) 4  7.1 g/m control  2  N w h i l e the NaN0  3  2  S0  On June 2 0 , 1976, n i t r o g e n was a p p l i e d 4  and NaNO^.  s u p p l i e d 5.4 g/m  p l o t was a l s o i n c l u d e d .  The (NH ) 4  2  N.  2  S0  4  supplied  An u n f e r t i l i z e d  The e x p e r i m e n t a l d e s i g n was a s p l i t  p l o t w i t h 3 r e p l i c a t i o n s as the main p l o t s , 3 n i t r o g e n s o u r c e s as the s u b - p l o t s and f o u r s t a g e s o f growth (weeks o f regrowth) as s u b - s u b plots. 4 - 5 ,  Samples were taken f o u r times a t i n t e r v a l s o f 3 weeks J u l y 25 - 26, August 15 - 16, and September 5 - 7 ) .  (July  The samples  were o b t a i n e d by randomly p l a c i n g a meter q u a d r a t frame i n each s u b p l o t and c l i p p i n g a l l  the aboveground v e g e t a t i v e g r o w t h .  were taken t o the l a b , d r i e d a t 60C and weighed.  The samples  D r i e d samples were  pooled f o r each t r e a t m e n t , ground and a n a l y z e d i n d u p l i c a t e f o r  nitrogen  by the procedure o f Nelson and Sommers ( 1 9 7 3 ) . On May 1 0 , 1977, a l l  p l o t s from the 1976 t r i a l s were  e x c e p t those t h a t were t r e a t e d w i t h NaNO^-  clipped  NaNOg p l o t s were not  sampled because o f the non s i g n i f i c a n t d i f f e r e n c e i n response t o ammonium and n i t r a t e s o u r c e s o f n i t r o g e n noted i n the 1976 t r i a l s (see T a b l e 7 . 6 ) .  S t a t i s t i c a l a n a l y s e s were done s e p a r a t e l y f o r each  s p e c i e s from each s i t e .  171  7.1.3.2  O b s e r v a t i o n s and r e s u l t s E f f e c t o f n i t r o g e n a p p l i c a t i o n on dry m a t t e r p r o d u c t i o n :  A p p l i c a t i o n o f n i t r o g e n s i g n i f i c a n t l y ( P < 0.01) i n c r e a s e d d r y m a t t e r y i e l d s i n the Brunswick marsh but not i n the P i t t and Iona marshes (Table 7 . 6 ) .  D a c t y l i s glomerata was the o n l y o l d f i e l d  t h a t d i d not respond to n i t r o g e n a p p l i c a t i o n .  species  The h i g h e s t y i e l d r e s -  ponse came from P h a l a r i s a r u n d i n a c e a ( U . B . C . ) f o l l o w e d by L o l i u m perenne and Carex l y n g b y e i (Brunswick m a r s h ) . A n a l y s i s of v a r i a n c e showed a h i g h l y l i n e a r y i e l d i n c r e a s e w i t h advancing s t a g e o f regrowth (Table 7 . 7 ) . noted f o r Carex l y n g b y e i and Carex l y n g b y e i  Q u a d r a t i c responses were  (Iona m a r s h ) , P h a l a r i s a r u n d i n a c e a  (Brunswick m a r s h ) .  This c u r v i l i n e a r  (U.B.C),  relationship  i s p l o t t e d g r a p h i c a l l y f o r P h a l a r i s a r u n d i n a c e a ( U . B . C . ) and Carex lyngbyei  (Iona marsh) i n F i g u r e s 7.1 and 7.2 r e s p e c t i v e l y .  E f f e c t o f n i t r o g e n source on dry m a t t e r p r o d u c t i o n :  In a l l  cases t h e r e was no s i g n i f i c a n t d i f f e r e n c e i n response  between ammonium and n i t r a t e sources o f n i t r o g e n a l t h o u g h T a b l e 7.6 shows some v a r i a t i o n i n response among the s p e c i e s examined.  E f f e c t o f n i t r o g e n a p p l i c a t i o n on N c o n t e n t i n the p l a n t s :  Nitrogen a p p l i c a t i o n increased N content in a l l e x c e p t Carex l y n g b y e i  (Table 7 . 8 ) .  the s p e c i e s  studied  T a b l e 7.6  E f f e c t o f Two Sources o f N i t r o g e n F e r t i l i z e r on Dry M a t t e r P r o d u c t i o n (g/m ).  Control  NH, Source* 4  N0  Calam c_. ( P i t t marsh)  284 - 29  298 - 15  255 - 19  NS  Carex 1_. (Iona marsh)  372 - 50  336 - 21  262 - 28  NS  Carex 1_. (Bruns. marsh)  471 - 39  388 - 29  224 - 34  R i a l , a. ( C o l . Farm)  301 - 45  293 - 35  213 - 15  P h a l . a. (U.B.C.)  577 - 31  549 - 20  228 - 36  Pact, g l . ( C o l . Farm)  392 - 39  490 - 50  427 - 28  L o l . p_.  411 - 18  415 - 27  187 - 30  Means a r e - 1 S.D. ** P ^ 0.01  * D i f f e r e n c e between NH. and N 0  o  J  Source  C o n t r o l v s N Source  Species  4  o  3  NS  source not s i g n i f i c a n t i n a l l cases.  Table 7.7  E f f e c t o f M a t u r i t y Stage on Dry M a t t e r P r o d u c t i o n (g/m ) .  ro  6  9  21  238 ± 3 5  369  25  309 ± 4 2  452  62  272 ± 1 5  404  31  252 ± 2 3  344  41  467 ± 27  534  26  428 ± 6 2  484  55  382 ± 5 3  422  3  Calam c. ( P i t t marsh)  56  Carex 1. (Iona marsh)  158  Carex 1. (Bruns. marsh)  318  P h a l . a. ( C o l . Farm)  65  P h a l . a. (U.B.C.)  245  Dact. g l . ( C o l . Farm)  259  L o l . p_. (Alaksen)  183  * means - 1 S,D.  S i g n i f i c a n c e of Contrasts  Age (Weeks)  Species  + + + + + + +  **  0.01  + + + + + + +  42  453  28  375  41  450  33  416  30  559  60  573  41  364  NS  + + + + + + +  Residual  Linear  Quadr.  29  **  NS  NS  35  **  **  NS  28  **  **  NS  61  **  NS  NS  40  **  **  NS  25  **  NS  NS  28  **  NS  NS  12  Not s i g n i f i c a n t  174  Figure 7.1:  E f f e c t s o f M a t u r i t y and F e r t i l i z e r N i t r o g e n on Dry Matter Production of P h a l a r i s arundinacea i n a U n i v e r s i t y of B r i t i s h Columbia Old F i e l d .  176  F i g u r e 7.2:  E f f e c t s of M a t u r i t y and F e r t i l i z e r N i t r o g e n on Dry M a t t e r P r o d u c t i o n o f Carex l y n g b y e i  i n Iona marsh.  177  50 0  0  3 WEEKS  6 OF  9 REGROWTH  12  T a b l e 7.8  E f f e c t o f N i t r o g e n A p p l i c a t i o n on t h e N Content o f t h e Shoots a t S e v e r a l Stages o f Growth.  3 weeks  Species  Carex 1. (Iona marsh)  No  Carex 1. (Brun. marsh)  No  Calamag. c. ( P i t t marsh)  No  P h a l a r i s a. ( C o l . Farm)  No  L o l i u m p. (Alaksen)  No  D a c t y l i s g. ( C o l . Farm)  l  N  l  N  l  N  l  N  l  N  No N  l  6 weeks  9 weeks  12 weeks  %  g/m  %  , 2 g/m  %  g/m  2.8 2.5  1.2 1.3  3.3 4.4  0.9 1.2  3.4 6.1  0.8 0.9  1.7 4.1  1.3 2.0  2.8 7.5  1.2 1.5  2.4 4.7  0.8 1.0  2.2 4.8  0.8 1,0  1.8 5.9  2.4 3.2  1.3 1.8  1.7 2.3  3.9 5.5  1.2 1.7  4.0 6.4  1.2 1.5  4.5 7.1  3.4 3.2  1.9 2.3  2.2 3.0  4.9 7.9  1.6 2.5  1.8 2.4  6.1 10.9  1.2 3.5  1.5 7.3  1.3 2.1  2.9 9.6  0.9 1.7  2.2 8.5  1.0 1.7  1.6 7.9  2.8 3.6  7.0 9.4  1.8 3.1  7.8 13.0  1.6 2.8  8.0 13.7  1.4 2.6  7.3 15.6  %  / g/m  1.5 1.7  2  2  3.7 10.1 •  2  179 % N g e n e r a l l y decreased w i t h i n c r e a s i n g age o f r e g r o w t h .  It  ranged from a h i g h o f 3.6% f o r f e r t i l i z e d D a c t y l i s g l o m e r a t a a t 3 weeks t o a low o f 0.8% f o r Carex l y n g b y e i a t 12 weeks o f r e g r o w t h . In c o n t a s t t o %N, N y i e l d s (g/m ) i n the p l a n t s g e n e r a l l y i n creased from 3 weeks t o a t l e a s t 9 weeks.  By the 12th week, a d e c l i n e  i n N y i e l d s was e v i d e n t i n Carex l y n g b y e i , L o l i u m perenne and 2 Dactyl i s glomerata.  The h i g h e s t uptake o f t o t a l N was 15.6 g/m  f o r D a c t y l i s g l o m e r a t a a t 12 weeks o f  regrowth.  Recovery of a p p l i e d n i t r o g e n :  Recovery o f a p p l i e d n i t r o g e n i n t h e shoots was c a l c u l a t e d by 2 s u b t r a c t i n g t o t a l N (g/m ) i n u n f e r t i l i z e d c o n t r o l p l o t s from t h a t of f e r t i l i z e d p l o t s .  The c a l c u l a t e d v a l u e s are shown i n T a b l e 7 . 9 .  In g e n e r a l , s p e c i e s growing on a r a b l e o l d f i e l d s r e c o v e r e d a much l a r g e r p r o p o r t i o n o f a p p l i e d n i t r o g e n than those growing on w e t l a n d s . Maximum r e c o v e r y was 135% f o r P h a l a r i s a r u n d i n a c e a ( a t U . B . C . )  while  the l e a s t was 31.5% f o r Carex l y n g b y e i ( a t Iona m a r s h ) . " C a r r y o v e r " e f f e c t of n i t r o g e n a p p l i c a t i o n :  Regarding the c a r r y o v e r e f f e c t o f n i t r o g e n a p p l i c a t i o n , i t  is  c l e a r from T a b l e 7.10 t h a t n i t r o g e n a p p l i e d i n 1976 d i d not have any s i g n i f i c a n t r e s i d u a l e f f e c t on the 1977 s p r i n g g r o w t h .  Moreover,  date o f c u t d u r i n g the p r e v i o u s y e a r d i d not a f f e c t the 1977 s t a n d i n g  180 Table 7.9  Apparent Recovery of Two Nitrogenus F e r t i l i z e r s at 12 weeks Regrowth.  NH. Source 4  7.1 g N applied/m Species  % N recovered  N0„ Source 2  2 5.4 g N applied/m 3  % N recovered  Calam. ( P i t t marsh)  31.0  40.7  Carex 1. (Iona Is.marsh)  39.4  31.5  Carex 1. (Brun.marsh)  69.0  59.3  Phal. a. (Col.Farm)  70.4  85.2  111.3  135.2  Dact.gl. (Col.Farm)  92.9  116.1  L o l . p_. (Alaksen)  85.9  Phal. a. (UBC)  '  94.4  T a b l e 7.10  Summary of the A n a l y s i s of V a r i a n c e of the C a r r y Over E f f e c t o f N i t r o g e n A p p l i e d i n 1976 on 1977 S t a n d i n g  Source o f Variation  Crops.  Calam. c_.  Carex 1.  Carex I.  P h a l . a.  P h a l . a.  Lol_. p_.  P i t t marsh  Iona marsh  Brun.marsh  Col.Farm  U.B.C.  Alaksen  NS  NS  NS  NS  NS  NS  Df  Fertilizer OVS NH, 4  1  E r r o r (A)  4  Date  3  NS  NS  NS  NS  NS  NS  F e r t x Date  3  NS  NS  NS  NS  NS  NS  378 ± 98  347 ± 68  673 ± 147  297 ± 154  213 ±  Error  12  Total  23  Means ± 1 S.D.  NS  Not  -  significant  — 172 + 53  46  182 crop y e i l d s .  Large s t a n d a r d d e v i a t i o n s from the means (averaged  o v e r t h r e e r e p l i c a t e s , two l e v e l s o f n i t r o g e n and f o u r d a t e s ) were r e c o r d e d i n d i c a t i n g marked s p e c i e s and s i t e v a r i a t i o n s .  7.1.3.3  Discussion  E f f e c t o f n i t r o g e n a p p l i c a t i o n on d r y m a t t e r p r o d u c t i o n :  A p p l i c a t i o n of nitrogen increased dry matter y i e l d s of a l l  the  s p e c i e s a l t h o u g h the magnitude o f response v a r i e d c o n s i d e r a b l y w i t h site.  Except f o r the D a c t y l i s g l o m e r a t a s i t e , a s i g n i f i c a n t  was r e c o r d e d i n a l l their substrates.  the o l d f i e l d s r e f l e c t i n g low n i t r o g e n s t a t u s  in  The D a c t y l i s g l o m e r a t a s i t e r e c e i v e s manure f r e -  q u e n t l y making i t r e l a t i v e l y more f e r t i l e than the o t h e r o l d sites.  response  field  No s i g n i f i c a n t response was r e c o r d e d a t the P i t t and Iona  marshes i n d i c a t i n g an adequate s u p p l y o f a v a i l a b l e n i t r o g e n i n t h e substrates.  A h i g h l y o r g a n i c s i t e such as the P i t t marsh would be  e x p e c t e d t o have l a r g e c o n c e n t r a t i o n s o f a v a i l a b l e n i t r o g e n s i n c e i n o r g a n i c n i t r o g e n i s a f u n c t i o n o f o r g a n i c m a t t e r (Jackson 1 9 5 8 ) . The t i d a l marsh s i t e s have f a r l e s s o r g a n i c m a t t e r a c c o u n t i n g i n f o r the p o s i t i v e response r e c o r d e d a t the Brunswick marsh.  part  Carex  l y n g b y e i i n Iona marsh d i d not respond presumably because t h i s marsh r e c e i v e s a l o t o f n u t r i e n t s from nearby sewage  outfill.  Time o f c u t t i n g d i d i n f l u e n c e the magnitude o f response t o a p p l i e d nitrogen.  The c u r v i l i n e a r y i e l d response i n d i c a t e s f i r s t l y t h a t t h e r e  was d e l a y e d response by Carex l y n g b y e i and P h a l a r i s a r u n d i n a c e a  (U.B.C.)  183 and s e c o n d l y t h a t towards the end o f the growing s e a s o n , senescence and m o r t a l i t y l o s s e s f a r out-weighed the e f f e c t of the a p p l i e d  nitrogen  r e s u l t i n g i n an o v e r a l l r e d u c t i o n i n r e s p o n s e .  E f f e c t o f n i t r o g e n s o u r c e on dry m a t t e r p r o d u c t i o n :  There was no d i f f e r e n c e i n y i e l d response between NH^ and NOg sources of n i t r o g e n .  T h i s was unexpected s i n c e d i f f e r e n c e s  between  the two s o u r c e s a r e known t o e x i s t ( e . g . Nowakowski and Cunningham 1966, T y l e r 1967).  P l o t s between t r e a t m e n t s were g e n e r a l l y  close  t o g e t h e r so t h a t l a t e r a l movement o f f e r t i l i z e r a p p l i e d c o u l d have accounted f o r t h i s  discrepancy.  E f f e c t o f n i t r o g e n a p p l i c a t i o n on N c o n t e n t i n t h e p l a n t s :  N i t r o g e n a p p l i c a t i o n i n c r e a s e d N percentages i n a l l a l t h o u g h the magnitude o f response v a r i e d w i t h s p e c i e s . o f N i n the p l a n t s  species Total  studied  quantity  (as g/m ) i n i t i a l l y i n c r e a s e d i n response t o a p p l i e d  n i t r o g e n r e a c h i n g a peak a t about the n i n t h week of regrowth f o r most s p e c i e s , a f t e r which i t d e c l i n e d .  These t r e n d s p a r a l l e l e d changes  in  dry m a t t e r y i e l d s r a t h e r than % N found i n the p l a n t s .  Recovery o f a p p l i e d n i t r o g e n :  The r a t h e r low n i t r o g e n r e c o v e r y v a l u e s (31 - 59.3%) r e c o r d e d the w e t l a n d s i t e s may be a t t r i b u t e d t o n i t r o g e n l o s s e s due t o  in  leaching  184  and d e n i t r i f i c a t i o n i n * t h e i m p e r f e c t l y d r a i n e d s o i l s .  Losses o f  applied  n i t r o g e n appeared to be minimal i n the a r a b l e o l d f i e l d s and r e c o v e r y values i n excess o f the i n i t i a l q u a n t i t i e s o f a p p l i e d n i t r o g e n were r e c o r d e d i n P h a l a r i s a r u n d i n a c e a ( U . B . C . ) and D a c t y l i s glomerata (Table Such h i g h v a l u e s p r o b a b l y r e f l e c t e d low l e a c h i n g and d e n i t r i f i c a t i o n l o s s e s , m i n e r a l i z a t i o n o f o r g a n i c m a t t e r s t i m u l a t e d by the f e r t i l i z e r as w e l l as f e r t i l i z e r e f f e c t from the p r e v i o u s y e a r .  "Carry over" e f f e c t of nitrogen a p p l i c a t i o n :  In a l l  the cases examined, a p p l i c a t i o n o f n i t r o g e n d i d n o t  i n f l u e n c e the dry m a t t e r p r o d u c t i o n the f o l l o w i n g y e a r i n d i c a t i n g e i t h e r complete u t i l i z a t i o n o f a p p l i e d n i t r o g e n the p r e v i o u s y e a r o r l o s s  of  any r e s i d u a l n i t r o g e n through l e a c h i n g and d e n i t r i f i c a t i o n .  7.2  L e a c h i n g o f N u t r i e n t s from the S t a n d i n g Crops  Loss o f n u t r i e n t s by s o l u b i l i z a t i o n and l e a c h i n g i s p r o b a b l y as i m p o r t a n t as n u t r i e n t uptake i n r e g a r d to p l a n t n u t r i t i o n and o v e r a l l n u t r i e n t c y c l i n g i n many e c o s y s t e m s .  Tukey and Mecklenburg (1964)  found t h a t r a d i o a c t i v e l e a c h a t e s from f o l i a g e were r e a b s o r b e d by r o o t s and t r a n s l o c a t e d t o aboveground p a r t s .  They p o i n t e d o u t t h a t  leaching  i s a l s o i m p o r t a n t i n c o m p e t i t i o n between p l a n t s and i n the development o f p l a n t a s s o c i a t i o n s and t h a t the r e c y c l i n g of n u t r i e n t s has i m p o r t a n t implications in plant n u t r i t i o n .  7.  185 Szczepanska and S z c z e p a n s k i (1973) were a b l e to l e a c h measurable amounts o f NHg, NOg, d i s s o l v e d o r g a n i c N, P, K, Ca and Na from v a r i o u s l a k e s h o r e emergent v e g e t a t i o n . most T e a c h a b l e .  B a r s d a t e and P r e n t k i  l o s s o f a p p r o x i m a t e l y 0.4 mg P/m t u n d r a marshes.  They r e p o r t e d t h a t potassium was the (1972) r e p o r t e d a growing season  from Carex a q u a t i l i s i n some a r c t i c  T h i s amounted to a p p r o x i m a t e l y 0.5% o f the a c t u a l  aboveground s t a n d i n g c r o p .  Boyd (1970b) and Mason and B r y a n t (1975)  observed t h a t l e a c h i n g o f n u t r i e n t s from w e t l a n d v e g e t a t i o n i s  especially  r a p i d soon a f t e r shoot d e a t h . V a r i o u s a s p e c t s o f l e a c h i n g from l i v i n g s t a n d i n g c r o p s are examined under t h i s s e c t i o n .  O p p o r t u n i t i e s f o r Teaching o f emergent v e g e t a t i o n  appear t o be e s p e c i a l l y g r e a t i n the t i d a l marshes where some emergents may be f l o o d e d t w i c e a d a y .  R i s i n g and f a l l i n g w a t e r l e v e l s i n the  f r e s h w a t e r P i t t marsh may be s i g n i f i c a n t but f o r most o f the season the emergents s t a n d w e l l above the water  7.2.1  level.  M a t e r i a l s and methods-  The l e a v e s from f i v e s p e c i e s were h a r v e s t e d on 23 August 1977 and t a k e n to the l a b where subsamples were d r i e d a t 105 C and weighed t o o b t a i n percentage dry m a t t e r .  The d r i e d l e a f m a t e r i a l was s t o r e d ,  l a t e r ground i n a W i l e y m i l l and the ash c o n t e n t determined by i g n i t i o n a t 550 C. On 24 A u g u s t , 20 - 30 g (80% average dm) of f r e s h l e a f m a t e r i a l were weighed and suspended i n 800 ml o f d i s t i l l e d water i n containers.  plastic  E i g h t c o n t a i n e r s were a l l o c a t e d t o each s p e c i e s and the  186  c o n t a i n e r s were p l a c e d on a bench i n a c o m p l e t e l y random arrangement. The e x p e r i m e n t was conducted a t room temperature f o r a t o t a l o f 96 h o u r s . A f t e r l e a c h i n g f o r 12 h o u r s , 4 p l a s t i c c o n t a i n e r s f o r each s p e c i e s were removed and the l e a f e x t r a c t was f i l t e r e d and i t s volume d e t e r m i n e d . For ease o f h a n d l i n g , the l e a c h a t e was e v a p o r a t e d t o 50 ml and the e x t r a c t s were t r a n s f e r r e d t o weighed c r u c i b l e s , f r e e z e d r i e d and weighed.  The average w e i g h t o f the r e s i d u e s was d i v i d e d by the c a l -  c u l a t e d dry w e i g h t o f l e a f m a t e r i a l t o o b t a i n the amount o f  leachate  e x p r e s s e d as mg/g l e a f d r y w e i g h t . The ash c o n t e n t of t h e l e a c h a t e was determined by i g n i t i o n  at  550 C f o r 6 h o u r s . The r e m a i n i n g s e t o f c o n t a i n e r s was removed a f t e r 96 hours o f l e a c h i n g and s u b j e c t e d to a s i m i l a r p r o c e d u r e . S i n c e the stomata appear t o be a major avenue f o r  leaching  o f n u t r i e n t s i n l i v i n g v e g e t a t i o n , we d e c i d e d t o check the l e a v e s o f some emergent s p e c i e s f o r presence o r absence o f s t o m a t a .  Simple  methods o f l e a f p r e p a r a t i o n were l a r g e l y adopted from Johansen  (1940).  In most c a s e s , the s u r f a c e s r e q u i r e d f r e e hand c u t t i n g ( e . g . S c i r p u s v a l i d u s ) t o o b t a i n comparable areas under the m i c r o s c o p e . s u r f a c e s were g e n e r a l l y covered w i t h immersion o i l  The  leaf  before taking  stomata! counts.  7.2.2  O b s e r v a t i o n s and r e s u l t s  T a b l e 7.11 shows t h a t a c o n s i d e r a b l e amount o f m a t e r i a l was d i s s o l v e d i n the f i r s t 12 h o u r s .  Moreover, p r o l o n g e d d u r a t i o n o f  187  T a b l e 7.11  Total Leachate  (mg/g L e a f D r y W e i g h t )  Location  Species  12  Pitt  marsh  Phalaris  II  II  Carex  Brunswick marsh Alaksen old field  hrs  96  6 3 - 4  sitchensis  4 6 - 5  5 3 - 3  Carex  lyngbyei  3 2 - 3  6 2 - 3  Lolium  perenne  40 - 4  53  64 - 4  8 0 - 3  45 ± 3  62 -  glomerata  MEAN  * D a t a a r e means -  1 S.E.  (n=4).  * * D i f f e r e n c e b e t w e e n 12 h r s a n d 96 h r s o f l e a c h i n g a r e s i g n i f i c a n t ( P ^ . 0 . 0 1 ) by t t e s t , c a l c u l a t e d t = 7 . 2 1 , t a b u l a t e d t (n=19) = 2 . 6 8 .  Species.'  hrs  4 4 - 3  Dactylis  arundinacea  from S e l e c t e d  ± 4  3**  188 l e a c h i n g s i g n i f i c a n t l y ( P < 0.01) i n c r e a s e d the t o t a l q u a n t i t y o f dissolved material.  These f i n d i n g s a r e i n agreement w i t h those  r e p o r t e d by N y k v i s t ( 1 9 5 9 ) .  The h i g h e s t i n c r e a s e between the two  p e r i o d s was r e c o r d e d i n Carex l y n g b y e i and D a c t y l i s g l o m e r a t a . The l e a c h a t e was p a r t i t i o n e d i n t o o r g a n i c and i n o r g a n i c and the r a t i o s a r e g i v e n i n F i g u r e 7 . 3 .  In a l l  the s p e c i e s  the i n o r g a n i c f r a c t i o n was l e s s than 50% o f t o t a l m a t e r i a l  fractions studied,  leached.  Carex l y n g b y e i and L o l i u m perenne had a h i g h e r p r o p o r t i o n o f m i n e r a l m a t t e r i n the l e a c h a t e compared to the o t h e r  species.  The percentage o f s t a n d i n g c r o p ash r e c o v e r e d i n the  leachate  o v e r the e n t i r e e x p e r i m e n t a l p e r i o d i s g i v e n i n F i g u r e 7 . 4 .  Phalaris  a r u n d i n a c e a l o s t 6.2% of i t s s t a n d i n g c r o p ash w h i l e the o t h e r  species  l o s t between 2 t o 2.8%. T a b l e 7.12 g i v e s e s t i m a t e s o f s t o m a t a l numbers on the surfaces of various wetland s p e c i e s .  leaf  Of i n t e r e s t i s the v a r i a t i o n  i n s t o m a t a l numbers i n the s p e c i e s examined.  No stomata were observed  on the l e a v e s o f Z o s t e r a m a r i t i m a , an a q u a t i c s p e c i e s .  Among the  emergents, s t o m a t a l numbers ranged from 15 on Bromus s i t c h e n s i s 350 on D a c t y l i s s t r i c t a l e a v e s .  to  Stomatal numbers were g e n e r a l l y  e v e n l y d i s t r i b u t e d on the upper and lower l e a f s u r f a c e s o f the p l a n t s .  7.2.3  Discussion  The r e s u l t s showed t h a t a s u b s t a n t i a l amount o f p l a n t m a t e r i a l can be l o s t through l e a c h i n g . The g e n e r a l d e c l i n e i n n u t r i e n t c o n t e n t w i t h m a t u r i t y r e p o r t e d  189  F i g u r e 7.3:  R a t i o o f I n o r g a n i c t o O r g a n i c M a t t e r Leached from the Shoots o f 3 Emergents and 2 A r a b l e Old F i e l d S p e c i e s .  o en  S P E C !  E S  PHAL  ARIS  C A R E X  S.  CAREX  L.  LOLI D ACT  i no r g a n i c  organi  /////////\  zzzzzzzzzzzzzz zzzzzzzzzzzzzza:  U M YLIS o  f /1 it 1111\ 0.5  c  191  F i g u r e 7.4:  P e r c e n t o f S t a n d i n g Crop Ash Recovered i n the Leachate.  > o H  <  r O  o  O  —  m  7J m  C  X  X  . r-  >  lM l  (/)  >  "0  > r-  >  r•  \ \ "0  N  m  \ \ \ \  \  o m 2  m  > O m  O  00  m  O m  193 T a b l e 7.12  Estimates  of S t o m a t a l number Observed under 50 x  M a g n i f i c a t i o n f o r S e v e r a l Wetland  Species.  number o f stomata Species  Zostera  on upper s u r f a c e  maritima  Salicornia virginica  0* 20  on lower  surface  0 20  Scirpus validus  175  175  S c i r p u s paludosus  150  150  90  60  Juncus b a l t i c u s  150  150  Carex l y n g b y e i  200  200  Typha l a t i f o l i a  250  250  15  15  350  350  Elymus  vancouveriensis  Bromus s i t c h e n s i s Distichlis  stricta  * V a l u e s a r e averages from s e v e r a l l e a f s e c t i o n s .  194  i n S e c t i o n 7.1 c o u l d be a t t r i b u t e d i n p a r t t o such l o s s e s . The h i g h e r p r o p o r t i o n o f o r g a n i c to i n o r g a n i c component found i n the l e a c h a t e i s c o n s i s t e n t w i t h the f i n d i n g s o f D a l b r o (1955) who c a l c u l a t e d c a r b o h y d r a t e l o s s e s as h i g h as 800 k g / h e c t a r e / y e a r l i v i n g vegetation.  in  Leached o r g a n i c s o l u b l e s may be an i m p o r t a n t  food s o u r c e t o organisms and decomposers a s s o c i a t e d w i t h the marshes. The g e n e r a l l y low m i n e r a l c o n t e n t found i n the l e a c h a t e s p e c i e s from P i t t marsh p r o b a b l y r e f l e c t s  of  t h e i r i n h e r e n t low m i n e r a l  c o n t e n t w h i l e t h e h i g h v a l u e s f o r Carex l y n g b y e i might be a r e s u l t o f the r e l a t i v e l y h i g h ash c o n t e n t o f t h i s s p e c i e s as w e l l as the d e p o s i t i o n of e x t r a n e o u s s i l t on the shoot s u r f a c e s by t i d a l  activity.  The n a t u r e o f the l e a c h i n g p r o c e s s i s p r o b a b l y f a r more complex than i t appears from t h i s e x p e r i m e n t .  High r a i n f a l l such as e n c o u n t e r e d  i n t h e c o a s t a l areas o f B r i t i s h Columbia would tend t o l e a c h much o f the s o l u b l e c o n s t i t u e n t s i n p l a n t s .  Such l o s s e s would be e x p e c t e d t o  be more s i g n i f i c a n t e s p e c i a l l y i n the t i d a l marshes. Some p l a n t c h a r a c t e r i s t i c s may a l s o be i m p l i c a t e d i n the phenomenon.  leaching  Tukey (1970) c i t e d numerous examples o f p l a n t s from which  l e a c h i n g l o s s e s were r e l a t e d t o the w e t t a b i l i t y of l e a f  surfaces.  M a r t i n and B a t t (1958) found t h a t the amount o f wax on the s u r f a c e of l e a v e s i n f l u e n c e d t h e i r w e t t a b i l i t y thus a f f e c t i n g t h e i r to leaching.  susceptability  The stomata would appear t o be major avenues by which  l e a c h i n g o c c u r s from l e a f s u r f a c e s .  That stomata are p r e s e n t i n emergent  s p e c i e s i n s u b s t a n t i a l numbers was observed i n our s t u d i e s , a l t h o u g h s h o u l d be noted t h a t no stomata were r e c o r d e d i i i Z o s t e r a m a r i t i m a , an  it  195 aquatic species.  The r o l e o f stomata i n l e a c h i n g o f w e t l a n d p l a n t s  awaits f u r t h e r c l a r i f i c a t i o n .  Considerable species v a r i a t i o n  in  s t o m a t a l number, d i s t r i b u t i o n and shape were o b s e r v e d i n o u r s t u d i e s . Such v a r i a t i o n s may be r e l a t e d t o e n v i r o n m e n t a l f a c t o r s and i t  would  appear t h a t the l e a c h i n g p r o c e s s s h o u l d be more m e a n i n g f u l l y examined a l o n g such g r a d i e n t s .  196 8.  GENERAL DISCUSSION AND RECOMMENDATIONS  The l a n d s c a p e s o f B r i t i s h C o l u m b i a , p r o m i n e n t l y m o d i f i e d by g l a c i a t i o n , p r e s e n t many l a r g e and v a r i e d w e t l a n d s .  Rough t o p o g r a p h y ,  and i n many p l a c e s c o n s i d e r a b l e p r e c i p i t a t i o n and modest e v a p o r a t i o n have l e d t o the c r e a t i o n o f marshes, meadows, s l o u g h s and o t h e r t y p e s of wetland i n a l l  p a r t s o f the P r o v i n c e .  These wetlands have not been  w e l l d e l i n e a t e d nor c l a s s i f i e d a l t h o u g h they a r e being r a p i d l y and m o d i f i e d f o r r e s i d e n t i a l , a g r i c u l t u r a l and i n d u s t r i a l  alienated  developments.  Some f e d e r a l and p r o v i n c i a l a g e n c i e s a r e c u r r e n t l y u n d e r t a k i n g i n v e n t o r y and c l a s s i f i c a t i o n based l a r g e l y on s o i l p r o f i l e c h a r a c t e r i s t i c s . complement these e f f o r t s , p a r t i c u l a r l y f o r management p u r p o s e s ,  To  this  study was undertaken i n which p r e d o m i n a n t l y p l a n t - m e d i a t e d p r o c e s s e s were examined.  The i n v e s t i g a t i o n s were e s s e n t i a l l y l i m i t e d t o the  emergent v e g e t a t i o n o f the marshes 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 . The study areas were l o c a t e d i n the P i t t marsh, Brunswick marsh and Iona I s l a n d marsh.  W i t h i n each marsh, the s t u d y was f u r t h e r l i m i t e d t o  a few s p e c i e s and a few v a r i a b l e s .  Some a r a b l e o l d f i e l d s i t e s were  a l s o included f o r comparison. S t u d i e s o f p l a n t - m e d i a t e d p r o c e s s e s i n an ecosystem can be approached i n many d i f f e r e n t ways.  Our i n v e s t i g a t i o n s were r a t h e r broad  i n n a t u r e s i n c e so l i t t l e i s known o f p l a n t p r o c e s s e s i n B r i t i s h Columbia w e t l a n d s , and s i n c e wetlands a r e so w i d e l y d i s t r i b u t e d and " i n d i v i d u a l " wetlands a r e so h i g h l y v a r i e d i n s i z e and n a t u r e .  197 8.1  P r o d u c t i v i t y o f the Emergent V e g e t a t i o n  S t u d i e s o f p r i m a r y p r o d u c t i v i t y a r e o f paramount importance s i n c e t h e y i n v o l v e e s t i m a t i o n o f energy and n u t r i e n t p o t e n t i a l o f w e t l a n d systems; they a r e a l s o c a r d i n a l as a t o o l  i n t h e i r management.  Our  p r o d u c t i v i t y e s t i m a t e s were based l a r g e l y on s i n g l e and m u l t i p l e h a r v e s t s o f aboveground s h o o t s .  Despite d e f i c i e n c i e s  i n methodology,  s e v e r a l i m p o r t a n t f e a t u r e s may be d i s c e r n e d from the s t u d y .  Peak  s t a n d i n g c r o p s were g e n e r a l l y h i g h a l t h o u g h t h e r e were tremendous v a r i a t i o n s between s p e c i e s as w e l l as between s i t e s . s t a n d i n g c r o p was 316 and the h i g h e s t was 1928 g/m  The l o w e s t peak dry m a t t e r f o r  S c i r p u s a c u t u s and P h a l a r i s a r u n d i n a c e a r e s p e c t i v e l y .  The n a t u r e o f  the e n v i r o n m e n t a l f a c t o r s i n f l u e n c i n g d r y m a t t e r p r o d u c t i o n i s  complex  v a r y i n g from marsh t o marsh and from s i t e t o s i t e w i t h i n the marsh. For the m a r i t i m e w e t l a n d c o m m u n i t i e s , c l i m a t e , water r e g i m e ,  salinity  and s u b s t r a t e n u t r i e n t s t a t u s appear t o be the major f a c t o r s .  Adequate  water s u p p l y and average m i l d - c o o l temperatures f a v o u r p h o t o s y n t h e t i c e x p l o i t a t i o n o f the growing season f o r a s i g n i f i c a n t p a r t o f the y e a r a c c o u n t i n g f o r the g e n e r a l l y h i g h s t a n d i n g c r o p s r e c o r d e d i n the s t u d y . Water depth and d u r a t i o n o f f l o o d i n g have c o n s i d e r a b l e on s p e c i e s p r o d u c t i o n and d i s t r i b u t i o n i n w e t l a n d s .  influence  Continuous  flooding  l i m i t s p l a n t growth by w a t e r l o g g i n g r o o t s and t o some e x t e n t by r e d u c i n g light.  Our f i n d i n g s g e n e r a l l y agreed w i t h t h i s c o n t e n t i o n .  In the  Pitt  marsh, S c i r p u s a c u t u s and Equisetum f l u v i a t i l e growing i n s t a n d i n g w a t e r most o f the y e a r had the l o w e s t s t a n d i n g c r o p s w h i l e P h a l a r i s from a l e s s m o i s t a r e a produced the h i g h e s t dry m a t t e r .  arundinacea  S i m i l a r obser-  198 v a t i o n s were made i n the Brunswick marsh; F e s t u c a a r u n d i n a c e a and Typha l a t i f o l i a , growing i n areas where h i g h t i d e s r e a c h o n l y o c c a s i o n a l l y and where the waters a r e l e s s s a l i n e , had h i g h e r s t a n d i n g c r o p s  than  Carex l y n g b y e i which grows i n areas a l m o s t d a i l y covered by t i d a l In the b r a c k i s h environment s a l i n i t y l e v e l s a r e u s u a l l y q u i t e  waters. low  but they f l u c t u a t e i n response t o o t h e r e n v i r o n m e n t a l v a r i a b l e s such as magnitude o f f r e s h e t and w i n t e r r a i n s and t h i s may impose s t r e s s e s on p l a n t s which a r e not n o r m a l l y s u b j e c t t o e x t r e m e s .  Although substrate  s a l i n i t i e s . v a r y on a d a i l y b a s i s i n the F r a s e r d e l t a f o r e s h o r e  according  t o t i d e h e i g h t s , d u r a t i o n o f f l o o d i n g and amount o f r a i n f a l l o r e v a p o r a t i o n , the s a l i n i t y e f f e c t on the p r o d u c t i v i t y of the Brunswick marsh has not been f u l l y i n v e s t i g a t e d .  T h i s e f f e c t would a p p e a r , however, to  be l e s s i n the b r a c k i s h marsh than i n the n e i g h b o u r i n g high s a l i n i t y s a l t marshes. S u b s t r a t e c h a r a c t e r i s t i c s and n u t r i e n t l i m i t a t i o n s o f the marshes were not a major s u b j e c t o f t h i s s t u d y , but the amount and n a t u r e o f  the  sediments d e p o s i t e d s h o u l d r e f l e c t the q u a n t i t y o f n u t r i e n t s p r e s e n t  in  the marshes.  The P i t t marsh, w i t h impeded d r a i n a g e system and h i g h l y  v a r i a b l e water l e v e l s , appears t o r e c e i v e l e s s n u t r i e n t s from a d j o i n i n g areas than the t i d a l marshes.  The h i g h q u a n t i t i e s o f r e a d i l y  available  n i t r o g e n i n the P i t t marsh, e v i d e n t from the f e r t i l i z e r t r i a l s , may be a t t r i b u t e d to the h i g h o r g a n i c m a t t e r c o n t e n t of the s u b s t r a t e as w e l l as man's r e c e n t water c o n t r o l  efforts.  There i s l i t t l e doubt t h a t  this  marsh would q u i c k l y become a bog as a r e s u l t o f d y k i n g ; as y e t o n l y a s m a l l p a r t o f the marsh can be so c l a s s i f i e d .  199 P a r t o f the v a r i a t i o n i n s t a n d i n g c r o p i n the marshes may be a t t r i b u t e d t o i n n a t e c h a r a c t e r i s t i c s o f the s p e c i e s .  Considerable  d i v e r s i t y i n p l a n t form i s t o be encountered i n f r e s h w a t e r and b r a c k i s h water marshes.  Many o f the m o r p h o l o g i c a l f e a t u r e s ,  while  being l a r g e l y a d a p t i v e t o the w e t l a n d e n v i r o n m e n t , may a l s o be i m p l i c a t e d i n the p h o t o s y n t h e t i c f u n c t i o n s o f the p l a n t . ( e . g . Carex l y n g b y e i ) develop f u l l  Some s p e c i e s  p h o t o s y n t h e t i c canopy w h i l e  ( e . g . S c i r p u s a c u t u s ) o c c u r o n l y t h i n l y i n the marshes.  others  The round  non-bladed shoots o f rushes ( S c i r p u s s p p . ) and the t r i a n g u l a r  shoots  o f sedges (Carex s p p . ) may i n some way be r e l a t e d t o p h o t o s y n t h e t i c efficiency.  The e r e c t n a t u r e o f Typha l a t i f o l i a l e a v e s may be an  " a s s e t " to t h i s s p e c i e s i n terms o f a b i l i t y t o q u i c k l y emerge above t h e water l e v e l .  Tremendous v a r i a t i o n s i n s t o m a t a l number, shape  and d i s t r i b u t i o n were a l s o noted i n the marsh s p e c i e s s t u d i e d . A l t h o u g h t h e s e s t o m a t a l v a r i a t i o n s appear t o be r e l a t e d t o e n v i r o n mental g r a d i e n t s , they s h o u l d have some b e a r i n g on the p h o t o s y n t h e t i c c a p a c i t y of the d i f f e r e n t s p e c i e s .  I t i s unfortunate t h a t very  information currently exists r e l a t i n g a l l  little  these i m p r e s s i v e m o r p h o l o g i c a l  f e a t u r e s o f w e t l a n d p l a n t s t o t h e i r p h o t o s y n t h e t i c a b i l i t y and hence their productivity.  The r e l a t i o n s h i p s undoubtedly deserve f u r t h e r  investigation. S i n g l e s t a n d i n g c r o p s d a t a were complemented w i t h d a t a from m u l t i p l e harvests.  S e q u e n t i a l h a r v e s t i n g showed t h a t most s p e c i e s  e x p e r i e n c e d r a p i d growth i n the s p r i n g and e a r l y summer d e c l i n i n g as shoot m o r t a l i t y i n c r e a s e d w i t h the onset o f c o l d weather i n the  fall.  Time o f peak d r y m a t t e r p r o d u c t i o n d i f f e r e d m a r k e d l y w i t h s p e c i e s .  200 Such d i f f e r e n c e s p r o b a b l y r e f l e c t the mode o f a d a p t a t i o n by the species to t h e i r environment.  In some s p e c i e s s p r i n g and e a r l y  summer a r e c h a r a c t e r i z e d by high growth r a t e s f o l l o w i n g e s t a b l i s h m e n t of p h o t o s y n t h e t i c s h o o t s .  early  Carex s i t c h e n s i s  for  example produces shoots i n w i n t e r and these shoots commence v e r y a c t i v e growth w i t h the o n s e t o f good w e a t h e r .  As the growing season p r o -  g r e s s e s such s p e c i e s may possess c o m p e t i t i v e advantages i n terms o f l i g h t and n u t r i e n t s .  E a r l y e s t a b l i s h m e n t i s p o s s i b l e presumably  through m o b i l i z a t i o n o f f o o d r e s e r v e s from belowground to aboveground parts.  In some marsh s p e c i e s , changing water l e v e l s a l s o seems t o  i n f l u e n c e i n i t i a t i o n of a c t i v e growth.  S c i r p u s a c u t u s , f o r example,  commences growth v e r y l a t e i n the growing season when the water  level  has dropped c o n s i d e r a b l y and c o n d i t i o n s f o r growth have i m p r o v e d . Many o f the p h e n o l o g i c a l developments such as time o f shoot emergence and d i f f e r e n t i a l  shoot m o r t a l i t y a l s o account f o r the v a r i a t i o n s  in  time of peak p r o d u c t i o n o f the v a r i o u s marsh s p e c i e s . In c o n c l u s i o n i t s h o u l d be p o i n t e d o u t t h a t f a c t o r s a f f e c t i n g w e t l a n d p r o d u c t i v i t y are complex, some being i n h e r e n t i n the p l a n t and o t h e r s i n the e n v i r o n m e n t .  In such c o n s i d e r a t i o n s , temporal and  s e a s o n a l a s p e c t s o f p l a n t development i n c l u d i n g time o f shoot emergence, p r e s e n c e o f o v e r w i n t e r e d shoots and shoot m o r t a l i t y s h o u l d be t a k e n i n t o account.  Gorham and Sommers (1973) and B e r n a r d and Gorham (1978)  s t r e s s e d t h a t s p e c i e s d i s p l a y i n g c o n s i d e r a b l e green phytomass  in  w i n t e r may have a c o m p e t i t i v e advantage because green w i n t e r shoots can begin growth as soon as c o n d i t i o n s become f a v o u r a b l e .  Moreover,  green w i n t e r shoots o f t e n c o n s t i t u t e the main aboveground organs  these that  201 grow up t o the time of maximum s t a n d i n g c r o p .  Ignorance o f a l a r g e  w i n t e r s t a n d i n g crop would cause one to o v e r e s t i m a t e the net p r i m a r y production of wetlands.  The above workers a l s o p o i n t e d out t h a t the  v e r y h i g h shoot m o r t a l i t y a s s o c i a t e d w i t h many w e t l a n d s p e c i e s may r e s u l t i n u n d e r e s t i m a t i n g t h e i r net p r o d u c t i o n .  This m o r t a l i t y w i l l  a l s o e x e r t c o n s i d e r a b l e i n f l u e n c e upon n u t r i e n t c y c l i n g i n w e t l a n d s . I t s h o u l d be p o s s i b l e t o m o n i t o r t h e s e p h e n o l o g i c a l  changes by t a g g i n g  i n d i v i d u a l shoots and f o l l o w i n g t h e i r c o u r s e o f development through the growing s e a s o n . Undetected l o s s e s o f green growth r e s u l t i n g from consumer a c t ivities  i s a common e r r o r a s s o c i a t e d w i t h p r i m a r y p r o d u c t i o n e s t i m a t e s  d e r i v e d from m u l t i p l e h a r v e s t s .  On the F r a s e r d e l t a marshes, some  of the green shoots o f Carex l y n g b y e i were s p a r i n g l y nipped by widgeon and o t h e r n a t i v e geese and l o c a l  heavy use o f S c i r p u s americanus  shoots i n w i n t e r have been documented f o r t h e F r a s e r d e l t a marshes (Burgess 1970 and Burton 1977).  S u p e r f i c i a l e x a m i n a t i o n s of  the P i t t marsh s p e c i e s showed f a i r l y l a r g e numbers of and phytophagus i n s e c t s .  tidal  phytopathogens  A l t h o u g h g r a z i n g and s i m i l a r a c t i v i t i e s seem  t o be r e l a t i v e l y u n i m p o r t a n t i n the wetlands of south w e s t e r n B r i t i s h C o l u m b i a , the magnitude o f such l o s s e s have not been a c c u r a t e l y quantified. I t was shown i n our s t u d i e s t h a t up t o 85 p e r c e n t o f the t o t a l p r o d u c t i o n o f marsh v e g e t a t i o n may be belowground.  This  observation  not o n l y r a i s e s new fundamental q u e s t i o n s , but t e n d s , i n p r o d u c t i v i t y e s t i m a t e s , t o s h i f t the emphasis from aboveground t o investigations.  belowground  The s e p a r a t i o n o f l i v i n g from dead p o r t i o n s of  underground organs do p r e s e n t c o n s i d e r a b l e d i f f i c u l t i e s .  the  One t e c h n i q u e  202 t h a t may be u s e f u l  i n v o l v e s e x h a u s t i n g belowground r e s e r v e s and  measuring the e t i o l a t e d shoots under s t a n d a r d temperature and m o i s t u r e conditions  (Marx 1963).  Additional  i n f o r m a t i o n on sampling below-  ground biomass i s p r o v i d e d by G a l l a g h e r ( 1 9 7 4 ) , V a l i e l a et^aj_. (1976) and de l a Cruz and Hackney ( 1 9 7 7 ) .  8.2  D i s p o s i t i o n o f Emergent V e g e t a t i o n  I t was p o i n t e d o u t i n S e c t i o n 5 t h a t the phytomass produced as a r e s u l t of p h o t o s y n t h e s i s may be d i s p o s e d through r o u t e s designates as: (3)  (1)  the g r a z i n g r o u t e ,  the d e t r i t a l r o u t e .  (2)  conveniently  a c c u m u l a t i o n r o u t e , and  A l t h o u g h the t h r e e r o u t e s appear t o be common  t o most w e t l a n d s , the r e l a t i v e importance o f each would seem t o v a r y from wetland t o w e t l a n d . Our r e s u l t s , based l a r g e l y on o b s e r v a t i o n s , i n d i c a t e d t h a t the f i r s t o f these r o u t e s i s r e l a t i v e l y unimportant i n the f r e s h w a t e r and b r a c k i s h t i d a l marshes o f south western B r i t i s h C o l u m b i a .  Any  g r a z i n g o f the l i v i n g v e g e t a t i o n i s c a r r i e d out m a i n l y by g a s t r o p o d s , earthworms, i n s e c t s and r e s i d e n t and m i g r a n t w a t e r f o w l . t e b r a t e s a r e r a r e i n the marshes.  Large v e r -  I t s h o u l d be noted t h a t a l t h o u g h  v e r y l i t t l e o f the m a r i t i m e emergents pass v i a the g r a z i n g r o u t e , many o f the i n t e r i o r meadows o f B r i t i s h Columbia a r e h e a v i l y g r a z e d by both n a t i v e and domestic u n g u l a t e s . f o r hay.  The meadows are a l s o  harvested  The main reasons f o r the minimal g r a z i n g o f the m a r i t i m e  marshes are s t i l l u n c e r t a i n . are discussed i n S e c t i o n 8.3.  Possible plant factors l i m i t i n g grazing Any f u t u r e i n v e s t i g a t i o n o f the causes  203  s h o u l d i n c l u d e animal experiments i f a f u l l e r u n d e r s t a n d i n g o f p l a n t - h e r b i v o r e i n t e r a c t i o n s i s t o be a c h i e v e d .  A comparative study  o f t h e c o a s t a l and i n t e r i o r emergents s h o u l d a l s o a i d i n the a n t i - h e r b i v o r e  the  identifying  factors.  The shoots o f emergent v e g e t a t i o n u s u a l l y e n t e r the l i t t e r compartment a f t e r senescence and d e a t h .  Some o f the f a l l e n l i t t e r may  be broken down by p h y s i c a l f o r c e s such as t i d e and w i n d , some by i  biological  f o r c e s such as microbes and some may be o x i d i z e d , e . g . i  through f i r e . '  Any l i t t e r f r a c t i o n which i s n e i t h e r e x p o r t e d t o  o t h e r h a b i t a t s nor used by consumers accumulates i n the s u b s t r a t e . O r g a n i c m a t t e r a c c u m u l a t i o n was a d i s t i n c t f e a t u r e o f the marshes studied.  In the P i t t marsh, the s u b s t r a t e was g e n e r a l l y peaty and  o r g a n i c m a t t e r a c c u m u l a t i o n appeared t o be f a i r l y u n i f o r m o v e r l a r g e areas.  Less o r g a n i c m a t t e r a c c u m u l a t i o n was noted i n the t i d a l marshes.  Moreover, the d i s t r i b u t i o n and t h i c k n e s s of phytomass a c c u m u l a t i o n 1  in  the t i d a l marshes v a r i e d c o n s i d e r a b l y even o v e r v e r y s h o r t d i s t a n c e s . In the t i d a l marshes, much o f the a e r i a l growth i s  eventually  i  degraded and e x p o r t e d t o o t h e r h a b i t a t s so t h a t any o r g a n i c m a t t e r a c c u m u l a t i n g jin the s o i l ground o r i g i n .  p r o f i l e would be e x p e c t e d to be of  under-  In the P i t t marsh, a c c u m u l a t i o n f a r outweighs  export  and the o r g a n i c m a t t e r accumulated o r i g i n a t e s from a e r i a l shoots as  i w e l l as from belowground o r g a n s . still  Many a s p e c t s o f a c c u m u l a t i o n p a t t e r n  remain t o be s t u d i e d i n the marshes of south w e s t e r n B r i t i s h  Columbia.  The l o n g term e f f e c t s o f a c c u m u l a t i o n on s e d i m e n t a t i o n and  system geomorphology s h o u l d be p a r t i c u l a r l y u s e f u l i n u n d e r s t a n d i n g the f u n c t i o n s o f these marshes.  204 A l t h o u g h | s i g n i f i c a n t organic matter accumulation takes place  in  the P i t t and F r a s e r d e l t a marshes, the o l d growth d a t a p r e s e n t e d i n t h i s r e p o r t d e m o n s t r a t e , t h a t a l a r g e p o r t i o n o f the phytomass p r o i  duced i n these systems may e n t e r the d e t r i t a l r o u t e through decomposition.  Decomposition i s a complex phenomenon i n v o l v i n g o x i d a t i o n ,  l e a c h i n g , p h y s i c a l and b i o l o g i c a l  fragmentation.  These p r o c e s s e s a r e  i complex and t h e i r r o l e s are p o o r l y understood i n most w e t l a n d s y s t e m s . Our s t u d i e s , a l t h o u g h broad i n n a t u r e , i d e n t i f i e d some o f e n v i r o n m e n t a l i a n d p l a n t f e a t u r e s p e r t i n e n t to gross processes.  the  decomposition  ;  Much o f the f r a g m e n t a t i o n o f p l a n t m a t e r i a l i n the t i d a l marshes i s e f f e c t e d by p h y s i c a l f o r c e s such as w i n d , t i d e s and f r e s h e t water and the r e s u l t a n t p a r t i c u l a t e m a t t e r i s e x p o r t e d from s i t e as i t The a c t i o n o f these f o r c e s i s by no means u n i f o r m and l o c a l  forms.  accumulation  o f undecomposed p l a n t m a t e r i a l i s not uncommon i n the t i d a l marshes. P h y s i c a l f o r c e s o f communition a r e f a r l e s s n o t i c e a b l e i n t h e P i t t marsh where much o f the o r g a n i c m a t t e r accumulates i n s i t u .  Dead S c i r p u s  a c u t u s s h o o t s may s t a n d e r e c t f o r s e v e r a l y e a r s b e f o r e t h e y a r e broken down and i n c o r p o r a t e d i n the s u b s t r a t e .  E x a m i n a t i o n o f the shoot s u r -  f a c e s w i t h s c a n n i n g e l e c t r o n m i c r o s c o p e showed more a b r a s i o n i n the Brunswick marsh s p e c i e s than i n the P i t t marsh s p e c i e s ; much o f a b r a s i o n undoubtedly a t t r i b u t a b l e t o t i d e s , s i l t and o t h e r moving w i t h  the  particles  freshet.  Temperature i s a v e r y s i g n i f i c a n t f a c t o r i n d e c o m p o s i t i o n p r o c e s s e s . Seasonal t r e n d s i n o l d growth y i e l d s were c o r r e l a t e d w i t h changes  in  ambient t e m p e r a t u r e .  in  Decomposition r a t e s were on the whole lower  205  the P i t t marsh than i n the t i d a l marshes.  The P i t t v a l l e y u s u a l l y  e x p e r i e n c e s lower mean monthly temperatures compared t o the F r a s e r d e l t a f o r e s h o r e where the ocean has a moderating e f f e c t on the temperature regime.  Lower s o i l t e m p e r a t u r e s were p r o b a b l y r e s p o n s i b l e ,  i n p a r t , f o r the lower d e c o m p o s i t i o n r a t e s r e c o r d e d i n b u r i e d l i t t e r bags compared t o those p l a c e d on the s u b s t r a t e s u r f a c e . B e s i d e s t e m p e r a t u r e , low d e c o m p o s i t i o n r a t e s i n the b u r i e d l i t t e r bags c o u l d be a t t r i b u t e d t o low oxygen l e v e l s below the s u r f a c e . A n a e r o b i c d e c o m p o s i t i o n i s c a r r i e d o u t by o b l i g a t e and f a c u l t a t i v e anaerobes which a r e f a r l e s s " e f f i c i e n t " than a e r o b e s .  As p e r i o d i c  i  f l o o d i n g i s c h a r a c t e r i s t i c o f most w e t l a n d s , the a n a e r o b i c f a c t o r  is  i m p o r t a n t not! o n l y f o r d e c o m p o s i t i o n belowground but a l s o f o r decomp o s i t i o n on the s u b s t r a t e s u r f a c e .  A l t h o u g h a n a e r o b o s i s i s a major  f a c t o r f o r the g e n e r a l l y lower r a t e s of d e c o m p o s i t i o n i n w e t l a n d s com-  i pared t o mesic h a b i t a t s , s u b s t a n t i a t i n g d a t a i s r e a l l y q u i t e  limited.  Some of |the observed v a r i a t i o n i n d e c o m p o s i t i o n r a t e s c o u l d be a t t r i b u t e d t o i n n a t e s p e c i e s c h a r a c t e r i s t i c s .  Of a l l  also  the s p e c i e s  s t u d i e d , D a c t y l i s g l o m e r a t a was the most r e a d i l y decomposed.  I t was  f o l l o w e d by Carex l y n g b y e i , P h a l a r i s a r u n d i n a c e a , S c i r p u s a c u t u s , Juncus e f f u s u s and Carex s i t c h e n s i s i n t h a t o r d e r .  These  differences  i  would seem t o r e f l e c t the chemical c o m p o s i t i o n o f the s p e c i e s .  Less  f i b r o u s s p e c i e s would be expected t o break down more r e a d i l y than highly fibrous species.  In our d e c o m p o s i t i o n s t u d i e s , young f l e s h y  shoots were a s s o c i a t e d w i t h h i g h e r r a t e s than the more f i b r o u s o v e r wintered shoots.  Some s p e c i e s i n the F r a s e r d e l t a marshes, e . g .  S a l i c o r n i a m a r i t i m u s tend t o possess f l e s h y s u c c u l e n t s h o o t s , i  apparently  206  as an a d a p t i v e f e a t u r e to the s a l i n e environment.  During d e c o m p o s i t i o n  t h e s e f l e s h y p a r t s are r a p i d l y l o s t l e a v i n g h i g h l y r e s i s t a n t s k e l e t a l t i s s u e s i n the c e n t r a l c o r e .  Most P i t t marsh s p e c i e s took l o n g e r t o  decompose than the Brunswick marsh s p e c i e s p r o b a b l y because o f high f i b r e c o n t e n t .  their  Thus the a e r i a l shoots o f the P i t t marsh s p e c i e s  remain l a r g e l y undecomposed c o n t r i b u t i n g t o the peaty h o r i z o n o f the s u b s t r a t e p r o f i l e f a r more than those from the Brunswick marsh s p e c i e s . Much i n f o r m a t i o n on d e c o m p o s i t i o n p r o c e s s e s can be o b t a i n e d through l i t t e r bag s t u d i e s . to be c r i t i c a l  C h o i c e of bags w i t h p r o p e r mesh appears  for accurate r e s u l t s .  A ' c o a r s e ' mesh may cause  sig-  n i f i c a n t l o s s e s o f p l a n t fragments t o o c c u r through the bags whereas a ' f i n e ' mesh, may e x c l u d e decomposer animals from the bags. scanning e l e c t r o n microscope technique f o r studying p l a n t a l s o shows c o n s i d e r a b l e . p r o m i s e i n d e c o m p o s i t i o n s t u d i e s .  The  surfaces If  used  i n c o n j u n c t i o n w i t h l i t t e r bags, i t s h o u l d p r o v i d e answers t o such questions as: decomposition?  what changes take p l a c e on p l a n t s u r f a c e s d u r i n g What happens t o t h e c u t i c l e ?  What happens t o the  i n t e r n a l t i s s u e s a f t e r the c u t i c l e i s removed?  The i n v i t r o  technique  ( B u r k h o l d e r and B o r n s i d e 1957) s h o u l d a i d i n s t u d y i n g the f i n e r of d e c o m p o s i t i o n p r o c e s s e s .  initial  aspects  A l t h o u g h the t e c h n i q u e i s not w i t h o u t  its  a s p e c t s o f a r t i f i c i a l i t y and time c o n s t r a i n t s , our s t u d i e s showed t h a t the method g i v e s r e s u l t s comparable t o those o b t a i n e d u s i n g l i t t e r bags. B e s i d e s r e f i n i n g o f the t e c h n i q u e s , t h e r e are many areas of d e c o m p o s i t i o n which r e q u i r e immediate a t t e n t i o n .  In a d d i t i o n t o t h e  s p e c i e s s t u d i e d , t h e r e a r e many o t h e r s p e c i e s which o c c u r i n p r o p o r t i o n s i n the marshes t o m e r i t s t u d y .  significant  Very l i m i t e d d a t a i s  207 a v a i l a b l e t o date on the d e c o m p o s i t i o n o f r o o t s and r h i z o m e s .  Our  s t u d i e s have shown t h a t underground phytomass may be a t l e a s t 7 times h i g h e r than t h a t aboveground.  S t u d i e s o f r o o t s and rhizome decompos-  i t i o n a r e t h e r e f o r e e s s e n t i a l f o r a complete u n d e r s t a n d i n g o f  the  o v e r a l l ecosystem f u n c t i o n s o f the w e t l a n d s . Decomposition s h o u l d r e p r e s e n t an i m p o r t a n t process i n the m a r i t i m e wetlands o f B r i t i s h Columbia e s p e c i a l l y i f  it  the n u t r i e n t elements b u i l t i n t o the o r g a n i c t i s s u e .  regenerates The c o n t r i -  b u t i o n made by l i t t e r d e c o m p o s i t i o n t o marsh n u t r i e n t r e c y c l i n g o n l y v a g u e l y known.  is  C r i t i c a l q u e s t i o n s c e n t r e on the problem o f  d e t r i t u s u t i l i z a t i o n and secondary p r o d u c t i o n .  How much o f  the  n u t r i e n t s r e l e a s e d d u r i n g d e c o m p o s i t i o n i n the Brunswick marsh c o n t r i b u t e s t o the F r a s e r e s t u a r i n e f o o d web?  I t has been shown i n o t h e r  s t u d i e s t h a t m i c r o b i a l d e c o m p o s i t i o n improves the q u a l i t y o f r e s u l t a n t d e t r i t u s e s p e c i a l l y by i n c r e a s i n g the p r o t e i n  the  content.  Is t h i s t r u e f o r the marshes o f south western B r i t i s h Columbia?  Our  s t u d i e s showed the energy c o n t e n t o f the l i v i n g shoots t o be a p p r o x i m a t e l y 4.4 K c a l / g dry m a t t e r i r r e s p e c t i v e o f s p e c i e s . c a l o r i c c o n t e n t h o l d f o r decomposing  8.3  Does t h i s  litter?  Proximate Chemical Components o f Emergent V e g e t a t i o n as a F a c t o r i n t h e Wetland System  Wetland emergent v e g e t a t i o n o c c u p i e s a p o s i t i o n i n the somewhat between d r y l a n d and a q u a t i c h a b i t a t s .  landscape  The e r e c t and r i g i d  n a t u r e o f t e r r e s t r i a l s p e c i e s i s m a i n t a i n e d by s u p p o r t i v e elements  208  which have been f a i r l y w e l l d e l i n e a t e d .  Such t i s s u e s a r e g e n e r a l l y  l a c k i n g i n a q u a t i c s p e c i e s s i n c e s u p p o r t i s rendered by w a t e r . U n l i k e a q u a t i c s p e c i e s , emergents r e q u i r e e l a b o r a t e s u p p o r t i v e s i n c e they a r e n o r m a l l y r o o t e d i n the s u b s t r a t e .  Except f o r  tissues  species  such as Polygonum amphibium and Ranunculus t r i c h o p h y l l u s , p a r t s  of  emergent p l a n t s must a l s o develop above the water l e v e l i n o r d e r t o r e s p i r e , t r a n s p i r e and o b t a i n 'enough" r a d i a n t energy f o r p h o t o s y n thesis. S t r u c t u r a l t i s s u e s a r e composed l a r g e l y o f c e l l u l o s e , l i g n i n , s i l i c a , and o t h e r r e l a t e d compounds.  hemicellulose,  These components may  occur i n d i f f e r e n t proportions i n d i f f e r e n t plant groupings.  In g e n e r a l ,  t h e emergent s t u d i e d c o n t a i n e d h i g h l e v e l s o f NDF, ADF, and l i g n i n but v e r y low l e v e l s o f s i l i c a .  A l t h o u g h s i l i c a l e v e l s were low i n  the emergents s t u d i e d , t h i s component p r o v i d e s the main s u p p o r t i v e s t r u c t u r e f o r a few emergents such as Equisetum spp.  S i l i c a is  also  found i n s u b s t a n t i a l q u a n t i t i e s i n many t r u e g r a s s e s from t e r r e s t r i a l habitats. All  these s t r u c t u r a l components, w h i l e o f f e r i n g s u p p o r t ,  l i m i t d e g r a d a t i o n o f the p l a n t o r p l a n t p a r t s .  Phalaris  usually  arundinacea  and Carex s i t c h e n s i s both w i t h low d e c o m p o s i t i o n r a t e s , f o r example, c o n t a i n e d h i g h l e v e l s of NDF, ADF, and l i g n i n . Carex l y n g b y e i degraded more r a p i d l y .  The l e s s  fibrous  NDF and l i g n i n p e r c e n t a g e s  in  the emergents were g e n e r a l l y h i g h e r , s t a g e by s t a g e , than those commonly r e p o r t e d f o r c u l t i v a t e d f o r a g e c r o p s .  Such high l e v e l s  p r o b a b l y e x p l a i n , a t l e a s t i n p a r t , the l i m i t e d use o f the marsh s p e c i e s by h e r b i v o r e s .  NDF l e v e l s above 55 - 60 p e r c e n t seem t o  limit  s i g n i f i c a n t l y the i n t a k e o f f o r a g e s by h e r b i v o r e s (Van S o e s t 1965).  209 I t appears t h a t d e g r a d a t i o n may be b e t t e r understood i f a s s a y i s supplemented w i t h h i s t o l o g i c a l parts.  Comparative h i s t o l o g i c a l  chemical  e x a m i n a t i o n o f the p l a n t  s t u d i e s showed l i g n i f i e d  tissues  t o be more w i d e l y d i s t r i b u t e d i n P h a l a r i s a r u n d i n a c e a , a g r a s s , than i n Carex l y n g b y e i , a sedge.  F u r t h e r m o r e , the sedge had much l o o s e  parchymatous t i s s u e w h i l e the g r a s s p o s s e s s e d c l o s e l y packed c e l l s with l i t t l e internal surface.  Such f e a t u r e s s h o u l d be o f  s i g n i f i c a n c e i n d i g e s t i b i l i t y and d e c o m p o s i t i o n p a t t e r n s .  considerable The f l e s h y  o u t e r t i s s u e s o f Carex l y n g b y e i degrade q u i t e r e a d i l y l e a v i n g behind a s k e l e t o n o f s l o w l y degradable t i s s u e s .  I t i s p o s s i b l e to study  the c o m p o s i t i o n o f the r e s i d u a l s t r u c t u r a l t i s s u e s through  histological  examinations. P l a n t d r y m a t t e r may be d i v i d e d i n t o c e l l w a l l  constituents  c o n s i s t i n g l a r g e l y of f i b r e , l i g n i n and s i l i c a ; and the c e l l  contents  c o n s i s t i n g of s o l u b l e c a r b o h y d r a t e s , p r o t e i n s , o r g a n i c a c i d s and l i p i d s . As a l r e a d y d i s c u s s e d , the c e l l w a l l c o n s t i t u e n t s w h i l e p r o v i d i n g  support  t o the p l a n t , may, depending on the l e v e l s , l i m i t g r a z i n g and decomposi t i o n o f the p l a n t s . degradable and i f  On the c o n t r a r y , c e l l c o n t e n t s are a l m o s t c o m p l e t e l y  r e t u r n e d to the s u b s t r a t e they are r e a d i l y used by  p l a n t s , decomposers and o t h e r organisms a s s o c i a t e d w i t h the w e t l a n d s . A s u b s t a n t i a l amount of s o l u b l e m a t e r i a l s both e l e c t r o l y t e s and n o n - e l e c t r o l y t e s a r e l o s t from l i v i n g emergent v e g e t a t i o n through leaching.  L e a c h i n g l o s s e s i n some emergents ranged from 45 t o 64 mg/g  l e a f dry w e i g h t i n 96 h o u r s .  Loss o f s o l u b l e substances from l i v i n g  p l a n t s i s l i k e l y t o be s i g n i f i c a n t i n the m a r i t i m e w e t l a n d s o f western B r i t i s h Columbia because t h i s a r e a r e c e i v e s p l e n t y o f  south rainfall  e s p e c i a l l y i n the w i n t e r months and t i d a l a c t i v i t y i s q u i t e prominent  210 i n the Fraser d e l t a f o r e s h o r e .  There i s u n c e r t a i n t y p a r t i c u l a r l y about  l e a c h i n g i n p l a n t s of the t i d a l marshes because they are i n many i n s t a n c e s water covered t w i c e a day.  S i n c e most l e a c h i n g o c c u r s  through the stomata and not through the c u t i c l e i n t e r r e s t r i a l  plants,  i t became a m a t t e r o f i n t e r e s t t o examine s t o m a t a l d i s t r i b u t i o n the emergents.  in  We r e c o r d e d c o n s i d e r a b l e v a r i a t i o n s i n s t o m a t a l number,  shape and d i s t r i b u t i o n .  The stomata were g e n e r a l l y numerous i n  highly  r e g u l a r p a t t e r n s u s u a l l y w i t h a l t e r n a t i n g p h o t o s y n t h e t i c and nonp h o t o s y n t h e t i c bands. terms o f l e a c h i n g ?  What i s the s i g n i f i c a n c e o f t h e s e v a r i a t i o n s  There must be some p h y s i o l o g i c a l mechanisms i n the  emergents which c o n t r o l l e a c h i n g l o s s e s .  I t i s p o s s i b l e t h a t some o f  the p l a n t s a r e adapted t o such l o s s e s even i f so f r e q u e n t l y .  in  they a r e c o v e r e d by water  I t i s a l s o p o s s i b l e t h a t p l a n t s which are not so  adapted t o l e a c h i n g a r e t o l e r a n t o f h i g h s a l t c o n c e n t r a t i o n w i t h the plant possessing special salt-removing organs, t y p i c a l o f many x e r o p h y t i c p l a n t s .  characteristics  The mechanisms i n v o l v e d i n l e a c h i n g o f  p l a n t s s h o u l d be i n v e s t i g a t e d .  these  The f a c t t h a t m e t a b o l i c a l l y i m p o r t a n t  m a t e r i a l s are l e a c h e d from the p l a n t s i n c l u d i n g i n o r g a n i c m a t e r i a l s , c a r b o h y d r a t e s , amino a c i d s and o r g a n i c a c i d s  (Tukey and Morgan 1964)  s u g g e s t s t h a t p l a n t l e a c h a t e s may be an i m p o r t a n t s o u r c e o f  nutrients  f o r p l a n t s and organisms i n the w e t l a n d h a b i t a t . Loss o f s o l u b l e c o n s t i t u e n t s o c c u r s not o n l y i n l i v i n g but a l s o i n dead p l a n t p a r t s .  vegetation  In our s t u d i e s , dead o v e r w i n t e r i n g  shoots l o s t from 4 t o 50% o f t h e i r d r y w e i g h t s between November and March.  Much o f t h i s l o s s c o u l d be a t t r i b u t e d to l e a c h i n g of the  "solubles".  The h i g h i n i t i a l  l o s s e s i n the l i t t e r bag and i n  vitro  211 d e c o m p o s i t i o n s t u d i e s were a l s o s u g g e s t i v e o f l e a c h i n g .  These  " s o l u b l e s " presumably p l a y s i g n i f i c a n t r o l e s i n subsequent d e c o m p o s i t i o n and i n the n a t u r e o f t h e o r g a n i c l a y e r s which accumulate and u l t i m a t e l y become p e a t , l i g n i t e and s i m i l a r m a t e r i a l s . P r o t e i n s c o n s t i t u t e an i m p o r t a n t p a r t of r e a d i l y plant fractions.  degradable  We s t u d i e d t h i s component by d e t e r m i n i n g t o t a l  n i t r o g e n (crude p r o t e i n = N x 6.25) i n s e l e c t e d emergent s h o o t s . C o n s i d e r a b l e s p e c i e s d i f f e r e n c e s were r e c o r d e d ; the p e r c e n t a g e s r a n g i n g from 0.6 i n S c i r p u s acutus t o 1.7 i n P h a l a r i s a r u n d i n a c e a . Large seasonal v a r i a t i o n s were a l s o r e c o r d e d f o r a l l s p e c i e s ,  nitrogen  l e v e l s g e n e r a l l y d e c l i n i n g as the season p r o g r e s s e d . The d e c l i n e i n n i t r o g e n (and s i m i l a r l y crude p r o t e i n ) o f  the  emergents i s accompanied, as mentioned e a r l i e r , by an i n c r e a s e i n the f i b r o u s components.  A l t h o u g h the s t r u c u t r a l components o f t h e emergent  s p e c i e s a r e g e n e r a l l y h i g h and the crude p r o t e i n l e v e l s l o w , the q u a l i t y o f the v e g e t a t i o n remains f a i r l y high e a r l y i n the growing season.  One might t h e r e f o r e e x p e c t v e r y young emergents t o be  a t t r a c t i v e t o h e r b i v o r e s and y e t t h i s does not seem t o be the case the c o a s t a l marshes.  in  I t may be p o s t u l a t e d t h a t e a r l y i n the growing  s e a s o n , f l o o d i n g and o t h e r u n f a v o u r a b l e c o n d i t i o n s d i s c o u r a g e g r a z e r s from u t i l i z i n g the high q u a l i t y v e g e t a t i o n .  L a t e i n the growing  season when f l o o d i n g i s m i n i m i z e d and o t h e r c o n d i t i o n s have improved, low q u a l i t y o f the emergents i n v a r i a b l y r e s t r i c t s t h e i r a v a i l a b i l i t y to h e r b i v o r e s .  P h e n o l i c s a r e a group o f secondary p l a n t  substances  t h a t c o u l d a l s o be i m p l i c a t e d i n the r e l a t i v e u n a c c e p t a b i l i t y o f  the  212 young l o w - f i b r e and h i g h - n i t r o g e n t i s s u e s .  If Dactyl i s glomerata,,  a w i d e l y a c c e p t e d s p e c i e s f o r g r a z i n g and one t h a t decomposes r e a d i l y , i s used as a s t a n d a r d f o r comparison w i t h o t h e r s p e c i e s , then i t seems u n l i k e l y from our s t u d i e s t h a t g r a z i n g and d e c o m p o s i t i o n of the marsh s p e c i e s a r e l i m i t e d by t o t a l p h e n o l i c c o n t e n t . l e v e l s i n the P i t t marsh s p e c i e s appeared further studies. will  However,  tidal phenolic  t o be high enough t o w a r r a n t  Techniques f o r d e t e r m i n i n g such secondary compounds  have t o be r e f i n e d and s t a n d a r d i z e d b e f o r e c a r r y i n g out the  investigations. Ash c o n s t i t u e n t s may be r e c o v e r e d i n s i g n i f i c a n t amounts i n the plant "solubles".  L a b i l e elements such as p o t a s s i u m and sodium s h o u l d  be r e c o v e r e d i n l a r g e q u a n t i t i e s w h i l e immobile ones such as c a l c i u m tend t o remain i n the i n s o l u b l e p l a n t f r a c t i o n s .  In our s t u d i e s  than 10 p e r c e n t o f the t o t a l ash was r e c o v e r e d i n the l e a c h a t e .  less Total  ash l e v e l s i n the s h o o t s , as determined by c o m b u s t i o n , v a r i e d o n l y s l i g h t l y w i t h age and s p e c i e s .  The P i t t marsh s p e c i e s g e n e r a l l y had  lower ash percentages than the t i d a l marsh s p e c i e s .  The low ash v a l u e s  r e c o r d e d i n the P i t t marsh s p e c i e s may be a s s o c i a t e d w i t h the grazing a c t i v i t y in t h i s oligotrophic habitat.  limited  The h i g h ash v a l u e s  r e c o r d e d i n the Brunswick marsh s p e c i e s may be a t t r i b u t e d t o e x t r a n e o u s s i l t d e p o s i t e d on the p l a n t s by t i d e and f r e s h e t water o r they may be an i n h e r e n t c h a r a c t e r i s t i c of b r a c k i s h marsh s p e c i e s . In view o f the p a s t and p r e s e n t r a p i d r a t e o f commercial e x p l o i t a t i o n o f the wetlands o f B r i t i s h C o l u m b i a , f u t u r e r e s e a r c h p l a n s assume an added urgency because answers a r e needed f o r c o n s e r v a t i o n and management p u r p o s e s .  Much p r o g r e s s can be a c h i e v e d by  213 f o c u s i n g on the p r o c e s s e s a t work i n the w e t l a n d s , f o r u n t i l p r o c e s s e s are b e t t e r u n d e r s t o o d , i t w i l l  these  be i m p o s s i b l e to make i n -  formed judgements about the w i s e use o f t h e s e w e t l a n d s .  Throughout  t h i s r e p o r t , i t has been e v i d e n t t h a t a l a r g e degree o f  variability  e x i s t s both w i t h i n and between marshes.  This c a l l s f o r great care  not o n l y i n a p p l y i n g r e s u l t s from one marsh ecosystem t o a n o t h e r but a l s o i n d e s i g n i n g f i e l d r e s e a r c h i n any one marsh.  214 BIBLIOGRAPHY  Adams, D.A. 1963. F a c t o r s i n f l u e n c i n g v a s c u l a r p l a n t z o n a t i o n i n North C a r o l i n a s a l t marshes. E c o l o g y 44: 445-456. Adams, G.C. and S . C . Z o l t a i 1969. Proposed openwater and w e t l a n d classification. 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North American F o r e s t S o i l s Conf. 4: 497-511.  Appendix I  % O r g a n i c M a t t e r Decomposed i n L i t t e r Bags, where Bags were P l a c e d on t h e Substrate Surface.  o  CO CM  Species  Time (days)  Brunswick marsh %  Pitt marsh %  Alaksen %  P h a l a r i s arundinacea  74 148 294  27.2* 27.8 52.0  22.2 22.2 53.0  21.5 22.1 52.7  Carex s i t c h e n s i s  74 148 294  24.0 24.9 18.7  16.9 17.1 34.9  7.8 10.6 31.2  S c i r p u s acutus  74 148 294  28.7 29.7 43.7  24.3 21.6 52.2  23.6 24.7 46.2  Juncus e f f u s u s  74 148 294  26.0 27.1 39.4  20.7 23.4 44.5  14.7 25.1 62.8  Carex l y n g b y e i  74 148 294  27.8 30.6 60.6  24.2 26.3 64.0  22.6 29.6 68.8  D a c t y l i s glomerata  74 148 294  41.4 42.3 78.7  33.6 37.4 78.2  31.8 35.3 93.1  * V a l u e s a r e averages o f two samples  Appendix I I  A n a l y s i s o f V a r i a n c e o f % Organic M a t t e r Decomposed i n L i t t e r Bags, where Bags were P l a c e d on the S u b s t r a t e S u r f a c e .  oo CM  Source o f Variation  DF  Sum SQ  Mean SQ  F-Value  Significance  Location  2  70.7  35.3  1.5  NS  Time  2  19833.0  9916.5  420.2  **  Time x L o c a t i o n  4  1311.9  328.0  13.9  **  Species  5  9860.7  1972.1  63.2 ( E r r o r A)  **  Time x S p e c i e s  10  3038.0  303.8  9.7  Error A  30  935.4  31.2  1.3  Error  54  1272.7  23.6  Total  107  36323.0  ** S i g n i f i c a n t a t 1% l e v e l o f p r o b a b i l i t y NS Not s i g n i f i c a n t  ( E r r o r A)  ** NS  Appendix I I I  % O r g a n i c M a t t e r Decomposed i n L i t t e r Bags, where Bags were P l a c e d 15 cm Below the S u r f a c e .  Species  P h a l a r i s arundinacea  Carex l y n g b y e i  D a c t y l i s glomerata  Time (days) 73  Brunswick marsh  7.0*  Pitt marsh  Alaksen  6.6  13.4  146  21.0  11.4  34.1  73  7.5  6.6  14.4  146  12.2  10.5  32.9  73  5.0  8.4  14.8  146  19.5  15.0  40.0  * V a l u e s a r e averages o f two samples.  Appendix IV  A n a l y s i s o f V a r i a n c e o f % Organic M a t t e r Decomposed i n L i t t e r Bags Bags were P l a c e d 15 cm Below t h e S u r f a c e .  Source o f Variation  DF  Sum SQ  Mean SQ  Location  2  1604.6  802.3  146.8  Date  1  1412.5  1412.5  261.6  Date x L o c a t i o n  2  412.7  206.3  37.7  Species  2  57.0  28.5  3.7 ( E r r o r A)  Date x S p e c i e s  2  63.2  31.6  4.1 ( E r r o r A)  Error A  8  61.6  7.6  18  98.4  5.5  Error  ** S i g n i f i c a n t (P < 0.01) NS  Not s i g n i f i c a n t  F-Value  1.4  Appendix V  I n V i t r o Decomposition o f O v e r w i n t e r e d Shoots from Wetland and C o n t r o l S p e c i e s ; Expressed as % O r g a n i c M a t t e r L o s s .  Brunswick marsh i n o c u l u m  P i t t marsh i n o c u l u m  Species  Time (days)  No H y s o l  Hysol  No H y s o l  Hysol  P h a l a r i s arundinacea  21 42  9.3* 13.9  13.2 12.1  9.8 18.1  11.9 18.9  Carex s i t c h e n s i s  21 42  10.7 13.5  12.0 17.2  9.3 18.9  9.5 17.7  Carex l y n g b y e i  21 42  19.2 23.3  22.6 26.0  20.0 28.7  25.5 26.9  Dactylis  21 42  12.6 22.4  14.2 24.6  16.1 24.7  17.1 24.5  21 42  8.6 10.3  10.3 10.0  9.9 9.8  10.3 10.7  Control  *  glomerata  (sterile)  V a l u e s a r e averages o f two samples  Appendix VI  Analysis of Variance of % Organic Matter Loss In V i t r o ; Overwintered Shoots.  DF  Sum SQ  Mean SQ  F-Value  Inoculum Source Additive Time Species  1 1 1 4  52.3 35.0 502.5 2012.8  52.3 35.0 502.5 503.2  45.5 30.3 437.7 436.3  ** ** ** **  Inoculum x Additive Inoculum x Time Inoculum x Species Additive x Time Additive x Species Time x Species  1 1 4 1 4 4  6.2 17.0 18.0 13.5 7.0 155.9  6.2 17.0 4.5 13.5 1.7 39.0  5.4 14.7 3.9 11.7 1.5 33.8  NS ** ** ** NS **  Inoculum x Add. x Time Inoculum x Add. x Species Inoculum x Time x Species Add. x Time x Species  1 4 4 4  1.2 6.7 47.5 16.4  1.2 6.7 11.9 4.1  1.1 1.4 10.3 3.5  NS NS ** NS  Inoculum x Add. x Time x Species  4  20.7  5.1  4.5  **  Error  40  46.1  1.1  Total  79  2959.0  Source of Variation  ** NS  S i g n i f i c a n t (P < 0.01) Not Significant  Significance  Appendix V I I  I n V i t r o Decomposition o f Young Shoots from Wetland and C o n t r o l S p e c i e s ; Expressed as % Organic M a t t e r L o s s .  Brunswick marsh i n o c u l u m  P i t t marsh i n o c u l u m  Time (days)  No H y s o l %  Hysol %  No H y s o l %  Hysol %  P h a l a r i s arundinacea  21 42  59.7* 67.2  60.2 63.9  64.5 62.5  59.8 68.9  Carex s i t c h e n s i s  21 42  42.2 46.6  48.4 53.4  46.9 48.6  54.5 56.0  Carex l y n g b y e i  21 42  65.7 71.9  66.0 71.2  70.6 72.0  72.2 73.3  D a c t y l i s glomerata  21 42  65.9 68.8  67.5 67.3  64.9 70.1  68.0 70.1  Control  21 42  29.2 37.4  26.5 32.6  26.9 26.9  27.8 32.2  (sterile)  * V a l u e s a r e averages o f two samples.  Appendix V I I I  A n a l y s i s o f V a r i a n c e o f % O r g a n i c M a t t e r L o s s I n V i t r o ; Young Shoots,  Source o f V a r i a t i o n  DF  Sum SQ  Mean SQ  F-Value  Significance  32.0 47.7 269.4 4475.0  8.9 13.3 75.0 1245.0  ** ** ** **  9.9 8.5 8.1 0.1 10.6 0.9  **  Inoculum Source Additive Time Species  1 1 1 4  32.0 47.7 269.4 17900.0  Inoculum x A d d i t i v e Inoculum x Time Inoculum x S p e c i e s A d d i t i v e x Time A d d i t i v e x Species Time x S p e c i e s  1 1 4 1 4 4  35.6 30.7 116.4 0.3 152.9 13.6  Inoculum x Add. x Time Inoculum x Add. x S p e c i e s Inoculum x Time x S p e c i e s Add. x Time x S p e c i e s  1 4 4 4  21.6 22.8 33.5 24.3  21.6 5.7 8.4 6.1  6.0 1.6 2.3 1.7  NS NS NS NS  Inoculum x Add. x Time x Species  4  44.2  11.1  3.1  NS  Error  40  143.7  3.6  —  —  Total  79  18889.0  ** S i g n i f i c a n t a t 1% o f p r o b a b i l i t y NS Not s i g n i f i c a n t  35.6 30.7 29.1 • 0.3 38.2 3.4  •k*  **  NS  **  NS  

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