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Water chemistry profile comparisons of early- and mid-successional forests in coastal British Columbia Binkley, Dan 1980

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WATER CHEMISTRY PROFILE COMPARISONS OF  EARLY- AND MID-SUCCESSIONAL  FORESTS  IN COASTAL BRITISH COLUMBIA  A THESIS SUBMITTED IN PARTIAL FULFILLMENT OF THE REQUIREMENTS FOR- THE DEGREE OF '  MASTER OF SCIENCE in  THE FACULTY OF 'GRADUATE STUDIES FACULTY OF FORESTRY  We accept  t h i s t h e s i s as meeting  the r e q u i r e d  standard  THE UNIVERSITY OF BRITISH COLUMBIA March 20, 1980 (c)  D a n i e l E. B i n k l e y ,  1980  In p r e s e n t i n g t h i s  thesis in partial  an a d v a n c e d d e g r e e a t the L i b r a r y I further for  shall  the U n i v e r s i t y  make i t  agree that  this  thesis for  It  Department  f i n a n c i a l gain shall  of  The U n i v e r s i t y o f B r i t i s h C o l u m b i a 2075 Wesbrook P l a c e V a n c o u v e r , Canada V6T 1W5  BP 75-51 1 E  the requirements I agree  r e f e r e n c e and copying of  this  that  not  copying or  for  that  study. thesis  by t h e Head o f my D e p a r t m e n t  i s understood  permission.  of  B r i t i s h Columbia,  extensive  s c h o l a r l y p u r p o s e s may be g r a n t e d  written  DE-6  of  freely available for  permission for  by h i s r e p r e s e n t a t i v e s . of  fulfilment  or  publication  be a l l o w e d w i t h o u t  my  ii  i ABSTRACT  A comparison of water c h e m i s t r y p r o f i l e s was made between a mids u c c e s s i o n a l 70 t o 90 y e a r - o l d f o r e s t and an e a r l y - s u c c e s s i o n a l 18 y e a r - o l d f o r e s t a t the U.B.C. Research F o r e s t . D o u g l a s - f i r and western r e d cedar dominated the  Western  hemlock,  the o l d e r ecosystem, w h i l e  younger ecosystem was composed o f D o u g l a s - f i r and r e d a l d e r .  The  c o n c e n t r a t i o n s of n u t r i e n t s and o t h e r chemicals were compared i n t h r o u g h f a l l , f o r e s t f l o o r and m i n e r a l s o i l water and stream-water.  leachates, saturated  zone-  The younger ecosystem was found to have g r e a t e r  c o n c e n t r a t i o n s i n the i n t e r m e d i a t e s t a g e s of the p r o f i l e s , w h i l e streamwater c o n c e n t r a t i o n s were more s i m i l a r between the ecosystems. The o v e r a l l t r e n d i n the water c h e m i s t r y p r o f i l e s was b e s t exemplif i e d by the c o n d u c t i v i t y p r o f i l e s .  C o n d u c t i v i t y was assumed t o be  e q u a l i n p r e c i p i t a t i o n f o r b o t h ecosystems, and was almost i d e n t i c a l i n stream-water. two  The s o i l l e a c h a t e i n the younger ecosystem, however, was  to three times g r e a t e r i n c o n d u c t i v i t y than i n the o l d e r The major e x c e p t i o n t o t h i s t r e n d was the n i t r a t e p r o f i l e  sons, where stream-water younger  ecosystem. compari-  c o n c e n t r a t i o n s were 17 times g r e a t e r i n the  than i n the o l d e r ecosystem.  However, b i o l o g i c a l n i t r o g e n  f i x a t i o n by the r e d a l d e r i n the younger ecosystem r e s u l t s i n s u b s t a n t i a l l y greater  inputs•  The c o n c e n t r a t i o n s o f s i l i c a i n c r e a s e d p r o g r e s s i v e l y through the p r o f i l e s of both ecosystems, b u t the l e v e l s were c o n s i s t e n t l y  40% to  100% h i g h e r i n the younger ecosystem, s u g g e s t i n g a g r e a t e r i n p u t of m i n e r a l c a t i o n s to the younger ecosystem through s o i l m i n e r a l weathering.  iii The h i g h e r c o n c e n t r a t i o n s of n u t r i e n t s w i t h i n the s o i l  leachate  stages of the younger ecosystem, combined w i t h the f a i l u r e of h i g h e r l e v e l s to be observed  i n the s a t u r a t e d zone-water and  water (with the e x c e p t i o n of n i t r a t e ) , tem was  suggest  these stream-  t h a t the younger  ecosys-  r e l a t i v e l y more e f f i c i e n t a t r e t a i n i n g d i s s o l v e d n u t r i e n t s than  the o l d e r ecosystem.  XV  TABLE OF CONTENTS  CHAPTER 1  INTRODUCTION  1  CHAPTER 2 2-1 2- 2  DEFINITIONS AND LITERATURE REVIEW Definitions Water c h e m i s t r y p r o f i l e changes through s u c c e s s i o n a l time  3 3  CHAPTER 3 3- 1 3-2 3- 3  DESCRIPTION OF STUDY AREAS General d e s c r i p t i o n The younger ecosystem The o l d e r ecosystem  5 11 11 13 14  CHAPTER 4 METHODS 4- 1 F i e l d methods 4T-1-1 C o l l e c t i o n p e r i o d and i n t e r v a l 4-1-2 P r e c i p i t a t i o n c o l l e c t i o n s 4-1-3 T h r o u g h f a l l c o l l e c t i o n s 4-1-4 S o i l leachate c o l l e c t i o n s 4-1-5 S a t u r a t e d zone-water c o l l e c t i o n s 4-1-6 Stream-water c o l l e c t i o n s 4-2 L a b o r a t o r y methods 4- 3 Sources o f b i a s  18 18 18 19 19 19 20 21 21 22  CHAPTER 5 RESULTS AND DISCUSSION 5- 1 Water c h e m i s t r y p r o f i l e comparisons 5-1-1 C o n c e n t r a t i o n r a t i o s , y o u n g e r : o l d e r ecosystem 5-1-2 R a t i o s o f stream-water c o n c e n t r a t i o n to p r o f i l e maxima 5-1-3 Chloride 5-1-4 pH 5-1-5 C o n d u c t i v i t y 5-1-6 N i t r a t e and ammonium 5-1-7 S i l i c a 5-1-8 Calcium and magnesium 5-1-9 Potassium 5-2 R e l a t i v e a n i o n d i s t r i b u t i o n 5-3 R e l a t i v e c a t i o n d i s t r i b u t i o n 5-4 Cation:anion balances 5-5 Comparisons w i t h o t h e r water c h e m i s t r y p r o f i l e studies 5-6 Dominant a n i o n s and c a t i o n s 5-7 N u t r i e n t d e p l e t i o n 5-8 N u t r i e n t r e t e n t i o n through s u c c e s s i o n a l time 5-9 C r i t i q u e of the water c h e m i s t r y p r o f i l e method  24 24 24  CHAPTER 6  CONCLUSIONS  24 30 32 32 33 35 37 37 38 39 39 40 42 44 45 47 50  LITERATURE CITED  53  APPENDIX  57  -  LIST OF TABLES T a b l e 1.  T a b l e 2.  T a b l e 3.  Mean c o n c e n t r a t i o n o f c h e m i c a l s i n p r e c i p i t a t i o n , t h r o u g h f a l l and stream-water f o r s p r u c e - f i r and aspen ecosystems i n New Mexico  7  Water c h e m i s t r y p r o f i l e s f o r D o u g l a s - f i r - w e s t e r n hemlock ecosystems, 70 to 90 y e a r s - o l d and 450 years-old.  9  pH, c o n d u c t i v i t y and s i l i c a water profiles.  chemistry 25 26  T a b l e 4.  Anion water c h e m i s t r y  T a b l e 5.  C a t i o n water c h e m i s t r y  T a b l e 6.  Water c h e m i s t r y p r o f i l e r a t i o s , younger o l d e r ecosystem  T a b l e 7.  T a b l e 8.  profiles  27  profiles ecosystem:  28  R a t i o s of stream-water c o n c e n t r a t i o n s to the p r o f i l e maximum c o n c e n t r a t i o n  29  Conductivity  41  balance ecosystem  58  T a b l e A-•1  S o i l p r o f i l e d e s c r i p t i o n , younger  T a b l e A-•2  S o i l p r o f i l e d e s c r i p t i o n , o l d e r ecosystem  59  T a b l e A-•3  S o i l chemical  60  T a b l e A-•4  F o r e s t f l o o r biomass and n u t r i e n t  T a b l e A-•5  L i t t e r f a l l biOmass and n u t r i e n t  T a b l e A-•6  S p e c i e s d i s t r i b u t i o n and  T a b l e A-•7  Aboveground  i n f o r m a t i o n averages content  content  biomass  net primary p r o d u c t i v i t y  62 63 66  estimates  68  vi LIST OF FIGURES F i g u r e 1.  F i g u r e 2.  F i g u r e 3.  F i g u r e 4.  F i g u r e 5.  Mean monthly temperatures, U.B.C. Research F o r e s t Office.  12  Monthly p r e c i p i t a t i o n , U.B.C. Research F o r e s t Office.  12  Younger ecosystem estimated turnovers.  15  Older ecosystem estimated turnovers.  biomass p o o l s and  biomass pools and  S i m p l i f i e d model o f water f l o w ecosystems.  16 through 49  Figure A - l .  R e g i o n a l map o f the study areas  69  F i g u r e A-2.  U.B.C. Research F o r e s t , study  70  area l o c a t i o n s  vii ACKNOWLEDGEMENTS  I g r a t e f u l l y acknowledge t h e e f f o r t s of my committee, Hamish Kimmins, A l a n C a r t e r and Tim B a l l a r d , i n t h e i r i n d e f a t i g u e a b l e attempts t o improve t h e grammar, o r g a n i z a t i o n , s t y l e and content of  my t h e s i s . The  and  I a p p r e c i a t e t h e i r help..r ... .  e x e c u t i o n o f t h e p r o j e c t was g r e a t l y a s s i s t e d by d i s c u s s i o n s  field  work h e l p from f e l l o w s t u d e n t s :  DeGatanzaro, Lynn Husted, Fred N u s z d o r f e r , and  Jane  Paul Courtin, J e n n i f e r C h r i s P e r r i n , Kathy Pomeroy  Richards.  Laboratory of  ;  and f i e l d methods a l s o were developed  with the help  Min Tsze, whose pragmatic approach to r e s e a r c h was an e s s e n t i a l  counter-balance.  Min's a n a l y s e s w i t h t h e AutoAnalyzer  were a g r e a t  help on a major p o r t i o n of my p r o j e c t . Greg Bohnenkamp was extremely  h e l p f u l i n l o c a t i n g and s u p p l y i n g  equipment, from rubben'.stoppers t o a i r p l a n e s . I a l s o thank t h e s t a f f o f t h e U.B.C. Research F o r e s t f o r t h e i r a s s i s t a n c e d u r i n g my e x c u r s i o n s . F i n a l l y , my g r a t i t u d e i s extended to Henry t h e Grouse, whose annoyingly  a g g r e s s i v e behavior  the r i g o r s o f c o l d  science.  o c c a s s i o n a l l y p r o v i d e d r e s p i t e from  F u r t h e r , H e n r i e t t a t h e b l a c k bear and  her two cubs a r e thanked f o r e v e n t u a l l y r e f r a i n i n g from d e s t r o y i n g my i n s t a l l a t i o n s and a l l o w i n g me to c o n t i n u e w i t h t h e study.  CHAPTER 1  INTRODUCTION  The p r o d u c t i o n of biomass p a r t by the a v a i l a b i l i t y  i n f o r e s t ecosystems i s r e g u l a t e d i n  of n u t r i e n t s .  Nutrient transfers,  additions  and l o s s e s i n ecosystems are o f t e n a s s o c i a t e d w i t h the flow of water. Water c h e m i s t r y p r o f i l e s which examine the c o n c e n t r a t i o n s o f c h e m i c a l s at v a r i o u s stages o f the water's passage through an ecosystem can p r o v i d e some i n s i g h t s i n t o  the n u t r i e n t dynamics  of the system.  Water c h e m i s t r y p r o f i l e s have been used to c h a r a c t e r i z e u n d i s turbed ecosystems  ( F e l l e r 1977, S o l l i n s e t a l . i n p r e s s ) , t o examine  the e f f e c t s of c l e a r c u t t i n g and s l a s h b u r n i n g  (Kimmins  and F e l l e r  1976),  to compare s o l u t i o n c h e m i s t r y mechanisms between ecosystems of d i f f e r ent biomes  (Johnson 1975) and to examine the e f f e c t s of a c i d  t i o n on h i g h e l e v a t i o n ecosystems  (Cronan and S c h o f i e l d  precipita-  1979).  T h i s t h e s i s r e p o r t s on a comparison of water c h e m i s t r y p r o f i l e s measured  i n a 70 to 90 y e a r - o l d mixed  (1974, 1977) w i t h those I measured tation with red alder.  c o n i f e r f o r e s t by M. C. F e l l e r  i n an 18 y e a r - o l d D o u g l a s - f i r p l a n -  These ecosystems were on s i m i l a r s i t e s ,  d i f f e r e n c e s i n water c h e m i s t r y p r o f i l e s can be a t t r i b u t e d d i f f e r e n c e s i n age and v e g e t a t i o n .  and the  l a r g e l y to  The o b j e c t i v e s were t o :  1.  Examine the changes i n c h e m i c a l c o n c e n t r a t i o n s from one water chemistry p r o f i l e stage to the next, comparing the c o n c e n t r a t i o n s as r a t i o s of the younger ecosystem to the o l d e r ecosystem.  2.  Examine the e f f i c i e n c y w i t h which each ecosystem r e t a i n e d d i s s o l v e d n u t r i e n t s , expressed as a r a t i o of the c o n c e n t r a t i o n i n the stream-water l e a v i n g the ecosystem to the maximum conc e n t r a t i o n i n the p r o f i l e .  3.  I n v e s t i g a t e the i n t e r p r e t a t i o n s which c o u l d be made about ecosystem n u t r i e n t dynamics through the water c h e m i s t r y p r o f i l e method.  Assess how t h i s i n f o r m a t i o n on ecosystem n u t r i e n t dynamics compares w i t h c u r r e n t i d e a s i n the l i t e r a t u r e .  CHAPTER 2  2-1  DEFINITIONS AND LITERATURE REVIEW  Definitions For the purpose of t h i s t h e s i s , I have used the f o l l o w i n g  defini-  tions: 1.  An ecosystem was d e f i n e d by W h i t t a k e r (1976) as "a community and  i t s environment  treated  t o g e t h e r as a f u n c t i o n a l system of complemen-  t a r y r e l a t i o n s h i p s , ( w i t h ) t r a n s f e r and c i r c u l a t i o n of energy and m a t t e r . " As used i n t h i s  t h e s i s , ecosystem boundaries were f o u r - d i m e n s i o n a l .  For the younger ecosystem, the s u r f i c i a l b o u n d a r i e s were the b o r d e r s between the 18 y e a r - o l d p l a n t a t i o n and the s u r r o u n d i n g o l d e r T h i s was not an e n t i r e watershed.  forest.  The s u r f i c i a l b o u n d a r i e s of the  o l d e r ecosystem were l a r g e l y the b o u n d a r i e s o f the watershed, w i t h the e x c e p t i o n of areas w i t h i n these b o u n d a r i e s which had younger (see F e l l e r 1974). or compacted t i l l  vegetation  The v e r t i c a l boundaries extended from the bedrock s u r f a c e s upward to the h e i g h t of the t a l l e s t  trees.  The f o u r t h dimension, time, covered the d a t a c o l l e c t i o n p e r i o d s . 2.  Input and output o f n u t r i e n t s were g e n e r a l l y d e f i n e d as matter  t h a t c r o s s e s the d e f i n e d boundaries o f an ecosystem. to t h i s d e f i n i t i o n  The e x c e p t i o n s  (as used i n t h i s t h e s i s ) i n v o l v e d elements which  are c o n t a i n e d i n m i n e r a l s .  The r e l e a s e of c a t i o n s from p r i m a r y and  secondary m i n e r a l s c o n s t i t u t e d an i n p u t  to the p o o l of n u t r i e n t s  p o t e n t i a l l y a v a i l a b l e f o r c y c l i n g w i t h i n , or l o s s from, the ecosystem. S i m i l a r l y , c a t i o n s combined i n the secondary f o r m a t i o n of c l a y m i n e r a l s would be c o n s i d e r e d an "output".  D e t e c t i o n of t h i s  beyond the r e s o l u t i o n of t h i s study.  type o f output was  A d d i t i o n a l l y , molecular nitrogen  which was w i t h i n the p h y s i c a l boundaries of the ecosystem would be  considered nitrogen  an i n p u t when f i x e d  to m o l e c u l a r  to N H 3 ; d e n i t r i f i c a t i o n of combined  n i t r o g e n o r n i t r o u s oxides would be an output.  A d e t a i l e d d i s c u s s i o n of ecosystem n u t r i e n t i n p u t s and outputs provided 3.  was  by Gorham e t a l . (1979).  Succession  i s a process  of s t r u c t u r a l development i n an ecosystem  through time, i n v o l v i n g changes i n v e g e t a t i o n  composition  and dominance.  F u n c t i o n a l changes, such as i n c r e a s e s or decreases i n p r o d u c t i v i t y and n u t r i e n t c y c l i n g r a t e s , a l s o occur The  through a s u c c e s s i o n a l sequence.  term primary s u c c e s s i o n i s used to d e s c r i b e ecosystem development  on a s i t e unmodified by a p r e v i o u s v e g e t a t i o n . occurs when a d i s t u r b a n c e a l l of the v e g e t a t i o n ' s  Secondary  succession  has d i s r u p t e d a v e g e t a t i o n but not removed  e f f e c t s on the development of the s i t e .  In  t h i s t h e s i s , " o l d e r " and "younger" r e f e r to the time s i n c e the most r e c e n t i n i t i a t i o n of secondary 4.  Water chemistry  succession.  p r o f i l e r e f e r s t o the changes i n c o n c e n t r a t i o n of  chemicals  i n water as i t passes from one stage  another.  These stages were p r e c i p i t a t i o n ,  and  mineral  s o i l leachates, saturated  i n the ecosystem to  throughfall, forest  floor  zone-water, and stream-water.  P r e c i p i t a t i o n was the incoming water from the atmosphere as measured by •precipitation collectors  ( d e s c r i b e d i n Methods, Chapter 3 ) .  f a l l r e f e r s t o water which passed through the canopies o v e r s t o r y and u n d e r s t d r y ,  where p r e s e n t .  Through-  of both the  Forest f l o o r leachate r e f e r s  to water which passed through the f o r e s t f l o o r and entered  a lysimeter.  M i n e r a l s o i l l e a c h a t e i n the younger ecosystem r e f e r s t o water which entered  a l y s i m e t e r l o c a t e d 25 cm below the i n t e r f a c e of the A and B  h o r i z o n s , and i n the o l d e r ecosystem i n t o l y s i m e t e r s p l a c e d  60 cm  below the s o i l s u r f a c e . l e c t i o n s may  I t should be noted that these l y s i m e t e r  not have been r e p r e s e n t a t i v e of a l l water p a s s i n g these  stages; p e r i o d s of r a p i d f l o w may flows d u r i n g p e r i o d s of s o i l  have been undersampled, j u s t as  t e n s i o n s g r e a t e r than 0.1 atm  kPa) of t e n s i o n would not have been sampled. r e f e r s to water sampled from the s a t u r a t e d compacted  col-  till  layer  Saturated  (about 10  zone-water  zone of the s o i l above the  (the term "groundwater" i s not used to a v o i d  c o n f u s i o n w i t h water deeper i n the e a r t h ' s c r u s t which i s beyond the d e f i n e d l i m i t s of the ecosystem). water exposed to the atmosphere  Finally,  stream-water r e f e r s to  i n the stream bed.  P r e c i p i t a t i o n and t h r o u g h f a l l c o l l e c t o r s , as w e l l as the  soil  l y s i m e t e r s , c o n t i n u o u s l y c o l l e c t e d samples whenever c o n d i t i o n s p e r m i t ted;  stream-water and s a t u r a t e d zone-water were sampled a t d i s c r e t e  i n t e r v a l s on the days of f i e l d  collections.  The a n a l y s e s p r e s e n t e d  here g i v e e q u a l weight to each c o l l e c t i o n p e r i o d , d i s r e g a r d i n g ences i n water volumes.  differ-  F u r t h e r , averages and s t a n d a r d e r r o r s are  based on a combination of a l l samples w i t h o u t s t r a t i f i c a t i o n by time or location.  2-2  L i t e r a t u r e Review, Water Chemistry P r o f i l e Changes Through Success i o n a l Time The d i f f e r e n c e s i n the v e g e t a t i o n between the two ecosystems of  the  comparisons p r e s e n t e d i n t h i s t h e s i s r e p r e s e n t a common s u c c e s s i o n a l  trend i n c o a s t a l P a c i f i c Northwest f o r e s t s K l i n k a 1976).  ( F r a n k l i n and Dyrness  1973,  The d i f f e r e n c e s i n water c h e m i s t r y p r o f i l e s s h o u l d r e -  v e a l t r e n d s which accompany the s u c c e s s i o n a l development of ecosystems on these s i t e s .  Water chemistry p r o f i l e c u r r e n t l y absent  comparisons through  from the l i t e r a t u r e .  s u c c e s s i o n a l time  William Graustein  (personal  communication) of the Department of Geology and Geophysics  at Y a l e  U n i v e r s i t y made such a comparison on a mountain i n n o r t h e r n Mexico.  New  H i s water c h e m i s t r y p r o f i l e comparisons i n v o l v e d an e a r l y - s u c -  c e s s i o n a l t r e m b l i n g aspen stand and The  are  an old-growth  spruce-fir  stand.  s p r u c e - f i r stand was 300 m h i g h e r than the aspen stand, but  Graustein  b e l i e v e d the m a j o r i t y of the d i f f e r e n c e s i n the water chemistry could be a t t r i b u t e d  to the e f f e c t s of the v e g e t a t i o n .  During  profiles a  two  year c o l l e c t i o n p e r i o d , he measured the c h e m i s t r y of water at the cipitation,  t h r o u g h f a l l , s o i l l e a c h a t e and  stream-water stages.  s o i l s o l u t i o n l y s i m e t e r s were not r e p l i c a t e d , and s p a t i a l v a r i a b i l i t y was of p r e c i p i t a t i o n ,  so no measure of  However, h i s more i n t e n s i v e sampling  comparisons.  Table 1 p r e s e n t s G r a u s t e i n ' s water With the e x c e p t i o n of n i t r a t e ,  i n c r e a s e d f o r a l l chemicals fall  His  t h r o u g h f a l l and stream-water c h e m i s t r y r e v e a l e d some  interesting patterns. profile  available.  pre-  from p r e c i p i t a t i o n  chemistry  the c o n c e n t r a t i o n  to t h r o u g h f a l l .  Through-  c o n c e n t r a t i o n s were c o n s i s t e n t l y g r e a t e r f o r the s p r u c e - f i r  system, w i t h n i t r a t e a g a i n b e i n g to have been taken up by both a b s o r b i n g more than  the aspen.  the o n l y e x c e p t i o n .  eco-  N i t r a t e appeared  canopies, w i t h the s p r u c e - f i r  canopy  While many of the i o n s i n t h r o u g h f a l l  o r i g i n a t e d from w i t h i n the l e a v e s , G r a u s t e i n a t t r i b u t e d much of  the  i n c r e a s e i n c o n c e n t r a t i o n to the washing from p l a n t s u r f a c e s of a e r o s o l p a r t i c l e s which impacted  on the v e g e t a t i o n b e f o r e the r a i n .  the major o b j e c t i v e s of h i s study was component of atmospheric water r u n o f f was  (One  to q u a n t i f y the a e r o s o l  n u t r i e n t i n p u t to these ecosystems.)  u s u a l l y more c o n c e n t r a t e d  from the s p r u c e - f i r  of  impaction Streamecosystem  Table 1.  Mean c o n c e n t r a t i o n of chemicals i n p r e c i p i t a t i o n , t h r o u g h f a l l and stream-water f o r s p r u c e - f i r and aspen ecosystems i n New Mexico. Data from W. G r a u s t e i n ( p e r s o n a l communication), ueq £ . - 1  Chemical Na K  +  +  Mg"^  a 2  N0 " 3  HCO3"  Cl"  so ~~ h  Spruce-Fir Stream-water Throughfall  Throup ;hf a l l  12.5  82  3.1  72  28  29  16  3.4  31  129  11  91  121  178  39  158  0.5 18  3. 7  Aspen Stream-water  2.9  18  Ca^ Si0  Precipitation  1. 4  124  6.5  167  2.6  8  8  2  243  -11  43  256  40  280  9  49  12  14  15  34  122  123  35  50  Si02 data are expressed i n m i c r o m o l e s / l i t e r .  8 than from the aspen ecosystem.  G r a u s t e i n proposed  that a g r e a t e r b i o -  mass a c c u m u l a t i o n r a t e i n the aspen stand p r o b a b l y accounted f o r these differences. Reiners  T h i s i s i n l i n e w i t h the h y p o t h e s i s of V i t o u s e k and  (1975,  ecosystems  1976)  ( d i s c u s s e d i n Chapter 5) of l a t e  being less e f f i c i e n t  successional  i n r e t a i n i n g incoming n u t r i e n t s  than  e a r l i e r stages. No water  c h e m i s t r y p r o f i l e comparisons  through s u c c e s s i o n a l  have been made f o r f o r e s t s i n the P a c i f i c Northwest.  G r i e r et a l .  (1974) compared n u t r i e n t c y c l i n g between the 450 y e a r - o l d f o r e s t of Watershed  time  Douglas-fir  10 on the H. J . Andrews E x p e r i m e n t a l F o r e s t i n  Oregon w i t h a 37 y e a r - o l d D o u g l a s - f i r p l a n t a t i o n a t the A. E. Thompson Research Center i n Washington.  Water c h e m i s t r y p r o f i l e d a t a are  now  a v a i l a b l e f o r these s i t e s , but the d i f f e r e n c e s i n parent m a t e r i a l comb i n e d w i t h the 170% g r e a t e r p r e c i p i t a t i o n at the H. J . Andrews would obscure the d i f f e r e n c e s i n water vegetation.  chemistry p r o f i l e s  site  caused by the  As an a l t e r n a t i v e , Table 2 p r e s e n t s a comparison  of the  old-growth H. J . Andrews ecosystem p r o f i l e s w i t h those measured by Feller  (1977) f o r the 70 to 90 y e a r - o l d mixed c o n i f e r ecosystem  i n the comparison p r e s e n t e d i n t h i s t h e s i s . were d i f f e r e n t  f o r the two ecosystems  o l d ecosystem and q u a r t z - d i o r i t e t i l l  used  The s o i l p a r e n t m a t e r i a l s  ( v o l c a n i c t u f f s f o r the 450 y e a r f o r the 70-90 y e a r - o l d  ecosystem),  but p r e c i p i t a t i o n i s s i m i l a r . Table 2 r e v e a l s s u b s t a n t i a l d i f f e r e n c e s i n p r e c i p i t a t i o n c h e m i s t r y f o r the two ecosystems.  P r e c i p i t a t i o n c o n c e n t r a t i o n s i n the 450 y e a r -  o l d ecosystem were f i v e times g r e a t e r f o r H , +  two-and-a-half  g r e a t e r f o r CI , and twelve times g r e a t e r f o r NO3 90 y e a r - o l d  ecosystems.  times  than i n the 70 to  9  T a b l e 2.  Water c h e m i s t r y p r o f i l e s f o r D o u g l a s - f i r - w e s t e r n hemlock ecosystems, 70 to 90 y e a r s - o l d and 450 years-old,. Data from F e l l e r ( ] 977). and S o l l i n s e t a l . ( i n press) , peq l * . a  -  Stage  PH  CI  NO3  Ca  Mg  K  Precipitation 70-90 450  4.5 5.2  17 44  1 1 - 1 0 0.9 7  5 4  2 1  Throughfall 70-90 450  4.7 5.3  27 52  12 Trace  32 18  14 12  22 18  Forest Floor Leachate 70-90 450  5.8 5.8  61 81  5 Trace  157 58  41 23  37 33  Mineral S o i l Leachate 70-90, 60 cm 450, 100 cm  6.5 6.9  31 104  22 0.1  71 398  38 46  7 16  Springs, S a t u r a t e d Zone 70-90 450  6.3 6.4  25  1 0.4  65 159  21 74  -2  Stream-Water 70-90 .450  6.8 6.7  23  4 1.4  75 160  26 69  2 9  Only d a t a f o r m i d - and l o w e r - s l o p e sampling  8  s t a t i o n s i n c l u d e d here.  10 The  p r e c i p i t a t i o n c a t i o n c o n c e n t r a t i o n d i f f e r e n c e s between the  450  y e a r - o l d and the 70 t o 90 y e a r - o l d ecosystems were s m a l l e r .  the  t h r o u g h f a l l stage,  u s u a l l y higher  the o l d e r ecosystem c a t i o n c o n c e n t r a t i o n s were  than the younger ecosystem's c o n c e n t r a t i o n s .  t i o n s of potassium  Concentra-  were s i m i l a r between the two ecosystems from p r e c i p -  i t a t i o n through f o r e s t f l o o r s t a g e s . systems experienced  In subsequent s t a g e s , both  eco-  d e c r e a s i n g K c o n c e n t r a t i o n s ; however, the decreases  were l e s s f o r the o l d growth ecosystem. less similarity.  Below  Calcium  and magnesium e x h i b i t e d  In the 70-90 y e a r - o l d ecosystem (the o l d e r ecosystem  of  the present  s t u d y ) , Ca and Mg reached  t h e i r maximum c o n c e n t r a t i o n s  in  the f o r e s t f l o o r l e a c h a t e stage and then decreased  of  the p r o f i l e .  through the r e s t  In the o l d growth ecosystem, Ca and Mg stream-water  c o n c e n t r a t i o n s exceeded the l e v e l s i n f o r e s t f l o o r l e a c h a t e . the w e a t h e r i n g r a t e s may have d i f f e r e d .  However,  (and hence c a t i o n i n p u t ) f o r the two ecosystems S i l i c a water chemistry p r o f i l e s would g i v e some  i n s i g h t s , but no s i l i c a data were c o l l e c t e d f o r the 450 y e a r - o l d ecosystem. Data on the consumption of H  +  through the p r o f i l e a l s o c o u l d be h e l p f u l  ( S o l l i n s e t a l . i n p r e s s ) , but the d i f f e r e n c e s i n p r o d u c t i v i t y and n u t r i e n t c y c l i n g r a t e s between the ecosystems make i t d i f f i c u l t t o • d i s t i n g u i s h between the b i o l o g i c and m i n e r a l o g i c consumption of H ions.  The comparison of these  +  two ecosystems showed that the ecosystems  d i f f e r e d in t h e i r water chemistry  p r o f i l e s , but not enough i n f o r m a t i o n  was  a v a i l a b l e to d i f f e r e n t i a t e between the e f f e c t s of the v e g e t a t i o n  and  of the s i t e s . Comparisons of water chemistry  are c u r r e n t l y too l i m i t e d which may occur.  profiles  through s u c c e s s i o n a l time  t o s y n t h e s i z e a g e n e r a l p i c t u r e of any trends  The present  step i n t o a l a r g e l y unexamined  study, field.  even w i t h i t s l i m i t a t i o n s , was a  11 CHAPTER 3  DESCRIPTION OF THE STUDY AREAS  The water c h e m i s t r y p r o f i l e s used i n t h i s study were measured i n three s e p a r a t e stands w i t h i n a 500 m r a d i u s i n the U n i v e r s i t y of B r i t i s h Columbia  Research F o r e s t .  The U.B.C. Research F o r e s t i s l o c a t e d  approx-  i m a t e l y 60 km e a s t o f Vancouver near Haney, B.C. (maps on pages 69 and 70).  3-1  General D e s c r i p t i o n Feller  (1977) p r e s e n t e d a d e s c r i p t i o n of the c l i m a t e and geology of  the a r e a , a b r i e f The  summary  of which i s g i v e n here.  study areas were between 100 and 300 m e l e v a t i o n , w i t h a  m a t i c c l a s s i f i c a t i o n of C , a f t e r Kopnen (1936). rb  This designates a  £  marine warm temperate  rainy  (mesothermal) c l i m a t e .  Summer i s the d r i e s t  p a r t of the y e a r , but even the d r i e s t month r e c e i v e s an average of r a i n .  More than 70% of the t o t a l p r e c i p i t a t i o n  d u r i n g the p e r i o d o f October t o March. average mean d a i l y - temperature  1°C.  temperatures  and B i n k l e y , manuscript  (and n u t r i e n t s )  i n preparation).  and r a r e l y l a s t s f o r more  F i g u r e s 1 and 2 p r e s e n t the mean monthly  and monthly p r e c i p i t a t i o n f o r the 1972-1973 p e r i o d of the  o l d e r ecosystem WCP ecosystem  The  Fog and m i s t s a r e  amount of water  Snow a c c u m u l a t i o n i n w i n t e r i s u s u a l l y minimal than two weeks a t a time.  are mild.  falls  o f the warmest month ( J u l y ) i s 17°C;  common and p r o b a b l y add an undetermined (DeCatanzaro  of 3 cm  (about 250 cm)  Temperatures  the c o l d e s t month (January) averages about  to these f o r e s t s  cli-  study.  i n v e s t i g a t i o n and the 197 8 p e r i o d of the younger  The 1978 p e r i o d was g e n e r a l l y warmer and d r i e r  than  the 1972-1973 p e r i o d . The q u a r t z - d i o r i t e bedrock l a y e r of compacted  (basal) t i l l ,  i n the study areas i s o v e r l a i n by a which i s l a r g e l y impermeable to water  12  1973 F i g u r e 1.  1972  1978  Mean monthly temperatures, U.B.C. R e s e a r c h F o r e s t Note d i s c o n t i n u o u s time s c a l e .  Office.  30-  1973 F i g u r e 2.  1972  1978  Monthly p r e c i p i t a t i o n , U.B.C. R e s e a r c h F o r e s t Note d i s c o n t i n u o u s time s c a l e .  Office.  and i s not u s u a l l y p e n e t r a t e d by r o o t s .  Some seepage through the t i l l  p r o b a b l y o c c u r s around bedrock o u t c r o p s and l a r g e b o u l d e r s . of  quartz-diorite ablation t i l l  A blanket  m a t e r i a l o v e r l i e s the b a s a l t i l l ; i t  averages one meter i n depth. The s o i l s are Humo-Ferric P o d z o l s by the Canadian System of S o i l Classification to  (Canada S o i l Survey Committee 1978), which corresponds  the T y p i c H a p l o r t h o d subgroup of the U.S. System  1975).  The t e x t u r e s range from p r e d o m i n a n t l y loamy  ( S o i l Survey S t a f f sand to sandy  loam.  The c o a r s e (> 2 mm) fragment c o n t e n t of these s o i l s i s o f t e n 50% or more. The study a r e a s are w i t h i n the d r i e r subzone of the C o a s t a l Western Hemlock Zone of K r a j i n a  (1965, 1969).  Klinka  U.B.C. Research F o r e s t i n t o ecosystem u n i t s . study areas f a l l  (1976) c l a s s i f i e d the Under h i s scheme, the  i n t o the Polystichum-Western Red Cedar ecosystem type.  T h i s i s s i m i l a r t o the Tsuga h e t e r o p h y 1 1 a / P o l y s t i c h u m h a b i t a t type of the  Tsuga h e t e r o p h y l l a Zone of F r a n k l i n and Dyrness  index i s 52 m a t 100 y e a r s ( K l i n k a  3-2  The Younger  (1973).  The s i t e  1976).  Ecosystem  The younger ecosystem was a 15 ha D o u g l a s - f i r p l a n t a t i o n , l i s h e d i n 1960.  estab-  The s i t e was p r e v i o u s l y o c c u p i e d by a f o r e s t which  o r i g i n a t e d a f t e r a w i l d f i r e i n 1848; t h i s stand was logged and the s i t e s l a s h b u r n e d i n 1959. The dominant v e g e t a t i o n on the s i t e was D o u g l a s - f i r menziesii alder  (Mirb.) F r a n c o ) , v i n e maple  (Alnus r u b r a Bong.), b i t t e r  and b i g l e a f maple  (Pseqdotsuga  (Acer c i r c i n a t u m P u r s h ) , r e d  cherry  (Prunus emarginata D o u g l . ) ,  (Acer macrophyllum P u r s h . ) .  The u n d e r s t o r y shrubs  14 were salmonberry (Rubus s p e c t a b i l i s Pursh) and e l d e r b e r r y racemosa L . ) the  (Sambucus  Swordfern ( P o l y s t l c h u m munitum ( K a u l f . ) P r e s l . ) was  dominant f e r n , and v a r i o u s mosses were common. The younger ecosystem study s i t e was not an e n t i r e watershed;  s u b s u r f a c e seepage-water d r a i n e d i n t o the area from s e v e r a l hundred meters of upslope 70-110 y e a r - o l d f o r e s t .  Table A - l ,  i n the Appendix,  presents a s o i l p r o f i l e d e s c r i p t i o n f o r a t y p i c a l s o i l p i t .  3-3  The Older Ecosystem Feller  (1974, 1977) measured water chemistry p r o f i l e s  watersheds which supported 70-90 y e a r - o l d f o r e s t s . e s t a b l i s h e d a f t e r a w i l d f i r e i n 1868. the  i n two nearby  These f o r e s t s were  The dominant o v e r s t o r y s p e c i e s i n  o l d e r ecosystem were western hemlock  (Tsuga h e t e r o p h y l l a (Raf.)  S a r g . ) , D o u g l a s - f i r , and western red cedar (Thuja p l i c a t a Donn).  Vine  maple and b i g l e a f maple were common u n d e r s t o r y s p e c i e s , and swordfern was  the most common herbaceous s p e c i e s .  3-4  Biomass P o o l s and Turnovers F i g u r e s 3 and 4 p r e s e n t the estimated biomass p o o l s and turnover  r a t e s f o r the younger and o l d e r ecosystems, r e s p e c t i v e l y .  These  figures  were d e r i v e d from u n p u b l i s h e d d a t a and data from the l i t e r a t u r e f o r the o l d e r ecosystems  (Kimmins, unpub. d a t a , and DeCatanzaro 1979) and from  d a t a I c o l l e c t e d f o r the younger ecosystem.  The d e t a i l s o f these  methods, as w e l l as a d d i t i o n a l s i t e d e s c r i p t i o n i n f o r m a t i o n , a r e i n the Appendix.  No e s t i m a t e was made of belowground biomass or n u t r i e n t  t u r n o v e r s , and belowground dynamics can exceed aboveground.  For  example, a 70 to 100 y e a r - o l d D o u g l a s - f i r f o r e s t was estimated duce 8 to 10 tons h a ha  - 1  yr  _  1  of f o l i a g e  - 1  yr  _  1  of f i n e r o o t s as compared  to p r o -  t o 2 to 3 tons  (D. S a n t a n t o n i o , p e r s o n a l communication).  Aboveground Deciduous Overstary Biomass 47,600  Net Annual Aboveground| Increment 7,500  Net Annual Abovegroundj Production 15,500  Total Aboveground| Litterfall 8,000  Aboveground Understory Biomass 7,000  F o r e s t F l o o r Biomass 20,200 Decomposition from F o r e s t F l o o r 8,000  FIGURE 3.  Younger ecosystem estimated biomass p o o l s and t u r n o v e r s , d e t a i l s In Appendix  (kg/ha).  Net Annual Aboveground Biomass Increment 5,500  Aboveground Coniferous Overstory Biomass 424,300  Net Annual Aboveground Production •9.600  Total Aboveground Litterfall 3 ,500 Abovegroun Understory Biomass ??? (minor)  F o r e s t F l o o r Biomass  35,000  {Decomposition [from F o r e s t F l o o r 3 ,500  FIGURE 4.  Older ecosystem biomass p o o l s and t u r n o v e r s , d e t a i l s i n Appendix  (kg/ha).  17 The most important comparisons  to be made between F i g u r e s 3 and 4  are the g r e a t e r n e t annual aboveground net p r o d u c t i v i t y o f the younger The younger ecosystem at about 7,500 kg h a "  1  i n the o l d e r ecosystem aboveground  yr  ecosystem.  ( F i g u r e 3) accumulated aboveground -  1  - 1  yr  - 1  .  biomass  , about 35% more than the 5,700 kg h a  (Figure 4).  - 1  yr  -  1  The annual net p r o d u c t i v i t y f o r the increment and  The n e t (aboveground) p r o d u c t i v i t y of the younger  ecosystem was 15,500 kg h a  ecosystem.  increment and g r e a t e r  system was e s t i m a t e d by summing the biomass  the l i t t e r f a l l v a l u e s .  9,200 kg h a  biomass  - 1  yr  -  1  w h i l e t h a t of the o l d e r ecosystem was  P r o d u c t i v i t y was about 7 0% g r e a t e r i n the younger  As emphasized  i n the Appendix,  these e s t i m a t e s a r e v e r y  approximate and a r e p r e s e n t e d only f o r d e s c r i p t i v e purposes.  18  CHAPTER 4  4-1  METHODS  F i e l d Methods Water samples were c o l l e c t e d at s e v e r a l stages of water's  through the ecosystems: mineral s o i l  precipitation,  passage  throughfall, forest floor  l e a c h a t e s , s a t u r a t e d zone-water and stream-water.  t a t i o n and t h r o u g h f a l l samples were c o l l e c t e d  Precipi-  i n c o n t i n u o u s l y open  f u n n e l s , s o i l l e a c h a t e s from alundum d i s c l y s i m e t e r s , s a t u r a t e d water from p i t s  and  ( o l d e r ecosystem) and piezometers (younger  zone-  ecosystem)  and stream-water as grab samples a t the downstream b o u n d a r i e s of the study a r e a s . The 14 sampling s t a t i o n s f o r the younger ecosystem water c h e m i s t r y p r o f i l e study were l o c a t e d randomly  along f i x e d  transects.  S i t e s where  D o u g l a s - f i r r e g e n e r a t i o n dominated were e x c l u d e d a c c o r d i n g to the o r i g i n a l o b j e c t i v e s of the younger ecosystem study.  The 11 sampling s t a t i o n s used  here from the o l d e r ecosystem were s u b j e c t i v e l y chosen by F e l l e r to  represent biogeocoenotic u n i t s .  4-1-1  C o l l e c t i o n P e r i o d and  Interval  I c o l l e c t e d water c h e m i s t r y p r o f i l e d a t a f o r the younger from March through November 1978. the  (1974)  I extracted  the d a t a r e p r e s e n t i n g ,  o l d e r ecosystem from a long term p r o j e c t by M. C. F e l l e r .  p e r i o d s from March to J u l y of 1973 grouped  and August  to p r o v i d e a p e r i o d comparable  ecosystem  The  to November 1972 were  to the younger ecosystem study.  O l d e r ecosystem t h r o u g h f a l l data are from March through November of and stream-water v a l u e s are the annual averages from June 1972 May  1973.  A c o l l e c t i o n i n t e r v a l of 2 weeks was  the  summers lenghtened t h i s  interval.  1973,  through  planned; dry weather i n  19 4-1-2  Precipitation  Collections  P r e c i p i t a t i o n was c o l l e c t e d o n l y i n the o l d e r ecosystem study. p r e c i p i t a t i o n chemistry reported  i n t h i s t h e s i s i s from F e l l e r ' s  sampling p e r i o d of August 1972 to J u l y for  The  1973.  P r e c i p i t a t i o n chemistry  p a r t of the p e r i o d of the younger ecosystem study was c o l l e c t e d and  a n a l y z e d from o t h e r l o c a t i o n s i n the U.B.C. Research F o r e s t by DeCantanzaro  and B i n k l e y  (manuscript i n p r e p a r a t i o n ) and by C. P e r r i n  ( p e r s o n a l communication); n u t r i e n t c o n c e n t r a t i o n s were s i m i l a r measured by F e l l e r file  (1977).  to those  F o r the purposes of the water c h e m i s t r y p r o -  comparisons p r e s e n t e d here, I have assumed t h a t  precipitation  c h e m i c a l c o n c e n t r a t i o n s were the same f o r b o t h p e r i o d s . The p r e c i p i t a t i o n c o l l e c t o r s c o n s i s t e d of 15 cm diameter p o l y e t h y l ene f u n n e l s and 4 l i t e r p o l y e t h y l e n e b o t t l e s .  Nylon f i b e r p l u g s were  used i n the necks of the f u n n e l s to reduce c o n t a m i n a t i o n .  No b i o l o g i c  i n h i b i t o r was used i n the water b o t t l e s i n these s t u d i e s .  4-1-3  Throughfall  Collections  To reduce sample v a r i a b i l i t y , a double f u n n e l c o l l e c t o r d e s i g n was used i n the younger ecosystem study.  Two f u n n e l s of the type used f o r  p r e c i p i t a t i o n c o l l e c t i o n were connected to a 4 l i t e r b o t t l e .  The  f u n n e l s were l o c a t e d below the u n d e r s t o r y v e g e t a t i o n , c a t c h i n g water t h a t had passed through both the o v e r s t o r y and shrub l a y e r s sent).  (where p r e -  S i n g l e f u n n e l c o l l e c t o r s were used i n the o l d e r ecosystem study.  Nylon f i b e r p l u g s were used to reduce c o n t a m i n a t i o n .  4-1-4  S o i l Leachate C o l l e c t i o n s T e n s i o n l y s i m e t e r s were used to c o l l e c t  the  forest floor-mineral s o i l  soil  s o l u t i o n samples  i n t e r f a c e and from the m i n e r a l s o i l .  from  20 F i f t e e n c e n t i m e t e r alundum d i s c l y s i m e t e r s w i t h o u t s i d e w a l l s were used in  the younger  ecosystem, w h i l e those i n the o l d e r ecosystem  10 cm alundum d i s c s w i t h s i d e w a l l s . columns of  employed  Tensions were s u p p l i e d by hanging  of water w i t h h e i g h t s of 90 t o 100.cm, g i v i n g about 9 to 10 kPa  tension.  Due to the s h a l l o w depth to b a s a l t i l l ,  had o n l y 70 cm columns  i n the younger ecosystem.  some l y s i m e t e r s  Mineral s o i l  lysime-  t e r s were l o c a t e d 10 cm below  the A/;B h o r i z o n i n t e r f a c e i n the younger  ecosystem, and a t 60 cm below  the s u r f a c e i n the o l d e r  4-1-5  S a t u r a t e d Zone-Water  Collections  Piezometers were i n s t a l l e d younger ecosystem.  a t 10 of the 14 sampling s t a t i o n s i n the  The piezometers c o n s i s t e d of 5 cm diameter by 100 cm  long p l a s t i c p i p e s , p e r f o r a t e d near the base. the  ecosystem.  Rubber s t o p p e r s p l a c e d on  top of the p i p e i n h i b i t e d gas exchange w i t h the atmosphere.  Samples  were o b t a i n e d by i n s e r t i n g a tube i n t o the piezometer and e x t r a c t i n g water w i t h a s y r i n g e . sampled  In the o l d e r ecosystem, F e l l e r  s a t u r a t e d zone-water  from two covered s o i l  U n l i k e the t h r o u g h f a l l and s o i l  (1974, 1977)  pits.  leachate c o l l e c t i o n s ,  zone-water was composed of water from w i t h i n and beyond boundaries.  the s a t u r a t e d  the ecosystem  The younger ecosystem was not an e n t i r e watershed, i t r e -  c e i v e d f l o w from o l d e r upslope ecosystems.  Similarly,  the o l d e r eco-  system sampling s t a t i o n s were l o c a t e d i n mid- to l o w e r - s l o p e p o s i t i o n s , r e c e i v i n g flow from l e s s p r o d u c t i v e upslope communities. reported  f o r saturated  Concentrations  zone-water may l a r g e l y r e f l e c t w i t h i n  system  p r o c e s s e s , but the. u n q u a n t i f i e d c o n t r i b u t i o n from upslope seepage unavoidable  error.  added  21 4-1-6  Stream-water C o l l e c t i o n s No  stream  s i n g l e stream  d r a i n e d the e n t i r e younger ecosystem.  chosen to r e p r e s e n t  area; approximately  area.  were c o l l e c t e d by F e l l e r watersheds.  the younger ecosystem s u r f a c e d w i t h i n the  one-half  s l o p e of the study  The  of t h i s  stream's drainage b a s i n was  up-  Stream-water samples f o r the o l d e r ecosystem (1974, 1977)  Again, drainage  above the w e i r s of h i s study  from upslope  ecosystems  shed but not sampled f o r t h r o u g h f a l l or s o i l  ( w i t h i n the water-  l e a c h a t e ) c o n t r i b u t e to  the stream-water. T h i s boundary problem of the s a t u r a t e d zone- and  stream-water  samples r e p r e s e n t a problem i n n o n - q u a n t i f i e d i n p u t s of n u t r i e n t s to the d e f i n e d ecosystems. cannot a v o i d such  4-2  The water chemistry p r o f i l e  study  problems.  L a b o r a t o r y Methods Water samples were analyzed  (titratable day  as used i n t h i s  alkalinity  of c o l l e c t i o n .  to pH  f o r pH,.bicarbonate  4.5)  and  logic  activity  Nothing was  i n the samples d u r i n g s t o r a g e .  c a t i o n ) found no s i g n i f i c a n t C o n d u c t i v i t y was meter u s i n g a CDC An O r i o n model 404  104  specific  Feller  ( p e r s o n a l communistorage.  2e c o n d u c t i v i t y  ( a l l measurements a t 20°  i o n meter was  used i n pH  measured by  pH endpoint w i t h 0.0005 M HC1  the  added to i n h i b i t b i o -  measured w i t h a Radiometer CDM conductivity c e l l  the  or f r o z e n u n t i l  changes i n c o n c e n t r a t i o n s d u r i n g  B i c a r b o n a t e as t o t a l a l k a l i n i t y was quot to a 4.5  e l e c t r i c a l c o n d u c t i v i t y on  Samples were then r e f r i g e r a t e d  other a n a l y s e s c o u l d be performed.  concentration  to 25°C).  determinations.  t i t r a t i n g a 25 ml  standard.  communication) d i d a p o t e n t i o m e t r i c t i t r a t i o n and  found  Feller  ali-  (personal  t h a t an  endpoint  22 of  4.5  pH may  be lower  than the t r u e e q u i v a l e n c e p o i n t , r e s u l t i n g i n  an o v e r e s t i m a t e of b i c a r b o n a t e c o n c e n t r a t i o n .  Subsequent to the  measurements of these s t u d i e s , he d i s c o v e r e d some anomalies e l e c t r o d e used.  The pH v a l u e s f o r the o l d e r ecosystem may  too low.  f o r K,  for  Values  atomic  Ca, and Mg were determined  a b s o r p t i o n spectrophotometry  An a i r - a c e t y l e n e flame was a c e t y l e n e flame was  used  t r a t i o n s were determined  used  f o r Ca.  Sources Two  unavoidable  istry  The  by s t a n d a r d methods AA-5.  and  anion  concen-  w i t h s t a n d a r d methods on a Technicon  Auto-  1977).  first  sources of b i a s are i n h e r e n t i n the water  chemistry  one more c r e p t i n t o the e x p e r i m e n t a l methods of  i n h e r e n t s o u r c e of b i a s was  c o n c e n t r a t i o n s without  averages  units  of b i a s  p r o f i l e method, and study.  be 0.3  pH  and a n i t r o u s o x i d e -  Ammonium, s i l i c a  a n a l y z e r I I ( d e t a i l s g i v e n by F e l l e r  4-3  w i t h the  on a V a r i a n T e c h t r o n  f o r K and Mg  pH  this  i n the use of water chem-  a knowledge of water volumes.  The  calculated  are unweighted w i t h r e s p e c t to the q u a n t i t y of water they r e p -  r e s e n t i n the ecosystem.  A dry p e r i o d which produced  a s m a l l volume of  s o i l l e a c h a t e w i t h h i g h c o n c e n t r a t i o n s r e c e i v e d e q u a l weight i n averaging w i t h a sample from a w e t t e r p e r i o d w i t h more d i l u t e c o n c e n t r a t i o n s . The second of  averages.  source of i n h e r e n t b i a s a l s o i n v o l v e d the  As p r e s e n t e d i n t h i s  comparison,  calculation  averages were c a l c u l t e d  as the means of a l l water samples a n a l y z e d f o r each s t a g e of the systems. and  time.  These means were based  on samples which d i f f e r e d  eco-  i n both  location  L o c a t i o n s which c o n s i s t e n t l y c o l l e c t e d water d u r i n g dry  weather r e c e i v e d more weight i n the c a l c u l a t i o n s of the averages l o c a t i o n s which c o l l e c t e d o n l y  sporadically.  than  The water c h e m i s t r y p r o f i l e  comparisons  p r e s e n t e d here were mea-  sured i n d i f f e r e n t y e a r s , i n t r o d u c i n g the t h i r d source of b i a s .  Dif-  f e r e n c e s i n the q u a n t i t y , t i m i n g and c o m p o s i t i o n of p r e c i p i t a t i o n are unaccounted profiles  f o r i n the comparisons  (as d i s c u s s e d i n Chapter  hydrologically  p r e s e n t e d here. 5) suggest  However, the c h l o r i d e  the two time p e r i o d s were  similar.  These sources of b i a s were u n a v o i d a b l e g i v e n the c o n s t r a i n t s of the s t u d i e s and s h o u l d be kept i n mind when e v a l u a t i n g the which f o l l o w .  comparisons  24 CHAPTER 5  RESULTS AND DISCUSSION  5-1 Water Chemistry The  Profile  Comparisons  r e s u l t s o f the water c h e m i s t r y  ized i n Tables  3 t o 7.  t i o n s o f the chemicals  Tables  p r o f i l e comparisons a r e summar-  3, 4 and 5 l i s t  by p r o f i l e s t a g e .  the average  concentra-  Table 6 presents  the r a t i o s  of c o n c e n t r a t i o n s o f the younger ecosystem to the o l d e r ecosystem f o r each p r o f i l e s t a g e .  Table  7 compares stream-water c o n c e n t r a t i o n w i t h the  h i g h e s t c o n c e n t r a t i o n i n each p r o f i l e , p r o v i d i n g a r e l a t i v e index o f the r e d u c t i o n i n c o n c e n t r a t i o n o f the chemicals  b e f o r e the water l e a v e s the  ecosystem i n the stream. 5-1-1 C o n c e n t r a t i o n R a t i o s , Younger Ecosystem:Older Ecosystem Values  i n T a b l e 6 g r e a t e r than  1.0 i n d i c a t e t h a t the c o n c e n t r a t i o n s  i n the younger ecosystem exceeded those o f the o l d e r ecosystem.  The  o v e r a l l p a t t e r n showed h i g h e r c o n c e n t r a t i o n s i n the younger ecosystem's water.  The magnitude o f the d i f f e r e n c e v a r i e d g r e a t l y among the c h e m i c a l s ;  c h l o r i d e was c o n s i s t e n t l y w i t h i n 40% of the o l d e r ecosystem's c o n c e n t r a t i o n s , w h i l e n i t r a t e reached  54 times  g r e a t e r c o n c e n t r a t i o n s i n the younger eco-  system's f o r e s t f l o o r l e a c h a t e .  The o t h e r major f e a t u r e o f the r a t i o s  of the two ecosystems was t h a t the r a t i o s tended to decrease  i n the lower  p a r t o f the p r o f i l e s , i n d i c a t i n g a convergence i n the c o n c e n t r a t i o n s f o r s e v e r a l o f the c h e m i c a l s . 5-1-2 R a t i o s of Stream-Water C o n c e n t r a t i o n Values  i n Table 7 l e s s than  to P r o f i l e Maxima  1.0 i n d i c a t e t h a t the maximum concen-  t r a t i o n o f the chemical was i n a p r o f i l e stage o t h e r than  stream-water.  The maximum c o n c e n t r a t i o n i n the p r o f i l e - was commonly the f o r e s t  floor  25  T a b l e 3.  pH, c o n d u c t i v i t y and s i l i c a water c h e m i s t r y average ( s t a n d a r d e r r o r ) .  profiles,  pH  Conductivity US cm"  Precipitation  4.5 (<.l)  17 (<1)  2 (.2)  Throughfall Younger Older  5.88(.05)  34 (2)  2 (.3)  4.7K.03)  27 (2)  2 (.2)  Forest Floor Leachate Younger Older  5.58(.05) 5.77(.13)  77 (11) 39 (2)  Stage  ;  Mineral S o i l Leachate Younger Older Saturated Water Younger Older  1  SiC^ nmol'l  62 (8) 41 (5)  5.80(.ll)  73 (14)  73 (8)  6.5K.04)  23 (2)  46 (3)  5.65(.06) 6.3 (<.l)  27 (2) 19 ( 1)  95 (6) 47 (3)  6.5K.06)  21 (2) 20 (1)  111 (10) 78 (2)  Zone-  Stream-Water Younger Older  6.8 (<.l)  - 1  T a b l e 4.  Anion water c h e m i s t r y p r o f i l e s , . a v e r a g e ueq 1  Stage  CI"  N0 ~ 3  HC0  3  SO  '4  (standard  error).  Total 61 (2.1)  5(<1)  28 (2)  4( 1) 12 (2)  151(13)  16(05)  108 (5) 73(11)  297 (14) 126 (13)  50 (7) 61 (4)  270(36) 5 (2)  75 (8) 117(14)  77 (9) 120 (6)  472 (39) 303 (16)  Mineral S o i l Leachate Younger Older  35 (3) 31 (3)  136(23) 22 (7)  103(15) 126(14)  64 (7) 53 (8)  338 (29) 232 (18)  S a t u r a t e d ZoneWater Younger Older  36 (4) 25 (1)  50(11)  1(<D  131(14) 77 (9)  58 (6). 35 (2)  275 138  Stream-Water Younger Older  23 (2) 23 (1)  63 (9) 4(<1)  128 (8) 128 (3)  37 (4) 44 (2)  251 (13) 199 (4)  Precipitation  17 (<D  11(<D  Throughfall Younger . Older  34 (2) 27 (2)  Forest Floor Leachate Younger Older  (20) (9)  T a b l e 5.  C a t i o n water c h e m i s t r y p r o f i l e s , average ueq 1  a  +  Stage  -  Precipitation  31. 6(1. 5 )  Throughfall Younger Older  +  K  ,NH  +  Ca  ++  (standard^error).  Mg  ++  CD  ---  Td.tal  2( .1)  0. 50(,.06)  10 (.4)  2. 4(0. 4) 24. 1(2. 2)  106 (8) 22 (4)  1. 60(,.22) 0. 20(..07)  60 (5) 32 (5)  52 (6) 14 (2)  222.,0 (11. 2) 92.,3 (7. 1)  Forest Floor Leachate Younger Older  6. 3(2. 3) 8. 0(1. 8)  69 (9) 37 (3)  1. 42(,.31) 275(29) 0. 29(.,07) 157(12)  117(14) 41 (4)  468.,7 (33. 5) 243.,3 (13. 1)  Mineral S o i l Leachate Younger Older  4. 0(1. 1) 0. 4(<. 1)  35 (7) 7 (1)  1. 35(..25) 160(13) 0. 19(..09) 71 (7)  79 (9) 38 (3)  279..4 (17. 3) 116., 6 (7- 7)  S a t u r a t e d ZoneWater Younger Older  3. 2(0. 8) 0. 5  24 (5) 2( <D  1. 36(..40) 0. IK..03)  81 (8) 65 (2)  35 (3) 21 (1)  144. 6 88.. 6  (9. 9) (2. 3)  Stream-Water Younger Older  0. 3(<. 1) 0. a  5 (1) 2( <D  0. 08(..04) 0. 11(,,01)  83 (4) 75 (2)  33 (2) 26 (.4)  121.,4 103. 3  (4. 6) (2. 0)  a  2  a  5  49,.1  These H c o n c e n t r a t i o n s converted from average pH v a l u e s , not c a l c u l a t e d a v e r a g e s of i n d i v i d u a l H c o n c e n t r a t i o n s .  (1. 6)  as  T a b l e 6.  Water c h e m i s t r y p r o f i l e r a t i o s , younger e c o s y s t e m r o l d e r ecosystem.  Cond.  Stage  Cl~  N0 3  ++  Mg"^  K  8.0  1-9  3.7  4.8  1.0  4.9  1.8  2.9  1.9  1.5  7.1  2.3  2.1  5.0  1.6  12.0  2.0  2.5  1.4  +  Precipitation  (Assumed to be t h e same f o r both eco systems)  Throughfall  0.1  1.3  1.3  Forest Floor Leachate  0.8  2.0  0.8  Mineral S o i l Leachate  10.0  3.2  1.1  6.4  1.4  1.4  50.  12.4  1.3  1.7  1.5  1.0  1.0  16.  0.7  1.1  1.3 "  Saturated Water  Zone-  Stream-Water  0.3 54.  6.2  Si0  Ca  NH. 4  +  2  N3 00  T a b l e 7.  R a t i o s o f stream-water c o n c e n t r a t i o n  Conductivity  t o t h e p r o f i l e maximum c o n c e n t r a t i o n .  Cl"  NC> ~ 3  NH  + 4  Ca " 44  Mg""" 1  4  K  +  SiC>  Younger Ecosystem  0.273  0.460  0.233  0.050  0.302  0.282  0.047  1.0  Older Ecosystem  0.5.13  0.377  0.182  0.550  0.478  0.634  0.091  1.0  2  30 l e a c h a t e stage.  S i l i c a was the only c h e m i c a l which reached  c o n c e n t r a t i o n a t the stream-water Table 7 shows t h a t although  i t s maximum  stage. the younger ecosystem o f t e n had g r e a t e r  c o n c e n t r a t i o n s i n f o r e s t f l o o r l e a c h a t e than  the o l d e r ecosystem, the  r e d u c t i o n s i n c o n c e n t r a t i o n s i n the younger ecosystem were g e n e r a l l y r e l a t i v e l y g r e a t e r than i n the o l d e r ecosystem. n i t r a t e r a t i o s i n Table systems.  The c h l o r i d e and  7 are i n t e r e s t i n g l y v e r y s i m i l a r f o r the eco-  However, w h i l e  the a b s o l u t e c h l o r i d e c o n c e n t r a t i o n s  i n the two  ecosystems were v e r y c l o s e , the n i t r a t e l e v e l s d i f f e r e d by more an order  of magnitude.  than  On a r e l a t i v e s c a l e , however, the younger eco-  system's n i t r a t e c o n c e n t r a t i o n s were reduced  as much as i n the o l d e r  ecosystem.  5-1-3  Chloride The  c h l o r i d e water chemistry  profiles  (Table 4) were v e r y  similar.  Both ecosystems showed i n c r e a s i n g c h l o r i d e c o n c e n t r a t i o n s from p r e c i p i t a t i o n to t h r o u g h f a l l to f o r e s t f l o o r  l e a c h a t e s t a g e s , f o l l o w e d by  d e c r e a s i n g l e v e l s through the r e s t of the p r o f i l e .  The maximum  differ-  ence i n c h l o r i d e c o n c e n t r a t i o n s between the ecosystems was 40% (Table 6); the average d i f f e r e n c e was about 20%. C h l o r i d e has g e n e r a l l y been c o n s i d e r e d n o n - r e a c t i v e with  c h l o r i d e i n p u t s b a l a n c i n g outputs  i n ecosystems,  (see Juang and Johnson 1967,  Hem 1970, Bryck 1977, Johnson and Cole 1977, L i k e n s e t a l . 1977, and Vitousek  1977).  concentrations  Assuming the p r e c i p i t a t i o n and stream-water c h l o r i d e i n the p r e s e n t  c h l o r i d e balance precipitation  suggests  study  r e p r e s e n t annual averages, the  t h a t e v a p ' o t r a n s p i r a t i o n equaled  (or about 60-65 cm i n an average y e a r ) .  about 25% o f  This  estimate  31 c o i n c i d e s w i t h e s t i m a t e s by McNaughton and Research F o r e s t , The  Black  s u g g e s t i n g that c h l o r i d e i n p u t s  c h l o r i d e budget suggests t h a t  i n g unmeasured i n p u t s  intrasystem  chloride cycle.  intrasystem  c h l o r i d e c y c l e i n a 125  U l r i c h and  They e s t i m a t e d an uptake of 27 kg h a  chloride concentrations  increase  the  leaves,  pointing  to  an  Mayer (1971) found a s i m i l a r  year-old yr  - 1  - 1  beech f o r e s t i n Germany. of c h l o r i d e from the  soil,  (after pre-  subtracted).  Although the mechanism r e s p o n s i b l e  i s a valuable  The  l e v e l s of c h l o r i d e found i n t h r o u g h f a l l  c i p i t a t i o n c h l o r i d e was  son  impaction.  experienc-  from p r e c i p i t a t i o n to t h r o u g h f a l l p r o b a b l y  r e f l e c t s "wash-out" of c h l o r i d e from w i t h i n  which b a l a n c e d the  equal outputs.  the ecosystems are not  of c h l o r i d e from a e r o s o l  i n chloride concentration  (1973) f o r the U.B.C.  f o r the measured p r o f i l e s  remains s p e c u l a t i v e , t h e  p a r t o f t h i s study.  compari-  I f i t i s assumed t h a t the mechan-  ism (s) c o n t r o l l i n g the b e h a v i o r of the both ecosystems, then the s i m i l a r i t y  chloride p r o f i l e  of  c h l o r i d e anions was  of the c o n c e n t r a t i o n  g e s t s that  the water f l u x through each ecosystem was  hydrologic  b e h a v i o r of both ecosystems was  the  same f o r  profiles  similar.  s i m i l a r , then the  If  sugthe  concentra-  t i o n comparisons p r e s e n t e d i n t h i s study should approximate r e a l r e l a t i v e d i f f e r e n c e s i n the q u a n t i t i e s of the  chemicals.  comparisons are p r e s e n t e d i n terms of c o n c e n t r a t i o n s , might a l s o h o l d similarity  true f o r q u a n t i t i e s .  suggests t h a t the s e p a r a t e p e r i o d s  were s i m i l a r , and not  Finally,  the  Thus, a l t h o u g h  these comparisons  chloride  time.  profiles'  of the ecosystem  that observed d i f f e r e n c e s between the  completely confounded by  the  studies  ecosystem  are  32  5-1-4  p.H Two s t r i k i n g  f e a t u r e s of the pH water c h e m i s t r y p r o f i l e s  (Table 3)  were the i n c r e a s e i n pH i n the t h r o u g h f a l l i n the younger ecosystem and the h i g h e r pH l e v e l s i n the o l d e r ecosystem's The l a r g e d e c r e a s e i n a c i d i t y i n t h r o u g h f a l l  s o i l - and stream-waters. ( r i s e i n pH) beneath the  canopy of the younger ecosystem was a l s o accompanied i n HCO3  , K , and Mg  concentrations  (discussed  by l a r g e  increases  later).  The lower pH i n the s o i l s o l u t i o n of the younger ecosystem was accompanied  by a h i g h e r d e c o m p o s i t i o n r a t e  greater n i t r i f i c a t i o n rate  ( F i g u r e s 3 and 4) and a  (as d i s c u s s e d i n s e c t i o n 5-1-6).. Both p r o -  cesses tend to i n c r e a s e s o i l a c i d i t y  (decrease pH).  The s o i l pH be-  neath deciduous f o r e s t s i s commonly h i g h e r than the pH beneath ous f o r e s t s on s i m i l a r s o i l s  ( P r i t c h e t t 1979).  beneath red a l d e r are t y p i c a l l y one pH u n i t ( F r a n k l i n e t a l . 1968).  conifer-  However, the s o i l s  lower than under  conifers  These lower pH l e v e l s i n s o i l s o l u t i o n of the  younger ecosystem p a r a l l e l the lower pH l e v e l s found i n the s o i l  chemi-  c a l a n a l y s e s (Appendix T a b l e A-3).  5-1-5  Conductivity Specific electrical  ability  conductance i s a measure of a substance's  to conduct an e l e c t r i c c u r r e n t .  Pure water has a v e r y low con-  d u c t i v i t y , a few hundredths m i c r o s i e m e n s c m presence of i o n s i n c r e a s e s the a b i l i t y electric  -1  a t 25°C  (Hem 1970).  The  of a s o l u t i o n to conduct an  c u r r e n t so that as the i o n i c c o n c e n t r a t i o n i n c r e a s e s , the  conductivity increases.  T h e r e f o r e , c o n d u c t i v i t y p r o v i d e s an index of  the t o t a l i o n i c c o n c e n t r a t i o n of a s o l u t i o n . The c o n d u c t i v i t y p r o f i l e s tern.  (Table 3) showed a v e r y i n t e r e s t i n g p a t -  The c o n d u c t i v i t y of incoming p r e c i p i t a t i o n was assumed to be  33 identical,  and the c o n d u c t i v i t y of o u t g o i n g stream-water was found to  be the same f o r both ecosystems.  I n t e r m e d i a t e i n the p r o f i l e s ,  however, l a r g e d i f f e r e n c e s were e x h i b i t e d .  The c o n d u c t i v i t i e s of  f o r e s t f l o o r and m i n e r a l s o i l l e a c h a t e s were 2.0 and 3.2 times g r e a t e r , respectively,  i n the younger  ecosystem.  I n t e r p r e t a t i o n s about i n d i v i d u a l n u t r i e n t c o n c e n t r a t i o n s be drawn d i r e c t l y from c o n d u c t i v i t y .  cannot  N o n e t h e l e s s , the c o n d u c t i v i t y  water c h e m i s t r y p r o f i l e s r e v e a l e d much g r e a t e r i o n i c  concentrations  w i t h i n the younger ecosystem w h i l e output c o n c e n t r a t i o n s were i d e n t i c a l f o r b o t h ecosystems.  The shape o f the c o n d u c t i v i t y p r o f i l e s suggested  a g r e a t e r degree of c y c l i n g w i t h i n the younger ecosystem than w i t h i n the o l d e r  5-1-6  ecosystem.  N i t r a t e and Ammonium The n i t r a t e water c h e m i s t r y p r o f i l e s  (Table 4) were u s u a l l y  g r e a t e r than the ammonium water c h e m i s t r y p r o f i l e s l e a s t an o r d e r of magnitude  (Table 5) by a t  a t a l l s t a g e s of both ecosystems.  The  average ammonium l e v e l s were c o n s i s t e n t l y h i g h e r i n the younger system.  eco-  The l a r g e decrease i n ammonium c o n c e n t r a t i o n from the younger  ecosystem's seepage-water processing  to the stream may have been due t o stream  through uptake by the b i o t a or n i t r i f i c a t i o n .  The two ecosystems were more d i s s i m i l a r i n t h e i r n i t r a t e than i n any o t h e r p r o f i l e . .  profiles  The l e v e l s o f n i t r a t e i n t h r o u g h f a l l were  lower i n the younger ecosystem than i n p r e c i p i t a t i o n , s u g g e s t i n g a n e t uptake of n i t r a t e by the hardwood f o l i a g e .  Such an uptake was n o t  apparent i n the o l d e r ecosystem, which suggests a second No b i o l o g i c i n h i b i t o r was added  to the t h r o u g h f a l l  interpretation.  collectors,  34 t h e r e f o r e the observed d e c r e a s e i n n i t r a t e l e v e l s i n the younger system c o u l d be due to m i c r o b i a l uptake w i t h i n the c o l l e c t o r . lower pH o f the o l d e r ecosystem's  eco-  The  t h r o u g h f a l l might have reduced such  activity. The average n i t r a t e c o n c e n t r a t i o n i n the younger ecosystem f l o o r l e a c h a t e was 270 yeq l ecosystem.  -  1  compared to only 5 yeq l  -  1  i n the o l d e r  The maximum c o n c e n t r a t i o n r e c o r d e d f o r the younger  system's f o r e s t f l o o r l e a c h a t e was over 1,000 yeq l n i t r a t e were n o t r e s t r i c t e d forest floor  -  1  .  forest  eco-  High l e v e l s of  to the s o i l s o l u t i o n under red a l d e r ; one  l y s i m e t e r w i t h no a l d e r w i t h i n 15 meters had peak n i t r a t e  c o n c e n t r a t i o n s o f over 500 yeq l  -  1  .  The r a t i o s o f n i t r a t e c o n c e n t r a t i o n s i n two ecosystems p r e s e n t e d i n Table 6 show d e c r e a s i n g r a t i o s from 54 a t the f o r e s t at the stream-water s t a g e .  f l o o r stage to 16  Although the younger ecosystem had c o n s i s t -  e n t l y h i g h e r n i t r a t e c o n c e n t r a t i o n s , the r e l a t i v e decrease  i n nitrate  c o n c e n t r a t i o n s from one stage to the next was g r e a t e r than i n the o l d e r ecosystem  (Table 7 ) .  C o n t r a r y to the p a t t e r n i n the m a j o r i t y of the water c h e m i s t r y p r o files,  the n i t r a t e l e v e l s i n the younger ecosystem's  times g r e a t e r than the o l d e r ecosystem's stream.  stream averaged 16  The younger  ecosystem  was n o t n e c e s s a r i l y l e s s capable o f r e t a i n i n g n i t r o g e n . .The s y m b i o t i c n i t r o g e n f i x a t i o n by the r e d a l d e r would i n p u t to the younger  have g r e a t l y i n c r e a s e d the  ecosystem.  No attempt was made to measure n i t r o g e n f i x a t i o n i n the younger ecosystem.  In a study on Vancouver  I s l a n d a t 510 m e l e v a t i o n ,  Binkley  (manuscript i n p r e p a r a t i o n ) e s t i m a t e d the i n p u t of n i t r o g e n from r e d a l d e r to a 15 to 20 y e a r - o l d D o u g l a s - f i r p l a n t a t i o n .  Based on the  35 a c e t y l e n e r e d u c t i o n technique n i t r o g e n f i x a t i o n estimate The  and the q u a n t i t y of r e d a l d e r nodules,  o f 130 to 215 kg h a  - 1  yr  -  1  a  was d e r i v e d .  r e d a l d e r b a s a l a r e a was almost twice as high i n the Vancouver  I s l a n d study Therefore  than i n the p r e s e n t  (13.9 m  2  ha  - 1  v s . 7.6 m  2  - 1  ).  that between 65 and 110 kg-N h a  - 1  yr  -  1  the younger ecosystem v i a the r e d a l d e r component of the ecosystem. This estimate  i s many times g r e a t e r than the p r e c i p i t a t i o n i n p u t o f  n i t r o g e n to these 1974).  ecosystems, estimated  a t 1-2 kg h a  yr  - 1  -  1  (Feller  Although this, n i t r o g e n f i x a t i o n r a t e i s only an e s t i m a t e , i t  does suggest much g r e a t e r n i t r o g e n . i n p u t  to the younger ecosystem.  T o t a l n i t r o g e n was n o t measured r e g u l a r l y ; however, o r g a n i c gen  ha  as a rough approximation of the n i t r o g e n f i x a t i o n i n p u t to  the younger ecosystem, I estimate enter  study  nitro-  accounted f o r 25% to 65% o f the t o t a l n i t r o g e n f o r a few samples  which were analyzed.  C l e a r l y , o r g a n i c n i t r o g e n i s a major component of  the n i t r o g e n p i c t u r e , and i t i s u n f o r t u n a t e i n these  5-1-7  that i t was n o t measured  studies.  Silica Silica  interest  i s not considered  i n t h i s study,  an e s s e n t i a l p l a n t n u t r i e n t .  however, i n r e l a t i o n  of o t h e r elements from s o i l  to the weathering r e l e a s e  minerals.  S i l i c a does n o t d i s s o c i a t e i n t o i o n i z e d s i l i c i c 8.5.  Therefore,  a c i d below pH  the s i l i c a found i n the s o l u t i o n s of t h i s study would  be i n the hydrated  nonionic  (I^SiO^) form.  monomolecular, and has a s o l u b i l i t y 1970).  I t was of  The primary source  T h i s form i s t y p i c a l l y  of about 115 mg l  -  1  a t 2 5 ° C (Hem  of s i l i c a i n the s o i l s o l u t i o n and stream-  water i s from the weathering of s i l i c a t e  minerals.  36 Once s i l i c a the ecosystem  i s r e l e a s e d from s i l i c a t e m i n e r a l s , i t t r a v e l s  w i t h few  interactions  e x c e p t i o n s to t h i s g e n e r a l i z a t i o n .  (Hem  1970).  First,  There are two  amount accumulated  in biologic  Second, s i l i c a  form secondary decreases  The  t i s s u e s i s p r o b a b l y a s m a l l p o r t i o n of i n the ecosystems of  ( B i r k e l a n d 1974).  leachate s i l i c a  term l y s i m e t e r study.  i n the  can recombine w i t h aluminum and o t h e r metals  clay minerals  in soil  silica  ( K l e i n and Geis 1978).  the amount r e l e a s e d through m i n e r a l weathering study.  possible  some accumulation of  ( " p h y t o l i t h s " ) occurs i n many groups of the f a m i l y Pinaceae, g r a s s f a m i l y Poaceae and some o t h e r taxa  through  Windsor  this to  (1969) found  c o n c e n t r a t i o n s w i t h depth i n a s h o r t -  He assumed the decrease c o u l d not be due  to  changes i n the q u a n t i t y of water, and h y p o t h e s i z e d a r e c o m b i n a t i o n of s i l i c a w i t h s e s q u i o x i d e s to form secondary The most s t r i k i n g was  their similarity  clay minerals.  f e a t u r e o f the s i l i c a water c h e m i s t r y  profiles  i n shape, w i t h c o n c e n t r a t i o n s c o n s i s t e n t l y 40 to  100% h i g h e r i n the younger ecosystem  (Table 3).  e x p l a n a t i o n s f o r the d i f f e r e n c e i n weathering  There are two  possible  r e l e a s e of s i l i c a .  The  m i n e r a l o g i c c o m p o s i t i o n of the q u a r t z - d i o r i t e t i l l parent m a t e r i a l s may  d i f f e r between the two ecosystems.  r e l e a s e c o u l d be  A l t e r n a t e l y , the h i g h e r  the r e s u l t of more r a p i d m i n e r a l weathering  lower pH or more a c t i v e o r g a n i c c h e l a t i o n i n the younger For the purposes demonstrates  of t h i s study, the s i l i c a p r o f i l e  the weathering  r e l e a s e of s i l i c a  may  r e l e a s e ) of n u t r i e n t  to  comparison  (and of n u t r i e n t c a t i o n s )  have e x p e r i e n c e d a g r e a t e r i n p u t cations.  due  ecosystem.  should not be assumed to have been e q u a l f o r both ecosystems. younger ecosystem  silica  The  (weathering  37 5-1-8 Calcium The  and Magnesium  p r o f i l e s f o r c a l c i u m and magnesium  are discussed together.  As w i t h s i l i c a ,  ( T a b l e 5) were s i m i l a r and  the p a t t e r n s f o r the two eco-  systems were remarkably s i m i l a r , w i t h the younger ecosystem's p r o f i l e s c o n s i s t e n t l y higher. at  However, the p r o f i l e s f o r the ecosystems converged  the s a t u r a t e d zone and stream-water s t a g e s .  magnesium c o n c e n t r a t i o n s  40% suggested  system.  c a l c i u m and  i n stream-water were 10% and 30% g r e a t e r , r e s -  p e c t i v e l y , i n the younger ecosystem, the s i l i c a of  Although  concentration difference  g r e a t e r m i n e r a l weathering r a t e s i n the younger eco-  R e f e r i n g to T a b l e  6, the r a t i o s for c a l c i u m and magnesium i n  the younger to o l d e r ecosystem decreased  from the m i n e r a l s o i l  stage to s a t u r a t e d zone and stream-water s t a g e s .  leachate  These decreases  p r o p o r t i o n a l l y g r e a t e r i n the younger ecosystem, s u g g e s t i n g  were  t h i s system  may r e t a i n a g r e a t e r p r o p o r t i o n of the d i s s o l v e d c a t i o n s .  5-1-9  Potassium The  shapes of the  potassium  profiles  ( T a b l e 5) were s i m i l a r f o r  the ecosystems; the major d i f f e r e n c e was the much g r e a t e r wash-out from the deciduous canopy of the younger ecosystem. have been r e g u l a t e d by l e a f c h a r a c t e r i s t i c s , .layer  The g r e a t e r wash-out c o u l d  such as l e a f area or c u t i c l e  composition. Interestingly,  t h e r e was a f i v e - f o l d decrease  i n potassium  concen-  t r a t i o n s i n the younger ecosystem from the s a t u r a t e d zone to the streamwater s t a g e s .  The potassium  i o n i s h i g h l y l a b i l e w i t h i n ecosystems, and  I have no e x p l a n a t i o n f o r the s u r p r i s i n g decrease  i n concentrations.  However, both ecosystems appear to be e f f i c i e n t l y r e t a i n i n g  potassium,  as shown by the l a r g e r e d u c t i o n s i n c o n c e n t r a t i o n s through the lower  profiles.  38 5-2  R e l a t i v e Anion D i s t r i b u t i o n The p r o f i l e s  f o r the t o t a l a n i o n c o n c e n t r a t i o n s  major d i f f e r e n c e s between cipitation,  S u l f a t e dominated i n p r e -  f o l l o w e d by c h l o r i d e , n i t r a t e and b i c a r b o n a t e .  t a n t d i f f e r e n c e s between stage.  the ecosystems.  First,  by the crowns  i n the younger ecosystem d e c r e a s e d the importance of anion.  The d i f f e r e n c e s between r e s t of the p r o f i l e s .  the t h r o u g h f a l l  was In the  anions.  the two ecosystems p e r s i s t e d  The a n i o n r a n k i n g f o r the younger  through the ecosystem's  was N0 ~ 3  > HC0 ~  = S0 ~~  3  > Cl~.  h  Along w i t h i n c r e a s i n g pH and d e c r e a s i n g NO3  through the younger eco-  system's p r o f i l e , b i c a r b o n a t e became the dominant zone- and stream-water. p a t t e r n was  This  by an i n c r e a s e of almost one-and-a-half pH u n i t s .  leachate  impor-  an apparent net uptake of n i t r a t e from p r e c i p i t a t i o n  o l d e r ecosystem, s u l f a t e dominated  soil  Two  the ecosystems were found a t the t h r o u g h f a l l  t h i s a n i o n w h i l e b i c a r b o n a t e became the dominant accompanied  (Table 4) show  present  anion i n saturated  In the o l d e r ecosystem, however, a c o n s i s t e n t  from the f o r e s t  floor  l e a c h a t e through stream-  water : HC0 ~ 3  Not s u r p r i s i n g l y ,  > SOL, " > C l ~ > N 0 ~ . -  3  the major d i f f e r e n c e s between  the two ecosystems i n v o l v e d  the a n i o n i c r a t i o s of  the n i t r a t e and b i c a r b o n a t e i o n s .  latter reflected  i n part  t h a t accompanied  the changes i n n i t r a t e  The  the change i n hydrogen i o n c o n c e n t r a t i o n s concentrations.  39 5-3  Relative Cation The  Distribution  c a t i o n d i s t r i b u t i o n s were more s i m i l a r between the ecosystems  than were anion d i s t r i b u t i o n s . magnesium and potassium systems.  The  r e l a t i v e magnitudes of. the  c o n c e n t r a t i o n s were s i m i l a r f o r both  calcium,  eco-  O v e r a l l , c a l c i u m c o n c e n t r a t i o n s were g r e a t e r than magnesium  c o n c e n t r a t i o n s which i n t u r n exceeded potassium hydrogen i o n was  important  p r i m a r i l y i n p r e c i p i t a t i o n and,  ecosystem, i n t h r o u g h f a l l . l a r i t y was  found  concentrations.  The major e x c e p t i o n  The  i n the o l d e r  to t h i s o v e r a l l s i m i -  a t the t h r o u g h f a l l stage, where potassium  dominated  i n the younger ecosystem w h i l e hydrogen i o n s dominated i n the o l d e r ecosystem.  5-4  Cation:Anion In o r d e r  Balances  to m a i n t a i n  of c a t i o n s must balance  electric neutrality,  the t o t a l e q u i v a l e n t s of anions.  of the t o t a l columns of T a b l e s 4 and t h i s balance. ences.  the t o t a l  Three b a s i c reasons  Comparisons  5 show s e v e r a l d i s c r e p a n c i e s i n  are advanced to e x p l a i n the  F i r s t , not a l l of the i n o r g a n i c i o n s p r e s e n t  samples were measured.  equivalents  differ-  i n the water  Sodium, i r o n and manganese made up a  substan-  t i a l p o r t i o n of the c a t i o n t o t a l f o r the o l d e r ecosystem but were not measured f o r the younger ecosystem.  These elements c o n t r i b u t e d 20%  the c a t i o n t o t a l i n the f o r e s t f l o o r l e a c h a t e i n F e l l e r ' s which n i c e l y balances  the f o r e s t f l o o r a n i o n  Second, the b i c a r b o n a t e too h i g h  estimates  ( F e l l e r , p e r s o n a l communication).  be of importance i n the c a t i o n : a n i o n The pared  sum  (1977) study,  t o t a l from Table  (as t o t a l a l k a l i n i t y ) may  of  4.  have been  F u r t h e r , o r g a n i c ions c o u l d  balances.  of the c o n d u c t i v i t i e s of the measured i o n s can be com-  to the measured c o n d u c t i v i t y of a s o l u t i o n as a check f o r the  presence  of unmeasured i o n s .  U s i n g standard v a l u e s f o r the c o n d u c t i -  v i t i e s of the i n d i v i d u a l i o n s (Golterman i o n i c sum  and  Cly-mo 1969), I c a l c u l a t e d  c o n d u c t i v i t i e s f o r each stage of each ecosystem.  calculated  c o n d u c t i v i t i e s are p r e s e n t e d  measured c o n d u c t i v i t i e s .  i n Table 8 together with  the  Where the measured c o n d u c t i v i t y exceeds  calculated,  the presence  suggested.  Based on F e l l e r ' s  manganese might add  These  the  of unmeasured s p e c i e s or a n a l y t i c a l e r r o r i s (1977) c a t i o n t o t a l s , sodium, i r o n  from 5% to 10%  to the c a l c u l a t e d  and  conductivities.  No o t h e r major i n o r g a n i c i o n s were unmeasured, s u g g e s t i n g c o n s i d e r a b l e importance soil  l e a c h a t e s of the younger ecosystem.  found and  f o r unmeasured o r g a n i c i o n s i n the f o r e s t f l o o r and  to be important  Schofield  Organic anions have been  s p e c i e s i n o t h e r s t u d i e s (Johnson  1979), where they have been used  1975,  to account  comparisons, for  of o r g a n i c i o n s , as i n d i c a t e d by  which i t was  a n a l y z e d , combine to underscore  the c o n d u c t i v i t y samples  the importance  of  profiles.  Comparisons With Other Water Chemistry A s i d e from the two  Profile  Studies  r e s e a r c h p r o j e c t s compared here, no  other  s t u d i e s have examined water chemistry p r o f i l e s i n low e l e v a t i o n f o r e s t s i n B r i t i s h Columbia.  Ballard for  coastal  S e v e r a l i n v e s t i g a t i o n s have, however,  examined n u t r i e n t c o n c e n t r a t i o n s i n s o i l l e a c h a t e and Bourgeois  dif-  anions.  a l o n g w i t h the o r g a n i c n i t r o g e n found i n the few  o r g a n i c compounds i n water chemistry  5-5  Cronan  f o r the  f e r e n c e s i n charge balance between the measured c a t i o n s and The presence  mineral  and L a v k u l i c h (1972), K l i n k a (1976) and  stream-water.  Otchere-Boateng  and  (1978) p r e s e n t e d data on s o i l s o l u t i o n n u t r i e n t c o n c e n t r a t i o n s  ecosystems i n the U.B.C. Research  F o r e s t which were s i m i l a r  to the  41  Table  .8.  C o n d u c t i v i t y balance,  Stage  us  cm  -i  Younger Ecosystem Calculated  Measured  Older  Ecosystem  Calculated  Measured  Precipitation  17  17  17  ' 17  Throughfall  33  34  22  27  Forest Floor Leachate  63  77  37  39  Mineral S o i l Leachate  40  73  21  23  Saturated Water  26  27  15  19  22  21  20  20  Zone-  Stream-Water  Sum of the c o n d u c t i v i t i e s of hydrogen, c a l c i u m , magnesium, p o t a s s i u m n i t r a t e , c h l o r i d e , b i c a r b o n a t e and s u l f a t e . C o n t r i b u t i o n s to c o n d u c t i v i t y from ammonium, phosphate and h y d r o x y l i o n s was n e g l i g i b l e .  42  o l d e r ecosystem of t h i s study. ces which would suggest  There appear to be no major d i f f e r e n -  t h a t the o l d e r ecosystem data i n t h i s  are not r e p r e s e n t a t i v e of s i m i l a r mixed c o n i f e r Johnson  study  stands.  (1975) p r o v i d e d water chemistry p r o f i l e data f o r a 45  y e a r - o l d D o u g l a s - f i r p l a n t a t i o n i n the A. E. Thompson f o r e s t near S e a t t l e , Washington. of the p r e s e n t  H i s s i t e was  study, but  l e s s p r o d u c t i v e than the ecosystems  the t o t a l anion and  f o l l o w e d s i m i l a r p a t t e r n s to those of my  cation concentrations  study.  His t o t a l  concentra-  t i o n s were i n t e r m e d i a t e between the c o n c e n t r a t i o n s of the younger o l d e r ecosystems of my  study;  c h l o r i d e c o n c e n t r a t i o n s were c o n s i s t e n t l y  h i g h e r , but f o l l o w e d a v e r y s i m i l a r p a t t e r n through n i t r a t e was Johnson's W.  the p r o f i l e ,  while  below d e t e c t i o n l i m i t s a f t e r the p r e c i p i t a t i o n stage i n study.  Graustein's  c e s s i o n a l aspen and  ( p e r s o n a l communication) comparisons of e a r l y l a t e s u c c e s s i o n a l s p r u c e - f i r ecosystems i n  Mexico, d i s c u s s e d i n Chapter  2, found  g r e a t e r stream-water  t i o n s of c a t i o n s and n i t r o g e n i n h i s o l d e r ecosystem. between h i s two study.  and  New  concentra-  The d i f f e r e n c e s  ecosystems are more pronounced than found  However, h i s o l d e r ecosystem was  suc-  an old-growth  in this  forest,  while  •the o l d e r ecosystem of the p r e s e n t study would s t i l l be c o n s i d e r e d be growing a t a r a p i d  5-6  rate.  Dominant Anions and Cole and Johnson  to  Cations  (1979) s t a t e that the dominant a n i o n i n s o i l  l e a c h a t e s i n D o u g l a s - f i r ecosystems i s b i c a r b o n a t e .  This conclusion  i s based on s t u d i e s on a low p r o d u c t i v i t y , S i t e C l a s s IV ecosystem. The  o l d e r ecosystem of the p r e s e n t  study was  much more p r o d u c t i v e ,  and  43 b i c a r b o n a t e was saturated  still  the dominant anion i n m i n e r a l s o i l  zone-water and  bicarbonate  stream-water.  leachate,  However, f o r e s t f l o o r  leachate  c o n c e n t r a t i o n s were matched by s u l f a t e c o n c e n t r a t i o n s .  F u r t h e r , i n the younger ecosystem n i t r a t e dominated a n i o n s ; but a g a i n , b i c a r b o n a t e was  the s o i l  leachates  dominant i n the s a t u r a t e d zone and  stream-water. In the old-growth  D o u g l a s - f i r f o r e s t at the H. J . Andrews E x p e r i -  mental F o r e s t i n Oregon, the p a t t e r n i s d i f f e r e n t . dominant a n i o n i n p r e c i p i t a t i o n ,  t h r o u g h f a l l and  a t e s and s u l f a t e dominated i n the m i n e r a l s o i l in press). and  Not  The  florest  floor  leachates  a l l major anions were determined  stream-water f o r t h i s  C h l o r i d e i s the  ( S o l l i n s et a l .  f o r s a t u r a t e d zone  ecosystem.  l a t e - s u c c e s s i o n a l s p r u c e - f i r water chemistry p r o f i l e s  Graustein  ( p e r s o n a l communication) a l s o showed a p a t t e r n that  from the dominant b i c a r b o n a t e a n i o n p r o f i l e .  and m i n e r a l s o i l l e a c h a t e . to the b i c a r b o n a t e  Only  of differed  R e l i a b l e c h l o r i d e data  are not a v a i l a b l e , but s u l f a t e dominated i n p r e c i p i t a t i o n ,  shift  leach-  throughfall,  i n stream-water d i d the dominance  anion.  In G r a u s t e i n ' s e a r l y - s u c c e s s i o n a l aspen ecosystem, b i c a r b o n a t e dominated from the t h r o u g h f a l l stage through  to the stream-water stage.  J u s t as the dominant a n i o n s h i f t e d from n i t r a t e s u c c e s s i o n a l comparison of the p r e s e n t study, shifted The  from b i c a r b o n a t e  to b i c a r b o n a t e i n the  the dominant  to s u l f a t e i n the n o r t h e r n New  anion  Mexico  study.  r e l a t i v e dominance of c a t i o n s i n G r a u s t e i n ' s study d i d not g r e a t l y  d i f f e r between h i s two  ecosystems, and  i d e n t i c a l to the p a t t e r n found study.  the p a t t e r n of Ca > Mg  f o r both ecosystems of the  > K is  present  I t appears t h a t r e l a t i v e anion dominance i s s t r o n g l y by the s u c c e s s i o n a l s t a g e ( v e g e t a t i o n ) p a t t e r n of c a t i o n dominance, t i v e to v e g e t a t i o n a l changes.  influenced  of an ecosystem, w h i l e the  Ca > Mg > K, appears to be l e s s s e n s i Anion dominance appears r e g u l a t e d i n  p a r t by the b i o t a of the ecosystem, and c a t i o n dominance l a r g e l y by geochemical  5-7  processes.  Nutrient  Depletion  Cole e t a l . (1978) p r e s e n t e d e s t i m a t e s of c a l c i u m the r o o t i n g zone f o r a 38 y e a r - o l d D o u g l a s - f i r ecosystem. the a l d e r ecosystem. water of the p r e s e n t tem  leaching  a l d e r ecosystem and a 48  They e s t i m a t e d a 25% g r e a t e r Calcium concentrations  below  year-old  l o s s of Ca from  i n the s a t u r a t e d  zone  study averaged 25% g r e a t e r  i n the younger  ecosys-  ( D o u g l a s - f i r - r e d a l d e r ) , w h i l e stream-water  concentrations  were  about 10%  greater.  F r a n k l i n e t a l . (1968) compared s o i l p r o p e r t i e s beneath r e d a l d e r and D o u g l a s - f i r .  The s o i l pH beneath the a l d e r was  lower than beneath the D o u g l a s - f i r . had o n l y o n e - t h i r d  about one u n i t  T h e i r a l d e r ecosystem s o i l  the exchangeable c a l c i u m  and o n e - s i x t h  the  also  exchange-  a b l e magnesium found i n t h e i r D o u g l a s - f i r ecosystem's  soil.  et  i n biomass,  a l . (1968) d i d not measure the Ca and Mg  speculated biomass,  that u n l e s s  contained  the s i t e of these m i n e r a l s .  depleting  S i m i l a r l y , Cole e t a l . (1978) found  l e s s exchangeable Ca beneath t h e i r a l d e r ecosystem.  calcium  than the D o u g l a s - f i r ecosystem.  14%  However, the  and f o r e s t f l o o r of the a l d e r ecosystem c o n t a i n e d  exchangeable p o o l s ,  and  the decreased Ca and Mg were accumulated i n  the lower s o i l pH of the a l d e r ecosystem c o u l d be  vegetation  Franklin  Summing the biomass  t h e i r a l d e r ecosystem had o n e - t h i r d more  65% more and  soil  calcium.  Despite  the 10-25% g r e a t e r c a l c i u m c o n c e n t r a t i o n s i n the waters  l e a v i n g the younger ecosystem of the p r e s e n t dence of c a l c i u m d e p l e t i o n from the s i t e .  study,  there was no e v i -  On a meq 100 g  - 1  b a s i s , exchangeable c a l c i u m i s s i m i l a r f o r both ecosystems Table A-3).  The younger ecosystem r e t u r n e d  much Ca i n aboveground l i t t e r f a l l content  The c a l c i u m  of the aboveground s t a n d i n g biomass was not e s t i m a t e d .  Fur-  that m i n e r a l n u t r i e n t r e l e a s e from  and secondary m i n e r a l s may have been g r e a t e r i n the younger  ecosystem. composition;  The i n c r e a s e c o u l d have been due to d i f f e r e n c e s i n m i n e r a l however, the g r e a t e r a c i d i t y  the younger ecosystem suggests been o c c u r r i n g .  (one-half u n i t  lower pH) i n  i n c r e a s e d r a t e s of weathering may have  In a d d i t i o n , the a c t i v i t y  o f o r g a n i c c h e l a t i n g agents  could have been g r e a t e r i n the younger ecosystem. exchangeable c a l c i u m and magnesium observed and  (Appendix  almost three times as  (Appendix Table A-5).  t h e r , the s i l i c a p r o f i l e suggested primary  of s o i l  The decreases i n  by F r a n k l i n e t a l . (1968)  Cole e t a l . (197 8) may be due to a g r e a t e r accumulation  elements i n biomass and a s h i f t s i t e s due to the lower s o i l pH.  of these  i n c a t i o n d i s t r i b u t i o n s on exchange These apparent decreases  i n Ca and  Mg may be more than o f f s e t by i n c r e a s e d i n p u t from m i n e r a l w e a t h e r i n g , r e s u l t i n g i n a net increase i n n u t r i e n t c a t i o n pools.  5-8  N u t r i e n t R e t e n t i o n Through S u c c e s s i o n a l Time In 1969, Odum p u b l i s h e d a summary of trends  s u c c e s s i o n a l time.  to be expected  One such t r e n d was t h a t the a b i l i t y  through  of ecosystems  to r e t a i n incoming n u t r i e n t s i n c r e a s e d through s u c c e s s i o n a l time. d i d not s p e c i f y i f t h i s a p p l i e d to primary both.  V i t o u s e k and R e i n e r s  He  or secondary s u c c e s s i o n , or  (1975, 1976) countered  this  statement  46 through  the l o g i c a l argument t h a t :  i f the r e t e n t i o n of n u t r i e n t s  by  ecosystems i s p r o p o r t i o n a l to the accumulation of n u t r i e n t s i n b i o mass, then an ecosystem  w i t h a steady s t a t e accumulation  (climax community) must be l e s s e f f i c i e n t some p r e v i o u s s u c c e s s i o n a l stage.  at r e t a i n i n g n u t r i e n t s  V i t o u s e k and R e i n e r s  p r e s e n t e d a g r a p h i c a l model of ecosystem  of biomass  (1975,  than 1976)  biomass a c c u m u l a t i o n ,  and  h y p o t h e s i z e d t h a t n u t r i e n t r e t e n t i o n would f o l l o w i n synchrony. V i t o u s e k and R e i n e r s  (1979) e l a b o r a t e d t h i s h y p o t h e s i s by  Gorham,  listing  f a c t o r s which r e g u l a t e n u t r i e n t r e t e n t i o n and v a r y through s u c c e s s i o n a l time.  Bormann and L i k e n s  (1979) f u r t h e r e l a b o r a t e d on the n u t r i e n t -  r e t e n t i o n - a n d - s u c c e s s i o n a l - t i m e theme, d i v i d i n g  the biomass accumula-  t i o n model i n t o f o u r phases r e p r e s e n t i n g s u c c e s s i o n a l development. The R e o r g a n i z a t i o n Phase begins secondary  s u c c e s s i o n , and  i s character-  i z e d by a net l o s s of biomass and n u t r i e n t s from the ecosystem.  An  A g g r a d a t i o n Phase r a p i d l y f o l l o w s , w i t h maximum r a t e s of biomass and nutrient accretion.  I f u n d i s t u r b e d , an ecosystem  would then  pass  through a n e g a t i v e biomass accumulation T r a n s i t i o n Phase i n t o a  Steady  S t a t e Phase. Both ecosystems of the p r e s e n t study would f a l l •Likens'  (1979) A g g r a d a t i o n Phase, where net ecosystem  positive.  i n t o Bormann and production i s  In a d d i t i o n , the 450 y e a r - o l d D o u g l a s - f i r ecosystem  cussed i n Chapter  2 a l s o had  a p o s i t i v e net ecosystem  dis-  productivity  ( G r i e r and Logan 1977); i t too f a l l s w i t h i n the A g g r a d a t i o n Phase. Yet the water c h e m i s t r y p r o f i l e s of these ecosystems d i f f e r e d  sub-  stantially. From the study o f water c h e m i s t r y p r o f i l e s p r e s e n t e d here, i t appears  that s i m p l i f i e d  g e n e r a l i z a t i o n s of ecosystem  nutrient  retention  through s u c c e s s i o n a l  time are of l i m i t e d u s e f u l n e s s  w i t h the d i v e r s i t y of n u t r i e n t i n p u t , output and s u c c e s s i o n a l ecosystems. derived  when  confronted  c y c l i n g rates  A more u s e f u l c o n c e p t u a l i z a t i o n  of  could  from the c h a r a c t e r i z a t i o n of f a c t o r s which i n f l u e n c e  be  these  p r o p e r t i e s i n s p e c i f i c ecosystems, a f t e r Gorham et a l . (1979).  Fac-  t o r s such as s o i l development, n i t r o g e n  pro-  cesses can  change w i t h s u c c e s s i o n a l  r a t e s cannot serve  5-9  time, and  Feller  biomass a c c u m u l a t i o n  as surrogate.measures of these f a c t o r s .  water chemistry p r o f i l e method p r e s e n t e d by Kimmins  (1976) and  are examined.  p r e s s ) c a l c u l a t e d n u t r i e n t f l u x e s by concentrations hydrology.  combining water c h e m i s t r y  profile  T h i s approach assumes that the water sampled at each p r o of a l l the water p a s s i n g  through -that  However, numerous s t u d i e s have demonstrated t h a t water move-  ment through s o i l s can be  a combination of r a p i d s a t u r a t i o n  through s o i l micropores and (e.g. F e l l e r 1974, Haines and  Beasley 1976,  Harr 1977, and  a c l e a r c u t t i n g study i n North C a r o l i n a .  At  stage,  tensionless  than the  tension  lysimeters  lysimeters.  tensionless lysimeters. where the  flow  slower movement through the s o i l m a t r i x  Wade (1979) compared t e n s i o n  stage,  S o l l i n s et a l . ( i n  w i t h a computer s i m u l a t i o n model of t h e i r ecosystem's  stage i s r e p r e s e n t a t i v e  stage.  and  used here does not address the problems of water  q u a n t i t i e s ; only concentrations  the  hydrologic  C r i t i q u e of the Water Chemistry P r o f i l e Method The  file  f i x a t i o n and  Chow 1978).  tensionless lysimeters the f o r e s t f l o o r  in  leachate  c o l l e c t e d seven times more water  Concentrations The  De V r i e s and  were a l s o g r e a t e r  p a t t e r n reversed  tension lysimeters  from  at the m i n e r a l  soil  c o l l e c t e d twice the water volume  48  c o l l e c t e d by the t e n s i o n l e s s l y s i m e t e r s .  After clearcutting,  mineral s o i l  tensionless lysimeters indicated  creased s o i l  l e a c h a t e c o n c e n t r a t i o n s , w h i l e the m i n e r a l s o i l  lysimeters indicated  that s o i l  duced by the treatment!  that the treatment i n tension  l e a c h a t e c o n c e n t r a t i o n s had been r e -  These a u t h o r s concluded t h a t t h e i r study  have t o l d more about l y s i m e t r y soil  the  than about c l e a r c u t t i n g e f f e c t s  may  on  solution. F i g u r e 5 p r e s e n t s a s i m p l i f i e d diagram of water passage  through  an ecosystem; uptake and e v a p o t r a n s p i r a t i o n are not i n c l u d e d , but would account f o r removal of water from every compartment. at  The water  sampled  each p r o f i l e stage i s the p r o d u c t of s e v e r a l f a c t o r s , and these f a c -  t o r s v a r y i n importance through time. Water c h e m i s t r y p r o f i l e s can g i v e , however, some i n s i g h t s p r o c e s s e s w i t h ecosystems.  The m o b i l i t y of anions i n s o i l s can regu-  l a t e the l o s s e s of c a t i o n s . istry profile changes  Johnson and Cole (197 7)  used water  i n f o r m a t i o n to develop a model p r e d i c t i n g  i n a n i o n i n p u t r a t e s on s o i l s .  used water c h e m i s t r y p r o f i l e s  Cronan and S c h o f i e l d  i n the N o r t h e a s t .  precipita-  Finally,  water done  The observed d i f f e r e n c e s i n c o n c e n t r a t i o n were  u s e f u l i n i d e n t i f y i n g d i f f e r e n c e s between the ecosystems. ecosystem was  (1979)  can be used f o r comparative purposes, as was  i n the p r e s e n t study.  chem-  the e f f e c t s of  to a s s e s s the impact of a c i d  t i o n on h i g h e l e v a t i o n ecosystems •chemistry p r o f i l e s  into  The  younger  found to have h i g h e r n u t r i e n t c o n c e n t r a t i o n s i n s o i l  l e a c h a t e than the o l d e r ecosystem, w h i l e stream-water n u t r i e n t t r a t i o n s were more s i m i l a r .  concen-  49  lAlIXCi  OVERSTORY CANOPY  I  L>UNDERSTORY  CANOPY  •THROUGHFALL FOREST FLOOR CHANNEL FLOW  FOREST FLOOR MATRIX FLOW  V MINERAL SOIL CHANNEL FLOW  MINERAL SOIL MATRIX FLOW .MINERAL SOIL LEACHATE SAMPLE 'SATURATED ZONE-WATER  UPSLOPE SATURATED FLOW  STREAM-WATER  Figure  5.  S i m p l i f i e d model of water f l o w through ecosystems. Uptake and e v a p o t r a n s p i r a t i o n a r e not i n c l u d e d i n t h e diagram, but account f o r removal of water from every compartment l i s t e d . Exchanges between compartments f l u c t u a t e o v e r time.. Sampling stages are underlined.  CHAPTER 6  1.  CONCLUSIONS  The younger ecosystem's water c h e m i s t r y  at most s t a g e s .  p r o f i l e s were o f t e n r i c h e r  However, the younger ecosystem's stream-water concen-  t r a t i o n s approached those of the o l d e r ecosystem.  The c o n d u c t i v i t y  p r o f i l e b e s t e x e m p l i f i e d the o v e r a l l t r e n d ; the g r e a t e r i n t h r o u g h f a l l and not found  soil  concentrations  l e a c h a t e of the younger of the ecosystems were  i n stream-water.  T h i s p a t t e r n suggests  a greater cycling  a v a i l a b i l i t y of n u t r i e n t s p e c i e s w i t h i n the younger ecosystem e q u i v a l e n t i n c r e a s e s i n stream-water output 2.  ecosystem was 3.  due  Nitrogen  Higher  l e v e l s were much h i g h e r ,  i n d i r e c t e f f e c t s on e c o s y s t e m a t i c  4.  The  systems f o l l o w e d the g e n e r a l p a t t e r n Ca  > Mg  profiles > K .  s u b s t a n t i a l l y both between ecosystems and to  pre-  function rates.  dominant c a t i o n s i n the water chemistry  stage  the  n i t r o g e n a v a i l a b i l i t y would have many d i r e c t  and  The  more l u x u r i a n t n u t r i e n t  to the n i t r o g e n f i x a t i o n of the red a l d e r over  v i o u s 18 y e a r s .  differed  stream-  c o n c e n t r a t i o n , the younger  The water chemistry p r o f i l e s a l s o suggested  probably  5.  concentrations.  c o n s i s t e n t l y more e f f i c i e n t .  regimes i n the younger ecosystem.  file  without  D e f i n i n g n u t r i e n t r e t e n t i o n e f f i c i e n c y as the r a t i o of the  water c o n c e n t r a t i o n to the maximum p r o f i l e  and  i n both The  eco-  anions  from one water pro-  another.  c h l o r i d e p r o f i l e s were s i m i l a r f o r the  i n g h y d r o l o g i c s i m i l a r i t y f o r the two  c y c l i n g of c h l o r i d e i s  ecosystems,  ecosystems and  p e r i o d s i n which the p r o f i l e s were measured. s i b l e f o r the observed  two  The mechanisms  p a t t e r n s are undetermined, but suggested.  f o r the  an  suggest-  separate respon-  intrasystem  51 6.  The  release  s i l i c a water c h e m i s t r y p r o f i l e s i n d i c a t e d that  the  of s i l i c a  higher i n  from s i l i c a t e m i n e r a l s have been 40%  younger ecosystem. several factors: increased  differences i n mineralogic  composition of the  more a v a i l a b l e forms i s d i f f i c u l t p r o f i l e does suggest t h a t the  to measure.  input  two  However, the  ecosystems.  stream-water outputs from the younger ecosystem of Ca may  these c a t i o n d i f f e r e n c e s do not  ences i n c a t i o n d e p l e t i o n between the 7.  The  silica  The  (10%)  greater and  indicate significant d i f f e r -  f o r the  the d i f f e r e n t e x t r a c t a n t s  not p o s s i b l e .  two  used.  ecosystems'  magnesium. 8.  T h i s does not  Total nitrogen  p o r t i o n of  form.  true i n the p r e s e n t  and  study.  a n a l y s e s of water samples i n d i c a t e d that a major  the d i s s o l v e d n i t r o g e n  i n an o r g a n i c  per  soils  i n exchangeable c a l c i u m  appear to h o l d  soils  Without measures  F r a n k l i n et a l . (1968) found the  beneath red a l d e r stands were d e p l e t e d  Mg  input.  of b u l k d e n s i t i e s , however, a comparison of exchangeable bases h e c t a r e was  to  ecosystems.  measures of exchangeable c a t i o n s  are s i m i l a r , d e s p i t e  The  from weather-  have been l e s s than the d i f f e r e n c e s i n weathering  Therefore,  soils,  mineral l a t t i c e  of n u t r i e n t c a t i o n s  have d i f f e r e d f o r the  to  chelating a c t i v i t y .  t r a n s f e r of n u t r i e n t c a t i o n s from the u n a v a i l a b l e  (30%)  the  T h i s weathering d i f f e r e n c e c o u l d have been due  a c i d i t y , or d i f f e r e n c e s i n o r g a n i c  i n g p r o c e s s e s may  weathering  The  i n the water c h e m i s t r y p r o f i l e s  l a c k of o r g a n i c  nitrogen  determinations  was re-  s u l t e d i n v e r y incomplete p i c t u r e s of the o v e r a l l n i t r o g e n water chemistry  profiles.  9.  Comparisons of the measured c o n d u c t i v i t y w i t h t h a t c a l c u l a t e d from  the  c o n d u c t i v i t i e s of the  s u b s t a n t i a l p o r t i o n of the  i n d i v i d u a l l y measured i o n s r e v e a l e d ionic constituents  that  a  i n the s o i l s o l u t i o n of  the younger ecosystem were u n i d e n t i f i e d . were accounted f o r , o r g a n i c  As a l l major  inorganic  ions  ions would appear to be important compo-  nents of the t o t a l water c h e m i s t r y p r o f i l e . measured and c a l c u l a t e d c o n d u c t i v i t y was  The agreement  between  c l o s e r f o r the o l d e r  eco-  system, s u g g e s t i n g a l e s s important (though perhaps s i g n i f i c a n t ) r o l e of o r g a n i c 10.  ions.  The younger ecosystem c y c l e s i t s n u t r i e n t more r a p i d l y than the  o l d e r ecosystem. leachate  than i n s a t u r a t e d  the younger ents.  Higher n u t r i e n t c o n c e n t r a t i o n s  in forest floor  zone-water o r stream-water suggest t h a t  ecosystem-was more e f f i c i e n t l y r e t a i n i n g d i s s o l v e d  nutri-  Higher r a t e s of b i o l o g i c uptake p r o b a b l y account f o r the major-  i t y of t h i s r e g u l a t i o n . spraying  I f the v e g e t a t i o n  were d i s t u r b e d ,  as i n the  of a h e r b i c i d e , the r a p i d l y c y c l i n g n u t r i e n t s n o r m a l l y r e -  tained within  the ecosystem by p l a n t uptake would be a v a i l a b l e f o r  l e a c h i n g from the system. standpoints  Such a l o s s could be of concern from the  of b o t h f e r t i l i t y  and stream  eutrophication.  53  i  LITERATURE CITED B e a s l e y , R.S. 1976. C o n t r i b u t i o n of s u b s u r f a c e f l o w from the upper s l o p e s of f o r e s t e d watersheds to channel flow. S o i l S c i e n c e S o c i e t y of America J o u r n a l 40:955-957. 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USDA A g r i c u l t u r a l Handbook 436. 754 pp. S o l l i n s , P., C.C. G r i e r , F.M. M c C o r r i s o n , K. Cromack, R. F o g e l and R.L. Fredriksen. The i n t e r n a l element c y c l e s of an old-growth D o u g l a s - f i r f o r e s t i n western Oregon. E c o l o g i c a l Monographs ( i n p r e s s ) .  56 U l r i c h , B. and R. Mayer. 1971. Systems a n a l y s i s of m i n e r a l c y c l i n g i n f o r e s t ecosystems. Pages 329-339 ixi I s o t o p e s and r a d i a t i o n i n s o i l - p l a n t relationships including forestry. I n t e r n a t i o n Atomic Energy Agency, Vienna. V i t o u s e k , P.M. 1977. The r e g u l a t i o n of element c o n c e n t r a t i o n s i n mountain streams i n the N o r t h e a s t e r n U n i t e d S t a t e s . E c o l o g i c a l Monographs 47:65-87. V i t o u s e k , P.M. and W.A. Reiners. 1975. Ecosystem s u c c e s s i o n and n u t r i e n t retention: a hypothesis. B i o s c i e n c e 25:376-381. V i t o u s e k , P.M. and W.A. Reiners. 1976. Ecosystem development and the b i o l o g i c a l c o n t r o l of stream water c h e m i s t r y . Pages 665-680 jin J.O. N r i a g u , ed. Environmental b i o g e o c h e m i s t r y , Ann Arbor S c i e n c e , Ann Arbor. W h i t t a k e r , R.H. New York. 387  1976. pp.  Communities and  Ecosystems.  MacMillan P u b l i s h i n g ,  Windsor, G.J. 1969. Dynamics of phosphorus, s i l i c o n , i r o n and aluminum movement i n g r a v i t a t i o n a l r a i n w a t e r i n a D o u g l a s - f i r ecosystem. Ph.D. Thesis. U n i v e r s i t y of Washington, S e a t t l e . 188 pp. Z a v i t k o v s k i , J . and M. Newton. 1971. L i t t e r f a l l and l i t t e r a c c u m u l a t i o n i n red a l d e r stands i n western Oregon. Plant and S o i l 35:257-268.  57 APPENDIX  A-l  Soil  A-l-1  Descriptions  Soil Profile  Descriptions  T a b l e s A - l and A-2 p r e s e n t s o i l p r o f i l e d e s c r i p t i o n s f o r the younger and o l d e r ecosystems.  I s e l e c t e d p i t number one as b e i n g  t y p i c a l o f the younger ecosystem, and F e l l e r  (1977) chose h i s p i t  number 9.  A-l-2  S o i l Chemical A n a l y s e s C a t i o n exchange  c a p a c i t y and exchangeable c a t i o n s were determined  on s o i l samples from both ecosystems. extraction  ( L a v k u l i c h 1976); F e l l e r  C a t i o n exchange  capacity  c a t i o n exchange  c a p a c i t i e s was made.  I chose a n e u t r a l s a l t  (1974) used pH 7 ammonium  i s pH dependent,  F o r e s t F l o o r Biomass  T a b l e A-3 l i s t s  and N u t r i e n t  acetate.  and so no comparison of the the average r e -  s u l t s from 12 p i t s i n the younger ecosystem and 9 p i t s  A-l-3  (1 N NaCl)  i n the o l d e r .  Content  I made c o l l e c t i o n s of the younger ecosystem's f o r e s t f l o o r a t two times:  A p r i l and November 1978.  Two 25 x 25 cm samples of the L+F  were c o l l e c t e d a t each of the WCP sampling s t a t i o n s , g i v i n g a t o t a l of 28 samples p e r c o l l e c t i o n . 1.5 meters  The sampling l o c a t i o n was s y s t e m a t i c a l l y  (downslope) from the f o r e s t f l o o r l y s i m e t e r .  The quadrat  s i z e p r e v e n t e d sampling o f l a r g e d e b r i s such as l o g s o r stumps. woody m a t e r i a l w i t h i n the quadrat was Feller ecosystem.  Any  sampled.  (1974) d i d n o t measure f o r e s t f l o o r biomass  f o r the o l d e r  To o b t a i n a r e p r e s e n t a t i v e e s t i m a t e of the f o r e s t f l o o r  biomass f o r a s i m i l a r ecosystem, I sampled  the f o r e s t f l o o r of the  o l d e r ecosystem immediately upslope from the younger ecosystem.  In  58 Table A - l .  S o i l p r o f i l e d e s c r i p t i o n , younger ecosystem p i t #1.  Deptt\ cm  Horizon  Description  3-0  LF  Recent a l d e r and salmonberry l e a f and twig l i t t e r ; F l a y e r w e l l developed; c l e a r boundary; few r o o t s .  0-9  Ah  Dark brown (10 YR 3/3); s i l t y loam, 50% c f ; f i n e , weak g r a n u l a r s t r u c t u r e ; v e r y f r i a b l e ; c l e a r , smooth boundary; abundant f i n e r o o t s .  10-40  Bhf  O l i v e brown (2.5 YR 4/4); s i l t y loam, 50% c f f i n e , weak g r a n u l a r s t r u c t u r e ; v e r y f r i a b l e ; g r a d u a l , smooth boundary; p l e n t i f u l r o o t s .  40-100  BC  L i g h t o l i v e brown (2.5 YR 5/4); s i l t y loam, 50% cf; f i n e , weak g r a n u l a r s t r u c t u r e ; v e r y f r i a b l e ; abrupt, wavy boundary; few r o o t s .  100+  IIC  Compacted  basal  till.  59 Table A-2.  S o i l p r o f i l e d e s c r i p t i o n , o l d e r ecosystem p i t //9 (from F e l l e r 1977),  Depth, cm  Horizon  Description  LFH  Fresh w e s t e r n hemlock and D o u g l a s - f i r l i t t e r ; F l a y e r w e l l developed w i t h y e l l o w m y c e l i a ; f r i a b l e ; abrupt, wavy boundary, abundant f i n e roots.  0-5  Ae  Grey (5 YR 5/1); sandy loam, 62% c f ; medium, weak subangular, b l o c k y s t r u c t u r e ; f r i a b l e ; abrupt, broken boundary; few r o o t s .  5-50  Bfh  Reddish brown (5 YR 4/4); sandy loam, 71% c f ; moderate, f i n e , a n g u l a r , b l o c k y s t r u c t u r e ; f i r m ; c l e a r , i r r e g u l a r boundary; abundant roots.  50-100  Bf  Y e l l o w i s h brown (10 YR 5/4); loamy sand, 94% c f ; weak, f i n e , g r a n u l a r s t r u c t u r e ; v e r y abrupt, i r r e g u l a r boundary; few r o o t s .  100+  R  Q u a r t z d i o r i t e bedrock.  15-0  T a b l e A-3.  S o i l chemical i n f o r m a t i o n averages .  Extractable Horizon  pH(H 0) 9  Org. Mat.*  3  Ca^  -meq  % Forest f l o o r Younger Older  K  Mg^  NHi,  +  100"  +  CEC  1  4.36 4.21  56 84  18.8 17.2  2.8 3.0  1.8 1.1  0.4  51.1  4.34 4.49  16 20  5.5 5.6  0.4 0.9  0.9 0.4  0.1  28.4  Ah Younger Older Bf Younger Older  4.71 5.11  7 3  0.8 0. 3  0.1 < .1  0.3 0.1  < .1  12.2  BC-C Younger Older  4.64 5.27  6 3  0.7 0.4  < .1 < .1  0.3 0.1  < .1  10.6  a  A v e r a g e based on 12 s o i l p i t s  f o r the younger, 9 f o r the o l d e r ecosystems.  k% o r g a n i c matter c a l c u l a t e d as l o s s - o n - i g n i t i o n a t 450°C f o r 2 hours. C  l N NaCl e x t r a c t i o n used f o r younger ecosystem samples, pH 7 ammonium a c e t a t e e x t r a c t i o n used f o r o l d e r .  February, lected.  1979,  30 random samples o f . t h e L+F  A d i s c o n t i n u o u s humus h o r i z o n was  (25 x 25 cm) were  p r e s e n t i n t h i s o l d e r eco-  system; the boundary between the H and Ah was Only  the L+F  col-  i n d i s t i n c t and  h o r i z o n s are r e p o r t e d i n T a b l e  gradual.  A-4.  These f o r e s t f l o o r samples were oven d r i e d a t 70°C to a c o n s t a n t weight and ground to pass a 2 mm determined  extract.  by atomic  a b s o r p t i o n spectrophotometry  Turnover  removing the accumulated  l e a f and  Content  twig l i t t e r  the f o r e s t f l o o r c o l l e c t i o n s .  i n August  (to  cover September to November).  (to cover A p r i l  Two  to August) and The  from the m i n e r a l  one  content of the l i t t e r f a l l .  i n November,  sample number was  i n an underestimate  not designed  l a r g e woody l i t t e r f a l l . sented i n Table A-5  are  1978  28 f o r each  of the l i t t e r  between  of the t o t a l biomass  A l s o , l e a f f a l l was  90-95% complete at the time of the November c o l l e c t i o n . scheme was  soil  c o l l e c t i o n s were made,  L e a c h i n g and p a r t i a l decomposition  c o l l e c t i o n s would r e s u l t  sampling  on a m i c r o -  i n the younger ecosystem were made by  one  collection.  HC1  Rates  C o l l e c t i o n s of l i t t e r f a l l  nutrient  on a 28%  Autoanalyzer.  L i t t e r f a l l Biomass and N u t r i e n t  exposed by  was  Total cations  T o t a l n i t r o g e n and phosphorus were determined  K j e l d a h l d i g e s t u s i n g the  A-2-1  P e r c e n t o r g a n i c matter  as l o s s - o n - i g n i t i o n a t 475°C f o r two hours.  were determined  A-2  sieve.  and  only about Finally,  the  to p r o v i d e a p r e c i s e e s t i m a t e of  For these reasons,  the l i t t e r f a l l  data pre-  underestimates.  L i t t e r f a l l biomass d a t a f o r the o l d e r ecosystem up s l o p e of the younger were c o l l e c t e d by Kimmins  (unpublished d a t a ) .  The biomass  and  T a b l e A-4.  F o r e s t f l o o r biomass and n u t r i e n t c o n t e n t , kg ha Biomass  N  P  K  Ca  Mg  C/N  338  27  20  195  48  34  40.  34  Younger Ecosystem April  1978, L+F  November 1978, L+F  20,760 ( 2 , 1 8 0 )  h  19,900  (2,340)  340  29  19  144  18,610  (1,475)  140  21  9  57  30  77  16,290 34,900  (2,325)  190 330  20 41  9 18  106 163  18 48  50  Older Ecosystem February 1979, L+F H Total  No humus l a y e r present i n the younger ecosystem. 'Standard e r r o r of the mean.  T a b l e A-5.  L i t t e r f a l l biomass and n u t r i e n t  Biomass Younger Ecosystem (2 c o l l e c t i o n t o t a l )  7,740 ( 6 4 0 )  Older Ecosystem  3,530  'Assuming, 58% carbon i n biomass'standard e r r o r of the mean-  b  content, kg h a ' y r '.  N  P  K  Ca  Mg  C/N  168  12  18  102  21  27  29  2  6  30  2  71  64 n u t r i e n t v a l u e s i n Table A-5 two y e a r s of  f o r the o l d e r ecosystem  are the average  collections.  The v a l u e s i n T a b l e A-5  are the b e s t e s t i m a t e s p o s s i b l e f o r  f a l l biomass and n u t r i e n t content w i t h i n the c o n s t r a i n t s of t h i s They should not be c o n s i d e r e d more r e l i a b l e  litterstudy.  than the above q u a l i f i c a -  tions allow.  A n a l y s e s were done u s i n g the same methods as f o r the  forest floor  samples.  A-2-2  F o r e s t F l o o r Decomposition  Rate  No d i r e c t measurements of decomposition were made f o r e i t h e r system.  However, some rough e s t i m a t e s may  f l o o r a c c u m u l a t i o n and  litterfall  aboveground l i t t e r f a l l was no s i g n i f i c a n t  be made based  almost e i g h t  forest  tons per h e c t a r e of  measured i n the younger ecosystem;  change i n f o r e s t f l o o r biomass was the f o r e s t  measured.  this limited  sampling,  steady-state  ( n e i t h e r accumulating nor l o s i n g biomass).  dence of approximate  on  f l o o r biomass appeared  and y e t Based on  to be i n Further e v i -  steady s t a t e f o r e s t f l o o r biomass i s t h a t  aboveground l i t t e r f a l l  i n the 18 y e a r - o l d ecosystem was  biomass of the f o r e s t f l o o r .  annual  40% of the  I f s u b s t a n t i a l accumulation  of the  f l o o r were o c c u r r i n g , annual aboveground l i t t e r f a l l would not be pected to be such a l a r g e p r o p o r t i o n of the f o r e s t f l o o r .  biomass i n a time s e r i e s of red a l d e r stands.  - 1  (1.5 to 2.5  the same p a t t e r n .  They found s t e a d y - s t a t e  My  19  r e s u l t s appear to f i t  For these reasons, the b e s t e s t i m a t e of  f o r e s t f l o o r decomposition  ex-  floor  i n year s i x , w i t h a biomass of  years of l i t t e r f a l l ) .  forest  Zavitkovski  and Newton (1971) measured aboveground l i t t e r f a l l and f o r e s t  f o r e s t f l o o r dynamics were reached  eco-  estimates.  From A p r i l to November of 1978  tons h a  of  i s the same as the annual  annual  aboveground  65 litterfall  rate.  However, t h i s e s t i m a t e does not take i n t o  account  the t u r n o v e r of l a r g e woody d e b r i s . Aboveground l i t t e r f a l l ecosystem Annual of  was  e s t i m a t e d a t 4.1  aboveground l i t t e r f a l l  t h i s 100+  ecosystem  and  27.3  tons h a  ,  - 1  i n the o l d e r  respectively.  i s 15% of the accumulated  forest  floor  Some accumulation or decrease i n the  have been o c c u r r i n g .  However, g i v e n the age of the  the magnitude of the aboveground l i t t e r f a l l  the accumulated  in relation  f o r e s t f l o o r , annual f o r e s t f l o o r i n p u t s and  were p r o b a b l y s i m i l a r . assumed to be  and  y e a r - o l d ecosystem.  f o r e s t f l o o r may  to  and f o r e s t f l o o r accumulation  T h e r e f o r e , the l i t t e r f a l l  measurement  outputs  was  the b e s t e s t i m a t e of the f o r e s t f l o o r decomposition  rate.  A g a i n , t h i s e s t i m a t e d i d not i n c l u d e the turnover of l a r g e woody material.  A-3  Standing Biomass Accumulation  A-3-1  S t a n d i n g Biomass  and P r o d u c t i o n  Accumulation  To c h a r a c t e r i z e the v e g e t a t i o n of the younger ecosystem, s e c t s were run p a r a l l e l to the s l o p e .  A t o t a l of 45 p r i s m p l o t s were  measured; the t r e e s w i t h i n the prism's f i e l d were t a l l i e d diameter at  and h e i g h t .  each p l o t was  4 tran-  by s p e c i e s ,  In a d d i t i o n , the u n d e r s t o r y v e g e t a t i o n biomass  s u b j e c t i v e l y e s t i m a t e d on the a r b i t r a r y s c a l e of  1-15.  To c o r r e l a t e the s u b j e c t i v e u n d e r s t o r y e s t i m a t e s w i t h a c t u a l biomass, 1 m  2  p l o t s were c l i p p e d at 3 p o i n t s .  The  range of the c l i p p l o t s  from 2-15  on the s u b j e c t i v e s c a l e . . R e g r e s s i o n e q u a t i o n s  diameter)  from Gholz et a l . (1979) were used  of  to o b t a i n rough  the s t a n d i n g v e g e t a t i o n biomass by s p e c i e s .  developed  (based  was  on  estimates  These r e g r e s s i o n s were  from measurements taken i n Oregon and Washington; they were  66 Table A-6.  S p e c i e s d i s t r i b u t i o n and biomass  Stems*ha  Species  1  Foliage  Younger Ecosystem-— B a s a l Area = 34.7 m  2  ha  1  Wood+Bark  Total  - 1  Douglas-fir Hemlock Cedar Subtotal  1,160 250 11 1,421  4,610 555 185 5,350  55,433 3,480 1,583 60,496  60,043 4,035 1,768 65,846  Alder Vine maple B i t t e r cherry B i g l e a f maple Subtotal  769 2,400 836 142 4,147  1,565 479 895 105 3,044  17,725 14,040 10,872 1,901 44,538  19,290 14,519 11,767 2,006 47,582  Understory TOTAL  "57568  2.000 10,394  5.000 110,034  7.000 120,428  231,398 112,355 58.915 402,668  244,524 115,252 64.519 424,295  Older  0  Ecosystem--B a s a l Area = 68.8 m  Hemlock Douglas-fir Cedar TOTAL  3  (kg h a " ) .  Based  411 68 157 636  2  ha  1  13,126 2,897 5.604 21,627  on r e g r e s s i o n e q u a t i o n s from Gholz e t a l.. (1979).  ^ B i t t e r c h e r r y es timates based on e q u a t i o n s f o r p i n p e n n s y l v a n i c a ) from Ribe (1973).  c h e r r y (Prunus  U n d e r s t o r y biomass e s t i m a t e s assume a l l u n d e r s t o r y biomass i s 2.5 cm base diameter salmonberry f o r the purposes of foliage:woody d i v i s i o n ^Understory biomass was not e s t i m a t e d f o r o l d e r  ecosystem.  not e v a l u a t e d f o r accuracy study.  of p r e d i c t i o n i n the younger ecosystem  T h e r e f o r e , the e s t i m a t e s i n Table A-6 should be taken o n l y as  b e s t e s t i m a t e s and n o t p r e c i s e v a l u e s . The v a l u e s l i s t e d  f o r the biomass of the major o v e r s t o r y s p e c i e s  i n the o l d e r ecosystem were c a l c u l a t e d by a p p l y i n g equations Gholz e t a l . (1979) t o c r u i s e d a t a s u p p l i e d by F e l l e r  A-3-2  Biomass P r o d u c t i v i t y  from  (1974).  Estimates  Rough e s t i m a t e s o f aboveground n e t ecosystem p r o d u c t i o n can be o b t a i n e d by d i v i d i n g biomass accumulation by age.  Aboveground n e t  primary p r o d u c t i v i t y can be e s t i m a t e d by summing the n e t biomass i n crement and the annual aboveground l i t t e r f a l l .  T a b l e A-7 p r e s e n t s my  e s t i m a t e s of these v a l u e s f o r both ecosystems.  The f i n a l  are based  on c a l c u l a t i o n s on rough e s t i m a t e s , t h e r e f o r e they a r e v e r y  approximate f i g u r e s . half third  estimates  The younger ecosystem appears  t o be about one-  to t w o - t h i r d s more p r o d u c t i v e and t o be accumulating more biomass.  about one-  Table A-7.  Aboveground n e t primary p r o d u c t i v i t y  Component T o t a l Biomass: Wood+Bark Foliage Forest Floor Total  (kg  estimates.  Younger  Older  110,000 4,200 20,000 135,200  403,000 18,000 35,000 456,000  7,500 7,800  5,700 3., 500  ha" ) 1  3  Annual Aboveground Net (kg ha • y r ) Ecosystem P r o d u c t i o n d Annual Aboveground L i t t e r f a l l ' 1  0  E s t i m a t e d Annual Aboveground Net Primary P r o d u c t i v i t y : (kg h a  - 1  yr)  15.300  9JM  These v a l u e s r e p r e s e n t o n l y 4/5 o f the c o n i f e r o u s f o l i a g e and none of the deciduous. I t i s assumed t h a t the d i f f e r e n c e s be- , tween these l i s t e d v a l u e s and those i n Table A-6 a r e i n c l u d e d i n the annual l i t t e r f a l l f i g u r e . Obtained by d i v i d i n g the t o t a l s above by 18 y e a r s f o r the younger ecosystem and by 80 f o r the o l d e r . T h i s e s t i m a t e r e p r e s e n t s the lower l i m i t of the t r u e aboveground NPP; biomass consumed by h e r b i v o r e s i s not c o n s i d e r e d . Not a f u l l y e a r ' s l i t t e r f a l l  f o r the younger ecosystem.  F i g u r e A-L  R e g i o n a l map  of the study  areas.  F i g u r e A-2.  U.B.C. Research F o r e s t , study area l o c a t i o n s . o  

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