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The soil water regime and growth of uneven-age interior Douglas-fir (Pseudotsuga menziesii var. glauca)… Korol, Ronda Lee 1985

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THE SOIL WATER REGIME AND GROWTH OF UNEVEN-AGE INTERIOR DOUGLAS-FIR (PSEUDOTSUGA MENZIESII VAR. GLAUCA) STANDS  BY RONDA LEE KOROL  A t h e s i s submitted i n p a r t i a l f u l f i l m e n t of the requirements  f o r the Degree o f  Master of S c i e n c e  in THE FACULTY OF GRADUATE STUDIES DEPARTMENT OF FORESTRY We accept t h i s  t h e s i s as conforming  t o the r e q u i r e d  standard  UNIVERSITY OF BRITISH COLUMBIA November 1985 ©  RONDA LEE KOROL, 1985  In p r e s e n t i n g  this thesis  in partial  an advanced degree at the U n i v e r s i t y the L i b r a r y  f u l f i l m e n t of the requirements f o r of B r i t i s h Columbia, I agree  s h a l l make i t f r e e l y a v a i l a b l e  f u r t h e r agree that  f o r reference  that  and study.  I  p e r m i s s i o n f o r e x t e n s i v e copying of t h i s t h e s i s f o r  s c h o l a r l y purposes may be granted by the Head of my Department by h i s or her  representatives.  this  thesis  I t i s understood that  f o r f i n a n c i a l gain  permission.  DEPARTMENT OF FORESTRY UNIVERSITY OF BRITISH COLUMBIA 2075 Wesbrook M a l l Vancouver, B.C., Canada V6T 1W5  Date:  November  27, 1985  copying or p u b l i c a t i o n of  s h a l l not be allowed without my  written  ABSTRACT  A study was initiated in 1984 to investigate the soil water regime and growth in uneven-age interior Douglas-fir stands. Eleven 10 m x 10 m microclimate plots covering a wide range of canopy coverages and twenty-two 25 m x 25 m inventory plots were established in the IDF and IDF biogeoclimatic subzones in the Kamloops a  area.  D  On one microclimate plot windspeed, relative humidity, air temp-  erature, solar irradiance, net radiation and soil temperature were measured.  Relative humidity, solar irradiance and air temperature were  measured on six additional plots, while on a l l eleven plots snow water equivalence, root zone water storage and rainfall were measured. The inventory plots, which had stand densities ranging from 96 to 2,784 trees h a , were located near the microclimate plots on areas partially - 1  logged between five and thirty years ago. trees on these plots.  There were a total of 956  One hundred trees were randomly selected for stem  analysis by falling and removing cross-sectional discs at ground level, breast height, base of the crown and midway through the crown. tional 700 increment cores were taken and analyzed.  An addi-  Diameter at breast  height was recorded for a l l the trees in a l l plots, while height and bark width was measured on 30% of the total number of trees.  The number  and age of the regeneration were obtained and a l l plots were mapped. Four permanent sample plots established by Balco Industries Ltd. were also remeasured. From the data obtained from the microclimate plots, the snow water equivalent depths, soil water matric potentials and courses of the soil water storage over the growing season were analyzed. (ii)  The growing season  e v a p o t r a n s p i r a t i o n and  transpiration  r a t e s , determined  balance method f o r each of the canopy coverages, It was  found  that although growing season  were roughly s i m i l a r f o r d i f f e r e n t  were a n a l y z e d .  evapotranspiration rates  canopy coverages,  transpiration rate varied considerably.  As  growing season  to d e c r e a s e .  be due  t r a n s p i r a t i o n r a t e tended  i n c r e a s i n g vapour p r e s s u r e d e f i c i t . p o t e n t i a l s had  T h i s was  was  Gross  ha  3  - 1  , and  densities,  about 37% of the t o t a l  stand d e n s i t y .  with i n c r e a s i n g year ) - 1  to  The  rainfall.  and h e i g h t growth r a t e r a t i o of the diameter  which had  stand d e n s i t y .  were found  stand volumes of 225 the annual  decreased  to h e i g h t  to 300  m  that there was  Stand r a t e s had  stand  .  with i n c r e a s i n g  and  240 m  - 1200  At lower  trees  stand  to i n c r e a s e w i t h  At stand d e n s i t i e s of > 1500 ha  stand volume.  trees  , annual  ha , - 1  volume  Furthermore,  i t was  a wide range of annual volume growth r a t e s that can  be o b t a i n e d f o r a g i v e n stand volume. different  ha  was  h i g h e s t growth r a t e s (9 -  at stand d e n s i t i e s of 901  stand volumes of between 96 and  growth r a t e decreased  The  volume growth r a t e s tended  i n c r e a s i n g stand volumes.  found  felt  Interception loss for  s u c c e s s f u l l y as a v a r i a b l e i n the l o c a l volume e q u a t i o n  decreased  ha  stand d e n s i t y i n c r e a s e d ,  Canopy r e s i s t a n c e i n c r e a s e d with  higher t r a n s p i r a t i o n r a t e s .  canopy coverage  with i n c r e a s i n g  11 m  season  S i t e s with h i g h e r s o i l water m a t r i c  Both the b r e a s t h e i g h t diameter  used  growing  to the l a r g e c o n t r i b u t i o n of the grass component to the  t r a n s p i r a t i o n at low canopy coverages.  a 100%  by the water  T h i s v a r i a t i o n was  due  to  densities.  diameter q-values  d i s t r i b u t i o n s which favoured annual (5 cm diameter  volume growth  c l a s s e s ) of between 1.28 (iii)  and  1.29.  There was a p o s i t i v e c o r r e l a t i o n between annual volume growth rate and growing season t r a n s p i r a t i o n f o r stands > 35% canopy coverage.  At  lower canopy coverages, the poor c o r r e l a t i o n was thought to be due to the large grass component.  The reduction i n the annual volume growth  rates of stand with densities > 1500 trees h a  - 1  appeared to be due to  increased between-tree competition and not s o l e l y to lower t r a n s p i r a t i o n rates because of i n t e r c e p t i o n  loss.  (iv)  T A B L E OF CONTENTS  Page ABSTRACT  i i  TABLE OF CONTENTS  v  LIST OF TABLES  viii  LIST OF FIGURES  ix  LIST OF SYMBOLS  . xiv  ACKNOWLEDGEMENTS  xvii  1.  INTRODUCTION  1  2.  THEORY  6  2.1 2.2 2.3 3.  4.  Forest Evapotranspiration R e l a t i o n s h i p Between Growth and T r a n s p i r a t i o n Uneven-age Stand Management  7 15 18  STUDY AREA  26  3.1 3.2 3.3 3.4 3.5  27 29 29 35 36  Location Climate Geology and S o i l s Vegetation Logging H i s t o r y  EXPERIMENTAL METHODS  40  4.1  F o r e s t Water Balance 4.1.1 F i e l d Measurements 4.1.2 A n a l y t i c a l Methods 4.1.2.1 Net R a d i a t i o n 4.1.2.2 E s t i m a t i o n of E v a p o t r a n s p i r a t i o n Using Water Balance A n a l y s i s  41 41 44 44  Volume Growth 4.2.1 F i e l d Measurements 4.2.1.1 Inventory P l o t s A. Data C o l l e c t i o n f o r Core A n a l y s i s B. Data C o l l e c t i o n f o r Stem A n a l y s i s 4.2.1.2 Permanent Sample P l o t s 4.2.2 A n a l y t i c a l Methods 4.2.2.1 Development of L o c a l Volume E q u a t i o n 4.2.2.2 Stand Growth  48 48 48 48 49 49 51 51 53  4.2  (v)  45  . . . .  . .  TABLE OF CONTENTS 5.  RESULTS AND 5.1  5.2  5.3  6.  7.  (continued)  DISCUSSION  Page 55  Water Balance Analysis 5.1.1 I n i t i a l S o i l Water Storage at the Beginning of the Growing Season 5.1.2 S o i l Water Storage D i s t r i b u t i o n i n the Root Zone 5.1.3 Course of S o i l Water Storage over the Growing Season 5.1.4 Evapotranspiration and Transpiration Rates Over the Growing Season 5.1.5 Factors Affecting Evapotranspiration and Transpiration  56  Relationships Derived from the Stem Analysis Trees ... 5.2.1 Relationships Between Diameter, Age and Stand Density 5.2.2 Relationsips Between Height, Age and Stand Density 5.2.3 Relationships Between Diameter-to-Height Ratio and Stand Density 5.2.4 The Local Volume Equation . . . . 5.2.5 Relationship Between Form Factor, Tree Diameter and Stand Density 5.2.6 R e l i a b i l i t y of the Local Volume Equation ....  91  Average Annual Volume Growth Relationships 5.3.1 Relationship Between Average Yearly Volume Growth and Stand Density and Volume 5.3.2 Relationship Between Average Annual Volume Growth and Stand Structure 5.3.3 Relationship Between Annual Volume Growth and Total Growing Season Transpiration  SUMMARY AND  CONCLUSIONS  56 60 64 70 78  91 94 96 103 104 106 109 109 118 121 125  6.1  Conclusions  125  6.2  Management Implications  129  LITERATURE CITED  133  (vi)  TABLE OF CONTENTS (continued) Page APPENDIX 1. APPENDIX 2. APPENDIX 3. APPENDIX 4. APPENDIX 5. APPENDIX 6.  Natural Regeneration Under a F a l l e r S e l e c t i o n Method 140 Analysis of Fish-eye Lens Photographs to to Determine Canopy Coverage 143 F o l i a r Analysis of the Lac Le Jeune and Knouff 12 km Sites . . . 149 Analysis of average volume growth by diameter class f o r a l l inventory plots i n three stand density classes f o r the 1978-1983 season. 153 The a, q and k c o e f f i c i e n t s , number of trees and stand volumes p r i o r to logging, immediately f o l l o w i n g logging, and c u r r e n t l y i n the stand . . . 156 Basal areas corresponding to the d i f f e r e n t stand volumes f o r the d i f f e r e n t density classes i n 1983 163  (vii)  L I S T OF TABLES  Page T a b l e 1: Table 2.  S o i l c h a r a c t e r i s t i c s of the m i c r o c l i m a t e p l o t s Summary of t r e e s sampled on the i n v e n t o r y p l o t s  31  (on per p l o t [1/16  50  ha] b a s i s )  Table 3 .  V a r i a b l e s i n f l u e n c i n g the i n i t i a l content  soil  water  T a b l e 4:  Changes i n the s o i l water s t o r a g e from May 3 to October 5, 1984  65  T a b l e 5:  E v a p o t r a n s p i r a t i o n r a t e s over the growing season (mm d a y )  72  61  - 1  T a b l e 6:  T r a n s p i r a t i o n r a t e s over the growing season (mm d a y  - 1  ).  76  Table 7:  Comparison of the t o t a l growing season t r a n s p i r a t i o n and t r a n s p i r a t i o n r a t e s  Table 8:  R a t i o of LE to [ s / ( s + y ) ] ( n " ) • (Also shown are m e t e o r o l o g i c a l v a r i a b l e s used i n the c a l c u l a t i o n of the a v a i l a b l e e n e r g y . ) R  evapo-  G  T a b l e 9: , .  Average vapour p r e s s u r e d e f i c i t s f o r time i n t e r v a l s .  Table  Average age and diameter at b r e a s t h e i g h t f o r d i f f e r e n t stand d e n s i t y c l a s s e s  10:  Table 11:  77  79  different  C u m u l a t i v e average h e i g h t growth r a t e f o r  .  85  the 92  stands  at d i f f e r e n t d e n s i t i e s .  98  T a b l e 12:  L o c a l volume t a b l e .  105  T a b l e 13:  T o t a l stand volume and d e n s i t y b e f o r e l o g g i n g ,  Table 14:  i m m e d i a t e l y f o l l o w i n g l o g g i n g and i n 1983 C u m u l a t i v e t o t a l stand volume from time of l o g l a s t l o g g i n g to 1983  T a b l e 15:  Course of annual volume growth 'from l o g g i n g to  110 Ill  1983  112  Table 16:  Summary of the permanent p l o t a n a l y s i s  115  Table 17:  Stand s t r u c t u r e c h a r a c t e r i s t i c s stand d e n s i t i e s  for  and growth r a t e s . (viii)  different .  119  LIST  OF  FIGURES  Page F i g u r e 1:  F i g u r e 2:  R e l a t i o n s h i p s between the water balance and e v a p o t r a n s p i r a t i o n components f o r a f o r e s t e d , p a r t i a l l y f o r e s t e d and grass s i t e . Only t r e e s a t l e a s t two metres i n h e i g h t are c o n s i d e r e d p a r t of the canopy. As the c o n t r i b u t i o n of the g r a s s component i s much h i g h e r than t h a t of the t r e e component f o r s i t e s w i t h l e s s than 5% canopy c o v e r a g e , these s i t e s are c o n s i d e r e d "grass" s i t e s  8  Map of study a r e a . The number l o c a t e d next the d i f f e r e n t symbols i n d i c a t e s the number of a c t u a l p l o t s at t h a t s i t e .  28  F i g u r e 3:  S o i l water r e t e n t i o n curves f o r the Lac Le Jeune site. . .  32  F i g u r e 4:  S o i l water r e t e n t i o n curves f o r the K n o u f f 12 km site  33  F i g u r e 5:  S o i l water r e t e n t i o n c u r v e s f o r the H e f f l e y s i t e .  F i g u r e 6:  R e l a t i o n s h i p between canopy coverage and s t a n d  F i g u r e 7:  F i g u r e 8:  F i g u r e 9:  F i g u r e 10:  F i g u r e 11:  density C a l i b r a t i o n of the n e u t r o n p r o b e s . Probe A i s from the B . C . M i n i s t r y of Environment w h i l e Probe B i s from A g r i c u l t u r e Canada  . . .  34  37 43  Course of the snow water e q u i v a l e n t depths on the p l o t s at the Knouff 12 km s i t e from January to June 1984  57  Course of the snow water e q u i v a l e n t depths on the p l o t s at the Lac Le Jeune s i t e from J a n u a r y t o June 1984  58  Course of the snow water e q u i v a l e n t depths f o r the H e f f l e y , Knouff 14 km and R e c r e a t i o n Area p l o t s from January to June 1984  59  D i s t r i b u t i o n of the s o i l water content f o r t h r e e p l o t s l o c a t e d at the Knouff 12 km s i t e on t h r e e d i f f e r e n t days  62  (ix)  LIST OF FIGURES (continued) Page F i g u r e 12:  F i g u r e 13:  F i g u r e 14:  D i s t r i b u t i o n of the s o i l water content f o r three p l o t s l o c a t e d at the Lac Le Jeune s i t e on t h r e e d i f f e r e n t days  63  The r a i n f a l l events and course of r o o t zone s o i l water s t o r a g e f o r the p l o t s at the Knouff 12 km s i t e  66  The r a i n f a l l events and course of r o o t zone s o i l water s t o r a g e f o r the p l o t s at the Lac Le Jeune s i t e  67  F i g u r e 15:  The r a i n f a l l events and course of r o o t zone water s t o r a g e f o r the H e f f l e y p l o t  F i g u r e 16:  The r a i n f a l l events and course of r o o t zone s o i l water s t o r a g e f o r the R e c r e a t i o n Area and Knouff 14 km p l o t s  69  Course of the s o l a r i r r a d i a n c e over the 1984 growing s e a s o n . These v a l u e s were c a l c u l a t e d as an average f o r the d a y l i g h t hours ( d a y l i g h t h o u r s (N) are i n Table 8)  71  The r e l a t i o n s h i p between the r a i n f a l l r e a c h i n g the ground ( P ) and r a i n f a l l above the canopy (P) f o r d i f f e r e n t canopy coverages  74  F i g u r e 19:  Changes i n P / P (c) w i t h canopy coverage  75  F i g u r e 20:  R e l a t i o n s h i p of the e v a p o t r a n s p i r a t i o n r a t e s t o s o i l water s t o r a g e and a v a i l a b l e energy ( R - G ) . A v a i l a b l e energy was c a l c u l a t e d as the average f o r the d a y l i g h t hours  80  The time course of E and T, the a v a i l a b l e energy and vapour p r e s s u r e d e f i c i t s f o r t h r e e p l o t s at the Knouff 12 km s i t e over the 1984 growing season.  82  The time course of E and T, the a v a i l a b l e energy and vapour p r e s s u r e d e f i c i t s f o r t h r e e p l o t s at the Lac Le Jeune s i t e over the 1984 growing season.  83  D a i l y t r a c e s of vapour p r e s s u r e d e f i c i t s t h r e e d i f f e r e n t days  84  F i g u r e 17:  F i g u r e 18:  soil  68  n  n  n  F i g u r e 21:  F i g u r e 22:  F i g u r e 23:  (x)  for  LIST OF FIGURES (continued) Page F i g u r e 24:  R e l a t i o n s h i p s between t r a n s p i r a t i o n and vapour p r e s s u r e d e f i c i t s f o r d i f f e r e n t canopy coverages and s o i l water m a t r i c p o t e n t i a l s g r e a t e r than - 0 . 5 MPa  87  R e l a t i o n s h i p s between t r a n s p i r a t i o n and vapour p r e s s u r e d e f i c i t s f o r d i f f e r e n t canopy coverages and s o i l water m a t r i c p o t e n t i a l s l e s s than - 0 . 5 MPa  88  R e l a t i o n s h i p s between canopy r e s i s t a n c e ( d r y ) and vapour p r e s s u r e d e f i c i t f o r d i f f e r e n t canopy coverages and s o i l water m a t r i c p o t e n t i a l s g r e a t e r than - 0 . 5 MPa  89  R e l a t i o n s h i p s between canopy r e s i s t a n c e ( d r y ) and vapour p r e s s u r e d e f i c i t s f o r d i f f e r e n t canopy coverages and s o i l water m a t r i c p o t e n t i a l s l e s s than - 0 . 5 MPa  90  R e l a t i o n s h i p s between diameter at b r e a s t h e i g h t (d) and age f o r t h r e e d i f f e r e n t stand d e n s i t i e s . Each l i n e i s the average diameter growth of f o u r t r e e s which were g r e a t e r than 125 years o l d  93  F i g u r e 29:  R e l a t i o n s h i p of the p r o p o r t i o n a l i t y constant (m) to stand d e n s i t y .  95  F i g u r e 30:  R e l a t i o n s h i p s between t o t a l h e i g h t and age f o r t h r e e d i f f e r e n t stand d e n s i t i e s . Each l i n e i s an average of the h e i g h t growth of f o u r t r e e s which were g r e a t e r than 125 years o l d .  F i g u r e 31:  R e l a t i o n s h i p s between the c u m u l a t i v e h e i g h t growth and stand d e n s i t y .  F i g u r e 32:  R e l a t i o n s h i p s between h e i g h t and diameter a t b r e a s t h e i g h t f o r t h r e e d i f f e r e n t stand d e n s i t i e s .  . .  100  F i g u r e 33:  R e l a t i o n s h i p s between h e i g h t and diameter at b r e a s t h e i g h t f o r t h r e e d i f f e r e n t stand d e n s i t i e s .  . .  101  F i g u r e 34:  R e l a t i o n s h i p between the d/H r a t i o and s t a n d density. The l i n e drawn i s from E q u a t i o n ( 5 4 ) .  . .  102  F i g u r e 25:  F i g u r e 26:  F i g u r e 27:  F i g u r e 28:  (xi)  99  LIST OF FIGURES ( c o n t i n u e d ) Page F i g u r e 35:  F i g u r e 36:  R e l a t i o n s h i p between the form f a c t o r and stand d e n s i t y f o r s e v e r a l v a l u e s of diameter at b r e a s t height  107  Comparison of p r e d i c t e d v e r s u s a c t u a l volumes of t r e e s 5 , 10 and 20 years ago. The s o l i d l i n e r e p r e s e n t s a 1:1 r e l a t i o n s h i p . The dashed l i n e r e p r e s e n t s the average r e l a t i o n s h i p of the p r e d i c t e d and a c t u a l volumes f o r a l l t h r e e time p e r i o d s . The a c t u a l e q u a t i o n s f o r the p r e d i c t e d (Vp) 5, 10 and 20 y e a r s a g o , as d e r i v e d from the a c t u a l volume ( V ) are V = 0.013 m + 0.909 V ; V = 0.005 m + 0.924 V ; and V = 0.007 m + 0.895 V , r e s p e c t i v e l y  108  The time course of the volume growth r a t e as r e l a t e d to stand d e n s i t y . The 301 - 600 and 601 - 900 l i n e s r e p r e s e n t an average of two p l o t s each w h i l e the 901 - 1200 l i n e r e p r e s e n t s an average of t h r e e p l o t s . Only one p l o t i s i n c l u d e d i n the 2701 - 3000 l i n e . .  113  The r e l a t i o n s h i p of t o t a l stand volume to a n n u a l volume growth f o r the d i f f e r e n t d e n s i t y c l a s s e s . Both the i n v e n t o r y and permanent sample p l o t s are i n c l u d e d .  117  The r e l a t i o n s h i p between annual volume growth and t o t a l growing season t r a n s p i r a t i o n . The e r r o r bars shown a r e f o r a 25 cm d t r e e w i t h an approximate h e i g h t of 29 m [ E q u a t i o n ( 5 2 ) ] , and assume t h a t the e r r o r s i n diameter and h e i g h t were 0.1 mm and 0 . 5 m, r e s p e c t i v e l y , f o r a one year growth p e r i o d on the permanent sample p l o t s and 0.1 mm and 0.1 m, r e s p e c t i v e l y , f o r a f i v e year growth p e r i o d on the i n v e n t o r y p l o t s . The form f a c t o r was determined to be 1.2 [ E q u a t i o n (62)] Open symbols i n d i c a t e p l o t s l o c a t e d next to a m i c r o c l i m a t e s t a t i o n , w h i l e the c l o s e d symbols i n d i c a t e t h a t T was i n t e r p o l a t e d from the m i c r o c l i m a t e p l o t s which had s i m i l a r s o i l c h a r a c t e r i s t i c s (from Table 7 ) . P l o t s marked w i t h a P are permanent sample p l o t s w h i l e the remainder are i n v e n t o r y p l o t s  123  a  a  p  F i g u r e 37:  F i g u r e 38:  F i g u r e 39:  p  3  3  p  3  a  a  (xii)  LIST OF FIGURES ( c o n t i n u e d )  Page F i g u r e 40:  R e l a t i o n s h i p between annual volume growth and t o t a l stand volume i n t e r p r e t e d f o r management purposes. M a i n t a i n i n g t h i s stand i n Zone A w i t h 900 to 1200 t r e e s ha w o u l d be c o n s i d e r e d o p t i m a l . The c u t t i n g c y c l e would be t e n y e a r s . I n cases where, a 20 year c u t t i n g c y c l e i s d e s i r e d , stands s h o u l d be m a i n t a i n e d w i t h between 800 - 1300 t r e e s h a and w i t h stand volumes r e p r e s e n t e d by Zone B . L o g g i n g i n Zone C s h o u l d be done w i t h c a u t i o n i f t h e r e are > 1500 t r e e s h a on the s t a n d , as stem c o l l a p s e would l i k e l y be a p r o b l e m . Logging down to Zone D would be u n a c c e p t a b l e , p a r t i c u l a r l y i f < 400 t r e e s ha remain a f t e r l o g g i n g . This i s due to both r e g e n e r a t i o n problems and low annual volume growth r a t e s . In a l l c a s e s , uneven-age s t a n d diameter d i s t r i b u t i o n s w i t h some l a r g e r r e s i d u a l t r e e s should be m a i n t a i n e d - 1  - 1  - 1  (xiii)  131  LIST OF SYMBOLS Symbol A  b a s a l area  m  D  drainage  mm  D  vapour p r e s s u r e d e f i c i t  kPa  E  evapotranspiration rate  mm  day  E(j  dry e v a p o r a t i o n r a t e  mm  day  E  0  free evaporation rate  mm  day  E  s  soil  mm  day  E  w  mm  day  wet  rate  evaporation rate evaporation rate  day"  1  F  c o n i c a l form f a c t o r  dimensionless  Fj  fraction  of the p e r i o d l e a v e s are dry  dimensionless  F  f r a c t i o n of the p e r i o d l e a v e s are wet  dimensionless  G  s o i l heat  W  m  -2  H  s e n s i b l e heat  W  m  -2  H  height  I  gross i n t e r c e p t i o n  I  w  t  gross  flux density flux density  m loss  tree i n t e r c e p t i o n  loss loss  mm  day  - 1  mm  day  - 1  mm  day  - 1  Ig  gross grass  interception  L  l a t e n t heat  of v a p o r i z a t i o n  L  length  m  M  r a t e of canopy energy storage  W m  N  number of t r e e s  trees  N  daylength  hours  P  above canopy r a t e of p r e c i p i t a t i o n  mm  (xiv)  J  kg  - 1  day  - 1  Symbol P  below canopy r a t e of p r e c i p i t a t i o n  mm  day  R  r a t e of runoff  mm  day  - 1  RH  r e l a t i v e humidity  %  R  n  net  W m  S  t  solar irradiance  day  - 1  mm  day  - 1  n  T T  r a d i a t i o n flux density  W m  . t o t a l t r a n s p i r a t i o n rate a  - 1  mm  a i r temperature  °K  Tfi  dry  Tg  grass t r a n s p i r a t i o n r a t e  mm  day  - 1  Tj;  tree  mm  day  - 1  U  windspeed  m  V  volume of t r e e  m  volume of cone  m  V  c  leaf t r a n s p i r a t i o n rate  t r a n s p i r a t i o n rate  W  s o i l water storage  a  solar absorption  a  r a t e of change i n number of successive  - 1  ram  c o e f f i c i e n t of v e g e t a t i o n trees  c  tree  Cp  s p e c i f i c heat of moist a i r  d  diameter  throughfall coefficient  height  dimensionless  in  diameter c l a s s e s  (at b r e a s t  s  cm  -1  dimensionless J kg  unless  otherwise noted)  cm  or  e *  s a t u r a t i o n vapour p r e s s u r e of the a i r  kPa  g  age  years  h  diameter c l a s s i n t e r v a l  cm  a  (xv)  °C~  - 1  m  1  Symbol number of t r e e s per h e c t a r e per  diameter t r e e s ha  interval sunshine ratio  hours  hours  of t r e e s i n s u c c e s s i v e  classes  cm"  1  diameter  (5 cm c l a s s e s i n t h i s t h e s i s )  aerodynamic r e s i s t a n c e  dimensionless s m~  1  canopy r e s i s t a n c e as d e f i n e d by Equation  (13)  s m _-1  r  cd  dry canopy r e s i s t a n c e  r  ct  canopy r e s i s t a n c e as d e f i n e d by Equation  s m  (21)  s m  s l o p e of s a t u r a t i o n vapour ratio with  of \ . dry  a x  to Egq  curve  kPa  "C"  1  for vegetation dimensionless  leaves  A  change i n a s s o c i a t e d parameter  dimensionless  Y  psychrometric  kPa  £a  e m i s s i v i t y of the atmosphere  dimensionless  e  emissivity  dimensionless  v  constant  of the v e g e t a t i o n  3  °C  9  v o l u m e t r i c s o i l water  P  d e n s i t y of moist a i r  kg  a  Stefan-Boltzmann  MJ m  s o i l water m a t r i c  content  constant potential  (xvi)  m  MPa  m  _ 1  -3  m -3 -2  d"  1  1  ACKNOWLEDGEMENTS  There are Of  s e v e r a l people f o r whose a s s i s t a n c e  p a r t i c u l a r importance were the h e l p and  s u p e r v i s o r , Dr. of Mr.  Trevor  T.A.  Black,  Jeanes,  Crabtree  provided  guidance of my  logistical of Balco  valuable  support  and  Industries  Forest  assistance  Alan Vyse  to thank f o r t h e i r advice  i n reviewing  of B.C.  equipment was  Dr. A l Van  provided  M i t c h e l l , B.C.  Other f i e l d  Davis,  Dennis  throughout  Dave  Bill  B.C.  Jack Cheng, B.C.  the of  Spittlehouse  C o l t e r of Crown  some a s s i s t a n c e  f o r data  collection.  M i n i s t r y of F o r e s t s , a s s i s t e d i n the  F i n a l l y I would l i k e support  to acknowledge my and  (xvii)  site selection.  Rene Thomson. monetary  support.  husband, J e r r y , f o r h i s  a l s o a s s i s t a n c e with  g r a t e f u l to Maureen Browning who  Forests,  Rocky Hudson, B.C.F.S.,  F o r e s t Research C o u n c i l , provided  u n d e r s t a n d i n g and  M i n i s t r y of  M i n i s t r y of  a s s i s t a n t s i n c l u d e Renata Piedmont and  Strang,  always be  Dr.  by Rod  Ryswyk, A g r i c u l t u r e Canada.  s u p p l i e d equipment and  Dr. Roy  Industries  the work are Dr. Peter M a r s h a l l  M i n i s t r y of F o r e s t s , and  Environment, Bruce C l a r k and  Bob  Ltd.  Products.  Field  and  suggestions  a s s i s t a n c e from Balco  U.B.C, Dr. Kenneth M i t c h e l l , Dr. Wayne Johnstone, Dr. Mr.  major  K e i t h Brown.  People whom I would l i k e  and  very g r a t e f u l .  Chan, Douglas G i l e s , Kenneth MacAulay, P a t r i c k L i n g e ,  and  study and  the  Vice-President  A d d i t i o n a l people who are R a n d a l l  and  I am  typed  the g r a p h i c s .  the  manuscript.  I will  1  1.  INTRODUCTION  2 1-  INTRODUCTION  Uneven-age stands c h a r a c t e r i z e  the i n t e r i o r D o u g l a s - f i r (IDF)  b i o g e o c l i m a t i c zone as a r e s u l t of past  logging practices,  and s i z e of n a t u r a l f i r e s , and the shade t o l e r a n c e Douglas-fir forest  (Pseudotsuga m e n z i e s s i i v a r g l a u c a  the  frequency  of i n t e r i o r  [Bessin] Franco).  All  stands i n the d r i e r IDF subzones are c u r r e n t l y r e q u i r e d to have  some form of p a r t i a l l o g g i n g as o u t l i n e d i n the Kamloops s i l v i c u l t u r e guide ( B . C . F . S . 1 9 7 9 ) . s u r f a c e temperatures  T h i s i s p a r t l y to prevent the h i g h ground  which would r e s u l t  from a c l e a r c u t .  The c u t t i n g  method s h o u l d r e l y on n a t u r a l r e g e n e r a t i o n as p l a n t a t i o n success i s very low ( C l a r k 1 9 6 2 ) .  Widespread use of diameter l i m i t and s e l e c t i o n  l o g g i n g systems has s l o w l y changed to a f a l l e r ' s s e l e c t i o n system of management.  T h i s system i s used p r i m a r i l y to encourage r e g e n e r a t i o n but  has the added advantage of enhancing the m u l t i p l e r e s o u r c e uses of land base (Johnstone 1 9 8 4 ) . selection  (uneven-age)  Both the s h e l t e r w o o d (even-age) or  r e g e n e r a t i o n systems would be  obtaining natural regeneration ' p r e f e r r e d management s y s t e m ' Therefore,  successful  ( K o s t l e r 1956); however the l a t t e r i s (B.C.M.F.  1981)  t h i s t h e s i s w i l l d e a l w i t h uneven-age  able c o n d i t i o n s for n a t u r a l regeneration  stands.  W i l l i a m s o n 1973; rule,  soil  Roeser 1 9 2 4 ) .  surface temperatures,  on f u l l y exposed s u r f a c e s ,  can c r e a t e f a v o u r -  ( H e l g e r s o n et a l . 1982;  S o i l t e m p e r a t u r e , p a r t i c u l a r l y at the s u r f a c e ,  the amount of shade ( C h i l d s et_ al_. 1985;  the  i n the Kamloops a r e a .  S h a d i n g , u s u a l l y i n the form of canopy c o v e r a g e ,  1979).  this  Marquis 1979;  Smith  i s a f f e c t e d by McDonald  I s a a c (1937) found t h a t ,  1976;  as a g e n e r a l  on a sunny day, c o u l d be 15-20°C h i g h e r  and 8-10°C  h i g h e r under a brush canopy than  3 the c o r r e s p o n d i n g a i r t e m p e r a t u r e . to the a i r  temperature under a c l o s e d f o r e s t  i n a study of a steep ( 3 0 ° ) , B.C.,  He found i t was a p p r o x i m a t e l y equal  found that  canopy.  Stathers  (1983),  south f a c i n g s l o p e on Vancouver I s l a n d ,  the daytime s o i l s u r f a c e  temperatures  d u r i n g the summer  remained above 50°C f o r seven h o u r s , and above 30°C f o r n i n e hours on a clearcut.  On areas which were shaded w i t h shade c a r d s ,  temperatures  never exceeded  they were g r e a t e r that  soil  50°C, and t h e r e were o n l y s i x hours when  than 30°C.  I n Oregon, C h i l d s et_ a l . (1985) showed  a s h e l t e r w o o d system s i g n i f i c a n t l y a m e l i o r a t e d s e a s o n a l  temperature  surface  c o n d i t i o n s and suggested  that  t e c h n i q u e where h i g h s o i l temperatures  soil  i t may be an a p p r o p r i a t e  limit reforestation  success.  I n s o l a t i o n damage to s e e d l i n g c o n i f e r s o c c u r s a t 64°C w i t h  exposure  p e r i o d s of l e s s than one hour  (Maguire 1 9 5 5 ) , but death from s e e d l i n g  d e s s i c a t i o n or c a m b i a l damage can occur at lower temperatures " d u r a t i o n ( B a l l a r d 1981; Shading increases  a l s o i n f l u e n c e s shoot and r o o t g r o w t h .  Increased  shading  root growth and decreases root r e s p i r a t i o n and shoot growth  area and subsequent  resistance increases  longer  Smith 1 9 5 1 ) .  (Krauch 1956), r e d u c i n g the shoot to root r a t i o , surface  of  moisture l o s s ,  (Ryker and P o t t e r 1970).  transpirational  thus i n c r e a s i n g drought  Too much canopy c l o s u r e ,  the s o i l m o i s t u r e and r o o t c o m p e t i t i o n and decreases  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 i n c i d e n t on the p l a n t . f o r D o u g l a s - f i r occured between 50% ( W i l l i a m s o n 1973) (Strothman 1972) California,  leaf  however, the  O p t i m a l shade  and 65%  canopy c l o s u r e i n the Oregon Cascades and n o r t h e r n  respectively.  4  A f a v o u r a b l e seedbed  i s also required for successful  Douglas-fir seedling establishment. consist  The most f a v o u r a b l e seedbed would  of a p p r o x i m a t e l y 25% m i n e r a l s o i l  W i l l i a m s o n 1973;  interior  ( B a l l a r d 1981;  Seidal  Smith 1951), a l o o s e g r a n u l a r s t r u c t u r e ,  c o l o u r to reduce s o l a r r a d i a t i o n a b s o r p t i o n (Krauch 1956; and a l o o s e  litter  (Krauch 1 9 5 6 ) .  a lighter Roeser 1924),  l a y e r which would r e t a i n the s o i l s u r f a c e  Selection  logging w i l l  1979;  moisture  generally mechanically disturb  the s o i l s u f f i c i e n t l y f o r seedbed p r e p a r a t i o n .  I n a problem a n a l y s i s by  C l a r k (1962) on the B i g Bar S u s t a i n e d Y i e l d U n i t i n i n t e r i o r B r i t i s h C o l u m b i a , i t was found t h a t established  91% of the t o t a l number of  seedlings  o c c u r r e d where seedbed and shade requirements were  I n a p r e l i m i n a r y e x a m i n a t i o n of the study area by the a u t h o r , found t h a t different (Appendix  s o i l surface  temperatures  canopy c o v e r a g e s ,  i t was  were reduced s i g n i f i c a n t l y under  and s e e d l i n g e s t a b l i s h m e n t  was  adequate  1).  Whereas  s o i l surface  temperatures  i n f l u e n c i n g seedling establishment, factor  adequate.  tend to be the major  s o i l m o i s t u r e may be the  i n f l u e n c i n g the growth of the r e s i d u a l stems (Watts  M i t c h e l l and Green 1 9 8 1 ) .  Selection  factor major 1983;  l o g g i n g may be c a u s i n g changes i n  the water regime which c o u l d a f f e c t the t r a n s p i r a t i o n r a t e of  the  stand.  These changes w i l l  i n f l u e n c e the growth r a t e of the  stems.  Although increased  growth r a t e s on the i n d i v i d u a l t r e e s are  forest  residual  uncommon f o l l o w i n g a p a r t i a l l o g g i n g , the c u t t i n g l e v e l and r e s i d u a l stand volumes n e c e s s a r y f o r o p t i m a l growth are unknown. Consequently, 1.  the o b j e c t i v e s of t h i s  To i n v e s t i g a t e  thesis  are:  how p a r t i a l l o g g i n g I n f l u e n c e s  the  water regime of uneven-aged i n t e r i o r D o u g l a s - f i r  soil stands.  not  5 2.  To determine the changes i n the volume growth of r e s i d u a l stems i n these stands as a r e s u l t of d i f f e r e n t  stand  s t r u c t u r e s and d e n s i t i e s . I n o r d e r to meet these o b j e c t i v e s , undertaken.  The f i r s t ,  t h e r e were two s t u d i e s  c a r r i e d out at two w i d e l y s e p a r a t e d  sites,  p r i m a r i l y d e a l t w i t h the water b a l a n c e i n stands h a v i n g a wide range of stand d e n s i t i e s .  T h i s r e q u i r e d the i n s t a l l a t i o n of s i x weather  and e l e v e n s o i l m o i s t u r e s a m p l i n g ( m i c r o c l i m a t e ) p l o t s . study d e a l t w i t h the l o n g term (5-30 1/16  years)  The second  growth r a t e s of twenty-two  ha i n v e n t o r y p l o t s u s i n g stem a n a l y s i s and increment  measurements.  stations  core  These p l o t s and f o u r a d d i t i o n a l p r e v i o u s l y e s t a b l i s h e d  permanent sample p l o t s were l o c a t e d near the m i c r o c l i m a t e p l o t s .  6  2.  THEORY  7 2. 2.1  Forest  Evapotranspiration  Forest  evapotranspiration  balance  THEORY  i s an important  component of the water  equation:  P+E  + D + R-  AW/At = 0  (1)  where AW, P, E, D, and R are, r e s p e c t i v e l y , the r a t e of change i n the s o i l water storage  i n the root zone, and the r a t e s of p r e c i p i t a t i o n ,  evapotranspiration, interval,  drainage and r u n o f f which o c c u r r e d  At. Evapotranspiration  E  where T  from the s o i l .  t  +.T  g  +  t  and Ig are the r a t e s  Under a  fully  s  this  small  c l o s e d canopy, the l a s t  t  terms of  two terms, because  f r a c t i o n of s o l a r r a d i a t i o n reaches the f o r e s t  + Tg , Ig w i l l  so that I « I , and E t  variables  i n (1)  s  will  and (2)  In  be assumed to be n e g l i g i b l e ,  a l s o be assumed to be n e g l i g i b l e . The  are i l l u s t r a t e d  energy t r a n s f e r r e q u i r e d  the l a t e n t heat  i n F i g . 1.  f o r the e v a p o t r a n s p i r a t i o n  of water  f l u x d e n s i t y , LE, ( t h e l a t e n t heat of v a p o r i z a t i o n ,  L, m u l t i p l i e d by E) and i s an important balance:  three  rate  As the canopy becomes l e s s dense, Tg becomes g r e a t e r .  thesis, T = T  The  cover, r e s p e c t i v e l y ,  i s the e v a p o r a t i o n  are u s u a l l y s m a l l when compared to the f i r s t  floor.  (2)  tg + E,s  t r a n s p i r a t i o n r a t e , and E  only a r e l a t i v e l y  is  + I  i n t e r c e p t i o n l o s s from the tree and grass  i s the grass  (2)  t  the time  r a t e can be d e f i n e d as  i s the t r e e t r a n s p i r a t i o n r a t e , I  t  of gross Tg  = T  during  component of the f o r e s t energy  ro . AW/At  TD (>85%  FORESTED Canopy C o v e r a g e )  AW/At  AW/At  TD  TD PARTIALLY FORESTED ( 5 - 8 5 % Canopy C o v e r a g e )  (0-5%  GRASS Canopy C o v e r a g e )  Figure 1: Relationships between the water balance and evapotranspiration components for a forested, p a r t i a l l y forested and grass s i t e . Only trees at least two metres i n height are considered part of the canopy. As the contribution of the grass component i s much higher than that of the tree component for s i t e s with less than 5% canopy coverage, these s i t e s are considered "grass" s i t e s .  9 R  n  (3)  - H - L E - G - M = 0  where R^, H, and G are the net r a d i a t i o n ,  s e n s i b l e and s o i l heat  d e n s i t i e s , r e s p e c t i v e l y , and M i s the r a t e of canopy energy  flux  storage.  The exchange o f s e n s i b l e and l a t e n t heat between the atmosphere and t h e forest  stand i s f a c i l i t a t e d  (Campbell  1977).  S e l e c t i o n l o g g i n g to d i f f e r e n t  d e n s i t i e s not o n l y a l t e r s (3)],  by t u r b u l e n c e w i t h i n and above the canopy  the m i c r o c l i m a t e  [i.e.,  stand s t r u c t u r e s and changing  the terms i n  but may i n f l u e n c e e v a p o t r a n s p i r a t i o n enough to s i g n i f i c a n t l y  change the water Penman  balance.  (1948)  combined the s u r f a c e energy  balance equation  (3)  and  the eddy d i f f u s i o n equations o f s e n s i b l e and l a t e n t heat  to produce the  (1965)  i n t r o d u c e d the  well-known Penman e v a p o r a t i o n e q u a t i o n . physiologically-based Penman-Monteith  Monteith  canopy r e s i s t a n c e i n t o the e q u a t i o n to give the  equation f o r c a l c u l a t i n g  the t r a n s p i r a t i o n r a t e assuming  the canopy i s dry (T^) as f o l l o w s  pc  s(R T  d  n  - G)  =  D  + -jE-  ±— C d  L  where R  n  (s +  Y  ( l+— ) )  - G i s the a v a i l a b l e energy  L, and s a r e , r e s p e c t i v e l y ,  (4)  ^  f l u x d e n s i t y , and p , C p ,  y>  the d e n s i t y of a i r , s p e c i f i c heat of a i r ,  the p s y c h r o m e t r i c c o n s t a n t , the l a t e n t heat o f v a p o r i z a t i o n , and t h e s l o p e of the s a t u r a t i o n vapour p r e s s u r e curve e v a l u a t e d at the a i r  10  temperature. resistance stand. given  The  The  aerodynamic r e s i s t a n c e , r , i s the a  between the  canopy and  canopy r e s i s t a n c e  diffusion above  leaves  the  (r j) C (  is  by  J  red -.  where LAI^ the  r±  and  are  s  evaporation w i l l l o s s from the a 100%  the  i t h l a y e r of the  Since E i s the  sum  be  si  GL A I i  1  (5)  l e a f area index and  of  the  e v a p o r a t i o n and  eliminated  trees.  and  r  stomatal  resistance  canopy.  by  be  over 20%  B l a c k 1981).  transpiration rates,  c o r r e c t i n g f o r the  E v a p o r a t i o n l o s s e s due  canopy coverage can  (Spittlehouse the  the measurement h e i g h t  f o r a canopy w i t h dry  n  of  eddy  of  the  gross  interception  to gross i n t e r c e p t i o n under growing season  G i l e s e t a l . (1985) found 8%  growing season r a i n f a l l was  l o s s under a 60%  and  100%  rainfall and  30%  of  canopy  coverage, r e s p e c t i v e l y . When the  leaves  can  be w r i t t e n  as  wet  canopy and  the  are wet,  the dry  sum  of the  and  dry  (F  w  and  f r a c t i o n of  the  evaporation rate  the  w  period  E  + F  w  the  F  evapotranspiration from a (E  w  f r a c t i o n of the p e r i o d  F j , r e s p e c t i v e l y ) as  E = F  The  average r a t e of  canopy t r a n s p i r a t i o n r a t e  r e s p e c t i v e l y ) weighted by wet  the  w  d  T  leaves  =  I/F^  and  completely T , d  the  leaves  are  follows  (6)  d  are wet  i s given  by  (7)  11  where I i s the r a t e of gross The  the e n t i r e p e r i o d .  f r a c t i o n of the p e r i o d the l e a v e s a r e dry i s g i v e n by  F  The  i n t e r c e p t i o n l o s s over  evaporation  = 1 - F  d  (8)  w  r a t e from leaves when c o m p l e t e l y  wet, i s  pc D  s(R E  Substituting  =  w  (7) and (8) i n t o  E = T  Substituting  ,  )  Y  d  p  r  L(s +  IS  (  9  )  (6) g i v e s  (10)  w  (10) g i v e s  s ( R - G) + p c D / r n  —L_  + 1(1 - T / E )  d  (9) and (4) i n t o  L(s + Y(l +  so  n  - G) +  ^  a  _  s + s +  a  Y  ^  Y  (l + r  ^  a  that s(R  - G) +  n  E =  PCpD _ -  _  (12)  L ( s + Y d + [1 - J - ] ) ) ^  Therefore,  an equation  f o r E which would take i n t o account p e r i o d s when  leaves are wet f o r p a r t of the time can be w r i t t e n as  pc D — p  s(R  n  - G) +  E =  ^  L ( s + ( l +-T")) Y  (13)  12  where the combined wet and dry canopy r e s i s t a n c e  r  Equation  c  = (1 - I / E ) r  (r )is c  (14)  c d  (14) i s Thorn and O l i v e r ' s (1977) e q u a t i o n ( 2 5 ) .  The average t r a n s p i r a t i o n r a t e f o r a canopy f o r which there i s gross i n t e r c e p t i o n l o s s e s i s , n e g l e c t i n g  soil  evaporation,  T = E - I  Equation  (15)  (10) can be s u b s t i t u t e d i n t o e q u a t i o n  T  T = T  d  - I  d  _1_ E  Substituting  (15) to g i v e  (16)  w  (9) and (4) i n t o (16) g i v e s  pc D D  s(R X =  n  : L(s +  - G) Y  —f-  I ( s + y) -  ( i + - £ ! ))  s +  Y  ( l + -£! )  (17)  or  pc D D  s(R T =  n  - G) +  -f~  - L I ( s + y) r  cd  (18)  L[s + y ( l + - T - ) ] 2  The canopy r e s i s t a n c e of the canopy ( w h i l e  i t i s dry) during a period i n  13  which the leaves  are wet p a r t of the time i s obtained  using  (18)  r e w r i t t e n as  r  c d <,  P°o  LT(s + y ( l + -£2-)) = s(Rn - G) + — 2 r  so  L I ( s + Y)  d9)  that  pc D D  r  c  d  C d  r  = —E- + r LT a  Y  Note that  s,(R  a  L Y  " G)  n  i  ._( J L LT  and T = E,  r  s  D  - ^ + r  (19a)  (2) of Tan and B l a c k (197 6)  i.e.  pc D  c d  j  - - - 1 - 1 - 1 T T  t h i s reduces to e q u a t i o n  when 1 = 0  If  D  a  a canopy r e s i s t a n c e  (R  n  - G)  [ - ( - - 2 — -  (r  c t  1 ) - 1]  ) was d e f i n e d  (20)  as f o l l o w s  pepD  s(R  n  -f-  - G) +  T = L[s + y(l r  for a period  (21)  a  d u r i n g which r a i n o c c u r r e d ,  then r  c  t  would be  ' c f ^ + r .  The (22)  r e l a t i o n s h i p between r from (19a) i s  (22)  c  d  and r  c  t  obtained  by s u b t r a c t i n g  14  s +  y  (23)  Y  P r i e s t l e y and dry-leafed  Taylor  vegetative  (1972) demonstrated that f o r a smooth  surface  (e.g. a g r i c u l t u r a l c r o p ) , w i t h adequate  water, t r a n s p i r a t i o n i s w e l l c o r r e l a t e d w i t h the f i r s t ,  or r a d i a t i v e  term, of the Penman-Monteith equation,  be  T  = a[s/(s +  d  where a i s an e x p e r i m e n t a l l y  Y  so that  )](R  n  -  i t could  expressed  (24)  G)/L  determined c o n s t a n t .  This  approach  been shown to work q u i t e w e l l f o r extremely rough s u r f a c e s f o r e s t s ) on a daytime or 24 hour b a s i s S h u t t l e w o r t h and  Calder  Over s h o r t e r showed that estimated  the  1978;  time p e r i o d s  =  d  Note that p c / ( L Y ) = ( R v a ) ~ T  p  T  the  and  (e.g.  Black  Tan  and  (1976)  f o r e s t stands can  be  by  (25)  [pc /(L )][D/r ] p  Y  where R  c d  v  i s the gas  and  r  a  content f o r  E q u a t i o n (18)  approaches zero,  c o n t r i b u t i o n of the  reduces  as i s the  case  r a d i a t i v e term becomes s m a l l .  Stomatal r e s i s t a n c e of f o r e s t canopies i s a f u n c t i o n of - 0.7  1981;  Black  I n t h i s case, t r a n s p i r a t i o n i s p r i m a r i l y a f u n c t i o n of D and  t h e t i c photon (0.4  has  Black 1973).  hour),  i s the a i r temperature.  a  to t h i s equation when 1 = 0 f o r e s t s , and  one  t r a n s p i r a t i o n from d r y - l e a f e d  T  for  (e.g.,  to a good approximation  water vapour and  (Spittlehouse  McNaughton and  as  vim) f l u x d e n s i t y ,  r . c  photosyn-  s o i l water p o t e n t i a l  (4 ) S  15 ( o r predawn l e a f water p o t e n t i a l ) (McNaughton and J a r v i s  1983).  and vapour p r e s s u r e  deficit  Tan et_ a l . (1978) found t h a t ,  the d a y t i m e , s t o m a t a l r e s i s t a n c e was r e l a t e d to s o i l water and D i n D o u g l a s - f i r t r e e s on Vancouver I s l a n d .  during potential  They showed t h a t E  i n c r e a s e d w i t h i n c r e a s i n g D , r e a c h i n g a maximum v a l u e and t h e r e a f t e r d e c l i n i n g , as a r e s u l t found t h a t  of r  s  i n c r e a s i n g markedly w i t h D.  They  the v a l u e of D at maximum t r a n s p i r a t i o n i n c r e a s e d  also  with  i n c r e a s i n g i(, . s  2.2  R e l a t i o n s h i p Between Growth and T r a n s p i r a t i o n It  has been r e c o g n i z e d f o r many y e a r s  growth i s c o r r e l a t e d w i t h t r a n s p i r a t i o n .  that, Boyer  f o r many p l a n t s , (1976) suggested  t h i s e m p i r i c a l r e l a t i o n s h i p can be used to e s t i m a t e g r o w t h . (1958) was the f i r s t  that  De Wit  t o f o r m a l i z e t h i s e m p i r i c a l r e l a t i o n s h i p as  Y = mT  (26)  where Y i s the r a t e of crop dry matter y i e l d and m i s an e x p e r i m e n t a l l y determined c o n s t a n t .  T h i s e q u a t i o n worked w e l l f o r a g r i c u l t u r a l crops  at mid to n o r t h e r n l a t i t u d e s the B . C . Peace R i v e r r e g i o n ) . limited, that  ( e . g . W a l l i s et^ a l . (1983) f o r hay crops i n I n a r i d c o n d i t i o n s where m o i s t u r e was  (26) d i d not work w e l l .  F o r t h i s c a s e , de Wit (1958) found  dry matter y i e l d r a t e was b e t t e r determined as  Y = nT/E  Q  (27)  16 where n i s an e x p e r i m e n t a l l y determined c o n s t a n t water e v a p o r a t i o n r a t e .  and E  E  T h i s i s because the  i s a p p r o x i m a t e l y p r o p o r t i o n a l to E / T i n a r i d c o n d i t i o n s where 0  tends  Q  i s the f r e e  E q u a t i o n (27) s t a t e s that Y i s a p p r o x i m a t e l y  i n v e r s e l y p r o p o r t i o n a l to s t o m a t a l r e s i s t a n c e . latter  0  t o be p r o p o r t i o n a l t o D.  Assuming aerodynamic and boundary l a y e r r e s i s t a n c e s are s m a l l , leaf  t r a n s p i r a t i o n i s equal to ( R T ) ~ ^ D / r g ) and the net v  photosynthesis  i s e q u a l to ( c  the c o n c e n t r a t i o n s respectively.  a  - Ci)/r ,  a  where c  s  a  and c^ are  of a t m o s p h e r i c and i n t e r n a l ( l e a f ) carbon d i o x i d e ,  Consequently,  the r a t i o of y i e l d t o t r a n s p i r a t i o n would  be  Y/T = c ( l a  B i e r h u i z e n and S l a t y e r r a t i o was c o n s t a n t ,  C i  /c )R T /D a  v  (1965) suggested  r a t e of dry matter  (28)  a  t h a t where the c ^ / c  y i e l d c o u l d be expressed  a  as  Y = kT/D  (29)  where D/T i s p r o p o r t i o n a l t o s t o m a t a l r e s i s t a n c e , was s i m i l i a r to de W i t ' s c o n s t a n t , c  i/ a c  r a t l  equation  °  w a s  constant  (29) t o a p o t a t o  n.  and the c o n s t a n t ,  k,  Wong et a l . (1981) found t h a t t h e  i n several plants. l e a f and e s t i m a t e d  Tanner  (1981) a p p l i e d  the y i e l d f o r an e n t i r e  crop by summing t h i s f o r the l e a f a r e a i n d e x ( L A I ) of the c r o p , and i n c l u d i n g the e f f e c t of growth and maintenance  respiration.  17  In  forestry,  several  workers have shown a good c o r r e l a t i o n between  growing season water d e f i c i t s , site  indices  or  on Vancouver I s l a n d  t r a n s p i r a t i o n , and  ( G i l e s et a l . 1985). between tree  balance model could  t r a n s p i r a t i o n , while basal  to be  Spittlehouse  growth and  correlated  be used to i n d i c a t e  evapotranspiration  found to be w e l l  Leaf area index, which has  correlated  (Gohlz 1982;  productivity. tal  available  (1978), would be  and  low  G r i e r and  may  and,  and  as  the  productivity  of a i r and  due  In t h i s  melt, r a i n f a l l  reduction Price  light  was  not  although a reduction  in  interception  l o s s and  forest  is  stoma-  et_ a l . of  the  et_ a l . not  generally transpiration  study s o i l water p o t e n t i a l might be as a r e s u l t of d i f f e r e n c e s  soil  to h i g h e r  found by Tan  growth r a t e .  u n l e s s D i s h i g h , and  stomatal r e s i s t a n c e ,  have o c c u r r e d .  to  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 rate  therefore,  to vary with stand d e n s i t y fall  s o i l moisture on  influence  photosynthesis i n coastal Douglas-fir  l i m i t e d by  related  Running 1977).  s o i l water p o t e n t i a l s ,  (1985), however, found that limiting,  linearly  expected to r e s u l t i n a p r o p o r t i o n a l  photosynthetic rate  water  Waring (1977) found a very high c o r r e l a t i o n between  Reductions i n the  resistances  Sitka  with annual volume growth.  a p h o t o s y n t h e t i c index (which combined the temperatures and  Jarvis  of s o i l  i s c l o s e l y r e l a t e d to stand  Schroeder et_ a l . 1982;  Emmingham and  a water  growth model f o r  a function  been found to be  e s t i m a t e d s o i l water d e f i c i t s ,  that  correlation  site productivity.  spruce i n which a growth index, which was d e f i c i t , was  deficits  found good a  suggested  with area  to s o i l water  (1983) a l s o  t r a n s p i r a t i o n , and  et a l . (1983) developed an  Forest  were shown to c o r r e l a t e w e l l  growing season water d e f i c i t s and annual increments were found  growth.  expected  i n snow through-  transpiration  rate.  18 2.3  Uneven-age Stand Management Gibbs (1978) d e f i n e d uneven-age  s i l v i c u l t u r e and management  as  the  " m a n i p u l a t i o n of a f o r e s t f o r a c o n t i n u o u s h i g h - f o r e s t c o v e r , r e c u r r i n g r e g e n e r a t i o n of a d e s i r a b l e s p e c i e s , and the o r d e r l y growth and development of t r e e s through a range of age or diameter c l a s s e s to p r o v i d e a s u s t a i n e d y i e l d of forest products. Managed uneven-age f o r e s t s are c h a r a c t e r i z e d by t r e e s of many ages, or s i z e s , i n t e r m i n g l e d s i n g l y or i n groups. Trees are h a r v e s t e d s i n g l y or i n v e r y s m a l l groups and the p r o c e s s of r e g e n e r a t i o n of the d e s i r a b l e s p e c i e s occurs e i t h e r c o n t i n u o u s l y or at each h a r v e s t . Each h a r v e s t u s u a l l y i n c l u d e s t h i n n i n g and c u l t u r a l t r e a t m e n t s to promote growth and m a i n t a i n or enhance stand s t r u c t u r e . " The advantages tion,  of the s e l e c t i o n  method, as i n d i c a t e d i n the  i n c l u d e e n s u r i n g the n a t u r a l r e g e n e r a t i o n  and e x c e l l e n t  site protection,  or wind ( D a n i e l et_ a l . to a p p l y the f a l l e r ' s  1979).  of a t o l e r a n t  w i t h l i t t l e or no exposure  species  to  insolation  Johnstone (1984) suggests t h a t i n order  selection  method i t  an e v e n l y d i s t r i b u t e d f o r e s t c o v e r , (iii)  introduc-  (ii)  i s n e c e s s a r y to ( i )  maintain  remove poor q u a l i t y t r e e s , and  improve s p a c i n g . The t h r e e major a s p e c t s of the s t r u c t u r e  volume, diameter  d i s t r i b u t i o n and s p e c i e s c o m p o s i t i o n (Davies  t r e e s p e c i e s other ( l e s s than 10%)  of an uneven-age  than i n t e r i o r D o u g l a s - f i r are o n l y a minor  of the uneven-age  stands  i n the I D F  subzone i n the i n t e r i o r of B . C . , o n l y the f i r s t together with t h e i r  a  stand  are  1966).  As  component  and IDF^  two w i l l  be  discussed,  interrelationships.  Volume growth p r e d i c t i o n s have been developed i n B . C . f o r t r e e s p e c i e s , but u n f o r t u n a t e l y , stands age.  and g e n e r a l l y Meyer et_ aT.  are o n l y a v a i l a b l e  several  f o r pure even-age  i n v o l v e s i t e i n d e x or p r o d u c t i v i t y as a f u n c t i o n of  (1952) s t a t e s  that  "under t h i s concept of (uneven-age) management the a c t u a l age of any g i v e n t r e e or group of t r e e s i s of l i t t l e or no  19 p r a c t i c a l importance. Volume per a c r e cannot be e x p r e s s e d as a f u n c t i o n of age, and the use of the r o t a t i o n as the b a s i s f o r r e g u l a t i o n i s no l o n g e r v a l i d . S i m i l a r l y , y i e l d tables based on stand age are meaningless because s i t e i n d e x cannot be o b t a i n e d from dominant t r e e c h a r a c t e r i s t i c s as determined f o r even-age s t a n d s . An e n t i r e l y d i f f e r e n t p h i l o s o p h y of management based on d i f f e r e n t concepts and c h a r a c t e r i s t i c s must be e v o l v e d . " Walker (1956) f u r t h e r  concluded t h a t " t h e a d a p t a t i o n  of net y i e l d  d a t a from even-age stands to uneven-age f o r e s t c o n d i t i o n s inaccurate,  and a waste of  to the c u t t i n g c y c l e .  The  aim of management i s to m a i n t a i n maximum growth r a t e s by c u t t i n g  b e f o r e the c u r r e n t defines  i s misleading,  time."  Growth of uneven-age stands i s r e l a t e d general  table  growth r a t e s d i m i n i s h s i g n i f i c a n t l y .  the volume of growing s t o c k a t t h r e e d i f f e r e n t  1.  The volume j u s t a f t e r a c y c l i c c u t .  2.  The volume j u s t b e f o r e a c y c l i c c u t .  3.  The average volume midway through the c u t t i n g  The t h i r d i s u s e f u l i n d e s c r i b i n g f o r e s t u n i t as a w h o l e . cutting cycle  Davies levels:  cycle.  the average g r o w i n g - s t o c k  I n order to m a i n t a i n a s u s t a i n e d  s h o u l d correspond  (1966)  l e v e l of a  yield,  the  to the time r e q u i r e d to r e g a i n the  volume removed i n the i n i t i a l c u t and i n c l u d e any adjustments made i n the growing s t o c k . r  Growth i n a p a r t i c u l a r  stand w i l l v a r y from year to year due to  c l i m a t i c and changing growth c o n d i t i o n s . diameter  classes w i l l also vary.  The growth r a t e s of  A b a l a n c e of these b i o l o g i c a l  i s n e c e s s a r y to o p t i m i z e the t o t a l growth r a t e of a s t a n d . it  may be n e c e s s a r y to i n c r e a s e or reduce  a better size d i s t r i b u t i o n .  different factors  Therefore,  the growing s t o c k to encourage  Too low a r e s e r v e growing s t o c k , o r  r e s i d u a l number of stems, would not f u l l y u t i l i z e the s i t e  productivty,  20 w h i l e too h i g h a growing s t o c k would reduce the stand v a l u e and volume growth through o v e r s t o c k i n g .  It  i s a l s o necessary  to m a i n t a i n a  d e s i r a b l e diameter d i s t r i b u t i o n which w i l l support the c o n t i n u i n g stand entries.  De L i o c o u r t (1898) determined t h a t a balanced  sustainable  d i a m e t e r d i s t r i b u t i o n was c h a r a c t e r i z e d by an i n v e r s e J-shape a constant  r a t i o , q , of t r e e s i n s u c c e s s i v e diameter c l a s s e s .  In order  t o determine the a c t u a l , or d e s i r e d , diameter d i s t r i b u t i o n , i t necessary  curve w i t h  Is  to know the d e s i r e d q - v a l u e , r e s i d u a l b a s a l a r e a , and the  maximum t r e e s i z e (Marquis 1978). Moser (1976) d e s c r i b e d the diameter d i s t r i b u t i o n u s i n g a n e g a t i v e exponential function:  N = ke"  (30)  a d  where N i s the number of t r e e s per h e c t a r e f o r diameter (at  breast  height) class  c h a r a c t e r i z i n g a given d i s t r i b u t i o n .  per diameter c l a s s  d , and k and a are  coefficients  The c o e f f i c i e n t a determines  r a t e at which the number of t r e e s change between s u c c e s s i v e classes.  In p r a c t i c e ,  i t can be  interval  the  diameter  c a l c u l a t e d from N and d measurements  as f o l l o w s :  [ln(N j / N ) ] 2  a =  (31) d  where  2 ~  d  l  and N are the number of stems i n s u c c e s s i v e 2  d^ and d 2  The r a t i o of N / N  diameter c l a s s  1  2  diameter  classes,  i s the v a l u e of q f o r a stand w i t h a  i n t e r v a l of dz ~ d\,  or h .  If  q i s known and c o n s t a n t ,  21 a can be c a l c u l a t e d from an approximate r e l a t i o n s h i p between a and q , for q < 1.3. (30)  This r e l a t i o n s h i p i s  w i t h respect  found by t a k i n g the d e r i v a t i v e of  to d as f o l l o w s :  dN = - a k e ~ d d  (32)  a d  D i v i d i n g (32)  by (30)  gives  dN  No -  « —£ N  N  so  Ni  L « —ah  (33)  2  that a « (q •- l ) / h f o r q < 1.3  i •  The c o e f f i c i e n t  (34)  k i s the number of t r e e s per h e c t a r e per  class  i n t e r v a l as d approaches  zero.  area,  A , i s known, k can be c a l c u l a t e d as f o l l o w s :  When the a c t u a l or d e s i r e d b a s a l  2  k = -(4A/ir)[{— + ^  where d^ and d  2  2.  (ad  + 1) }e" 2 - (iL +  2  zero and d  2  =  2  k = (4A/ir) [~~7 a°  A  (35)  2  a a  3  + l)}e"  d and i s r e p r e s e n t a t i v e  , -adr — + ~T(ad + 1) e ] a a 1  l  diameter c l a s s e s .  d e s i r a b l e or a c t u a l t r e e on the s t a n d ,  r  (ad  ad  are the s m a l l e s t and l a r g e s t  cases where d ^ approaches largest  diameter  reduces  a d  l]  (35)  _ 1  In of  the  to  1  (36)  R e s e a r c h e r s have demonstrated an e m p i r i c a l r e l a t i o n s h i p showing a p o s i t i v e c o r r e l a t i o n between a and k (Meyer et a l .  1961).  The v a l u e of q and a w i l l vary depending on the r a t e of  diameter  growth and the growing space r e q u i r e d f o r each c l a s s and the desirable  diameter f o r the crop t r e e s .  intervals)  g e n e r a l l y range from 1.1  largest  V a l u e s of q (5 cm diameter  to 2 (Meyer 1952), w i t h the lower  the q v a l u e the h i g h e r the growing space u t i l i z e d by l a r g e r , valuable trees.  class  more  Maintenance a l s o i n c r e a s e s w i t h low q v a l u e s due to  number of s m a l l stems which develop and s h o u l d be removed.  Growing  space o c c u p i e d by s u r p l u s s m a l l stems can o n l y be u t i l i z e d at expense of the l a r g e r  the  the  stems.  A l t h o u g h t h i s e m p i r i c a l approach i s u s e f u l f o r d e s c r i b i n g a desirable  diameter d i s t r i b u t i o n , b i o l o g i c a l f a c t o r s  determine  the a c t u a l diameter d i s t r i b u t i o n (Davies 1966;  P h i l l i p 1977). it  is.  The f l a t t e r  s h o u l d be used to Leak and  the c u r v e , the more e c o n o m i c a l l y  favourable  T h i s diameter d i s t r i b u t i o n , however, i s l e s s l i k e l y to be b i o l o -  g i c a l l y sustainable  f o r l o n g p e r i o d s of t i m e , due to m o r t a l i t y i n the  younger, s m a l l e r diameter c l a s s e s . diameter classes w i l l  vary w i t h the l a r g e r  r a t e than the s m a l l e r t r e e s . compensated  The growth r a t e s of the  different  t r e e s growing at a f a s t e r  A d e f i c i e n c y i n one diameter c l a s s may be  by f a v o u r i n g the growth r a t e s of the t r e e s i n the  s m a l l e r diameter c l a s s .  The diameter d i s t r i b u t i o n can have a  cant impact on gross volume i n c r e a s e  or p o s s i b l e  next signifi-  s u s t a i n e d gross  yield  of a stand (Meyer 1952). Currently,  the m a j o r i t y of the uneven-age  stands  in i n t e r i o r B.C.  are u n s t r u c t u r e d and, as s u c h , have an unbalanced diameter d i s t r i b u t i o n w i t h an abundance of some diameter c l a s s e s and a r e d u c t i o n or absence of  23 others.  Any growth p r o j e c t i o n s  these stands  based on the past m o r t a l i t y r a t e s of  may be u n r e l i a b l e f o r e v a l u a t i n g d i f f e r e n t  or l o n g term p r o j e c t i o n s  (Johnstone  growth and s i t e index  f o r i n t e r i o r D o u g l a s - f i r i n the Rocky M o u n t a i n s , u s i n g  stands  difference  The sample s i t e t r e e s s e l e c t e d were  dominant t r e e s , w i t h no o b s e r v a b l e  establishment. essentially  of s u p p r e s s i o n ,  and r e g u l a r r a d i a l growth  A l t h o u g h the t r e e s grew i n uneven-age  t r e e s w i l l p r o v i d e an i n d i c a t i o n of r e l a t i v e s i t e p r o d u c t i v i t y , but cannot f o r a g i v e n stand s t r u c t u r e  the  damage, w e l l developed and h e a l t h y  (e.g.,  since  stands,  open-grown w i t h l i t t l e c o m p e t i t i o n e v i d e n t .  Langsaeter  and no  i n these curves and ones developed from even-age  i n the same a r e a .  crowns, no s i g n s  curves  uneven-age  He found no changes i n h e i g h t growth w i t h s t o c k i n g ,  significant  structures  1984).  Monsurud (1984) has developed h e i g h t  stands.  stand  they were  These s i t e  good, f a i r ,  poor)  be used to p r o j e c t a c t u a l volume growth  and d e n s i t y .  (1941) h y p o t h e s i z e d t h a t f o r an even-age stand the  y e a r l y volume growth per h e c t a r e remains c o n s t a n t over a range of stand volumes.  Yearly height  c o n s t a n t over t h i s  growth i s a l s o assumed to be  range of stand volumes.  total total  relatively  An i n c r e a s e i n y e a r l y volume  growth per h e c t a r e w i t h i n c r e a s i n g s t o c k i n g w i l l be observed only when s t o c k i n g i s low and t h e r e i s u n f i l l e d growing s p a c e . growth occurs general (Smith  between 60% of f u l l  s t o c k i n g and f u l l  r u l e i s a l s o b e l i e v e d to be a p p l i c a b l e  O p t i m a l stand stocking.  to uneven-age  This stands  1962).  Walker (1956) d e f i n e s s t o c k i n g at which the  full  s t o c k i n g of an uneven-age  stand as  " f u l l p r o d u c t i v e c a p a c i t y " of the s i t e i s  w i t h a minimum of s u p p r e s s i o n and m o r t a l i t y .  While i n t h i s  the  utilized  optimal  24 range,  t h i n n i n g does not i n c r e a s e  redistributes  the t o t a l p r o d u c t i o n , but  the growth on fewer stems.  Once a c r i t i c a l p o i n t i s  reached and the stands become o v e r s t o c k e d , due to c o m p e t i t i o n .  rather  t o t a l s t a n d growth decreases  This c r i t i c a l stocking l e v e l v a r i e s with  site  characteristics. There have been some s t u d i e s , however, i n which t o t a l p r o d u c t i v i t y did increase levels.  Barrett  above t h a t  (1973) found t h a t  stand  indicated with optimal stocking  l o g g i n g o l d growth ponderosa p i n e  ( P i n u s ponderosa Laws) to leave o n l y the advanced r e g e n e r a t i o n i n a t h r e e - f o l d volume growth r a t e i n c r e a s e  over that of the o l d growth  overstory.  The growth r a t e of s a p l i n g s was s t i l l  years a f t e r  t h i n n i n g and the author e s t i m a t e d  growth r a t e f i v e to s i x times  rising rapidly  i t was suggested  that of the o r i g i n a l o v e r s t o r y .  that  eight  t h a t i t would have a  another study by Tiramer and Weetman ( 1 9 6 9 ) , on b l a c k spruce mariana),  resulted  In (Picea  t o t a l p r o d u c t i o n would be g r e a t e r  than  that which would occur f o l l o w i n g t h i n n i n g due to an improved thermal environment. stands,  A l t h o u g h these examples are on p r e d o m i n a n t l y  they i l l u s t r a t e i n s t a n c e s  even-age  where volume growth was i n c r e a s e d  with  stand m a n i p u l a t i o n . For a g i v e n c u t t i n g c y c l e and s i t e q u a l i t y , t h e r e  i s an optimum  s t a n d s t r u c t u r e and d e n s i t y which w i l l r e s u l t i n the maximum p r o d u c t i v e c a p a c i t y and net r e t u r n (Davies 1966). site  The p r o d u c t i v e c a p a c i t y of  can o n l y be f u l l y r e a l i z e d w i t h the e s t a b l i s h m e n t  and maintenance  of the d e s i r a b l e growing s t o c k at these l e v e l s .  It  accepted  i n the s o u t h e r n  that  the u n s t r u c t u r e d uneven-age  stands  i o r of B . C . are not c u r r e n t l y at t h i s l e v e l .  the  is  Therefore,  generally  an  inter-  increase  volume growth i n these stands c o u l d be a c h i e v e d by the b a l a n c i n g of  the  age c l a s s e s .  T h i s would  result  in a better u t i l i z a t i o n  a r e a , both s p a t i a l l y and over time (Knuchel 1953). occupy a l l of the s t r a t a , and mature f u n c t i o n of age, but may ( D a n i e l et a l . 1979;  of the growing  Trees are able to  t r e e s are not h a r v e s t e d merely as a  be allowed to a c h i e v e a d d i t i o n a l volume growth  Smith 1962).  26  3.  STUDY AREA  3. 3.1  STUDY AREA  L o c a t i o n of Study P l o t s The  study area i s near Kamloops,  major s i t e s  established  B r i t i s h Columbia.  f o r the water balance study.  There were two  The f i r s t  l o c a t e d near the Knouff Lake Road at the 12 km marker,  i n the  subzone, had a predominantly southern exposure, and i n c l u d e d climate plots representing five d i f f e r e n t The IDF  second study s i t e was a  subzone, i n c l u d e d  IDF^ f i v e micro-  closure.  l o c a t e d o f f the Lac Le Jeune Road i n the  three m i c r o c l i m a t e p l o t s w i t h d i f f e r e n t  c l o s u r e s and had a n o r t h e r n exposure. (< 3° s l o p e ) .  degrees of canopy  was  canopy  Both s i t e s were r e l a t i v e l y  There were three other m i c r o c l i m a t e p l o t s  flat  established,  two o f f the Todd Mountain Road i n the H e f f l e y drainage ( R e c r e a t i o n area and H e f f l e y p l o t s ) , and one o f f the Knouff Lake Road (Knouff 14 km plot). facing. wide  These p l o t s had moderate  (<15°) and were p r i m a r i l y south  A l l m i c r o c l i m a t e p l o t s were 10 m x 10 m i n s i z e , with a 25 m  buffer  zone.  The i n v e n t o r y and permanent were l o c a t e d sites,  slopes  adjacent  sample  p l o t s used f o r growth  analysis  to the m i c r o c l i m a t e p l o t s at the Knouff Lake Road  and H e f f l e y d r a i n a g e , and near Lac Le Jeune.  Additional  invent-  ory p l o t s were l o c a t e d near McQueen Lake, Red Lake, Anderson Lake, P i n a n t a n Lake and Orchard Lake. 1280  m,  sented.  The e l e v a t i o n ranges from 1006 m t o  topography i s g e n t l y to moderate, There were twenty-two  f o u r permanent  sample  plots  c o n s i s t e d of ten c i r c u l a r a logged a r e a .  and a l l a s p e c t s are r e p r e -  inventory plots  (Figure 2).  subplots, f i v e  25 m x 25 m i n s i z e ,  Each permanent  sample  and  plot  i n a c o n t r o l area and f i v e i n  The c o n t r o l area s u b p l o t s were 0.01  ha i n s i z e and the  28  y  / "^Orchard Lake Road >. .  O r c h a r d Lake  'Knouff  Lake  \ Red Lake Road  i JTodd I Mountain | Road  McOuean Lake  \ Kamloops  'Lac D u b o i s ' Road  Lake  Heffley  fs-f/l  Paul  . HWY  1  _  —'  Lake  Lake Road  Paul  V  "V—v ,* C\"  Lake  ££\>p I n a n t a n  Lake  ' ' N..^  KAMLOOPS CITY LIMITS  Lac La Juene Road;  KEY • EXPERIMENT 1: Microclimate Plot Lac La Juene  /  f HWY  Anderson Lake R o a d C " ^  5  O EXPERIMENT 2: Inventory P l o t A PERMANENT SAMPLE PLOT  Stump Lake  F i g u r e 2:  Map of study a r e a . The number l o c a t e d next the d i f f e r e n t symbols i n d i c a t e s the number of a c t u a l p l o t s at that s i t e .  29  logged s u b p l o t s were 0.02  ha i n s i z e .  Subplots were l o c a t e d  linearly  30 m apart along a compass heading.  3.2  Climate In  mm,  the I D F  subzone,  a  with an average  170 cm,  of 376 mm,  a v e r a g i n g 144  ranging from 376 mm s n o w f a l l ranges  annual r a i n f a l l  cm.  from 140 cm  of  3°C and  to 287  (between  deficit, days  3.3  60 and  The 116  52 and  of 428 mm.  Annual  a v e r a g i n g 183 cm a y e a r .  IDF  a  has a f r o s t  d a y s ) , and  5°C f o r the I D F  a  f r e e p e r i o d averaging  f i v e months w i t h a s o i l moisture frost  f r e e p e r i o d averaging 75  106 d a y s ) , and four months with a s o i l moisture  ( M i t c h e l l and Greene  1981).  Geology and S o i l s The  soils  m o r a i n a l and  are o r t h i c  the bedrock  or e u t r i c b r u n i s o l s .  ranges  from a g r a v e l l y  generally  good.  A detailed  The  parent m a t e r i a l i s  geology i s p r i m a r i l y v o l c a n i c with some f i n e to  medium sedimentary m a t e r i a l  is  from 110 cm to  are 5°C and 4°C with a mean annual minima  w h i l e the I D F ^ i has an average  (between  deficit  cm,  to 429  i s h i g h e r f o r the I D F ^ i ,  2°C and a mean annual maxima of 6°C and  and I D F ^ i , r e s p e c t i v e l y . 90 days  annual r a i n f a l l with an average  Mean annual temperatures  from 315 mm  and annual s n o w f a l l ranges  The  to 465 mm  varies  ( M i t c h e l l and Greene 1981).  loamy sand to a g r a v e l l y  sandy  R o o t i n g depth i s approximately 80  loam and drainage cm.  d e s c r i p t i o n of the s o i l c h a r a c t e r i s t i c s  c l i m a t e p l o t s was  done.  however, have s i m i l i a r  The  S o i l texture  f o r the m i c r o -  i n v e n t o r y and permanent sample  soil characteristics.  The  plots,  o r g a n i c l a y e r on a l l  30 p l o t s i s very s h a l l o w w i t h a F and H l a y e r of a p p r o x i m a t e l y 1 cm. o v e r l y i n g L l a y e r of a p p r o x i m a t e l y 2 cm i s common.  The p a r t i c l e  An density q  and the b u l k d e n s i t y of the o r g a n i c l a y e r was found to be 1.88  Mg m  and 0.53  72%.  Mg m~ , r e s p e c t i v e l y ,  A d d i t i o n a l o r g a n i c matter scattered  which r e s u l t e d i n a p o r o s i t y of  i n the form of r e s i d u a l l o g g i n g s l a s h  ,  is  around the p l o t s to a depth of 30 cm.  The s o i l  texture  of the Lac Le Jeune s i t e was a g r a v e l l y sandy loam  w i t h an impermeable l a y e r at 1 m, w h i l e the s o i l t e x t u r e 12 km s i t e was a g r a v e l l y loamy s a n d .  The coarse fragment  content was determined f o r the 0 - 50 cm and 50 50 cm x 50 cm x 100 cm deep s o i l p i t s , t h r e e at the Knouff 12 km s i t e ,  of the Knouff (> 10 mm)  100 cm depths from  two at the Lac Le Jeune  site,  and one each a t the H e f f l e y , K n o u f f 14  km and R e c r e a t i o n area p l o t s .  V a l u e s ranged from 0% to 25% by volume  f o r the e n t i r e  1).  s o i l p i t (Table  was determined to be 2.64  Mg m  .  The d e n s i t y of the c o a r s e The b u l k d e n s i t y of the  fragment  fines  (< 10 mm), as determined by the e x c a v a t i o n method ( B l a k e 1965), was 1.49  Mg m~  and 2.25  3  and 2.19  Mg m~  3  at  25 - 50 cm d e p t h s ,  Mg m ~ at the Lac Le Jeune s i t e , 3  the Knouff 12 km s i t e , respectively  (Table 1 ) .  and 1.39  Mg m  - 3  f o r the 0 - 25 cm and The R e c r e a t i o n area and  Knouff 14 km p l o t s were assumed to have a p p r o x i m a t e l y the same v a l u e s . The b u l k d e n s i t y of H e f f l e y p l o t was c a l c u l a t e d s e p a r a t e l y p l o t c o n t a i n e d no coarse f r a g m e n t s .  Mg m  - 3  (Table  this  For the H e f f l e y p l o t the f i n e b u l k  d e n s i t y at the 0 - 25 cm depth was 1.46 d e p t h , 2.12  because  Mg m  - 3  and at the 25 -  50 cm  1).  S o i l water r e t e n t i o n curves were o b t a i n e d f o r the Lac Le J e u n e , Knouff 12 km and H e f f l e y s i t e s  (Figs.  samples  cm l e n g t h )  (7.6  cm diameter x 7.6  3, 4 and 5) from u n d i s t u r b e d taken at the s u r f a c e  soil  and at  Table 1:  Site  f of Plots  Canopy Average (X)  S o l i c h a r a c t e r i s t i c s of the microclimate p l o t s .  Bulk d e n s i t y of f i n e s (pg m" ) Soil Texture  0-25  cm  25-50 cm  Coarse fragments (0% volume) 0-50  cm  50-100 cm  Average a v a i l a b l e s o i l water content (mm) at s o i l water m a t r i c p o t e n t i a l s -0.01  MPa  -0.1  MPa  -1.5  MPa  0 50 100  Sandy loams  1.49  2.19  11.6  15.3  240  168  96  5  0 10 25 50 100  Loamy sands  1.39  2.25  12.0  13.9  136  104  72  Knouff 14 km  1  10  Loamy sands  *  *  20.4  30.6  Recreation Area  1  35  Loamy sands  *  *  20.2  23.6  Heffley Creek  1  20  Loamy sands  1.46  Lac Le Jeune  3  Knouff 12 km  1  2.12  0  0  not  264  obtained  208  "These p l o t s were assumed to have s i m i l a r values as the Knouff 12 km s i t e , because coarse fragment content and s o i l were s i m i l a r . The H e f f l e y plot s o i l c h a r a c t e r i s t i c s were analyzed s e p a r a t e l y due to lack of c o a r s e fragments.  120  texture  F i g u r e 3:  S o i l water r e t e n t i o n curves f o r the Lac Le Jeune  site.  -1.6  F i g u r e 4:  I  -1.4  I  I  I  I  I  -1.2 -1 -0.8 -0.6 -0.4 SOIL WATER POTENTIAL (MPa)  S o i l water r e t e n t i o n curves f o r the Knouff  12 km  I  -0.2  site.  Figure 5:  S o i l water retention curves f o r the Heffley s i t e .  depths of 10 cm, 25 cm, and 60 cm. [the  The a v a i l a b l e water storage c a p a c i t y  water h e l d between s o i l water m a t r i c p o t e n t i a l s of -0.01 MPa  (field  c a p a c i t y ) and -1.5 MPa ( w i l t i n g p o i n t ) ] was much h i g h e r f o r the H e f f l e y and  Lac Le Jeune s i t e s  than f o r the Knouff  s o i l water m a t r i c p o t e n t i a l s  s  of 33%, 26%, and 15% s o i l water  volume, w h i l e the Lac Le Jeune s i t e  respectively,  averages  f o r the e n t i r e root zone.  matric potentials,  the Knouff  (Table 1 ) . At  (\|,) of -0.01 MPa, -0.1 MPa and -1.5 MPa,  the H e f f l e y p l o t has an average by  12 km s i t e  12 km s i t e  content  30%, 21% and 12%,  For these same s o i l water averages  only 17%, 13% and 9%,  respectively.  3.4  Vegetation Coniferous tree species include i n t e r i o r  pine,  lodgepole pine  IDFbi,  spruce  (Pinus c o n t o r t a Dougl.), and on s i t e s  (Picea spp.).  p o o r l y developed  shrub  The herb  (Spirea b e t u l i f o l i a ) ,  dominating,  with  pinegrass  and a major twinflower  W i l d strawberry  (Linnaea  ( F r a g a r i a v e s c a ) , oregon grape  (Rosa w o o d s i i ) are f r e q u e n t l y found on  sites. The  100%,  of a  a l b u s ) , and s e r v i c e b e r r y ( A l m e l a n c h i e r  (Mahonia n e r v o s a ) , and w i l d rose some  i n the  vegetation consists  l a y e r i s w e l l developed  ( C a l a m a g r o s t i s rebescens) b o r e a l i s ) component.  Understory  l a y e r dominated by s p i r e a  snowberry (Symphoricarpos alniflolia).  D o u g l a s - f i r , ponderosa  Knouff  12 km s i t e has f i v e m i c r o c l i m a t e p l o t s of a v e r a g i n g  50%, 25% 10% and 0% (±10%) canopy coverage,  s i t e has three m i c r o c l i m a t e p l o t s a v e r a g i n g coverages. coverages  w h i l e the Lac Le Jeune  100%, 50% and 0% canopy  The a d d i t i o n a l three m i c r o c l i m a t e p l o t s have canopy averaging  10%, 20% and 35%.  Canopy coverages  were  determined  initially  with a s p h e r i c a l densiometer  V i r g i n i a ) and  later verified  fish-eye  (Kelliher  as  the  lens  1985)  by a n a l y z i n g  i s occupied  metre height  was  by  selected  have a s i g n i f i c a n t  impact  snow t h r o u g h f a l l .  The  t r e e s per h e c t a r e  trees  photographs taken with a  solid  angle at two  only  the m i c r o c l i m a t e ,  d e n s i t y of the  was  done on  particularly  inventory  to 2,784 t r e e s per h e c t a r e .  the Lac  Le Jeune and  Knouff  the Lac  than the Knouff 12 km  The  moisture d e f i c i t .  A fertilizer  by Weetman and  response to f e r t i l i z a t i o n , a n a l y s i s was  3.5  96  densities 6.  12 km  sites  not  screening  Fournier  sample  replicated  twice.  is richer in available  (Appendix 3).  growth, due  from a  I t i s u n l i k e l y that  to the  trial  extreme  done on  (1981) showed no  soil  interior  significant  however, a p r e - f e r t i l i z a t i o n  growth  nutrient  done.  Logging H i s t o r y The  first  major l o g g i n g  with the advent of World War decided  that  i n the Kamloops area II.  In the  only mature trees could  diameter s i z e , the  stand  shown i n F i g u r e  Le Jeune s i t e  site  f e r t i l i z a t i o n would improve stand  Douglas-fir  regarding  a n a l y s i s of the n u t r i e n t content of the c o n i f e r needles  r e s u l t s i n d i c a t e that  nutrients  two  p l o t s v a r i e d from  composite of the p l o t s l o c a t e d at each s i t e , and The  The  the  those t r e e s l a r g e enough to  c o r r e s p o n d i n g to the above canopy coverages are A foliar  metres above  ( b o l e s , branches, f o l i a g e ) .  to i n c l u d e on  densiometer, A r l i n g t o n ,  (Appendix 2). Canopy coverage i s d e f i n e d  f r a c t i o n of the h e m i s p h e r i c a l  ground that  (Forest  initiated  l a r g e r t r e e s were the  be  diameter l i m i t older  tees was  occurred  1960's the B.C. felled  and,  logging. not  Forest  basing  The  i n the  1940's  Service  maturity  assumption  always c o r r e c t .  on  that  These  37  F i g u r e 6:  Relationship  between canopy coverage and stand  density.  38  trees  could  possess b e t t e r  genotypes, i n h a b i t the more favourable  s i t e s , and/or be more open grown.  In combination with t h i s and  s t r u c t u r e c o n s i s t i n g of l a r g e areas of even-size and  missing  either  diameter c l a s s e s , diameter l i m i t  micro-  a  stand  diameter d i s t r i b u t i o n s  logging  often resulted i n  dense pockets of r e s i d u a l stems of v a r i a b l e q u a l i t y or  small  clearcuts. By was  the  evident  personal a  e a r l y 1970's these stands were i n very that a b e t t e r  type of l o g g i n g was  communication).  The  "mark to c u t " i n the mid  each t r e e to be  felled.  The  The  ter  be harvested  stems were l e f t  s i t e s , however, had stems are of low improved. be  felled  at the  and  next stand  1983,  implemented  the  put  on a d d i t i o n a l volume  entry.  Furthermore, the  stands i n such poor c o n d i t i o n that Over time the cost  as  mark  a seed source f o r the next crop.  However, because the on a l l the  first  r e s i d u a l t r e e s would then provide  to provide  vigour.  (Clark  f o r e s t e r would s e l e c t and  necessary shade f o r n a t u r a l r e g e n e r a t i o n which could  necessary  s e l e c t i o n method was  1970's.  poor shape and i t  stand  Some  even the  q u a l i t y should  bet-  "better"  have  of marking each i n d i v i d u a l tree  c u t t i n g permits was  to  prohibitive, faller's selection  evolved. Faller's  s e l e c t i o n began i n the  marking each tree to be  felled,  Each f a l l e r i s i n s t r u c t e d as to be  left  foreman.  on  the  stand  and  to the  left,  cannot be  felled  and  T h i s would be  of f o r e s t e r s  trees  type of t r e e to f a l l  t r e e s below the u t i l i z a t i o n  Service  Instead  f a l l e r s e l e c t s the  Again, the b e t t e r t r e e s are  except that  1970's.  works under c l o s e s u p e r v i s i o n  wide range of diameter c l a s s e s .  Forest  the  late  stems are  and  fall.  the  spacing  of a woods taken from a  a true s e l e c t i o n system  s p e c i f i c a t i o n s of the  economically  to  as part  B.C.  of a commercial  39  logging operation.  Falling  these  s m a l l e r stems would be c l a s s i f i e d  "damage to immature stems" and  result  stand  from being o b t a i n e d , as l a r g e areas  s t r u c t u r e s and  be overstocked logging.  densities  in fines.  T h i s prevents  optimal  with s m a l l stems that cannot be thinned at the time  When funds  are a v a i l a b l e , however, these  i n a separate stand e n t r y f o r j u v e n i l e  spacing.  t r e e s can be  as  may of  thinned  EXPERIMENTAL METHODS  41  4. 4-1  EXPERIMENTAL METHODS  F o r e s t Water Balance  4.1.1  F i e l d Measurements The  main weather s t a t i o n was  l o c a t e d at the Knouff  With the e x c e p t i o n of a r e l a t i v e humidity  (RH)  12 km  sensor and  some of the  t h e r m i s t o r s , a l l the weather s t a t i o n i n s t r u m e n t s , which were to  a Campbell  Scientific  canopy coverage) irradiance  plot.  CR21 On  t h i s p l o t , h o u r l y measurements of  ( S ) , net r a d i a t i o n , and  soil  t  heat  in series.  Rainfall  from, r e s p e c t -  a Met-One anemometer, r e s p e c t i v e l y .  l o c a t e d with minimal humidity was polystyrene  o b s t r u c t i o n by any  i n t e g r a t e d every two sensor  located  hours  from a Phys-Chem  at the 50% canopy coverage  S o i l and  a i r temperatures  plots  50%,  100%  25%,  c a p a c i t y of the CR21 p o s i t i o n ) connected temperature  and  In  addition  (U) bucket  instruments were Relative  sulphonated  p l o t and  recorded  were obtained on a l l f i v e  canopy coverages)  to two  channels.  by expanding  T h i s c o n f i g u r a t i o n enabled  to be monitored.  the  Data were read from transferred  soil  C a s s e t t e s had  the c a s s e t t e by a Campbell  to the Amdahl V/8  to be  C2000  computer at U . B . C .  to the data recorded with the data l o g g e r , each  m i c r o c l i m a t e p l o t at the Knouff  12 km  26  A l l data were recorded  with a c a s s e t t e r e c o r d e r powered by a 6 V Gel c e l l .  microcomputer and  soil  data logger with a s t e p p i n g s w i t c h ( C l a r e r e l a y ,  at 40 p o s i t i o n s  changed weekly.  The  tipping  t r e e s on the h o r i z o n .  on the data l o g g e r . (0%, 10%,  three  (P) and windspeed  were measured by c o u n t i n g the pulses from a S i e r r a Misco r a i n gauge and  solar  f l u x d e n s i t y were  i v e l y , a Kipp s o l a r i m e t e r , Swissteco S - l net radiometer, and f l u x p l a t e s connected  connected  data l o g g e r , were l o c a t e d at the grass ( 0 %  o b t a i n e d by e l e c t r o n i c a l l y i n t e g r a t i n g the v o l t a g e output  heat  site.  s i t e had a hygrothermograph to  42  r e c o r d a i r temperature  and r e l a t i v e humidity, and storage r a i n gauges  to measure below-canopy r a i n f a l l . thermograph  The Lac Le Jeune s i t e had a hygro-  l o c a t e d on the grass p l o t  the three p l o t s  (0%, 50%,  and s t o r a g e r a i n gauges on each of  100% canopy c o v e r a g e ) .  S o i l s u r f a c e temperatures were taken throughout  the daytime, w i t h  an i n f r a r e d  thermometer, every two weeks on a l l e l e v e n m i c r o c l i m a t e  plots.  net r a d i a t i o n and s o i l heat f l u x d e n s i t y measurements were  The  taken f o r four weeks i n August.  A l l other growing  were taken from May  Winter measurements of snow depth  water  to October.  and  e q u i v a l a n t depths were taken every two weeks w i t h a snow auger.  Four snow samples S o i l water  were taken and  content was  the r e s u l t s averaged  503).  f o r each  plot.  measured on a l l e l e v e n p l o t s a p p r o x i m a t e l y  every two weeks w i t h a neutron probe  (Campbell P a c i f i c Nuclear Model  The measurement depths were at 15 cm i n t e r v a l s from the s u r f a c e  to the 75 cm depth. three aluminium  Except f o r the p l o t s at the Knouff 12 km  access tubes  t h i c k n e s s ) were i n s t a l l e d one  season measurements  metre a p a r t .  (50 mm  outer diameter and 12 mm  i n a triangular  12 km  wall  c o n f i g u r a t i o n approximately  The grass and completely f o r e s t e d  age) p l o t s at the Knouff  site,  (100% canopy c o v e r -  s i t e have f o u r access tubes arranged i n a  square, w h i l e the other t h r e e p a r t i a l l y  f o r e s t e d p l o t s have f i v e  tubes arranged as two a d j a c e n t t r i a n g l e s .  A l l tubes are one  access  metre  apart. There were two neutron probes used over the 1984 Probe A (B.C. M i n i s t r y of Environment) calibrated  season.  used u n t i l J u l y 5 and  once, w h i l e probe B ( A g r i c u l t u r e Canada, Kamloops) was  f o r the remainder samples  was  growing  of the summer and c a l i b r a t e d  used  twice by g r a v i m e t r i c  soil  taken one metre away from a c a l i b r a t i o n a c c e s s tube ( F i g u r e 7).  43  Figure  7:  C a l i b r a t i o n of the neutron p r o b e s . Probe A i s from B . C . M i n i s t r y of Environment w h i l e Probe B i s from A g r i c u l t u r e Canada.  the  44  The  0 - 5 cm and 5 - 10 cm s o i l  depths were sampled g r a v i m e t r i c a l l y  each  time the neutron probe was used. The hygrothermographs were c a l i b r a t e d R e f o r e s t a t i o n Centre l a b .  The sulphonated p o l y s t y r e n e sensor and h a i r  hygrometers  were c a l i b r a t e d  both Knouff  12 km and Lac Le Jeune s i t e s .  calibrated  4.1.2  p e r i o d i c a l l y w i t h an Assmann psychrometer at  at the U.B.C. Biometeorology l a b .  Net R a d i a t i o n  Net  radiation  f o r the daytime  R  where S  t  i s the s o l a r  n  was c a l c u l a t e d  = aS  irradiance,  t  as  + L*  (37)  L* i s the net longwave  irradi-  a i s the s o l a r a b s o r p t i o n c o e f f i c i e n t and assumed to be  0.88 f o r a f o r e s t The  A l l o t h e r i n s t r u m e n t s were  A n a l y t i c a l Methods  4.1.2.1  ance,  p r i o r to use at the B a l c o  cover ( G i l e s et_ a l . 1985; J a r v i s et_ a l .  net longwave i r r a d i a n c e  L* =  where e  v  was c a l c u l a t e d  e (e v  i s the e m i s s i v i t y  1976).  as  - l ) o T ' ( 0 . 1 + 0.9 n/N) a  of the v e g e t a t i o n [assumed to be 0.96  ( G i l e s et a l . 1985) i n t h i s s t u d y ] , a i s the Stefan-Boltzmann T  a  i s the mean daytime  hours  a i r temperature  The l a t t e r  constant,  i n K e l v i n s , n i s the number of  of sunshine, N i s the d a y l e n g t h , and e  atmosphere.  (38)  +  a  a  i s the e m i s s i v i t y  of the  i s g i v e n to a good approximation by a l i n e a r i z e d  45  v e r s i o n of the Idso-Jackson  e  where T  a  The The  a  (1969) equation given by Campbell  = 0.72 + 0. 005T  (39)  a  i s i n °C. net r a d i a t i o n was assumed to be the same f o r a l l p l o t s .  measurements r e q u i r e d to c a l c u l a t e RJJ were o b t a i n e d over a  g r a s s cover, except a partially  f o r the a i r temperature  forested plot.  which was o b t a i n e d  Due to the s e n s i t i v i t y  a b s o r p t i o n c o e f f i c i e n t , which would be l e s s a forest and  (1977)  cover,  of R  plots.  daily  and h i g h e r s u r f a c e temperature  courses  of S  t  indicated  o b s t r u c t e d f o r the f i r s t underestimate multiplied  4.1.2.2  the edges of the  absorption  of the p l o t s .  A l s o , the  that the Weathermeasure a c t i n o g r a p h was  and l a s t  of approximately  to the 0%, 10%  Longwave r a d i a t i o n from  grass p l o t s would tend to compensate f o r the lower coefficient  to the  f o r a grass cover than f o r  there may be an over estimate of ^  25% canopy coverage  N  from  two hours of each day r e s u l t i n g  20%.  The d a i l y S  by 1.25 to compensate f o r t h i s  t  i n an  measurements were  underestimate.  E s t i m a t i o n of E v a p o t r a n s p i r a t i o n U s i n g Water  Balance  Analysis. There was no n o t i c e a b l e r u n o f f observed  on the s i t e s ,  drainage was assumed to be n e g l i g i b l e s i n c e the s o i l water remained below that c o r r e s p o n d i n g  t o a s o i l water m a t r i c  of -0.1 MPa f o r the m a j o r i t y of the growing season. i n most s o i l s ,  drainage  becomes n e g l i g i b l e  and s o i l content  potential  At t h i s  potential  because of a marked  46  decrease i n the u n s a t u r a t e d h y d r a u l i c Under these c o n d i t i o n s  conductivity  (Baver e_t_ al^. 1972).  (1) reduces to  E = P - AW/ At  (40)  where AW/At was c a l c u l a t e d over seven or f o u r t e e n K final w  " initial)/( final w  " initial)(  t  t  m m  day i n t e r v a l s u s i n g  day )]. - 1  The f o r e s t  r o o t zone water balance which excludes i n t e r c e p t i o n l o s s from the tree canopy can be w r i t t e n as  T + Ig + E  where P  n >  n  - AW/At  (41)  the net p r e c i p i t a t i o n , i s the sum of the t h r o u g h f a l l and  stemflow (the l a t t e r was observed Net  = P  s  to be very  small and was  neglected).  p r e c i p i t a t i o n was measured at one or two week i n t e r v a l s on a l l  p l o t s , except f o r H e f f l e y , Knouff those cases,  P  was estimated  n  14 km and R e c r e a t i o n  n  = cP  t h i s p r o p o r t i o n a l i t y should  p r e c i p i t a t i o n rates free throughfall  (Rutter  In  from  P  Theoretically,  Area p l o t s .  (42)  only hold  f o r low  et al_. 1971), where c i s i d e n t i f i e d as the  coefficient.  Assuming that Ig + E  s  i s much l e s s than T, equation (41)  becomes T « P  n  - ZW/ At  (43)  47  T h i s would  o n l y be true at h i g h e r canopy  component i s s m a l l . The of  growing  Otherwise Tg would  0.11  _ 1  2,450 J k g  - 1  the  and 0.660 k P a ° C .  There was  grass p l o t  heat  flux  In t h i s approach,  _ 1  was  irradiance  vapour  was  calculated  y are,  respectively,  reasonable agreement between R calculated  n  used when c a l c u l a t i n g a v a i l a b l e  using  the canopy  energy  J m  site  ( J a r v i s ejt a_l. 1976), and D was  at 15°C, r  t a k e n at the 50% canopy a  the s a t u r a t i o n  follows  (Tetens  e * a  (37).  (R  The  soil  This n  - G) u s i n g  a  was  l i n k e d with changes i n  resistance  u s i n g e q u a t i o n (25) where pep was  1200  e *,  measured on  n  temperature.  pressure d e f i c i t s ,  C°  the  the c o e f f i c i e n t a was  To see i f the v a r i a t i o n i n T i s more c l o s e l y the  sum  model f o r  measured to be 3% of the net r a d i a t i o n .  and  the  at an a i r temperature of 15°C, and L i s  at Knouff 12 km and R  (G) was  relationship solar  used.  was  To t e s t  the P r i e s t l e y - T a y l o r  u s i n g e q u a t i o n (24) where s and  kPa°C  negligible.  1 to October 6.  of the E to net r a d i a t i o n ,  e v a p o t r a n s p i r a t i o n was calculated  not be  season e v a p o t r a n s p i r a t i o n or t r a n s p i r a t i o n  the d a i l y E or T values from June  sensitivity  coverages where the grass  of the dry leaves  assumed to be  assumed to be 5 s m  for a  forested  determined from measurements of  RH,  coverage p l o t , u s i n g D = (1 - RH)e *, where  vapour  a  p r e s s u r e of the a i r , was  calculated  as .  1930)  = (0.6108)10  [7.5 T / ( T a  a  + 237.3)1  (44)  48 4-2  Volume Growth  4.2.1 F i e l d Measurements 4.2.1.1.  Inventory Plots  A l l inventory plots were marked and each tree over 7.5 cm d (diameter at breast height) (coreable size) had d and species recorded, and was numbered with spray paint. recorded and were numbered.  Additionally a l l stumps had diameters  The location of the trees, stumps, and  regeneration (< 7.5 cm d) were mapped.  The age of the regeneration was  determined by counting the branch whorls and some destructive sampling to count the rings. A.  Data collection for core analysis  One of the sets of four adjacent plots (see Fig. 2) was completely inventoried, including a l l tree heights, d, and an increment core taken from each tree with a d > 7.5 cm. From this set of four plots which contained 313 trees (n), the last five years of growth was analyzed to determine the number (N) of trees to be cored on each of the remaining plots using  N =  tn-1'  (45)  where t -\ is the appropriate t-statistic for the 95% confidence level n  and n-1 degrees of freedom (1.96), S is the standard deviation of the x  last five years radial growth, and E is the sampling error (5% of the mean).  The value of N was found to be 698 (S = 0.0593 cm y r x  x = 0.0898 cm y r ) . - 1  - 1  ;  There were 961 numbered trees from a l l the plots;  49  therefore, the  about 70% of the t r e e s on each p l o t were cored.  t r e e s , bark width was  height  and these values  B.  required  were averaged.  (45) was  (cm  ra )  only  _ 1  used i n s t e a d of growth.  communication;  ).  Since  (S  x  (or about  Kozak 1985,  determined  = 0.0984 cm y r  personal  _ 1  ;  be  10% of the t r e e s f o r each  f o r stem a n a l y s i s ( M i t c h e l l 1985,  100 t r e e s s e l e c t e d  taken:  I t was  t h i s number c o u l d not r e a l i s t i c a l l y  100 of the 961 t r e e s  p l o t ) were f e l l e d  The  was  -1  d e v i a t i o n of the d t o  t r e e s were n e c e s s a r y f o r stem a n a l y s i s  x = 0.2591 cm y r obtained,  a l s o used to determine the number of t r e e s  f o r stem a n a l y s i s , except the standard  ratio  t h a t 231  discs  measured i n s i x d i f f e r e n t l o c a t i o n s at b r e a s t  Data c o l l e c t i o n f o r stem a n a l y s i s  Equation  height  For each of  personal  communication).  f o r stem a n a l y s i s had a minimum of f o u r  one at the base of the t r e e , one a t 1.3 m,  one at the base  of the crown, and the l a s t midway through the crown, as suggested by Mitchell  (1984, p e r s o n a l  determined by t a k i n g height  communications).  The number of d i s c s were  tea d i s c s at i n t e r v a l s of one-tenth t o t a l  on f o u r t r e e s and p l o t t i n g the t r e e form.  four d i s c s could  adequately d e s c r i b e  t r e e s , number of t r e e s cored,  The  the  t o t a l number of f o r stem  p l o t s are i n T a b l e 2.  Permanent Sample P l o t s  Permanent sample L t d . i n 1980 Forests,  the t r e e form.  found that  and the number o f t r e e s sampled  a n a l y s i s i n each of the 22 i n v e n t o r y  4.2.1.2  I t was  tree  and 1982,  plots, originally were remeasured  e s t a b l i s h e d by Balco according  I n v e n t o r y Branch s p e c i f i c a t i o n s .  This  Industries  to the B.C. M i n i s t r y of included  recording d  Table 2.  Summary of trees sampled on the i n v e n t o r y p l o t s  (on per p l o t  Location  Total number of t r e e s >5 cm dbh  Total number of regen. <5 cm dbh  total number of stumps  Anderson Lake H e f f l e y Creek H e f f l e y Creek H e f f l e y Creek H e f f l e y Creek  A B C D  54 65 68 29 29  93 767 508 317 941  20 12 10 4 4  6 7 7 3 3  39 47 49 21 21  16 65 68 29 29  6 7 8 9 10  Heffley Heffley Heffley Heffley Knouff  E F G H A  41 43 61 19 6  369 202 217 217 33  6 7 10 2 17  4 4 4 2 1  30 31 27 14 4  21 23 24 14 4  11 12 13 14 15  Knouff 14 Knouff 14 Knouff 14 McQueen Orchard Lake  B C D  13 13 61 174 18  41 37 62 0 91  12 21 6 5 13  1 1 6 18 2  10 10 45 126 13  6 8 26 28 12  16 17 18 19 20  Orchard Lake Orchard Lake Orchard Lake Orchard Lake Pinantan  B C D E  102 15 30 24 20  57 33 49 114 3  8 12 12 9 17  11 2 3 3 2  74 11 22 18 15  21 12 13 13 12  21  Red Lake  20  576  3  2  15  12  22  Knouff 19  80  221  17  8  45  18  961  4,899  227  100  700  Plot No. 1 2 3 4 5  TOTALS  Creek Creek Creek Creek 14  A  Number of t r e e s f o r stem analysis  [1/16 ha] b a s i s ) .  Number of trees f o r increment cores  Number of heights  494  51 and  species  previously  4.2.2  for a l l marked trees, and remeasuring the heights of the recorded trees, and age and height  of selected  regeneration.  A n a l y t i c a l Methods A stand table was developed for each of the 22 inventory  5 cm d classes, including regeneration.  plots by  The c o e f f i c i e n t s a, q, and k  were determined for the diameter d i s t r i b u t i o n currently on each plot [eq. (30) and (31)]. and  Analysis of the height  to age, height  to diameter,  diameter to age relationships were done for each density c l a s s .  density classes were selected from height  The  and diameter relationships to  be 10 - 300, 301 - 600, 601 - 900, 901 - 1200, 1201 - 1500, 1501 - 1800, 1801 - 2100, 2101 - 2400, 2401 - 2700, and 2701 - 3000 trees per hectare.  4.2.2.1 The  Development of a Local Volume Equation volume (V) of the stem analysis sample trees was determined by  using Sraalian's equation (Husch et_ a l . 1972)  n V = J ^ (  d  l i  2  +  d  2i )Li/8 2  (46)  where d]^ and d£i are the top and bottom diameters of log section i with a length, L^.  Although Smalain's equation has been shown to  overestimate tree volume by approximately nine percent, other methods (Huber's and Newton's equations) require the additional measurement of the cross-sectional area at the middle of each log section (Young et a l .  52  1967).  Since s u c c e s s i v e volumes are s u b t r a c t e d from each other to  determine  growth r a t e s , e r r o r i n the l a t t e r w i l l  be s m a l l .  volume equation u s i n g m u l t i p l e r e g r e s s i o n was developed  A local  from the  measured volume of the 100 sample t r e e s (Schumacher and H a l l 1933)  log V = l o g a + b l o g d + c l o g H  where a, b and c are e x p e r i m e n t a l l y determined h e i g h t , and d i s taken at b r e a s t h e i g h t . is  implictly  relationship  expressed  ratio varied ratio  studied.  density class  variable  T h i s was not the case  I n these stands, the diameter  constant  (see RESULTS).  f o r the v a r i a t i o n i n the form last  In a l o c a l volume e q u a t i o n H  c o n s i d e r a b l y with stand d e n s i t y .  remained f a i r l y  coefficients, H i s  as a f u n c t i o n of d and a constant p r o p o r t i o n a l  i s assumed between H and d.  uneven-age stands  (47)  for different Therefore, this  to h e i g h t  I t was found sized  i n the  that  this  stems i n the same  r a t i o was used  to account  f a c t o r due to d e n s i t y and r e p l a c e d the  i n (47), so that i t was r e w r i t t e n as  l o g V = a + b l o g d + c l o g d/H  T h i s equation was t e s t e d to determine  i t s accuracy  t r e e volume 5, 10 and 20 years ago from increment height.  (48)  i n estimating  cores taken at b r e a s t  The volumes were c a l c u l a t e d assuming the same d/H r a t i o as  c u r r e n t l y on the stands and were compared to a c t u a l volumes from  stem a n a l y s i s and Smalian's  10 and 20 years ago, at d i f f e r e n t  equation.  The diameters  determined  of the t r e e 5,  i n t e r v a l s along the stem were obtained  53 from the d i s c s removed.  The t r e e h e i g h t at each time was determined by  using  ht "  where h  h  c "  i s the h e i g h t 5,  t  h e i g h t of the t r e e ,  g  c  (8c ~ g > / ( c " L  t  h  10 or 20 years  h  L  (49)  )  ago ( t ) ,  h  c  i s the  i s the c u r r e n t age of the t r e e ,  g^ i s  current the  age of the t r e e when i t was the h e i g h t of the p o s i t i o n where the d i s c n e a r e s t the t r e e top was removed  4.2.2.2  (h^).  Stand Growth  The increment  cores were measured on the Addo-X t r e e r i n g a n a l y z e r  i n f i v e year i n t e r v a l s s i n c e  the time of the l a s t  logging.  The one  core  t a k e n from each was c o r r e c t e d t o e q u a l the r a d i u s of the t r e e ( M i t c h e l l 1984,  personal communication).  i n t e r v a l as the d i f f e r e n c e at  Growth was c a l c u l a t e d f o r each f i v e year  between the volume per h e c t a r e on the  the b e g i n n i n g and end of each i n t e r v a l .  equations  required d outside bark,  S i n c e the l o c a l volume  the bark w i d t h was determined as a  p r o p o r t i o n of the o u t e r bark d i a m e t e r , and the cores c o r r e c t e d i n c l u d e bark w i d t h . period,  stand  The growth r a t e of each p l o t f o r each f i v e  to year  r e f l e c t i n g the e f f e c t s of a g i v e n stand volume, and s t a n d  d e n s i t y was used as one growth datum p o i n t . The i n i t i a l s t a n d c o n d i t i o n s p r i o r to l o g g i n g and i m m e d i a t e l y f o l l o w i n g l o g g i n g were a l s o a n a l y z e d .  The a , q , and k  coefficients  and volume f o r each p l o t at the time of l o g g i n g was e s t i m a t e d from the stump diameters  c o n v e r t e d to d (DemaTchalk 1984), and the d i a m e t e r s  of  54  the r e s i d u a l t r e e s at the time of the l a s t same v a r i a b l e s were determined  l o g g i n g were determined.  f o r the stand immediately  The  following  logging. The permanent  sample p l o t growth was determined as the d i f f e r e n c e  i n the volume per h e c t a r e c u r r e n t l y on the stand and at the time of p l o t establishment.  The f i v e s u b p l o t s both i n the c o n t r o l l e d and the logged  s i t e s were combined and analyzed as one 0.05 logged p l o t  f o r each permanent  sample  plot.  ha c o n t r o l and one 0.10 ha  RESULTS AND DISCUSSION  RESULTS AND DISCUSSION 5.1  Water Balance Analysis  5.1.1  I n i t i a l S o i l Water Content at the Beginning of the Growing Season  A major s o i l water The  factor  influencing  the i n i t i a l  content was the s o i l recharge due t o the s p r i n g  snow melted o f f the south f a c i n g  Heffley canopy  growing season root  sites f i r s t  lower e l e v a t i o n  ( F i g s . 8 and 9 ) .  coverage p l o t s by A p r i l  1.  zone  snowmelt.  Knouff 12 km and  The snow was o f f the 0% and 100%  I t was o f f the p a r t i a l l y  forested  p l o t s by A p r i l 15, w i t h the e x c e p t i o n of the Knouff 12 km 50% canopy coverage p l o t . to the l a r g e  The snow was o f f t h i s p l o t by A p r i l  amount of l o g g i n g s l a s h p r e s e n t .  wave r a d i a t i o n beneath below (Oke 1978). and Knouff  the snow's s u r f a c e ,  The h i g h e r e l e v a t i o n  14 km p l o t s  f a c i n g Lac Le Jeune  retained  100% canopy  1, very l i k e l y due  The s l a s h absorbs  short-  which melts the snow from  south f a c i n g R e c r e a t i o n Area  t h e i r snow u n t i l A p r i l coverage p l o t l o s t  30.  The north  i t s snow by A p r i l 1,  p r o b a b l y due to a low i n i t i a l  snow cover, w h i l e the 50% and 0% canopy  coverage p l o t s  snow f o r an a d d i t i o n a l month ( F i g . 10).  retained  their  The maximum snow water e q u i v a l e n t on lower canopy coverage p l o t s  depth was c o n s i s t e n t l y higher  coverages, w i t h the h i g h e s t v a l u e s on both 0% canopy (140 mm at Lac Le Jeune  and 110 mm at Knouff 12 km).  The lowest v a l u e s were observed on both 100% canopy (50 mm on e a c h ) .  While the Lac Le Jeune  30 mm g r e a t e r snow water e q u i v a l e n t canopy 100%  plots  coverage p l o t s had  depth than the Knouff 12 km 0%  coverage p l o t , both of the 50% canopy  canopy  depths.  0% canopy  coverage  coverage p l o t s  coverage p l o t s had s i m i l a r maximum snow water  and both of  equivalents  57  JAN F i g u r e 8:  FEB  MAR  APR  Course of the snow water e q u i v a l e n t depths on the p l o t s the Knouff 12 km s i t e from January to June 1984.  at  58  F i g u r e 9:  Course of the snow water e q u i v a l e n t depths on the p l o t s the Lac Le Jeune s i t e from January to June 1984.  at  59  Figure 10:  Course of the snow water equivalent depths for the Heffley, Knouff 14 km and Recreation Area plots from January to June 1984.  The  initial  s o i l water  v a r i e d from 252 mm 3).  to 92 mm  s t o r a g e (W) f o r a r o o t i n g depth of 80 cm f o r the e l e v e n m i c r o c l i m a t e p l o t s  (Table  The three Lac Le Jeune p l o t s had a p p r o x i m a t e l y twice as much  i n i t i a l W as the Knouff 12 km p l o t s . age p l o t had the h i g h e s t i n i t i a l p l o t had the second h i g h e s t W of a l l the p l o t s .  W.  The Lac Le Jeune 0% canopy The Knouff 12 km 0% canopy  covercoverag  snow water e q u i v a l e n t but the lowest  initia  T h i s was p a r t l y due to the snow m e l t i n g e a r l i e r  than on the other p a r t i a l l y  forested plots.  T h i s appeared t o r e s u l t  from warm days and very c o l d n i g h t s , c a u s i n g the snow to melt but p r e v e n t i n g the ground  from thawing  These f i n d i n g s i n d i c a t e  to enable i n f i l t r a t i o n  that the i n i t i a l  o f the water.  W was the r e s u l t  of the i n t e r -  a c t i o n of the maximum snow water e q u i v a l e n t , d u r a t i o n of snow cover, soil to  temperatures at the time of snow melt and the a b i l i t y  r e t a i n water.  of the s o i l  An a d d i t i o n a l f a c t o r i s the r o o t zone s o i l  storage i n the p r e v i o u s autumn p r i o r  water  to s n o w f a l l ; however, these data  were not a v a i l a b l e i n t h i s study.  5.1.2  S o i l Water Content D i s t r i b u t i o n i n the Root Zone The v o l u m e t r i c s o i l water  0-7.5 cm s o i l  content ( 6 )  tends to be h i g h e s t f o r the  depth, and over the growing season the s o i l  from the top down.  F i g s . 11 and 12 show how 9 v a r i e s w i t h s o i l  throughout the r o o t zone f o r the 0%, 50% and 100% canopy at  the Knouff 12 km and L a c Le Jeune  July  13, and August  tends to dry  19, 1984.  sites,  coverage  plots  r e s p e c t i v e l y , on June 15,  The Lac Le Jeune  p l o t s had a  u n i f o r m d i s t r i b u t i o n of water on June 15, but by August were n o t i c e a b l y d r i e r a t the 10-40 cm depth.  depth  These  fairly  19 the p l o t s  plots  remained  Table 3.  P l o t Name  Lac Le Jeune  Heffley Knouff 14 km R e c r e a t i o n Area  Knouff 12 km  Canopy coverage (%)  Variables  Elevation (m)  i n f l u e n c i n g the i n i t i a l  Maximum snow water equivalence (mm)  Date a t which no snow remained on p l o t  0% 50% 100%  1069  140 70 50  May 3 May 3 April 1  20% 10% 35%  878 980 912  75 105 95  A p r i l 15 May 3 May 3  110 100 95 65 50  April April April April April  0% 10% 25% 50% 100%  878  s o i l water c o n t e n t .  1 15 15 1 1  S o i l temperature (°C) a t the 5 cm depth at the time of snowmelt  Initial s o i l root zone water content (9) (mm)  +0.5 +1.5 +0.5  252 215 220  0.5 0.5 0.5  234 169 146  -1.5 0 0.5 0.5 0.5  94 122 143 118 115  June  15,  1984  July  13, 1984  VOLUMETRIC WATER CONTENT Figure 11:  August  19, 1984  (%)  Distribution of the s o l i water content for three plots located at the Knouff 12 km s i t e on three different days.  June  15, 1984  July  13, 1984  August  19, 1984  15 -  VOLUMETRIC WATER Figure 12:  CONTENT  (%)  Distribution of the s o i l water content for three plots located at the Lac Le Jeune s i t e on three different days.  w e t t e r at the lower depths p a r t l y impermeable canopy all  because  of the presence of an  l a y e r a t the 1 m depth, which r e t a r d e d d r a i n a g e .  coverage  the p l o t s .  ( g r a s s ) p l o t at the Lac Le Jeune  August  19.  throughout  The Knouff 12 km 0% canopy the summer.  g e n e r a l l y remained the  partially  appeared  The 0% canopy  coverage p l o t s at both  sites  f o r e s t e d p l o t s were d r i e r at the lower depths.  This  to be due to the observed presence of grass r o o t s only i n the i n the grass p l o t s and t r e e r o o t s i n both the forested  t o t a l r e d u c t i o n i n the s o i l water  October 4, 1984, ranged give a preliminary  plots.  trees.  s t o r a g e from May 3 to  from 123 mm t o 40 mm  ( T a b l e 4 ) . These values  i n d i c a t i o n of the s o i l water which  F i g s . 13, 14, 15 and 16 i l l u s t r a t e  s t o r a g e and r a i n f a l l  events.  mm over the summer on a l l p l o t s . these f i g u r e s to  plot  Course of Root Zone S o i l Water Storage The  water  content p r o f i l e s by  coverage p l o t was the d r i e s t  upper and lower depths i n the p a r t i a l l y  the  between-plot  d r i e r i n the a p p r o x i m a t e l y top 40 cm o f s o i l , w h i l e  upper depths of the s o i l  5.1.3  s i t e was the w e t t e s t of  The Knouff 12 km p l o t s had the most  v a r i a t i o n on June 15, but had s i m i l a r s o i l water  The 0%  i s t r a n s p i r e d by  the course of the s o i l  P r e c i p i t a t i o n was approximately 90  The h o r i z o n t a l l i n e s on the graphs i n  i n d i c a t e the s o i l water  s t o r a g e i n the root zone  be 80 cm deep) a t s o i l water m a t r i c p o t e n t i a l s o f -0.01 MPa  (assumed (field  c a p a c i t y ) , -0.1 MPa and -1.5 MPa ( w i l t i n g p o i n t ) , and assume a uniform d i s t r i b u t i o n of the water water  content i n the s o i l p r o f i l e .  Since no s o i l  r e t e n t i o n data were o b t a i n e d f o r the R e c r e a t i o n Area or Knouff 14  km p l o t s i l l u s t r a t e d  i n F i g . 16, these two p l o t s are not d i s c u s s e d i n  T a b l e 4:  Changes i n the s o i l water s t o r a g e from May 3 t o October 5, 1984.  Plot Lac Le Jeune Grass P a r t i a l l y forested Forested  A8 (mm)  (0% canopy coverage) (50% canopy coverage) (100% canopy coverage)  123 87 92  Forested  (0% canopy coverage) (10% canopy coverage) (25% canopy coverage) (50% canopy coverage) (100% canopy coverage)  40 46 48 50 64  Heffley Knouff 14 km R e c r e a t i o n Area  (20% canopy coverage) (10% canopy coverage) (35% canopy coverage)  110 73 42  K n o u f f 12 km Grass P a r t i a l l y forested  66  O 10055  MAY  JUN  JUL  AUG  SEP  (1984) Figure 13:  The r a i n f a l l events and course of root zone s o i l water storage for the plots at the Knouff 12 km s i t e .  67  (1984) 14-  The r a i n f a l l events and course of root zone s o i storage for the plots at the Lac Le Jeune s i t e .  68  Figure 15:  The r a i n f a l l events and course of root zone s o i l water storage for the Heffley p l o t .  69  Figure 16:  The r a i n f a l l events and course of root zone s o i l water storage for the Recreation Area and Knouff 14 km plots.  terms of s o i l water m a t r i c p o t e n t i a l . soil  texture,  soils  their retention  However, on the b a s i s  properties  are probably s i m i l a r to the  at the Knouff 12 km s i t e . Only two p l o t s were a t f i e l d  first  measured.  capacity  time (about 1 week), w h i l e the Knouff 12 km 25%  canopy coverage p l o t remained at f i e l d latter  decline  i n e a r l y May, when 6 was  The Lac Le Jeune 0% canopy coverage p l o t remained at  t h i s l e v e l f o r a short  The  of t h e i r  capacity  until  p l o t , however, had s t a n d i n g water nearby.  the end of June. There was a  i n the s o i l water s t o r a g e o f a l l the p l o t s c o r r e s p o n d i n g to the  Increase i n s o l a r i r r a d i a n c e  i n spring  ( F i g . 17). T h i s  was a l s o the  time of bud break, which o c c u r r e d on June 15 on the south f a c i n g elevation the  p l o t s , and about one week l a t e r at the Lac Le Jeune s i t e .  the Knouff  l e s s than -0.1 MPa.  At t h i s time,  12 km 0%, 50% and 100% canopy coverage p l o t s had s o i l  water storages c o r r e s p o n d i n g to average m a t r i c p o t e n t i a l s of l e s s -1.5  By  middle of J u l y a l l p l o t s had s o i l water s t o r a g e s c o r r e s p o n d i n g to  average s o i l water m a t r i c p o t e n t i a l s only  lower  MPa (permanent w i l t i n g p o i n t ) .  A l l p l o t s had an i n c r e a s e  than  i n root  zone s o i l water storage i n mid-August, as a r e s u l t of an i n c r e a s e i n rainfall  and the d e c l i n e  was a l s o  the time of bud s e t .  5.1.4  Evapotranspiration  of s o l a r i r r a d i a n c e  at t h i s time of year.  This  and Transpiration Rates Over the Growing  Season Table 5 l i s t s  the c a l c u l a t e d  evapotranspiration  m i c r o c l i m a t e p l o t s f o r 1-4 week p e r i o d s d u r i n g  rates  f o r the 11  the 1984 growing season  (June 1 to October 4 ) . The h i g h e s t  evapotranspiration  all  As expected, the p l o t s which had t h e  p l o t s from June 23 t o J u l y  13.  rates  occurred on  Figure 17:  Course of the solar irradiance over the 1984 growing season. These values were calculated as an average for the daylight hours (daylight hours (N) are i n Table 8).  Table 5;  E v a p o t r a n s p i r a t i o n r a t e s over the growing season (mm day  l  )  K n o u f f 12 km P l o t s Canopy Coverage 10% 25% 50%  0% June June June June July July Aug.  1 8 16 23 14 25 20  --  -  June June June July July Aug. Oct.  7 15 22* 13 24 19* 4  0.81 1.08 1.22 2.12 0.85 0.84 1.09  0.83 1.26 0.61 2.33 0.43 0.91 1.27  0.35 1.38 0.56 2.19 0.31 0.94 1.58  0.88 1.26 0.55 2.50 0.42 0.65 1.64  100% 0.80 1.34 0.89 2.40 0.45 0.64 1.61  L a c Le Jeune P l o t s Canopy Coverage 0% 50% 100%  HATF  June June June July Aug.  1 23 28 14 19  DATE  June June June June July July Aug.  1 8 16 23 14 25 20  -  June June June July July Aug. Oct.  7 15 22* 13 24 19* 4  -  June June JulyAug. Oct.  22 27* 13* 18 4  1.90 2.57 1.39 1.61 1.43  1.44 2.20 1.21 0.98 2.38  Knouff 14 (10%)  Heffley (20%)  0.69 1.09 0.68 2.47 0.64 1.06 1.07  0.95 0.55 1.41 2.68 1.06 0.61 1.76  * P e r i o d s of no recorded r a i n f a l l .  1.86 1.97 0.99 0.78 2.85  R e c r e a t i o n Area (35%) 0.47 0.72 0.69 1.18 0.57 1.28 1.24  highest  initial  s o i l water  storages a l s o had  a t i o n r a t e s d u r i n g the growing season was  s m a l l because  <-0.01 MPa.  Drainage d u r i n g the  Consequently, as i n d i c a t e d e a r l i e r , n e g l e c t i n g drainage  rainfall  i n the c a l c u l a t e d  r e a c h i n g the ground  g i v e n canopy c l o s u r e was  (P ) n  values of E.  (mainly t h r o u g h f a l l ) f o r a  a constant p r o p o r t i o n  (c) of the above canopy  p r e c i p i t a t i o n as i n d i c a t e d by the s l o p e s of the l i n e s r e l a t i o n s h i p appeared events.  The  coverage. coverages  The  to be constant f o r both l a r g e and  constant c decreased from 0.98  increased  from 10% to 100% the c a l c u l a t e d  time i n t e r v a l d u r i n g the 1984 the f o r e s t e d  loss  no r a i n f a l l .  to a f o r e s t  to 0.63  ( F i g . 19).  t r a n s p i r a t i o n r a t e s f o r each p l o t  growing  season.  and  T r a n s p i r a t i o n rates f o r  In t h i s  case there was  cover, so that E = T.  no  canopy coverage  plots.  Table 7 l i s t s  the t o t a l  growing  canopy coverage p l o t s at the Knouff to 138 mm.  The  t o t a l E r a n g i n g from 168 mm  of no  than on the h i g h  season E and T f o r each p l o t . 12 km  The  s i t e had a t o t a l E ranging  three p l o t s at the Lac Le Jeune s i t e had a to 178 mm.  12 km and Lac Le Jeune s i t e s  canopy coverage or stand d e n s i t y . however, v a r i e d  interception  During time i n t e r v a l s  h i g h e r on the low canopy coverage p l o t s  Knouff  small r a i n f a l l  as canopy  r a i n f a l l , T was  from 129 mm  This  p l o t s were lower than E, except f o r time i n t e r v a l s d u r i n g  there was due  i n F i g . 18.  standard d e v i a t i o n of c i n c r e a s e d with i n c r e a s i n g canopy  Table 6 l i s t s  which  growing  s o i l water m a t r i c p o t e n t i a l s were g e n e r a l l y  would cause only a s m a l l e r r o r The  seasion.  the h i g h e s t e v a p o t r a n s p i r -  G e n e r a l l y the t o t a l E on the  exhibited The  l i t t l e v a r i a t i o n with  t o t a l T f o r the growing  c o n s i d e r a b l y w i t h canopy coverage.  completely f o r e s t e d p l o t s on both the Knouff  12 km  The  season,  t o t a l T on the  and Lac Le Jeune  74  Figure 18:  The relationship between the r a i n f a l l reaching the ground ( P ) and r a i n f a l l above the canopy (P) for d i f f e r e n t canopy coverages. n  75  Figure 19:  Changes i n P /P n  (c) with canopy coverage.  T a b l e 6:  T r a n s p i r a t i o n r a t e s over the growing s e a s o n (mm day  ).  K n o u f f Lake P l o t s  DATE June June June June July July Aug.  1 8 16 23 14 25 20  -  Canopy Coverage 10% 25% 50%  0%  June June June July July Aug. Oct.  7 15 22* 13 24 19* 4  0.81 1.08 1.22 2.12 0.85 0.84 1.09  0.69 1.16 0.61 2.31 0.41 0.91 1.24  0.45 1.34 0.56 2.14 0.27 0.94 1.37  100%  0.63 1.20 0.55 2.20 0.30 0.65 1.38  0.45 1.07 0.89 2.01 0.31 0.64 0.98  L a c Le Jeune P l o t s Canopy Coverage 0% 50% 100% June June June July Aug.  1 23 28 14 19  -• June - June -• J u l y - Aug. -• O c t .  DATE  June June June June July July Aug.  1 8 16 23 14 25 20  -  June June June July July Aug. Oct.  7 15 22* 13 24 19* 4  22 27* 13* 18 4  1.90 2.57 1.39 1.61 1.43  1.10 2.20 1.21 0.90 2.24  Knouff '.L4 (10%)  Heffley (20%)  0.68 1.07 0.67 2.42 0.63 1.06 1.05  0.93 0.54 1.36 2.63 1.04 0.59 1.73  * P e r i o d s of no r e c o r d e d r a i n f a l l .  1.08 1.97 0.99 0.68 1.97  R e c r e a t i o n Area (35%) 0.39 0.60 0.63 1.08 0.52 1.17 1.14  T a b l e 7:  Comparison of the t o t a l growing season e v a p o t r a n s p i r a t i o n and t r a n s p i r a t i o n r a t e s .  PLOT (Canopy Coverage)  12 km 0% 10% 25% 50% 100%  IE (mm)  ET  (mm)  Knouff  129 132 134 138 138  129 129 128 122 107  Knouff 14 km 10% H e f f l e y 20% R e c r e a t i o n Area 35%  134 153 113  132 147 102  Lac Le Jeune 0% 50% 100%  179 168 178  179 153 132  78  s i t e s was coverage  less  than on the p a r t i a l l y  p l o t had  forested plots.  the h i g h e s t t o t a l T at the Knouff  the h i g h e s t t o t a l T o c c u r r e d on the grass p l o t site. will  These r e s u l t s support  25%  12 km  canopy  site,  while  at the Lac Le Jeune  the s u g g e s t i o n s of C a l d e r  (1979) that grass  t r a n s p i r e more than a c o n i f e r o u s f o r e s t ; however, the e v a p o r a t i o n  of r a i n f a l l resulting The  i n t e r c e p t e d by the f o r e s t  in similar  C a l i b r a t i o n s of the neutron  samples i n d i c a t e d a p o s s i b l e e r r o r  p o s s i b l e e r r o r a s s o c i a t e d with o c c u r r e d under completely  mean square  5.1.5  to u n c e r t a i n t i e s i n  error  of 7%,  and  probe with g r a v i m e t r i c while  the  the P measurements was forested plots.  the  largest  estimated  Consequently,  i n E i s 11.4%, i . e . ( 9  2  +  to be  9%  the root  7 ) * . 2  0  5  Factors Affecting Evapotranspiration and Transpiration Rates The  found  (RMS)  T,  E.  probe measurements of s o i l water content  measurements of P. soil  can compensate f o r the lower  e r r o r s i n the E and T c a l c u l a t i o n s are due  the neutron  and  The  values of the r a t i o of LE  to be q u i t e low,  ranging from  values appear to be too low defined  by L E  0.6  1.1  and  m a x  E and  T are probably  expected  n  McNaughton and soil  to 0.33  b a s i s ) were  (Table 8 ) .  These  a range  G e n e r a l l y , values of  for coniferous forests  1983;  0.15  y)^n (daytime  to be estimates of the P r i e s t l e y - T a y l o r  = a(s/(s+y)R .  Black  to s/(s +  ( G i l e s et a l . 1985;  Black 1981). limited.  These low  In t h i s  a  from  S p i t t l e h o u s e and  a values i n d i c a t e  case E or T would  the  be  to i n c r e a s e with i n c r e a s i n g root zone water content r e g a r d l e s s  of a v a i l a b l e  energy.  Although  E appears  to be s o i l  appear to i n c r e a s e with i n c r e a s i n g W ( F i g . 20). are s t r a t i f i e d  a c c o r d i n g to the a v a i l a b l e energy.  limited,  The  i t does not  data i n t h i s  In cases  figure  i n which E  T a b l e 8:  R a t i o of LE to [ s / ( s + Y)](Rn_ ~ ^) • (Also shown are m e t e o r o l o g i c a l v a r i a b l e s c a l c u l a t i o n of the a v a i l a b l e energy.)  TIME INTERVAL  T  a  (°C)  n  N  R  n  (hrs)  ( h r s ) (W m ) -2  G  S  t  L*  LE  1  used i n the  LE  (W m )  (W m )  (W m )  (W m )  [s/(s + y ) ] ( R -  -2  -2  -2  -2  n  June June June June July July Aug.  1 8 16 23 14 25 20  -  June June June July July Aug. Oct.  7 15 22 13 24 19 4  10.50 9.28 14.87 15.85 19.82 22.27 10.01  5.77 9.09 10.66 8.39 10.85 9.91 8.21  14.7 14.7 14.8 15.0 15.1 14.8 13.5  296.15 246.32 322.71 416.91 424.22 363.65 318.35  10.25 7.39 9.68 12.51 12.73 10.91 9.55  377.93 340.14 431.68 462.96 478.29 412.91 370.37  -36.43 -53.00 -57.11 -46.04 -54.07 -49.26 -52.02  30.62 58.33 26.74 116.66 14.58 31.60 67.08  0.15 0.39 0.14 0.46 0.06 0.14 0.35  June June June July Aug.  1 23 28 14 19  -  June June July Aug. Oct.  22 27 13 18 4  11.55 15.84 15.84 21.00 10.01  8.51 8.39 8.39 10.50 8.21  14.7 15.0 15.0 15.0 13.5  384.93 439.90 455.14 449.07 359.26  11.55 13.20 13.65 13.47 10.78  372.50 393.96 393.96 424.60 364.37  -49.35 -45.70 -45.70 -52.00 -52.02  53.47 106.94 58.82 43.75 108.89  0.39 0.43 0.23 0.18 0.56  LE was c a l c u l a t e d  f o r the 50% canopy coverage p l o t s .  G)  80  R -6 ( w m  2  n  )  2.5-  —  o E  <  •  2-  1.5-  >  404.4 -  •  (S)  <§)  1-  308.8-®  <§)<§)  o  e> 7>t7)  *°  o  331.3-  c  e>e>  0 5-  °  •  lb®  %  O  CL.  *  •  CL (/) z < cn  •  ®  41 1.5 - O  OO  o 50  100  150  200  250  ROOT ZONE (80 cm) WATER STORAGE (mm)  Figure  20:  R e l a t i o n s h i p of the e v a p o t r a n s p i r a t i o n r a t e s to s o i l water storage and a v a i l a b l e energy ( R - G). A v a i l a b l e energy was c a l c u l a t e d as an average f o r the d a y l i g h t hours. n  81  is  l i m i t e d by the a v a i l a b l e energy and not s o i l water c o n t e n t , E would  i n c r e a s e w i t h i n c r e a s i n g a v a i l a b l e energy.  T h i s i s not the case as the  p e r i o d w i t h the h i g h e s t average a v a i l a b l e energy lowest E.  (412 W m  T h i s suggests that the vapour p r e s s u r e d e f i c i t  ) has the may  be  playing  a major r o l e i n the e v a p o t r a n s p i r a t i o n p r o c e s s . The time courses of E and T, a v a i l a b l e energy and the average time D are shown i n F i g . 21 f o r the Knouff 14 km for of  the Lac Le Jeune s i t e . the f o r e s t e d p l o t s and R  day-  s i t e , and i n F i g . 22  There i s a poor c o r r e l a t i o n between E and T n  - G of. a l l the p l o t s .  There does, how-  e v e r , appear to be a s t r o n g n e g a t i v e c o r r e l a t i o n between E and T of the f o r e s t e d p l o t s and vapour p r e s s u r e d e f i c i t . appear to have a c o n s i s t e n t deficit  or a v a i l a b l e  The g r a s s p l o t s do not  r e l a t i o n s h i p w i t h e i t h e r vapour p r e s s u r e  energy.  The average daytime D i s the a r i t h m e t i c average of the 10:00 14:00 D.  for  of  18, 1984  and was  each time i n t e r v a l .  vapour n  F i g u r e 23 shows three d a i l y  The h i g h e s t h o u r l y average v a l u e of D,  August  R  hour v a l u e s (Tanner 1981).  -  pressure d e f i c i t s  2.1 kPa.  i n this  Table 9 l i s t s  Although S p i t t l e h o u s e on Vancouver  G and s o i l water s t o r a g e .  The  traces of  f i g u r e , occurred  on  the average daytime D (1981) recorded g r e a t e r  I s l a n d , he was  a b l e to r e l a t e E t o  s o i l water c o n t e n t s d u r i n g much  the growing season i n h i s study, however, were g r e a t e r than those  found i n t h i s study. sure d e f i c i t s ,  The s e n s i t i v i t y of t r a n s p i r a t i o n to vapour  i n the i n t e r i o r  of B.C.  may  pres-  be due to extended periods of  low s o i l water m a t r i c p o t e n t i a l s and p o s s i b l y due to g r e a t e r of  and  sensitivity  the stomata of i n t e r i o r D o u g l a s - f i r compared to those of c o a s t a l  Douglas-fir.  82  o 3-  1• 0  2.0 £  1.5-  o  '.0 0.5-  0-  •T 400 6  * ° «  c  300 -  0%  200 100  50% 100%  JUN Figure 21:  JUL  AUG  i  SEP  The time course of E and T, the available energy and vapour pressure d e f i c i t s for three plots at the Knouff 12 km s i t e over the 1984 growing season.  83  3-  •o  0  3-1  0  2.0-  1.5  £  a '-° 0.5-  0rT  400-  E 3  300  o  200  c  100  i  50%  0  Figure 22:  0% 100% i  JUN  JUL  AUG  SEP  The time course of E and T, the available energy and vapour pressure d e f i c i t s for three plots at the Lac Le Jeune s i t e over the 1984 growing season.  84  2.5  2^  A  JUNE 3, 1984  O  JULY 6, 1984  •  AUGUST 5, 1984  / /  1.5  f  JO-  \  .0  H  P  •' A-A  0.5 H  • 0  Figure 23:  10 15 TIME (hours)  20  25  Daily traces of vapour pressure d e f i c i t s for three d i f f e r e n t days.  T a b l e 9: Average daytime (10:00 and 14:00 hours) vapour pressure d e f i c i t s f o r d i f f e r e n t time i n t e r v a l s .  Time i n t e r v a l  D (kPa)  Knouff  June June June June July July Aug.  1 8 16 23 14 25 19  -  June June June July July Aug. Oct.  12 km  7 15 22 13 24 18 4  Lac Le Jeune  June June June July Aug.  1 23 28 14 19  -  June June July Aug. Oct.  22 27 13 18 4  S  x  (kPa)  site  0.39 0.31 1.39 1.11 1.97 1.43 0.88  0.04 0.17 0.11 0.39 0.30 0.22 0.23  site  1.40 1.00 1.53 1.83 0.88  0.17 0.19 0.41 0.30 0.23  86  F i g s . 24 and 25 show T p l o t t e d as a f u n c t i o n of D, f o r s o i l water m a t r i c p o t e n t i a l s g r e a t e r than -0.5 MPa, and l e s s than -0.5 MPa, respectively.  I n both  a D of approximately d e c l i n e i n T. and  cases, T i n c r e a s e d w i t h i n c r e a s i n g D, peaking at  1.1 kPa. A f t e r t h i s p o i n t , t h e r e i s a r a p i d  F o r low v a l u e s of D ( l e s s  canopy coverage  s o i l water m a t r i c p o t e n t i a l d i d not appear to i n f l u e n c e T, which was  similar for a l l plots. had  than 0.88 kPa),  At h i g h e r values of D, however, the grass  plots  the h i g h e s t T, and as the f o r e s t cover i n c r e a s e d , T tended to  decrease,  particularly  at values of D h i g h e r than 1.2 kPa. The p l o t s  with low water contents values of D.  ( F i g . 25) had much lower  The grass covered  T, e s p e c i a l l y a t h i g h  p l o t s d i d not respond  t o s o i l water  m a t r i c p o t e n t i a l as much as the f o r e s t e d p l o t s ; however, there was a r e d u c t i o n i n T on these p l o t s at the end of the summer, probably  due to  a r e d u c t i o n i n the grass l e a f area due to g r a z i n g and the senescence of grass on the south  facing slopes.  F i g u r e s 26 and 27 show the r e l a t i o n s h i p  between r j and D f o r c c  s o i l water m a t r i c p o t e n t i a l s (^ ) >-0.5 MPa and <-0.5 MPa, r e s p e c t i v e s  ly,  f o r a range of canopy coverages.  remained r e l a t i v e l y When ty was l e s s s  r j C (  ij/ . s  at h i g h e r D.  At the h i g h e r range of i | / , r  low, i n c r e a s i n g s l i g h t l y  s  c  d  at h i g h e r values of D.  than -0.5 MPa, however, there was a l a r g e i n c r e a s e i n The grass p l o t s had the lowest  The r e s i s t a n c e tended  to i n c r e a s e w i t h  r  c  d  , r e g a r d l e s s of  i n c r e a s i n g canopy  coverage. T h e r e f o r e , D appeared to have a d e f i n i t e c o n t r o l l i n g i n f l u e n c e on transpiration, particularly water m a t r i c p o t e n t i a l s . expected.  on the f o r e s t e d p l o t s and w i t h  low s o i l  When D was low, T was low, as would be  When D i n c r e a s e d to above 1.2 kPa, canopy r e s i s t a n c e  87  Figure 24:  Relationships between t r a n s p i r a t i o n and vapour pressure d e f i c i t s for different canopy coverages and s o i l water matric potentials greater than -0.5 MPa.  88  2.5-1  1  0  " l  0.5  1  1  1  1.5  r  2  VAPOUR PRESSURE DEFICIT (kPa)  Figure 25:  Relationships between transpiration and vapour pressure d e f i c i t s for different canopy coverages and s o i l water matric potentials less than -0.5 MPa.  89  800  CANOPY COVERAGE o  E „w,  600  IOS •  D 25* • 507. A K>0* •  cr UJ  o Z  400  CO  •  CO UJ  ce >-  Q_  o z <  _ _ J3  200-  0.2  0.4  0.6  0.8  1  1.2  1.4  1.6  1.8  2  VAPOUR PRESSURE DEFICIT (kPa) Figure 26:  Relationships between canopy resistance (dry) and the vapour pressure d e f i c i t for different canopy coverages and s o i l water matric potential greater than -0.5 MPa.  90  2500  T i  CANOPY COVERAGE • o%  i  O 1055  £  2000  in Q  co co  Q  25%  •  5055  i i  A 1007.  1500-  ••r  1000  LU  cr >CL O  z < CJ  500-  0  0.5  1  1.5  2  VAPOUR PRESSURE DEFICIT (kPa) Figure 27:  Relationships between canopy resistance (dry) and the vapour pressure d e f i c i t s for different canopy coverages and s o i l water matric potential less than -0.5 MPa.  91  increased, p a r t i c u l a r l y potentials.  The  h i g h e r was  h i g h e r the canopy coverage  the v a l u e of r  ation rates. corresponded was  on the f o r e s t e d s i t e s , w i t h low s o i l water m a t r i c  The  C (  j , and  and  subsequently,  high v a l u e s of r  C (  j found  the h i g h e r the D, the lower  f o r the grass p l o t s , which  l e a f area i n d i c e s and  r e s i s t a n c e s of s e n e s c i n g l e a v e s .  As  Black  (1976).  Consequently,  o c c u r r e d on the p l o t s which had Transpiration stand d e n s i t y .  (the sum  a l . (1985) found  thinned s t a n d .  of T  t  In the former  the thinned p l o t s ,  the l a t t e r  case, s o i l was  content.  stands were s i m i l a r , w h i l e Whitehead  h i g h e r on an unthinned  stand than on a  case, t r a n s p i r a t i o n from an  understory  r e d u c t i o n i n the t r e e t r a n s p i r a t i o n  resulting in similar not l i m i t i n g  t r e e s , and h i g h e r LAI's had  5.2  the h i g h e r t r a n s p i r a t i o n r a t e s  these r e s u l t s , B l a c k et a l . (1980) found  s a l a l component compensated f o r any of  which i s i n agreement  and Tg) decreased w i t h an i n c r e a s e d  unthinned  that T was  stomatal  potential  the h i g h e r a v a i l a b l e s o i l water  In c o n t r a s t with  that the T of thinned and  the h i g h e r  s o i l water m a t r i c  i n c r e a s e d , the s e n s i t i v i t y of T to D decreased,  et  transpir-  to the high values of D o c c u r r i n g at the end of the summer,  probably a r e s u l t of lower  w i t h Tan and  the  the  t o t a l plot  transpirations.  In  so p l o t s w i t h the l a r g e r number of  higher t r a n s p i r a t i o n  rates.  Relationships Derived From the Stem Analysis Trees  5.2.1  Relationships Between Diameter, Age and Stand Density The  diameter  growth at b r e a s t h e i g h t decreased  stand d e n s i t y , as would be expected curves  i n F i g . 28 were f i t t e d  d = m(g  increasing  (Table 10 and F i g . 28).  u s i n g the  -  with  10)°-  The  equation  6  (50)  92  T a b l e 10:  Average  age and diameter at b r e a s t h e i g h t f o r the d i f f e r e n t stand d e n s i t y c l a s s e s .  Density class (trees h a )  mean  0 301 601 901 1501 2701  12.2 16.3 20.1 15.1 11.9 10.0  - 1  -  300 600 900 1200 1800 3000  d (cm) range  6.2 5.8 5.4 5.5 6.6 5.7  -  24.1 35.4 51.2 47.0 21.6 19.5  age ( y e a r s ) mean range  50 ' 58 82 105 51 76  22 30 33 35 35 50  -  120 102 150 210 73 147  93  AGE (years)  F i g u r e 28:  R e l a t i o n s h i p s between diameter at b r e a s t h e i g h t (d) and age f o r t h r e e d i f f e r e n t stand d e n s i t i e s . Each l i n e i s the average diameter growth of f o u r t r e e s which were g r e a t e r than 125 years o l d .  94  where d i s the diameter coefficient is  (cm) at b r e a s t h e i g h t , ra i s an  ( g i v e n i n F i g . 28) s p e c i f i c  age ( y e a r s ) from g e r m i n a t i o n .  experimental  to each d e n s i t y c l a s s and g  The c o n s t a n t ,  10 y e a r s ,  corresponds  to the approximate time r e q u i r e d f o r the t r e e s to reach b r e a s t An e q u a t i o n  to c a l c u l a t e age from d and stand  determined as f o l l o w s . S and the curve  i s as f o l l o w s  ra = 40.5 S  - 1  - 0  -  ( F i g . 29).  d = 40.5 S  By r e a r r a n g i n g  d e n s i t y (S) was  The v a l u e s of m i n F i g . 28 were p l o t t e d a g a i n s t  fitted  where S i s i n t r e e s h a  height.  _ 0  (51)  5  S u b s t i t u t i n g (51) i n t o  - (g - 10) 5  0  (52), age can be expressed  (50) g i v e s  (52)  6  as  g = 10 + 0.00207 d l . 6 7 0 . 8 3 s  This equation this  i f d i s taken a t b r e a s t h e i g h t .  5  3  Although  equation was s u c c e s s f u l l y used f o r the 100 t r e e s sampled f o r stem  analyses 140 years  5.2.2  i s only v a l i d  (  i t should  be used with c a u t i o n f o r t r e e s g r e a t e r  than  of age.  Relationships Between Height, Age and Stand Density Height  (H) i s g e n e r a l l y b e l i e v e d to be mainly  environment r a t h e r than i n the stands  stand  density.  a f u n c t i o n of s i t e  T h i s , however, was not the case  s t u d i e d , as i n d i c a t e d by the h e i g h t growth of the stem  )  F i g u r e 29:  R e l a t i o n s h i p of density.  the p r o p o r t i o n a l i t y  constant  (m)  to s  96 analysis  trees  ( F i g . 30).  At 100 y e a r s of age,  stand d e n s i t y (300-600 t r e e s h a ) - 1  t r e e s growing at a low  were a p p r o x i m a t e l y 48% t a l l e r  t r e e s growing at a moderate s t a n d d e n s i t y (900-1200 t r e e s h a  - 1  ),  than and  a p p r o x i m a t e l y 82% t a l l e r than t r e e s growing a t a h i g h stand d e n s i t y (2700-3000 t r e e s h a  - 1  ).  The c u m u l a t i v e h e i g h t g r o w t h , d e f i n e d as  c u r r e n t h e i g h t of the t r e e d i v i d e d by the c u r r e n t age, 0.26  m year  f o r a s t a n d d e n s i t y of <300 t r e s s h a  - 1  f o r a s t a n d d e n s i t y of 2700 - 3000 t r e e s h a In contrast  - 1  - 1  (Table  the  ranged from  to 0.12  m year  11 and F i g .  31).  to these r e s u l t s , Monserud (1984) found no change  in  the h e i g h t growth r a t e w i t h s t a n d d e n s i t y , on the t r e e s he s e l e c t e d s t u d y i n e i t h e r an even-age selected  stand.  for  The sample t r e e s he  f o r s t u d y , however, were dominants i n an open s t a n d w i t h  consistent  5.2.3  or uneven-age  - 1  even r a d i a l growth and no s i g n s of  suppression.  The Relationship Between Diameter-to-Height Ratio and Stand Density Diameter at b r e a s t h e i g h t i n c r e a s e d l i n e a r l y i n p r o p o r t i o n to  height  (Figs.  d to H ( i . e . 33)  32 and 3 3 ) .  the r a t i o of  the r e c i p r o c a l of the s l o p e of the l i n e s i n F i g s . 32 and  decreased.  ratios  As the s t a n d d e n s i t y i n c r e a s e d ,  Except f o r i m m e d i a t e l y a d j a c e n t d e n s i t y c l a s s e s ,  were s t a t i s t i c a l l y s i g n i f i c a n t l y d i f f e r e n t .  the r a t i o of d to H decreased  the  F i g . 34 shows  that  slowly with i n c r e a s i n g stand d e n s i t y .  The e q u a t i o n t h a t best d e s c r i b e s  the r e l a t i o n s h i p between d/H and S i s  97  AGE (years)  F i g u r e 30:  R e l a t i o n s h i p s between t o t a l h e i g h t and age f o r three d i f f e r ent stand d e n s i t i e s . Each l i n e i s an average of the height growth of four t r e e s which were g r e a t e r than 125 years o l d .  98  T a b l e 11:  Cumulative average h e i g h t growth r a t e f o r stands at d i f f e r e n t densities.  Density class (trees h a )  Height  (m)  age ( y e a r s )  - 1  mean  0 301 601 901 1501 2701  -  300 600 900 1200 1800 3000  12.92 14.19 14.74 15.75 8.62 9.15  range  5.35 4.70 8.00 8.70 5.90 4.95  -  20 .90 25 .74 36 .00 28 .95 16 .20 14 .70  mean  50 58 82 105 51 76  22 30 33 35 35 50  Cumulative average h e i g h t growth r a t e (m y e a r " *)  range  mean  -  0.26 0.21 0.18 0.15 0.17 0.12  120 102 150 210 73 147  0.06 0.08 0.06 0.04 0.02 0.03  99  0.30-1  F i g u r e 31:  R e l a t i o n s h i p s between the cumulative h e i g h t growth and stand density.  100  Figure  32:  R e l a t i o n s h i p s between h e i g h t and diameter at f o r three d i f f e r e n t stand d e n s i t i e s .  breast  height  DIAMETER (cm)  F i g u r e 33:  R e l a t i o n s h i p s between h e i g h t and diameter at b r e a s t f o r t h r e e d i f f e r e n t stand d e n s i t i e s .  height  102  Figure 34:  Relationship between the d/H ratio and stand density. The line drawn is from Equation (54).  103  d/H = 0.0341S  where d/H i s i n m m  - 0 . 140  .  T h i s equation  The L o c a l Volume  5.2.4  A linear  (54)  i s shown as the l i n e  i n F i g . 34.  Equation  l o g a r i t h m i c equation  to d e s c r i b e  current  individual  tree  volume (V) as a f u n c t i o n of d and d/H was determined f o r the stem analysis  t r e e s to be  log  V = -3.983  +  2.603  log d -  0.5556  l o g d/H  where V, d and H are i n c u b i c metres, centimetres tively.  The r e g r e s s i o n equation  and metres,  r e l a t i n g estimated  to a c t u a l volume ( V ) i s V = 0.008 m a  3  + 0.951 V  by u s i n g a l o g f u n c t i o n .  respec-  volume, u s i n g (55)  ( r = 0.986, n = 100, 2  a  SE =0.00697 m ). The 5% underestimate i s due p a r t l y introduced  (55)  This equation,  to a n e g a t i v e  bias  when expressed as a  power f u n c t i o n , becomes  V = 0.000104 d  2 . 04 7  E l i m i n a t i n g H i n (56) u s i n g  V = 0.0000525 d  H  0.556  (56)  (54) g i v e s V i n terms of d and S as  2. 603c  0.078  (57)  When both d and H are expressed i n metres, (56) becomes  V = 1.29 d 2  0  4  7  H 0  5 5 6  (58)  104 and  (57) becomes  d 2.603 <, 0.078  V = 8.44  Using equation (55), a l o c a l volume table was  (59)  developed  (Table 12).  It should be noted that a time factor i s not included i n this table. Although,  for a given diameter at breast height, volume increases with  increasing stand density, trees growing at a higher stand density are actually growing slower.  For example, (53) shows that a tree with a  breast height diameter of 10 cm, trees h a  - 1  growing at a stand density of 2850  would be about three times older than a tree with the same  diameter growing at a stand density of 450 stems  5.2.5  ha . - 1  Relationship Between Form Factor, Tree Diameter and Stand Density The form factor (F) i s defined as  F =  V/V  (60)  c  where V i s the volume of a tree and V ,  the volume of a cone with the  c  same height as the tree and a base diameter equal to the tree diameter at breast height, i s given by  V  = (rr/12) d H  (61)  2  c  Substituting (59) and (61) into (60) gives  F  =  4.93  d  0.0<47 _0.^ H  (62)  Table 12:  L o c a l volume  table.  VOLUME ( r ) d/H R a t i o D (cm)  1.63  1.50  1.38  1.29  1.21*  5 10 15 20 25 30 35 40 45 50 55 60 65 70 75 80 85 90 95 100  0.005 0.032 0.091 0.193 0.345 0.555 0.828 1.170 1.59 2.09 2.69 3.37 4.15 5.04 6.03 7.13 8.34 9.53 11.55 12.59  0.006 0.033 0.096 0.202 0.361 0.580 0.867 1.23 1.67 2.19 2.81 3.53 4.35 5.27 6.31 7.46 8.73 10.23 11.75 13.18  0.006 0.035 0.100 0.212 0.378 0.608 0.908 1.29 1.75 2.30 2.94 3.70 4.55 5.52 6.61 7.82 9.14 10.72 12.30 14.13  0.006 0.036 0.104 0.220 0.393 0.630 0.943 1.34 1.82 2.39 3.06 3.84 4.72 5.73 6.85 8.11 9.51 10.96 12.59  0.006 0.037 0.108 0.228 0.407 0.655 0.977 1.38 1.88 2.47 3.16 3.97 4.90 5.94 7.11 8.41 9.84 11.48  150  450  750  —  1050  (cm/m)  1.14  1.10*  1.075*  1.065*  1.06  0.006 0.390 0.111 0.236 0.420 0.676 1.01 1.43 1.95 2.56 3.27 4.11 5.06 6.14 7.35 8.69  0.006 0.039 0.114 0.240 0.420 0.690 1.03 1.46 1.98 2.61 3.34 4.19 5.16 6.27  0.006 0.039 0.115 0.243 0.435 0.698 1.04 1.48 2.01 2.64 3.39 4.25  0.007 0.039 0.116 0.244 0.438 0.703 1.05 1.49 2.02 2.65  0.007 0.041 0.116 0.245 0.439 0.705 1.05 1.49  — —  — — — —  1350  1650  Midpoint  l  1  — — —  — — — — — —  -T  2250  1950  —  — — — — —  — — — — — — — — — — —  2550  2850  — — —  of D e n s i t y C l a s s ( t r e e s h a " ) 1  The d/H r a t i o s l i s t e d are from a c t u a l data and not determined from e q u a t i o n (54). an (*) were l i n e a r l y i n t e r p o l a t e d from the a c t u a l data p o i n t s i n F i g u r e 34.  R a t i o s marked w i t h  106 where d and H are i n m e t e r s .  S u b s t i t u t i n g (54)  F = 1.10  where d i s i n m e t e r s . constant  d  gives  -0 . 397 -0. 062 s  ( f i 3 )  From t h i s e q u a t i o n i t can be seen t h a t  for a  d , F decreases s l o w l y w i t h i n c r e a s i n g S, and the t r e e s  more c o n i c a l i n shape ( F i g . 3 5 ) . constant  i n t o (62)  S,  T h i s f i g u r e a l s o shows t h a t ,  become for a  the form f a c t o r decreases s i g n i f i c a n t l y w i t h i n c r e a s i n g t r e e  diameter.  5.2.6  R e l i a b i l i t y of the Local Volume Equation E s t i m a t i o n of t r e e volumes u s i n g the l o c a l volume e q u a t i o n  (55)  were compared to a c t u a l volumes of t r e e s 5, 10 and 20 years ago, determined from S m a l i a n ' s e q u a t i o n ( 4 6 ) .  as  Because the d to H r a t i o was  found to decrease s l o w l y w i t h i n c r e a s i n g stand d e n s i t y , the c u r r e n t d t o H r a t i o was assumed to have remained a p p r o x i m a t e l y c o n s t a n t p r e v i o u s 20 y e a r s .  Therefore,  over  the o n l y v a r i a b l e c h a n g i n g i n (55)  the t r e e diameter at b r e a s t h e i g h t .  was  F i g . 36 shows the e s t i m a t e d volume  v e r s u s the a c t u a l volume on the t r e e s 5, 10, and 20 years ago. (55)  the  Equation  e s t i m a t e d the volume of the t r e e s 5, 10 and 20 years ago w i t h i n 9%,  8% and 10%,  respectively  This indicates  that  (r  2  = 0 . 9 6 7 , 0.984 and 0 . 9 8 3 ,  respectively).  the l o c a l volume e q u a t i o n can e s t i m a t e  volume of a t r e e i n the i n v e n t o r y p l o t s w i t h a c c e p t a b l e  the  past  accuracy.  107  1.5-  cr O i— o  cr O  0.5-  500  1000  !  1500  I  2000  i  2500  3000  STAND DENSITY (trees ha" ) 1  Figure 35:  Relationship between the form factor and stand density several values of diameter at breast height.  1  3500  108  ACTUAL VOLUME (m ) 3  F i g u r e 36:  Comparison of p r e d i c t e d versus a c t u a l volumes of t r e e s 5, 10 and 20 years ago. The s o l i d l i n e r e p r e s e n t s a 1:1 relationship. The dashed l i n e r e p r e s e n t s the average r e l a t i o n s h i p s of the p r e d i c t e d and a c t u a l volumes f o r a l l three time p e r i o d s . The a c t u a l equations f o r the p r e d i c t e d volumes ( V ) 5, 10 and 20 years ago, as d e r i v e d from the a c t u a l volume ( V ) are V - 0.013 m + 0 . 9 0 9 V ; V - 0.005 m + 0 . 9 2 4 V ; and V = 0.007 m + 0.895V , respectively. p  a  3  p  a  3  p  a  p  a  3  109  5.3  Average Annual Stand Volume Growth  5.3.1.  Relationship of Average Annual Stand Growth to Stand Density and Volume  T a b l e 13 shows the stand d e n s i t y and l o g g i n g , immediately inventory plots. t i o n , was ated.)  found  Stand  In 1983  f o l l o w i n g l o g g i n g and  (Plot  22,  and  immediately  total  from 9 to 477 m  1968  harvested  volume by 1983  Table  ha  Plots  (15 years a f t e r  from  than p l o t s  - 1  - 1200  3 and 8 had  annual  0.2  to 11.0  trees h a  - 600  time course of the average  m  less  d e n s i t y c l a s s had  i n the 301  14 shows the  80 to  ha  while  . stand  cumulative  In three cases, the volume regained t h e i r  harvested  volume growth r a t e s ( f o r f i v e  s i n c e the l a s t  values o c c u r r i n g on p l o t s with v a l u e s on the 901  from 2 to 243 m - 1  Table  elimin-  (30 years a f t e r l o g g i n g ) .  year p e r i o d s ) of each p l o t  3000 t r e e s h a  transi-  from  2784 t r e e s h a ,  21  l o g g i n g ) , while p l o t 4 r e g a i n e d i t s  15 shows the average  growth r a t e s ranged  .  of l o g g i n g .  been r e g a i n e d .  volume by  seen  f o l l o w i n g l o g g i n g ranged  stand volumes ranged  stand volumes s i n c e the time h a r v e s t e d had  f o r each of the  l o c a t e d i n the IDF-Montane Spruce  stand d e n s i t i e s were between 96 and  volumes ranged  class,  i n 1983  to be more r e p r e s e n t a t i v e of the l a t t e r and was  densities  2552 t r e e s ha  t o t a l stand volume b e f o r e  - 1  f o r the e i g h t p l o t s logged  that the h i g h e s t average - 1200  d e n s i t y c l a s s and  average  values f o r three p l o t s .  - 1  year  - 1  - 1  , with  trees h a  density plots.  slightly  lower  - 1  and  Plots  lowest  the h i g h e s t  i n the 2701  -  F i g . 37 shows the to d e n s i t y  From t h i s f i g u r e ,  i t can  be  growth r a t e s o c c u r r e d on p l o t s i n  ranged The  The  o v e r a l l growth r a t e s  density class.  i n 1953.  4).  the  growth r a t e s , as r e l a t e d  annual  the 901  ha  than 300  trees h a annual  3  l o g g i n g (Appendix  from  6.0  to 9.7  m  3  ha"  1  h i g h e s t stand d e n s i t y c l a s s  year  - 1  (2701  -  Table 13:  T o t a l stand volume and d e n s i t y  Plot number  Last logging (year) < 300 t r e e s h a 9 1968 10 1968 11 1968 12 1968 15 1978 17 1978 301 - 600 t r e e s h a 4 1953 5 1953 18 1978 19 1978 20 1968 21 1978 601 - 900 t r e e s h a 1 1978 6 1953 7 1953  before l o g g i n g ,  Before l o g g i n g Volume Density (m h a ) ( t r e e s h a * ) 3  - 1  -  immediately  f o l l o w i n g l o g g i n g and i n 1983  Following logging Volume Density (m ha~ ) ( t r e e s ha ) d  l  l  1983 Volume Density (m h a ) (trees h a 3  _ l  - 1  19 375 391 487 65 416  352 352 400 560 480 256  2 10 3 2 28 68  288 80 176 208 272 224  24 23 17 9 39 87  304 96 208 224 288 240  181 267 225 282 312 132  528 464 656 528 592 368  67 25 39 103 9 43  414 280 480 384 320 320  194 140 48 124 19 61  464 464 480 384 320 320  477 261 348  1200 752 800  273 81 89  864 304 608  274 236 261  864 656 688  477 328 343 240  1200 1232 826 1072  179 243 207 76  864 976 812 896  416 477 448 105  1040 1088 972 976  309  1760  181  1632  200  1632  235  2864  97  2752  160  2784  - 1  - 1  901 - 1200 t r e e s h a " 2 1953 3 1953 8 1953 13 1968 1501 - 1800 t r e e s h a 16 1978 2701 - 3000 t r e e s h a 14 1953  .  1  - 1  - 1  - 1  )  Ill  T a b l e 14:  C u m u l a t i v e t o t a l s t a n d volume from time of l a s t l o g g i n g to 1983. Volume (m  Plot number  1  Year  Last logging  < 300 t r e e s 9 10 11 12 15 17  ha" )  ha 1968 1968 1968 1968 1978 1978  1953  1958  1963  1968  1973  1978  1983  — — — — —  — — — — —  — — — — — —  2 10 3 2  — —  8 11 5 3  ——  15 13 8 4 28 68  24 23 17 9 29 87  67 25  82 37  103 61  123 76  146 100  9  12  168 119 39 103 15 43  194 140 48 124 19 61  - 1  301 - 600 t r e e s h a " 4 1953 5 1953 18 1978 19 1978 20 1968 21 1978 601 -900 t r e e s h a 1 1978 6 1953 7 1953  1  — — — • ——  — — —  — — —  - 1  901 - 1200 t r e e s h a 2 1953 3 1953 8 1953 13 1968  — —  —  —  —  —  —  —  81 89  100 113  124 140  146 166  174 197  237 202 227  274 236 261  179 243 207  211 298 256  254 346 311  309 382 349 76  352 419 388 100  383 448 418 125  416 477 448 153  181  200  154  160  - 1  —  — —  — ~"  1501 - 1800 t r e e s h a "• 1 16 1978 2701 - 3000 t r e e s h a "• 1 14 97  113  127  137  149  112  Table 15:  Course of annual volume growth from logging to 1983. Average yearly volume growth (m  Plot number  Last logging  19531958  < 300 trees h a ,9 1968 10 1968 11 1968 12 1968 15 1978 17 1978  19581963  19631968  ha  )  19681973  19731978  1978 1983  1.2 0.2 0.4 0.2  1.4 0.4 0.6 0.2  1.8 2.0 1.8 1.0 2.2 3.8  5.2 4.2 1.8 4.2 0.8 3.6  - 1  — — — — — ——  301 - 600 trees h a 4 1953 1953 5 18 1978 1978 19 20 1968 21 1978 601 -900 trees h a 1 1978 1953 6 7 1953  . — — — — — —  — — — — — ——  — ——  — ——  4.0 3.0  4.6 4.8  4.4 3.8  - 1  3.0 2.4  4.2 4.8  — — — —  — — — —  — — — —  — —  —  —  —  —  4.4 5.2  4.6 6.2  8.6 9.6 11.0  10.9 7.2 7.6  8.6 7.4 7.8 4.80  0.6  — —  0.6  ——  - 1  3.8 4.8  901 - 1200 trees ha~ 1 6.4 2 1953 3 1953 11.0 8 1953 9.8 1968 13  4.8 5.4  —  5.6 6.0  7.4 6.8 6.8  6.2 5.8 6.0 5.0  6.6 5.8 6.0 5.6  1501 - 1800 trees ha'-1 1978 16 2701 - 3000 trees ha'-1 3.2 14 1953  3.8  2.8  2.0  2.4  1.0  1.2  113  -1  trees ha 301-600  10  I  601-900 901-1200  O  L.  8  2701-3000  .ZlT  o o  r  L_.  Ul  o > _J <  2-  < — i —  1953  1958  1963  1968  1973  1978  1 983  TIME (year) F i g u r e 37:  The time course of the volume growth r a t e as r e l a t e d to stand d e n s i t y . The 301 - 600 and 601 - 900 l i n e s r e p r e s e n t an average of two p l o t s e a c h , w h i l e the 901 - 1200 l i n e r e p r e s e n t s an average of three p l o t s . Only one p l o t i s i n c l u d e d i n the 2701 - 3000 l i n e .  114 3000 t r e e s h a ) - 1  had the lowest average a n n u a l growth r a t e s which were 3  between 1.0  1  l  and 3.8 m h a  -  year  .  They were h i g h e s t  f o l l o w i n g l o g g i n g and decreased w i t h t i m e . of l e s s than 900 t r e e s h a time s i n c e the l a s t class  P l o t s w i t h stand  densities  tended to have i n c r e a s i n g growth r a t e s w i t h  l o g g i n g , w h i l e the p l o t s In the 901 - 1200  tended t o i n c r e a s e  thereafter  - 1  immediately  declining.  density  f o r a p p r o x i m a t e l y 10 to 15 y e a r s a f t e r  logging,  The growth r a t e s per h e c t a r e c a l c u l a t e d from the  stem a n a l y s i s t r e e s (= 10% of the t o t a l number of t r e e s ) a g r e e d , f o r one i n s t a n c e ,  w i t h i n 8% of the v a l u e s c a l c u l a t e d from core  ( « 70% of the t o t a l number of t r e e s ) .  except analysis  The e x c e p t i o n o c c u r r e d on the  - 1200 d e n s i t y p l o t s d u r i n g the 1958 - 1963  time p e r i o d .  In this  901  case,  the annual growth r a t e s c a l c u l a t e d from the stem a n a l y s i s t r e e s were 16% h i g h e r than those c a l c u l a t e d from the core a n a l y s i s T a b l e 16 shows the growth r a t e s and changes  trees.  i n stand d e n s i t y ,  d/H r a t i o and volume of the permanent sample p l o t s s i n c e The annual growth r a t e s were between 1 and 10 m ha highest  growth r a t e was at a stand d e n s i t y of 1100  the  establishment.  year  .  trees h a  lowest growth r a t e was at a s t a n d d e n s i t y of 2755 t r e e s h a  - 1  - 1  The , while  .  the  These  p l o t s showed the same r e l a t i o n s h i p between annual volume growth r a t e s and stand d e n s i t y as the 21 i n v e n t o r y p l o t s . the l o c a l volume e q u a t i o n ) representative  of t h e i r d e n s i t y c l a s s .  s i n c e treatment establishment  of the treatment  ( t h i n n i n g ) had o c c u r r e d .  The d/H r a t i o s  (used i n  p l o t s were n o t , as  They were, however,  yet,  increasing  The t r e e m o r t a l i t y s i n c e  plot  on the c o n t r o l p l o t s appeared to be due to c o m p e t i t i o n ,  w h i l e the m o r t a l i t y which o c c u r r e d on the treatment to be due to stem c o l l a p s e .  p l o t s was observed  From a sample of 100 t r e e s which were  observed to have stem c o l l a p s e ,  i n the g e n e r a l v i c i n i t y of the  permanent  Table 16:  Plot  Summary of the permanent p l o t  Time of E s t a b l i s h m e n t 1983 d/H Volume density d/H density Volume m" ) (m h a ) ( t r e e s ha ) (cm m ) (m h a ) ( t r e e s h a ^ ( c m -1  A  B  C  D  analysis.  3  - 1  1  -  3  - 1  (m  3  Growth ha y - 1  K n u t s f o r d (1980)* Control Treatment  2280 1100  1.07 1.06  241 140  2240 1050  1.05 1.08  250 170  3 10  Knouff (1982)* Control Treatment  1440 700  1.19 1.19  438 208  1440 700  1.12 1.21  442 214  4 6  S u g a r l o a f (1982)* Control Treatment  2755 888  1.06 1.08  155 107  2521 836  1.06 1.10  156 114  1 7  Lac Le Jeune (1982)* Control Treatment  1987 880  1.12 1.13  170 88  1987 880  1.12 1.16  172 96  2 8  *Year of i n i t i a l p l o t e s t a b l i s h m e n t .  _ 1  )  116  sample p l o t s , 85% a density  had  of ~ 1500  d/H  r a t i o s of l e s s than 1.0  trees h a  before  - 1  heavy t h i n n i n g of such stands can  thinning.  cm  m ,  This  result i n serious  which suggests  -1  indicates  l o s s e s due  that to stem  collapse. Figure  38 shows the  r e l a t i o n s h i p of annual volume growth to  volume f o r d i f f e r e n t stand permanent sample p l o t s . trees h a ,  d e n s i t i e s and  i n c l u d e s both the i n v e n t o r y  In p l o t s w i t h stand  densities greater  annual volume growth r a t e tended to decrease with  - 1  stand and  than  1500  increasing 3  stand  volume.  T h i s was  probably caused by  t r e e s and -  In these p l o t s , stand  increased  3000 t r e e s h a  - 1  which were observed height  of < 6 cm.  exceed  between t r e e s .  In the  c l a s s , there were approximately 320  to be dead.  A l l these t r e e s had  In p l o t s with stands l e s s than 900  stand and  t o t a l stand  d e n s i t i e s of 901  477  m  ha  .  volumes d i d not  - 1200  trees h a  exceed 275 had  - 1  stand  m  m  ha  small  p l o t i n the  2701  trees  ha  breast  trees h a ,  annual  - 1  volume;  ha .  P l o t s with  - 1  volumes between  Annual volume growth r a t e i n c r e a s e d  with  105  increasing 3  stand  volume u n t i l  the  stand  volume reached approximately 275  t h e r e a f t e r volume growth r a t e s Clark year p e r i o d  1.83  suggested that t h i s  cm)  m  ha  m  ha  3  - 1  logging,  were removed.  low  year  - 1  f o r an  s i n c e the  due  20  interior Douglas-fir  s e l e c t i o n logging.  growth r a t e was  particularly  ,  -  decreased.  i n the Kamloops area w i t h f a l l e r ' s  original  1  (1952) c a l c u l a t e d the average annual growth r a t e f o r a to be  - 1  diameters at  volume growth r a t e tended to i n c r e a s e with i n c r e a s i n g stand however, the  170  the presence of a l a r g e number of  competition  density  volume d i d not  —1  Johnstone  to the i n t e n s i t y of  l a r g e diameter c l a s s e s  stand (1984)  the (>  75  T h i s growth r a t e i s s i m i l a r to ones found i n t h i s  study on stands w i t h a low  number of t r e e s and  a low  t o t a l stand  volume.  117  12-i  500  TOTAL STAND VOLUME ( m h a " ) 3  Figure  38:  1  The r e l a t i o n s h i p of t o t a l stand volume to annual volume growth f o r the d i f f e r e n t d e n s i t y c l a s s e s . Both the i n v e n t o r y and permanent sample p l o t s are i n c l u d e d .  118  As  i n d i c a t e d by the data obtained from  t r e e growth a f t e r a p a r t i a l  l o g g i n g more than compensated  number of t r e e s , i . e . the treatment growth r a t e s than partial  the c o n t r o l  stands.  (unlogged)  plots.  This i n d i c a t e s  can surpass  that  the volume growth rates  (1973) on Ponderosa p i n e , and  (1984) and Berg and  Bell  T h i s i s i n c o n t r a s t , however, with Langsaeter that a broad  f o r the fewer  T h i s i s i n agreement with the p o s t - t h i n i n g f i n d -  i n g s , i n even-age stands of B a r r e t t W i l l i a m s o n and C u r t i s  plots,  (logged) p l o t s had much h i g h e r  l o g g i n g of uneven-age stands  of unlogged  the permanent sample  range of stand volumes w i l l  (1979) on D o u g l a s - f i r .  (1941), who h y p o t h e s i z e d  result  i n the same per h e c t a r e  growth  rates.  5.3.2  Relationship Between Average Annual Volume Growth and Stand Structure The  a, q and k c o e f f i c i e n t s  ately after 17.  f o r each of the i n v e n t o r y p l o t s  l o g g i n g and c u r r e n t l y  The values of a and k i n t h i s  immedi-  on the stand are summarized i n Table t a b l e are the a r i t h m e t i c mean of the  a and k values (found i n Appendix 5) f o r p l o t s which met the f o l l o w i n g criteria:  ( i ) o c c u r r e d i n the a p p r o p r i a t e stand d e n s i t y c l a s s and ( i i )  o c c u r r e d i n the a p p r o p r i a t e range of annual  y e a r l y volume growth r a t e s  (from Table 1 5 ) . As o n l y the a values immediately c u r r e n t l y on the stand are known, only the annual for  the f i v e years immediately  time p e r i o d were i n c l u d e d . equation  The v a l u e s of q were c a l c u l a t e d  (31) u s i n g the a r i t h m e t i c mean a v a l u e s .  14, while  the diameter  volume growth r a t e s  f o l l o w i n g l o g g i n g and f o r the 1978 - 1983  volume growth r a t e s c o r r e s p o n d i n g Table  f o l l o w i n g l o g g i n g and  from  The range of annual  to a g i v e n d e n s i t y c l a s s are from  of the l a r g e s t  t r e e i s found  i n Appendix 5.  Table 17:  Density class (trees h a  Stand  -  )  < 300  structure  Average yearly volume growth (m h a y 3  c h a r a c t e r i s t i c s f o r d i f f e r e n t stand d e n s i t i e s and growth  Stand volume (m h a )  a (cm" )  1 - 2 2 - 4  2 - 10 2 - 15 28 - 68  0 0.0275 0.0390  1 1.15 1.21  0 32 70  15 20 30  - 1  _ 1  < 1  )  3  - 1  k ( t r e e s ha  3  3  1  1  cm *)  largest tree (d cm  301  - 600  < 1 2 - 4 4 - 6  0 - 19 25 - 67 103 - 168  0.0743 0.0241 0.0509  1.45 1.13 1.29  83 91 170  20 30 70  601  - 900  3 _ 5 6 - 8  81 - 89 202 - 237  0.0296 0.0510  1.16 1.29  92 222  50 70  76 - 179 207 - 243 383 - 448  0.0888 0.0495 0.0446  1.46 1.28 1.48  435 304 410  35 50 70  181  0.1002  1.65  1242  40  97--154  0.1230  1.85  1539  30  901 - 1200,  4.8 _ 7 9 - 11 5 - 7  6  1501  - 1800  3.8  2701  - 3000  1 _ 3.2  From T a b l e 15. F r o m T a b l e 14. A r i t h m e t i c mean of values i n Appendix 5. ^ C a l c u l a t e d from a r i t h m e t i c a and k values and E q u a t i o n ( 3 0 ) . Frora stand table i n Appendix 5. ^As the average growth r a t e s over time tended to have approximately  rates.  2  5  n  ( F i g . 37), the average stand volumes.  growth rates  of 5 - 7 m  1  ha  1  year  a bell  shape  curve  o c u r r e d at two d i f f e r e n t  120  The  stands had  highly  diameter c l a s s e s , and  i r r e g u l a r diameter d i s t r i b u t i o n s with  there were some l a r g e r diameter c l a s s e s with more  trees  than found i n s m a l l e r  this,  the a, q  represent  diameter c l a s s e s  (5 cm d c l a s s e s ) and  an average f o r the  i n f l u e n c e d by  plot.  The  density,  q c o e f f i c i e n t s also increased  with stand  trees i n the  smaller  stand  density  The  -1  1.29.  This  i n d i c a t e s that  diameter  density,  expected.  The  growth r a t e s - 1200  a high  f o r each of  trees h a ,  the  smaller  At  stand  combined with 40  cm  diameter c l a s s e s d e n s i t i e s > 1500 the  total  stand  were slower reduction As  (76  trees h a ,  proportion  high  - 1  the  i n both height  than those  k coefficients  relatively  ( F i g . 18).  year )], tively  growth r a t e s of the  b a s a l area  small  m  3  the  small  ha ) - 1  On  on  the  p l o t s i n the  the p l o t s i n t h i s  [corresponding  diameter at b r e a s t (35  cm),  and  the a, q and  d e n s i t i e s due  stand  trees  and  these p l o t s  to  901  volume and  - 1200  c l a s s with low  to low height  t r e e s on  (30  the  growth r a t e s .  p r e v i o u s l y mentioned, the h i g h e s t  - 179 - 1  and  to  of t r e e s i n the  a, q and  p l o t being  than trees grown at lower stand  growth r a t e s occurred class  The  from  ( D a n i e l et a_l. 1979).  l a r g e s t t r e e on  volume.  the  ranged from 1.28  d) were observed f o r stands with a l a r g e number of small  a low  values  ranged  - 1  and  the  The  l a r g e r diameter c l a s s e s which tended to grow at a f a s t e r r a t e in  a  i n d i c a t i n g that  c o r r e s p o n d i n g q values there was  and  classes,  diameter c l a s s i n c r e a s e d .  c l a s s e s between 300  0.0495 to 0.0510 cm .  smaller  as would be  of a which corresponded to the h i g h e s t three  Because of  k c o e f f i c i e n t , which i s s t r o n g l y  the number of t r e e s i n the  of  (Appendix 5).  k c o e f f i c i e n t s are approximate  tended to i n c r e a s e with stand  proportion  missing  growth r a t e s of the  k values  annual volume  trees h a stand  - 1  density  volumes  (1 - 5 m  3  l a r g e s t t r e e was were r e l a t i v e l y  ha  - 1  relahigh  (0.0888 cm  , 1.56  and  435  t r e e s ha  cm"  , respectively), indicating a  l a r g e p r o p o r t i o n of small diameter t r e e s . 207  - 243  year  - 1  ),  m  ha  3  (and  - 1  As  volumes i n c r e a s e d  annual volume growth i n c r e a s e d  to 9 - 11 m  the l a r g e s t diameter t r e e (at breast h e i g h t ) on  increased  to 50  ating a higher approximately  cm,  while  the a, q and  p r o p o r t i o n of l a r g e t r e e s . 380 m  ha  , (and  the  When stand  ha  3  indic-  decreased),  to i n c r e a s e  (70  With the presence of more l a r g e r diameter t r e e s , the a, q and  coefficients  decreased.  (approximately  120  However, due  trees h a  - 1  ),  - 1  volumes reached  annual volume growth r a t e s continued  to  stand  k c o e f f i c i e n t s decreased,  the l a r g e s t diameter tree at breast h e i g h t cm).  stand  k  to the i n f l u x of s m a l l stems  the decrease i n the c o e f f i c i e n t s  was  small. Prior  to l o g g i n g , the a, q and k c o e f f i c i e n t s  (Appendix 5 ) . i n negative  ranged  indicates  The  average a, q and  - 1  -1  cm ;  1.06,  0.0566 cm ,  -1  -1  that the o v e r a l l  less  than 1,  the remainder of the p l o t s , -1  0.0108 cm ,  with an i n c r e a s e  5.3.3  For  f o l l o w i n g l o g g i n g , and  respectively, trees h a  t h i r d of the p l o t s , q was  from 0.0084 to 0.0578 cm ,  respectively.  Immediately  212  one  a values.  coefficients 527,  On  tended to be  stand  k values  c u r r e n t l y on  120  tree h a  1.30,  1.05  and  - 1  257  s t r u c t u r e was  to 1.62, to  the stands -1  resulting  the a, q and  prior  cm ;  low  and  to  were, -1  - 1  12  logging,  0.0629 cm ,  trees h a  k  cm .  This  -1  improved a f t e r  1.21,  logging,  i n the number of s m a l l stems.  R e l a t i o n s h i p of  Annual Volume Growth and  T o t a l Growing Season  Transpiration The  r e l a t i o n s h i p between annual volume growth r a t e on  p l o t s f o r the 1978  - 1983  time p e r i o d  (Table 15) and  total  the  inventory  growing  122 season t r a n s p i r a t i o n i n 1984 coverages.  i s shown i n F i g . 39 f o r d i f f e r e n t  I t was assumed t h a t the r e l a t i v e d i f f e r e n c e s  i n growing  season t r a n s p i r a t i o n between p l o t s i n 1984 was r e p r e s e n t a t i v e over the 1978  to 1983 time p e r i o d .  p l o t t i n g the growth r a t e s (Table 16) f o r 1984  on the permanent  canopy  of  those  T h i s assumption was t e s t e d by and growing season  sample p l o t s  ( F i g . 39).  transpiration  A l t h o u g h the  of the a n n u a l growth r a t e of these p l o t s was l e s s than t h a t f o r inventory p l o t s ,  the agreement i n the g e n e r a l  ous a s s u m p t i o n .  G i l e s et a l . ( 1 9 8 5 ) , i n a t r a n s e c t study of  accuracy the  t r e n d supports the  previ-  coastal  Douglas-fir,  found t h a t the l o n g term growth r a t e to s o i l water  deficit  relationship  f o l l o w e d the same t r e n d as t h a t found over a two year  period. Fig.  39 shows t h a t the r e l a t i o n s h i p between growth and t r a n s p i r a -  t i o n had a r e l a t i v e l y h i g h c o r r e l a t i o n f o r the 35 - 65% and 85 canopy coverages (r  = 0.892 and 0 . 8 9 0 , r e s p e c t i v e l y ) .  100%  The growing  season t r a n s p i r a t i o n combined both the c o n t r i b u t i o n of the grass and t r e e components.  I n the case of the 35 - 65% canopy coverage range,  p r o p o r t i o n of t r e e t r a n s p i r a t i o n to t o t a l t r a n s p i r a t i o n would be expected  to remain r o u g h l y c o n s t a n t so t h a t an i n c r e a s e i n T w i l l  c o r r e s p o n d to an i n c r e a s e i n g r o w t h , as i n d i c a t e d by the d a t a . h i g h c o r r e l a t i o n between growth and t r a n s p i r a t i o n f o r the coverages of > 85% would be expected so t h a t T  i s a reduction i n T  due to g r o s s i n t e r c e p t i o n  t  i n the growth r a t e , however, lower T .  This indicates  * T.  canopy  as the c o n t r i b u t i o n of Tg to T  would be n e g l i g i b l e ,  t  The  At h i g h canopy c o v e r a g e s , loss.  This  i s much h i g h e r than expected  there  reduction from j u s t a  t h a t much lower growth r a t e s on p l o t s w i t h a  canopy coverage of > 85% are due m a i n l y to between t r e e  competition.  the  123  12  CANOPY COVERAGE A 5-15% O 20-30% •  O D .C  OP  35-655:  O 85-100%  8 LTD;  [J  •p  6-  o o _J <  4 -  •  o  It O.  3  100  110  120  130  140  150  160  170  GROWING SEASON TRANSPIRATION (mm) F i g u r e 39:  The r e l a t i o n s h i p between a n n u a l volume growth and t o t a l growing season t r a n s p i r a t i o n . The e r r o r bars shown a r e f o r a 25 cm d t r e e w i t h an approximate h e i g h t of 29 m [ E q u a t i o n ( 5 2 ) ] , and assume t h a t the e r r o r s i n diameter and h e i g h t were 0.1 mm and 0 . 5 m, r e s p e c t i v e l y , f o r a one year growth p e r i o d on the permanent sample p l o t s and 0 . 1 mm and 0 . 1 m, r e s p e c t i v e l y , f o r a f i v e year growth p e r i o d on the i n v e n t o r y plots. The form f a c t o r was determined to be 1.2 [ E q u a t i o n (62)]. Open symbols i n d i c a t e p l o t s l o c a t e d next to a m i c r o c l i m a t e s t a t i o n , w h i l e the c l o s e d symbols i n d i c a t e t h a t T was i n t e r p o l a t e d from the m i c r o c l i m a t e p l o t s which had s i m i l a r s o i l c h a r a c t e r i s t i c s (from T a b l e 7 ) . P l o t s marked w i t h a P are permanent sample p l o t s w h i l e the remainder are inventory p l o t s .  Keyes and G r i e r  (1981) found that  p r o d u c t i o n of dense stands was  a reduction  i n above-ground biomass  due to an i n c r e a s e  biomass p r o d u c t i o n , p a r t i c u l a r l y  i n below-ground  i n the growth of the f i n e r o o t s .  At  canopy coverages of < 30%, a poor r e l a t i o n s h i p between growth r a t e and t r a n s p i r a t i o n was  observed, with a l a r g e  s i m i l a r values of T ( F i g . 39).  This  range of growth r a t e s f o r  was p r o b a b l y due to a v a i l a b l e  growing space which i s not occupied by t r e e s large  contribution  and, subsequently, the  of the grass component to t o t a l  P l o t s which had h i g h e r volume growth r a t e s water contents and, t h e r e f o r e ,  a l s o had h i g h e r  h i g h e r s o i l water m a t r i c  These p l o t s a l s o had lower c a l c u l a t e d  soil  potentials.  values of canopy r e s i s t a n c e ,  r e f l e c t i o n of the h i g h e r t r a n s p i r a t i o n r a t e s and 2 7 ) .  transpiration.  on these p l o t s  a  ( F i g s . 26  SUMMARY AND CONCLUSIONS  126 6.  SUMMARY AND CONCLUSIONS  6.1 Conclusions 1.  Canopy coverages  of between 25% and 65% r e s u l t e d I n the h i g h e s t  v a l u e s of the s o i l water s t o r a g e a t the b e g i n n i n g of the growing season,  p a r t i c u l a r l y on s o u t h - f a c i n g s l o p e s ,  d u r a t i o n of snow c o v e r . slopes,  by i n c r e a s i n g the  At lower canopy coverages  on s o u t h e r n  snowmelt tended t o occur b e f o r e the ground thawed a n d ,  consequently, regardless  runoff occurred.  of a s p e c t ,  At h i g h e r canopy  coverages,  the maximum snow water e q u i v a l e n t depth was  reduced s u f f i c i e n t l y to cause s i g n i f i c a n t r e d u c t i o n s i n s o i l  water  s t o r a g e at the b e g i n n i n g of the growing s e a s o n . 2.  Root zone s o i l water s t o r a g e decreased mid-June t o mid-August i n 1984. p l o t s , which had lower i n i t i a l  most r a p i d l y from  The m a j o r i t y of the s o u t h - f a c i n g s o i l water s t o r a g e s , tended to have  s o i l water m a t r i c p o t e n t i a l s  of between - 0 . 1 and - 1 . 5 MPa f o r most  of the 1984 growing s e a s o n .  The n o r t h - f a c i n g s l o p e s  ( e . g . Lac Le  Juene) had h i g h e r snow water e q u i v a l e n t depths and remained throughout the 1984 growing s e a s o n .  The g r a s s p l o t s tended to be  d r i e r at the top of the root z o n e , w h i l e the p a r t i a l l y and f o r e s t e d 3.  forested  p l o t s tended to be d r i e r at d e p t h .  The r a i n f a l l r e a c h i n g t h e ground was an a p p r o x i m a t e l y p r o p o r t i o n of the above-canopy 63% f o r canopy coverages  4.  wetter  constant  r a i n f a l l and was 98%, 95%, 85% and  of 10%, 25%, 50% and 100%, r e s p e c t i v e l y .  The growing season e v a p o t r a n s p i r a t i o n r a t e s were s i m i l a r f o r different  canopy coverage  growing season  p l o t s l o c a t e d at the same s i t e .  The  t r a n s p i r a t i o n , however, v a r i e d c o n s i d e r a b l y f o r  127  different had  canopy coverages.  the h i g h e s t  100% had  coverages of l e s s  growing season t r a n s p i r a t i o n  canopy coverage p l o t s , the h i g h e s t  P l o t s with  respectively.  folowed  than 25%  by the 50% and  The Lac Le Jeune p l o t s  growing season t r a n s p i r a t i o n ,  r e g a r d l e s s of canopy  coverage. T r a n s p i r a t i o n was found to be more s e n s i t i v e energy.  to be s o i l  l i m i t e d ; however, i t was  to vapour p r e s s u r e  deficits  to a v a i l a b l e  T h i s s e n s i t i v i t y may be due to extended p e r i o d s of low  s o i l water m a t r i c adaptation  p o t e n t i a l s and, p o s s i b l y , a p h y s i o l o g i c a l  of the i n t e r i o r D o u g l a s - f i r s p e c i e s .  Canopy r e s i s t a n c e i n c r e a s e d s l i g h t l y with sure d e f i c i t s ally  than  at high  s o i l water m a t r i c  at low s o i l water m a t r i c  i n c r e a s i n g vapour  potentials.  d e f i c i t s , when the vapour pressure water m a t r i c p o t e n t i a l was low. ages had higher  T h i s r e s u l t e d i n a much  in  deficit  pressure  was h i g h and the s o i l  Furthermore, h i g h e r  canopy  canopy r e s i s t a n c e s at h i g h vapour p r e s s u r e  i n lower t r a n s p i r a t i o n  the p r o p o r t i o n of the t o t a l  pres-  p o t e n t i a l s , but d r a m a t i c -  g r e a t e r d e c l i n e i n t r a n s p i r a t i o n with i n c r e a s i n g vapour  resulting  found  rates.  This r e f l e c t s  deficits  the i n c r e a s e  transpiration originating  t r e e s as the t r e e s are more s e n s i t i v e than grass  cover-  from the  to vapour  pressure  deficits. Both the diameter with  ( b r e a s t h e i g h t ) and h e i g h t  i n c r e a s i n g stand d e n s i t y .  The  of diameter to h e i g h t was found  r a t i o of b r e a s t height  c l a s s was found  decreased  Diameter at b r e a s t h e i g h t was  to be p r o p o r t i o n a l to (age minus 10 y e a r s ) tionship  growth r a t e s  0 , 6  the r e l a -  to be l i n e a r .  diameter-to-height  to be a good i n d i c a t o r  , while  found  f o r a given d e n s i t y  of form f a c t o r and was used  128  in  the l o c a l volume e q u a t i o n .  current  to estimate  t r e e volumes and a l s o t r e e volumes 5, 10 and 20 years ago  with acceptable 9.  T h i s equation was found  The c o n i c a l form  accuracy. f a c t o r was found  to decrease  s l o w l y with i n c r e a s -  i n g stand d e n s i t y and r a p i d l y with i n c r e a s i n g diameter. a diameter  Trees  with  at b r e a s t h e i g h t o f 40 cm a t stand d e n s i t i e s of 1000 and  2000 t r e e s h a  - 1  had c o n i c a l form  f a c t o r s of about 1.1 and 1.0,  respectively. 10.  The h i g h e s t annual  volume growth r a t e of 9 to 11 m  ha  year-  o c c u r r e d a t stand d e n s i t i e s r a n g i n g from 901 - 1200 t r e e s h a o  t o t a l stand volumes of between 200 t o 300 m  — 1  ha  .  At h i g h e r  volumes, there was a r e d u c t i o n i n annual growth r a t e , to between-tree c o m p e t i t i o n . growth r a t e s appeared the annual  At lower  growth r a t e s i n c r e a s e d with  to stand volumes r a n g i n g from 97 to 240 m with i n c r e a s i n g stand volumes.  - 1  s m a l l diameter  h i g h stand Values  cm  -1  trees.  of q (5 cm diameter  Corresponding  ha  -  , growth r a t e s  T h i s was due to very  slow  M o r t a l i t y was observed  at these  c l a s s e s ) r a n g i n g from 1.28 t o 1.29 f o r  than 1200 t r e e s  - 1  a and k values ranged  and 170 to 304 t r e e s h a  diameter  corresponded  1  densities.  stand d e n s i t i e s of l e s s rate.  , which  At  and h e i g h t growth r a t e s c a u s i n g the stand to c o n s i s t of  primarily  11.  however,  i n c r e a s i n g stand volume.  3  diameter  lower  growing space;  stand d e n s i t i e s of g r e a t e r than 1500 t r e e s h a  decreased  stand  probably due  stand d e n s i t i e s ,  to be due to u n f i l l e d  with  - 1  - 1  cm , -1  had the h i g h e s t growth from 0.0495 t o 0.0510  respectively.  d i s t r i b u t i o n c o u l d o n l y be maintained  T h i s stand  on stands of < 1500  129  trees h a  - 1  .  At higher stand d e n s i t i e s  were much h i g h e r due to the l a r g e s t  the a, q, and k c o e f f i c i e n t s  diameter t r e e being  relatively  small. 12.  Based on the c a l c u l a t e d a, q and k v a l u e s p r i o r partial  l o g g i n g , i t was found t h a t , i n g e n e r a l , the stands  appeared partial  to and a f t e r a studied  to have b e t t e r o v e r a l l diameter d i s t r i b u t i o n a f t e r a logging.  However, i n some cases there were m i s s i n g  diameter c l a s s e s and, i n other cases, the t o t a l r e s i d u a l s t a n d volumes were lower  than necessary f o r f a v o u r a b l e annual growth  rates. 13.  At canopy coverages ha  - 1  ),  of > 35% (or stand d e n s i t i e s  there was a l i n e a r c o r r e l a t i o n between growing  p i r a t i o n and annual volume growth.  annual volume growth was a t t r i b u t e d grass to the t o t a l (> 1500 t r e e s h a  due  - 1  transpiration.  season  trans-  At lower canopy coverages, the  poor c o r r e l a t i o n observed between growing  higher  of > 600 t r e e s  season t r a n s p i r a t i o n and  to the high c o n t r i b u t i o n of the At canopy coverages of > 85%  ) , the r e d u c t i o n i n annual volume growth i s much  than would be p r e d i c t e d from the r e d u c t i o n i n t r a n s p i r a t i o n  to gross i n t e r c e p t i o n  loss.  volume growth r a t e s appeared  In t h i s  case, the lower  annual  to be p r i m a r i l y due to between t r e e  competition.  6.2  Management Implications Primary o b j e c t i v e s  of a management p l a n which would o p t i m i z e annual  growth r a t e s would be to ( i ) reduce gross i n t e r c e p t i o n rainfall  and s n o w f a l l to i n c r e a s e s o i l water  transpiration,  l o s s of both the  content and growing  season  ( i i ) maximize the p r o p o r t i o n of t o t a l t r a n s p i r a t i o n  which  130 originates  from the t r e e s ,  ( i i i ) reduce between-tree  c o m p e t i t i o n , and  ( i v ) m a i n t a i n a f a v o u r a b l e t r e e diameter d i s t r i b u t i o n . F i g u r e 40 shows the average of the h i g h e s t annual growth r a t e s v e r s u s s t a n d volumes and i n c l u d e s a l l study p l o t s (see  F i g . 38).  o r d e r to be i n Zone A , which has the h i g h e s t growth r a t e s , s h o u l d have between 900 and 1200 t r e e s h a at these s t a n d d e n s i t i e s ,  - 1  year  - 1  .  the s t a n d  The f i g u r e suggests  that  stand volumes s h o u l d be reduced to  a p p r o x i m a t e l y 250 m h a . ha  - 1  In  Assuming the s t a n d w i l l grow about 10 m  and a t e n - y e a r  c u t t i n g c y c l e i s d e s i r a b l e , r e - e n t r y i n t o the  s t a n d s h o u l d occur at a stand volume of 350 m ha c u t t i n g c y c l e i s d e s i r e d , F i g . 40 suggests  that  .  If  a 20 year  stands s h o u l d be  m a i n t a i n e d w i t h i n the range of stand volumes shown by Zone B ( » 220 380 m ha ha  - 1  year  ) , which s h o u l d have an average volume growth r a t e of 8 m - 1  f o r the 20 years p e r i o d .  To o b t a i n these growth r a t e s ,  s t a n d d e n s i t y s h o u l d be between 800 and 1300 t r e e s h a Both the management s c e n a r i o s that  - 1  cm m ) . - 1  If  -  i l l u s t r a t e d by Zones A and B assume  the o r i g i n a l s t a n d d e n s i t y i s < 1500 t r e e s h a  h e i g h t r a t i o of 1.0 ha  -  - 1  (or a d i a m e t e r  the o r i g i n a l s t a n d has > 1500  (Zone C, between 100 to 220 m h a 3  s t a n d s h o u l d be done w i t h c a u t i o n .  - 1  ),  to  trees  the f i r s t e n t r y i n t o the  The r i s k of stem c o l l a p s e i s v e r y  h i g h at these s t a n d d e n s i t i e s and s e v e r a l s t a n d e n t r i e s may be to c r e a t e the d e s i r e d stem diameter d i s t r i b u t i o n .  necessary  In t h i s c a s e ,  the  t r e e s s h o u l d be t h i n n e d to a s p a c i n g of t w i c e the canopy w i d t h ( a p p r o x i m a t e l y 65% canopy coverage or a s p a c i n g of  » 3 m x 3 m).  s t a n d s h o u l d be t h i n n e d a g a i n once canopy c l o s u r e o c c u r s . r e q u i r e frequent e n t r i e s  T h i s would  i n t o the s t a n d s ; however, i t would reduce  m o r t a l i t y of the next crop of  trees.  The  the  C3i  12  F i g u r e AO:  R e l a t i o n s h i p between annual volume growth and t o t a l stand volume i n t e r p r e t e d f o r management purposes. M a i n t a i n i n g the stand i n Zone A with 900 to 1200 t r e e s h a would be c o n s i d e r e d o p t i m a l . The c u t t i n g c y c l e would be ten y e a r s . In cases where a 20 year c u t t i n g c y c l e i s d e s i r e d , stands should be maintained w i t h between 800 - 1300 t r e e s h a and w i t h stand volumes r e p r e s e n t e d .by Zone B. Logging i n Zone C should be done with c a u t i o n i f there are > 1500 trees h a on the stand, as stem c o l l a p s e would l i k e l y be a problem. Logging down to Zone D would be unacceptable, p a r t i c u l a r l y i f < 400 t r e e s h a remain a f t e r l o g g i n g . T h i s i s due to both r e g e n e r a t i o n problems and low annual volume growth rates. In a l l cases, uneven-age stand diameter d i s t r i b u t i o n s , with some l a r g e r r e s i d u a l t r e e s , should be maintained. - 1  - 1  - 1  - 1  132  The < 100 m  3  avoided.  final ha  - 1  zone i n F i g . 40 i s D.  Logging  to a t o t a l  , p a r t i c u l a r l y on fewer than 400 t r e e s h a  - 1  stand volume of , should be  N a t u r a l r e g e n e r a t i o n may become a problem at these low l e v e l s .  A l s o there would be a l a r g e grass component r e s u l t i n g volume growth r a t e s .  i n low annual  In a l l cases, i t would be important  f a v o u r a b l e stem diameter  distribution,  even i f j u v e n i l e  to m a i n t a i n a  s p a c i n g was  required. This  f i g u r e a l l o w s a rough estimate of the stand volumes and  d e n s i t i e s which are n e c e s s a r y growth, based  to m a i n t a i n c e r t a i n r a t e s of annual  on growth r a t e s determined  from a l l study p l o t s .  volume  F i g . 39  suggests, however, that stands which have h i g h e r s o i l water m a t r i c p o t e n t i a l s and, e s s e n t i a l l y , h i g h e r growing season w i l l have a h i g h e r annual  volume growth r a t e s .  t r a n s p i r a t i o n rates  T h e r e f o r e , stands which  have h i g h e r a v a i l a b l e s o i l water content may have ( i ) h i g h e r volume growth r a t e s , lower  annual  ( i i ) maximum growth r a t e s that occur at h i g h e r or  stand volumes, or ( i i i ) a combination  other hand, s i t e s which tend to be d r i e r  of ( i ) and ( i i ) .  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F o r e s t f e r t i l i z a t i o n s c r e e n i n g t r i a l s , I n t e r i o r of B r i t i s h C o l u m b i a , 1980: Lodgepole p i n e , D o u g l a s - f i r and w h i t e s p r u c e . R e s . B r a n c h , B . C . M . F . , U n i v e r s i t y of B r i t i s h C o l u m b i a , Vancouver, B . C . Whitehead, D. P . G . J a r v i s and R . H . W a r i n g . 1984. Stomatal c o n d u c t a n c e , t r a n s p i r a t i o n , and r e s i s t a n c e to water uptake i n a Pinus s y l v e s t r i s spacing experiment. Can. J . F o r . Res. 14:692-700. W i l l i a m s o n , R. L . 1973. R e s u l t s of shelterwood h a r v e s t i n g of D o u g l a s f i r i n the Cascades of w e s t e r n Oregon. U . S . D . A . F o r . S e r v . R e s . Paper PNW-161. 11 PPW i l l i a m s o n , R . L . and R . O . C u r t i s . 1984. 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Forest  cover and  APPENDIX 1: NATURAL REGENERATION UNDER A FALLER SELECTION METHOD  141  APPENDIX 1: NATURAL REGENERATION UNDER A FALLER SELECTION METHOD  F i g u r e A l - 1 shows the amount of r e g e n e r a t i o n which o c c u r r e d a t different  stand d e n s i t i e s .  r e g e n e r a t i o n surveys  This figure  i n c l u d e s the r e s u l t s of the  on a l l i n v e n t o r y and m i c r o c l i m a t e  d e n s i t i e s of between 400 and 1300 t r e e s h a " ( o r canopy 1  ranging At  lower  plots.  At stand  coverages  from 10% to 75%) n a t u r a l r e g e n e r a t i o n appears to be adequate. stand d e n s i t i e s  soil  as 75°C at 1:00 p.m., prevent densities,  s u r f a c e temperatures, regeneration success.  between-tree c o m p e t i t i o n  inhibits  which can be as high At h i g h e r  regeneration  stand  establishment.  142  20000-1  15000  10000  5000-  1  500  1000  1500  2000  2500  3000  STAND DENSITY (trees h a " ' ) Figure A l - 1 :  The r e l a t i o n s h i p between the number of r e g e n e r a t i o n e s t a b l i s h e d and the t o t a l number of t r e e s per h e c t a r e .  143  APPENDIX 2: ANALYSIS OF FISH EYE LENS PHOTOGRAPHS TO DETERMINE CANOPY COVERAGE  144  APPENDIX 2: ANALYSIS OF FISH EYE LENS PHOTOGRAPHS TO DETERMINE CANOPY COVERAGES  The lens  fish  eye lens  which was attached  photographs were taken w i t h a S o l i g a r to a M i n o l t a XG w i t h a 52 mm inner  c o n v e r t o r , u s i n g Kodak PX-135 panochromatic 68 mm diameter c i r c u l a r f i e l d . was d i v i d e d  t o t a l canopy canopy  #25 ASA.  The g r i d used f o r a n a l y s i s  i n t o 27 equal s e c t o r s  coverage was determined  film  as shown i n F i g . A2-1.  f o r each s e c t o r  coverage of the p l o t .  f i s h eye  diameter P r i n t s had a of the p r i n t s The canopy  and the average was used  f o r the  F i g s . A2-2 through A2-4 i l l u s t r a t e  coverages of 10%, 50% and 100%, r e s p e c t i v e l y .  143  Figure  A.2-1:  Grid  f o r a n a l y s i s of f i s h eye l e n s photographs a diameter of 68 mm.  with  146  Figure A2-2:  Example of 10% canopy coverage.  Figure A2-3:  Example of 50% canopy coverage.  148  Figure A2-4:  Example of a forested plot (>85% canopy coverage).  APPENDIX 3: FOLIAR ANALYSIS OF THE LAC LE JEUNE AND KNOUFF 12 km SITES  150  APPENDIX 3 : FOLIAR ANALYSIS OF THE LAC LE JEUNE AND KNOUFF 12 km SITES  A foliar  a n a l y s i s was  Lac Le Jeune s i t e s . suggested  T a b l e A3-1 Europe.  T a b l e A3-1  minimum v a l u e s .  specifically  for interior  the Knouff  l i s t s the average  12 km  and  r e s u l t s along with  U n f o r t u n a t e l y , no c r i t i c a l v a l u e s were Douglas-fir.  The  are from c o a s t a l D o u g l a s - f i r and  found  c r i t i c a l values l i s t e d i n s c r e e n i n g t r i a l s done i n  T h e r e f o r e , t h e s e r e s u l t s must be used w i t h c a u t i o n , and  only serve as a guide.  should  I t i s d o u b t f u l t h a t f e r t i l i z a t i o n would i n c r e a s e  volume growth of i n t e r i o r deficits.  done on t r e e s from  D o u g l a s - f i r stands  due  to the prolonged  water  151 Table A3-1:  # 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16  a b c d  Foliar  analysis results.  Concentration  Knouff 12 km  Lac Le Jeune  Suggestei minimum  N% P% K% Ca% Mg% Al% Mn ppm Fe ppm Zn ppm Cu ppm Fe ppm Cu ppm A c t i v e Fe ppm B ppm S% N/S  0.943 0.195 0.710 0.406 0.097 0.006 523 40 20 1 42.5 3.2 25 16.3 0.1 9.6  1.115 0.256 0.960 0.385 0.148 0.005 660 33 31 2.5 36.9 4.2 25 18.2 0.104 10.69  l 0.14 0.5 0.1 0.1  M o r r i s o n (1984) E v e r a r d (1973) B a l l a r d (1979) S t o n e (1968)  a  b  b  b b  0.1 10 2.6 50 2.6 50 10  b  d  a  c  a  c  c  14.6  C  (:  152 LITERATURE CITED B a l l a r d , T . M . 1979. Development of i n t e r i m o p e r a t i o n a l g u i d e l i n e s f o r f o r e s t f e r t i l i z a t i o n i n the Kamloops F o r e s t D i s t r i c t . Unpubl. C o n t r a c t Research Report to B . C . F o r . S e r v . 86 p p . Everard, J . 1973. F o l i a r a n a l y s i s sampling methods i n t e r p r e t a t i o n and a p p l i c a t i o n of r e s u l t s . Q . J . F o r . 67:51-66. Morrison, I.K. 1974. M i n e r a l n u t r i t i o n of c o n i f e r s w i t h s p e c i a l r e f e r e n c e to n u t r i e n t s t a t u s i n t e r p r e t a t i o n : A r e v i e w of the literature. C a n . F o r . S e r v . P u b l . No. 1343. S t o n e , E . L . 1968. Microelement n u t r i t i o n of f o r e s t t r e e s : a review. In: Begnston, G . M . , F o r e s t F e r t i l i z a t i o n Theory and P r a c t i c e . TVA, Muscle S h o a l s , Alabama, p p . 1 3 2 - 1 7 5 .  153  APPENDIX 4: ANALYSIS OF AVERAGE VOLUME GROWTH BY DIAMETER CLASS FOR ALL INVENTORY PLOTS IN THREE STAND DENSITY CLASSES FOR THE 1978-1983 TIME INTERVAL.  154  APPENDIX 4: ANALYSIS OF AVERAGE VOLUME GROWTH BY DIAMETER  CLASS FOR ALL INVENTORY  PLOTS IN THREE STAND DENSITY CLASSES FOR THE 1978-1983 TIME INTERVAL.  Analysis  of the y e a r l y diameter  (at breast  h e i g h t ) growth f o r the  1978 - 1983 p e r i o d was done f o r a l l I n v e n t o r y p l o t s i n the 300 - 600, 900 - 1200 and 2700 - 3000 t r e e s h a included and  i n the lowest d e n s i t y  one i n the h i g h e s t  density  - 1  density  classes.  S i x p l o t s were  c l a s s , four i n the middle d e n s i t y class.  class  The volume growth of trees i n the  5 - 15, 15 - 25, 25 - 35, 35 - 45 and 45 - 55 cm diameter c l a s s e s were analyzed  separately  f o r each d e n s i t y  diameter c l a s s was determined  class.  The number of trees i n each  from the stand t a b l e i n Appendix  5.  Tree  volumes were c a l c u l a t e d from E q u a t i o n ( 5 7 ) . Table A4-1 i l l u s t r a t e s the annual volume growth r a t e s which  would o c c u r , given  and number of t r e e s f o r each 10 cm diameter inventory  the diameter growth  c l a s s as i n d i c a t e d from the  p l o t s , and summed f o r a l l t r e e s on the p l o t .  Table A4-1:  Mid point of diameter class (cm)  Analysis i n three  of average volume growth by diameter c l a s s f o r a l l i n v e n t o r y stand d e n s i t y c l a s s e s f o r the 1978 - 1983 time i n t e r v a l .  Number of trees  300 - 600 trees h a " 10 200 20 150 100 30 40 50 50 25 Total 525  1 year diameter increment (cm)  Volume (m~ 1983  1982  3  ha" ) 1  difference  Total volume (m h a year 3  - 1  1  900 - 1200. trees h a " 325 10 250 20 30 200 150 40 100 50 1025 Total  0.171 0.226 0.322 0.289 0.265  0.035 0.210 0.603 1.263 2.247  0.034 0.204 0.586 1.240 2.216  0.001 0.006 0.017 0.023 0.031  0.2 0.9 1.7 1.2 0.8 4.8  0.130 0.175 0.276 0.243 0.210  0.038 0.226 0.650 1.363 2.424  0.036 0.221 0.634 1.341 2.398  0.002 0.005 0.016 0.022 0.026  0.6 1.3 3.2 3.3 2.6 11.0  0.045 0.075 0.128  0.0395 0.239 0.689  0.390 0.237 0.681  0.005 0.002 0.008  1.1 1.2 0.4 2.2  1  2700 - 3000 t r e e s h a 10 2100 600 20 50 30 Total 2750  - 1  plots  - 1  )  APPENDIX 5: THE a, q AND k COEFFICIENTS, NUMBER OF TREES AND STAND VOLUMES PRIOR TO LOGGING, IMMEDIATELY FOLLOWING LOGGING AND CURRENTLY ON THE STAND.  157  APPENDIX 5: THE a, q AND k COEFFICIENTS, NUMBER OF TREES AND STAND VOLUMES PRIOR TO LOGGING, IMMEDIATELY FOLLOWING LOGGING AND CURRENTLY ON THE STAND. Included plots  i n t h i s appendix i s the 1984 stand  (Table A5-1).  The more commonly found diameter d i s t r i b u t i o n s are  i l l u s t r a t e d i n F i g s . A5-1 through A 5 3 . —  structure  t a b l e f o r the i n v e n t o r y  characteristics  c u r r e n t l y on the stand.  prior  Table A5 2 l i s t s —  the stand  to l o g g i n g , f o l l o w i n g l o g g i n g and  TABLE A 5 ~ l :  Stand  table f o r the Inventory p l o t s by d (cm) c l a s s e s , 1984. Trees ha"' d c l a s s e s (cm)  Plot Regenernumber a t i o n <5.0 1 1488 48 2 13272 96 3 8128 48 4 5072 0 5 15056 0 6 6336 64 3472 7 112 3472 8 64 3232 9 16 10 528 16 656 11 32 12 592 172 992 13 208 0* 624 14 15 1456 16 912 16 250 17 528 0 736 64 18 1824 19 48 20 48 96 9216 32 21  5.110 416 208 256 144 112 304 240 240 32 16 64 80 432 768 96 250 48 128 112 112 48  10.115 160 112 128 64 64 64 112 96 32 16 48 16 208 1184 80 640 32 192 32 64 64  15.120 208 128 192 64 80 32 32 64 16 16 16 48 48 160 32 352 48 48 48 16 32  The p l o t numbers are the same as l n Table 2. *A11 the small trees l n t h i s p l o t were dead.  20. 125 32 48 96 32 32 96 48 32 32 16 48 0 64 16 16 304 48 0 32 32 80  25.130 0 144 96 32 16 32 32 32 48 16 0 0 0 32 32 64 16 0 64 0 64  30.135 16 176 80 48 16 16 48 48 32 0 0 0 0 0 0 0 32 0 16 0 0  35.140 16 96 80 16 48 0 32 64 16 0 0 0 0 0 0 0 0 0 32 0 0  40.145 0 16 64 0 0 0 0 48 64 0 0 0 0 0 0 16 .0 0 0 0 0  45.150 0 16 32 16 32 16 16 32 0 0 0 0 0 0 0 0 0 0 0 0 0  Totals 50.155 0 0 0 0 0 0 16 0 16 0 0 0 0 0 0 0 0 0 0 0 0  55.160 0 0 16 0 0 16 0 0 16 0 0 0 0 0 0 0 0 0 0 0 0  60.165 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0. 0 0 0 0 0  65.170 0 0 0 16 0 16 0 16 0 0 0 0 0 0 0 0 0 0 0 0 0  <5.0 cm d 896 1040 1072 432 400 656 688 672 320 96 208 224 960 2784 272 1632 224 480 384 320 320  All trees 2384 13312 9200 5504 15456 6992 4160 4144 3552 624 864 816 1952 2784 1728 2544 752 1216 2208 368 9536  TABLE A5-2:  Plot Year number logged 1 1978 2 1953 3 1953 4 1953 5 1953 6 1953 7 1953 8 1953 9 1968 10 1968 11 1968 12 1958 13 1968 14 1953 15 1978 16 1978 17 1978 18 1978 19 1978 20 1978 21 1978  Number of trees ha" 1200 1232 1216 528 464 752 800 926 352 352 400 560 1072 2864 480 1760 416 656 528 592 368 1  Stand c h a r a c t e r i s t i c s p r i o r to l o g g i n g , Immediately f o l l o w i n g l o g g i n g , and c u r r e n t l y on the s t a n d .  Vcilume a (m h a " ) (cm" ) 477 0.0116 329 0.0384 334 0.0499 181 0.0366 267 -0.0019 261 . 0.0183 348 0.0084 343 0.0275 19 0 375 -0.322 391 -0.0081 487 0 240 0.0139 235 0.0578 65 -0.0085 309 0.0301 256 -0.0231 225 0.0231 282 -0.0173 312 -0.0173 132 0.0183 5  1  The p l o t numbers are the same as In Table breast h e i g h t .  q  k  1  1  2.  Number of trees Volume ha" (m h a ) 864 237 928 179 1072 243 414 67 2 80 25 304 81 608 89 816 207 288 2 80 10 176 3 208 2 896 76 2752 97 272 28 1632 181 224 68 480 39 384 103 320 9 320 43  1.05 1.05 1.12 1.06 0.95 1.11 1.05 1.20 1.00 0.75 0.75 1.00 1.15 1.62 0.85 1.28 0. 95 1.14 0.99 0.95 1.20  144 235 527 208 104 96 61 63 0 12 30 0 110 513 29 122 51 81 46 40 48  3  - 1  a (cm" ) 0.0536 0.0576 0.0528 0.0520 0 0.0278 0.0313 0.0575 0 0 0 0.1099 0.1040 0.1522 0.0347 0.2041 0.0231 0.0924 0.0485 0.0549 0.0283  q  k  1  Number of trees Volume ha" (m h a ) 864 274 1040 416 1028 477 464 194 464 140 656 236 688 261 976 448 304 24 96 23 208 17 224 9 976 105 2784 160 288 39 1632 200 240 87 480 48 384 124 320 19 320 61 1  137 1.26 285 1.11 1.12 380 1.14 215 1 .00 0 1.17 106 1.13 77 1.20 227 1.00 0 1.00 0 1.00 0 144 1.50 1.43 362 1.75 1539 1.20 45 1.60 442 1.11 40 1.33 161 1.10 78 1.50 83 1.10 58  A l l values are f o r 5 cm diameter c l a s s e s and only  Include  3  - 1  trees greater  a (cm" ) 0.0536 0.0421 0.0693 0.0549 0.0486 0.0497 0.0478 0.0347 0 0 0 0.1099 0.1199 0.1522 0.0549 0.2041 0.0231 0.0924 0.0485 0.0599 0.0203  q  k  1  1.26 536 1.49 357 1.43 512 1.29 249 1.17 182 1.15 219 1.17 178 1.43 91 1.00 0 1.00 0 1.00 0 1.50 144 1.80 584 1.75 1539 1.14 83 1.60 442 1.11 40 1.33 161 1.10 78 1.50 83 1.101 58  than 5.0 cm at  vO  160  80-i  DIAMETER CLASS  Figure  A5-1:  (cm)  Example of the diameter d i s t r i b u t i o n inventory p l o t s .  found on 18% of the  161  F i g u r e A5-2:  Example of the diameter d i s t r i b u t i o n inventory p l o t s .  found on 45% of the  1200-1  1000-  DIAMETER C L A S S Figure A5-3:  (cm)  Example of the d i a m e t e r d i s t r i b u t i o n found on 37% o f inventory plots.  163  APPENDIX 6: BASAL AREAS CORRESPONDING TO THE DIFFERENT STAND VOLUMES FOR THE DIFFERENT DENSITY CLASSES IN 1983  Table A6-1 shows the b a s a l areas i n v e n t o r y p l o t s i n 1983.  and stand  volumes on the 21  TABLE A6-1:  Basal  areas which correspond to the d i f f e r e n t c l a s s e s In 1983.  Plot number  Volume (m h a "  B a s a l area (m h a )  3  < 300 trees ha" 9 10 11 12 15 17 .  2  - 1  1  24 23 17 9 29 87  8 9 6 3 14 17  301 - 600 t r e e s h a 4 194 140 5 18 48 124 19 20 19 21 61  28 24 7 14 3 8  601 - 900 t r e e s h a 274 1 6 236 7 261  24 23 22  - 1  - 1  901 - 1200 t r e e s h a 416 2 3 477 448 8 13 153  - 1  46 41 43 14  1501 - 1800 t r e e s h a 200 16  - 1  2701 - 3000 trees h a 14 160  - 1  35  33  density  

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