Open Collections

UBC Theses and Dissertations

UBC Theses Logo

UBC Theses and Dissertations

Ecological physiology of conifer seedling and sapling suppression by, and release from, competing vegetation Bigley, Richard Ernest 1988

Your browser doesn't seem to have a PDF viewer, please download the PDF to view this item.

Item Metadata

Download

Media
831-UBC_1988_A1 B53.pdf [ 8.73MB ]
Metadata
JSON: 831-1.0097952.json
JSON-LD: 831-1.0097952-ld.json
RDF/XML (Pretty): 831-1.0097952-rdf.xml
RDF/JSON: 831-1.0097952-rdf.json
Turtle: 831-1.0097952-turtle.txt
N-Triples: 831-1.0097952-rdf-ntriples.txt
Original Record: 831-1.0097952-source.json
Full Text
831-1.0097952-fulltext.txt
Citation
831-1.0097952.ris

Full Text

ECOLOGICAL PHYSIOLOGY  OF CONIFER SEEDLING AND  SAPLING  SUPPRESSION BY, AND RELEASE FROM, COMPETING VEGETATION By RICHARD ERNEST BIGLEY B.Sc, M.Sc,  Washington S t a t e U n i v e r s i t y , University  A THESIS SUBMITTED  1979  o f B r i t i s h Columbia,  1981  I N PARTIAL FULFILLMENT OF  THE REQUIREMENTS FOR THE DEGREE OF DOCTOR OF  PHILOSOPHY in  THE FACULTY OF GRADUATE STUDIES (Faculty  of Forestry,  Department o f F o r e s t Science)  We a c c e p t t h i s t h e s i s a s c o n f o r m i n g to the standard  UNIVERSITY OF B R I T I S H October  COLUMBIA  1988  Richard Ernest Bigley,  1988  In  presenting  degree freely  at  this  the  thesis  in  partial  fulfilment  University  of  British  Columbia, 1 agree that the  available for  copying  of  department publication  this or of  reference  thesis by  this  for  his  and study. scholarly  or  thesis  her  for  Department  of  The University of British Columbia Vancouver, Canada  Date  DE-6  (2/88)  Qc\7o&€£.  </  ;  /98fi  I further  purposes  gain  the  requirements  agree that  may  representatives.  financial  permission.  of  It  shall not  be is  an  advanced  Library shall make  permission for  granted  by  understood be  for  allowed  the that  without  it  extensive  head  of  my  copying  or  my  written  ABSTRACT  The  o v e r a l l o b j e c t i v e o f t h i s t h e s i s was t o i m p r o v e o u r  understanding of the l i g h t  environment  a s s o c i a t e d w i t h two  of t h e major deciduous c o m p e t i t o r s o f commercial  conifer  s e e d l i n g s i n low e l e v a t i o n c o a s t a l B r i t i s h Columbia, physiological  response o f young c o n i f e r s t o s p e c i f i c  e n v i r o n m e n t s and changes  i n t h e environment.  conducted t o i n v e s t i g a t e : changes  and t h e  i n the light  S t u d i e s were  1) s e a s o n a l a n d h e r b i c i d e - i n d u c e d  regimes b e n e a t h t h e c a n o p i e s o f two  b r u s h s p e c i e s , 2) g r o w t h a n d p h y s i o l o g y o f s e e d l i n g s o f three c o n i f e r species i n s e v e r a l d i f f e r e n t deciduous brush e n v i r o n m e n t s t h r o u g h o u t t h e y e a r , a n d 3) c h a n g e s  i n the  p h y s i o l o g y a n d g r o w t h o f s u p p r e s s e d c o n i f e r s a p l i n g s when d i f f e r e n t methods a n d s c h e d u l e s w e r e u s e d t o r e d u c e s h a d i n g f r o m an o v e r t o p p i n g r e d a l d e r S e a s o n a l changes  canopy.  i n t h e l i g h t q u a n t i t y and q u a l i t y  were documented w i t h i n s a l m o n b e r r y Pursch) and below r e d a l d e r The p r e d i c t i o n o f l i g h t  (Rubus  spectabilis  ( A l n u s r u b r a Bong.) c a n o p i e s .  attenuation within  canopies u s i n g t h e Beer-Lambert  salmonberry  l a w was g o o d f o r f o l i a t e d  c a n o p i e s u s i n g l e a f a r e a i n d e x , and d e f o l i a t e d u s i n g stem a r e a i n d e x . the r a t i o  As s a l m o n b e r r y l e a f a r e a  of red to far-red l i g h t declined  Growth  o f grand f i r  w e s t e r n hemlock Douglas-fir  canopies increased,  exponentially.  ( A b i e s q r a n d i s (Dougl.) F o r b e s ) ,  (Tsuga h e t e r o p h y l l a  (Pseudetsuga m e n z i e s i i  (Raf.) Sarg.) and (Mirbel)  Franco)  iii seedlings  decreased with  overtopping  increases  deciduous species.  between c o n i f e r s p e c i e s  i n t h e canopy d e n s i t y o f  Physiological differences  and d i f f e r e n c e s between  overtopping  c a n o p y t r e a t m e n t s d e c l i n e d i n t h e autumn a n d w i n t e r . on t h e p h y s i o l o g i c a l m e a s u r e m e n t s , s u p p r e s s i o n intolerant Douglas-fir the p e r i o d t h a t leafless. increases  seedlings  overtopping  Based  o f t h e shade  was g r e a t l y r e d u c e d  during  d e c i d u o u s c a n o p i e s were  A n i m a l damage r e d u c e s g r o w t h a n d p r o b a b l y the duration  seedlings  a r e under  overtopping  canopies. Suppressed D o u g l a s - f i r overtopping  saplings  released  from  b y r e d a l d e r c a n o p i e s showed t h e g r e a t e s t  growth  r e s p o n s e when t h e a l d e r c a n o p i e s w e r e r e m o v e d i n t h e s p r i n g ; complete removal o f t h e a l d e r canopy d u r i n g  t h e summer h a d a  p r e d i c t a b l y d e l e t e r i o u s e f f e c t on t h e s a p l i n g p h y s i o l o g y growth.  Herbicide  i n j e c t i o n s r e s u l t e d i n a slower but  predictable increase  i n c o n i f e r growth.  and  iv TABLE OF CONTENTS Page ABSTRACT  i  L I S T OF TABLES  i  v i i  L I S T OF FIGURES  x i  L I S T OF APPENDICES  xiii  ACKNOWLEDGEMENTS  xiv  CHAPTER  1.  INTRODUCTION  1  A. RESEARCH OBJECTIVES  5  B. STUDY DESIGN  7  C. DESCRIPTION OF STUDY S I T E S CHAPTER  2.  10  D. DESCRIPTION OF STUDY S P E C I E S .... SEASONAL AND HERBICIDE-INDUCED CHANGES IN THE LIGHT ENVIRONMENT WITHIN THE CANOPIES OF TWO DECIDUOUS S P E C I E S  16 19  INTRODUCTION  19  METHODS  23  A. Sample p l o t s  23  B. F i e l d t r e a t m e n t s  23  B. F i e l d m e a s u r e m e n t s  23  RESULTS  28  A. D i s t r i b u t i o n o f l e a f a n d s t e m biomass, area index, and l i g h t attenuation w i t h i n salmonberry canopies  28  B. B e e r - L a m b e r t coefficients  32  extinction  C. A n n u a l c h a n g e s i n l i g h t q u a n t i t y and q u a l i t y w i t h i n s a l m o n b e r r y canopies  36  D. A n n u a l a n d h e r b i c i d e - i n d u c e d changes i n l i g h t q u a n t i t y and q u a l i t y under r e d a l d e r canopies DISCUSSION  CHAPTER 3.  45  A. D i f f e r e n c e s i n c a n o p y s t r u c t u r e and l i g h t a t t e n u a t i o n w i t h i n salmonberry t h i c k e t s of d i f f e r e n t ages  45  B. S e a s o n a l c h a n g e s i n l i g h t q u a n t i t y and q u a l i t y  50  C. H e r b i c i d e - i n d u c e d c h a n g e s i n l i g h t q u a n t i t y and q u a l i t y  57  CONCLUSIONS  59  PHYSIOLOGY AND GROWTH OF SEEDLINGS OF THREE CONIFER SPECIES UNDER DIFFERENT DENSITIES OF DECIDUOUS COMPETITORS  61  INTRODUCTION  61  METHODS  65  A. F i e l d  treatments  65  B. F i e l d  measurements  67  RESULTS  72  A. S e e d l i n g p h y s i o l o g y  72  B. S e e d l i n g  80  survival  C. S e e d l i n g g r o w t h  82  DISCUSSION  CHAPTER 4.  40  87  A. S e e d l i n g p h y s i o l o g y  87  B. S e e d l i n g  89  survival  a n d g r o w t h ....  CONCLUSIONS  94  THE EFFECT OF TREATMENT AND TREATMENT TIMING ON THE RELEASE RESPONSE OF SUPPRESSED DOUGLAS-FIR SAPLINGS  95  INTRODUCTION  95  vi  METHODS  101  A. F i e l d t r e a t m e n t s  101  B. F i e l d m e a s u r e m e n t s  102  RESULTS  105  A. S a p l i n g p h y s i o l o g y  105  B. S a p l i n g m o r p h o l o g y  129  DISCUSSION  136  A. E f f e c t o f t r e a t m e n t a n d t i m i n g on r e l e a s e r e s p o n s e B. S e l e c t i o n o f r e l e a s e and t i m i n g  136  treatment '. .  144  C. The e c o l o g i c a l i m p l i c a t i o n s o f release treatments  CHAPTER 5.  147  CONCLUSIONS  14 9  A P P L I C A T I O N OF FINDINGS AND CONCLUSIONS  150  LITERATURE CITED  155  APPENDICES  169  vii  L I S T OF TABLES T a b l e 1. Mean m o n t h l y t e m p e r a t u r e a n d m o n t h l y p r e c i p i t a t i o n a t t h e A d m i n i s t r a t i o n B u i l d i n g s i n 1983 a n d 1984, a n d t h e 20 y e a r a v e r a g e s f o r t h e UBC R e s e a r c h F o r e s t ..12 T a b l e 2. Mean r e l a t i v e l i g h t (PPFD) i n t e n s i t y a t 50 cm, c u m u l a t i v e l e a f a r e a i n d e x (LAI) and stem a r e a i n d e x (SAI) a b o v e 50 cm, a n d B e e r - L a m b e r t extinction c o e f f i c i e n t (K) t o 50 cm f o r d i f f e r e n t a g e s o f s a l m o n b e r r y t h i c k e t s b a s e d on L A I o n l y ( K ) a n d c o m b i n e d L A I a n d SAI ( K ) i n t h e summer a n d SAI ( K ) o n l y i n t h e w i n t e r (see F i g u r e s 2a t h r o u g h 2e f o r s p e c i f i c s t a n d data) 33 F  F + A  A  T a b l e 3. Horizon specific, v e r t i c a l d i s t r i b u t i o n of B e e r - L a m b e r t e x t i n c t i o n c o e f f i c i e n t s ( b a s e d on l e a f a r e a index) and s p e c i f i c l e a f a r e a s w i t h i n s a l m o n b e r r y c a n o p i e s o f d i f f e r e n t a g e s ( s e e F i g u r e s 2a t h r o u g h 2e f o r s p e c i f i c s t a n d data) 35 T a b l e 4. V e r t i c a l measurements o f Z e t a ( r a t i o o f energy a t 660:730 nm) w i t h i n s a l m o n b e r r y c a n o p i e s o f d i f f e r e n t a g e s ( s e e F i g u r e s 2a t h r o u g h 2e f o r s p e c i f i c s t a n d data) 39 T a b l e 5. P l a n t i n g s t o c k e s t a b l i s h e d w i t h i n salmonberry and red a l d e r stands 66 T a b l e 6. S p r i n g a n d summer means o f p h o t o s y n t h e t i c r a t e , P s (mgC02*dm * h r ) , l e a f c o n d u c t a n c e , g-^ (em's ) , v a p o r p r e s s u r e d e f i c i t , D (KPa), p h o t o s y n t h e t i c a l l y a c t i v e r a d i a t i o n d u r i n g Ps m e a s u r e m e n t s , PPFD ( u M o l ' m ' s ) , l e a f w a t e r p o t e n t i a l , wp (MPa), a n d c h l o r o p h y l l c o n t e n t , C h i (mg'g ), o f D o u g l a s - f i r (DF), grand f i r ( G F ) , a n d w e s t e r n h e m l o c k (WH) s e e d l i n g s w i t h i n salmonberry stands o f d i f f e r e n t d e n s i t y 73 2  1  - 2  - 1  T a b l e 7. Autumn a n d w i n t e r means o f p h o t o s y n t h e t i c r a t e , P s (mgC0 ' d m ' h r ) , l e a f c o n d u c t a n c e , g-^ (em's" ) , v a p o r p r e s s u r e d e f i c i t , D (KPa), p h o t o s y n t h e t i c a l l y a c t i v e r a d i a t i o n d u r i n g Ps m e a s u r e m e n t s , PPFD (uMol'm *s ) , l e a f w a t e r p o t e n t i a l , wp (MPa), a n d c h l o r o p h y l l c o n t e n t , C h i (mg'g - -), o f D o u g l a s - f i r (DF) , g r a n d f i r ( G F ) , a n d w e s t e r n h e m l o c k (WH) s e e d l i n g s w i t h i n salmonberry stands o f d i f f e r e n t d e n s i t y 74 - 2  - 1  2  -  1  viii T a b l e 8. S p r i n g a n d summer means o f p h o t o s y n t h e t i c r a t e , P s (mgC02*dm ^ ' h r ) , l e a f c o n d u c t a n c e , g-j_ (em's ) , vapor p r e s s u r e d e f i c i t , D (KPa), p h o t o s y n t h e t i c a l l y a c t i v e r a d i a t i o n d u r i n g Ps m e a s u r e m e n t s , PPFD (uMol*m~^*s ) , l e a f w a t e r p o t e n t i a l , wp (MPa), a n d c h l o r o p h y l l c o n t e n t , C h i ( m g ' g ) , o f D o u g l a s - f i r (DF), g r a n d f i r ( G F ) , a n d w e s t e r n h e m l o c k (WH) s e e d l i n g s w i t h i n r e d a l d e r stands o f d i f f e r e n t d e n s i t y 75 - 1  T a b l e 9. Autumn a n d w i n t e r means o f p h o t o s y n t h e t i c r a t e , P s (mgCC>2 "dm ^ * h r ) , l e a f c o n d u c t a n c e , gj_ (em's" ) , v a p o r p r e s s u r e d e f i c i t , D (KPa), p h o t o s y n t h e t i c a l l y a c t i v e r a d i a t i o n d u r i n g P s m e a s u r e m e n t s , PPFD (uMol'm s ), l e a f w a t e r p o t e n t i a l , wp (MPa), a n d c h l o r o p h y l l c o n t e n t , C h i (mg'g ) , o f D o u g l a s - f i r ( D F ) , g r a n d f i r (GF), a n d w e s t e r n h e m l o c k (WH) s e e d l i n g s w i t h i n r e d alder stands of d i f f e r e n t density 76 -  - 1  -  T a b l e 10. S u r v i v a l o f p l a n t e d s e e d l i n g s t h e f i r s t two y e a r s under d e c i d u o u s shade. P e r c e n t o f 40 s e e d l i n g s p e r species per treatment 81 T a b l e 1 1 . Mean v a l u e s o f s p e c i f i c l e a f a r e a (SLA) o f 1984 f o l i a g e , r e l a t i v e l e a f g r o w t h r a t e (RLGR), r e l a t i v e d i a m e t e r g r o w t h r a t e (RDGR), a n d r e l a t i v e h e i g h t g r o w t h r a t e (RHGR) f o r D o u g l a s - f i r ( D F ) , g r a n d f i r ( G F ) , a n d w e s t e r n h e m l o c k (WH) s e e d l i n g s a f t e r t h r e e years o f growth w i t h i n salmonberry stands o f different densities 83 T a b l e 12. Mean v a l u e s o f s p e c i f i c l e a f a r e a (SLA) o f 1984 f o l i a g e , r e l a t i v e l e a f g r o w t h r a t e (RLGR), r e l a t i v e d i a m e t e r g r o w t h r a t e (RDGR), a n d r e l a t i v e h e i g h t g r o w t h r a t e (RHGR) f o r D o u g l a s - f i r ( D F ) , g r a n d f i r ( G F ) , a n d w e s t e r n h e m l o c k (WH) s e e d l i n g s a f t e r t h r e e y e a r s o f growth w i t h i n r e d alder stands o f d i f f e r e n t densities 84 T a b l e 1 3 . Mean v a l u e s o f p h o t o s y n t h e s i s , l e a f d i f f u s i v e c o n d u c t a n c e ( g ^ ) , l e a f w a t e r p o t e n t i a l (wp), a n d c h l o r o p h y l l content (chl) f o r c u r r e n t year D o u g l a s - f i r f o l i a g e f r o m s a p l i n g s r e l e a s e d a t Haney on May 24, 1983 followed through time 106 T a b l e 14. Mean v a l u e s o f p h o t o s y n t h e s i s , l e a f d i f f u s i v e c o n d u c t a n c e ( g ^ ) , l e a f w a t e r p o t e n t i a l (wp), a n d c h l o r o p h y l l content (chl) f o r c u r r e n t year D o u g l a s - f i r f o l i a g e f r o m s a p l i n g s r e l e a s e d a t Haney on A u g u s t 9 , 1983 f o l l o w e d t h r o u g h t i m e 109  ix T a b l e 1 5 . Mean v a l u e s o f p h o t o s y n t h e s i s , leaf diffusive c o n d u c t a n c e (g-^), l e a f w a t e r p o t e n t i a l (wp) , a n d c h l o r o p h y l l content (chl) f o r current year Douglas-fir f o l i a g e f r o m s a p l i n g s r e l e a s e d a t Haney on J u n e 9, 1984 followed through time 113 T a b l e 16. Mean v a l u e s o f p h o t o s y n t h e s i s , leaf diffusive c o n d u c t a n c e (g-^) , l e a f w a t e r p o t e n t i a l (wp) , a n d c h l o r o p h y l l content (chl) f o r current year Douglas-fir f o l i a g e f r o m s a p l i n g s r e l e a s e d a t Haney on A u g u s t 7, 1984 f o l l o w e d t h r o u g h t i m e 115 T a b l e 17. Mean d i u r n a l v a l u e s o f p h o t o s y n t h e s i s , leaf d i f f u s i v e c o n d u c t a n c e ( g ^ ) , a n d means o f l e a f w a t e r p o t e n t i a l (wp), a n d c h l o r o p h y l l c o n t e n t ( c h l ) o f D o u g l a s - f i r s a p l i n g s r e l e a s e d a t Haney i n 1983 a s m e a s u r e d S e p t e m b e r 24, 1983 119 T a b l e 18. Mean v a l u e s o f p h o t o s y n t h e s i s , leaf diffusive c o n d u c t a n c e ( g ^ ) , a n d means o f l e a f w a t e r p o t e n t i a l (wp), a n d c h l o r o p h y l l c o n t e n t ( c h l ) o f D o u g l a s - f i r s a p l i n g s r e l e a s e d i n a t Haney 1984 a s m e a s u r e d O c t o b e r 3, 1984 122 T a b l e 19. Mean d i u r n a l v a l u e s o f p h o t o s y n t h e s i s , leaf d i f f u s i v e c o n d u c t a n c e ( g ^ ) , a n d means o f l e a f w a t e r p o t e n t i a l (wp) , a n d c h l o r o p h y l l c o n t e n t ( c h l ) o f 1983 and 1984 f o l i a g e f r o m D o u g l a s - f i r s a p l i n g s r e l e a s e d a t Haney i n 1983 a s m e a s u r e d S e p t e m b e r 7, 1984 125 T a b l e 2 0 . Mean d i u r n a l v a l u e s o f p h o t o s y n t h e s i s , leaf d i f f u s i v e c o n d u c t a n c e (g-^) , a n d means o f l e a f w a t e r p o t e n t i a l (wp), a n d c h l o r o p h y l l c o n t e n t ( c h l ) o f 1983 and 1984 f o l i a g e f r o m D o u g l a s - f i r s a p l i n g s m a n u a l l y r e l e a s e d i n 1983 a t P o w e l l R i v e r a s m e a s u r e d on J u n e 20, 1984 128 T a b l e 2 1 . Mean v a l u e s o f c u r r e n t y e a r s p e c i f i c l e a f a r e a ( S L A ) , f o r D o u g l a s - f i r s a p l i n g s r e l e a s e d a t Haney i n 1983 a n d 1984 m e a s u r e d a t t h e e n d o f t h e g r o w i n g s e a s o n of release 132 T a b l e 2 2 . Mean v a l u e s o f s p e c i f i c l e a f a r e a ( S L A ) , r e l a t i v e l e a f g r o w t h r a t e (RLGR), r e l a t i v e d i a m e t e r g r o w t h r a t e (RDGR), r e l a t i v e h e i g h t g r o w t h r a t e (RHGR), a n d s h o o t t o r o o t r a t i o (S/R) f o r D o u g l a s - f i r s a p l i n g s r e l e a s e d a t Haney i n 1983 a n d m e a s u r e d a t t h e e n d o f t h e 1984 growing season 133  X  T a b l e 2 3 . Mean v a l u e s o f s p e c i f i c l e a f a r e a (SLA) o f 1984 f o l i a g e , r e l a t i v e l e a f g r o w t h r a t e (RLGR), r e l a t i v e d i a m e t e r g r o w t h r a t e (RDGR), a n d r e l a t i v e h e i g h t g r o w t h r a t e (RHGR) f o r D o u g l a s - f i r s a p l i n g s r e l e a s e d m a n u a l l y a t P o w e l l R i v e r i n 1983 a n d m e a s u r e d a t t h e e n d o f t h e 1984 g r o w i n g s e a s o n 135  xi  L I S T OF  FIGURES  F i g u r e 1. L o c a t i o n o f s t u d y s i t e s on t h e U n i v e r s i t y B r i t i s h Columbia Research f o r e s t  of 11  F i g u r e 2a-e. V e r t i c a l d i s t r i b u t i o n o f l e a f and s t e m b i o m a s s , l e a f and s t e m a r e a i n d e x , and r e l a t i v e l i g h t (PPFD) i n t e n s i t y w i t h i n s a l m o n b e r r y t h i c k e t s i n t h e summer a n d t h e w i n t e r , (a) 1 - y e a r - o l d t h i c k e t ; (b) 2y e a r - o l d t h i c k e t ; (c) 3 - y e a r - o l d t h i c k e t ; (d) 5 - y e a r o l d t h i c k e t ; (e) 8 - y e a r - o l d t h i c k e t 29-31 F i g u r e 3. Mean m o n t h l y l i g h t (PPFD) i n t e n s i t y ( a t 50 cm) under a 5 - y e a r - o l d l i v e salmonberry t h i c k e t (LAI=10.7), and i n a c l e a r i n g . Mean m o n t h l y v a l u e s w i t h d i f f e r e n t l e t t e r s a r e s i g n i f i c a n t l y d i f f e r e n t (p<0.05) 37 F i g u r e 4. S o l a r r a d i a t i o n q u a l i t y ( a t 50 cm) u n d e r 5 - y e a r - o l d s a l m o n b e r r y t h i c k e t (LAI=10.7)  a 38  F i g u r e 5. Mean m o n t h l y l i g h t (PPFD) i n t e n s i t y ( a t 50 cm) under l i v e , h e r b i c i d e - d e f o l i a t e d r e d a l d e r s t a n d s (7 y e a r o l d , 8 m t a l l ) and i n a c l e a r i n g . Mean m o n t h l y values with d i f f e r e n t l e t t e r s are s i g n i f i c a n t l y d i f f e r e n t (p<0.05) 41 F i g u r e 6. Changes i n t h e r e l a t i v e l i g h t (PPFD) i n t e n s i t y b e n e a t h a r e d a l d e r c a n o p y (7 y e a r o l d , 8 m t a l l ) following a herbicide application. Points separated v e r t i c a l l y by more t h a n t h e v e r t i c a l b a r a r e s i g n i f i c a n t l y d i f f e r e n t (p<0.05) 42 F i g u r e 7. S o l a r r a d i a t i o n q u a l i t y ( a t 50 cm) 7 - y e a r - o l d (8 m) r e d a l d e r c a n o p y  under  a 44  F i g u r e 8a-b. D i u r n a l p a t t e r n s of p h o t o s y n t h e t i c photon f l u x d e n s i t y (PPFD), a t m o s p h e r i c v a p o r p r e s s u r e d e f i c i t ( D ) , l e a f d i f f u s i v e c o n d u c t a n c e ( g ^ ) , and p h o t o s y n t h e s i s f r o m t h e May 24, 1983 Haney r e l e a s e t r i a l s , (a) m e a s u r e d May 26, 1983 on 1983 f o l i a g e , (b) m e a s u r e d J u n e 17, 1983 on 1983 f o l i a g e 107 F i g u r e 9a-b. D i u r n a l p a t t e r n s of p h o t o s y n t h e t i c photon f l u x d e n s i t y (PPFD), a t m o s p h e r i c v a p o r p r e s s u r e d e f i c i t ( D ) , l e a f d i f f u s i v e c o n d u c t a n c e (g-]_) , a n d p h o t o s y n t h e s i s f r o m t h e A u g u s t 18, 1983 Haney r e l e a s e t r i a l s , (a) m e a s u r e d A u g u s t 20, 1983 on 1983 f o l i a g e , (b) m e a s u r e d S e p t e m b e r 11, 1983 on 1983 f o l i a g e 110  xii Figure lOa-b. D i u r n a l p a t t e r n s of p h o t o s y n t h e t i c photon f l u x d e n s i t y (PPFD), a t m o s p h e r i c v a p o r p r e s s u r e d e f i c i t (D), l e a f d i f f u s i v e c o n d u c t a n c e ( g ^ ) , and p h o t o s y n t h e s i s f r o m t h e J u n e 9, 1984 Haney r e l e a s e t r i a l s , (a) m e a s u r e d J u n e 11, 1984 on 1984 f o l i a g e , (b) m e a s u r e d J u l y 12, 1984 on 1984 f o l i a g e 114 Figure l l a - b . D i u r n a l p a t t e r n s of p h o t o s y n t h e t i c photon f l u x d e n s i t y (PPFD), a t m o s p h e r i c v a p o r p r e s s u r e d e f i c i t (D), l e a f d i f f u s i v e c o n d u c t a n c e ( g n ) , and p h o t o s y n t h e s i s f r o m t h e A u g u s t 7, 1984 Haney r e l e a s e t r i a l s , (a) m e a s u r e d A u g u s t 9, 1984 on 1984 foliage. (b) m e a s u r e d S e p t e m b e r 7, 1984 on 1984 f o l i a g e . . . . 1 1 7 F i g u r e 12a-c. D i u r n a l p a t t e r n s o f p h o t o s y n t h e t i c photon f l u x d e n s i t y (PPFD), a t m o s p h e r i c v a p o r p r e s s u r e d e f i c i t (D) , l e a f d i f f u s i v e c o n d u c t a n c e (g-^) , and p h o t o s y n t h e s i s from the 1983 Haney r e l e a s e t r i a l s , (a) m e a s u r e d S e p t e m b e r 24, 1983 on 1983 f o l i a g e , (b) m e a s u r e d S e p t e m b e r 7, 1984 on 1983 f o l i a g e . (c) m e a s u r e d S e p t e m b e r 8, 1984 on 1984 f o l i a g e . Box= May 24, 1983 t r e a t m e n t ; t r i a n g l e = A u g u s t 18, 1983 t r e a t m e n t ; s o l i d dot= u n t r e a t e d c o n t r o l 120 F i g u r e 13a-b. D i u r n a l p a t t e r n s o f p h o t o s y n t h e t i c photon f l u x d e n s i t y (PPFD), a t m o s p h e r i c v a p o r p r e s s u r e d e f i c i t (D) , l e a f d i f f u s i v e c o n d u c t a n c e (g-^) , and p h o t o s y n t h e s i s from the 1984 Haney r e l e a s e t r i a l s , (a) m a n u a l r e l e a s e , m e a s u r e d O c t o b e r 3, 1984 on 1984 f o l i a g e , (b) h e r b i c i d e r e l e a s e , m e a s u r e d O c t o b e r 3, 1984 on 1984 f o l i a g e . Box= J u n e 9, 1984 treatment; r i n g = J u l y 10, 1984 t r e a t m e n t ; t r i a n g l e = A u g u s t 7, 1984 t r e a t m e n t ; diamond= S e p t e m b e r 5, 1984 t r e a t m e n t ; solid dot= u n t r e a t e d c o n t r o l 123 F i g u r e 14a-b. D i u r n a l p a t t e r n s o f p h o t o s y n t h e t i c photon f l u x d e n s i t y (PPFD), a t m o s p h e r i c v a p o r p r e s s u r e d e f i c i t ( D ) , l e a f d i f f u s i v e c o n d u c t a n c e (g^ ) , and p h o t o s y n t h e s i s from the 1983 P o w e l l R i v e r r e l e a s e t r i a l s , (a) m e a s u r e d J u n e 20, 1984 on 1983 f o l i a g e , (b) m e a s u r e d J u n e 20, 1984 on 1984 f o l i a g e . Box= J u n e 7, 1983 t r e a t m e n t ; c i r c l e = J u l y 19, 1983 treatment; t r i a n g l e = A u g u s t 30, 1983 t r e a t m e n t ; diamond= December 27, 1984 t r e a t m e n t ; s o l i d d o t = u n t r e a t e d c o n t r o l . 130  xiii L I S T OF APPENDICES  Appendix  1  Appendix 2 thesis  Examples data Glossary  anaylsis  of abbreviations  169 used i n the 189  ACKNOWLEDGEMENTS  I w o u l d l i k e t o e x p r e s s my s i n c e r e a p p r e c i a t i o n t o D r . J.P.  K i m m i n s who p r o v i d e d  d i r e c t i o n and f i n a n c i a l  at a l l s t a g e s o f t h i s work. c o m m i t t e e , D r s . A. B l a c k ,  The o t h e r  P. J o l l i f f e ,  members o f my D. L a v e n d e r , a n d G.  Weetman, I w o u l d l i k e t o t h a n k f o r t h e i r a d v i c e reading  of this thesis.  assistance  I am f u r t h e r i n d e b t e d  and c r i t i c a l t o the staff  of t h e U n i v e r s i t y o f B r i t i s h Columbia Research F o r e s t , Dr. J.  Bassman  (now a t W a s h i n g t o n S t a t e  many g r a d u a t e s t u d e n t s ,  U n i v e r s i t y ) , and t h e  undergraduate s t u d e n t s and student  t e c h n i c i a n s t h a t have l e n t a hand and f r e e l y engaged i n t h e exchange o f ideas Financial  and equipment.  s u p p o r t f o r t h i s p r o j e c t h a s come f r o m t h e  Canadian F o r e s t r y  Service  B.C. M i n i s t r y o f F o r e s t s . Ministry of Forests District  S p e c i a l t h a n k s t o t h e B.C.  Research s t a f f i n t h e Vancouver  f o r a l l o w i n g s a m p l i n g on t h e i r  i n s t a l l a t i o n near Powell This  ENFOR a n d PRUF p r o g r a m s a n d t h e  Forest  research  River.  work w o u l d n o t h a v e b e e n p o s s i b l e w i t h o u t my  Jeannette's patience,  c o n v i c t i o n , and a s s i s t a n c e .  wife  1 CHAPTER ONE INTRODUCTION  Competing v e g e t a t i o n the  establishment  o f crop t r e e s .  growth by r e d u c i n g in their 1984).  frequently delays  success  Attempts t o increase  t h i s competition  have v a r i e d  ( R u s s e l l 1961, D i e r a u f  Because t h e b i o l o g y  environments i s poorly  o r even p r e v e n t s tree  considerably  1977, S t e w a r t e t a l .  o f c o n i f e r growth i n brush  understood, i t i s often d i f f i c u l t t o  explain this variation satisfactorily. K l e b ' s c o n c e p t , r e c e n t l y r e s t a t e d by Kramer provides within, be  an o u t l i n e by w h i c h t h e v a r i a t i o n i n c o n i f e r g r o w t h a n d when r e l e a s e d  understood.  Kramer  from, competing v e g e t a t i o n  (1987) s t a t e s t h a t  environment operate c o o p e r a t i v e l y and  biochemical  quantity  (1987),  might  " h e r e d i t y and  through the p h y s i o l o g i c a l  processes of the t r e e t o determine the  and q u a l i t y o f growth...".  One c a n c o n c l u d e  from  t h i s concept t h a t c u l t u r a l treatments modify growth through changes i n p h y s i o l o g y . crop trees one  In order,  t o u n d e r s t a n d why a n d how  a r e a f f e c t e d by a p a r t i c u l a r f a c t o r o r t r e a t m e n t ,  must l e a r n how t h a t  physiological  factor or treatment a f f e c t s t h e i r  processes.  Trees acclimate  t o long-term changes i n t h e i r  e n v i r o n m e n t b y means o f a v a r i e t y o f p h y s i o l o g i c a l a n d morphological  changes t h a t a l l o w c o n t i n u e d  function i n that  new e n v i r o n m e n t .  A common e n v i r o n m e n t a l c h a n g e t h a t c a n  occur i n the l i f e  of a tree i s modification i n light  2 c o n d i t i o n s as a r e s u l t vegetation.  of a l t e r a t i o n i n the surrounding  D e c i d u o u s v e g e t a t i o n i s t h e most common  source  o f shade i n p l a n t a t i o n s o f young c o n i f e r s i n c o a s t a l P a c i f i c Northwest, c r e a t i n g overtopping g r e a t l y throughout The  canopy d e n s i t i e s t h a t  t h e year.  m i c r o c l i m a t e below deciduous  considerable seasonal v a r i a t i o n Zavitkovski, than  vary  1982).  canopies  ( H u t c h i s o n a n d M a t t , 1977;  F o l i a t e d canopies  90% o f t h e i n c o m i n g  undergoes  may i n t e r c e p t more  photosynthetically-active  radiation  i n c o m p a r i s o n w i t h up t o 5 0 % ' i n t e r c e p t i o n b y l e a f l e s s canopies  (Monsi  Zavitkovski,  a n d S a e k i , 1 9 5 3 ; R e i f s n y d e r a n d L u l l , 1965,  1982).  foliage selectively photosynthesis.  Light quality absorbs  Very  little  deciduous  a t t e n u a t i o n and e i t h e r  o r r e s p i r a t i o n w i t h i n hardwood  canopies.  i s known a b o u t t h e shade c a s t b y t h e common  competitors  the United States.  i n west c o a s t  forests  i n Canada and  Models f o r t h e d e s c r i p t i o n o f t h e l i g h t  a t t e n u a t i o n i n deciduous untested  wavelengths c r i t i c a l f o r  K i r a e t a l . (1969) r e p o r t e d a g o o d  c o r r e l a t i o n s between l i g h t photosynthesis  i s a l s o m o d i f i e d as t h e  canopies  e x i s t , but they are  f o r t h e species competing w i t h P a c i f i c  Northwest  conifers. A tree's a b i l i t y  t o grow amongst c o m p e t i t o r s  i s related  t o i t s " t o l e r a n c e " , which i s d e f i n e d as t h e r e l a t i v e c a p a c i t y t o s u r v i v e a n d grow u n d e r c o n d i t i o n s o f l o w available light 1979).  and h i g h r o o t c o m p e t i t i o n  The a b i l i t y  t o withstand low l i g h t  (Daniel et a l . levels  (i.e. to  3 be  "shade t o l e r a n t " )  i s generally  considered  important c h a r a c t e r i s t i c of t o l e r a n c e  the  most  ( S h i r l e y 1943,  SAF,  1944).  When c o n i f e r s grow w i t h i n d e c i d u o u s c a n o p i e s  relative  shading of the  may  the  canopy changes s e a s o n a l l y ,  and  so  r e l a t i v e p h y s i o l o g i c a l a c t i v i t y between s p e c i e s  different  shade t o l e r a n c e  In temperate r e g i o n s photosynthesis 1979).  the  Helms  continues  under those  canopies.  where w i n t e r s year round  of  are  mild,  (Kramer and  (1965) f o u n d t h a t D o u g l a s - f i r  Kozlowski,  i n the  Western  h e m l o c k zone o f W a s h i n g t o n s t a t e u s u a l l y h a v e p o s i t i v e a s s i m i l a t i o n rates throughout the when d e c i d u o u s c o m p e t i t o r s Emmingham and that  Waring  same r e g i o n may  are  autumn and  leafless.  1981)  a c c u m u l a t e more t h a n 50 p e r May.  have been v e r y  few  forest conifers.  Autumn and  i n which shade-intolerant  under deciduous To  winter  elevation  survive  l e s s e n the  o f t e n put  density  studies full  may  be  a  and  grow  competitors. c h a n c e s o f m o r t a l i t y and  t o improve  g r o w t h o f young c o n i f e r p l a n t a t i o n s , a c o n s i d e r a b l e is  (1979,  coastal  photosynthesis  c o n i f e r s can  of  season"  i n v e s t i g a t i o n s of the o f low  in  Despite  have f o r c o n i f e r growth, L i n d e r  annual c y c l e of photosynthesis  way  "non-growing  cent  noted i n h i s review of c o n i f e r photosynthesis  that there  by  (1974) show t h a t D o u g l a s - f i r t r e e s  the p o t e n t i a l importance t h i s may  times  Calculations  t h e i r a n n u a l a s s i m i l a t e b e t w e e n O c t o b e r and  photosynthesis  winter,  into vegetation  management t o r e d u c e  of deciduous competitors.  As  mentioned  the  effort the  previously,  4 there  i s considerable variation  results  from t h e s e e f f o r t s .  the magnitude  1  f a c t o r t h a t can e f f e c t  both  One  The  o c c u r r e n c e and e x t e n t  i s r e l a t e d to the a b i l i t y  higher  that  and t h e r a t e a t w h i c h r e s p o n s e o c c u r s i s  "release shock" . shock  i n the release response  l i g h t environments.  of f o l i a g e to acclimate  S i n c e t h e r a t e and e x t e n t  w h i c h f o l i a g e can a c c l i m a t e t o changes on t h e m a t u r i t y magnitude likely  of f o l i a g e  of l i g h t  of release  in light  is  to  dependent  ( J u r i k e t a l . , 1 9 7 9 ) , and t o t h e  intensity  change  (Powles, 1984), i t i s  t h a t t h e t i m i n g and m e t h o d o f r e l e a s e w i l l  release  to  affect  response.  T h i s t h e s i s has t h r e e m a j o r  s e c t i o n s , which  s t u d i e s t h a t were u n d e r t a k e n .  the  c a s t by two commonly o c c u r r i n g d e c i d u o u s  shade  competitors. physiology  The  second examines  and g r o w t h o f t h r e e  The  describe  the three  first  the seasonal  describes  patterns  c o n i f e r species growing  of under  d i f f e r e n t d e n s i t i e s o f t h e s e two d e c i d u o u s c o m p e t i t o r s . third  explores  e f f e c t s t h a t t h e t i m i n g and t h e m e t h o d o f  r e l e a s e h a v e on t h e r e s p o n s e o f s u p p r e s s e d D o u g l a s - f i r saplings.  1  The  t e r m r e l e a s e s h o c k i s c h a r a c t e r i z e d by t h e  visual  symptoms o f p o o r p l a n t a c c l i m a t i o n a f t e r e x p o s u r e t o environments with increased l i g h t (poor growth, c h l o r o s i s , Ronco  the  (1975)  and m o i s t u r e  deficits  casting of foliage etc.).  See  f o r f u r t h e r d i s c u s s i o n and r e l a t e d t e r m s .  The  5 RESEARCH  The thesis  overall  was  to  environment through and To  to  the  p r o v i d e an  created  time,  and  and  these  how  of  the  attenuation  within  Experiments  were  conifers  suppressed  overtopping The  was  the  to  deciduous  following  to the  environment  and  red  year  and  light  tested.  conifer  seedlings  m o r p h o l o g i c a l l y , by  competing  acclimate to  canopy.  of  the  to predict  how  the  deciduous  was  this  i t changes  environment  canopies test  that  throughout  Law  deciduous  saplings  of  light  physiologically  of  c o m p e t i t o r s , how  monitored  salmonberry  of  understanding  respond  Beer-Lambert  densities  research reported in  influence  conducted  influenced,  different how  deciduous  objectives  salmonberry  ability  were  by  of the  improved  reductions i n the  satisfy  alder  objective  OBJECTIVES  the  vegetation,  removal  and  of  competitors.  hypotheses  served  as  the  focus  of  this  research. 1. light of  The  Beer-Lambert  attenuation  ages 2.  canopies  at  low  The  autumn,  and  species  will  elevation  shade  will  within  law  canopies  in coastal  B.C.  acclimate to  be  lower  accurately  salmonberry  foliage  therefore  will  of  conifers  the  describe of  beneath  increased  light  autumn  than  during  variety  deciduous in  photosynthetic differences i n the  a  the between  midsummer.  6  3.  Growth  deciduous compared 4. which  canopies with The  red  and  be  between smaller  tolerant  method  during  exposure,  will  less  suppressed  overtopping status  differences  or  Douglas-fir  and  will  after  their  in  under d i f f e r e n t  tolerant  species  as  species.  (manual  alder  species  herbicide)  saplings  influence  acclimation  subsequent  are their  to  growth.  the  and  the  released  season from  physiological increased  in  7  STUDY  Three  experiments  DESIGN  were  conducted  t o meet  the  research  objectives: 1.  Characterization  salmonberry  and  Changes red  alder  The  vertical  light  which  2.  i n the  light  environment  The  data  i n age  above  the  were  and  of  two  the  by  sampling  a  chronosequence.  underplanted  and  quantified  sampling  and  period.  biomass,  was  o b t a i n e d by and  salmonberry  1 2 month  ground  canopies  a c t e d as  growth  seedlings  composition a two  period.  planting  and  year  Changes  total  hemlock  of  2).  under a  under  the  for same  other  sites  seedlings  3).  Conifer  through  (Chapter  followed over  within  P h y s i o l o g y and  known  were  i n consecutive years  (Chapter  and  canopies  distribution  varied  environment  alder  canopies  salmonberry.  light  red  attenuation  thicket  of the  growth  p l a n t e d under density  at  the  randomized dominated  grand design  sites.  a  were one  physiology over  end  were measured. and  (shading)  e s t a b l i s h m e n t and  in their  deciduous  of  the  third  canopies  maintained  year a  12  measurement month  growing  established  using a  from  western  completely  on  both  salmonberry  and  At  each  site,  replicate  three  red  period  season  Seedlings of Douglas-fir,  f i r were  of  alder areas  each  8 of three  c a n o p y d e n s i t i e s w e r e p r e p a r e d by m a n u a l  the vegetation  at ground l e v e l .  The  three  clipping  canopy d e n s i t i e s  were: (a) h i g h d e n s i t y a r e a s i n w h i c h t h e only  5-10%  of f u l l  sun  ( d e t e r m i n e d by  d a y l i g h t hours compared w i t h t h e adjacent  open  seedlings (c) low  i n t e g r a t i o n over  same measurement i n  ( c r e a t e d by  r e c e i v e d 25-35% o f f u l l density areas  the  seedlings  3.  Physiology The  light  and  thinning)  of f u l l  p h y s i o l o g i c a l status of from o v e r t o p p i n g  At each r e l e a s e treatment,  e s t a b l i s h e d using a completely  by  Douglas-fir red  appropriate  locations.  established  randomized design  consisting  are  f i e l d and  experimental and  f o u n d w i t h i n t h e methods s e c t i o n o f  the  (2, 3,  4).  These s t u d i e s r e q u i r e d  of r e p l i c a t e p l o t s i n three  l o c a t i o n s w i t h homogeneous  the  separate  In each case a survey of the p o t e n t i a l area  c o n d u c t e d and  and  laboratory procedures,  chapter  establishment  alder  treatment.  specific  analyses  4).  p l o t s were  A d e s c r i p t i o n of p l o t establishment,  data  (Chapter  c o n t r o l , a h e r b i c i d e release treatment,  a manual r e l e a s e  treatments,  where  sunlight.  c a n o p i e s were examined u s i n g a s e r i e s o f s i t e s  o f an u n t r e a t e d  stand)  growth of r e l e a s e d s a p l i n g s  saplings after release  i n which  sunlight.  ( s m a l l gaps i n the  r e c e i v e d a b o u t 90%  g r o w t h and  over time.  received  areas).  (b) medium d e n s i t y a r e a s the  seedlings  vegetative  was  9  c o n d i t i o n s were s e l e c t e d t o reduce v a r i a b i l i t y at a given and  site.  P l o t s w i t h i n s u i t a b l e a r e a s were mapped  randomly assigned  to the  d i f f e r e n t treatments.  s t u d i e s o f s a l m o n b e r r y g r o w t h and i n v o l v e d the  between p l o t s  Douglas-fir  p r e l o c a t i o n of p l o t s f o r f u t u r e  For  release use.  the  this  10  DESCRIPTION OF STUDY S I T E S  A.  Environmental The  setting  m a j o r s t u d i e s were l o c a t e d i n t h e s o u t h e r n ,  elevation area of the U n i v e r s i t y of B r i t i s h Research  F o r e s t n e a r Haney, B r i t i s h  50 km e a s t o f V a n c o u v e r study area i s t y p i c a l  (Fig. 1).  mountains o f southwestern  B. C :  Columbia  Columbia,  approximately  The t o p o g r a p h y  of the coastal  foothills  of the  of the  gentle slopes consisting of  g l a c i o - m a r i n e m a t e r i a l s over a c i d igneous bedrock. all  lower  p l o t s were h u m o - f e r r i c p o d z o l s  (Canada S o i l  S o i l s on  Survey  C o m m i t t e e , 1970) w i t h t e x t u r e s o f s a n d y l o a m t o loamy w i t h a l o w (<40%) c o a r s e f r a g m e n t The  content.  c l i m a t e i s warm m a r i t i m e m e s o t h e r m a l w i t h t h e  m a j o r i t y o f t h e average the winter. period. Table  sand  220 cm o f p r e c i p i t a t i o n  falling in  Summers a r e warm a n d o f t e n h a v e an e x t e n d e d d r y  Temperatures i n t h e w i n t e r a r e g e n e r a l l y  1 summarizes t h e temperatures  and p r e c i p i t a t i o n  t h e s t u d y p e r i o d a s w e l l a s t h e 20 y e a r a v e r a g e s the weather s t a t i o n a t t h e Research office.  mild.  Forest  (data  during from  administration  The s t u d y p l o t s w e r e w i t h i n t h e d r y s u b z o n e o f t h e  C o a s t a l W e s t e r n H e m l o c k Zone  (Krajina,  1965).  A detailed  description of the soils  and v e g e t a t i o n i n t h e a r e a o f t h e  t h e s e p l o t s c a n be f o u n d  i n Kiinka  (1976).  Part of the data contained i n Chapter at  a site  16 km n o r t h w e s t  head o f Okeover I n l e t  4 was  collected  o f P o w e l l R i v e r , B.C. n e a r t h e  (49.22°N 124.33°W).  T h i s a r e a has  F i g u r e 1. L o c a t i o n o f s t u d y s i t e s on t h e B r i t i s h Columbia Research f o r e s t .  University  12 T a b l e 1.  Mean m o n t h l y t e m p e r a t u r e a n d m o n t h l y  precipitation  at the A d m i n i s t r a t i o n  B u i l d i n g s i n 1983 a n d 1984, a n d t h e 20  year averages f o r the  UBC R e s e a r c h F o r e s t . Temperature  Month  Ave  1983 max Ave m i n  Ave  (°C)  1984 max Ave m i n  20 y r Ave max Ave m:  Jan  8.5  2.7  7.1  -1.9  3 .9  -1 .6  Feb  9.1  1.6  9.2  -2.1  6.6  0 .2  Mar  11.7  2.3  12.7  -0.2  8 .4  0 .8  Apr  14.7  2.5  13. 9  3.1  12 .4  3 .3  May  19.1  8.2  15.1  5.5  16 .8  6. 6  Jun  18.7  10.3  18.1  9.3  19 .4  9 .4  Jul  20.9  9.7  24.2  11.2  22 .6  10 .9  Aug  23.4  10.5  22.5  11.0  21 . 9  10 . 9  Sep  18.9  7.9  19.1  8.1  19 .2  8 .8  Oct  14.0  3.2  11.9  4.5  13 .2  5 .6  Nov  9.2  3.7  7.8  2.3  8 .0  1 .8  Dec  3.2  -5.1  3.3  -2.7  5 .3  0 .0  Precipitation  (mm)  1983  1984  Jan  363.8  432.2  289  Feb  310.2  217.4  219  Mar  189.9  218.9  231  Apr  123. 6  186.1  154  May  86.4  211.3  111  Jun  153.3  133.4  92  Jul  247.0  21.3  68  Aug  44 .1  63.7  80  Sep  113.5  116.0  128  Oct  156.4  252.3  244  Nov  482.5  367.6  275  Dec  131.1  216.2  315  2401.8  2436.4  2206  Total  20 v r  13 g e n t l e topography and d u r i c h u m o - f e r r i c p o d z o l s s o i l from g l a c i a l site,  till.  derived  The c l i m a t e i s d r y e r t h a n t h e Haney  r e c e i v i n g o n l y 120 cm o f p r e c i p i t a t i o n .  Twenty y e a r  a v e r a g e t e m p e r a t u r e s a r e 2 °C i n J a n u a r y a n d 17 °C i n J u l y . The a r e a f a l l s w i t h i n t h e wet s u b z o n e o f t h e C o a s t a l D o u g l a s - f i r Zone  A.  Sample  (Krajina,  1965).  locations  The d a t a f o r e a c h o f t h e e x p e r i m e n t s r e p o r t e d i n C h a p t e r s 2, 3 1984.  a n d 4 were c o l l e c t e d d u r i n g 1982, 1 9 8 3 , a n d  S i t e s used i n s t u d i e s r e p o r t e d i n C h a p t e r 2 were  two s u b h y g r i c ( i m p e r f e c t l y d r a i n e d ) s a l m o n b e r r y (Fig.  from  thickets  1 A, B) a n d f r o m a m e s i c r e d a l d e r s t a n d ( F i g . 1 C ) . S i t e A had been c l e a r c u t and c a b l e y a r d e d i n t h e f a l l  of  1981.  I t was c h a r a c t e r i z e d b y a T s u g a h e t e r o p h y l l a /  A c h l y s t r i p h y l l a - P o l v s t i c h u m munitum p l a n t (Kiinka,  1976) a n d a moder humus f o r m .  association  The s i t e  elevation  was 200 m a b o v e s e a l e v e l : t h e s l o p e was 1 0 % t o t h e w e s t . S i t e B, u s e d i n s t u d i e s r e p o r t e d i n C h a p t e r s 2 a n d 3, c o n s i s t e d o f two s e p a r a t e s a l m o n b e r r y t h i c k e t s ,  one on t h e  margin o f a c l e a r i n g and t h e second w i t h i n a 1 5 - y e a r - o l d Douglas-fir plantation.  B o t h t h i c k e t s were on l e v e l  a n d o c c u p i e d o v e r 500 irr i n a r e a . -  ground  The t h i c k e t b o r d e r i n g t h e  c l e a r i n g was e i g h t y e a r s o l d a n d t h e o t h e r w i t h i n t h e p l a n t a t i o n was f i v e  y e a r s o l d i n 1982.  Both  received  s u b s u r f a c e m o i s t u r e i n t h e summer a n d were c h a r a c t e r i z e d b y the  Tsuga h e t e r o p h y l l a / P o l y s t i c h u m m u n i t u m - T i a r e l l a  14 t r i f o l i a t a plant  association  (Klinka,  1976) a n d h a d a m u l l  humus f o r m . S i t e C, u s e d t o c o l l e c t d a t a f o r C h a p t e r s 2, 3 a n d 4, was an a l d e r s t a n d  on a power l i n e  border of the research west. the  forest.  The s l o p e  The a r e a was m o d e r a t e l y d r a i n e d  Tsuoa h e t e r o p h y l l a / A c h l v s  plant  association  (Klinka,  groomed w i t h t r a c t o r s  degree o f s u r f a c e  1976).  i n 1973.  soil  alder establishment.  was 5% t o t h e  and c h a r a c t e r i z e d by  This  a r e a was c l e a r e d a n d  The a d j a c e n t  undisturbed  regeneration  disturbance  while  A l l Douglas-fir  and r e d a l d e r used i n Densities of red  a l d e r w e r e a p p r o x i m a t e l y 1500 s t e m s p e r h e c t a r e c l o s e d canopy 8 t o 9 meters t a l l .  The harvest 1979.  saplings  Powell  s i t e was g r o o m e d w i t h  i n 1978 a n d p l a n t e d Manual brushing  plantation i n the f a l l  hectare  The h e i g h t s  and formed a of the  averaged 3 meters.  River  alder resprouting,  the high  g u a r a n t e e d prompt r e d  e x p e r i m e n t s were 7 t o 8 y e a r s o f age.  Douglas-fir  near t h e  t r i p h v l l a - P o l v s t i c h u m muniturn  f o r e s t a s s u r e d ample D o u g l a s - f i r  the  right-of-way  a tractor  with Douglas-fir  after  seedlings i n  treatments of red alder i nthe o f 1980 r e s u l t e d i n v e r y  ranging  i n t h e study area.  of t h e treatments reported  dense r e d  f r o m 4,300 t o 51,500 s t e m s p e r By t h e s p r i n g o f 1983, t h e y e a r i n this thesis,  the red alder  c a n o p i e s were 3 meters t a l l  and t h e D o u g l a s - f i r  were 1.5 m e t e r s i n h e i g h t .  The s i t e b e l o n g s t o t h e  Pseudotsuga m e n z i e s i i / G a u l t h e r i a  shallon-Berberis  seedlings  nervosa  plant and  association.  t h e s l o p e was  (1984) c o n t a i n s  The e l e v a t i o n was 10-15% t o t h e w e s t .  100 m a b o v e s e a l e v e l P e n d l and D'Anjou  further d e t a i l s of the Powell River  site.  16 DESCRIPTION OF STUDY SPECIES The  two d e c i d u o u s  salmonberry rubra  species i n this  (Rubus s p e c t a b i l i s P u r s h )  s t u d y were and r e d a l d e r  (Alnus  Bong.). Salmonberry  i s a "strongly rhizomatous,  perennial species usually  1-3 (5) m t a l l ,  thicket-forming  t h e stem e r e c t t o  arching, usually strongly b r i s t l y below..leaves pinnately 3 (5) f o l i a t e . . . "  ( H i t c h c o c k e t a l . (1977).  Salmonberry  i sa  common u n d e r s t o r y component o f l o w l a n d m o i s t f o r e s t s , b u t i t o c c u r s up t o an e l e v a t i o n o f a b o u t Western  1400 m i n t h e C o a s t a l  Hemlock Zone o f t h e P a c i f i c N o r t h w e s t .  can form e x t e n s i v e and dense shrub t h i c k e t s  i n forest  o p e n i n g s where i t c a n r e t a r d shade i n t o l e r a n t r e g e n e r a t i o n by heavy  shading.  wide v a r i e t y o f mature f o r e s t s ,  Salmonberry  conifer  a l s o grows i n a  usually associated  c a n o p y o p e n i n g s , a n d i s c o n s i d e r e d t o be s h a d e Age  Salmonberry  with  tolerant.  o f t h e s a l m o n b e r r y t h i c k e t s a t s i t e A was known  from d i r e c t o b s e r v a t i o n a f t e r t h e c l e a r c u t t i n g ; p a r t s o f t h e same s i t e were s a m p l e d  i n three consecutive years.  The a g e s  o f t h e s a l m o n b e r r y t h i c k e t s a t s i t e B were d e t e r m i n e d records of disturbance date, the aging o f n a t u r a l  from  conifer  s e e d l i n g s w i t h i n t h e salmonberry, and a g i n g o f t h e salmonberry root s t o c k s , assuming d e v e l o p f o r two y e a r s Red  (Barbor,  t h a t r o o t s t o c k s do n o t  1976).  a l d e r commonly o c c u r s a s a s e r a i  s p e c i e s on  productive s i t e s throughout t h e P a c i f i c Northwest.  I t i sa  r a p i d l y g r o w i n g t r e e w h i c h c a n a t t a i n a maximum h e i g h t o f  17 25 m,  and  height  growth i n the  about a meter a year. it  generally  Red  10 y e a r s i s commonly  a l d e r can  suppresses the  produce dense shade  growth of a l l but  t o l e r a n t c o n i f e r s between the and  first  time the  i t s canopy growth s l o w s a t a s t a n d  and  t h e most s h a d e  a l d e r canopy  closes  age  40  o f 30  to  years. Leaves of red a l d e r are b r o a d l y long.  Red  a l d e r o c c u r s on  P a c i f i c N o r t h w e s t up and  elliptic  and  a wide range of s i t e s  t o a p p r o x i m a t e l y 800  of alder i s considered  t o be  i s u s u a l l y r a p i d on e x p o s e d m i n e r a l  in  low,  The  replaced  Torr.  &  by b l a c k  and  regeneration  s o i l w i t h i n the  heterophylla  i t tends  trichocarpa  and  w e s t e r n hemlock  (Raf.) S a r g . , g r a n d - f i r Douglas-fir  (Abies  (Tsuaa arandis  (Pseudotsuaa m e n z i e s i i  F r a n c o , were u s e d i n t h i s  study.  range o f shade t o l e r a n c e ,  a l t h o u g h t h e i r shade  r a t i n g by  different  However, t h e  f o l l o w e d by  three  extensive  (very-tolerant)  grand-fir  (intermediate are  of t o l e r a n c e  on  a  tolerance  (Minore,  197 9 ) ,  i s always given  Douglas-fir  (ratings after Fowells,  commercial species  brush competition  represent  as  as t h e most s h a d e t o l e r a n t  ( t o l e r a n t ) and  tolerance)  (Dougl.)  (Mirb.)  These s p e c i e s  a u t h o r s v a r i e s somewhat  r e l a t i v e order  w e s t e r n hemlock  All  Western  Gray).  Three c o n i f e r s p e c i e s ,  Lindl.,  (Populus  Cottonwood  the  shade  H e m l o c k Zone, e x c e p t w h e r e f r o s t h e a v i n g o c c u r s and t o be  cm  m in elevation,  a c h i e v e s i t s b e s t g r o w t h on m o i s t s i t e s .  tolerance  5-15  1976).  t h a t commonly e n c o u n t e r  cutovers  e i t h e r when  regenerating focus  n a t u r a l l y o r when p l a n t e d .  Douglas-fir i s the  o f the r e l e a s e s t u d i e s because i t s suppression  deciduous canopies i s p a r t i c u l a r l y  by  s e v e r e a n d commonplace.  19 CHAPTER 2  SEASONAL AND HERBICIDE-INDUCED CHANGES I N THE LIGHT ENVIRONMENT WITHIN THE CANOPIES OF TWO DECIDUOUS SPECIES  INTRODUCTION  A common o b j e c t i v e o f v e g e t a t i o n  management on m o i s t ,  fertile  forest sites  i s t o reduce s h a d i n g by competing  species  so t h a t c r o p t r e e s can a c h i e v e  high  growth r a t e s .  S h a d i n g o f y o u n g c o n i f e r s on t h e s e p r o d u c t i v e  sites i n the  P a c i f i c Northwest i s p r i m a r i l y by d e c i d u o u s s p e c i e s .  Little  i s known a b o u t t h e q u a l i t y , q u a n t i t y a n d d y n a m i c s o f t h e shade c a s t by d e c i d u o u s c o m p e t i t o r s , considerable  effort to limit  despite the  them t h r o u g h  vegetation  management. Studies  o f t h e shade c a s t b y b r o a d l e a f  some a g r i c u l t u r a l  c r o p s may p r o v i d e  f o r e s t s and  c l u e s about t h e l i g h t  environment o f young c o n i f e r s w i t h i n t h e canopy o f d e c i d u o u s plants.  Studies  demonstrated that  o f d e c i d u o u s f o r e s t c a n o p i e s have f o l i a t e d and l e a f l e s s  canopies can  i n t e r c e p t more t h a n 90% a n d 5 0 % o f t h e i n c i d e n t photosynthetic Saeki, 1971;  a c t i v e r a d i a t i o n , r e s p e c t i v e l y (Monsi and  1953; G e i g e r ,  1965; R e i f s n y d e r  Z a v i t k o v s k i , 1974).  and L u l l ,  1965; Horn,  However, f e w s t u d i e s g i v e i n s i g h t  as t o how m o d i f i c a t i o n s i n l i g h t q u a l i t y may d i f f e r a s p l a n t community s t r u c t u r e d e v e l o p s .  The s e a s o n a l  dynamics o f  20 light  conditions that are a r e s u l t of overstory  phenology  are r e c e i v i n g  p a r t because phenology McCree, The  foliage  increasing research attention,  of the c o n t r o l l i n g  influence that  has on u n d e r s t o r y p r o d u c t i v i t y  in  overstory  (Blackman,  1962;  1984). light  environment  w i t h i n deciduous canopies i s  c o n s t a n t l y c h a n g i n g t h r o u g h annual canopy growth, foliage cycles,  a n d d i u r n a l p a t t e r n s o f shadow  seasonal  and  sunfleeks.  Light quality  i s a l s o m o d i f i e d as  selectively  a b s o r b s a g r e a t e r p r o p o r t i o n o f b l u e and  than of other wavelengths,  foliage  and t h e l i g h t p a s s i n g t h r o u g h t h e  c a n o p y becomes i n c r e a s i n g l y e n r i c h e d w i t h g r e e n a n d i n f r a r e d wavelengths S m i t h , 1977;  red  ( F e d e r e r and T a n n e r ,  and F l o y d e t a l . , 1 9 7 8 ) .  q u a l i t a t i v e changes i n l i g h t  1966;  near-  Holmes  and  Both q u a n t i t a t i v e  and  are important i n d e s c r i b i n g  shade and i t s r o l e i n c a u s i n g p o s s i b l e  morphogenetic  responses of p l a n t s growing w i t h i n deciduous canopies. E x p e r i m e n t a l e v i d e n c e s u m m a r i z e d by S m i t h the  r o l e of l i g h t  quality  (1982)  illustrates  i n shade a c c l i m a t i o n t h r o u g h i t s  e f f e c t on s t e m e x t e n s i o n , l e a f s t r u c t u r e a n d  size,  and  the  physiological processes. Monsi and S a e k i  (1953)  proposed that the a t t e n u a t i o n  l i g h t w i t h i n a c a n o p y i s an e x p o n e n t i a l f u n c t i o n cumulative l e a f area, i n accordance w i t h the e x t i n c t i o n law. and B l a c k m a n and P e r t t u  Monteith  of  Beer-Lambert  ( 1 9 6 5 ) , K i r a e t a l . ( 1 9 6 9 ) , Newton  ( 1 9 7 0 ) , K a w a h a r a and T a d a k i  (1981), Wien  of  (1982)  (1978),  Lindroth  and o t h e r s h a v e f o u n d ,  that  21 the Beer-Lambert law d e s c r i b e d number o f d i f f e r e n t p l a n t  p l a n t communities, Anderson  a given  ina  communities.  However, b a s e d on a r e v i e w  Beer-Lambert e x t i n c t i o n  the l i g h t attenuation  of light penetration  into  (1964, 1966) w a r n e d t h a t t h e  c o e f f i c i e n t may n o t b e c o n s t a n t f o r  canopy o r s p e c i e s .  She p o i n t e d  out that t h e  a s s u m p t i o n s made by t h e B e e r - L a m b e r t Law a r e u n l i k e l y met  i n nature,  penetration  and d e m o n s t r a t e d t h a t l e a f i n c l i n a t i o n , l i g h t  angle,  and d i f f u s e  v s . beam r a d i a t i o n  m a j o r i n f l u e n c e s on t h e e x t i n c t i o n Araki  coefficients  c a n have  of  canopies.  (1985) s u g g e s t e d a s t r a t u m - s p e c i f i c a p p r o a c h f o r t h e  calculation resulting Yim  of extinction  c o e f f i c i e n t s t o avoid t h e problems  from h e t e r o g e n e i t y  i n canopy  characteristics.  e t a l . (1969) f o u n d t h a t s t e m s u r f a c e  (substituted attenuation  area  f o r l e a f area) a c c u r a t e l y d e s c r i b e d i n an a r t i f i c i a l l y  f o u n d t h a t stems and t w i g s  defoliated  of various  i n t e r c e p t e d f r o m 28 t o 69 p e r c e n t R o b e r t s and M i l l e r light  t o be  i n b o t h t h e summer a n d w i n t e r  Newton a n d B l a c k m a n  shrub stand.  shrub  They  species  of incident  (1977) r e p o r t e d  the light  light.  about 20% i n t e r c e p t i o n f o r two s h r u b  species.  (1970) s t a t e d t h a t s t e m s u r f a c e  area  must be i n c l u d e d f o r a v a l i d e s t i m a t i o n o f a c a n o p y extinction  coefficient.  interception  I t i s now r e c o g n i z e d  o f l i g h t n e e d s t o be c o n s i d e r e d ,  "whole-shrub" e x t i n c t i o n  coefficients  (Roberts  that  of  stem  and t h a t and M i l l e r ,  22 1977), which for  i n c l u d e b o t h l e a f and stem a r e a , a r e v a l u a b l e  d e s c r i b i n g l i g h t w i t h i n many d i f f e r e n t  plant  communities. H e r b i c i d e s a r e s o m e t i m e s e m p l o y e d on p r o d u c t i v e f o r e s t l a n d t o reduce The  s h a d i n g by a v a r i e t y  o f deciduous  e f f e c t s o f h e r b i c i d e t r e a t m e n t s on b r u s h  environments Staebler, Shure,  have r a r e l y been examined  plants.  light  (Rediske and  1 9 6 2 ; R e d i s k e e t a l . , 1963 a n d G o t t s c h a l k a n d  1979).  environment  S t u d i e s o f h e r b i c i d e - i n d u c e d changes i n l i g h t  may h e l p u s t o u n d e r s t a n d how p l a n t s  within  d e f o l i a t e d canopies respond t o these treatments. T h i s c h a p t e r has t h r e e o b j e c t i v e s :  1) To c h a r a c t e r i z e  the l i g h t  environment  deciduous  competitors i n t h e P a c i f i c Northwest  and  b e l o w t h e c a n o p i e s o f two common (red a l d e r  s a l m o n b e r r y ) , and t o d e s c r i b e f o r salmonberry t h e  w i t h i n - c a n o p y changes i n l i g h t q u a n t i t y and q u a l i t y take p l a c e through a growing as t h e c a n o p y d e v e l o p s . the Beer-Lambert  and from year t o y e a r  2) To t e s t t h e a p p r o p r i a t e n e s s o f  equation f o rdescribing l i g h t attenuation  w i t h i n salmonberry salmonberry  season,  that  thickets.  I t i s hypothesized that i n  canopies, t h e Beer-Lambert  law u s i n g l e a f  index, can d e s c r i b e l i g h t a t t e n u a t i o n i n f o l i a t e d and i n d e f o l i a t e d c a n o p i e s u s i n g s t e m a r e a i n d e x .  canopies 3) t o  d e s c r i b e t h e e f f e c t s o f a h e r b i c i d e t r e a t m e n t on l i g h t q u a n t i t y and q u a l i t y .  area  23 METHODS  A. S a m p l i n g  plots  T h r e e r e p l i c a t e a r e a s c o n s i s t i n g o f homogeneous salmonberry  t h i c k e t s were l o c a t e d a t s i t e A i n 1982 f o r  s a m p l i n g i n 1982, 1983, and 1984 of the s i t e ) . replicate, i n each  and a sample t a k e n from each Sampling  salmonberry  l o c a t i o n s w e r e l o c a t e d by  compass b e a r i n g s .  In  t h i c k e t s aged 5 and 8 y e a r s were  s a m p l e d i n 1983 a t s i t e B. site  of the three plots  2 m from t h e f i x e d p l o t c e n t e r , s u c c e s s i v e samples  being located along different addition,  1 for details  A p l o t c e n t e r was e s t a b l i s h e d i n e a c h  of three years.  measuring  (see Chapter  A l d e r d a t a were c o l l e c t e d  from  C.  B. F i e l d Herbicide  treatments treatment  Stems o f r e d a l d e r w e r e i n j e c t e d w i t h 2,4-D  amine on  May 24, 1983 i n o r d e r t o s t u d y t h e r a t e o f d e f o l a t i o n a n d i n c r e a s e s i n l i g h t beneath  the canopies.  Approximately  o f a 4 0 % s o l u t i o n was u s e d p e r c e n t i m e t e r o f s t e m  3 mL  diameter.  The h e r b i c i d e was a p p l i e d t o c u t s i n t h e b a r k a n d cambium t h a t were a n g l e d t o h o l d t h e h e r b i c i d e i n t h e c u t s u r f a c e .  C. F i e l d m e a s u r e m e n t s V e r t i c a l biomass and a r e a p r o f i l e s Salmonberry  f o r salmonberry  c a n o p i e s were d e s t r u c t i v e l y  using the s t r a t i f i e d c l i p technique  sampled i n J u l y  (50 cm i n t e r v a l s )  (Monsi  24 and S a e k i ,  1953).  margin, a i m  A t a minimum o f 2 m f r o m t h e  s a m p l e p l o t was  square metal p l o t  frame.  d e f i n e d on t h e g r o u n d by a  V e r t i c a l p o l e s were d r i v e n  the ground at each c o r n e r of the p l o t column  thicket  o f v e g e t a t i o n t o be s a m p l e d .  w i t h i n e a c h 50 cm s t r a t u m (measured  into  frame t o d e f i n e t h e A l l l e a v e s and  stems  from t h e ground)  were  c l i p p e d and p l a c e d i n i n d i v i d u a l b a g s f o r t r a n s p o r t t o t h e laboratory.  Three 1 m  r e p l i c a t e p l o t s were sampled i n each  o f t h e f i v e t h i c k e t ages  (3 ages a t s i t e A;  2 ages a t  site  B) . In the l a b o r a t o r y , The  l e a v e s were s e p a r a t e d f r o m  s u r f a c e a r e a o f t h r e e 30 g s u b s a m p l e s  e a c h s t r a t u m was  by d i v i d i n g a l l ( b e l o w 0.25,  of leaves  determined w i t h a l e a f a r e a meter  Lambda I n s t r u m e n t s ) b e f o r e d r y i n g . t h e stems  from (LI-3000,  Stem a r e a was e s t i m a t e d  into four diameter s i z e  0.25-0.49, 0.5-0.74, and 0.75  s u b s a m p l i n g stems  stems.  from each s i z e c l a s s ,  cm a n d  classes larger),  and d e t e r m i n i n g t h e  p r o j e c t e d a r e a o f each subsample w i t h a l e a f a r e a meter. L e a v e s and stems w e r e d r i e d a t 65°C t o a c o n s t a n t w e i g h t . The  a v e r a g e s p e c i f i c s t e m a r e a p e r s t e m s i z e c l a s s was  t o c o n v e r t s t e m w e i g h t t o stem  used  area.  I n t e g r a t i o n o f l i g h t w i t h i n and b e n e a t h c a n o p i e s The  integration of l i g h t  (photosynthetically  active  p h o t o n f l u x d e n s i t y , PPFD) w i t h i n t h e s a l m o n b e r r y c a n o p i e s a n d b e n e a t h t h e r e d a l d e r c a n o p y was a n t h r a c e n e method  determined using the  ( D o r e , 1958; R e d i s k e e t a l . ,  1963;  Marquis  25 and Y e l e n o s k y , 1962; F i s h e r and M e r r i t t , borosilicate vials solution canopy  1973) .  Fifteen  (7 mL) c o n t a i n i n g 6 mL o f a n t h r a c e n e  (0.1 g a n t h r a c e n e / 1 b e n z e n e ) were u s e d i n e a c h  s t r a t a measured and i n a nearby unshaded  area.  Diurnal  integrations of light  a t 50 cm were m e a s u r e d a t  monthly  i n t e r v a l s under t h e 5 - y e a r - o l d salmonberry  and t h e r e d a l d e r s t a n d i n 1983.  thicket  L i g h t was i n t e g r a t e d a t 50  cm h e i g h t i n t e r v a l s w i t h i n s a l m o n b e r r y c a n o p i e s j u s t  prior  to destructive sampling. V i a l s were suspended e l a s t i c bands t o t h e v i a l  by a h o r i z o n t a l cap.  s t r i n g a t t a c h e d by  The e x p o s e d v i a l s  were  t r a n s p o r t e d i n a l i g h t - p r o o f c o n t a i n e r and a n a l y z e d w i t h i n two d a y s o f e x p o s u r e .  Decreases  concentrations resulting d e t e r m i n e d by changes spectrophotometer  i n anthracene  from exposure t o l i g h t  were  i n UV a b s o r p t i o n u s i n g a UV  (Unicam SP8000) a t 350 nm w a v e l e n g t h .  C a l i b r a t i o n o f a n t h r a c e n e c o n c e n t r a t i o n change t o c u m u l a t i v e p h o t o s y n t h e t i c a l l y a c t i v e photon  f l u x d e n s i t y was made b y  c o r r e l a t i n g anthracene absorption t o cumulative readings f r o m quantum s e n s o r s s o l a r monitor  ( L I - 1 9 0 S , LI-COR) a n d an i n t e g r a t i n g  (LI-1776, LI-COR).  A regression equation  9  h a v i n g an r =0.97  ( A p p e n d i x 1) was d e v e l o p e d t o c o n v e r t  anthracene a b s o r p t i o n o f exposed v i a l s t o c u m u l a t i v e p h o t o s y n t h e t i c a l l y a c t i v e photon  flux density  (PPFD).  26 Determination of light quality within The to  was d e t e r m i n e d  and r e d a l d e r  canopies  using a portable spectroradiometer  International Light).  Radiant energy  t a k e n a t 20 nm w a v e l e n g t h the 5-year-old salmonberry  The  i n t h e 300  s p e c t r a l d i s t r i b u t i o n o f r a d i a n t energy  900 nm r e g i o n u n d e r s a l m o n b e r r y  slightly  canopies  intervals  (IL-700,  measurements were  f r o m 300 t o 900 nm u n d e r  and t h e r e d a l d e r stand under  o v e r c a s t c o n d i t i o n s on S e p t e m b e r 19 a n d 20,  tripod-mounted  s e n s o r was h e l d a t 1 m a b o v e t h e g r o u n d .  Measurements o f t h e photon also determined  1983.  f l u x a t 660 nm a n d 730 nm w e r e  a t 50 cm h e i g h t i n t e r v a l s w i t h i n one o f t h e  sample p l o t s o f each o f t h e f i v e ages o f s a l m o n b e r r y t h i c k e t s b e f o r e t h e y were d e s t r u c t i v e l y  Calculation of extinction  sampled.  coefficients  Beer-Lambert l i g h t e x t i n c t i o n c o e f f i c i e n t s  f o r the  summer a n d w i n t e r were c a l c u l a t e d f r o m d a t a on l e a f  area  i n d e x a l o n e , stem a r e a i n d e x a l o n e , and f o r t h e combined l e a f and stem a r e a i n d e x f o r t h e s a l m o n b e r r y v a r i o u s ages, and w i n t e r .  and l i g h t v a l u e s d e t e r m i n e d The e x t i n c t i o n c o e f f i c i e n t  thickets of  i n b o t h t h e summer (K) d e s c r i b e s t h e  amount o f a t t e n u a t i o n o f l i g h t w i t h i n a c a n o p y i n r e l a t i o n to a area index.  The g r e a t e r t h e K, t h e g r e a t e r t h e  27  a t t e n u a t i o n f o r a g i v e n area index.  The f o l l o w i n g equation  was used t o determine the e x t i n c t i o n c o e f f i c i e n t I /I 2  where:  I  z  0  =exp [-K(F or A)]  = P h o t o s y n t h e t i c a l l y a c t i v e photon f l u x at height z with the  I  Q  (K).  canopy.  = P h o t o s y n t h e t i c a l l y a c t i v e photon f l u x above the  canopy.  K  = Extinction  coefficient.  F  = Cumulative l e a f area from the top of the canopy t o z.  A  = Cumulative stem area from the top of the canopy t o height z.  Z  Data  = Height i n the  canopy.  analysis Data were s u b j e c t e d to a one-way a n a l y s i s of v a r i a n c e .  S i g n i f i c a n c e between s t r a t a was  determined at p< 0.05  the Tukey m u l t i p l e comparisons t e s t  (Stoline,  1981).  with Linear  r e g r e s s i o n models were used t o d e s c r i b e l i g h t a t t e n u a t i o n i n r e l a t i o n t o cumulative area i n d i c e s .  28 RESULTS  A. D i s t r i b u t i o n the l i g h t The  o f l e a f and stem biomass and a r e a i n d e x , and  a t t e n u a t i o n w i t h i n salmonberry  v e r t i c a l d i s t r i b u t i o n s o f l e a f and stem biomass and  area i n d i c e s , salmonberry  and t h e accompanying l i g h t  attenuation, within  c a n o p i e s o f v a r i o u s ages a r e g i v e n i n F i g u r e 2.  By t h e g r o w i n g  season  o v e r s t o r y and removal  following clearcutting of the of commercially valuable portions of  t h e t r e e s t e m s a t s i t e A, a s a l m o n b e r r y w h i c h was t a l l e r  t h a n 50 cm  a r e a i n d e x o f 0.8 nr-*m t h e same s a l m o n b e r r y 9  and  canopies  .  canopy had developed  ( F i g . 2a) a n d h a d a t o t a l  leaf  By two a n d t h r e e y e a r s o f a g e ,  t h i c k e t h a d l e a f a r e a i n d i c e s o f 3.0  _9  7.6 irr'm  , respectively  ( F i g s . 2b a n d 2 c ) .  The c a n o p y  r e a c h e d a h e i g h t o f 1 t o 1.5 m i n y e a r 2, a n d r e m a i n e d  at  a b o u t t h e same h e i g h t i n y e a r 3 as e l o n g a t i n g s t e m s made a transition  from t h e near v e r t i c a l growth  t o an a r c h i n g f o r m .  year  I n t h e 5 - y e a r - o l d s t a n d t h e canopy  h e i g h t was b e t w e e n 1.5 a n d 2 m 9  of the f i r s t  ( F i g . 2d) w i t h a l e a f  area  _9  i n d e x o f 10.7 irr'm  , while the 8-year-old  t h i c k e t had reached  a height of nearly 3 m with a cumulative  l e a f a r e a i n d e x o f 13.0 m -m 2  always  -2  ( F i g . 2e).  salmonberry  L e a f a r e a was  low a t t h e base o f t h e canopy and g e n e r a l l y i n c r e a s e d  with height. _9  The from  r a t i o o f l e a f t o stem biomass  0.8 t o 0.6  h e i g h t growth  (Kg'm ^)  decreased  f r o m y e a r 1 t o y e a r 2, a s s t e m b r a n c h i n g a n d  accelerated.  The r a t i o r e m a i n e d  constant at  29  AREA & LIGHT INTENSITY  BIOMASS 1 yr old  200  200-1  n  Legend  Legend E23 Stems  EZ3 Leaves  £ o  0  100  200  300  1.5  400  3  4.5  LAI or SAI (m • m )  Foliage or Stems (g/m )  2  2  0  25  50  z  75  100  Relative Light Intensity (%) F i g u r e 2a-e. V e r t i c a l d i s t r i b u t i o n o f l e a f and stem b i o m a s s , l e a f a n d s t e m a r e a i n d e x , a n d r e l a t i v e l i g h t (PPFD) i n t e n s i t y w i t h i n s a l m o n b e r r y t h i c k e t s i n t h e summer a n d t h e w i n t e r , (a) 1 - y e a r - o l d t h i c k e t ; (b) 2 - y e a r - o l d t h i c k e t ; (c) 3 - y e a r - o l d t h i c k e t ; (d) 5 - y e a r - o l d t h i c k e t ; (e) 8 - y e a r - o l d thicket.  AREA & LIGHT INTENSITY  BIOMASS 3 yr old  Legend  200-1  5  Legend  O  Summer  U&  Stems  A  Winter  EZ3  Leaves  yr old  LAI or SAI {m • nr )  Foliage or Stems (g/m )  2  2  0  25  50  2  75  100  Relative Light Intensity {%)  BIOMASS 8 yr old  A R E A & LIGHT INTENSITY  Foliage (g/m )  LAI or SAI (m • rrr )  2  2  2  i  i  i  i  i  i  i  i  i  i  0  0.5  1  1.5  2  0  25  50  75  100  Stems (kg/m ) 2  Relative Light Intensity (%) to  32 a b o u t 0.6  i n s t a n d s o f a g e s 3 and  g r o w t h o f stem d i a m e t e r , branching, resulted  5.  However,  s t e m h e i g h t , an i n c r e a s e i n s t e m  and a s l o w i n g o f l e a f b i o m a s s g r o w t h  i n a t o t a l l e a f t o stem weight  8-year-old salmonberry thickets,  continued  stem w e i g h t  h e i g h t , but  thicket.  r a t i o of  In younger  g r e a t e s t b e t w e e n 1 and  2 m.  The  .15  i n the  salmonberry  declined with increasing  i n the 8-year-old t h i c k e t  rate,  canopy  stem biomass  was  r a t i o of l e a f area to  a r e a r e m a i n e d c o n s i s t e n t a t a b o u t 20  f o r the  first  3  consecutive years of growth  (Figs.  and  l e a f a r e a t o stem a r e a r a t i o s  8-year-old thickets  31 and  7,  had  2a t h r o u g h  stem  expressed  i n t h e open d e c l i n e d as t h i c k e t s  as p e r c e n t  i n c r e a s e d i n age  summer f o l i a t e d and w i n t e r l e a f l e s s p e r i o d s  depth  2e).  In a l l canopies,  i n t h e canopy.  intensities  5 of  o f a b o u t 9%  full  thickets.  gave v a l u e s o f 0.5  f o r both  (Figs.  2a  integrated light  sun w e r e f o u n d u n d e r t h e 5 However,  measurements under t h e s e c a n o p i e s , typically  of l i g h t  light intensity declined with  Minimum d i u r n a l  8 y e a r - o l d salmonberry  light  The  respectively.  L i g h t i n t e n s i t y a t 50 cm  through  2c).  and  instantaneous  avoiding sunflecks,  t o 3% o f t h e u n s h a d e d m i d - d a y  values.  B. B e e r - L a m b e r t e x t i n c t i o n The  extinction  area index  (K ) F  coefficients  c o e f f i c i e n t b a s e d on c u m u l a t i v e  f o r salmonberry  d e c l i n e d as l e a f a r e a i n d e x and  canopies  a b o v e 50  leaf  cm  stem a r e a i n d e x i n c r e a s e d i n  T a b l e 2. Mean r e l a t i v e l i g h t (PPFD) i n t e n s i t y a t 50 cm, c u m u l a t i v e l e a f a r e a i n d e x ( L A I ) a n d s t e m a r e a i n d e x (SAI) a b o v e 50 cm, a n d B e e r - L a m b e r t e x t i n c t i o n c o e f f i c i e n t s (K) t o 50 cm f o r d i f f e r e n t a g e s o f s a l m o n b e r r y t h i c k e t s b a s e d on LAI o n l y ( K ) and combined L A I and SAI ( K ) i n t h e summer a n d S A I ( K ) o n l y i n t h e w i n t e r ( s e e F i g u r e s 2a t h r o u g h 2e for s p e c i f i c stand data). F  F + A  A  S t a n d age 1 2 3 5 8 S t a n d age 1 2 3 5 8  % light a t 50 cm 78a 12b 10c 3d 2d  1  % light a t 50 cm 98a 8 6b 77c 64d 42e  1  —summer— 9 LAI (m •m~ ) 2  K  Z  . 6e 2 .0d 7 • 4c 10 .4b 13 . 0a  1 . 91a . 91b .27d .4 6c .42c  --wi n t e r — SAI (m* •m )  K  z  .02d . 08c .2 9b .24b 1 .41a  t— - i  F+A  1.83a .87b .2 6e .46c .38d  A o r  o i . i. O a 12 .42b 3 .73c 4 .69c .88d  Mean v a l u e s w i t h i n a c o l u m n f o l l o w e d w i t h d i f f e r e n t l e t t e r s a r e s i g n i f i c a n t l y d i f f e r e n t (p<0.05).  34 3 years o f growth  the f i r s t  (Table 2).  of t h e 5 and 8 - y e a r - o l d t h i c k e t s of t h e 3 - y e a r - o l d t h i c k e t , different  from each  K  F  were b o t h g r e a t e r t h a n t h a t  b u t were n o t s i g n i f i c a n t l y  other.  (A) t o t h e c a l c u l a t i o n  The c u m u l a t i v e K ' s  The a d d i t i o n  F + A  3-4%  by about  compared t o v a l u e s o b t a i n e d u s i n g l e a f a r e a i n d e x ( T a b l e 2). extinction  The i n c l u s i o n  thicket,  8-year-old t h i c k e t .  effect  However, e x t i n c t i o n  (summer f o r K  and K  F  v a l u e s o f 0.79,  respectively  (Appendix  Changes i n K i n Table K  F  3.  F  year-old thicket  0.79,  ( K ) show t h a t A  days.  , winter for K ) A  area  indices.  i n t e n s i t y on a r e a  a n d 0.83  for K , K F  indices  , and K  F + A  A  1).  between d i f f e r e n t  canopy s t r a t a  a t t h e t o p o f t h e canopy.  the values of K  t h r o u g h t h e canopy.  A variety  F  are given  I n t h e 8-  increased with  depth  o f l e a f a n g l e s c o u l d be f o u n d  the canopies, but the i n c l i n a t i o n o f leaves i n  t h e u p p e r most s t r a t a o f l e a v e s w e r e g e n e r a l l y of  based  I n canopies younger than 8 y e a r s , t h e h i g h e s t  v a l u e was a l w a y s  throughout  F + A  with increasing  Regressions of log r e l a t i v e l i g h t 2  levels  r e a c h i n g 50 cm on c l e a r w i n t e r  on l i g h t  declined logarithmically  r  coefficients  o f even s m a l l stem a r e a s c a n have a s i g n i f i c a n t  Light levels  had  i n t h e 5-year-old  i n a 10% r e d u c t i o n i n t h e  and r e s u l t e d  on s t e m a r e a i n d e x a n d w i n t e r l i g h t the presence  alone  o f stem a r e a t o t h e c a l c u l a t i o n o f  c o e f f i c i e n t s made no d i f f e r e n c e  salmonberry  index  decreased the e x t i n c t i o n  f o r 1 t o 3 year o l d t h i c k e t s  coefficient  o f stem a r e a  45 t o 8 5 ° .  i n t h e range  The a n g l e d e c l i n e d downward t h r o u g h t h e  35 Table 3. H o r i z o n - s p e c i f i c , v e r t i c a l d i s t r i b u t i o n o f BeerLambert e x t i n c t i o n c o e f f i c i e n t s (based on l e a f area index) and s p e c i f i c l e a f areas w i t h i n salmonberry canopies o f d i f f e r e n t ages (see F i g u r e s 2a through 2e f o r s p e c i f i c stand data). Beer-Lambert e x t i n c t i o n canopy horizon (cm)  — s t a n d age 1  250-300 200-250 150-200 100-150 50-100 Specific  2  1.61a .7 9b  1.91 l e a f area  50 cm canopy h o r i z o n base (cm) 250-300 200-250 150-200 100-150 50-100 0- 50  coefficients  (cm  a-  1  162b 172a  (years)—  1  .54a .23b  5  1.30a .23c .41b  8 22e 30d 1 77c 13 43b 56 38a  )  2  1  F  3  — s t a n d age 1  (K )  153c 164b 180a  3  149b 150b 227a  (years)— 5  163d 168c 188b 196a  8 156e 158e 173d 206c 228b 256a  1  Mean v a l u e s w i t h i n a column f o l l o w e d with ^ d i f f e r e n t l e t t e r s are s i g n i f i c a n t l y d i f f e r e n t (p<0.05).  36 canopy t o n e a r l y z e r o at t h e base  o f t h e canopy.  Specific  l e a f area i n c r e a s e d w i t h depth i n a l l of the canopies (Table  3).  C. A n n u a l  changes i n l i g h t q u a n t i t y and q u a l i t y  within  salmonberry canopies. Seasonal averages of l i g h t  (PPFD) i n t e g r a t e d u n d e r  a  s a l m o n b e r r y c a n o p y and i n an u n s h a d e d a r e a a r e shown i n F i g u r e 3.  The  h i g h e s t l i g h t under  d u r i n g M a r c h and t h e l o w e s t was  the salmonberry  was  i n J u n e and J u l y .  Flowering  and l e a f e x p a n s i o n b e g a n i n M a r c h a n d r e s u l t e d i n r e d u c t i o n s in total  light penetration.  intensity  Declines i n relative  light  c o n t i n u e d as f o l i a g e d e v e l o p e d t h r o u g h t h e  r e a c h i n g about  9% f u l l  sun i n May.  Light  levels  spring  increased  as l e a v e s s e n e s c e d i n t h e autumn, b u t d e a d l e a v e s w e r e commonly e n t r a p p e d by and d r a p e d o v e r b r a n c h e s , may  h a v e h a d a c o n t i n u e d i n f l u e n c e on l i g h t  and  these  attenuation  throughout the winter. The  s p e c t r a l energy d i s t r i b u t i o n o f l i g h t under  5 - y e a r - o l d salmonberry t h i c k e t  i s shown i n F i g u r e 4 .  the  p h o t o s y n t h e t i c a l l y a c t i v e spectrum,  the  b l u e a n d r e d l i g h t was  an e n v i r o n m e n t far-red of  (730)  different  light  The  ratio  The  creating  of red  (or z e t a ) , w i t h i n s a l m o n b e r r y  ages i s g i v e n i n T a b l e 4 .  Within  a l a r g e r amount o f  a b s o r b e d by t h e c a n o p y ,  enriched i n green.  a  (660)  canopies  zeta values  c o n s i s t e n t l y d e c l i n e d with depth through a l l the canopies.  to  F i g u r e 3. M e a n m o n t h l y l i g h t (PPFD) i n t e n s i t y ( a t 50 cm) u n d e r a 5 - y e a r - o l d l i v e salmonberry thicket (LAI=10.7), and i n a c l e a r i n g . Mean m o n t h l y v a l u e s with different l e t t e r s are s i g n i f i c a n t l y d i f f e r e n t (p<0.05).  100000  10000-  E c E  1000T  -  ^  ^  \  ^  100-  Legend A No canopy •  10300  400  500  600  700  Live  800  canopy 900  Wavelength (nm) F i g u r e 4. S o l a r r a d i a t i o n t h i c k e t (LAI = 10.7) .  quality  ( a t 50 cm) u n d e r a 5 - y e a r - o l d  salmonber  Table 4. V e r t i c a l measurements of Zeta ( r a t i o of energy at 660 and at 730 nm) w i t h i n salmonberry canopies of d i f f e r e n t ages (see F i g u r e s 2a through 2e f o r s p e c i f i c stand d a t a ) . canopy horizon (cm) above canopy 250 200 150 100 100 50  — s t a n d age  (years)—  2  3  5  1.06  1.07  1.06  .54 .32  .58 .26 .14  .65 .41  8 1.07 .50 .36 .20 .14 .14 .13  40 As c a n o p y l e a f a r e a i n c r e a s e d , t h e z e t a v a l u e s ? e x p o n e n t i a l l y ( r =0.88, A p p e n d i x 1 ) .  D. A n n u a l and h e r b i c i d e - i n d u c e d and g u a l i t y  under r e d a l d e r  changes i n l i g h t q u a n t i t y  canopies.  The a n n u a l c y c l e o f r a d i a t i o n  p e n e t r a t i o n below  and h e r b i c i d e - k i l l e d r e d a l d e r c a n o p i e s 5.  live  i s shown i n F i g u r e  The h e r b i c i d e - k i l l e d c a n o p y p r o v i d e d  relatively  reduction i n l i g h t throughout the year. provided  declined  The  live  constant  canopy  t h e same l e v e l o f s h a d e as h e r b i c i d e - k i l l e d  trees  f r o m November t h r o u g h M a r c h , b u t t h e d i f f e r e n c e i n l i g h t below t h e l i v e and dead c a n o p i e s  i n c r e a s e d w i t h the onset of  f l o w e r i n g and l e a f e x p a n s i o n i n A p r i l . was  The c u m u l a t i v e  light  s i m i l a r under t h e l i v e canopy f o r t h e days measured i n  March, A p r i l , stand July  a n d May,  although  increased over t h i s p e r i o d . and A u g u s t ) ,  had a l l o w e d those  above t h e  T h r o u g h t h e summer  (June,  l i g h t l e v e l s below t h e canopy remained  c l o s e t o t h e a n n u a l minimum.  By November, l e a f a b s c i s s i o n  l i g h t l e v e l s under t h e l i v e  canopy t o  equal  o f t h e dead canopy. The t i m e c o u r s e  i n j e c t i o n w i t h 2,4-D Figure  6.  occurred  of red alder d e f o l i a t i o n amine on May  f o r t h r e e weeks a f t e r t r e a t m e n t ;  penetration however,  leaf  n o t e d i n some c a s e s a f t e r  The c a n o p y t y p i c a l l y d e f o l i a t e d  months f o l l o w i n g  after  24, 1983 i s shown i n  No s i g n i f i c a n t c h a n g e i n l i g h t  c u r l i n g a n d some b r o w n i n g was week.  incident radiation  one  s l o w l y o v e r t h e two  the h e r b i c i d e treatment,  regardless of the  Treatment E222 Live canopy \Z3 Dead canopy CLJ No canopy  DEC  JAN  FEB  MAR  APR  MAY  JUN - JUL  AUG  SEP  OCT  NOV  F i g u r e 5. Mean m o n t h l y l i g h t (PPFD) i n t e n s i t y ( a t 50 cm) u n d e r l i v e , herbicide-defoliated r e d a l d e r s t a n d s (7 y e a r o l d , 8 m t a l l ) a n d i n a clearing. Mean m o n t h l y v a l u e s w i t h d i f f e r e n t l e t t e r s a r e s i g n i f i c a n t l y d i f f e r e n t (p<0 . 05) .  42  100 -i  80'  co  60-  C  CD  O  40  CD  CL  20  0 0  4  6  8  10  52  Time (weeks) F i g u r e 6. C h a n g e s i n t h e r e l a t i v e l i g h t (PPFD) i n t e n s i t y b e n e a t h a r e d a l d e r c a n o p y (7 y e a r o l d , 8 m t a l l ) f o l l o w i n g a herbicide application. P o i n t s s e p a r a t e d v e r t i c a l l y by more t h a n t h e v e r t i c a l b a r a r e s i g n i f i c a n t l y different (p<0.05).  43 season of treatment. application, treatment.  Except i n the case of a poor  t h e r e d a l d e r c a n o p y was  herbicide  l e a f l e s s a year a f t e r  B r e a k a g e o f b r a n c h e s and s u b s e q u e n t l y o f stems  r e s u l t e d i n t h e e l i m i n a t i o n of. t h e o v e r t o p p i n g d e a d woody canopy o v e r t h e f o l l o w i n g 3 6 months. F i g u r e 7 shows t h e s p e c t r a l e n e r g y d i s t r i b u t i o n l i g h t u n d e r f o l i a t e d and d e f o l i a t e d r e d a l d e r . h e r b i c i d e - d e f o l i a t e d canopy d i d not a l t e r t h e  The spectral  q u a l i t y o f energy t h a t p e n e t r a t e d below t h e canopy, a c t e d as a n e u t r a l d e n s i t y  filter  and r e d u c e d t h e  amount o f e n e r g y e q u a l l y a c r o s s t h e s p e c t r u m .  of  but  total  In contrast,  t h e f o l i a t e d c a n o p y s t r o n g l y d e p l e t e d e n e r g y i n t h e wavel e n g t h s b e l o w 740 nm,  e s p e c i a l l y a r o u n d 680 nm.  v a l u e s under the l i v e  r e d a l d e r w e r e 0.13  u n d e r t h e d e a d c a n o p y , a n d 1.13  The  zeta  compared w i t h  w i t h o u t a canopy.  1.19  100000^  10000-  E c E  1000CT.  ^3  100-  Legend  10300  A  No c a n o p y  X  Dead c a n o p y  •  Live c a n o p y T  400  500  600  700  800  900  Wavelength (nm) F i g u r e 7. S o l a r a l d e r canopy.  radiation  quality  ( a t 50 cm) u n d e r a 7 - y e a r - o l d  (8 m) r e d '  45 DISCUSSION  A.  Differences  i n c a n o p y s t r u c t u r e and  light  attenuation  w i t h i n s a l m o n b e r r y t h i c k e t s o f d i f f e r e n t ages As  the  occurred  salmonberry canopies developed, major  i n t h e v e r t i c a l d i s t r i b u t i o n and  a s s o c i a t e d shade.  area  index  of the  to increase  canopy i n c r e a s e d .  a t t e n u a t i o n w i t h depth i n the w i t h t h i c k e t age distribution,  q u a l i t y of  These m o d i f i c a t i o n s o f t h e  microenvironment continued  changes  light  as t h e t o t a l  The  the  rate of  leaf  light  salmonberry canopies v a r i e d  because of d i f f e r e n c e s i n l e a f  s p e c i f i c l e a f area,  l e a f o r i e n t a t i o n and  canopy s t r u c t u r e .  Canopy s t r u c t u r e Salmonberry canopies developed considerable very  r a p i d l y . T h e r e was  leaves  and  the pipe  model h y p o t h e s i s  i n the The  The  and  the  by  ( S h i n o z a k i et a l . , 1964a,b).  second  Leaf  year. (year  8)  i n which l e a f area  showed a index  was  d e c l i n e d w i t h each s u c c e s s i v e  Beer-Lambert e x t i n c t i o n c o e f f i c i e n t s  particularly  of  d i s p r o p o r t i o n a t e l y more t h a n s t e m b i o m a s s  o l d e s t canopy  distribution the top  development  s t e m s w i t h i n t h i c k e t s as w o u l d be p r e d i c t e d  biomass i n c r e a s e d only  a generally parallel  l e a f areas  i n the  8-year-old  vertical concentrated 50  cm  horizon.  suggest t h a t ,  canopy, l e a f o r i e n t a t i o n  dominant f a c t o r i n d e t e r m i n i n g  light  at  attenuation.  was  46 Blackman  (1962) h y p o t h e s i z e d t h a t  arrangement of steeply  base.  The  less  as  3).  the  e x c e p t i o n was than the  F  t h e r e was  and  l e a v e s at the  the  pattern  of  predicted  arrangement.  extinction  canopy s t r a t a d e c l i n e d  c o e f f i c i e n t of the  thicket  5-year-old thicket  greater moisture a v a i l a b i l i t y was  g r o w i n g , and  i n a different pattern  upper  l e a f area increased  3 - y e a r - o l d canopy.  5-year-old thicket  that  canopy,  coefficients  In g e n e r a l , the  resulted  of the  Blackman w o u l d have  p r o d u c t i v e canopy  Canopy e x t i n c t i o n  the  top  i n c l i n e d or h o r i z o n t a l  c o e f f i c i e n t s that  for a highly  greater K  efficient  8 - y e a r - o l d s a l m o n b e r r y c a n o p y had  extinction  The  most  l e a v e s f o r d r y - m a t t e r p r o d u c t i o n w o u l d have  i n c l i n e d l e a v e s at the  progressively  the  of  (Table  w h i c h had  a  It i s possible  that  at the  which  that  s i t e on  t h i s may  salmonberry growth  have on  site. The  addition  extinction  or the  stem a r e a t o t h e  c o e f f i c i e n t s reduced the  stratum of the influence  of  on  8-year-old thicket  the  extinction  (1970) f o u n d t h a t  c o e f f i c i e n t w i t h the  The  c a l c u l a t i o n of K  directly discernible  A  i n h a l f , but  had  8-year-old t h i c k e t .  the  addition  c o n s i d e r a b l y , d e p e n d i n g on  v a l u e s f o r the  c o e f f i c i e n t s i n other  upper h o r i z o n s of the  Blackman  calculation  the  reduction in of  stem a r e a  plant  of 50-100 little canopies Newton  extinction varied  species.  i l l u s t r a t e s how  factors  from biomass c l i p p i n g can  cm  not  strongly  and  47  influence of  light  attenuation.  In the winter, the path length  beam r a d i a t i o n t h r o u g h t h e c a n o p y g r e a t l y e x t e n d s t h e  shadow c a s t b y any o v e r t o p p i n g c a n o p y . leaves o f t e n remain  In salmonberry,  w i t h i n t h e canopy and c r e a t e a  l i g h t - o b s t r u c t i n g area that i s very d i f f i c u l t No a t t e m p t canopies  dead  to quantify.  was made t o q u a n t i f y d e a d l e a v e s w i t h i n t h e  i n t h e study p l o t s at the time of t h e w i n t e r  measurements.  light  I t was n o t e d t h a t s h a d i n g f r o m t h e d e a d  l e a v e s was g r e a t e s t i n t h e autumn a n d e a r l y w i n t e r , a n d t h a t this  s o u r c e o f s h a d i n g c a n be s i g n i f i c a n t w i t h i n an  e x t e n s i v e a r e a o f dense salmonberry s h o u l d a l s o be u s e d  thickets.  i n interpreting the K  l i g h t measurements used d a y s w i t h few c l o u d s .  v a l u e s , because  A  f o r t h e i r c a l c u l a t i o n w e r e t a k e n on IfK  A  v a l u e s had been c a l c u l a t e d w i t h  l i g h t measurements from days dominated t h a n d i r e c t beam r a d i a t i o n , c o e f f i c i e n t s would l i k e l y  Foliage  Caution  by d i f f u s e r a t h e r  the resultant  extinction  have been g r e a t l y  reduced.  characteristics  A reduced  extinction coefficient provides a greater  c a p a b i l i t y t o support  l a r g e r l e a f areas i n lower  canopy  strata.  S p e c i f i c l e a f a r e a s f r o m t h e 3- a n d 8 - y e a r - o l d  thickets  support t h i s  idea.  c o e f f i c i e n t s were r e l a t i v e l y increase i n s p e c i f i c (Table 3 ) .  Where u p p e r s t r a t a l o w , t h e r e was no  extinction significant  l e a f area i n the s t r a t a d i r e c t l y  below  48 Salmonberry  l e a v e s showed g r e a t p l a s t i c i t y  l e a f area i n response t o the d i f f e r e n t w i t h i n the canopies. (1980)  light  K a w a h a r a and T a d a k i  in specific  environments  (1978)  and  Araki  reported increased s p e c i f i c l e a f area w i t h depth i n a  number o f b r o a d l e a f c a n o p i e s .  The  degree  of l e a f  response  s h o u l d , h o w e v e r , d e p e n d on t h e s h a d e t o l e r a n c e o f t h e  plant  species. The specific  s e l f shading t h a t produced  the observed p a t t e r n  l e a f areas w i t h i n the salmonberry canopies  the growth  affects  o f t h e s a l m o n b e r r y as w e l l as t h e e n v i r o n m e n t  c o n i f e r s w i t h i n t h e canopy. and W a i s t e r  (1984)  S w a r t z e t a l . (1984)  studied light  of  and  for  Wright  i n t e r c e p t i o n i n commercial  Rubus s p e c i e s t h a t h a v e s i m i l a r a r c h i t e c t u r e t o  salmonberry.  Both papers  productivity  suggested t h a t s e l f shading reduces  i n r a p i d l y g r o w i n g Rubus Because  thickets.  o f t h e c o m p l e x i t y o f l e a f a n g l e s and  l e a v e s w i t h i n t h e s a l m o n b e r r y c a n o p i e s , no  folding  reliable  q u a n t i t a t i v e d a t a a r e a v a i l a b l e on l e a f a n g l e s .  It  o b s e r v e d t h a t b o t h t h e a n g l e o f t h e l e a f m i d - r i b and angle of the l e a f b l a d e from t h e m i d - r i b changed the growing season. shortly  Leaf angles appeared  a f t e r l e a f e x p a n s i o n was  heliotropism i n foliage  the  t o be s t e e p e s t  complete, but  fluctuated in  The p o s s i b i l i t y  i s r a r e l y mentioned  i n t h e l i t e r a t u r e on v a r i a t i o n  was  throughout  t h e l a t e summer and autumn, p o s s i b l y i n r e s p o n s e t o l o s s as s o i l m o i s t u r e d e c l i n e d .  of  turgor  of  i n discussions  i n canopy l e a f  inclination.  49 Monsi and S a e k i  (1953) s u g g e s t e d  t h a t t h e Beer-Lambert  extinction  c o e f f i c i e n t b a s e d on l e a f a r e a i n d e x i s c l o s e l y  correlated  w i t h t h e i n c l i n a t i o n o f l e a v e s i n t h e canopy.  Data from t h i s study support extinction  coefficient  t h e i r proposal that the  o f a c a n o p y c a n be a p p r o x i m a t e d  the c o s i n e o f t h e average l e a f angle.  by  This r e l a t i o n s h i p  may  be v a l u a b l e f o r f i e l d c o m p a r i s o n s o f u p p e r c a n o p y s t r a t a i n which leaves are g e n e r a l l y uniformly d i s t r i b u t e d approximately  t h e same s p e c i f i c l e a f  and a r e o f  area.  Canopy d y n a m i c s The  d i s t r i b u t i o n o f shade i n c a n o p i e s  can v a r y g r e a t l y  and change w i t h t i m e .  of similar  height  Consequently,  d e s c r i p t i o n s o f t h e r e l a t i v e canopy p o s i t i o n  of conifer  seedlings within  i n their  implications  conifer  canopies  may v a r y  f o r the s e e d l i n g ' s l i g h t environment.  i n t h e canopies conifers  deciduous  o f competing s p e c i e s surrounding  may be an u n d e r l y i n g a n d p e r s i s t e n t  Any  characterization  o f the m i c r o c l i m a t e beneath  canopies  from t h e t r a n s i t o r y  within and  t h e canopy, such  foliage  Tadaki,  as pigment c o n t e n t  characteristics  deciduous of conditions  (Sanger,  1971)  ( T a d a k i , 1966; K a w a h a r a a n d  1978).  Variation height,  nature  crop  problem w i t h  seedling-shrub competition indices.  suffers  Changes  i n height growth increment,  and l e a f area i n d e x a r e p r o b a b l y  the moisture  regime o f t h e s p e c i f i c s i t e .  maximum  closely Data  thicket  related to from  50  Henstrom  and L o g a n  (1986)  show t h a t  salmonberry  canopy  height growth i s c l e a r l y r e l a t e d t o ecosystem moisture.  The  g r e a t e s t h e i g h t and l e a f a r e a i n d e x o f s a l m o n b e r r y o c c u r r e d on t h e m o i s t  (subhygric to hygric)  sites.  A l e a f area index  o f 13  i s p r o b a b l y a b o u t t h e maximum f o r s a l m o n b e r r y .  meter  i s t h e t y p i c a l maximum s a l m o n b e r r y c a n o p y  drier  (subxeric)  sites.  additional  c o n t i n u e d t h e l e n g t h o f a r c h i n g canes t h e g r o w i n g t i p f u r t h e r above t h e  produce  and canopy  phenology  elevating  quality conditions, a i r  and s t r u c t u r e combine t o  a c o n s t a n t l y c h a n g i n g and c y c l i c  beneath deciduous canopies.  growth  ground.  i n l i g h t q u a n t i t y and  phenology  stem  rather than  I n t e r a c t i o n s of s o l a r angle, weather quality,  h e i g h t on  Canopy h e i g h t a p p e a r e d t o l e v e l o f f  e v e n t u a l l y at a l l s i t e s because  B. S e a s o n a l c h a n g e s  One  The  light  environment  extent t o which  c o n t r o l s l i g h t p e n e t r a t i o n was  plant  c l e a r i n both the  r e d a l d e r and s a l m o n b e r r y c a n o p i e s . Salmonberry on c o a s t a l s i t e s  regularly  i n Washington  p r e c o c i o u s development successful  foliates  e a r l i e r than red alder  and B r i t i s h C o l u m b i a .  o f s a l m o n b e r r y may  The  increase  f l o w e r i n g and a l l o w a r a p i d s t a r t t o  leaf  e x p a n s i o n when s a l m o n b e r r y o c c u r s , as i t d o e s commonly, i n the understory of deciduous t r e e s l i k e  red alder or b i g l e a f  maple.  P l a n t age, t h e s p e c i f i c s i t e ,  all  i n f l u e n c e the t i m i n g o f f o l i a g e development  may  d e l a y o r advance  t h e development  and weather  conditions and  o f c a n o p i e s by a c o u p l e  can  51 weeks a t t h e b e g i n n i n g  o f e a c h new g r o w i n g s e a s o n .  Annual  v a r i a t i o n i n the time of l i t t e r f a l l  i n r e d a l d e r was  r e p o r t e d b y Z a v i t k o v s k i a n d Newton  (1971).  Light  quantity The  and  lowest  light  i n t e n s i t y under b o t h t h e salmonberry  r e d a l d e r canopies  was d u r i n g t h e p e r i o d o f g r e a t e s t  i n c i d e n t r a d i a t i o n (summer s o l s t i c e ) .  This  coincidence of  minimum l i g h t p e n e t r a t i o n u n d e r d e c i d u o u s c a n o p i e s  at  maximum i n c i d e n t r a d i a t i o n h a s b e e n r e p o r t e d b y o t h e r s (Hutchison  a n d M a t t , 1977; Z a v i t k o v s k i , 1982) .  (1982) s u s p e c t s all  that this  deciduous canopies.  Zavitkovski  relationship generally applies to I t i s reasonable  that p l a n t phenology i s timed  to  hypothesize  t o a l l o w peak l e a f  area  development, o r f o l i a g e c h a r a c t e r i s t i c s t h a t maximize interception of light, support  a t a t i m e when t h e e n v i r o n m e n t c a n  t h e g r e a t e s t amount o f f o l i a g e .  The  loss of leaves  i n t h e autumn i n b o t h t h e  salmonberry and r e d a l d e r canopies in  s o l a r angle,  light was  was o f f s e t b y t h e d e c l i n e  with the result that the t o t a l  amount o f  r e a c h i n g t h e ground beneath l i v e deciduous  s i m i l a r i n t h e summer a n d e a r l y w i n t e r  Slight  leaf  increases  canopies  ( F i g s 3 and 5 ) .  i n l i g h t p e n e t r a t i o n i n August and  September c o u l d have r e s u l t e d from e a r l y l e a f  fall  defoliation.  i n c r e a s e d and  During  many o f t h e l e a v e s  that period, l i t t e r  contained  holes,  fall  suggesting  or insect  t h a t they had  52 b e e n f e d on by t h e a l d e r f l e a b e e t l e ( A l t i c a LeConte) or o t h e r i n s e c t s . allowed l i g h t  ambiens  By November, l e a f a b s c i s s i o n  l e v e l s u n d e r t h e l i v e r e d a l d e r canopy t o  e q u a l t h o s e o f t h e dead canopy. u s u a l l y not complete  Winter d e f o l i a t i o n  i n red alder at the study  a t t a c h e d t o t h e stem t i p s However, t h e s e few  u n t i l the f o l l o w i n g  leaves produced  to the red alder  little  was  location;  o f t e n t h e uppermost l e a v e s of the canopy remained  comparison  had  green  and  spring.  shade i n  stems.  S e a s o n a l c y c l e s i n l i g h t p e n e t r a t i o n were a l s o e v i d e n t in leafless  canopies through the e f f e c t  solar angle.  As  of the  solar elevation declines,  changing  the o p t i c a l  path  l e n g t h t h r o u g h t h e s t a n d i n c r e a s e s and e x c l u d e s a g r e a t e r p r o p o r t i o n o f beam r a d i a t i o n .  At w i n t e r s o l s t i c e ,  the  r e a c h i n g t h e f l o o r o f most d e c i d u o u s  stands i s dominated  diffuse radiation  The  (Anderson,  1964).  c y c l e o f l i g h t under deciduous n o t o n l y on t o t a l modifications.  i s less l i k e l y  distribution  1976;  1977).  Holmes and S m i t h ,  t o have  (Holmes and  shown i n F i g u r e s 3 and 5 a r e n o t  representative c h a r a c t e r i z a t i o n of the annual environment  limits  r a d i a t i o n , but the e x t e n t of l i g h t  Diffuse light  by  seasonal  canopies prescribes  a l t e r e d s p e c t r a l energy  Averages  resulting  light  quality an  McCartney,  a light  w i t h i n t h o s e c a n o p i e s b e c a u s e m e a s u r e m e n t s were  o n l y t a k e n on s e l e c t e d r a i n l e s s d a y s .  However, t h e  average  i n c o m i n g l i g h t d u r i n g t h e d a y s i n w h i c h m e a s u r e m e n t s were  53 t a k e n were s i m i l a r t o t h o s e m e a s u r e d a t n e a r l y t h e latitude  (45°  33')  Both stand e f f e c t on light  i n W i s c o n s i n by  density  and  Zavitkovski  canopy h e i g h t  light penetration.  Few  data are  (1982). have a  Graham, i n p r e p a r a t i o n ) .  (1976), w o r k i n g w i t h h y b r i d p o p l a r ,  available  l e s s important i n determining  extensive  suggested that  i n t e r e s t i n the  density plantings  (Atkinson w i t h i n low density  light transmission  density  Studies  the  light  red a l d e r stands would help  guidelines  There i s use  of  augmentation  of seasonal  trends  provide  f o r mixed red a l d e r - c o n i f e r p l a n t a t i o n s . directly  i n f l u e n c e s the  l e n g t h y e a r a r o u n d , a l t h o u g h s t u d i e s by (1984) show t h a t t h e  d i f f u s e r a d i a t i o n at t i m e s of the They r e p o r t e d  Baldocchi  that  i n the  path et a l .  s o l a r e l e v a t i o n on beam r a d i a t i o n .  stand,  62 p e r c e n t o f  i s s u f f i c i e n t to counter the  of  angle i s  for a l e a f l e s s oak-hickory and  as  proportion  y e a r when t h e  d i f f u s e r a d i a t i o n c o m p r i s e s b e t w e e n 35 r a d i a t i o n and  optical  importance of s o l a r angle diminishes  angle d e c l i n e s because of increases  total  in  P a c i f i c Northwest i n the  of red alder for s o i l  et a l . , 1979).  Stand height  small.  density  growth of l a t e r a l branches i n hardwoods.  considerable  the  on  Z a v i t k o v s k i et a l .  hardwood s t a n d s t h a n i n c o n i f e r s t a n d s because o f  low  strong  l e v e l s under r e d a l d e r stands of d i f f e r e n t d e n s i t i e s  ( B i g l e y and  is  can  same  effect  the of  54  Light  quality The  s p e c t r a l d i s t r i b u t i o n s o f l i g h t measured under  the salmonberry  and r e d a l d e r  f o l i a t e d c a n o p i e s were  t o t h o s e measured under a v a r i e t y canopies al.,  of other  both  similar  deciduous  ( F e d e r e r a n d T a n n e r , 1966; Freyman, 1968; F l o y d e t  1978; B j o r k m a n a n d L u d l o w , 1972) a n d t o l i g h t  t r a n s m i s s i o n through species taken  (Loomis,  individual  leaves of broad-leaved  1965; H o r n , 1 9 7 1 ) .  tree  These m e a s u r e m e n t s were  i n l a t e summer a n d p r o b a b l y r e p r e s e n t t h e maximum  extent of selective absorption of l i g h t within the canopies. Because t h e s p e c t r a l d i s t r i b u t i o n o f l i g h t p e n e t r a t i n g t h e canopy i s s e n s i t i v e t o t h e pigment c o n t e n t w i t h i n t h e foliage,  t h e time course o f l i g h t  a t t e n u a t i o n changes i n a  l e a f i n g canopy i s p r o b a b l y l o n g e r f o r l i g h t q u a l i t y t h a n f o r quantity.  Sanger  (1971) i l l u s t r a t e d how t h e p i g m e n t  o f l e a v e s may n o t r e a c h a maximum u n t i l growth  has concluded.  extended  after leaf  content  area  I t i s possible that the resulting  period of higher zeta values i s important i n the  morphogenic response  of plants developing foliage  deciduous  Tasker  canopies.  and Smith  beneath  (1977) f o u n d t h a t z e t a  c h a n g e s commonly t a k e p l a c e i n d e p e n d e n t l y o f c h a n g e s i n intensity of light  i n several broad-leaved  forests.  Floyd  e t a l . (1978) f o u n d t h a t t h e r a t i o o f s p e c t r a l e n e r g y o f light  a t 450 and a t 625 nm t o l i g h t  i n c r e a s e d as f o l i a g e d e v e l o p e d oak  a t 550 nm  (green)  i n t h e s p r i n g under a mixed  and y e l l o w p o p l a r canopy. Autumn l e a f s e n e s c e n c e  often involves the d i f f e r e n t i a l  55 l o s s of pigments.  Federer  and  Tanner  (1966) f o u n d t h a t  t h e y e l l o w r e g i o n o f t h e s p e c t r u m was senescing  sugar maple.  s p r i n g and  again  perhaps without  l e a f p i g m e n t s change i n t h e  a m e a s u r a b l e e f f e c t on t o t a l  most f a l l  m a p l e and  When r e d a l d e r and as g r e e n l i t t e r .  filter  light  salmonberry  quantity leaves vine  i n young c o n i f e r  p l a n t a t i o n s i n t h e P a c i f i c N o r t h w e s t and p e r i o d where a c c e s s o r y  quality,  However, b o t h  b i g l e a f maple o c c u r w i d e l y  selectively  under  i n t h e autumn, so d o e s l i g h t  w i t h i n the canopy. senesce,  Thus, as  altered  only  have a s e n e s c e n c e  pigments dominate the  l i g h t to the understory  foliage  and  for a  considerable period. H o l m e s and M c C a r t n e y  (197 6)  r e l a t i o n s h i p b e t w e e n z e t a and fairly  f o u n d a good e x p o n e n t i a l  l e a f area  s t a b l e w i t h i n the lower  index.  Z e t a became  canopy h o r i z o n s  during  p e r i o d s when r a d i a t i o n i n t h e p h o t o s y n t h e t i c a l l y a c t i v e region continued suggested had  to decline.  Holmes and  t h a t i n canopy s t r a t a  begun, c h l o r o p h y l l content  In salmonberry,  w o u l d be  and  reduced  likely  i n most  ability  and  to modify t r a n s m i t t e d l i g h t .  coefficients  thus Low  i n t h e u p p e r c a n o p y s t r a t a may  maintenance of high zeta values  and  light canopies  shade-acclimated  l e a v e s a t t h e base of t h e canopy w h i c h have h i g h e r lower pigment c o n t e n t s  leaves  and  of p e n e t r a t i n g  with large l i g h t gradients, there exist  l e a f areas,  (1976)  i n which senesence of  m o d i f i c a t i o n of the s p e c t r a l q u a l i t y would d e c l i n e .  McCartney  a  specific  diminished  extinction a i d i n the  a favorable  light  56 environment to support sun-acclimated  leaves  lower i n  the  canopy.  Sunfleeks Sun  flecks l i k e l y play  physiology  an  important r o l e i n  of c o n i f e r seedlings  w i t h i n canopies of  p l a n t s t h r o u g h t h e i r e f f e c t s on b o t h l i g h t quantity.  Light  the deciduous  quality  and  l e v e l s i n deep s h a d e u n d e r e i t h e r  s a l m o n b e r r y o r r e d a l d e r c a n o p i e s w e r e commonly f o u n d t o b e t w e e n 0.5  and  3%  of f u l l  sun.  t h a t under a h y b r i d p o p l a r be  as  low  as  0.18%  of the  Zavitkovski  stand,  open s u n .  deciduous shrubs i s not  subjected  continuously,  Integrated  however.  the  (1982)  reported  a v e r a g e i n t e n s i t y can The  understory  t o s u c h low values  beneath  light  of l i g h t  over  d a y l i g h t h o u r s u n d e r f o l i a t e d r e d a l d e r and  salmonberry  c a n o p i e s o f t e n a p p r o a c h e d 10%  The  sunfleck sun;  light  others  o f 31%  of f u l l  for poplar  average s u n f l e c k  plantations  mixed hardwood f o r e s t  (Allard,  1 9 4 7 ) , and  89%  of the  poplar  (1982) f o u n d t h a t  42%  of  light  20%  Ludlow,  sunflecks  the  average full  intensities  ( Z a v i t k o v s k i , 1 9 8 2 ) , 46%  Q u e e n s l a n d r a i n f o r e s t ( B j o r k m a n and Zavitkovski  sun.  i n t e n s i t y u n d e r r e d a l d e r was  have r e p o r t e d  be  in a  in a  1972).  contributed  66  to  t o t a l p h o t o s y n t h e t i c a l l y a c t i v e r a d i a t i o n under  stands.  m e a s u r e m e n t s and  The  comparison of i n t e g r a t e d  light  measurements o f shade a v o i d i n g  u n d e r b o t h r e d a l d e r and  sun  salmonberry a l s o support  statement t h a t the m a j o r i t y  of l i g h t  flecks the  i n c i d e n t a t 50  cm  is  57 p r o v i d e d by sun  flecks.  Utilization s e e d l i n g s may intermittent 1969;  o f s u n f l e c k s by o v e r t o p p e d  be h i g h as d e m o n s t r a t e d light  Sierzbicki,  conifer  by s t u d i e s  of  on p h o t o s y n t h e s i s (McCree a n d 1980).  Sun  Loomis,  flecks also provide light  more b a l a n c e d s p e c t r a l q u a l i t y t o t h e l o w e r c a n o p y . and S m i t h  t h o u g h t t o have o n l y minute  1980;  Holmes  (1977) f o u n d t h a t s u n f l e c k s w i t h i n a wheat c a n o p y  had d e c r e a s e d z e t a v a l u e s , but s u n f l e c k s a r e  (Horn,  of a  1971;  o r no  B j o r k m a n and Ludlow,  and G r o s s ,  1982).  The  shifts 1972;  generally  in spectral S m i t h and  quality  Geller,  r a p i d movement o f s u n f l e c k s  (due t o d i s t u r b a n c e o f t h e c a n o p y by w i n d ) may  average  spectral variation  diffraction  through the  C.  i n sunflecks resulting  from  any  canopy.  H e r b i c i d e - i n d u c e d changes i n l i g h t q u a n t i t y and  quality  I n i t i a l m o d i f i c a t i o n s i n t h e c a n o p y o f r e d a l d e r due  to  h e r b i c i d e t r e a t m e n t s were s i m i l a r t o t h o s e t h a t o c c u r d u r i n g autumn s e n e s c e n c e . was  Following defoliation,  a second phase i n w h i c h canopy d i s i n t e g r a t i o n l e d t o t h e  e l i m i n a t i o n o f a l l canopy s h a d i n g .  The  d e f o l i a t i o n of red  alder s t a r t e d p r e d i c t a b l y w i t h i n the f i r s t herbicide application, The of  light  regime  the treatment.  month a f t e r  although the d e f o l i a t i o n  rate  f o l l o w i n g t r e a t m e n t d e p e n d e d on t h e Treatments  experienced higher l i g h t of  however, t h e r e  e a r l y i n the growing  the  varied. timing  season  at t h e base o f t h e canopy because  the higher s o l a r angle at the time of  defoliation.  58 The  second phase  material) killing,  o f response  may v a r y c o n s i d e r a b l y  (the downing  i n duration.  o f woody Method o f  age a n d f o r m o f t h e p l a n t , r o o t i n g s u b s t r a t e ,  type  o f wood d e c a y a g e n t s a c t i n g on t h e wood, a n d e x p o s u r e t o t h e weather  a l l may i n f l u e n c e t h e r a t e a t w h i c h b r a n c h e s a n d  b o l e s a r e removed f r o m t h e c a n o p y . Stem g i r d l i n g may p r o v e t o be a p l a u s i b l e means o f canopy  removal w i t h m i c r o c l i m a t e m o d i f i c a t i o n s  those which h e r b i c i d e s  i n d u c e . However, my o b s e r v a t i o n s  s u g g e s t t h a t t h e t i m e c o u r s e o f d e f o l i a t i o n and break-up w i l l  likely  similar to  canopy  be l e n g t h e n e d b y s t e m g i r d l i n g ,  because  o f slow d e p l e t i o n o f s t e m - s t o r e d m o i s t u r e and c a r b o h y d r a t e s , and t h e p o s s i b i l i t y  of incomplete severing  of the conducting  tissue. H e r b i c i d e - k i l l i n g o f salmonberry t h i c k e t s a l s o has a period the  a f t e r d e f o l i a t i o n where t h e stems decay and f a l l  canopy.  Observations of herbicide-treated  t h i c k e t s suggest t h a t  salmonberry  s t e m s may r e m a i n i n p l a c e f o r s e v e r a l  years following d e f o l i a t i o n . canopy  N o n - f o l i a r components o f t h e  have n o t been f o u n d t o m o d i f y t h e s p e c t r a l  distribution of light penetrating  canopies.  These  d e f o l i a t e d c a n o p i e s s h o u l d have l i t t l e  i n f l u e n c e on t h e  l i g h t environment  limited neutral  density  shading.  from  other than providing  59  CONCLUSIONS  1. varies  Light  throughout  composition, plant  red alder  the year  and t h i s  and salmonberry  i n both  variation  intensity  i s strongly  canopies  and  spectral  controlled  by  phenology. 2.  Modifications  salmonberry from  beneath  year 3.  canopies  i n the light  environment  are accentuated  within  as t h e canopy  grows  t o year.  In salmonberry,  attenuation  well  while  defoliated,  using leaf  t h e Beer-Lambert  law d e s c r i b e s  t h e canopy  i s foliated  area  and stem  index  light  and  area  index,  respectively. 4. whole,  The Beer-Lambert poorly  conifer  5. as  caused few  characteristics  while  growing  a  up t h r o u g h  other than of leaf  i n describing  surface  area,  a  orientation, light  such  are  attenuation i n  thickets.  Changes  i n the light  by h e r b i c i d e  months  long.  encounter  t o be i m p o r t a n t  salmonberry 6.  would  t h i c k n e s s and t h e angle  believed  as a  canopy.  Leaf  leaf  t o t h e canopy  d e s c r i b e s the s u c c e s s i o n o f environments  seedling  salmonberry  law, a p p l i e d  b u t may  treatments have  a time  environment occur course  under  rapidly  red alder  i n the  up t o s e v e r a l  first years  7. total  Sun f l e c k s make an i m p o r t a n t  light  and t h e y  tool  for  may h e l p t o b a l a n c e l i g h t  the  study  changing l e v e l s  of  quality  within  the  studied.  Herbicides provide the  to  e n e r g y r e c e i v e d by s e e d l i n g s b e n e a t h a c a n o p y ,  deciduous canopies 8.  contribution  of  a valuable,  but  canopy a r c h i t e c t u r e  defoliation.  seldomly by  used  providing  61  CHAPTER 3 PHYSIOLOGY AND GROWTH OF SEEDLINGS OF THREE CONIFER SPECIES UNDER DIFFERENT DENSITIES OF DECIDUOUS  COMPETITORS  INTRODUCTION The sites  establishment  of conifer seedlings  i n t h e P a c i f i c Northwest o f t e n  includes  s h a d i n g by d e c i d u o u s shrubs o r t r e e s . those deciduous species growth and i n c r e a s e d  on  early mortality of conifer  or d e s i r a b l e  seedlings.  competitors  may  (e.g. i n r i p a r i a n  Some d e c i d u o u s c a n o p y e n c r o a c h m e n t i s u s u a l l y  inevitable despite competition  various  strategies t o avoid  (e.g. s i t e preparation  large planting The  from  i s a major cause o f reduced e a r l y  be p o s s i b l e , p r a c t i c a l ,  zones).  a period of  Competition  However, c o m p l e t e r e m o v a l o f t h e o v e r t o p p i n g not  productive  such  and prompt p l a n t i n g o f  stock).  c o n c e p t o f shade t o l e r a n c e  provides  the basis f o r  an u n d e r s t a n d i n g o f c o n i f e r g r o w t h i n d i f f e r e n t l i g h t environments. have g r e a t e r  By d e f i n i t i o n ,  e a r l y work i n t h i s  Krueger, Continual  conifers  should  s u r v i v a l and growth under t h e c a n o p i e s o f other  plants than l e s s shade-tolerant  conditions  shade-tolerant  p l a n t s have.  Much o f t h e  f i e l d was c o n d u c t e d u n d e r u n v a r y i n g  light  t h a t do n o t r e f l e c t n a t u r a l c o n d i t i o n s ( e . g .  1967; L o g a n , 1969; M a g n u s s e n a n d P e s c h l , shade and n e u t r a l d e n s i t y  filtering  1981).  a r e more  62 i n d i c a t i v e of i n t a c t c o n i f e r o u s canopies than of the environments  c r e a t e d by d e c i d u o u s  D u n l a p and Helms on t h e g r o w t h growth  shrubs or  trees.  (1983) r e v i e w e d t h e e f f e c t s o f s h a d e  o f p l a n t e d s t o c k , and c o n c l u d e d t h a t  r e l a t i o n s h i p s between t r e e s of d i f f e r e n t  tolerance i n f i e l d  light  the  relative  s i t u a t i o n s are p o o r l y understood.  (1957) f o u n d t h e t e n y e a r s u r v i v a l o f b o t h t h e s h a d e i n t o l e r a n t D o u g l a s - f i r and  Ruth  relatively  shade-tolerant western  h e m l o c k t o be o n l y 17% u n d e r deep c o n i f e r o u s s h a d e . Newton and W h i t e  (1983) f o u n d t h a t w e s t e r n h e m l o c k s e e d l i n g s  p l a n t e d under salmonberry s u r v i v a l and g r o w t h .  canopies performed  poorly i n both  However, s h a d e t o l e r a n c e r e m a i n s  s i n g l e best guide to p r e d i c t i n g the l i k e l i h o o d s u p p r e s s i o n i n shade. grand  f i r might  of  P e r r y e t a l . (1985) s u g g e s t e d  that  be a g o o d c a n d i d a t e f o r p l a n t i n g i n  p r e e x i s t i n g c a n o p i e s b e c a u s e i t i s shade t o l e r a n t appeared  the  n o t t o be s e r i o u s l y damaged by  and  animals.  Shade t o l e r a n t s p e c i e s h a v e g r e a t e r p h o t o s y n t h e t i c efficiently growth  a t low l i g h t  i n t e n s i t y and g e n e r a l l y have h i g h e r  r a t e s i n s h a d e as c o m p a r e d t o s h a d e  species  (Armitage and V i n e s , 1982).  under deciduous changes,  intolerant  However, t h e  light  canopies i s s u b j e c t t o wide s e a s o n a l  and p h y s i o l o g i c a l d i f f e r e n c e s b e t w e e n p l a n t s  by d e c i d u o u s  c a n o p i e s and t h o s e not shaded  seasonally.  Halas  may  shaded  change  (1971) f o u n d t h a t t h e w i n t e r  photosynthetic a c t i v i t y  o f shaded  p l a n t s grown u n d e r h i g h l i g h t .  He  plants declined less  than  concluded that the  shaded  63 p l a n t s had  a more f a v o r a b l e g r o w i n g c o n d i t i o n w i t h  incidence of f r o s t ,  s m a l l e r a i r t e m p e r a t u r e f l u c t u a t i o n s and  reduced a i r vapor pressure  deficits.  F r y and  (1977) f o u n d c o n s i d e r a b l e p h o t o s y n t h e t i c fir  and  Helms  in  i n grand  southern  (1963) r e p o r t e d t h a t D o u g l a s - f i r i n  W a s h i n g t o n s t a t e was  capable  t h e w i n t e r when a p p r o p r i a t e The  Phillips  activity  w e s t e r n hemlock t h r o u g h o u t t h e year  England.  reduced  o b j e c t i v e of the  of high photosynthetic climatic conditions  studies presented  i s t o compare t h e g r o w t h and  seasonal  rates i n  occurred.  in this  patterns  chapter  of c e r t a i n  p h y s i o l o g i c a l parameters between c o n i f e r s e e d l i n g s  of  different  of  shade t o l e r a n c e under d e c i d u o u s c a n o p i e s  different density that photosynthesis  (relative shading). i s c a r r i e d out  year  c o a s t a l P a c i f i c Northwest, i t i s l i k e l y light  Since  i t i s known  around i n the that increases  i n t e n s i t y a f t e r autumn l e a f d r o p c o u l d be  c o n i f e r s o v e r t o p p e d by d e c i d u o u s c a n o p i e s . hypothesized  utilized  have  r a t e s t h a n shade i n t o l e r a n t t r e e  s e e d l i n g s during the periods t h a t deciduous competitors foliated,  but  t h a t the d i f f e r e n c e between s e e d l i n g s  different tolerance w i l l competitors I f the  are  by  It is  t h a t shade t o l e r a n t t r e e s e e d l i n g s w i l l  greater photosynthetic  in  d i m i n i s h during the periods  are  of that  leafless.  concept of shade t o l e r a n c e p r o v i d e s  f o r s e e d l i n g growth under deciduous canopies  a good model  i n the  Pacific  N o r t h w e s t , t h e n s e e d l i n g growth under i n c r e a s i n g canopy density  should  d e c l i n e to the greatest extent  i n seedlings  o f t h e l o w e s t shade t o l e r a n c e . growth r a t e s o f seedlings salmonberry  under deciduous  and r e d a l d e r w i l l  d e c r e a s i n g shade t o l e r a n c e  I t i s hypothesized  decrease  canopies  that of  i n order of  as c a n o p y d e n s i t y  increases.  65 METHODS Field  Plot  treatments  establishment P l o t s were e s t a b l i s h e d i n the  l o c a t i o n s B and by  7-year-old  with high, by  s i t e s d o m i n a t e d by  red alder, r e s p e c t i v e l y . low  c a n o p i e s and  of f u l l  a t t a i n e d by  sun.  full  sun  soil  at s e e d l i n g  reached s e e d l i n g  removed and  level.  Fifteen seedlings g r a n d f i r and  two  t y p e i n d i c a t e d i n T a b l e 5.  to r e s t r i c t seedlings  (50  were p l a n t e d  The  t o 20  cm full  period.  (western hemlock, w i t h i n each of  p l o t s of each d e n s i t y . w i t h the  Screen e x c l o s u r e s  of each s p e c i e s  a n i m a l damage and  seedling were  three  Planting stock  placed  w i t h i n each treatment  assure a s u f f i c i e n t  number o f  w i t h o u t damaged f o l i a g e f o r t h e p h y s i o l o g i c a l  measurements.  25  cm).  a b o u t 90%  y e a r measurement  of each species  rectangular  seedlings  was  average of  level  received  c o n d u c t e d i n e a r l y M a r c h o f 1982  around ten  an  levels  These c a n o p y d e n s i t i e s w e r e  Douglas-fir)  40 m'  had  growing-season average l i g h t  maintained throughout the  was  density plots  a l l p l a n t b i o m a s s a b o v e 10  surface  plots  established  A c a n o p y o f medium d e n s i t y  d e n s i t y p l o t s had  replicate  high  and  At b o t h s i t e s ,  removal of whole p l a n t s u n t i l  t o 40 p e r c e n t  from the  The  at  salmonberry  canopy d e n s i t y were  manual c l i p p i n g / c u t t i n g .  o f 2-10%  sun  the  medium, and  undisturbed  low  C,  s p r i n g o f 1982  66  T a b l e 5. P l a n t i n g s t o c k e s t a b l i s h e d w i t h i n s a l m o n b e r r y red a l d e r stands. Seed s o u r c e Species Seedlot" e l e v a t i o n (m) Stock type Nursery Douglas -fir  and  2891  175  2 + 0 BR  Green Timbers  G r a n d f i r 2899  111  2+1  BR  Chilliwack  Western hemlock  340  1+1  PBR  Surrey  3906  B r i t i s h Columbia M i n i s t r y of F o r e s t s , F o r e s t S e r v i c e identification.  67 F i e l d Measurements Schedule  o f measurements  All  measurements o f t r e e p h y s i o l o g y were r e p e a t e d a t  four d i f f e r e n t times of the year.  Two m e a s u r e m e n t s were  c o n d u c t e d when t h e o v e r t o p p i n g c a n o p i e s w e r e f o l i a t e d and A u g u s t ,  1984),  a n d two when t h e c a n o p i e s were  (November, 1983 a n d F e b r u a r y ,  (June  defoliated  1984) .  P h o t o s y n t h e t i c a l l y a c t i v e r a d i a t i o n and vapor  pressure  deficits All  measurements o f l i g h t  i n Chapter radiation  4 a r e i n micromoles (PPFD).  r e p o r t e d i n t h i s Chapter and of photosynthetically  active  Light levels taken during the  p h o t o s y n t h e t i c d e t e r m i n a t i o n s were measured by p l a c i n g a quantum s e n s o r  (LI-COR L I - 1 9 0 S ) a l o n g s i d e t h e s a m p l e chamber  o f t h e i n s t r u m e n t used t o measure p h o t o s y n t h e t i c r a t e s ( d e s c r i b e d below) and r e c o r d i n g a s i n g l e value.  instantaneous  To c h a r a c t e r i z e t h e s h a d i n g o f s p e c i f i c t r e a t m e n t s ,  i n c o m i n g r a d i a t i o n was i n t e g r a t e d u s i n g t h e c h e m i c a l (anthracene) procedure d e s c r i b e d i n Chapter  2.  Vapor  p r e s s u r e d e f i c i t s were c a l c u l a t e d f r o m m e a s u r e m e n t s t a k e n w i t h a thermocouple  psychrometer  at t h e time of the  p h o t o s y n t h e t i c measurements.  Photosynthesis P h o t o s y n t h e t i c r a t e s were measured u s i n g t h e ^C02 1  method d e s c r i b e d by S h i m s h i  (1969) a n d N e i l s o n ( 1 9 7 7 ) .  68 M o d i f i c a t i o n s t o t h e . o r i g i n a l gas e x p o s u r e  apparatus  d e s c r i b e d by P r i c e e t a l . (1986) w e r e u s e d . A l l p h o t o s y n t h e t i c measurements f o r a s p e c i f i c t r e a t m e n t were r e p l i c a t e d f i v e t i m e s u s i n g n e e d l e p a i r s t h a t were f r o m f i v e measurement t r e e s  (one d e t e r m i n a t i o n p e r t r e e )  i m m e d i a t e l y b e f o r e measurement.  To p r e p a r e f o r a  measurement, s e v e r a l n e e d l e s were c a r e f u l l y middle s e c t i o n  excised  removed from t h e  ( t o r e d u c e v a r i a t i o n i n n e e d l e s i z e and  maturity) of a twig,  and d i v i d e d i n t o  sets f o r conductance  measurements, p h o t o s y n t h e t i c measurements, and t h e measurement o f l e a f w i d t h . To d e t e r m i n e p h o t o s y n t h e t i c r a t e s , p a i r s o f n e e d l e s w e r e s e a l e d i n a 300 mm  J  c o n t a i n i n g 323 ppm and 78% N  2  1 2  C0 2  chamber, a n d e x p o s e d t o a i r 1 4  C0  2  (6.19 u C i  ( a n d .95% A) f o r 20 s e c .  -  1 1 4  C0 ),  20.8%  2  0 , 2  Gas f l o w r a t e s o f 1.40  m l ' s ^ t h r o u g h t h e chamber were c a l i b r a t e d a t t h e b e g i n n i n g -  of  each measurement  series at a s i t e .  Immediately a f t e r the  e x p o s u r e p e r i o d , t h e n e e d l e s were r e m o v e d f r o m t h e chamber and a 7 mm  segment f r o m t h e e x p o s e d  s e c t i o n o f each needle  was c u t w i t h a p a p e r p u n c h and s e a l e d i n a 20 mL scintillation  vial  c o n t a i n i n g 2 mL t i s s u e  glass  solubilizer  (NCS,  Amersham C o r p . ) . W i t h i n two weeks o f c o l l e c t i o n , scintillation  counting.  samples  were p r e p a r e d  for  liquid  In order to s o l u b i l i z e  the  l e a f t i s s u e and reduce c o l o r q u e n c h i n g , t i s s u e  digestion  (12-48 h a t 50 ° C ) , f o l l o w e d by b l e a c h i n g w i t h 0.5-1 mL hydrogen  p e r o x i d e f o r a 24 h p e r i o d a t 50 °C w e r e  6%  required.  69 Some s a m p l e s r e q u i r e d an a d d i t i o n a l 0.5 peroxide  and  quenching.  warming  cocktail  monoethyl ether,  efficiencies foliage  Leaf d i f f u s i v e  to control excessive a l i q u o t of  parts; ethyleneglycol ( S p e c t a f l u o r , Amersham  added t o each v i a l . scintillation  a v e r a g e d 82%.  18 mL  Radioassy  was  spectrometer.  C a l c u l a t i o n of  CO2  f o l l o w e d T i e s z e n e t a l . (1974) .  r e s i s t a n c e porometer  (LI-COR 700)  on medium  used t o measure l e a f d i f f u s i v e c o n d u c t a n c e .  conductance values presented determinations continuous  then  conductance  A diffusive c y c l e was  of hydrogen  c o m p l e t e , an  ( t o l u e n e , 100  conducted using a l i q u i d  u p t a k e by  °C)  40 p a r t s ; POPOP-PPO  6 p a r t s ) was  Counting  h a t 50  Once b l e a c h i n g was  scintillation  Corp.),  (6-12  mL  are the average of  using detached needles.  three  In order t o assure  l e a f s u r f a c e area over the a p e r t u r e  to  tape,  then  were  the  needles  b a c k e d by t h e t a p e w e r e p l a c e d so t h a t t h e n e e d l e s p e r p e n d i c u l a r t o t h e measurement o p e n i n g . measurements were c o n c u r r e n t  w i t h the  a  the  measurement chamber, t h r e e t o f i v e c o n i f e r n e e d l e s p l a c e d s i d e - b y - s i d e on c e l l o p h a n e  The  laid  These  photosynthetic  determinations.  Leaf water p o t e n t i a l s L e a f w a t e r p o t e n t i a l s were t a k e n on  before  0900 t o 1000  f o l i a g e from s e e d l i n g s u s i n g the p s y c h c r o m e t r i c  (Wescor Dew  point microvoltmeter  m o d e l HR-33 and  method  sample  hr  70 chamber C - 5 1 ) .  Because  were t i m e consuming,  l e a f water p o t e n t i a l  measurements  a l l measurements were t a k e n t h e day  b e f o r e p h o t o s y n t h e t i c and l e a f conductance measurements.  A  s i n g l e l e a f w a t e r p o t e n t i a l measurement was made f r o m t h r e e o f t h e f i v e measurement t r e e s u s e d i n f o r t h e p h o t o s y n t h e t i c measurements.  C h l o r o p h y l l content i n f o l i a g e C h l o r o p h y l l content o f c u r r e n t year f o l i a g e o f each t r e e s p e c i e s i n e a c h t r e a t m e n t was d e t e r m i n e d . each o f t h r e e sample  s e e d l i n g s i n e a c h p l o t was t a k e n  t h e t o p t h i r d o f t h e crown extraction  a n d s t o r e d a t 5 °C  (storage u s u a l l y  t h r e e sample  A twig  3-5 d a y s ) .  from  until  F o l i a g e samples  s e e d l i n g s p e r p l o t were e x t r a c t e d ,  were a v e r a g e d f o r each p l o t .  from  from  and t h e d a t a  C h l o r o p h y l l was e x t r a c t e d i n  a c e t o n e and p e t r o l e u m e t h e r u s i n g t h e method d e s c r i b e d by Smith and B e n i t e z (1955).  Pigment  a b s o r b e n c i e s were  determined using a spectrophotometer. c o n t e n t was e x p r e s s e d on a f r e s h w e i g h t  Growth  (a+b)  basis.  analysis  Growth  a n a l y s i s was c o n d u c t e d on s e e d l i n g s w i t h i n  w h i c h were d e s t r u c t i v e l y Foliage  Chlorophyll  sampled  plots  i n O c t o b e r o f 1984.  f r o m s i x s e e d l i n g s f r o m e a c h p l o t was p a r t i t i o n e d by  a n n u a l age c l a s s .  Stems a n d w a s h e d r o o t s were d r i e d a t 65°C  f o r 120 h o u r s a n d f o l i a g e dry weight.  f o r 48 h o u r s b e f o r e d e t e r m i n i n g  The r e l a t i v e component g r o w t h r a t e s  were  71 calculated  following Ledig  (1974).  Leaf area  w e r e made on s u b s a m p l e s o f e a c h f o l i a g e age LI-3000  Data  (Lambda I n s t r u m e n t s )  determinations  class using a  l e a f area meter b e f o r e d r y i n g .  analysis D a t a w e r e s u b j e c t e d t o a one-way a n a l y s i s  of v a r i a n c e .  S i g n i f i c a n c e b e t w e e n t r e a t m e n t s / s p e c i e s was  determined  p<  test  0.05  1981).  w i t h t h e Tukey m u l t i p l e  comparisons  at  (Stoline,  72 RESULTS Seedling  physiology  Photosynthesis Differences within a given  i n the photosynthetic  during the period that the  d e c i d u o u s c a n o p i e s were l e a f l e s s , midsummer p e r i o d .  i n comparison t o the  Grand f i r growing w i t h a low d e n s i t y  canopy c o n s i s t e n t l y had t h e g r e a t e s t  photosynthetic  rate  (Tables  6, 7, 8 a n d 9 ) , e x c e p t f o r one  s e t o f measurements i n t h e w i n t e r photosynthetic  (Table  9).  The  lowest  r a t e s i n t h e s p r i n g a n d summer were t h o s e o f  D o u g l a s - f i r under the high d e n s i t y canopies 8).  species  canopy d e n s i t y , and between d i f f e r e n t canopy  density treatments diminished  overtopping  r a t e between  (Tables  6 and  A t t h e autumn a n d w i n t e r m e a s u r e m e n t s t h e D o u g l a s - f i r  r a t e s were c l o s e r t o t h o s e o f t h e o t h e r  species,  and a t t h e  s a l m o n b e r r y s i t e , t h e D o u g l a s - f i r autumn a n d w i n t e r equaled those o f the grand f i r (Tables The p e r f o r m a n c e o f a s p e c i f i c  7 and 9 ) .  s p e c i e s between t h e  d i f f e r e n t treatments varied with species the  rates  and season.  During  s p r i n g measurement a t t h e s a l m o n b e r r y s i t e , a l l s p e c i e s  were s i g n i f i c a n t l y  d i f f e r e n t between t r e a t m e n t s w i t h t h e low  canopy d e n s i t y t r e a t m e n t h a v i n g  the greatest,  canopy d e n s i t y t r e a t m e n t t h e lowest  photosynthetic  A t t h e summer measurement t h e medium a n d h i g h treatments d i d not d i f f e r s i g n i f i c a n t l y significant  and t h e h i g h rates.  canopy d e n s i t y  (Table  d i f f e r e n c e i n t h e autumn a n d w i n t e r  6).  The  only  d a t a was t h e  73 T a b l e 6. S p r i n g a n d summer means o f p h o t o s y n t h e t i c r a t e , P s (mgCC>2'dm ' h r ) , l e a f c o n d u c t a n c e , g-^ (em's" ) , v a p o r p r e s s u r e d e f i c i t , D (KPa), p h o t o s y n t h e t i c a l l y a c t i v e r a d i a t i o n d u r i n g P s m e a s u r e m e n t s , PPFD (uMol'm ' s •"•) , l e a f w a t e r p o t e n t i a l , wp (MPa), a n d c h l o r o p h y l l c o n t e n t , C h l (mg'g ) , o f D o u g l a s - f i r ( D F ) , g r a n d f i r ( G F ) , a n d w e s t e r n h e m l o c k (WH) s e e d l i n g s w i t h i n s a l m o n b e r r y s t a n d s o f different density. I  2  a  Treatment/ species  spring Ps  (June 14, 1984; C l e a r 22 t o 9.5°C) g D PPFD wp Chl x  Low  1.2  DF GF WH  5.6c 8.6a 6.7b  1  .16bc .18a .18ab  Medium  0.4  DF GF WH  3.4e 5.8c 4.7d  0.4 i.7f 3.6d 3.7d summer  Low DF GF WH  -0.5ab -0.5abc -0.3c  3.27a 3.44a 2.51b  -0.6a 3.38a - 0 . 4 a b c 3.34a - 0 . 5 a b c 2.62b  ( A u g u s t 23, 1984; B r o k e n c l o u d 19.5 t o 11°C) 1.1 1500 5.6b 7.9a 5.1b  .0 9ab .10a .06abc  - l . O a b c 2.56b - 0 . 8 a b c 2.43bc - 0 . 8 a b c 2.03d 0.6  1.5de 3.4c 3.2c  -1.2a 3.15a - 0 . 9 a b c 3.24a -0.6c 2.07cd 0.8  0.6e 2.5cd 2.8c  380  .05abc .08ab .10a  High DF GF WH  2.65b 2.71b 1.66c  2 65  .07f .10e .07f  Medium DF GF WH  -0.2c -0.2c -0.3bc 400  .12de .16ab .14cd  High DF GF WH  1100  .02c .04bc .05abc  120 -1.1a -l.Oab -0.7bc  Mean v a l u e s w i t h i n a c o l u m n f o l l o w e d w i t h d i f f e r e n t l e t t e r s a r e s i g n i f i c a n t l y d i f f e r e n t (p<0.05).  3.03a 3.13a 2.07cd  74 T a b l e 7. Autumn a n d w i n t e r means o f p h o t o s y n t h e t i c r a t e , P s (mgC02*dm ' h r ) , l e a f c o n d u c t a n c e , g^_ (era's" ) , v a p o r p r e s s u r e d e f i c i t , D (KPa), p h o t o s y n t h e t i c a l l y a c t i v e r a d i a t i o n d u r i n g P s m e a s u r e m e n t s , PPFD ( u M o l ' m ' s ), l e a f w a t e r p o t e n t i a l , wp (MPa), a n d c h l o r o p h y l l c o n t e n t , C h l ( m g ' g ) , o f D o u g l a s - f i r (DF), g r a n d f i r (GF), and w e s t e r n h e m l o c k (WH) s e e d l i n g s w i t h i n s a l m o n b e r r y s t a n d s o f different density. 2  - 1  - 2  - 1  autumn Treatment/ species  (November 28, 1983; C l o u d y 7.5 t o 0.5°C) Chl Ps D PPFD wp 91  Low DF GF WH  0.4 5.0a 4.3a 5. Oa  0.3 5.0a 3.7b 4.2ab  Low DF GF WH  -winter  - 0 . 3 b c d 3.12a -0.4ab 3.14a - 0 . 3 b c d 1.94c  ( F e b r u a r y 17, 1984; C l e a r 9 t o -7°C) 0.5 831  3. 6ab 4 .2a 3.1bcd  03ab 04a 03ab  -0.8ab -0.6d -0.9a 0.6  3.4abc 3.8ab 2.6d  - 0 . 7 b c d 2.56b - 0 . 6 c d 3.17a -0.8ab 2.06c 0.5  3.5abc 3.2bcd 2.8cd  03ab 02b 02b  2.30bc 2.48b 2.03c  716  . 03ab . 03ab ,04ab  High DF GF WH  787  . 08ab . 06bc . 04cd  Medium DF GF WH  -0.2d 3.04a - 0 . 3 b c d 3.13a -0.5a 2.10c 0.3'  5. 3a 4.3ab 4. l a b  884  09a 05bc 03d  High DF GF WH  -0.2cd 2.50b -0.2cd 2.54b - 0 . 4 a b c 2.07c  09a 08ab 07ab  1  Medium DF GF WH  962  720 -0.6d 2.95a -0.5d 3.02a -0.8abc 2.23bc  Mean v a l u e s w i t h i n a c o l u m n f o l l o w e d w i t h d i f f e r e n t letters are s i g n i f i c a n t l y different (p<0.05).  T a b l e 8. S p r i n g and summer means o f p h o t o s y n t h e t i c rate, P s ( m g C 0 ' d m ' h r ) , l e a f c o n d u c t a n c e , g-^ ( e m ' s ) , v a p o r p r e s s u r e d e f i c i t , D (KPa), p h o t o s y n t h e t i c a l l y a c t i v e r a d i a t i o n d u r i n g Ps m e a s u r e m e n t s , PPFD (uMol'm s ), l e a f w a t e r p o t e n t i a l , wp (MPa), a n d c h l o r o p h y l l c o n t e n t , C h l (mg'g ), o f D o u g l a s - f i r (DF), g r a n d f i r (GF), and w e s t e r n h e m l o c k (WH) s e e d l i n g s w i t h i n r e d alder stands of d i f f e r e n t density. - 2  - 1  2  Treatment/ species  spring Ps  (June 16, 1984 C l e a r 17 t o 8°C) PPFD wp D 9l  Low DF GF WH  0.9 S^bc 6. 8a 6. 3ab  1  DF GF WH  0.3 4.4d 5.8abc 5.2dc  Low DF GF WH  0.3 1.3f 2.8e 2. 5e summer ( A u g u s t 24, 4.7ab 5.4a 4. l b c  -0.3bc -0 .2c -0.4ab  3.12ab 3.23a 2.88bc  359 - 0 . 6 a b c 3.07a 3.16a -0.4bc - 0 . 5 a b c 2.06c  . 05cd .07bc . 07bc 0.5  1.3f 2.0ef 1.3f  3.19a 2.93bc 2.62d  2. 62b -0.7a - 0 . 5 a b c 2.54b 1. 65d -0.7a  .0 9ab .12a .07bc  High DF GF WH  -0.2c -0.3bc -0 .5a  1984; C l o u d y 22 t o 1 0 ° C ) — 1462 1.6  0.4 2.7de 3. 2d 3.4bcd  2.7 9 c d 2.62cd 2.04e  182  .03d .07c . 05cd  Medium DF GF WH  -0 .2c -0.3bc -0.4ab 672  .0 9bc .14a .14a  High DF GF WH  1316  . 12ab • 15a .15a  Medium  Chl  .02d .0 6c .04cd  146 3.14a -0.6ab 3.24a -0.4c - 0 . 5 a b c 1.94cd  ^ Mean v a l u e s w i t h i n a c o l u m n f o l l o w e d w i t h d i f f e r e n t l e t t e r s a r e s i g n i f i c a n t l y d i f f e r e n t (p<0.05).  76 T a b l e 9. Autumn a n d w i n t e r means o f p h o t o s y n t h e t i c r a t e , P s (mgCC^'dm 'hr ) , l e a f c o n d u c t a n c e , g± ( e m ' s ) , v a p o r p r e s s u r e d e f i c i t , D (KPa), p h o t o s y n t h e t i c a l l y a c t i v e r a d i a t i o n d u r i n g P s m e a s u r e m e n t s , PPFD (uMol'm *s ) , l e a f w a t e r p o t e n t i a l , wp (MPa), and c h l o r o p h y l l c o n t e n t , C h l ( m g ' g ) , o f D o u g l a s - f i r ( D F ) , g r a n d f i r ( G F ) , and w e s t e r n h e m l o c k (WH) s e e d l i n g s w i t h i n r e d a l d e r stands of d i f f e r e n t density. Z  -  - 1  autumn Treatment/ species  (November 29, 1983; C l o u d y 5.5 t o -1°C) — Ps wp Chl D PPFD 9l  Low  0.2  DF GF WH  4 .2a 4.8a 4.4a  1  . 08ab .05bcd .0 6abc  Medium  0.1  DF GF WH  4.4a 4.6a 4.1a  0.1 4.3a 4.5a 4.1a winter  Low DF GF WH  4. l a 3.4b 3.1b  . 03a . 02a . 03a 0.7  3. 6ab 3.2ab 3. 3ab  1  0.7 2.8b 3.4ab 3.1b  3 .00a 3.12a 2.12c  -0 .2a -0.2a -0.3a  3.05a 3.17a 1.99c  .04a . 03a . 03a  —  -0. 6a -0. 8a -0.7a  2. 66b 2.50bc 2.07d  -0.7a -0. 6a -0. 6a  2.55bc 3.19a 2.07d  -0.5a -0.7a -0. 6a  3.12a 3.04a 2.2 9 c d  676  . 03a .02a .03a  High DF GF WH  -0.3a -0.2a -0.2a  1984; O v e r c a s t 10 t o 0 .5°C) 0.8 734  Medium DF GF WH  2. 60b 2.57b 2.08c  642  . 0 6abc .05bcd .03d  ( F e b r u a r y 29,  -0.2a -0.1a -0.3a 769  .09a . 04cd . 05bcd  High DF GF WH  734  572  Mean v a l u e s w i t h i n a c o l u m n f o l l o w e d w i t h d i f f e r e n t l e t t e r s a r e s i g n i f i c a n t l y d i f f e r e n t (p<0.05).  winter  value  f o r grand f i r under h i g h  lower than the values sampling date  f o r t h e low d e n s i t y  seasonal  p a t t e r n was r e p e a t e d a t t h e r e d  I n t h e s p r i n g a n d summer a g i v e n  g e n e r a l l y had reduced photosynthesis overtopping winter  canopy d e n s i t y  the only  (Table  8).  increasing  I n t h e autumn a n d treatments  r a t e i n D o u g l a s - f i r under  high  c a n o p y t r e a t m e n t as c o m p a r e d w i t h t h e o t h e r  treatments  (Table  9).  Comparison between s p e c i e s greatest  with  species  s i g n i f i c a n t d i f f e r e n c e between  was a l o w e r p h o t o s y n t h e t i c density  t r e a t m e n t on t h a t  (Table 7 ) .  A similar alder s i t e .  d e n s i t y w h i c h was  w i t h i n t r e a t m e n t s shows t h e  differences i n the spring  i n t h e autumn  (Table  9).  (Table  8)  and t h e l e a s t  I n t h e s p r i n g a n d summer a t t h e  salmonberry s i t e , D o u g l a s - f i r equaled t h e  photosynthetic  r a t e o f hemlock o n l y under t h e lowest canopy d e n s i t y summer.  Hemlock p h o t o s y n t h e t i c  throughout t h e year under high medium d e n s i t y autumn.  treatments,  i n the  r a t e s matched grand f i r density,  i n t h e summer a t  and f o r a l l t r e a t m e n t s i n t h e  D o u g l a s - f i r was e q u a l t o g r a n d f i r u n d e r a l l  t r e a t m e n t s i n t h e autumn a n d a t t h e medium d e n s i t y  treatment  in the winter. I n t h e s p r i n g a n d summer D o u g l a s - f i r p e r f o r m e d  better  i n r e l a t i o n t o hemlock a t t h e r e d a l d e r s i t e t h a n a t t h e salmonberry s i t e photosynthetic density  (Table  6 v s 8).  Hemlock had g r e a t e r  rates than Douglas-fir  treatment i n the spring.  only  a t t h e low  I n t h e s p r i n g a n d summer  78 D o u g l a s - f i r equaled grand f i r only density.  a t t h e medium c a n o p y  D o u g l a s - f i r was e q u a l t o g r a n d f i r a t a l l  t r e a t m e n t s i n t h e autumn, b u t was g r e a t e r treatment i n the winter.  a t the low d e n s i t y  Hemlock p h o t o s y n t h e t i c  rates  below t h o s e o f D o u g l a s - f i r w i t h i n t h e low d e n s i t y summer a n d  Leaf  conductance  conductance than i n photosynthesis. conductances d e c l i n e d w i t h density  (Table  occurred  6 and 8 ) .  i n the winter  the photosynthesis greatest sites,  Few  9).  a n d summer  differences  7 and 9 ) .  As r e f l e c t e d  (Tables  surpassed the conductance o f grand f i r c a n o p y i n t h e autumn  more s i m i l a r t o t h o s e o f t h e l o w d e n s i t y  and  Douglas-fir  showed no  w e s t e r n hemlock c o n t i n u e d  (Table  winter became  significant and w i n t e r  while  t o show d i f f e r e n c e s b e t w e e n l o w  treatments.  8  than the high  d i f f e r e n c e b e t w e e n t r e a t m e n t s i n t h e autumn  density  in  A t t h e s a l m o n b e r r y and r e d a l d e r  m e a s u r e m e n t s , t h e medium d e n s i t y t r e a t m e n t v a l u e s  high  leaf  canopy  significant  I n t h e p e r i o d b e t w e e n t h e autumn  density treatment.  i n leaf  measurements, grand f i r g e n e r a l l y had t h e  conductance.  Douglas-fir  Spring  increasing overtopping  o n l y u n d e r t h e medium d e n s i t y  and  i n the  winter.  T h e r e were f e w e r d i f f e r e n c e s b e t w e e n s p e c i e s  and  were  79 Leaf water p o t e n t i a l Few s i g n i f i c a n t d i f f e r e n c e s occurred  i n l e a f water  p o t e n t i a l between species growing at d i f f e r e n t d e n s i t y treatments  (Tables  d i f f e r e n c e occurred  canopy  6, 7, 8, and 9). When a  at the salmonberry s i t e i t was g e n e r a l l y  under t h e medium or high d e n s i t y  treatment.  Comparing s p e c i e s w i t h i n treatments, hemlock showed a d i f f e r e n t p a t t e r n between the r e d a l d e r and salmonberry s i t e s i n the s p r i n g  (Tables  6 and 8 ) . At the r e d a l d e r  site  hemlock had c o n s i s t e n t l y g r e a t e r water s t r e s s than e i t h e r D o u g l a s - f i r and/or grand f i r .  At the salmonberry  site  western hemlock was lower only under the medium d e n s i t y treatment.  In the summer, western hemlock water s t r e s s  remained r e l a t i v e l y low under the canopies. and  In the autumn  w i n t e r there was no s i g n i f i c a n t d i f f e r e n c e between  s p e c i e s w i t h i n a treatment at the r e d a l d e r  site.  D o u g l a s - f i r had lower l e a f water p o t e n t i a l s than western hemlock at the medium d e n s i t y salmonberry s i t e i n the autumn.  Grand f i r was below hemlock at a l l treatments i n  the w i n t e r  Chlorophyll The  (Tables 7 and 9 ) .  content  r e l a t i o n s h i p between c h l o r o p h y l l content and  s p e c i e s w i t h i n a treatment was very  c o n s i s t e n t and may have  only changed under the medium d e n s i t y treatment i n t h e winter,  when the grand f i r c h l o r o p h y l l content was above  that of Douglas-fir.  Grand f i r c h l o r o p h y l l content was  80 consistently greater content. density  than western hemlock c h l o r o p h y l l  Between t r e a t m e n t s ,  seedlings  under t h e low  canopy t r e a t m e n t g e n e r a l l y had lower c h l o r o p h y l l  content than the high density 8 and 9 ) .  Hemlock  canopy t r e a t m e n t  (Tables  showed no s i g n i f i c a n t d i f f e r e n c e s  t r e a t m e n t s i n t h e autumn  and w i n t e r  6,  7,  between  at both the red alder  a n d s a l m o n b e r r y s i t e s a n d t h e s a l m o n b e r r y i n t h e summer. B e t w e e n t h e autumn Douglas-fir the  and w i n t e r  the c h l o r o p h y l l content of  a t t h e medium d e n s i t y  low, then t h e h i g h  t r e a t m e n t came t o r e s e m b l e  canopy d e n s i t y  r e d a l d e r and s a l m o n b e r r y s i t e s  Seedling Grand f i r seedlings  t r e a t m e n t and b o t h t h e  (Tables  7 and 9 ) .  survival  c o n s i s t e n t l y had g r e a t e r  t h a n D o u g l a s - f i r or western hemlock s e e d l i n g s  survival  a f t e r two  growing seasons under a l l d e n s i t i e s o f b o t h t h e salmonberry and a l d e r c a n o p i e s intermediate  (Table  10).  Western hemlock had  s u r v i v a l a n d D o u g l a s - f i r t h e l o w e s t on a l l  p l o t s on b o t h t h e s a l m o n b e r r y a n d a l d e r s i t e s , low  density  alder plot.  The l o w d e n s i t y p l o t s g e n e r a l l y h a d t h e survival.  except the  S u r v i v a l u n d e r t h e medium a n d h i g h  c a n o p i e s w e r e s i m i l a r i n most c a s e s .  greatest density  The w i d e s t v a r i a t i o n s  81  T a b l e 10. S u r v i v a l of p l a n t e d s e e d l i n g s a f t e r the second g r o w i n g season under deciduous shade. P e r c e n t o f 40 s e e d l i n g s per s p e c i e s per shrub d e n s i t y treatment. Treatment/ species  Salmonberry  Red A l  Low DF GF WH  72 88 82  82 92 72  53 75 60  42 82 68  32 78 64  52 82 72  Medium DF GF WH High DF GF WH  82 w e r e e x h i b i t e d b y D o u g l a s - f i r w h i c h h a d much l o w e r under t h e h i g h but high  density  t h a n t h e medium d e n s i t y  p o o r e r s u r v i v a l u n d e r t h e medium d e n s i t y density  The  salmonberry,  alder than the  alder.  Seedling  Specific  leaf  growth  area  s p e c i f i c l e a f area of t r e e seedlings  under both t h e  r e d a l d e r a n d s a l m o n b e r r y c a n o p i e s v a r i e d among and  species  survival  (Tables  area increased  11 a n d 1 2 ) .  with greater  W i t h no o v e r t o p p i n g hemlock s e e d l i n g s  canopy  In general,  overtopping (low d e n s i t y  treatments  specific  canopy  density.  treatment)  had a s i g n i f i c a n t l y h i g h e r  leaf  western  specific  leaf  area than Douglas-fir  and grand f i r a t b o t h t h e salmonberry  and  I n t h e medium d e n s i t y  red alder sites.  specific all  treatment  l e a f a r e a a t t h e s a l m o n b e r r y s i t e was d i f f e r e n t f o r  the species.  The o n l y  species  n o t t o have a s i g n i f i c a n t  change i n s p e c i f i c l e a f a r e a between t r e a t m e n t s a t a s i t e was g r a n d f i r u n d e r medium a n d h i g h  Leaf growth The  red alder.  rate  l e a f growth r a t e d e c r e a s e d i n g r a n d f i r and  Douglas-fir density.  density  given  at both s i t e s with  i n c r e a s i n g overtopping  At the salmonberry s i t e there  canopy  w e r e no s i g n i f i c a n t  83 T a b l e 1 1 . Mean v a l u e s o f s p e c i f i c l e a f a r e a (SLA) o f 1984 f o l i a g e , r e l a t i v e l e a f g r o w t h r a t e (RLGR), r e l a t i v e d i a m e t e r g r o w t h r a t e (RDGR), a n d r e l a t i v e h e i g h t g r o w t h r a t e (RHGR) f o r D o u g l a s - f i r (DF), grand f i r (GF), and w e s t e r n hemlock (WH) s e e d l i n g s a f t e r t h r e e y e a r s o f g r o w t h w i t h i n salmonberry stands o f d i f f e r e n t d e n s i t i e s . Treatment/ species  SLA (cm^'g ) i  RLGR (g-yr ' g ) i  l  RDGR (mm* y r 'mm  RHGR "cm ) (cm'yr  Low DF GF WH  83^ 109e  1.2ab 1.7a 0.9bc  0.7bc 1.4a 0 . 9ab  0.85a 0.90a 0.82a  162c 136d 177b  0.4cd 0.8bcd 1.2ab  0.3c 0.9ab 0. 8bc  0.4 6ab 0.64ab 0.76a  180b 154c 214a  0.3d 0.3d 0.6bcd  0.3c 0. 6bc 0.7bc  0.22b 0.58ab 0.72a  80f  Medium DF GF WH High DF GF WH  Mean v a l u e s f o l l o w e d b y d i f f e r e n t l e t t e r s w i t h i n a r e s i g n i f i c a n t l y d i f f e r e n t (p<0.05).  a column  84 T a b l e 12. Mean v a l u e s o f s p e c i f i c l e a f a r e a (SLA) o f 1984 f o l i a g e , r e l a t i v e l e a f g r o w t h r a t e (RLGR), r e l a t i v e d i a m e t e r g r o w t h r a t e (RDGR), a n d r e l a t i v e h e i g h t g r o w t h r a t e (RHGR) f o r D o u g l a s - f i r (DF), g r a n d f i r (GF), and w e s t e r n hemlock (WH) s e e d l i n g s a f t e r t h r e e y e a r s o f g r o w t h w i t h i n red alder stands of d i f f e r e n t d e n s i t i e s . Treatment/ species  SLA ( c m ' g ^) 2  RLGR (g'yr ' g 1  ^5  RDG -1 (mm'yr mm )(cm'yr  'cm  _!)  Low DF GF WH  1.4ab 1.6a 1.Oabc  0. 9abc 1.3a 1. l a b  0.62abc 0.87a 0.65abc  132d 141cd 170b  0.7c 1.5ab l.Obc  0.4cd 0.8abcd 1.2ab  0.37bc 0.71ab 0.70ab  165b 158bc 198a  0.5c 0.7c 0. 6c  0.3d 0.6bcd 0.8abed  0 .30c 0.54abc 0.66abc  73f 82f HOe  J  Medium DF GF WH High DF GF WH  Mean v a l u e s f o l l o w e d b y d i f f e r e n t l e t t e r s w i t h i n a c o l u m n are s i g n i f i c a n t l y d i f f e r e n t (p<0.05).  85  d i f f e r e n c e s between D o u g l a s - f i r densities. noticeably  a n d g r a n d f i r a t any  A n i m a l c l i p p i n g o f g r a n d f i r f o l i a g e was greater  t h a n on t h e o t h e r s e e d l i n g s .  The w e s t e r n  hemlock  seedlings  at t h e r e d a l d e r s i t e had s i g n i f i c a n t l y  greater  f o l i a g e g r o w t h r a t e s t h a n D o u g l a s - f i r when t h e r e  was  an o v e r t o p p i n g c a n o p y .  R e l a t i v e diameter growth  rate  T h e r e was no s i g n i f i c a n t  change i n t h e r e l a t i v e  diameter growth r a t e i n D o u g l a s - f i r  or western  hemlock  between salmonberry treatment d e n s i t i e s .  Grand f i r  c o n s i s t e n t l y grew f a s t e r t h a n D o u g l a s - f i r  at a l l salmonberry  treatment d e n s i t i e s . intermediate  hemlock  growth  was  a t b o t h t h e l o w a n d medium d e n s i t i e s o f  salmonberry. species  Western  T h e r e was no s i g n i f i c a n t d i f f e r e n c e b e t w e e n  at the high  density  salmonberry p l o t s .  At the r e d  a l d e r s i t e t h e medium d e n s i t y was i n t e r m e d i a t e  i n growth f o r  Douglas-fir  d i dnot  and grand f i r ,  d i f f e r between t r e a t m e n t s . d i f f e r e n c e between s p e c i e s the  low and h i g h  medium d e n s i t y intermediate  density  b u t w e s t e r n hemlock T h e r e was no  significant  r e l a t i v e diameter growth r a t e f o r  red alder treatments.  At the  r e d a l d e r t r e a t m e n t g r a n d f i r was  i n r e l a t i v e diameter growth  rate.  R e l a t i v e h e i g h t growth  rate  On b o t h t h e s a l m o n b e r r y and r e d a l d e r p l o t s  western  h e m l o c k and g r a n d f i r d i d n o t d i f f e r s i g n i f i c a n t l y r e l a t i v e h e i g h t growth  r a t e between t r e a t m e n t s .  in  Douglas-f  h e i g h t growth d e c l i n e d w i t h i n c r e a s i n g o v e r t o p p i n g canopy density.  87 DISCUSSION As utilize  hypothesized, seasonal  D o u g l a s - f i r s e e d l i n g s were a b l e t o  increases i n l i g h t that occurred i n the  autumn a n d w i n t e r t o n a r r o w t h e p h y s i o l o g i c a l d i f f e r e n c e s between i t and s e e d l i n g s w i t h g r e a t e r shade t o l e r a n c e . However, a c h i e v e d g r o w t h , a s an i n t e g r a t o r o f p h y s i o l o g i c a l success  and e n v i r o n m e n t a l  hazards,  suggests  t h a t growth o f  D o u g l a s - f i r d e c l i n e s s h a r p l y as shade from competitors  increases.  damage, p l a n t e d g r a n d establishment  Seedling  With  deciduous  adequate p r o t e c t i o n from  f i r may be an e x c e l l e n t c h o i c e f o r  i n unavoidably  shrubby  areas.  physiology  L i m i t a t i o n s o f t h e methodology r e s t r i c t e d t o d a y s when t h e c o n i f e r f o l i a g e was d r y . western  animal  h e m l o c k zone t h i s  In the Coastal  i s not the t y p i c a l  t h e autumn a n d w i n t e r m o n t h s .  Helms  measurements  situation i n  (1963) i n d i c a t e d  that  t h e s e d r y a n d r e l a t i v e l y warm d a y s w e r e t h e p e r i o d s o f maximum p h o t o s y n t h e t i c a c t i v i t y Therefore,  i n those  seasons.  the photosynthetic r a t e s t h a t are reported here  f o r t h e s p r i n g , autumn a n d w i n t e r m i g h t be c o n s i d e r e d among t h e maximums f o r t h o s e p e r i o d s .  I n t h e summer, Helms  r e p o r t e d t h a t r a i n y d a y s may i m p r o v e t h e m o i s t u r e  relations  o f t h e t r e e and a l l o w g r e a t e r p h o t o s y n t h e t i c r a t e s ;  i f so  t h e v a l u e s r e p o r t e d h e r e a r e more s e a s o n a l l y t y p i c a l , b u t p e r h a p s among t h e l o w e r o f t h e p o s s i b l e v a l u e s . i n t e r p r e t i n g s e a s o n a l d i f f e r e n c e s between s p e c i e s  In there  88 c o u l d be c o n f o u n d i n g b e t w e e n s p e c i e s different with  rates  This  greatest  capacity  increases  of the leaves  r a t e and as a f u n c t i o n o f l e a f  p o s s i b l e s o u r c e o f c o n f o u n d i n g w o u l d be t h e  i n t h e s p r i n g when t h e r a t e o f i n c r e a s e  photosynthetic 1977;  rate  and  No a t t e m p t was made t o s e p a r a t e  differences i n photosynthetic  photosynthetic age.  i n which the photosynthetic  leaf maturity.  seasonal  and t r e a t m e n t s ,  Sestak,  capacity 1985).  i s the steepest  Since  were made, i t i s d i f f i c u l t  o f new  leaf  ( F r y and P h i l l i p s ,  no m e a s u r e m e n t s o f r e s p i r a t i o n t o determine the net c o n t r i b u t i o n  t h a t changes i n g r o s s p h o t o s y n t h e t i c  r a t e s made t o c h a n g e s  i n net C O 2 uptake. Results  from t h i s experiment support t h e statement  shade t o l e r a n t s p e c i e s  o f t e n have g r e a t e r  photosynthetic  r a t e s i n shaded environments than under h i g h and  Jarvis,  1 9 8 0 ; Hodges a n d S c o t t ,  that  1968) .  light  (Leverenz  However, u n d e r a  d e c i d u o u s canopy t h e magnitude and t h e f r e q u e n c y o f d i f f e r e n c e s may v a r y  seasonally.  u n d e r t h e medium a n d h i g h the  ability  density  t o have p h o t o s y n t h e t i c  equal t o the low d e n s i t y same t r e a t m e n t .  Helms  penetrated  canopy t r e a t m e n t rates greater  (1963) a l s o f o u n d  showed  than or  During periods  suppressed  assimilation rates i nthe when a d e q u a t e  t o the suppressed trees t h e i r  r a t e s were g r e a t e r  Douglas-fir  t r e a t m e n t and g r a n d f i r under t h e  D o u g l a s - f i r t o be c a p a b l e o f h i g h autumn a n d w i n t e r .  In the winter,  than dominant t r e e s .  light  photosynthetic  89  The  f e w e r number o f d i f f e r e n c e s i n l e a f  c h l o r o p h y l l c o n t e n t , an l e a f w a t e r p o t e n t i a l  conductance, i n t h e autumn  t h a n a t t h e o t h e r s a m p l i n g t i m e s may h a v e r e s u l t e d f r o m t h e onset o f c o l d hardening  ( F r y and P h i l l i p s , 1 9 7 7 ) .  The  g r e a t e r l e a f water p o t e n t i a l s a t the salmonberry s i t e  may  have r e s u l t e d from d r y i n g o f t h e low b u l k d e n s i t y o r g a n i c material that stands.  typically  accumulates under  Drew a n d F e r r e l l  (1979)  salmonberry  reported that  Douglas-fir  water p o t e n t i a l s are lower i n the winter r e g a r d l e s s of l e a f w a t e r p o t e n t i a l s a n d t h a t p l a n t s grown u n d e r lower water p o t e n t i a l s than p l a n t s under l a r g e r o o t systems  full  low l i g h t had sun.  The  on t h e l o w c a n o p y d e n s i t y t r e a t m e n t  s e e d l i n g s may h a v e c o m p e n s a t e d f o r t h e h i g h e r m o i s t u r e demands i n t h o s e p l o t s ,  r e s u l t i n g i n the lack o f water  p o t e n t i a l d i f f e r e n c e s between t r e a t m e n t s . (1979)  reported that  s t o m a t a l c l o s u r e i s more s e n s i t i v e t o  vapor pressure d e f i c i t s water p o t e n t i a l .  Drew a n d F e r r e l l  i n t h e autumn r e g a r d l e s s o f p l a n t  T h i s w o u l d e x p l a i n why l e a f c o n d u c t a n c e i s  down i n t h e w i n t e r w h i l e w a t e r p o t e n t i a l  s t a y e d about t h e  same.  S e e d l i n g s u r v i v a l and growth No s i n g l e a g e n t a p p e a r e d r e s p o n s i b l e f o r t h e m o r t a l i t y of  the planted seedlings.  S e v e r a l f a c t o r s such as t h e l a t e  planting f o r that elevation, the longer duration of storage of  seedlings before planting,  d i f f i c u l t i e s i n planting  w i t h i n e x i s t i n g c a n o p i e s and r o o t n e t w o r k s , and e v e r p r e s e n t  90 a n i m a l damage may h a v e i n f l u e n c e d s u r v i v a l o f s e e d l i n g s . Most m o r t a l i t y o c c u r r e d that  initial  w i t h i n t h e f i r s t year,  establishment  a n i m a l s was t h e d o m i n a n t  r a t h e r t h a n f o l i a g e damage f r o m cause.  Between-species trends difficult  to interpret.  i n c r e a s i n g stock  size.  suggesting  i n seedling survival are  Greater  survival i s related to  Although large stock  was d i f f i c u l t  to p l a n t , the large grand f i r seedlings  (2+1 BR) e s t a b l i s h e d  readily.  had a tendency t o  dry  The w e s t e r n h e m l o c k s e e d l i n g s  a n d c a s t n e e d l e s , s o m e t i m e s w i t h i n a few weeks o f  planting,  despite moist s o i l s .  Douglas-fir  smallest, but the easiest t o plant. and  (1983)  White  seedlings  have g r e a t e r  canopies.  (1984)  and S t e i n  w e s t e r n hemlock o u t p l a n t e d salmonberry  found t h a t  (1983)  reported  Newton  larger t o outgrow  shrub  poor s u r v i v a l o f  w i t h i n e x i s t i n g and e s t a b l i s h i n g  canopies.  These r e s u l t s s u g g e s t t h a t D o u g l a s - f i r w i l l tolerate  was t h e  (1978),  Newton  s u r v i v a l and a b i l i t y  Newton a n d W h i t e  stock  low l e v e l s o f o v e r t o p p i n g  live  canopies  only before  s u r v i v a l and growth a r e reduced from t h a t o f t h e unshaded condition.  However, R u t h  (1956)  reported  that t h i r d  s u r v i v a l o f D o u g l a s - f i r and w e s t e r n hemlock r e m a i n e d i n t h e 90 p e r c e n t i l e u n t i l completely  seedlings  o v e r t o p p e d by d e c i d u o u s c a n o p i e s .  experiments reported  year  seedlings were In the  here, above-ground c o m p e t i t i o n  was  c o n t r o l l e d w h i l e below ground competition  from r e s p r o u t s  left  i s important,  unchecked.  Below-ground competition  was but  91 the e l i m i n a t i o n o f below-ground in operational  competition i s not f e a s i b l e  forestry other than the short periods a f t e r a  large a p p l i c a t i o n of herbicides or mechanical scarification..  By means o f c a n o p y  m a n i p u l a t i o n and  t r e n c h i n g around r o o t s o f w e s t e r n hemlock,  Christy  (1986)  demonstrated t h a t t h e r e d u c t i o n o f below ground c o m p e t i t i o n had a l e s s e r e f f e c t than i n c r e a s i n g l i g h t  i n the situation  b e i n g s t u d i e d , b u t t h a t t h e r e was a s t r o n g e f f e c t between r e d u c t i o n o f above and below  synergistic ground  competition. O v e r a l l growth o f s e e d l i n g s g e n e r a l l y decreased w i t h i n c r e a s i n g canopy  density.  Douglas-fir,  the least  t o l e r a n t o f t h e c o n i f e r s s t u d i e d , h a d t h e most  shade  pronounced  growth r e d u c t i o n w i t h i n c r e a s i n g shade.  Both shaded  hemlock  to maintain  and grand f i r  showed t h e a b i l i t y  e x c e l l e n t growth r e l a t i v e t o unshaded t e r m p r o s p e c t s o f w e s t e r n hemlock from t h e s a l m o n b e r r y canopy  appear  seedlings.  and grand f i r  western  The l o n g emergence  good.  R e s u l t s from t h e s p e c i f i c l e a f a r e a measurements suggest that the l i g h t  l e v e l s were l o w e r under t h e  salmonberry canopies f o r a given treatment density under t h e r e d a l d e r .  D o u g l a s - f i r and w e s t e r n hemlock  t o have l a r g e r s p e c i f i c l e a f a r e a s under  tended  salmonberry than  f o r s i m i l a r t r e a t m e n t s on t h e R e d a l d e r s i t e . specific  than  Grand f i r  l e a f a r e a s were a b o u t t h e same a t b o t h s i t e s .  The  r e s p o n s e o f s p e c i f i c l e a f a r e a was v e r y s e n s i t i v e t o t r e a t m e n t c o n f i r m i n g t h e f i n d i n g s o f D e l R i o and Berg  (197 9)  92 f o r D o u g l a s - f i r , T u c k e r and Emmingham Tucker  (1983) f o r g r a n d  good i n d i c a t o r o f l i g h t R e m o v a l o f b u d s and identifiable  fir,  that s p e c i f i c  ( w h i c h was  f o l i a g e by  animals  was  a major  G r a n d f i r was  f o l l o w e d by D o u g l a s - f i r a n d r a r e l y damaged).  western  G r a z i n g may Ruth  in a l l  t h e most  hemlock  have a c t e d  to  (1956) f o u n d  animal  o f s e e d l i n g s t o i n c r e a s e w i t h t h e amount o f  o v e r t o p p i n g canopy. greatest extent  Browsing  a f f e c t e d height growth t o  for Douglas-fir, although  h a d m i s s i n g o r damaged l e a d e r s . the best  l e a f area i s a  c a u s e o f g r o w t h r e d u c t i o n and v a r i a t i o n  e q u a l i z e growth between s p e c i e s . browsing  and  environment.  three conifer species i n a l l plots. susceptible  (1977) f o r h e m l o c k  s e v e r a l grand f i r  Diameter growth i s l i k e l y  i n d i c a t o r of s e e d l i n g establishment  b e c a u s e o f no d i r e c t  animal  damage and  r e l a t i o n s h i p between diameter  the  the  g r o w t h and  and  growth  allometric  root  development.  However, r e d u c t i o n s i n h e i g h t g r o w t h a r e i m p o r t a n t t h e y a c t t o p r o l o n g t h e s u p p r e s s i o n by t h e  because  overtopping  canopy. The  main e f f e c t of animal  growth r a t e s .  Some o f t h e new  o f D o u g l a s - f i r and  grand  g r o w t h on  f i r and  l e a v i n g some p a r t i a l n e e d l e s . specific  damage a p p e a r e d t o be  30%  approximately  o f h e m l o c k was  P a r t i a l needles  l e a f a r e a as i n t a c t n e e d l e s ;  of leaves c o u l d p o s s i b l y act to lower the sink f o r a v a i l a b l e carbohydrates  had  but, p a r t i a l specific is  on  leaf 75%  clipped the  same  removal  l e a f areas i f  reduced.  93 Based on the type o f i n j u r i e s , they occurred area,  (March through June), and s i g h t i n g s i n the  I b e l i e v e grouse were doing the m a j o r i t y  a l l the s e e d l i n g s . 1961)  and the time i n which  Fowle  (1943)  ( c i t e d i n Lawrence et a l . ,  observed heavy and repeated d e f o l i a t i o n i n j u r i e s  grouse i n D o u g l a s - f i r p l a n t a t i o n s on Vancouver Grouse  o f damage t o  from  Island.  c l i p p i n g o f f o l i a g e was found i n the f i r s t  5 years i n  51% o f p l a n t a t i o n s w i d e l y s c a t t e r e d i n c o a s t a l Washington and Oregon  (Black e t a l . 1979).  Douglas-fir plantations al.(1979) r e p o r t e d in  a succession  On two h i g h - s i t e  i n southwestern Washington,  Black et  t h a t buds removed by grouse was the f i r s t  o f animal damage agents c o n s i s t i n g o f  grouse, hare, and deer, with i n some cases over 80% o f t r e e s damaged by grouse by the second growing  season.  94  CONCLUSIONS 1. D i f f e r e n c e s  i n the physiology  between s p e c i e s  d i f f e r e n t treatments had a seasonal  cycle.  within the  These  d i f f e r e n c e s were g r e a t e s t  i n t h e s p r i n g a n d summer a n d l e a s t  i n t h e autumn a n d w i n t e r ,  suggesting  suppression  by  deciduous canopies v a r i e s g r e a t l y from season t o season. 2.  Suppression  o f D o u g l a s - f i r s e e d l i n g s by d e c i d u o u s  canopies i s g r e a t l y reduced during t h e p e r i o d that  deciduous  canopies are l e a f l e s s . 3. P h y s i o l o g i c a l d i f f e r e n c e s b e t w e e n t r e e s o f d i f f e r e n t tolerance 4.  c a n b e r e d u c e d i n t h e autumn a n d w i n t e r .  S p e c i f i c l e a f area  and l e a f growth r a t e s o f a l l s p e c i e s  r e s p o n d e d s e n s i t i v e l y t o t r e a t m e n t s a n d a r e l i k e l y an excellent 5.  index  o f t h e degree o f  shading.  The g r o w t h o f s h a d e t o l e r a n t s p e c i e s  declined less  with  i n c r e a s i n g d e c i d u o u s s h a d i n g t h a n t h a t o f shade i n t o l e r a n t species. 6. A n i m a l damage p r o b a b l y duration  seedlings  reduces growth and i n c r e a s e s t h e  a r e under a canopy.  95 CHAPTER 4 THE EFFECT OF TREATMENT AND TREATMENT TIMING ON THE RELEASE RESPONSE OF SUPPRESSED DOUGLAS-FIR SAPLINGS  INTRODUCTION  The maintain  objective of conifer release i s t o increase or t h e r a t e o f c r o p t r e e growth by removal o f  competing vegetation.  Conifer release  r e q u i r e d when c o m p e t i n g v e g e t a t i o n the  i s most  often  overtops crop t r e e s , but  s u c c e s s i n i n c r e a s i n g c o n i f e r g r o w t h by r e m o v i n g  overtopping  vegetation  has been v a r i a b l e  ( D i e r a u f , 1977;  MacLean and Morgan, 1983; S t e w a r t e t a l . , 1984). response t o release  from o v e r t o p p i n g  Conifer  competitors  d e p e n d s on  a c c l i m a t i o n f r o m a s h a d e d e n v i r o n m e n t t o an u n s h a d e d o r partly  shaded environment, a p r o c e s s which i n v o l v e s a  v a r i e t y o f p h y s i o l o g i c a l and m o r p h o l o g i c a l t h e s e changes occur, benefit The  changes.  Unless  the released conifer i s unlikely t o  from t h e r e l e a s e . f o l i a g e morphology a t t h e time o f c o n i f e r  release  treatments a f f e c t s the a b i l i t y o f suppressed c o n i f e r s t o utilize  the increased  light.  Rapidly  occurring  p h y s i o l o g i c a l changes, such as changes i n pigment may a l l o w p l a n t s t o e x p l o i t t e m p o r a r y i n c r e a s e s If light  c o n d i t i o n s remain i n c r e a s e d  content,  i n light.  throughout the  d e v e l o p m e n t o f new f o l i a g e (as i n t h e c a s e o f r e l e a s e treatments),  changes i n s t r u c t u r e and t h e r e f o r e  i n function  96 allow the plant to increasingly acclimate to the environmental conditions (1980)  (Larcher,  a n d T u c k e r and Emmingham  1980).  (1977)  W a l l a c e and Dunn  recognized that  initial  a c c l i m a t i o n of released f o r e s t t r e e s  initial  changes  i n p h y s i o l o g y (e.g. l e a f  conductance), but c o n t i n u e d p o s i t i v e  new  requires  diffusive  response to  release  t r e a t m e n t s u l t i m a t e l y d e p e n d s on a d j u s t m e n t s i n l e a f anatomy. P l a n t s undergo higher l i g h t  a w i d e number o f c h a n g e s  levels-.. (Boardman, 1977;  A c c l i m a t i o n o f t h e shade to increased l i g h t  1979;  Patterson,  f o l i a g e o f shade  saturation  (Boardman, 1977;  1967;  1967).  L e a f s t o m a t a l f r e q u e n c y and c o n d u c t a n c e (Holmgren,  1968;  and p h o t o r e s p i r a t i o n  Crookston et a l . ,  c h l o r o p h y l l c o n t e n t o f shade  foliage  l e a f areas  respiration (Zelawski, also  1975).  environments  (Del R i o and B e r g ,  T u c k e r a n d Emmingham, 1977; Munch, 1 9 7 5 ) .  Aussenac  reviewed s t r u c t u r a l differences i n c o n i f e r  foliage  under d i f f e r i n g  l i g h t environments.  Boardman  e t a l . ( 1 9 7 9 ) , Bunce e t a l . ( 1 9 7 7 ) , N o b e l Pieters  (1974)  The  (Lewandowska e t  1 9 7 6 ) , a n d c o n i f e r s grown i n l o w l i g h t  have h i g h e r s p e c i f i c  and  (on an a r e a b a s i s ) i s  g e n e r a l l y h i g h e r t h a n t h a t o f sun f o l i a g e al.,  Kramer  L a r c h e r , 1980), and h i g h e r d a r k  G a u h l , 1976)  species  i n higher  (Loach,  increase  1980) .  intolerant  intensity generally results  photosynthetic light Kozlowski;  i n response t o  1979; (1973) grown  (1977), Clough  ( 1 9 7 6 ) , and  concluded that the m a j o r i t y of the  97 differences i n photosynthetic plants  c o u l d be a t t r i b u t e d t o i r r e v e r s i b l e c h a n g e s i n  internal  leaf  area.  Drew a n d F e r r e l l found t h a t hemlock,  and K e l l e r and Tregunna  r e s p e c t i v e l y , had a reduced a b i l i t y In general,  had a l e s s x e r o p h y t i c compared t o p l a n t s  The  plants  t o avoid  from shaded  environments development  environments  (Keller,  t o which f o l i a g e o f a  t o changes  i n the l i g h t  197 3;  given  environment  d e p e n d p r i m a r i l y on t h e s t a g e o f l e a f d e v e l o p m e n t  (Gauhl,  1976;  S e s t a k , 1977; B u n c e e t a l . , 1977; P e a r c e a n d L e e ,  1969;  P r i o u l e t a l . , 1 9 8 0 ; J u r i k e t a l . , 1 9 7 9 ) , on p l a n t  preconditioning Strand  ( P r i o u l e t a l . , 1980; Seemann e t a l . , 1986;  and O q u i s t ;  i n t e n s i t y change  1 9 8 5 ) , a n d on t h e m a g n i t u d e (Powles,  K e l l e r and Tregunna bleaching canopy  of light  1984). (1976)  o b s e r v e d c h l o r o s i s and  o f f o l i a g e w i t h i n hours o f removing a r e d a l d e r  from w e s t e r n hemlock.  Acclimation  p l a n t s t r a n s f e r r e d from low t o h i g h 2 days  as  1967).  r a t e and t h e e x t e n t can a c c l i m a t e  (1976)  and western  anatomy a n d p o o r e r r o o t  from unshaded  1967; P h i l l i p s ,  species  (1977)  shade-grown p l a n t s o f D o u g l a s - f i r  desiccation.  Brix,  r a t e b e t w e e n s u n a n d shade  light  of chlorophyll i n c a n be c o m p l e t e i n  ( L o n n e b u r g e t a l . , 1985) a n d t h e e n t i r e  photosynthetic et a l . , 1969). found that  apparatus can a c c l i m a t e C r o o k s t o n e t a l . (1975)  increases  i n light  w i t h i n a week and Gauhl  resulted i n greater  r e s p i r a t i o n w i t h i n a d a y i n some c a s e s .  These  (Hatch  (1976) dark  studies  98  emphasize t h e c o m p l e x i t y o f changes t h a t t a k e p l a c e as p h y s i o l o g i c a l p r o c e s s e s r e s p o n d t o b o t h endogenous and exogenous i n f l u e n c e s .  B u n c e e t a l . (1977) f o l l o w e d  course of photosynthetic  light  acclimation  the time  i n soybean.  f o u n d t h a t when t r a n s f e r r i n g l o w l i g h t - a c c l i m a t e d  plants  from low t o h i g h l i g h t ,  rate,  changes i n p h o t o s y n t h e t i c  They  leaf  d i f f u s i v e c o n d u c t a n c e , l e a f w a t e r p o t e n t i a l , l e a f anatomy, photosynthetic  unit  s i z e , and g l y c o l a t e  were complete w i t h i n  (Powles, 1984).  content,  u n i t s , s p e c i f i c l e a f a r e a and  malate dehydrogenase a c t i v i t y  s h a d e grown p l a n t s  activity  one d a y , w h e r e a s c h l o r o p h y l l  number o f p h o t o s y n t h e t i c  Photoinhibition  oxidase  showed s l o w e r  change.  i s a major l i m i t a t i o n t o t h e a b i l i t y o f  t o acclimate  t o higher l i g h t  Photoinhibition  i n the photosynthetic  capacity  cases i s i r r e v e r s i b l e .  Foliage  environments  r e s u l t s i n sharp  declines  o f f o l i a g e , which i n severe that  d e v e l o p e d i n shade o r  w h i c h h a s b e e n i n s h a d e f o r an e x t e n d e d p e r i o d , i s p a r t i c u l a r l y p r o n e t o p h o t o i n h i b i t i o n when s u d d e n l y to high l i g h t ,  e s p e c i a l l y as water s t r e s s  (Lichtenthaler  e t a l . , 1983; G a u h l ,  1985;  Bjorkman and Powles,  (1986) f o u n d t h a t  1983).  exposed  increases  1976; O g r e n a n d O q u i s t , However, S h a r p a n d B o y e r  i n h i b i t i o n of electron transport  o c c u r r e d a t low water p o t e n t i a l s regardless  function  of the light  exposure. Mid-day r e d u c t i o n s  i n p h o t o s y n t h e s i s have been  a t t r i b u t e d t o a wide v a r i e t y o f e n v i r o n m e n t a l and physiological variables  including photoinhibition  (Helms,  99 1963).  The  d i u r n a l course of p h o t o s y n t h e s i s  c l u e s as t o the a b i l i t y  should  of c o n i f e r s t o a c c l i m a t e  give  to  conditions after release. Ronco  (1975) brought a t t e n t i o n t o the importance of  measures t o a v o i d s o l a r i z a t i o n be  a major part)  of p h o t o o x i d a t i o n photoinhibition e x h i b i t e d by Gorden, 1973; and  (of which p h o t o i n h i b i t i o n  of newly p l a n t e d  seedlings.  The  symptoms  which t y p i c a l l y accompany a l l but (Powles, 1984;  Kok  et a l . , 1965)  minor  are  r e c e n t l y r e l e a s e d suppressed c o n i f e r s Ferguson and Adams, 1980;  Radosevich, 1982).  a b i l i t y t o acclimate  may  often (e.g.  S i e d e l , 1980;  Conard  In s h o r t , -a suppressed c o n i f e r ' s  to the c o n d i t i o n s  c r e a t e d by a r e l e a s e  treatment i s an important determinant of the  release  response. The  o b j e c t i v e of t h i s chapter i s to i n v e s t i g a t e the  r e l a t i o n s h i p between c o n i f e r response to d i f f e r e n t methods  (manual and h e r b i c i d e treatments) and to the  of these treatments. the way  Two  hypotheses are examined:  i n which c o n i f e r s are r e l e a s e d  i n f l u e n c e the r a t e i n which they a c c l i m a t e l i g h t environment, and  timing 1,  that  ( q u i c k l y with manual  treatments or slowly with h e r b i c i d e treatments)  new  release  and  2, t h a t because of  will utilize  the  greater  p h e n o t y p i c p l a s t i c i t y e a r l y i n the year, and because water s t r e s s i s expected to be higher the c a p a c i t y  l a t e r i n the growing season,  f o r suppressed c o n i f e r s a p l i n g s to a c c l i m a t e  r e l e a s e c o n d i t i o n s w i l l decrease throughout the season.  growing  to  1 0 0  These hypotheses were t e s t e d i n a s e r i e s o f manual and herbicide  release  the y e a r .  t r e a t m e n t s conducted a t d i f f e r e n t t i m e s o f  Differences  i n physiological acclimation  ( p h o t o s y n t h e t i c r a t e , l e a f d i f f u s i v e conductance,  response  l e a f water  p o t e n t i a l , and c h l o r o p h y l l c o n t e n t ) and m o r p h o l o g i c a l response  (growth o f f o l i a g e , stem d i a m e t e r , and h e i g h t ) w i l l  be used t o show t h e e f f e c t s o f d i f f e r e n t t r e a t m e n t s on Douglas-fir  release  response.  101 METHODS  A.  Field  treatments  R e l e a s e t r e a t m e n t s a t two examine t h e h y p o t h e s e s . conducted  f o r two  l o c a t i o n s were used  to  A t Haney, r e l e a s e t r e a t m e n t s w e r e  c o n s e c u t i v e y e a r s and were u t i l i z e d f o r  i n t e n s i v e measurements.  Treatments  conducted  R i v e r s i t e were u s e d t o s u p p l y a d d i t i o n a l second year response  of  at the Powell  i n f o r m a t i o n on  the  saplings.  Haney ?  E i g h t e e n 630 m  s u b p l o t s were i d e n t i f i e d w i t h i n  areas  o f t h e s i t e C r e d a l d e r s t a n d t h a t w e r e homogeneous and a t l e a s t 200 The  c o n i f e r s a p l i n g s per  had  ha.  f o l l o w i n g t h r e e t r e a t m e n t p l o t s were e s t a b l i s h e d  each of s i x t r e a t m e n t dates  (May  and J u n e 9, J u l y  7, and S e p t e m b e r 5 i n 1 9 8 4 ) :  1)  2) a m a n u a l t r e a t m e n t , and 3)  an  10, A u g u s t  an u n t r e a t e d c o n t r o l p l o t , herbicide treatment.  The  t h e m a n u a l t r e a t m e n t by c h a i n saws.  Manually  24 and A u g u s t  r e d a l d e r c a n o p y was  felling  at about  18 i n  on  1983,  removed i n  30 cm h e i g h t w i t h  f e l l e d a l d e r stems were removed  from  the research p l o t s to allow greater access during p h y s i o l o g i c a l measurements. r e d a l d e r c a n o p y was  In the h e r b i c i d e treatment,  k i l l e d w i t h an i n j e c t i o n o f 2,4-D  the  amine  9  at about  1.5  m i n height.  A 230 m  measurement p l o t  e s t a b l i s h e d a t the c e n t e r of each t r e a t m e n t p l o t .  was  A l l  c o n i f e r s a p l i n g s w i t h i n t h e measurement p l o t w e r e t a g g e d  (an  102 a v e r a g e o f 17 p e r p l o t ) ,  and f i v e o f t h e s e were c h o s e n a t  random t o be s a m p l e d .  Powell River The s t u d y a r e a c o n s i s t e d o f two c o n t i g u o u s b l o c k s e a c h having five  0.11 h a p l o t s  ( f o u r t r e a t m e n t s and a c o n t r o l )  (see P e n d l and D ' A n j o u , 1 9 8 4 ) . treatment p l o t s  s e t o f 0.11 ha  ( t h e December r e l e a s e t r e a t m e n t )  e s t a b l i s h e d on t h e same s i t e contiguous blocks. of  An a d d i t i o n a l  was  150 m t o t h e n o r t h o f t h e two  The t r e a t m e n t s c o n s i s t e d o f t h e  felling  t h e a l d e r a t f o u r t i m e s i n 1983: 1) J u n e 7 a n d 8, 2)  19 t h r o u g h 2 1 , 3) A u g u s t 30 t h r o u g h  July  S e p t e m b e r 1, a n d 4)  December 27, p l u s an u n t r e a t e d c o n t r o l .  The a l d e r s t e m s  w e r e s m a l l enough t h a t t h e y w e r e l e f t w h e r e t h e y  fell.  Only  9  conifers  i n t h e c e n t e r 230 m  measurement p l o t  o f each  t r e a t m e n t p l o t w e r e i n c l u d e d i n t h e random s e l e c t i o n o f f i v e sample  trees.  B. F i e l d  Measurements  Schedule  o f measurements  The f o l l o w i n g m e a s u r e m e n t s o f t r e e p h y s i o l o g y a n d e n v i r o n m e n t were made s e v e r a l t i m e s  following  treatments.  T y p i c a l l y two t o f o u r s e t s o f m e a s u r e m e n t s w e r e t a k e n t h e f i r s t week a f t e r t h e t r e a t m e n t s .  One o r two o f t h e s e  were  d i u r n a l s e t s o f measurements, t h e r e m a i n i n g were m e a s u r e m e n t s t a k e n i n t h e m o r n i n g o n l y b e t w e e n 0800 a n d  103 1130.  A d d i t i o n a l morning only or d i u r n a l measurements were  t y p i c a l l y taken a f t e r one month and again at the end o f the growing  season  (September-October).  Photosynthetically-active  radiation  Measurement of s p e c i f i c l i g h t c o n d i t i o n s at the time o f the p h o t o s y n t h e t i c d e t e r m i n a t i o n s was with a quantum sensor as d e s c r i b e d i n the methods s e c t i o n o f Chapter 3.  To  c h a r a c t e r i z e the shading o f s p e c i f i c treatments, incoming r a d i a t i o n was i n t e g r a t e d u s i n g a chemical  (anthracene)  procedure d e s c r i b e d i n Chapter 2.  Leaf d i f f u s i v e conductance  and vapor p r e s s u r e d e f i c i t s  Leaf d i f f u s i v e conductance  (three r e p l i c a t e s from t h r e e  s a p l i n g s per p l o t ) and vapor p r e s s u r e d e f i c i t s were determined as d e s c r i b e d i n the methods s e c t i o n of Chapter 3.  Photosynthesis Photosynthetic rates one  ( f i v e r e p l i c a t e s per sample p l o t  from each of f i v e measurement s a p l i n g s ) were measured  u s i n g methods d e s c r i b e d i n Chapter 3.  C h l o r o p h y l l content i n f o l i a g e F o l l o w i n g r e l e a s e treatments at the Haney s i t e ,  and i n  the autumn at both s i t e s , the c h l o r o p h y l l content o f f o l i a g e was determined on both treatment and c o n t r o l t r e e s u s i n g the methods d e s c r i b e d i n Chapter 3.  S e v e r a l twigs were taken  104 from the top third, of -the crown o f each o f three t r e e s i n each measurement p l o t and combined sample. One composite  c h l o r o p h y l l determination  sample  with a composite  was made from each  sample.  Growth a n a l y s i s Growth a n a l y s i s  (methods c i t e d i n Chapter 3)  was  conducted on s i x c o n i f e r s a p l i n g s w i t h i n each measurement p l o t t h a t was biomass was Haney 1983 of 1984.  sampled i n October of 1984.  determined f o r s i x s a p l i n g s  Coarse root  from each of the  and Powell R i v e r r e l e a s e treatments i n the Roots were removed by l o o s e n i n g  the  fall  soil  surrounding the stump and l i f t i n g the r o o t system out. Coarse r o o t s r a r e l y broke during e x c a v a t i o n  and recovery  was  good.  Leaf water p o t e n t i a l s Leaf water p o t e n t i a l s  (three r e p l i c a t e s , one each from  three of the f i v e sample measurement s a p l i n g s per p l o t ) were determined u s i n g methods c i t e d i n Chapter 3.  Data a n a l y s i s Data were subjected  t o an one-way a n a l y s i s of v a r i a n c e .  S i g n i f i c a n c e between treatments was  determined at p<  with the Tukey m u l t i p l e comparisons t e s t  0.05  ( S t o l i n e , 1981).  105  RESULTS  A.  Sapling physiology  I n i t i a l changes i n s a p l i n g p h y s i o l o g y a f t e r r e l e a s e treatments a. 1983  Haney experiments  One  day a f t e r the May  24,  1983  removal of the red a l d e r  canopy i n the manual r e l e a s e treatment,  photosynthetic  rate  and l e a f water p o t e n t i a l were s i g n i f i c a n t l y h i g h e r than  the  c o n t r o l v a l u e s , and c h l o r o p h y l l content had d e c l i n e d 20% from the content  of c o n t r o l f o l i a g e  (Table 13).  no s i g n i f i c a n t change i n l e a f d i f f u s i v e Measurements on day two  There  was  conductance.  a f t e r the treatments  showed  l e a f d i f f u s i v e conductance of the manual treatment  had  risen  s i g n i f i c a n t l y r e l a t i v e to the c o n t r o l , w h i l e l e a f water p o t e n t i a l had  f u r t h e r d e c l i n e d from c o n t r o l v a l u e s .  p h o t o s y n t h e t i c r a t e f o r the manual treatment  Average  remained  s i g n i f i c a n t l y g r e a t e r than the h e r b i c i d e and the c o n t r o l treatments.  However, F i g u r e 8a shows d i f f e r e n c e s i n average  p h o t o s y n t h e t i c r a t e t o be a r e s u l t of h i g h morning v a l u e s . In the afternoon,  gas exchange was  the same f o r a l l the  treatments. One treatment and  month a f t e r the r e l e a s e treatments,  the h e r b i c i d e  showed s i g n i f i c a n t l y higher p h o t o s y n t h e t i c r a t e  l e a f d i f f u s i v e conductance than the c o n t r o l ; however the  h e r b i c i d e treatment  averages were s t i l l  s i g n i f i c a n t l y below  106 Table 13. Mean v a l u e s o f p h o t o s y n t h e s i s , l e a f d i f f u s i v e conductance , l e a f water p o t e n t i a l , and c h l o r o p h y l l content f o r c u r r e n t year Douglas - f i r f o l i a g e from s a p l i n g s r e l e a s e d at Haney on May 24 , 1983 f o l l o w e d through time. photosynthesis Days a f t e r treatment 1, 2 4 7^ 24 3  J  Days a f t e r treatment 1 2 4 7 24  (mgCO, •dm M H 3.2a 3.1a 3.0a 5. 6a 5.2a  2  z  1.2b 1.1b 1.5b 1.4b 3.7b  • hr !) C 1.1b 1.0b 1.6b 1.5b . 8c  l e a f water potential (MPa) M H C -1.6b -2 .2b -1. 9b -1.2b -1.0a  Manual treatment c o n t r o l (C).  -.7a -.8a -. 6a -.7a -. 6a  -. 8a -.7a -.6a -.7a -.7a  leaf diffusive conductance (cm* s ) M H C - 1  .08a .12a .16a .15a .17a  .06a .06b .08b .10b .13b  . 06a . 05b . 07b . 0 6b . 06c  chlorophyll content (mg'g ) M H -1  2.67b 2.63b 2.61b 2.54b 2.33b  (M), h e r b i c i d e treatment  3.44a 3.28a 3.18a 3.32a 2.53b  C 3.32a 3.48a 3.40a 3.46a 3.06a  (H), u n t r e a t e d  p  Mean v a l u e s w i t h i n a row f o l l o w e d with d i f f e r e n t are s i g n i f i c a n t l y d i f f e r e n t (p<0.05). Mean from d i u r n a l measurements.  letters  T  B  I  1  T  1  10  12  14  16  0  J  1  1  1  e  10  12  Time (hr)  Release type  T  14  p  IB  T i m e (hr)  manual release  herbicide release  control  F i g u r e 8a-b. D i u r n a l p a t t e r n s o f p h o t o s y n t h e t i c p h o t o n f l u x d e n s i t y (PPFD), a t m o s p h e r i c v a p o r p r e s s u r e d e f i c i t (D), l e a f d i f f u s i v e c o n d u c t a n c e ( g ^ ) , and p h o t o s y n t h e s i s f r o m t h e May 24, 1983 Haney r e l e a s e t r i a l s , (a) m e a s u r e d May 26, 1983 on 1983 f o l i a g e , (b) m e a s u r e d June 17, 1983 on 1983 f o l i a g e .  108 those  o f t h e manual t r e a t m e n t  content  of the release treatments  control, no  but  t h e manual t r e a t m e n t  longer different  13).  (Table  Chlorophyll  were b o t h b e l o w  the  l e a f water p o t e n t i a l  was  f r o m t h e h e r b i c i d e r e l e a s e and c o n t r o l  values. F i g u r e 8b treatment,  shows t h a t 22  t h e manual t r e a t m e n t  d i f f u s i v e c o n d u c t a n c e no afternoon, day  canopy c o n t i n u e d  on  I n a d d i t i o n , as d e f o l i a t i o n o f  i n the h e r b i c i d e treatment,  the  the  photosynthetic both  rates  the c o n t r o l values.  1983  treatments  i d e n t i c a l to those  established in  w e r e r e p l i c a t e d on a p l o t on A u g u s t 7,  r e s u l t e d i n t h e same i n i t i a l  1983.  This  p a t t e r n of p h y s i o l o g i c a l  d i f f e r e n c e s between t r e a t m e n t s a v e r a g e p h o t o s y n t h e t i c r a t e and and  deficit  showed c o n s i s t e n t l y h i g h e r p h o t o s y n t h e t i c  Release May  leaf  longer d e c l i n e d sharply i n the  l e a f d i f f u s i v e c o n d u c t a n c e r a t e s r o s e so t h a t  treatments than  release  p h o t o s y n t h e t i c r a t e and  despite a r i s i n g vapor pressure  o f measurement.  r a t e and  days a f t e r the  ( T a b l e 14).  Increases  leaf diffusive  in  conductance,  d e c l i n e s i n l e a f w a t e r p o t e n t i a l and c h l o r o p h y l l  content,  were measured i n t h e manual r e l e a s e t r e a t m e n t .  d i u r n a l p a t t e r n o f p h o t o s y n t h e t i c r a t e and c o n d u c t a n c e two  days a f t e r t h e manual t r e a t m e n t  showed h i g h p h o t o s y n t h e t i c r a t e and conductance values afternoon  leaf  leaf  The  diffusive (Fig.  9a)  diffusive  i n the morning, which d e c l i n e d i n the  as d i d t h e May  r e l e a s e upon  treatment.  T a b l e 14. Mean v a l u e s o f p h o t o s y n t h e s i s , l e a f d i f f u s i v e conductance, l e a f water p o t e n t i a l , and c h l o r o p h y l l content f o r c u r r e n t y e a r D o u g l a s - f i r f o l i a g e from s a p l i n g s r e l e a s e d a t Haney on A u g u s t 9, 1983 f o l l o w e d t h r o u g h t i m e . photosynthesis Days a f t e r treatment 1. 2 4 7^ 3  Days a f t e r treatment 1 2 4 7 22  (mgCOo'dm M H x  3.6a 2 .9a 3 . 3a 2 . Oa 2 .4b  2  1.2b . 6b 1.5b 1.1b 2.7a  2  'hr  1  )  C  1.1b .6b 1.6b 1.2b .7c  l e a f water potential (MPa) M H C -2 .8b -2 . 6b -2 .4a -1 .8b -2 .2b  -1.3a -1.2a -1.2a -1.3a -1.5a  Manual t r e a t m e n t c o n t r o l (C).  -1.3a -1.4a -1.1a -1.3a - 1 . 6a  leaf diffusive conductance _1 ) (em's M H C .17a .10a .16a .12a . 11a  . 08b . 04b . 0 9b . 08b . 05b  .09b .04b .10b .09b .14a  chlorophyll content (mg-g ) M H x  2. 61b 1.30b 1.21b 1.28b 1.06b  3.23a 2.89a 2.82a 2.82a 2.46a  (M), h e r b i c i d e t r e a t m e n t  C  3.12a 2.83a 2.89a 2.89a 2.86a  (H), u n t r e a t e d  2  Mean v a l u e s w i t h i n a row f o l l o w e d w i t h d i f f e r e n t a r e s i g n i f i c a n t l y d i f f e r e n t (p<0.05). Mean f r o m d i u r n a l  measurements.  letters  0  J  1  1  1  1  1  B  10  12  14  16  0  i  (  1  (  l  r~  6  8  10  12  14  10  Time (hr) Release type  Time (hr) manual release  herbicide release  control  F i g u r e 9 a - b . D i u r n a l p a t t e r n s o f p h o t o s y n t h e t i c p h o t o n f l u x d e n s i t y (PPFD), a t m o s p h e r i c v a p o r p r e s s u r e d e f i c i t (D) , l e a f d i f f u s i v e c o n d u c t a n c e (g-^) , a n d p h o t o s y n t h e s i s f r o m t h e A u g u s t 18, 1983 Haney r e l e a s e t r i a l s , (a) m e a s u r e d A u g u s t 2 0 , 1983 on 1983 f o l i a g e , (b) m e a s u r e d S e p t e m b e r 1 1 , 1983 on 1983 foliage.  Ill  T h r e e weeks a f t e r t h e A u g u s t r e l e a s e manual t r e a t m e n t  p h o t o s y n t h e t i c r a t e and  ( F i g . 9b) leaf  the  diffusive  conductance values continued the p a t t e r n of d e c l i n i n g e a r l y morning v a l u e s t o values s i m i l a r t o those of u n t r e a t e d c o n t r o l by m i d - a f t e r n o o n . photosynthetic r a t e of the  The  was  s i g n i f i c a n t l y h i g h e r t h a n t h e manual t r e a t m e n t ,  and  s t r o n g l y c o n t r o l l e d by  p o t e n t i a l and  t h r e e weeks. o n l y 37%  levels.  Leaf  c h l o r o p h y l l content of t h e manual  remained s i g n i f i c a n t l y  was  light  the  average  h e r b i c i d e treatment  t o be  from  appeared  water treatment  lower than the other treatments  C h l o r o p h y l l content o f t h e manual of the c o n t r o l values.  Despite  after  treatment  significant  c h a n g e s i n t h e p h o t o s y n t h e t i c r a t e and  leaf  conductance i n the h e r b i c i d e treatment  a f t e r t h r e e weeks,  t h e r e w e r e no  changes i n l e a f water  c h l o r o p h y l l content  b.  1984  Haney  r e l a t i v e to the  potential  and  control.  experiments  A r e p e a t o f t h e 1983 t r e a t m e n t s was  diffusive  conducted  m a n u a l and h e r b i c i d e r e l e a s e i n t h e same s t a n d i n 1984  e x p l o r e i n more d e t a i l t h e e f f e c t s o f t i m i n g on release response.  The  earliest  1984  to  initial  release period  was  J u n e 9, and t h e i m m e d i a t e c h a n g e s i n t h e p h y s i o l o g y b e t w e e n t r e a t m e n t s were s i m i l a r t o t h o s e measured i n e a r l y  1983.  Two  days a f t e r t h e t r e a t m e n t s ,  average p h o t o s y n t h e t i c r a t e  and  l e a f d i f f u s i v e conductance o f t h e manual t r e a t m e n t  were  s i g n i f i c a n t l y g r e a t e r than those of the h e r b i c i d e treatment  112 or the 10a)  control  (Table 15),  showed r a p i d d e c l i n e s  photosynthetic rate the  day.  and  diurnal pattern  from i n i t i a l l y  control  The  measured between the  m a n u a l and  after release  and  had  and  the over  control treatments  d i m i n i s h e d a f t e r two  treatments, average  the weeks.  photosynthetic  (Table  c o n t r o l were not  significant.  and  The  s h a r p mid-day d e c l i n e s  treatment  ( F i g . 9a  and  increased A u g u s t 9,  exhibited  10b).  two  Both the  above c o n t r o l 1984  release  changes i n p h o t o s y n t h e t i c r a t e  pattern  longer  days  herbicide  a f t e r two  a v e r a g e p h o t o s y n t h e t i c r a t e was  30.  days t h a t  and  the  increased  rate  treatment  day  A u g u s t 1983  The  showed  photosynthetic  l e v e l s by  the  after  t r e a t m e n t showed  s i m i l a r t o those measured i n the  diurnal pattern  treatments  l e a f d i f f u s i v e conductance of  l e a f d i f f u s i v e conductance of the had  15).  diurnal  m a n u a l t r e a t m e n t a month a f t e r t r e a t m e n t no  The  the  potential  i n l e a f water p o t e n t i a l between the  of p h o t o s y n t h e t i c r a t e  trees  herbicide  l e a f d i f f u s i v e c o n d u c t a n c e o f a l l t r e a t m e n t s were  Differences  and  and  leaf diffusive  i n l e a f water  s i g n i f i c a n t l y d i f f e r e n t from each other  the  in  manual t r e a t m e n t .  m a n u a l t r e a t m e n t and  difference  A month a f t e r t h e  the  high  treatments continued to increase  f o l l o w i n g weeks.  s e c o n d day  accompanied the  i n photosynthetic rate  conductance between the  and  (Fig.  l e a f d i f f u s i v e conductance e a r l y  content also  Differences  rate  the  S i g n i f i c a n t reductions i n l e a f water p o t e n t i a l  chlorophyll  and  and  initial were  release  period.  (Table  16),  showed a h i g h p h o t o s y n t h e t i c  rate  113 Table 15. Mean v a l u e s o f p h o t o s y n t h e s i s , l e a f d i f f u s i v e conductance, l e a f water p o t e n t i a l , and c h l o r o p h y l l content f o r c u r r e n t year D o u g l a s - f i r f o l i a g e from s a p l i n g s r e l e a s e d at Haney on June 9, 1984 f o l l o w e d through time. photosynthesis Days a f t e r treatment 2 4 15 30  Days a f t e r treatment 1 4 15 30  (mgC0 'dm "hr" ) M H C -2  1  2  1  2.9a 3.5a 5.4a 4.9a  2  .8b 1.2b 1.6b 2.3b  1 .Ob 1 .lb 1 .3b ,7c  l e a f water potential (MPa) M H -1.2b -1.3b -. 8a -. 5a  Manual treatment c o n t r o l (C).  -.6a -.2a -,4a -.3a  leaf diffusive conductance (cm* s ) M H - 1  .07a .16a .18a .18a  .08a .09b .10b .14b  . 09a . 09b . 09b . 0 6c  chlorophyll content (mg-g ) M H x  C -. 5a -,3a -. 5a -.2a  2.62b 2.2 6b 2.57b 2.12b  (M), h e r b i c i d e treatment  3.18a 3.16a 2.92abi 2.74a  C 3.01a 3.12a 3.18a 3.21a  (H), u n t r e a t e d  2  Mean v a l u e s w i t h i n a row f o l l o w e d w i t h d i f f e r e n t are s i g n i f i c a n t l y d i f f e r e n t (p<0.05).  letters  0-J  1  1  i  1  1  1  8  10  12  14  16  18  Time (hr)  Release type  manual release  0  J  1  i  8  10  herbicid_e_release  1  12  Time (hr)  control  F i g u r e lOa-b. D i u r n a l p a t t e r n s o f p h o t o s y n t h e t i c p h o t o n f l u x d e n s i t y (PPFD), a t m o s p h e r i c vapor p r e s s u r e d e f i c i t (D), l e a f d i f f u s i v e c o n d u c t a n c e ( g ) , and p h o t o s y n t h e s i s f r o m t h e June 9, 1984 Haney r e l e a s e t r i a l s , (a) m e a s u r e d June 11, 1984 on 1984 f o l i a g e , (b) m e a s u r e d J u l y 12, 1984 on 1984 f o l i a g e . 1  115 T a b l e 16. Mean v a l u e s o f p h o t o s y n t h e s i s , l e a f d i f f u s i v e conductance, l e a f water p o t e n t i a l , and c h l o r o p h y l l content f o r c u r r e n t y e a r D o u g l a s - f i r f o l i a g e from s a p l i n g s r e l e a s e d a t Haney on A u g u s t 7, 1984 f o l l o w e d t h r o u g h t i m e . photosynthesis Days a f t e r treatment 2 4 15 30  3  3  Days a f t e r treatment 2 4 15 30  (mgC0 'dm 'hr ) M H C - 2  - 1  2  1  2.0a 4.2a 3.4a 1.9a  2  1.0b 1.1b 2.6b 2.2a  l e a f water potential (MPa) M H -2.6b -2.6b -2.6b -2.6b  Manual treatment control (C).  -.7a -.6a -.7a -1.3a  .8b 1.0b 1.2c .9b  leaf diffusive conductance (cm- s ) H M C x  .06a . 14a .11a .08b  .04a .04b .12a .16a  .04a .05b .06b .08b  chlorophyll content (mg'g ) M H l  C -.7a -.6a -. 6a -.8a  2 . 44b 1 .55b 1 .71b .84c  (M), h e r b i c i d e t r e a t m e n t  2.88a 2.77a 2 .58a 2.14b  C 2 . 80a 2 .84a 2 .59a 2 .71a  (H), u n t r e a t e d  ?  Mean v a l u e s w i t h i n a row f o l l o w e d w i t h d i f f e r e n t are s i g n i f i c a n t l y d i f f e r e n t (p<0.05). Mean f r o m  diurnal  measurements.  letters  116  e a r l y i n t h e d a y , f o l l o w e d by a s t e e p No s i g n i f i c a n t  increase  decline  i n leaf diffusive  accompanied t h e i n c r e a s e  (Fig. 11a).  conductance  i n manual t r e a t m e n t  photosynthetic  r a t e a t t h e s e c o n d day measurement. A m o n t h a f t e r t h e A u g u s t 1984 r e l e a s e average p h o t o s y n t h e t i c  r a t e s o f t h e manual and h e r b i c i d e  t r e a t m e n t s w e r e n e a r l y t h e same higher  light  treatment,  (Table  16), despite the  l e v e l s w i t h i n t h e manual t r e a t m e n t  Leaf d i f f u s i v e  lib).  conductance o f f o l i a g e i n t h e manual  t r e a t m e n t was s i g n i f i c a n t l y  lower than t h a t o f f o l i a g e i n  the h e r b i c i d e treatment  (Table  and  o f t h e manual t r e a t m e n t  c h l o r o p h y l l content  significantly  (Fig.  16).  Leaf water p o t e n t i a l remained  lower than both t h e h e r b i c i d e and c o n t r o l .  Unlike the other  release periods,  t h e A u g u s t 1984  h e r b i c i d e t r e a t m e n t showed s i g n i f i c a n t l y photosynthetic  r a t e and l e a f d i f f u s i v e  c o n t r o l a f t e r two weeks.  higher  conductance over t h e  These i n c r e a s e s  were n o t  accompanied by changes i n l e a f water p o t e n t i a l o r c h l o r o p h y l l content  until  c h l o r o p h y l l content  when m e a s u r e d 30 d a y s a f t e r t r e a t m e n t Integrated  light  had decreased  (Table 1 6 ) .  l e v e l s were n o t m e a s u r e d o v e r t h e p e r i o d  a f t e r t h e A u g u s t 1984 h e r b i c i d e r e l e a s e t r e a t m e n t ,  so  comparison w i t h d e f o l i a t i o n rates i n other periods  c a n n o t be  made.  However, c a n o p y d e f o l i a t i o n was o b s e r v e d t o be  particularly  r a p i d on t h e A u g u s t 1984 p l o t .  The d i u r n a l  T 8  1 10  r 11  1 12  1 13  1 14  1 16  0  J  1 8  1 10  Time (hr)  Release t y p e  -i 12  1 14  r 16  Time (hr)  manual release  herbicide release  control  Figure l l a - b . D i u r n a l p a t t e r n s o f p h o t o s y n t h e t i c p h o t o n f l u x d e n s i t y (PPFD), a t m o s p h e r i c v a p o r p r e s s u r e d e f i c i t (D) , l e a f d i f f u s i v e c o n d u c t a n c e (g-^) , a n d p h o t o s y n t h e s i s f r o m t h e A u g u s t 7, 1984 Haney r e l e a s e t r i a l s , (a) m e a s u r e d A u g u s t 9, 1984 on 1984 f o l i a g e , (b) m e a s u r e d S e p t e m b e r 7, 1984 on 1984 foliage.  118 pattern  of photosynthetic  rate f o r the herbicide treatment a  month a f t e r t r e a t m e n t shows t h a t r e l a t i v e l y  small  the  treatment  light conditions  compared t o t h e manual  resulted i n a greatly increased  photosynthetic  changes i n  rate  (Fig. l i b ) .  End o f f i r s t saplings a.  growing season d i f f e r e n c e s i n t h e physiology  a t t r i b u t e d to d i f f e r e n t release  1983 Hanev  treatments.  experiments  T a b l e 17 p r o v i d e s saplings  i n the four  a comparison of the physiology  1983 t r e a t m e n t / d a t e  Average  of the p h y s i o l o g i c a l c h a r a c t e r i s t i c s d i d not  significantly  of the  release  c o m b i n a t i o n s as measured i n September o f 1983. values  of  differ  b e t w e e n e i t h e r o f t h e May t r e a t m e n t s .  The  manual t r e a t m e n t from August c o n s i s t e n t l y d i f f e r e d from t h e h e r b i c i d e t r e a t m e n t and t h e c o n t r o l . Photosynthetic  r a t e and l e a f d i f f u s i v e c o n d u c t a n c e o f  t h e manual t r e a t m e n t c o n t i n u e d  t o d r o p o v e r t h e two  b e t w e e n t h e one-month p o s t - t r e a t m e n t m e a s u r e m e n t s and  t h e end o f September measurements  diurnal pattern  of photosynthetic  rate  (Table  photosynthetic  afternoon  (Table The  depression  herbicide of both  r a t e a n d l e a f d i f f u s i v e c o n d u c t a n c e as  c o m p a r e d w i t h t h e May h e r b i c i d e  14)  ( F i g . 12a) shows t h e  May m a n u a l r e l e a s e t r e a t m e n t and t h e A u g u s t t r e a t m e n t had g r e a t e r  17).  weeks  release.  119  T a b l e 17. Mean d i u r n a l v a l u e s o f p h o t o s y n t h e s i s (Ps) , l e a f d i f f u s i v e c o n d u c t a n c e (g-^) , a n d means o f l e a f w a t e r p o t e n t i a l (wp), a n d c h l o r o p h y l l c o n t e n t ( c h l ) o f D o u g l a s - f i r s a p l i n g s r e l e a s e d a t Haney i n 1983 a s m e a s u r e d S e p t e m b e r 24, 1983.  P s  _  - i  2  Treatment  (mgC0 'dm ^ ' h r )  M May 24 M Aug. 18 H May 24 H Aug. 18 Control  4.6a .3d 4.4a 3.2b 1.3c  1  x  2  2  Manual r e l e a s e treatment (H) .  wp  9i - i (em's ) (MPa) .22a .05c .23a .19ab .14b  (M), h e r b i c i d e  chl (mg'g  -. 6a 2.0b  1  )  -.7a -. 6a  2.36c .98d 2.41c 2.77b 3.28a  release  treatment  -. 6a  Mean v a l u e s w i t h i n a c o l u m n f o l l o w e d w i t h d i f f e r e n t l e t t e r s a r e s i g n i f i c a n t l y d i f f e r e n t (p<0.05).  Time (hr)  Release type  Time (hi)  manual release  herbicide release  Time (hr)  control  F i g u r e 1 2 a - c . D i u r n a l p a t t e r n s o f p h o t o s y n t h e t i c p h o t o n f l u x d e n s i t y (PPFD), a t m o s p h e r i c v a p o r p r e s s u r e d e f i c i t ( D ) , l e a f d i f f u s i v e c o n d u c t a n c e ( g ^ ) , and p h o t o s y n t h e s i s f r o m t h e 1983 Haney r e l e a s e t r i a l s , (a) m e a s u r e d S e p t e m b e r 24, 1983 on 1983 f o l i a g e , (b) m e a s u r e d S e p t e m b e r 7, 1984 on 1983 f o l i a g e , (c) m e a s u r e d S e p t e m b e r 8, 1984 on 1984 f o l i a g e . Box= May 2 4 , 1983 t r e a t m e n t ; t r i a n g l e = A u g u s t 18, 1983 t r e a t m e n t ; s o l i d d o t = u n t r e a t e d c o n t r o l .  121 b.  1984  Haney e x p e r i m e n t s  Treatment d i f f e r e n c e s at the f o r the  1984  treatments are  end  growing  shown i n T a b l e 18.  of photosynthetic  r a t e and  not  d i f f e r e n t f o r the  significantly  of the  season  Mean  values  l e a f d i f f u s i v e c o n d u c t a n c e were manual t r e a t m e n t s  e s t a b l i s h e d i n J u n e and  J u l y , and  photosynthetic  l e a f d i f f u s i v e conductance f o r these  treatments  r a t e and  ( F i g . 13b)  are very  diurnal patterns  similar.  t r e a t m e n t s e s t a b l i s h e d i n A u g u s t and photosynthetic  S e p t e m b e r had  and  Reductions i n l e a f water p o t e n t i a l  treatments.  The  photosynthetic  h e r b i c i d e t r e a t m e n t s were s i m i l a r t o t h o s e o f  m a n u a l t r e a t m e n t s e s t a b l i s h e d i n A u g u s t and 18).  However, t h e  l e a f d i f f u s i v e conductances of  J u l y manual t r e a t m e n t s The  (Table  diurnal pattern  release periods conditions  and  t h e p l o t , and  various  shows a c o n s i s t e n t  higher  1984  nesting  p h y s i o l o g i c a l response  the  (Table  the June  and  greater  herbicide of  the  light  the p h o t o s y n t h e t i c  (Table  18).  environmental  ( F i g 13b).  C h l o r o p h y l l content generally decreased with since h e r b i c i d e treatment  the  18).  of the  time s i n c e treatment, the  rates  September  h e r b i c i d e t r e a t m e n t s were s i m i l a r t o t h o s e o f t h e  the  similar  i n t h e A u g u s t m a n u a l t r e a t m e n t f o l i a g e as  compared t o a l l o t h e r of the  release  r a t e , l e a f d i f f u s i v e conductance,  c h l o r o p h y l l content. were g r e a t e s t  Manual  of  The  longer  level  within  rate. increased  time  122 Table 18. Mean v a l u e s of p h o t o s y n t h e s i s (Ps), l e a f d i f f u s i v e conductance (g-^) , and means of l e a f water p o t e n t i a l (wp), and c h l o r o p h y l l content (chl) of D o u g l a s - f i r s a p l i n g s r e l e a s e d at Haney i n 1984 as measured October 3, 1984.  Treatment M June M Jul. M Aug. M Sept. H June H Jul. H Aug. H Sept. Control i  Ps (mgC0 'dm -hr )  9 10 7 5 9 10 7 5  Manual treatment c o n t r o l (C).  -2  2  4.4a 4.9a 2.3c 2.8bc 2.8bc 3.3b 2.1c 1.6c l.ld  -1  g^ (em's ) -1  .20a .17ab . 05c . 08c .19a . 15b . 18a .13b .07c  wp (MPa) -.4a -1.6b  (M), h e r b i c i d e treatment  -. 3a -. 3a -.4a  _ (mg'g ) c n l  1  -1  2.0 9d 2.29cd 1.19e . 94e 2.34cd 2.54bc 2.70b 2.77b 3.30a  (H), u n t r e a t e d  p  Mean v a l u e s w i t h i n a column f o l l o w e d w i t h d i f f e r e n t l e t t e r s are s i g n i f i c a n t l y d i f f e r e n t (p<0.05).  3 Oct. 1984  „  2000  T  1600 1000-  D-  n-  B  3 Oct. 1984  -o ^  600  a.  O.  •XL  Release t y p e  2  -T  1  1  1  " • : - : - : : - - B  E •a  manual release  herbicide release  —-'8 o i  tn J=  c  E  >  "D  O  ;8:,,  n  -j5r---  ° 8 10  12  Time (hr)  14  10  12  ---A  14  Time (hr)  F i g u r e 13a-b. D i u r n a l p a t t e r n s o f p h o t o s y n t h e t i c p h o t o n f l u x d e n s i t y (PPFD), a t m o s p h e r i c v a p o r p r e s s u r e d e f i c i t (D), l e a f d i f f u s i v e c o n d u c t a n c e ( g ^ ) , a n d p h o t o s y n t h e s i s f r o m t h e 1984 Haney r e l e a s e t r i a l s , (a) m a n u a l r e l e a s e , m e a s u r e d O c t o b e r 3, 1984 on 1984 f o l i a g e , (b) h e r b i c i d e r e l e a s e , m e a s u r e d O c t o b e r 3, 1984 on 1984 f o l i a g e . Box= June 9, 1984 t r e a t m e n t ; r i n g = J u l y 10, 1984 t r e a t m e n t ; t r i a n g l e = A u g u s t 7, 1984 t r e a t m e n t ; d i a m o n d ^ S e p t e m b e r 5, 1984 t r e a t m e n t ; s o l i d d o t = u n t r e a t e d c o n t r o l .  124 C o m p a r i s o n o f t h e p h y s i o l o g y o f s u c c e s s i v e age c l a s s e s o f foliage after release a. 1983 Hanev  experiments  Mean d i u r n a l v a l u e s o f p h o t o s y n t h e t i c r a t e , d i f f u s i v e conductance, of  l e a f water  end  determinations  p o t e n t i a l and c h l o r o p h y l l c o n t e n t t a k e n a t t h e  o f t h e second  treatments  a n d means o f m o r n i n g  leaf  growing  are presented  season  f o r t h e 1983 r e l e a s e  i n Table  19.  I n 1983, t h e  p h o t o s y n t h e t i c r a t e o f t h e August manual t r e a t m e n t significantly the c o n t r o l  was  lower t h a n t h e o t h e r r e l e a s e t r e a t m e n t s and (Table 1 7 ) .  I n 1984, t h e d i f f e r e n c e  between t h e August manual t r e a t m e n t  remained  and t h e o t h e r  t r e a t m e n t s ; h o w e v e r , t h e p h o t o s y n t h e t i c r a t e o f t h e 1983 f o l i a g e i n 1984 was s i g n i f i c a n t l y control values.  higher than  comparable  D i f f e r e n c e s i n p h o t o s y n t h e t i c r a t e between  t h e two May t r e a t m e n t s  and t h e August h e r b i c i d e t r e a t m e n t  t h a t w e r e s e e n i n 1983 h a d d i m i n i s h e d when t h e 1983 f o l i a g e was r e m e a s u r e d i n 1984 ( T a b l e 1 9 ) . P h o t o s y n t h e t i c r a t e f o r t h e 1984 f o l i a g e d i d n o t d i f f e r significantly  between t h e t r e a t m e n t s  on t h e A u g u s t m a n u a l t r e a t m e n t had  significantly  (Table 1 9 ) .  produced  1984 f o l i a g e  trees  that  g r e a t e r average p h o t o s y n t h e t i c r a t e than  t h a t o f t h e 1 9 8 3 - p r o d u c e d f o l i a g e i n 1984. 12c  Only  F i g u r e s 12b a n d  compare t h e S e p t e m b e r 1984 d i u r n a l p a t t e r n s o f  p h o t o s y n t h e t i c r a t e m e a s u r e d i n t h e two age c l a s s e s o f f o l i a g e on t h e 1983 r e l e a s e t r e a t m e n t s . that  F i g u r e 12b shows  f o l i a g e on t h e 1983 A u g u s t m a n u a l t r e a t m e n t  continued  125 T a b l e 19. Mean d i u r n a l v a l u e s o f p h o t o s y n t h e s i s , l e a f d i f f u s i v e c o n d u c t a n c e , a n d means o f l e a f w a t e r p o t e n t i a l , and c h l o r o p h y l l c o n t e n t o f 1983 a n d 1984 f o l i a g e f r o m D o u g l a s - f i r s a p l i n g s r e l e a s e d a t Haney i n 1983 a s m e a s u r e d S e p t e m b e r 7, 1984. photosynthesis  leaf diffusive conductance (em's )  (mgC0 'dm 'hr ) - 2  - 1  - 1  2  83  Treatment M May H May M Aug. H Aug. Control X  2  5. 5a 5.2a 2.1b 4. 9a 1.4c  84  6%  3  6. Oa 9 2 5. 3a 5. 5a 162* 4 .7a -4 1.4b  83  84  4%  .21a .21a .16a .20a .lib  .22a .21a .20a .19a .lib  5 0 25 -5  l e a f water potential (MPa)•  M May H May M Aug. H Aug. Control  chlorophyll content (mg'g ) x  83  84  &%  83  -. 3a -. 5ab -.8c -.4ab -. 6bc  -.5b -.4ab -.5b -. 3a -.7c  67* -20 -38* 25 17  2.35b 2.4 6b 1.12c 2.50b 2.78a  Manual r e l e a s e (H) .  treatment  (M), h e r b i c i d e  84  ft%  2.12c 1.92c 1. 61d 2.45b 3.34a  -10 -22 44* -2 20  release  treatment  ?  Mean v a l u e s w i t h i n a c o l u m n f o l l o w e d w i t h d i f f e r e n t l e t t e r s a r e s i g n i f i c a n t l y d i f f e r e n t (p<0.05). 9  P e r c e n t d i f f e r e n c e b e t w e e n 1983 a n d 1984 f o l i a g e v a l u e s . * i n d i c a t e s s i g n i f i c a n t d i f f e r e n c e (p<0.05) b e t w e e n f o l i a g e age classes. J  126 to  d e c l i n e sharply i n p h o t o s y n t h e t i c r a t e throughout  the  day,  reaching values at or below those of the c o n t r o l .  1984  p h o t o s y n t h e s i s p a t t e r n s o f 1983  release treatments  are s i m i l a r  foliage  from t h e  t o each other  to  release treatment  each other except  and  leaf diffusive  manual t r e a t m e n t defoliated  s a p l i n g s ( F i g . 12c)  f o r drops  effect  are  of  similar  i n t h e day.  from t h e August  Shading  from t h e  canopy i n t h e h e r b i c i d e t r e a t m e n t  have l i t t l e  foliage  i n both photosynthetic r a t e  conductance of f o l i a g e  late  other  ( F i g . 12b).  D i u r n a l p h o t o s y n t h e t i c p a t t e r n s o f t h e 1984 t h e 1983  The  i n a l l o w i n g 1983  and  standing  appeared t o  1984  foliage  to  a c h i e v e t h e same p h o t o s y n t h e t i c r a t e as t h e m a n u a l r e l e a s e treatment  (Table 19).  Leaf d i f f u s i v e  ( T a b l e 19)  showed no  treatments  f o r b o t h 1983  and  on  1983  1984-produced  f o r the s p e c i f i c treatments. this relationship  c o n d u c t a n c e and t r e a t m e n t  foliage  foliage.  s i g n i f i c a n t d i f f e r e n c e s between  t h e August manual t r e a t m e n t diffusive  averages  s i g n i f i c a n t d i f f e r e n c e s between r e l e a s e  F u r t h e r , t h e r e w e r e no classes of foliage  conductance  a t t h e end  of the  1983  For a l l but  between  resembled  age  leaf  measurements  growing  season  (Table  17) . In  1983,  leaf diffusive  manual t r e a t m e n t treatments  was  treatment growing  v e r y l o w as c o m p a r e d t o a l l o t h e r  (Table 17).  c o n d u c t a n c e o f 1983  conductance f o r the August  Differences in leaf  foliage  between t h e August manual  and t h e o t h e r t r e a t m e n t s  season.  Leaf water  diffusive  d i m i n i s h e d over the  potential  1984  remained s i g n i f i c a n t l y  127 higher  as c o m p a r e d t o t h e  m a n u a l t r e a t m e n t s had  The  treatments  significant  d i f f e r e n c e s b e t w e e n 1984 release treatments  other  19).  p a t t e r n of c h l o r o p h y l l content  d i f f e r e n c e s between  1983  treatments.  t r e a t m e n t showed a s i g n i f i c a n t content  b.  1983  b e t w e e n age  Powell  provided  increase  River  decline in  August manual in chlorophyll  experiments e s t a b l i s h e d at Powell  a r e p l i c a t i o n of the  changes i n the  study  f o l i a g e o f t h e Haney 1983  w i t h a w i d e r range of r e l e a s e p e r i o d s .  of  River  release t r i a l s , As  was  seen i n  f o l i a g e f r o m Haney m a n u a l r e l e a s e t r e a t m e n t s  19),  the photosynthetic  r a t e and  the  e s t a b l i s h e d l a t e i n the  were c o n s i d e r a b l y year  ( J u n e and  December h a d c o n t r o l and 1984  (The  treatments,  River plots  growing season  (August) in  the  manual r e l e a s e conducted i n  a photosynthetic  rate intermediate  August r e l e a s e t r e e values.)  foliage photosynthetic  the  (Table  lower than those r e l e a s e d e a r l i e r  July).  but  leaf diffusive  conductance of f o l i a g e of t r e e s i n the Powell 20)  in  year-to-year  1983  (Table  foliage,  class.  Manual r e l e a s e t r i a l s 1983  The  1984  and  e x c e p t t h e August h e r b i c i d e t r e a t m e n t d i d not as much as t h e May  1983  f o l i a g e from the  t r e a t m e n t s were s i m i l a r c o m p a r i n g t h e  1984  The  l e a f water p o t e n t i a l  f o l i a g e and  (Table  19).  (Table  between  In c o n t r a s t t o  r a t e f r o m t h e Haney 1983  the photosynthetic  rate of the  the  1984  Powell  the  release River  128 T a b l e 2 0 . Mean d i u r n a l v a l u e s o f p h o t o s y n t h e s i s , l e a f d i f f u s i v e c o n d u c t a n c e , a n d means o f l e a f w a t e r p o t e n t i a l , and c h l o r o p h y l l c o n t e n t o f 1983 a n d 1984 f o l i a g e f r o m D o u g l a s - f i r s a p l i n g s r e l e a s e d m a n u a l l y i n 1983 a t P o w e l l R i v e r a s m e a s u r e d on J u n e 20, 1 9 8 4 . photosynthesis  leaf diffusive conductance (em's )  (mgC0 'dm 'hr ) -2  1  84  A%  1  2  Treatment  83  June 7 J u l y 19 Aug. 30 Dec. 30 Control  3.7a 4.0a .4d 2.2b 1.0c  1  83  2  4.6a 24* 4.6a 15 2.6b 550* 3.7a 68* .8c -20  chlorophyll content (mg'g ) 84 83  . 17a .19a .0 9b .0 9b .0 6b  84  a%  .13a .14a .15a .08b .05b  -24* -26* 21* -11 -17  x  June 7 J u l y 19 Aug. 30 Dec. 30 Control  2.32b 2 .18b .68d 1.76c 3.16a  1.81b 1.82b 1.33c 1.83b 3.40a  a% -22* -17* 96* -4 8  Mean v a l u e s w i t h i n a c o l u m n f o l l o w e d w i t h d i f f e r e n t l e t t e r s a r e s i g n i f i c a n t l y d i f f e r e n t (p<0.05). P e r c e n t d i f f e r e n c e b e t w e e n 1983 a n d 1 9 8 4 . * i n d i c a t e s s i g n i f i c a n t d i f f e r e n c e (p<0.05) b e t w e e n f o l i a g e age c l a s s e s . 2  129 f o l i a g e remained s i g n i f i c a n t l y d i f f e r e n t between the and  other treatment The  foliage  August  periods.  d i u r n a l p a t t e r n of photosynthesis  i n the  from the P o w e l l R i v e r r e l e a s e t r e a t m e n t s  1983 ( F i g . 14a)  showed r a p i d d r o p s i n r a t e s f r o m m o r n i n g m e a s u r e m e n t s f o r t h e A u g u s t and December t r e a t m e n t s . t o what was treatments The foliage  observed  i n the  a t Haney i n 1983  days a f t e r manual r e l e a s e  ( F i g . 9) and  1984  ( F i g . 11).  d i u r n a l p a t t e r n of photosynthetic r a t e f o r the from the P o w e l l R i v e r r e l e a s e t r e a t m e n t s  shows h i g h e r m o r n i n g v a l u e s to the  first  This pattern i s similar  1983  and t h e 1984  foliage. foliage  The  as  ( F i g . 14b) compared  Leaf d i f f u s i v e conductance of the from the P o w e l l R i v e r treatments  s i m i l a r between t r e a t m e n t s , (Table 20).  f o r a l l treatments  1984  June and  except  1983  were  f o r the August r e l e a s e  J u l y f o l i a g e had  showed  s i g n i f i c a n t d e c l i n e s i n l e a f d i f f u s i v e conductance between the  1983  and  1984  age  c o n t e n t b e t w e e n 1983 foliage  and  f r o m t h e J u n e and  s i g n i f i c a n t decreases August treatment  B.  classes. 1984  Changes i n c h l o r o p h y l l foliage varied greatly.  July release periods both  i n c h l o r o p h y l l content  foliage  had  i n 1984;  increased i n chlorophyll  The  the  content.  S a p l i n g morphology  Changes i n f o l i a g e s p e c i f i c  l e a f area the growing  season  of  release Few  significant  reductions i n specific  o c c u r r e d t h e same y e a r as t h e t r e a t m e n t .  leaf  area  Only f o l i a g e  from  Release type manual release control  Time (hr)  Time (hr)  F i g u r e 14a-b. D i u r n a l p a t t e r n s o f p h o t o s y n t h e t i c p h o t o n f l u x d e n s i t y (PPFD), a t m o s p h e r i c v a p o r p r e s s u r e d e f i c i t (D) , l e a f d i f f u s i v e c o n d u c t a n c e (g-jj , a n d p h o t o s y n t h e s i s f r o m t h e 1983 P o w e l l R i v e r r e l e a s e t r i a l s , (a) m e a s u r e d J u n e 20, 1984 on 1983 f o l i a g e , (b) m e a s u r e d J u n e 2 0 , 1984 on 1984 f o l i a g e . Box= J u n e 7, 1983 t r e a t m e n t ; c i r c l e = J u l y 19, 1983 t r e a t m e n t ; t r i a n g l e ^ A u g u s t 30, 1983 t r e a t m e n t ; diamond= December 27, 1984 t r e a t m e n t ; s o l i d d o t = u n t r e a t e d control.  t h e 1983 May m a n u a l a n d t h e 1984 J u n e m a n u a l  treatments  d e c l i n e d i n s p e c i f i c l e a f a r e a by t h e end o f t h e growing  season  after  Changes i n growth a. 1983 Haney  release  two g r o w i n g  first  (Table 21).  seasons  after  release  experiments  T a b l e 22 shows t h a t s i g n i f i c a n t d e c r e a s e s l e a f area occurred i n f o l i a g e  o f t h e August  h e r b i c i d e t r e a t m e n t s b e t w e e n 1983 and 1984.  in specific  manual  and  The p a t t e r n s  s i g n i f i c a n t d i f f e r e n c e s b e t w e e n 1984 m e a s u r e m e n t s  were  i d e n t i c a l between s p e c i f i c l e a f a r e a , r e l a t i v e l e a f growth  rate,  and shoot t o r o o t r a t i o .  t r e a t m e n t s were d i f f e r e n t b o t h were d i f f e r e n t characteristic,  area  Where t h e m a n u a l  from t h e h e r b i c i d e t r e a t m e n t s ,  from t h e c o n t r o l .  In each  t h e h e r b i c i d e t r e a t m e n t gave i n t e r m e d i a t e  values. R e l a t i v e diameter growth  r a t e was g r e a t e s t i n t r e e s  f r o m t h e May m a n u a l r e l e a s e t r e a t m e n t  (Table 22).  w e r e no d i f f e r e n c e s b e t w e e n t h e r e l a t i v e d i a m e t e r  There growth  r a t e s o f t h e o t h e r r e l e a s e t r e a t m e n t s , w h i c h were a l l significantly  greater than the c o n t r o l .  Height growth  only s i g n i f i c a n t l y greater than the c o n t r o l  was  f o r t h e May  manual r e l e a s e t r e a t m e n t .  b . 1983 P o w e l l R i v e r  experiment  The P o w e l l R i v e r r e l e a s e t r e a t m e n t s a l l h a d significantly  l o w e r 1984  foliage  s p e c i f i c l e a f area  than  132 Table 21. Mean values o f c u r r e n t year s p e c i f i c l e a f area (SLA), f o r D o u g l a s - f i r s a p l i n g s r e l e a s e d at Haney i n 1983 and 1984 measured at the end o f the growing season o f release. (cnr-g  Treatment — 1983 — M May M Aug. H May H Aug. Control X  89b 188a 173a 184a 170a  x  )  — 1984 — 2  M June M July M Aug. M Sept. H June H July H Aug. H Sept. Control  Manual treatment (M), h e r b i c i d e treatment c o n t r o l (C) . 1  ?  110b 168a 175a 184a 162a 178a 182a 169a 176a  (H),  column f o l l o w e d with d i f f e lues within a l e Mean t t e r s v aare s i g n i f i c a n t l y d i f f e r e n t (p<0.05)  133 Table 22. Mean values of s p e c i f i c l e a f area (SLA), r e l a t i v e l e a f growth r a t e (RLGR), r e l a t i v e diameter growth r a t e (RDGR), r e l a t i v e height growth r a t e (RHGR), and shoot t o root r a t i o (S/R) f o r D o u g l a s - f i r s a p l i n g s r e l e a s e d at Haney i n 1983 and measured at the end o f t h e 1984 growing season.  M May M Aug. H May H Aug. Control  SLA (cm *g • ) a% 72c -19 79c -58* 111b -36* 123b -33* 183a 8  M May M Aug. H May H Aug. Control  RHGR (cirryr • cm ) .52a .34b .42ab .45ab .25b  Treatment 1  2  2  3  1  Manual treatment c o n t r o l (C).  1  ^  (<?'yr  G R  _i  9" )  1.66a 1.72a 1.12b 1.21b .45c  (mirryr  'mm  )  .89a .62b .52b .41b .31c  S/R (g'g ) 3.1c 3.5c 4.1b 4.3b 5.6a  (M), h e r b i c i d e treatment  (H), untreated  p  Mean v a l u e s w i t h i n a column f o l l o w e d w i t h d i f f e r e n t l e t t e r s a r e s i g n i f i c a n t l y d i f f e r e n t (p<0.05). Percent d i f f e r e n c e between 1983 (Table 22) and 1984. * i n d i c a t e s s i g n i f i c a n t d i f f e r e n c e (p<0.05) between f o l i a g e age c l a s s e s . 3  134 c o n t r o l at the  end  of the  1984  R e l a t i v e l e a f g r o w t h r a t e and  growing season  greatest  f o l l o w e d by  July treatment.  growth r a t e nor  increases  Neither  than the  control.  s i g n i f i c a n t d i f f e r e n c e s between the r a t e s o f any  i n the  June  of the  l e a f area  f o r the  There were  r e l a t i v e height  r e l e a s e t r e a t m e n t s and  the  rate  release,  relative  r e l a t i v e diameter growth r a t e  r e l e a s e were g r e a t e r  23).  r e l a t i v e diameter growth  b o t h showed t h e the  (Table  August  no growth  control.  135 Table 23. Mean values o f s p e c i f i c l e a f area (SLA) o f 1984 f o l i a g e , r e l a t i v e l e a f growth r a t e (RLGR), r e l a t i v e diameter growth r a t e (RDGR), and r e l a t i v e height growth r a t e (RHGR) f o r D o u g l a s - f i r s a p l i n g s r e l e a s e d manually at Powell R i v e r i n 1983 and measured at t h e end o f the 1984 growing season. Release date  § _i (cm *g )  RLGR (g'yr ^'g ^)  RDGR (mm'yr mm  June 7 J u l y 19 Aug. 30 Control  87c 90bc 112b 150a  1.48a .80b .32c .30c  .55a .38b .18c .25c  L A  2  1  RHGR (cm'yr "cm June 7 J u l y 19 Aug. 30 Control  1,  1  )  )  .39a .51a .4 6a .30a  Mean v a l u e s w i t h i n a c o l u m n f o l l o w e d w i t h d i f f e r e n t l e t t e r s a r e s i g n i f i c a n t l y d i f f e r e n t (p<0.05).  136 DISCUSSION  A.  E f f e c t o f t r e a t m e n t and The  t i m i n g on  suppressed D o u g l a s - f i r i n the  presented  h e r e showed an a b i l i t y  increases  i n l i g h t made a v a i l a b l e by  t i m i n g of the distinct  consequences f o r the  growth.  The  on t h e  1985;  continued  to the  T r e a t m e n t and  had  of  increased release  rate, extent  and  timing  t i m i n g b o t h had  an  f r o m t h e m a n u a l r e l e a s e t r e a t m e n t s showed, T r e g u n n a , 197 6;  of p l a n t s switched  e n v i r o n m e n t c a n be  rapid.  conductance lagged  a day  photosynthetic  c h l o r o p h y l l content  13,  15,  as  Lonneburg et a l . ,  initial  changes i n  from a low t o a h i g h  the  light  Changes i n l e a f d i f f u s i v e o r two  rate, despite  and  b e h i n d changes i n  changes i n l e a f water p o t e n t i a l  i n manual r e l e a s e t r e a t m e n t s  S a m p l i n g was  too  infrequent  to detect  sequence of response i n the h e r b i c i d e treatments, increases  the  of a c c l i m a t i o n a f t e r release  ( K e l l e r and  16).  maintenance  achievement of  Hatch e t a l . , 1969), t h a t the  physiology  However,  c h a r a c t e r i s t i c s measured.  extent  have  experiments  r e l a t i o n s h i p b e t w e e n t h e p h y s i o l o g i c a l and  morphological  others  release.  a c c l i m a t i o n of suppressed t r e e s to  of s p e c i f i c changes.  Results  s e r i e s of  to r a p i d l y u t i l i z e  r a t e s and  conditions varied according  R a t e and  response  r e l e a s e treatment i n r e l a t i o n t o season  elevated photosynthetic  effect  release  i n photosynthetic  r a t e were measured  (Tables the  but  full  when  (usually  after  a b o u t one m o n t h ) , l e a f d i f f u s i v e c o n d u c t a n c e h a d  increased,  but not l e a f water p o t e n t i a l .  Powles  (1984)  summarized e v i d e n c e w h i c h s u g g e s t s t h a t t h e r a t e and e x t e n t of l i g h t a c c l i m a t i o n stress.  i s greater  i n t h e absence o f moisture  The r e l a t i v e l y l o w e r m o i s t u r e s t r e s s o f t h e  h e r b i c i d e t r e a t m e n t s c o m p a r e d t o t h e m a n u a l t r e a t m e n t s may have been i m p o r t a n t i n a l l o w i n g released release  saplings t o acclimate conditions  Differences  foliage  on h e r b i c i d e  to a greater  extent  to the  (Table 1 9 ) .  i n t h e s t a g e o f l e a f d e v e l o p m e n t may h a v e  been i m p o r t a n t i n l i m i t i n g t h e r e s p o n s e o f f o l i a g e i n release  treatments conducted i n t h e l a t t e r part  growing season leaves the part  (Tables  t o acclimate  17, 18, a n d 2 0 ) .  to a different  The a b i l i t y o f  l i g h t regime vary  degree o f d i f f e r e n t i a t i o n o f t h e i n d i v i d u a l of leaf.  P e a r c e and Lee (1969), and J u r i k  (1979) f o u n d t h a t t h e g r e a t e s t a c c l i m a t i o n was when l e a v e s  of the  potential  with  leaves or et a l .  for light  were e x p a n d i n g .  Prioul et a l .  (1980) f o u n d t h a t t h e m a g n i t u d e o f t h e m o d i f i c a t i o n s p o s s i b l e when l e a v e s  are exposed t o a d i f f e r e n t  light  i n t e n s i t y v a r i e d w i t h t h e stage o f development, and t h e specific physiological  or s t r u c t u r a l parameter  Changes i n t h e environment as a r e s u l t release  considered.  o f t h e manual  t r e a t m e n t s w e r e e x t r e m e c o m p a r e d t o c h a n g e s i n most  published  reports  increased  light intensity.  physiological  studying  acclimation  o f shade f o l i a g e t o  However, t h e r a t e s a t w h i c h  changes o c c u r r e d  i n released  saplings  were  138 s i m i l a r t o those observed i n s t u d i e s i n more c o n t r o l l e d environments with a v a r i e t y of p l a n t s 1976;  Lonneburg et a l . , 1985;  When any  water r e l a t i o n s and  to r e l e a s e  initial  photosynthetic  r e l e a s e response was  detectable,  r a t e s were higher than the c o n t r o l .  r e l e a s e d with the manual treatment e a r l y i n the season maintained and a c t u a l l y continued elevated photosynthetic This trend represented to t h e i r new  Tregunna,  Hatch et a l . , 1969).  Response of s a p l i n g photosynthesis, c h l o r o p h y l l content  ( K e l l e r and  Saplings  growing  to increase  the  r a t e measured f o l l o w i n g r e l e a s e . an i n c r e a s i n g a c c l i m a t i o n of s a p l i n g s  environment.  In c o n t r a s t , those s a p l i n g s  r e l e a s e d manually l a t e r i n the growing season tended to have constant  or d e c l i n i n g p h o t o s y n t h e t i c  i n a b i l i t y to i n c r e a s e or maintain  r a t e s over time.  photosynthesis  This  suggests  t h a t the e f f e c t s of p h o t o i n h i b i t i o n were more dominant than acclimation.  D i f f e r e n c e s i n the response of manual  treatments r e f l e c t e d s i g n i f i c a n t r e d u c t i o n s  i n the  ability  of the suppressed s a p l i n g s to a c c l i m a t e t o r a p i d and changes i n the unshaded c o n d i t i o n i n the  major  second h a l f of the  growing season. C o n i f e r responses to the h e r b i c i d e treatment were l e s s dependent on treatment t i m i n g than were the manual treatments.  Response was  c l o s e l y c o r r e l a t e d to i n c r e a s e s i n  the l i g h t environment as the red a l d e r canopy d e f o l i a t e d . However, without comparative p h o t o s y n t h e t i c  measurements  139 between s a p l i n g s from the treatments under c o n t r o l l e d c o n d i t i o n s , d i f f e r e n c e s i n c a p a c i t y at a given time cannot be  determined. A lowering  of the s u s c e p t i b i l i t y of the r e l e a s e d  t o mid-day p h o t o s y n t h e t i c  rate reductions  allowed average p h o t o s y n t h e t i c  through time  r a t e s to i n c r e a s e  e a r l y season manual r e l e a s e treatments and the treatments.  Data given  show t h a t r e d u c t i o n s  i n Figure  12a  and  trees  i n the  herbicide  Tables 17 and  i n l e a f water p o t e n t i a l s and  18  increased  l e a f d i f f u s i v e conductance accompanied reduced tendency towards p h o t o s y n t h e t i c water s t r e s s was  rate declines.  c e n t r a l t o the d i u r n a l f l u c t u a t i o n s i n the  observed p h o t o s y n t h e t i c In general,  This suggests t h a t  rate.  the r e s u l t s from a l l r e l e a s e  treatments  show t h a t l e a f d i f f u s i v e conductance i n r e l e a s e d  Douglas-fir  d e c l i n e s with i n c r e a s i n g atmospheric moisture demand, t h a t these r e d u c t i o n s a lowering Tregunna  and  i n d i f f u s i v e conductance c o i n c i d e with  of p h o t o s y n t h e t i c  rate.  However, K e l l e r  and  (197 6) found t h a t when suppressed western hemlock  s e e d l i n g s were r a p i d l y exposed to an unshaded environment, l e a f conductance d i d not d e c l i n e , to the severe detriment l e a f water p o t e n t i a l .  K e l l e r and  Tregunna  (197 6)  t h a t shade f o l i a g e of r e l e a s e d hemlock maintains  of  suggested relatively  h i g h l e a f conductance t o m a i n t a i n a f a v o r a b l e  internal C O 2  concentration  photosynthetic  to support the higher p o s s i b l e  r a t e s r e s u l t i n g from the i n c r e a s e  in light.  Bunce  (1981)  found that the s e n s i t i v i t y of l e a f conductance t o change i n  140 vapor pressure  d e f i c i t was  negatively correlated with  l e n g t h of the root system per u n i t of p l a n t area. reasonable  to hypothesize  that the enlarged  photosynthetic  d e c l i n e s i n those  photosynthetic  rate  ( T a b l e 20)  that recovery assured  19 and  20),  f o l l o w i n g years' root growth  and  i n the  22).  relatively  high photosynthetic  f o l l o w i n g the  those  photosynthetic This  suggests  l e s s severe  i n treatments  performance  a  below  perhaps because  following photoinhibition.  intensities  of  photosynthetic  of f o l i a g e g e n e r a l l y d e c l i n e s  exposure to greater l i g h t  had  a pattern  significantly  of saplings i n other treatments,  c h l o r o p h y l l content  Foliage  match.  declines in  chlorophyll concentrations  extensive photooxidation  of  r a t e , w h i c h by t h a t t i m e ,  that maintained  l e a f w a t e r p o t e n t i a l and  new  (Table  r e l e a s e treatment  previous-year-foliage could nearly  r a t e had  poor  f o l i a g e slowly increased over time.  the year  high  low  f o l i a g e w i t h i n the  When p h o t o i n h i b i t i o n was  developing  Saplings  and  from the e f f e c t s o f p h o t o i n h i b i t i o n i s not  manual treatment) , the p h o t o s y n t h e t i c  current-year  the  foliage  (Table  w i t h t h e d e v e l o p m e n t o f new  environment. 13,  and  a t b o t h Haney  over time from the e f f e c t s  rate i s also reflected  performance of the  reduced  treatments.  R i v e r showed p o o r r e c o v e r y  of p h o t o i n h i b i t i o n (Tables  on  t h u s mid-day  S a p l i n g s r e l e a s e d i n A u g u s t o f 1983 Powell  It i s  root systems  s a p l i n g s from the e a r l y r e l e a s e t r e a t m e n t s s u s c e p t i b i l i t y t o w a t e r s t r e s s and  the  increases  of  The  as  (Boardman  the  141 1977) .  Water s t r e s s g e n e r a l l y  p h o t o i n h i b i t i o n and 1983;  P o w l e s and  i s thought t o encourage both  photooxidation  (Gauhl,  B j o r k m a n , 1983) .  Low  reduce r a t e s of pigment formation al.,  1975,  1976).  reduced w i t h the Kozlowski  Further,  Osmond,  l e a f water p o t e n t i a l s  (Hemming, 1965;  stomatal  Alberte  c o n t r o l can  be  d e s t r u c t i v e l o s s of c h l o r o p h y l l  and  continued  (Davies  released  a f t e r June were u n a b l e t o  growing season.  Also,  by p h o t o s y n t h e t i c  i f f o l i a g e i s damaged  r a t e and  of the  i t may  e n v i r o n m e n t by  (Table  20),  and  (Table  23). ability  indicated  i n f l u e n c e the  t r e e to produce f o l i a g e t h a t  u t i l i z e the  (as  following  l e a f w a t e r p o t e n t i a l ) , as  R i v e r August r e l e a s e ,  increased  t h i s w i l l be  can  in  fully  photosynthetic  rate  r e f l e c t e d i n lower growth  of f o l i a g e from s a p l i n g s  i n d i c a t i o n that before  d e v e l o p m e n t may  allow  e n v i r o n m e n t a l change. anatomy and  i n the  early  of the  J u r i k e t a l . (197 9) can  l e a f t o more a c c u r a t e l y  conditions.  J u l y , continued  However, P a t t e r s o n  be  modified  reflect  to  showed t h a t during  leaf  leaf  s t r u c t u r a l change i n response  photosynthesis  the  future  g r o w i n g s e a s o n manual t r e a t m e n t t o d e c r e a s e i n s p e c i f i c a r e a i s an  to  change  l e a f area s i g n i f i c a n t l y u n t i l the  The  and  release  foliage specific  ability  greatly  chlorophyll loss.  stem growth response t o  Saplings  Powell  et  1974) , p o s s i b l y p r o v i d i n g a p o s i t i v e f e e d - b a c k  l o w w a t e r p o t e n t i a l s and  Foliage  197 6;  leaf  expansion  the p r e v a i l i n g l i g h t  (1980) c a u t i o n s  that  some  142 apparent changes i n s p e c i f i c l e a f a r e a w i t h may r e s u l t increased result high  from w e i g h t added by i n c r e a s e d l e a f volume.  Increases  increased  s t a r c h and n o t  i n weight could  from a d d i t i o n s o f c u t i c l e d e p o s i t i o n  evaporative  conditions  increased  as o b s e r v e d by K e l l e r  and biomass a l l o c a t i o n  ( T a b l e 22)  partitioning  (Brix,  foliage  saplings.  (Silvius,  1 9 6 7 ; Webb, 1977) o f  p l a n t s accompany t h e t r a n s i t i o n t o i n c r e a s e d intensities.  (1973).  r o o t g r o w t h on r e l e a s e d  Major s h i f t s i n t h e photosynthetic 1979)  also  encouraged by  D a t a f r o m t h e 1983 r e l e a s e e x p e r i m e n t s indicate greatly  light  light  Shaded D o u g l a s - f i r p r o d u c e and m a i n t a i n  a t t h e expense o f r o o t s  (Drew a n d F e r r e l l , 1 9 7 7 ;  Webb, 1 9 7 7 ) .  Because l i g h t s u p p r e s s e d p l a n t s have a l a r g e  shoot-to-root  r a t i o , i t has been s u g g e s t e d t h a t  growth r e s p o n s e by r e l e a s e d stress  t r e e s may b e due t o m o i s t u r e  ( H e r r i n g and E t h e r i d g e ,  from c o n t r o l l e d  a poor  1976; K o t o r ,  environments support t h i s  1972).  Studies  hypothesis  (Magnussen, 1 9 8 1 ; M a g n u s s e n a n d P e s c h l ,  1981).  release,  near t h e surface o f  root  the mineral  systems were c o n c e n t r a t e d  soil  and s a p l i n g s  c o u l d be e a s i l y  growth f o l l o w i n g r e l e a s e would a l l o w lodging,  lodged.  exposure t o wind and p r e c i p i t a t i o n , herbicide-released  saplings  Root  saplings to resist  w h i c h w o u l d be i m p o r t a n t t o t h e c o n t i n u e d  of both the manually- released trees  overstory  Before  i n resisting  survival increased  and a l s o t o t h e  i n avoiding  begins t o break-up and lodge.  damage when t h e  143 Larger  rooting surfaces  i n c r e a s i n g the  supply  are probably  of moisture  l e a f d i f f u s i v e conductance  important  to support  the  (thus p h o t o s y n t h e t i c  in  greater rates)  and  growth r a t e s observed i n the p o s i t i v e response t o c o n i f e r release.  An  i n c r e a s e i n root growth i s perhaps  prerequisite to increases diameter growth  (Table  low p h o t o s y n t h e t i c observed that the senesce  i n l e a f area growth r a t e  22).  Where t r e a t m e n t s  r a t e and  1968;  be  b e e n r e p o r t e d by  G o r d o n , 1973;  Emmingham an  Leaf  on t h e  ( B e l l o n and  and  Tucker  f u t u r e growth of s a p l i n g s .  water p o t e n t i a l s (Tables  17  and  20)  (Tables  a l s o suggested a delay  22  and  i n the  23).  an  activity  and  impact  with low  leaf  a l s o showed a p o o r l e a f a r e a two H o y e r and  Belz  r e l e a s e response of  seasons (1984) suppressed  D o u g l a s - f i r r e l e a s e d manually from red a l d e r throughout  the  season.  Production  o f new  l e a f area  to  demand.  Those t r e a t m e n t s  a b i l i t y t o i n c r e a s e i n d i a m e t e r and  if  may  response t o help adjust the c o n i f e r shoot  t r e e s t h a t showed p o o r p h o t o s y n t h e t i c  growing  and  i n l e a f area  p h y s i o l o g i c a l c o n d i t i o n a f t e r r e l e a s e had  after release  to  Kowalski,  Emmingham, 1 9 7 7 ) .  root r a t i o to increased evaporative The  a t Haney  (1977) s u g g e s t e d t h a t r e d u c t i o n s  important  was  abscission after conifer  others  T u c k e r and  i t  c l a s s e s would begin  S e p t e m b e r 1984  P o w e l l R i v e r August 1983).  and  resulted in  l e a f water p o t e n t i a l ,  o l d e r f o l i a g e age  ( e . g . A u g u s t 1983,  r e l e a s e has  a  is particularly  a c c l i m a t i o n o f shade f o l i a g e i s l i m i t e d a f t e r  important release.  144 B u i l d i n g of sun-acclimated late  f o l i a g e area  i n the growing season i s not  current-year  ( i f set before  the  growth r a t e s are  activity,  e i t h e r the  release treatment),  low,  released  o n l y h a n d i c a p p e d by  foliage photosynthetic  d e t e r m i n a t e buds w h i c h r e f l e c t  on t r e e s  but  poor  also  by  shaded c o n d i t i o n  where l e a f  area  or the p h y s i o l o g i c a l s t r e s s of  ( i f buds d e v e l o p e d a t t h e t i m e o f r e l e a s e ) .  The  release  generally  more c o n s i s t e n t p h y s i o l o g i c a l s t a t u s o f s a p l i n g s f o l l o w i n g release  i n the h e r b i c i d e r e l e a s e treatments i s r e f l e c t e d i n  t h e more c o n s i s t e n t and following release.  intermediate  Stein  growth  (1985) f o u n d t h a t  D o u g l a s - f i r r e l e a s e d w i t h h e r b i c i d e s show growth three r e l e a s e and  B.  intermediate manual  control trees.  timing.  r e l a t i v e r e s p o n s e o f s a p l i n g s t o manual  h e r b i c i d e r e l e a s e t r e a t m e n t s was season of the treatment. s t r o n g l y support the i n the  suppressed  y e a r s a f t e r r e l e a s e as c o m p a r e d w i t h  S e l e c t i o n o f r e l e a s e t r e a t m e n t and The  increases  h i g h l y d e p e n d e n t on  B o t h p h y s i o l o g i c a l and  conclusion  and the  growth  that saplings released  data early  g r o w i n g s e a s o n r e s p o n d e d more f a v o r a b l y t o m a n u a l  r e l e a s e than those r e l e a s e d manually l a t e r i n the s e a s o n o r t h a n t h o s e r e l e a s e d by some p o i n t midway t h r o u g h t h e response diminished marginal  and  herbicides.  growing season,  However,  have been t h r e a t e n e d .  and The  s u r v i v a l of the  at  release  to the p o i n t at which i n i t i a l  delayed,  growing  growth  was  released trees  may  herbicide-release  treatment,  145 although  r e s u l t i n g i n slower  response because of the  delay  i n t r e a t m e n t e f f e c t on e n v i r o n m e n t , g a v e more p r e d i c t a b l e release  responses.  The  s e l e c t i o n of a release treatment should  t h e t r e a t m e n t t i m i n g and crop t r e e suppression. longer  the  a l s o the As  d e g r e e and  g r o w i n g s e a s o n , t h e more c r i t i c a l  less than 5 to  the  duration  t h e s e e x p e r i m e n t s showed,  s a p l i n g s developed under the  D o u g l a s - f i r t h a t had  consider  the  not  h a v e had  the  method.  n o t b e e n s u p p r e s s e d f o r as  6 y e a r s ) may  the  canopy t h r o u g h  release  of  long  such a  (eg.  severe  r e l e a s e response, because the magnitude of a c c l i m a t i o n would not  h a v e b e e n as g r e a t ; t h e  shading) c o u l d determine the More i n f o r m a t i o n s h a d i n g on t h e  on t h e  l e v e l of suppression  (degree  amount o f a c c l i m a t i o n  i n f l u e n c e o f d e g r e e and  increased predictive a b i l i t y  and  confidence  in  required.  duration  acclimation process could provide  of  of  for anticipating  response to the t i m i n g of treatments.  C h a p t e r s 2 and  3  provide  examination of  leaf  area  some o f t h i s  of successive  ratio,  or the  information.  l e a f age  The  classes, the  shoot-to-root  r a t i o o f stem d i a m e t e r t o stem h e i g h t  g i v e e v i d e n c e as t o t h e h i s t o r y o f s a p l i n g s ' The  could  suppression.  s a p l i n g s t h a t w e r e r e l e a s e d a t Haney were  considered  severely  considerable  time.  s u p p r e s s e d and  had  T h e i r r e l e a s e r e s p o n s e may  extreme example of r e l e a s e response. River t r i a l s  been f o r a  i l l u s t r a t e how  represent  However, t h e  s i m i l a r r e s p o n s e s can  an  Powell occur i n  146 s a p l i n g s w i t h a s h o r t e r h i s t o r y and  l e s s e r degree  of  suppression. The to the  phenology of the  H o y e r and aim  i n the  Belz  (1984) r e p o r t e d  of minimizing  w o u l d be  f r e e from l i g h t  optimum p e r i o d  period  the  a t r e a t m e n t window  competition.  with  a f t e r manual  B a s e d on  of August.  a series  these authors suggested that  f o r r e d a l d e r c u t t i n g was T r e a t m e n t s on  f a i l e d to provide  sprouting.  on  timing.  t h u s m a x i m i z i n g the p e r i o d t h a t young c o n i f e r s  red alder c u t t i n g t r i a l s ,  end  greatest  red alder resprouting  and  the  i t s susceptibility  s e l e c t i o n o f manual t r e a t m e n t  cutting,  and  and  c o n t r o l treatment i s t y p i c a l l y the  consideration  the  competitor  are  e i t h e r side of  applied,  the  between e a r l y J u l y  as g o o d a c o n t r o l o f  When h e r b i c i d e s  this  alder  susceptibility  c o n i f e r crop i s of immediate importance, because of  h a z a r d o f damaging newly e x p a n d i n g f o l i a g e . treatment timing phenology.  consideration  Thus,  i s u s u a l l y much more c o g n i z a n t  Successful  conifer release  of the b i o l o g y  of  obviously  of both the  of  crop  of the  herbicide crop  requires  and  competitor. C o s t and  e f f e c t i v e n e s s of release  importance, but  r e l i a b l e data are  t h a t compares t h e found t h a t the either basal  cost  cost  saw  In a r a r e  brushing  was  Miller  also  of  study (1984)  l e s s than  o r stem i n j e c t i o n w i t h h e r b i c i d e s  an A p p a l a c h i a n h a r d w o o d f o r e s t . the  scarce.  of r e l e a s e treatments,  of chain  spraying  treatment are  in  Manual t r e a t m e n t s a l s o have  a d v a n t a g e o f e a s e i n i d e n t i f y i n g any  untreated  areas.  147 However, manual c u t t i n g o f a l d e r u s u a l l y r e s u l t s i n sprouting light  w h i c h can  (Harrington  quickly r e e s t a b l i s h competition  1984,  H o y e r and  Belz  (1984) .  t r e a t m e n t s o f r e d a l d e r , r e t u r n t r e a t m e n t s may especially  i f conifer release  A d d i t i o n a l t r e a t m e n t s may  be  In manual be  required,  response i s delayed.  a l s o be  required with  i n j e c t i o n s s i n c e i n d i v i d u a l t r e e s may a p p l i c a t i o n may  for  insufficient  be  herbicide  missed or  to provide  the  the  desired  level  of c o n t r o l .  C.  The  e c o l o g i c a l i m p l i c a t i o n s of release  The  e c o l o g i c a l i m p l i c a t i o n s of the  r e l e a s e treatments r e l a t e to the p r o c e s s e s are  c h a n g e d and  the  t o e x p a n d t h e i r c a n o p i e s and and  only  t y p e and  r a t e at which  timing  environmental crop  trees  r o o t s t o occupy the  new  space  increases  The  light,  removal of a but  may  probably results i n increases Kimmins  in available soil  (1983) showed t h a t t h e  a l d e r canopy w i t h h e r b i c i d e s m i n e r a l i z a t i o n r a t e s and  response i s delayed, the pulse  of increased  may  be  lost  from the  p o t e n t i a l competitors  only site,  last and  one  If conifer  o r two  the  of release  nutrient growing  w i l l p e r h a p s be  r a t h e r t h a n by  red  soil  concentrations  soil.  a v a i l a b i l i t y w h i c h may  and  removal of a  a v a i l a b l e n u t r i e n t s w i t h i n the  soil  nutrients.  resulted i n higher  increased  red  increase  m o i s t u r e t h r o u g h reduced canopy e v a p o t r a n s p i r a t i o n  B i g l e y and  of  c a p a b i l i t y of the  capture u n u t i l i z e d resources.  a l d e r canopy not  treatments  seasons  utilized  released  trees.  by  148  The l o n g e r  the delay,  alder or other continue  species  the greater will  t h e chance t h a t  e s t a b l i s h a dominant canopy and  t h e growth suppression  of the Douglas-fir.  The r a t e o f c a n o p y r e m o v a l may ecological  succession  sprouting  also influence the  of non-crop species.  g r a s s e s were o b s e r v e d t o i n c r e a s e  Shade t o l e r a n t  under h e r b i c i d e  treated  r e d a l d e r c a n o p i e s a t Haney, w h e r e a s Rubus u r s i n u s p a r v i f l o r u s r e a d i l y e s t a b l i s h e d i n openings created manual t r e a t m e n t s .  Control  o f non-crop species  may be an i m p o r t a n t c o n s i d e r a t i o n considered heavily,  a n d Rubus by t h e  composition  where c o n i f e r r e l e a s e i s  i n a r e a s where w i l d l i f e n e e d s s h o u l d  o r where p o t e n t i a l c o m p e t i t o r s  be w e i g h t e d  are of concern.  CONCLUSIONS  1.  Suppressed  conditions 2.  growth 3.  season  by r e l e a s e  determined  acclimation  to  i n relation  to the  treatments.  of the release  Manual  release  treatments  future  treatments  physiological  condition  and  after  June  strongly  showed t h e  of photoinhibition.  Herbicide  treatment  treatment  timing  5.  increases  Large  saplings 6.  r a p i d l y began  rate.  effects 4.  created  The t i m i n g  growing  Douglas-fir  that  Height  response.  than  response  manual  i n root  was  a poor  less  dependent  on  release. growth  had the greatest  growth  was  were  positive  indicator  indicative of response of i n i t i a l  to  release.  release  150 CHAPTER 5 A P P L I C A T I O N OF FINDINGS AND  CONCLUSIONS  F o r e s t v e g e t a t i o n management h a s e m e r g e d a s a r e s e a r c h priority  and as a r e c o g n i z e d  subdiscipline of forestry.  W i t h t h i s a t t e n t i o n h a s come a p r o f u s i o n o f new i n f o r m a t i o n on t h e r e l a t i o n s h i p b e t w e e n young c o n i f e r s a n d a s s o c i a t e d non-crop v e g e t a t i o n . managers, t h i s  I n o r d e r t o be o f p o t e n t i a l b e n e f i t t o  information should strengthen  b a s i s o f t h e v e g e t a t i o n management p r o c e s s .  the ecological Solving the  p r o b l e m s f a c i n g l a n d managers due t o c o m p e t i t i o n  from non-  c r o p v e g e t a t i o n i n young p l a n t a t i o n s i n v o l v e s t h r e e  phases:  1) t h e r e c o g n i t i o n o f a weed p r o b l e m , 2) p r e d i c t i o n o f f u t u r e c o m p e t i t i v e o u t c o m e s a n d 3) s e l e c t i o n a n d a p p l i c a t i o n of treatments. and  The f o l l o w i n g d i s c u s s e s t h e s e t h r e e  r e l a t e s them t o i n f o r m a t i o n p r e s e n t e d i n t h e p r e v i o u s  three  chapters.  1. R e c o g n i t i o n The  o f the existence of a problem.  r e c o g n i t i o n o f what l e v e l o f c a n o p y / r o o t  encroachment c o n s t i t u t e s s u f f i c i e n t control, in  phases  remains p r i m a r i l y  competition t o warrant  subjective.  Competing v e g e t a t i o n  f o r e s t p l a n t a t i o n s changes c o n s i d e r a b l y t h r o u g h t i m e and  the t r a n s f e r o f i n f o r m a t i o n from p l a c e t o p l a c e  i s risky.  Many p u b l i s h e d r e p o r t s i n f o r e s t v e g e t a t i o n management give poor d e s c r i p t i o n s o f t h e c o m p e t i t i v e studied.  still  environment  A major o b s t a c l e t o t h e r e c o g n i t i o n o f s i g n i f i c a n t  151  c o m p e t i t i v e s i t u a t i o n s i s our  i n a b i l i t y to describe  i n f l u e n c e o f c o m p e t i n g v e g e t a t i o n on c r o p t r e e s . t h e immense v a r i a t i o n i n s p e c i e s and occur,  the  Because  s i t e combinations  that  r e c o g n i t i o n o f p o t e n t i a l problems are dependent  the extent of experience plantation.  An  the  individual assessing  understanding  o f t h e c a n o p y g r o w t h and  to b e t t e r assess the competitive nature  on  the  e n v i r o n m e n t r e l a t i o n s h i p s d e s c r i b e d i n t h e t h e s i s may persons  of  of  light help  deciduous  canopies. I n d e s c r i b i n g t h e c o m p e t i t i o n e n v i r o n m e n t , i t has shown t h a t l i g h t q u a l i t y and extent independently  and  q u a n t i t y c a n v a r y t o some  t h a t shade  characteristics,  i n c l u d i n g t h e s e a s o n a l c y c l e , may  be  M i x t u r e s of species would present  considerable  for descriptive  been  species  specific. complexity  purposes.  I t i s c l e a r from r e s u l t s p r e s e n t e d  in this thesis  that  t h e B e e r - L a m b e r t l a w a p p l i e d t o t h e c a n o p y as a w h o l e i s a poor d e s c r i p t i o n of the succession of environments a s e e d l i n g would encounter canopy.  w h i l e growing  A s i n g l e salmonberry  different  composition  and  through  c a n o p y has  The  and  salmonberry  horizons of  very  a d e s c r i p t i o n o f them s h o u l d  able to r e f l e c t the heterogeneity i n s p e c i f i c l e a f angle,  a  conifer  leaf  d i s t r i b u t i o n that occurs w i t h i n the  be  area, canopy.  r e s u l t s g i v e n h e r e show t h a t a s p e c i f i c h e i g h t i n  t h e canopy w i l l have a s u c c e s s i o n o f d i f f e r e n t over time.  Since the l i g h t  w i t h i n a deciduous  environments  environment at a g i v e n  canopy changes through  time,  position  survey  152 methods w h i c h e s t i m a t e c o v e r a g e and canopy encroachment should consider the v e r t i c a l they  are describing.  d i s t r i b u t i o n o f the canopies  Changes i n l i g h t q u a l i t y w i t h canopy  d e v e l o p m e n t a n d t h e s u b s e q u e n t e f f e c t on c o n i f e r g r o w t h a r e r a r e l y c o n s i d e r e d i n t h e assessment o f deciduous competition. salmonberry quality  shrub  T h i s work h a s shown t h a t e a r l y g r o w t h o f canopies  q u i c k l y e s t a b l i s h shade t h a t has l i g h t  a l t e r e d from t h e unshaded c o n d i t i o n .  These  r e d u c t i o n s i n l i g h t q u a l i t y may n o t be c o n s i d e r e d  important  on t h e i r own, b u t f u t u r e w o r k s h o u l d a l s o e x a m i n e t h e e f f e c t s of these  shifts  i n light  quality  2. P r e d i c t i o n o f f u t u r e c o m p e t i t i v e  on c o n i f e r  growth.  interactions.  I n o r d e r t o make d e c i s i o n s c o n c e r n i n g t h e c o n t r o l o f c o m p e t i n g v e g e t a t i o n , one must p r e d i c t t h e r e l a t i v e o f c o m p e t i t i o n on f u t u r e c u m u l a t i v e understanding  growth.  An  o f s p e c i e s shade t o l e r a n c e i s v e r y  to a n t i c i p a t i n g competitive situations.  impact  important  Selection of  c o n i f e r s p e c i e s i s one o f t h e m a n a g e r s ' most p o w e r f u l i n e s t a b l i s h i n g p l a n t a t i o n s i n areas Use  o f grand  hazard.  f i r i n t h e c o a s t a l D o u g l a s - f i r and Western  hemlock zones l o o k s v e r y p r o m i s i n g kept  of high brush  tools  i n check.  i fanimal  damage c a n b e  Western hemlock i s a l s o a good  alternative  t o D o u g l a s - f i r , p a r t i c u l a r l y where advance r e g e n e r a t i o n c a n be  utilized.  C a u t i o n s h o u l d b e u s e d when t h e p o t e n t i a l  growth i n low l i g h t o f a s p e c i e s i s determined u s i n g n e u t r a l d e n s i t y shade and/or c o n t i n u o u s  from r e p o r t s shade.  The  153 a s s i m i l a t i o n o c c u r r i n g d u r i n g the season canopies at  a r e l e a f l e s s may  sites,  s e e d l i n g s t o grow  from measurements o f  i s of prime importance  the p r e d i c t i v e  b o t h t h e c r o p and  the l i t e r a t u r e may  deciduous  e n v i r o n m e n t i n summer.  Because shading  of  allow overtopped  f a s t e r r a t e s t h a n w o u l d be e x p e c t e d  the l i g h t  when  d i f f e r by  on p r o d u c t i v e  f o c u s i s on t h e r e l a t i v e h e i g h t competitor.  T h e r e i s some e v i d e n c e  t h a t p a t t e r n s o f canopy h e i g h t site.  In the absence o f t e s t e d i n d i c e s  knowledge o f s p e c i e s combinations  and  s i t e typing should help i n  in  development  m o d e l s , t h e f o r e s t e r must d e p e n d on r e c o g n i t i o n and  Ecological  growth  specific  or  previous  sites.  simplifying  i n f o r m a t i o n t r a n s f e r and p r o j e c t i n g i n t o t h e f u t u r e f o r a number o f s i l v i c u l t u r a l p r a c t i c e s Henderson, i n p r e s s ) .  (e.g. B i g l e y  Understanding  and  differences in  v e g e t a t i o n d e v e l o p m e n t c a n be u s e f u l i n a n t i c i p a t i n g assigning treatment  3.  S e l e c t i o n and  and  priorities.  application of  treatments.  Much p r o g r e s s has b e e n made i n r e c e n t y e a r s i n t h e of  treatment  herbicide  vegetation.  allow greater s p e c i f i c i t y Continued  f o r mechanical  very important of  i n v e g e t a t i o n management.  f o r m u l a t i o n s , d e l i v e r y e q u i p m e n t , and  experience  tools  technology  treatments.  i n reducing  New  testing problem  d e v e l o p m e n t o f b o t h h a n d and  killing  area  power  of undesired vegetation i s a l s o  for maintaining s e l e c t i v i t y  and  flexibility  154 Results  given  here demonstrate  i n treatment timing  strategy  one s i d e o f a c o n f l i c t  for red alder release.  r e s u l t s i n d i c a t e t h a t t h e chances o f poor r e l e a s e increase the  over t h e growing season.  August  My  response  and September a r e  b e s t months t o m a n u a l l y c u t r e d a l d e r t o m i n i m i z e  resprouting  (Harrington,  1984 a n d H o y e r  from a p h y s i o l o g i c a l p o i n t time t o release  and B e l z ,  o f view, t h i s  1984), b u t  i s a l s o t h e worst  overtopped Douglas-fir.  I f done p r o p e r l y ,  manual r e l e a s e  b e t h e method  of choice  i n most c a s e s .  planning,  w o r k e r t r a i n i n g a n d s u p e r v i s i o n may be l o w e r .  consequences  Growth  should  response i s r a p i d and  o f both poor a l d e r s p r o u t i n g  c o n t r o l and  r e l e a s e t i m i n g have been i l l u s t r a t e d e x p e r i m e n t a l l y Powell  River  Also  at the  site.  as c o n i f e r a c c l i m a t i o n t o shade  f o l i a g e i s more numerous a n d e x t r e m e ) the  The  increases  one c a n c o n c l u d e  l i t e r a t u r e t h a t t h e t i m i n g a n d mode o f r e l e a s e  becomes more c r i t i c a l . showing t h e s i g n s  (shade from  likely  When o v e r t o p p e d c o n i f e r s a r e n o t y e t  o f suppression,  greater  r e l e a s e method and t i m i n g a r e l i k e l y .  flexibility in  155 LITERATURE CITED A l b e r t e , R. S., E.L. F i s c u s and A.W. W a y l o r . 1975. The e f f e c t s o f w a t e r s t r e s s on t h e d e v e l o p m e n t o f t h e p h o t o s y n t h e t i c apparatus i n green leaves. Plant P h y s i o l . 55:317-321. A l b e r t e , R.S., P.R. M c C l u r e and J . P . T h o r n b e r . 1976. Photosynthesis i n t r e e s , organization of c h l o r o p h y l l and p h o t o s y n t h e t i c u n i t s i z e i n i s o l a t e d gymnosperm chloroplasts. P l a n t P h y s i o l . 58:341-344. A l l a r d , H.A. 1947. L i g h t i n t e n s i t y s t u d i e s i n Canaan V a l l e y , WV. C a s t e n e a 12:63-74. A n d e r s o n , M.C. 1964. S t u d i e s of the woodland l i g h t c l i m a t e (II) Seasonal v a r i a t i o n i n l i g h t c l i m a t e . J . E c o l . 52:643-663. A n d e r s o n , M.C. 1966. S t a n d s t r u c t u r e and l i g h t p e n e t r a t i o n ( I I ) A t h e o r e t i c a l a n a l y s i s . J . A p p l E c o l . 3:41-54. A r a k i , M. 1980. D i f f e r e n c e i n s i z e , s p e c i f i c l e a f a r e a and i n c l i n a t i o n o f l e a v e s among l e a f l a y e r s i n O u e r c u s and C e l t i s leaves. T r a n s . 92nd. Mtg. J a p . F o r . S o c . 233234. A r a k i , M. 1985. The v e r t i c a l p r o f i l e o f l i g h t i n t e n s i t y i n a f o r e s t stand. I. L i g h t - t r a n s m i s s i o n c o e f f i c i e n t of p a r t i a l f o l i a g e and i t s e s t i m a t i o n . J . J a p . F o r . Soc. 67:1-10. A r m i t a g e , A.M. and H.M. Vines. 1982. Net photosynthesis, d i f f u s i v e r e s i s t a n c e , and c h l o r o p h y l l c o n t e n t o f s h a d e t o l e r a n t and s u n - t o l e r a n t p l a n t s grown u n d e r d i f f e r e n t l i g h t regimes. H o r t . S c i . 17:342-343. A t k i n s o n , W.A., B.T. Bormann and D.S. D e B e l l . 1979. Crop r o t a t i o n o f D o u g l a s - f i r and r e d a l d e r : A p r e l i m i n a r y b i o l o g i c a l and e c o n o m i c a s s e s s m e n t . B o t . Gaz. 140 suppl.: s 102-107. A u s s e n a c , G. 1973. m o r p h o l o g y and 30:375-392.  E f f e c t o f d i f f e r e n t m i c r o c l i m a t e s on t h e s t r u c t u r e on n e e d l e s . Ann. S c i . F o r .  B a l d o c c h i , D., B. H u t c h i s o n , D. M a t t , and R. M c M i l l e n . 1984. Seasonal v a r i a t i o n s i n the r a d i a t i o n regime w i t h i n an o a k - h i c k o r y f o r e s t . A g r i c . and F o r . M e t e o r . 33:177-191.  156 B a r b e r , H.W. Jr. salmonberry Washington. S e a t t l e , WA,  1976. An a u t o e c o l o g i c a l s t u d y o f (Rubus s p e c t a b i l i s . P u r s c h ) i n W e s t e r n Ph.D. D i s s e r t a t i o n , U n i v . o f Wash., 154 p.  B e l l o n , S. and M. K o w a l s k i . 1968. The c o u r s e o f g r o w t h i n the regeneration a f t e r uncovering. Z e s z y t Naukowe S z k o l y Glownej Gospodarstwa Wiejskiego w Warszawie ( L e s n i c t w o ) 10:41-54. B i g l e y , R.E. and R.L. Graham. In p r e p a r a t i o n . The l i g h t microclimate w i t h i n red a l d e r stands of d i f f e r e n t density. B i g l e y , R.E. and J.A. H e n d e r s o n . I n p r e s s . E f f e c t s of s l a s h b u r n i n g on p l a n t s u c c e s s i o n and t i m b e r s t a n d establishment. H a n l e y D. and J . Kamenga (eds.) P r o c e e d i n g s o f The b u r n i n g d e c i s i o n . S e a t t l e WA. April 5-7, 1988. B i g l e y , R.E. and J.P. K i m m i n s . 1983. H e r b i c i d e e f f e c t s on ecosystem n i t r o g e n l o s s . Paper presented t o : Proc. Amer. Soc. F o r . C o n v e n t i o n , 16-20 O c t . 1983, Portland OR. B j o r k m a n , 0. and M.M. Ludlow. 1972. C h a r a c t e r i z a t i o n of t h e l i g h t c l i m a t e on t h e f l o o r o f a Q u e e n s l a n d rainforest. Carnegie I n s t . , Dept. P l a n t B i o l . 19711972 Ann. Rep.:85-94. B j o r k m a n , 0. and S.B. P o w l e s . 1983. I n h i b i t i o n of p h o t o s y n t h e t i c r e a c t i o n s under water s t r e s s : Interaction with l i g h t l e v e l . P l a n t a 164:226-235 B l a c k , H.C, E . J . Dimock I I , J . E v a n s , and J.A. Rochelle. 1979. A n i m a l damage t o c o n i f e r o u s p l a n t a t i o n s i n O r e g o n and W a s h i n g t o n . P a r t 1. a s u r v e y 1 9 6 3 - 1 9 7 5 . R e s . B u l l . 25 O r e g o n S t a t e U n i v . S c h o o l o f F o r e s t r y . 45 p. B l a c k m a n , G.E. 1962. The l i m i t o f p l a n t p r o d u c t i v i t y . Rep. E. M a i l i n g Res. S t n . 1 9 8 6 : 3 9 - 4 0 . B o a r d m a n , N.K. 1977. C o m p a r a t i v e p h o t o s y n t h e s i s o f sun shade p l a n t s . Ann. Rev. P l a n t P h y s i o l . 2 8 : 3 5 5 - 3 7 7 . Brix,  H. 1967. An a n a l y s i s o f d r y m a t t e r p r o d u c t i o n D o u g l a s - f i r seedlings i n r e l a t i o n to temperature l i g h t i n t e n s i t y . Can. J . B o t . 4 5 : 2 0 6 3 - 2 0 7 2 .  of and  B u n c e , J.A., D.T. P a t t e r s o n , M.M. P e e t and R.S. Alberte. 1977. L i g h t a c c l i m a t i o n d u r i n g and a f t e r l e a f expansion i n soybean. P l a n t P h y s i o l . 60:255-248.  and  157  Canada S o i l S u r v e y Committee. 1970. c l a s s i f i c a t i o n f o r Canada. Can.  The s y s t e m o f s o i l D e p t . A g r i c , 249 p.  Christy, E.J. 1986. E f f e c t o f r o o t c o m p e t i t i o n and on g r o w t h o f s u p p r e s s e d w e s t e r n h e m l o c k (Tsuaa heterophvlla). V e g e t a t i o 65:21-28.  shading  C l o u g h , J.M., R.S. A l b e r t e and J.A. T e e r i . 1979. P h o t o s y n t h e t i c a d a p t a t i o n o f Solanum d u l c a m a r a L. t o sun and shade e n v i r o n m e n t s : II. Physiological c h a r a c t e r i z a t i o n of p h e n o t y p i c response t o environment. P l a n t P h y s i o l . 64:25-30. C o n a r d , S.G. and R.S. R a d o s e v i c h . 1982. Growth r e s p o n s e o f w h i t e f i r t o d e c r e a s i n g s h a d i n g and r o o t c o m p e t i t i o n by Montane C h a p a r r a l s h r u b s . F o r . S c i . 28:309-320. Crookston, 1975. 16.  R.K., K . J . T r e h a r n e , P. L u d f o r d and J . L . Ozbun. Response o f beans t o s h a d i n g . C r o p S c i . 15:412-  D a n i e l , T.W., J.A. Helms and F.S. B a k e r . 1979. Principles of S i l v i c u l t u r e . 2d e d . M c G r a w - H i l l Book Co., New Y o r k , NY, 500 p. D a v i e s , W.J. and T.T. K o z l o w s k i . 1974. Stomatal o f f i v e woody a n g i o s p e r m s t o l i g h t i n t e n s i t y humidity. Can. J . B o t . 52:1525-1534.  responses and  D e l R i o , E., and A. B e r g . 1979. S p e c i f i c l e a f area of D o u g l a s - f i r r e p r o d u c t i o n as a f f e c t e d by l i g h t and n e e d l e age. F o r . S c i . 25:183-186. D i e r a u f , T.A. 1977. R e s e a r c h s t u d i e s on r e s p o n s e t o r e l e a s e i n t h e Commonwealth o f V i r g i n i a . Unpublished r e p o r t on f i l e , D i v . o f F o r . , D e p t . o f C o n s e r v . C h a r l o t t e s v i l l e , VA. Dore, W. G. 1958. 39:151-152.  A  simple chemical  light  meter.  Ecology  Drew, A.P. and W.K. Ferrell. 1977. Morphological acclimation to l i g h t intensity i n Douglas-fir seedlings. Can. J . B o t . 55:2033-2042. Drew, A.P., and W.K. Ferrell. 1979. S e a s o n a l changes i n the water balance of D o u g l a s - f i r (Pseudotsuaa m e n z i e s i i ) s e e d l i n g s grown u n d e r d i f f e r e n t l i g h t intensities. Can. J . B o t . 57:666-674. D u n l a p , J.M., and J.A. Helms. 1983. F i r s t - y e a r growth o f p l a n t e d D o u g l a s - f i r and w h i t e f i r s e e d l i n g s u n d e r d i f f e r e n t shelterwood regimes i n C a l i f o r n i a . For. E c o l . and Manang. 5:255-268.  158  Emmingham, W.H., a n d R.H. W a r i n g . 1974. C o n i f e r g r o w t h under d i f f e r e n t l i g h t environments i n t h e S i s k i y o u M o u n t a i n s o f S o u t h w e s t e r n Oregon. Northwest S c i . 47:88-99. Emmingham, W.H., a n d R.H. W a r i n g . 1 9 7 7 . An i n d e x o f p h o t o s y n t h e s i s f o r comparing f o r e s t s i t e s i n western Oregon. C a n . J . F o r . R e s . 7:165-174. F e d e r e r , C.A., a n d C.B. T a n n e r . 1966. S p e c t r a l d i s t r i b u t i o n of light i n the forest. E c o l o g y 47:555560. F e r g u s e n , D.E. a n d D.L. Adams. 1980. R e s p o n s e o f a d v a n c e grand f i r r e g e n e r a t i o n t o o v e r s t o r y removal i n n o r t h e r n Idaho. F o r e s t S c i . 26 ( 4 ) : 5 3 7 - 5 4 5 . F i s h e r , B. C. a n d C. M e r r i t t . 1 9 7 3 . The a n t h r a c e n e - i n benzene c h e m i c a l l i g h t meter. P r o c . I n d i a n a Acad. S c i . 161:155-161. F l o y d , B.W., J.W. B u r l e y , a n d R.D. N o b l e . 1978. F o l i a r d e v e l o p m e n t e f f e c t s on f o r e s t f l o o r l i g h t q u a l i t y . F o r . S c i . 24:445-451. F o w e l l s , H.A. 1965. S i l v i c s o f f o r e s t t r e e s o f t h e U n i t e d States. USDA A g r i c . Handbook 2 7 1 . Fowle, C D . , 1 9 4 3 . S t u d i e s i n methods f o r c o n t r o l l i n g grouse browse. P r e l i m i n a r y r e p o r t , B.C. F o r e s t S e r v i c e 15 p . F r e y m a n , S. 1 9 6 8 . S p e c t r a l d i s t r i b u t i o n o f l i g h t i n f o r e s t s o f t h e D o u g l a s f i r zone o f s o u t h e r n B r i t i s h Columbia. C a n . J . P l a n t S c i . 48: 3 2 6 - 3 2 8 . F r y , D.J., a n d I . D . J . P h i l l i p s . 1977. P h o t o s y n t h e s i s o f c o n i f e r s i n r e l a t i o n t o annual growth c y c l e s and d r y matter production. I I . Seasonal photosynthetic c a p a c i t y and mesophyll u l t r a s t r u c t u r e i n A b i e s g r a n d i s . P i c e a s i t c h e n s i s . Tsuga h e t e r o p h y l l a and L a r i x l e p t o l e p i s g r o w i n g i n S.W. E n g l a n d . Physiol. P l a n t . 40:300-306. G a u h l , E. 1 9 7 6 . P h o t o s y n t h e t i c r e s p o n s e t o v a r y i n g l i g h t i n t e n s i t y i n e c o t y p e s o f S o l a n u m d u l c a m a r a L. f r o m shaded and exposed h a b i t a t s . Oecologica (Berlin) 22:275-281. G e i g e r , R. 1 9 6 5 . The c l i m a t e n e a r t h e g r o u n d . MA: H a r v a r d U n i v . P r e s s , 611 p p .  Cambridge,  159  Gordon, D.T. 1973. R e l e a s e d a d v a n c e r e g e n e r a t i o n o f w h i t e and r e d f i r g r o w t h , damage and m o r t a l i t y . USDA F o r e s t S e r v . R e s . P a p . PSW-95. 12 p p . G o t t s c h a l k , M. R. a n d D. J . S h u r e . 1979. H e r b i c i d e e f f e c t s on l e a f l i t t e r d e c o m p o s i t i o n p r o c e s s e s i n an o a k h i c k o r y f o r e s t . E c o l o g y 60:143-151. G r o s s , L. J . 1982. P h o t o s y n t h e t i c d y n a m i c s i n v a r y i n g l i g h t e n v i r o n m e n t s : A model and i t s a p p l i c a t i o n s t o whole l e a f c a r b o n g a i n . E c o l o g y 63:84-93. H a l a s , L. 1971. E f f e c t o f h a b i t a t i r r a d i a n c e on t h e y e a r ' s c o u r s e o f p h o t o s y n t h e t i c r a t e o f P r u n u s l a u r o c e r a s u s L. leaf discs. P h o t o s y n t h e t i c a 5:352-357. H a r r i n g t o n , C.A. 1984. F a c t o r s i n f l u e n c i n g i n i t i a l sprouting of red alder. Can. J . F o r . R e s . 14:357-361. H a t c h , M.D., C R . S l a c k a n d T.A. B u l l . 1969. Light-induced c h a n g e s i n t h e c o n t e n t o f some enzymes o f t h e C ~ d i c o r b o x y l i c a c i d pathway o f p h o t o s y n t h e s i s a n d i t s e f f e c t on o t h e r c h a r a c t e r i s t i c s o f p h o t o s y n t h e s i s . Photochemistry 8:697-714. 4  Helms, J.A. 1963. S e a s o n a l p a t t e r n s o f a p p a r e n t p h o t o s y n t h e s i s i n Pseudotsuga m e n z i e s i i (Mirb.) F r a n c o i n r e l a t i o n t o e n v i r o n m e n t and s i l v i c u l t u r a l treatment. Ph.D D i s s e r t a t i o n , U n i v . o f Wash., S e a t t l e , WA, 225 pp. Helms, J.A. 1965. D i u r n a l and s e a s o n a l p a t t e r n s o f n e t a s s i m i l a t i o n i n D o u g l a s - f i r as i n f l u e n c e d by environment. E c o l o g y 46:698-708. Hemming, I.V. deficit.  1965. C h l o r o p h y l l f o r m a t i o n P h y s i o l . P l a n t 18:994-1000.  and water  H e n d e r s o n , J.A. 1978. P l a n t s u c c e s s i o n on t h e A l n u s rubra/Rubus s p e c t a b i l i s h a b i t a t type i n western W a s h i n g t o n . N o r t h w e s t S c i . 52:156-167. H e n s t r o m , M.A. and S.E. L o g a n . 1986. P l a n t a s s o c i a t i o n and management g u i d e S i u s l a w N a t i o n a l F o r e s t . USDA F o r . S e r v . PNW R e g i o n R b - E c o l 220-1986a. H e r r i n g , L . J . a n d D.E. E t h e r i d g e . 1976. A d v a n c e d a m a b i l i s f i r r e g e n e r a t i o n i n t h e Vancouver F o r e s t D i s t r i c t . B.C. F o r . S e r v . / C a n . S e r v . J o i n t R e p o r t . No. 5. 23 p p . H i t c h c o c k , C L . , A. C r o n q u i s t , M. Ownbey, a n d J.W. Thompson. 1977. Vascular P l a n t s o f the P a c i f i c Northwest. Univ. o f Wash. P r e s s . , S e a t t l e , WA, 5 v o l .  160 H o d g e s , J.D. 1967. Patterns of photosynthesis natural environmental conditions. Ecology  under 48:234-242.  H o d g e s , J.D., and D.R.M. S c o t t . 1968. Photosynthesis s e e d l i n g s of s i x c o n i f e r s p e c i e s under n a t u r a l conditions. E c o l o g y 49:973-981.  in  H o l m g r e n , P. 1968. Leaf factors a f f e c t i n g l i g h t - s a t u r a t e d p h o t o s y n t h e s i s i n e c o t y p e s of S o l i d a a o v i r a a u r e a from e x p o s e d and s h a d e d h a b i t a t s . P h y s i o l . P l a n t . 21:676698. H o l m e s , M.G. and H. A. M c C a r t n e y . 1976. S p e c t r a l energy d i s t r i b u t i o n i n t h e n a t u r a l e n v i r o n m e n t and i t s i m p l i c a t i o n s f o r p h y t o c h r o m e f u n c t i o n , pp. 467-476 I n : S m i t h , H. (ed.) L i g h t an p l a n t d e v e l o p m e n t . Butterworth, London. H o l m e s , M.G., and H. S m i t h . 1977. The f u n c t i o n o f phytochrome i n the n a t u r a l environment. I I . The i n f l u e n c e o f v e g e t a t i o n c a n o p i e s on t h e s p e c t r a l e n e r g y d i s t r i b u t i o n of n a t u r a l d a y l i g h t . P h o t o c h e m . and P h o t o b i o l . 25:539-545. H o r n , H.S. 1971. The a d a p t i v e g e o m e t r y o f t r e e s . P r i n c e t o n , N J : P r i n c e t o n U n i v . P r e s s , 144 pp. H o y e r , G.E. and D. B e l z . 1984. time of c u t t i n g red a l d e r . WA.  Stump s p r o u t i n g r e l a t e d t o WA DNR R e p o r t 45, O l y m p i a ,  H u t c h i s o n , B.A., and D.R. Matt. 1977. The a n n u a l c y c l e o f s o l a r r a d i a t i o n i n a deciduous f o r e s t . A g r i c . Meteor. 18:155-265 J u r i k , T.W., J . F . C h a b o t and B.F. C h a b o t . 1979. Ontogeny of photosynthetic performance i n F r a o a r i a v i r a i n i a n a under changing l i g h t regimes. P l a n t P h y s i o l . 63:542547. K a w a h a r a , T. and Y. T a d a k i . 1978. S t u d i e s on S a s a communities. I I I . R e l a t i o n s h i p between l i g h t i n t e n s i t y and b i o m a s s o f S a s a n i p p o n i c a . J . Jap. For. Soc. 60:244-248. K e l l e r , R.A. Thesis,  1973. T o l e r a n c e i n western hemlock. Ph.D. Univ. B r i t i s h Columbia, Vancouver, B.C.  K e l l e r , R.A. and E.B. T r e g u n n a . 1976. E f f e c t s of exposure on w a t e r r e l a t i o n s and p h o t o s y n t h e s i s o f w e s t e r n hemlock i n h a b i t a t forms. Can. J . F o r . Res. 6:40-48  161 Kira,  T., K. S h i n o z a k i and K. H o z u m i . 1969. S t r u c t u r e of f o r e s t c a n o p i e s as r e l a t e d t o t h e i r p r i m a r y productivity. P l a n t and C e l l P h y s i o l . 1 0 : 1 2 9 - 1 4 2 .  K i i n k a , K. 1976. Ecosystems u n i t s , t h e i r c l a s s i f i c a t i o n , i n t e r p r e t a t i o n and m a p p i n g i n t h e U n i v e r s i t y o f B r i t i s h C o l u m b i a R e s e a r c h F o r e s t . Ph.D. D i s s e r t a t i o n . Univ. of B r i t i s h Columbia, Vancouver, B.C. Kok,  B., E.B. G a s s n e r and H.J. R u r a i n s k i . 1965. P h o t o i n h i b i t i o n of c h l o r o p l a s t r e a c t i o n s . Photochem. P h o t o b i o l . 4:215-227.  Kotar, J. 1972. Ecology of Abies amabilis i n r e l a t i o n to i t s a l t i t u d i n a l d i s t r i b u t i o n and i n c o n t r a s t t o i t s a l t i t u d i n a l d i s t r i b u t i o n and i n c o n t r a s t t o i t s common a s s o c i a t e T s u g a h e t e r o p h y l l a . Ph.D. D i s s e r t a t i o n , U n i v . o f Wash., S e a t t l e . 226 pp. K r a j i n a , V.J. 1965. B i o g e o c l i m a t i c z o n e s and c l a s s i f i c a t i o n of B r i t i s h Columbia. Ecology of N o r t h A m e r i c a 1:1-17 Kramer, P.J. Plants. Kramer, P.J. growth.  and T.T. K o z l o w s k i . A c a d e m i c P r e s s , New  1979. York.  Physiology 811 pp.  Western o f Woody  1987. The r o l e o f w a t e r s t r e s s i n t r e e J . A r b o r i c . 13(2):33-38.  K r u e g e r , K.W. 1967. L i g h t i n t e n s i t y and amount o f f o l i a g e i n f l u e n c e root production of D o u g l a s - f i r seedlings. J. F o r e s t r y 65:22. L a r c h e r , W. 1969. The e f f e c t o f e n v i r o n m e n t a l and p h y s i o l o g i c a l v a r i a b l e s on t h e c a r b o n d i o x i d e gas e x c h a n g e o f t r e e s . P h o t o s y n t h e t i c a 3 (2) :167-198. L a r c h e r , W. 1980. P h y s i o l o g i c a l P l a n t E c o l o g y , 2nd S p r i n g e r - V e r l a g , New Y o r k . 303 pp.  ed.  L a w r e n c e , W.H., N.B. K v e r n o , and H.D. Hartwell. 1961. G u i d e t o w i l d l i f e f e e d i n g i n j u r i e s on c o n i f e r s i n t h e P a c i f i c Northwest. West. F o r . C o n s e r v . A s s n . 44 p. L e d i g , T.F. 1974. Concepts of growth a n a l y s i s . pp.166182. In; Reed, C P . P . and G.H. Feschner (eds.), Proc. o f t h e T h i r d N o r t h A m e r i c a n F o r e s t B i o l o g y Workshop. Colorado State Univ., Fort C o l l i n s , CO. L e v e r e n z , J.W., and P.G. J a r v i s . 1980. Photosynthesis i n s i t k a s p r u c e ( P i c e a s i t c h e n s i s (Bong.) C a r r . ) X. A c c l i m a t i o n t o quantum f l u x d e n s i t y w i t h i n and b e t w e e n trees. J . A p p l i e d E c o l . 17:697-708.  162 Lewandowska, M., J.W. H a r t and P.G. J a r v i s . 1976. Photosynthetic e l e c t r o n t r a n s p o r t i n p l a n t s of S i t k a spruce subjected to d i f f e r i n g l i g h t environments during growth. P h y s i o l . P l a n t . 37:269-278. L i c h t e n t h a l e r , H.K., R. B u r g s t a h l e r , C. Buschmann, D. M e i e r , U. P r e n z e l and A. S c h o n t h a l . 1983. E f f e c t of high l i g h t s t r e s s on c o m p o s i t i o n , f u n c t i o n and s t r u c t u r e o f the photosynthetic apparatus. pp. 3 5 3 - 3 7 0 . In: R. M a r c e l l e , H. C l i j s t e r s and M Van P o u c k e ( e d s . ) , E f f e c t s o f S t r e s s on P h o t o s y n t h e s i s . Martinus N i j h o f f / D r W. J u n k P u b l i s h e r s , B o s t o n . L i n d e r , S. 1979. P h o t o s y n t h e s i s and r e s p i r a t i o n o f conifers: A c l a s s i f i e d r e f e r e n c e l i s t 1891-1977. S t u d . F o r . S u c c . 149, 71 p. L i n d e r , S. 1981. P h o t o s y n t h e s i s and r e s p i r a t i o n o f conifers: A c l a s s i f i e d reference l i s t . Supplement I . 1977-1981. S t u d . F o r . S u c c . 161, 32 p. L i n d r o t h , A. and K. P e r t t u . 1981. Simple c a l c u l a t i o n of e x t i n c t i o n c o e f f i c i e n t of f o r e s t stands. Agric. M e t e o r . 25:97-110 L o a c h , K. 1967. Shade t o l e r a n c e i n s e e d l i n g s . I. Leaf p h o t o s y n t h e s i s and r e s p i r a t i o n i n p l a n t s r a i s e d u n d e r a r t i f i c i a l s h a d e . New P h y t o l . 6 6 : 6 0 7 - 6 2 1 . L o g a n , K.T. 1969. G r o w t h o f t r e e s e e d l i n g s as a f f e c t e d by light intensity. IV. Black spruce, white spruce, b a l s a m f i r , and e a s t e r n w h i t e c e d a r . P u b l . No. 1256 D e p t . F i s h . F o r . , Can. F o r . S e r v . , 12 p. L o o m i s , W.E. Ecology  1965. Absorption 46:14-17.  o f r a d i a n t e n e r g y by  leaves.  M a c L e a n , D.A. and M.G. Morgan. 1983. L o n g - t e r m g r o w t h and y i e l d r e s p o n s e o f y o u n g f i r t o m a n u a l and chemical r e l e a s e from shrub c o m p e t i t i o n . The F o r e s t r y C h r o n i c l e 59:177-183. M a g n u s s e n , S. 1981. C o m p a r a t i v e s t u d i e s on t h e s h a d e t o l e r a n c e o f young w h i t e f i r (Abies g r a n d i s ( L i n d l . ) ) seedlings. S c h r i f t e n aus d. F o r s t l . F a k . U n i v . G o t t i n g e n , Bd. 71:51-121. M a g n u s s e n , S. and A. P e s c h l . 1981. The i n f l u e n c e o f s h a d i n g on t h e p h o t o s y n t h e s i s and t r a n s p i r a t i o n o f s i l v e r and g r a n d f i r s e e d l i n g s . A l l g . Forst.-v. J-Ztg. 154:82-92.  163 M a r q u i s , D. A. a n d G. Y e l e n o s k y . 1962. A c h e m i c a l l i g h t meter f o r f o r e s t r e s e a r c h . USDA F o r . S e r v . N. E. F o r . E x p . S t a . P a p . 1 6 5 . 25 p . McCree, K . J . 1984. D a i l y p h o t o s y n t h e s i s t o t a l s c a l c u l a t e d from s o l a r r a d i a t i o n histograms. A g r i c . and F o r . M e t e o r . 33:239-248. M c C r e e , K. J . , a n d R. S. L o o m i s . 1969. P h o t o s y n t h e s i s i n f l u c t u a t i n g l i g h t . E c o l o g y 50:422-428. M i l l e r , G a r y W. 1984. R e l e a s i n g young hardwood c r o p t r e e s - u s e o f a c h a i n saw c o s t s l e s s t h a n h e r b i c i d e s . USDA NE F o r . E x p . S t a . R e s . P a p . NE-550. M i n o r e , D. 1979. Comparative a u t o e c o l o g i c a l c h a r a c t e r i s t i c s o f northwestern t r e e species. A l i t e r a t u r e r e v i e w . USDA F o r . S e r v . Gen. T e c h . R e p o r t PNW-87. M o n s i , N. a n d T. S a e k i . 1953. Uber den L i c h t f a k t o r i n den P f l a n z e n g e s e l l s c h a f t e n und s e i n e Bedeutung f u r d i e Stoffproduktion. J a p . J . B o t . 14:22-52. M o n t e i t h , J . L . 1965. L i g h t d i s t r i b u t i o n i n f i e l d c r o p s . Ann. B o t . 29:17-37.  and p h o t o s y n t h e s i s  Munch, W.D. 1975. S u i t a b i l i t y o f t h e 100-needle w e i g h t as a measure o f growth r e s p o n s e s t o h e r b i c i d e a p p l i c a t i o n s i n young f o r e s t p l a n t a t i o n s . W a c h r i c h t e n b l a t t des Deutchen P f l a n z e n s c h u t d i e n s t e s 27:22-23. N e i l s o n , R.E. 1 9 7 7 . A t e c h n i q u e f o r m e a s u r i n g p h o t o s y n t h e s i s i n c o n i f e r s by CO2 u p t a k e . P h o t o s y n t h e t i c a 11:241-250. Newton, J . E . , G.E. B l a c k m a n . 1 9 7 0 . The p e n e t r a t i o n o f s o l a r r a d i a t i o n through l e a f canopies o f d i f f e r e n t s t r u c t u r e . A n n . B o t . 34:329-348. Newton, M., a n d D.E. W h i t e . 1 9 8 3 . E f f e c t o f s a l m o n b e r r y on growth o f p l a n t e d c o n i f e r s . P r o c . W e s t . S o c . Weed S c i . 1983:59-64. N o b e l , P.S. 1 9 7 6 . P h o t o s y n t h e t i c r a t e s o f s u n v e r s u s s h a d e leaves o f Hyptis emoryi Torr. P l a n t P h y s i o l . 58:218223. O g r e n , E. a n d G. O q u i s t . 1 9 8 5 . E f f e c t s o f d r o u g h t on p h o t o s y n t h e s i s , c h l o r o p h y l l f l u o r e s c e n c e and photoinhibition s u s c e p t i b i l i t y i n intact willow leaves. P l a n t a 166:380-388.  164 Osmond, C.B. 1983. I n t e r a c t i o n s between i r r a d i a n c e , n i t r o g e n n u t r i t i o n , and w a t e r s t r e s s i n t h e s u n - s h a d e r e s p o n s e s o f Solanum d u l c a m a r a . O e c o l o g i c a 57:316-321. P a t t e r s o n , D.T. 1980. L i g h t and T e m p e r a t u r e A d a p t a t i o n . In. P r e d i c t i n g p h o t o s y n t h e s i s f o r ecosystem models Vol. 1. H e s k e t h , J . D. and J . W. J o n e s (eds) pp 205235. P e a r c e , R.B. and D.R. Lee. 1969. P h o t o s y n t h e t i c and morphological adaptation of a l f a l f a leaves to l i g h t i n t e n s i t y at d i f f e r e n t satges of m a t u r i t y . Crop S c i . 9:791-799. P e n d l , F. and B. D ' A n j o u . 1984. E f f e c t o f t i m i n g on t h e success of mechanical c o n t r o l of red a l d e r - o p e r a t i o n a l t r i a l : E s t a b l i s h m e n t r e p o r t SX 8310/V. On f i l e a t t h e M i n i s t r y of F o r e s t s Research s e c t i o n , Vancouver r e g i o n . P e r r y , D.A., J . T a p p e i n e r , and B. M c G i n l e y . 1985. A review o f l i t e r a t u r e p e r t a i n i n g t o v e g e t a t i o n management o f the Siuslaw National Forest: Phase I — E a r l y s u c c e s s i o n a l p a t t e r n s , c o m p e t i t i o n b e t w e e n t r e e s and a s s o c i a t e d v e g e t a t i o n , and e f f i c a c y o f v e g e t a t i o n control techniques. P r e p a r e d f o r t h e S i u s l a w Nat. Forest, OR. P h i l l i p s , R.A. 1967. Stomatal c h a r a c t e r i s t i c s through a t r e e c r o w n . M.Sc. T h e s i s , U n i v . o f Wash., S e a t t l e , 67 p. P i e t e r s , G.A. 1974. The g r o w t h o f sun and s h a d e l e a v e s P o p u l u s e u r a m e r i c a n a ' r o b u s t a ' i n r e l a t i o n t o age, l i g h t i n t e n s i t y and t e m p e r a t u r e . Meded. Landbouwhogesch. Wageningen 74:11. 106 p.  of  P o w l e s , S.B. 1984. P h o t o i n h i b i t i o n of photosynthesis i n d u c e d by v i s i b l e l i g h t . A n n u . Rev. P l a n t P h y s i o l . 35: 15-44. P o w l e s , S.B. and 0. B j o r k m a n . 1983. P h o t o i n h i b i t i o n of photosynthesis: e f f e c t on c h l o r o p h y l l f l u o r e s c e n c e a t 77K i n i n t a c t l e a v e s and i n c h l o r o p l a s t membranes o f Nerium oleander. P l a n t a 156:97-107. P r i c e , D.T., T.A. B l a c k and F.M. K e l l i h e r . 1986. Effects o f s a l a l u n d e r s t o r y r e m o v a l on p h o t o s y n t h e t i c r a t e and s t o m a t a l c o n d u c t a n c e • o f young D o u g l a s - f i r t r e e s . Can J . F o r . R e s . 16:90-97. P r i o u l , J . L . , J . B r a n g e o n and A. R e y s s . 1980. Interaction b e t w e e n e x t e r n a l and i n t e r n a l c o n d i t i o n s i n t h e development of p h o t o s y n t h e t i c f e a t u r e s i n a grass l e a f . P l a n t P h y s i o l . 66:770-774.  165  Rediske, J . H. and G. R. S t a e b l e r . 1962. H e r b i c i d a l s e l e c t i v i t y o f c h l o r o p h e n o x y b u t y r i c s on D o u g l a s - f i r . F o r . S c i . 8:353-359. Rediske, J . H., D. C. Nicholson, and G. R. S t a e b l e r . 1963. Anthracene technique f o r e v a l u a t i n g canopy d e n s i t y following application of herbicides. F o r . S c i . 9:339343. R e i f s n y d e r , W.E. and H.W. L u l l . 1965. Radiant energy i n relation to forests. USDA For. Serv. Tech. B u l l . 1344, 111 p. Roberts, S.W. and P.C. M i l l e r . 1977. I n t e r c e p t i o n o f s o l a r r a d i a t i o n as a f f e c t e d by canopy o r g a n i z a t i o n i n two mediterranean shrubs. Oecologia P l a n t . 12:273-290. Roberts, C. 1979. Cooperative brush c o n t r o l study. First year r e p o r t . Prepared f o r the Siuslaw Nat. F o r e s t , OR Ronco, F. 1975. D i a g n o s i s : F o r . 73:31-35.  "Sunburned" t r e e s .  1975. J .  R u s s e l l , T.E. 1961. C o n t r o l o f u n d e r s t o r y hardwoods f a i l s to speed growth o f p o l e - s i z e l o b l o l l y . USDA For. Serv. South. F o r . Notes no. 131, South F o r . Exp, Stn., New Orleans. Ruth, R.H. 1956. P l a n t a t i o n s u r v i v a l and growth i n two b r u s h - t h r e a t areas i n c o a s t a l Oregon. Prepared f o r the Siuslaw Nat. F o r e s t , OR Ruth, R.H. 1967. D i f f e r e n t i a l e f f e c t o f s o l a r r a d i a t i o n on s e e d l i n g establishment under a f o r e s t stand. Ph.D. D i s s e r t a t i o n , Ore. State Univ., C o r v a l l i s , OR, 165 pp. Sanger, J.E. 1971. Q u a n t i t a t i v e i n v e s t i g a t i o n s o f l e a f pigments from t h e i r i n c e p t i o n i n buds through autumn c o l o r a t i o n t o decomposition i n f a l l i n g l e a v e s . Ecology 52:1075-1089. Seeman, J.R., W.J.S. Downton and J.A. B e r r y . 1986. Temperature and l e a f osmotic p o t e n t i a l as f a c t o r s i n the a c c l i m a t i o n o f p h o t o s y n t h e s i s t o h i g h temperature in desert plants. P l a n t P h y s i o l . 80:926-930. Sestak, Z. 1977. P h o t o s y n t h e t i c c h a r a c t e r i s t i c s d u r i n g ontogenesis o f l e a v e s : 1. C h l o r o p h y l l s . P h o t o s y n t h e t i c a 11:367-448. Sharp, R.E. and J.S. Boyer. 1986. P h o t o s y n t h e s i s at low water p o t e n t i a l s i n sunflower: Lack o f p h o t o i n h i b i t o r y effects. P l a n t P h y s i o l . 82:90-95.  166  S h i m s h i , D. 1 9 6 9 . A r a p i d f i e l d method f o r m e a s u r i n g photosynthesis w i t h l a b e l l e d carbon d i o x i d e . J . Exp. Bot. 20:381-401. S h i n o z a k i , K., K. Y o d a , K. H o z u m i , a n d T. K i r a . 1964a. A q u a n t i t a t i v e a n a l y s i s o f p l a n t form - t h e p i p e model theory. I . B a s i c a n a l y s i s . J a p . J . E c o l . 14:97-105. S h i n o z a k i , K., K. Y o d a , K. H o z u m i , a n d T. K i r a . 1964b. A q u a n t i t a t i v e a n a l y s i s o f p l a n t form - t h e p i p e model theory. I I . F u r t h e r evidence o f t h e t h e o r y and i t s a p p l i c a t i o n i n forest ecology. J a p . J . E c o l . 14:133139. S h i r l e y , H.L. 1943. I s t o l e r a n c e shade? J . F o r . 41:339-345.  t h e c a p a c i t y t o endure  S i e d e l , K.W. 1980. D i a m e t e r and h e i g h t g r o w t h o f suppressed grand f i r saplings a f t e r overstory removal. USDA F o r . S e r v . R e s . P a p . PNW-275, 9 p p . S i e r z b i c k i , B. 1980. I n t e r m i t t e n t l i g h t as p h y s i o l o g i c a l and e c o l o g i c a l f a c t o r o f p h o t o s y n t h e s i s o f p i n e a n d spruce. A c t a P h y s i o l . P l a n t . 2:69-80. S i l v i u s , J . E . 1979. P h o t o s y n t h a t e p a r t i t i o n i n g i n soybean l e a v e s a t two i r r a d i a n c e l e v e l s : Comparative responses of a c c l i m a t e d and u n a c c l i m a t e d l e a v e s . Plant Physiol. 64:872-875. S m i t h , H. 1982. L i g h t q u a l i t y , p h o t o p e r c e p t i o n , and p l a n t strategy. A n n . Rev. P l a n t P h y s i o l . 3 3 : 4 8 1 - 5 1 8 . S m i t h , J.H.C., a n d A. B e n i t e z . 1955. C h l o r o p h y l l s : a n a l y s i s i n p l a n t m a t e r i a l s . In. K. P a e c h a n d M.V. T r a c e y (eds.) I V : Modern M e t h o d s o f p l a n t a n a l y s i s , p p . 142-196. S m i t h , W.K., a n d G.N. G e l l e r . 1980. L e a f a n d e n v i r o n m e n t a l parameters i n f l u e n c i n g t r a n s p i r a t i o n : t h e o r y and f i e l d measurements. O e c o l o g i a 46:308-313. Society o f American Foresters. 1944. F o r e s t terminology: A g l o s s a r y o f t e c h n i c a l t e r m s u s e d i n f o r e s t r y (Comm. Report). S o c . Amer. F o r . , Wash. D.C., 84 p. S t e i n , W.I. 1985. Manual and c h e m i c a l o p t i o n s f o r r e l e a s i n g D o u g l a s - f i r from c o m p e t i n g b r u s h i n Oregon's C o a s t Range. U n p u b l i s h e d P r o g . Rep. on f i l e a t U.S. F o r e s t S e r v i c e , C o r v a l l i s , OR.  167 S t e w a r t , R.E., L.L. G r o s s and B.H. H o n k a l a . 1984. o f c o m p e t i n g v e g e t a t i o n on f o r e s t t r e e s : A bibliography with abstracts. USDA F o r . S e r v . T e c h . R e p o r t WO-43.  Effect Gen.  S t o l i n e , M.R. 1981. The s t a t u s o f m u l t i p l e c o m p a r i s o n s : simultaneous e s t i m a t i o n of a l l p a i r w i s e comparisons i n one-way ANOVA d e s i g n s . Amer. S t a t . 3 5 : 1 3 4 - 1 4 1 . S t r a n d , M. and G. O q u i s t . 1985. I n h i b i t i o n of p h o t o s y n t h e s i s by f r e e z i n g t e m p e r a t u r e s and h i g h l i g h t l e v e l s i n c o l d - a c c l i m a t e d seedlings of Scots pine (Pinus s v l v e s t r i s ) : I . E f f e c t s on t h e l i g h t - l i m i t e d and l i g h t - s a t u r a t e d r a t e s o f CO2 a s s i m i l a t i o n . P h y s i o l . P l a n t . 64:425-430. S w a r t z , H.J., S.E. G r a y , L.W. D o u g l a s s , E. D u r n e r , CS. W a l s h and G.J. G a l l e t t a . 1984. The e f f e c t o f a d i v i d e d c a n o p y t r e l l i s d e s i g n on t h o r n l e s s b l a c k b e r r y . H o r t S c i . 19:533-535. T a d a k i , Y. 1966. Some d i s c u s s i o n s on t h e l e a f b i o m a s s f o r e s t s t a n d s and t r e e s . J a p . F o r . Exp. S t n . B u l l . 184:135-161.  of  T a s k e r R., and H. S m i t h . 1977. The f u n c t i o n o f p h y t o c h r o m e i n t h e n a t u r a l e n v i r o n m e n t - V. S e a s o n a l c h a n g e s i n r a d i a n t energy q u a l i t y i n woodlands. P h o t o c h e m . and P h o t o b i o l . 26:487-491. T i e s z e n , L.L., D.A. J o h n s o n and M.M. Caldwell. 1974. A P o r t a b l e s y s t e m f o r t h e measurement o f photosynthesis u s i n g 14-carbon d i o x i d e . P h o t o s y n t h e t i c a 8:151-160. T u c k e r , G.F. 1983. F o l i a r m o r p h o l o g y and t h e a c c l i m a t i o n o f shade t o l e r a n t c o n i f e r s t o v a r y i n g l i g h t l e v e l s . M.Sc. t h e s i s , U n i v . o f Wash., S e a t t l e , WA, 95 p. T u c k e r , G.F. and W.H. Emmingham. 1977. Morphological changes i n l e a v e s o f r e s i d u a l w e s t e r n hemlock a f t e r c l e a r and s h e l t e r w o o d c u t t i n g . F o r . S c i . 2 3 : 1 9 5 - 2 0 3 . W a l l a c e , L.L. and E.L. Dunn. 1980. Comparative p h o t o s y n t h e s i s o f t h r e e gap p h a s e s u c c e s s i o n a l species. O e c o l o g i a 45:331-340.  tree  Webb, W.L. 1977. Rates of current photosynthate accumulation i n roots of D o u g l a s - f i r seedlings: S e a s o n a l v a r i a t i o n . pp 1 4 9 - 1 5 2 . I n : Marshall J.K. ( e d . ) , The B e l o w - g r o u n d E c o s y s t e m : A s y n t h e s i s o f Plant Associated Processes. Range S c i . Dep., Sci S e r i e s 26, C o l o r a d o S t a t e U n i v . , F o r t C o l l i n s , CO.  168 W i e n , H.C. 1982. Dry m a t t e r p r o d u c t i o n , l e a f area d e v e l o p m e n t , and l i g h t i n t e r c e p t i o n o f cowpea l i n e s w i t h b r o a d and n a r r o w l e a f l e t s h a p e . C r o p S c i . 2 2 : 7 3 3 737. W r i g h t , C . J . , P.D. Waister. 1984. L i g h t i n t e r c e p t i o n and f r u i t i n g cane a r c h i t e c t u r e i n t h e r e d r a s p b e r r y grown u n d e r a n n u a l and b i e n n i a l management. J . H o r t . S c i . 59:395-402. Yim,  Y - J , H. Ogawa, and T. K i r a . 1969. Light interception by s t e m s i n p l a n t c o m m u n i t i e s . Jap. J . E c o l . 19:233238.  Zavitkovski, J. 1974. S o l a r r a d i a t i o n measurements i n t h e Enterprise Radiation Forest, pp 3 3 - 4 5 . In: Rudolph, T.D. (ed.), E n t e r p r i s e R a d i a t i o n Forest. U.S. Atom. E n e r g y Comm. P u b l . T I D - 2 6 1 1 3 . Zavitkovski, J. 1982. C h a r a c t e r i z a t i o n of l i g h t climate under canopies of i n t e n s i v e l y c u l t u r e d h y b r i d p o p l a r plantations. A g r i c . Meteor. 25:245-255. 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 r e d a l d e r s t a n d s i n w a s t e r n Oregon. P l a n t and s o i l 35:257-268. Z a v i t k o v s k i , J . , J.G. I s e b r a n d s and D.H. Dawson. 1976. P r o d u c t i v i t y and u t i l i z a t i o n p o t e n t i a l o f s h o r t r o t a t i o n Populus i n the Lake S t a t e s . pp. 3 9 2 - 4 0 1 . T h i e l g e s , B.A. and S.B. L a n d ( e d s . ) , P r o c . Symp. E a s t e r n C o t t o n w o o d and R e l a t e d S p e c i e s . Louisiana State Univ.  In:  169  APPENDIX 1  Examples o f d a t a  (Additional  analysis  t a b l e s not p r e s e n t e d i n t h i s a v a i l a b l e from t h e a u t h o r )  appendix  are  Regressions  i n Chapter  Anthracene absorbence vs. cumulative light Regression Analysis - Beciprocal Dependent  model; i/Y = a+bX  variable: 8:ANTHCAL.ABS  Independent variable: B:ANTHCAL.MOLIS  Parameter  Estimate  Standard Error  T Wal ue  Prob. Level  Intercept Slope  0.135352 0.0345317  0.0138269 7.57676E-4  9.73898 45.5758  2.42029E-14 0  Analysis of Variance Source Model Error Total (Corr.)  Sum of Squares 10.0754 .310436  Df 1 64  10.385797  65  Mean Square 10.0754 .004851  Correlation C o e f f i c i e n t = 0.984941 Stnd. Error of Est. = 0.069646  10  F-Ratio "077.1517  E-squared =  20 Cumulative light (Moles)  Prob. Level 00000  97.01 percent  30  40  Leaf area index vs Summer light Regression  Analysis - Linear model: Y = a«-bX  Dependent variables BsftPP!>2. logsura  Independent variable: 3: APP!>2. LAI  Parameter  Tstiraate  Standard Zrrsr  7 Uaiuc  ?rcb. Levei  Intercept Siope  1.85S62 -0.103912  0.0697905 3.33042S-2  2S.5437 -11.7=7=  0 4.529711-14  Analysis of Variance Source Jtodei Errtr  S'JfT: O f  Squares 3.04S3S 2.417120  Df V 37  Mean Square 9.04il-: .05::2:  7-Patio L3S.4769S  Prob. Level 00000  Tctai (Ccrr Ccrrelat ion C o e f f i c i e n t = -0.39333? Stna. Error of Est. = 0.255553  3  s  8-squared =  78.91 percent  12  3 2  2  Leaf area index (mm )  15  Leaf and stem area index vs. Summer light Regression Analysis - Linear model: Y - a+bX Independent v a r i a b l e : B:AP?D2.lasa  Sependent variable: E:APPD2.logsum  Parameter  Estimate  Standard Error  "T Value  Prcb. .Level  Intercept Slope  1.94353 -0.09=0757  0.063611? 3.1542E-3  26.3697 -11.7324  0 4.37423E-14  Analysis oi Source Mode: Zrrcr  Variance  Sum G: Squares 3.05114 .412251  Df i 27  t l .462495  38  Total (Corr  Mean Square 3.05114 .C65199  Ccrrelatlcn Coefficient = -0. S£S57? :tnd. Error c- Est. = 0.25524  Prcb. Lsve« 00000  •-Ratio 133.92401  fi-souared =  78.56 «src=r.t  r-T,. 1.6  * i.2  J  1 •t->  -§> 0.3  -  s_ QJ i —  E  "  °  0.4  -  ..........  I  J  I  I  I  I  j  J  I  12 2  2  Leaf and stem area index (mm )  L 16  Stem area index vs. Winter light Regression Analysis - Linear model: Y = a+bX Dependent variable: E:AP?D2.Icgwin  Independent variable: SSAPPU2.SAI  Parameter  Estimate  Standard Error  -T Value  Prob. Level  Intercept Slope  1.96071 -0.212425  3.071O1Z-3 0.0157662  216.152 -13.5352  0 6.65134E-16  Analysis cf '.'airanoe Source rtcdel Error  Sum of Squares .2=3=4 .073441  Df 1 37  .437076  33  Total (Corr.l  Correlatton Coe f f i c i e n t = -0. 912125 Stnd. Error of Est. = 0.0445521  Mean Square .35264 .00123:  F-?.atio 183.20204  F.-squared =  Prob. Level .00000  83. 20 percent  2 —  0  0.4  0.8  Stem area index (m 'm )  1.2  l.S  Cumulative l e a f area index vs. Red to Far-red r a t i o Regression Analysis - Exponential model: Y = exp(arbX) Independent variable: B:7S23.iai.  Dependent variable: 2;7fi33.:eta  Parameter  Estimate  Standard Srrcr  T Value  . Prob. Level  Intercept Stops  -0.172523 -0.134514  0.100913 0.0120259  -1.70953 -10.3266  0.107952 3.263371-3  Analysis cf Variance Source Mode I Grrcr  Sum at' Squares 3.44353 1.133390  l( 1 15  9.637016  16  Total (Corr )  Corre! at i on C o e f f i c i e n t = -0.986315 Stria. Error of Est. = 0.261471  3  6  Mean Square 3.44363 .079226  •-Patio 105.53959  E-squared =  67.67 percent  9  Cumulative l e a f area index  12 (m m ) 2,  Proc. Level .00000  2  15  ANOVA on  light  values  i n Table  177  Summer light values Qne-Uay Analysis cf Variance Data? B:L1CHTDA7. surnl i t Level codes: B:LICHTDAT.sum Labels: Sance test'  Confidence le»el: 95 Analysis of variance  Source o: v a r i a t i o n  Sum cf Squares  d.f.  Mean square  F-ratio  Between groups Within groups  178514.98 1133.02  4 220  44623.744 5.150  999.959  Total <corrected)  17964S.00  224  Sig. level .0000  Table of means for 3:LIQHTDAT. sumlit by BsLISHTDAT.su.ro Level si s2 s3 s4 s5 Total  Count  Avera-j'e  Stnd. Error (internal)  Stnd. Error < pooled s)  95 Percent i n t e r v a l s for mean  45 45 45 45 45  76.577773 12.155556 10.23S3S9 2.622222 2.355556  .4544326 .3595103 .4002305 .2091030 .1302231  .3332997 .3332557 .3382997 .3332997 .3332997  75.334632 11.412410 9.545743 1.S7S07? 1.612410  77.320923 12.393701 11.032035 3.365363 3.093701  225  20.300000  .1512322  .1512922  20.467555  21.132345  Multiple range analysis for B:LICHTDAT.suml i t by E:LIGH72AT. sum Method: 95 Percent Level Count s5 s4 s3 sa si  45 45 45 45 45  Average 2.355556 2.622222 10.283339 12.155556 76.577773  Homogeneous Groups * * * * *  178  Winter Tign't"va 1 lies One-Way Analysis of Marsance Data; E:LI£H7I>A7. win! i t Level codes: BsLlSHTPAT.win Labels: Kangc-  test:  Confidence l e v e l : 55  Analysis of variance Source of v a r i a t i o n;  SUIT. of Squares  ci. f.  Between groups Within groups  52015.218 4627.8=7  4 220  TetaL 'I corrected)  S6643.182  224  Hean square  F-ratio  20503.325 21.036  574.713  Sig.  level  .0000  5 mi55irig value( s) have beer, excluded. Table of means for B: L!GHTDAT.mini i t by B:LIGHTDAT.win Level wi ui2 w3 w4 W3  Total  Stnd. Error- Stnd. Error ( i nter-na!) (pooled E)  95 Percent i ntervai s for mean  Count  Average  45 45 45 45 45  96.933333 96.666647 76.422222 64.244444 4i.7?77?S  .4124330 .7373648 .5099900 .6147641 .9523333  .6337114 .6337114 .6337114 .6337114 . 6-337114  95.431419 35.164752 74.520303 62.742530 40.275863  93.435243 33.163531 77.924137 65.746359 43.279692  225  73.203339  .3057650  .3057650  72.537212  73.330565  M u l t i p l e range analysis for E:L!GK7DAT.winiit by E:LiGHTDAT. win Method: 95 Percent Count Level w5 w4 a3 w2  45 45 45 45 45  Average 41.777773 64.244444 76.422222 So.666667 36.933333  Homogeneous Croups * * * * *  179  ANOVA on p h o t o s y n t h e t i c and l e a f c o n d u c t a n c e v a l u e s i n T a b l e 5.  180  Summer l e a f conductance values One-Way Analysis of Variance Data: 8:G3.gsbsu Level codes: B:GS.treat Labels: Range test:  Confidence l e v e l : 95  Analysis of variance Source of v a r i a t i o n  Sum of Squares  d. f.  Between groups Ui thin groups  0194667 • 0035333  3 13  Total ( corrected)  •  0230000  26  Mean square  F-rati o  .0024333 .0001963  12.396  Sig.  level  . 0000  1 missing valuet s) have been excl uded.  T  Level HD HG HH LD LG LH MD MG MH Total  Count  able of means for B:GS.gsbsu by B:G3. treat  Average  3 3  Stnd. Error ( i nternal)  Stnd. Error < pooled s)  95 Percen intervals for mean  3 3 3 3 3 3 3  .0166667 .0400000 .0466667 .0366667 .0966667 .0566667 .0466667 .0833333 .0966667  .0033333 .0057735 .0033333 .0033333 .0088192 .0088192 .0033333 .0145297 .0120185  .0080390 .0080890 .0080890 .0080890 .0080890 .0080890 .0080890 .0080890 .0080890  -.0089650 .0143684 .0210350 .0610350 .0710350 .0310350 .0210350 .0577017 .0710350  .0422983 .0656316 .0722983 .1122983 .1222933 .0822983 .0722983 .1089650 .1222983  r>t ci  .0633333  .0026963  .0026963  .0547895  .0713772  Multiple range analysis for E:GS.gsbsu by B: GS.treat Method!: 95 Percent Level Count HD HC HH MD LH MG LD LG MH  3 3 3 3  3 3 3 ?  3  Average .0166667 .0400000 .0466667 .0466667 .0566667 .0333333 .0866667 .0966667 .0966667  Homogeneous Groups  * *#  *** *** *** ** ** k  *  Spring leaf conductance .values .  .  .  • ,,  Une-wau Analysis ot Variance Data: BiGS.gsbsp Level  codes: B:GS.treat  Labels: Confidence l e v e l : 95  Range test:  Analysis Source of v a r i a t i o n  Sum of Squares  of variance d. f.  Between groups Within groups  • 0010667  3 18  Total ( corrected)  .0450667  26  0440000  Mean square  F-ratio  .0055000 .0000593  92.312  Sig.  level  . 0000  1 missi ng value< s) h ave been excl uded.  Table of means for B:GS.g sbsp by B:GS. treat  Level HD HS HH LD LG LH MD MG MH Total  Average  Stnd. Error ( i nternal)  Stnd. Error ipooled s)  3 3 3 3 3 3 3 3 3  .0666667 .1033333 .0733333 .1533333 .1833333 .1800000 .1233333 .1566667 .1400000  .0033333 .0033333 .0066667 .0033333 .0033333 .0057735 .0033333 .0033333 .0057735  .0044444 .0044444 .0044444 .0044444 .0044444 .0044444 .0044444 .0044444 .0044444  .0525336 .0892502 .0592502 .1392502 .1692502 .1659169 .1092502 .1425836 .1259169  .0807498 .1174164 .0874164 .1674164 .1974164 .1940831 .1374164 .1707498 .1540831  2?  .1311111  .0014815  .0014815  .1264167  .1353055  Count  95 Percent i ntervals for mean  Multiple range analysis for B:GS.gsbsp by B:GS.treat Method: 95 Percent Count Level HD HH HG MD MH LD MG LH LG  3 3 3 3 3 3 3 3 3  Average .0666667 .0733333 .1033333 .1233333 .1400000 .1533333 .1566667 .1300000 .1333333  Homogeneous Groups  * tr  * *#  ** ** *  Summer photosynthetic values One-Way Analysis of Variance Data*. B:PS.psbsu Level codes: B:PS.treat Labels Range test:  Confidence level : 95  Analysis of variance Source of v a r i a t i o n  Sum of Squares  d.f.  Mean square  F-ratio  Between groups Within groups  199.43373 7.77200  3 36  24.304222 .215839  114.393  Total (corrected)  206.20578  44  Sig. level . 0000  1 missing value< s) have been excl uded.  Table of means for B:PS.psbsu by B:PS.treat  Level HD HG HH LD LG LH MD MG MH Total  Count  Average  Stnd. Error ( i nternal)  Stnd. Error (pooled s)  5 5 5 5 5 5 5 5 5  .6000000 2.5000000 2.8200000 5.5600000 7.8800000 5.0600000 1.5000000 3.4000000 3.2400000  .0707107 .0707107 .1327567 .0673233 .3813135 .2336664 .0836660 .2213594 .2908608  .2077926 .2077926 .2077926 .2077926 .2077926 .2077926 .2077926 .2077926 .2077926  -.0176058 1.3823942 2.2023942 4.9423942 7.2623942 4.4423942 .3823942 2.7823942 2.6223942  1.2176058 3.1176053 3.4376058 6.1776058 8.4976058 5.6776058 2.1176053 4.0176058 3.3576053  45  3.6177778  .0692642  .0692642  3.4119092  3.8236464  95 Percent i ntervals for mean  Multiple range analysis for B:PS.psbsu by B:PS.treat Method: 95 Percent Count Level HD MD HG HH MH MG  •LH LD LG  5 5 5 5 C  5 5 5 5  Average .6000000 1.5000000 2.50OOO0O 2.3200000 3:2400000 3.4000000 5.0600000 5.5600000 7.9300000  Homogeneous Groups  Spring photosynthetic values Qne-Uay Analysis cf Variance Data: B:pS.psbsp Level codes: E:PS . treat Labels: Range test:  Confidence level : 5 Q  Analysis of variance Source of v a r i a t i o n  Sum of Squares  d.f.  Mean square  F-ratio  Between groups Within groups  172.14178 1.17600  3 36  21.517722 .032667  658.706  Total \ corrected)  173.31778  44  Sig.  ievel  . 0000  1 missing value(s ) have been excluded.  Table of means for B:P3.p sbsp by B:PS.treat  Level HD HG HH LD LG LH MD MG MH Total  Count  Average  Stnd. Error (internal)  5 5 5 5 5 5 5 5 5  1.6800000 3.6200000 3.7000000 5.6200000 8.6400000 6.7400000 3.4200000 5.8200000 4.6600000  .0969536 .0374166 .0774597 .0734847 .0812404 .0678233 .0860233 .0489898 .1249000  .0808290 .0808290 .0808290 .0808290 .0808290 .0808290 .0808290 .0808290 .0808290  1.4397582 3.3797582 3.4597582 5.3797582 8.3997582 6.4997582 3.1797582 5.5797582 4.4197582  1.9202418 3.8602418 3.9402418 5.8602418 3.8802418 6.9802418 3.6602418 6.0602418 4.9002418  45  4.8777778  .0269430  .0269430  4.7976972  4.9578584  Stnd. Error '. pool ed s)  95 Percent i ntervals for mean  Multiple range analysis for B:PS.psbsp by B:P3.treat Method: 95 Percent Level Count HD MD HG HH MH LD MG LH LG  5 C J  c •J c J c J  5 5 c 5  Average 1.6300000 3.4200000 3.6200000 3.70OOOO0 4.6600000 5.6200000 5.8200000 6.740000Q 3.6400000  Homogeneous Croups *  * * *  ANOVA on  growth d a t a  in  Table  185 S p e c i f i c leaf area One-Uay Analysis o: Variance  .• • .  Data: i :GJ0UTHC3.ESLfi Level : odes: B : G ?. 0 U' labels: Cc>n(: ier.c t J f ve. 1 ; 95  Banff i ?• s * :  Analysis cf variance Source 01 v a r i a t i o n  Sum of Squares  d.f.  ^ean square  F-ratio  Between oroups •Ji tMr. groups  152214.25 3525.56  8 72  19026.731 4 5.022  388.121  Totai (corrected)  155743.30  SO  Sig.  level  . 0000  Table o: means far ?: GECuiTHCS. 3SLA by 3:C?.CUT«C3. treat  Level HD HG HH LD LG LH MD MG MH Total  Count 9 9 9 9 9 9 9 9 9 81  Average 180.44444 153.S3889 214.11111 83.00000 79.77778 108.77778 162.66667. 136.11111 176.77778  95 Percent i ntervals for mean  Stnd. Error (internal)  Stnd. Error (pooled s)  2.2980131 1.9539450 3.1066436 1.6583124 1.9348972 2.4876237 3.0092450 1.2585577 2.5861693  2.3336477 :.3338477 2.3336477 2.3338477 2.3338477 2.3338477 2.333B477 2.333S477 2.3333477  173.72900 147.17345 207.39567 76.23456 73.06234 102.06234 155.95122 129.39567 170.06234  187.15989 160.60433 220.32655 89.71544 86.49322 115.45322 169.23211 142.62=55 133.45322  .7779492  .7779492  141.71214  146. ', 10  143.55062  Multiple range analysis.for 8:GR0WTHC3.ESLA by B: GR0UTHC3.tr Method:: 55 Percent Count Level LG LD LH  MG HG  MD MH MD  rirl  9 9 9 9 9 9 Q  C  Average 79.77773 93.00000 108.7777S 136.11111 152.3°SS9 162.66667 176.77778 180.44444 214.11111  Homogeneous Croups  *  * * *  ;i  Leaf growth rate One-Way Analysis cf Variance Data: •:GSDuTHCS.BLAG Levei codes: :-: GK0UTHC3. treat Late 1s: Range  Cor. f i dence i eve::  Analysis c: variance Source oi v a r i a t i o n Between groups Uithin groups  Surr. of Squares  i . f.  15.797778 6.324444  S 72  Total ; corrected)  Mean square 1. 9747c«iii .0947940  F-rat;o  3ig.  20.534  .  leve! VJJ'J  SO  Table of means for E:CRQUTHC3.BLAG by B:GR0UTHC3.treat  Level HD HG HH LD LG LH MD MG MH Total  Average  Stnd. Error (internal)  Stnd. Error (pooled s)  Q 9  3111111 3000000 6444444 1. 2111111 1. 6555556 9444444 3666667 7666667 i . • 1666667  .0512197 .0897527 .0851651 . 1111111 .1226004 .1055556 .0687184 .0957427 .1563472  .1026233 .1026233 .1026233 .1026233 .1026233 .1026233 .1026233 .1026233 .1026233  .0155215 .0047103 .3491548 .9153215 1.3602659 .6491548 .0713770 .4713770 .8713770  5064005 ,5952897 ,9397341 4. ,5064005 • 1,,9508452 1,.2397341 .6619563 i, .0619563 .4619563  81  8185185  .0342078  .0342078  .7200SS6  .9169484  Count Q 9 9 ? 9 5 9  95 Percent i n t e r v a l s for mean  Multiple range analysis for B:GRGUTHC3.BLAG by B:GP.0UTHC3. t r Method: 95 Percent Level Count HG HD MD HH MG LH MH LD  9 9 9  c Ct  9 9 Q 9  Average .3000000 ,3111111 .3666667 .6444444 .7566667 .9444444 .1666667 1.2111111 1.6555555  Homogeneous Groups  * ** ***  *** <r*  ** **  Relative diameter growth rate One-iiiay Analysis  cf '-.'ariar.ee  i-ata: E: GRCUTHC3. EDG Level  codes: 3: GP.P/J7HC2. treat  Label s: range t est:  n f i den:e leve;  Analysis Source of variation Between groups Uithir. groups Total  (corrected)  Sum of Squares  ::' variance d. f.  3. c  6733323  72  13 848395  90  Mean square  F-ratio  1.0218327 .0737953  12.569  rig.  level  Table of means for 3:GE0UTHC3. BDG by B:GJ.01i.'THC3. treat  Leve 1 HD • HG HH LD LG LH MD MG MH Total  Count  Average  Stnd. Error (internal)  Stnd. Error <pooled s)  95 Percent i n t e r v a l s for mean  5 5 9 9 9 9 9 9 9  .2777778 .577777b .6888889 .7111111 1.3666667 .8777778 .2666667 .9111111 .8000000  .0595757 .0741204 .0633431 .1033393 .1290994 .1139905 .0577350 .0975156 .1116034  .0935689 .0935689 .0935689 .0935689 .0935689 .0935689 .0935689 .0935689 .0935519  .0085414 .3065414 .4196525 .4418747 1.0974303 .6085414 -.0025697 .6418747 .5307636  • .5470142 .6470142 .9581253 .9803475 1.5359030 1.1470142 .5359030 1.1803475 1.0692364  SI  .7197521  .0311896  .0311896  .6300076  .9094935  Multipi e range analysis for B:GJ;QLI7HC3.BDG by E: GR0UTHC3.tr Method: 95 Percent Count Leve i MD HD HG HH LD MH  9 9 9 9 5 9  LP  MG LG  9  Average .2666667 • 2777778 .577777S .6388S39 .7111111 .3000000 .3777773 .9111111 1.3666667  Homogeneous Groups * * »+  **  ** ** ** *  188  Relative height growth rate One-Way Analysis of Variance Data: S:CR0UTHC3.BHC Level  c r i e s : : :GK0L'7'-"3. treat  Labe i s :  Far.ge t est:  Cc nfiaence  An&i j i s S  Source of v a r i a t i o n Setueer groups Within groups  level : ?5  c i va r: ar.re  Sum of Squares  a.f.  Mean square  F-rat: o  j . 3419556 4. S472C00  8 72  .4177444 .0673222  6. 205  . 1891555  60  "otal ( corrected)  : i 9.  i eve;  . 0000  Table of means for E:GR0ulTHC3. BHG by B:CRDUTHC3. treat  Level HD HG HH LD LG LH MD MG MH Total  Stnd. Error (internal)  Stnd. Error (pooled s)  .6433333 .757777S  .0771182 .0632773 .0518734 .1269855 .1022449 .0879867 .0672429 .0591138 .1110528  .0S6 .:54 .0364S34 .0864S34 .0864884 .0864864 .0864884 .0864584 .0864384 .09646 34  -.0255295 .3400260 .4722483 .6066527 .6522463 .5744705 .2123594 .3944705 .5039149  .4721562 .6377517 .5699740 1.1044134 1.1499740 1.0721962 .7110651 .3921962 1.0066406  .6640741  .028S295  .0288295  .5811198  .7470234  Court  Average  5  .2233333 .5888889 .7211111 .8555556 .9011111 .8233333  S  9 9 9 9 9 9 9 SI  . 4622222  /  35 Percent intervals lor mean  Multiple range anal usis for B:GR0UTHC3.BHG by B: GRGUTHC3. t r Method: S5 Percent Count Level HD MD HG MG liH MH LH LD  9 J 9 s 9 9 9 9  Average .2233333 .5886539 .6433332 .721111' .75777-3 .i23w-ij  .3555556 .9011111  homogeneous Croups  * ** ** *•*  * t  •*• *•  189  APPENDIX  Glossary of abbreviations  2  used i n the  thesis  190  Abbreviations: Tree  species  DF  Douglas-fir  GF  Grand  WH  Western hemlock  Physiological  fir  (Pseudotsuga m e n z i e s i i  (Abies qrandis  (Mirb.) Franco)  (Dougl.)  Lindl.)  (Tsuga h e t e r o p h y l l a  (Raf.) Sarg.)  measurements  Chl  C h l o r o p h y l l c o n t e n t , (mg'g )  D  Atmospheric vapor pressure d e f i c i t ,  g^  Leaf d i f f u s i v e  x  conductance,  (KPa)  (em's ) — 7  —  1  PPFD  P h o t o s y n t h e t i c p h o t o n f l u x d e n s i t y , (uMol'm s •"•) (a M o l e (Mol) i s A v o g a d r o s ' number o f p h o t o n s i n t h e p a s t c a l l e d an E i n s t e i n )  Ps  Photosynthetic rate,  wp  L e a f w a t e r p o t e n t i a l , (MPa)  (mgC0 'dm 'hr ) - 2  - 1  2  Growth measurements 7  7  LAI  Leaf area index  RDGR  R e l a t i v e diameter growth r a t e  RHGR  R e l a t i v e h e i g h t growth r a t e  RLAGR  Relative  SAI SLA S/R  (m^'m )  p p (m m^) p —1 l e a f a r e a (cm *g )  Specific  Shoot t o r o o t r a t i o  (g'g ) - 1  -  (cm'yr - "' c m )  l e a f area growth r a t e  Stem a r e a i n d e x  (mm'yr -  - 1  1  (g'yr  -  

Cite

Citation Scheme:

        

Citations by CSL (citeproc-js)

Usage Statistics

Share

Embed

Customize your widget with the following options, then copy and paste the code below into the HTML of your page to embed this item in your website.
                        
                            <div id="ubcOpenCollectionsWidgetDisplay">
                            <script id="ubcOpenCollectionsWidget"
                            src="{[{embed.src}]}"
                            data-item="{[{embed.item}]}"
                            data-collection="{[{embed.collection}]}"
                            data-metadata="{[{embed.showMetadata}]}"
                            data-width="{[{embed.width}]}"
                            async >
                            </script>
                            </div>
                        
                    
IIIF logo Our image viewer uses the IIIF 2.0 standard. To load this item in other compatible viewers, use this url:
http://iiif.library.ubc.ca/presentation/dsp.831.1-0097952/manifest

Comment

Related Items