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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 .Sc . ( 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 i n THE FACULTY OF GRADUATE STUDIES (Department o f P l an t Sc ience) We accept t h i s t h e s i s as conforming to the r equ i r ed standard THE UNIVERSITY OF BRITISH COLUMBIA June, 1979 fc) Bob Humphrey Ogwang In presenting this thesis in partial fulfilment of the requirements for an advanced degree at the University of British Columbia, I agree that the Library shall make it freely available for reference and study. I further agree that permission for extensive copying of this thesis for scholarly purposes may be granted by the Head of my Department or by his representatives. It is understood that copying or publication of this thesis for financial gain shall not be allowed without my written permission. Department of The University of British Columbia 2075 Wesbrook P l a c e Vancouver, Canada V6T 1W5 i i ABSTRACT The landscapes o f B r i t i s h Columbia, prominent ly mod i f i ed by g l a c i a t i o n , present many la rge and va r i e d wet lands . These wet lands have not been we l l de l i nea ted nor c l a s s i f i e d a l though they are be ing r a p i d l y mod i f i ed 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 deve lop-ments. Some f ede ra l and p r o v i n c i a l agencies are c u r r e n t l y undertak ing i nven to ry 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 . 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 purposes, t h i s s tudy was undertaken i n which predominant ly p lant-med ia ted processes 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 mar i t ime marshes o f south western B r i t i s h Columbia w i th study s i t e s l o ca t ed i n the P i t t , Brunswick and Iona marshes. Est imates o f p r o d u c t i v i t y were obta ined from s i n g l e and sequent ia l ha rves t i ng o f the a e r i a l v ege t a t i on . Peak s tand ing crops va r i ed between spec ies and between s i t e s . Spec ies d i f f e r en ce s were a t t r i b u t e d to p l an t c h a r a c t e r i s t i c s such as pho tosyn the t i c canopy development and shoot con-f i g u r a t i o n . Peak s tand ing crops were a l so r e l a t ed to environmental v a r i a b l e s such as c l ima t e , water regime, s a l i n i t y and subs t ra te n u t r i e n t s t a t u s . Data from sequent i a l ha rves t i ng revea led tha t most emergents exper ienced a r ap i d growth i n the sp r i ng and e a r l y summer d e c l i n i n g w i th the onset o f co ld weather i n the f a l l . Time o f peak product ion d i f f e r e d markedly between spec ies depending on presence o r absence o f over -w in tered pho tosyn the t i c shoots , t ime o f shoot emergence and seasonal i i i shoot m o r t a l i t y r a t e s . S tud ies o f belowground organs showed tha t roots and rhizomes may comprise up to 85 percent o f the t o t a l phytomass o f emergent vege ta t i on emphasizing the importance o f t h i s f r a c t i o n i n wet land func t i ons and p rocesses . The main routes o f d i s p o s i t i o n o f the emergents were i d e n t i f i e d as the g raz ing rou te , accumulat ion route and the d e t r i t a l r ou te . Graz ing was r e l a t i v e l y unimportant i n the marshes. Any g raz ing o f the l i v i n g vegeta t i on was c a r r i e d out l a r g e l y by gast ropods, e a r t h -worms, i n s e c t s and r e s i den t and migrant wa te r f ow l . Minimal g raz ing o f the marsh vegeta t i on appeared to be r e l a t e d to unfavourable wet land c o n d i t i o n s , h igh l e v e l s of s t r u c t u r a l c ons t i t uen t s and low l e v e l s o f n i t r ogen i n the p l a n t s . Qua l i t y o f the vege ta t i on dec l i ned sha rp l y w i th age. Low ash l e v e l s and high pheno l i c content were a l s o imp l i c a t ed i n the minimal g raz ing of the P i t t marsh vege ta t i on . To ta l energy content appeared to be unimportant i n t h i s regard . Organic mat ter accumulat ion was a d i s t i n c t f ea tu re o f the marshes s t ud i e d . There was more o rgan i c matter accumulat ion i n the P i t t than in the Brunswick marsh. Accumulat ion a l s o seemed to be more uni form over l a rge 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 tha t a l a rge po r t i on o f the phytomass produced i n the marshes en te rs the d e t r i t a l pathway v i a decompos i t ion. Factors a f f e c t i n g decomposit ion ra tes were d i scerned 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 decomposit ion s t u d i e s . Fragmentat ion o f l i t t e r by phys i c a l f o r ces gene r a l l y preceded b i o l o g i c a l i v degradat ion . Such comminution was more marked i n the F rase r d e l t a marshes where t i d a l and f r e she t a c t i v i t i e s are predominant. Temperature 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 disappearance r a t e s . The ra tes were gene r a l l y lower i n the " coo l e r " P i t t marsh than i n the "warmer" Brunswick marsh. Low s o i l temperatures together w i th low oxygen tens ions were r e spons i b l e f o r the r e l a t i v e l y low decomposit ion ra tes i n bu r i ed l i t t e r samples. Decomposit ion ra tes 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 vege ta t i on . Less f i b r ous spec ies such as Carex  lyngbye i were more r e a d i l y degraded than more f i b r ous spec ies such as Carex s i t c h e n s i s . Leaching of r e a d i l y degradable p l an t ma t e r i a l s occurred i n s i g n i f i c a n t q u a n t i t i e s both i n l i v i n g and dead vege ta t i on . Leaching l osses i n l i v i n g shoots averaged 64 mg/g l e a f dry matter i n 4 days. 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 imp l i c a t ed i n the po s s i b l e mechanisms c o n t r o l l i n g l each ing l osses i n l i v i n g emergent vege t a t i on . In dead shoots , dry weight l o s ses o f up to 50 percent were recorded over a f ou r month p e r i o d . Such l osses were a t t r i b u t e d main ly to l e a ch i ng . High i n i t i a l l o sses i n the l i t t e r bag and i n v i t r o decomposit ion t r i a l s were a l s o suggest ive o f l e a ch i ng . V TABLE OF CONTENTS Page 1. INTRODUCTION 1 2. REVIEW OF RELEVANT LITERATURE 5 2.1 D e f i n i t i o n s 5 2.2 Wetland C l a s s i f i c a t i o n 6 2.3 Adaptat ion o f Emergent Spec ies to the Wetland Environment 7 2.4 D i s t r i b u t i o n o f Wetland F l o ra 9 2.5 P r o d u c t i v i t y o f Emergent Vegetat ion 10 2.6 The Animal Fac tor in Wetlands 12 2.7 The D i s p o s i t i o n o f Wetland Vegetat ion 14 2.7.1 The g raz ing pathway 14 2.7.2 D e t r i t a l pathway 18 2.7.3 Accumulat ion pathway 20 3. GENERAL DESCRIPTION OF THE STUDY AREAS, SUBSTRATES AND SPECIES 22 3.1 T i da l Marshes o f the F raser Foreshore 22 3.2 Fresh Water Marshes - P i t t Meadows . . 28 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 Subst ra tes 34 3.4.1 Ma t e r i a l s and methods 34 3.4.2 Observat ions and r e s u l t s 35 3.4.3 D i s cuss i on 35 3.5 De s c r i p t i o n o f the I nd i v i dua l P l an t Species 37 3.5.1 Some taxonomic fea tu res o f the p r i n c i p a l spec ies s tud i ed 38 3.5.2 Some p l an 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 spec ies s t ud i ed 39 v i Page 3.5.3 Some gross morpho log ica l f ea tu res of the s tand ing shoots 40 3.5.3.1 Ma t e r i a l s and methods 40 3 .5 .3 .2 Observat ions and r e s u l t s 41 3 .5 .3 .3 D i s cuss i on 43 4. PRODUCTIVITY OF EMERGENT VEGETATION 44 4.1 Peak Standing Crop Y i e l d s 44 4.1.1 Ma t e r i a l s and methods 44 4 .1 .2 Resu l t s . 46 4 .1 .3 D i scuss ion 48 4.2 Seasonal Changes i n Dry Matter Product ion 51 4.2.1 Ma t e r i a l s and methods 52 4.2.2 Observat ions and r e s u l t s 52 4 .2 .3 D i scuss ion 56 4.3 Year to Year V a r i a t i o n i n Spr ing Standing Crops . . . 59 4.3.1 Ma t e r i a l s and methods 60 4 .3 .2 Resu l t s 60 4 .3 .3 D i s cuss i on 60 4.4 Quan t i t a t i v e Est imates o f Dead Phytomass 62 4.4.1 Ma t e r i a l s and methods 63 4.4.2 Observat ions and r e s u l t s 63 4 .4 .3 D i s cuss i on 66 4.5 Belowground Phytomass 68 4.5.1 Ma t e r i a l s and methods 68 4.5.2 Observat ions and r e s u l t s 69 4 .5 .3 D i s cuss i on 7^ v i i 4.6 C a l o r i c Content o f Some Emergent Species 75 4.6.1 Ma t e r i a l s and methods 75 4 .6 .2 Observat ions and r e s u l t s 76 4 .6 .3 D i scuss ion 76 5. DISPOSITION OF EMERGENT VEGETATION 78 5.1 Graz ing o f Emergent Wetland Vegeta t ion 79 5.2 Accumulat ion o f Emergent Vegetat ion in the Subs t ra te 80 5.3 Decomposit ion o f Emergent Vegetat ion 85 5.3.1 Decomposit ion s tud i e s us ing l i t t e r bags . . . . 85 5.3.1.1 Ma t e r i a l s and methods 86 5 .3 .1 .2 Observat ions and r e s u l t s 87 5 .3 .1 .3 D i scuss ion 91 5.3.2 In v i t r o decomposit ion of Emergent Vegeta t ion 95 5.3.2.1 Ma te r i a l s and methods 96 5 .3 .2 .2 Observat ions and r e s u l t s 97 5 .3 .2 .3 D i scuss ion 1 0 2 6. PLANT FACTORS LIMITING DEGRADATION OF EMERGENT VEGETATION 1 0 4 6.1 Neutra l and Ac i d Detergent F ib re 1 0 6 6.1.1 Ma t e r i a l s and methods 1 0 6 6.1.2 Resu l ts 106 6 .1 .3 D i scuss ion . 113 v i i i Page 6.2 L i g n i n 113 6.2.1 Ma t e r i a l s and methods 114 6.2.2 Observat ions and r e s u l t s 115 6 .2 .3 D i scuss ion 116 6.3 C u t i c l e 124 6.3.1 Ma t e r i a l s and methods 126 6.3 .2 Observat ions and r e s u l t s 126 6 .3 .3 D i s cuss i on 129 6.4 S i l i c a 152 6.4.1 Ma t e r i a l s and methods 152 6.4 .2 Observat ions and r e s u l t s 152 6 .4 .3 D i scuss ion 154 6.5 Pheno l i c Compounds 154 6.5.1 Ma t e r i a l s and methods 155 6.5.2 Observat ions and r e s u l t s 156 6 .5 .3 D i s cuss i on 156 7. NUTRIENTS IN EMERGENT VEGETATION 158 7.1 Nu t r i en t Concentrat ions i n the Standing Crops . . . . 159 7.1.1 Tota l ash 159 7.1.1.1 Ma t e r i a l s and methods 160 7 .1 .1 .2 Observat ions and r e s u l t s 160 7 .1 .1 .3 D i scuss ion 160 7.1.2 N i t rogen and s u l f u r 163 7.1.2.1 Ma t e r i a l s and methods 164 7 .1 .2 .2 Observat ions and r e s u l t s 164 7 .1 .2 .3 D i s cuss i on 168 Page 7.1.3 Response o f some emergents to f e r t i l i z e r n i t rogen 168 7.1.3.1 Ma t e r i a l s and methods 169 7 .1 .3 .2 Observat ions and r e s u l t s 171 7 .1 .3 .3 D i scuss ion 182 7.2 Leaching from Shoots o f Emergent Vegetat ion 184 7.2.1 Ma t e r i a l s and methods 185 7.2.2 Observat ions and r e s u l t s 186 7.2.3 D i scuss ion 188 8. GENERAL DISCUSSION AND RECOMMENDATIONS . . 196 8.1 P r o d u c t i v i t y of Emergent Vegetat ion 197 8.2 D i s p o s i t i o n o f Emergent Vegetat ion 202 8.3 Proximate Chemical Components o f Emergent Vegetat ion as a Fac to r i n the Wetland System . . . . 207 BIBLIOGRAPHY 214 APPENDIX 230 I . % o rgan i c mat ter decomposed i n l i t t e r bags, where bags were p laced on the subs t r a t e su r face 230 I I . Ana l y s i s o f var iance o f % o rgan i c mat ter decomposed i n l i t t e r bags, where bags were p laced on the subs t ra te su r face 231 I I I . % organ i c mat ter decomposed i n l i t t e r bags, where bags were p laced 15 cm below the sur face 232 IV. Ana l y s i s o f var iance o f % organ i c mat ter decomposed i n l i t t e r bags, where bags were p laced 15 cm below the sur face 233 V. In v i t r o decomposit ion of overwintered shoots from wet land and con t ro l s p e c i e s ; expressed as % o rgan i c mat ter l o s s 234 X Page V I . Ana l y s i s o f var iance o f % organ i c mat ter l o s s i n v i t r o ; overwintered shoots 235 V I I . In v i t r o decomposit ion o f young shoots from wet land and con t ro l s pe c i e s ; expressed as % organ i c matter l oss 236 V I I I . Ana l y s i s o f var iance o f % o rgan i c matter l o s s i n v i t r o , young shoots 237 x i LIST OF TABLES Table Page 3.1 E l e c t r i c a l C o n d u c t i v i t y , pH, % Organic Ma 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 3.2 Some Gross Morpho log ica l Features of Standing Shoots of Se l e c ted Species from P i t t and Brunswick marshes, October 1977 42 4.1 Est imates 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 in a rab l e lands a t A laksen and Colony Farm 47 4.2 Est imates o f Peak Standing Crop Y i e l d s (Dry Mat ter i n grams as averaged from two meter square quadrats) f o r s i x spec ies of the P i t t marsh, October 1977 47 2 4.3 Seasonal Changes i n the Standing Crops (g/m Dry Mat ter ) o f f i v e spec ies from the F rase r d e l t a marshes and Arab le l ands , Summer 1976 53 4.4 Seasonal Changes i n Standing Crops (g/m Dry Mat ter ) of f ou r spec ies from the P i t t marsh, 1977 53 4.5 Spr ing Standing Crop Est imates of e i gh t spec ies from from three l o c a t i o n s (g/m^ Dry Mat ter as averaged from two meter square quadrats) 61 2 4.6 Dry Matter Y i e l d s (g/m ) of New Growth and Old Growth of s e l e c t ed spec ies from the Fraser d e l t a marshes and nearby Arab le Lands, Summer 1976 64 2 4.7 Dry Matter Y i e l d s (g/m ) o f New Growth and Old Growth of f i v e spec ies from the P i t t marsh, 1977 65 2 4.8 Dry Mat ter Y i e l d s (g/m ) of Old Growth f o r some s pe c i e s , Winter of 1977/78 65 4.9 Belowground Phytomass (dry wt. ba s i s ) of s e l e c t ed spec ies from Brunswick marsh and P i t t o l d f i e l d , November 1977 70 4.10 Ra t i o of Belowground to Aboveground Phytomass of s e l e c t ed spec ies from Brunswick marsh, P i t t marsh and P i t t o l d f i e l d , November 1977 72 x i i Table Page 4.11 Percent of Read i l y Hydro lyzab le carbohydrates (dry wt. bas i s ) i n Belowground Phytomass o f s e l e c t ed spec ies from Brunswick marsh, P i t t marsh and P i t t o l d f i e l d , November 1977 73 4.12 Seasonal Changes i n Energy Content (Kca l /g) of the Standing Crop of some Emergents from severa l l o c a t i o n s , 1977 77 5.1 Summary of the Main E f f e c t s o f L i t t e r Bag Decomposit ion where Bags were p laced on the Subs t ra te Sur face 88 5.2 Summary of the Main E f f e c t s of L i t t e r Bag S t ud i e s , where Bags were p laced 15 cm Below the Sur face 92 5.3 Summary o f the Main E f f e c t s o f In V i t r o S tud i e s , Overwintered Shoots 9 8 5.4 Summary of 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 99 6.1 Seasonal Changes i n Neutra l Detergent F i b re (as % Dry M a t t e r ) , Summer 1976 107 6.2 Seasonal Changes i n Neutra l Detergent F i b re (as % Dry M a t t e r ) , Winter 1977-1978 110 6.3 Seasonal Changes i n A c i d Detergent F i b r e (as % Dry M a t t e r ) , Summer 1976 H I 6.4 Seasonal Changes i n A c i d Detergent F i b r e (as % Dry M a t t e r ) , 1977, 1978 1 1 2 6.5 Seasonal Changes i n L i g n i n (as % Dry M a t t e r ) , 1976 . . . . 117 6.6 Seasonal Changes i n L i g n i n (as % Dry M a t t e r ) , 1977 - 1978 U S 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 o f L i g n i f i e d Leaf T i ssues i n Transverse se c t i ons H 9 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 of L i g n i f i e d Stem T issues i n Transverse sec t i ons '20 6.9 Anatomical Component Measurement on Leaves i n Transverse sec t i ons 12' Anatomical Component Measurements on Stems i n Transverse sec t i ons Seasonal Changes i n Cu t i n (as % Dry M a t t e r ) , Summer 1976 Seasonal Changes i n Cu t in (as % Dry M a t t e r ) , 1977 - 1978 S i l i c a (as % Dry Weight) i n the Standing Crops of some spec ies samples on 19 October 1977 . . . Average Concent ra t ion o f Tota l Phenols i n the Leaves Harvested on 10 May 1978 Seasonal Changes in Tota l Ash (as % Dry Wt.) o f Se l e c ted spec ies from severa l s i t e s , 1976 . . . . 2 Seasonal Changes i n Tota l Ash (as % and as g/m Dry Matter i n the s tand ing crop) o f s e l e c t ed spec ies from severa l s i t e s , 1977 - 1978 Seasonal Changes i n N i t rogen (as % Dry. Wt.) o f s e l e c t ed spec ies from severa l s i t e s , 1976 . . . . Seasonal Changes i n N i t rogen (as % Dry Wt. and g/m 2 i n Dry Mat ter of s tand ing crop) of s e l e c t ed spec ies from severa l s i t e s , 1977 Seasonal Changes in S u l f u r (par ts per m i l l i o n , Dry Wt.) of s e l e c t ed p l an t spec ies from severa l s i t e s , 1977 E f f e c t o f two sources of N i t rogen F e r t i l i z e r on Dry Matter Product ion (g/m 2) E f f e c t of Ma tu r i t y Stage on Dry Matter Product ion (g/m 2) E f f e c t o f N i t rogen A p p l i c a t i o n on the N Content o f the Shoots a t severa l stages o f growth . . . . Apparent Recovery of two Nitrogenous F e r t i l i z e r s a t 12 weeks o f Regrowth ., x i v Table Page 7.10 Summary of the Ana l y s i s of Var iance o f the Carry Over E f f e c t of N i t rogen App l i ed in 1976 on 1977 standing, crops 181 7.11 Tota l Leachate (mg/g Leaf Dry Weight) from se l e c t ed spec ies 187 7.12 Est imates of Stomatal Number observed under 50 x Magn i f i c a t i o n f o r severa l Wetland spec ies 193 XV LIST OF FIGURES F igure Page 3.1 Map showing Loca t i on o f the Study Areas 3.2 Photographs showing Emergent Communities i n the Brunswick marsh (Summer 1977) 3.3 Photographs showing Emergent Species i n the P i t t marsh, (Spr ing 1978) 3.4 Photographs showing Lo l ium perenne - Agropyron  repens stand at A laksen dyked a rab le o l d f i e l d . 4.1 Photographs showing V a r i a t i o n s i n Communities w i th Va r i a b l e Water Depth . . 4.2 Photographs showing con t r a s t s i n Timing o f Shoot Death, Iona marsh 4.3 Photographs showing Older Overwintered F lower ing Shoots and New Shoots of Carex s i t c h e n s i s i n P i t t marsh (Spr ing 1976) 5.1 Accumulat ion o f Organic Mat ter i n the P i t t marsh (Summer 1976) 5.2 Accumulat ion of Organic Mat ter i n the Brunswick marsh 5.3 Decomposit ion i n L i t t e r Bags P laced on the Subs t ra te Sur face 5.4 In V i t r o Decomposit ion of Overwintered and Young SFoo t i . . '. 100-101 6.1 Seasonal Changes i n NDF 108-109 6.2 Scanning E l e c t r on Photomicrographs of Adax ia l Leaf Sur faces of Carex s i t c h e n s i s ( P i t t ) 130-132 6.3 Scanning E l e c t r on Photomicrographs o f Shoot Sur faces of Sc i rpus acutus ( P i t t ) 133-135 6.4 Scanning E l e c t r on Photomicrographs of Adax ia l Leaf Sur faces o f Equisetum f l u v i a t i l e ( P i t t ) 136-138 23-24 26-27 29-30 32-33 49-50 54-55 57-58 81-82 83-84 xv i F igure Page 6.5 Scanning E l e c t r on Photomicrographs of Adax ia l Leaf Sur faces o f Carex lyngbye i (Brunswick) 139-141 6.6 Scanning E l e c t r on Photomicrographs o f Adax ia l Leaf Surfaces of Festuca arundinacea (Brunswick) 142-144 6.7 Scanning E l e c t r on Photomicrographs o f Adax ia l Leaf Sur faces of Typha l a t i f o l i a (Brunswick) 145-147 6.8 Scanning E l e c t r on Photomicrographs o f Adax ia l Leaf Sur faces of Dacty l i s glomerata (A laksen) 148-150 7.1 E f f e c t s o f Ma tu r i t y and F e r t i l i z e r N i t rogen on Dry Matter Product ion o f 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 o l d f i e l d . . .174-175 7.2 E f f e c t s o f Ma tu r i t y and F e r t i l i z e r N i t rogen on Dry Matter P roduct ion of Carex lyngbye i i n Iona marsh 176-177 7.3 Ra t i o of Inorgan ic to Organic Mat ter Leached from the Shoots o f 3 Emergents and 2 Arab le o l d f i e l d Spec ies 189-190 7.4 Percent o f Standing Crop Ash Recovered i n the Leachate 191-192 xv i i A C K N O W L E D G E M E N T S I wish to acknowledge the guidance and c on s t r u c t i v e c r i t i c i s m s g iven to me by my supe r v i s o r P ro fesso r V. C. Br ink throughout the research p r o j e c t . Suggest ions 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 an t Sc ience Department) and Dr. A. J . Renney ( P l an 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 app re c i a t ed . Many thanks to Dr. G. W. Eaton f o r h i s advice on s t a t i s t i c a l ana l y ses . Techn ica l a s s i s t ance by I . D e r i c s , A. He ra r th , A. Hoda ( P l a n t S c i e n c e ) , B. vonSp ind le r ( S o i l Sc ience) and G. Galzy (Animal Sc ience) i s g r a t e f u l l y acknowledged. Spec i a l thanks to 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 ance w i th the e l e c t r on microscope. My s i n ce r e thanks a l s o go to Miss J ud i t h Johnson f o r her a s s i s t ance dur ing the p repara t i on o f the manuscr ip t . F i n a l l y I wish to g r a t e f u l l y acknowledge the f i n a n c i a l a i d prov ided by the Canadian I n t e rna t i ona l Development Agency f o r my s tud ies in Canada. 1 1. INTRODUCTION The terms "marshes", "swamps", "bogs" , have been used f o r c en tu r i e s but on ly r e c en t l y have there been any attempts to group them under a s i n g l e term: wet land . The need to do t h i s has grown out o f a de s i r e to understand and desc r i be the c h a r a c t e r i s t i c s and va lues o f a l l types o f l a nd , as we l l as to w i s e l y and e f f e c t i v e l y manage wet land ecosystems. However, a s i n g l e , i n d i s pu t ab 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 f o r wet land would not s a t i s f y a l l i n t e r e s t e d d i s c i p l i n e s . Moreover, there i s a g rada t i on between dry and wet environments and boundaries imposed can on ly be a r b i t r a r y . Consequent ly , on ly a gene ra l i z ed d e f i n i t i o n w i l l be g iven here to serve as a frame o f re ference f o r the s tud i e s repor ted i n t h i s t h e s i s . Wetland may be regarded as land where the water t ab l e i s a t , near or above the land sur face long enough each yea r to promote the format ion of hyd r i c s o i l s and to support the growth o f hydrophytes. I f "permanent" o r yea r long open water i s cons idered aquat i c h a b i t a t , then the upper l i m i t o f wet land i s determined by: (1) the change from predominant ly hydrophytes to predominant ly mesophytes or xerophytes; (2) the change from predominant ly hyd r i c to non-hydr i c s o i l s ; (3) the change from land tha t i s f l ooded at some time to land which i s never f l ooded dur ing years of normal p r e c i p i t a t i o n . Wet lands, by t h i s d e f i n i t i o n , range from sub-aquat i c to x e r i c environments, from coas ta l s a l t marshes to i n t e r i o r s loughs and to bogs. They occur on azonal f r e s h l y depos i ted sediments and on o l d ombrogenous pea ts ; 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 to a r c t i c l a t i t u d e s , 2 and from lowland to a l p i n e zones. Wetland p l an t communities are commonly a s soc i a t ed w i th r e l a t i v e l y stagnant water bodies ( e . g . lakes and swamps), as we l l as streams and sho re l i n e s where water movements are s u b s t a n t i a l . There are many biogeochemical f a c t o r s at tendant on areas o f wet land vege t a t i on , but i t i s important to observe tha t catchment bas ins w i th s tand ing water are gene r a l l y f i l l i n g , i n vary ing degree, w i th o rgan i c and i no rgan i c sediments and s o l u b l e s . The sma l l e r bas ins o f ten r e ce i ve ma te r i a l o f l o c a l o r i g i n . The sediments and so l ub l e s o f r i v e r i n e and coas ta l waters may, on the o the r hand, be imported f ron and/or exported to l a rge areas w i th w ide ly d i f f e r i n g parent m a t e r i a l s . The economic and e co l og i c importance o f wet lands i s r e f l e c t e d in t h e i r d i v e r s i f i e d f u n c t i o n s . 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 wo r l d , e . g . the Ganges, N i l e , Rhine and T i g r i s -Euphrates de l t a s i s common reco rd . B i o l o g i c a l l y , some wet land systems are known to be among the most p roduc t i ve ecosystems and they have been i n t e n s i v e l y e xp l o i t e d by man. Some o f the wo r l d ' s g rea tes t centres o f human popu l a t i o n , i n du s t r y , and a g r i c u l t u r e are found on mod i f i ed wet lands . Wetland vege ta t i on i s a l s o used by man f o r f u e l , food and pu lp . Desp i te t h e i r importance, i t i s perhaps a s t on i sh i ng t h a t , as a sub jec t o f s c i e n t i f i c i n q u i r y , wet land systems have been accorded s i g n i f i c a n t a t t e n t i o n on l y r e c e n t l y . H i s t o r y shows tha 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 en tu r i e s and s t i l l cont inues at a . r ap i d pace. Dra inage, canal c o n s t r u c t i o n , dyk i ng , i r r i g a t i o n , waste d i s p o s a l , o i l 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 are 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 wet lands i n var ious par t s o f the wo r l d . So r ap i d are the e x p l o i t a t i o n s , mod i f i c a t i o n s and a l i e n a t i o n s o f wet lands t ha t i f t h e i r na tu ra l f unc t i ons are to be s tud i ed at a l l , they must be s tud i ed now. There are ex tens i ve areas o f wet land i n B r i t i s h Columbia which have not y e t been adequately mapped o r desc r i bed . Large areas o f wet meadow occur on the comparat ive ly uni form sur faces o f the i n t e r i o r p l a teaux , along the margins o f r i v e r s and l a k e s , and at the head o f v i r t u a l l y a l l i n l e t s along the f i o r d coas t . Much o f the wet land 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 dra inage pa t te rns e f f e c t e d by recent and complete g l a c i a t i o n s o f the P rov ince . In B r i t i s h Columbia t oo , desp i t e the comparat ive ly recent occupancy of the land by whi te man, e x p l o i t a t i o n i s proceeding r a p i d l y w i th comparat ive ly l i t t l e knowledge o f wet land d i s t r i b u t i o n , e c o l o g i c a l processes and f u n c t i o n s . I t i s to be expected tha t an invento ry and c l a s s i f i c a t i o n of wet lands should r e ce i ve f i r s t a t t e n t i o n . So va r i ed however are the wet lands 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 , nature and use, tha t i nvento ry i s proceeding s l ow ly and h a l t i n g l y . A s s i s t ance would be accorded the invento ry i f there was a be t t e r under-stand ing of the f unc t i ons o f , and the processes at work i n , the wet land systems. The work repor ted here was undertaken to a i d i n , or perhaps i t might even be s a i d to i n i t i a t e a b e t t e r understanding o f the r o l e p lan ts p lay i n these f unc t i ons and processes . Such e f f o r t s would be o f va lue not on ly f o r i nvento ry purposes, but a l s o f o r proper management, use and conserva t ion o f the wet lands . 4 There are severa l ways o f assess ing the r o l e p lan ts p l ay i n wet land systems. In B r i t i s h Columbia, the q u a n t i t i e s of p l an t ma te r i a l produced i n wet land systems are known on ly from s ca t t e r ed sources and are o f t en poor ly determined. The q u a l i t y o f the p l an t ma te r i a l has been on l y t h i n l y assessed . 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 wet land p l an t s - whether through g r a z i n g , o x i d a t i o n , accumulat ion or t r a n s po r t a t i o n to other systems. The bas i c approach o f the i n qu i r y t he re f o re centered on these d e f i c i e n t areas w i th 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 an t communities o f south western B r i t i s h Columbia. The techniques used were r a t he r crude and s imp le , l a r g e l y i n d i c a t i v e o f the comparat ive you th fu lness o f wet land s tud i e s which o f t en lack s o p h i s t i c a t i o n and are u s u a l l y , at bes t , s em i - quan t i t a t i v e . I t i s hoped tha t t h i s i n q u i r y w i l l c o n s t i t u t e pa r t o f a broader study o f B r i t i s h Co lumbia 's wet land systems. 5 2. REVIEW OF RELEVANT LITERATURE 2.1 D e f i n i t i o n s The term "wet land" can be used to desc r ibe a wide v a r i e t y o f h i g h l y c on t r a s t i n g landscapes. A common f ea tu re o f wet lands i s tha t they have a high water t ab l e f o r a s ub s t an t i a l pa r t o f the y ea r . The i r subs t ra tes are h i gh l y v a r i a b l e , ranging i n ma t e r i a l s tha t are almost 100 percent o rgan i c to almost 100 percent minera l matter and a l l the po s s i b l e combinat ions i n between. The water a s soc i a t ed w i th wet lands may be f r e sh or s a l i n e w i th i n f i n i t e combinat ions between the two extremes. I t i s t he re f o re not s u r p r i s i n g , as has been p r e v i ou s l y s t a t e d , t ha 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 wet land e x i s t i n the l i t e r a t u r e . The d e f i n i t i o n g iven i n the i n t r oduc t o r y statement and repor ted here was supported by Cowardin e t aj_. (1976). I t conven ien t l y combines both edaphic and vege ta t i ona l f ea tu res o f wet land . Some workers emphasize on ly one o r the o ther as a bas i s f o r t h e i r d e f i n i t i o n . For i n s t a n c e , wet lands are de f ined by S j o r s (1948) and the Na t i ona l S o i l Survey Committee o f Canada (1970) as areas where wet s o i l s are p r eva l en t , having a water t ab l e near or above minera l s o i l , as i n d i c a t e d by g l ey i ng i n the minera l s o i l h o r i z on . Mornsjo (1969) g ives a s i m i l a r d e f i n i t i o n but adds tha t wetlands have a vege ta t i on adapted to p e r i o d i c wa te r l ogg ing . He a l s o s t a t e s tha t the s o i l s o f wet lands are l a r g e l y peat and when minerogenic they may be g l e y i s h s o i l s o f var ious k i nd s . Terminology f o r wet land s o i l s o f North America has been desc r ibed by McK inz ie (1974). 6 Concomitant w i th the v a r i e t y o f d e f i n i t i o n s are the numerous shades o f meaning a t tached to terms such as swamp, bog, peat , meadow and marsh which are commonly used to desc r i be the wet lands . There i s no doubt t ha 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 rea l and important d i f f e r en ce s among h i gh l y complex e c o l o g i c a l s i t u a t i o n s . For a complete exp lana t i on o f the s p e c i f i c d i f f e r en ce s o r s i m i l a r i t i e s between wet land terms such as ombrogeneous, ombrotrophic , ombrophilous and so l igeneous wet lands and bog, moor, swamp and f e n , the reader i s r e f e r r e d to Hotchk iss and Stewart (1947) , Penfound (1952) , Heinselman (1963) and Z o l t a i e t al_. (1975). 2.2 Wetland C l a s s i f i c a t i o n Nat iona l and reg iona l systems o f c l a s s i f i c a t i o n have been developed f o r wet land i n many par t s o f the wor ld to serve a number o f o b j e c t i v e s . In g ene r a l , most systems group wet lands accord ing to ex t e rna l o r i n t e r n a l f e a t u r e s . The ex te rna l f ea tu res may be subd iv ided i n t o those s t r e s s i n g the b i o t i c or a b i o t i c e lements. The b i o t i c s ubd i v i s i on s emphasize fea tu res of p l an t physiogonomy, dominance o r f l o r i s t i c s (Penfound 1967, P o l l e t t and Br idgewater 1973, Wh i t taker 1962). The a b i o t i c cha rac te r -i s t i c s are emphasized i n a landform approach where the sur face form o f wet lands (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 d i f f e r e n t types . Most o f the i n t e r n a l p r ope 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 tu s (S jo 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 ind i s the bas i s f o r the r e c en t l y 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 Un i ted S t a t e s . Tak ing , 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 bas i c wet land c l asses i n Level 1 (marsh, swamp, f en , bog and sha l low open wa 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 bas i s of s o i l t ype , water regime, water chemis t ry , i n t e r n a l dra inage c h a r a c t e r i s t i c s , sur face morphology and dominant l i f e forms o f vege ta t i on s . Each c l a s s i s subd iv ided i n Level 2 accord ing to su r face morphology o f the wet land ( f o r bogs and f e n s ) , hydrotopographic f ea tu res ( f o r marshes and swamps) and ad j o i n i ng land ( f o r sha l low open wa te r s ) . Leve l s 3 and 4 s t r e s s vege ta t i on types and the s p e c i a l i z e d needs o f va r ious 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 dd i t i o n to the Z o l t a i e t a]_. system, there probably e x i s t many other systems l i k e tha t repor ted 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 Columbia, which are being used i n var ious par t s o f Canada. In most cases , such reg iona l systems are s e n s i t i v e to d i f f e r en ce s t ha t a na t i ona l system cannot r e f l e c t so t ha t they serve a be t t e r purpose f o r i n t e n s i v e research and management. Taxons f o r B r i t i s h Columbia wet lands , i t may be observed, are not we l l e s t ab l i s h ed and tend to be h i g h l y d e s c r i p t i v e on ly weakly r e f l e c t i n g fundamental processes a s soc i a t ed w i th t h e i r occur rence . 2.3 Adapta t ion o f Emergent Species to the Wetland Environment Wetland subs t ra tes may be s imply and conven ien t l y de f ined as subs t ra tes t ha t are more or l e s s permanently sa tu ra ted 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 of wet land s o i l s i n North Amer ica . 8 The outs tand ing f ea tu res o f these s o i l s are the accumulat ion o f p l an t res idues i n the sur face h o r i z on , the presence o f a permanently reduced hor i zon below i t , p r e v a i l i n g anaerob ic cond i t i ons and g ene r a l l y low pH. These f ea tu res o f t en present s t r e s s cond i t i ons to the p l an t s growing, i n wet land s ub s t r a t e s . Through e v o l u t i o n , wet land p lan ts have developed severa l adapt ive mechanisms tha t enable them to "ward o f f " t o x i c r educ t i on p roduc ts , to accumulate nu t r i e n t s f o r use dur ing unfavourable c o n d i t i o n s , to grow i n an oxygen d e f i c i e n t medium and to s u r v i v e low pH c o n d i t i o n s . The anatomical and morpho log ica l adaptat ions found i n p lan ts a s soc i a t ed w i th water logged and anaerob ic environments are we l l known and were summarized by A rbe r (1920). In p a r t i c u l a r the development o f lacunae and l a rge i n t e r c e l l u l a r spaces i s f requent i n such p l a n t s . Arber (1920) demonstrated tha t such morpho log ica l f ea tu res are e s p e c i a l l y developed i n p l an t s o f s tagnant water whereas they may not be present a t a l l i n s i t u a t i o n s where water f low i s f a s t and oxygen supply i s adequate. S i f t o n (1945) and Scholander e t aJL (1955) concluded tha t the roots and rhizomes o f marsh p l an t s r e ce i ve t h e i r oxygen from a e r i a l pa r t s through gas spaces connect ing these organs. Cou l t and Va l l ance (1958) observed tha t most wet land p lan ts do r e l y upon a i r spaces f o r oxygen supply but tha t under anaerobic cond i t i ons some are able to reduce t h e i r oxygen demand. I t would appear tha t reduc ing cond i t i ons may cause an accumulat ion o f t o x i c compounds around the roots and rhizomes o f wet land p lan ts hence caus ing i n j u r y to these organs. Ruther (1955) suggested tha t a f l u c t u a t i n g water t ab l e may serve to remove such t o x i n s . B a r l e t t (1961) 9 repor ted tha t some r e s i s t an ce to wate r logg ing i s l i n k e d w i t h the capac i t y o f the roots of wet land p l an t s to o x i d i z e the rh i zo sphe re , presumably by oxygen t r a n s l o c a t i o n from the shoot . I n ev i t a b l y some o f the oxygen con-ta i ned w i t h i n the subae r i a l par t s o f such p l an t s must leak i n t o the surround ing medium and i t i s po s s i b l e t ha t t h i s l o c a l r a i s i n g o f oxygen p o t en t i a l cou ld be o f value in reduc ing t o x i c i t y . The roots and rhizomes o f semi-submerged p l an t s apparent ly can r e s p i r e anae r ob i c a l l y f o r long per iods o f time w i thou t i n j u r y (La ing 1940). McMannon and Crawford (1971) cons idered tha t morpho log ica l adaptat ions o f wet land p lan ts were not i n themselves adequate to account f o r t o l e rance to wa te r l ogg i ng . They showed t ha t lowered oxygen tens ions 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 metabol ism. They concluded tha t i n spec ies 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 ra ted and ethanol i s produced under anaerob ic c o n d i t i o n s . Flood t o l e r a n t spec ies however have a metabo l i c sw i tch which d i v e r t s g l y c o l y s i s from producing ethanol to ma la te . Other adaptat ions o f p l an ts to the wet land environment have been reviewed by Cannel l (1977). 2.4 D i s t r i b u t i o n o f Wetland F l o r a In marked con t r a s t to many better-known t e r r e s t r i a l p l a n t communit ies, wet land vegeta t i on t y p i c a l l y l a cks f l o r i s t i c d i v e r s i t y and i s o f ten dominated by a few g rasses , sedges o r rushes . The same genera and f r equen t l y the same spec ies may be encountered repeated ly i n w i de l y separated geograph ica l reg ions (Chapman 1960, J e f f r i e s 1977), some ranging from t r o p i c to a r c t i c l a t i t u d e s . Indeed some wet land spec ies are found wherever wet land occu r s . 10 Another s t r i k i n g f ea tu re i s t ha t monotypic communities o c c a s i o n a l l y dominate l a rge a reas . Many members o f the genus Carex o f t en form dense monotypic stands along the borders o f l a k e s , streams and bogs. F l o a t i n g sedge mats f r equen t l y invade smal l ponds and may f i n a l l y overspread them complete ly as "sedge meadows", some o f which l a t e r evo lve i n t o sphagnum bogs. Cons iderab le spec ies d i v e r s i t y may be encountered i n some wetlands such as b rack i sh marshes. The b i o t i c and phys i ca 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 ude p l an t compet i t i on (Weaver and Clements 1938), t i d e e l e v a t i o n (Adams 1963), water regime (Ha r r i s and Marsha l l 1963, M i l l a r 1969, Mornjo 1969, Jeglum 1971), water chemist ry (Scu l thorpe 1967), s a l i n i t y (Dodd and Coupland 1966, McNaughton 1966, Mooring e t aJL 1971, Shea 1972), and minera 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 of Emergent Vegeta t ion A l a rge body o f l i t e r a t u r e e x i s t s concern ing s a l t marsh, b r a ck i sh marsh and f reshwater marsh p r o d u c t i v i t y e s t ima te s . An exhaus t ive summary of the product ion l i t e r a t u r e would go f a r beyond the scope of t h i s study hence on ly a few r e l e van t f ea tu res are rev iewed. The pr imary produc t ion of t i d a l wet lands has been purported to be very high (Penfound 1956, Westlake 1963, Odum 1971) and K i rby and Gosse l i nk (1976) have r e c en t l y demonstrated tha t s a l i n e and b ra ck i sh wet land pr imary product ion may be even h igher than p r e v i ou s l y suspected. I t should be noted, however, tha t p roduct ion can be very low i n s a l i n e swamps and a few other wet land types (Muc 1971, Haag 1974). n Bernard (1973) noted tha t aboveground s tand ing crop o f Carex sp . (sedges) were lower i n general than those o f o ther wet land spec ies such as Typha (Boyd 1970 a, Boyd and Hess 1970), Phragmites ( P ea r s a l l and Gorham 1956) and G l y c e r i a (Westlake 1971). These spec ies commonly have aboveground stand ing crops over 1,000 g/m whereas most Carex wetlands do not reach tha t f i g u r e . A l though no attempt i s made to summarize a v a i l a b l e i n fo rmat i on on the pr imary product ion of we t l ands , a scan through the l i t e r a t u r e shows cons ide rab le v a r i a t i o n i n s tand ing crops between d i f f e r e n t systems even w i t h i n a g iven c l i m a t i c a rea . 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 to unique environmental f a c t o r s to which the wet land spec ies are sub jec ted . The gene r a l l y high p r o d u c t i v i t y of t i d a l marshes may be a t t r i b u t e d to severa l f a c t o r s . Odum (1961) s t r e s ses high n u t r i e n t s t a tus as a major f a c t o r ; t i d a l a c t i on o f ten supp ly ing l a r ge q u a n t i t i e s of n u t r i e n t s and oxygen wh i l e the marsh ac ts as a " t r a p " f o r these components. Reader (1978) a l s o showed tha t the a v a i l a b i l i t y of minera l n u t r i e n t s i n wet land subs t ra tes may, i n the main, be r e spons i b l e f o r v a r i a t i o n s i n s tand ing crops o f d i f f e r e n t s tands . The h ighe r pr imary p r o d u c t i v i t y a s soc i a t ed w i t h reed swamps ( e . g . Typha and Phragmites stands) compared to Carex wetlands has been a t t r i b u t e d to h igher s i l t a t i o n ra tes (Bernard 1973), the inc reased s i l t a t i o n presumably i n c r ea s i ng the n u t r i e n t i npu t . Water depth, du ra t i on and r e g u l a r i t y of inundat ion have a l s o been r e l a t e d to the supply of n u t r i e n t s (Gorham 1957, V a l i e l a e t al_. 1975). 12 Bernard (1973) compared the p r o d u c t i v i t y of Carex wet lands from var ious l a t i t u d e s and a l t i t u d e s and found tha t those a t h igh l a t i t u d e s and h igh e l e va t i o n s had s tand ing crops l e s s than 300 g/m wh i l e those at lower and more sou the r l y s i t e s produced over 1,000 g/m . Gorham (1974) cont inued ana l yz ing 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 tand ing crop w i th summer temperature, p a r t i c u l a r l y the h ighes 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 tand ing crop have been repor ted by Keefe (1972), Cooper (1974), Hatcher and Mann (1975). The nor th-south g rad i en t i n wet land product ion appears to be c l o s e l y c o r r e l a t e d w i th those f a c t o r s which measurements of l a t i t u d e i n t e g r a t e , e s p e c i a l l y temperature 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) cau t i on tha t the apparent d e c l i n e i n product ion at h igher 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 ten imp l i ed i n the l i t e r a t u r e . 2.6 The Animal Fac to r i n Wetlands Al though the work repor ted in t h i s t h e s i s emphasized p l an t processes , the animal f a c t o r cannot be ignored 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 un c t i o n i n wet land systems i n much the same way as they do i n o the r ecosystems. They f un c t i o n as grazers (Smal ley 1959, McLean and T i s d a l e 1960, Teal 1962). Cons iderab le q u a n t i t i e s o f wet land vege ta t i on may be grazed e s p e c i a l l y by i n s e c t herb ivores (Smal ley 1960). Many animals a l so f un c t i on i n p o l l i n a t i o n and d i s pe r s a l o f wet land p l a n t s . The i r r o l e i n comminution, subs t ra te turnover and d e t r i t a l format ions was emphasized by MacFadyen (1961). 13 An i n t r oduc t o r y statement on the extent and value o f the wet lands of B r i t i s h Columbia was g iven at a symposium held i n De l t a (Proceedings of B r i t i s h Columbia Wetland Seminar, 1975). Some o f the wetlands prov ide s h e l t e r and food f o r d i f f e r e n t ca tegor i es of r e s i d en t and migratory b i r d s (Barnard 1975, Burgess 1970). I t i s now b e l i e v e d , a l though not y e t documented, tha t i n i n d i r e c t ways, the B r i t i s h Columbia coas ta l emergent communities p lay a s i g n i f i c a n t r o l e i n the feed ing o f salmon wh i l e some o f them ac t as egg beds f o r o ther f i s h e s . The vege ta t i on i s a l so u t i l i z e d to va ry ing degrees by l a rge ungulates such as deer , moose, e l k , beaver and muskrat. The i n f l uence o f human a c t i v i t y on wet land systems cannot be over-emphasized. The sub jec 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 to r e ce i ve 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 . Consequent ly , on ly a few human a c t i v i t i e s w i l l be c i t e d here . C a n a l i z a t i o n , whether f o r gas or o i l e x p l o r a t i o n , i s f r equen t l y accompanied by f reshen ing s a l t water areas or b r i ng i ng s a l t i n t o f r e sh water a reas , thus changing the composi t ion o f the vege ta t i on t h e r e i n . Drainage can change wet land i n t o mod i f i ed hyd r i c communities where dra inage i s imper fec t o r to t e r r e s t r i a l communities or farmlands where dra inage i s more o r l e s s complete. In some wet lands , 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 nu t r i e n t s may promote l u x u r i a n t growth o f vege ta t i on a l though t o x i c f r a c t i o n s may i n o ther s i t u a t i o n s e l im i n a t e o ther spec ies ( V a l i e l a a n d Teal 1976). Wetlands i n B r i t i s h Columbia, a l though ex t en s i v e , have been a l i e na t ed f o r a mu l t i t ude o f purposes and w i th a s t on i sh i ng r a p i d i t y (Northcote 1974). S ince the days o f f i r s t dyke c on s t r u c t i o n i n the 14 1870's much o f the wet land has been occupied by suburb ia and i ndus t r y and now human a c t i v i t i e s of many k inds are extend ing a t an i n c r e a s i n g l y r ap i d r a t e . Becker (1971) and Hoos and Packman (1974) have gene r a l l y reviewed the a c t i v i t i e s i n s p e c i f i c contexts and i n d i c a t ed t h e i r cu r ren t pa t te rns of change. The nature o f the problem was a l s o e x t e n s i v e l y d i scussed at the B. C. Wetland Seminar (1975). Wetland p lan ts are o f t en harvested by man and conserved f o r forage a l though the forage i s o f ten o f low n u t r i t i o n a l q u a l i t y . Other d i r e c t uses o f wet land p l an t s by man, such as c r a f t , med ic ine , f ue l and pu l p , have been v a r i o u s l y reviewed i n Es tua r i ne Processes , V o l . 1 (1976). 2.7 The D i s p o s i t i o n o f Wetland Vegeta t ion I t i s w ide ly accepted tha t energy enters most ecosystems through the process o f photosynthes is which u l t i m a t e l y leads to a bu i l d -up o f p l an t m a t e r i a l . Th is ma te r i a l may be consumed by herb ivores or i t may d ie and pass through what i s termed the "decomposer" food cha i n . In most ecosystems the f a t e of ma te r i a l en te r i ng t h i s pathway i s to be broken down and r e sp i r ed by the r e s i d en t b i o t a u n t i l i t i s complete ly d i s s i p a t e d . However, many wet lands have a decomposer food cha in which i s impaired as a r e s u l t o f extreme phys i ca l c ond i t i on s such as wetness and anaerobosis l ead ing to accumulat ion o f undecomposed p l an t m a t e r i a l . 2.7.1 The g raz ing pathway Graz ing o f wet land vegeta t i on was b r i e f l y d i scussed under s e c t i on 2.6. The grazers o f l i v i n g vege ta t i on range from la rge na t i ve ungulates 15 such as deer o r domest ic l i v e s t o c k to smal l faunal communities such as a r thropods . A l though some wet lands are i n t e n s i v e l y g razed , i t appears t ha t i n many wet land systems, e s p e c i a l l y coas ta l marshes, g raz ing removes on ly a smal l f r a c t i o n o f t h e i r pr imary p roduc t i on . Smal ley (1959) found d i r e c t g raz ing i n a marsh system to be l e s s than 5 percent . Teal (1962) repor ted tha t the major energy f low between au to t roph i c and he te ro t r oph i c l e v e l s on a wet land was by way of the d e t r i t a l food cha in r a the r than the g raz ing food cha i n . In Georg ia e s t u a r i e s dominated by Spa 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 rgan i c matter to be the c h i e f l i n k between pr imary and secondary product ion because the grass was on ly m in ima l l y grazed wh i l e i t was l i v i n g . The reasons f o r the minimal g raz i ng o f some wet land emergent communities have s c a r c e l y been exp l o red . From s tud ies of o ther ecosystems, the main p l an t f a c t o r s a f f e c t i n g g raz ing use o f l i v i n g vege ta t i on are now more or l e s s we l l de f i ned . Martz ejt aj_. (1967) acknowledged tha t the chemical compos i t ion o f p l an t s a f f e c t s t h e i r p a l a t a b i l i t y . Heady (1964) reviewed severa l papers i n which the i n v e s t i g a t o r s concluded tha t t o t a l n u t r i t i v e va lue was the best i n d i c a t o r o f p a l a t a b i l i t y . The ma te r i a l s s e l e c t ed were u sua l l y h igher i n gross energy (Cook e_t al_. 1956), n i t rogen (Heady 1964), sugars and s o l ub l e carbohydrates (Reid e t al_. 1967) and lower in c e l l wa l l c ons t i t uen t s (Reid et_ al_. 1967) compared to the ma te r i a l r e j e c t e d . However, animal pre ferences cannot e a s i l y be a t t r i b u t e d to s imple p l an t c ons t i t uen t s such as these and the l i t e r a t u r e on t h i s sub jec t i s r a the r 16 con fus ing . For i n s t ance , Reid e t al_. (1967) noted s i g n i f i c a n t p o s i t i v e c o r r e l a t i o n s between preference r a t i n g and s o l ub l e carbohydrate content i n o r chardgrass . Re id 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 i n t a l l f escue . Bland and Dent (1964) compared the pre ferences of c a t t l e amongst 14 s t r a i n s o f orchardgrass at severa l l o c a t i o n s . At one s i t e , pre ferences were most c o r r e l a t e d w i th percent t o t a l sugars -a l though not w i th sucrose conten t . At a l l o ther l o c a t i o n s , t o t a l sugar content and pre ference were not r e l a t e d . A rno ld and H i l l (1972) s t a t ed tha t i t i s h i gh l y u n l i k e l y t ha t an animal cou ld g i ve an i n t eg r a t ed response to so l ub l e carbohydrates . What t h i s f r a c t i o n inc ludes depends not on ly on the p a r t i c u l a r carbohydrate present i n the p l an t under c ons i de ra t i on but a l so on the methods by which they are ex t r a c t ed 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 accumulat ing to i m p l i c a t e many p l an t secondary substances as a n t i b i o t i c agents i n e c o l o g i c a l i n t e r -a c t i ons between p l an t s and t h e i r a s soc i a t ed b i o t a . In terms o f p l a n t -herb ivore i n t e r a c t i o n s , secondary substances t ha t have been shown e i t h e r to have a negat ive e f f e c t on herb ivore f i t n e s s ( e . g . inc reased m o r t a l i t y , lower growth ra tes ) or to have de te r r en t e f f e c t on he rb ivo re g raz ing i nc lude a l k a l o i d s (Parmer and B r i nk 1976), e s t r ogen i c compounds ( B i e l y and K i t t s 1964), cyanogenic g l y co s i de s (Jones 1972), tann in and o ther pheno l i c compounds (Feeny 1970, Donne l ly and Anthony 1970). A l though i n o ther i n v e s t i g a t i o n s some o f these substances have been found to e x h i b i t no e f f e c t on herb ivore g raz ing pa t t e r n s , i t i s reasonable to assume tha t secondary substances must o f f e r some form of defense to the 17 p l a n t . I f they d i d not , then the metabo l i c costs a s soc i a t ed w i th t h e i r p roduct ion should cause the e l i m i n a t i o n o f genotypes producing these substances from the p l an t popu l a t i on . Morpho log ica l c h a r a c t e r i s t i c s of p l an ts seem to be a s soc i a t ed i n some cases w i th t h e i r a c c e p t a b i l i t y to he rb i vo re s . C ra igm i l e s e t a l . (1964) recorded 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 t ex tu re and p a l a t a b i l i t y i n t a l l f e s cue . Judas Hecart (1965) a l s o repor ted 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 ra s s . Abso lu te s i z e o f the t ransve rse s e c t i o n o f the vascu l a r bundles was s t r ong 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 ed accept-a b i l i t y . Accord ing to Heady (1964), pre ference f o r s p e c i f i c p l an t s may a l s o be r e l a t e d to the presence o f awns, sp i nes , h a i r i n e s s , s t i c k i n e s s and t e x t u r e . A v a i l a b i l i t y o f p l an t s to herb ivores can be a f f e c t ed by the environmental cond i t i ons o f the h a b i t a t . P l an t communities growing i n i n a c c e s s i b l e areas are not l i k e l y to be grazed to any cons ide rab le degree. The importance o f topograph ica l and phys i c a l f ea tu res o f the hab i t a t i n r e l a t i o n to a v a i l a b i l i t y of p l an t s to herb ivores was emphasized by Hercus (1961). The ex tent to which each o f the above p l an t f a c t o r s con t r i bu tes 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 wet land p l an t s by herb ivores has ha rd ly been exp lo red . Odum e t al_. (1972) concluded tha t the l a r ge 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 coas ta l emergent spec ies make them unpalab le to g r a ze r s . Har r i son and Mann (1975) observed tha t the high C : N r a t i o o f aqua t i c ee l g ra s s (Zostera s p . ) , g rea te r than 20 : 1, made i t a very poor d i r e c t food source (17 :1 being the maximum f o r an adequate d i e t , Russe l l - Hunter 1970). 18 2.7.2 D e t r i t a l pathway A l a rge p ropo r t i on o f the t o t a l matter produced i n wet land systems may pass through the d e t r i t a l pathway; the term d e t r i t u s being w ide l y accepted as meaning n o n - l i v i n g p l a n t o r animal remains and the assoc i a ted m i c r o f l o r a . D e t r i t a l processes i n vo l ve the breakdown o f dead p l an t ma te r i a l by var ious p h y s i c a l , chemical and b i o l o g i c a l fo rces i n t o p r o g r e s s i v e l y sma l l e r p i e c e s . Wave a c t i o n , t i d a l cu r ren ts and f r e e z i n g and thawing would c e r t a i n l y be important i n detach ing and fragment ing l a rge p ieces of wet land p l a n t s . Ha r r i son and Mann (1975) observed tha t m i c r ob i a l a c t i v i t y and l each ing ra tes were inc reased as mechanical a c t i o n reduced the s i z e o f ee lg rass (Zos te ra sp . ) l eaves . Small p a r t i c l e s u sua l l y have h igher su r face area f o r c o l o n i z a t i o n by microorganisms. Upon death o f the p l a n t , there are r ap 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 importance. Odum et a l . (1972) have summarized these degradat ion processes f o r marsh vege t a t i on . The ma te r i a l leached i s i n the form o f very l a b i l e compounds (sugars , s t a r che s , o rgan i c a c i d s , e t c . ) and appears to 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 (Ga l l agher e t al_. 1976). Once the o rgan i c compounds en t e r i n t o s o l u t i o n , the re i s a r ap i d inc rease i n the a s soc i a t ed b a c t e r i a and fungi as the var ious p l an t components become a v a i l a b l e f o r degradat ion . Except f o r the high energy i n t e r t i d a l marshes, i t appears t ha t b i o l o g i c a l degradat ion i s the main agent i n p l an t f ragmentat ion 19 (Burkho lder and Brons ide 1957, Gossen l ink and K i rby 1974). B i o l o g i c a l degradat ion i nvo l ves a wide range o f organisms which sub jec t the dead vegeta t i on to a whole success ion o f processes such as comminution, mix ing w i th minera l matter and changes i n the phys i ca l s t r u c t u r e o f the o rgan i c d e b r i s . The r o l e o f i n v e r t eb r a t e d e t r i t o vo r e s i n the mechanical breakdown o f dead vege ta t i on was emphasized by Fenchel (1970). He noted tha t the a c t i v i t y of the i n ve r t eb ra t e s con t r i bu ted more to community r e s p i r a t i o n than to the metabo l i c a c t i v i t y o f the i n ve r t eb ra t e s themselves. I t i s a l s o known tha t f e c a l ma te r i a l from these i nve r t eb ra t e s prov ides a l a rge sur face area f o r m i c r ob i a l c o l o n i z a t i o n which i n tu rn enhances the decomposit ion o f p a r t i c u l a t e o rgan i c matter i n the environment. At the same time r e co l on i z ed f e c a l matter can be u t i l i z e d by "depos i t " feed ing i n ve r t eb ra t e s thereby enhancing t h e i r food supply (Hargrave 1975). Engelman (1961, 1968) d i scussed the importance of d i g e s t i o n and eges t i on i n s o i l ar thropod communities and presented a community model having a we l l i n t eg ra t ed d e t r i t a l component to emphasize the r e cupe ra t i ve nature o f d e t r i t a l food chains i n which the t r a n s f e r o f matter and energy i s p r i m a r i l y through success ive consumption o f the egested m a t e r i a l . M i c r o b i a l decomposit ion o f wet land p lan ts i s by f a r the most complex degradat ion mechanism. As a decomposer m i c r o f l o r a begins to c o l on i z e the dead p l a n t , i t p lays a dual r o l e as a food source f o r many de t -r i t o v o r e s and as an agent f o r the biogeochemical r e c y c l i n g o f elements i n the ecosystem. Both b a c t e r i a and fung i p l ay an important r o l e i n the degradat ion o f p l an t m a t e r i a l . Mor r i son et al_. (1977) have shown tha t 20 the i n i t i a l su r face 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 ime , d i l u t e d by f u n g i , a lgae and o ther more complex organisms. He te ro t roph i c a c t i v i t y can be app rec i ab l y i n f l uenced by m i c r o f l o r a l su c ces s i on , p a r t i c u l a r l y dur ing major s h i t s i n type and number o f organisms. As the m i c r ob i a l - d e t r i t a l complex matures and protozoans and micro i n ve r t eb ra t e s appear, m i n e r a l i z a t i o n ra tes o f , f o r example, phosphorus (Barsdate e t al_. 1972) and carbon (Fenchel 1970) i nc rease s i g n i f i c a n t l y . I t appears tha t the processes a s soc i a t ed w i th b i o l o g i c a l degradat ion 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 enr ichment o f the o rgan i c d e t r i t u s presumably by convers ion of low p r o t e i n p l an t t i s s u e to high p r o t e i n m i c r o b i a l b iomass. Odum and de l a Cruz (1967), Kaushik and Hynes (1971), de l a Cruz and Gabr i e l (1974) and de l a Cruz (1975) repor ted an ash f r ee crude p r o t e i n range o f 5 to 24 percent o f p a r t i a l l y decomposed and par-t i c u l a t e d e t r i t u s . The degradat ion o f p l an t ma te r i a l to s ubpa r t i c u l a t e forms together w i th the p r o t e i n enrichment are g ene r a l l y cons idered to be the main l i n k i n the food cha in between wet land f l o r a and t h e i r a ssoc i a ted and f r equen t l y abundant secondary consumers (Burkho lder and Borns ide 1957, Odum and de l a Cruz 1967, de l a Cruz 1975). Odum (1971) cons idered microorganisms the pr imary consumers i n such de t r i t u s -based systems. 2.7.3 Accumulat ion pathway Accumulat ion o f dead vege ta t i on appears to be a common f ea tu re o f some wetlands e s p e c i a l l y where cond i t i ons do not favour r ap i d decompos-i t i o n , t r a n s p o r t a t i o n to o ther hab i t a t s or where o x i d a t i o n processes such as f i r e are uncommon. I f decomposi t ion and/or t r a n s po r t a t i o n r a t e 21 f a i l s to keep pace w i th dry matter p roduc t i on , then peat and s i m i l a r o rgan i c matter w i l l be formed. The r a t e o f peat fo rmat ion and accumulat ion w i l l depend upon the r a t i o of dry matter p roduct ion and removal . Peat accumulat ion i n any system i s a slow and compl i cated process . Walker (1970) gave an average f i g u r e to be i n the order o f 20 to 80 cm i n 1,000 y ea r s . Cameron (1970) has accumulated some data on peat fo rmat ion i n North Amer ica . He repor ted bog growth va lues o f the o rder o f 100 to 200 cm i n 1,000 years i n some wet lands o f Canada and the Un i ted S t a t e s . A cons ide rab le amount of energy from pr imary product ion remains s to red up i n the peat and p e a t - l i k e m a t e r i a l s . Th i s s torage o f reserve energy by wet land systems i s o f cons i de rab l e importance s i n ce such " f o s s i l " energy can be tapped by man and re leased i n combust ion. 22 3. GENERAL DESCRIPTION OF THE STUDY AREAS, SUBSTRATES AND SPECIES B r i t i s h Co lumbia 's wetlands c o n s t i t u t e an important percentage o f the p r o v i n c i a l land base. D i f f e r e n t forms of wet land are encountered throughout the Prov ince depending on e l e v a t i o n , c l i m a t e , s o i l t ype , n u t r i e n t l e v e l s , water t u r b i d i t y , temperature, c i r c u l a t i o n and general hyd ro l og i c regime o f the watersheds. In southwestern B r i t i s h Columbia, they range from b rack i sh coas ta l marshes and i n t e r -t i d a l lands to f r e sh water meadows and f i e l d depress i ons . "Before the advent of whi te man, much of the lower F raser v a l l e y was we t l and . " (Nor thco te , 1974). Dykes have g r e a t l y reduced the wet land areas; w i thout dyk ing , there i s l i t t l e doubt they should s t i l l be near l y as wet as those areas which are now l y i n g ou ts ide of the dyking systems. The s i t e s chosen f o r study (F igure 3.1) a l though not t r u l y r e p r e s en 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 eas t coast o f Vancouver I s l and and a l s o to the coas ta l wet lands of Washington and Oregon. 3.1 T i da l Marshes of the F raser Foreshore On the bas i s o f severa l s tud i e s commissioned by the Federal Government (Hoos and Packman, 1974), the F raser d e l t a was proposed to be comprised of 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 of the F raser r i v e r and Boundary Bay. Th is 2 area i s es t imated to be approx imate ly 337 km and almost a l l o f i t i s e i t h e r dyked, or above the i n f l u ence o f the t i d e . I t should be noted however, tha t l a rge areas of the a l l u v i um of " r a i s e d " and low l e v e l F igure 3.1: Map showing Loca t i on o f the Study Areas . I SITED STATES O l AMERICA , I2J CO 4 ; 25 land be longing to the F raser system a l so occurs eas t o f New Westminster and tha t the system i s t i d a l as f a r as Har r i son r i v e r and l a k e . T ida l marshes e x i s t a long the seaward edge o f the F raser d e l t a , from the Vancouver mainland j u s t north of Sea I s l and to the Tsawassen causeway. In the main arm o f the F r a se r , above Westham I s l a n d , t i d a l marshes cover most of Duck, Barber and Woodward I s l and s , as we l l as Ladner marsh. A few narrow f r i n ge s of t i d a l marsh remain upstream o f Ladner i n Deas, Crescent and o ther s l oughs . The c o a s t l i n e of Boundary Bay a l so supports a f r i n g e o f t i d a l marsh from Beach Grove to Crescent Beach. The t o t a l t i d a l marsh area of the Fraser r i v e r -fo reshore i s est imated to be around 27 km (Yamanaka, 1975). The c l ima te o f t i d a l marshes f a l l w i t h i n the general category o f the west coast marine t ype , w i th m i l d w in te r s (mean January 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 of the geology of the Fraser r i v e r d e l t a i s g iven by Luternauer (Hoos and Packman, 1974). Our study s i t e s were l o ca ted a t Brunswick Po i n t and Iona I s l a nd . The vege ta t i on of Brunswick Po in t and Iona I s l and i s r ep r e sen t a t i v e o f b rack i sh t i d a l marshes. Both s i t e s are s i t u a t e d on the i n t e r f a c e o f f r e sh water from the F raser r i v e r , and the s a l t water wedges from the S t r a i t o f Georg ia . Hence the vege ta t i on not on ly e x h i b i t s a h o r i z on t a l zonat ion which i s ma in ly i n f l uenced by t i d a l exposure, but a l s o a g rada t i on from b rack i sh to marine water (F igure 3 .2 ) . The major vege ta t i on types have been descr ibed i n general terms by Burgess (1970), Forbes (1972), McLaren (1972), Hoos and Packman (1974), 26 F igure 3.2: Photographs showing Emergent Communities i n the Brunswick marsh (Summer 1977). Top photo: Carex lyngbye i i n f l owe r . Note t ha t f l owe r i ng time was consp icuous ly r e l a t e d to r e l a t i v e e l e va t i on s o f the s ub s t r a t e ; e a r l i e s t f l owe r i ng occurred on the s l i g h t l y e l eva ted sub s t r a t e s . Bottom photo: Carex lyngbye i i n foreground; f r e she t channel and a s soc i a t ed s i l t d epos i t . photographs for page 27 are missing 28 Yamanaka (1975) and Moody (1978). Common dominants are Sc i rpus  mar i t imus L., and Carex lyngbye i Horneum. Other spec ies common to the a rea , but which u sua l l y occur i n patches, i n c lude T r i g l o c h i n • mar i t ima 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 . , Sc i rpus  v a l i du s Vah l . and S a l i c o r n i a v i r g i n i c a L. Des c r i p t i on s o f the ve r t eb ra te and i n ve r t eb r a t e fauna of the wet lands are being assembled by Westwater Research Centre ( U n i v e r s i t y of B r i t i s h Co lumbia) , by The Canadian W i l d l i f e Se rv i c e (A laksen) 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 Vancouver). 3.2 Fresh Water Marshes - P i t t Meadows P i t t Meadows are about 45 km eas t of the c i t y of Vancouver. A g rea te r pa r t o f the land i s dyked aga ins t f l oods from the P i t t , A l oue t t e and F raser r i v e r s . The c l ima t e , s o i l s , vege ta t i on and fauna of the area were e x t en s i v e l y desc r ibed by Barnard (1975). B r i e f l y , the s o i l s are 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 parent m a t e r i a l . The water t ab l e r i s e s w i th cons ide rab le freedom dur ing the wet months and i s high through May and June, when the F rase r r i v e r f r e she t peaks. The vege ta t i on occurs i n stands of both p u r i t y and cons ide rab le d i v e r s i t y (F igure 3 .3 ) . The dominant spec ies i n c l ude P h a l a r i s arundinacea L., Ca lamagrost i s canadensis (Michx.) Beav. , Carex r o s t r a t a S tokes , Sc i rpus acutus Muh l . , Juncus  e f fusus L. and Equisetum spp. 29 F igure 3.3: Photographs showing Emergent Spec ies i n the P i t t marsh, Spr ing 1978. Top photo: Ca lamagrost i s canadensis i n foreground; Carex s i t c h e r i s i s , Sc i rpus cyper inus i n midground. Bottom photo: Emergent communities ou t s i de dyke, w i th P ha l a r i s arundinacea on dyke s l ope s . 30 31 3.3 Upland S i t e s A few dry land s i t e s were s tud i ed f o r comparison w i th the wet land h a b i t a t s . Most o f them were l o ca ted on areas sometimes des ignated as " o l d f i e l d " i . e . a rab le land tha t has been l e f t r e l a t i v e l y unmanaged f o r a few y ea r s . U n i v e r s i t y of B r i t i s h Columbia Farm i s l o ca ted on g l a c i a l t i l l and outwash about 100 meters above sea l e v e l . The c l ima te i s humid-mar i t ime. The s o i l s are we l l d r a i ned , s l i g h t l y a c i d i c and, a t one t ime, supported c l imax con i fe rous f o r e s t . The f i e l d s have been f r equen t l y plowed. Colony Farm i s about 15 km eas t o f the c i t y o f Vancouver. I t i s a P r o v i n c i a l Government d a i r y fa rm, w i th major hectarage e s t ab l i s hed to hay and pas tu re . The Dacty l i s g lomerata 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 rece i ves f e r t i l i z e r and manure annua l l y . The P ha l a r i s arundinacea s i t e chosen f o r the study i s l o ca ted 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 ed , except f o r occas iona l s p r i ng and f a l l f i r i n g o f the dead p l a n t m a t e r i a l . A laksen Nat iona l W i l d l i f e Refuge Farm i s on a l l u v i um subs t ra te of the F raser d e l t a f o r e sho re , a subs t ra te s i m i l a r to t ha t o f Brunswick and Iona marshes. The area i s we l l dyked and managed p r i m a r i l y f o r wa te r f ow l . Most o f i t i s e s t ab l i s h ed to pasture grasses and legumes such as Phleum  pratense L. ( t imo thy ) , Lo l ium perenne L. (pe renn ia l rye g r a s s ) , and T r i f o l i u m repens L. (white c l o ve r ) (F igu re 3 .4 ) . 32 F igure 3.4: Photographs showing Lol iurn perenne - Agropyron repens stand a t A laksen dyked a r ab l e o l d f i e l d . As a r e s u l t o f g raz i ng o f top and rhizome by na t i v e geese and widgeon i n one season, almost a l l the Lo l ium was removed and rep laced by Agropyron. 33 34 3.4 A t t r i b u t e s o f Some of the S i t e Subs t ra tes I t has been i n d i c a t ed tha t a g reat d i v e r s i t y e x i s t s , o f ten over very sho 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 nature o f B r i t i s h Columbia wet lands . Rather than r e l y e x c l u s i v e l y on sub-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 tha t a p r e sen ta t i on o f subs 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 usefu l f o r the purpose o f our s tudy . I t ' i s to be. r e i t e r a t e d tha t our i n v e s t i g a t i o n s centered l a r g e l y on p l an t mediated processes and not c l a s s i f i c a t i o n o f the wet lands . 3.4.1 M a t e r i a l s and methods Ana lyses were done on subs 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 to three s o i l cores were taken from each s i t e and composited to make a sample. The s o i l samples were d r i ed a t 60° C and pu l v e r i z ed i n a mortar w i th a p e s t l e . Organic mat ter was determined by the Wa lk ley-B lack procedure ( 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 prepared by mix ing 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 water . A f t e r shak ing f o r one hour, readings were taken us ing a Beckman pH meter. E l e c t r i c a l c o n d u c t i v i t y , a r e f l e c t i o n o f t o t a l s o l u t e s i n the s o i l s o l u t i o n , was measured w i th a c o n d u c t i v i t y meter ( rad iometer type CDM 2e) w i th the read ings expressed i n m i l l imhos/cm. S o i l p repa ra t i on was the same as f o r pH. Potass ium, ca l c i um, phosphorus and magnesium were 35 measured us ing methods o u t l i n e d i n the Morgan S o i l Tes t i ng System (Lunt e t al_. 1958). 3.4.2 Resu l t s Table 3 g ives crude est imates of some of the edaphic v a r i a b l e s measured. The t ab l e shows a wide range of 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 D i s cuss i on Except f o r P i t t marsh, most s i t e s g ene r a l l y have at l e a s t medium l e v e l s of minera l c ons t i t uen t s i n the s ub s t r a t e s . The low minera 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 each ing l o s s e s . In areas c ons t an t l y f l ooded l each ing and removal of i o n i c ma t e r i a l s i n waterways leave 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 the F raser d e l t a marshes, t i d a l f l u s h i n g b r ings i n so lu tes 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 rab le s i t e s a r e - r e l a t e d to uptake by the c u l t i v a t e d p l an t s pe c i e s . Organic matter i s g ene ra l l y much h igher i n wet lands compared to a rab le "dry" l ands . Th 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 rgan i c matter content would be a r e f l e c t i o n of long term accumulat ion of phytomass i n the wet lands . 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 rgan i c matter tending to accumulate near the dykes where t i d a l a c t i o n i s l e a s t . 36 Table 3.1 Electrical Conductivity (E.C.), pH, % Organic Matter (O.M.), and Available Major Elements in the top 10 cm of the Soil Profile of Some of the Study Sites Site E.C. pH % O.M. P K Ca Mg (mmhos/cm) Brunswick marsh 0.4 Iona marsh 0.5 Pi t t marsh 0.4 Alaksen 0.1 U.B.C. 0.1 Colony Farm (site 1) 0.9 Colony Farm (site 2) 0.1 6.7 10.2 med 6.6 10.6 med 4.8 51.3 high 5.8 9.1 med 5.9 4.2 med 4.5 6.0 med 4.8 10.6 med med med med med med med low low low low med med low med med med high high low med med Site 1 Dactylis glomerata site Site 2 Phalaris arundinacea site 37 Because n i t r ogen content i s dependent on the o rgan i c matter content o f the s o i l (Jackson 1958), i t should e x h i b i t the same t rend as o rgan i c mat te r . S i m i l a r l y s o i l phosphorus, w i th 45 - 50 percent g ene r a l l y cons idered to be o rgan i c , would r e f l e c t o rgan i c m a t t e r . l e v e l s . Some phosphorus may of course be l o s t v i a over f low of water from the wet lands. The i n f l u ence of s a l i n e marine water i n the t i d a l marshes accounts f o r the h igher pH a t the marshes wh i l e m i c r ob i a l a c t i v i t y may be a f a c t o r i n the more a c i d i c c ond i t i on s of the P i t t marsh. 3.5 De s c r i p t i o n o f the I nd i v i dua l P l an t Spec ies Stud ied In a recent paper, Bernard and Gorham: (1978) emphasized the need to study the l i f e h i s t o r i e s of wet land spec ies f o r they have a profound i n f l uence on the product ion processes 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 na tu ra l h i s t o r y t he re f o re as an i n t e g r a l pa r t o f the q u a n t i t a t i v e ecosystem eco logy . " Bernard and Gorham con-s i de red two p a r t i c u l a r aspects of sedge l i f e h i s t o r i e s as c r i t i c a l : (a) the very cons ide rab le green s tand ing crop i n w i n t e r and (b) the very h igh shoot m o r t a l i t y a s soc i a t ed w i th some sedge spec ies be fore a t t a i n i n g t h e i r "normal" l i f e span. Our contemporaneous s t u d i e s , a l though broader i n scope, are s i m i l a r l y d i r e c t e d . Presented 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 gross morpho l og i ca l , taxonomic and hab i t a t fea tures o f the p r i n c i p a l spec ies we se l e c t ed f o r study from southwestern B r i t i s h Columbia. Other fea tures are r e f e r r e d to i n the balance of the t ex t where r e l e van t . 38 3.5.1 Some Taxondmic f ea tu res .and hab i t a t s o f the p r i n c i p a l spec ies s tud ied* Species Family Habitat Distribution Equisetum f l u v i a t i l e (Scouring rush) Scirpus acutus (Hardstern bulrush) Scirpus (cyperinus?) (Wool-grass) Carex sitchensis (Sitka sedge) Calamagrostis  canadensis (Bluejoint) Phalaris arundinacea (Reed canary grass) Juncus effusus (Common rush) Typha l a t i f o l i a (Common cat-tail) Carex lyngbyei (Lyngby's sedge) Dactylis glomerata (Orchard grass) Equisetaceae Cyperaceae Cyperaceae Cyperaceae Graminaea Graminaea Juncaceae Typhaceae Cyperacea Gramineae Lolium perenne Gramineae (Perennial rye grass) Agropyron repens (Quack grass) Gramineae bogs and stand-ing water usually standing water, up to lm. deep shallow standing water shallow standing water water margins & land short flooded water margins & land short flooded tide f l a t s & most old fields shallow slow moving fresh water brackish water, intertidal arable land & old fields arable land & old fields arable land & old fields Alaska to Pennsylvania Widespread in temperate North America Canada to Florida Alaska to California Alaska to Quebec to California Circumboreal, Alaska to California Circumboreal, Alaska to Cali -fornia, Europe Alaska to Mexico, Erasia, North Africa Circumboreal along sea coasts Introduced to North America, native to Eurasia & North Africa Introduced to North America, native to Eurasia Introduced to North America, native to Eurasia * Nomenclature adopted from Hitchcock Cronquist (1973). et a l . (1969) and Hitchcock and 39 3.5.2 Some p l an 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 spec ies s tud i ed Species Standing shoot description Standing shoot in winter Root & Rhizome description Equisetum f l u v i a t i l e terete,hollow Scirpus acutus  Scirpus cyperinus Carex sitchensis Calamagrostis canadensis Phalaris arundinacea Juncus effusus Typha l a t i f o l i a Carex lyngbyei Dactylis glomerata  Lolium perenne terete, pithy, t a l l triangular, pithy, hollow tendency to tufting triangular, hollow,blades 3 ranked terete,hollow t a l l , blades 2 ranked tubular, caespitose, nearly bladeless erect, t a l l , spongy triangular, blades some-what succulent caespitose, blades caespitose, blades thin, 2 ranked shoot bases rarely green shoot bases rarely green dead dead except tips terete, hollow, dead blades 2 ranked dead green & dead dead green & dead dead dead rhizomes pithy, thick, very extensive rhizomes thick, pithy rhizomes short, pithy rhizomes extensive fine rhizomes, lacunae rhizomes thick, extensive lacunae rhizomes short, pithy rhizomes extensive, thick, pithy roots & rhizomes fine, pithy roots fibrous roots fibrous Agropyron repens blades thin, 2 ranked dead rhizomes solid, extensive 40 3.5.3 Some gross morpho log ica l f ea tu res of the s tand ing shoots In the wet land environment, s t r a t e g i e s "adopted" by d i f f e r e n t spec ies are many, undoubtedly to meet v a r i a t i o n s i n the phys i c a l c o n d i t i o n s . D i f f e r ences i n shoot he ight i n r e l a t i o n to water depth i s an apparent adap ta t i on . Pheno log ica l d i f f e r en c e s i n t ime o f shoot emergence, t ime o f f l owe r i ng and t ime o f shoot death may a l l be r e l a t e d to environmental changes. Some adapt ive f ea tu res o f the i n d i v i d u a l wet land spec ies were presented under Sec t i on 3 . 5 . 1 , some are i nco rpora ted below wh i l e others appear i n the balance o f the t ex t when r e l e v a n t . 3.5.3.1 Ma t e r i a l s and methods At what was deemed to be a general peak f o r s tand ing crops (October 1977), f ou r 0.25m quadrat samples were harvested f o r each spe c i e s . Dry weights were obta ined from the harves t from two quadrats . From the o the r two quadra ts , average shoot he i gh t s , numbers, volumes and photosynthe t i c areas were determined. Shoot volumes were es t imated by water d i s p l a c e -ment and volume/weight r a t i o s were computed. For spec ies l i k e Juncus  e f fusus w i th t ubu l a r shoots , su r face areas were c rude ly es t imated us ing the 2 II rh formula f o r a c y l i n d e r , wh i l e those o f spec ies l i k e Sc i rpus  cyper inus w i th t r i a n g u l a r c ross s e c t i o n s , the %nal formula f o r a r egu l a r pr i sm was used (Where r = rad ius o f a c y l i n d e r , h = he ight o f the c y l i n d e r , n = number o f s i des o f a p r i sm, 1 = s l a n t he ight and a = length o f one s i de of the pr ism base) . Area/weight r a t i o s were then computed. 41 3.5.3.2 Observat ions and r e s u l t s Table 3.2 shows some of the gross morpho log ica l data c o l l e c t e d from s e l e c t ed spec ies from P i t t (P) and Brunswick (B) marshes i n October 1977. For the P i t t marsh s pe c i e s , the t ab l e proceeds from very wet to l e s s mois t s i t e s . Desp i te the wide range o f v a r i a b i l i t y between spe c i e s , some c h a r a c t e r i s t i c t rends may be d i s ce rned along t h i s mo is ture g r ad i en t . Dry matter y i e l d s o f apparent peak s tand ing crops rough ly p a r a l l e l e d the water depth g rad i en t . Quadrat y i e l d s of Juncus e f fusus were not easy to determine because o f i t s caesp i tose na tu re . 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 matter than P h a l a r i s a rund inacea, the h ighes t y i e l d i n g spec ies from the P i t t marsh. Equisetum f l u v i a t i l e and Sc i rpus acutus shoots growing i n the we t tes t s i t e s had the h ighes t volume/weight r a t i o s . These r a t i o s were s i m i l a r to t ha t o f Typha l a t i f o l i a from Brunswick marsh. No d i s c e r n i b l e t rends cou ld be detected in the area/weight r a t i o s o f the shoots from d i f f e r e n t s pe c i e s . Although there was cons ide rab l e spec ies v a r i a t i o n , shoot dens i t y appeared to inc rease w i th decreas ing water depth. Sc i rpus acutus produced 23 shoots per 0.25m whereas Juncus e f fusus had a shoot dens i t y o f 934. The lowest shoot dens i t y was recorded 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 he ight ranged from 0.8m i n Equisetum f l u v i a t i l e and Juncus e f fusus to 1.6m i n P ha l a r i s a rund inacea. Typha l a t i f o l i a produced much t a l l e r shoots than the spec ies from P i t t marsh. 42 Table 3.2 Some gross morphological features of standing shoots of selected species from Pitt (P) and Brunswick (B) marshes, October 1977. Species Site Dry wt Ratio Ratio # shoots Average g/0.25m2 volume/wt area/wt per 0.25m height(m) 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 1.0 Carex s i t . P 213 6 118 78 1.1 Calamagrostis c. P 316 4 73 114 1.3 Juncus eff. P 290 8 98 934 0.8 Phalaris ar. P 482 5 67 163 1.6 Typha lat. B 426 13 83 15 2.7 43 3 .5 .3 .3 D i s cuss i on Morpho log ica l c h a r a c t e r i s t i c s such as shoot he i gh t , pho tosyn the t i c area and shoot volume can be o f cons ide rab l e va lue i n the understanding o f p roduc t ion processes and adapta t ion of wet land spec ies to t h e i r e nv i r on -ment. Dry matter y i e l d s at t ime o f peak s tand ing crop roughly p a r a l l e l e d water depth g r ad i en t . However the s tand ing crop a t any one t ime 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 iven s pe c i e s . Some spec ies are known to extend the length o f t h e i r ' g row ing ' season i n t o w i n t e r , ma in ta in i ng p h o t o s y n t h e t i c a l l y a c t i v e sur face f o r very long pe r i od s . Moreover, peak s tand ing crop does not take i n t o account any shoot m o r t a l i t y dur ing the growing season. Ex tens ive development of a i r c a v i t i e s , lacunae and p i t h y t i s s u e i n the roots 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 an t s growing under water-logged c o n d i t i o n s . These f ea tu res are r e f l e c t e d i n the high volume/weight r a t i o s recorded i n some of the spec ies examined. In b r a ck i sh or s a l i n e h a b i t a t s , succu lence appears to be an added adapt ive f ea tu re to the h igher l e v e l s o f s o l u t e . No d i s c e r n i b l e t rends were detec ted in the area/weight r a t i o s of the shoots from d i f f e r e n t s pe c i e s . There are o f course obvious d i f f i c u l t i e s a s soc i a t ed w i th l e a f area measurements. Some shoots are open, some are t e r e t e wh i l e others are v i r t u a l l y b l a d e l e s s . Shoot dens i t y o f the emergents appeared to d e c l i n e w i th i n c r e a s i n g water depth . Such a de c l i n e i n shoot number i s o f ten accompanied by decreased dry matter p roduc t i on . 44 4. PRODUCTIVITY OF EMERGENT VEGETATION I t was beyond the scope of t h i s study to present a d e t a i l e d i n v e s t i g a t i o n of the pr imary product ion processes of the wetlands o f B r i t i s h Columbia. Rather , our approach was to e s t a b l i s h some base l i ne data 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 o f the wet lands . Our admi t t ed l y crude and s imple approach enabled us to sample a f a i r l y l a r ge number o f p l an t communities cons i de r i ng the l i m i t a t i o n s o f t ime , space and funds . 4.1 Peak Standing Crop Y i e l d s The pr imary product ion o f wet lands may be obta ined by severa l methods: (1) measuring peak s tand ing crop; (2) maximum minus minimum stand ing crop; (3) d isappearance methods; (4) m u l t i p l e harvests and (5) gaseous exchange. The peak s tand ing crop method i s w ide l y used (West lake, 1963) and has the advantages o f being r e l a t i v e l y cheap, r a p i d and use fu l i n comparison to d i f f e r e n t p l an t communit ies. We cons idered the method to be s u i t a b l e f o r the purposes of our probes i n t o processes ope ra t i v e i n B r i t i s h Co lumbia 's wet lands , as i n fo rmat i on on these wetlands i s s t i l l very scanty . We a l so d i r e c t e d major a t t e n t i o n to s i n g l e crop ha rves t s , because o f the l i m i t a t i o n s o f t ime and the t e chn i c a l d i f f i c u l t i e s a s so c i a t ed w i th the o the r methods. 4.1.1 Ma t e r i a l s and methods In most wet lands o f south western B r i t i s h Columbia, the emergent vege ta t i on i s qu i t e sharp ly 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 an t s pe c i e s , each spec ies e x i s t i n g i n a lmost pure s tands . A c co r d i ng l y , samples o f each spec ies were t aken , more or l e s s c e n t r a l l y from a zone (pure s t and) . The f o l l o w i n g were the spec ies chosen f o r sampl ing: (a) From the P i t t marsh: Sc i rpus acutus Muh l .* (hardstem bu l rush) Equisetum f l u v i a t i l e L. ( scour ing rush) Juncus e f fusus L. (common rush) P ha l a r i s arundinacea L. (reed canarygrass) The order of the spec ies l i s t i n g f o l l ows a g radat ion from the we t tes t zones w i t h s tand ing water a l l season (top) to the l e a s t wet zones where s tand ing water i s found f o r on ly shor t per iods a l though the subs t ra te i s r a r e l y dry (bottom). (b) From Brunswick Po in t marsh: Carex lyngbye i Horneum (Lyngby's sedge) Typha l a t i f o l i a L. (common c a t - t a i l ) Festuca arundinacea Schreb ( t a l l fescue) The spec ies are l i s t e d i n order of decreas ing t i d a l i nunda t i on , Carex lyngbye i i s inundated by t i d e s f o r the l onges t p e r i o d , wh i l e Festuca arundinacea i s on ly i n f r e q u e n t l y sub jec ted to t i d a l waters . (c) From Iona I s l and marsh: Carex lyngbye i Horneum (Lyngby's sedge) Iona I s l and marsh i s s i m i l a r to tha t of Brunswick Po in t w i th the except ion tha t i t i s much i n f l uenced by sewage d i sposa l and o ther man mediated d i s t u rbance . 46 (d) From Alaksen (Nat iona l W i l d l i f e Refuge Farm): Lo l ium perenne L. (pe renn ia l ryegrass) Dacty l i s glomerata L. (orchard g rass ) Agropyron repens L. Beauv. (quack grass) Lo l ium perenne and Dacty l i s g lomerata , commonly used as hay and pas tu re , were i nc luded f o r compar ison. Migrant and r e s i d en t b i r d s grazed the s i t e so s e l e c t i v e l y t ha t the dominant Lo l ium d isappeared almost complete ly from the sward i n the f i r s t yea r o f the s tudy . (e) From Colony Farm ( P r o v i n c i a l Government Farm): P h a l a r i s arundinacea L. (reed canarygrass) Dacty l i s glomerata L. (orchard grass) To es t imate peak s tand ing crop y i e l d s , two samples were taken f o r each spec ies us ing one meter square quadra ts . The sampl ing frame was tossed i n t o the stand and ad jus ted so tha t a t l e a s t two meter d i s t ance was mainta ined between the edges o f ad jacent quadra ts . Green photo-s y n t h e t i c a l l y a c t i v e shoots were cut a t ground l e v e l , p laced i n bags, t ranspor ted to 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 tunnel d r i e r a t 60°C and weighed. 4 .1 .2 Resu l t s Cons iderab le v a r i a t i o n i n peak s tand ing crop es t imates were recorded a t the t i d a l and a r ab l e s i t e s (Table 4 . 1 ) . For the t i d a l marsh s i t e s , Carex lyngbye i produced the l e a s t dry matter as compared to Typha l a t i f o l i a and Festuca arund inacea. Carex lyngbye i g ene r a l l y 47 Table 4.1 Estimates of peak standing crop yields (dry matter in g/m , as averaged from two meter square quadrats on Brunswick and Iona marshes and in arable lands at Alaksen and Colony Farm) Location Species September 1976 October 1977 Brunswick marsh Iona Alaksen Colony Farm Carex lyngbyei  Typha l a t i f o l i a  Festuca arundinacea  Carex lyngbyei  Lolium perenne Phalaris arundinacea 745 1125 689 655 1055 424 1704 311 Table 4.2 Estimates of peak standing crop yields (dry matter in grams as averaged from two meter quadrats) for six species of the P i t t marsh, October 1977 Species Scirpus cyperinus Carex sitchensis , 2 g/m Scirpus acutus 316 Equisetum f l u v i a t i l e 2 24 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 , wh i l e the o ther two spec ies are f r equen t l y found at h igher t i d e l e v e l s . From the a rab l e s i t e s , P h a l a r i s arundinacea had a h igher peak s tand ing crop (1055 g/m ) than Lo l ium perenne (483 2 g/m average ) . A general t rend of i n c r ea s i ng s tand ing crop y i e l d s from more hyd r i c to l e s s hyd r i c h ab i t a t s was noted f o r the spec ies sampled from the P i t t marsh (Table 4 . 2 ) . Equisetum f l u v i a t i l e produced the l e a s t dry matter 2 (224 g/m ) wh i l e P ha l a r i s arundinacea produced the h ighest y i e l d (1928 g/m 2 ) . 4 .1 .3 D i s cuss i on From Table 4 . 1 , i t can be seen tha t peak y i e l d s f o r Carex lyngbye i o f the Brunswick and Iona marshes are lower than those f o r Festuca  a rund inacea, the common spec ies o f the zone nearer the dyke and the high t i d e l e v e l . Typha l a t i f o l i a occupies a s pe c i a l h ab i t a t a long the f o re sho re , o c cu r r i ng main ly where g r a v i t a t i o n a l water appears to i n f l ow through the dykes from nearby a g r i c u l t u r a l l ands . Subst ra te and water l e v e l t he re f o re appear to be major y i e l d determinants (F igure 4 . 1 ) . These observa t i ons are supported by peak s tand ing crop y i e l d s g iven by Yamanaka (1975) f o r the F raser d e l t a marshes i n c l ud i ng Brunswick and Iona marshes. Yamanaka noted tha t f o r a g iven marsh, there was a rough ly l i n e a r decrease i n peak s tand ing crop y i e l d s w i th i n c r ea s i ng d i s tance seaward from the dykes. The data obta ined from the P i t t marsh (Table 4 . 2 ) , a l s o i n d i c a t e tha t as the marsh zonat ion grades towards the near aqua t i c h a b i t a t , 49 F igure 4 . 1 : Photographs showing Va r i a t i o n s i n Communities w i th Va r i a b l e Water Depth. Top photo: P i t t marsh, sp r i ng 1978 Bottom photo: Brunswick marsh, sp r i ng 1978 (Douglas f i r l og f l o t sam i n foreground o f t en l o c a l l y d e s t r u c t i v e o f p l an t c o ve r ) . So 51 spec ies by s pe c i e s , peak s tand ing crop y i e l d s d e c l i n e . The change i n va lue i s so marked tha t desp i t e the c r u d i t y of the peak harvest techn ique , i t may be i n f e r r e d tha t the gradat ion i s v a l i d . Data from peak y i e l d quadrats can be use fu l f o r broad com-pa r a t i v e purposes. However, such est imates appear to be too con-s e r v a t i v e o f t en i gno r i ng l osses from senescence, decay, ab ras ion or g r a z i ng . 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 l a t e r d i s c u s s i o n s , to ml^ie&eJ^gifeSfcy the p re c i s e t ime o f maximum dry matter p r oduc t i on . • ' 4.2 Seasonal Changes in Dry Matter Product ion I t was qu i t e apparent very e a r l y i n t h i s study tha t the growth and development pat te rns of the va r i ous p l an t spec ies under i n v e s t i g a t i o n were very d i f f e r e n t . Because of these 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 tha t data from s i n g l e date harvests would very l i k e l y m i s -represent ac tua l dry matter p roduct ion by the spec i e s . Al though the approach o f sequen t i a l sampl ing has i t s weaknesses, the technique i s supe r i o r to the s i n g l e harvest method i n e s t ima t i ng t rue dry matter p roduc t ion because i t takes i n t o account such d i f f e r e n c e s i n spec ies growing pa t t e rn s . A c co r d i ng l y , we dec ided to c o l l e c t s tand ing crop data a t i n t e r v a l s of severa l months to supplement the peak s tand ing crop data presented i n Sec t i on 4 . 1 . 52 4.2.1 Ma t e r i a l s and methods The ma t e r i a l s and methods were s i m i l a r to those desc r i bed under Sec t i on 4 . 1 . 4 .2 .2 Observat ions and r e s u l t s The seasonal changes i n dry matter of s tand ing crops of severa l spec ies from the F raser d e l t a marshes and a rab l e lands are presented i n Table 4 . 3 . The t ab l e shows tha t most spec ies exper ienced a r ap i d growth i n the sp r i ng and e a r l y summer months but t ha t time of peak dry matter p roduc t ion d i f f e r e d w i th s pe c i e s . Carex lyngbye i had peak s tand ing crop probably around J u l y or August d e c l i n i n g i n September, wh i l e Festuca arundinacea extended i t s peak y i e l d to a much l a t e r date . S i m i l a r t rends were apparent f o r the a rab l e s pe c i e s , Pha l a r i s  arundinacea behaving much Tike Festuca arund inacea. The seasonal changes i n s tand ing crop y i e l d s of severa l p l an t spec ies sampled from the P i t t V a l l e y marsh i n May and October 1977 are presented i n Table 4 .4 . May y i e l d s were cons i de rab l y lower than October y i e l d s f o r a l l spec ies examined. The t rend o f dec reas ing dry matter p roduc t ion w i th i n c r ea s i ng h yd r i c c ond i t i on s were d i sce rned e s p e c i a l l y i n the October samples. I t appears tha t the seasonal l i f e h i s t o r i e s o f p l an t spec ies i n wetlands have a profound i n f l u ence on t h e i r p roduct ion processes . Some of these l i f e h i s t o r y events were recorded i n our s t u d i e s . In g ene r a l , t im ing o f shoot death appeared to vary w i th spec ies (F igure 4 . 2 ) . 53 Table 4.3 Seasonal changes i n the standing crops (g/m dry matter) of f i v e species from the Fraser d e l t a marshes and a r a b l e lands, Summer 1976. L o c a t i o n Species May 18-23 June 5-7 J u l y 5-9 Sept. 16-21 Iona marsh Brunswick marsh Colony Farm Alaksen a r a b l e f i e l d Carex l y n g b y e i 351 Carex l y n g b y e i 661 Festuca arundinacea - 787 P h a l a r i s arundinacea 520 Lolium perenne - 773 D a c t y l i s glomerata 520 844 872 900 844 689 745 1125 714 1055 688 665 Table 4.4 Seasonal changes i n standing crops (g/m dry matter) of four species from the P i t t marsh, 1977. Species May 1977 October 1977 Scirpus cyperinus  Carex s i t c h e n s i s  Calamagrostis canadensis P h a l a r i s arundinacea 200 165 149 507 1100 852 1264 1928 54 F igure 4 .2 : Photographs showing Con t ras t s i n Timing o f Shoot Death, Iona marsh. Top photo: brown Carex lyngbye i green Elymus yancouve r i ens i s , Bottom photo: l i v e and dead shoots of Juncus e f fusus i n mid w in te r ( P i t t ) 56 The number o f Carex lyngbye i shoots dy ing seemed to be minimal around f r e s h e t time i n June and J u l y . In September and October , dramat ic death o f shoots was observed and appeared to be r e l a t e d to the advent o f s a l t water from storms. On the o ther hand, Festuca arund inacea, a coarse grass e s t a b l i s h e d a t f a i r l y high t i d e l e v e l s , u sua l l y remained green we l l i n t o the autumn. Most of the cu r r en t season 's shoots o f the spec ies s tud i ed were dead by l a t e f a l l u s ua l l y before the advent o f f r e e z i n g temperatures. During w i n t e r , new shoots o f some marsh spec ies emerged from the subs t ra te to he ights rang ing from a few m i l l i m e t e r s to 50 mm or more. V a r i a t i o n s i n pheno log i ca l pa t te rns o f development were a l so noted in the P i t t marsh emergents. Carex s i t c h e n s i s was in f u l l f l ower before shoots o f Sc i rpus acutus had emerged from the s ub s t r a t e . Cons iderab le development o f new pho tosyn the t i c shoots o f Carex s i t c h e n s i s and Juncus e f fusus took p lace dur ing the w i n t e r months. In s p r i n g , a k ind o f "high l i n e " cou ld be seen across Carex s i t c h e n s i s stands d e l i n e a t i n g the overwintered ma te r i a l s from green shoots o f the cu r ren t season (F igure 4 . 3 ) . 4 .2 .3 D i s cuss i on Seasonal trends i n s tand ing crop were not so e a s i l y d i s c e r n i b l e p a r t l y because the samples were not c o l l e c t e d f r equen t l y enough i n any one yea r . But i n g e n e r a l , dry matter 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 adua l l y i n c r ea sed , reach ing a peak i n mid season f o r spec ies l i k e Carex l yngbye i and l a t e r i n the season f o r spec ies l i k e Pha l a r i s arundinacea and Festuca arund inacea. These f i n d i ng s are i n genera l 57 F igure 4 .3 : Photographs Showing Older Overwintered F lower ing Shoots and New Shoots o f Carex s i t c h e n s i s i n P i t t marsh (Spr ing 1976). 59 agreement w i th those of Barnard (1975) and Moody (1978) who repor ted J u l y and August to be the per iod o f peak dry matter p roduct ion f o r most common spec ies o f the P i t t and F raser d e l t a fo reshore marshes r e s p e c t i v e l y . However, our r e s u l t s show tha t some Important spec ies from the same marshes may reach peak y i e l d s much l a t e r than August . From our obse r va t i on s , i t appears t ha t innate d i f f e r en ce s i n spec ies l i f e h i s t o r y and pheno log ica l development cou ld be very important i n determin ing the seasonal pat te rns o f dry matter p roduc t ion by the emergent communit ies. A l though seasonal t rends i n dry matter p roduct ion may be spec ies c h a r a c t e r i s t i c , such t rends may be cons i de rab l y a l t e r e d by the many unpred i c tab l e events i n the wet land environment. Spec ies y i e l d pa t te rns cou ld 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 soc i a ted w i th heavy r a i n s i n the P i t t marsh or by high t i d e s b r i n g i n g i n s a l i n e water o f va ry ing date and volume i n the Brunswick marsh. Such e r r a t i c changes are not uncommon i n the wet lands s tud i ed (Barnard 1975, Moody 197,8). I t i s t he re f o r e reasonable to assume that y e a r l y d i f f e r en c e s i n dry matter product ion e x i s t even w i t h i n the same s tand . 4 .3 Year to Year V a r i a t i o n i n Spr ing Standing Crops Quadrat samples f o r es t imates of s tand ing crops were g ene r a l l y taken from s i t e s h i gh l y uni form i n stand and sub s t r a t e . Moreover, most stands sampled were a s so c i a t ed w i th sharp ecotones; i n o ther words, there was l i t t l e i n t e r g r ada t i o n from zone to zone. Given the stand 60 p u r i t y and our s t r a t i f i c a t i o n us ing mid-zone s i t i n g , one would expect l i t t l e year to year v a r i a t i o n i n samples obta ined from a s p e c i f i c date . We tes ted t h i s hypothes is by sampling on approx imate ly the same date over a three year per iod i n the same general l o c a t i o n s . 4.3.1 Ma t e r i a l s and methods The ma t e r i a l s and methods were s i m i l a r to those desc r ibed i n Sec t i on 4 . 1 . Sampling was undertaken a t approx imate ly the same date i n May of 1976, 1977 and 1978, and i n the same general l o c a t i o n s . 4 .3 .2 Resu l t s Large spec ies d i f f e r en c e s i n sp r i ng s tand ing crop can be seen 2 from Table 4 . 5 . The s tand ing crop y i e l d s ranged from 127 g/m i n 2 Sc i rpus cyper inus to 561 g/m i n Dacty l i s g lomerata. Loca t ion d i f f e r en ce s were a l s o ev i den t . The a rab l e spec ies from Alaksen had h igher sp r i ng s tand ing crops than the spec ies from the P i t t and Brunswick marshes. However, f o r each spec ies there was very l i t t l e v a r i a t i o n i n s tand ing crop over the three year pe r i od . 4 .3 .3 D i s cuss i on The data from Table 4.5 con f i rm our o r i g i n a l surmise tha t l i t t l e year to year v a r i a t i o n i s to be expected from samples taken from the same s i t e on the same date a l though between spec ies and between s i t e 61 Table 4.5 Spring standing crop estimates of ei g h t species from three 2 l o c a t i o n s (g/m dry matter as averaged from two meter square quadrats). L o c a t i o n Species May 1976 May 1977 May 1978 Brunswick marsh P i t t marsh Alaksen o l d f i e l d 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 Carex s i t c h e n s i s 168 165 178 Calamagros t i s canadensis 154 149 180 P h a l a r i s arundinacea - 507 480 D a c t y l i s glomerata 520 561 Lolium perenne - 487 540 62 v a r i a t i o n s can be very l a r g e . The high 1976 s tand ing crop va lue f o r Carex lyngbye i can be a t t r i b u t e d i n pa r t to inadequate sepa ra t i on o f green ma te r i a l s from the o l d growth. The low w i t h i n s i t e v a r i a t i o n i n s tand ing crop i s probably r e l a t e d to the r a t he r uni form mar i t ime temperatures of the coas t , e s p e c i a l l y i n s p r i n g , which should have a moderat ing e f f e c t on marsh water temper-a ture hence s t i m u l a t i n g uni form growth. Fur ther s t ud i e s are necessary to determine i f the s i t u a t i o n holds t rue f o r o ther seasons of the yea r . The l a t t e r pa r t o f the year i s o f t en a s soc i a t ed w i th s ub s t an t i a l and h i gh l y v a r i a b l e changes i n terms o f c l i m a t e , t ime o f f r e s h e t , magnitude of f r e she t e t c . In t h i s case , the annual d i f f e r en c e s may be of a very d i f f e r e n t o rde r . 4.4 Quan t i t a t i v e Est imates o f Dead Phytomass Recogn iz ing the use fu lness o f dead phytomass es t imates p a r t i c u l a r l y w i th regard to shoot m o r t a l i t y , net pr imary produc t ion and d e t r i t a l p rocesses , p a r t i t i o n i n g o f green and dead shoots was undertaken. The dead shoot es t imates i n c luded combined f r a c t i o n s o f dead s tand ing c rop , sur face l i t t e r and du f f . Such es t imates are undoubtedly crude i n view of the l a r ge v a r i a t i o n s to be expected i n the dead components but i t should be noted tha t s tud i e s of "o ld growth" i n the wetlands o f south western B r i t i s h Columbia are s t i l l on ly i n t h e i r you th fu l s tages . 4.4.1 M a t e r i a l s and methods 63 The ma te r i a l s and methods were s i m i l a r to those desc r i bed i n prev ious se c t i ons f o r green s tand ing c rop . Combined s tand ing and su r face l i t t e r and du f f were c o l l e c t e d from dup l i c a t e square-quadrats o f 2 0.25m s i z e . In the p r e s en t a t i o n , the combined l i t t e r f r a c t i o n s are des ignated as o l d growth. 4 .4 .2 Observat ions and r e s u l t s Table 4.6 shows tha t o l d growth was present i n a l l the spec ies sampled from the t i d a l marshes and nearby a rab le lands throughout the summer months. The amount o f o l d growth i n Festuca arundinacea stands dec l i ned from May to September. In Carex lyngbye i s tands , o l d growth y i e l d s dec l i ned between May and J u l y and then inc reased i n September. The h ighes t o l d growth y i e l d s were recorded i n Festuca  arund inacea. At the d r i e r upland s i t e s , seasonal dead biomass changes were s i m i l a r to those of Carex l y ngbye i , the amount of o l d growth d e c l i n i n g from May to J u l y and then i n c r ea s i ng i n September. P h a l a r i s arundinacea accumulated more dead ma te r i a l than Lo l ium perenne or Dacty l i s g lomerata. Old growth y i e l d s o f f i v e spec ies sampled from the P i t t marsh i n May and October 1977 are g iven i n Table 4 .7 . Except f o r Carex s i t c h e n s i s , there was a d e c l i n e i n o l d growth y i e l d s from May to October. 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 detected between o l d growth accumulat ion and seasonal p e r i o d i c i t y of f l o o d i n g . However, examinat ion of the s o i l 64 Table 4.6 Dry matter yields (g/m ) of new growth (NG) and old growth (OG) of selected species from the Fraser delta marshes and nearby arable lands, Summer 1976. Location Species May June July Sept. 18-23 5-7 5-9 16-21 Iona marsh Carex lyngbyei NG 351 OG 201 872 151 689 301 Brunswick marsh Carex lyngbyei NG OG 661 27 900 24 745 35 Festuca arundinacea NG OG 787 731 844 520 1125 366 Colony Farm Phalaris arundinacea NG 520 OG 1267 714 408 1055 576 Alaksen old f i e l d Lolium perenne NG OG 773 13 688 18 665 24 I I it Dactylis  glomerata NG OG 520 7 844 6 65 2 Table 4.7 Dry matter y i e l d s (g/m ) of new growth (NG) and o l d growth (OG) of f i v e species from the P i t t marsh, 1977. Species May October Scirpus acutus NG * 316 OG * 312 Scirpus cyperinus NG 200 1100 OG 691 330 Carex s i t c h e n s i s NG 165 852 OG 453 644 Calamagrostis canadensis NG 149 1264 OG 428 150 P h a l a r i s arundinacea NG 507 1928 OG 1126 200 * under water Table 4.8 Dry matter y i e l d s (g/m2) of o l d growth f o r some s p e c i e s , Winter of 1977/78. L o c a t i o n Species Nov. 15 Mar. 3 % Loss Between 1977 1978 Nov. & March Brunswick marsh P i t t marsh Alaksen o l d f i e l d Carex l y n g b y e i 758 Typha l a t i f o l i a 3576 Scirpus cyperinus 1260 Carex s i t c h e n s i s 1230 Calamagrostis canadensis 1177 Agropyron repens 624 384 2814 1172 1177 1012 414 49.3 21.3 7.0 4.3 14.0 33.6 66 p r o f i l e showed marked f i b r o u s peat accumulat ion i n the wet tes t zones wh i l e the d r i e r subs t ra tes were main ly a l l u v i a l s i l t . In the w in te r of 1977/78, dead biomass changes were f o l l owed i n the Brunswick and P i t t marshes and on the A laksen quasi o l d f i e l d . The data are presented i n Table 4 .8 . Measurable l o sses were recorded i n the w in te r desp 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 aspects o f the l o s s p rocess . Losses from the warmeY t i d a l marsh and a rab le s i t e s were h igher than those from the co l de r P i t t marsh s i t e s . 4 . 4 . 3 D i s cuss i on The o l d growth data presented, a l though c rude, po r t r ay a few trends tha t are worthy o f ment ion. The general d e c l i n e i n o l d growth y i e l d s as the season progresses i s r e l a t e d i n par t to inc reased decomposit ion ra tes as temperature r i s e s from sp r i ng to summer. Decomposit ion 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 increases i n September and October (see Tables 4.6 and 4.7) would be r e l a t e d to inc reased shoot m o r t a l i t y which takes p lace towards the end of the growing season. At the t i d a l marsh s i t e s , lower o l d growth va lues were recorded f o r Brunswick Po in t compared to Iona I s l a nd . T ide and f r e s he t waters are very a c t i v e i n the Brunswick marsh w i th the r e s u l t tha t much of the dead shoot ma te r i a l i s exported from the s i t e as i t forms. By c o n t r a s t , the waters o f Iona marsh are gene ra l l y l e s s t u rbu l en t and dead shoots accumulate f o r longer pe r i ods . 67 Festuca arundinacea accumulated more o l d growth than Carex  lyngbye i because o f i t s es tab l i shment and h igher t i d e l e v e l s so t ha t i t i s on l y o c c a s i o n a l l y sub jec ted to t i d e and storm water. Th is grass i s a l s o coarse and h i gh l y f i b r ou s so t ha t i t degrades r a t he r s l ow l y . Death and degradat ion o f the shoots of the grasses from the upland s i t e s occur red throughout the sampl ing pe r i od but a t no t ime i n summer was there any marked o l d growth accumula t ion . The high temperatures in these s i t e s undoubtedly encourage more m i c r ob i a l a c t i v i t y and comminution by s o i l organisms. P h a l a r i s arundinacea had h igher o l d growth y i e l d s because i t i s more f i b r ou s than Lo l ium perenne and Dacty l i s g lomerata . From the high dead phytomass est imates and low percentage l osses recorded a t the P i t t marsh s i t e s (Tables 4.7 and 4 . 8 ) , i t appears tha t decomposit ion r a t e s are much s lower a t these s i t e s compared to the t i d a l marsh and a rab l e s i t e s . Slower decomposit ion r a te s a t the P i t t marsh may be r e l a t e d to many f a c t o r s among which are absence of t i d a l a c t i o n hence l e s s f ragmentat ion and lower mean monthly temperatures hence l e s s m i c r ob 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 should be emphasized a t t h i s po in t tha t the study of l i t t e r dynamics i s a complex one. S a t c h e l ! (1967) o f f e r ed a condensed review of l i t t e r i n t e r f a c e of animate and inanimate matter and i t s re levance to agronomy, p o l l u t i o n and o ther ecosystem processes . He po inted out tha t l i t t e r processes are o f t en complex and pro longed, i n i t i a t i n g f r equen t l y before death a t ra tes which depend on the p lan t subs t ra te as we l l as the c h a r a c t e r i s t i c s of the environment. The meaning o f 68 " l i t t e r " i t s e l f i s obscure (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 ab i t a t s so t ha t any d e f i n i t i o n must be regarded as a r b i t r a r y . I t i s c l e a r nonethe less t ha t the l i t t e r i tem c o n s t i t u t e s an important process i n these wet lands . 4.5 Belowground Phytomass I t appears t ha t the phytomass ( root and rhizome) belowground comprises a l a r ge and major pa r t o f the t o t a l phytomass o f a g iven area of wet land (Ga l l agher 1974). The belowground f r a c t i o n i s c e r t a i n l y much l a r g e r than tha t commonly found i n we l l dra ined subs t ra tes such as a rab l e l ands . A somewhat s i m i l a r f r a c t i o n a t i o n has been recorded i n the phytomass of h igh 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 1967). I t i s to be noted tha t phytomass produc t ion s tud i e s i n wet lands have tended to ignore belowground f r a c t i o n s (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 working i n the 'mud and water ' and a l s o because of the d i f f i c u l t y i n separa t ing l i v i n g from dead p l an t m a t e r i a l . In view o f the importance of roo ts and rhizomes p a r t i c u l a r l y as energy s torage organs, attempts were made to determine (1) belowground phytomass y i e l d s and (2) the amount of ' a v a i l a b l e ' or r e a d i l y hyd ro l y zab l e carbohydrates i n the belowground organs. 4 .5.1 Ma t e r i a l s and methods 2 Aboveground s tand ing shoots were harvested from 0.25m quadrats i n November 1977. Roots and rhizomes were sampled from the same 69 quadrats by t ak i ng cores w i th a plugger to a depth of 30 cm. The p lugger cores had a diameter o f 8.5 cm. Two cores were taken from each quadrat . Each core was cut i n t o two 15 cm sec t i ons i n the f i e l d , bagged and t ranspor ted to the U n i v e r s i t y of B r i t i s h Columbia P l an t Sc ience F i e l d Lab where they were washed i n a s p e c i a l l y designed root washing machine employing water j e t s and s i e v e s . Success fu l separa t i on of l i v i n g and dead ma te r i a l s cou ld not be ach ieved w i th cons i s tence 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. Resu l t s are repor ted as belowground dry matter per 0.25m 2 . ' A v a i l a b l e ' or r e a d i l y hydro l yzab le carbohydrates were es t imated by the pheno l - su lphu r i c a c i d method descr ibed by Barnet t (1954); absorbance was read a t 480 nm w i th a Perk in-E lmer double beam spectrophotometer. 4 .5 .2 Observat ions and r e s u l t s Desp i te the d i f f i c u l t y i n separa t ing l i v i n g from dead belowground phytomass i t was apparent tha t most of the ma te r i a l i n c luded was l i v i n g or near l i v i n g . Furthermore, desp i te the l a teness of the ha rves t , aboveground dry matter y i e l d s determined probably prov ided a crude es t imate o f peak s tand ing c rops . The data g iven i n Table 4.9 show tha t most o f the belowground phytomass tended to be concentrated in the upper ( 0 - 1 5 cm) hor i zons o f the s ub s t r a t e . Carex s i t c h e n s i s had the h ighes t t o t a l belowground phytomass 70 T a b l e 4 . 9 B e l o w g r o u n d phy tomass ( 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 f r o m B r u n s w i c k m a r s h , P i t t m a r s h and P i t t o l d f i e l d , November 1 9 7 7 . B e l o w g r o u n d phy tomass by c o r e d e p t h * 0 - 1 5 cm 15 - 30 cm T o t a l L o c a t i o n S p e c i e s g / 0 . 2 5 m 2 % g / 0 . 2 5 m 2 % B r u n s w i c k marsh S c i r p u s a m e r i c a n u s 721 84 139 16 860 C a r e x l y n g b y e i 1127 89 146 11 1273 it Typha l a t i f o l i a 1418 85 248 15 1666 P i t t marsh S c i r p u s c y p e r i n u s 1080 58 786 42 1866 ii C a r e x s i t c h e n s i s 1862 88 248 12 2110 I I C a l a m a g r o s t i s c a n a d e n s i s 1252 64 717 36 1969 I I J u n c u s e f f u s u s 320 94 21 6 596 P i t t o l d f i e l d L o l i u m p e r e n n e 302 100 0 0 302 * v a l u e s a r e a v e r a g e s o f two s a m p l e s 71 wh i l e Lo l ium perenne, a dry land s pe c i e s , had the lowest va l ue . Roots and rhizome weights o f Juncus e f fusus and Sc i rpus americanus were lower than those o f o ther wetland spec i e s . Except i n Lo l ium perenne and Sc i rpus americanus, t o t a l belowground phytomass exceeded aboveground s tand ing phytomass i n a l l the spec ies examined (Table 4 .10 ) . The Lo l ium perenne stand had been grazed p r i o r to sampling wh i l e the shoots o f Sc i rpus americanus had been almost complete ly washed o f f by t i d e s . The r a t i o s of belowground to aboveground phytomass were i n the range o f 7:1 f o r a l l wet land spec ies except Juncus e f fusus and Typha l a t i f o l i a . Percentage es t imates of ' a v a i l a b l e ' carbohydrates i n belowground organs are g iven i n Tab le 4 .11 . These es t imates were g ene r a l l y h igher i n the upper than i n the lower s e c t i o n s . In not ing the r a the 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 tha t under our c o n d i t i o n s , t h i s spec ies i s caesp i t o se and remains v i r t u a l l y green i n w in te r growing main ly i n a rab l e o l d f i e l d s . In these r e spe c t s , Juncus e f fusus i s d i f f e r e n t from the o ther wet land spec ies examined. 4 .5 .3 D i s cuss i on Although l i v i n g and dead p l an t ma t e r i a l s cou ld not be separa ted , our data appear to support Ga l l a ghe r ' s (1974) obse rva t i on tha t below-ground phytomass o f wet land s i t e s o f t en comprises a very l a rge f r a c t i o n of the t o t a l phytomass. The belowground va lues recorded are a l s o g ene r a l l y much g rea te r than those repor ted f o r g r a s s l ands . Ovington ejt al_. (1963) repor ted 500 - 1200 g/m i n c en t r a l M innesota, Dahlman 72 Table 4.10 R a t i o of belowground to aboveground phytomass of s e l e c t e d species from Brunswick marsh, P i t t marsh and P i t t o l d f i e l d , November 1977. Lo c a t i o n Species Belowground phytomass g/0.25m2 Aboveground standing phytomass g/0.25m2 R a t i o of belowground to aboveground phytomass Brunswick marsh Scirpus americanus 860 Carex  l y n g b y e i Typha l a t i f o l i a 1273 1666 189 894 P i t t marsh Scirpus  cyperinus 1866 315 Carex s i t c h e n s i s 2110 294 Calamagrostis canadensis 1969 294 Juncus effusus 341 596 0.6 P i t t o l d f i e l d Lolium  perenne 302 < 1 73 Table 4.11 Percent of r e a d i l y h y d r o l y z a b l e carbohydrates (dry wt b a s i s ) i n belowground phytomass of s e l e c t e d species from Brunswick marsh, P i t t marsh and P i t t o l d f i e l d , November 1977. L o c a t i o n Species % R e a d i l y h y d r o l y z a b l e carbohydrates i n below-ground phytomass* 0 - 1 5 1 5 - 3 0 cm cm Brunswick marsh Scirpus americanus 14.1 12.2 !! 11 Carex l y n g b y e i 30.8 10.1 tl I I Typha l a t i f o l i a 25.8 18.3 P i t t marsh Scirpus cyperinus 24.3 14.3 I I Carex s i t c h e n s i s 26.2 13.8 I I Calamagrostis canadensis 20.3 13.1 I I Juncus effusus 18.6 19.2 P i t t o l d f i e l d Lolium perenne 13.9 - -* Values are averages of two samples 74 2 and Kucera (1965) repor ted 1400 - 1900 g/m i n M i s s o u r i , wh i l e 2 Wiegert and McGinnis (.1975) repor ted 278 - 525 g/m i n South C a r o l i n a . Our belowground va lues are somewhat h igher than those repor ted by Bernard and MacDonald (1974) f o r a f reshwater Carex r o s t r a t a wet land but lower than those g iven by Broome ejt al_. (1975) and de l a Cruz and Hackney (1977) f o r some s a l t marshes i n eas te rn Un i ted S t a t e s . These 2 workers repor ted belowground phytomass range of 7000 - 10000 g/m f o r the s a l t marshes they s t ud i e d . The lower va lues observed f o r Sc i rpus  americanus cou ld be a s soc i a t ed w i th s pe c i a l f ea tu res of the environment as i n the case o f Juncus e f f u s u s . Sc i rpus americanus i s found seawards from Carex lyngbye i and i n our s i t e the stands are sub jec t to f requent s i l t coverage. Our belowground/aboveground phytomass r a t i o s are between those g iven by McNaughton (1966) and T y l e r (1971) but are not as high as those g iven by W ie l go l a sk i (1972) f o r some a r c t i c communit ies. Much o f the p l an t ma t e r i a l s from the lower hor i zons of our cores appeared to be dead and low i n s torage t i s s u e which probably accounted f o r t h e i r low l e v e l s of hyd ro l yzab le carbohydrates . The s i g n i f i c a n c e of the high belowground phytomass recorded here appears to l i e i n the a b i l i t y o f many emergent spec ies to s t o re l a r ge energy reserves i n underground organs. Miss Kathy Kennedy (unpubl ished work) , a f e l l o w student a t the U n i v e r s i t y of B r i t i s h Columbia, examined the " food" reserves of a number of wet land spec ies on the eas t coas t o f Vancouver I s l and us ing cores and an e t i o l a t i o n technique (Marx 1963). She found up to 550 days were r equ i r ed to exhaust the belowground reserves o f wet land spec ies wh i l e those from a rab l e g rass lands were 75 exhausted i n on l y 30 days. I t may we l l be tha t wet land spec ies have evo lved a " s t r a t e g y " o f l a r ge energy storage belowground to meet the many environmental s t r e s se s to which they are f r equen t l y sub jec ted . The reserves may a l s o a i d i n e a r l y es tab l i shment a t the beginning o f the growing season (Mooney and B i l l i n g s 1960, Fonda and B l i s s 1966). 4.6 C a l o r i c Content of Some Emergent Spec ies I t appears t ha t s tand ing crop est imates should be supplemented w i th energy determinat ions so t ha t p r o d u c t i v i t y va lues can be con-v e n i e n t l y expressed i n these terms. Q u a n t i t a t i v e l y , energy i s important i n the o v e r a l l sub jec t o f ecosystem f u n c t i o n s . Whi le i t i s t r ue tha t ' a v a i l a b l e ' or ' d i g e s t i b l e ' energy i s more important i n t h i s r ega rd , knowledge of the gross energy i n s tand ing crops can be use fu l e s p e c i a l l y i n an exp l o r a t o r y study of the k ind repor ted i n t h i s t h e s i s . From numerous repor t s i n the l i t e r a t u r e , i t appears t ha 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 rge number of wet land and t e r r e s t r i a l p l an t communities i r r e s p e c t i v e o f s pe c i e s , s i t e or stage of ma tu r i t y (Boyd 1968, 1969a, 1970b; de l a Cruz 1975, Go l l e y 1961). Ana lyses of the energy va lues of some lower mainland communities were done to determine whether they conform to these e s t a b l i s h e d t r ends . 4.6.1 Ma t e r i a l s and methods C a l o r i c va lues were determined i n some ground samples us ing a Par r A d i a b a t i c Bomb Ca lo r imete r accord ing to methods desc r ibed i n Par r Techn ica l Manual No. 31. 4.6 .2 Observat ions and r e s u l t s 76 No major energy changes were recorded i n a l l the spec ies dur ing the two sampl ing dates (Table 4 . 12 ) . On the whole the c a l o r i c va lues f e l l w i t h i n a narrow range of 4.4 Kca l /g o f dry mat te r . Only very s l i g h t f l u c t u a t i o n s were recorded. Ca lamagrost i s canadens is , Juncus  e f fusus and Carex lyngbyei had h igher c a l o r i c va lues i n May compared to October. The reverse was t rue f o r Sc i rpus acu tus , Typha l a t i f o l i a and Dacty l i s g lomerata . Energy va lues f o r P h a l a r i s arundinacea and Sc i rpus cyper inus remained cons tan t . 4 .6 .3 D i s cuss i on In a l a rge number of macrophytes the gross energy l e v e l has been found to vary on ly s l i g h t l y w i th s p e c i e s , age or s i t e . For example, Boyd (1968) repor ted an average 4.3 Kcal/gm f o r va r i ous aqua t i c macro-phytes . De l a Cruz (1975) found the c a l o r i c content o f Spa r t i na  cynosuro ides and Sc i rpus americanus to range between 4.2 - 4.6 K c a l / g . Squ i res and Good (1974) gave a seasonal average o f 3.9 Kca l /g i n Spa r t i na a l term" f l o r a . The c a l o r i c va lues obta ined i n the study repor ted here compare we l l w i th those i n the l i t e r a t u r e f o r a lmost any k ind of p l an t m a t e r i a l , the general range being from 4.0 to 4.6 Kca l /g of dry mat te r . S ince there i s l i t t l e seasonal d i f f e r en ce in c a l o r i c v a l u e s , i t can be concluded tha t the c a l o r i c s tand ing crop i s merely a f un c t i on of dry matter p roduc t i on . Organisms u t i l i z i n g the wet land p l an t s as a food source consume an amount o f t o t a l energy tha t i s rough ly p ropo r t i ona l to the quan t i t y o f dry matter i n t a k e . 77 Table 4.12 Seasonal changes in energy content (Kcal/g) of the standing crop of some emergents from several locations, 1977. Location Species May October Pitt marsh Calamagrostis canadensis 4.6 * 4.4 ii ii Phalaris arundinacea 4.4 4.4 ii I I Scirpus acutus 4.4 4.7 I I it Scirpus cyperinus 4.5 4.5 ii ii Juncus effusus 4.6 4.2 Brunswick marsh Carex lyngbyei 4.5 4.4 I I I I Typha l a t i f o l i a 4.2 4.4 Alaksen old f i e l d Dactylis glomerata 4.3 4.4 Data are averages of two samples. 78 5. DISPOSITION OF EMERGENT VEGETATION As a r e s u l t o f the pho tosyn the t i c process i n which r ad i an t energy i s transformed i n t o chemical energy, the p l an t mate r i a l produced may occur as l i v i n g matter or as dead mat te r . The d i s p o s i t i o n i n the b i o -sphere of the phytomass thus formed may take severa l r ou t e s . Under na tu ra l c o n d i t i o n s , the major routes o f "return" commonly i d e n t i f i e d f o r communication purposes are: (1) the graz ing-brows ing r ou t e , (2) the accumulat ion r ou t e , and (3) the d e t r i t a l r ou t e . In g raz ing and browsing, predominant ly l i v i n g phytomass i s consumed, u sua l l y i n s i t u , by va r i ous k inds o f herb ivores rang ing from l a rge ungulates to very smal l i n v e r t e b r a t e s . Accumulat ion i nvo l ves i n co rpo ra t i on of dead phytomass i n t o the subs t ra te as l i g n i t e , c o a l , petro leum, 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 route o f t en commences w i th comminution or fragmen-t a t i o n o f dead phytomass by ene rge t i c processes such as t r amp l i n g , w ind, t i d a l a c t i v i t y and running water . During f ragmenta t i on , l a r ge p l a n t su r faces are exposed to the a c t i o n o f the wide a r r ay o f decomposer organisms. The p a r t i c u l a t e matter r e s u l t i n g from these processes may e i t h e r remain i n s i t u o r i t may be exported to other hab i t a t s by the same ene rge t i c f o r ces which b r i ng about f ragmenta t i on . No sharp d i v i s i o n s can be drawn between g r a z i n g , accumulat ion and d e t r i t a l systems. What c on s t i t u t e s dead t i s s u e i s a matter of con-t r ove r sy and death may come from "normal" p h y s i o l o g i c a l processes o r from other causes such as fungal i n f e c t i o n s . Despi te these amb i gu i t i e s , we cons idered i d e n t i f i c a t i o n o f the three routes of p l an t d i s p o s i t i o n r e l e van t to s tud i e s o f wet land processes . 79 5.1 Graz ing of Emergent Vegeta t ion Par t of the energy from emergent vege ta t i on would be expected to be channe l l ed through the c l a s s i c a l ' g r a z i n g ' food c ha i n . The supply o f food d i r e c t l y to animals g raz ing the l i v i n g p l an t t i s s u e s appear to vary i n importance from wet land to wet land as do the grazers themselves. Our f i n d i n g s , based l a r g e l y on obse r va t i on s , showed g raz i ng to be minimal on the Fraser d e l t a t i d a l marshes. Some o f the green shoots of Carex lyngbye i were s pa r i n g l y nipped by widgeon and other na t i ve geese. Much o f the g raz ing e s p e c i a l l y by waterfowl appeared to take p lace i n w i n t e r . Burgess (1970) and Burton (1977) repor ted s i m i l a r l o c a l heavy g raz ing of Sc i rpus americanus i n the w in te r months. Other her-b ivores rang ing from i n s e c t s to earthworms and shrimps were a l s o found i n the t i d a l marshes. Most of the spec ies observed were not i d e n t i f i e d and t h e i r r o l e s in the marshes have not been documented. D e s c r i p t i o n of the ve r t eb ra te and i n ve r t eb r a t e fauna of the F raser d e l t a marshes are c u r r e n t l y being assembled by the Canadian W i l d l i f e Se rv i ce (A l ak sen ) , Westwater Research Centre ( U n i v e r s i t y of 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 Vancouver) . Graz ing by lower and h igher animals a l s o appeared to be minimal i n the P i t t marsh. Numerous smal l animals were observed i n the marsh. Some po 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 rge numbers. Many r e s i den t and migrant b i r d s were f r e quen t l y s i gh ted i n the marsh a l though they appear to feed more on ne ighbour ing a g r i c u l t u r a l lands (Barnard 1975). In con tas t to the wetland s p e c i e s , marked g raz ing by wa te r f ow l , gastropods and i n s e c t s was noted i n p l an t s of the nearby a g r i c u l t u r a l o l d 80 f i e l d s . The pastures a t A laksen are p r i m a r i l y managed f o r waterfowl wh i l e those a t Colony Farm are f r e quen t l y grazed by d a i r y cows. 5.2 Accumulat ion of Emergent Vegeta t ion i n the Subst ra te Some re fe rence has a l ready been made under Sec t i on 4.4 to the accumulat ion of phytomass i n the s i t e s s t ud i e d . In the t i d a l marshes, e a r l y sp r i ng examinat ion showed tha t water movements over the p l an t cover had l ed to seemingly c a p r i c i o u s removal of dead p l an t m a t e r i a l . C lose to channe l s , the cover had been swept c l ean o f dead shoots wh i l e i n areas where storm and t i d a l a c t i on s were l e s s v igorous accumulat ion of dead fragements occu r red . Comminution, accumulat ion and export was obv i ous l y v a r i a b l e even over sho r t d i s t a n c e s . Examination o f the subs t ra te a long the channels showed some recogn i zab le roo t and shoot accumulat ions a l though again the d i s t r i b u t i o n and th i ckness of accumulat ion va r i e d g r e a t l y . In the P i t t marsh, examinat ion o f the s o i l p r o f i l e showed marked f i b r ou s peat accumulat ion i n the we t tes t zones. The d r i e r subs t ra tes c ons i s t ed main ly o f a l l u v i a l s i l t d e p o s i t s . Accumulat ion o f o rgan i c matter appears then to be c h a r a c t e r i s t i c o f both the f reshwater (F igure 5.1) and b rack i sh t i d a l marshes (F igure 5 .2 ) . Even at the Brunswick marsh where a s ub s t an t i a l p o r t i on of the l i t t e r i s exported by t i d a l a c t i o n , cons ide rab le organ ic matter accumulat ions are encountered i n some a reas . 81 F igure 5.1: Accumulat ion of Organic Mat ter i n the P i t t marsh (Summer 1976). Old Growth V i s i b l e on top; Accumulat ion i n Subs t ra te P r o f i l e over 1 m deep. 82 83 F igure 5.2: Accumulat ion of Organic Matter i n the Brunswick marsh. Top photo: overw intered l i v i n g " s p i k e s " and dead shoots o f Carex l y ngbye i ; most o f o.fn. has been washed away by w in te r storm and t i d e . Bottom photo: l o c a l i z e d accumulat ion o f Zostera mar i t ima , Carex l y ngbye i , e t c . , about 1 m deep. 85 5.3 Decomposit ion of Emergent Vegeta t i on In many s t ab l e or steady s t a t e ecosystems such as those i n many g ras s l ands , the phytomass produced i n a season u sua l l y undergoes more or l e s s complete degradat ion through o x i d a t i o n , f i r e and/or g r a z i n g . In wet land systems oppor tun i t y f o r degradat ion by these processes i s o f t en so markedly reduced tha t phytomass i n va r i ous s t a t e s o f accumulat ion i s encountered. Some of the phytomass undergoes deg-rada t i on or breakdown to p a r t i c u l a t e forms t ha t can be termed d e t r i t u s . Odum and de l a Cruz (1963) de f i ned the term d e t r i t u s as dead p a r t i c u l a t e o rgan i c matter p lus i t s a s soc i a t ed m i c r o f l o r a and fauna. The degradat ion (or decomposit ion or decay) o f p l an t ma te r i a l to p a r t i c u l a t e forms i s a complex, cont inuous process i n v o l v i n g numerous b i o t i c and a b i o t i c events which can be approached i n many d i f f e r e n t ways. We cons idered ra te and l o c a t i o n o f the decomposi t ion process to be important v a r i a b l e s i n c h a r a c t e r i z i n g wet land s i t e s . We employed two techniques i n our i n v e s t i g a t i o n s : (1) the ' l i t t e r bag' technique (Kormondy 1968), and (2) the i n v i t r o o rgan i c matter l o s s technique (Burkho lder and Bornside 1957). 5.3.1 Decomposit ion s tud i e s us ing l i t t e r bags Decomposit ion s tud i e s have been examined i n a number of e n v i r o n -ments i n c l u d i ng 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 Gabr i e l 1974) and stream (Boyd 1970a) us ing 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 tha t changes i n weight of the decomposing p l an t s i n l i t t e r bags would be s i m i l a r to changes i n these ma t e r i a l s ou t s i de the bags. 5.3.1.1 Ma t e r i a l s and methods F i e l d decomposit ion of p l an t ma te r i a l was determined by means of the ' l i t t e r bag 1 method f r e quen t l y employed i n t h i s type of s tudy. Samples o f P h a l a r i s a rund inacea, Carex s i t c h e n s i s , Sc i rpus acu tus , Juncus e f fusus ( a l l from P i t t marsh); Carex lyngbye i (from Brunswick marsh); and Dacty l i s glomerata (from A laksen) were harvested and chopped i n t o approx imate ly 7 cm segments on 9 August , 1977. Natura l decomposit ion o f cu r ren t y e a r ' s s tand ing crop g ene r a l l y proceeds a t an app rec i ab l e r a t e from the beginn ing o f autumn when most shoots d i e . The ma 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 stage of ma tu r i t y and hence presumed to be p h y s i o l o g i c a l l y dead or c l o se to death ready to go through the decomposit ion phase. Known weights o f shoot ma te r i a l were enc losed i n 15 x 20 cm nylon bags w i th 3 mm mesh. The bags were i d e n t i f i e d us ing p l a s t i c l a b e l s . The bags (24 f o r each spec i e s ) were grouped i n t o th ree ; one group to be taken to Brunswick marsh, another to A laksen and the f i n a l group to P i t t marsh. On 10 August, 1977, they were taken to these three l o c a t i o n s and l o o s e l y p laced on the sur face of the s ub s t r a t e . Two bags per spec ies 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 October, 1977). A s i m i l a r c o l l e c t i o n was made on 5 January, 1978 ( a f t e r 148 days) and the experiment was terminated on 1 June, 1978 ( a f t e r 294 days) . 87 In the l a b o r a t o r y , the bags were opened and the samples c leaned o f sand. V i s i b l e i n s e c t s and o ther i n ve r t eb r a t e s were a l s o removed. The samples were d r i ed to constant we igh t , weighed and ashed. Weight losses due to l e a c h i n g , f ragmentat ion by m i c r ob i a l a c t i v i t y , escape o f p a r t i c l e s from the bags, e t c . , were i n t e r p r e t e d as decomposit ion r a t e s . To assess the magnitude o f decomposit ion ra tes below the subs t r a t e s u r f a c e , another exper iment was c a r r i e d out on dead vege t a t i on . The exper iment i n vo l ved three spec i e s : P ha l a r i s a rund inacea, Carex lyngbye i and Dacty l i s g lomerata. The samples were ha rves ted , t r ea ted as desc r ibed above, taken to the three l o c a t i o n s and bu r i ed approx imate ly 15 cm deep i n the subs t r a t e on 24 October, 1977. Ha l f o f the bags (two f o r each spec i e s ) were r e t r i e v e d a f t e r 73 days (5 January , 1978) and the r e s t were c o l l e c t e d on 1 June, 1978 ( a f t e r 146 days ) . 5 .3 .1 .2 Observat ions and r e s u l t s Resu l t s of decomposit ion i n l i t t e r bags are g iven i n Appendices I and I I I . Analyses o f var iance are presented i n Appendices I I and IV. The f i r s t 74 days o f i n s i t u su r face decomposit ion w i tnessed a r ap i d l o s s o f o rgan i c mat ter by a l l the spec ies s tud i ed (F igure 5 . 3 ) . The loss was s l i g h t a f t e r t h i s pe r iod u n t i l 5 January , 1978 (148 days) when i t s t a r t e d to inc rease aga i n . The percentages o f o rgan i c matter decomposed to October and to January were s i m i l a r averag ing 24.4% and 26.5% r e s p e c t i v e l y but by 1 June, 1978 up to 54.1% o f the o r i g i n a l o rgan i c mat ter had decomposed (Table 5 . 1 ) . 88 Table 5.1 Summary of the Main E f f e c t s of L i t t e r Bag Decomposition, Where Bags were Placed on the Substrate Surface. Main E f f e c t % organic matter decomposed Time 74 day decomposition 148 day decomposition 294 day decomposition 24.4 a* 26.5 a 54.1 b Lo c a t i o n Brunswick marsh P i t t marsh Alaksen o l d f i e l d 36.1 a 34.2 a 34.7 a Species Carex s i t c h e n s i s  Juncus effusus  Scirpus acutus  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 20.7 a 31.5 b 32.7 b 33.4 b 39.4 c 52.4 d * f o r each main e f f e c t , means fo l l o w e d by the same l e t t e r s are 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 observations on that e f f e c t i r r e s p e c t i v e of the other f a c t o r s . Decomposit ion i n L i t t e r Bags P laced on the Subs t ra te Sur face . Carex s i t c h e n s i s O-O Sc i rpus acutus Q - a P ha l a r i s arundinacea m—m Juncus e f fusus  Carex lyngbye i  Dacty l i s glomerata 91 The amount of o rgan i c matter decomposed va r i e d w i th spec i e s . The lowest va lues were recorded f o r the spec ies from P i t t marsh f o l l owed by Carex lyngbye i (Brunswick marsh) and Dacty l i s glomerata (A laksen o l d f i e l d ) . Dacty l i s g lomerata l o s t 50% of i t s o r i g i n a l weight i n about 187 days wh i l e Carex lyngbye i shoots took 234 days to l o se t h i s amount (F igure 5 .3 ) . By the end of the exper imenta l pe r iod (1 June, 1978) most o f the shoots were devoid of leaves and dry weight l o sses had reached va lues as h igh as 83.3%. Appendix II shows tha t there were s i g n i f i c a n t i n t e r a c t i o n s (P < 0.01) i n terms o f t ime x l o c a t i o n and t ime x s pe c i e s . The changes i n o rgan i c matter l o s ses w i th time f o r bur ied samples p a r a l l e l e d those p laced a t the s o i l su r face (Table 5 . 2 ) . However by comparing Tables 5.1 and 5.2, th ree major d i f f e r en c e s i n the pa t te rns o f weight l o s s were d i s c e rned . F i r s t l y , the abso lu te decomposit ion l o sses were much l e s s i n bur ied samples compared to those p laced on the s o i l s u r f a c e . Second ly , wh i l e decomposit ion ra tes of samples p laced on the s o i l su r face d i d not vary w i th s i t e s , bu r i ed samples decomposed much f a s t e r a t A laksen o l d f i e l d s i t e than those a t P i t t marsh and Brunswick marsh s i t e s . F i n a l l y , the amount of o rgan i c matter decomposed va r i ed w i th spec ies f o r sur face samples but the pa t t e rn was s i m i l a r f o r bur ied samples i r r e s p e c t i v e of s pe c i e s . 5 .3 .1 .3 D i s cuss i on I t has been repor ted tha t i n l i t t e r bag s t u d i e s , s i g n i f i c a n t l o sses may occur as p l an t fragments escape through the bags (Kormondy 1968). The i n i t i a l r ap i d l o s s of o rgan i c matter repor ted i n these 92 Table 5.2 Summary of the Main E f f e c t s of L i t t e r Bag St u d i e s , Where Bags were Placed 15 cm below the Surface. % organic matter Main E f f e c t decomposed  Time 73 day decomposition 9.3 a* 146 day decomposition 21.9 b L o c a t i o n Brunswick marsh 12.1 a P i t t marsh 9.7a Alaksen o l d f i e l d 24.9 b Species 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 followed by the same l e t t e r are not 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 of a l l observations on that e f f e c t i r r e s p e c t i v e of the other f a c t o r s . 93 s tud i e s can the re fo re be a t t r i b u t e d both to decomposit ion as we l l as p a r t i c l e l o s s from the bags. Ignor ing po s s i b l e p a r t i c l e l o sses through the bags, the i n i t i a l h igh s o l u b i l i z a t i o n l o sses i n d i c a t e a high r a t e of d i s s o l v ed o rgan i c matter product ion by the p l an t s pe c i e s . The major d i f f e r en c e s i n decomposit ion losses 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 environmental and p l an t c h a r a c t e r i s t i c s . Among the environmental f a c t o r s , temperature appeared to p lay a s i g n i f i c a n t r o l e . The seasonal t rends i n decomposi t ion ra tes were c o r r e l a t e d w i th changes i n ambient temperature. Decomposit ion took p lace s l ow l y dur ing the c o l d w in te r i n c r ea s i ng w i th the advent o f s p r i n g . By June the leaves had complete ly d i s i n t e g r a t e d l eav i ng behind hard stems tha t resembled o l d growth from the preceding yea r . Lower s o i l temperatures were a l s o p a r t l y r e spons i b l e f o r the lower decomposit ion l o sses recorded i n bur ied bags compared to those p laced on the sub-s t r a t e su r f a ce . The lower decomposit ion r a te s recorded f o r bur i ed samples can a l s o be a t t r i b u t e d to o ther f a c t o r s . Sur face samples tend to be more a c c e s s i b l e to d e t r i t o vo r e s than bur ied ones. Furthermore, the sur face l a ye r of the subs t r a t e o f ten undergoes more ae rob i c r e s p i r a t i o n and f e rmen ta t i on . Below the su r f a ce , the l a r g e l y anaerob ic decomposit ion i s much s lower and i s c a r r i e d out by the " l e s s e f f i c i e n t " o b l i g a t e and f a c u l t a t i v e anaerobes. For sur face samples, no s i g n i f -i c an t d i f f e r en c e was found i n decomposit ion l o s ses a t the three hab i t a t s a l though the va lues were s l i g h t l y h igher i n Brunswick marsh than i n the P i t t marsh and A laksen o l d f i e l d (Table 5 .1 ) . The s l i g h t l y lower r a te s a t the A laksen o l d f i e l d cou ld be r e l a t e d to moisture d e f i c i e n c y 94 i n the d ry land wh i l e the lower r a te s a t the P i t t marsh may be a t t r i b u t e d to the co l d o l i g o t r o p h i c nature of the marsh. The above f i n d i n g s show t ha t temperature, mois ture and oxygen a v a i l a b i l i t y are the main environmental f a c t o r s i n f l u e n c i n g decom-p o s i t i o n r a te s i n the wetlands of south western B r i t i s h Columbia. In general p l an t ma t e r i a l s exposed to warm mois t and ae rob i c con-d i t i o n s decompose more r a p i d l y than those subjec ted to cond i t i on s which are c o l d , anaerob ic and d ry . T i da l a c t i o n a l s o inc reases degradat ion r a t e s . In a d d i t i o n to d i f f e r en ce s which occur red due to environment, some of the observed v a r i a t i o n i n decomposit ion l osses cou ld be a t t r i b u t e d to innate spec ies d i f f e r e n c e s . Woody p l an t s decompose more s l ow l y than herbaceous, and the more succu len t herbaceous spec ies f a s t e r than the more f i b r o u s . Godshak and Wetzel (1978) repor ted a high negat ive c o r r e l a t i o n between decay ra tes and t o t a l f i b r e content i n f i v e spec ies o f aqua t i c macrophytes. Moody (1978) observed a r ap i d l o s s o f f l e s h y par t s o f S a l i c o r n i a mari t imus and T r i g l o c h l i n  mar i t ima i n the F raser d e l t a t i d a l marshes. Percentage l osses from l i t t e r bags a f t e r 103 days were 46, 52, 85 and 92 f o r Carex l y ngbye i , Sc i rpus mar i t ima , S a l i c o r n i a mar i t imus and T r i g l o c h l i n mar i t ima r e s p e c t i v e l y . These d i f f e r en ce s were due no doubt to v a r i a t i o n s i n chemical compos i t ion of the spec ies Moody s t u d i e d . Decomposit ion d i f f e r en ce s repor ted i n our s tud i e s cou ld s i m i l a r l y be a t t r i b u t e d to spec ies 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 tha t the leaves had complete ly d i s i n t e g r a t e d by June l e av i ng behind on ly hard stems. Apparent l y the r e l a t i v e l y s o f t leaves w i th low 95 f i b r e content succumbed f i r s t to decomposit ion processes wh i l e the h i gh l y f i b r ou s stems f o l l owed much l a t e r . P i t t marsh spec ies gene ra l l y took longer to decompose presumably because of t h e i r h igh f i b r e con ten t . The above spec ies d i f f e r en ce s were noted i n sur face samples but not i n bur ied ones (Table 5 .2 ) . Th is may be a f un c t i on of s c a l e s i n ce much l e s s decomposit ion occurred i n the bur ied bags. I t would appear t ha t under wet land c o n d i t i o n s , p a r t l y undecomposed p l an t ma te r i a l o v e r l a i n by dead vege ta t i on from subsequent years degrades a t a very slow r a t e i r r e s p e c t i v e o f spec ies wh i l e sur face ma t e r i a l s degrade a t r a t e s dependent on spec ies and environmental c o n d i t i o n s . 5.3.2 In v i t r o decomposit ion of emergent vege ta t i on In e a r l i e r s e c t i o n s , i t was noted tha t p l an t ma t e r i a l s from wetlands may, as they are produced or a f t e r they are produced, be a l t e r e d f o l l o w i n g one or a l l pathways o f t en c l a s s i f i e d broad ly as accumula t ion , 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 po inted out t h a t , to va ry ing degrees, processes o f comminution and b i o t i c a c t i v i t y may be very i n v o l v ed . Much can be and has been learned from f i e l d obse rva t i on o f these processes . S tandard ized i n v i t r o s tud i e s may a l s o prov ide usefu l i n f o rmat i on a l though the use o f the indoor l abo ra t o r y i s not w i thout i t s aspects o f a r t i f i c i a l i t y and t ime c o n s t r a i n t s . Almost end less s o p h i s t i c a t i o n can be envisaged i n p o s s i b l e l abo ra t o r y s tud ies of the degradat ion of wet land v ege t a t i o n . We chose a s imple technique developed l a r g e l y by Burkholder and 96 Borns ide (1957) which seemed to meet the quasi survey nature of our i n v e s t i g a t i o n s . 5.3.2.1 Ma t e r i a l s and methods Overwintered ma te 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 pu l ve r i z ed i n a Wi ley m i l l . 1.5 g of p l an t ma te r i a l were p laced i n each of a s e r i e s of 125 ml f l a s k s . One se t o f samples were incubated w i th 70 ml o f inoculum from P i t t marsh and the o ther se t w i th 70 ml of inoculum from Brunswick marsh. The inoculum was prepared by f i l t e r i n g a suspension o f marsh mud i n the surrounding water . 5 ml a l i q u o t s o f "Hyso l " (10 mg/ml), a "complete" 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 on t a i n i ng each inoculum source and 5 ml d i s t i l l e d water to the o ther h a l f . Con t ro l s were a l s o prepared by i ncuba t ing s t e r i l i z e d P h a l a r i s  arundinacea samples w i th the inoculum. The c on t r o l s were used to demonstrate the ex tent of s o l u b i l i z a t i o n l o s ses i n the absence of m i c r ob i a l a c t i v i t y . A l l t reatments conta ined two r e p l i c a t i o n s . The f l a s k s were p laced on a mechanical shaker , aerated o c c a s i o n a l l y and incubated a t 25° C i n the dark to prevent pho tosyn thes i s . A f t e r 21 days of i ncuba t i on one se t of f l a s k s was removed, f i l t e r e d and the res idue t r a n s f e r r e d to ta red c r u c i b l e s . They were then oven d r i e d , weighed and ashed at 550°C. The o ther set of samples was t r ea ted s i m i l a r l y a f t e r 42 days. Decomposit ion l o sses a f t e r 21 and 42 days are presented on percentage o rgan i c matter b a s i s . 97 In May, 1978, young vege ta t i v e shoots were c o l l e c t e d , d r i e d and ground. The ground samples were t r ea t ed i n e x a c t l y the same way as the overw intered m a t e r i a l s . 5 .3.2.2 Observat ions and r e s u l t s Data from the i n v i t r o decomposi t ion s tud i e s are presented i n Tables 5.3 and 5.4 and Appendices V to V I I . In both overwintered and young shoots , the main treatment 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) (Tables 5.3 and 5.4) r e s p e c t i v e l y . There were a l s o many s i g n i f i c a n t i n t e r a c t i o n s 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 rgan i c matter l o s s a f t e r 42 days was h igher than the amount l o s t i n 21 days of i n c uba t i o n . F igure 5.4 i n d i c a t e s t ha t l o s s i n o rgan i c matter was r ap i d dur ing the f i r s t 21 days a f t e r which f u r t h e r decomposit ion took p lace a t a r e l a t i v e l y s lower r a t e . Decomposit ion proceeded at a f a s t e r r a te w i th P i t t marsh inoculum than w i th Brunswick marsh inocu lum. The a d d i t i o n o f Hysol to both sources o f inoculum inc reased the percentage o f o rgan i c matter decomposed. The lowest o rgan i c matter l o sses were recorded i n the s t e r i l e c o n t r o l s . 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  arundinacea had the lowest decomposit ion va lues wh i l e Carex lyngbye i had the h ighes t and Dacty l i s g lomerata was i n t e rmed ia te . A major d i f f e r en c e i n the pa t t e rn of decomposit ion between young and overwintered ma te r i a l s was the extremely high va lues repor ted f o r the former compared w i th the l a t t e r . 98 Table 5.3 Summary of the Main E f f e c t s of In V i t r o S t u d i e s ; Overwintered shoots. Main E f f e c t % organic matter decomposed  Time 21 day decomposition 42 day decomposition 13.6 a 18.6 b Source of inoculum A d d i t i v e Brunswick marsh P i t t marsh No Hysol Hysol 15.3 a 16.9 b 15.5 a 16.8 b Species C o n t r o l ( s t e r i l e ) P h a l a r i s arundinacea  Carex s i t c h e n s i s  D a c t y l i s 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 followed by the same l e t t e r are 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 observations on that e f f e c t i r r e s p e c t i v e of the other f a c t o r s . 99 Table 5.4 Summary of the Main E f f e c t s of In V i t r o Studies; Young Shoots. Main E f f e c t % organic matter decomposed  Time 21 day decomposition 42 day decomposition 54.4 a* 58.1 b Source of inoculum A d d i t i v e Brunswick marsh P i t t marsh No Hysol Hysol 55.6 a 56.9 b 54.4 a 57.0 b Species C o n t r o l ( s t e r i l e ) Carex s i t c h e n s i s  P h a l a r i s arundinacea  D a c t y l i s glomerata  Carex l y n g b y e i 29.9 a 49.6 b 63.4 c 67.8 d 70.4 e * f o r each main e f f e c t , means fo l l o w e d by the same l e t t e r are 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 observations on that e f f e c t i r r e s p e c t i v e of the other f a c t o r s . 100 F igure 5.4: In V i t r o Decomposit ion o f Overwintered and Young Shoots . O^O Contro l ( S t e r i l i z e d ) Carex s i t c h e n s i s o - a Pha l a r i s arundinacea  Carex lyngbyei  Dacty l i s glomerata y o u n g s h o o t s 21 42 0 T i m e e l a p s e d ( d a y s ) 102 5 .3 .2 .3 D i s cuss i on Loss o f o rgan i c matter i n the shaking f l a s k s probably takes p lace through d i f f u s i o n o f metabo l i c products such as C0 2 and Nh^. Changes i n percentage o rgan i c matter decomposed under l abo ra t o r y cond i t i ons p a r a l l e l e d those i n the f i e l d s . The trends were s i m i l a r to those repor ted by Burkholder and Borns ide (1957). The high i n i t i a l l o sses cou ld be a t t r i b u t e d main ly to d i s s o l u t i o n of s o l ub l e p l an t f r a c t i o n s s i n ce even i n the absence of m i c r ob i a l a c t i v i t y ( s t e r i l i z e d samples) the magnitude of o rgan i c l o s s was r e l a t i v e l y h i g h , averag ing about 10% i n overwintered ma t e r i a l s and 30% i n young shoots . A l though d i f f e r en c e s are bound to occur between i n v i t r o and f i e l d obse rva t i ons , c e r t a i n aspects of decomposit ion i n nature can be exp la ined through l abo ra t o r y s t u d i e s . The extent of decomposit ion tha t a p l an t undergoes i nvo l ves a number of f a c t o r s i n c l u d i n g the time cons ide red , temperature, the nature of the decomposer organisms, the a v a i l a b i l i t y of n u t r i e n t s and the presence of na tura l i n h i b i t o r s i n the medium. In our s t u d i e s , p l an t samples t r ea t ed w i th P i t t marsh inoculum degraded f a s t e r than those t r ea t ed w i th Brunswick marsh inoculum a l though a c t i v i t y d i f f e r en ce s were not g reat (Tables 5.3 and 5 .4 ) . M i c r ob i a l a c t i v i t y would appear to p lay 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 raser b rack i sh marshes. The tendency f o r somewhat h igher decomposit ion ra tes a t the Brunswick marsh would then be r e l a t e d more to t i d a l a c t i on than to m i c r ob i a l degradat ion . The add i t i o n of Hysol s i g n i f i c a n t l y inc reased decomposit ion r a t e i n both young and overwintered shoots (Tables 5.3 and 5 .4 ) . Th is 103 inc rease 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 no rgan i c n u t r i e n t s supp l i ed i n Hyso l . The Hysol used had the f o l l ow i n g compos i t ion: 20%N, 20%P, 20%K, 0.04%Mn, 0.03%Fe, 0.002%Cu, O.OOUMb and 0.04%B. In na tu re , the i no rgan i c requirements of the microbes are probably supp l i ed by nu t r i e n t s i n the mud and surrounding water r a t he r than from dead undecomposed vege t a t i on . Young shoots would be expected to have high p r o t e i n content and t h e i r p o s i t i v e response to Hysol i n d i c a t e s t ha t n i t r ogen was not the f a c t o r l i m i t i n g decomposi t ion i n the f l a s k s . I t i s p o s s i b l e tha t any o r a l l o f the t r ace elements p lus the o ther macronut r ients cou ld have accounted f o r t h i s response. V a r i a t i o n i n spec ies decomposit ion i n the f l a s k s was s i m i l a r to t ha t i n the f i e l d , Carex lyngbye i degrading the f a s t e s t wh i l e the P i t t marsh spec ies degraded the l e a s t . Such v a r i a t i o n s can be a t t r i b u t e d main ly to d i f f e r en c e s i n s t r u c t u r a l compos i t i on . Indeed the importance o f the s t r u c t u r a l components i n t h i s regard i s i l l u s t r a t e d by the much h igher decomposit ion r a te s repor ted f o r the young l ow - f i b r e shoots . 104 6. PLANT FACTORS LIMITING DEGRADATION OF EMERGENT VEGETATION Much of the examinat ion of the wet land vege ta t i on to t h i s po in t r e l a t e s to gross processes o f dry matter p roduc t i on , i . e . how much dry matter i s produced, when i t i s produced, where i t goes and under what environmental c o n d i t i o n s . In an e a r l i e r s e c t i on i t was shown tha 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 wet land spec ies s tud i ed are s l i g h t . These observa t ions support those o f Boyd (1968, 1969a, 1970b) tha t l i v i n g o r dead p l an t ma te r i a l 'moving' i n t o g r a z i ng , d e t r i t a l or accumulat ion pathways have about the same c a l o r i c va lues r ega rd l e ss o f s p e c i e s , stage o f ma tu r i t y or ' d i g e s t -i b i l i t y ' . Bes ides h ab 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 to be a matter o f chemis t ry and phys ics of the p l an t r a t he r than i t s t o t a l c a l o r i c con ten t . S ince most p r o t e i n s , sugars , s ta rches and l i p i d s are r e a d i l y degradab le , the f i b r ou s components o f p l an t c e l l w a l l s would seem to p lay a more important 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 evo lved through geo log i ca l t ime and appear to p ro tec t l i v i n g p l an t s from the phys i ca l elements o f the s o i l and c l ima te and from b i o l o g i c a l elements such as herb ivores and decomposers. Even i n dead p l an t ma t e r i a l s these p r o t e c t i v e mechanisms may cont inue to e xe r c i s e an i n f l u ence on the routes taken i n degrada t i on . Some o f the p r o t e c t i v e chemical and phys i ca l elements developed by p l an t s have been we l l de l i nea ted i n mesic and x e r i c environments but compara t ive ly l i t t l e a t t e n t i o n has been accorded these mechanisms i n p l an t s o f wet land h a b i t a t s . Th is s e c t i on i s devoted p r i m a r i l y to 105 the examinat ion of some of these mechanisms i n r e l a t i o n to the emergent p l an t communities o f mar i t ime south western B r i t i s h Columbia. 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 convent iona l proximate scheme o f a n a l y s i s because o f the l a t t e r ' s l i m i t a t i o n s e s p e c i a l l y i n e c o l o g i c a l s t u d i e s . The proximate scheme was o r i g i n a l l y developed on the premise tha t crude f i b r e represented the i n d i g e s t i b l e po r t i on wh i l e the n i t r ogen f r e e e x t r a c t represented the d i g e s t i b l e carbohydrate po r t i on o f the p l a n t . That t h i s premise i s not always t rue was recogn ized severa l years ago. In a dd i t i o n to the f a c t t ha t 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 ogen f r e e e x t r a c t (Crampton and Maynard 1938), a cons ide rab le pa r t of the i n d i g e s t i b l e l i g n i n i s o f t en found i n the n i t r ogen f r e e e x t r a c t which i s supposed to represent a v a i l a b l e carbohydrates (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 ogen f r ee e x t r a c t has been preserved l a r g e l y f o r data comparisons and because crude f i b r e i s o f t en c o r r e l a t e d nega t i v e l y w i th n u t r i t i v e va l ue . The development of p l an t c e l l wa l l f r a c t i o n a t i o n procedures (Van Soest 1963, Van Soest and Wine 1967) was an attempt to overcome the i n c o n s i s t e n c i e s i n the proximate scheme o f a n a l y s i s . The Van Soes t 1 s procedures, which we adopted, d i v i d e p l an t dry matter i n t o two p a r t s : c e l l c on ten t s , l a r g e l y s o l ub l e ca rbohydra tes , p r o t e i n s , o rgan i c ac ids and l i p i d s , are almost complete ly degradable ( J a r r i g e 1965, Van Soest and Moore 1965) wh i l e the c e l l wa l l d e g r a d a b i l i t y i s v a r i a b l e depending on the ex tent of l i g n i f i c a t i o n , s i1 i f i c a t i o n , e t c . Some o f the p l an t phys i ca l f a c t o r s l i k e l y to a f f e c t degradat ion pa t te rns were a l s o examined e s p e c i a l l y w i th re fe rence to the deve lop-ment and d i s t r i b u t i o n of l i g n i f i e d t i s s u e s and the nature of the c u t i c u l a r s u r f a c e s . 106 6.1 Neutra l and Ac i d Detergent F i b re 6.1.1 Ma t e r i a l s and methods C e l l wa l l c on s t i t u en t s were ana lyzed as f i b r e i n s o l u b l e i n neu t ra 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 detergent s o l u t i o n (Goering and Van Soest 1970). Neutra l detergent f i b r e (NDF) c on s i s t s l a r g e l y o f c e l l u l o s e , hem i ce l l u l o se and l i g n i n wh i l e l i g n i n and c e l l u l o s e are combined i n a c i d detergent f i b r e (ADF) (Van Soest 1963). 6.1.2 Resu l t s Despi te the l a rge 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 g ene r a l l y inc reased as the season progressed (Tables 6.1 and 6.2 and F igure 6 .1 ) . In 1976, the lowest NDF va lue was 44.6% f o r Lo l ium perenne c o l l e c t e d i n May and the h ighes t was 76.1% f o r Festuca arundinacea harvested i n September. Lo l ium perenne i s a good q u a l i t y pasture spec ies whereas Festuca arundinacea i s a very coarse grass found main ly i n the f r i n g e s of the dykes. A s ub s t an t i a l i nc rease i n NDF was recorded i n the w in te r months (Table 6 . 2 ) . Changes i n ADF fo l l owed s i m i l a r t rends as f o r NDF w i th May samples having lower va lues than those c o l l e c t e d towards the end o f the growing season (Tables 6.3 and 6 . 4 ) . Overwintered p l an t ma t e r i a l s had the h ighes t ADF content . Carex lyngbye i and Juncus e f fusus gene ra l l y had lower ADF percentages compared to the o ther spec ies examined. Juncus e f fusus o f t en remains p a r t l y green dur ing w i n t e r . The low ADF va lues f o r Carex lyngbye i cou ld be an inherent c ha r a c t e r -i s t i c o f t h i s s pe c i e s . 107 Table 6.1 Seasonal Changes i n N e u t r a l Detergent F i b r e (as % Dry M a t t e r ) , Summer 1976. L o c a t i o n Species May J u l y Sept. P i t t marsh Calamagrostis canadensis 62.7* 65.5 69.0 I I I I 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 I I I I Festuca arundinacea 62.1 72.3 76.1 Alaksen o l d f i e l d Lolium perenne 44.6 53.7 68.7 * Values are averages of two samples. 108 F igure 6 .1: Seasonal Changes i n NDF. CKO Ca lamagrost i s canadensis ( P i t t ) * Carex s i t c h e n s i s ( P i t t ) />r-A Carex lyngbye i (Brunswick) O O Festuca arundinacea (Brunswick) Lo l ium perenne (Alaksen) M O N T H S no Table 6.2 Seasonal Changes i n N e u t r a l Detergent F i b r e (as % Dry M a t t e r ) , Winter 1977 - 1978. Lo c a t i o n Species 19 Oct./77 4 Mar./78 P i t t marsh Calamagrostis canadensis 73.0* 77.0 I I I I P h a l a r i s arundinacea 70.1 80.4 it I I Carex s i t c h e n s i s 69.7 75.9 I I I I Scirpus cyperinus 70.7 84.5 I I I I Scirpus acutus 73.6 81.8 I I I I Juncus effusus 75.7 74.9 Brunswick marsh Carex l y n g b y e i 67.9 84.9 it I I Typha l a t i f o l i a 70.9 82.1 Alaksen o l d f i e l d D a c t y l i s glomerata 71.0 80.0 * Values are averages of two samples. I l l Table 6.3 Seasonal Changes i n A c i d Detergent F i b r e (as % Dry M a t t e r ) , Summer 1976. L o c a t i o n Species May J u l y Sept P i t t marsh Calamagrostis canadensis 39.0* 41.2 43.3 Brunswick marsh Carex l y n g b y e i 28.9 31.8 34.9 it I I Festuca arundinacea 38.5 43.9 51.2 Alaksen o l d f i e l d Lolium perenne (+ Agropyron repens) 28.3 38.4 47.2 * Values are averages of two samples. 112 Table 6.4 Seasonal Changes i n A c i d Detergent F i b r e (as % Dry M a t t e r ) , 1977, 1978. 14 May 19 Oct. 4 Mar. L o c a t i o n Species 1977 1977 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 M Scirpus acutus 33.8 48.4 51.1 Juncus effusus 26.5 36.2 39.0 Brunswick marsh Carex l y n g b y e i 27.8 35.3 43.1 I I I I Typha l a t i f o l i a 30.2 46.1 53.3 Alaksen o l d f i e l d D a c t y l i s glomerata 34.1 41.8 51.0 * Values are averages of two samples. 113 6 .1 .3 D i scuss ion Due to inadequate number o f samples, no s t a t i s t i c a l a na l y s i s was done. However, the data presented showed a d i s t i n c t t rend o f i n c r e a s i n g NDF and ADF as the season p rogressed . The i n c rease was e s p e c i a l l y notab le i n the f a l l and w i n t e r months. S ince the shoots were dead and the re fo re metabol-i c a l l y i n a c t i v e , t h i s f a l l i n c rease was probably l i n k e d to a decrease i n o the r more s o l ub l e components r a t he r than an ac tua l i n c r e a s e . S i g n i f i c a n t l o s s o f s o l ub l e ma te r i a l s may occur through l each ing and decomposit ion i n 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 neu t r a l and a c i d detergent f i b r e s l i e s i n t h e i r degradab i l i t y by hern ivores and d e t r i t o v o r e s . The r e s u l t s repor ted here show tha t the ra te and ex ten t o f degradat ion o f the p l an t ma te r i a l s would vary w i th s p e c i e s . For example, Carex l y n g b y e i , whole o r p a r t s , w i th lower NDF and ADF va lues would be degraded f a s t e r than the more f i b r ou s Festuca  arund inacea. 6.2 L i gn i n L i g n i n probab ly p lays seve ra l r o l e s i n p l a n t t i s s u e s . I t i s p o s s i b l e t ha t i t may have evo lved as a d e t o x i f i c a t i o n product thus o f f e r i n g s u r v i v a l va lue to p l an t s (Neish 1960). L i gn i n p lays a major r o l e g i v i n g s t reng th and r i g i d i t y to the p l a n t (Fahn 1967) and i s e s s e n t i a l f o r development of e r e c t t e r r e s t r i a l p l an t s (Neish 1965). Blum (1968) showed l i g n i f i c a t i o n to be a s soc i a t ed w i th i n s e c t r e s i s t an ce i n sorghums. L i gn i n i s h i g h l y r e s i s t a n t to decomposit ion 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 of carboyhdrates i n the p l a n t c e l l wa l l 114 to rumen microbes. Of a l l the p l an t compounds tha t can be r e a d i l y measured by chemical means, l i g n i n appears to g i ve the best c o r r e l a t i o n w i th d i g e s t i b i l i t y (Har t l ey and Jones 1976). I t i s g ene r a l l y be l i eved tha t the a b i l i t y of c e r t a i n p l an t s to r e s i s t d i g e s t i o n and decomposit ion may not on ly be r e l a t e d to t o t a l l i g n i n content but a l s o to the p o s i t i o n and ex tent of the l i g n i f i e d t i s s u e s , a f ea tu re which i s not r e a d i l y perce ived i n o rd i na ry chemical a n a l y s i s . A c co r d i ng l y , l i g n i n was examined not on ly 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 s tud ies of i t s d i s t r i b u t i o n w i t h i n d i f f e r e n t p l an t t i s s u e s . 6.2.1 Ma t e r i a l s and methods Tota l l i g n i n content was determined by the permanganate o x i d a t i o n o f a c i d detergent f i b r e (Goering and Van Soest 1970). For h i s t o l o g i c a l s t u d i e s , shoots of P ha l a r i s arundinacea from P i t t Meadows and Carex lyngbye i from Brunswick Po in t were c o l l e c t e d on 27 May, 9 J u l y and 17 September, 1976. On each sampl ing da te , the shoots s e l e c t ed were cons idered r ep r e sen t a t i v e of the s tand . Each Carex lyngbye i shoot had an average o f 5 leaves and the t h i r d one from the bottom was chosen f o r s e c t i o n i n g . For P ha l a r i s  a rund inacea, the f i f t h l e a f from an average of e i gh t was s e l e c t e d . Stem sec t i ons were obta ined from the base of these shoots . The samples were taken to the lab where 15-20 micron sec t i ons were cut us ing a Lab-Line/Hooker p l an t microtome (Lab-L ine Instruments I n c . , I l l i n o i s ) . Temporary se c t i ons were prepared and s t a i n ed w i th a c i d ph l o r og l u c i no l (Johansen 1940). 115 H i s t o l o g i c a l obse rva t i ons were made w i th a l i g h t microscope. Images were p ro jec ted on a screen by means of a p r o j e c t i o n tube on a compound microscope. The c r o s s - s e c t i o n a l areas of the anatomical components were measured by a p lan imeter and expressed as a percentage o f the t o t a l a rea . 6.2.2 Observat ions and r e s u l t s Seasonal changes i n l i g n i n content are g iven i n Tables 6.5 and 6 .6 . As was repor ted f o r f i b r ou s c o n s t i t u e n t s , l i g n i n i n the p l an t s r e g i s t e r e d a steady inc rease as the season progressed w i th overwintered ma te r i a l s having the h ighes t va l ue s . Species v a r i a t i o n i n l i g n i n content was ev i den t . Except f o r Carex lyngbye i and Juncus e f f u s u s , wet land spec ies g ene r a l l y had h igher l i g n i n va lues than the d ry land spec ies Dactyl i s g lomerata and Lo l ium perenne. Tables 6.7 and 6.8 show the r e a c t i o n of l e a f and stem t i s s u e s to a c i d ph l o r og l u c i no l f o r Carex lyngbye i and P h a l a r i s arund inacea. There was p rog ress i ve 1 i g n i f i c a t i o n of the l e a f t i s s u e s w i th t ime (Table 6 . 7 ) . Vascu la r bundles were the f i r s t to be l i g n i f i e d f o l l owed by the surrounding bundle sheath c e l l s . Other s i t e s o f 1 i g n i f i c a t i o n were to be found above and below the bundle e lements, the l a r g e s t zone o c cu r r i ng below the mid v e i n . The i n t e n s i t y o f l i g n i f i c a t i o n was h ighes t i n the sclerenchyma c e l l s a s soc i a t ed w i th major bundles. In g ene 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 than those of P h a l a r i s . 116 The pa t t e rn of 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 to t ha t i n the leaves (Table 6 .8 ) . However there was a marked d i f f e r e n c e between Carex and Pha l a r i s stems. The ep idermis 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 wh 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. Tables 6.9 and 6.10 show the anatomical measurements f o r leaves and stems r e s p e c t i v e l y . The v a r i a t i o n in c ross s e c t i on areas r e f l e c t s the s i z e o f the stem se c t i oned . Both t ab l e s show absence of i n t e r -c e l l u l a r c a v i t i e s i n Pha l a r i s wh i l e Carex had a t l e a s t 1.8% r i s i n g to a high va lue o f 9.4% i n the stems by September. Seasonal changes i n % vas cu l a r bundles were not no t i c eab l e and both spec ies mainta ined s i m i l a r va l ues . However, the p ropo r t i on of va s cu l a r bundles was twice as high i n the stems as i n the l eaves . There was a general inc rease in sclerenchyma t i s s u e w i th age of the p l a n t s . The leaves had lower sclerenchyma percentages than the stems. The h ighest stem s c l e r -enchyma va lue was 24.1% f o r P ha l a r i s compared to on ly 9.4% f o r Carex. Percent parenchymatous t i s s u e gene r a l l y dec l i ned r e f l e c t i n g the inc reased p ropor t i on of t o t a l l i g n i f i e d t i s s u e s . 6.2.3 D i scuss ion P rogress i ve 1 i g n i f i c a t i o n i s gene ra l l y cons idered to be the major cause o f the de c l i n e in d i g e s t i b i l i t y as a herbage matures. The high l i g n i n va lues recorded towards the end of the growing season would make the emergents poor q u a l i t y forage a t t h i s s tage . In the f a l l and w i n t e r , l i g n i n l e v e l s i n some wetland p l an t s were as high as 117 Table 6.5 Seasonal Changes i n L i g n i n (as % Dry M a t t e r ) , 1976. L o c a t i o n Species May J u l y 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 I I I I Festuca arundinacea 2. 9 9. 4 11.9 Alaksen o l d f i e l d Lolium perenne (+ Agropyron repens) 2. 8 5. 9 8.0 * Values are averages of two samples. 118 Table 6.6 Seasonal Changes i n L i g n i n (as % Dry Matter) 1977 - 1978. L o c a t i o n Species 14 May 19 Oct. 4 Mar. 1977 1977 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 effusus 2.4 4.2 6.4 Brunswick marsh Carex l y n g b y e i 3.3 7.3 11.7 I I I I Typha l a t i f o l i a 3.7 14.1 16.8 Alaksen o l d f i e l d D a c t y l i s glomerata 3.1 6.5 10.4 * Values are averages of two samples. ** March samples were taken from dead overwintered p l a n t s except f o r Carex s i t c h e n s i s , Juncus effusus and Carex l y n g b y e i . 119 Table 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 Leaf Tissues i n Transverse Sections. S t a i n i n g I n t e n s i t y Ranking* Carex l y n g b y e i P h a l a r i s 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 * Using 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 to determine l i g n i f i e d l e a f t i s s u e , the ranking was as f o l l o w s : 0 = no s t a i n i n g 1 = very l i g h t s t a i n i n g 2 = m i l d s t a i n i n g 3 = strong s t a i n i n g 4 = very strong s t a i n i n g 120 Table 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 of L i g n i f i e d Stem Tissues i n Transverse Sections. S t a i n i n g I n t e n s i t y Ranking* Carex l y n g b y e i P h a l a r i s arundinacea Stem Tissue 27/5 Date 9/7 17/9 27/5 Date 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 Vasc u l a r Bundles 3 3 4 4 4 4 * Using 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 to determine l i g n i f i e d stem t i s s u e , the ranking was as f o l l o w s : 0 = no s t a i n i n g 1 = very l i g h t s t a i n i n g 2 = m i l d s t a i n i n g 3 = strong s t a i n i n g 4 = very strong s t a i n i n g 121 Table 6.9 Anatomical Component Measurement on Leaves i n Transverse Sections. Carex lyng b y e i P h a l a r i s arundinacea Date Date 27/5 9/7 17/9 27/5 9/7 17/9 Mean t o t a l c r o s s -s e c t i o n area (cm ) % i n t e r c e l l u l a r c a v i t i e s % v a s c u l a r bundles % sclerenchyma % t o t a l l i g n i f i e d t i s s u e s % parenchyma ( l a r g e l y l i g n i f i e d ) 32.0 30.0 28.3 3.2 6.4 7.3 4.8 6.7 7.8 1.1 2.4 3.2 5.9 9.1 11.0 94.1 90.9 89.0 62.5 93.3 83.1 6.0 6.0 6.2 5.0 5.6 6.5 11.0 11.6 12.7 89.0 88.4 87.3 122 Table 6.10 Anatomical Component Measurements on Stems i n Transverse Sections. Carex l y n g b y e i P h a l a r i s arundinacea Date D a t e 27/5 9/7 17/9 27/5 9/7 17/9 mean t o t a l c r o s s -s e c t i o n a l area (cm 2) * 47.4 68.2 99.6 229.0 202.2 206.5 % i n t e r c e l l u l a r c a v i t i e s 1.8 7.0 9.4 — — % v a s c u l a r bundles 13.1 13.3 13.6 11.6 11.2 12.6 % sclerenchyma 5.9 6.7 9.4 19.0 19.2 24.1 % t o t a l l i g n i f i e d t i s s u e s 19.0 20.0 23.0 30.6 30.4 36.7 % parenchyma 81.0 80.0 77.0 69.4 69.6 63.3 * The means were obtained from at 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 at 50 x m a g n i f i c a t i o n . 123 18.2% (see Table 6 . 6 ) . At t h i s stage such a p l an t would be of l i t t l e va lue to most he rb i vo re s . Decomposit ion by s o i l m i c ro -organisms cou ld a l s o be c u r t a i l e d . Minderman (1968) noted t ha t the p ropo r t i on i ng of l i g n i n i n l i t t e r fragments tends to d i c t a t e the shape o f the long term decomposit ion curve once the more l a b i l e components have been removed. Lo l ium perenne, Dacty l i s g lomerata and Carex lyngbye i would, presumably, degrade f a s t e r than the other spec ies on account of t h e i r r e l a t i v e l y low l i g n i n va l ues . The low l i g n i n l e v e l s i n Juncus e f fusus throughout the year can be a t t r i b u t e d i n pa r t to i t s tendency t o r e t a i n green shoots and to develop new shoots even i n the w in te r months. Shenk and E l l i o t (1971) observed l a rge v a r i a t i o n s among grasses and legumes i n r e l a t i v e amounts and arrangements of va s cu l a r bund les , l i g n i f i e d wa l l s and o ther anatomical s t r u c t u r e s . Schank e t al_. (1973) repor ted tha t the percentage of va s cu l a r bundles i n stem cross sec t i ons o f Hemarthrias sp . was i n v e r s e l y r e l a t e d to in v i t r o o rgan i c matter d i g e s t i b i l i t y . W i l k i n s (1972) c a l c u l a t e d c ross s e c t i o na l areas o f sc lerenchyma, vas cu l a r t i s s u e and non-vascu la r t i s s u e in temperate grasses and repor ted s i g n i f i c a n t negat ive c o r r e l a t i o n s between po t en 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 tha t vas cu l a r bund les , c u t i n i z e d ep ide rm i s , and s c l e r -enchyma passed through the an ima l ' s d i g e s t i v e t r a c t und iges ted . Other repor t s have shown tha t sclerenchyma and o ther l i g n i f i e d t i s s u e s are u s u a l l y not degraded (Ak in e t al_. 1973, Baker and Ha r r i s 1947, Drapala e t aJL 1947). D i f f e rences i n the ease of d i g e s t i b i l i t y o f t i s s u e types suggest t ha t the amounts of s l ow ly d i g e s t i b l e as we l l as non -d i g e s t i b l e l i g n i f i e d t i s s ue s could a f f e c t the r a t e o f d i g e s t i o n 124 as we l l as decomposit ion o f p l an t m a t e r i a l s . Our s tud i e s showed tha t l i g n i f i e d t i s s u e was con f ined c h i e f l y to the vas cu l a r bundles i n the e a r l y stages of growth. L i g n i f i c a t i o n then spread g radua l l y to o ther t i s s u e s as the season progressed . Th is pa t t e rn 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 l i g n i n 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 va r i ous t i s s ue 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 of sclerenchyma t i s s u e was much h igher i n the l a t t e r than the former. Carex a l s o had loose parenchyma arrangement w i th numerous i n t e r c e l l u l a r c a v i t i e s whereas Pha l a r i s was a s so c i a t ed w i th c l o s e l y packed c e l l s w i th l e s s i n t e r n a l su r f a ce . These fea tu res might be expected to favour Carex r a the r than Pha l a r i s i n d i g e s t i o n and decompos i t ion . 6.3 C u t i c l e The na tura l p r o t e c t i v e cover ing o f the leaves of h igher p l an t s c on s i s t s of a l a ye r of n o n - l i v i n g c u t i c l e a s soc i a t ed w i th the th ickened outer wa l l s o f the ep ide rm is . I t i s made up of a spongy framework of c u t i n formed from po lymer ized ac i d s w i th wax embedded i n them (Eg l i n t on and Hamilton 1967). Marked v a r i a t i o n s occur i n the th i ckness of the c u t i c l e and i n the degree o f wax format ion between leaves o f d i f f e r e n t s pe c i e s , between d i f f e r e n t aged leaves of one spec ies 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 th i ckness probably depends on gene t i c as we l l as environmental f a c t o r s . • 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 ro t e c t s the p lan t from invad ing organisms and probably reduces t r a n s p i r a t i o n . An outs tand ing proper ty o f c u t i c l e i s i t s chemical s t a b i l i t y which makes i t extremely r e s i s t a n t to b i o l o g i c a l deg rada t i on . The r e s i s t an ce of c u t i n i z e d ma t e r i a l s to b a c t e r i a l decomposit ion may be evidenced by the pe r s i s t ence i n nature of p o l l e n g ra ins which con ta in much c u t i n over long per iods o f geo l og i c a l t ime. I t has been suggested tha t herbage consumed by g raz ing herb ivores i s degraded i n i t i a l l y by phys i ca l removal o f the c u t i c l e and break ing o f f i b r e s thus c r ea t i ng f r a c t u r e s and entry s i t e s f o r m i c r ob i a l enzymes capable of d i g e s t i n g the s t r u c t u r a l carbohydrates (Monson and Burton 1972, Baker and Ha r r i s 1947, Monson e t al_. 1972). Heinen (1961) has demonstrated the ex i s tence of a cu t i nase system i n c e r t a i n microorganisms which enables them to u t i l i z e c u t i n as a carbon source under aerob i c c o n d i t i o n s . However under anaerob ic c o n d i t i o n s , the c u t i c l e may be preserved almost i n d e f i n i t e l y (Ha r r i s 1956). I t i s g ene r a l l y known tha t p l a n t ma te r i a l f i n a l l y d isappears dur ing decomposit ion even under wet land c o n d i t i o n s , suggest ing tha t smal l but d i s c e r n i b l e changes i n the l e a f sur faces occur dur ing the t r ans f o rma t i on . Over a sho r t pe r iod o f t ime, such changes are l i k e l y to be beyond the r e s o l u t i o n o f l i g h t microscopy. The scanning e l e c t r on microscope appeared to be usefu l f o r de tec t i ng these changes s i n ce i t permits observat ions a t d i f f e r e n t magn i f i c a t i on s of the sur face s t r u c t u r e o f the shoots . 126 6.3.1 Ma t e r i a l s and methods Tota l c u t i n content was es t imated by d i g e s t i n g KMnO l i g n i n res idue w i t h 72 percent H 2 S 0 4 (Goer ing and Van Soest 1970). Cu t in was then c a l c u l a t e d as l o s s in weight upon ash i ng . To study the nature 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 shoot ma 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 tr immed, mounted on aluminum studs and coated under vacuum w i t h go ld pal ladum, then observed and photographed. Severa l random samples o f each shoot were observed under the microscope and photo-graphed. Only s i n g l e photomicrographs are presented i n the t h e s i s . 6 .3.2 Observat ions and r e s u l t s Seasonal changes i n c u t i n content of the emergent spec ies s t ud i ed are presented i n Tables 6.11 and 6.12. The t ab l e s show t ha t c u t i n l e v e l s were gene r a l l y low, ranging 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 spec i e s . The lowest va lues were found i n P h a l a r i s arundinacea wh i l e Sc i rpus  c ype r i nus , Carex lyngbye i and Typha l a t i f o l i a conta ined h igher percentages. The t ab l e s a l s o show a r e l a t i v e l y c on s i s t en t inc rease i n c u t i n content from May to September and October f o r most spec ies s t u d i e d . However, there was a d e c l i n e i n overwintered m a t e r i a l s , Carex  s i t c h e n s i s and Sc i rpus acutus being the on ly excep t i ons . 127 Table 6.11 Seasonal Changes i n C u t i n (as % Dry M a t t e r ) , Summer, 1976. L o c a t i o n Species May 18-21 J u l y 6-9 Sept. 16-21 P i t t marsh ! ! I I Brunswick marsh Alaksen o l d f i e l d Calamagrostis canadensis 0.9* 1.2 1.4 P h a l a r i s arundinacea 0.6 0.8 0.9 Carex l y n g b y e i 1.3 1.1 1.3 Lolium perenne 0.7 1.0 1.1 * Values are averages of two samples. 128 Table 6.12 Seasonal Changes i n C u t i n (as % Dry M a t t e r ) , 1977-1978. Lo c a t i o n Species 14 May 19 Oct. 4 Mar. 1977 1977 1978 P i t t marsh Brunswick marsh Alaksen o l d f i e l d Calamagrostis canadensis 0.8* P h a l a r i s arundinacea 0.3 Carex s i t c h e n s i s 0.8 Scirpus cyperinus 1.5 Scirpus acutus 0.7 Juncus effusus 0.9 Carex l y n g b y e i 1.1 Typha l a t i f o l i a 1.1 D a c t y l i s glomerata 0.8 1.8 0.5 1.0 2.2 1.0 0.9 1.8 1.7 1.0 1.0 0.3 1.1 2.1 1.0 0.8 0.8 1.6 0.6 * Values are averages of two samples. 129 Scanning e l e c t r on micrographs of l e a f or stem sur faces of the spec ies s tud i ed are shown i n F igures 6.2 to 6 .8 . I t i s p o s s i b l e and most l i k e l y tha t the presence of s i l t depos i t s on the sur faces obscured many f ea tu res tha t would be of i n t e r e s t i n t h i s s tudy . These s i l t depos i t s were qu i t e prominent in the ma te r i a l s c o l l e c t e d from Brunswick marsh where the p l an t s are f r equen t l y subjected to t i d a l a c t i o n . Despi te these anomal ies , severa l f ea tu res p e r t i n en t to degradat ion were d i s c e rned . Al though not shown i n the photographs, most spec ies had se r r a t ed l e a f edges. Of a l l the spec ies examined, on l y Carex s i t c h e n s i s and Festuca arundinacea had tr ichomes (F igures 6.2 and 6 . 6 ) . These tr ichomes were g l andu l a r i n Carex s i t c h e n s i s ; s tou t sharp-po in ted and non-g landu lar i n Fes tuca . By comparing top and bottom photographs, i t was observed tha t very l i t t l e weather ing o f the sur faces took p lace on spec ies from the P i t t marsh and A laksen o l d f i e l d (F igures 6 .2 , 6.3 and 6.8) except f o r Equisetum whose su r face s t r u c t u r e was complete ly l o s t over the w in te r months (F igure 6 . 4 ) . C u t i c u l a r sur faces of the Brunswick marsh spec ies were h i gh l y abraded dur ing the w in te r (F igures 6.5 and 6.6) a l though to a l e s s e r degree i n Typha l a t i f o l i a ( F igu re 6 . 7 ) . 6.3.3 Di scuss ion Low percentages of c u t i n were recorded i n t h i s study which i n d i c a t e t ha t c u t i n content j jer s_e probab ly p lays a minor r o l e i n depress ing 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 raz ing pathways. 130 F igure 6.2: Scanning E l e c t r on Photomicrographs of Adax ia l Leaf Sur faces o f Carex s i t c h e n s i s ( P i t t ) . A. (x 50) Top photo: young photosyn the t i c blade showing g l andu l a r t r i chomes. Bottom photo: overwintered blade showing l i t t l e e ros i on B. (x 400) Top photo: young pho tosyn the t i c blade Bottom photo: overwintered blade 133 F igure 6 .3: Scanning E l e c t r on Photomicrographs of Shoot Sur faces o f Sc i r pus acutus ( P i t t ) . A. (x 50) Top photo: young pho tosyn the t i c shoot Bottom photo: overwintered shoot showing l i t t l e e ro s i on B. (x 400) Top photo: young pho tosyn the t i c blade Bottom photo: overwintered blade 136 F igure 6.4: Scanning E l e c t r on Photomicrographs of Adax i a l Leaf Sur faces of Equisetum f l u v i a t i l e ( P i t t ) . A. (x 50) Top photo: young photosynthe t i c blade Bottom photo: overwintered blade showing severe e ros i on B. (x 400) Top photo: young photosyn the t i c blade Bottom photo: overwintered blade 139 F igure 6.5: Scanning e l e c t r o n photomicrographs of Adax ia l Leaf Sur faces o f Carex lyngbye i (Brunsw ick) . A. (x 50) Top photo: young pho tosyn the t i c blade Bottom photo: overwintered blade showing severe e ros ion and depos 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 pho tosyn the t i c blade Bottom photo: overwintered blade 142 F igure 6.6: Scanning E l e c t r on Photomicrographs of Adax ia l Leaf Sur faces o f Festuca arundinacea (Brunsw ick) . A. (x 50) Top photo: young photosyn the t i c b lade Bottom photo: overw intered blade showing almost severe e ros i on B. (x 400) Top photo: young photosynthe t i c blade Bottom photo: overwintered blade 145 F igure 6.7: Scanning E l e c t r on Photomicrographs of Adax ia l Leaf Sur faces o f Typha l a t i f o l i a (Brunswick) . A. (x 50) Top photo: young pho tosyn the t i c blade Bottom photo: overwintered blade showing c u t i c u l a r e r o s i o n . B. (x 400) Top photo: young photosyn the t i c blade Bottom photo: overwintered blade 6 148 F igure 6.8: Scanning E l e c t r on Photomicrographs o f Adax ia l Leaf Sur faces o f Dacty l i s glomerata (A l aksen) . A. (x 50) Top photo: young photosyn the t i c blade Bottom photo: overwintered blade showing c u t i c u l a r e r o s i o n . B. (x 400) Top photo: young photosynthe t i c blade Bottom photo: overwintered blade 151 I t appears, however, tha t l i k e the f i b r ou s f r a c t i o n s , c u t i c u l a r ma te r i a l g ene r a l l y inc reases as p l an t s age. The dec l i ne i n c u t i n content over the w in te r months probably r e f l e c t e d l osses due to weather ing and abras ion of the p l an t su r f a ce s . Al though se r r a t ed 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 ng , i t appears from t h i s study tha t few wet land spec ies have a we l l developed tr ichome system f o r defense i n t h i s regard . There i s no doubt t ha t the p r i c k l y tr ichomes possessed by Festuca arundinacea might deter c e r t a i n c l a sses of herb ivores from feed ing on the p l a n t s . G landu lar tr ichomes such as those found i n Carex s i t c h e n s i s (F igure 6.2) cou ld produce t ox i n s and/or r e p e l l e n t s which are ob j e c t i onab l e to p o t en t i a l g r a z e r s . S i m i l a r r o l e s of t r ichomes i n p l an t defense have been reviewed by Lev in (1973). The r e s u l t s a l s o showed v a r i a b l e su r face changes a few months a f t e r senescence and death o f the a e r i a l shoots . Minimal sur face changes were recorded i n the P i t t marsh s pe c i e s , except f o r Equisetum, i n d i c a t i n g l i t t l e degradat ion of the shoots . The f a s t degradat ion of Equisetum r e f l e c t e d the non- f ib rous nature of t h i s s pe c i e s . Degradat ion a l so appeared to be minimal but uni form i n the o l d f i e l d s pe c i e s . The Brunswick marsh spec ies su f f e r ed f a r more abras ion than the P i t t marsh o r o l d f i e l d spec i e s . C u t i c u l a r and epidermal removal was presumably accompl ished e a s i l y through t i d a l a c t i v i t y i n the b ra ck i sh marsh. However, t a l l robust spec ies growing a t h igher subs t ra te e l e va t i on s may stand e r e c t throughout the w in te r months and remain r e l a t i v e l y undegraded u n t i l the summer when most of the shoots f a l l to the subs t ra te su r f a c e . Typha l a t i f o l i a was a good example (F igure 6 . 7 ) . 152 6.4 S i l i c a A l though i t has been e s t a b l i s h ed tha t s i l i c a i s metabo l i zed by many spec ies of p l a n t s , i t may i n some ins tances be regarded as no more than s o i l con taminat ion . Uptake o f s i l i c a by p l an t s depends both on the a v a i l a b i l i t y of s i l i c a i n the s o i l and on the cha r a c t e r -i s t i c o f the p l an t spec ies (Jones e t a]_. 1963). Many members of the grass f am i l y are a c t i v e cumulators o f s i l i c a (Jones and Handreck 1967). S i l i c a appears to f un c t i on 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 reng th to the p l a n t . But i t has a l s o been suggested tha t i n c e r t a i n spec i e s , c e l l wa l l s i l i c a may, l i k e l i g n i n , l i m i t m i c r ob i a l degradat ion of the s t r u c t u r a l carbohydrates (Van Soest and Jones 1968). High l e v e l s of s i l i c a have a l so been a s so c i a t ed w i th u r i n a r y c a l c u l i i nc idence i n c a t t l e (Parker 1957). 6.4.1 Ma t e r i a l s and methods S i l i c a was obta ined on some se l e c t ed samples as the ash remain ing a f t e r permanganate l i g n i n ash was leached w i th 48% HBr f o r one hour (Goering and Van Soest 1970). 6 .4.2 Resu l t s Table 6.13 shows tha t most spec ies d i d not depos i t high l e v e l s of s i l i c a . The on ly spec ies w i th s i l i c a l e v e l s above 2% were P h a l a r i s  arundinacea and Carex l y ngbye i . Table 6.13 S i l i c a (as % Dry Weight) i n the Standing Crops of Some Species Sampled on 19 October, 1977. L o c a t i o n Species % S i l i c a 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 " " Scirpus acutus 0.7 " " Juncus effusus 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 Alaksen o l d f i e l d D a c t y l i s glomerata 1.9 * Values are averages of two samples. 154 6 .4 .3 D i s cuss i on S i l i c a has been repor ted to be a n u t r i t i o n a l problem in the Northern Great P l a i n s of North America where some o f the range grasses con ta in more than 2% s o l ub l e s i l i c a (Bezeau e t al_. 1966). P h a l a r i s arundinacea and Carex lyngbye i were the on ly spec ies w i th a t o t a l s i l i c a content above 2%. There i s a p o s s i b i l i t y t ha t some of the va lues were e leva ted due to s o i l contaminat ion p a r t i c u l a r l y i n Carex lyngbyei which exper iences f requent t i d a l a c t i o n . I t appears from the r e s u l t s tha t s i l i c a l e v e l s i n the emergent communities are f a r too low to be a l i m i t i n g f a c t o r i n t h e i r deg rada t i on , whether by g razers or by d e t r i t o v o r e s . Br ink e t al_. (1961) repor ted tha t w i th the except ion of a few spec ies such as Equisetum, the s i l i c a content o f wet land spec ies i n B r i t i s h Columbia i s too low to be a n u t r i t i o n a l concern i n ungu la tes . 6.5 Pheno l i c Compounds Bes ides the s t r u c t u r a l components d i scussed i n the preceding s e c t i o n s , i t appears t ha t there are so l ub l e c on s t i t u en 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 to the p l a n t . Some o f the so-c a l l e d secondary p l an t substances are known to possess t o x i c or 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 render p l an t s unpa la tab le to he rb i vo re s . The same compounds may a l so r e t a r d or i n h i b i t m i c r ob i a l a c t i v i t y i n the s o i l hence reduc ing decomposit ion r a t e s . 155 We assessed the t o t a l pheno l i c content of some o f the emergent spec ies because pheno l i c compounds appear to be one of the most widespread secondary p l an t metabo l i t e s known. The general r o l e of pheno l i c compounds i n p l an t s has not y e t been we l l documented. Some o f them have been imp l i c a t ed i n a l l e l o p a t h y (Van Sumere 1960) wh i l e others have been shown to be r e spons i b l e f o r u n p a l a t a b i l i t y of c e r t a i n forage p lan ts (Burns et al_. 1976). The r o l e i n d e t r i t a l , accumulat ive and g raz ing pathways has not been we l l documented. 6.5.1 Ma t e r i a l s and methods Young p l an t s tend to have h igher concen t ra t i ons of secondary compounds than mature ones w i th the leaves con ta i n i ng more than the stems (Parmar and Br ink 1976). Young l e a f samples were the re fo re c o l l e c t e d on 10 May, 1978 when peak pheno l i c concen t ra t i ons were expected i n the p l a n t s . A f t e r s epa r a t i on , the leaves were immediate ly submerged i n l i q u i d n i t rogen and taken to the lab where they were f reeze d r i e d . Dr ied samples were ground i n a Wi ley m i l l to pass through a 1 mm sc reen . 2 g of sample were ex t r a c t ed w i th 80% methanol as desc r i bed by Burns et_ al_. (1976) and t o t a l pheno l i c content was determined us ing the Fo l in -Denn is reagent and ch lo rogen i c a c i d as the standard (Rosenb la t t and Peluso 1941). 6.5.2 Observat ions and r e s u l t s 156 To ta l pheno l i c concen t ra t i ons i n the leaves of p l an t s from the Brunswick marsh and A laksen o l d f i e l d were s i m i l a r , averag ing 20 mg/g of l e a f dry weight (Table 6 .14) . The spec ies from the P i t t marsh showed cons ide rab le v a r i a t i o n i n pheno l i c con ten t . Sc i r pus cyper inus r e g i s t e r e d 59.5 mg/g, the h ighest va l ue , wh i l e Juncus e f fusus had the lowest l e a f concen t ra t i on o f 10.8 mg/g. 6 .5 .3 D i s cuss i on I t i s probab le tha t q u a n t i f i c a t i o n of t o t a l phenols by the procedure desc r ibed here cou ld go a long way i n e xp l a i n i n g v a r i a t i o n s in a c c e p t a b i l i t y o f the p l an t s by g raz ing herb ivores as we l l as the ra tes o f m i c r ob i a l decomposit ion i n the f i e l d . Burns e t al_. (1967) and L a n g i l l e and McKee (1968) repor ted a tann in content range of 1.5 to 3.8% i n crownvetch. The tann in values were determined by a method s i m i l a r to t ha t used i n our s t u d i e s . The workers concluded tha t these tann in l e v e l s were too low to i n f l u ence p a l a t a b i l i t y o f crownvetch. Al though there were no d i r e c t l y comparable data to support ou rs , i t appears, from the repor t s o f the above workers , t ha t t o t a l pheno l i c l e v e l s i n most spec ies sampled were not of s u f f i c i e n t magnitude to s i g n i f i c a n t l y i n f l u ence animal response o r p l an t decay. However, f u r t h e r work i s recommended to c l a r i f y t h i s aspec t . 157 Table 6.14 Average Concentration of T o t a l Phenols i n the Leaves Harvested on 10 May, 1978. Phenolic Content L o c a t i o n Species mg / gm dry weight 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 Brunswick marsh Carex l y n g b y e i 19.8 " Typha l a t i f o l i a 19.1 Alaksen o l d f i e l d D a c t y l i s glomerata 20.0 * Values are averages of two samples. 158 7. NUTRIENTS IN EMERGENT VEGETATION Nu t r i en t t r a n s f e r s i n p l an t communities have severa l aspects tha t deserve spec i a l a t t e n t i o n w i th respec t to n u t r i e n t c y c l i n g i n wet land systems. The major sources of n u t r i e n t s to wet land p l an t s i n c lude water ( p r e c i p i t a t i o n , su r face water , ground wa te r ) , a i r and the subs t r a t e . Nu t r i en t s accumulated in the p l an t s may be re turned to the environment through: (1) l each ing of aboveground s tand ing crops (and a l s o through gu t t a t i o n v i a s a l t glands i n p l an t s of s a l i n e and b rack i sh a r e a s ) , (2) r e l ease v i a decomposit ion ( d e t r i t u s ) and (3) 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 are s to red or re l eased dur ing death and decompos i t ion. A f u l l 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 of t h i s t r e a t i s e . Consequent ly, on ly a few aspects of n u t r i e n t c y c l i n g were examined as pa r t o f the many p l an t mediated processes in the wetlands of south western B r i t i s h Columbia. The major aspects d i scussed under t h i s s e c t i on i n c l ude n u t r i e n t concen-t r a t i o n i n the s tand ing crops and l each ing l o s ses from the p l a n t s . The r e l ease of nu t r i e n t s v i a decomposit ion has- been l a r g e l y d i scussed under Sec t i on 5 and i s not covered here. Our data were obta ined s o l e l y from aboveground s tand ing shoots but i t should be po in ted out tha t s tud i e s o f belowground organs ( roots and rhizomes) r equ 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 t h e i r l a rge dry matter y i e l d s (Table 4 . 9 ) . Moreover, the perenn ia l growth hab i t o f many wet land p lan ts p laces a s i g n i f i c a n t importance on n u t r i e n t reserves belowground. A sp r i ng dep l e t i on and f a l l recharge 159 of nu t r i e n t s i n the roots and rhizomes might be expected as has been shown i n o ther s tud i e s (Klopatek 1975). 7.1 Nu t r i en t Concent ra t ion i n the Standing Crops T i ssue n u t r i e n t l e v e l s have not been w ide ly exp lored i n emergent communities of B r i t i s h Columbia a l though a l a rge body of l i t e r a t u r e e x i s t s f o r wetlands o f o ther reg ions (Keefe 1972, Dykyjova 1973, Hutchinson 1975). From repo r t s on other wet lands , d i f f e r en 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 to a d d i t i v e e f f e c t s of spec ies (Boyd 1970a, Mason and Bryant 1975), s i t e f e r t i l i t y (Boyd and Hess 1970, Wali ejt al_. 1972) and seasonal t rends (Boyd 1969). Our n u t r i e n t s tud i e s focussed l a r g e l y on t o t a l a sh , n i t r ogen and su lphur . 7.1.1 Tota l ash Laboratory a n a l y s i s f o r t o t a l ash i s g ene r a l l y i n d i c a t i v e of the amount of minera l n u t r i e n t s present i n p l a n t s . However, ash va lues o f t en i nc lude extraneous mate r i a l of non-p lant o r i g i n . The p ropo r t i on of extraneous ma te r i a l i s l i k e l y to be s i g n i f i c a n t i n wet land spec ies which are p e r i o d i c a l l y covered w i th sediment- laden water . Ash determinat ion i s the re fo re use fu l not on ly f o r e s t ima t i ng t o t a l minera l content of the p l an t s but a l s o f o r c o r r e c t i n g organ ic matter v a l u e s . 160 7.1.1.1 Ma t e r i a l s and methods Dry ground ma te r i a l s were prepared from samples used i n the s tand ing crop es t ima t i ons repor ted in the prev ious s e c t i o n s . These were analyzed f o r ash by combustion a t 550° C. 7 .1 .1 .2 Observat ions and r e s u l t s Seasonal trends i n ash content o f s e l e c t e d spec ies are g iven i n Table 7.1 f o r 1976, and Table 7.2 f o r 1977/78. In both years there was a steady dec l i ne i n % ash w i th t ime. For each sampl ing da te , the P i t t marsh spec ies gene ra l l y had lower ash percentages than those from the t i d a l marshes and a rab le o l d f i e l d s . Ca l c u l a t ed ash l e v e l s ( i n g/m dry matter) i n the s tand ing crops (Table 7.2) d i d not show a s i m i l a r and c on s i s t en t d e c l i n e . In most cases ash l e v e l s i nc reased between May and October, but i n the w i n t e r , a general de c l i ne was noted f o r some spec ies and an inc rease in o t he r s . 7 .1 .1 .3 D i s cuss i on Due to i n s u f f i c i e n t samp l ing , no s t a t i s t i c a l a na l y s i s was done on the da ta . However, a general t rend of i n c r ea s i ng ash content w i th age o f the p lan ts was recorded. Such dec l i nes would be a t t r i b u t e d p a r t l y to decreased minera l uptake dur ing e l abo r a t i on o f s t r u c t u r a l carbohydrates . The high ash va lues a s soc i a t ed w i th Brunswick marsh spec ies may be a r e s u l t o f s i l t depos i t s on the p lan ts from t i de s al though they cou ld a l s o r e f l e c t the innate c h a r a c t e r i s t i c s of the p l a n t s . Moody ( 1978 ) observed tha t washing o f p l a n t ma te r i a l s from Brunswick marsh d i d not change % 161 Table 7.1 Seasonal Changes in Total Ash (as % Dry Wt.) of Selected Species from Several Sites, 1976. Location Species May July Sept. Pitt 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 i t I I Festuca arundinacea 9.5 6.2 5.9 Alaksen old f i e l d Lolium perenne 7.0 5.9 5.3 I I I I i t Dactylis glomerata 10.5 8.3 — * Values are averages of two samples. Table 7.2 Seasonal Changes i n T o t a l Ash (as % and as g/m dry matter i n the standing crop) of Selected Species from Several S i t e s , 1977 / 1978. L o c a t i o n Species May Oct. March 1977 1977 1978 g/m2 % g/m2 % g/m2 P i t t marsh Calamagrostis canadensis 5.1* 7.6 5.4 52.1 4.6 46.6 i t I I P h a l a r i s arundinacea 6.1 30.9 5.2 102.0 — — i i I I Carex s i t c h e n s i s 5.1 8.4 3.6 30.7 3.2 37.7 I I I I Scirpus cyperinus 6.0 12.0 3.7 40.7 2.8 32.8 I I I I Scirpus acutus — — 2.8 8.8 — — Brunswick marsh Carex lyngbyei 10.7 38.6 7.2 30.5 12.6 48.4 i i I I Typha l a t i f o l i a 11.1 42.3 5.3 126.4 5.3 115.8 Alaksen o l d f i e l d D a c t y l i s glomerata 8.7 48.8 7.5 21.8 6.9 26.2 * Values are averages of two samples. 163 ash s i g n i f i c a n t l y . Low ash percentages repor ted f o r P i t t marsh spec ies probably r e f l e c t low minera l uptake by p l an t s growing in the o l i g o t r o p h i c h a b i t a t . Ash uptake per un i t area (Table 7.2) i s i n t e r e s t i n g i n tha t i t p a r a l l e l s t o t a l dry matter product ion and i t seems to i n d i c a t e tha t the wet land p lan ts accumulate a f a i r l y l a r ge amount of minera l n u t r i e n t s i n t h e i r s tand ing c rops . 7.1.2 N i t rogen and s u l f u r F ixed n i t rogen i n wet land hab i t a t s appears to f r equen t l y l i m i t dry matter product ion and add i t i o n o f f e r t i l i z e r n i t r ogen o f ten r e s u l t s i n dramat ic y i e l d inc reases (Ty l e r 1967, Stewart e t al_. 1973, Haag 1974, V a l i e l a and Teal 1974). On the o ther hand, wet land sub-s t r a t e s , p a r t i c u l a r l y those w i th high o rgan i c matter content , tend to possess l a r ge amounts of t o t a l o rgan i c n i t r ogen (Sanford and Lancaster 1962). When o x i d a t i o n o f these subs t ra tes o c cu r s , e . g . through dra inage , much o f the n i t rogen becomes p o t e n t i a l l y a v a i l a b l e to p lan ts (Ponnamperuma 1972, N i c h o l l s and MacCrimmon 1974). The concen t ra t i on of n i t r ogen in the s tand ing crop o f some emergent spec ies was determined as pa r t of the n i t rogen c y c l e in wet lands . S u l f u r , l i k e~n i t r o g en , i s to be found i n cons i de rab l e amounts i n the protein-enzyme complexes of a l l p l a n t s . Presence of aromat ic s u l f u r gases was qu i t e ev ident i n some wet land subs t ra tes i n our study a reas , and s ince 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 wet land p l an t s seems to be s can ty , 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 wet land spec i e s . 164 7.1.2.1 Ma t e r i a l s and methods Tota l n i t rogen was determined on dry ground samples by the semi-micro K je ldah l procedure o f Nelson and Sommers (1973). S u l f u r was ana lyzed by the t u r b i d i m e t r i c procedure developed by Bards l ey and Lancaster (1965). A l l samples were obta ined from green s tand ing shoots . 7 .1 .2 .2 Observat ions and r e s u l t s Seasonal changes in n i t rogen content of the standing crops are g iven in Tables 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 the season progressed dur ing 1976 and 1977. The h ighes t N content was obta ined i n May (1.88% i n 1976 and 2.6% i n 1977) and the lowest (0.6%) i n September or October r e s p e c t i v e l y . N percentages obta ined i n May 1977 were on average h igher than those obta ined dur ing the same pe r i od i n 1976, probably imp ly ing annual v a r i a t i o n i n uptake and l e v e l s i n the s ub s t r a t e . Tables 7.3 and 7.4 a l s o show cons ide rab l e spec ies v a r i a t i o n i n terms o f N. The emergent spec ies g ene r a l l y had s i m i l a r o r even h igher n i t rogen l e v e l s than the t e r r e s t r i a l s pe c i e s . Ca l cu l a t ed n i t rogen l e v e l s per un i t area (g/m ) g ene r a l l y r e f l e c t e d s tand ing crop y i e l d s . I t i s apparent from Table 7.5 tha t s u l f u r l e v e l s f o l l owed the same t rend as n i t r o gen , the va lues d e c l i n i n g from May to October. I t i s not c l e a r , why the s u l f u r content i n Carex l y ngbye i , the on l y t r u l y b rack i sh marsh spe c i e s , i nc reased dur ing the same pe r i od . 165 Table 7.3 Seasonal Changes i n Nitrogen (% Dry Wt.) of Selected Species from Several S i t e s , 1976. L o c a t i o n Species May J u l y Sept. P i t t marsh Iona marsh Brunswick marsh Alaksen o l d f i e l d Calamagrostis canadensis 1.8* Carex l y n g b y e i 1.4 Carex l y n g b y e i 1.3 Festuca arundinacea 1. 3 Lolium perenne 1.1 D a c t y l i s glomerata 1.3 0.8 1.0 1.1 0.8 0.6 0.8 0.6 0.7 0.9 0.8 0.6 * Values are averages of two samples. 166 Table 7.4 Seasonal Changes i n Nitrogen (% Dry Wt. and g/m i n Dry Matter of Standing Crop) of Selected P l a n t Species from Several S i t e s , 1977. L o c a t i o n Species May % , 2 g/m October % , 2 g/m P i t t marsh Calamagrostis canadensis 1.8* 2.7 0.6 15.6 i i I I P h a l a r i s arundinacea 2.6 13.2 0.8 15.7 I I I I Carex s i t c h e n s i s 1.7 1.8 0.7 6.0 i t I I Scirpus cyperinus 1.9 3.8 0.7 7.7 I I I I iScirpus acutus - - 0.6 1.9 Brunswick marsh Carex l y n g b y e i 2.3 8.3 0.8 3.4 I I Typha l a t i f o l i a 2.1 8.0 0.6 14.3 Alaksen o l d f i e l d Lolium perenne 2.0 11.2 0.8 2.3 * Values are averages of two samples. 167 Table 7.5 Seasonal Changes i n S u l f u r (parts per m i l l i o n , Dry Wt.) of Selected P l a n t Species from Several S i t e s , 1977. Loc a t i o n Species May 10 Oct. 16 P i t t marsh I I I I I I I I I I I I I I I I Brunswick marsh Alaksen o l d f i e l d Calamagrostis canadensis 920* 490 P h a l a r i s arundinacea 1400 770 Scirpus cyperinus 1620 810 Scirpus acutus 1300 335 Juncus effusus 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 Lolium perenne 1440 290 * Values are averages of two samples. 168 7 .1 .2 .3 D i scuss ion T i s sue concen t ra t i ons o f N, P, K and S normal ly 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 sp r i ng to f a l l (Boyd 1969, 1970a, Dykjova 1973). Our r e s u l t s g ene r a l l y conf i rmed t h i s t r end . 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 the r f a c t o r s , to decreased uptake f o r aboveground p roduc t i on , t r a n s l o c a t i o n to storage t i s s ue s belowground, and to l each ing of nu t r i e n t s from the p l a n t s . Species d i f f e r en ce s i n % N and S were probably a r e f l e c t i o n of innate spec ies 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 . The amount of n i t rogen accrued i n the s tand ing crop (g/m ) gene ra l l y p a r a l l e l e d s tand ing crop dry matter p roduc t i on . 7.1.3 Response of some mar i t ime emergents to f e r t i l i z e r n i t r ogen The nu t r i e n t dynamics o f marsh s o i l s are gene ra l l y qu i t e d i f f e r e n t from t h e i r t e r r e s t r i a l c oun te rpa r t s . The anaenobic s o i l ma in ta ins reduced compounds and ions such as NH4+, h^S, Mn++, Fe++ and CH^ ins tead o f t h e i r o x i d i z e d counterpar ts NO^, S0^~, M n + + + + , F e + + + and C 0 2 (Har ter 1966). Among the n u t r i e n t e lements, n i t r ogen appears to be c r i t i c a l f o r many components and processes i n wet lands . S i g n i f i c a n t response to app l i e d n i t r ogen i n terms o f dry matter p roduct ion has been repor ted f o r s a l t marshes (Stewart e t al_. 1973, V a l i e l a and Teal 1974) and o ther wetlands (Ty l e r 1967, Haag 1974). V a l i e l a and Teal (1974) suggested tha t n i t rogen i s one of 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 ke the o ther n u t r i e n t components, reduced forms of N such as NH^ (Pesek 1964) are o f t en more predominant i n wet land subs t ra tes than the o x i d i z ed forms ( e . g . NOg). The n i t r a t e forms are l o s t e i t h e r through l each ing ( P a t r i c k and Mahaptra 1968) or through d e n i t r i f i c a t i o n v i a n i t r a t e to n i t r ogen gas (Taha e t al_. 1967, Keeney 1973). We examined the response o f some wet land spec ies to f e r t i l i z e r n i t rogen p a r t l y because o f our i n t e r e s t i n n i t r ogen c y c l i n g i n wet lands, and a l s o because of the recent i n t e r e s t i n the use of n i t r ogen f e r t i l i z e r s to enhance p l an t es tab l i shment i n d i s tu rbed wet land areas . The main ob j e c t i v e s of the study were to determine whether a d d i t i o n of n i t rogen r e s u l t e d i n changes i n dry matter p roduct ion and n i t r ogen content o f the p l a n t s , whether there was any d i f f e r e n c e i n response between NH^ and NO^  sources and whether there was a " c a r r y -ove r " e f f e c t to the f o l l o w i n g y ea r . 7.1.3.1 Ma t e r i a l s and methods This t r i a l was undertaken a t seven s i t e s : (1) P i t t marsh, (2) Iona marsh, (3) Brunswick marsh, (4) Colony Farm ( Pha l a r i s  arundinacea s i t e ) , (5) Colony Farm ( D a c t y l i s g lomerata s i t e ) , (6) U n i v e r s i t y of B. C. Farm, (7) A laksen Farm. S i t e (1) rep-resented a f r e sh water marsh, (2) and (3) were b ra ck i sh marshes and the r e s t were a rab l e o l d f i e l d s . 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 tudy. On June 12 and 13, 1976, when most o f the wet land subs t ra tes were wet but w i th no s tand ing water , s tand ing shoots were c l i p p ed a t ground l e v e l and the p l o t s were c leaned up as much as po s s i b l e by r a k i n g . On June 20, 1976, n i t r ogen was app l i e d as 336 kg/ha each o f (NH 4) 2 S 0 4 and NaNO^. The (NH 4) 2 S 0 4 supp l i ed 2 2 7.1 g/m N wh i l e the NaN0 3 supp l i ed 5.4 g/m N. An u n f e r t i l i z e d con t ro l p l o t was a l s o i n c l uded . The exper imenta l des ign was a s p l i t p l o t w i th 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 ogen sources as the sub-p lo t s and fou r stages of growth (weeks of regrowth) as sub-sub-p l o t s . Samples were taken fou r t imes a t i n t e r v a l s of 3 weeks ( J u l y 4 - 5 , J u l y 25 - 26, August 15 - 16, and September 5 - 7 ) . The samples were obta ined by randomly p l a c i ng a meter quadrat frame i n each sub-p l o t and c l i p p i n g a l l the aboveground vege ta t i ve growth. The samples were taken to the l a b , d r i ed a t 60C and weighed. Dr ied samples were pooled f o r each t reatment , ground and ana lyzed i n dup l i c a t e f o r n i t r ogen by the procedure o f Nelson and Sommers (1973). On May 10, 1977, a l l p l o t s from the 1976 t r i a l s were c l i p ped except those tha t were t r ea t ed w i th NaNO^- 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 to ammonium and n i t r a t e sources of n i t r ogen noted i n the 1976 t r i a l s (see Table 7 . 6 ) . S t a t i s t i c a l ana lyses were done sepa ra te l y f o r each spec ies from each s i t e . 171 7 .1 .3 .2 Observat ions and r e s u l t s E f f e c t of n i t r ogen a p p l i c a t i o n on dry matter p roduc t i on: A p p l i c a t i o n o f n i t r ogen s i g n i f i c a n t l y ( P < 0.01) inc reased dry matter 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 ) . Dacty l i s glomerata was the on ly o l d f i e l d spec ies tha t d i d not respond to n i t r ogen a p p l i c a t i o n . The h ighest y i e l d r e s -ponse came from Pha l a r i s arundinacea (U.B.C. ) f o l l owed by Lo l ium perenne and Carex lyngbye i (Brunswick marsh). Ana l y s i s of va r iance showed a h i gh l y l i n e a r y i e l d inc rease w i th advancing stage of regrowth (Table 7 .7 ) . Quadrat ic responses were noted f o r Carex lyngbye i (Iona marsh), P h a l a r i s arundinacea ( U . B . C ) , and Carex lyngbye i (Brunswick marsh). Th is c u r v i l i n e a r r e l a t i o n s h i p 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 arundinacea (U.B.C.) and Carex  lyngbye i (Iona marsh) i n F igures 7.1 and 7.2 r e s p e c t i v e l y . E f f e c t of n i t r ogen source on dry matter p roduc t i on: In a l l cases there was no s i g n i f i c a n t d i f f e r en c e i n response between ammonium and n i t r a t e sources of n i t rogen a l though Table 7.6 shows some v a r i a t i o n i n response among the spec ies examined. E f f e c t of n i t r ogen a p p l i c a t i o n on N content i n the p l a n t s : N i t rogen a p p l i c a t i o n inc reased N content i n a l l the spec ies s tud i ed except Carex lyngbye i (Table 7 . 8 ) . Table 7.6 E f f e c t of Two Sources of Nitrogen F e r t i l i z e r on Dry Matter Production (g/m ). Species NH, Source* N0 o Source 4 J C o n t r o l C o n t r o l vs N Source Calam c_. ( P i t t marsh) Carex 1_. (Iona marsh) Carex 1_. (Bruns. marsh) R i a l , a. (Col . Farm) Ph a l . a. (U.B.C.) Pact, g l . (Col . Farm) L o l . p_. 284 - 29 372 - 50 471 - 39 301 - 45 577 - 31 392 - 39 411 - 18 298 - 15 336 - 21 388 - 29 293 - 35 549 - 20 490 - 50 415 - 27 255 - 19 262 - 28 224 - 34 213 - 15 228 - 36 427 - 28 187 - 30 NS NS NS Means are - 1 S.D. ** P ^  0.01 * D i f f e r e n c e between NH. and N0 o source not s i g n i f i c a n t i n a l l cases. 4 3 Table 7.7 E f f e c t of M a t u r i t y Stage on Dry Matter Production (g/m ). ro Species Age (Weeks) S i g n i f i c a n c e of Contrasts 3 6 9 12 L i n e a r Quadr. Re s i d u a l Calam c. ( P i t t marsh) 56 + 21 238 ± 3 5 369 + 42 453 + 29 ** NS NS Carex 1. (Iona marsh) 158 + 25 309 ± 4 2 452 + 28 375 + 35 ** ** NS Carex 1. (Bruns. marsh) 318 + 62 272 ± 1 5 404 + 41 450 + 28 ** ** NS Phal. a. (Col . Farm) 65 + 31 252 ± 2 3 344 + 33 416 + 61 ** NS NS Pha l . a. (U.B.C.) 245 + 41 467 ± 27 534 + 30 559 + 40 ** ** NS Dact. g l . (Col. Farm) 259 + 26 428 ± 6 2 484 + 60 573 + 25 ** NS NS L o l . p_. (Alaksen) 183 + 55 382 ± 5 3 422 + 41 364 + 28 ** NS NS * means - 1 S,D. ** 0.01 NS Not s i g n i f i c a n t 174 F igure 7 .1: E f f e c t s of Ma tu r i t y and F e r t i l i z e r N i t rogen on Dry Matter Product ion 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 igure 7.2: E f f e c t s of Ma tu r i t y and F e r t i l i z e r N i t rogen on Dry Matter Product ion of Carex lyngbye i i n Iona marsh. 177 5 0 0 0 3 6 9 12 W E E K S O F R E G R O W T H Table 7.8 E f f e c t of Nitrogen A p p l i c a t i o n on the N Content of the Shoots at Several Stages of Growth. Species 3 weeks 6 weeks 9 weeks 12 weeks % / 2 g/m % g/m2 % , 2 g/m % g/m2 Carex 1. (Iona marsh) No N l 1.5 1.7 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 Carex 1. (Brun. marsh) No N l 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 Calamag. c. ( P i t t marsh) No N l 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 P h a l a r i s a. (Col . Farm) No N l 3.4 3.2 1.9 2.3 2.2 3.0 4.9 7.9 1.6 2.5 3.7 10.1 • 1.8 2.4 6.1 10.9 Lolium p. (Alaksen) No N l 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 D a c t y l i s g. (Col . Farm) No N l 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 15.6 179 % N g ene r a l l y decreased w i th i n c r e a s i n g age of regrowth. I t ranged from a high of 3.6% f o r f e r t i l i z e d Dacty l i s glomerata a t 3 weeks to a low of 0.8% f o r Carex lyngbye i at 12 weeks of regrowth. In con tas t to %N, N y i e l d s (g/m ) i n the p lan ts g ene r a l l y i n -creased from 3 weeks to a t l e a s t 9 weeks. By the 12th week, a de c l i n e i n N y i e l d s was ev iden t i n Carex l y ngbye i , Lo l ium perenne and 2 Dacty l i s g lomerata . The h ighes t uptake o f t o t a l N was 15.6 g/m f o r Dactyl i s glomerata at 12 weeks of regrowth. Recovery of app l i ed n i t r ogen : Recovery o f app l i ed n i t r ogen i n the shoots was c a l c u l a t e d by 2 s ub 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 on t r o l p l o t s from tha 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 va lues are shown i n Table 7.9. In gene ra l , spec ies growing on a r ab l e o l d f i e l d s recovered a much l a r g e r p ropor t i on of app l i ed n i t r ogen than those growing on wet lands . Maximum recovery was 135% f o r P h a l a r i s arundinacea (at U.B.C.) wh i l e the l e a s t was 31.5% f o r Carex lyngbye i (a t Iona marsh). "Carry over" e f f e c t of n i t r ogen a p p l i c a t i o n : Regarding the ca r r y over e f f e c t of n i t rogen a p p l i c a t i o n , i t i s c l e a r from Table 7.10 tha t n i t r ogen app 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 dua l e f f e c t on the 1977 sp r ing growth. Moreover, date o f cut dur ing the prev ious year d i d not a f f e c t the 1977 s tand ing 180 Table 7.9 Apparent Recovery of Two Nitrogenus Fert i l i z e r s at 12 weeks Regrowth. NH. Source N0„ Source 4 2 3 2 7.1 g N applied/m 5.4 g N applied/m Species % N recovered % N recovered Calam. 31.0 40.7 (Pitt marsh) Carex 1. 39.4 31.5 (Iona Is.marsh) Carex 1. 69.0 59.3 (Brun.marsh) Phal. a. 70.4 85.2 (Col.Farm) Phal. a. 111.3 135.2 (UBC) Dact.gl. 92.9 116.1 (Col.Farm) Lol. p_. 85.9 ' 94.4 (Alaksen) Table 7.10 Summary of the A n a l y s i s of Variance of the Carry Over E f f e c t of Nitrogen Applied i n 1976 on 1977 Standing 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 Source of V a r i a t i o n Df F e r t i l i z e r OVS NH, 1 NS NS NS NS NS NS 4 E r r o r (A) 4 3 NS NS NS NS NS NS 3 NS NS NS NS NS NS Date F e r t x Date E r r o r 12 T o t a l 23 — Means ± 1 S.D. - 172 + 53 378 ± 98 347 ± 68 673 ± 147 297 ± 154 213 ± 46 NS Not s i g n i f i c a n t 182 crop y e i l d s . Large standard dev i a t i ons from the means (averaged over three r e p l i c a t e s , two l e v e l s o f n i t r ogen and fou r dates) were recorded i n d i c a t i n g marked spec ies and s i t e v a r i a t i o n s . 7 .1 .3 .3 D i s cuss i on E f f e c t of n i t r ogen a p p l i c a t i o n on dry matter p roduc t i on : A p p l i c a t i o n of n i t r ogen inc reased dry matter y i e l d s o f a l l the spec ies a l though the magnitude o f response v a r i e d cons i de rab l y w i th s i t e . Except f o r the Dacty l i s g lomerata s i t e , a s i g n i f i c a n t response was recorded i n a l l 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 ogen s ta tus i n t h e i r s ub s t r a t e s . The Dactyl i s glomerata s i t e r e ce i ves manure f r e -quent ly making i t r e l a t i v e l y more f e r t i l e than the other o l d f i e l d s i t e s . No s i g n i f i c a n t response was recorded at the P i t t and Iona marshes i n d i c a t i n g an adequate supply o f a v a i l a b l e n i t r ogen in the s ub s t r a t e s . A h i gh l y o rgan i c s i t e such as the P i t t marsh would be expected to have l a rge concen t ra t i ons o f a v a i l a b l e n i t r ogen s i n ce i no rgan i c n i t rogen i s a f un c t i on of o rgan i c matter (Jackson 1958). The t i d a l marsh s i t e s have f a r l e s s o rgan i c matter account ing i n pa r t f o r the p o s i t i v e response recorded a t the Brunswick marsh. Carex  lyngbyei i n Iona marsh d id not respond presumably because t h i s marsh rece i ves a l o t of n u t r i e n t s from nearby sewage o u t f i l l . Time o f c u t t i n g d i d i n f l u ence the magnitude o f response to a pp l i e d n i t r o gen . 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 tha t there was de layed response by Carex lyngbye i and Pha l a r i s arundinacea (U.B.C. ) 183 and secondly t ha t towards the end of the growing season, senescence and m o r t a l i t y l o sses f a r out-weighed the e f f e c t of the app l i ed n i t r ogen r e s u l t i n g i n an o v e r a l l r educ t i on i n response. E f f e c t of n i t r ogen source on dry matter p roduc t i on : There was no d i f f e r en c e i n y i e l d response between NH^ and NOg sources of n i t r o gen . Th is was unexpected s ince d i f f e r en c e s between the two sources are known to e x i s t ( e . g . Nowakowski and Cunningham 1966, T y l e r 1967). P l o t s between treatments were gene r a l l y c l o se together so tha t l a t e r a l movement o f f e r t i l i z e r app l i ed cou ld have accounted f o r t h i s d i s c repancy . E f f e c t of n i t rogen a p p l i c a t i o n on N content i n the p l a n t s : N i t rogen a p p l i c a t i o n inc reased N percentages i n a l l spec ies s tud ied a l though the magnitude o f response va r i e d w i th s pe c i e s . Tota l quan t i t y o f N i n the p l an t s (as g/m ) i n i t i a l l y inc reased i n response to app l i e d n i t r ogen reach ing a peak a t about the n in th week of regrowth f o r most s pe c i e s , a f t e r which i t d e c l i n e d . These trends p a r a l l e l e d changes i n dry matter y i e l d s r a t he r than % N found i n the p l a n t s . Recovery of a pp l i e d n i t r ogen : The r a the r low n i t r ogen recovery va lues (31 - 59.3%) recorded i n the wet land s i t e s may be a t t r i b u t e d to n i t rogen l osses due to l each ing 184 and d e n i t r i f i c a t i o n in*the impe r f e c t l y dra ined s o i l s . Losses of app l i ed n i t r ogen appeared to be minimal i n the arab le o l d f i e l d s and recovery values in excess o f the i n i t i a l q u a n t i t i e s of app l i e d n i t r ogen were recorded in Pha l a r i s arundinacea (U.B.C. ) and Dacty l i s glomerata (Table 7. Such high values probably r e f l e c t e d low l each ing 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 rgan i c mat ter s t imu l a t ed 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 prev ious y ea r . "Carry over" e f f e c t o f n i t r ogen 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 ogen d i d not i n f l u ence the dry matter product ion the f o l l ow i ng yea 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 app l i ed n i t r ogen the prev ious yea r o r l o s s o f any r e s i dua l n i t r ogen through l each ing and d e n i t r i f i c a t i o n . 7.2 Leaching o f Nu t r i en t s from the Stand ing 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 each ing i s probably as important as n u t r i e n t uptake i n regard to p l an 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 in many ecosystems. Tukey and Mecklenburg (1964) found tha t r a d i o a c t i v e leachates from f o l i a g e were reabsorbed by roots and t r an s l o c a t ed to aboveground p a r t s . They po in ted out t ha t l each ing i s a l s o important i n compet i t ion between p lan ts and i n the development o f p l a n t a s so c i a t i on s and tha t the r e c y c l i n g of n u t r i e n t s has important imp l i c a t i o n s i n p l a n t n u t r i t i o n . 185 Szczepanska and Szczepanski (1973) were ab le to leach measurable amounts of NHg, NOg, d i s s o l v ed o rgan i c N, P, K, Ca and Na from var i ous lakeshore emergent vege t a t i on . They repor ted tha t potassium was the most Teachable. Barsdate and P ren tk i (1972) repor ted a growing season l o s s o f approx imate ly 0.4 mg P/m from Carex a q u a t i l i s i n some a r c t i c tundra marshes. Th is amounted to approx imate ly 0.5% of the ac tua l aboveground s tand ing c rop . Boyd (1970b) and Mason and Bryant (1975) observed tha t l each ing o f n u t r i e n t s from wet land vege ta t i on i s e s p e c i a l l y r ap i d soon a f t e r shoot death. Var ious aspects of l each ing from l i v i n g s tand ing crops are examined under t h i s s e c t i o n . Oppor tun i t i e s f o r Teaching o f emergent vege ta t i on appear to be e s p e c i a l l y g reat i n the t i d a l marshes where some emergents may be f l ooded tw ice a day. R i s i ng and f a l l i n g water l e v e l s i n the f reshwater 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 stand we l l above the water l e v e l . 7.2.1 Ma t e r i a l s and methods-The leaves from f i v e spec ies were harvested on 23 August 1977 and taken to the lab where subsamples were d r i ed a t 105 C and weighed to ob ta i n percentage dry mat te r . The d r i ed l e a f ma te r i a l was s t o r e d , l a t e r ground i n a Wi ley m i l l and the ash content determined by i g n i t i o n a t 550 C. On 24 August, 20 - 30 g (80% average dm) of f r e sh l e a f ma te r i a l were weighed and suspended i n 800 ml of d i s t i l l e d water i n p l a s t i c c on t a i ne r s . E igh t con ta ine r s were a l l o c a t e d to each spec ies and the 186 con ta ine r s were p laced on a bench i n a complete ly random arrangement. The exper iment was conducted a t room temperature f o r a t o t a l o f 96 hours. A f t e r l each ing f o r 12 hours , 4 p l a s t i c con ta ine r s f o r each spec ies 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 determined. For ease of hand l i ng , the leachate was evaporated to 50 ml and the e x t r a c t s were t r a n s f e r r e d to weighed c r u c i b l e s , f r ee ze d r i e d and weighed. The average weight of the res idues was d i v i d ed by the c a l -cu l a t ed dry weight of l e a f mate r i a l to ob ta i n the amount o f l eachate expressed as mg/g l e a f dry we ight . The ash content of the leachate was determined by i g n i t i o n a t 550 C f o r 6 hours. The remaining se t o f con ta ine r s was removed a f t e r 96 hours o f l each ing and subjec ted to a s i m i l a r procedure. S ince the stomata appear to be a major avenue f o r l each ing o f n u t r i e n t s i n l i v i n g v ege t a t i o n , we dec ided to check the leaves of some emergent spec ies f o r presence or absence o f stomata. Simple methods o f l e a f p repara t i on were l a r g e l y adopted from Johansen (1940). In most cases , the su r faces requ i r ed f r e e hand c u t t i n g ( e . g . S c i r pus  v a l i d u s ) to ob ta in comparable areas under the microscope. The l e a f sur faces were gene r a l l y covered w i th immersion o i l before t ak i ng stomata! counts . 7.2.2 Observat ions and r e s u l t s Table 7.11 shows tha t a cons i de rab l e amount o f ma te r i a l was d i s s o l v ed i n the f i r s t 12 hours. Moreover, prolonged du ra t i on o f 187 T a b l e 7 .11 T o t a l L e a c h a t e (mg/g L e a f D r y W e i g h t ) f r o m S e l e c t e d S p e c i e s . ' L o c a t i o n S p e c i e s 12 h r s 96 h r s P i t t marsh I I I I P h a l a r i s a r u n d i n a c e a C a r e x s i t c h e n s i s B r u n s w i c k m a r s h C a r e x l y n g b y e i 4 4 - 3 4 6 - 5 3 2 - 3 6 3 - 4 5 3 - 3 6 2 - 3 A l a k s e n o l d f i e l d L o l i u m p e r e n n e  D a c t y l i s g l o m e r a t a 40 - 4 64 - 4 53 ± 4 8 0 - 3 MEAN 45 ± 3 62 - 3** * 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 and 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 . 188 l each ing s i g n i f i c a n t l y ( P < 0.01) i nc reased the t o t a l quan t i t y o f d i s s o l v ed m a t e r i a l . These f i n d i n g s are i n agreement w i th those repor ted by Nykv i s t (1959). The h ighes t i nc rease between the two per iods was recorded i n Carex lyngbye i and Dacty l i s g lomerata . The l eachate was p a r t i t i o n e d i n t o o rgan i c and i no rgan i c f r a c t i o n s and the r a t i o s are g iven i n F igure 7 .3 . In a l l the spec ies s t ud i e d , the i no rgan i c f r a c t i o n was l e s s than 50% of t o t a l ma te r i a l l eached . Carex lyngbye i and Lo l ium perenne had a h igher p ropor t i on of minera l matter i n the l eachate compared to the o ther spec i e s . The percentage of s tand ing crop ash recovered i n the leachate over the e n t i r e exper imenta l per iod i s g iven i n F igure 7.4. P h a l a r i s  arundinacea l o s t 6.2% of i t s s tand ing crop ash wh i l e the o ther spec ies l o s t between 2 to 2.8%. Table 7.12 g ives es t imates of stomatal numbers on the l e a f su r faces of va r i ous wet land spec i e s . Of i n t e r e s t i s the v a r i a t i o n i n stomatal numbers i n the spec ies examined. No stomata were observed on the leaves of Zostera mar i t ima , an aquat i c s pe c i e s . Among the emergents, stomatal numbers ranged from 15 on Bromus s i t c h e n s i s to 350 on Dacty l i s s t r i c t a l e aves . Stomatal numbers were g ene r a l l y even ly d i s t r i b u t e d on the upper and lower l e a f su r faces of the p l a n t s . 7 .2.3 D i s cuss i on The r e s u l t s showed tha t a s ub s t an t i a l amount o f p l an t ma te r i a l can be l o s t through l e a ch i ng . The general d e c l i n e i n n u t r i e n t content w i th ma tu r i t y repor ted 189 F igure 7.3: Rat io o f Inorgan ic to Organic Mat ter Leached from the Shoots o f 3 Emergents and 2 Arab le Old F i e l d Spec i es . o en S P E C ! E S P H A L A R I S C A R E X S. C A R E X L. L O L I U M D A C T Y L I S i n o r g a n i c /////////\ o r g a n i c zzzzzzzzzzzzzz zzzzzzzzzzzzzza: f /1 it 1111\ o 0.5 191 F igure 7.4: Percent of Standing Crop Ash Recovered i n the Leachate. r o O > O > > o . r- 7J H — m m < C X X l -M l r-(/) • > r-> "0 m O m "0 N m o m 2 m > O m O \ \ \ \ \ \ \ 00 193 Table 7.12 Estimates of Stomatal number Observed under 50 x M a g n i f i c a t i o n f o r Several Wetland Species. number of stomata Species on upper surface on lower surface Zostera maritima 0* 0 S a l i c o r n i a v i r g i n i c a 20 20 Scirpus v a l i d u s 175 175 Scirpus paludosus 150 150 Elymus vancouveriensis 90 60 Juncus b a l t i c u s 150 150 Carex lyngb y e i 200 200 Typha l a t i f o l i a 250 250 Bromus s i t c h e n s i s 15 15 D i s t i c h l i s s t r i c t a 350 350 * Values are averages from s e v e r a l l e a f s e c t i o n s . 194 i n Sec t i on 7.1 cou ld be a t t r i b u t e d i n pa r t to such l o s s e s . The h igher p ropor t i on of o rgan i c to i no rgan i c component found i n the leachate i s c ons i s t en t w i th the f i n d i n g s o f Dalbro (1955) who c a l c u l a t e d carbohydrate l o s ses as h igh as 800 kg/hec tare/year i n l i v i n g vege t a t i on . Leached organ i c so l ub l e s may be an important food source to organisms and decomposers a s soc i a t ed w i th the marshes. The g ene r a l l y low minera l content found i n the leachate of spec ies from P i t t marsh probably r e f l e c t s t h e i r inherent low minera l content wh i l e the high va lues f o r Carex lyngbye i might be a r e s u l t o f the r e l a t i v e l y high ash content of t h i s spec ies as we l l as the depos i t i on of extraneous s i l t on the shoot sur faces by t i d a l a c t i v i t y . The nature of the l each ing process i s probably f a r more complex than i t appears from t h i s exper iment. High r a i n f a l l such as encountered in the coas ta l areas of B r i t i s h Columbia would tend to leach much of the s o l ub l e c on s t i t u en t s i n p l a n t s . Such l osses would be expected to 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 an t c h a r a c t e r i s t i c s may a l so be imp l i c a t ed i n the l each ing phenomenon. Tukey (1970) c i t e d numerous examples o f p l an t s from which l each ing l osses were r e l a t e d to the w e t t a b i l i t y of l e a f s u r f a c e s . Mar t in and Ba t t (1958) found tha t the amount of wax on the sur face of leaves i n f l uenced 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 s u s c e p t a b i l i t y t o l e a c h i n g . The stomata would appear to be major avenues by which l each ing occurs from l e a f s u r f a c e s . That stomata are present i n emergent spec ies i n s ub s t an t i a l numbers was observed i n our s t u d i e s , a l though i t should be noted tha t no stomata were recorded i i i Zos te ra mar i t ima , an 195 aqua t i c s pe c i e s . The r o l e o f stomata i n l each ing of wet land p l an t s awai ts f u r t h e r c l a r i f i c a t i o n . Cons iderab le spec ies v a r i a t i o n i n stomatal number, d i s t r i b u t i o n and shape were observed i n our 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 to environmental f a c t o r s and i t would appear tha t the l each ing process should be more mean ing fu l l y examined along such g r ad i e n t s . 196 8. GENERAL DISCUSSION AND RECOMMENDATIONS The landscapes o f B r i t i s h Co lumbia, prominent ly mod i f i ed by g l a c i a t i o n , present many l a r ge and v a r i e d wet lands . Rough topography, and i n many p laces cons i de rab l e p r e c i p i t a t i o n and modest evaporat ion have l ed to the c r e a t i o n of marshes, meadows, s loughs and o ther types of wet land i n a l l pa r t s of the P r ov i n ce . These wetlands have not been we l l d e l i n ea t ed nor c l a s s i f i e d a l though they are being r a p i d l y a l i e n a t e d and mod i f i ed 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 developments. Some f ede ra l and p r o v i n c i a l agencies are c u r r e n t l y undertak ing i nven to ry 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 . 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 purposes, t h i s study was undertaken i n which predominant ly p lant -med ia ted processes 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 to the emergent vege ta t i on o f the marshes o f south western B r i t i s h Columbia. The study areas were l o ca ted i n the P i t t marsh, Brunswick marsh and Iona I s l and marsh. W i th in each marsh, the study was f u r t h e r l i m i t e d to a few spec ies and a few v a r i a b l e s . Some a rab l e o l d f i e l d s i t e s were a l s o i nc luded f o r compar ison. S tud ies o f p lant-med ia ted processes 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 the r broad i n nature s i n ce so l i t t l e i s known o f p l an t processes i n B r i t i s h Columbia wet lands , and s ince wetlands are so w ide 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 are so h i gh l y v a r i e d i n s i z e and na tu re . 197 8.1 P r o d u c t i v i t y o f the Emergent Vegeta t ion S tud ies o f pr imary p r o d u c t i v i t y are o f paramount importance s i n ce they i n vo l ve e s t ima t i on of energy and n u t r i e n t p o t en t i a l o f wet land systems; they are a l s o c a r d i na l as a too l i n t h e i r management. Our p r o d u c t i v i t y es t imates 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 har -ves t s o f aboveground shoots . Desp i te d e f i c i e n c i e s i n methodology, severa l important f ea tu res may be d i sce rned from the s tudy . Peak s tand ing crops were gene r a l l y high a l though there were tremendous v a r i a t i o n s between spec ies as we l l as between s i t e s . The lowest peak s tand ing crop was 316 and the h ighes t was 1928 g/m dry matter f o r Sc i rpus acutus and Pha l a r i s arundinacea r e s p e c t i v e l y . The nature o f the environmental f a c t o r s i n f l u e n c i n g dry matter p roduct ion i s complex va ry ing from marsh to marsh and from s i t e to s i t e w i t h i n the marsh. For the mar i t ime wet land communit ies, c l i m a t e , water regime, s a l i n i t y and subs t r a t e n u t r i e n t s t a tus appear to be the major f a c t o r s . Adequate water supp ly and average m i l d - coo l temperatures favour pho tosyn the 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 pa r t o f the year account ing f o r the gene ra l l y h igh s tand ing crops recorded i n the s tudy. Water depth and du ra t i on o f f l o o d i n g have cons i de rab l e i n f l u en ce on spec ies product ion and d i s t r i b u t i o n i n wet lands . Continuous f l o o d i n g l i m i t s p l an t growth by water logg ing roots and to some extent by reduc ing l i g h t . Our f i n d i n g s gene r a l l y agreed w i th t h i s c on t en t i on . In the P i t t marsh, Sc i rpus acutus and Equisetum f l u v i a t i l e growing i n s tand ing water most o f the year had the lowest s tand ing crops wh i l e P ha l a r i s arundinacea from a l e s s mois t area produced the h ighes t dry mat te r . S i m i l a r obser -198 va t i ons were made i n the Brunswick marsh; Festuca arundinacea and Typha  l a t i f o l i a , growing i n areas where high t i d e s reach on ly o c c a s i o n a l l y and where the waters are l e s s s a l i n e , had h igher s tand ing crops than Carex lyngbye i which grows i n areas a lmost d a i l y covered by t i d a l wa te rs . In the b rack i sh environment s a l i n i t y l e v e l s are u s ua l l y qu i t e low but they f l u c t u a t e i n response to o the r environmental v a r i a b l e s such as magnitude o f f r e s h e t and w in te r r a i n s and t h i s may impose s t r e s s e s on p l an t s which are not normal ly sub je c t to extremes. A l though subs t ra te s a l i n i t i e s . v a r y on a d a i l y bas i s i n the F raser d e l t a fo reshore accord ing to t i d e he i gh t s , du ra t i on of f l o o d i n g and amount of r a i n f a l l o r evapor-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 . Th i s e f f e c t would appear, however, to be l e s s i n the b rack i sh marsh than i n the ne ighbour ing high s a l i n i t y s a l t marshes. Subs t ra te 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 of the marshes were not a major sub je c t of t h i s s tudy, but the amount and nature of the sediments depos i ted should r e f l e c t the quan t i t y of n u t r i e n t s present i n the marshes. The P i t t marsh, w i th impeded dra inage system and h i gh l y v a r i a b l e water l e v e l s , appears to r e ce i ve l e s s n u t r i e n t s from ad j o i n i ng areas than the t i d a l marshes. The high q u a n t i t i e s o f r e a d i l y a v a i l a b l e n i t r ogen i n the P i t t marsh, ev ident 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 igh o rgan i c matter content of the subs t r a t e as we l l as man's recent water con t ro l e f f o r t s . There i s l i t t l e doubt t ha t t h i s marsh would q u i c k l y become a bog as a r e s u l t o f dyk ing; as y e t on ly a smal l par t o f the marsh can be so c l a s s i f i e d . 199 Par t o f the v a r i a t i o n i n s tand ing crop i n the marshes may be a t t r i b u t e d to innate c h a r a c t e r i s t i c s of the s pe c i e s . Cons iderab le d i v e r s i t y i n p l an t form i s to be encountered i n f reshwater and b rack i sh water marshes. Many of the morpholog ica l f e a t u r e s , wh i l e being l a r g e l y adapt ive to the wet land environment, may a l s o be imp l i c a t ed i n the photosynthe t i c f unc t i ons o f the p l a n t . Some spec ies ( e . g . Carex l yngbye i ) develop f u l l pho tosyn the t i c canopy wh i l e o thers ( e . g . Sc i rpus acutus) occur on ly t h i n l y i n the marshes. The round non-bladed shoots o f rushes (Sc i rpus spp.) and the t r i a n g u l a r shoots of sedges (Carex spp.) may i n some way be r e l a t e d to pho tosyn the t i c e f f i c i e n c y . The e r e c t nature o f Typha l a t i f o l i a leaves may be an " a s se t " to t h i s spec ies i n terms o f a b i l i t y to q u i c k l y emerge above the water l e v e l . Tremendous 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 a l s o noted i n the marsh spec ies s t u d i e d . Al though these stomatal v a r i a t i o n s appear to be r e l a t e d to env i r on -mental g r ad i e n t s , they should have some bear ing on the pho tosyn the t i c c apac i t y of the d i f f e r e n t s pe c i e s . I t i s unfor tunate t ha t very l i t t l e i n f o rmat i on c u r r e n t l y e x i s t s r e l a t i n g a l l these impress ive morpho log ica l f ea tu res o f wet land p l an t s to t h e i r pho tosyn the t i c a b i l i t y and hence t h e i r p r o d u c t i v i t y . The r e l a t i o n s h i p s undoubtedly deserve f u r t h e r i n v e s t i g a t i o n . S i n g l e s tand ing crops data were complemented w i t h data from mu l -t i p l e ha rves t s . Sequent ia l ha rves t i ng showed tha t most spec ies exper ienced r ap i d growth i n the sp r i ng 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 inc reased w i th the onset o f c o l d weather i n the f a l l . Time of peak dry matter product ion d i f f e r e d markedly w i th s pe c i e s . 200 Such d i f f e r en ce s probably r e f l e c t the mode of adapta t ion by the spec ies to t h e i r environment. In some spec ies sp r i ng and e a r l y summer are c ha r a c t e r i z ed by high growth r a t e s f o l l ow i n g e a r l y es tab l i shment of pho tosyn the t i c shoots . Carex s i t c h e n s i s f o r example produces shoots i n w in te r and these shoots commence very a c t i v e growth w i th the onset o f good weather. As the growing season p ro -gresses such spec ies may possess compet i t i ve advantages i n terms of l i g h t and n u t r i e n t s . E a r l y es tab l i shment i s p o s s i b l e presumably through m o b i l i z a t i o n of food reserves from belowground to aboveground p a r t s . In some marsh s pe c i e s , changing water l e v e l s a l s o seems to i n f l u en ce i n i t i a t i o n o f a c t i v e growth. Sc i rpus acu tus , f o r example, commences growth very l a t e i n the growing season when the water l e v e l has dropped cons i de rab l y and cond i t i on s f o r growth have improved. Many of the pheno log ica 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 i n t ime of peak product ion o f the va r i ous marsh spe c i e s . In conc lu s i on i t should be po in ted out t ha t f a c t o r s a f f e c t i n g wet-land p r o d u c t i v i t y are complex, some being i nheren t i n the p l an t and others i n the environment. In such c on s i d e r a t i o n s , temporal and seasonal aspects o f p l an t development i n c l u d i n g t ime of shoot emergence, presence o f overwintered shoots and shoot m o r t a l i t y should be taken i n t o account. Gorham and Sommers (1973) and Bernard and Gorham (1978) s t r e s sed tha t spec ies d i s p l a y i n g cons i de rab l e green phytomass i n w in te r may have a compet i t i ve advantage because green w in te r shoots can begin growth as soon as cond i t i ons become f avou rab l e . Moreover, these green w in te r shoots o f ten c o n s t i t u t e the main aboveground organs tha t 201 grow up to the t ime of maximum stand ing c rop . Ignorance of a l a rge w in te r s tand ing crop would cause one to overes t imate the net pr imary produc t ion of wet lands . The above workers a l s o po in ted out tha t the very high shoot m o r t a l i t y a s so c i a t ed w i th many wet land spec ies may r e s u l t i n underest imat ing t h e i r net p roduc t i on . Th is m o r t a l i t y w i l l a l so exe r t cons ide rab l e i n f l u ence upon n u t r i e n t c y c l i n g i n wet lands . I t should be po s s i b l e to monitor these pheno log ica l changes by tagg ing i n d i v i d u a l shoots and f o l l ow i ng t h e i r course o f development through the growing season. Undetected l o s ses o f green growth r e s u l t i n g from consumer a c t -i v i t i e s i s a common e r r o r a s soc i a t ed w i th pr imary product ion es t imates de r i ved from m u l t i p l e ha rves t s . On the F raser d e l t a marshes, some of the green shoots of Carex lyngbyei were s pa r i n g l y nipped by widgeon and o ther na t i ve geese and l o c a l heavy use of Sc i rpus americanus shoots i n w in te r have been documented f o r the F raser d e l t a t i d a l marshes (Burgess 1970 and Burton 1977). S u p e r f i c i a l examinat ions of the P i t t marsh spec ies showed f a i r l y l a rge numbers of phytopathogens and phytophagus i n s e c t s . A l though g raz ing and s i m i l a r a c t i v i t i e s seem to be r e l a t i v e l y unimportant i n the wetlands of south western B r i t i s h Columbia, the magnitude o f such l o s ses have not been a c cu r a t e l y q u a n t i f i e d . I t was shown i n our s t ud i e s t ha t up to 85 percent o f the t o t a l p roduct ion o f marsh vege ta t i on may be belowground. Th is obse rva t i on not on ly r a i s e s new fundamental ques t i on s , but t ends , i n p r o d u c t i v i t y e s t ima tes , to s h i f t the emphasis from aboveground to belowground i n v e s t i g a t i o n s . The separa t i on o f l i v i n g from dead po r t i ons of the underground organs do present cons i de rab l e d i f f i c u l t i e s . One technique 202 tha t may be use fu l i nvo l ves exhaust ing belowground reserves and measuring the e t i o l a t e d shoots under standard temperature and mo is ture c ond i t i on s (Marx 1963). Add i t i o na l i n fo rmat i on on sampling below-ground biomass i s prov ided by Ga l l agher (1974), V a l i e l a et^aj_. (1976) and de l a Cruz and Hackney (1977). 8.2 D i s p o s i t i o n of Emergent Vegeta t ion I t was po inted out i n Sec t i on 5 t ha t the phytomass produced as a r e s u l t of photosynthes is may be d isposed through routes conven ien t l y des ignates as: (1) the g raz ing r ou te , (2) accumulat ion r ou t e , and (3) the d e t r i t a l r ou te . A l though the three routes appear to be common to most wet lands , the r e l a t i v e importance of each would seem to vary from wetland to wet land . Our r e s u l t s , based l a r g e l y on obse r va t i on s , i n d i c a t e d tha t the f i r s t o f these routes i s r e l a t i v e l y unimportant i n the f reshwater and b rack i sh t i d a l marshes of south western B r i t i s h Columbia. Any g raz ing o f the l i v i n g vege ta t i on i s c a r r i e d out ma in ly by gas t ropods , earthworms, i n se c t s and r e s i d en t and migrant wa te r f ow l . Large v e r -tebra tes are r a r e i n the marshes. I t should be noted tha t a l though very l i t t l e o f the mar i t ime emergents pass v i a the g raz ing r ou t e , many of the i n t e r i o r meadows of B r i t i s h Columbia are h e a v i l y grazed by both na t i v e and domestic ungu la tes . The meadows are a l s o harvested f o r hay. The main reasons f o r the minimal g raz ing o f the mar i t ime marshes are s t i l l u n c e r t a i n . Pos s i b l e p l an t f a c t o r s l i m i t i n g g raz ing are d i scussed i n Sec t i on 8 .3 . Any f u t u r e i n v e s t i g a t i o n of the causes 203 should i n c l ude animal experiments i f a f u l l e r understanding o f the p l an t - he rb i vo r e i n t e r a c t i o n s i s to be ach ieved . A comparat ive study o f the c oa s t a l and i n t e r i o r emergents should a l s o a i d i n i d e n t i f y i n g the a n t i - h e r b i v o r e f a c t o r s . The shoots of emergent vege ta t i on u s u a l l y en te r the l i t t e r com-partment a f t e r senescence and death . Some of the f a l l e n l i t t e r may be broken down by phys i c a l f o r ces such as t i d e and w ind , some by i b i o l o g i c a l f o r ces 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 exported to other hab i t a t s nor used by consumers accumulates i n the s ub s t r a t e . Organic matter accumulat ion was a d i s t i n c t f ea tu re of the marshes s t u d i e d . In the P i t t marsh, the subs t r a t e was gene r a l l y peaty and o rgan i c matter accumulat ion appeared to be f a i r l y uni form over l a r ge a reas . Less o rgan i c matter accumulat ion was noted i n the t i d a l marshes. Moreover, the1 d i s t r i b u t i o n and th i ckness of phytomass accumulat ion i n the t i d a l marshes v a r i e d cons i de rab l y even over very sho r t d i s t a n c e s . In the t i d a l marshes, much of the a e r i a l growth i s e v en t ua l l y i degraded and exported to other h ab i t a t s so tha t any o rgan i c matter accumulat ing jin the s o i l p r o f i l e would be expected to be of under-ground o r i g i n . In the P i t t marsh, accumulat ion f a r outweighs expor t and the o rgan i c matter accumulated o r i g i n a t e s from a e r i a l shoots as i we l l as from belowground organs. Many aspects of accumulat ion pa t t e rn s t i l l remain to be s tud ied i n the marshes of south western B r i t i s h Columbia. The long term e f f e c t s o f accumulat ion on sed imentat ion and system geomorphology should be p a r t i c u l a r l y usefu l i n understanding the f unc t i ons of these marshes. 204 A l t h o u g h | s i g n i f i c a n t o rgan i c matter accumulat ion takes p lace i n the P i t t and F raser d e l t a marshes, the o l d growth data presented i n t h i s r epo r t demonstrate, t ha t a l a rge po r t i on of the phytomass p ro -i duced i n these systems may enter the d e t r i t a l route through decomp-o s i t i o n . Decomposit ion 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 ch i n g , phys i ca l and b i o l o g i c a l f r agmenta t i on . These processes are i complex and t h e i r r o l e s are poor l y understood i n most wet land systems. Our s t u d i e s , a l though broad i n na tu re , i d e n t i f i e d some o f the env i r onmen ta liand p l an t f ea tu res p e r t i n en t to gross decomposi t ion processes . ; Much of the f ragmentat ion o f p l an t ma te r i a l i n the t i d a l marshes i s e f f e c t ed by phys i ca l f o r ces such as w ind, 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 matter i s exported from s i t e as i t forms. The a c t i o n of these f o r ces i s by no means uni form and l o c a l accumulat ion o f undecomposed p l an t ma te r i a l i s not uncommon i n the t i d a l marshes. Phys i c a l f o r c e s o f communition are f a r l e s s no t i c eab l e i n the P i t t marsh where much of the organ ic matter accumulates i n s i t u . Dead Sc i rpus  acutus shoots may stand e r e c t f o r seve ra l years before they are broken down and i nco rpo ra ted i n the sub s t r a t e . Examination of the shoot s u r -faces w i th scanning e l e c t r on microscope showed more abras ion i n the Brunswick marsh spec ies than i n the P i t t marsh spec i e s ; much o f the abras ion undoubtedly a t t r i b u t a b l e to t i d e s , s i l t and o ther p a r t i c l e s moving w i th f r e s h e t . Temperature i s a very s i g n i f i c a n t f a c t o r i n decomposi t ion p rocesses . Seasonal t rends 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 th changes i n ambient temperature. Decomposit ion ra tes were on the whole lower i n 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 exper iences lower mean monthly temperatures compared to the F raser de l t a fo reshore where the ocean has a moderating e f f e c t on the tem-perature regime. Lower s o i l temperatures were probably r e s p o n s i b l e , i n p a r t , f o r the lower decomposit ion r a t e s recorded i n bur ied l i t t e r bags compared to those p laced on the subs t r a t e su r f a ce . Bes ides temperature, low decomposit ion ra tes i n the bur i ed l i t t e r bags cou ld be a t t r i b u t e d to low oxygen l e v e l s below the s u r f a c e . Anaerobic decomposit ion i s c a r r i e d out by o b l i g a t e and f a c u l t a t i v e anaerobes which are f a r l e s s " e f f i c i e n t " than aerobes. As p e r i o d i c i f l o od i ng i s c h a r a c t e r i s t i c o f most wet lands , the anaerob ic f a c t o r i s important not! on ly f o r decomposit ion belowground but a l s o f o r decom-p o s i t i o n on the subs t ra te su r f a ce . A l though anaerobos is i s a major f a c t o r f o r the gene ra l l y lower ra tes of decomposit ion i n wet lands com-i pared to mesic h a b i t a t s , s u b s t a n t i a t i n g data i s r e a l l y qu i t e l i m i t e d . Some of |the observed v a r i a t i o n i n decomposit ion r a te s cou ld a l s o be a t t r i b u t e d to innate spec ies c h a r a c t e r i s t i c s . Of a l l the spec ies s t ud i e d , Dacty l i s glomerata was the most r e a d i l y decomposed. I t was f o l l owed by Carex l y ngbye i , P h a l a r i s a rund inacea, Sc i rpus acu tus , Juncus e f fusus and Carex s i t c h e n s i s i n tha t o rde r . These d i f f e r en ce s i would seem to r e f l e c t the chemical compos i t ion of the s pe c i e s . Less f i b r ou s spec ies would be expected to break down more r e a d i l y than h i gh l y f i b r ou s spec i e s . In our decomposit ion s t u d i e s , young f l e s h y shoots were a s soc i a t ed w i th h igher ra tes than the more f i b r o u s ove r -w in tered shoots . Some spec ies i n the F raser d e l t a marshes, e . g . S a l i c o r n i a mar i t imus tend to possess f l e s h y succu len t shoots , apparen t l y i 206 as an adapt ive f ea tu re to the s a l i n e environment. During decomposit ion these f l e s h y par t s are r a p i d l y l o s t l e av i ng h i gh 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 en t r a l c o re . Most P i t t marsh spec ies took longer to decompose than the Brunswick marsh spec ies probably because of t h e i r high f i b r e content . Thus the a e r i a l shoots of the P i t t marsh spec ies remain l a r g e l y undecomposed c o n t r i b u t i n g to the peaty ho r i zon of the subs t ra te p r o f i l e f a r more than those from the Brunswick marsh s pe c i e s . Much i n fo rmat i on on decomposit ion processes can be obta ined through l i t t e r bag s t u d i e s . Choice of bags wi th proper mesh appears to be c r i t i c a l f o r accurate r e s u l t s . A ' c oa r se ' mesh may cause s i g -n i f i c a n t l o s ses o f p l an t fragments to occur through the bags whereas a ' f i n e ' mesh, may exc lude decomposer animals from the bags. The scanning e l e c t r o n microscope techn ique f o r s tudy ing p l a n t su r faces a l s o shows cons ide rab le .p romise i n decomposit ion s t u d i e s . I f used i n con junc t i on w i th l i t t e r bags, i t should prov ide answers to such quest ions as: what changes take p lace on p l an t sur faces dur ing i n i t i a l decomposit ion? What happens to the c u t i c l e ? What happens to 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 techn ique (Burkho lder and Borns ide 1957) should a i d i n s tudy ing the f i n e r aspects of decomposit ion processes . Al though the technique i s not w i thout i t s aspects of 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 tud i e s showed tha t the method g ives r e s u l t s comparable to those obta ined us ing l i t t e r bags. Bes ides r e f i n i n g of the techn iques , there are many areas of decomposi t ion which r equ i r e immediate a t t e n t i o n . In a d d i t i o n to the spec ies s t ud i e d , there are many other spec ies which occur i n s i g n i f i c a n t p ropor t i ons i n the marshes to mer i t s tudy . Very l i m i t e d data i s 207 a v a i l a b l e to date on the decomposit ion of roots and rh izomes. Our s tud i e s have shown tha t underground phytomass may be a t l e a s t 7 t imes h igher than tha t aboveground. S tud ies o f roo ts and rhizome decompos-i t i o n are t he re f o r e e s s e n t i a l f o r a complete understanding o f the o v e r a l l ecosystem func t i ons of the wet lands . Decomposit ion should represent an important process i n the mar i t ime wetlands of B r i t i s h Columbia e s p e c i a l l y i f i t regenerates the n u t r i e n t elements b u i l t i n t o the o rgan i c t i s s u e . The c o n t r i -bu t i on made by l i t t e r decomposi t ion t o marsh n u t r i e n t r e c y c l i n g i s on ly vaguely known. C r i t i c a l quest ions cent re on the problem of d e t r i t u s u t i l i z a t i o n and secondary p roduc t i on . How much of the nu t r i e n t s r e l eased dur ing decomposit ion i n the Brunswick marsh con-t r i b u t e s to the Fraser e s tua r i ne food web? I t has been shown i n o the r s t ud i e s tha t m i c r ob i a l decomposi t ion improves the q u a l i t y o f the 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 ea s i ng the p r o t e i n con ten t . Is t h i s t rue f o r the marshes o f south western B r i t i s h Columbia? Our s tud i e s showed the energy content o f the l i v i n g shoots to be approx-imate ly 4.4 Kca l /g dry matter i r r e s p e c t i v e o f s pe c i e s . Does t h i s c a l o r i c content hold f o r decomposing l i t t e r ? 8.3 Proximate Chemical Components of Emergent Vegeta t ion as a Fac to r i n the Wetland System  Wetland emergent vege ta t i on occup ies a p o s i t i o n i n the landscape somewhat between dry land and aquat i c h a b i t a t s . The e re c t and r i g i d nature of t e r r e s t r i a l spec ies i s mainta ined by suppor t i ve elements 208 which have been f a i r l y we l l d e l i n e a t e d . Such t i s s u e s are g ene r a l l y l a c k i ng i n aqua t i c spec ies s ince support i s rendered by water . Un l i ke aqua t i c s pe c i e s , emergents requ i re e l abo ra te suppor t i ve t i s sues s ince they are normal ly rooted i n the s ub s t r a t e . Except f o r spec ies such as Polygonum amphibium and Ranunculus t r i c h o p h y l l u s , pa r t s of emergent p l an t s must a l s o develop above the water l e v e l i n o rder to r e s p i r e , t r a n s p i r e and ob ta in 'enough" r ad i an t energy f o r photosyn-t h e s i s . S t r u c t u r a l t i s s ue s are composed l a r g e l y of c e l l u l o s e , h em i c e l l u l o s e , l i g n i n , s i l i c a , and other r e l a t e d compounds. These components may occur i n d i f f e r e n t p ropor t i ons i n d i f f e r e n t p l an t group ings . In gene ra l , the emergent s tud ied conta ined high l e v e l s of NDF, ADF, and l i g n i n but very low l e v e l s o f s i l i c a . A l though 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 prov ides the main suppor t i ve 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 i s a l s o found i n s ub s t an t i a l q u a n t i t i e s i n many t rue grasses from t e r r e s t r i a l h a b i t a t s . A l l these s t r u c t u r a l components, wh i l e o f f e r i n g suppor t , u sua l l y l i m i t degradat ion of the p l an t or p l an t p a r t s . P ha l a r i s arundinacea and Carex s i t c h e n s i s both w i th low decomposi t ion r a t e s , f o r example, conta ined high l e v e l s of NDF, ADF, and l i g n i n . The l e s s f i b r ou s Carex lyngbyei degraded more r a p i d l y . NDF and l i g n i n percentages i n the emergents were gene ra l l y h i ghe r , stage by s tage , than those commonly repor ted f o r c u l t i v a t e d forage c rops . Such high l e v e l s probably 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 of the marsh spec ies by he rb i vo re s . NDF l e v e l s above 55 - 60 percent seem to l i m i t s i g n i f i c a n t l y the i n take o f forages by herb ivores (Van Soest 1965). 209 I t appears t ha t degradat ion may be be t t e r understood i f chemical assay i s supplemented w i th h i s t o l o g i c a l examinat ion o f the p l an t p a r t s . Comparative h i s t o l o g i c a l s t ud i e s showed l i g n i f i e d t i s s u e s to be more w ide ly d i s t r i b u t e d i n Pha l a r i s a rund inacea , a g r a s s , than i n Carex l y ngbye i , a sedge. Furthermore, the sedge had much loose parchymatous t i s s u e wh i l e the grass possessed c l o s e l y packed c e l l s w i th l i t t l e i n t e r n a l s u r f a c e . Such f ea tu res should be of cons ide rab le 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 decomposit ion p a t t e r n s . The f l e s h y outer t i s s u e s of Carex lyngbye i degrade qu i t e r e a d i l y l e a v i n g behind a ske le ton o f s l ow 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 compos i t ion o f the r e s i dua l s t r u c t u r a l t i s s u e s through h i s t o l o g i c a l examinat ions . P l an t dry matter may be d i v i d ed i n t o c e l l wa l l c on s t i t u en t s 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 ub l e ca rbohydra tes , p r o t e i n s , o rgan i c a c i d s and l i p i d s . As a l r eady d i s cus sed , the c e l l wa l l c ons t i t uen t s wh i l e p r ov i d i ng support to the p l a n t , may, depending on the l e v e l s , l i m i t g raz ing and decompos-i t i o n of the p l a n t s . On the c on t r a r y , c e l l contents are a lmost complete ly degradable and i f returned to the subs t ra te they are r e a d i l y used by p l a n t s , decomposers and o ther organisms a s soc i a t ed w i th the wet lands . A s ub s t an t i a l amount of s o l ub l e ma t e r i a l s both e l e c t r o l y t e s and non - e l e c t r o l y t e s are l o s t from l i v i n g emergent vege ta t i on through l e a c h i n g . Leaching l osses i n some emergents ranged from 45 to 64 mg/g l e a f dry weight i n 96 hours. Loss of s o l ub l e substances from l i v i n g p l an t s i s l i k e l y to be s i g n i f i c a n t i n the mar i t ime wet lands of south western B r i t i s h Columbia because t h i s area r e ce i ve s p l en ty of r a i n f a l l e s p e c i a l l y i n the w in te 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 sho re . There i s unce r t a i n t y p a r t i c u l a r l y about l each ing i n p l an t s of the t i d a l marshes because they are i n many ins tances water covered twice a day. S ince most l each ing occurs 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 p l a n t s , i t became a matter of i n t e r e s t to examine stomatal d i s t r i b u t i o n i n the emergents. We recorded cons ide rab l e 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 . The stomata were g ene r a l l y numerous i n h i gh l y r egu l a r pat te rns u sua l l y w i th a l t e r n a t i n g pho tosyn the t i c and non-photosyn the t i c bands. What i s the s i g n i f i c a n c e of these v a r i a t i o n s i n terms of l each ing? There must be some p h y s i o l o g i c a l mechanisms i n the emergents which con t ro l l each ing l o s s e s . I t i s p o s s i b l e tha t some of the p l an t s are adapted to such l o s ses even i f they are covered by water so f r e quen t l y . I t i s a l s o po s s i b l e tha t p l an t s which are not so adapted to l each ing are t o l e r a n t of h igh s a l t concen t ra t i on w i t h the p l an t possess ing s p e c i a l sa l t - remov ing organs, t y p i c a l c h a r a c t e r i s t i c s o f many xe rophy t i c p l a n t s . The mechanisms i nvo l ved i n l each ing o f these p l an t s should be i n v e s t i g a t e d . The f a c t tha t m e t a b o l i c a l l y important ma t e r i a l s are leached from the p l an t s i n c l u d i n g i no rgan i c m a t e r i a l s , ca rbohydra tes , amino ac i d s and o rgan i c ac ids (Tukey and Morgan 1964) suggests t ha t p l an t l eachates may be an important source o f n u t r i e n t s f o r p lan ts and organisms i n the wet land h a b i t a t . Loss o f s o l ub l e c on s t i t u en t s occurs not on ly i n l i v i n g vege ta t i on but a l so i n dead p l an t p a r t s . In our s t u d i e s , dead ove rw in te r i ng shoots l o s t from 4 to 50% o f t h e i r d ry weights between November and March. Much of t h i s l o s s cou ld be a t t r i b u t e d to l each ing of the " s o l u b l e s " . The high i n i t i a l l o sses in the l i t t e r bag and i n v i t r o 211 decomposi t ion s tud i e s were a l s o suggest ive o f l e a ch i ng . These " s o l u b l e s " presumably p lay s i g n i f i c a n t r o l e s i n subsequent decomposi t ion and i n the nature o f the o rgan i c l a y e r s which accumulate and u l t i m a t e l y become peat , 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 important pa r t of r e a d i l y degradable p l an t f r a c t i o n s . We s tud ied t h i s component by determin ing t o t a l n i t r ogen (crude p r o t e i n = N x 6.25) i n s e l e c t ed emergent shoots . Cons iderab le spec ies d i f f e r en c e s were recorded; the percentages rang ing from 0.6 i n Sc i rpus acutus to 1.7 i n P ha l a r i s a rund inacea . Large seasonal v a r i a t i o n s were a l s o recorded f o r a l l s p e c i e s , n i t r ogen l e v e l s gene ra l l y d e c l i n i n g as the season progressed. The d e c l i n e i n n i t r ogen (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 inc rease i n the f i b r o u s components. Al though the s t r u c u t r a l components o f the emergent spec ies are gene r a l l y high and the crude p r o t e i n l e v e l s low, the q u a l i t y of the vege ta t i on remains f a i r l y high e a r l y i n the growing season. One might t he re f o r e expect very young emergents to be a t t r a c t i v e to herb ivores and ye t t h i s does not seem to be the case i n the coas ta l marshes. I t may be pos tu l a ted tha t e a r l y i n the growing season, f l o o d i n g and o ther unfavourab le cond i t i ons d iscourage grazers from u t i l i z i n g the high q u a l i t y v ege t a t i o n . Late in the growing season when f l o od i ng i s min imized and o ther cond i t i on s have improved, low q u a l i t y of 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 he rb i vo re s . Pheno l i cs are a group of secondary p l an t substances t ha t cou ld a l s o be imp l i c a t ed 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 of the 212 young l ow - f i b r e and h igh-n i t r ogen t i s s u e s . I f Dacty l i s g lomera ta , , a w ide l y accepted spec ies f o r g raz i ng and one t ha t decomposes r e a d i l y , i s used as a standard f o r comparison w i th o ther s pe c i e s , then i t seems u n l i k e l y from our s tud ies tha t g raz ing and decomposit ion of the t i d a l marsh spec ies are l i m i t e d by t o t a l pheno l i c con ten t . However, pheno l i c l e v e l s i n the P i t t marsh spec ies appeared to be high enough to warrant f u r t h e r s t u d i e s . Techniques f o r determin ing such secondary compounds w i l l have to be r e f i n e d and s tandard i zed before c a r r y i ng out the i n v e s t i g a t i o n s . Ash c ons t i t u en t s may be recovered i n s i g n i f i c a n t amounts i n the p l an t " s o l u b l e s " . L a b i l e elements such as potassium and sodium should be recovered i n l a rge q u a n t i t i e s wh i l e immobile ones such as ca lc ium tend to remain i n the i n s o l u b l e p l an t f r a c t i o n s . In our s tud i e s l e s s than 10 percent o f the t o t a l ash was recovered i n the l e a cha te . Tota l ash l e v e l s i n the shoots , as determined by combust ion, v a r i e d on l y s l i g h t l y w i th age and spe c i e s . The P i t t marsh spec ies g ene r a l l y had lower ash percentages than the t i d a l marsh spec i e s . The low ash va lues recorded i n the P i t t marsh spec ies may be a s soc i a t ed w i th the l i m i t e d g raz ing a c t i v i t y i n t h i s o l i g o t r o p h i c h a b i t a t . The h igh ash va lues recorded i n the Brunswick marsh spec ies may be a t t r i b u t e d to extraneous s i l t depos i ted on the p l an t s by t i d e and f r e s h e t water or they may be an inherent c h a r a c t e r i s t i c of b rack i sh marsh spe c i e s . 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Appendix I % Organic Matter Decomposed i n L i t t e r Bags, where Bags were Placed on the Substrate Surface. o CO CM Brunswick P i t t Species Time marsh marsh Alaksen (days) % % % P h a l a r i s arundinacea 74 27.2* 22.2 21.5 148 27.8 22.2 22.1 294 52.0 53.0 52.7 Carex s i t c h e n s i s 74 24.0 16.9 7.8 148 24.9 17.1 10.6 294 18.7 34.9 31.2 Scirpus acutus 74 28.7 24.3 23.6 148 29.7 21.6 24.7 294 43.7 52.2 46.2 Juncus effusus 74 26.0 20.7 14.7 148 27.1 23.4 25.1 294 39.4 44.5 62.8 Carex l y n g b y e i 74 27.8 24.2 22.6 148 30.6 26.3 29.6 294 60.6 64.0 68.8 D a c t y l i s glomerata 74 41.4 33.6 31.8 148 42.3 37.4 35.3 294 78.7 78.2 93.1 * Values are averages of two samples Appendix I I A n a l y s i s of Variance of % Organic Matter Decomposed i n L i t t e r Bags, where Bags were Placed on the Substrate Surface. oo CM Source of V a r i a t i o n DF Sum SQ Mean SQ F-Value S i g n i f i c a n c e L o c a t i o n Time Time x L o c a t i o n Species Time x Species E r r o r A E r r o r 2 2 4 5 10 30 54 70.7 19833.0 1311.9 9860.7 3038.0 935.4 1272.7 35.3 9916.5 328.0 1972.1 303.8 31.2 23.6 1.5 420.2 13.9 63.2 (Error A) 9.7 (Error A) 1.3 NS ** ** ** ** NS T o t a l 107 36323.0 ** S i g n i f i c a n t at 1% l e v e l of p r o b a b i l i t y NS Not s i g n i f i c a n t Appendix I I I % Organic Matter Decomposed i n L i t t e r Bags, where Bags were Placed 15 cm Below the Surface. Species Time (days) P h a l a r i s arundinacea 73 146 Carex lyngbyei 73 146 D a c t y l i s glomerata 73 146 * Values are averages of two samples. Brunswick P i t t marsh marsh Alaksen 7.0* 6.6 13.4 21.0 11.4 34.1 7.5 6.6 14.4 12.2 10.5 32.9 5.0 8.4 14.8 19.5 15.0 40.0 Appendix IV A n a l y s i s of Variance of % Organic Matter Decomposed i n L i t t e r Bags Bags were Placed 15 cm Below the Surface. Source of V a r i a t i o n DF Lo c a t i o n 2 Date 1 Date x L o c a t i o n 2 Species 2 Date x Species 2 E r r o r A 8 Er r o r 18 ** 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 Sum SQ Mean SQ F-Value 1604.6 802.3 146.8 1412.5 1412.5 261.6 412.7 206.3 37.7 57.0 28.5 3.7 ( E r r o r A) 63.2 31.6 4.1 (E r r o r A) 61.6 7.6 1.4 98.4 5.5 Appendix V In V i t r o Decomposition of Overwintered Shoots from Wetland and C o n t r o l Species; Expressed as % Organic Matter Loss. Brunswick marsh inoculum P i t t marsh inoculum Species Time (days) No Hysol Hysol No Hysol 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 lyngbyei 21 42 19.2 23.3 22.6 26.0 20.0 28.7 25.5 26.9 D a c t y l i s glomerata 21 42 12.6 22.4 14.2 24.6 16.1 24.7 17.1 24.5 C o n t r o l ( s t e r i l e ) 21 42 8.6 10.3 10.3 10.0 9.9 9.8 10.3 10.7 * Values are averages of two samples Appendix VI Analysis of Variance of % Organic Matter Loss In Vitro; Overwintered Shoots. Source of Variation DF Sum SQ Inoculum Source 1 52.3 Additive 1 35.0 Time 1 502.5 Species 4 2012.8 Inoculum x Additive 1 6.2 Inoculum x Time 1 17.0 Inoculum x Species 4 18.0 Additive x Time 1 13.5 Additive x Species 4 7.0 Time x Species 4 155.9 Inoculum x Add. x Time 1 1.2 Inoculum x Add. x Species 4 6.7 Inoculum x Time x Species 4 47.5 Add. x Time x Species 4 16.4 Inoculum x Add. x Time x Species 4 20.7 Error 40 46.1 Total 79 2959.0 Mean SQ F-Value Significance 52.3 45.5 ** 35.0 30.3 ** 502.5 437.7 ** 503.2 436.3 ** 6.2 5.4 NS 17.0 14.7 ** 4.5 3.9 ** 13.5 11.7 ** 1.7 1.5 NS 39.0 33.8 ** 1.2 1.1 NS 6.7 1.4 NS 11.9 10.3 ** 4.1 3.5 NS 5.1 4.5 ** 1.1 ** Significant (P < 0.01) NS Not Significant Appendix V I I In V i t r o Decomposition of Young Shoots from Wetland and C o n t r o l Species; Expressed as % Organic Matter Loss. Brunswick marsh inoculum P i t t marsh inoculum Time No Hysol Hysol No Hysol Hysol (days) % % % % P h a l a r i s arundinacea 21 59.7* 60.2 64.5 59.8 42 67.2 63.9 62.5 68.9 Carex s i t c h e n s i s 21 42.2 48.4 46.9 54.5 42 46.6 53.4 48.6 56.0 Carex lyngb y e i 21 65.7 66.0 70.6 72.2 42 71.9 71.2 72.0 73.3 D a c t y l i s glomerata 21 65.9 67.5 64.9 68.0 42 68.8 67.3 70.1 70.1 Co n t r o l ( s t e r i l e ) 21 29.2 26.5 26.9 27.8 42 37.4 32.6 26.9 32.2 * Values are averages of two samples. Appendix V I I I A n a l y s i s of Variance of % Organic Matter Loss In V i t r o ; Young Shoots, Source of V a r i a t i o n DF Sum SQ Mean SQ F-Value S i g n i f i c a n c e Inoculum Source A d d i t i v e Time Species Inoculum x A d d i t i v e Inoculum x Time Inoculum x Species A d d i t i v e x Time A d d i t i v e x Species Time x Species Inoculum x Add. x Time Inoculum x Add. x Species Inoculum x Time x Species Add. x Time x Species Inoculum x Add. x Species E r r o r x Time 1 32.0 32.0 8.9 ** 1 47.7 47.7 13.3 ** 1 269.4 269.4 75.0 ** 4 17900.0 4475.0 1245.0 ** 1 35.6 35.6 9.9 ** 1 30.7 30.7 8.5 •k* 4 116.4 29.1 • 8.1 ** 1 0.3 0.3 0.1 NS 4 152.9 38.2 10.6 ** 4 13.6 3.4 0.9 NS 1 21.6 21.6 6.0 NS 4 22.8 5.7 1.6 NS 4 33.5 8.4 2.3 NS 4 24.3 6.1 1.7 NS 4 44.2 11.1 3.1 NS 40 143.7 3.6 — — T o t a l 79 18889.0 ** S i g n i f i c a n t at 1% of p r o b a b i l i t y NS Not s i g n i f i c a n t 

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