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UBC Theses and Dissertations

Restoring productivity on severely degraded forest soil in British Columbia Carr, William Wade 1985

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RESTORING PRODUCTIVITY ON SEVERELY DEGRADED FOREST SOIL IN BRITISH COLUMBIA by WILLIAM WADE CARR B.Sc., Oregon State University, June 1975 M.Sc., University of B r i t i s h Columbia, October 1977 A THESIS SUBMITTED IN PARTIAL FULFILLMENT OF THE REQUIREMENTS FOR THE DEGREE OF Doctor of Philosophy in THE FACULTY OF GRADUATE STUDIES (Department of Forestry) We accept this thesis as conforming to the reauired standard THE UNIVERSITY OF BRITISH COLUMBIA October 1985 © William Wade Carr, 1985 In presenting this thesis in partial fulfilment of the requirements for an advanced degree at the University of British Columbia, I agree that the Library shall make it freely available for reference and study. I further agree that permission for extensive copying of this thesis for scholarly purposes may be granted by the head of my department or by his or her representatives. It is understood that copying or publication of this thesis for financial gain shall not be allowed without my written permission. Department of FORESTRY The University of British Columbia 1956 Main Mall Vancouver, Canada V6T 1Y3 D A T E OCTOBF.F , / 1 Q 8 S DE-6(3/81) i i ABSTRACT F o r e s t r o a d b u i l d i n g and t i m b e r h a r v e s t i n g o p e r a t i o n s have been r e c o g n i z e d as p r i n c i p a l c a u s e s of f o r e s t s o i l d e g r a d a t i o n . These a c t i v i t i e s can r e s u l t i n a c c e l e r a t e d s o i l e r o s i o n , e x c e s s i v e s c a r i f i c a t i o n , a n d / o r i n c r e a s e d s o i l d e n s i t y , w hich may a d v e r s e l y a f f e c t s i t e p r o d u c t i v i t y . A s t u d y o f l a n d i n g a r e a s e m p h a s i z e t h e d e f i c i e n c i e s i n c u r r e n t r e h a b i l i t a t i o n g u i d e l i n e s I n c r e a s e d s o i l d e n s i t y on both summer and w i n t e r l a n d i n g s was s t i l l e v i d e n t a t 30 cm and t h e s o i l n u t r i e n t q u a l i t y was p o o r . Two f i e l d t e s t s of a g r e e n f a l l o w s y s t e m on s u b s o i l m a t e r i a l s e x p o s e d by e r o s i o n and l a n d i n g c o n s t r u c t i o n p r o v e d s u c c e s s f u l i n b u i l d i n g s i t e n u t r i e n t c a p i t a l t o a c c e p t a b l e l e v e l s . S e e d l i n g g r o w t h r e s p o n s e t o g r e e n f a l l o w c r o p e s t a b l i s h m e n t i n t h e c o a s t a l study v e r i f i e d t h e s e f i n d i n g s . A b e n e f i t - c o s t a n a l y s i s o f s e v e r a l f o r e s t s o i l r e h a b i l i t a t i o n s c e n a r i o s d e m o n s t r a t e d t h e i m p o r t a n c e of i n c l u d i n g secondary and i n t a n g i b l e f a c t o r s . From a p e c u n i a r y s t a n d p o i n t , b a s e d on p r i m a r y b e n e f i t s a n d c o s t s , r e h a b i l i t a t i o n was e c o n o m i c a l l y f e a s i b l e o n l y when a l o w s o c i a l d i s c o u n t r a t e (2%) and an o p t i m i s t i c stumpage i n c r e a s e p r o j e c t i o n ( 3 % per y e a r ) , were u s e d . A d i s c u s s i o n of some s e c o n d a r y and i n t a n g i b l e b e n e f i t s ( i . e . , h a r v e s t i n g r a t e s , i» i employment, government revenues, e r o s i o n c o n t r o l , and i n d u s t r y i m a g e ) s t r e s s e s t h e need f o r e f f e c t i v e f o r e s t s o i l r e h a b i l i t a t i o n . f V TABLE OF CONTENTS Page ABSTRACT i i LIST OF TABLES v i i ACKNOWLEDGEMENTS ,x 1.0 INTRODUCTION 1 1.1 Problem Statement 1 1.2 Objective 4 2.0 SOIL DEGRADATION DUE TO FOREST HARVESTING ACTIVITIES — AN OVERVIEW 8 -2.1 Introduction 8 2.2 The Causes of Forest Soil Degradation 8 2.2.1 The Construction of Skid Roads and Landings 9 2.2.2 Accelerated Soil Erosion 9 2.3 The Effect of Site Degradation on Soil Properties 12 2.3.1 Increased Soil Density 12 2.3.2 Removal of Surface Soil Horizons 14 2.3.3 Tree Growth and Forest Productivity 15 3.0 THE EFFECT OF LANDING CONSTRUCTION ON SOME FOREST SOIL PROPERTIES — A CASE STUDY 18 3.1 Problem Statement 18 3.2 Objective 19 3.3. Limitations 20 3.4 Study Location and Methodology 21 3.4.1 Site Description 21 3.4.2 Spatial Nature of Soil Density 22 3.4.3 Effect of Landing Construction on Soil Nutrient Content and Concentration 24 3.4.4 Effect of Landing Construction on Regeneration Performance 27 3.5 Results and Discussion 28 3.5.1 Spatial Nature of Soil Density 28 3.5.2 Effect of Landing Construction on Soil Nutrient Content and Concentration 31 Nitrogen 32 Phosphorus 35 Potassium 38 Summary of Effects on Nutrients 41 V Page 3.5.3 Effect of Landing Construction on Regenerative Performance 41 Regeneration Stocking 42 Foliar Nutrient Concentration 43 Seedling Height 46 3.6 Summary and Conclusion 47 4.0 RESTORING PRODUCTIVITY ON DEGRADED FOREST SOILS: TWO CASE STUDIES 50 4.1 Problem Statement 50 4.2 Literature Review 51 4.3 Objectives 53-4.4 Limitations 53^ 4.5 Materials and Methods 54 4.5.1 Site Description 55 Coastal Study — Koksilah 55 Interior Study — Vanderhoof 57 4.5.2 Field Sampling Procedures 59 Coastal Study — Koksilah 59 Interior Study — Vanderhoof 60 4.5.3 Laboratory Procedures 61 Coastal Study — Kokksilah 61 Interior Study — Vanderhoof 64 4.6 Results and Discussion 65 4.6.1 Site Nutrient Pools -- Koksilah 65^ Vegetative and Soil Components 65 Nutrient Totals 67 4.6.2 Site Nutrient Pools — Vanderhoof 73 Vegetative and Soil Components 73 Nutrient Totals 75 4.6.3 Regeneration Performance -- Koksilah 78 4.6.4 Regeneration Performance — Vanderhoof 80 4.6.5 Summary 82 4.6.6 Conclusion 83 5.0 SOME ECONOMIC CONSIDERATIONS OF FOREST LAND RECLAMATION 85 5.1 Introduction 85 5.2 A Benefit-Cost Approach to Forest Land Rehabilitation 87 5.2.1 Benefit-Cost Procedures for Forest Land Rehabilitation 88 5.2.2 Assumptions for Degraded and Rehabilitated Forest Soil 91 Yield Reduction Assumptions 92 vi Page Assumptions Regarding Volume Recovery Due to Rehabilitation 93 Costs of Rehabilitation 94 5.3 Benefit-Cost Analysis for Forest Land Rehabilitation Scenarios 96 5.3.1 Working Unit Description 96 Coastal Forest 96 Interior Forest 96 5.3.2 Alternative Management Plans 9 7 ^ Coastal Forest 97 Interior Forest 98 5.4 Calculation of Benefit-Cost Ratios 99 5.4.1 Coastal Forest 100^ 5.4.2 Interior Forest 101" 5.4.3 Discussion 102 5.5 Some Secondary and Intangible Benefits and Costs of Forest Land Rehabilitation 103 5.5.1 Vancouver Forest Region — Effects on Timber Harvest, Employment, and Government Revenue 104 5.5.2 Prince George Forest Region — Effects on Timber Harvest, Employment, and Government Revenue 107 5.5.3 Additional Intangible Benefits 108 5.6 Alternative Considerations in Forest Land Rehabilitation 109 5.6.1 Rehabilitation as an Operational Cost 109 5.6.2 Recovery of Lost Productivity Through Intensive Silviculture 113 5.7 Summary and Conclusions 116 6.0 CONCLUSION 118/ LITERATURE CITED 12^ APPENDICES 13^ v i i LIST OF TABLES Pa^e 1 Comparison of s o i l b u l k d e n s i t y (kg/ha) by depth f o r summer and w i n t e r l o g g i n g 29 2 I n c r e a s e i n s o i l b u lk d e n s i t y on the l a n d i n g areas as a p e r c e n t of the o f f - l a n d i n g a r e a 31 3. S o i l n i t r o g e n c o n t e n t (kg/ha) by season of l o g g i n g 33 4. S o i l N i t r o g e n c o n c e n t r a t i o n (5) by season of l o g g i n g 34 5. S o i l phosphorus c o n t e n t (kg.ha) by season of l o g g i n g 36 6. S o i l phosphorous c o n c e n t r a t i o n (ppm) by season of l o g g i n g 37 7. S o i l p o t a s s i u m c o n t e n t (kg/ha) by season of l o g g i n g 39 8. S o i l p o t a s s i u m c o n c e n t r a t i o n (ppm) by season of l o g g i n g 40 9. R e g e n e r a t i o n s t o c k i n g survey (%) 43 10. F o l i a r N, P, and K c o n c e n t r a t i o n (%) 45 11. S e e d l i n g H eight (cm) f o r a l l s t a n d s 47 12. G r a i n f a l l o w v e g e t a t i v e matter (kg/ha) — K o s i l a h 66 13. C o n c e n t r a t i o n (%) of N, P, and K i n the v e g e t a t i v e components — K o k s i l a h 67 14. S o i l N, P, and K c o n c e n t r a t i o n s — K o k s i l a h 68 15. T o t a l N, P, and K (kg/ha) p o o l s f o r t r e a t e d p l o t s --K o k s i l a h 69 16. Comparison of t o t a l N, P, and K p o o l s between t r e a t e d and c o n t r o l p l o t s 00 K o k s i l a h 71 17. Green f a l l a o w v e g e t a t i v e matter and n u t r i e n t c o n c e n t r a t i o n s (N, P, and K) -- Vanderhoof 74 Page 18. S o i l n u t r i e n t c o n c e n t r a t i o n (N, P, and K) --Vanderhoof 74 19. T o t a l N, P, and K p o o l s (kg/ha) f o r t r e a t e d p l o t s — Vanderhoof 76 20. Comparison of t o t a l N, P, and K p o o l s (kg/ha) between t r e a t e d and c o n t r o l p l o t s -- Vanderhoof 76 21. F o l i a r N, P, and K c o n c e n t r a t i o n s (%) i n D o u g l a s - f i r s e e d l i n g s -- K o k s i l a h 79 22. D o u g l a s - f i r s e e d l i n g h e i g h t (cm) -- K o k s i l a h 81 23. F o l i a r N, P, and K c o n c e n t r a t i o n (%) and h e i g h t (cm) of l o d g e p o l e p i n e s e e d l i n g s — Vanderhoof 81 Acknowledgments I am very g r a t e f u l f o r the guidance and a s s i s t a n c e p r o v i d e d by my s u p e r v i s o r y c o m m i t t e e of Dr. J.V. T h i r g o o d , D r. T.M. B a l l a r d , D r . D. H a l e y , and D r . M. P i t t , w h i c h h a s b e e n i n v a l u a b l e i n the c u l m i n a t i o n of t h i s r e s e a r c h . I am d e e p l y i n d e b t e d t o t h e B.C. M i n i s t r y o f F o r e s t s Research Branch f o r t h e i r f i n a n c i a l s u p p o r t . A s p e c i a l t h a n k s goes t o t h e f o r m e r d i r e c t o r , Mr. R a l p h S c h m i d t , f o r h i s e a r l y e n c o u r a g e m e n t and h i s e n t h u s i a s m f o r th e e n t i r e f o r e s t l a n d r e h a b i l i t a t i o n p r o g r a m . I w i s h t o thank Wordpower S e r v i c e s f o r word p r o c e s s i n g t h i s r e s e a r c h . A s s i s t a n c e i n the f i e l d e x p e r i m e n t s by B r i t i s h C o lumbia F o r e s t P r o d u c t s L t d . , T a k l a L o g g i n g , and the Vanderhoof F o r e s t D i s t r i c t i s g r e a t l y a p p r e c i a t e d . I am a l s o t h a n k f u l f o r t h e a s s i s t a n c e w i t h c h e m i c a l a n a l y s e s p r o v i d e d by Dr. and Mrs. W. Herman of P a c i f i c S o i l A n a l y s i s L t d . , Vancouver. C o n s t r u c t i v e r e v i e w s and comments of a l l o r p o r t i o n s of t h i s t h e s i s have been p r o v i d e d by Dr. P.A. Adams (Oregon S t a t e U n i v e r s i t y ) , Dr. A.A. Bomke (U.B.C.), Dr. A. F a r l e y (U.B.C.), Dr. D L o u s i e r (B.C. M i n i s t r y of F o r e s t s ) , Dr. H.P. Sims ( A l b e r t a M i n i s t r y of E n v i r o n m e n t ) , D r . R.B. S m i t h ( C . F . S . ) , a n d D r . P.F. Z i e m k i e w i c z ( A l b e r t a M i n i s t r y o f E n e r g y and N a t u r a l R e s o u r c e s ) . 1 1.0 INTRODUCTION 1.1 Problem Statement Twenty-two p e r c e n t of the t o t a l f o r e s t l a n d of Canada i s i n B r i t i s h C o l u m b i a . T h i s h i g h l y p r o d u c t i v e l a n d s u p p o r t s r o u g h l y 43 p e r c e n t by volume of Canada's me r c h a n t a b l e t i m b e r ( B r i t i s h C o lumbia R o y a l Commission on F o r e s t R e s o u r c e s , 1976). To put t h i s i n a n a t i o n a l p e r s p e c t i v e , B r i t i s h C o l u m b i a p r o d u c e s o v e r 25 p e r c e n t of Canada's p u l p , 70 p e r c e n t o f t h e l u m b e r , and o v e r 90 p e r c e n t of t h e p l y w o o d ( A s s o c i a t i o n of B r i t i s h C o lumbia P r o f e s s i o n a l F o r e s t e r s , 1980). T h i s a c c o u n t s f o r r o u g h l y h a l f of Canada's f o r e s t p r o d u c t s v a l u e , w h i c h i s g r e a t e r than t h a t of f o s s i l f u e l p r o d u c t i o n (Canada. 1981). T h u s , t h e i m p o r t a n c e of f o r e s t r y t o B r i t i s h C o l u m b i a c a n n o t be o v e r - e m p h a s i z e d . R o u g h l y 50 p e r c e n t of t h e t o t a l v a l u e of s h i p m e n t s made by B r i t i s h C o l u m b i a ' s m a n u f a c t u r i n g i n d u s t r y i s f o r e s t based ( B r i t i s h Columbia R o y a l Commission on F o r e s t R e s o u r c e s , 1976). The f o r e s t i n d u s t r y u s u a l l y p r o v i d e s a p p r o x i m a t e l y 95,000 d i r e c t j o b s a n d , u s i n g t h e g e n e r a l l y a c c e p t e d m u l t i p l i e r of two, ge n e r a t e s another 190,000 jo b s i n s u p p o r t ( R e e d , 1 9 7 3 ) . T h i s i m p l i e s t h a t f o r e s t r y d i r e c t l y a c c o u n t s f o r 8.5 p e r c e n t of t h e p r o v i n c i a l work f o r c e , or 25 pe r c e n t when i n d i r e c t employment i s i n c l u d e d . A p p r o x i m a t e l y o n e - h a l f of B r i t i s h Columbia's l a n d base, or 47 m i l l i o n h e c t a r e s , i s f o r e s t e d , w i t h 42 m i l l i o n h e c t a r e s c o n s i d e r e d a c c e s s i b l e to l o g g i n g . Of t h i s a c c e s s i b l e f o r e s t l a n d , a p p r o x i m a t e l y 7 m i l l i o n h e c t a r e s i s e x p e c t e d t o be needed f o r o t h e r uses by the year 2000 ( A s s o c i a t i o n of B r i t i s h C o l u m b i a P r o f e s s i o n a l F o r e s t e r s , 1 980). The r e m a i n i n g n e t f o r e s t l a n d base of 35 m i l l i o n h e c t a r e s must su p p o r t B r i t i s h Columbia's l a r g e s t i n d u s t r y . Over t h e p a s t d e c a d e , f o r e s t e r s and t h e f o r e s t i n d u s t r y have e x p r e s s e d g r a v e c o n c e r n o v e r t h e l o s s of p r o d u c t i v e f o r e s t l a n d through a l i e n a t i o n to o t h e r uses. The A s s o c i a t i o n of B r i t i s h C o l u m b i a P r o f e s s i o n a l F o r e s t e r s has p r e s e n t e d b r i e f s t o t h e p r o v i n c i a l g o v e r n m e n t on l a n d a l i e n a t i o n t o a g r i c u l t u r e (Nov., 1980) and e n e r g y d e v e l o p m e n t ( O c t . , 1 983). F o r m e r C h i e f F o r e s t e r , W. Young ( 1 9 8 3 ) , commented b r i e f l y on t h i s p r o b l e m a t a B.C. M i n i s t r y of A g r i c u l t u r e w o r k s h o p on s o i l d e g r a d a t i o n . D u r i n g a s p e e c h a t t h e C a n a d i a n C l u b of V a n c o u v e r ( F e b . 18, 1 9 8 3 ) , P. B e n t l e y , t h e p r e s i d e n t of Canadian F o r e s t P r o d u c t s , s a i d : We r e c o g n i z e t h e need f o r some a l i e n a t i o n of t h e f o r e s t l a n d base f o r new highways, t r a n s m i s s i o n l i n e s , and o t h e r developments t h a t o f f e r us a h i g h s t a n d a r d of l i v i n g . On t h e o t h e r h a n d , we must r e s i s t e r o s i o n f r o m t h e f o r e s t l a n d base f o r s i n g l e p u r p o s e s s u c h as p a r k s , e c o l o g i c a l r e s e r v e s , w i l d n e r n e s s a r e a s or o t h e r n o n - e s s e n t i a l p u r p o s e s . . . . E a ch h e c t a r e of f o r e s t l a n d p r o v i d e s , on an a v e r a g e , 1.8 man-years of employment and end p r o d u c t s worth $38,000. Whether we c l e a r t h a t p r o d u c t i v e a c c e p t i t i s s t a t e t h e s e views i n t h e i r e n t i r e t y or n o t , i t i s e s s e n t i a l t o m a i n t a i n t h e l a n d base i n a i f f o r e s t r y i s t o c o n t i n u e as t h e l e a d i n g 3 i n d u s t r y i n B.C. P a r a l l e l t o the c o n c e r n s s expressed about a l i e n a t i o n of f o r e s t l a n d t o o t h e r u s e s , c o n c e r n has a l s o grown r e g a r d i n g t h e l o s s of f o r e s t p r o d u c t i v i t y t h r o u g h l o g g i n g o p e r a t i o n s . W h i l e i t i s r e c o g n i z e d t h a t l o g g i n g o p e r a t i o n s c a u s e u n a v o i d a b l e d i s t u r b a n c e of v e g e t a t i o n and s o i l , p o o r l y planned or executed o p e r a t i o n s can r e s u l t i n e x c e s s i v e d i s t u r b a n c e and s i t e d e g r a d a t i o n . T h i s s i t e d e g r a d a t i o n , w h i c h t h e B.C. M i n i s t r y o f F o r e s t s ( 1 9 8 4 ) d e f i n e s as a r e d u c t i o n i n p r o d u c t i v e c a p a b i l i t y o f a s i t e t h r o u g h s o i l damage or u n a c c e p t a b l e d i s t u r b a n c e , r e p r e s e n t s a form of " i n t e r n a l " l a n d a l i e n a t i o n over which f o r e s t e r s and the f o r e s t i n d u s t r y have d i r e c t c o n t r o l . L ogging o p e r a t i o n s can d i r e c t l y and i n d i r e c t l y r e s u l t i n s i t e d e g r a d a t i o n . The r e m o v a l of s u r f a c e s o i l h o r i z o n s by c o n s t r u c t i o n a c t i v i t i e s c an s e r i o u s l y d e p l e t e s i t e n u t r i e n t c a p i t a l . I n the case of l a n d i n g s and s k i d r o a d s , the r e s i d u a l s o i l m a t e r i a l may be c o m p a c t e d , f u r t h e r r e d u c i n g s o i l p r o d u c t i v i t y . L o gging o p e r a t i o n s i n steep t e r r a i n can g r e a t l y a c c e l e r a t e s o i l e r o s i o n t h r ough mass w a s t i n g , which not o n l y d e p l e t e s s o i l n u t r i e n t c a p i t a l but o f t e n a d v e r s e l y a f f e c t s o t h e r f o r e s t r e s o u r c e s . R e c o g n i t i o n of t h e p o t e n t i a l f o r l o g g i n g o p e r a t i o n s t o b r i n g a b o u t s i t e d e g r a d a t i o n has r e s u l t e d i n a n e w l y p r o p o s e d f o r e s t r y p o l i c y : R e d u c t i o n of  S i t e D i s t u r b a n c e from Logging O p e r a t i o n s (B.C. M i n i s t r y of 4 F o r e s t s , 1984). T h i s d e f i n e s measures to r e s t r i c t the amount of s i t e d i s t u r b a n c e f r o m l o g g i n g o p e r a t i o n s and i n c l u d e s p r o v i s i o n s f o r s i t e r e h a b i l i t a t i o n measures to r e s t o r e f o r e s t p r o d u c t i v i t y . U n f o r t u n a t e l y , t h e d e v e l o p m e n t of e f f e c t i v e r e h a b i l i t a t i o n methodology f o r use on degraded f o r e s t s o i l s i n B r i t i s h C o lumbia has been l a c k i n g . R e h a b i l i t a t i o n g u i d e l i n e s e x i s t o n l y f o r l a n d i n g and s k i d r o a d a r e a s , and t h e s e have been s u b j e c t to no v e r i f i c a t i o n t e s t i n g . Much of the r e s e a r c h r e p o r t e d i n t h i s t h e s i s was c o n d u c t e d as p a r t of t h e B.C. M i n i s t r y of F o r e s t s R e s e a r c h B r a n c h ' s mandate t o d e v e l o p e f f e c t i v e r e h a b i l i t a t i o n methods and t e c h n i q u e s t o r e s t o r e s i t e p r o d u c t i v i t y on degraded f o r e s t s o i l s . 1.2 O b j e c t i v e The p r e m i s e o f t h i s t h e s i s i s t h a t s e v e r e s i t e d e g r a d a t i o n r e s u l t i n g f r o m l o g g i n g o p e r a t i o n s , o r t h e p r e v i o u s l y m e n t i o n e d " i n t e r n a l " l a n d a l i e n a t i o n , can be a l l e v i a t e d by c e r t a i n f o r e s t s o i l management p r a c t i c e s . The o b j e c t i v e i s to address t h r e e q u e s t i o n s : 1. What a r e t h e c o n s e q u e n c e s o f c e r t a i n f o r e s t h a r v e s t i n g o p e r a t i o n s f o r s o i l p r o p e r t i e s and s i t e p r o d u c t i v i t y ? 2. Can f o r e s t s o i l d e g r a d a t i o n be r e v e r s e d by c e r t a i n k i n d s of s o i l management p r a c t i c e s ? 3. I s such r e h a b i l i t a t i o n economic? 5 The a n s w e r s t o t h e s e q u e s t i o n s a r e s o u g h t t h r o u g h a c o m b i n a t i o n of l i t e r a t u r e r e v i e w and s p e c i f i c case s t u d i e s or s c e n a r i o s . However, such an approach i s s u b j e c t to p r a c t i c a l l i m i t a t i o n s which may r e s t r i c t the scope of the answers. The c a s e s t u d y u n d e r t a k e n i n a d d r e s s i n g t h e f i r s t q u e s t i o n f o c u s e s on t h e i m p a c t s of l a n d i n g c o n s t r u c t i o n a s s o c i a t e d w i t h g r o u n d - b a s e d l o g g i n g . T h i s r e p r e s e n t s not o n l y the w o r s t case of s o i l d e g r a d i n g a c t i v i t y i n h a r v e s t i n g o p e r a t i o n s , b u t a l s o o n e t h a t i s s u b j e c t t o s i t e r e h a b i l i t a t i o n g u i d e l i n e s . The r e s u l t s a r e a l s o e a s i l y a p p l i c a b l e to the c o n s t r u c t i o n of main s k i d r o a d s , which when c o m b i n e d w i t h t h e a r e a e x t e n t o f l a n d i n g s can o c c u p y up t o 35% o f c u t - o v e r a r e a s ( F r o c h l i c h , 1 9 7 9 ) . The i d e n t i f i c a t i o n of " d e g r a d a t i v e " e f f e c t s p r e s u p p o s e s k n o w l e d g e t h a t a c e r t a i n d i r e c t i o n of s o i l p r o p e r t y change i s d e t r i m e n t a l and/or t h a t an optimum v a l u e of the s o i l p r o p e r t y i s known. I n s p e c t i o n of s i t e s and r e v i e w of l i t e r a t u r e can s u g g e s t a l i s t of s o i l p r o p e r t i e s , i m p o r t a n t to s i t e p r o d u c t i v i t y , which are l i k e l y t o be a f f e c t e d by f o r e s t l a n d i n g c o n s t r u c t i o n . Comparing such p r o p e r t i e s on d i s t u r b e d and u n d i s t u r b e d s i t e s s e r v e s t o c o n f i r m or e l i m i n a t e them from the l i s t . The l i t e r a t u r e can t h e n s u g g e s t p o s s i b l e r e h a b i l i t a t i v e m e a s u r e s s p e c i f i c t o those s o i l p r o p e r t i e s t h a t r e m a i n on the l i s t . A l i s t of m e a s u r e s w h i c h a r e a p p a r e n t l y e f f e c t i v e and r e a s o n a b l y i n e x p e n s i v e c o n s t i t u t e s a c o m b i n a t i o n o f 6 a m e l e o r a t i v e t r e a t m e n t s w i t h o p e r a t i o n a l p o t e n t i a l , m e r i t i n g e v a l u a t i o n . The s e l e c t i o n of r e h a b i l i t a t i o n m e a s u r e s f o r t e s t i n g i n t h i s r e s e a r c h i s ba s e d on e x i s t i n g i n f o r m a t i o n . S i n c e n ot a l l s o i l p r o p e r t i e s a r e e v a l u a t e d , some i m p o r t a n t a s p e c t s of s o i l d e g r a d a t i o n may be o v e r l o o k e d and some e f f e c t i v e r e h a b i l i t a t i o n measure may not be sought. P r a c t i c a l l i m i t a t i o n s of f i e l d t e s t i n g r e q u i r e t h a t a t t e n t i o n be f o c u s s e d o n l y on a c o m b i n a t i o n of measures which a p p e a r p r o m i s i n g . The t e s t i n g of i n d i v i d u a l m e a s u r e s i n i s o l a t i o n i s p r o b l e m a t i c b e c a u s e a s i n g l e measure may n o t remove a l l g r o w t h l i m i t i n g f a c t o r s . I t must be remembered t h a t t h e " b o t t o m l i n e " f o r e v a l u a t i o n of a c o m b i n a t i o n of a m e l e o r a t i o n m e a s u r e s i s t h e e f f e c t on s i t e p r o d u c t i v i t y or ti m b e r y i e l d . P r o d u c t i v i t y c h a n g e s a s s o c i a t e d w i t h " d e g r a d a t i o n " and " r e h a b i l i t a t i o n " m e asured o v e r a r e l a t i v e l y s h o r t p e r i o d of j u v e n i l e t r e e growth may be p r o b l e m a t i c when e x t r a p o l a t e d over an e n t i r e s t a n d r o t a t i o n . A r e a s o n a b l e a l t e r n a t i v e f o c u s s e s on m e a s u r a b l e s o i l p r o p e r t i e s and s e e d l i n g p e r f o r m a n c e as a s u r r o g a t e f o r p r o d u c t i v i t y f o r t h e p u r p o s e s of e v a l u a t i n g r e h a b i l i t a t i v e m e a s u r e s . I n t h i s manner, t h e s h o r t - t e r m e v a l u a t i o n i d e n t i f i e s major concerns f o r the e s t a b l i s h m e n t and m a i n t e n a n c e of e a r l y p l a n t a t i o n s w h i c h a r e of o v e r w h e l m i n g importance f o r t r e e growth over the e n t i r e r o t a t i o n . The economic consequences of s o i l d e g r a d a t i o n on f o r e s t 7 land can be estimated by a s s i g n i n g a d o l l a r value to a measured l o s s of p r o d u c t i v i t y but assessing the economic f e a s i b i l i t y of rehabitation i s more complicated. Aside from the aforementioned problems of assessing "restoration" over a short time p e r i o d , the assumptions used i n an economic analyses are often paramount in the decision-making process. To some extent, this can be addressed by dealing with a range of economic assumptions rather than single values. The above r a t i o n a l e u n d e r l i e s the approach followed i n this research. It i s a p r a c t i c a l approach subject to certain l i m i t a t i o n s . A l t h o u g h t h i s a n a l y s i s of f o r e s t l a n d degradation and r e h a b i l i t a t i o n must be used c a u t i o u s l y , i t s usefulness i s not s e r i o u s l y v i t i a t e d by the l i m i t a t i o n s . O perational d e c i s i o n s i n f o r e s t r y and i n business are often based on short-term trend a n a l y s i s . The inherent r i s k s i n doing nothing while w a i t i n g (e.g., over a 60-year r o t a t i o n ) for complete data can far outweigh the risks associated with acting on the basis of preliminary r e s u l t s . 8 2 . 0 S O I L D E G R A D A T I O N D U E T O F O R E S T H A R V E S T I N G  A C T I V I T I E S - AN O V E R V I E W 2 . 1 I n t r o d u c t i o n F o r e s t r o a d b u i l d i n g a n d t i m b e r h a r v e s t i n g h a v e b e e n r e c o g n i z e d a s p r i n c i p a l c a u s e s o f f o r e s t s o i l d e g r a d a t i o n . T h e s e a c t i v i t i e s c a n r e s u l t i n a c c e l e r a t e d s o i l e r o s i o n , t h e r e m o v a l o f s u r f a c e s o i l h o r i z o n s , a n d i n c r e a s e d s o i l d e n s i t i e s w h i c h m a y r e s u l t i n a r e d u c t i o n o f t h e p r o d u c t i v e c a p a b i l i t y o f a s i t e . A l t h o u g h i t i s r e c o g n i z e d t h a t l o g g i n g o p e r a t i o n s c a u s e u n a v o i d a b l e d i s t u r b a n c e s o f v e g e t a t i o n a n d s o i l , w h e n t h e e x t e n t o f e x c e s s i v e d i s t u r b a n c e a n d s i t e d e g r a d a t i o n e x c e e d s a c c e p t a b l e l i m i t s f o r a g i v e n a r e a , e f f o r t s m u s t b e m a d e t o r e s t o r e t h e p r o d u c t i v e c a p a b i l i t y o f t h e s i t e . 2 . 2 C a u s e s o f F o r e s t S o i l D e g r a d a t i o n F o r e s t r o a d b u i l d i n g a n d t i m b e r h a r v e s t i n g o p e r a t i o n s m a y d i r e c t l y o r i n d i r e c t l y r e s u l t i n s o i l d e g r a d a t i o n . T h e c o n s t r u c t i o n o f s k i d r o a d s a n d l a n d i n g s d u r i n g g r o u n d - b a s e d t i m b e r h a r v e s t i n g c a n d i r e c t l y a f f e c t s o i l p h y s i c a l a n d c h e m i c a l p r o p e r t i e s t o t h e d e t r i m e n t o f s i t e p r o d u c t i v i t y . R o a d b u i l d i n g a n d t i m b e r r e m o v a l h a v e b e e n s h o w n t o b e p r i m a r y c a u s e s o f a c c e l e r a t e d s o i l e r o s i o n i n f o r e s t e d t e r r a i n . I n s u c h a m a n n e r , n o t o n l y c a n s i t e p r o d u c t i v i t y b e a f f e c t e d b u t n e g a t i v e i m p a c t s o n o t h e r f o r e s t r e s o u r c e s a r e o f t e n r e a l i z e d . 9 2.2.1 The C o n s t r u c t i o n of S k i d Roads and Landings I n t h e i n t e r i o r f o r e s t r e g i o n s of B r i t i s h C o l u m b i a t h e c o n v e n t i o n a l method of h a r v e s t i n g t i m b e r w i t h g r o u n d - b a s e d e q u i p m e n t n e c e s s i t a t e s t h e c o n s t r u c t i o n of s k i d r o a d s and l a n d i n g s . Based on a 1983 M i n i s t r y of F o r e s t s i n t e r n a l survey ( u n p u b l i s h e d ) , l a n d i n g a r e a s occupy an average of f o u r to f i v e p e r c e n t of c u t - o v e r l a n d and s k i d r o a d s a p p r o x i m a t e l y 16 p e r c e n t . I n s t e e p e r t e r r a i n t h e o v e r a l l e x t e n t o f t h e l a n d i n g s w i l l d e c l i n e s l i g h t l y but s k i d r o a d a r e a s can i n c r e a s e t o a t l e a s t 30 p e r c e n t , i f n o t more (McLeod & H o f f m a n , 1984; Schwab & W a t t , 1981; S m i t h & Wass, 1976; F r o e h l i c h , 1973; H a t c h e l l e t a l . , 1970). The c o n s t r u c t i o n of s k i d r o a d s and l a n d i n g s a l t e r s s o i l p h y s i c a l and c h e m i c a l p r o p e r t i e s . The d e g r e e and e x t e n t of changes i n s o i l p r o p e r t i e s due t o s o i l c o m p a c t i o n and/or the exposure of more dense s u b s o i l m a t e r i a l are o f t e n dependent on s i t e c o n d i t i o n s d u r i n g c o n s t r u c t i o n , i t s p e r i o d of o p e r a t i o n , and s o i l t y p e ( v a n d e r W e e r t , 1 9 7 4 ) . F u r t h e r m o r e , t h e r e s u l t i n g e f f e c t on s i t e p r o d u c t i v i t y i s a complex i n t e r a c t i o n b e t w e e n s o i l t y p e , t h e i m p a c t on c h e m i c a l and p h y s i c a l p r o p e r t i e s , and t r e e s p e c i e s (Greacan & Sands, 1980). 2.2.2 A c c e l e r a t e d S o i l E r o s i o n A c c e l e r a t e d w i t h b o t h r o a d s o i l e r o s i o n i n managed f o r e s t s i s a s s o c i a t e d c o n s t r u c t i o n and t i m b e r h a r v e s t i n g . The 10 r e m o v a l of s u r f a c e s o i l h o r i z o n s by a c c e l e r a t e d e r o s i o n s e r i o u s l y d e p l e t e s s i t e n u t r i e n t c a p i t a l and a l t e r s s o i l p r o p e r t i e s , t h u s a d v e r s e l y a f f e c t i n g s i t e p r o d u c t i v i t y . S u r f a c e e r o s i o n and mass w a s t i n g from roaded a r e a s i s u s u a l l y more v i s u a l and much g r e a t e r i n volume on an a r e a l b a s i s than t h a t from f a i l u r e s i n c l e a r c u t s ( S i d l e , 1980), but the i m p a c t on s i t e p r o d u c t i v i t y i s of s i m i l a r magnitude i n both c a s e s . Road b u i l d i n g i s w i d e l y r e c o g n i z e d as one of the p r i m a r y causes of a c c e l e r a t e d e r o s i o n i n managed f o r e s t l a n d ( S i d l e , 1 9 8 0 ) . S e v e r a l s t u d i e s c o n d u c t e d on f o r e s t e d s l o p e s i n t h e we s t e r n U. S. i n d i c a t e t h a t road c o n s t r u c t i o n was r e s p o n s i b l e f o r b e t w e e n 60 and 90 p e r c e n t of a l l mass f a i l u r e s . A l a n d s l i d e i n v e n t o r y c o n d u c t e d by t h e USFS i n Oregon and Washington f o l l o w i n g the 1964-65 w i n t e r f l o o d s i n d i c a t e d t h a t r o a d - r e l a t e d mass f a i l u r e s were i n v o l v e d i n a p p r o x i m a t e l y 60 p e r c e n t of t h e damage r e p o r t s ( S i d l e , 1 9 8 0). I n a s i m i l a r i n v e n t o r y c o n d u c t e d i n I d a h o , o n l y n i n e o ut of 89 l a n d s l i d e s were not r o a d a s s o c i a t e d (Megahan,1 9 8 1 ) . R e i d e t a l . (1981) c o n c l u d e d t h a t r o a d a s s o c i a t e d mass w a s t i n g was r e s p o n s i b l e f o r a p p r o x i m a t e l y 60 p e r c e n t of t h e e r o s i o n damage i n t h e C l e a r w a t e r R i v e r b a s i n of Washington. Many i n v e s t i g a t i o n s have shown a r e l a t i o n s h i p b e t w e e n f o r e s t h a r v e s t i n g and an i n c r e a s e d f r e q u e n c y of s m a l l s h a l l o w l a n d s l i d e s w i t h t i m e a f t e r l o g g i n g ( 0 ' L o u g h l i n & Z i e m e r , 1982; W i l f o r d & Schwab, 1982; Gray & Megahan, 1981; Wu & S w a n s t o n , 11 1980; Megahan et a l . , 1978; Burroughs & Thomas, 1977; Ziemer & S w a n s t o n , 1977; O ' L o u g h l i n , 1974; S w a n s t o n , 1974a, 1974b; D y r n e s s , 1967; and B i s h o p & S t e v e n s , 1964). These s t u d i e s i n d i c a t e t h a t s l o p e s t a b i l i t y on many s t e e p f o r e s t e d l a n d s depends p r i m a r i l y on r e i n f o r c e m e n t from t r e e r o o t s (O'Loughlin & Z i e m e r , 1982). The decrease i n s l o p e s t a b i l i t y and i n c r e a s e i n s o i l e r o s i o n w i t h t i m e a f t e r h a r v e s t i n g i s o f t e n a t t r i b u t e d to the decay of the r o o t component i n the s o i l m a n t l e . Both f o r e s t h a r v e s t i n g and road c o n s t r u c t i o n can i n c r e a s e the f r e q u e n c y of mass w a s t i n g on f o r e s t e d s l o p e s . A summary of r e p o r t e d mass w a s t i n g r a t e s f o r O r e g o n , W a s h i n g t o n , and south c o a s t a l B r i t i s h C olumbia found d e b r i s avalanche r a t e s on c l e a r c u t s t o be 2.2 - 3.7 and f r o m r o a d s 25.2 - 34.4 t i m e s g r e a t e r than on u n d i s t u r b e d f o r e s t s l o p e s (Swanson & Swanson, 1976). A r e c e n t s t u d y c o n d u c t e d on s t e e p t e r r a i n a t R e n n e l l Sound on t h e Queen C h a r l o t t e I s l a n d s f o u n d t h e r a t e of mass w a s t i n g f r o m r o a d s and c l e a r c u t s a v e r a g e d 15 t i m e s g r e a t e r t h a n t h a t f o u n d on f o r e s t e d t e r r a i n (Schwab, 1 9 8 2 ) . I n t h a t s t u d y , l a n d s l i d e s o c c u p i e d 6.2% of the steep t e r r a i n t h a t had been s u b j e c t t o r o a d c o n s t r u c t i o n and t i m b e r h a r v e s t i n g as compared to 0.1% i n the n a t u r a l f o r e s t . A much boader survey of l a n d s l i d e a c t i v i t y on t h e Queen C h a r l o t t e I s l a n d s by G i m b a r z e v s k i (1983) r e v e a l e d t h a t a p p r o x i m a t e l y 2% of logged t e r r a i n had been s u b j e c t t o mass w a s t i n g as opposed to 0.7% of u n l o g g e d t e r r a i n . On t h e s o u t h c o a s t of B r i t i s h C o l u m b i a , O'Loughlin (1974) observed l a n d s l i d e s t o occupy a p p r o x i m a t e l y 12 0.5% of logged t e r r a i n . Obviously the scale of mass wasting in logged terrain i s highly variable, depending on s o i l , climate, slope, and logging method. 2.3 The Effect of Site Degradation On Soil Properties 2.3.1 Increased Soil Density The influence of site degradation on many s o i l physical properties i s closely associated with increases in s o i l densities. For the most part, this increase i s a result of compactive forces exerted by construction and harvesting equipment. However, the removal of surface horizons during construction (scalping) or accelerated erosion may result in the exposure of more dense subsoil materials which exhibit t r a i t s s i m i l ar to compacted s o i l s . The increase in s o i l density is usually at the expense of soil macropores which, in turn, affect so i l a i r , water, and temperature regimes (Ruark et a l . , 1982). The impact of the increase in s o i l density w i l l be discussed in terms of soil compaction, although this may not necessarily be the causative action. Soil bulk density is the most commonly used measurement or index of s o i l compaction. However, variations in other s o i l physical conditions, for example s o i l texture or s o i l moisture, make meaningful comparisons of bulk density differences among s o i l types d i f f i c u l t . Increases in s o i l 13 bulk d e n s i t y from compaction are g r e a t e s t at the s o i l s u r f a c e and d e c l i n e r a p i d l y w i t h d e p t h . The r e p o r t e d i n c r e a s e s i n b u l k d e n s i t y i n the s u r f a c e s o i l l a y e r (0-10 cm) have ranged from 15 p e r c e n t ( S t e i n b r e n n e r & G e s s e l , 1955) to 20 p e r c e n t ( D i c k e r s o n , 1976) i n s k i d r o a d s and 50 p e r c e n t on l a n d i n g s ( P e r r y , 1964). The i n c r e a s e s on s k i d roads taper o f f q u i c k l y at the 10 to 20 cm depth (McLeod, 1983; Gent et a l . , 1983; Wert & Thomas, 1981; F r o e h l i c h , 1979; Haines et a l . , 1975). In a d d i t i o n to i n c r e a s e s i n b u l k d e n s i t y , c o m p a c t i o n s t u d i e s have q u a n t i f i e d decreases i n s o i l macropore s t r u c t u r e up to 68 p e r c e n t ( D i c k e r s o n , 1976). S i m i l a r l y , d e c r e a s e s i n a i r p e r m e a b i l i t y , w a t e r i n f i l t r a t i o n , and h y d r a u l i c c o n d u c t i v i t y have been w e l l documented. The p e r s i s t e n c e of these negative impacts on the s o i l i s q u i t e v a r i e d . Dickerson (1976) estimated the recovery period of s o i l p h y s i c a l p r o p e r t i e s i n the s k i d t r a c k to be 12 y e a r s and o n l y e i g h t y e a r s f o r the between t r a c k s o i l . Thorud and F r i s s e l (1976) found r e c o v e r y of s o i l b u l k d e n s i t y w i t h i n 8 3/4 y e a r s i n the 0 to 7.6 cm l a y e r , but no r e c o v e r y i n the 13.2 to 19.6 cm l a y e r . Wert and Thomas (1981) o b s e r v e d a r e c o v e r y of b u l k d e n s i t y i n the 0 to 15 cm l a y e r a f t e r 32 y e a r s , but no change at 20-to-30 cm. J akobsen (1983) found s i g n i f i c a n t e f f e c t s on bulk d e n s i t y and h y d r a u l i c c o n d u c t i v i t y s t i l l e v i d e n t a f t e r 32 y e a r s and P e r r y (1964) e s t i m a t e d at l e a s t 40 y e a r s were r e q u i r e d f o r the r e c o v e r y of l o g d e c k s . The magnitude and l o n g e v i t y of the n e g a t i v e i m p a c t s of s o i l 14 compaction have a great influence on tree growth and si t e productivity. 2.3.2 Removal of Surface Soil Horizons The removal of surface s o i l horizons, whether i t be the organic horizon (forest floor) only or down through the B or C, d r a s t i c a l l y affects the functions of s o i l . The forest floor protects and maintains surface s o i l structure which controls water and air movement in the s o i l . It also plays an important part in the modification of s o i l temperature. In conjunction with the A and B horizons, i t provides both habitat and food source for s o i l macro- and microorganisms (Ballard, 1980b). And l a s t l y , the importance of the surface horizons on site nutrient capital cannot be overstated. In a review of s o i l aeration, Cannell (1977) addresses the influence of increased soi l density and reduced porosity on s o i l chemical and b i o l o g i c a l a c t i v i t y . Reduced s o i l aeration due to compaction decreases root respiration and microbial a c t i v i t y . Poor aeration, as well as lower s o i l penetrability, have also resulted in decreases of mycorrhizal growth and penetration (Skinner & Bowen, 1974; Mitchell et al . , 1982). A key factor affecting tree nutrition i s the removal of nutrient r i c h organic and surface horizons that often accompanies logging activity and/or accelerated soil erosion. 15 The importance of surface s o i l horizons on s i t e nutrient capital is demonstrated in studies by Cole et a l . (1967) and Turner and Singer (1976), among others. The importance to tree nut r i t i o n of even thin organic horizons i s further demonstrated by Cole et a l . (1974) and Kimmins and Hawkes, (1978). Herring and McMinn (1980), studying s i t e preparation, attributed regeneration nutrient problems to the removal of organic matter during scarification. 2.3.3 Tree Growth and Forest Productivity S o i l degradation due to forest harvesting a c t i v i t i e s results in the reduction of the capacity of a site to produce commercial timber. The establishment, development, and growth rate of commercial species are adversely affected by increases in s o i l density and the removal of surface soi l horizons. The magnitude of this impact i s dependent on the extent of the affected area and degree of disturbance, s o i l type, and tree species (Halverson & Zisa, 1982; Cannell, 1977). Increases in s o i l density affect s o i l strength and aeration which influence seedling establishment, development, and growth rate. Although the effects of s o i l strength (normally directly related to bulk density) and s o i l aeration are d i f f i c u l t to separate, several studies define c r i t i c a l values for bulk density above which root growth and development are affected. Bulk densities above 1,400 kg/m^ 16 r e s t r i c t l o b l o l l y pine root growth, branching, and p e n e t r a t i o n (Gent et a l . , 1983; M i t c h e l l et a l . , 1982). H i l d e b r a n d (1983) found d e n s i t i e s of 1,250 kg/m^ i n loamy s o i l s hindered root p e n e t r a t i o n and development of beech s e e d l i n g s , with a d e n s i t y of 1,350 kg/m^ h a l t i n g r o o t g rowth. Minko (1975) c l a i m s 1,500 kg/m^ to be a c r i t i c a l d e n s i t y f o r r a d i a t a p i n e growth i n a s i l t y - c l a y n u r s e r y s o i l , w i t h i m p r o v e d s e e d l i n g h e i g h t and r o o t development as the s o i l d e n s i t y approached 1,200 kg/m3. H e i l m a n (1981) d e m o n s t r a t e d a d e c l i n e i n D o u g l a s - f i r s e e d l i n g root p e n e t r a t i o n i n loam and sandy loam s o i l s as the bulk d e n s i t y i n c r e a s e d from 1,330 to 1,770 kg/m3} w i t h a maximum of 1,730 to 1,830 kg/m^. A l t h o u g h s e e d l i n g s can e s t a b l i s h and grow i n s o i l s w i t h h i g h d e n s i t y , t h e i r development i s g r e a t l y r e t a r d e d . A r e d u c t i o n i n t r e e growth r a t e o b s e r v e d on the s c o u r p o r t i o n s of l a n d s l i d e a r e a s may r e s u l t from the exposure of more dense s u b s o i l m a t e r i a l s and the l o s s of s u r f a c e s o i l h o r i z o n s ( M i l e s et a l . , 1984; Sm i t h et a l . , 1983; Mark et a l . , 1964). Regeneration delays and reduced s t o c k i n g l e v e l s have been reported i n c o n j u n c t i o n with i n c r e a s e s i n s o i l d e n s i t y due to compaction (Wert & Thomas, 1981; Smith & Wass, 1979; H a t c h e l l et a l . , 1970; and S t e i n b r e n n e r & G e s s e l , 1955). The r e p o r t e d e s t i m a t e s of volume r e d u c t i o n on s k i d r oads range from 45 p e r c e n t a f t e r 26 y e a r s ( P e r r y , 1964) to 74 p e r c e n t and 80 p e r c e n t a f t e r 32 y e a r s (Wert & Thomas, 1981; J a k o b s e n , 1983, 17 r e s p e c t i v e l y ) . Volume r e d u c t i o n e s t i m a t e s pro-rated over the e n t i r e c u t - o v e r a r e a a r e 11.8 p e r c e n t (Wert & Thomas, 1981) and 12-15 p e r c e n t ( S m i t h & Wass, 1979). Not o n l y are l o w e r growth r a t e s , r e g e n e r a t i o n d e l a y s , and reduced s t o c k i n g l e v e l s i n c u r r e d on a r e a s s u b j e c t to a c c e l e r a t e d e r o s i o n or mass w a s t i n g , b u t t h e u p p e r p o r t i o n s of s l i d e a r e a s may be c o n s i d e r e d n o n - s t o c k a b l e due to i m p e n e t r a b l e or u n s t a b l e s u b s t r a i t ( M i l e s et a l . , 1984: S m i t h et a l . , 1983). Such a r e a s may be l o s t from c o m m e r c i a l t i m b e r p r o d u c t i o n f o r an extended p e r i o d of time. 18 3.0 THE EFFECT OF LANDING CONSTRUCTION ON SOME FOREST SOIL PROPERTIES — A CASE STUDY 3 .1 Problem Statement The conventional method of timber harvesting in the i n t e r i o r forest regions of B r i t i s h Columbia i s with ground-based equipment, such as t r a c t o r s or skidders. This necessitates the construction of landing areas and skid roads, which by altering so i l characteristics, can adversely affect future productivity. Most of the l i t e r a t u r e on disturbance consequences of ground-base logging is from U.S., New Zealand, and Aust r a l i a , which concentrates on skid roads and their impact on such s o i l physical properties as bulk density and associated soi l characteristics. Only one paper by Hatchell et a l . (1970) mentions the log-deck or landing. The effect on s o i l nutrient levels i s b r i e f l y discussed in papers by Smith and Wass (1979), Youngberg (1959), and Greacen and Sands (1980), but not quantified. Yet, such studies provide the data base and rationale for the Ministry of Forests landing and skid road rehabilitation guidelines. At present, a l l the i n t e r i o r f o r e s t regions have recommended rehabilitation guidelines applicable to landings and main skid roads. These generally c a l l for s o i l decompaction to a depth of 30 cm and replacement of removed topsoil. However, there has been no documentation in British 19 Columbia of the depth of compaction on these areas nor that 30 cm i s an adequate r i p p i n g depth. F u r t h e r , both past and present landing c o n s t r u c t i o n p r a c t i c e s make replacement of top s o i l nearly impossible. S o i l development in the i n t e r i o r regions of B r i t i s h Columbia i s r e s t r i c t e d i n depth, and the removal and s t o c k p i l i n g of a t h i n l a y e r of t o p s o i l with c u r r e n t equipment i n the presence of stumps and other vegetation i s often i m p r a c t i c a l . Therefore not u n l i k e most mined land r e c l a m a t i o n , s u b s o i l w i l l normally be the base material from which s i t e productivity may be recovered. A case study was conducted i n B r i t i s h Columbia to determine the nature of the r e s i d u a l s o i l m a t e r i a l a f t e r landing construction. Such data would be applicable to main skid roads. S o i l physical and chemical data were collected to s e r v e as a b a s i s f o r the d e v e l o p m e n t of e f f e c t i v e r e h a b i l i t a t i o n management p r a c t i c e s . A d d i t i o n a l l y , i n f o r m a t i o n regarding c o n i f e r regeneration was collected to a s s e s s the impact of l a n d i n g c o n s t r u c t i o n on f o r e s t productivity. 3.2 Objective The o b j e c t i v e of t h i s p r o j e c t was to gather baseline i n f o r m a t i o n regarding the impact of landing c o n s t r u c t i o n on s o i l properties and regeneration performance. These data are i m p o r t a n t to the d e v e l o p m e n t of e f f e c t i v e l a n d i n g 20 r e h a b i l i t a t i o n guidelines and for the proper c l a s s i f i c a t i o n of such areas i n the f o r e s t inventory system. The f o l l o w i n g three groups of information were collected from landings and adjacent areas for comparative analysis: 1. s p a t i a l nature of s o i l density; 2. effect on s o i l nutrient content and concentration 3. effect on regeneration performance. 3.3 Limitations As mentioned previously, the effect on s i t e productivity t h a t r e s u l t s from i n c r e a s e d s o i l d e n s i t y i s a complex interaction between s o i l type, the impact on s o i l chemical and physical properties, and tree species. In order to accomplish the o b j e c t i v e of t h i s study, s o i l type and tree species were selected so as to be constant throughout the project. Only one s o i l type was studied due to cost r e s t r a i n t . Lodgepole pine ( P i n u s £ o^n _t C) _r_t a_)_ was the only c o m m e r c i a l s p e c i e s t h a t regenerated w i t h i n the study area i n adequate numbers for performance comparison on compacted s o i l s . This removed confounding f a c t o r s from the study, but now l i m i t s the a p p l i c a b i l i t y of these r e s u l t s to other areas. However, the r e s u l t s and general conclusions from t h i s p r o j e c t should as s i s t in the development of e f f e c t i v e landing r e h a b i l i t a t i o n g u i d e l i n e s throughout the i n t e r i o r regions and promote a 21 greater awareness of the effect of ground-based logging on future site productivity. 3. 4 Study Location and Methodology To accomplish the objectives within the limited budget, a homogeneous plateau in the Prince George Forest Region was chosen as the study area. Six cut-blocks of similar pre-logging stand composition and timber y i e l d acted as experimental units. These stands, within the same soil type and ecosystem unit classification, were stratified by season of logging (summer or winter). Each cut-block had at least four landing areas which were of full-bench construction. An additional requirement of the experimental units was that the age of the stands within the season of logging strata be parallel. In this case, stand ages (years post-logging) were chosen .as one, s i x , and eleven years post-1ogging. This helped remove the confounding influence of changes in logging equipment over time and would allow for some general stand comparison regarding regeneration performance. 3.4.1 Site Description The study area was located approximately 40 km northwest of Prince George near Mossvale. The cutblocks chosen for study are bound by Bugle Lake and Mossvale Lake to the north, and Lamb Lake and Twin Bay Lake to the south. The area 22 c o o r d i n a t e s a r e 1 2 3 ° 30' (±2')W and 5 4 ° 225' (±5')N. Located on the Nechako P l a i n of the I n t e r i o r P l a t e a u ( H o l l a n d , 1964), the parent m a t e r i a l i s a g r a v e l l y g l a c i o f l u v i a l deposit w i t h a sandy loam-loamy sand t e x t u r e . F a r s t a d and L a i r t , (1954) c l a s s i f i e d t h i s area as part of the C h i l a k o Stony Sandy Loam complex. A more r e c e n t s o i l c l a s s i f i c a t i o n ( C o t i c et a.l., 1976) i d e n t i f i e s the area as a Degraded D y s t r i c B r u n i s o l ( p r o b a b l y Eena or D e s e r t e r S e r i e s ) . The e q u i v a l e n t i n the USDA C l a s s i f i c a t i o n (1978) i s a D y s t r o c h r e p t or C r y o c h r e p t . The area l i e s w i t h i n the Sub-boreal Spruce B i o g e o c l i m a t i c zone ( K r a j i n a , 1965) and was r e c e n t l y c l a s s i f i e d by McLeod and DeLong (1984) as a SBSe2-05 or Submesic P i n e - F e a t h e r moss ec o s y s t e m u n i t . Unlogged s t a n d s a r e a complex of P i n u s £L2.Lt£_I_tii - M c e a _g_l. a^ u. _c a. x iLIL_8.iL2. B JL JUL A - Xii££iJliJi.5_, membranaceum - Cornus canadensis - Pleurozium s c h r e b e r i . The m o i s t u r e r egime i s s u b m e s i c - m e s i c and the n u t r i e n t r egime s u b m e s o t r o p h i c - m e s o t r o p h i c . Timber volumes i n t h i s a r e a a v e r a g e 350 m^/ha. The l a n d i n g s a v e r a g e d 0.4 ha i n s i z e , which i s t y p i c a l f o r t h i s r e g i o n . 3.4.2 S p a t i a l Nature of S o i l Density A d i f f e r e n c e i n s o i l b u l k d e n s i t y b e t w e e n p a i r e d o b s e r v a t i o n s p o i n t s w i t h i n the s i x c u t - b l o c k s was chosen to i n d i c a t e s o i l d egradation. One p a i r of ob s e r v a t i o n s was taken at each l a n d i n g . The point of measurement w i t h i n the la n d i n g 23 was randomly s e l e c t e d from the p o r t i o n of the l a n d i n g midway between the l a n d i n g c e n t r e and o u t e r edge. The o f f - l a n d i n g measurement was t a k e n 15-20 m f r o m t h e o u t e r edge of t h e l a n d i n g , on t h e same l i n e f r o m t h e p l o t c e n t r e as t h e i n s i d e p o i n t . C a r e was t a k e n t o a v o i d s k i d r o a d s f o r t h e o u t s i d e m e a s u r e m e n t . B u l k d e n s i t y d e t e r m i n a t i o n was made w i t h a s i n g l e p r o b e n u c l e a r d e n s i o m e t e r (MC-1, C a m p b e l l P a c i f i c N u c l e a r C o r p o r a t i o n ) . To a s s e s s t h e s p a t i a l n a t u r e of s o i l c o m p a c t i o n on l a n d i n g a r e a s , d e n s i t y measurement were taken a t t h r e e probe d e p t h s ( 1 0 , 20, and 30 cm) w h i c h r e s u l t e d i n an i n t e g r a t e d a v e r a g e d e n s i t y o v e r t h a t d e p t h (0-10 cm, 0-20 cm, and 0-30 cm). To c a l c u l a t e t h e d e n s i t y o v e r t h e p r o b e d e p t h , t h r e e r e p l i c a t e r e a d i n g s ( o r r a d i a t i o n c o u n t s ) were t a k e n a t 1 2 0° i n t e r v a l s around the probe. A s o i l m o i s t u r e r e a d i n g was taken w i t h each d e n s i t y measure to a l l o w f o r s o i l d e n s i t y c o r r e c t i o n i n t o a d r y w e i g h t b a s i s . The s o i l d e n s i t y and m o i s t u r e d a t a were t h e n used i n s t a n d a r d c a l i b r a t i o n e q u a t i o n s , d e v e l o p e d f o r t h i s d e n s i o m e t e r and probe d e p t h , t o c a l c u l a t e s o i l b u l k d e n s i t y . To b e t t e r understand the e f f e c t of s o i l c o m p a c t i o n w i t h s o i l d e p t h , t h e d e n s i t y of t h r e e l a y e r s (0-10 cm, 10-20 cm, and 20-30 cm) was c a l c u l a t e d a l g e b r a i c a l l y . A s i n g l e f a c t o r a n a l y s i s of v a r i a n c e ( l a n d i n g v e r s u s o f f -l a n d i n g s o i l d e n s i t y ) w i t h t h r e e r e p l i c a t i o n s was performed on the summer and w i n t e r - l o g g e d stands f o r the 0-30 cm p r o f i l e , 24 as w e l l as t h e i n d i v i d u a l l a y e r s . A n a l y s i s of v a r i a n c e (ANOVA) was a l s o p e r f o r m e d on t h e i n c r e a s e or change i n s o i l d e n s i t y due t o l a n d i n g c o n s t r u c t i o n t a k e n as a p e r c e n t a g e of t h e o f f - l a n d i n g b u l k d e n s i t y ( s i n g l e f a c t o r -- s e a s o n of l o g g i n g , t h r e e r e p l i c a t i o n s ) . 3.4.3 E f f e c t of Landing C o n s t r u c t i o n on S o i l N u t r i e n t Content  and C o n c e n t r a t i o n The s o i l n u t r i e n t s t a t u s ( c o n t e n t and c o n c e n t r a t i o n ) of n i t r o g e n (N), phosphorus ( P ) , and p o t a s s i u m (K) was d e t e r m i n e d f o r t h e l a n d i n g and o f f - l a n d i n g a r e a i n e a c h c u t - b l o c k . The p a i r e d o b s e r v a t i o n s ( l a n d i n g and o f f - l a n d i n g ) were t a k e n a t t h e f o u r l a n d i n g s s e l e c t e d f o r t h e b u l k d e n s i t y s e c t i o n . Two s o i l s u b s a m p l e s were t a k e n a t e a c h l a n d i n g and o f f - l a n d i n g a r e a . The s e l e c t i o n of s a m p l i n g p o i n t s used a p r o c e d u r e s i m i l a r t o t h a t d e s c r i b e d i n S e c t i o n 3.4.2 These s a m p l i n g p o i n t s would l a t e r s e r v e as p l o t c e n t e r s f o r the r e g e n e r a t i o n assessment. S o i l samples w i t h i n the l a n d i n g were taken to a depth of 30 cm u s i n g a 5 - c m - d i a m e t e r c o r e r . S a m p l e s were s t o r e d i n p l a s t i c bags f o r t r a n s p o r t a t i o n . P r o c e d u r e s used f o r n u t r i e n t a n a l y s i s of o r g a n i c m atter d i f f e r from those f o r m i n e r a l s o i l , so the p r o f i l e sample f o r the o f f - l a n d i n g a r e a was s e p a r a t e d i n t o two components, o r g a n i c and m i n e r a l . The o r g a n i c h o r i z o n s a m p l e was t a k e n u s i n g a c u t t i n g r i n g 7.6 cm i n d i a m e t e r and 4.0 cm deep. T h i s sample was always taken to a c o n s t a n t depth 25 and a w e i g h t c o r r e c t i o n f o r m i n e r a l c o n t e n t was made l a t e r ( s e e b e l o w ) . N e x t , a s o i l s a m p l e t o a d e p t h of 26 cm was taken of the r e m a i n i n g p r o f i l e . The sub-samples were bagged s e p a r a t e l y and l a b e l l e d so t h a t r e c o n s t r u c t i o n of the n u t r i e n t p r o f i l e c o u l d be made a f t e r a n a l y s i s . Data comparison was to be based on t h e t o p 30 cm o f r o o t i n g medium, r a t h e r t h a n t h e top 30 cm of m i n e r a l s o i l . Sample p r e p a r a t i o n and a n a l y s i s were conducted a t P a c i f i c S o i l A n a l y s i s I n c . , V a n c o u v e r . S o i l s a m p l e s were a i r - d r i e d f o r at l e a s t 24 h o u r s , s e p a r a t e d i n t o c o a r s e (_> 2mm) and f i n e (< 2mm) f r a c t i o n s , and weighed. The f i n e f r a c t i o n was used i n the c h e m i c a l a n a l y s e s . The o r g a n i c h o r i z o n samples were oven-d r i e d a t 80°C f o r 24 h o u r s , w e i g h e d , and gro u n d i n a W i l e y M i l l f i t t e d w i t h a 1-mm s i e v e . T h i s m a t e r i a l was t h e n a n a l y z e d f o r n i t r o g e n , phosphorus, and p o t a s s i u m c o n t e n t . A l l l a b o r a t o r y a n a l y s i s p r o c e d u r e s were b a s e d on t h e Methods M a n u a l — P e d o l o g y L a b o r a t o r y , D e p a r t m e n t o f S o i l S c i e n c e , U.B.C. ( L a v k u l i c h , 1978) e x c e p t where n o t e d . The f o l l o w i n g a n a l y s e s were performed: s o i l pH: d e t e r m i n e d i n 0.01 M C a C l 2 u s i n g a c o m b i n a t i o n e l e c t r o d e pH meter; t o t a l s o i l u s i n g a s e m i - m i c r o K j e h d a l d i g e s t n i t r o g e n : w i t h c o l o r i m e t r i c d e t e r m i n a t i o n u s i n g a T e c h n i c o n a u t o a n a l y z e r ; a v a i l a b l e s o i l u s i n g the Bray P - l method; phosphorus: 26 available so i l potassium using a Morgan's extraction (1.0 N NaOAc) in conjunction with atomic absorption; organic horizon N, P. K: using a Caro's acid digest with N and P c o l o r i m e t r i c a l l y determined on a Technicon autoanalyzer and K measured by atomic absorption. An additional step was taken to correct the organic horizon weight for mineral pa r t i c l e s that may have been incorporated during sampling. This procedure was similar to that used by Kimmins and Hawkes (1978). A 1.000 g sub-sample from each milled organic horizon sample was dry-ashed, the residual material weighed, and the percentage calculated. This residual percentage, less 10%, was assumed to be mineral par t i c l e s and the o r i g i n a l sample mass was corrected to an organic matter mass basis. The choice of 10% was based on experience at the P.S.A.I, laboratory with organic samples (pers. comm. W. Herman, 1984). Analysis of variance (two factor: summer versus winter logging and off-landing versus landing area, with three replications) was performed on both the nutrient content and concentration data. Comparisons were based on the top 30 cm of rooting medium, which in the case of the off-landing area was 4 cm of forest floor and 26 cm of mineral s o i l . S o i l nutrient concentration for the off-landing areas was based on the weighted average, by depth, of the concentration of the forest floor and the mineral soi l layer. 27 3.A.4 Effect of Landing Construction on Regeneration  Performance The paired observation points used in Section 3.4.3 served as centres for paired observation plots to assess regeneration performances on the 6- and 11-year-old cut-blocks. Stocking assessment was based on standard Ministry of Forests procedures. The plot size was 50 m^  and the target stocking was 1,200 well-spaced trees per hectare (or 6 well-spaced trees per plot at 2.87 m inter-tree spacing). A l l well spaced trees had to be of acceptable quality and capable of becoming a crop tree. The height of the five largest, well-spaced lodgepole pine in each plot was measured to the nearest 0.5 cm, and a composite sample of current year's foliage was taken from the upper one-quarter of each measured tree. Foliage nitrogen, phosphorus, and potassium concentrations were determined using a Caro's acid digest with nitrogen and phosphorus determined co1orimetrica 11y on a Technicon autoanalyzer and potassium measured by atomic absorption ( B a l l a r d , 1980). Because of the low number of natural regenerated spruce (Picea glauca) on the landings, only lodgepole pine were selected for height growth and f o l i a r analysis. The regeneration performance data was analyzed on a stand basis. A single factor AN0VA (landing versus off-landing) with four replicates (based on two subsamples) was performed. 28 The v a l u e f o r each r e p l i c a t e was t h e a v e r a g e of t h e two subsamples. Only g e n e r a l o b s e r v a t i o n s r e g a r d i n g the e f f e c t s of s e a s o n of l o g g i n g o r s t a n d age were p o s s i b l e i n t h i s s e c t i o n . 3 . 5 R e s u l t s and D i s c u s s i o n 3.5.1 S p a t i a l Nature of S o i l D e n s i t y The s o i l b u l k d e n s i t y d a t a f o r t h e two s e a s o n s of l o g g i n g i s p r e s e n t e d i n T a b l e 1 f o r the 0-30 cm p r o f i l e depth as w e l l as t h e c a l c u l a t e d l a y e r s . A n a l y s i s - o f - v a r i a n c e i n d i c a t e s a s i g n i f i c a n t i n c r e a s e i n s o i l d e n s i t y due t o l a n d i n g c o n s t r u c t i o n f o r both summer and w i n t e r l o g g i n g at a l l depths ( A p p e n d i x A ) . The w i n t e r - 1 o g g e d s t a n d s e x h i b i t e d a v a r i a b i l i t y i n b o t h t h e l a n d i n g and o f f - l a n d i n g e s t i m a t e s w h i c h c o u l d a c c o u n t f o r t h e l o w e r l e v e l of p r o b a b i l i t y i n d e t e r m i n i n g a s i g n i f i c a n t d i f f e r e n c e . The presence of h i g h e r s o i l d e n s i t y l e v e l s i n the 20-30 cm l a y e r f o r both seasons of l o g g i n g a g r e e s w i t h s t u d i e s by Wert and Thomas ( 1 9 8 1 ) , F r o c h l i c h ( 1 9 7 9 ) , and Power ( 1 9 6 4 ) . T h i s w o u l d s u g g e s t t h a t t h e d e p t h o f d e c o m p a c t i o n o r r i p p i n g d u r i n g l a n d i n g r e h a b i l i t a t i o n a c t i v i t i e s s h o u l d exceed 30 cm and may need to be more i n t h e r a n g e of 40 t o 50 cm. F.R.I. (1977) and P o t t e r and Lamb (1975) recommend r i p p i n g t o a 40 t o 50 cm d e p t h i n compacted s o i l f o r improved s e e d l i n g s u r v i v a l . 29 TABLE 1 C o m p a r i s o n of s o i l b u l k d e n s i t y ( k g / h a ) by d e p t h f o r summer and w i n t e r l o g g i n g Area Depth (cm) 0-10 10-20 20-30 0-30 O f f - l a n d i n g L a nding Summer Logging 860+30C 1 ) 1170±30 1630±40 (2) 1930±20 1290±30 1820±20 1100±30 1730±30 *** W i n t e r Logging O f f - l a n d i n g L a nding 8301170 13801150 11501120 1550+100 13001110 16201110 1090+120 15101100 1. V a l u e s a r e means +SE of t h r e e r e p l i c a t i o n s w i t h f o u r subsamples. 2. * * * and * d e n o t e s i g n i f i c a n t d i f f e r e n c e a t t h e 99% and 90% l e v e l s of p r o b a b i l i t y , r e s p e c t i v e l y . 30 The i n c r e a s e i n s o i l d e n s i t y f o r the o v e r a l l p r o f i l e (0-30 cm) was g r e a t e r i n t h e su m m e r - l o g g e d a r e a s ( T a b l e 2 ) . S t a t i s t i c a l a n a l y s i s r e v e a l e d t h i s to be the case i n the 10-20 cm and 20-30 cm l a y e r s , w h i l e t h e i n c r e a s e i n t h e 0-10 cm l a y e r d i d not d i f f e r s i g n i f i c a n t l y f o r w i n t e r and summer l o g g i n g ( A p p e n d i x B ) . The d e g r e e of i n c r e a s e d s o i l d e n s i t y d e c l i n e s w i t h d e p t h f o r b o t h s e a s o n s of l o g g i n g , but more r a p i d l y so f o r t h e w i n t e r l o g g i n g . D u r i n g w i n t e r l o g g i n g , snow may r e d u c e c o m p a c t i v e f o r c e s f r o m heavy e q u i p m e n t and f r o z e n s o i l c o n d i t i o n s c a n i n c r e a s e t h e r e s i s t a n c e t o c o m p a c t i o n . A d d i t i o n a l l y , s u c h a c o m b i n a t i o n of c o n d i t i o n s c o u l d a l l e v i a t e t h e need f o r deep s c a l p i n g of t h e s o i l t o p r o v i d e a f i r m o p e r a t i n g s u r f a c e f o r t h e l o g g i n g e q u i p m e n t . T h i s l a t t e r f a c t o r appears to c o n t r i b u t e t o the l o w e r i n c r e a s e i n s o i l d e n s i t y on the w i n t e r - l o g g e d a r e a s f o r the d e n s i t y of the 0-10 cm l a y e r w i t h i n the l a n d i n g i s e q u i v a l e n t t o the 20-30 l a y e r o u t s i d e the l a n d i n g (Table 1). The l o w e r i n c r e a s e i n s o i l d e n s i t y due t o w i n t e r l o g g i n g w i t h i n t h e s t u d y a r e a agrees w i t h r e s u l t s from w i n t e r l o g g i n g i n M i n n e s o t a (Mace and W i l l i a m s , 1971). A l t h o u g h t h e summer l a n d i n g s were s u b j e c t t o a g r e a t e r i n c r e a s e i n s o i l d e n s i t y t h a n w i n t e r l a n d i n g s , b o t h have o v e r a l l d e n s i t i e s (0-30 cm) g r e a t e r t h a n 1500 kg/m^. As d i s c u s s e d i n Chapter 2, s o i l b u l k d e n s i t i e s g r e a t e r than 1300 t o 1400 kg/n_3 have been shown t o be c r i t i c a l l e v e l s f o r r o o t 31 TABLE 2 I n c r e a s e i n s o i l b u l k d e n s i t y on the l a n d i n g a r e a as a p e r c e n t of the o f f - l a n d i n g a r e a Season of Logging 0-10 Depth (cm) 10-20 20-30 0-30 Summer 89110C1) 53±6 43±5 62±4 Win t e r 66±23 36±5 * ( 2 ) 26±2 39±8 1. V a l u e s a r e means ±SE of t h r e e r e p l i c a t i o n s w i t h f o u r subsamples. 2. * and ** denote s i g n i f i c a n t d i f f e r e n c e at the 90% and 95% l e v e l s of p r o b a b i l i t y , r e s p e c t i v e l y . g r o w t h and d e v e l o p m e n t of c e r t a i n t r e e s p e c i e s . T h e r e f o r e , w h i l e summer l a n d i n g s were s u b j e c t t o a g r e a t e r i n c r e a s e i n s o i l d e n s i t y t h a n w i n t e r l a n d i n g s i n b o t h c a s e s i n c r e a s e d d e n s i t y l e v e l s t h a t can a d v e r s e l y a f f e c t s e e d l i n g r o o t growth and e v e n t u a l s i t e p r o d u c t i v i t y . 3.5.2 E f f e c t of Lan d i n g C o n s t r u c t i o n on S o i l N u t r i e n t  Content and C o n c e n t r a t i o n S t a n d a r d l a n d i n g c o n s t r u c t i o n p r a c t i c e s i n the study area i n v o l v e t h e d i s p l a c e m e n t of t h e f o r e s t f l o o r and s u r f a c e 32 mineral s o i l (at least to 20 cm in depth) to create a firm operating surface for equipment. Since the stockpiling and recovery of this nutrient-rich so i l material is impractical in most locations (at least for present construction practices and typical s o i l conditions), the residual so i l material has to be the basis for any future forest productivity. In this section, the effect of s o i l displacement (scaling) during landing construction on s o i l nutrient content (to a depth of 30 cm) and nutrient concentration was investigated. When dealing with the s o i l nutrient content data, i t must be remembered that the landing areas contain more soil mass per unit volume (62% and 39% for summer and winter landings, respectively), albeit of poorer quality, than off-landing areas. Due to high s o i l density, the a v a i l a b i l i t y for tree use of this nutrient pool may be limited. The data regarding the quality of residual s o i l material on an equal mass basis (percent concentration) may be of greater importance to landing r e h a b i l i t a t i o n since most r e h a b i l i t a t i o n measures include decompaction. Nitrogen Soil nitrogen content and concentration for landing and o f f - l a n d i n g areas are presented in Tables 3 and 4, respectively. Statistical analysis for the effect of landing construction on nitrogen content indicates no si g n i f i c a n t 33 difference between landing and off-landing areas (Appendix C). However there was a s i g n i f i c a n t decrease in nitrogen concentration due to landing construction (Appendix D). Landing construction resulted in the removal of the forest f l o o r , which accounted for 15% of the winter, and 20% of the TABLE 3 Soil nitrogen content (kg/ha) by season of logging Off-landing area Season Landing area (1) (2) 0-4 cm 4-30 cm Total 0-30 cm (3) (4) Summer 250±60 1401±80 1660±60 ns 1450±60 Winter 340±70 14001200 1740±270 ns 17101330 1. Total N from Caro's acid digest, weight corrected. 2. Total so i l N. 3. Values are means 1SE for three replications of four subsamples. 4. ns denotes no significant difference between off-landing and landing totals. 34 TABLE 4 Soil nitrogen concentration (%) by season of logging Off-landing area Season Landing area (1) 0-4 cm (2) 4-30 cm 0-30 cm Summer (A) 0.361 ±.158 0.060±.001 0.099 ±.020 *** 0.037 ±.003 Winter 0.569±.213 0.078±.007 0.144±.034 *** 0.053±.012 1. Total N from Caro's acid digest. 2. Total soi l N concentration. 3. Weighted average by depth 4. Values are means ±SE for three replications with four samples. 5. *** denotes a significant different at 99% level of probability between off-landing average and landing estimate. summer-logged areas' nitrogen pool, and the exposure of mineral s o i l with lower nitrogen content. The impact of scalping was offset by the increase in s o i l density of the residual so i l on the landing. Assuming that the off-landing area has s u f f i c i e n t nitrogen content for commercial forest 35 production, i t could be assumed that the same holds true for the landing. However, the increase in resistance to root penetration and decrease in s o i l aeration due to higher s o i l density in the landing would seem to limit the accessibility of the 0- to 30-cm layer's nitrogen content which may impede tree growth. The use of s o i l decompaction measures during landing rehabilitation to alleviate the problems associated with high s o i l density would induce a corresponding decrease in s o i l nitrogen content in the "new" (less compact) 0- to 30-cm layer. Reduced tree growth could be expected on decompacted landings due to lower nitrogen content in this root accessible s o i l layer. This appears to be the case in the studies by Hatchell (1981) and Berg (1975) where f e r t i l i z e r additions to ripped skid roads resulted in a further increase in seedling height growth. Landing r e h a b i l i t a t i o n measures may need to deal with both soi l physical properties and s o i l f e r t i l i t y i f f u l l recovery of site productivity is desired. Phosphorus So i l phosphorus content and concentration data are presented in Tables 5 and 6, respectively. S t a t i s t i c a l analysis confirms a highly s i g n i f i c a n t decrease in the s o i l phosphorus content of landing areas due to scalping construction and operation (Appendix E). Unlike the s o i l nitrogen content, the increase in s o i l density was not enough 36 TABLE 5 S o i l phosphorus c o n t e n t (kg/ha) by season of l o g g i n g Season (1) 0-4 cm O f f - l a n d i n g a r ea (2) 4-30 cm T o t a l L a nding a r e a 0-30 cm Summer (5) 61±6 (3) 101±29 162130 (A) 3516 Win t e r 4715 3415 8119 *** 2116 1. T o t a l P from Caro's a c i d d i g e s t . 2. A v a i l a b l e s o i l P. 3. V a l u e s are means 1SE f o r t h r e e r e p l i c a t i o n s w i t h f o u r subsamples. 4. ***denotes a s i g n i f i c a n t d i f f e r e n c e at the 99% l e v e l of p r o b a b i l i t y between o f f - l a n d i n g and l a n d i n g t o t a l s . 5. ** denotes a s i g n i f i c a n t d i f f e r e n c e at 95% l e v e l of p r o b a b i l i t y between summer-logged and w i n t e r - l o g g e d s t a n d s . 37 TABLE 6 S o i l phosphorus c o n c e n t r a t i o n (ppm) by season of l o g g i n g O f f - l a n d i n g a r e a Season L a n d i n g a r e a (1) (2) (3) 0-4 cm 4-30 cm Average 0-30 cm (4) (5) Summer 679±88 45±26 130±11 *** 9±1 Winter 704±71 16±4 108±10 *** 6±2 1. T o t a l P from Caro's a c i d d i g e s t . 2. A v a i l a b l e s o i l P. 3. Weighted average by depth. 4. Values are means ±SE f o r t h r e e r e p l i c a t e s of f o u r subsamples. 5. *** denotes a s i g n i f i c a n t d i f f e r e n c e at 99% l e v e l of p r o b a b i l i t y between o f f - l a n d i n g average and l a n d i n g e s t i m a t e . t o o f f s e t t h e r e m o v a l of t h e f o r e s t f l o o r (0-4 cm) and t h e s u r f a c e m i n e r a l s o i l . The s o i l p h o s p h o r u s p o o l i s h i g h l y dependent on the phosphorus a s s o c i a t e d w i t h the s o i l o r g a n i c m a t t e r ( 3 9 % f o r t h e summer- and 59% f o r t h e w i n t e r - l o g g e d s t a n d s ) . A d d i t i o n a l l y , t h e s c a l p i n g of t h e s u r f a c e m i n e r a l s o i l has r e s u l t e d i n e x p o s u r e of s o i l t h a t i s l o w e r i n 38 s o i l has resulted in exposure of s o i l that i s lower in available phosphorus concentration (Appendix 6). Although the summer-logged stands have a higher phosphorus content than the winter-logged stands, both are extremely sensitive to the removal of surface s o i l horizons. The decline in s o i l phosphorus content on the landing areas (80% for summer- and 74% for winter-logged stands) may be even greater since the a c c e s s i b i l i t y of the dense s o i l to root exploitation i s lim i t e d . As with the s o i l nitrogen concentration, the low available s o i l phosphorus level of the residual soi l material on landings may point to the need to address s o i l f e r t i l i t y problems during landing rehabilitation. Potassium The effects of landing construction on the soil potassium pool are similar to those encountered with s o i l nitrogen. The s o i l potassium content (Table 7) was not s i g n i f i c a n t l y affected by s o i l scalping (Appendix G). Although the forest floor (0-4 cm) accounted for 46% of the summer and 39% of the winter-logged stands' potassium content, the increase in bulk density of the residual s o i l material on the landing offset this loss. As was the case with s o i l nitrogen, the overall soi l potassium concentration (Table 8) suffered a significant decline (Appendix H). However, when compared to the off-landing mineral soils the soil potassium concentration of the 39 TABLE 7 S o i l p o t a s s i u m c o n t e n t (kg/ha) by season of l o g g i n g O f f - l a n d i n g a r ea Season (1) 0-4 cm (2) 4-30 cm T o t a l L a nding a r e a 0-30 cm Summer 84±12 (3) 99±13 (4) 182±11 ns 188±27 Wi n t e r 78 + 4 128±18 206±14 ns 162±41 1. T o t a l K from Caro's a c i d d i g e s t . 2. A v a i l a b l e s o i l K. 3. V a l u e s are means ±SE f o r t h r e e r e p l i c a t e s w i t h f o u r subsamples. 4. ns denotes no s i g n i f i c a n t d i f f e r e n c e between o f f - l a n d i n g and l a n d i n g t o t a l s . 40 TABLE 8 Soil potassium concentration (ppm) by season of logging Off-landing area Season (1) 0-4 cm (2) 4-30 cm (3) Average Landing area 0-30 cm Summer (A) 900±61 49±4 (5) 162±11 *** 53±11 Winter 1078±122 61±11 197±24 *** 47±15 1. Total K from Caro's acid digest. 2. Available so i l K. 3. Weighted average by depth. 4. Values are means ±SE of three replications with four subsamples. 5. *** denotes a significant difference at the 99% level of probability. residual so i l was not adversely affected by scalping, as was the case with soi l nitrogen. The so i l potassium concentration is highly dependent on mineral weathering but not humification and mineralization as are s o i l nitrogen and phosphorus (Thompson, 1978). While an overall decline in s o i l potassium content did not occur, the loss of the readily available and easily accessible potassium may be of considerable importance to the future tree growth. 41 Summary of Effects on Nutrients Overall, the s o i l phosphorus pool i s the most sensitive to scalping during landing construction. The removal of the forest floor combined with the exposure of substantially poorer q u a l i t y s o i l m a t e r i a l (as i n d i c a t e d by s o i l concentration) results in a much reduced phosphorus pool available for plant growth. The s o i l nitrogen and potassium pools behave similarly, with a large loss of nutrients due to the removal of the forest f l o o r , which was offset by the increase in s o i l density of the r e s i d u a l mineral s o i l . However, the accessibility of these nutrients for plant use in the more dense r e s i d u a l s o i l i s suspect. Following decompaction during landing r e h a b i l i t a t i o n , the "new" less compact 0-30 cm layer w i l l have a smaller though more accessible nutrient pool. If rehabilitation measures do not address soi l f e r t i l i t y problems, forest productivity on such areas may suffer. 3.5.3 Effect of Landing Construction on Regeneration  Performance In the previous two sections of this study, i t has been shown that landings have much higher bulk density and poorer so i l quality than cut-over lands. However, i t is d i f f i c u l t to use these factors alone to confidently predict a decline in 42 f o r e s t y i e l d . Tree growth i n v o l v e s complex i n t e r a c t i o n s and i f a i r , w a t e r , and n u t r i e n t s u p p l i e s meet t h e g r o w t h r e q u i r e m e n t s , growth need not be i m p a i r e d by a r e s t r i c t e d r o o t system or low s o i l n u t r i e n t c o n c e n t r a t i o n . To a s c e r t a i n t h e e f f e c t o f l a n d i n g c o n s t r u c t i o n on s i t e p r o d u c t i v i t y , c o n i f e r r e g e n e r a t i o n p e r f o r m a n c e f a c t o r s were m e a s u r e d i n t h e o l d e r f o u r c u t b l o c k s . F o r e a c h s t a n d , d i f f e r e n c e s i n s e e d l i n g s t o c k i n g , s e e d l i n g h e i g h t g r o w t h , and f o l i a r n u t r i e n t s t a t u s between l a n d i n g and o f f - l a n d i n g areas were t e s t e d f o r . A l t h o u g h assessment of the l o n g - t e r m impact of l a n d i n g c o n s t r u c t i o n on f u t u r e s i t e y i e l d i s beyond t h e scope of t h i s s t u d y , g e n e r a l i n f e r e n c e s based on t h i s data are p o s s i b l e . R e g e n e r a t i o n S t o c k i n g The r e g e n e r a t i o n survey was based on w e l l - s p a c e d t r e e s , n o t t o t a l s t o c k i n g , and t h e t a r g e t f i g u r e f o r s a t i s f a c t o r y s t o c k i n g was 1200 s e e d l i n g s ( o r t r e e s ) per h e c t a r e . The r e s u l t s of t h e s t o c k i n g s u r v e y a r e p r e s e n t e d i n T a b l e 9. S t a t i s t i c a l a n a l y s i s i n d i c a t e d o n l y one of t h e f o u r s t a n d s , the s i x - y e a r - o l d summer-logged c u t b l o c k , s u f f e r e d a decrease i n s t o c k i n g due t o l a n d i n g c o n s t r u c t i o n ( A p p e n d i x I ) . The o t h e r t h r e e s tands demonstrated no decrease i n the s t o c k i n g of l a n d i n g s due t o c o n s t r u c t i o n , and were of a c c e p t a b l e l e v e l s . S i n c e t h e s u r f a c e l a y e r (0-10 cm) b u l k d e n s i t y of t h e s i x -y e a r - o l d summer l a n d i n g s i s no g r e a t e r than t h a t of the o t h e r 43 TABLE 9 R e g e n e r a t i o n s t o c k i n g survey (stems/ha) Year p o s t - l o g g i n g Season o f f - l a n d i n g a r e a L a n d i n g a r e a Summer Wint e r (1) 1225175 1300158 9001147 1075+150 (2) * 11 Summer Wint e r 13251111 1225148 1225+103 9501168 1. V a l u e s a r e means 1SE o f f o u r e s t i m a t e s w i t h two subsamples. 2. ^denotes a s i g n i f i c a n t d i f f e r e n c e at the 90% l e v e l of p r o b a b i l i t y between o f f - l a n d i n g and l a n d i n g a v e r a g e s . l a n d i n g s , t h e d e c r e a s e i n s t o c k i n g w o u l d n o t a p p e a r t o be e n t i r e l y a f u n c t i o n of l a n d i n g c o n s t r u c t i o n . F o l i a r N u t r i e n t C o n c e n t r a t i o n The f o l i a r n u t r i e n t c o n c e n t r a t i o n f o r N, P, and p r e s e n t e d i n T a b l e 10. S t a t i s t i c a l a n a l y s i s of e a c h K a r e s t a n d 44 r e v e a l e d a s i g n i f i c a n t , d i f f e r e n c e i n f o l i a r K f o r the 6-year-o l d summer l a n d i n g s and i n f o l i a r N f o r t h e e l e v e n - y e a r - o l d summer l a n d i n g s as compared to the o f f - l a n d i n g a r e a s (Appendix J ) . The i n c r e a s e i n f o l i a r K f o r t h e s i x - y e a r - o l d summer l a n d i n g s may r e f l e c t a h i g h e r a v a i l a b l e p o t a s s i u m l e v e l i n the r e s i d u a l m i n e r a l s o i l t h a n t h e o f f - l a n d i n g m i n e r a l s o i l (63 v e r s u s 46 ppm, r e s p e c t i v e l y ) and s u g g e s t s p o s s i b l e l u x u r y consumption of p o t a s s i u m . The f o l i a r p o t a s s i u m l e v e l s f o r a l l t h e s t a n d s , b o t h o f f - l a n d i n g and l a n d i n g a r e a s , a r e a d e q u a t e f o r l o d g e p o l e p i n e growth ( B a l l a r d , 1980). The s i g n i f i c a n t d ecrease i n f o l i a r n i t r o g e n c o n c e n t r a t i o n on t h e e l e v e n - y e a r - o l d summer l a n d i n g s i s b i o l o g i c a l l y i m p o r t a n t . The f o l i a r n i t r o g e n l e v e l on t h e l a n d i n g a r e a i s below the d e f i c i e n c y t h r e s h o l d f o r l o d g e p o l e p i n e , s u g g e s t i n g d e f i c i e n c y i n s o i l n i t r o g e n a v a i l a b i l i t y ( B a l l a r d , 1980). A l t h o u g h the n i t r o g e n c o n t e n t on the l a n d i n g s i s comparable to the o f f - l a n d i n g a r e a s , the l a n d i n g s on t h i s c u t b l o c k are more dense than the l a n d i n g s on the e l e v e n - y e a r - o l d w i n t e r - l o g g e d c u t b l o c k (1750 v e r s u s 1480 kg/m^, r e s p e c t i v e l y ) . I t a p p e a r s t h a t the s e e d l i n g s i n the o l d e r , more dense summer l a n d i n g s may be d e m o n s t r a t i n g t h e e f f e c t s of s o i l n u t r i e n t d e p l e t i o n over t i m e as the r e s u l t of a r e s t r i c t e d r o o t zone. T h i s c o u l d be e x p e c t e d based on t h e e f f e c t of h i g h s o i l d e n s i t y on r o o t development as d i s c u s s e d i n Chapter 2. 45 TABLE 10 F o l i a r N, P, and K c o n c e n t r a t i o n (%) Year O f f - l a n d i n g L anding p o s t - l o g g i n g a r e a a r e a Season N (1) 6 Summer 1.57 + 02 1.61 + .02 Win t e r 1.52 ± . 03 1.49 + .02 (2) 11 Summer 1.49 ± . 04 1.26 + .03** Wi n t e r 1.46 + 05 1.48 + .02 6 Summer 0.170 + P .003 0.176 + .003 Win t e r 0. 158 + .001 0.162 .004 11 Summer 0.159 + .008 0. 142 + .004 Win t e r 0.148 + .004 0.155 + .003 K 6 Summer 0.643 + .014 0.690 + .010** W i n t e r 0.637 + .015 0.603 + .027 11 Summer 0.559 + .011 0.556 + .012 Win t e r 0.577 + .012 0.581 + .019 1. V a l u e s a r e means ±SE of f o u r e s t i m a t e s w i t h two subsamples. 2. ** denotes a s i g n i f i c a n t d i f f e r e n c e at the 95% l e v e l of p r o b a b i l i t y between o f f - l a n d i n g and l a n d i n g n i t r o g e n c o n c e n t r a t i o n . 46 Seedling Height •j Statistical analysis (Appendix K) of the seedling height data presented in Table 11 indicated a s i g n i f i c a n t (at 90% probability) and highly s i g n i f i c a n t (at 99% probability) effect of landing construction on the six-year-old and eleven-year-old cutblocks respectively. Seedling height on the six-year-old summer landings averaged only 54% of that on the off-landing area, while the winter landings averaged 72%. The d i f f e r e n c e was more pronounced on the e1even-year-o1d cutblocks, 42% and 38% for summer- and winter-logged areas respectively. This trend of greater height difference between off-landing and landing areas could persist for some time. It appears that the higher s o i l density of the landing areas, combined with the poorer nutrient soi l quality, is adversely affecting height growth. It i s very doubtful that these landing areas w i l l produce merchantable timber within a standard rotation age for this forest type, although at the time of a regeneration survey such areas would be considered fully stocked. The inclusion of comparable landing areas in an allowable cut c a l c u l a t i o n may therefore r e s u l t in overcutting by four to five percent. 47 TABLE 11 S e e d l i n g h e i g h t s (cm) f o r a l l s t a n d s Year p o s t - l o g g i n g Season O f f - l a n d i n g a r e a L a n d i n g a r e a 6 Summer Wint e r 74 ± 81 88 ± 5 40 + 11 6 3 + 9 (2) 11 Summer Wint e r 283 ± 24 266 ± 15 120 ± 17 *** 100 ± 25 *** 1. V a l u e s a r e means ±SE o f f o u r e s t i m a t e s w i t h two subsamples. 2. *} *** denote a s i g n i f i c a n t d i f f e r e n c e a t the 90% and 99% l e v e l s of p r o b a b i l i t y , r e s p e c t i v e l y , between o f f - l a n d i n g and l a n d i n g a v e r a g e s . 3.6 Summary and C o n c l u s i o n A l t h o u g h summer l a n d i n g s c o n s t r u c t i o n r e s u l t e d i n g r e a t e r s o i l d e n s i t y a t t h e d e e p e r d e p t h s t h a n on w i n t e r l a n d i n g s , both were s u f f i c i e n t l y dense to a d v e r s e l y a f f e c t t r e e growth i n t h i s s t u d y a r e a . The i n c r e a s e i n s o i l d e n s i t y , when compared t o o f f - l a n d i n g a r e a s , was g r e a t e s t a t t h e s o i l 48 surface and declined rapidly with depth and i t s influence was s t i l l evident at the 20- to 30-cm depth. To f u l l y a l l e v i a t e this problem, s o i l decompaction measures during landing rehabilitation may have to go to 40 or 50 cm in depth. The residual s o i l material on landing areas was of r e l a t i v e l y poor quality compared to off-landing areas, as rated by nutrient concentration. The removal of surface soi l horizons, especially the forest floor (0-4 cm), had a serious impact on the nitrogen and phosphorus n u t r i e n t pools. Potassium was a f f e c t e d to a l e s s e r degree. Landing r e h a b i l i t a t i o n measures may need to address this decline in s o i l f e r t i l i t y i f f u l l recovery of productivity i s the objective. There was l i t t l e evidence that landing construction adversely a f f e c t e d stocking l e v e l s or f o l i a r n utrient concentrations of regenerated lodgepole pine on these sites. Although seedlings were able to establish and grow in s o i l greater than 1500 kg/n_3 in density, seedling height growth was adversely affected. The difference in height between landing and off-landing lodgepole pine appeared to increase with time, as inferred by studying landings of different ages. Although root systems were not examined, i t seems likely that the decrease in seedling height i s due to a combined effect of restricted root development and localized nutrient depletion around the seedling root. It is doubtful that the landings in 49 around the s e e d l i n g r o o t . I t i s d o u b t f u l that the l a n d i n g s i n the study area w i l l produce c o m m e r c i a l - s i z e d timber comparable to the o f f - l a n d i n g areas w i t h i n the c u r r e n t r o t a t i o n without r e m e d i a l measures ..being i n s t i t u t e d . U n t i l such time, l a n d i n g a r e a s s h o u l d be c o n s i d e r e d u n d e r - p r o d u c t i v e and be e x c l u d e d (or compensated f o r ) i n a l l o w a b l e cut c a l c u l a t i o n s . 50 4.0 RESTORING PRODUCTIVVITY ON DEGRADED FOREST SOILS:  TWO CASE STUDIES 4.1 Problem Statement The l i t e r a t u r e review and case study presented in the preceding chapters illustrate some of the impacts that forest harvesting can have on s o i l productivity. Within the newly proposed Ministry of Forests policy: Reduction of Site  Disturbance from Logging Operations (1984), one of the main objections i s the r e h a b i l i t a t i o n of unacceptable s i t e disturbances in accordance with firmly established guidelines and procedures. Unfortunately, there are no such guidelines for r e h a b i l i t a t i o n of areas subject to accelerated s o i l erosion, and those that exist for landing construction deal only with the increase in soild density. The removal or loss of f e r t i l e surface s o i l horizons during s i t e degradation through accelerated erosion or scalping procedures and insurance of possible soil f e r t i l i t y problems have yet to be adequately addressed. Much work and some reassessment appear to be warranted i f t h i s p o l i c y i s to meet i t s primary objective ". . . of protecting and conserving the attainment of maximum productivity . . . ." There i s l i t t l e in forestry l i t e r a t u r e that deals with the recovery or enhancement of s o i l f e r t i l i t y a f t e r 51 degradation, except in regard to erosion control. It is more appropriate to borrow from mined land reclamation and agriculture for methodologies to recover site productivity. These disciplines deal with degraded soi l material where most of the effort is directed to accelerating so i l development "in situ." 4.2 Literature Review In agriculture, s o i l degradation due to repeated cropping may necessitate putting land under fallow cover crops for five or more years (Agboola, 1975). The establishment of a self-sustaining, production plant cover is often used as the main c r i t e r i a to define successfu11y-rec1 aimed land (Ziemkiewicz, 1979). In both cases, the establishment of a high biomass producing cover crop (often containing grasses and legumes) is considered essential to improvement of the physical and chemical properties of degraded s o i l s and the enhancement of site productivity. A green fallow or cover crop enhances s o i l f e r t i l i t y through several processes. Deep penetrating roots can encourage " b i o l o g i c a l weathering" of parent material, thus promoting n u t r i e n t a v a i l a b i l i t y . The surface horizon concentration of phosphorus, potassium, and other nutrients can be greatly enhanced through nutrient "mining" — the 52 translocation of available nutrients in an organic form to the surface and subsequent release through detritus decompostion (Azboola, 1975). The rapid accumulation of s o i l nitrogen under a fallow crop depends upon the presence and activity of leguminous and non-leguminous species which can f i x gaseous nitrogen to available forms. The rapid turnover of the fallow crop root mat plays an important role in the storage and release of carbohydrates and nutrients. Slough root material provides an available energy source for s o i l microbes which promote cycling of slough nutrients. The accumulation of organic matter in the s o i l through root decomposition enhances s o i l nutrient retention (C.E.C.), aggregation, b u f f e r i n g c a p a c i t y , and chelate formation (Allison, 1973). The accumulation of surface detritus, though slow to breakdown and be incorporated in the s o i l , w i l l eventually enter the active nutrient cycle. In the meantime, this organic mat acts as a mulch modifying s o i l moisture and temperature regimes. This, in turn, w i l l promote s o i l biological activity and assist in maintaining the cycling of nutrients. The use of green fallow crops on severly degraded forest land appears to be a viable method for the restoration or enhancement of site productivity. 53 4.3 Objectives The objective of these case studies i s to evaluate the effectiveness of a green fallow crop in restoring productivity on severely degraded forest s i t e s . Based on the l i t e r a t u r e , the green fallow system appears to be a low cost method of enhancing s o i l f e r t i l i t y , with the additional benefit of controlling s o i l erosion. A comparison of s o i l nitrogen, potassium, and phosphorus pools from treated and control (untreated) sites was used to predict productive capability for the purpose of evaluating the effectiveness of s o i l restoration measures. The enhancement of soil nutrient levels to acceptable minimum levels for commercial tree growth, combined with an evaluation of seedling performance was used to determine the fea s i b i l i t y of restoring productivity through green fallowing. 4.4 Limitations Due to budget l i m i t a t i o n s , only two test sites were established for evaluation of the green fallow system. The chosen sites were representative of the pr i n c i p a l site degrading processes encountered with forest harvesting in their respective regions. The coastal study, monitored for seven years, was established on subsoil material exposed by 54 road construction and subject to accelerated s o i l erosion. The results from this study could also be applicable to coastal areas following surface horizon removal by mass wasting. The i n t e r i o r study, monitored for two years, was established on summer landings that had been subject to scalping and so i l compaction. The landing areas had been deep ripped according to standard landing r e h a b i l i t a t i o n procedures. No measures had been taken to enhance the f e r t i l i t y of the "rehabilitated" landings. A l i m i t a t i o n to this approach was the short time period over which restoration effects were measured. Soil changes or seedling responses associated with "restoration" measured over a short period of time may not represent changes in the long run. This may bias the conclusions regarding recovery of productivity at the time of timber harvest. However, a short-term analysis can give a preliminary indication as to whether a proper course of action has been undertaken and whether long-term studies are warranted. 4.5 Materials and Methods Two t e s t s i t e s were es t a b l i s h e d for a p r e l i m i n a r y evaluation of the effectiveness of a green fallow crop in restoring site productivity on severely degraded forest s o i l . At each site, forest harvesting activities had resulted in the 55 At each s i t e , f o r e s t h a r v e s t i n g a c t i v i t i e s had r e s u l t e d i n the r e m o v a l of s u r f a c e s o i l h o r i z o n s and t h e e x p o s u r e of t h e C h o r i z o n or p a r e n t m a t e r i a l . The green f a l l o w crop e s t a b l i s h e d a t each s i t e was s e l e c t e d w i t h s o i l and c l i m a t i c l i m i t a t i o n s and management o b j e c t i v e s i n m i n d . At t h e c o a s t a l s i t e ( K o k s i l a h ) , a g r a s s - l e g u m e c o v e r c r o p was e s t a b l i s h e d t o c o n t r o l s o i l e r o s i o n and r e s t o r e s i t e p r o d u c t i v i t y . O n l y l e g u m e s were i n c l u d e d i n t h e f a l l o w c r o p f o r t h e i n t e r i o r s tudy (Vanderhoof) where r e c o v e r y of s i t e p r o d u c t i v i t y was the o n l y g o a l and g r a s s - t r e e c o m p e t i t i o n expected to be a problem. F o r e a c h s t u d y , a c o m p a r i s o n o f s i t e n u t r i e n t c a p i t a l ( n i t r o g e n , p h o s p h o r u s , and p o t a s s i u m ) b e t w e e n t r e a t e d ( r e v e g e t a t e d ) and c o n t r o l p l o t s was c a r r i e d o u t . N u t r i e n t p o o l s from the t r e a t e d p l o t s i n c l u d e d s o i l and o r g a n i c m a tter ( c o v e r c r o p s h o o t , r o o t , and d e t r i t u s ) c o m p o n e n t s , w h i l e t h e c o n t r o l n u t r i e n t p o o l s i n c l u d e d o n l y t h e s o i l . I n a d d i t i o n , h e i g h t g r o w t h and v i g o r (as i n d i c a t e d by f o l i a r n u t r i e n t c o n c e n t r a t i o n ) of s e e d l i n g s e s t a b l i s h e d on t h e p l o t s were compared. 4.5.1 S i t e D e s c r i p t i o n C o a s t a l Study — K o k s i l a h The study s i t e i s l o c a t e d a p p r o x i m a t e l y of S h a w n i g a n Lake i n t h e K o k s i l a h R i v e r 15 km n o r t h w e s t w a t e r s h e d . The 56 c o o r d i n a t e s of t h e a r e a a r e 1 2 3° 48' 30" W and 4 8° 48' 50" N. The n a t u r a l s o i l i s an O r t h i c D y s t r i c B r u n i s o l , p a r t of t h e Shawnigan G r a v e l l y Sandy Loam a s s o c i a t i o n (Keser & S t . P i e r r e , 1 9 7 3 ) . The f o r e s t f l o o r (7-0 cm), Ae (0-1 cm), and Bm ( 1 -50cm) h o r i z o n s were removed, due to road c o n s t r u c t i o n and s o i l e r o s i o n . The r e s i d u a l s o i l m a t e r i a l i s a compact g r a v e l l y , g l a c i a l t i l l w i t h a s a n d y - l o a m t e x t u r e . The a v e r a g e b u l k d e n s i t y f o r t h e s i t e i s 1500 kg/m^, as d e t e r m i n e d u s i n g t h e core method ( t h r e e sub-samples per p l o t ) . A c c o r d i n g t o K l i n k a e t a l . ( 1 9 7 9 ) , t h e s i t e l i e s w i t h i n t h e D r i e r E a s t e r n V a n c o u v e r I s l a n d v a r i a n t o f t h e C o a s t a l Western b i o g e o g c l i m a t i c zone (CWHa2/05). T h i s i s a complex of Tsuga ( h e t e r o p h y l l a ) - P s e u d o t s u g a ( m e n z i e s i i ) - H y l o c o m i u m  (spendens) - S t o k e s i e l l a (oregana). The v a r i a n t i s c o n s i d e r e d by K l i n k a e t a l . (1979) t o be m e s o t r o p h i c -- m e s i c s i t e ( n u t r i e n t r i c h -- w e l l d r a i n e d ) . The a r e a was opened up f o r l o g g i n g i n 1973 and p a r t of t h e w a t e r s h e d s t i l l s u p p o r t s a h i g h l y p r o d u c t i v e D o u g a l s - f i r and w e s t e r n h e m l o c k s t a n d ( D o u g l a s - f i r s i t e i n d e x 42 m at 100 y e a r s ) . I n June 1976, two r e p l i c a t e s of p a i r e d t r e a t e d and c o n t r o l r e s e a r c h p l o t s were e s t a b l i s h e d on an e x t e n s i v e a r e a of s u b s o i l m a t e r i a l e x p o s e d d u r i n g r o a d c o n s t r u c t i o n . Each p l o t was a p p r o x i m a t e l y 50 m x 25 m and t h e s l o p e g r a d i e n t ranged from 40 to 90%. The r e v e g e t a t e d p l o t s were seeded a t a 57 r a t e of 100 kg/ha w i t h a g r a s s - l e g u m e seed mix (Appendix L ) . These p l o t s a l s o r e c e i v e d a 450 kg/ha a p p l i c a t i o n of 10-30-10 f e r t i l i z e r as a s t a r t e r . Cover establishment on the t r e a t e d p l o t s was e s t i m a t e d at 70% i n A p r i l 1977, w i t h no v e g e t a t i o n on the c o n t r o l p l o t s ( C a r r & B a l l a r d , 1980). In May 1977, D o u g l a s - f i r s e e d l i n g s (1-2 s t o c k ) were p l a n t e d at 1.5 m x 1.5 m spacing on a l l p l o t s . I n t e r i o r Study — Vanderhoof The s t u d y s i t e i s l o c a t e d a p p r o x i m a t e l y 30 km s o u t h of Vanderhoof near C o r k s c r e w Creek on the K l u s k u s F o r e s t Road. The c o o r d i n a t e s of the chosen c u t - b l o c k are 1 2 4° 21" 30" W and 5 3° 51' 10" N. The n a t u r a l s o i l of the area was i d e n t i f i e d as part of the C h i l a k o Stony Sandy loam complex (Fa r s t a d & L a i r d , 1954) and i s c l a s s i f i e d as a Degraded D y s t r i c B r u n i s o l , A l i x s e r i e s ( C o t i c et a l . , 1976). The f o r e s t f l o o r (5-0 cm), Ae (0-1 cm), and Bm (1-25 cm) h o r i z o n s were removed by s c a l p i n g during l a n d i n g c o n s t r u c t i o n . The r e s i d u a l s o i l m a t e r i a l i s a g r a v e l l y , g l a c i o f l u v i a l d e p o s i t w i t h a sandy loam-sand t e x t u r e . The area l i e s w i t h i n the Sub-boreal Spruce B i o g e o c l i m a t i c zone ( K r a j i n a , 1965) and was r e c e n t l y f u r t h e r c l a s s i f i e d as a F a l s e s a r s a p a r i l l a — P r i n c e ' s pine-moss e c o s y s t e m u n i t (SBSk2/04) by DeLong and McLeod (1984). T h i s i s a complex of 58 ZAUujs. (co^ntorta) — P_s^e^_u d_ o^_t u_^ a_ ( m .ejissi^ s.ii ) — R £ js a_ (acicularis) — Aralia (nudicaulis) — Chimaphila (umbellata) — Pleurozium (schreberi). Th.e moisture regime i s submesic and the nutrient regime i s submesotrophic — mesotrophic (poor-medium). This area, which was clearcut in the later summer of 1976, supported a medium site class stand of Pinus  contorta and Picea glauca engelmannii (lodgepole pine and hybrid spruce). In August 1980, twenty-eight landings and connecting skid roads were deep-ripped to a depth of approximately 50 cm using an experimental three-toothed plow. The ripping t r i a l was considered successful in reducing soi l density to acceptable levels, approximately 1350 kg/m.3 as determined using the core method. For comparison, s o i l density on unripped summer landings of a sim i l a r s o i l material near Fort St. James averaged 1650 kg/m^ (see Chapter 3). In 1981, four of the ripped landings were selected for this study. These landings were selected due to similarity in s o i l condition and topographic orientation. Prior to the treatment, form subsampling locations within each landing were randomly selected for s o i l analysis. The plots were then seeded with a legume seed mix (Appendix M) at a rate of 40 kg/ha and given a starter f e r t i l i z e r application of 19-19-19 at a rate of 300 kg/ha. In June 1981, lodgepole pine seedlings (2-0 bare-root stock) were planted on three control 59 and three treated plots at a spacing of 1.5 m x 1.5 m. By August 1982, cover establishment on the treated plots was vi s u a l l y estimated as 65% and the control plots as less than 5%. 4.5.2 Field Sampling Procedures  Coastal Study — Koksilah S o i l and organic matter analyses were performed in September 1980 and 1982. Within each plot, two treated and two controls, three subsampling locations were randomly selected. A l l subsamples were analyzed separately and later averaged to represent the plot value. For the control plots, a s o i l sample was taken to a depth of 30 cm using a 5 cm-diameter soi l core. The s o i l samples were stored in plastic bags for t r a n s p o r t . On the treated p l o t s , the sample c o l l e c t i o n procedure was carried out by layers. The above-ground organic matter (shoot and standing detritus) was clipped from within a 25 cm x 25 cm frame and placed in paper bags for transport. Next, a 5-cm s o i l core was taken to a depth of 30 cm, as on the control plots. Care was taken to label the layered samples from each subsample location so that the total nutrient pool could be estimated. In 1982, the current year foliage was collected from five 60 randomly selected seedlings in each plot for foliar nutrient concentration a n a l y s i s (N,P, and K). To t a l height and internodal length of the seedlings were measured and the height in previous years estimated. Interior Study — Vanderhoof I n i t i a l s o i l analysis prior to treatment was in 1981, with f i n a l s o i l , organic matter, and seedling analyses performed in September 1983. On each landing, four subsample locations were randomly selected for before (control) and a f t e r (treated) sampling. For the c o n t r o l sampling, a composite s o i l sample consisting of two 5 cm-diameter s o i l cores taken to a 30 cm depth was collected at each subsample location. The composite s o i l samples were stored in a plastic bags for transport. For the post-treatment assessment, the sample c o l l e c t i o n procedure was carried out in layers. At each subsample locations, above ground organic matter (shoot and standing detritus) was clipped from within a 0.385 m^  c i r c u l a r plot (radius of 0.35 m) and stored in paper bags for transport. Next, a composite s o i l sample was taken using the same procedure as on the control plots. Care was taken to label the layered samples from each subsample location so that the total nutrient pool could be estimated. For the evaluation of the effect of the fallow crop 61 establishment on regeneration performance, 30 seedlings from each of the planted landing areas (three control and three treated) were randomly selected for height measurement. Additionally, six composite samples of the current year's foliage (5 seedlings per composite) were collected from each landing and analyzed for folia r nutrient concentration. 4.4.3 Laboratory Procedures Coastal Study — Koksilah Preparation and a n a l y s i s of s o i l , shoot, standing detritus, and folia r samples were conducted at the Department of S o i l Science, U.B.C. (1980) and at P a c i f i c S o i l Analysis Inc., Vancouver (1982). (The same analytical procedures were followed at each laboratory using similar equipment). So i l samples were air- d r i e d at 20°C for at least 24 hours. The organic components (roots and fallen detritus) were separated from the treated plot s o i l samples by hand clearing under a microscope. The air-dried s o i l material from a l l plots was separated into coarse (_> 2 mm) and fine (< 2 mm) fractions by sieving and weighed. The fine fraction was used for the chemical analyses. The root and fallen detritus samples (referred to as R + D) were oven-dried at 80°C for 24 hours, weighed, and expressed as a percentage of the original s o i l sample. The R 62 + D sample was then ground into a fine powder, using a mortar and pestle, for chemical analysis. The shoot and standing detritus samples (referred to as S + D) were oven-dried at 80°C for 24 hours in the paper bags, weighed (corrected for bag weight), and ground in a Wiley M i l l f i t t e d with a 1 mm sieve. The f o l i a r samples were air- d r i e d for at least 24 hours and needles were separated from branches. The needles were then oven-dried at 80°C for 214 hours and ground to a uniform powder for analysis, using a small blender fitted with special blades. A l l vegetative material was then analyzed for N, P, and K. A l l laboratory analysis procedures were based on the Methods Manual — Pedology Laboratory, Department of Soi l Science, U.B.C. (Lavkulich, 1978), except the f o l i a r analysis which was based on Ballard (1980). The following analyses were performed: total s o i l nitrogen: using a semi-micro Kjeldahl digest with colorimetric d e t e r m i n a t i o n using a Technicaon autoanalyzer; available soil phosphorus: using the Bray P-l method; available so i l potassium: using a Morgan's extraction ( 1 . 0 N N a 0 C c ) i n conjunction with atomic 63 a b s o r p t i o n d e t e r m i n a t i on; f a l l o w crop and f o l i a r N, P, and K: u s i n g a Caro's a c i d d i g e s t w i t h N and P c o l o r i -m e t r i c a l l y determined on a Technicon a u t o a n a l y z e r and K m e a s u r e d by a t o m i c a b s o r p t i o n . The c o m p a r i s o n of n u t r i e n t p o o l s between t r e a t e d and c o n t r o l p l o t s was based on t o t a l n u t r i e n t p o o l s . For the t r e a t e d p l o t s , t h e s e i n c l u d e d both f a l l o w c r o p and s o i l components. The use of t o t a l n u t r i e n t pool o f f s e t the problem of component s e p a r a t i o n i n the l a y e r e d s a m p l i n g scheme, p a r t i c u l a r l y with s e p a r a t i o n of the f a l l o w d e t r i t u s and root component from the s o i l . Hand c l e a n i n g of s o i l samples f o r ro o t s and d e t r i t u s can miss a s u b s t a n t i a l p o r t i o n of f i n e root and d e t r i t u s m a t e r i a l . A l t h o u g h t h i s r e s u l t s i n t h e un d e r e s t i m a t i o n of the root and d e t r i t u s c o n t r i b u t i o n to s i t e n u t r i e n t c a p i t a l , the missed organic m a t e r i a l and i t s n u t r i e n t c o n t e n t are a c c o u n t e d f o r i n the s o i l component. The use of t o t a l n u t r i e n t p o o l f o r c o m p a r a t i v e p u r p o s e s removes t h i s problem. S t a t i s t i c a l a n a l y s i s of t h e e f f e c t of f a l l o w c r o p e s t a b l i s h m e n t on s i t e n u t r i e n t c a p i t a l was c o n d u c t e d u s i n g 64 a n a l y s i s of v a r i a n c e (ANOVA) based on a s p l i t - l o t d e s i g n . The main e f f e c t i s t r e a t m e n t d i f f e r e n c e s (two r e p l i c a t i o n s ) , w i t h t h e y e a r of s a m p l i n g b e i n g s p l i t - p l o t e f f e c t . T h i s t e c h n i q u e i s recommended by L i t t l e and H i l l (1978) f o r r e p e a t e d s a m p l i n g of an e x p e r i m e n t a l u n i t . Changes i n t h e t h r e e c o m p o n e n t s w i t h i n t h e t r e a t e d p l o t s o v e r t i m e were t e s t e d f o r u s i n g ANOVA ( s i m p l e f a c t o r , two r e p l i c a t i o n s ) . S t a t i s t i c a l a n a l y s i s of e f f e c t on r e g e n e r a t i o n was a l s o conducted u s i n g ANOVA ( s i n g l e f a c t o r , two r e p l i c a t i o n s ) . I n t e r i o r Study — Vanderhoof P r e p a r a t i o n and a n a l y s i s of s o i l , b i o m a s s , and f o l i a r samples were performed a t P a c i f i c S o i l A n a l y s i s I n c . i n 1981 and 1 9 8 3 . S a m p l e p r e p a r a t i o n and l a b o r a t o r y a n a l y s i s p r o c e d u r e s were the same as those used i n the K o k s i l a h s t u d y . S t a t i s t i c a l a n a l y s i s of the e f f e c t s on s i t e n u t r i e n t c a p i t a l was conducted u s i n g ANOVA ( s i n g l e f a c t o r , f o u r r e p l i c a t i o n s ) . For e f f e c t s on r e g e n e r a t i o n p e r f o r m a n c e , s i n g l e f a c t o r ANOVA w i t h t h r e e r e p l i c a t i o n s was performed. 65 4 . 6 R e s u l t s and D i s c u s s i o n 4.6.1 S i t e N u t r i e n t P o o l s - K o k s i l a h  V e g e t a t i v e and S o i l Components The q u a n t i t y of v e g e t a t i v e m a t t e r p r o d u c e d by t h e g r e e n f a l l o w c r o p i s s u m m a r i z e d i n T a b l e 12 f o r t h e S + D and R + D components and t o t a l p r o d u c t i o n . T h e r e was no s i g n i f i c a n t change i n the p r o d u c t i o n of v e g e t a t i v e m a t t e r (components or t o t a l ) b e t w e e n y e a r s f i v e and s e v e n . The g r e e n f a l l o w c r o p a p p e a r s t o be i n a q u a s i - s t e a d y - s t a t e l e v e l o f p r o d u c t i o n . The i n v a s i o n of n a t i v e t r e e and s h r u b s p e c i e s c o m b i n e d w i t h the growth of p l a n t e d s e e d l i n g s s h o u l d e v e n t u a l l y r e s u l t i n a d e c l i n e i n f a l l o w c r o p p r o d u c t i o n and an a c c u m u l a t i o n o f d e t r i t u s m a t e r i a l . T h i s i n c r e a s e i n the d e t r i t u s p o o l s h o u l d i n c r e a s e s o i l b i o l o g i c a l a c t i v i t y , r e s u l t i n g i n the e v e n t u a l r e l e a s e o f t h e n u t r i e n t s t i e d up i n t h e d e t r i t u s and i n c o r p o r a t i o n of o r g a n i c m a t t e r i n t o the s o i l . T h i s p r o c e s s s h o u l d enhance s o i l p r o p e r t i e s and n u t r i e n t l e v e l s ; however, the t i m e r e q u i r e d f o r these b e n e f i t s to a c c r u e i s not known. A comparison of n u t r i e n t c o n c e n t r a t i o n s i n the S + D and R + D v e g e t a t i v e c o m p o n e n t s ( T a b l e 13) r e v e a l s a f l u c t u a t i o n i n n i t r o g e n and p o t a s s i u m c o n c e n t r a t i o n b e t w e e n t h e two s a m p l i n g p e r i o d s . The n u t r i e n t c o n c e n t r a t i o n i n h e r b a c e o u s v e g e t a t i o n can v a r y g r e a t l y d e p e n d i n g upon t h e s t a g e of 66 TABLE 12 Green fallow vegetative matter (kg/ha) — Koksilah Year Component Total S + D R + D 1980 11,700 ± 2.1001 38,900 ± 800 53,600 ± 2,700 1982 15,900 ± 3,500 31,300 ± 3,300 47,200 ± 6,900 ns^ ns ns 1. Values are means ± SE of two replications 2. ns denotes no significant difference between years. growth. Ziemkiewicz (1979) demonstrated this for high-altitude native and agronomic herbaceous species. Although care was taken to sample the vegetation at the same date in September, the vegetation appears to have been in a more dynamic growth phase in 1980. This i s indicated by higher N and K concentrations in the above-ground component and K concentration in the below-ground component. In 1982, a higher N concentration in the R + D vegetation component paralleled a lower S + D concentration and did not affect t o t a l s o i l N (Table 14). The decrease in K concentration of both vegetative components in 1982 paralleled an increase in available so i l K concentrations of the treated plots over the 1980 l e v e l . There was a s i g n i f i c a n t increase in s o i l available K concentration between 1980 and 1982, probably a result of accelerated weathering of the mineral s o i l . There 67 TABLE 13 Concentration (%) of N, P, and K in the vegetative components — Koksilah Component Year N P K S + D 1980 1.91 ± 0.081 0.189 ± 0.029 1.47 ± 0.01 1982 1.52 ± 0.05 tt* 0.140 ± 0.016 ns^ 0.88 ± 0.01 ** R + D 1980 0.96 ± 0.01 0.089 ± 0.017 0.29 ± 0.02 1982 1.26 ± 0.06 0.118 ± 0.006 ns 0.15 ± 0.01 1. Values are means ± SE of two replications 2. ns, ** denote no s i g n i f i c a n t difference and s i g n i f i c a n t difference, respectively, between years at 95% level of probability. was no s i g n i f i c a n t change in the tota l s o i l N and available s o i l P concentrations of the control plots, or the available s o i l P concentration of the treated plots between sampling dates. Nutrient Totals Although there was a shift in component contribution in the treated plot K pool between years, the total pool was not affected (Table 15). There was no change in the N and P nutrient pool totals on the treated areas or- the N, P, and K 68 TABLE 14 S o i l N, P, and K concentrations — Koksilah Year Total N (%) Available P (ppm) Available K (ppm) Control 1980 0.014 ± 0.0011 12.3 ± 2.0 33 ± 2 1982 0.016 ± 0.001 ns^ 14.4 ± 1.8 ns 43 ± 3 •«•-si-Treated 1980 0.026 ± 0.004 1982 0.031 ± 0.005 ns 16.0 ± 3.6 16.4 ± 2.5 ns 45 ± 6 95 ± 12 1. Values are means ± SE of two re p l i c a t i o n s 2. ns, * * denote no s i g n i f i c a n t d i f f e r e n c e and s i g n i f i c a n t d i f f e r e n c e , r e s p e c t i v e l y , between years at 95% l e v e l of pr o b a b i l i t y . 69 TABLE 15 Total N, P, and K (kg/ha) pools for treated plots — Koksilah Year S + D Component Contribution R + D Soil Total 1980 1982 244 ± 311 240 ± 50 Nitrogen 352 ± 14 393 + 56 727 ± 74 729 ± 61 1303 ± 152 1362 ± 178 1980 1982 22 ± 1 22 ± 3 Phosphorus 35 + 3 36 ± 2 45 ± 8 38 ± 1 102 ± 5 96 ± 5 1980 1982 172 ± 30 134 ± 30 Potassium 110 ± 8 47 ± 5 **2 126 ± 10 220 ± 13 408 ± 30 401 ± 56 1. Values are means ±SE of two replications. 2. ** denotes a significant difference between years at 95% level of probability. 70 totals from the control plots between sampling periods (Table 16). S t a t i s t i c a l analysis of the N, P, and K pool totals indicate a significant increase in the site N, P, and K levels due to the establishment of the fallow crop (Appendix N). The increase was evident in the 1980 sampling and had not s i g n i f i c a n t l y changed by 1982. It appears that the increase in s i t e N, P, and K pools had reached a maximum within the f i r s t five years with no change between years five and seven. This pattern of maximum change within the f i r s t five years was also evident in the green fallow vegetation matter production (Table 12). The gain in the nitrogen pool, based on the 1980 data, was 827 kg/ha (allowing for an i n i t i a l f e r t i l i z e r input of 45 kg/ha). This increase of approximately 165 kg/ha/year over the f i r s t five year period would be primarily a function of nitrogen f i x a t i o n by the legume species in the green fallow cover crop. The process of nutrient "mixing" would contribute l i t t l e to this increase due to a low natural t o t a l s o i l nitrogen concentration (0.014% in the control, 1980). The magnitude of this increase in the nitrogen pool is within the values reported by Sprent (1979) of 150-300 kg/ha/year for mixed grass and legume stands. Once the treated plots had reached a tota l nitrogen pool and cycling level adequate- to sustain the fallow crop, further accumulation ceased as has 71 TABLE 16 Comparison of total N, P, and K pools between treated and control plots — Koksilah Year Treated Control Nitrogen 1980 1303 ± 1521 431 ± 91 **2 1982 1362 ± 178 398 ± 57 ** Phosphorus 1980 102.1 ± 5.3 38.9 ± 8.1 1982 96.3 ± 5.2 37.4 ± 11.1 Potassium 1980 408 ± 30 105 ± 11 ** 1982 401 ± 56 109 ± 20 ** 1. Values are means ±SE of two replications. 2. ** denotes a significant difference between years at 95% level of probability. 72 been reported by Sprent (1979), Agboola (1975), Singh (1975), and many others. The phosphorus increase of approximately 63 kg/ha (1980) could be accounted for solely by the i n i t i a l f e r t i l i z e r application only i f a l l of the phosphorus f e r t i l i z e r stayed in the available pool and was not fixed in the s o i l . However, forage crops u t i l i z e approximately 30% of applied f e r t i l i z e r P, the remainder of which is fixed in the soi l (Hinish, 1980). A small percentage of the f i x e d phosphorus can become available each year and may eventually result in the recovery of most of the applied phosphorus (Thompson, 1978). The acid s o i l condition, coupled with a r e l a t i v e l y high s o i l clay content (approximately 15%), would favor phosphorus fixation to some degree. Nutrient "mining" from deeper depths may have accounted for the remaining 70% of the increase, or about 44 kg/ha. According to Standard and Pierre (1953), the growing of a deep-rooted legume crop may be the most efficient means of achieving greater utilization of subsoil phosphorus. The potassium pool demonstrated a substantial increase due to fallow crop establishment, approximately 260 kg/ha after accounting for the i n i t i a l f e r t i l i z e r application. Since the potassium content in a s o i l does not change much even over long periods of time, nutrient "mining" by deep penetrating roots must have been the principal cause of the 73 increase. Thompson (1978) reports that a good a l f a l f a crop can withdraw up to 150 kg/ha/year of soil potassium. The 1980 sampling showing 70% of the potassium pool to be associated with the vegetative components (Table 15) would seem to verify the importance of vegetation establishment for potassium accumulation within the soi l surface. 4.6.2 Site Nutrient Pools — Vanderhoof  Vegetative and Soil Components The data for the green fallow vegetative components at Vanderhoof are presented in Table 17, along with the corresponding N, P, and K concentrations. There is a wide gap between the S + D and R + D components in vegetative matter production. This site i s naturally submesic, and with the removal of surface s o i l horizons during landing construction d r i e r conditions probably e x i s t . In grasslands, x e r i c conditions result in a reduction of shoot mass and promote production of a large root mass (Rodin and Basilevich, 1967). This appears to be the case at Vanderhoof. The s o i l nutrient concentration comparison for the control (before) and treated (after) data (Table 18) revealed a s i g n i f i c a n t increase in t o t a l s o i l N and available K concentration two years after fallow crop establishment. This 7 4 TABLE 1 7 Green f a l l o w v e g e t a t i v e m a t t e r and n u t r i e n t c o n c e n t r a t i o n s (N, P, and K) — Vanderhoof Cmpt. P r o d u c t i o n N P K (kg/ha) (%) (%) (%) S + D 2 4 0 0 ± 2 0 0 1 1 . 5 0 ± 0 . 0 8 0 . 2 2 4 ± 0 . 0 1 4 1 . 7 0 ± 0 . 1 0 R + D 3 6 2 0 0 ± 8 4 0 0 0 . 5 2 ± 0 . 0 6 0 . 1 9 2 ± 0 . 0 2 2 0 . 2 5 ± 0 . 0 6 1 . V a l u e s are means ± SE f o r f o u r r e p l i c a t i o n s . TABLE 1 8 S o i l n u t r i e n t c o n c e n t r a t i o n (N, P, and K) — Vanderhoof P l o t s T o t a l N A v a i l a b l e P A v a i l a b l e K (A) . (PPm) (ppm) C o n t r o l 0 . 0 3 8 ± 0 . 0 0 8 1 5 5 . 7 ± 1 8 . 4 1 1 8 ± 1 8 T r e a t e d 0 . 0 5 2 ± 0 . 0 1 0 6 4 . 0 ± 1 6 . 4 1 6 9 ± 2 4 •5€- •3€* 3 n <3 2 1 . V a l u e s a re means ± SE f o r f o u r r e p l i c a t i o n s . 2 . ns d e n o t e s no s i g n i f i c a n t d i f f e r e n c e a t 9 5 % l e v e l of p r o b a b i l i t y . 3 . ** d e n o t e s a s i g n i f i c a n t d i f f e r e n c e a t 9 5 % l e v e l of p r o b a b i l i t y . 75 trend was similar to that at Koksilah. The available P concentration had not shown a s i g n i f i c a n t increase, as was also the case in the coastal study. Nutrient Totals The component contribution to the t o t a l site nutrient pools i s p resented in Table 19. The high production (kg/ha) of the R + D component dominates the vegetative contribution of nitrogen and potassium. The phosphorus pool i s less dominated by the R + D component than are nitrogen or potassium. A comparison of nitrogen, phosphorus, and potassium pools before and after legume establishment i s presented in Table 20. The phosphorus pool shows a very significant increase, at the 95% l e v e l of probability, due to green fallow crop establishment (Appendix 0). The nitrogen and potassium pool increases are also s i g n i f i c a n t , but at a lower level of p r o b a b i l i t y (90%). Both the phosphorus and potassium increases would indicate nutrient "mining" by the crop root system. The nitrogen pool increase would be, in part, a result of nitrogen fixation by the legumes. The phosphorus pool increase is approximately 58 kg/ha, excluding the 25 kg/ha f e r t i l i z e r application. As is evident in Tables 19 and 20, the increase in phosphorus i s t o t a l l y 76 TABLE 19 Total N, P, and K pools (kg/ha) for treated plots Vanderhoof Component Contribution Total S + D R + D Soil Nitrogen 188 ± 30 1175 ± 106 1400 ± 133 Phosphorus 68 ± 11 150 ± 28 250 ± 32 Potassium 5 ± 1 77 ± 15 417 ± 65 499 ± 76 37 ± 91 41 + 3 1. Values are means ± SE for four replications. TABLE 20 Comparison of total N, P, and K pools (kg/ha) between treated and control plots — Vanderhoof Nutrient Treated Control N P K 1400 + 1331 259 ± 32 499 ± 76 1005 ± 110 *2 145 ± 18 ** 332 ±23 * 1. Values are means ± SE for four replications 2. *, ** denote s i g n i f i c a n t difference between treated and control plots at 90% and 95% level of probability. 77 accounted for in the vegetative components, with no additional available P in the s o i l . Agboola (1975) reports only a minor increase in soi l available P concentration after one year of a legume fallow crop. Phosphorus is tightly cycled and highly mobile within the plant and translocates to areas of active growth from areas of senescence. There would be l i t t l e phosphorus in the detritus for release into the s o i l , and that which was released is subject to phosphate fixation. The s o i l potassium pool i s approximately 120 kg/ha excluding the 47 kg/ha f e r t i l i z a t i o n . Unlike phosphorus, part of the increase in the potassium pool has reached the s o i l (approximately 44 kg/ha available K). Agboola (1975) reported a s i m i l a r l e v e l of increased s o i l potassium (45 kg/ha exchangeable K) under a legume fallow crop. Plant residues are generally high in potassium, which is not in an organic form in the plant. Potassium can be added to the s o i l by leaching of plant detritus or after detritus decomposition, and is readily available for crop use (Allison, 1973). The increase in the nitrogen pool of approximately 156 kg/ha/year (after deduction of f e r t i l i z e r N) i s within the range reported in the l i t e r a t u r e for legume stands (Sprent, 1979; A l l i s o n , 1973) and agrees c l o s e l y with the l e v e l reported by Simpson (1976) for clover stands. Part of this increase has affected the total so i l N concentration, raising 78 speculate that the increase in nitrogen c a p i t a l , as well as phosphorus and potassium, should continue u n t i l a s e l f -sustaining, stable nutrient cycle establishes on the plots as happened at Koksilah. Determination of the eventual magnitude of nutrient pool increase was beyond the scope of this second case study. 4.6.3 Regeneration Performance — Koksilah Foli a r N, P and K concentrations for the Douglas-fir seedlings at Koksilah are presented in Table 21. Statistical analysis (Appendix P) indicates a s i g n i f i c a n t increase in f o l i a r N and K concentrations in response to the fallow crop establishment and the increase in s o i l concentrations. The f o l i a r N concentration at Koksilah i s the more c r i t i c a l factor. A folia r level of 1.2% N is viewed as a minimum level for satisfactory growth of Douglas-fir (Ballard, 1980), which the control plots do not meet. A low growth rate would be expected in the control plots, but not in the treated plots which easily exceed the minimum for f o l i a r N concentration. There was no significant effect during periods of sampling on the foliar N levels. The use of a fallow crop resulted in a s i g n i f i c a n t increase i n f o l i a r K concentration. This response to 79 TABLE 21 Foliar N, P and K concentrations (%) in Douglas-fir seedlings -- Koksilah Plots 1980 1982 Nitrogen Control 1.08 ± 0.161 0.94 ± 0.05 Treated 1.72 ± 0.07 1.77 ± 0.02 *#2 Phosphorus Control 0.298 ± 0.034 *3 0.252 ± 0.022 Treated 0.330 ± 0.026 Potassium 0.241 ± 0.008 Control 0.516 ± 0.004 * 0.724 ± 0.046 Treated 0.839 ± 0.005 0.887 ± 0.064 *# 1. Values are means ± SE of two replications. 2. * denotes a s i g n i f i c a n t difference between treated and control levels at 95% level of probability. 3. ** denotes a s i g n i f i c a n t difference between year levels within treatments at the 95% level of probability. increased s o i l a v a i l a b i l i t y of K, though s t a t i s t i c a l l y s i g n i f i c a n t , i s not b i o l o g i c a l l y s i g n i f i c a n t and probably indicates luxury consumption of potassium. This was also evident in the significant increase in foliar K levels on the control plots between 1980 and 1982 which could be in response to higher available K in the soil (Table 14). While there was no significant effect of treatment on the foliar P concentration, there was a significant effect due to 80 year of sampling on the treated plot. This decrease in foliar P level indicates a d i l u t i o n effect of f o l i a r P due to an increase in f o l i a r biomass. However, the f o l i a r P concentration for both control and treated plots is above the minimum level to maintain adequate growth (Ballard, 1980). The height data (Table 22) indicates a substantial difference in seedling growth between the control and treated plots (Appendix Q). There is a three-fold difference in total height, and a f i v e - f o l d d i f f e r e n c e in the l a s t annual increment. The control seedlings have grown much more slowly than seedlings in the treated plots. Based on the age correction-height table for Douglas-fir (Hegyi et al., 1979), the control plots would be below the low-site classification. The treated p l o t s would be medium to good s i t e , which corresponds to the original site classification. 4.6.4 Regeneration Performance — Vanderhoof The seedling f o l i a r nutrient concentration and height growth data for the lodgepole pine seedling planted at Vanderhoof are presented in Table 23. Statistical analysis of the data (Appendix R) indicated no s i g n i f i c a n t effect on any measured parameters two years after fallow crop establishment. Although there is an increase in total s o i l N and available P, there i s no r e f l e c t i o n of these increases in the seedling 81 TABLE 22 Douglas-fir seedling height (cm) — Koksilah Age (years) Control Treated 9 43.1 ± 9.41 140.1 ± 14.2 ##/ 8 32.4 ± 6.8 85.3 ± 9.2 7 24.1 ± 5.4 45.5 ± 6.2 6 19.1 ± 5.0 32.0 ± 7.4 1. Values are means ± SE of two replications. 2. ** denotes a s i g n i f i c a n t difference between control and treated plots at the 95% level of probability. TABLE 23 Fo l i a r N, P and K concentration (%) and height (cm) of lodgepole pine seedlings — Vanderhoof Plot N P K Height Control 1.68 ± 0 .201 0. 170 ± 0.012 0.734 ± 0.029 36.5± 1 .7 Treated 1.72 ± 0 .07 0. 172 ± 0.005 0.744 ± 0.025 43.3 ± 2 .0 ns2 ns ns ns 1. Values are means ± SE of three replications. 2. ns denotes no significant difference between plots. f o l i a r concentrations. The levels in both the control and treated plots are above those suggested by Ballard (1979) as adequate for satisfactory lodgepole pine growth. The seedling height data bears this out. However, this t r i a l i s s t i l l quite young and as seedling requirements for adequate nutrients increase, there may be a response to the higher 82 nutrient levels that result from the green fallow treatment. 4.6.5 Summary The use of a green fallow crop on severely degraded forest s o i l s appears to be a viable management tool for the enhancement, and possible eventual recovery, of s i t e productivity. In the coastal t r i a l , the nitrogen, potassium, and phosphorus nutrient pools had increased to a plateau within five years that improved seedling performance to that expected from a comparable undisturbed site (medium site-class Doug1as-fir). Of the improvement in s o i l n u t r i e n t concentrations, the increase in t o t a l s o i l nitrogen was the most important. According to Bockheim (1982), the approximate minimum level of t o t a l s o i l N essential for satisfactory growth of medium nutrient requiring species, such as Douglas-f i r , i s 0.05%. Due to the fallow crop, the t o t a l s o i l N concentration exceeds the l i m i t for low requirement species (0.02%) and i s approaching that of the medium requirement species. The higher level of foliar nitrogen concentration, currently above an adequate l e v e l , combined with greater seedling height growth confirm this enhancement in site quality. Although the p l a n t - s o i l nutrient relationship had s t a b i l i z e d by year f i v e , eventual changes in plant cover composition should shift the fallow crop vegetative production 83 into the detritus pool. The decay and accumulation of this organic matter in the soil w i l l further improve soi l nutrient levels and enhance so i l properties. After two years, the legume fallow crop established at the i n t e r i o r site had enhanced site nutrient capital (N, P, and K) and concentrations of to t a l s o i l N and available s o i l K. The post-treatment total s o i l N concentration now exceeds (in 1985) the minimum level for medium nutrient requiring species (Bockheim, 1982). Although there was no growth response in the lodgepole pine seedlings, the enhancement of site nutrient capital should eventually benefit commercial forest production. Further gains to soil nutrient levels and soil properties may be expected as the fallow crop continues to mature. 4.6.6 Conclusion Both fallow crop t r i a l s can be viewed as successful in restoring productivity on severely degraded forest s o i l s within the limited time-frame of this project. The benefits to the site can begin soon after crop establishment (within two years at Vanderhoof) and reach an i n i t i a l maximum fairly quickly (within five years at Koksilah). A second increment of benefits to the site can be expected with the eventual accelerated decay and incorporation of the detritus component 84 as the s i t e matures. Whether the increases in site nutrient capital, s o i l nutrient concentration, and seedling performance are enough to assure recovery of commercial tree production is beyond the scope of this project. However, as stated in Chapter 1, the risks inherent in doing nothing far outweigh the risks of action on the basis of preliminary results. 85 5.0 SOME ECONOMIC CONSIDERATIONS OF FOREST LAND  REHABILITATION 5.1 Introduction As discussed in the previous chapters, forest harvesting operations have been shown to be p r i n c i p a l agents in forest s o i l degradation. This site degradation, arising from accelerated s o i l e r o s i o n , s c a r i f i c a t i o n , and/or s o i l compaction, adversely affects both the physical and chemical properties of the s o i l . The result may be the t o t a l loss of s i t e productivity for the next rotation, as i s the case with most landslides and landings, or reduced productivity, as with skid roads. Either way, the loss of forest productivity through s o i l degradation, even i f small, can have an effect on the forest sector many times greater than the proportion of productivity lost. When accessible, good-site land is removed from production, forest development is increasingly forced into marginal areas with higher operational costs and lower yield (B.C. Ministry of Forests, 1980c). Any reduction in the forest land base, whether through direct land alienation or incurred through reduced productive c a p a b i l i t y , means a reduction in the forest harvesting levels. Future harvesting schedules and m i l l commitments may have to be adjusted downward. Employment and government revenues w i l l 86 subsequently suffer. The Ministry of Forests p o l i c i e s regarding landing construction and r e h a b i l i t a t i o n (already e x i s t i n g ) and reductions in site disturbance (Planning Branch proposal) begin to address the problems of site degradation and loss of production, but establishment of workable r e h a b i l i t a t i o n guidelines and procedures i s needed. Of equal importance, a fi n a n c i a l commitment must be made to the r e h a b i l i t a t i o n of both the newly created and the backlog of degraded forest site in the province. Based on the results reported in Chapter 4 and work in other fields of land reclamation, the recovery of site productivity on degraded soils is possible. The somewhat high cost of r e h a b i l i t a t i o n should be viewed in terms of the costs incurred by the alternative of neglecting the land, and not s o l e l y in terms of f o r e s t investment. It must be remembered that one of the purposes and functions of the Ministry of Forests is (Ministry of Forests Act, 1979): . . . to manage, protect, and conserve the forest and range resources of the Crown, having regard to the immediate and long term economic and social benefits that they may confer on the Province." The remainder of this chapter i s concerned with the economic impacts of forest land rehabilitation. Scenarios of forest land rehabilitation alternatives w i l l be developed for both coastal and interior forests. The costs and benefits of 87 alternatives w i l l be discussed to provide a framework for management decisions. 5.2 A Benefit-Cost Approach to Forest Land Rehabilitation Forest land r e h a b i l i t a t i o n , as with most f o r e s t management a c t i v i t i e s in B r i t i s h Columbia, is financed by public funds. This may involve direct funding through Ministry of Forests expenditures and indirect funding through the stumpage appraisal system or intensive s i l v i c u l t u r e via Section 88 (Forest Act, 1978). Either way, forestry projects must compete not only among themselves for funding but also with other public resource and s o c i a l programs. While the level of funding available to the public sector is set at the p r o v i n c i a l executive l e v e l , the d e c i s i o n as to the disbursement of allocated funds is made within the Ministry of Forests. It i s at the regional (or in some cases d i s t r i c t ) level that selection of forestry projects is generally made. The manager, guided by Ministry policy, must choose among projects based on their associated costs and benefits. To this end, the benefit-cost technique of project evaluation can be of great assistance in problems of forest management spending (Gregory, 1971; Haley, 1966). The benefit-cost analysis i s a method of assessing the economic feas i b i l i t y and competitive position of a potential 88 project in comparison to alternative projects. This analysis is basically a comparison of the benefits of a project to i t s costs. The costs and benefits include primary (direc t ) , secondary ( i n d i r e c t ) , and intangible (mostly of a socia l nature) components. It i s a p a r t i c u l a r l y useful technique when a number of intangible factors are involved (Haley, 1966). These intangible factors, though not measurable by accepted methods, must be taken into consideration in any decision. 5.2.1 Benefit-Cost Procedures for Forest Land Rehabilitation 9 There are three basic steps in carrying out a benefit-cost analysis (Haley, 1966): 1. Definition of a working unit 2. Formulation of alternative management plans 3. Calculation of a benefit-cost ratio for each alternative. The working units for this chapter w i l l be 100 hectare clear cut units (excluding roads) in the Vancouver and Prince George Forest Regions. This size of clearcut, though larger than the 80 ha average for each region, is within the operational range of 50 - 140 ha (B.C. Ministry of Forests, 1980a). Stand c h a r a c t e r i s t i c s , stumpage prices, and operational costs are 89 based on regional averages. The management alternatives considered w i l l be land r e h a b i l i t a t i o n or no action. A l l assumptions and cost data come from Chapters 3 and 4 or from operational t r i a l s carried out by the Ministry of Forests Research Branch. An additional alternative of planting the clearcut w i l l be included for comparison of primary benefits/primary costs. The c a l c u l a t i o n of a b e n e f i t - c o s t r a t i o for each alternative should take the following form (Haley, 1966): Primary benefits + Secondary benefits + Intangible benefits Primary costs + Secondary costs + Intangible costs For this discussion, only a primary benefit-cost ratio w i l l be considered. * Secondary and intangible components, which are di f f i c u l t to properly value w i l l be discussed together based on McKillop (1978). Since the primary benefit-cost ratio is to be calculated in 1984 d o l l a r s , some assumptions regarding future stumpage prices must be made and a discount rate selected. The selection of these values i s very important in this or any other economic analysis, especially when long time periods are involved. The choices used in this discussion are based on those used in other studies. A review of some pertinent l i t e r a t u r e estimating stumpage price increases displayed a range from no real increase (Marty & Newman, 1969) to 3-90 5%/year (Hair, 1971). Recent studies on the economic impact of s o i l compaction in the U.S. used a real rate of 3%/year (Elwood, 1983) and approximately 2.5%/year (Garland, 1983). Such estimates may be overly optimistic for British Columbia, where logging costs are increasing while wood quality and product markets are decreasing. Therefore, both an optimistic rate of 3%/year and a pessimistic rate of 0%/year w i l l be used for projected stumpage increase. A review of l i t e r a t u r e regarding the selection of an appropriate discount rate revealed not only a wide range of rates but also much controversy. Foster (1979) and Gregory (1971) provide e x c e l l e n t reviews of the discount rate controversy. B a s i c a l l y , there are two major schools of thought: opportunity cost of c a p i t a l or s o c i a l time preference (Manning, 1977). The argument for using the opportunity cost of cap i t a l i s based on the fact that the money used for government projects is removed from the private sector by taxes and borrowing should be judged against private sector investment opportunities at an unadjusted rate of 10 -17% (Foster, 1979). The proponents of social time preference argue that public investments are undertaken for current and future social benefit and should be discounted at lower rates around 3 - 5%. There are also those who advocate different rates based on the length of the project with higher rates for 91 short-term planning and lower rates for long-term strategic planning (Foster, 1979; Manning, 1977; and Teeguarden, 1976). For the purpose of this discussion, two discount rates w i l l be used. A low discount rate of 2 % per year (adjusted for i n f l a t i o n ) r e f l e c t s the social time preference rate and a higher real rate of 6% which approximates (once adjusted for the difference between U.S. and Canadian rates) the interest rate used by the U.S. Forest Service for investment studies (Row et a l . , 1981). 5.2.2 Assumptions for Degraded and Rehabilitated Forest Soil To assess the economic implications of forest land reclamation, one must attempt to quantify both the yield loss due to s o i l d e g r a d a t i o n and the r e c o v e r y due to r e h a b i l i t a t i o n . Only a few studies have t r i e d to quantify forest productivity losses due to s o i l degradation, and the majority of these deal with skid road compaction. Aside from the studies reported in Chapter 4, the economic assessment of the recovery of forest production due to r e h a b i l i t a t i o n a c t i v i t i e s has p r i m a r i l y been confined to e i t h e r s o i l decompaction or mined land reclamation. A problem encountered in the quantification of loss or recovery of forest productivity i s the projection of volume estimates from immature stands to f i n a l harvest. The 92 conditions that cause yield reductions may be outgrown (e.g., surface soi l compaction) or benefits from rehabilitation may be only temporary (e.g., nutrient accumulation). Wert and Thomas (1981) quantified a volume reduction, due to skid roads, of 11.8% on a Douglas-fir stand 32 years after tractor logging. However, stocking v a r i a b i l i t y , competition, and uncertainty regarding future growth of affected trees make f i n a l stand yield estimates somewhat tenuous. However, for the purpose of t h i s chapter, i t w i l l be assumed that reductions or gains measured at anytime during stand development w i l l continue unchanged to final harvest. Yield Reduction Assumptions Volume loss due to skid road construction has received the most study of any of the causes of f o r e s t s o i l degradation. Estimates vary from complete loss of volume, i.e., 1% volume loss prorated over the entire clearcut for each 1% skid road (MacLeod, 1983, unpublished), to growth enhancement on cool, coarse soils in the Nelson Region (Smith and Wass, 1979). However, based on reviews by Perry (1964), Froehlich (1979), Smith and Wass (1979), and MacLeod (1983, unpublished), a prorated volume reduction of 0.5% for each 1% of skid roads in a clearcut w i l l be used in this chapter as best summarizing the available data. 93 The assumptions concerning the loss of productivity from accelerated s o i l erosion and construction of landing areas are more straightforward. Based on the survey of 45 forest harvesting induced landslides on the Queen Charlotte Islands by Smith et a l . (1983), where landslides had reduced conifer basal area and were dominated by Alnus rubra (Bong.), i t w i l l be assumed that these areas w i l l not contribute to the merchantable forest volume for one rotation. Using the conclusions of Chapter 3, a l l landing areas w i l l also be assumed to be non-productive for the next rotation. No attempt w i l l be made to carry projected volume reductions for more than one rotation. Assumptions Regarding Volume Recovery Due to  Rehabilitation The assumptions regarding the recovery of f o r e s t productivity following rehabilitation activities are primarily based on Chapter 4. For landslides and other areas subject to accelerated erosion, grass-legume establishment w i l l be considered an adequate treatment to halt continual erosion (Carr & Ballard, 1980) and to restore f u l l productivity for the current rotation within five years (Chapter 4). Landing areas w i l l be assumed to need both decomposition and legume establishment based on Chapter 3. Although ripping did result in successful seedling establishment in Vanderhoof, growth 94 response to the legume seeding for further site enhancement is expected. Berg (1975) found increased tree growth in New Zealand from deep r i p p i n g of compacted s o i l s and f e r t i l i z a t i o n . Although skid road r e h a b i l i t a t i o n was not tested in Chapter 4, a rehabilitation scheme can be devised. The inner track, mid-road, outer track, and berm comprise the running surface of skid roads and occupy approximately 50% of the area disturbed (Smith and Wass, 1979). This p o r t i o n of the skid road has been subject to an increase in so i l density and, based on the numerous skid road studies previously mentioned, must be decompacted before satisfactory tree growth i s possible. Additionally, the entire skid road i s assumed to have been subject to scalping, and revegetation with legumes as a green fallow w i l l also be viewed as necessary for recovery of productivity. Costs of Rehabilitation The costs associated with forest land rehabilitation are based on operational t r i a l s conducted by the Ministry of Forests. These t r i a l s were contracted out and r e f l e c t the true operational cost to the Ministry of Forests. These costs could be reduced i f larger programs were undertaken, but this has yet to be the case within the Ministry. 95 The costs incurred during rehabilitation of coastal areas B.C. subject to accelerated erosion are: a. $900/ha for grass-legume establishment by hydraulic seeding (Carr, 1983 - Interim Report E.P. 834-02, unpublished). b. $260/ha for tree planting (B.C. Ministry of Forests, 1983). The costs of r e h a b i l i t a t i n g landings and skid roads in the interior are: a. $300/ha for deep ripping (Salewski, 1980 - Report G-09-29, Vanderhoof Forest Region, unpublished); b. $450/ha for legume establishment by broadcast seed application (Carr, 1981 - Interim Report E.P. 834-07, unpublished); c. $260/ha for tree planting (B.C. Ministry of Forests, 1983). Ripping i s required for a l l landing areas, but only the running s u r f a c e of s k i d roads r e q u i r e t r e a t m e n t s (approximately 50% of the total skid road area). 96 5.3 Benefit-Cost Analysis For Forest Land Rehabilitation Scenarios 5.3.1 Working Unit Description Coastal Forest The coastal stand to be analyzed is based on the average stand for the Vancouver Forest Region B.C. (Ministry of Forests 1980a). For s i m p l i c i t y , the 100 ha c l e a r c u t (excluding roads) w i l l be expected to regenerate to the current regional species mix of western hemlock (39%), western red cedar (21%), balsam (30%), and Douglas-fir (17%). The average mean annual increment (MAI) i s 4.3 m^/year (B.C. Ministry of Forests, 1983). The age at harvest w i l l coincide with the culmination of the MAI and for this average stand w i l l be 75 years. A stand stumpage price (weighted by species), based on average stumpages over the five year period 1979-1983, i s $8.09/m3. Current logging costs for the stand totals $55/m3 (based on 1984 logging costs in the Vancouver watershed). If left to natural regeneration, only 68% of the stand w i l l be s a t i s f a c t o r i l y stocked while planting w i l l result in 87% satisfactory stocking (B.C. Ministry of Forests, 1983). 97 Interior Forest The interior stand to be analyzed is based on the average stand for the Prince George Region (B.C. Ministry of Forests, 1980a). For simplicity, the 100 ha clearcut (excluding roads) w i l l regenerate the current regional species mix of spruce (55%), lodgepole pine (32%), and balsam (8%) with a MAI of 1.9 m 3/ year. The selected age of harvest w i l l be 100 years. A stand stumpage price (weighted by species), based on average stumpage prices over the five year period 1979-1983, i s $5.25/m3. Current logging costs for the stand are approximately $17.50/m3 (based on 1984 data from Takla Logging in Fort St. James). Natural regeneration of stands in the Prince George Region averages 45% satisfactory stocking, while planting averages 82% (B.C. Ministry of Forests, 1983). 5.3.2 Alternative Management Plans  Coastal Forest The management a l t e r n a t i v e s are r e h a b i l i t a t i o n of degraded f o r e s t land or no r e h a b i l i t a t i o n . If no rehabilitation measures are undertaken, 1% of the productive land base (1 ha) w i l l be lost from the next rotation due to accelerated erosion (Chapter 2). If r e h a b i l i t a t i o n i s undertaken, then f u l l recovery of production is expected. The 98 cost of rehabilitation (green fallow crop establishment plus tree planting) for the working unit is $1,160. For comparison, a management alternative for a 100 ha stand of planting or natural generation w i l l be analyzed in a s i m i l a r manner. Based on r e g i o n a l averages, natural regeneration w i l l result in only 68% satisfactory stocking and planting w i l l result in 87% satisfactory stocking. For this example, a s i m p l i f i e d assumption that only s a t i s f a c t o r i l y stocked areas w i l l contribute to the f i n a l harvest w i l l be made. The cost of planting for the Vancouver Region i s $260/ha (stand to t a l $26,000). Site preparation before planting w i l l not be viewed as necessary. Interior Forest The i n t e r i o r forest stand w i l l be assumed to have been clearcut logged using ground-based equipment. The resulting 4% of the area in landings and 16% in skid roads (skid roads only produce 50% of potential volume) w i l l result in a net 12% loss of forest productivity for the next rotation. Once again, the management alternatives are rehabilitation or no r e h a b i l i t a t i o n . If r e h a b i l i t a t i o n measure are undertaken, then f u l l recovery of productivity w i l l be expected. The cost of rehabilitation for landing areas (deep ripping plus green fallow crop establishment plus conifer planting) is $l,010/ha. 99 The cost for skid roads (where only the running surface i s deep ripped) is $860/ha. The total cost for 'rehabilitation of degraded forest land within the working unit is $17,800. For comparison, a management a l t e r n a t i v e for the regeneration options of planting or natural regeneration w i l l be analyzed. Based on regional averages and the simplistic assumption that only s a t i s f a c t o r i l y stocked areas w i l l contribute to the fina l harvest, naturally regenerated areas w i l l be only 45% f u l l y stocked and planted areas 82% f u l l y stocked. The t o t a l cost for planting of the 100 ha working unit is $26,000. 5.4 Calculation of Benefit-Cost Ratios Detailed worksheets of the benefit-cost ratios for the interior and coastal management alternatives can be found in Appendices S and T. A summary f o r both o p t i o n s , rehabilitation and planting, w i l l be presented below. It must be emphasized that the analyses performed in this section cover only the primary costs and benefits. The scenarios have been simplified to aid in discussion of the options and should not be taken out of the context of the stand assumptions. 100 5.4.1 Coastal Forest The net production loss due to erosion in this stand is 1 ha or 322 m3 at 75 years. The projected real stumpage at that time is $8.10/m3 or $74.35/m3, based on 0% and 3% increase per year respectively. (For convenience, the f i r s t value in each given pair w i l l be based on the 0%/year stumpage increase and the second based on the 3%/year increase.) The d i f f e r e n t i a l stand value of r e h a b i l i t a t i o n i s $2,608 or $23,941. The present value of the difference at a discount rate of 2% i s $536 or $4,917, and $32 or $300 at a rate of 6%. The cost of stand r e h a b i l i t a t i o n i s $1,160, resulting in, a benefit-cost ratio of 0.46 or 4.24 at a 2% discount rate and 0.03 or 0.26 at a 6% discount rate. It would appear that in this example, from a pecuniary standpoint, r e h a b i l i t a t i o n i s economically feasible only at a discount rate of 2% when projected stumpage values increase at 3%/year. In the other three combinations, one would reject r e h a b i l i t a t i o n since their B/C < 1. This also exemplifies the extreme sensitivity of such analyses to chosen discount interest rates and projected value increases. For comparison, increased yield expected due to planting of the stand i s 19% or 6,127 m3. The present value of this difference i s $10,195 or $93,584 (based on a stumpage increase of 0% or 3% per year respectively) using a 2% discount rate and $622 or $5,713 using a 6% discount rate. With a stand 101 planting cost of $26,000, the benefit-cost ratios are 0.39 or 3.60 and 0.05 or 0.21, respectively. The result obtained i s similar to the rehabilitation option, planting being feasible only in the 2% discount rate and 3%/year stumpage increase option. Further, the higher b e n e f i t - c o s t r a t i o of the re h a b i l i t a t i o n option for that combination suggest that a higher priority should be given to rehabilitation. 5.4.2 Interior Forest The productivity loss due to landing and skid road c o n s t r u c t i o n i s equivalent to 12%, r e s u l t i n g in a net productive stand of 88 ha. At a projected stumpage of $5.25/m3 or $100.90/m3 in the year 2084, based on a 0%/year and 3% year increase, the value loss i s $1 1,970 or $230,052. The present value of this loss at a 2% discount rate is $1,654 or $31,793 for stumpage projections of 0%/year and 3%/year, respectively. At a discount rate of 6%, the present value would be $39 or $748. With a stand r e h a b i l i t a t i o n cost of $17,800, the benefit-cost ratio for the 2% discount rate i s 0.09 or 1.79, and 0.002 or 0.042 for the 6% discount rate. As in the cost forest example, r e h a b i l i t a t i o n i s economically feasible only in the favorable combination of the lower discount rate and higher projected stumpage increase. 102 For comparison, a gain of 37% from planting increases the projected stand yield by 7.030 m 3. Following the procedure for benefit-cost ratio c a l c u l a t i o n , at the 2% discount rate, the benefit-cost ratio is 0.20 or 3.77 (based on 0% or 3%/year stumpage increases) and 0.005 or 0.088 at the 6% discount rate. Planting i s only economically feasible at the most favorable discount rate-stumpage increase combination, as has been the case in a l l previous examples. However, unlike the coast forest scenario, planting has the higher benefit-cost ratio and should be given priority over rehabilitation. 5.4.3 Discussion From a primary benefit-cost viewpoint, coastal forestry appears to be the better option for investment into rehabilitation than the interior based on comparative benefit-cost r a t i o s . Although the discount rate and stumpage value increase assumptions are c r i t i c a l to any decision, the shorter return period (75 versus 100 years), combined with the higher wood value and larger yield per hectare, favors the coast. In the planting option, these factors are offset by a greater volume increase in the interior, 37% versus 19% for the coast. As a result, the benefit-cost ratios for planting are similar. 103 5.5 Some Secondary and Intangible Benefits and Costs of  Forest Land Rehabilitation The major problem plaguing benefit-cost analyses is the proper valuation of the secondary and intangible components. The intangible components, by definition, are not measurable by accepted methods (Gregory, 1972). With secondary components, there i s often d i f f i c u l t y with valuation and uncertainty in the fruition of benefits or costs attributable to a project. For this reason, secondary and intangible components of the benefit-cost analyses undertaken in this chapter are considered separately and often require a subjective appraisal of value. The benefits that accrue from forest land rehabilitation can best be defined as not incurring the costs of losing timber land from production. These costs can be assessed at the various levels at which they affect the industry, i.e. national, provincial (state) or local level, and in regard to the following c r i t e r i a (McKillop, 1978): a. loss in timber harvest and processed wood b. effect on employment, both direct and indirect c. loss of government revenue d. effect on industry markets For this discussion, the impacts w i l l be discussed only at the 104 forest region and timber supply area levels with no attempt to assess directly the effects on a provincial or national level. Additionally, no attempt w i l l be made to assess the impact of forest land rehabilitation on timber markets. Forest harvesting rates in British Columbia are currently based on resource analyses that determine timber supply problems within the province (B.C. Ministry of Forests, 1980a). This procedure simulates the long-term consequences of a chosen harvesting rate with the sustainable yield as the basis for management decisions. The sustainable yield is the volume of harvest that can be sustained from productive forest sites with only basic s i l v i c u l t u r a l treatment (B.C. Ministry of Forests, 1980a). One assumption in the analysis i s that the productive capability of logged sites w i l l be maintained (B.C. M i n i s t r y of F o r e s t s , 1983c). As discussed and demonstrated in Chapter 2, t h i s i s not r e a l i s t i c . Any reduction in the forest land base, either direct or indirect, means a reduction in the rate of harvest (Young, 1981). 5.5.1 Vancouver Forest Region—Effects on Timber Harvest,  Employment and Government Revenue Based on the Forest and Range Resource Analysis Technical Report (B.C. Ministry of Forests, 1980a), the net productive forest land base is 3.2 m i l l i o n hectares with a long-run sustained yield (LRSY) of 4.8 m i l l i o n cubic meters per year. 105 Using the assumption of a 1% loss of productive forest land due to erosion of logged sites over the rotation, the net land base would be lowered by 32,000 ha and the LRSY by approximately 50,000 m3. This change in the harvest level can have a profound effect on the forest industry. The lowering of the LRSY by 1% in the Vancouver Region would be c r i t i c a l in most of the timber supply areas. The Quadra TSA currently has a commitment of 1.86 million m3 per year for the next 20 years (B.C. Ministry of Forests, 1980c). With a LRSY of 1.96 m i l l i o n m3, this commitment can only be met i f land losses are kept down, otherwise resistance to land alienation for other purposes would increase, as would the pressure to log economically marginal or environmentally sensitive sites. The situation in the Fraser TSA is even more c r i t i c a l . The current commitment of 1.64 million m3 cannot be met since the LRSY i s only 1.46 m i l l i o n m3 (B.C. Ministry of Forests, 1980b). The d e f i c i t expected at current harvest levels w i l l be hastened by erosion losses. The continued eff i c i e n c y and p r o f i t a b i l i t y of regional processing plants would be in greater jeopardy. Using the Council of Forest Industries (1981) estimate that 130 ha of average forest land supports one direct forestry job and the generally accepted m u l t i p l i e r of 2 for indirect jobs (Reed, 1973), the loss of 32,000 ha due to 106 erosion represents approximately 246 potential direct jobs and 492 indirect over the rotation. When combined with other expected job losses due to technological advances and shifting markets, the many communities within the VancouverForest Region that are highly dependent on the forest industry w i l l not only experience an increase in local unemployment but also require greater government spending for s o c i a l assistance programs. The inevitable movement of s k i l l e d personnel to other communities or professions may lower industry productivity. Further impacts of loss of community image or community de s t a b i l i z a t i o n may have even greater long-term social consequences. The loss of even a small percentage of jobs can result in severe local problems. The potential loss of taxes from a forest industry based on higher commitment levels than can be sustained and the probable increase in social benefit spending due to higher unemployment w i l l compound government budget problems incurred by a decrease in direct stumpage revenue. In 1982-83, the Vancouver Region accounted for approximately 26 m i l l i o n dollars in net stumpage revenue to the government or 30% of the t o t a l forest revenue. Even a small loss in net stumpage from the Vancouver Region can have a relatively large effect on a provincial revenue that is highly dependent on the forest industry. 107 5.5.2 Prince George Forest Region — Effects on Timber  Harvest, Employment, and Government Revenue The intangible (and secondary) costs incurred in the Vancouver Region due to loss of forest production would, for the most part, be greater in the Prince George Region. The higher assumed loss of 12% due to erosion, s c a r i f i c a t i o n , and/or compaction would be applied to a larger forest region where nearly twice as much area is annually harvested. The Prince George Forest Region (minus the Peace River Area) has a net productive land base of 7.3 m i l l i o n hectares and a LRSY of 6.0 million m3 (B.C. Ministry of Forests, 1980). The loss of 12% of the productive land base would eliminate approximately 2025 f u l l - t i m e jobs (675 d i r e c t l y and 1350 indirectly) over a rotation. In a region so dominated by the forest industry, the impacts on social assistance programs, local unemployment, and community stability could be immense. The equivalent lowering of the LRSY d r a s t i c a l l y affects not only the p r o f i t a b i l i t y but also the operability of many processing plants. A regional deficit is already expected in about 60 years and a decrease in LRSY would accentuate the problem (B.C. Ministry of Forests, 1980a). The loss of future taxes and increased social assistance spending would be accompanied by a decrease in forest revenue (approximately $900,000 based on 1982-883 net stumpage revenue). The 108 budgetary problems of the government wil l probably increase i f forest land r e h a b i l i t a t i o n i s not undertaken or intensive s i l v i c u l t u r a l measures implemented to recover l o s t productivity. 5.5.3 Additional Intangible Benefits Aside from the intangible and secondary components of f o r e s t land r e h a b i l i t a t i o n discussed in the preceding sections, a few other intangible aspects are noteworthy. F i r s t , erosion control i s a side benefit gained in the land rehabilitation schemes put forth in this thesis. Erosion from forest land has received a great deal of attention over the past decade. The potential impact of sedimentation on community or residential water supply was a primary cause for re-evaluation of the proposed logging plans for the Blewett Watershed in the Nelson Region. Concern for the potential impacts of erosion on the salmon resource on the Queen Charlotte Islands prompted the establishment of the Fish Forestry Interaction Program. Forest land rehabilitation can alleviate much of the public concern regarding s o i l erosion. A second benefit i s the enhanced public image of the forest industry. To a public indoctrinated with forest f i r e protection, resource protection, the need to harvest forests instead of create parks, etc., the existence of landslide and 109 erosion scars or large tracts of denuded and compacted s o i l in clearcuts presents a conflicting image of forestry. This can result in public distrust and opposition to further logging expansion. Areas may be excluded from development or logging plans greatly restricted, the results of which would adversely a f f e c t the f o r e s t i n d u s t r y . For an industry that i s intimately associated with the general public, and whose operations and funding are government directed, a positive p u b l i c image i s of great i m p o r t a n c e . F o r e s t land r e h a b i l i t a t i o n can greatly assist the industry image by removing one of the most v i s i b l e negative aspects of forest harvesting. 5.6 Alternative Considerations in Forest Land Rehabilitation 5.6.1 Rehabilitation as an Operational Cost Instead of viewing forest s o i l r e h a b i l i t a t i o n from a forest investment standpoint, i t could be regarded as a part of logging within the protection or clean-up phases. In this manner, funds for rehabilitation would then be made available through the stumpage appraisal system. Although immediate revenue in the form of net stumpage receipts would be lower, the problem of interest or discount rates would not be a factor in management decisions. Additionally a minor increase 110 in logging costs for resource protection would be easier to justify than investing money in the rehabilitation of small, isolated degraded s i t e s . The current stumpage appraisal system does contain p o s s i b l e avenues for i n c l u s i o n of r e h a b i l i t a t i o n costs. In the Vancouver appraisal manual, Section C-4: Erosion c o n t r o l of Phase Cost 2-9: Road Maintenance (B.C. M i n i s t r y of F o r e s t s , 1983b) i s a possibility. Section 5.21: Ripping of landings and roads and 5.22: Grass seeding of the Kamloops appraisal manual (B.C. Ministry of Forests, 1984) could be used together for landing and skid road rehabilitation. Erosion, more often than loss of forest production, i s often the primary problem associated with severely degraded s o i l in coastal forestry. Concern for the impact of erosion on water quality and f i s h e r i e s values prompts more action within a l l levels of forestry administration in B r i t i s h Columbia than the loss of a relatively small amount of forest to landslides. However, i t i s fortunate that the same basic system of revegetation can be used to solve or alleviate both problems. Using the Vancouver Forest Region — Appraisal G__u 1 d_£ (B.C. M i n i s t r y of F o r e s t s , 1983b), t o t a l maximum allowance for erosion control on a 100 hectare stand would be approximately $44,550 i f the entire road system required erosion control. Based on the average coastal stand of Chapter 5.3.1., the maximum allowance would be $0.14/m3. The I l l estimated r e h a b i l i t a t i o n cost in the scenario i s $1,160 for the stand or $0.04/m3. The cost of r e h a b i l i t a t i o n could easily be absorbed within the erosion control cost provided the entire road system did not warrant erosion control measures. The cost of r e h a b i l i t a t i o n would cause an approximate increase in logging costs of 0.07% (based on $55/n_3). With the benefits of r e h a b i l i t a t i o n (Chapter 5.5.) and the almost n e g l i g i b l e increase in logging c o s t s , rehabilitation of severely degraded coastal forest soi l is a viable management alternative (as i t was in Chapter 5.4.1 with a 2% discount rate). The use of the stumpage a p p r a i s a l approach for rehabilitation of degraded interior forest soi l does l i t t l e to promote a favorable management decision. In the Appraisal  Manual — Kamloops Region (B.C. Ministry of Forests, 1984), a standard allowance of $0.03/m3 i s given for ripping of landings and roads, and $97.30/ha for grass seeding of scarified areas. Assuming similar allowances for the Prince George Region, the average i n t e r i o r stand would be allowed $570 for ripping and $1,950 for seeding ($2,520 t o t a l or $0.13/m3). Although ripping and seeding are the pri n c i p a l components in the rehabilitation scenario approximately $3,600 is needed for landing (4 ha) and skid road (8 ha) ripping with an additional $9,000 for legume seeding (total $12,600, not 112 including tree planting). Based on 190 m-Vha, the allowance would have to be $0.66/mJ for the stand, not $0.13 /mJ as currently allowed. The ripping allowance alone would have to be $0.18/m3. The required ripping and seeding would increase logging costs approximately 3.8% (based on $17.50/m3 logging cost in Fort St. John). To f u r t h e r detract from the r e h a b i l i t a t i o n option, the calculated stumpage for the i n t e r i o r stand (based on 1984 Takla logging data) i s approximately $7.46 for pine and $8.33 for spruce. As with much of the i n t e r i o r , minimum stumpage (or 3% of s e l l i n g price) i s charged and any additional costs must be borne by the company. The justification for rehabilitation of degraded i n t e r i o r forest s o i l s must rely heavily on the intangible benefits. Based on the existence of landing construction and rehabilitation policy, such a decision has been made but the costing procedure appears to be lacking. If the Ministry of Forests' goal in such a p o l i c y i s maintenance of the production forest base, adequate guidelines and funding must be made available. 5.6.2 Recovery of Lost Productivity Through Intensive  Silviculture Restoring productivity on severely degraded forest soils i s operationally f e a s i b l e , though in some cases r e l a t i v e l y expensive. Economic j u s t i f i c a t i o n i s dependent on heavy 113 reliance on intangible benefits, particularly in the interior f o r e s t scenario. Intensive s i l v i c u l t u r e provides an alternative method of recovering stand productivity lost through s o i l degradation. A higher yield from non-degraded soils may be used to offset potential losses. Basic s i l v i c u l t u r a l measures are those which maintain the forest resource base, while the objective of intensive s i l v i c u l t u r e i s to enhance the resource. A c t i v i t i e s undertaken as part of an intensive s i l v i c u l t u r e program are (B.C. Ministry of Forests 1980a): Backlog planting - where man's assistance is required to generate a desired forest stand in an acceptable time period; Spacing - which concentrates on the selection of p o t e n t i a l superior trees and the removal of the less valuable trees; Fertilization - e x p e c t e d to promote a r a p i d a c c e l e r a t i o n in growth on s i t e s deficient in one or more available nutrient elements; Site rehabilitation - employed in the conversion of forest areas occupied by non-commercia1 spe c i e s , to a stage prepared for restocking by a suitable species; 114 Conifer release - to remove undesirable and competitive plant growth from a stand; Thinning - further removal of trees that hinder the growth of superior trees and the conversion of the harvest into forest products. The benefits of intensive forestry are increased wood volume and value, as well as provision of employment opportunities. The size of the yield increase is highly variable and stand-dependent. Considerable research has been, and w i l l continue to be, undertaken to identify suitable stands and optimum levels of treatment. Barrett (1980) provides an excellent review of s i l v i c u l t u r a l practices suitable for various forest types. A comparison of options for the r e h a b i l i t a t i o n costs in the previous scenarios reveals the following. To rehabilitate degraded s o i l on the coast w i l l cost $1,160 per 100 ha stand. Based on 1982-83 costs in the Vancouver Region (B.C. Ministry of Forests, 1983a), expenditure of that amount on intensive silviculture would allow the following options: Backlog planting - approximately 4.5 ha or Spacing - approximately 1.8 ha or Fertilization - approximately 5.1 ha or 115 Site rehabilitation - approximately 1.2 ha or Conifer release - approximately 2.3 ha or some combination of the above. If the forest manager was w i l l i n g to forgo some of the intangible b e n e f i t s , p a r t i c u l a r l y erosion c o n t r o l , and expected volume increase from one or a combination of the options offset the projected 1% loss, intensive silviculture would be a viable alternative to s o i l r e h a b i l i t a t i o n . A s i m i l a r argument could be used for the i n t e r i o r s o i l rehabilitation scenario, where the $17,800 (based on 1982-83 interior regional costs) could be used for: Backlog planting - approximately 70 ha or Spacing - approximately 68 ha or Site rehabilitation - approximately 72 ha or Conifer release - approximately 36 ha or some combination of the above. Enhancement of productivity to offset the equivalent 12% loss from the 100 ha stand would require spacing to improve the yield by approximately 18% or conifer release by 33%. A benefit-cost analysis for the various alternatives would be a useful tool for the forest manager in making such a decision. 116 5.7 Summary and Conclusions The objectives„of this chapter were to develop re a l i s t i c forest s o i l r e h a b i l i t a t i o n scenarios for both coastal and in t e r i o r forest stands and to outline the various economic c o n s i d e r a t i o n s . Chapter 4 has shown that r e s t o r i n g p r o d u c t i v i t y of degraded f o r e s t s o i l i s o p e r a t i o n a l l y f e a s i b l e . However, the economic j u s t i f i c a t i o n of the operation from an investment standpoint i s questionable. Calculation of a direct benefit-direct cost ratio indicated that r e h a b i l i t a t i o n was a favorable option only when a 2% discount rate and 3% annual stumpage increase were assumed. The advantage of benefit-cost analysis is that i t allows for inclusion of intangible factors for subjective valuation within the decision-making process. It would be the secondary and intangible benefits that j u s t i f y forest investment into rehabilitation, and not the pecuniary aspects. Avenues exist for inclusion of so i l rehabilitation costs within the appraisal system as a logging cost. Coastal s o i l r e h a b i l i t a t i o n could easily be covered within the current system, but allowances for interior s o i l rehabilitation must be increased i f Ministry policy regarding landings and skid roads i s to be carried out. Even with that, operators on minimum stumpage might r e s i s t s o i l r e h a b i l i t a t i o n due to increased logging costs. If forest so i l rehabilitation is to 117 be practiced, adequate funding must be made available from the Ministry, either d i r e c t l y or in a more equitable indirect manner. The recovery of lost productivity through intensive s i l v i c u l t u r e as opposed to degraded s o i l r e h a b i l i t a t i o n should be considered in the decision-making process. This is especially true in the i n t e r i o r where high r e h a b i l i t a t i o n costs could provide funding for a substantial intensive si l v i c u l t u r a l program. The recovery of forest productivity on s o i l s severely degraded by harvesting operations'should be a primary consideration of the Ministry of Forests. The mandate to preserve and protect the forest resource exis t s , as do forestry p o l i c i e s aimed at preventing the degradation of forest land. However, operationally feasible guidelines must be developed and adequate funding provided. Failure to do so w i l l allow for the incurrence of the f i n a n c i a l and social costs resulting from a reduced land base. The "internal" alienation of the forest land base cannot be allowed to continue i f forestry is to maintain i t s position as British Columbia's industrial leader. 118 6.0 CONCLUSION Forest road building and timber harvesting operations have been recognized as pr i n c i p a l causes of forest s o i l degradation. These a c t i v i t i e s , which can r e s u l t in accelerated s o i l erosion, excessive scarification, and/or soi l compaction, adversely affect so i l properties resulting in site degradation and lost productivity. Although the mandate exists to protect and conserve the forest land base, specific policies and operational guidelines are needed. Accelerated erosion from harvested forest land, which can affect from 0.5 to 2.0 percent of roaded and clearcut area, can result in lost forest productivity due to the removal of nutrient r i c h surface s o i l horizons as well as adversely affecting other forest resources. The construction of skid roads and landings, which can occupy 16-32% and 4-5% of cutover lands, respectively, not only have surface s o i l removed but are also subject to increased s o i l density. Once again, loss of site productivity can r e s u l t . Management a c t i v i t i e s must address the problems of erosion control, nutrient depletion, and increased soi l density. Skid roads have received world wide attention with regard to increased s o i l density and i t s effect on s o i l physical properties and tree growth. Landing areas, though subject to larger increases, have been the subject of a few studies. The 119 effect of landing or skid road construction on s o i l nutrient levels has only been alluded to but never quantified. A study of landings near Fort St. James revealed that while summer landings were more dense than winter landings, both exceeded a bulk density of 1400 kg/m3 which i s recognized as a level adversely a f f e c t i n g f o r e s t productivity. Additionally, compaction was s t i l l evident at the 20- to 30- cm depth in both types of landings, i n d i c a t i n g the need for s o i l decompaction to a depth greater than the already recommended 30 cm. S o i l nutrient quality on the landings also suffered due to scarification during construction. The s o i l nitrogen, available phosphorus, and available potassium concentrations were substantially lower following construction. The nitrogen and phosphorus levels were more severely affected by removal of surface horizons than s o i l potassium. Although the landings were generally well-stocked with lodgepole pine, height growth suffered. Tree growth loss was greater on summer (46%) than winter (30%) landings six years after logging. However, eleven years after logging, growth loss was nearly equal (approximately 60%) on summer and winter landings. Landing areas cannot be expected to contribute to the future merchantable timber volume unless both the s o i l density and nutrient problems are solved. Revegetation of denuded soils with legumes and grasses is not only one of the most effective methods of erosion control 120 but also of enhancing s o i l physical and chemical properties. The use of grasses and legumes as a green fallow i s widely practiced in agriculture and in mined land reclamation. The use of a green fallow as part of forest s i t e r e h a b i l i t a t i o n measures was tested on a coastal forest s o i l that had been subjected to accelerated erosion and on an i n t e r i o r forest soil that had been subjected to landing construction. In the coastal study, substantial enhancement of site nutrient capital occurred within five years. The nitrogen, phosphorus, and potassium pools a l l benefited greatly from the green fallow. Nitrogen showed the greatest gain (890 kg/ha), primarily due to the abundance of legumes in the revegetation cover. Douglas-fir seedlings responded with improved foliar nitrogen and potassium concentrations and a 300% increase in height growth. In the interior study, decompacted landings were treated with broadcast a p p l i c a t i o n of a legume seed mix and f e r t i l i z e r . After only two years, the legume green fallow had improved site nutrient capital. Once again, nitrogen showed the greatest gain (33 2 kg/ha), due to the presence of the legumes. Potassium and phosphorus levels improved to a lesser degree. Although seedling foli a r nutrient concentration and seeding height growth had not increased, the t o t a l s o i l N concentration exceeded minimum levels for adequate growth of 121 medium nutrient-requiring coniferous species. The use of a green fallow system in site rehabilitation for the recovery of productivity was viewed as successful in both the coastal and interior studies. The cost of forest land r e h a b i l i t a t i o n cannot be viewed entirely from a pecuniary standpoint. Benefit-cost analysis of rehabilitation scenarios for both the coastal and interior forest underscored this point. The direct benefit-direct cost r a t i o s were f o r the most part u n f a v o r a b l e toward r e h a b i l i t a t i o n . However, the benefit-cost analysis can be made more meaningful by consideration of secondary and intangible components which require a subjective appraisal of value. The loss of forest land from production has a negative impact on employment, government revenue, and, possibly the most important, timber harvesting l e v e l s . Many of the province's timber supply areas are at a maximum (or over) commitment. Even a small loss of productive land can be c r i t i c a l . Although policies and financing avenues exist for forest land r e h a b i l i t a t i o n , both must be improved. If not, the net product land base w i l l d ecline f o r c i n g f o r e s t development of high-cost - low-yield marginal areas a well as promoting an increase in land use conflicts. LITERATURE CITED Agboola, A.A. 1975. Problems of improving soi l f e r t i l i t y by the use of green manuring in the tropical farming system. FAQ Soil Bulletin, _27, 147-164. Allison, F.E. 1973. Organic Matter and Its Role in Crop  Production. Washington: Elsevier. Anonymous. 1977. Improving the efficiency of ripping. Forest Ind. Review, 8 (8), 28-32. Association of B.C. Professional Foresters. 1983. A Renewable Resource Position on Hydro Dams and Power  Lines — A Report to the Government. (Available from: ABCPF, 510-744 W. Hastings, Vancouver, B.C.) Association of B. C. Professional Foresters. 1980 Defining  Provincial Forests — A Brief to the Cabinet. (Available from: ABCPF, 510-744 W. Hastings, Vancouver, B.C.) Ballard, T.M. 1980a. Some Forest Tree Nutrition Problems in the Kamloops Forest Region. B.C. Ministry of Forests contract report. Vancouver: U.B.C., Dept. of Soil Science and Faculty of Forestry. Ballard, T.M. 1980b. Tree nutrition. In P. F. Ziemkiewicz et a l . (Eds.), Proceedings: Workshop on Reconstruction  of Forest Soils in Reclamation (pp.9-21). Report ±RRTAC 80-4. Edmonton: Alberta Land Conservation and Reclamation Council. Ballard, T.M. 1979. Development of Interim Operational Guidelines for Forest Fertilization in the Kamloops Forest  District. B.C. Ministry of Forests contract report. Vancouver: U.B.C., Department of Soil Sciences and Faculty of Forestry. Barrett, J.A. 1980. Regional Silviculture of the United  States. New York: John Wiley & Sons. Berg, P.J. 1975. Developments in the establishment of second rotation radiata pine at riverhead forest. N.Z.J. For., 20, 272-82. 3 Bishop, D.M. and M.E. Stevens. 1964. Landslides on Logged Areas in Southern Alaska. USDA Forest Service Research Paper NCR-1. Bockheim, J. 1982. Forest soils. In R.A. Young (Ed.), Introduction to Forest Science (pp. 93-111). New York: John Wiley & Sons. B.C. Ministry of Forests. 1984. Ministry policy draft proposal: Reduction of site disturbance from logging  operations. Victoria: B.C. Ministry of Forests, Planning Branch. B.C. Ministry of Forests. 1983a. Report of the Ministry of  Forests. B.C. Ministry of Forests, ISSN 0068-1490. Victoria: Queen's Printer. B.C. Ministry of Forests. 1983b. Vancouver Forest Region —  Appraisal Manual. Vancouver: B.C. Ministry of Forests, B.C. Ministry of Forests. 1983c. Appraisal Manual — Kamloops Forest Region. Kamloops: B.C. Ministry of Forests. B.C. Ministry of Forests. 1982. Statistics Relating to the  B.C. Forest Industry. B.C. Ministry of Forests, Strategic Studies Branch. Victoria: Queen's Printer. B.C. Ministry of Forests. 1980a. Forest and Range Resource  Analysis Technical Report. B.C. Ministry of Forests, ISBN 0-7719-8324-7. Victoria: Queen's Printer. B.C. Ministry of Forests. 1980b. Fraser Timber Supply Area  Summary. B.C. Ministry of Forests, Information Service Branch. Victoria: Queen's Printer. B.C. Ministry of Forests. 1980c. Quadra Timber Supply Area  Summary. B.C. Ministry of Forests, Information Services Branch. Victoria: Queen's Printer. British Columbia Royal Commission on Forest Resources. 1976. Timber Rights and Forest Policy in British Columbia: Volume I. Victoria: Queen's Printer. Burroughs, E.R. Jr., & B.R. Thomas. 1977. Declining Root  Strength in Douglas-fir After Felling as a Factor in  Slope Stability. USDA Forest Service Research Paper, INT-190. Ogden: Intermountain Forest and Range Experiment Station. Canada. 1981. Canada Year Book 1980-81. Ministry of Supply and Services. Ottawa: Queen's Printer. Cannell, R.Q. 1977. Soil aeration in relation to root growth and s o i l management. Appl. Bio., 2\ 1-86. Carr, W.W. & Ballard, T.M. 1980. Hydroseeding of forest roadsides in British Columbia for erosion control. Journal of Soil and Water Conservation, 35 (1): 33-35. Carr, W.W. 1981. Preliminary report: Landing rehabilitation  t r i a l s in Vanderhoof (E.P. 834-07). Unpublished report prepared for the B.C. Ministry of Forests, Research Branch, Victoria. Carr, W.W. 1982. Preliminary Report: The use of J-TAC A.S.  in aerial hydroseeding. (E.P. 834-02-02). Unpublished report prepared for the B.C. Ministry of Forests, Research Branch, Victoria. C a s t i l l o , S.R., Dowdy, R.H., Bradford, J.M. & Larson, W.E. 1982. Effects of applied mechanical stress on plant growth and nutrient uptake. Agron. J., 74, 256-7. Cole, D.W., Turner, J.W. & Bledsoe, C. 1974. Requirements an uptake of mineral nutrients in coniferous ecosystems. In Symp. Below Ground Ecosystem. Fort Collins, Colorado. Fort Collins: Dowden, Hutchison and Ross. Cole, D.W., Gessel, S.P, & Dice, S.F. 1967. Distribution and cycling of nitrogen, phosphorus, and potassium in a second-growth Douglas-fir ecosystem. In Young, H.E. (Ed.), Symposium on primary productivity and mineral  cycling in natural ecosystems (p.197-230). Orono: Univ. of Maine Press. Cotic, I., van Barneveld, J, & Sprout, P.N. 1974. Soils of  the Nechako-Francois Lake Area. B.C. Department of Agriculture, Soils Branch. Victoria: Queen's Printer. Council of Forest Industries. 1981. Forest Land for the Future — Forest Industry Task Force on Forest Land for  the Future. (Available from C0FI, 1055 West Hastings, Vancouver, B. C.) Delong, C. & A. McLeod. 1985. A f i e l d guide for the identification and interpretation of ecosystems of the SBSk2 in the Prince George Forest Region. First approximation, author's draft. Prince George: Ecology Section, B.C. Ministry of Forests. Delong C. & A. McLeod. 1985. A Field guide for the identification and interpretation of ecosystems of the SBSe2 in the Prince George Forest Region. Forest approximation, author's draft. Prince George: Ecology Section, B.C. Ministry of Forests. Dickerson, B.P. 1976. Soil compaction after tree-length skidding in northern Mississippi. Soil Sci. Soc. Am. J. , 40, 965-966. Dyrness, C.T. 1967. Mass Soil Movements in the H.J. Andrews  Experimental Forest. USDA Forest Service Research Paper PNW-42. Portland: PNW Forest and Range Experiment Station. Elwood, N.E. 1983 An economist's f i r s t look at soil compac- tion. Unpublished paper presented at a short course entitled, "Forest Soil Compaction — Problems and Alternatives." Oregon State University, Department of Forest Engineering, La Grande, Oregon. Farstad, L. & Laird, D.G. 1954. Soil Survey of the Quesnel, Francois Lake, and Bulkley-Terrace Areas in the  Central Interior of British Columbia. Report ±4 of the B.C. Soil Survey, B.C. Ministry of Agriculture — Soil Branch. Ottawa: Queen's Printer. Forest Act. 1978. Royal Statute Chapter 140 (27 E l i z . 2). Victoria: Queen's Printer. Foster, B.B. 1979. Multiple discount rates for evaluating public forestry investments. For. Chron., 55, 17-20. Froehlich, H.A. 1973. The impact of even-age forest management on physical properties of soils. In R. Herman & D. Lavender (Eds.). Even-age Management  Symposium. Oregon State University. Corvallis, Oregon. Garland, J.E. 1983. Some economic considerations of soil compaction for uneven-age management. Unpublished paper presented at a short course entitled, "Forest Soil Compaction -- Problems and Alternatives." Oregon State University, Department of Forest Engineering, la Grande, Oregon. Gent, J.A., Ballard, R., & Hassan, A.E. 1983. The impact of harvesting and site preparation on physical properties of Lower Coastal Plain soils. Soil Sci. Soc. Am. J., 47, 595-598. Gimbarzevsky, P. 1983. Regional Overview of Mass Wasting on  the Queen Charlotte Islands. Working Paper WP3/83, Fish Forestry Interaction Program. Victoria: B.C. Ministry of Forests, Research Branch. Gray, D.H. and W.F. Megahan. 1981. Forest Vegetation Removal  and Slope Stability in the Idaho Batholith. USDA Forest Service Research Paper INT-271. Ogden: International Forest and Range Experiment Station. Greacan, E.L. and R. Sands. 1980. Compaction of forest soils — a review. Aust. J. Soil Res., 18, 163-189. Gregory, G.R. 1971. Forest Resource Economics. New York: Ronald Press. Haines, L.W., Maki, T.E., & Sanderford, S.G. 1975. The effects of mechanical site preparation treatments on s o i l , productivity, and tree growth. In Forest Soils  and Forest Land Management, (pp. 379-395). Quebec City: University of Laval Press. Hair, D. 1971. The nature and use of comprehensive timber appraisals. J. of For., 71, 565-567. Haley, D. 1966. An economic appraisal of sustained yield  forest management for British Columbia. Unpublished Ph.D. thesis, Faculty of Forestry, University of British Columbia, Vancouver. Halverson, H.G. & Zisa, R.P. 1981. Measuring the Response  of Conifer Seedlings to Soil Compaction Stress. USDA Forest Service. Research Paper NE-509. University Park: Northeast Forest and Range Experiment Station. Hatchell, G.E., Raltson, CW. & F o i l , R.R. 1970. S o i l disturbance in logging. J. of Forestry, 68, 772-775. Hegyi, F., Jelinek, J., & Carpenter, D.B. 1979. Site Index  Equations and Curves for the Major Tree Species in B.C. Forest Inventory Report ±1, B.C. Ministry of Forests. Victoria: Queen's Printer. s^i Heilman, P. 1981. Root penetration of Douglas-fir seedlings into compacted soils. For. Sci., 27 (4), 660-666. Herring, L.J. & McMinn, R.G. 1980. Natural and advanced regeneration of Engelmann spruce and subalpine f i r compared 21 years after site treatment. For. Chron., 56 (2), 55-57. Hilderbrand, E.E. 1983. (The influence of s o i l compaction on soil functions on forest sites.) Fortwissen Schaftichis  Centralblatt, 102 (2), 111-125. (from English summary). Hinish, W.W. 1980. Soil f e r t i l i t y : The components of high yield. Crops and Soils, 32 (4), 7-10. Holland, S.S. 1964. Landforms of British Columbia: A Physiographic Outline. Bulletin ±48, B.C. Department of Mines and Petroleum Resources. Victoria : Queen's Printer. Jakobsen, B.F. 1983. Persistence of compaction effects in a Forest Kraznozem. Aust. For. Res, 13, 305-308. Keser, N. & St. Pierre D. 1973. Soil of Vancouver Island _^ A Compendium. Research Note No. 56, B.C. Ministry of Forests. Victoria: Queen's Printer. Kimmins, J.P. & Hawkes, B.C. 1978. Distribution and chemistry of fine roots in a white spruce-subalpine f i r stand in British Columbia: implications for management. Can. J. For. Res. 8, 265-279. Klinka, K., Nusdorker, F.C., & Skoda L. 1979. Biogeo- climatic Units of Central and Southern Vancouver Island. B.C. Ministry of Forests. Victoria: Queen;s Printer. Krajina, V.J. 1965. Ecology of Western North America. Vancouver: Department of Botany, U.B.C. Lavkulich, L. 1979. Methods Manual - Pedology Laboratory. Vancouver: Dept. of Soil Science, U.B.C. L i t t l e , T.M. & H i l l s , F.J. 1978. Agricultural Experi- mentation - Design and Analysis. Toronto: John Wiley & Sons. McKillop, W. 1978. Economic costs of withdrawing timber and timberland from commercial production. J. For., 76, 414-417. MacLeod, A. 1983. A pilot study of s o i l compaction on skid  t r a i l s and landings in the Prince George Forest Region. Unpublished report. Research Section. Prince George Forest Region. McLeod, A. & Hoffman, E. 1984. A pilot study of s o i l dis- turbance on selected cutovers in the Prince George Forest  Region. Unpublished report. Research Section, Prince George Forest Region. Mace, A.C., Jr., Williams, T., & Tappeiner, J.C., II. 1971. Effect of Winter Harvesting Methods on Soil Bulk Density and Infiltration Rates. Minn. For. Res., Note 228. Duluth: University of Minnesota Press. Manning, G.H. 1977. Evaluating public forestry investments in British Columbia. For. Chron, 55, 155-158. Marty, R. & Newman, W. 1969. Opportunities for management intensification on the national forests. J. For., 67, 482-485. Megahan, W.F. 1981. Effect of s i l v i c u l t u r a l practices on erosion and sedimentation in the interior West — a case for sediment budgeting. In Proceedings - Symposium on  Interior West Watershed Management. (April 8-10, 1980, Spokane, Wash.) Pullman, Washington: Washington State University Cooperative Extension Service. Megahan, W.F., Day, N.F., & B l i s s , T.M. 1978. Landslide occurance in the western and central Northern Rocky Mountain physiographic province in Idaho. In C.T. Youngberg (Ed.). Forest Soils and Land Use. Fort Collins, Colorado: Colorado State University Press. Miles, D.W.R., Swanson, F.J. & Youngberg, C.T. 1984. Effects of landslide erosion on subsequent Douglas-fir growth and stocking levels in the western Cascades, Oregon. Soil Sci. Soc. Am. J., 488 (3), 667-671. Ministry of Forests Act. 1979. Royal Statute Chapter 272 (28 Eliz.2). Victoria: Queen's Printer. Minko, G. 1975. Effects of s o i l physical properties, irrigation, and f e r t i l i z e r on Pinus radiata seeding development in the Benalla Nursery. For. Tech. Paper,  Forestry Commission, Victoria(Australia), 22, 19-24. 73 f M i t c h e l l , M.L., Hassan, A.E., Davey, C.B., & Gregory, J.D. 1982. Loblolly pine growth in compacted greenhouse soils. Trans. ASAE (1982), 304-307 & 312. O'Loughlin, CL. 1971. An Investigation of the Stability of  Steep Land Forest Soils in the Coast Mountains, Southwest  British Columbia. Unpublished Ph.D. thesis, Faculty of Forestry, U.B.C., Vancouver. O'Loughlin, CL. & Ziemer, R.R. 1982. The importance of  root strength and deterioration rates upon edaphic  stability in steepland forests. Paper presented at a Workshop on "Carbon Uptake and Allocation in Sub-alpine Ecosystems." International Union of Forest Research Organization (Aug. 2-11, 1982) Corvallis, Oregon. Perry, T.O. 1964. s o i l compaction and loblolly pine growth. USFS Tree Planter's Notes (1964) 67-69. Potter, M.K., & Lamb, K.M. 1974. Root development of radiata pine in the gravel soils of Eyrewell Forest, Canterbury. N.Z. J . For., 19, 264-275. Reed, F.L.C. & Associates Ltd. 1973. The British Columbia Forest Industry — Its Direct and Indirect Impact on the  Economy. A report to the B.C. Department of Lands, Forests and Water Resources, Victoria. Reid, L.M., Dunne, T., & Cederholm. C.J. 1981. Application of sediment budget studies to the evaluation of logging road impact. J. of Hydrology, 20 (1), 49-62. Rodin, L. & Basilevich, N. 1967. Production and Mineral  Cycling in Terrestrial Vegetation. Edinburgh, U.K.: Oliver and Boyd. Row, C, Kaiser, H.K., & Sessions, J. 1981. Discount rates for long-term Forest Service investments. J. of Forestry, 79, 367-369, 376. Ruarck, G.A., Maden, D.L. & Tattar, T.A.. 1982. The influence of s o i l compaction and aeration on the root growth and vigour of trees -- a literature review — Part I. Arbor cultural Journal, (i, 251-265. Salewski, W. 1980. Landing Rehabilitation. Unpublished report. B.C. Ministry of Forests, Vanderhoof District. /3q Schwab, J.W. 1982. Mass wasting, October-November 1982 Storm, Rennell Sound, Queen Charlotte Islands (E.P. 782-02). Unpublished report. Research Section. Prince Rupert Forest Region. Sidle, R.C. 1980. Slope Stability on Forest Land. USDA Forest Service Extension Publication PNW-209. Portland: PNW Forest and Range Experiment Station. Simpson, J.R. 1976. Transfer of nitrogen from three pasture legumes under periodic defoliation in a fi e l d environment. Aust. J. Exp. Agric. Animal Husb., 16 863-868. Singh, A. 1975. Use of organic materials and green manures as fe r t i l i z e r s in developing countries. In Organic  Materials as Fer t i l i z e r s . FAO Soil Bulletin No. 27: Rome: Food and Agriculture Organization. Skinner, M.F. & Bowen, G.D.. 1974. The penetration of so i l by mycelial strands of ectomycorrhizal fungi. Soil Bio.  Biochem. , (>, 57-61. Smith, R.B., Commandeur, P.R., & Ryan, M.W. 1983. Effect of  mass wasting on vegetation succession, soi l development,  and forest growth on the Queen Charlotte Islands. Working paper 8/83,Fish ForestryInteraaction Program. Victoria: B.C. Min. of Forests, Research Branch. Smith, R.B. & Wass, E.F. 1979. Tree Growth on and Adjacent to Contour Skid Roads in the Subalpine Zone, Southeastern  B.C. (BC-R-2) Environment Canada, Forestry Service. Ottawa: Queen's Printer. Sprent, J.I. 1979. The Biology of Nitrogen-fixing Organisms. London: McGraw-Hill. Stanford, G. & Pierre, W.N. 1953. Availability of soil and f e r t i l i z e r phosphorus. In W.N. Pierre & A.C. Norman (Eds.). Soils and Fert i l i z e r — Phosphorus Agronomy 4. New York: Academic Press. Steinbrenner, E.C. & Gessel, S.P. 1955. Effect of tractor logging on soils and regeneration in the Douglas-fir region of southwestern Washington. Soc. Am. For. Proc., 1955, 77-80. 13/;. Swanston, D.N. 1974. The Forest Ecosystem of Southwest Alaska: Soil Mass Movement. USDA Forest Service General Technical Report PNW-17. Portland: PNW Forest and Range Experiment Station. Swanston, D.N. & Swanson, F.J. 1976. Timber harvesting, mass erosion and steepland forest geomorphology in the Pacific Northwest. In D.R. Coates (Ed.). Geomorphology  and Engineering (pp. 199-221). Stroudsburgh, Pa.: Dowden, Hutchenson, & Ross. Teeguarden, D. 1976. Comments and viewpoint. In W. McKellop & W.J. Mead (Eds.). Timber Policy Issues in British  Columbia (pp. 233-239). Vancouver: U.B.C. Press. Thompson, M.L. 1978. Soils and F e r t i l i t y . Toronto: McGraw-H i l l Press. Thorud, D.B. & F r i s s e l l , S.S., Jr. 1976. Time Changes in  Soil Density Following Compaction Under an Oak Forest. Minn. For. Res. Note: 257. Duluth: University of Minn. Press. Turner, J. & Singer, M.J.. 1976. Nutrient distribution and cycling in a sub-alpine coniferous forest ecosystem. J.  of Appl. Ecol. , 13, (1), 295-301. van der Weert, R. 1974. Influence of mechanical forest clearing on soi l conditions and the resulting effects on root growth. Trop. Agric., 51 (2), 325-331. Wert, S. & Thomas, B.R. 1981. Effects of skid roads on diameter, height, and volume growth in Douglas-fir. Soil Sci. Soc. Am. J., 45, 629-632. Wilford, D.J. & Schwab, J.W. 1982. Soil mass movements in the Rennell Sound area, Queen Charlotte Islands, British Columbia. In Canadian Hydrology Symposium (June 14-15,  1982). Fredricton, N.B. (pp. 521-541) Ottawa: National Research Council. Wu, T.H. & Swanston, D.N. 1980. Risk of landslides in shallow soils and i t s relation to clearcutting in southeastern Alaska. For. Sci•, 26 (3), 495-510. Young, W. 1981. Timber Supply Management in B.C. - past - Present - Future. Burgess - Lane Memorial Lecture. Vancouver: Faculty of Forestry, U.B.C. Youngberg, C.T. 1959. The influence of so i l conditions, following tractor logging, on the growth of planted Douglas-fir seedlings. Soil Sci. Am. Proc, 231 76-78. Ziemer, R.R. & Swanston, D.N. 1977. Root Strength Changes  After Logging in Southeastern Alaska. USDA Forest Service Research Note PNW-306. Portland: PNW Forest and Range Experiment Station. Ziemkiewicz, P.F. 1979. Effects of f e r t i l i z a t i o n on the nutrient and organic matter dynamics of reclaimed coal- mined areas and native grasslands in southeastern British  Columbia. Unpublished Ph.D. thesis, Faculty of Forestry, U.B.C., Vancouver. /3 3 APPENDIX A STATISTICAL ANALYSIS OF SOIL BULK DENSITY DATA BY LAYER--FORT ST. JAMES Analysis - ANOVA: singlefactor (landingvs.off-landing density), three replications 0-10 cm: Winter logging Source df SS MS F Treatment 1 451004 451004 5.99 Error 4 301117 75279 Total 5 752121 : Summer logging Source df SS MS F Treatment 1 870204 870204 220.08 Error 4 15817 3954 Total 5 886021 10-20 cm: Winter logging Source df SS MS F Treatment 1 248067 248067 6.93 Error 4 143133 35783 Total 5 391200 : Summer logging Source df SS MS F Treatment 1 510417 510417 288.21 Error 4 7083 1771 Total 5 517500 20-30 cm: Winter logging Source df SS MS F Treatment 1 161704 161704 4.67 Error 4 138534 34633 Total 5 300238 : Summer logging Source df SS MS F Treatment 1 408204 408204 241.25 Error 4 6767 1692 Total 5 414971 0-30 cm: Winter logging Source df SS MS F Treatment 1 257923 257923 5.81 Error 4 177497 44375 Total 5 435420 : Summer logging Source df SS MS F Treatment 1 582817 582817 257.09 Error 4 9066 2267 Total 5 591883 APPENDIX B STATISTICAL ANALYSIS OF THE INCREASE IN SOIL DENSITY — FORT ST. JAMES Analysis - ANOVA: single factor (season of logging), three replications 0-10 cm Source df SS MS F Treatment 1 294 294 <1 Error 4 6188 1547 Total 5 6482 10-20 cm Source df SS MS F Treatment 1 434 431 4.67 Error 4 371 93 Total 5 805 20-30 cm Source df SS MS F Treatment 1 417 417 7.58 Error 4 218 55 Total 5 635 0-30 cm Source df SS MS F Treatment 1 771 771 4.67 Error 4 660 165 Total 5 1431 APPENDIX C STATISTICAL ANALYSIS OF SOIL NITROGEN CONTENT (0-30 cm)—FORT ST. JAMES Analysis - ANOVA: two factors (season of logging, off-landing versus landing), three replications Source df SS MS F Treatment 3 155034 Season 1 88580 88580 <1 Area 1 42602 42602 <1 Season x Area 1 23852 23852 <1 Error 8 1153295 144161 Total 11 1308329 J3? APPENDIX D STATISTICAL ANALYSIS OF SOIL NITROGEN CONCENTRATION (0-30 cm)—FORT ST. JAMES Analysis ANOVA: two factors (season of logging, off-landing versus landing) three replicates Source df SS MS Treatment 3 20858 Season 1 2670 Area 1 17557 Season x Area 1 631 Error 8 10408 2670 17557 631 1301 2.05 13.50 <1 Total 11 31266 APPENDIX E STATISTICAL ANALYSIS OF SOIL PHOSPHORUS CONTENT (0-30 cm)—FORT ST. JAMES Analysis - ANOVA: two factors (season of logging, off-landing versus landing area), three replications Source df SS MS F Treatment 3 36142 Season 1 7701 7701 6.60 Area 1 24480 24480 20.99 Season x Area 1 3961 3961 3.40 Error 8 9326 1166 Total 11 45468 /3f APPENDIX F STATISTICAL ANALYSIS OF SOIL PHOSPHORUS CONCENTRATION (0-30 cm)—FORT ST. JAMES Analysis - ANOVA: two factors (season of logging, off-landing versus landing area), three replications Source df SS MS F Treatment 3 38826 Season 1 547 547 3. 30 Area 1 37969 37969 228. .73 Season x Area 1 310 310 1. 87 Error 8 1329 166 Total 11 APPENDIX G STATISTICAL ANALYSIS OF SOIL POTASSIUM CONTENT (0-30 cm)—FORT ST. JAMES Analysis - ANOVA: two factors (season of logging, off-landing versus landing area), three replications Source df SS MS F Treatment 3 2991 Season 1 5 5 <1 Area 1 1160 1160 <1 Season x Area 1 1826 1826 <1 Error 8 16350 2044 Total 11 19341 . / / / APPENDIX H STATISTICAL ANALYSIS OF SOIL POTASSIUM CONCENTRATION (0-30 cm)—FORT ST. JAMES Analysis - ANOVA: two factors (season of logging, off-landing versus landing area), three replications Source df SS MS F Treatment 3 61347 Season 1 1633 1633 1.06 Area 1 57132 57132 36.99 Season x Area 1 2582 2582 1.67 Error 8 12360 1545 Total 11 73707 /</* APPENDIX I STATISTICAL ANALYSIS OF REGENERATION STOCKING SURVEY BY STAND—FORT ST. JAMES Analysis - ANOVA: single factor (land versus off-landing), four replications 6-year Winter logging Source df SS MS F Treatment 1 101250 101250 1.98 Error 6 307500 51250 Total 7 408750 6-year Summer logging Source df SS MS F Treatment 1 211250 211250 3.87 Error 6 327500 54583 Total 7 538750 11-year Winter logging Source df SS MS F Treatment 1 151250 151250 2.40 Error 6 377500 62916 Total 7 528750 11-year Summer logging Source df SS MS F Treatment 1 20000 20000 <1 Error 6 275000 45833 Total 7 295000 ^3 APPENDIX J STATISTICAL ANALYSIS OF FOLIAR NUTRIENT CONCENTRATION BY STAND—FORT ST. JAMES Analysis - ANOVA: single factor (landing versus off-landing), four replications Foliar N 6-year Summer logging Source df SS MS F Treatment 1 0.0054 0.0054 3.38 Error 6 0.0097 0.0016 Total 7 0.0151 6-year Winter logging Source df SS MS F Treatment 1 0.0019 0.0019 <1 Error 6 0.0171 0.0028 Total 7 0.0190 11-year Summer logging Source df SS MS F Treatment 1 0.0109 0.0109 18. 10 Error 6 0.0036 0.0006 Total 7 0.0145 y / / 11-year Winter logging Source df SS MS F Treatment 1 0.0001 0.0001 <1 Error 6 0.0036 0.0006 Total 7 0.0037 Foliar P 6-year Summer logging Source df SS MS F Treatment 1 721 72 2.25 Error 6 190 32 Total 7 262 1A11 P values x 106 6-year Winter logging Source df SS MS F Treatment 1 32 32 <1 Error 6 278 46 Total 7 310 11-year Summer logging Source df SS MS F Treatment 1 561 561 3.67 Error 6 916 153 Total 7 1477 11-year Winter logging Source df SS MS F Treatment 1 120 120 3.33 Error 6 214 36 Total 7 334 Foliar K 6-year Summer logging Source df SS MS F Treatment 1 44181 4418 7.70 Error 6 3446 574 Total 7 7864 XA11 K values x 106 6-year Winter logging Source df SS MS F Treatment 1 2312 2312 1.21 Error 6 11492 1915 Total 7 13804 11-year Summer logging Source df SS MS F Treatment 1 21 21 <1 Error 6 3111 519 Total 7 3132 11-year Winter logging 7 ^ Source df SS MS F Treatment 1 2381 2381 2.40 Error 6 5945 991 Total 7 8326 APPENDIX K STATISTICAL ANALYSIS OF SEEDLING HEIGHTS FOR EACH STAND—FORT ST. JAMES Analysis - ANOVA: single factor (off-landing versus landing) , four replications 6-year Summer logging Source df SS MS F Treatment 1 2201 2201 5.91 Error 6 2235 372 Total 7 4436 6-year Winter logging Source df SS MS F Treatment 1 1233 1233 Error 6 1357 226 5.46 Total 7 2590 11-year Summer logging Source df SS MS F Treatment 1 53301 53301 31.86 Error 6 10038 1673 Total 7 6339 11-year Winter logging Source df SS MS F Treatment 1 54781 54781 32.19 Error 6 10213 1702 Total 7 64994 APPENDIX L SEED MIX USED AT KOKSILAH Grasses Percentage by weight Lolium multiflorum 5.5 Lolium perenne 5.5 Phleum pratense 5.5 Agrostis alba 4.0 Dactylis glomerata 13.0 Festuca arundenacia 20.0 Festuca rubra 12.0 Festuca ovina 9 .0 Legumes Trifolium repens 4.0 Trifolium pratense 7 . 0 Trifolium hybridum 5.5 Lotus cjnrniculatus 9.0 APPENDIX M SEED MIX USED AT VANDERHOOF Medicago sativa 35% (by weight) Trifolium subterraneum 15% Trifolium repens 15% Trifolium hybridum 15% Lotus corniculatus 20% APPENDIX N STATISTICAL ANALYSIS OF TOTAL N, P, AND K POOLS FOR TREATMENT EFFECTS—KOKSILAH Analysis - ANOVA for split-plot design (main factor-treatment, split factor-year), two replications Nitrogen Source df SS MS F Treatment 1 1683613 1683613 124.6 Error (a) 2 27057 13514 Year 1 365 365 <1 Treatment x 1 4231 4231 1.10 Year Error (b) 2 7659 3830 Total 7 172294 APPENDIX N STATISTICAL ANALYSIS OF TOTAL N, P, AND K POOLS FOR TREATMENT EFFECTS — KOKSILAH Analysis • ANOVA for split-plot des ign (main : factor-treatment, split factor- year), two replicatioi Nitrogen Source df SS MS F Treatment 1 1683613 1683613 124.6 Error (a) 2 27057 13514 Year 1 365 365 <1 Treatment x 1 4231 4231 1. 10 Year Error (b) 2 7659 3830 Total 7 172294 Phosphorus Source df SS MS F Treatment 1 7887.7 7887.7 85.6 Error (a) 2 184.2 92.1 Year 1 57.2 57. 2 <1 Treatment x 1 0.4 0.4 <1 Year Error (b) 2 118.9 59.4 Total 7 8248.4 Potassium Source df SS MS F Treatment 1 165888 165888 56. 1 Error (a) 2 5914 2957 Year 1 112 113 <1 Treatment x 1 12 12 <1 Year Error (b) 2 262 131 Total 7 172188 APPENDIX 0 STATISTICAL ANALYSIS OF TOTAL N, P, AND K POOLS FOR TREATMENT EFFECTS -- VANDERHOOF Analysis ANOVA: single factor, four replications Nitrogen Source df SS MS F Treatment 1 311261 311261 5.21 Error 6 358657 59776 Total 7 669918 Phosphorus Source df SS MS F Treatment 1 25538 25538 9.6 Error 6 15928 2655 Total 7 41466 Potassium Source df SS MS F Treatment 1 56113 56113 4.45 Error 6 75627 12605 Total 7 131740 /S3 APPENDIX P STATISTICAL ANALYSIS FOR FOLIAR N, P, AND K CONCENTRATIONS IN DOUGLAS-FIR SEEDLINGS — KOKSILAH Analysis ANOVA for split-plot design (main factor -treatment, split-factor year), two replications Nitrogen Source df SS MS F Treatment 1 1.080 1.080 43.2 Error (a) 2 0.050 0.025 Year 1 0.004 0.004 <1 Treatment X Year 1 0.367 0.36 2.21 Error (b) 2 0.331 0.165 Total 7 1.832 Phosphorus Source df SS MS F Treatment 1 0.0002 0.0002 <1 Error (a) 2 0.0035 0.0017 Year 1 0.0091 0.0091 15.16 Treatment X Year 1 0,0009 0.0009 1.50 Error (b) 2 0.0012 0.0006 Total 7 0.0149 Potassium Source df SS MS F Treatment 1 0.1179 0.1179 45.35 Error (a) 2 0.0052 0.0026 Year 1 0.0329 0.0329 9. 14 Treatment X Year 1 0.0128 0.0128 3.56 Error (b) 2 0.0072 0.0036 Total 7 0.1760 APPENDIX P STATISTICAL ANALYSIS OF DOUGLAS-FIR SEEDLING HEIGHT -- KOKSILAH Analysis ANOVA: single factor, two replications Age 9 Source df SS MS F Treatment 1 8313.7 8313.7 1409.10 Error 2 11.8 5.9 Total 3 8325.5 Age 8 Source df SS MS F Treatment 1 2381.4 2381.4 243.00 Error 2 19.7 9.8 Total 3 2401.1 Age 7 Source df SS MS F Treatment 1 410.1 410.1 78.87 Error 2 10.4 5.2 Total 3 420.5 Age 6 Source df SS MS F Treatment 1 92.2 92.2 40.98 Error 2 4.5 2.2 Total 3 96.7 APPENDIX Q STATISTICAL ANALYSIS OF FOLIAR N, P, AND K CONCENTRATION AND HEIGHT OF LODGEPOLE PINE SEEDLINGS — VANDERHOOF Analysis ANOVA: single factor, three replications Foliar N Source df SS MS F Treatment 1 0.002 0.002 <1 Error 4 0.292 0.073 Total 5 0.294 Foliar P ( x 106) Source df SS MS F Treatment 1 4 4 <1 Error 4 1090 273 Total 5 1094 Foliar K ( x 105) Source df SS MS F Treatment 1 17 17 <1 Error 4 435 109 Total 5 452 < Seedling height Source df SS MS F Treatment 1 70.04 70.04 3.86 Error 4 72.61 18.15 Total 5 142.65 APPENDIX R BENEFIT-COST WORKSHEET — VANCOUVER (BASED ON B.C. MINISTRY OF FORESTS, 1980a AND 1983) STAND DESCRIPTION Area: 100 ha (excluding roads) Disturbance: 1% loss to erosion Stand: Composition Western hemlock (39%) Western red cedar (21%) Balsam (30%) Douglas-Fir (17%) Site Class Good (4%) Medium (38%) Poor (49%) Low (9%) Stumpage 5 yr Ave. ($/m3) 5.19 13.63 5.29 9.52 8.10 average MAI (m3/ha) 10.18 6.21 2.84 1.50 4.3 average Age at harvest 75 years MANAGEMENT OPTIONS Option A. No Rehabilitation Rehabilitation B. No Planting Planting Result Cost equivalent loss $ 0 1% productivity f u l l productivity $ 1,160 68% f u l l stocking $ 0 87% f u l l stocking $26,000 CALCULATIONS 1. Projected Volume: A. No Rehabilitation 31,928 m3 Rehabilitation 33,250 m3 322 m3 B. No Planting 21,930 m3 Planting 28,058 m3 6,128 m3 2. Projected Stumpage: A. 75 years @ 0% = $ 8.10/m;? B. 75 years @ 3% = $74.35/m3 3. Value of Difference A. 1) 322 m3 x $ 8.10/m3 = $ 2,608 2) 322 m3 x $74.35/m3 = $ 23,941 B. 1) 6128 m3 x $ 8.10/m3 = $ 49,637 2) 6128 m3 x $74.35/m3 = $455,617 4. Present Gross Value 2% 6% A. 1) $ 536 $ 32 2) $ 4,917 $ 300 B. 1) $10,195 $ 622 2) $93,854 $5,713 5. Benefit-Cost Ratio 2% 6% A. 1) 0.46 0.03 2) 4.24 0.26 B. 1) 0.39 0.05 2) 3.60 0.21 APPENDIX S BENEFITCOST WORKSHEET PRINCE GEORGE (BASED ON B.C. MINISTRY OF FORESTS, 1980a AND 1983) STAND DESCRIPTION Area: 100 ha (excluding roads) Disturbance: 4% Landings 16% Skid roads Stand: Composition Spruce (55%) Lodgepole pine (32%) Balsam (8%) Site Class Good (16%) Medium (45%) Poor (37%) Low (2%) Stumpage 5 yr 7.35 3.21 2.25 Ave 5.25 average MAI (m3/ha) 3.42 2.13 1.12 0.40 Average at harvest 100 years 1.93 average Option A. No Rehabilitation Rehabilitation B. No Planting Planting MANAGEMENT OPTIONS Result Cost equivalent l o s s — $ 0 1% productivity f u l l productivity $ 1,160 68% f u l l stocking $ 0 87% f u l l stocking $26,000 Option A. No Rehabilitation Rehabilitation B. No Planting Planting Result Cost equivalent loss $ 0 1% productivity f u l l productivity $ 1,160 68% f u l l stocking $ 0 87% f u l l stocking $26,000 CALCULATIONS 1. Projected Volume: A. No Rehabilitation 16,720 m3 Rehabilitation 19,000 m3 difference 2,280 m3 B. No Planting 8,550 m3 Planting 15,580 m3 difference 7,030 m3 2. Projected Stumpage: A. 100 years @ 0%/year $ 5.25 B. 100 years @ 3%/year $100.90 3. Value of Difference: A. 1) 2280 m3 x $ 5.25/m3 = $ 11,970 2) 2280 m3 x $100.90/m3 = $230,052 B. 1) 7030 ml x $ 5.25/m3 = $ 36,907 2) 7030 m3 x $100.90/m3 = $709,327 4. Present Gross Value: 2% 6% A. 1) $ 536 $ 32 2) $ 4,917 $ 300 B. 1) $10,195 $ 622 2) $93,854 $5,713 5. BenefitCost Ratio 2% 6% A. 1) 0.46 0.03 2) 4.24 0.26 B. 1) 0.39 0.05 2) 3.60 0.21 

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