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Study of litterfall and forest floor accumulation in the spacing plantations of Douglas fir at the University… Woon, Chio-Yio 1970

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A STUDY OF LITTERFALL Al© FOREST FLOOR ACCUMULATION IN THE SPACING PLANTATIONS OF DOUGLAS FIR AT THE UNIVERSITY OF BRITISH COLUMBIA RESEARCH FOREST BY CHIO-YIO WOON B. Agri. (Forestry), Tokyo University of Agriculture & Technology, 1967 A THESIS SUBMITTED IN PARTIAL FULFILMENT OF THE REQUIREMENTS FOR THE DEGREE OF MASTER IN FORESTRY i n the Department of Forestry We accept this thesis as conforming to the required standard THE UNIVERSITY OF BRITISH COLUMBIA January, 1970 In present ing th is thesis in p a r t i a l f u l f i lment of the requirements for an advanced degree at the Un ivers i ty of B r i t i s h Columbia, I agree that the L ibrary sha l l make i t f r e e l y ava i l ab le for reference and Study. I fur ther agree that permission for extensive copying of th is thesis for s cho l a r l y purposes may be granted by the Head of my Department or by his representat ives . It is understood that copying or pub l i ca t i on of th is thesis for f i n a n c i a l gain sha l l not be allowed without my wr i t ten permission. (Chio T i o Woon) Department of Fores t ry  The Un ivers i ty of B r i t i s h Columbia Vancouver 8, Canada Date January, 1970  ABSTRACT L i t t e r f a l l i n the UBG Research Forest was collected from traps randomly-placed i n each of f i v e half-acre plots of twelve year old Coastal Douglas f i r of spacings ranging from 3 x 3 to 15 x 15 feet. Collections were also made from a half-acre plot of 3 x 3 feet spaced eleven year old western hemlock, and from an older, thinned natural stand of western red cedar and western hemlock. Forest f l o o r accumulations and s o i l samples from each plot were also collected and analysed. The amount of l i t t e r f a l l i n the Douglas f i r spacing plots showed that the denser the stand the greater was the l i t t e r f a l l . The percentage of l i t t e r from broadleaved species present was i n increasing order from the 3 x 3 to the 15 x 15 feet Douglas f i r p l o t s . The amount of l i t t e r f a l l i n the Douglas f i r was about 3,000 kg/ha more than that i n the western hemlock pl o t of the same spacing. The l i t t e r f a l l i n the cedar-hemlock stand showed a large amount of cones and twigs, but was not greater than the l i t t e r f a l l collected from the denser plantations of Douglas f i r . I t should be noted that the 3 x 3 and 6 x 6 feet Douglas f i r plots of t h i s study gave a much greater l i t t e r f a l l than the values reported by other authors for t h i s species. However, judging from the l i t e r a t u r e , comparable data for stands of t h i s age and density are not available. Since the v a r i a t i o n of l i t t e r f a l l within a plot was very great, the number of traps needed w i l l have to be increased to a t t a i n a precision of i 10 gm at 5% p r o b a b i l i t y l e v e l for an annual c o l l e c t i o n . The amount of forest f l o o r decreased as spacing widened. I t was shown s t a t i s t i c a l l y that two groups of plots existed: one with associated vegetation (12 x 12 and 15 x 15 feet) and the other without ( 3 x 3 and 6 x 6 feet p l o t s ) . The weight of forest floor of western hemlock was less than that of Douglas i f i r of the same spacing. The weights of forest f l o o r obtained i n t h i s study were well below the figures given by other authors i n t h i s f i e l d . The index of forest f l o o r turnover, calculated from the r a t i o of l i t t e r -f a l l / f o r e s t f l o o r showed that the closer-spaced plantations had a higher r a t i o than the wider-spaced. This suggests that faster c i r c u l a t i o n of nutrient elements i s going on i n the stand with a f u l l canopy than i n a more widely spaced stand. The chemical contents of the l i t t e r f a l l and forest f l o o r were determined on composite samples from each plot. Nutrient concentration i n l i t t e r f a l l and forest f l o o r did not vary with spacing i n the Douglas f i r plots. The ground vegetation layer found only under the wider Douglas f i r spacings showed greater concentration of phosphorus and potassium than the l i t t e r or forest f l o o r of a l l the spacings. The calcium concentration i n the western hemlock and cedar-hemlock plots was higher than that found i n the Douglas f i r p l o t s , but phosphorus was found to be lower. However, the t o t a l amount of nutrients i n l i t t e r f a l l and i n forest f l o o r under d i f f e r e n t l y spaced Douglas f i r plant-ations followed a d i s t i n c t pattern: a higher content was present i n the denser and lower i n the wider p l o t s . No clear relationship between l i t t e r f a l l or forest f l o o r accumulations and growth as measured so far was observed. The importance of s o i l physical properties i n affecting growth should be considered more closely, because the plots were dif f e r e n t i n s o i l texture and probably i n other physical ch a r a c t e r i s t i c s . i i ACKNOWLEDGMENTS I would like to acknowledge my appreciation for the guidance and suggestions given patiently by Dr. P. G. Haddock of the Faculty of Forestry, University of British Columbia, throughout the process of preparing and writing of this thesis. I am very much indebted to the Department of Soil Science, for the use of their laboratory and to Dr. L. E. Lowe for the advice he gave in the analytical work. I also appreciate very much the valuable suggestions from Dr. A. Kozak of the Faculty of Forestry, on the statistical analysis of my data. Many thanks to Mr. ¥. ¥. Bourgeois, a fellow graduate student in Soil Science, for the help given in the soil pit sampling, and also to Mr. J.Walters, the Director of UBC Research Forest and his staff for the convenience provided during the field work. I wish to express my deep gratitude for the sustained encouragement and company while doing the monotonous work in the field and laboratory from my wife Yuen-Fong. Last but not the least, I thank the financial help from NRC (Grant # A 1375) without which this work would not be accomplished. i i i TABLE OF CONTENTS PAGE ABSTRACT i ACKNOWLEDGMENTS i i i TABLE OF CONTENTS iv LIST OF FIGURES v i i i LIST OF TABLES ix LIST OF APPENDICES X CHAPTER ONE INTRODUCTION 1 CHAPTER WO LITERATURE REVIEW 3 I. Spacing in Plantations 4 Spacing and Growth 5 Thinning in Plantations 6 Comment and Summary 7 II. Size and Number of Litter Traps 8 Summary 9 UL Litterfall 9 Importance of Litterfall 10 Influence of Tree Density and Basal Area on Litter Production 10 Annual and Seasonal Variations in Litter Production 11 Influence of Biomass and Litter Production 11 Influence of Site Quality on Litter Production . 13 Contribution to Litter by Understory Vegetation. 13 Accumulation of Litter on the Forest Floor L4 iv Decomposition of Litter 15 Comment and Summary 15 IV. Forest Floor 16 V. Forest S o i l 17 VI. Mineral Elements 19 Mineral Elements i n the Foliage 19 Release of Mineral Elements from Forest Floor .. 20 Return to the Soi l 20 CHAPTER THESE .'METHODOLOGY 25 I) - Description of the Area 25 Location 25 Climate 25 Study Area 25 II) Methods of Sampling 27 Litter 27 Forest Floor 28 Soi l • 28 III) Preparation of Samples 29 Plant Tissue 29 Soil 29 IV) Chemical Analysis of N, P, K, Ca and pH 29 1) Plant Tissue 29 Total Nitrogen Determination (by Semi-micro Kjeldahl method) 29 Preparation of Organic Matter and P, K and Ca Determination (Chapman and Pratt 196l). 30 2) Soi l 30 v T o t a l N Determination (By Semi-micro K j e l d a h l method) 30 F l u o r i d e - D i l u t e A c i d E x t r a c t i o n of Soluble P and Determination (Jackson I960) 30 Exchangeable K and Ca E x t r a c t i o n w i t h NH^ OAc 31 pH Determination ( l : 1, S o i l : Water R a t i o ) .... 31 CHAPTER FOUR RESULTS AND DISCUSSION 34 L i t t e r Accumulation i n Screens 34 Summary 39 Number of L i t t e r Traps Required 4-1 F o r e s t F l o o r Accumulation i n D i f f e r e n t Spacing P l a n t a t i o n s 44 Summary 46 R e l a t i o n s h i p Between L i t t e r f a l l and Forest F l o o r Accumulation 47 S o i l 49 M i n e r a l Elements i n L i t t e r f a l l , Forest Floor and S o i l 49 N i t r o g e n 49 Nitrogen i n S o i l 53 Phosphorus 53 A v a i l a b l e Phosphorus i n S o i l 54 Potassium 55 Calcium 56 Exchangeable Calcium i n S o i l 57 v i Variations i n Chemical Content i n the Seasonal L i t t e r f a l l 57 Phosphorus 59 Potassium , 59 Calcium 60 Summary" 65 CHAPTER FIVE GENERAL CONCLUSIONS 67 BIBLIOGRAPHY 71 APPENDICES 83 v i i » LIST OF FIGURES FIGURE PAGE 1. Location Map of the University Research Forest 22 2. Location of Study Area i n UBG Research Forest 2 3 3. Mean, Maximum and Minimum Monthly Temperature i n °F for the Period 1959-1967 24 4.. Mean, Maximum and Minimum Monthly Precipitation i n Inches for the Period 1959-1967 24. 5. Sketch Map of the Main Study Area 26 6. Weight and Composition of One Year Litter Accumulation 1967 to 1968 3 2 7. Comparison of Two Years 1 L i t t e r f a l l i n Different Plots 33 8a. Cumulative L i t t e r f a l l i n Douglas Fir Spacing Plantations i n kg/ha 37 8b. Cumulative L i t t e r f a l l i n Western Hemlock and Thinned Cedar-Hemlock Stands i n kg/ha 38 9. Forest Floor Accumulation i n Different Plots 4-3 10. Distribution of Chemical Nutrient i n L i t t e r f a l l (kg/ha/yr) and Forest Floor (kg/ha) Under Different Douglas Fir Spacing Plantations 62 11. Nitrogen Content i n Different Plots i n Percent 63 12. Phosphorus Content i n Different Plots i n Percent ... 63 13. Calcium Content i n Different Plots i n Percent 64. 14.. Potassium Content i n Different Plots i n Percent .... 64-v i i i LIST OF TABLES TABLES PAGE 1. Ratio of Total Non-leaf and Stem Production to Leaf Production 1 3 2 . Annual Return of N, P, K and Ca (kg/ha) in a Thirty-six year old Douglas Fir Stand 2 1 3 . Means and Confidence Interval (95%) of Litterfall in Different Plots (in gm/screen) 3 5 4. Number of Traps Needed for Obtaining Litterfall Weights at 5% Probability Level 4 2 5. Index of Litter Decomposition 48 6. Classification of Soil Profile into Parent Material, Texture and Sub-group 49 7. Chemical Contents in Percent Dry Weight of Litterfall (1967-1968), and Three Layers (V, L, FH) of Forest Floor 51 8. Chemical Properties of Soil 5 2 9. Variations in Chemical Contents in Different Plots of Seasonal (May 3 0 to August 20, 1968) Litterfall Samples 58 10. Nutrient Contents in 1967 - 1968 Litterfall (kg/ha/yr) and Forest Floor (kg/ha) 61 ix LIST OF APPENDICES APPENDIX PAGE I Annual L i t t e r f a l l of Douglas Fir i n Oven-Dried Weight 83 II Forest Floor Accumulation of Douglas Fir i n Oven-Dried Weight 84 III S o i l Profile Characteristics of the Different Plots 85 IV Mineral Contents of Litter of Several Conifer Species i n Percent Dry Weight 86 V Mineral Contents of Forest Floor of Douglas Fir Stands 87 VI Foliage Mineral Contents of Several Conifer Species (in % dry weight) 88 VII Average Oven-Dry Weight, Standard Deviation and Co-efficient of Variation of L i t t e r f a l l at Different Periods 89 VIII Summary of St a t i s t i c a l Analyses 90 IX Average Growth Data for the Douglas Fir Plantations as of 1968 91 X L i s t of Associated Vegetation (mostly ground or understory) on the Different Plots 92 XI Diagram of the Litter Trap 93 XII Trap Location i n Different Plots 94 x 1 CHAPTER ONE - INTRODUCTION The problems facing forest managers are numerous and varied. One i s now faced with the necessity to harvest the v i r g i n forest without causing s i t e deterioration and to establish for the next crop, the ri g h t kind of species for the expected market. The new crop must be established on ecologically suited s i t e s and the necessary tending provided to produce f a s t growth. Various l i n e s of research are being carried out by u n i v e r s i -t i e s , government services, and i n d u s t r i a l firms to help to obtain the needed information. One of the most important l i n e s of s i l v i c u l t u r a l research i s that dealing with the nutrient cycle for the most important species i n the P a c i f i c Northwest—Douglas f i r . (Pseudotsuga menziesii (Mirb.) Franco.) The Northwest P a c i f i c Coast area i s favoured by physiographic and climatic conditions which provide very favourable growing s i t e s for Douglas f i r . The i n i t i a l impact of logging has i n seventy years or so resulted i n the destruction of much of the beautiful Douglas f i r v i r g i n forests. In order to restock the logged-over land, many plantations were established when natural regeneration f a i l e d or was too slow or incomplete. There i s s t i l l much disagreement with.regard to the choice of species and spacing, and i n the nature and importance of the nutrient cycle and f e r t i l i t y needs of the lar g e l y glaciated s o i l s of the Northwest P a c i f i c . The mineral content of a forest ecosystem i s one of the factors control-l i n g productivity. Low productivity has often been correlated with a deficiency i n certain mineral elements i n s o i l and plants, notably nitrogen, phosphorus and potassium (Gessel, Walker and Haddock 1951; Leyton 1958; Madgwick 1964; Shibamoto 1963; Rodin-Bazilevich 1965). The re-use of 2 mineral elements annually returned to the soil has been found to be crucial in maintaining the productivity of forest sites. Mayer (1956) states that the annual growth of woodlands does not reach its normal level until forty years after litter removal is stopped. The objective of this study was to obtain data on litter accumulation and forest-floor development in spacing stands of native species. Further i t was the aim to relate these data to results of previous work and the general problem of the nutrient cycle in silviculture. 3 CHAPTER TWO - LITERATURE- REVIEW The productivity of forest lands i s controlled by many interacting factors; the physical and chemical properties of s o i l ; aspect; altitude and l a t i t u d e , etc. Though physical properties of the land are important, i t i s d i f f i c u l t to r e c t i f y or amend these. Some large-scale work on drain-age i s being carried out on heath lands i n B r i t a i n , Finland, and some other European countries. The chemical properties of s o i l have been related to productivity (Rennie 1955; Shibamoto 1963) and "empirical" forest f e r t i l i -zation i s being practised on an increasing scale. (Hagner 1967; Gessel 1967; Kawana 1965). An experienced forester, while t r a v e l l i n g i n the forest, could t e l l you the degree of productivity of the forest land without being able to ex-p l a i n i t i n d e t a i l . He could t e l l by looking at the r e l i e f , the s o i l and the surrounding tree stand and associated plants. But we need more concrete facts on the productivity of forest lands. Work i s being carried out to i d e n t i f y and evaluate the factors or elements contributing most to s i t e q u a l i t y with the help of many new techniques and a n a l y t i c a l aides, including use of radio-active tracers (Ovington I960). In t r y i n g to determine the nutrient status of the s o i l and the pathway into the tree, as well as the role mineral elements play i n the metabolic system, we have obtained a better understanding of the f i x a t i o n of nutrient elements, their absorption into the plant and their d i s t r i b u t i o n to the organs concerned with metabolism. The forest ecosystem i s a l i v i n g , dynamic system. The mineral elements for metabolism are used and re-used. This turnover i s termed the nutrient cycle. Remezov (1956) distinguished the b i o l o g i c a l cycling of mineral elements and their turnover within an ecosystem from the large-scale geological 4 c y c l i n g involving processes of p r e c i p i t a t i o n , weathering, erosion and sedimentation. There are many factors that offer resistance to the free movement and use. of minerals i n a forest ecosystem of a given potential. These factors are simple drought, permanent mineral f i x a t i o n , temporary b i o l o g i c a l immobilization and loose exchangeable absorption. An understanding, and therefore control and manipulation, of these resistance factors i s of great importance to land managers concerned with the productivity of forest lands. I Spacing i n Plantations The controversy over the best spacing has long been disputed ever since man started managing his forest lands. The optimun density of a stand w i l l vary according to species, s i t e q u a l i t y , seedling supply,final product and other economic considerations. That different spacings have particular functions was c l e a r l y demon-strated i n Japanese forestry from about the seventeenth century (imperial Forest Association, 1924). The production of timber for ship building (Benko Timber) from Sugi (Cryptomeria japonica D. Don) i n the Obi d i s t r i c t i n Kyushu i s one of the examples. Planting was at wide spacing - 600 to 1,500 trees per hectare. No thinning or pruning was carried out. The logs produced after f o r t y years were of high buoyancy, and low spec i f i c gravity. They were used for ship-building. The average annual diameter growth reached 0.6 to 0.7 inches and the grain was coarse. On the other hand, i n Yoshino d i s t r i c t , a management for di f f e r e n t timber products existed, which aimed at the production of wine-cask wood and construction timber from Sugi and Hinoki (Chamaecyparis obtusa). With t h i s i n mind, close planting at 5 10,000 to 15,000 trees per hectare was used. This produced s t r a i g h t , r e l a t i v e l y knotless logs f i t for wine-cask making and construction timber. Wine-cask timber must have at l e a s t f i v e annual rings per 1.2 inches. Be-cause of close planting, improvement cuttings began after nine years of growth. In good l o c a l i t i e s , they were sold. P r o f i t was not expected from the improvement cutting, which aimed actually at better growth of the remain-ing trees. The f i n a l cut was at s i x t y years. In considering spacing i n plantations, the following factors must be taken into account because of the long-term nature of forestry investments! a) the kind of product; b) length of rotations; c) tree species; d) s i t e ; e) economy. The aims of spacing i n plantation can be l i s t e d as: a) for the best and f u l l e s t u t i l i z a t i o n of land potentials for growth; b) for the reduction of s i l v i c u l t u r a l practices l i k e weeding and pruning through natural means; c) to achieve stems of particular q u a l i t y , e.g., straight, knotless and low taper; d) to increase t o t a l y i e l d ; e) for easier mechanical manipulation; f ) to produce a quick cover for erosion and flood control by close spacing and g) with wider spacing, larger diameters can be attained more quickly. Spacing and Growth Isaac (1937), Crane (1962, Harms et a l . (1965). Ware et a l . (194-8). Sjolte-Jorgensen (1967) reported that planting density exerts a powerful control over increment. Ware et a l . (194-8), working on the growth of Southern pine plantations at fourteen years of 4- x 4- feet to 1 6 x 16 feet found that close spacing produced the most wood and volume and widest spacing the l e a s t . Plantations spaced at 6 x 6 feet or closer, and thinned at twelve years to 6 about 500 trees per acre (equivalent to a spacing of 10 x 10 feet for trees over four inches dbh (diameter at breast height and over) l e f t a stand equal i n quantity and far superior i n qua l i t y to unthinned 8 x 8 or 10 x 10 plant-ations. They found that spacings wider than 10 x 10 feet give i n s u f f i c i e n t desirable crop trees and incomplete use of the growing space for at least the f i r s t fourteen years. The greater speed with which the i n d i v i d u a l trees reach sawlog size i s offset by the lower q u a l i t y of the lumber. Eversole, (1955) working on a twenty-seven year-old Douglas f i r plantation spaced at from 4 x 4 feet to 12 x 12 feet,concluded that wide spacing had l i t t l e e ffect on increasing the volume. I t only increased the average diameter. The average limb size was increased by wider spacing. S t i e l l (1964) too found increased limb size i n his red pine study. Harms et al.(1965) reported that greater densities produced greater y i e l d i n the twelfth year of growth of slash pine and that an increase i n number of trees per hectare increased the basal area. Reukema (1966) also acknowledged that lower volume and basal area would r e s u l t as spacing increased. Thinning i n Plantations This c u l t u r a l procedure has been almost ignored so far i n North America, especially i n the P a c i f i c Northwest, because of the abundance of v i r g i n old-growth forests. This practice i s s t i l l l i mited owing to the high labour cost. The idea of investing more i n s i l v i c u l t u r e i s s t i l l d i f f i c u l t for some to accept but methods are improving and more i s being spent. Worthington and Staebler (l96l) discussed the economic and technical aspects of thinning i n respect to Douglas f i r . Berg (1966) stated that intensive management schedules can maintain growth increment equal to or i n excess of 7 natural stands. If stands are carefully thinned, the remaining trees are able to take the advantage of release and occupy the site. In Japan, Kira et a l . ( l 9 5 3 ) and Shinozake et a l . ( l 9 5 6 ) worked out the competition-density effect and Tadaki ( 1 9 6 3 a , 1964-) introduced the plan of pre-estimating the stem volume yield in even aged stands based on C-D (competition-density) rules. Comment and Summary Wider-spaced plantations are frequently cheaper to establish than those more closely spaced (Smith and Walters 1 9 5 7 ) and this reduction in cost may eradicate any advantage in yield attained from the denser stand (Stiell and Berry 1 9 6 7 ; Osborn 1 9 6 7 ) . But these assume (l) that the f u l l use of land potential is not cr i t i c a l , ( 2 ) acceptance of lower quality and volume yield, ( 3 ) longer rotation age for the crop to attain clear wood without pruning, (4.) no thinning. The idea behind dense planting and starting improvement cutting or commercial thinning is not only to f a c i l i -tate early returns on capital investment but more importantly to produce a better quality crop (Ware et al . 1 94 - 8 ; Dobie 1 9 6 6 ; Steele 1 9 5 5 ; Osborn 1 9 6 8 ; Berg 1 9 6 6 ) . There is a specific number of trees at a given size which can completely occupy an area and fully utilize the site. Anything more than this number is surplus and these surplus trees will affect the growth of the chosen number, sometimes to the extent of causing severe reduction in growth, (Harmon 1 9 6 6 ) . Wide spacing is preferred to close spacing here in Northern America (Smith and Walters 1 9 5 7 ; Osborn 1 9 6 7 ; Smith 1 9 5 8 ; Reukema 1 9 5 9 ) because of 8 three fac t o r s : a) high cost of seedlings; b) higher cost of labour i n plant-ing large number of trees per hectare; c) the general i n a b i l i t y to conduct precommercial thinnings or the assumption that commercial thinnings w i l l not be fea s i b l e . On the other hand, the merits of dense spacing are also considered (Osborn 1968; Berg 1966; Ware et a l 194-8; Dobie 1966). When / more thinnings could be commercially u t i l i z e d , more of the better and close-to-market s i t e s would be turned to dense spacing to produce better managed stands of higher q u a l i t y . I I Size and Number of L i t t e r Traps In order to measure the amount of organic matter returning to the s o i l and also the quantity of nutrient elements that re-cycle i n the forest ecosystem v i a l e a f - f a l l , many workers have made use of buckets, square, rectangular and round traps and screens. Not much work has been done to determine the s i z e , shape and number of traps to be used. Saito et a l (1967 / and 1968) made successive studies on 4-5-year-old Chamaecyparis obtusa stands of 1,300 trees per hectare. They found that the least l i t t e r f a l l was i n August and the most i n November. They arrived at the conclusion that s i x 2 traps of 1 m would be s u f f i c i e n t to determine the absolute l i t t e r f a l l i n 2 the i r 10 x 10m p l o t . Sasa et a l (1968) i n their model study of l e a f - f a l l i n laboratory used paper cuttings of diamond-shaped leaves of small (3.0 cm x 1.5 cm), medium 2 ( 8 . 0 cm x 4-«0 cm) and large (12.0 cm x 6.0 cm) sizes and 900 cm traps of round, square and rectangular shapes. Their results showed that the square trap, though having a constant c o l l e c t i o n r a t i o with the round trap, has a higher c o l l e c t i o n . The square trap did not show any corner e f f e c t . The 9 t r i angu l a r t rap when compared with round and square ones had a greater corner e f f e c t , thus reducing the c o l l e c t i o n of the large leaves . Under the same cond i t i on of l e a f - f a l l , square traps c o l l e c t e d more leaves per un i t area .than the round t raps . Regarding the s ize of traps requ i red , they found no r e l a t i o n s h i p between the s ize and c o l l e c t i o n per un i t area i n the l abora tory study. With t h i s background they tested the number of traps requ i red i n the f i e l d and found that regardless of area, ten traps would be s u f f i c i e n t i n a whole l e a f - f a l l season, but f o r pe r i od i c shorter i n t e r v a l s a minimum of twenty traps was recommended. Summary I t has been reported that square traps are better than other shapes and that the larger the surface area, the lower w i l l be the c o e f f i c i e n t of p v a r i a t i o n . About ten traps of Im should be quite s u f f i c i e n t to determine 2 the annual l i t t e r f a l l i n a 10 x 10 m p l an ta t i on . I l l L i t t e r f a l l The product ion of organic matter remains from the f o r e s t stand i s known as l i t t e r f a l l . This may be composed of leaves , branches, bark and f r u i t . Th i s l i t t e r i s then exposed to decomposition, being used by the macro and micro-organisms as a source of energy. When the organisms pe r i sh and de -compose, the mineral elements necessary f o r p lant growth are s lowly re leased in to the s o i l along with the re lease of carbon d iox ide . The process con -t inues unless some elements are taken out of the ecosystem, where the minera l or other elements might be incorporated in to another ecosystem. 10 Importance of L i t t e r f a l l The importance of organic matter has long been recognized i n Europe espec i a l l y i n German forests. Where l i t t e r had been removed continuously over long periods, forest productivity had declined. Mayer (1956) states that the annual growth of woodlands does not reach i t s normal l e v e l u n t i l f o r t y years after l i t t e r removal i s stopped. On the other hand, interest i n forest l i t t e r on the North American continent has been centred primarily around effects upon such factors as f i r e hazard and seedbed condition (Scott 1955). However, some consideration of the possible harmful effects of indiscriminate destruction or removal of such l i t t e r on the productivity of forest s i t e s has been mentioned i n the l i t e r a t u r e . The importance o f ' . l i t t e r as the water-storage layer from the watershed management point of view has also been considered. (Kittredge 1948; Mader et al.1968; Warren et al.1969). L i t t e r accumulation and humus layers are being studied for amounts and chemical composition ( W i l l 1967; Ovington 1956; Ohmasa and Mori 1937) to understand the nutrient c y c l i n g of woodland and to replenish the woodland with the mineral elements that seem short. Methods of hastening decomposition of the l i t t e r layer and thus getting the elements contained therein back into a useful cycle have been under intensive study (Wittich 1952; Weetman 1965; Hayes 1965b). Influence of Tree Density and Basal Area on L i t t e r Production Hatiya e± _•• (1966a, 1966b) reported that l i t t e r f a l l was highest from very high density Larix leptolepis and Pinus densiflora. x^hereas Bray and 11 Gorham (1964) concluded that l i t t e r production appeared to be l i t t l e affected by differences i n tree density within closed-canopy forests. In Norway, Bonnevie-Svendsen and Gjems (1957) have shown a d i s t i n c t c o r r e l a t i o n between annual f a l l of leaf l i t t e r and stand basal area i n a series of Gymnosperm and Angiosperm stands. Reukema (1964) also reported that the l i t t e r f a l l i s proportional to the basal area i n the Douglas f i r stands he studied. Annual and Seasonal Variations i n L i t t e r Production Reukema (1964), i n his thirteen years' period study of a f i f t y - t w o -year-old Douglas f i r , found that the maximum annual l i t t e r f a l l was three times more than that of the minimum annual l i t t e r f a l l . This was attributed to clim a t i c conditions. The rate of l i t t e r f a l l was at i t s lowest about A p r i l and usually reached a maximum i n October and November. Dimock (1958) i n d i -cated that l i t t e r f a l l per year over an extended period was not a constant fig u r e . S i m i l a r l y , Douglas f i r l i t t e r f a l l was not distributed evenly over the year, but usually f e l l at a maximum rate during October. Minimum l i t t e r -f a l l normally occurred during the later winter or early spring. Extreme low temperatures may t r i p l e the amount of l i t t e r that f a l l s during the ensuing year. Rodin et al.(l965) found that stands produce the maximum l i t t e r at around f o r t y years of age. The xrork of Alway and Zon (1930) and Kittredge (1948)showed a similar trend. Influence of Biomass and L i t t e r Production Biomass of leaves d i f f e r s s i g n i f i c a n t l y among di f f e r e n t forest types and d i f f e r e n t geographic regions. Deciduous hardwood forests of the temperate 12 zone tend to have the least amount, mostly within the range of two to four tons per hectare, ovendried weight. Forests of broadleaf evergreens and pine bear more leaves (around seven to nine tons). Subarctic or subalpine f i r and spruce forests as well as alpine dwarf pine scrubs have the greatest amount, reaching twenty tons per hectare or more. Kira and Shidei (1967)j and Tadaki (1963b, 1966), pointed out that the average longevity of leaves seemed to be an important factor responsible for the difference of le a f biomass. Mollar (1947) demonstrated that the volume of tree foliage for any par t i c u l a r species i n a closed-stand remains r e l a t i v e l y constant, irrespective of the degree of thinning. He suggested that t h i s s i g n i f i e d a s t r i v i n g for f u l l u t i l i z a t i o n of l i g h t under forest conditions. Aiba et a l , (1968) concluded i n their study on si t e and productivity that new le a f volume did not change d r a s t i c a l l y i n accordance with si t e differences. The old leaves were retained for a short time on a lower q u a l i t y s i t e . There were larger amounts on better s i t e s . This was thought to be due to the fact that the lower the s i t e , the shorter i s the retention of old leaves and thus the amount of old leaves i s less on low s i t e s . In other words, the better the s i t e , the longer i s the retention of old leaves. Thus, Bray and Gorham (1964) summed up by saying that the use of leaf l i t t e r values as production indices would therefore greatly over-estimate Equatorial forest production and underestimate production by Temperate ever-greens, because evergreen Gymnosperm leaves produce annually over 60$ more than the Equatorial forest leaves (see Table l ) . 13 Table 1. Ratio of Total, Non-leaf and Stem Production to Leaf Production (Bray and Gorham 1964) Total/Leaf Non-leaf/Leaf Stem/Leaf Cool temperate evergreen Gymnosperms 4.9 3-9 3.1 Equatorial forest 3.3 2.4 2.0 Influence of Site Quality on Litter Production Research has shown that variations in site quality have an influence on the amount of l i t t e r f a l l in much the same fashion that site influences wood production. Mork (1942) presented data which indicated that increasing elevation, hence decreasing site index, reduced the amount of l i t t e r f a l l in both Norway spruce and European birch. Chandler (l94l) also indicated that leaf - fa l l decreased with decreasing site quality. But Aiba s i al.(1968) in their study of thirty-year-old Pinus densiflora stands of different site qualities concluded that on the better site, the old needles are retained longer than on the lower site. On the whole, the amount of l i t t e r f a l l will be quite closely correlated with the general productivity of the site. Contribution to Litter by Understory Vegetation The contribution of understory plants to forest l i t ter is closely re-lated to the density of the forest canopy, as well as light penetration into the forest floor (Scott 1955). Levina (cited by Rodin 1965) demonstrated, 14 from a study of the role of mosses, lichens and shrubs in two types of pine forest in the Kola peninsula (Russia) that an increase in the swampiness of the habitat was reflected in an increase in the total mass of the l i t t e r f a l l , most of i t from the understory vegetation. Other investigators mention the fact that subordinate vegetation, es-pecially moss, is present in substantial quantity and some even stress its importance in soil formation or as a source of nutrients (Mork 1942). Hard-woods and lesser vegetation also add considerable amount to the total l i t t e r f a l l (Reukema 1964). Accumulation of Litter on the Forest Floor Annual l i t t e r f a l l is dependent on the density of the stand, species, site, age etc. (Kittredge 1948, Puri 1950). The accumulation of litter on the forest floor is dependent on a l l these influences, as well as a l l the other factors of environment which influence the decomposition of organic matter. Thus, temperature, humidity and rainfall, through their effect on various soil organisms, (Bray and Gorham 1964) play an important part in determining the amount of litter on the forest floor. Extreme differences exist in forest floor development between the tropical forests and the sub-arctic or boreal forests. Very thin forest floors exist in the former and thick accumulations of raw humus develop in the latter. The l i t t e r f a l l in these two regions varies from 3.5 tons per hectare in the cool temperate to 10.9 tons per hectare in the Equatorial region, Bray and Gorham (1964). Jenny et al.(1949) gave these figures: 919 to 3,138 kg/ha in the temperate forest and 8,515 to 11,993 kg/ha in the tropical forest. 15 Decomposition of Litter To understand the amount of nutrients in circulation, the study of the intensity of litter decomposition has been studied by many authors (Waksman 1938; Witkamp 1966; Remozov 1956; Tsutsumi 1963; Ovington 1954; Will 1967; Thomas 1967). Waksman (1938) noted that the nature and speed of decomposition of the litter is affected by these factors: 1. Nature of higher vegetation: the needles of conifers vary remarkably in chemical composition from deciduous leaves. 2. Nature of micro-organisms active in the disinteg-ration of plant residues; where fungi are predominant, a type of humus will result which is different from that produced by a population consisting largely of bacteria and invertebrates. 3- Nature of soil — particularly its structure which affects penetration of water and its chemical composition, especially the reaction and abundance of basic materials. 4« Environment, especially climatic conditions, and particularly rainfall and temperature. Factors 2 and 3 are affected by 4. Thus i t was found that the rate of decomposition differed greatly depending upon the micro-organisms present and the composition of the litter itself (Tsutsumi 1963; Hayes 1965b). Comment and Summary The understanding of l i t t e r f a l l may lead to a more vivid and hopefully accurate picture of the productivity of the crop and land. A closed forest is a living dynamic ecosystem that partially perpetuates its essential nutrients by the recycling of the elements of the old decomposed tissue. When more intensive management of forests is required, the need will come (or has 16 come in some countries) when forest fertilization will be considered necessary to supplement the low nutrient level in many forest soils. Lit terfall has been quite intensively studied in Europe and Japan, but on the North American continent, the interest has so far been centred mostly on the prevention of fire hazards and on seedbed preparation, or in relation to the hydrologic cycle. The amount of l i t t e r f a l l is influenced by biomass \Aich can be cor-related with site quality. It has been found that the better the site, the higher will be the l i t t e r f a l l (Chandler 1941; Mork 1942.) But Aiba et al (1968) showed that the lower the site, the higher is the l i t t e r f a l l , because of the shorter retention period of old needles. IV Forest Floor Forest floor is defined as the accumulation of organic matter residues overlying the mineral s o i l . The silvicultural and soil-forming importance of the processes of organic matter decomposition and of the development of different humus forms was f irs t recognized by Hundeshagen in 1830 (cited by Wilde 1946). Unfortunately, his work went unnoticed, and i t was not until four decades later that Emeris suggested classifying forest humus into three types; one made up of well-decomposed organic matter incorporated with the mineral soil (H layer) and the other two made up of "raw" organic remains (L and F layers). Shortly after Emeris1 paper, Muller in 1878 and 1884 (cited by Wilde 1946) successively issued two papers on the natural humus; their relation to forest growth and their effects on soil development. Terms like "mor" and "mull" were coined and widely used from then on. A more elaborate classification of forest humus was undertaken by Heiberg and 17 Chandler (194-1) for the northern United States. An important aspect of the forest floor i s that owing to the physical, chemical and b i o l o g i c a l influences, i t buffers vegetation and micro-climate action on the s o i l , (Forest S o i l Committee 1957). According to Williams and Dyrness (1967), less than one quarter of the t o t a l available nutrient supply i s contained i n the forest floor material. The rate at which nutrients are released to plants i s of prime significance to forest productivity. The hydrological part played by the forest f l o o r i n preventing floods i s also recognized (Kittredge 1948, Mader and L u l l 1968; Warren and F f o l l i o t t 1969). The t o t a l depth and t o t a l weight of forest f l o o r s are highly variable and a large number of samples needs to be taken (Gessel and B a l c i 1963). The range between maximum and minimum values within a s i t e i s highest i n the L layer of mor and the H layer of the duff mull, but the greatest v a r i a t i o n among the sampling s i t e s occurred i n the H layer of both types. The d i f f e r e n t trends i n the formation of the forest floor depend greatly on the type of l i t t e r f a l l i n g on the s o i l surface, the factors determining the rate of decomposition, the organisms present on the s i t e and the physical property"of the s o i l (Waksman 1938). V Forest S o i l Forest s o i l i s not merely a s t a t i c , i n e r t mass of material providing moisture, nutrients and anchorage for the tree. I t also i s a complex dynamic and l i v i n g body, which often responds very favourably to modifying influences (Wilde 1946). Though the mineral elements i n the s o i l far exceed the amount needed by 18 the plants, nevertheless, most of these mineral elements are bound up i n complex compounds not rea d i l y available to the l i v i n g organisms. The weathering of rocks, the breaking down of organic matter and the chemical actions of the exudations from l i v i n g organisms help to dissolve and break down the complex compounds. On the other hand, however, there are mineral elements adsorbed on the surface of clay minerals. These mineral elements are readily exchangeable and ea s i l y absorbed by l i v i n g organisms. The physical and chemical properties of s o i l s affect the productivity s i g n i f i c a n t l y . How s o i l gravel and stone content i s related to s i t e index was reported by Carmean (1954, Lutz and Chandler ( 1957 ) . The volume of fine s o i l (less than two mm) available to supply moisture and nutrients for tree growth i s important (Stephens 1963 ) . Site index of P a c i f i c Northwest s o i l s i s found to correlate with texture, and s o i l depth (Gessel 1950). Tarrant (1949) noted that the amount of s o i l nitrogen i n Douglas f i r region seems to be closely re-lated to the amount of organic matter and that the calcium i n t h i s region i s generally low, because of pronounced leaching and also because of low o r i g i n a l calcium content i n s o i l s derived from marine sediments. The Forest S o i l s Committee of the Douglas f i r Region (1957) suggested that the f e r t i l i t y l e v e l of Douglas f i r region s o i l s i s generally w e l l within the range of values reported i n i t s publication. The surface s i x inches of s o i l i n the Cascades i s reported to have a nitrogen content from 4 ,259 to 7,398 kg. per hectare and an available phosphorus content of 8 to 12 kg. per hectare. The leaching loss from Douglas f i r region s o i l does not seem grave (Cole and Gessel 1965) and i s usually compensated by p r e c i p i t a t i o n and f i x a t i o n input (Weetman 1962 ) . 19 VI Mineral Elements Mineral elements are needed for the formation of protoplasm i n plants and animals, together with a supply of water, carbon dioxide and energy from the sun. The mineral element content i n plants often correlates with high productivity and good s i t e quality. Thus foliage analysis for mineral elements i s often used as an index of deficiency or otherwise (Gessel et al.1951; Beaton et al'1965 and Webber 1964). The available mineral elements i n the s o i l , too, have been under intensive study to determine s i t e q u a l i t y (Keser I960, Tarrant 1949, Webber 1964). On the other hand, s o i l chemists are trying to fi n d the best procedure t'o determine, a v a i l a b i l i t y of nutrients which are cor-related with growth. In order to understand the whole forest ecosystem, Ovington (1954-1958), i n a series of studies, considers every important factor and t r i e s to get at a clear picture of the nutrient cycle i n a closed forest ecosystem (Isutsumi et al.1968). Mineral Elements i n the Foliage The nutrient elements i n the foliage may d i f f e r quite s i g n i f i c a n t l y , due to the d i f f e r e n t extracting power of the species; difference i n s i t e ; p osition on the crown; age of the fol i a g e ; season of sampling and age of the tree. Thus, mineral elements i n the l i t t e r f a l l , too, may d i f f e r (Daubenmire 1953). Fluctuations i n the chemical composition of the plant during the growth period i s recognized as s i g n i f i c a n t (Lutz and Chandler 1957; Leyton 1958). Some mineral elements, for example, phosphorus and potassium are migratory as com-pared to other elements and less of these may be removed from the tree i n a natural l i t t e r f a l l (Ovington 1958). However, calcium shows a d e f i n i t e l y higher content (Gessel s i al.1951) when the old foliage f a l l s to the ground. 20 Release of Mineral Elements from Forest Floor The outflow of mineral elements from the forest floor by leaching of decaying products and the movement of soil micro-organisms has been studied by only a few workers. Thus, use of lysimeters to study the release of elements from forest floor leachates has been undertaken (Smirmova et al • 1 9 6 4 ; Cole 1964). More typical work is done on the weight loss and mineral contents after decomposition (Jenny et al»1949; Weetman 1965; Tsutsumi 1963). By measuring changes with time in the mineral contents of fresh l i t t e r , the movement of nutrients within the forest floor can be studied (Bray and Gorham 1 9 6 4 ) . Return to the Soil The major channel of the return of mineral elements to the forest soil is by way of l i t t e r , which undergoes decomposition and leaching. Litter to-gether with crownwash and stemflow have been studied (Cole et aJL.1968; Madgwick et al.1959). Annual return of mineral elements to the soil via stem flow and crown wash sources was found to be negligible for phosphorus, most for pot-assium. Nitrogen and calcium was found high in the l i t t e r f a l l component (Cole et al-1968). Potassium present in ionic form in plant tissues leaches readily (Kawada 1966). In the dead organic material, potassium and phosphorus contents are noticeably lower than in live material (Rodin et al.1965). The quantity of mineral elements leached from the tree crowns or trunks by precipitation is slight in comparison to the amount returned by the annual l i t t e r f a l l (see Table 2) but such quantity may be of some significance in the balance of such elements as calcium and potassium (Rodin et al.1965). 21 Table 2: Annual Return of N, P, K,. Ca (kg/ha) In a 36-year-old Douglas f i r stand N P K Ca Litter 13.6 0.2 2.7 11.1 Stemflow + Leafwash 1.7 0.4 12.3 4.6 (adapted from Cole s i a l , 1968) Much of the dissolved mineral elements from the forest floor or from precipitation is not leached from the soi l . The elements are either fixed on clay surfaces or immobilized by biological fixation, and thus stay in the upper portion of the soil profile (Smirnova et al.1964; Remezov 1961; Reikerk 1967). The correlation obtained between nutrient contents of l i t ter and the rate of decomposition emphasizes the value of chemical studies on the soil (Owen, 1954). FIGURE I. LOCATION MAP OF THE UNIVERSITY RESEARCH FOREST 24 8 0 _ ~60 ui •550 or UJ a. „ 3Q_ FIGURE 3. MEAN, MAXIMUM AND MINIMUM MONTHLY TEMPERATURE IN ° F FOR THE PERIOD 1959 TO 1967 (GRIFFITH 1968) STATION: UBC RESEARCH FOREST OFFICE. MINIMUM ,1 2 0 -FIGURE 4. MEAN, MAXIMUM AND MINIMUM MONTHLY PRECIPITATION IN INCHES FOR T H E PERIOD 1959 TO 1967 (GRIFFITH 1968) STATION! UBC RESEARCH FOREST OFFICE. co UJ X o 15-JO-% o UJ _ or 5-M J MONTH 25 CHAPTER THREE - METHODOLOGY  I) Description of the Area  Location The study was conducted in the Research Forest of the University of British Columbia. This is about thirty-five miles east by northeast from the centre of Vancouver and approximately four miles north of Haney. It covers an area of 1 2 , 7 3 8 acres, (5>155 hectare) see Figures 1 and 2 . Climate The region as a whole is warm and dry during the warmest six months with an average monthly precipitation of 4 - . 3 inches and comparatively mild with an average monthly precipitation of 10.6 inches during the other six months. See Figures 3 and 4-. With such a climate, the University Research Forest is with-i n the Coast Forest Region, Southern Pacific Coast Section (C-2) defined by Rowe (1959). The primary species are Douglas f i r (Pseudotsuga menziesii (Mirb.) Franco.), western hemlock (Tsuga heterophylla (Rat.) Sarg) and western red cedar (Thu.ja plicata D. Don). Study Area The study area is about 1,500 feet east from the Administration Office. The site for Douglas f i r is good (site index 1 6 5 feet at 100 years for Douglas f i r ) , with flat or nearly so topography and deep, medium to coarse textured soi l . Slash had been bulldozed and burned in piles soon after logging operation. Two-year-old Douglas f i r seedlings of University of British Columiba Research Forest seed origin grown at the B. C. Forest Service Nursery at Green Timbers were used. Western hemlock was planted a year later (1958), with FIGURE 5. SKETCH MAP OF THE MAIN STUDY AREA I PROV. 8'X8' DF * FERT. DF 6'X6' ALOUETTE RIVER ROAD F E D C B A 15' X 15' 6' X 6' 3 ' X3 ' 12' X 12' 3'X 3' 9'X 9' DF DF WH DF DF DF SCALE t-CHAINS 0 27 1 + 1 seedlings grown i n the Research Forest nursery with seeds from the University of B r i t i s h Columbia Research Forest. Five different spacings of Douglas f i r plantations, and one 3 x 3 feet western hemlock plantation, each of one-half acre (0.202 hectare), and a 0.2 acre of thi r t y - f i v e - y e a r - o l d thinned stand of western red cedar-western hemlock (si t e index for western hemlock at 100 years i s over 180) were selected for the study. This stand has about three-fourth western red cedar. The arrangement of the plots i s given i n Figure 5 « Annotations are given to each plot and are l i s t e d below: A — 9 x 9 feet Douglas f i r (Research Forest Project 57—5) B — 3 x 3 feet Douglas f i r (Research Forest Project 5 7 — 5 ) C — 12 x 12 feet Douglas f i r (Research Forest Project 5 7 — 5 ) D — 3 x 3 feet Western hemlock (Research Forest Project 5 7 — 5 ) E — 6 x 6 feet Douglas f i r (Research Forest Project 57—5) F — 15 x 15 feet Douglas f i r (Research Forest Project 57—5) CH — thinned cedar-hemlock (PSP-111 Project 56—2) (A l i s t of vegetation i n the various plots i s given i n Appendix X. I t i s noted that the plantations had several cleanings done a few years prior to the present study.) II) Methods of Sampling  L i t t e r Cuprinol (copper naphthenate i n l i g h t o i l ) treated wooden frames of inner measurement 4-5.72 x 4-5.72 cm (18 i n . x 18 in.) with p l a s t i c screens were used for l i t t e r c o l l e c t i o n . Ten of these were set up randomly by Wayne Johnston 1 i n 1967 i n each of the p l o t s , except for cedar-hemlock plantation (PSP-111 Project 5 2 — 2 ) where thirty-three of them were set up systematically. Any organic materials f a l l i n g into the frame are included. 1. A report submitted to Dr. Haddock i n Forestry 5 5 5 course. 28 These may be composed of needles, twigs, cones etc. The p l a s t i c screens with organic materials were taken at inte r v a l s and put into p l a s t i c bags, to be taken into the laboratory. They were a i r - d r i e d , i f the organic materials could not be separated from the screens immediately. Forest Floor 2 A p l a s t i c board of 20 x 20 cm was used as a standard template for cutting the forest f l o o r , which was subdivided into three layers, namely: V = Vegetation-annuals (present i n wider spacings) L = L i t t e r layer FH = Humified layer (because of the d i f f i c u l t y experienced i n d i f f e r e n t i a t i n g these two—F and H layers, they were grouped into one.) The d i f f e r e n t layers were bagged separately and taken into the laboratory. A representative section of the forest floo r i n each p l o t was selected. Samples were taken along a s t r i p from the base of a tree to the next one nearby. A replicate s t r i p running perpendicular to the f i r s t sampled s t r i p was also taken. When a perennial plant was encountered i n the s t r i p , a s h i f t to the l e f t or ri g h t was made to avoid d i f f i c u l t y i n sampling. Twelve samples were taken from the plo t with wide spacing (15 x 15 feet) and the maximum number of samples (three at the most) were taken from the closed spacing ( 3 x 3 fe e t ) . S o i l A s o i l p i t was dug i n a representative area of each plantation and the p r o f i l e described and sampled. S o i l p r o f i l e descriptions follow the directions given by the National S o i l Survey Committee of Canada (1965). 29 IlO Preparation of Samples  Plant Tissue The plastic bags containing l i t t e r f a l l were air-dried in the laboratory whenever oven-drying could not be done right away. Litter was removed from the screen and put into a tin. It was then placed in an oven at 70° G. for 48 hours and weighed. Forest floor was treated in the same way. But since i t was not collected by screens, i t was directly put into the tin and oven-dried. The organic matter was ground in an electric mill and passed through a 1 mm sieve (l6 mesh per inch). It was then stored in plastic bags for later chemical analysis. Soil Soils collected in plastic bags were spread out in the laboratory for air drying. When thoroughly dried, they were passed through a 2 mm (lO mesh per inch) sieve and the weight of stone and those passing 2 mm -sieve were re-corded. Some of the 2 mm soil sievings were ground to pass through a 0.14 mm (100 mesh per inch) sieve for semimicro—Kjeldahl method of nitrogen determin-ation (Black et al.1965). IV) Chemical Analysis of N, P, K, Ga and pH 1. Plant Tissue Total Nitrogen Determination (by Semi-micro Kjeldahl Method) A sample of 0.1000 gm. was placed in a dry Kjeldahl flask and 1.1 grams of K„S0, catalyst mixture was added. Then3 mis of concentrated H„S0. was 30 poured in and the flask was heated on a digestion stand. Black's(l965) procedure was followed. Preparation for Organic matter and P, K, and Ca  Determination (Chapman and Pratt 1961) 1.00 gm of sample was placed in a porcelain dish, with 3 mis of 50% Mg (NO-^g' 6^0 solution added. Sufficient water was added to wet the sample. The hot plate was started low and the heat was gradually increased until the sample was dry. The sample was then placed in a muffle furnace at 550° C. for three hours or more until completely ashed. Then the ash was extracted by using 5 mis 2N HC1 and made up to 100 mis. i) Total P Determination (Jackson I960) 2 mis of plant extract were pipetted into a 50 mis volumetric flask and procedure followed that of Jackson's (i960) Chlorostannous-reduced Molybdenum blue colorirnetric method. i i ) K and Ca Determination 2 mis of plant extract were pipetted and diluted to 50 mis. This was then fed into a Perkin-Elmer 303, atomic absorption spectrophotometer at 766 mu for K and 4-25 mu for Ca determination. 2. Soil Total N Determination (by Semi-micro K.jeldahl Method) Same as mentioned above except that 0.2000 gm of soil was used and in the case of more organic soil 0.1000 gm was used. Fluoride-Dilute Acid Extraction of Soluble.: P and  Determination (Jackson I960) 2.5 gm of soil were weighed out into a 50 mis centrifuge tube. Then 20 mis of dilute acid fluoride solution were added. The tube was stoppered and 31 shaken for 1 minute. It was then centrifuged and filtered. Phosphorus determination has been described above. 2 mis of aliquot was transferred to a 125 mis conical flask and 5 mis of water added. Then 3 mis of chloromolybdic acid reagent were added and finally 3 drops of dilute SnCl^ was added and shaken well. Colour reading \-jas taken after five minutes at 660 mu. Exchangeable K and Ca Extraction with NH.OAc 4 10 gm of air dried soil were weighed into a 100 mis centrifuge tube and 50 mis of IN NH.OAc were added by means of an automatic pipette. The contents 4 were then shaken for 10 minutes and left to stand overnight. They were centri-fuged and the supernatant filtered and the same procedure of adding 50 mis of NH.OAc and shaking for 5 minutes was repeated three times and made up to 250 4 mis mark. The extract was directly fed into Perkin-Elmer 303, atomic absorption apparatus for individual determination. pH Determination (in 1:1. soil? water ratio) 10 gm of soil were weighed into a beaker and 10 mis of distilled water were added and stirred. (Organic soil may need more than 10 mis of water to obtain pasty phase.) The suspension was allowed to stand for an hour and stirred regularly. The pH was measured with the glass electrode of Beckman pH meter. 32 4 -FIGURE 6. WEIGHT AND COMPOSITION OF ONE YEAR LITTER ACCUMULATION 1967 TO 1968 tsS$$3 BROADLEAVED LITTER 3 -< X _ o o o .2 -X o LU ui > o 1 -CONES AND BRANCHES NEEDLES B 3 X 3 DF E 6X6 DF A C 9X9 12X12 DF DF PLOT 15X15 DF D 3 X 3 WH CH FIGURE 7 COMPARISON OF TWO YEARS' LITTERFALL IN DIFFERENT PLOTS 00 IO 5 . 4 . < X o X. o o o t_ cc Ui 1. >vk( .•if,-.-;^; ' :•• y d 3'X3' DF 11 ?/f-'.W-.V Vm-:-'.'1,: >i-mm ill m km:-Ii « ISM?* 6X6 DF ,A , 9X9 ' DF 12X12' DF if MP mm gift ,fjif.-*.ifi • V'M')' V''-ftp '^•'iiJ'-'-s. I * mm. CH OJ OJ DF WH 34 CHAPTER FOUR - RESULTS AND DISCUSSION  Litter Accumulation in Screens The amounts and variations of the litter collected at different times of sampling are given in Appendix VII. Figure 6 breaks up the one year accumu-lation (1967 to 1968) into needles, cones and branches, and broadleaved l i t t e r . It is noted that in the Douglas f i r plots the wider the spacing the greater is the amount of broadleaved litter. In the 3 x 3 feet western hemlock plot, the amount of needle litter is less than one-half of the total l i t t e r . In the cedar-hemlock stand, the amount of cones and branches occupies a substantial percentage (24$). Among the most possible explanations are (a) that this stand is older,about 35 years-old, (b) i t has been thinned to a wider spacing and (c) i t consists of a high percent of cedar twigs. The standard deviation of each plot and the number of screens, as seen in Appendix VII, shows that there is a great variation in this kind of work. Plantation 12 x 12 feet has a very high standard deviation (46.37), which may also be due to the lesser number (7) of screens. (Ten screens were originally placed in each of the spacing plots, but due to disturbances some were lost or upset.) The standard variation of litter weights in each plot in the second year collection, which is a total of the seasonal collections from May 30, 1968 to May 30, 1969, is s t i l l very high. In addition, there is no obvious relation-ship between spacing and variation in l i t t e r f a l l . Of the plots having competi-tive vegetation (9 x 9, 12 x 12, 15 x 15 feet) Douglas f i r and 3 x 3 feet western hemlock, a l l but the 12 x 12 feet Douglas fir show a higher standard deviation than for the previous year. Table 3 - Means and Confidence Interval {95%) of L i t t e r f a l l i n Different Plots (in grn/screen) Period 3' x 3' 6' x 6" 9' x 9' 12' x 12' 15' x 15' 3' x 3' Thinned DF DF DF DF DF WH CH May 12, 1967 to May 30, 1968 85.84 * 16.82 + 64.10 20.12 + 33.49 15.14 + 51.77 42.88 + 20.93 7.37 + 24.40 10.11 + 69.28 9.05 May 30, 1968 to May 30, 1969 107.30 + 14.86 110.84 + 21.30 + 59.26 30.88 + 43.51 22.33 + 36.68 11.82 + 40.01 18.18 + 60.20 6.40 May 30, 1968 to August 20, 1968 6.94 + 2.50 + 16.24 3.83 + 6.90 5.55 + 4.99 2.15 + 8.35 3.06 + 6.43 3.23 + 4.11 1.27 August 20, 1968 to September 29, 1968 7.56 + 1.97 + 6.13 1.92 + 5.03 4-23 + 3-95 2.66 + 3-37 1.77 + 5.64 2.43 + 2.39 0.67 September 29, 1968 to November 9, 1968 6.41 + 1.19 + 7.12 1.60 + 5.09 2.10 + 5.95 3.60 + 15.41 7.63 + 12.53 8.01 + 16.38 2.78 November 9, 1968 to May 30, 1969 * 86.40 + 13.07 + 82.78 16.80 + 42.93 22.18 32.80 18.87 + 9.54 3.76 + 24.91 18.29 + 36.33 4.01 DF = Douglas Fir WH = Western Hemlock CH = Cedar--Hemlock * Unusually heavy snow prevented more frequent collections between November 9th and May 30th, 1969. 36 The confidence interval (at 95% level) of the weights of l i t ter collected under the different plots is tabulated in Table 3 in gm per screen. Figure 7 compares the weights of the 1967 to 1968 litter samples to the total weights of the 1968 to 1969 season collections. These two years' l i t ter values are found to be significantly different at 5% level. On the whole, more weight was accumulated in the 1968 to 1969 collection except for the 12 x 12 feet Douglas f i r and thinned cedar-hemlock stands. Though not much can be said about this, the extreme cold weather of the 1968 to 1969 winter may have caused the greater amount of l i t t e r f a l l (Reukema 1964). The l i t t e r f a l l accumulation of the Douglas f i r plots, from May 12, 1967 to May 30, 1969 is shown in Figure 8a. The total l i t t e r f a l l for the two years' period correlates with the density of the stand, and this follows that when the stand is dense, the amount of l i t t e r f a l l is great. The trend of the l i t t e r f a l l for the two years' collection period is that the closer the plantation the greater is the l i t t e r f a l l (see Figure 7). In the f i rs t year (1967 to 1968) l i t t e r f a l l , i t drops from denser to wider. But 12 x 12 feet Douglas f i r disrupts the trend, with a higher amount than the preceding 9 x 9 feet. The 15 x 15 feet plot drops again lower than 12 x 12 feet. The differences in the f i rs t year (1967 to 1968) are found to be highly significant and Duncan's new multiple test shows that they overlap with each other (see Appendix VIII). The l i t t e r f a l l of the second year shows a much more distinct trend. It drops significantly from denser to wider spacings ex-cept that of 6 x 6 feet plot which has a l i t t l e more than 3 x 3 feet plot. Duncan's new multiple test shows that treatment means can be divided into two groups, with overlap at 9 x 9 feet plot. These groups are: a) plots with no ground vegetation"'" ( 3 x 3 and 6 x 6 feet plantations) and b) plots with 1. Ground vegetation used here l i teral ly means vegetation on the ground (mosses and annuals). 39 associated vegetation (9 x 9, 12 x 12 and 15 x 15 feet plantations). In the l a t t e r p l o t s , hare's and deer's droppings have been found i n screens. Summary 1. In the dense spacings of Douglas f i r p l o t s , 3 x 3 and 6 x 6 feet, broad-leaved l i t t e r accounts for l e s s than 1.5% of the 1967 to 1968 l i t t e r samples. Plantation B (3 x 3) has a l i t t l e more broadleaved l i t t e r than 6 x 6 feet p l o t because of the mortality i n Douglas f i r that has occurred due to overcrowding. Plantation E (6 x 6 feet) has less than 0.2% of broadleaved l i t t e r . Although the l i t t e r f a l l i n f u l l y closed stands i s expected to eventually a t t a i n a r e l a t -i v e l y stable l e v e l (Bray and Gorham 1964). The present data are inadequate as yet to test the hypothesis. Only 3x3 and 6 x 6 feet plots are t r u l y • closed stands. 2. In these Douglas f i r plantations, the wider the spacing, the higher i s the proportion and t o t a l amount of broadleaved l i t t e r . I t i s because of the a v a i l -a b i l i t y of l i g h t and moisture (Scott 1955) that the broadleaved plants become established. 3. In plots that have broadleaved species, the v a r i a b i l i t y i n the amount of l i t t e r f a l l i s lower i n 1967 to 1968 when the period of accumulation i n trays was longer than 1968 to 1969. 4. The weight of l i t t e r f a l l i n Douglas f i r plantations of 1967 to 1968 i s i n decreasing order: 3' x 3', 6" x 6', 12' x 12', 9' x 9', 15' x 15'. ( i t should be noted that only 7 screens were collected from the 12 x 12 feet plantation at the time of sampling and the standard deviation was 46.37 compared to 21.17 of the 9 x 9 feet plantation.) I t may be said that close spacing for example, the 3 x 3 feet plantation may experience higher root competition and also i n c i d e n t a l l y 2. "Associated vegetation" here means vegetation that crowds i n during the course of growth. I t includes mostly perennial hardwood species and some ground vegetation. 40 may reduce the retention of older needles (Alba et al.1968). 5. The weight of l i t t e r f a l l in 1968 to 1969 Douglas f i r plantations s t i l l shows the decreasing order: 6' x 6', 3' x 3', 9' x 9', 12' x 12', 15' x 15'. Duncan's new multiple test (Appendix VIII) shows that in these five spacing plantations, there are two groups of plots. The f i rs t two are without associated vegetation and the last two have associated vegetation. The 9 x 9 feet plot could not be distinguished statistically, giving results seemingly half-way between the two. 6. Lit terfall of Douglas f i r , is about 3,000 kg. per hectare more than western hemlock for both years. Although reports confirming this comparison are lack-ing, a look at Tarrant et ,al's (l95l) data on western hemlock (1,050 kg/ha) and Douglas f i r in Appendix I, will clearly show that Douglas f i r produces more li t ter than western hemlock, but that the magnitude of previously reported differences is not as great as in this study. 7. Cones and branches have not been found in the l i t t e r f a l l of the closely spaced plantations, although they have been collected in the two plots C and F which are spaced 12 x 12 and 15 x 15 feet respectively. 8. The l i t t e r f a l l under the 35-year-old, thinned cedar-hemlock stand was 3,314 kg. per hectare for 1967 to 1968. It is less than that of the 3 x 3 feet Douglas f i r which had 4,106 kg. per hectare, but about the same as the 6 x 6 feet Douglas f i r plot. A considerable difference has also been observed in the second year's (1968 to 1969) sampling (see Figure 7). However, i t is perhaps not meaningful to compare the two different species, age and sites. That this thinned cedar-hemlock stand has had a greater percentage of cones and branches in the l i t t e r f a l l may be due either to older age and/or wider spacing, or more 41 l i k e l y the characteristics of western red cedar foliage separation. The data for the d i f f e r e n t spacings shows that the weight of l i t t e r i n the wider spaced plantations f a l l s within the general range of 1,000 to 2,500 kg. per hectare (derived from the l i t t e r f a l l summarized i n Appendix I for stands of d i f f e r e n t ages). However, for closer spacings ( 3 x 3 and 6 x 6 feet) the values (3,000 to 4,000 kg/ha/yr) are somewhat greater than the figures r e -ported by the other authors.. In Reukema's (1964) paper, the trend of weights with density of stand was quite obvious: the heavier the thinning (and thus, the wider the spacing), the lower was the l i t t e r f a l l . Number of L i t t e r Traps Required To determine the number of traps required for a certain degree of precision, several formulae have been used by various people. Saito et a l .(1967 and 1968) 2 2 2 and Sasa e£ al-(l968) used the formula: n=t CV /e for their recent studies i n Japan. But t h i s formula i s considered to be biased. Therefore, a di f f e r e n t 2 2 2 formula: n=t S /E i s used i n t h i s study. n: student's t for p probability l e v e l and n-1 degrees of freedom. S: estimate of the population variance. E: precision desired. The results for di f f e r e n t precisions at 95$ confidence l e v e l are tabulated i n Table 4. I t i s obvious that i n t h i s kind of study where the v a r i a t i o n involved i s usually very high, the number of l i t t e r traps needed w i l l depend on the accuracy and confidence l e v e l one assumes. I f fewer traps are used, the confidence l e v e l or accuracy or both w i l l be lower than when using more traps. Table 4 - Number of Traps Needed for Obtaining L i t t e r f a l l Weights at 5$» Prob a b i l i t y Level. P r e c i s i o n Period 3' x 3' 6' x 6« 9" x 91 12' x 12' 15' x 15' 3' x 3' Thinned Desired DF DF DF DF DF WH CH E = 10 gm May 12, 1967 to May 3 0 , 1968 24 25 20 85 7 10 28 E = 10 gm May 3 0 , 1968 to May 3 0 , 1969 19 37 70 3 9 13 , 28 15 E = 2 gm May 30, 1968 to August 20, 1968 14 30 52 10 20 22 15 E =" 2 gm August 20, 1968 to September 29, 1968 10 9 36 13 8 14 6 E = 2 gm September 29, 1968 to November 9,1968 5 7 10 26 112 112 61 E = 5 gm November 9, 1968 to May 3 0 , 1969 51 87 150 95 7 102 22 43 FIGURE 9. FOREST FLOOR ACCUMULATION IN DIFFERENT PLOTS 22-X o g GROUND VEGETATION 20-16-14-< X \ CO o o o X CD Ul Ul > o 12-10-4-L LAYER FH LAYER u . Q "ro X "ro u . Q "CO X "to C\l X "C\J u . Q "o> X "0> u. o H cc Ul u . "co X "CO X "in u. Q > O or o. "oo X oo X "ro X "to B C F PLOT CH 44 Forest Floor Accumulation i n Different Spacing Plantations Figure 9 gives the oven-dry weight of forest f l o o r i n two layers: L layer and FH layer. The FH layer has not been further separated because of the d i f f i c u l t y i n distinguishing the two layers. Under the Douglas f i r spacing p l o t s , there seems to be a rough con-sistency between the amount of forest f l o o r and spacing. The plots may be considered to consist of two d i f f e r e n t groups: one with considerable associ-ated vegetation and the other without or with r e l a t i v e l y small amounts. In general, the oven-dry weight of forest f l o o r decreases as spacing increases. In plots without ground vegetation, the accumulation decreases as spacings increase from 3 x 3 feet to 6 x 6 feet to 9 x 9 feet. S i m i l a r l y , i n the plots where associated vegetation has been well developed, the accumulation again i s l e s s , and inversely related to spacing, (from 12 x 12 to 15 x 15 f e e t ) . For a comparison, two plots have been selected, which are located (see Figure 5) across the road. One has been f e r t i l i z e d at the time of planting (U. B. G. Forest Project 58 — 15) with 6 x 6 feet spacing and the other: a provenance study plot (U.B.C. Forest Project 57 — 7 planted i n 1959) with 8 x 8 feet spacing. In these two p l o t s , some ground vegetation i s present. The accumulations were less than i n the spacing study plots of about the same spacings. These differences may be explained as possibly the r e s u l t of: a) difference i n provenance, l o c a l s i t e and age. b) the ground vegetation may contribute to the l i t t e r composition which may hasten the decomposition of the Douglas f i r forest f l o o r . The 3 x 3 feet western hemlock pl o t produces the least amount of forest f l o o r ; 6,369 kg. per hectare. This may be due to the nature of the crown which has rather few needles or perhaps the r e l a t i v e l y poor development and 45 slow growth of western hemlock planted i n the open. Thus, the forest floor of western hemlock has been found to be less than half of that of the simi-l a r l y spaced ( 3 x 3 feet) Douglas f i r (15,988 kg. per hectare) which i s only one year older. However, a great variety of shrubs and ground vegetation has been found on the western hemlock plot and some, for example, the red alder (Alnus rubra Bong) even over-topped the hemlock. This rapidly decomp-osing l i t t e r from the broadleaved components plus the scantiness of hemlock needles may account for the low amount df forest floor under the western hemlock plantation. In the thinned cedar-hemlock stand, the amount of forest floor i s 21,075 kg. per hectare which i s about twice as much as any of the spacing plots. It may be the result of the older age (35 years) of the stand or due to the difference i n species, and/or of the excellent site and also of the substantial amount of woody materials (branches, twigs and cones) which have resisted decomposition. When looking at the forest floor data of other workers, (given i n Appendix II) the values shown i n this work seem lower than the others. This may be due to the condition of the forest floor after logging and planting, or many other local stand and site differences. The study area has been logged and bull-dozed and the slash has been piled and burnt (Smith and Walters 1957). Since the area i s quite level, a considerable amount of old debris was partly turned under the s o i l or bull-dozed into piles, leaving quite a clean surface. Thus, the forest floor collected i s probably largely the result of the l i t t e r accumulated by this new twelve year old plantation. The mean dry weight of the five Douglas f i r spacing plots i s 12,000 kg. per hectare. With the inclusion of the two selected comparison plots ( f e r t i l i z e d and provenance) 46 the mean value is 11,000 kg. per hectare which is about one-third as much as the mean value of a l l the forest floor accumulation under 50 years which is 30,000 kg. per hectare (See Appendix II). It is understood that the forest floor in the temperate region is cumulative as years go by because of the slower rate of decomposition. Some variation may be caused by sampling error which accounts for the great variation in the results presented. For example, values shown for stands up to forty years of age vary from 11,000 to 73,000 kg. per hectare. The replication of the L. layer in the sampling of forest floor in each Douglas f i r plantation has been found to be non-significantly different ex-cept for 12 x 12 feet plots, where the difference is significant at 5$ level. However, in the forest floor studies, significant differences have been found in the replicates of the B (3 x 3 feet), A (9 x 9 feet), C(12 x 12 feet) and F (15 x 15 feet), the former two being at 1% level. , Duncan's new multiple test shows that the amount of L. Layer of C (12 x 12) is significantly greater than that of E (6x6 feet) which is significantly greater than A (9 x 9 feet), F (15 x 15 feet) and B (3x3 feet), whereas forest floor B (3 x 3 feet) is significantly different from C (12 x 12 feet), E (6 x 6 feet); F (15 x 15 feet) and A (9 x 9 feet). Until more detailed work has been done, the difference in C, E, F, A can not be statistically evaluated. Summary 1. The micro-site variability of the place of sampling may affect the amount of forest floor accumulation quite drastically. This may help to explain the discrepancies noted. 4 7 2. Subsequent sampling of two plots of spacings 6 x 6 feet (Project 57—15) and 8 x 8 feet (provenance study, Project 57—7) shows lower values for fo r e s t f l o o r weights (See Figure 9) than for the comparable spacing p l o t s , but the relationship between spacings i s quite consistent with that of the 6 x 6 and 9 x 9 feet spacing study p l o t . 3. The western hemlock plantation ( 3 x 3 f e e t ) , shows the least amount of forest f l o o r . The percentage of broadleaved material i s about 59$ of the l i t t e r f a l l i n screens l e f t i n place for a year. (1967-68) 4 . Comparing Douglas f i r and western hemlock of the same spacing ( 3 x 3 f e e t ) , i t i s evident that on the western hemlock s i t e the forest floo r i s t h i n . Moreover, i n the Douglas f i r p l o t , ground vegetation has been absent, whereas i n the western hemlock p l o t , the associated vegetation has beendense and some (red alder and black cottonwood etc.) are even t a l l e r than the hemlock. 5. Douglas f i r spacing plantations of 3 x 3 feet and 6 x 6 feet have no ground vegetation. The forest f l o o r sample i n the 9 x 9 feet p l o t also has no ground vegetation, although the d i s t r i b u t i o n of ground vegation i s patchy and i s even dense at some other places within the p l o t . The amount of forest f l o o r decreases as spacing widens. This i s upset, however, when the spacing i s at 12 x 12 feet. The amount drops again when the spacing i s 15 x 15 feet. Relationship between L i t t e r f a l l and Forest Floor Accumulation In general, the closer the spacing, the greater i s the l i t t e r f a l l and forest f l o o r accumulation. In t h i s study, the f i v e Douglas f i r spacing plots may be placed into two groups; one without associated vegetation and the other with associated vegetation. In the f i r s t group (3 x 3 to 9 x 9 f e e t ) , 48 i t can be said that the amount of l i t t e r f a l l or forest f l o o r i s highest i n the plantation of the closest spacing and lessens as spacing widens. In th i s study beyond 9 x 9 feet i n i t i a l spacing, competitive vegetation generally i n -creases i n abundance and causes a higher value i n l i t t e r f a l l or forest f l o o r than the preceding closer spacings. This assumption i s for a plantation and where the associated vegetation consists of competitive volunteer species. The r a t i o of l i t t e r f a l l over the forest f l o o r i s presented i n Table 5. Table 5'. Index of Forest Floor Turnover Douglas f i r Spacing(Feet) 3x3 6 x 6 9 x 9 12 x 12 15 x 15 L i t t e r kg/ha/yr ( l ) 4,106.46 3,066.45 1,602.11 2,476.67 1,001.26 Forest Floor kg/ha (2) 15,987.50 12,251-55 9,029.53 12,979.15 9,759.38 Ratio (1/2) 0.26 0.25 0.18 0.19 0.10 This index i s a rough measure of forest floor turnover rate. The resul t presented here shows that the closer-spaced the plantation, the higher the r a t i o (0.26)j the wider-spaced the plantation, the lower i s the r a t i o (0.10). This r e s u l t indicates that under the dense stand, the micro-climate favours more rapid turnover — of prime importance probably on t h i s s i t e i s the s o i l water regime, although differences i n s o i l water and temperature have not been measured. On the other hand, i t would be expected that the contribution of broadleaved material to the conifer l i t t e r would favour a more rapid turnover than i f the l i t t e r i s composed of pure conifer needles and twigs. 49 S o i l The s o i l p r o f i l e c h a r a c t e r i s t i c s for the Douglas f i r and western hemlock plantations and the cedar-hemlock stand are described i n Appendix I I I and summarized i n Table 6. Table 6: C l a s s i f i c a t i o n of S o i l P r o f i l e into Parent Material, Texture and Sub-group Plantation Parent Material Texture Sub-soil group DF B (3x3) Ablation till/outwash Loamy sand Orthic humo-ferric podzol DF E (6x6) Ablation t i l l to outwash S i l t Orthic humo-ferric podzol DF A( 9x9) Ablation till/outwash Loam Orthic humo-ferric podzol DF 0(12x12) Ablation till/outwash S i l t loam Orthic humo-ferric podzol DF F(15x15) Outwash Gravelly Gleyed mini humo-ferric loamy sand podzol WH D (3x3) Outwash Loamy Sand Orthic humo-ferric podzol GH Thinned Ablation till/outwash S i l t loam Orthic humo-ferric podzol DF = Douglas f i r WH = Western Hemlock CH = Cedar-hemlock I t i s understood that although the s o i l i s c l a s s i f i e d under the same sub-group except for the 15 x 15 feet plantation and that the parent material i s the same outwash, the texture d i f f e r s considerably. Thus, i t i s expected that growth w i l l d i f f e r due to diff e r e n t soil-water regimes and that the growth w i l l r e f l e c t the differences i n water-holding a b i l i t y of the s o i l . Mineral Elements i n L i t t e r f a l l . Forest Floor and S o i l  Nitrogen Nitrogen content i n l i t t e r f a l l and forest f l o o r i s given i n percentage i n Table 7. The concentration i n the l i t t e r f a l l , except for cedar-hemlock stand, i s higher than i n the L layer of the forest f l o o r and t h i s i n turn i s higher 50 than that found i n the FH layer. I t i s calculated by the loss on i g n i t i o n that the FH layer contains more mineral matter than L layer. Thus, on the basis of actual organic matter, FH layer contains higher nitrogen content, because as decomposition advances, the concentration of mineral elements increases. The work by Webber (1964) on l i t t e r f a l l of Douglas f i r gives a comparable N content of I.46 to 1.56$, a l i t t l e higher than t h i s study. But W i l l (1959) reported from 0.83 to 1.07$ which i s low when compared to t h i s study. Nitrogen content i n forest f l o o r i s within the range given by Gessel and B a l c i (1963) but higher than that given by the Forest S o i l Committee of Douglas f i r region (1957) and Youngberg (1966). Although the above res u l t s give the content as a whole without separating the layers, i t i s s t i l l a good compar-ison to make. For the western hemlock p l o t , nitrogen content i n l i t t e r (l.47$) i s greater than that ( l . l l to 1.39$) of Webber (1964). No particular trend i s observed i n the nitrogen content of the di f f e r e n t Douglas f i r p l o t s , except for a very high content i n 15 x 15 feet plot (2.25$) which may be due to ground vegetation f a l l i n g into traps. The nitrogen content i n t h i s study i s similar i n Douglas f i r and western hemlock but Webber (1964) had a higher value for Douglas f i r . However, between cedar-hemlock and Douglas f i r plots quite a s i g n i f i c a n t difference i n nitrogen content i s observed i n t h i s study (0.67$ and 1.47$)respectively, but not i n Webber's ( 1 9 6 4 ) . Concentrations of nitrogen i n current needles of Douglas f i r within the range of 0.6 to 2.3$ have been reported by Gessel et a l (1950). Heilman and Gessel(1963) reported that the range i s 0.89 to 1.05$ i n u n f e r t i l i z e d Douglas f i r trees of between t h i r t y to fifty-two years of age. For western red cedar, Table 7: Chemical Contents i n Percent Dry Weight of L i t t e r f a l l (1967-1968)*, and Three Layers (V, L, FH) of Forest Floor 6»x6« 8'x8' 3'x3« 3'x3« 6'x6« 9fx9< LE'x^' 15'xl5! Fert Prov WH CH DF DF DF DF DF DF DF Ig n i t i o n Loss L Layer 89.77 81.45 81.56 74.34 90.88 _ _ 86.63 93.93 % FH Layer 67.40 59.54 60.99 50.79 58.73 - - 62.04 78.69 Nitrogen % L i t t e r f a l l 1.48 1.47 1.36 1.46 2.25 mm 1.47 0.67 of Sample V Layer - - - 1.88 1.63 - ' — - — L Layer 1.48 1.22 1.22 1.15 1.65 1.05 1.29 0.93 0.80 FH Layer 1.15 1.06 1.11 0.91 1.44 0.97 1.23 0.81 1.40 Phosphorus % L i t t e r f a l l 0.125 0.114 0.103 0.106 0.121 _. 0.078 0.035 V Layer - - - 0.295 0.253 - - - -L Layer 0.116 0.110 0.104 0.096 0.100 0.104 0.058 0.110 0.043 FH Layer 0.030 0.059 0.038 0.130 0.074 0.008 0.076 0.075 0.083 Potassium % L i t t e r f a l l 0.075 0.088 0.088 0.068 0.085 _ 0.075 0.045 V Layer - - - 1.375 1.775 - - - — L Layer 0.085 0.073 0.083 0.095 0.105 0.055 0.153 0.075 0.058 FH Layer 0.043 0.038 0.038 0.050 0.038 0.028 0.065 0.065 0.040 Calcium % L i t t e r f a l l 0.400 0.563 0.475 0.513 0.975 _ 1.225 1.500 V Layer - - - 0.410 0.738 - - - — L Layer 0.403 0.408 0.525 0.408 0.715 0.558 0.508 1.025 1.208 FH Layer 0.248 0.265 0.293 0.163 0.200 0.338 0.338 0.400 0.653 * = L i t t e r f a l l was those collected between May 12, 1967 to May 30, 1968. The determination was done on a composite sample 52 Table 8: Chemical Properties of Soil Plantation Depth pH N$ Avail. Exchangeable 2% Stone P ppm. K (ppm) Ca (ppm) mm % B Ap 0 -24 5.07 0.574 15.2 96.25 600.0 61.3 38.7 3'x 3' Ahe 24-34 5-19 0.178 2.0 33.75 302.5 60.3 39.7 DF Bfh 34-47 5.40 0.175 2.0 25.50 181.5 7.6 92.4 Bf 47-62 5.60 0.382 3.5 21.50 80.0 38.0 62.0 B I I c 62-74 5-75 0.270 35.0 23-75 99.5 38.9 61.1 I I C 74+ 5-77 0.207 0.0 10.50 35.0 50.7 49.3 E Ap 0-12 5.00 0.434 19.0 85.00 550-0 59.1 40.9 6'x6' Ae 12-19 4-78 0.273 16.5 21.75 152.5 63.2 36.8 DF Bf 19^47 5-50 0.217 6.0 18.75 50.0 45-1 54.9 BC 47-52 5-75 0.123 10.0 19.25 243.0 49.0 51.0 C 52+ 5.77 0.116 6.0 17.00 140.0 36.9 63.1 A Ap 0-10 4-90 0.567 28.5 96.25 4,200.0 49.7 50.3 9'x9' Ae 10-13 4-60 0.175 4.0 27.00 212.5 71.3 28.7 DF Bth 13-18 5.02 0.434 9.0 23-75 10.0 57.0 43.0 Bf-, 18-41 5.18 0.277 0.0 >• 22.75 11.5 61.1 38.9 Bf 41-61 5-48 0.165 0.0 13.00 37.5 46.5 53-5 BIIC 61-71 5-67 0.273 0.0 10.75 40.0 44.8 55.2 C Ap 0-17 4.73 0.693 18.5 115-50 1,260.0 52.3 47.7 ISfxL? 1 Ae 17-20 4-90 0.193 11.5 24-50 417.5 80.9 19.1 DF Bth 20-30 5.32 0.284 18.0 30.00 205.0 50.1 49.9 Bf 30-49 5.45 0.193 12.0 19.00 136.3 54.9 45.1 BIIC 49-75 5.50 0.126 4-5 12.00 88.8 58.7 41.3 IIC 75+ 5.52 0.070 6.5 8.00 79.0 37.6 63.4 F Ap 0-9 4.90 0.455 31.0 58.75 380.0 59.4 40.6 15'x 15* Bf 9-13 5-60 0.266 0.0 15.00 61.5 36.8 63.2 DF Bfg 13-56 5-95 0.168 10.0 28.50 77.5 33.2 66.8 Bfc 56-72 5.85 0.280 0.0 25.00 66.3 36.3 63.7 C 72+ 6.00 0.046 0.0 19.25 45.5 47.4 52.6 D Ap 0-5 5-61 0.242 3.0 27.00 110.0 58.9 41.9 WH Ae 5-6 5-46 0.067 4.0 15.75 31.3 82.7 17.3 3'x 3 ' Bf 6-13 5.60 0.154 4.5 12.50 15.8 63.7 36.3 Bf^ 13-43 5.60 0.109 0.0 9.00 11.3 52.1 47.9 BC^ 43-56 6.01 0.095 3.0 11.50 13.8 46.2 53.8 C 56+ 5.79 0.095 9.0 9.25 31.0 33.3 66.7 Thinned Bf 0-13 5.40 0.427 1.0 16.5 31.0 63-3 36.7 CH B f i 13-17 5.48 0.410 1.5 9.3 62.5 67.6 32.4 BIIC 17-24 5-50 0.364 1.0 5.5 30.0 49.8 50.2 IIC 24+ 5.50 0.196 0.5 5.5 41.8 . 53.9 46.1 53 Gessel (1950) reports that the range i s 0.70 to 1.44$. Nitrogen i n S o i l Table 8 gives some chemical properties of the s o i l s . In general, the deeper the horizon sampled, the less i s the nitrogen content except for the Ae horizon. According to Tarrant (1949), t o t a l nitrogen content of 0.55$ has been obtained from a s i t e I Douglas f i r s o i l . But, except for the 6 x 6 feet and 15 x 15 feet p l o t s , the present results show values higher than 0.55$ t o t a l nitrogen (see table 8). The nitrogen content i n 3 x 3 feet western hemlock has the lea s t value (0.242$) i n the top horizon. Phosphorus Table 7 gives the phosphorus content i n percent for the various plots. With respect to the l i t t e r f a l l i n the one year sample (May 1967 to May 1968), the trend from 3 x 3 feet to 9 x 9 feet i s i n decreasing order but there i s a sudden increase i n phosphorus content from 12 x 12 feet to 15 x 15 feet. This can be explained by the fa c t that these l a t t e r two plantations contain quite a considerable amount of associated vegetation, as seen from the high values of phosphorus i n the V layer i n these two plantations. The phosphorus content i n Douglas f i r l i t t e r i n t h i s study seems compar-able to values obtained by W i l l (1959), but lower than Webber's (1964) values (0.12 to 0.22$). As for the forest f l o o r , the phosphorus content i n the L layer shows a d i s t i n c t downward trend from dense to wider spacings. But i n the FH layer, phosphorus seems highly variable and no consistency i s apparent. The phosphorus content reported by Gessel and B a l c i (1963) and Forest S o i l Committee of 54 Douglas f i r Region (1957) agrees with the findings, but Youngberg's (1966) results are higher than that found i n this study. The phosphorus content i n the l i t t e r of the 3x3 feet western hemlock plot i s appreciably lower than the,Douglas f i r of the same spacing, but Webber's (1964) results do not show any great difference between the two species. In the thinned cedar-hemlock stand, the phosphorus content i n l i t t e r i s low (0.035$), which disagrees with the high values i n Webber's work (0.16 to 0.23$). A phosphorus concentration of about 0.16$ occurs i n the needles from 131 to 150 years old rejected plus Douglas f i r candidate trees (Beaton et ai.1964). Heilman and Gessel (1963) find considerably higher levels, i n the order of 0.29 to 0.26$ i n needle samples taken from 30 to 52 years old Douglas f i r . According to Gessel et al.. (i960) the phosphorus content of Douglas f i r needles i s usually between 0.1 and 0.25$. Available Phosphorus i n Soil The available phosphorus content i n s o i l i s very low (Table 8). No dis-tinct trend between the spacing plantations has been observed. The deeper the horizon, the less i s the available phosphorus. This available phosphorus i s usually i n the form of ortho-phosphate ions, H2P0^ and HP0~. The relative amounts of these two ions, which can be absorbed by plants, are affected by the pH of the medium surrounding the roots. Lower pH values would decrease the absorption of HPOT form. Other forms of phosphorus are absorbed too. They are 4 pyrophosphates, metaphosphates and perhaps some soluble organic phosphates. 55 Average values of available phosphorus given by Tarrant (1949) for Douglas f i r s i t e s I, I I , I I I and IV are 39, 31, 11 and 26 ppm. These figures cover the range of values reported here. (See Table 8). In the 3 x 3 feet western hemlock p l o t , the available phosphorus value i s generally lower than i n the Douglas f i r plots. The thinned cedar hemlock stand has a very low available phosphorus content ( l ppm). Low phosphorus values are characteristic of highly acidic P a c i f i c Northwest s o i l s (Tarrant et a l .1951). Potassium No d i s t i n c t trend can be observed from the l i t t e r f a l l as to i t s potassium content (Table 7). The value i n t h i s study (the average content for Douglas f i r plots) i s about 0.08$ which corresponds with the average given by Webber (1964), but i s much lower than the value (0.25$) given by W i l l (1959). In forest f l o o r , especially i n the L layer, there i s a trend towards higher potassium contents at wider spacing. But, no such trend has been ob-served i n the FH layer. The present value i s lower than the work of other authors such as Gessel and B a l c i (1963), Youngberg (1966) and Forest S o i l Committee of Douglas f i r region (1957). I t should be noted that the vegetation on the forest f l o o r gives an average potassium content of 1.6$ i n two wider Douglas f i r plantations (12 x 12 and 15 x 15 feet) where ground vegetation has been found. Western hemlock l i t t e r and forest f l o o r have about the same concentration (0.075$) as Douglas f i r i f not lower. But the cedar-hemlock pl o t has a lower value than both western hemlock and Douglas f i r . Heilman and Gessel (1963) 56 i n their Washington study showed that the potassium content i n foliage of u n f e r t i l i z e d Douglas f i r varied between 0.50 and 0.38$. Values of 0.3 to 1.0$ are considered to be t y p i c a l for Douglas f i r . However, i n t h i s study,potassium content i n the l i t t e r f a l l (0.08$) i s substantially lower. I t may be due to ex-cessive leaching i n t h i s high r a i n f a l l coastal region, especially since much of the l i t t e r i n screens was exposed for long periods of time for the 1967 to 1968 c o l l e c t i o n s . Nye (l96l) reported extraordinarily high leaching i n t r o p i c a l f orest. Exchangeable potassium i n the s o i l does not follow any pattern i n the d i f f e r e n t p l o t s . The amount of exchangeable potassium as the depth of horizon sampled, increases (Table 3). Calcium Calcium content i n the l i t t e r f a l l of Douglas f i r plots ranged from 0.400$ to 0.975$. The wider spacing seems to contain a higher amount than the closer spacing. The r e s u l t for the Douglas f i r plots i s about half as much as given by Webber (1964) and W i l l (1959). The calcium contents i n western hemlock and western red cedar are much higher than the Douglas f i r plots. Webber (1964) shows t h i s trend i n his work too. The re s u l t s for the forest f l o o r samples do not permit any d e f i n i t e con-clusions. Values ranging from 0.32 to 0.86$ are given by Forest S o i l Committee of Douglas f i r Region (1957). But what Youngberg (1966) has reported ranges from 0.33 to 1.05$. These results cover the present work. Gessel et a l . (1950) have presented figures as high as 0.80$ for Douglas f i r f o l i a g e . The customary range i n calcium content of Douglas f i r has been reported to be between 0.2 and 0.75$ (Gessel et a l . I960). Calcium concentration i n 57 western hemlock foliage samples i n Beaton et al's (1965) work appears to be lower than that of Douglas f i r . However, the calcium content of the western hemlock l i t t e r i s almost as high as that of cedar-hemlock p l o t , and considerably-higher than that of Douglas f i r . This may be attributed to the contribution from the associated vegetation (See Figure 6). A noticeably high concentration i s present i n the western hemlock plot (1.225 and 1.025$) and cedar-hemlock p l o t (1.500 and 1.208$) for l i t t e r f a l l and fore s t f l o o r respectively. Gessel e_t al_.(l95l) have also observed high calcium values for western red cedar forest f l o o r . Exchangeable Calcium i n S o i l No d i s t i n c t pattern i n calcium concentration i s observed i n the Douglas f i r p l o t s (See Table 8). On the whole, plantations 3x3, 6 x 6 and 15 x 15 feet have low values from 380 to 600 ppm, but plantations 9 x 9 and 12 x 12 feet have extremely high value of 4,200 and 1,260 ppm. As for western hemlock plantation, 110 ppm. of exchangeable calcium i s present. The mineral s o i l of cedar-hemlock has 31 ppm. Variation i n Chemical Content i n Seasonal L i t t e r f a l l A set of l i t t e r f a l l samples collected between May 30th to August 20th, 1968, from the various study plots were analysed for the chemical content. Table 9 gives the results with v a r i a t i o n and number of samples employed. Nitrogen was l e f t out because i t i s a di f f e r e n t procedure altogether, and due to time l i m i t a t i o n . Table 9s Variations i n Chemical Contents i n Different Plots of Seasonal (May 30 to August 20, 1963) L i t t e r f a l l Samples P l o t Species ' x 3« DF 6' x 6« DF 9' x 9' DF 12' x 12« DF 15« x 15' DF V x 3' WH CH W u o x\ ft 01 o p-i No. of Samples x {%) Range SD CV % 10 0.051 0.024-0.093 0.017 33.0 10 0.104 0.088-0.161 0.022 21.0 9 0.065 0.019-0.143 0.044 68.0 8 0.145 0.054-0.260 0.069 48.0 10 0.126 0.050-0.178 0.044 35.0 9 0.111 0.073-0.191 0.037 33.0 17 0.038 0.001-0.063 0.017 45.0 •H 01 01 - P o CM No. of Samples - (%) x Range SD CV % 10 0.083 0.038-0.133 0.026 31.0 10 0.073 0.050-0.168 0.033 45.0 9 0.385 0.110-1.008 0.343 89.0 8 0.519 0.113-1.215 0.429 83.0 10 0.422 0.065-0.835 0.266 63.0 9 0.230 0.038-0.663 0.230 100 17 0.086 0.035-0.355 0.071 83.0 •H O rH a o No. x of Samples (*) Range SD CV % 10 0.588 0.353-0.850 0.133 23.0 10 0.752 0.590-0.950 0.114 15.0 9 0.672 0.233-1.225 0.297 44.0 8 0.692 0.500-0.988 0.160 23.0 10 0.955 0.483-1.415 0.330 35.0 9 1.286 0.725-1.730 0.284 24.0 17 0.633 0.515-0.795 0.088 14.0 DF = Douglas F i r j WH = Western Hemlock: CH = Thinned Cedar-Hemlock; — = Mean Value; SD = Standard Variation; CV = Co-efficient of Variation. 59 Phosphorus The phosphorus contents in the five spacing plantations of Douglas f i r are found to be significantly different at 1% level. By ranking the treatment means with Duncan's new multiple test, i t is found that 3 x 3 feet plot is significantly different (5$) from 12 x 12 and 15 x 15 feet plots. The rest of the plots cannot be statistically distinguished at 5% significant level. The variations in the widely spaced plots ( 9 x 9 feet and wider) are greater than the closely spaced plots. This was due mainly to the presence of associated vegetation in these widely spaced plots. The phosphorus contents in the Douglas f i r and western hemlock plots of the same ( 3 x 3 feet) spacing are found to be significantly different at 5% level. Comparing the annual (Table 7) and seasonal (Table 9) l i t t e r f a l l of the five spacings, the phosphorus content differs greatly only in the 3 x 3 , 9 x 9 and 12 x 12 feet plots. The reason for the difference is not known. Most probably, i t may be the seasonal variation in the chemical content. In the 3 x 3 feet western hemlock, there is a difference of 0 .033$, but the cedar-hemlock stand did not show much difference. Potassium The potassium contents in the five Douglas f i r plots are found to be significantly different at 1% level. It is obvious that the plots can be divided into two groups; one with associated vegetation and the other with none. However, plot 3 x 3 feet (without associate vegetation group) could not be distinguished by Duncan's new multiple test at a 5% level. The potassium contents in the Douglas f i r and western hemlock plots of the 60 same 3 x 3 feet spacing are found to be non-sig'nif i c a n t l y d i f f e r e n t at 5$ l e v e l . Comparing the values of potassium i n the annual (1967 to 1968) and the seasonal c o l l e c t i o n s , 9 x 9 , 12 x 12 and 15 x 15 feet plots of the l a t t e r have a higher concentration of potassium than the annual c o l l e c t i o n . Most probably, the seasonal c o l l e c t i o n presents a true picture of potassium i n the l i t t e r f a l l of the wider spacings. As soon as the l i t t e r from these widely spaced plots f a l l s into the screens, potassium starts washing o f f to an extent that i t s amount i s decreased with time. Thus, seasonal differences may have disappeared due to leaching losses. I t may be assumed, however, that i n the clo s e l y spaced plots ( 3 x 3 and 6 x 6 f e e t ) , less potassium i s i n c i r c u l a t i o n and so l e s s i s leached. In the western hemlock pl o t the seasonal determination shows a higher potassium value than the annual samples. But the cedar-hemlock stand does not. Calcium The calcium contents of the f i v e Douglas f i r plots are found to be s i g n i f i c a n t l y d i f f e r e n t at 5% l e v e l . Plots 3 x 3 and 9 x 9 feet are s i g n i f i -cantly lower than that of 15 x 15 feet p l o t . The calcium content i n the Douglas f i r and western hemlock of the same 3 x 3 feet spacing are found to be s i g n i f i c a n t l y d i f f e r e n t at 1% l e v e l . The seasonal and annual determination of calcium i n Douglas f i r did not show any d i s t i n c t relationship. In the western hemlock p l o t , the calcium content i n seasonal and annual determination, i s r e l a t i v e l y the same. But the seasonal samples i n cedar-hemlock plot shows a lower calcium content, No possible explanation can be given. Table 10: Nutrient Contents i n 1967-1968 L i t t e r f a l l (kg/ha/yr) and Forest Floor (kg/ha) Fert. Prov. Thinned DF DF DF DF DF DF DF WH Cedar-V x 3' 6' x 6« 9' x 9 1 12' x 121 15! x 15' 6 1 x 6' 8'x 8« 3' x 3" Hemlock Nitrogen L i t t e r f a l l 60.78 45.08 21.79 36.16 22.53 - - 17.16 22.21 L Layer 55.44 74.29 61.39 82.30 62.68 55.70 46.54 22.82 43.93 FH Layer 140.78 65.32 44.37 52.99 85.83 59.47 62.02 31-69 218.47 Forest Floor 196.22 139.61 105.76 135.29 148.51 115.17 108.56 54.51 262.10 Phosphorus L i t t e r f a l l 5.13 3.50 1.65 2.63 1.21 - - 0.91 1J6 L Layer 4.35 6.70 5-23 6.87 3.80 5.52 2.09 2.70 2.36 FH Layer 3.67 3.64 1.52 7.57 4-41 0.49 3.83 2.93 12.93 Forest Floor 8.02 10.34 6.75 14.34 8.21 6.01 5.92 5.63 15.29 Potassium L i t t e r f a l l 3.08 2.70 1.41 1.68 0.85 - - 0.88 1.49 L Layer 3.18 4-45 4.18 6.80 3.99 2.92 5.52 1.91 3.19 FH Layer 5.26 2.34 1.52 2.91 2.26 1.72 3.28 2.35 6.23 Forest Floor 8.44 6.79 5.70 8.71 6.25 4.64 8.80 4.26 9.42 Calcium L i t t e r f a l l 16.43 17.26 7.61 12.71 9.76 - - 14.30 49.71 L Layer 15.10 24-84 26.42 29.20 27.16 29.60 18.33 25.16 66.34 FH Layer 30.36 16.33 11.71 9.49 11.92 20.72 17.04 15.65 101.76 Forest Floor 45-46 41.17 38.13 38.69 39.08 50.32 35-37 40.81 168.10 62 FIGURE 10. DISTRIBUTION OF CHEMICAL NUTRIENTS IN LITTER-FALL (KG/HA/YR) AND FOREST FLOOR (KG/HA) UNDER DIFFERENT DOUGLAS FIR SPACING PLANTATIONS 100-50-UJ > O •51 x N (FF) * Ca (FF) ' N ( L ) § 0 - A ~~ * Ca (L) | : * - . T • * P (FFi * 1 • * . K (FF) x UJ A > o g * P ( L ) Ti-K(L) (L) LITTERFALL (FF) FOREST FLOOR B E A C t. 3 X 3 6 X 6 9X9 12X12 15X15 63 FIGURE II. NITROGEN CONTENT IN DIFFERENT PLOTS IN PERCENT 5 0 H x A A. A 7 A O o o^°1 9 * * o ••5 i LxJ CD O or r -FIGURE 12. PHOSPHORUS CONTENT IN DIFFERENT PLOTS IN PERCENT A I YEAR LITTERFALL X VEGETATION LAYER o L LAYER 7 FH LAYER •l -A CO r> or O-05-X CL 7 CO V A o X CL •01 B E A C F G , , I . ,D , CH 3'X3' 6'X6' 9*9* I2'XI2' 15'xtf 6'X6 8X8 3X3 DF DF DF DF DF DF DF WH 64 K M FIGURE 13. CALCIUM CONTENT IN DIFFERENT PLOTS IN PERCENT A A 0 O A 111 A FIGURE 14. POTASSIUM CONTENT IN DIFFERENT PLOTS IN % A I YEAR LITTERFALL x VEGETATION LAYER o L LAYER v FH LAYER O , -I o A A or UJ V 7 V V A 7 •01 3X3 DF 6'X6' DF 9^9" DF ,C , 12X12 DF ,F , 15X15 DF # WH CH 65 Summary The chemical properties of the 1967 to 1968 l i t t e r f a l l , and the L and FH layers of forest floor are given i n Table 7. The amounts of nutrient elements i n kg. per hectare are reported i n Table 10. The mineral elements i n the FH layer show a generally consistent lower percentage than that i n the L layer. However, l i t t e r f a l l contains about the same mineral content as the L layer, i f not more. The most probable explanation for this i s leaching and/or some other forms of chemical change. Associated vegetation found especially i n the plantations spaced at 12 x 12 and 15 x 15 feet contains a higher percentage of phosphorus and potassium than that i n the pure coniferous l i t t e r . The significance of associated vegetation with regard to nutrients has been recognized (Scott 1955, Ovington 1956), but this does not apply to the establishment of a young stand where they would compete with seed-lings for nutrients. In the cedar-hemlock stand i n respect to the annual collection, the per-centage of phosphorus and potassium seems lower than i n the Douglas f i r plant-ations; on the contrary, the percentage of calcium i s higher. This may be due to the inherent nature of western red cedar, which contains more calcium. Western hemlock does not seem to differ much, but the concentration of calcium i s higher than that of Douglas f i r . The contribution of calcium from the associated vegetation i n the hemlock plot should not be overlooked (See Figure 6). The distribution of the amount of mineral nutrients i n l i t t e r f a l l and on the forest floor under differently spaced Douglas f i r plantations follows a distinct pattern (Figure 10). Under the plots with no associated vegetation ( 3 x 3 and 6 x 6 feet) and under the plots with ground vegetation (12 x 12 66 and 15 x 15 f e e t ) , the tendency i s : the denser the stand, the higher i s the amount of nutrient content. This may be related to the trend that l i t t e r f a l l i s higher i n denser plantations or to the trend that forest f l o o r accumulation i s greater i n denser plantations. But no d i s t i n c t relationship can be observed i n the mineral contents of the different plantations (Figures 11, 12, 13 and 1 4 ) . More samples should be obtained for analysis to give results which would j u s t i f y s t a t i s t i c a l analysis for testing significance. Also replicated spacing plant-ations are desirable to measure variations due to s o i l or other differences. No relationship can be observed between l i t t e r f a l l or forest f l o o r and growth (represented by average dbh and average height: data obtained from the Research Forest, Appendix LX). As has been mentioned e a r l i e r , differences i n s o i l texture may affect growth s i g n i f i c a n t l y (Gessel 1950). Spacing control i s a means of providing conditions favouring growth of i n d i v i d u a l trees. The optimum density changes as the stand matures. I t i s clear that the 3 x 3 feet plantation has grown to the point where competition has become eff e c t i v e . A slowing of diameter growth, natural thinning and wind-throw have been observed. On the other hand, i n the plantation of widest spacing, (15 x 15 f e e t ) , growth i n height or dbh did not show d i s t i n c t super-i o r i t y over the closer spacings. Thus, i t would appear that something between that of the widest and closest spacing at t h i s age (12 years) would be the best spacing. Preference should be given to 6 x 6 or 9 x 9 feet. But t h i s may have to be changed to a wider spacing at an older age as for example by thinning, i n order to prevent excessive reduction i n growth. The phosphorus, potassium and calcium contents i n the seasonal l i t t e r f a l l were found to be s i g n i f i c a n t l y d i f f e r e n t under the f i v e Douglas f i r spacings. This shows that the nutrient cycle with various associated • -vegetation i s 67 d i f f e r e n t . A f u l l e r use must be made of the associated vegetation's di f f e r e n t mineral composition i n c o n t r o l l i n g the nutrient cycle once we have more complete information. CHAPTER FIVE - GENERAL CONCLUSIONS The l i t t e r f a l l i n t h i s experiment follows a d i s t i n c t pattern, that i s : the denser the plantation, the higher i s the l i t t e r f a l l . The most probable cause i s the shorter retention of the needles under dense over-shading. This r e s u l t follows the same pattern as the thinning-plot study of Reukema (1964-), where the unthinned has the highest l i t t e r f a l l . In Aiba et a l ' s (1968) s i t e study, the lowest s i t e which contains the densest number of trees has the greatest l i t t e r f a l l . They also found the new leaf volume to be equal regard-less of s i t e . The f i v e Douglas f i r spacing plots may be divided into two groups: one e s s e n t i a l l y without and the other with associated vegetation. Under the dense plantations ( 3 x 3 and 6 x 6 feet) no ground vegetation has been found. The l i t t e r f a l l decreases as spacing increases. The 9 x 9 feet plantation seems to be the changing point between the with and without associated vegetation con-d i t i o n . Under the group with associated vegetation (12 x 12 and 15 x 15 f e e t ) , i t i s found that 12 x 12 feet plot has more l i t t e r f a l l than the l a t t e r . The two years' samples were found to be s i g n i f i c a n t l y d i f f e r e n t . The most probable cause i s suggested to be the severe winter of the second year (1968 to 1969). Quite a substantial l i t t e r f a l l difference i s also found between Douglas f i r and western hemlock of the same spacing ( 3 x 3 f e e t ) . Western hemlock i s a year younger i n t h i s study plot and more shade-tolerant than Douglas f i r , but they are of a different vegetative community. At the twelfth year (eleventh for the 68 western hemlock), no ground vegetation can be found under the Douglas f i r plantation; whereas, under the western hemlock, there i s a profuse growth of competitive vegetation, some of which (red alder, black cottonwood etc.) even overtopped the hemlock. The exposed growth conditions created at the estab-lishment of the plantation may be unfavourable for the optimum growth of western hemlock. The weights of forest f l o o r obtained i n the University of B r i t i s h Columbia Research Forest are well below the figures given by other workers i n t h i s f i e l d . The condition of the area at plantation establishment and i t s previous history should be noted, variations i n remaining debris from the preceding stand may contribute s i g n i f i c a n t l y to differences observed. The area i n which these experimental plots were established was bull-dozed and the slash burnt i n p i l e s . I t i s the net accumulation of forest f l o o r of twelve years of establishment that i s being considered i n t h i s thesis. The accumulation of fore s t floor follows clo s e l y the pattern of the l i t t e r f a l l , that i s : 3 x 3 -6 x 6 - 9 x 9 and 12 x 12 - 15 x 15 feet. The rate of decomposition, judging from the r a t i o of l i t t e r f a l l to forest f l o o r shows a d i s t i n c t relationship with spacing. The denser the spacing, the higher i s the r a t i o and vice versa. This would mean faster c i r c u l a t i o n of nutrient elements i n the stand with f u l l canopy than i n wider spacings. The s o i l parent material i s of g l a c i a l outwash, With the exception of Plantation F (15 x 15 f e e t ) , the s o i l s of a l l plots are grouped under the same sub-soil group: orthic humo-ferric podzol. But the texture d i f f e r s . This would affect the water-holding capacity and, ultimately, growth. I t should be noted that i n the comparison of growth data, consideration should be given to the s o i l , before v a l i d conclusions can be made. 69 Since so l i t t l e work has been done on the determination of nutrient elements i n the s o i l s of the P a c i f i c Northwest, no v a l i d or s i g n i f i c a n t com-parison can be made. The nitrogen content of the top layer of the mineral s o i l i n the Douglas f i r plots has been found to be about the same as that of Site I Douglas f i r s o i l (0-5556) of Tarrant's study (1949). Only two plantations (12 x 12 feet Douglas f i r and 3 x 3 feet western hemlock) have lower values than t h i s . The Ap layer i n western hemlock ( 3 x 3 feet) p l o t has the least nitrogen content (0.242%) and since t h i s plot i s i n the approximate centre of the study area, i t i s suggested that the effect of vegetation on the s o i l may have caused the r e -s u l t . More detailed study of the effect of western hemlock on s o i l should be carr i e d out. The phosphorus content i n the s o i l i s low, more concrete data should be obtained to provide sound bases for i t s supplement. I t i s found that the nutrient cycle d i f f e r s s i g n i f i c a n t l y i n the d i f f e r e n t plots, due perhaps to the associated broad-leaved vegetation present i n the wider spaced plots. E f f i c i e n t use might be made of t h i s v a r i a t i o n once i t i s f u l l y understood, to activate and supply some of the mineral elements t i e d up i n the s o i l . I t has been found that clo s e l y spaced Douglas f i r plantations help to con-t r o l the problem of brush competition, because the dense tree canopy w i l l shade out or prevent establishment of competitive vegetation. Due to competitive shading, the lower branches, up to f i v e feet at l e a s t , of the dense spacings ( 3 x 3 and 6 x 6 feet) are dead or dying. Thus i n time, the plantation trees may develop r e l a t i v e l y clear boles. However, for the wider spacing, the l i v e branches are close to the ground and the taper i s great. As time goes by, i t w i l l be advisable f o r the forest manager to apply s i l v i c u l t u r a l techniques to mould the environment and produce whatever kind of products are 70 wanted. Because the v a r i a t i o n of the l i t t e r f a l l of the twelve year old plantations i s great, the number of l i t t e r traps needed w i l l be greater i n order to a t t a i n a higher precision and confidence l e v e l . With a 2,090 cm (324 square inches) square trap on a 0.202 ha (0.5 acre) p l o t , one would expect to have at le a s t 30 traps to arrive at a 95$ confidence l e v e l and a precision of 10 gm. But i n the cedar hemlock stand where the canopy i s closed, 3 0 of the above-mentioned traps would be s u f f i c i e n t . 71 BIBLIOGRAPHY 1. Aiba, Y.j A. Kawanaj K. Sasaki, 1968. The Study of Site and Productivity of Pinus densiflora 79th. Nichirin Ringaku; Taikai Koenshyu: 89-90 (In Japanese). 2. Alway, F. J. and R. Zon, 1930. 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Growth after Precommercial Thinning i n Two Stands of Douglas F i r . United States Forest Service P a c i f i c Northwest Forest and Range Experiment Station Research Note #117, 6 pp. 120. Stephens, F. R. I963. Relation of Douglas F i r Productivity to Some Zonal S o i l s i n the Northwestern Cascades of Oregon. Forest S o i l Relation-ship i n North America, Oregon State University University, Press p. 254-268. 121. S t i e l l , W. M. 1964. Twenty-year Growth of Red Pine Planted at Three Spacings. Canadian Department of Forestry Publication no. 1045, ppl.24« 122. S t i e l l , W. M. 1966. Red Pine Crown Development i n Relation to Spacing. Canadian Department of Forestry Publications #1145, pp.--44. 123. S t i e l l , W.M. and A. B. Berry 1967. White Spruce Plantation Growth and Yie l d at the Petawawa Forest Experimental Station. Canadian Department of Forestry Departmental Publication #1200, 15 pp. 124. Strand, R. F. 1964. S o i l and Growth Studies i n Douglas F i r Stands Near Mola l l a , Oregon. Ph. D. Thesis Oregon State University, C o r v a l l i s , Oregon, 193 pp. 125. Tadaki, Y. 1963a. The Pre-estimating of Stem Yield based on the Competition-Density E f f e c t s . B u l l e t i n of Government Forest Experiment Station 154: 1-20. 126. Tadaki, Y. 1963b. Studies on Productive Structure of Forests IV: Some Studies on Leaf-amount of Stands and Individual Trees. J . Jap. For. Soc. 45, 249-256. (Jap. with English Summary). 127. Tadaki, Y. 1964. E f f e c t of Thinning on Stem, Volume Yi e l d Studied with Competition-Density E f f e c t . (Japanese with an English Summary) B u l l e t i n of Government Forest Experiment Station 166: 1-22. 0 80 128. Tadaki, Y. & Y. Kawasaki 1966. Studies on the Production Structure of Forest, IX; Primary Production of a Young Cryptomeria .iaponica Plantation with Excessively High Stand Density. Journal of Japanese Forestry Society 4 8 : 55-61. 129. Tadaki, Y. 1966. Some Discussions on the Leaf Biomas of Forest Stands and Trees. B u l l e t i n Government For. Exp. Sta. 184, 135-161. 130. Tadaki, Y. et a l 1966. Studies on the Productivity Structure of Forest X: Primary Production of an Unthinned Forty-five Year Old Stand of Ghamaecyparis obtuse. Journal of Japanese Forestry Society 48: 387 pp. 131. Tarrant, R. F. 1949. Douglas F i r Site Quality and S o i l F e r t i l i t y . Journal of Forestry 47: 716-720. 132. Tarrant, R. F.; L. A. Isaac; R. F. Chandler 1951. Observation on the L i t t e r f a l l and Foliage Nutrient Content of Some P a c i f i c Northwest Tree Species. Journal of Forestry 49: 914-915• 133. Tarrant, R. F. and R. E. M i l l e r 1963. Accumulation of Organic Matter and S o i l Nitrogen Beneath a Plantation of Red Alder and Douglas F i r . Proceedings S o i l Science Society of America 27(2): 231-234« 134. Thomas, W. A. 1967. Decomposition of Loblolly Pine Needles Mixed with Dogwood Leaves. Abstract i n B u l l . Ecol. Amer. 48 (3) 125. 135. Tsutsumi, T. 1963- L i t t e r Decomposition and Variation i n In-organic Nutrient Content. 74th N i c h i r i n Ringaku Taikai Joenshyu ( i n Japanese) 136. Tsutsumi, T.j T. Kawaharaj T. Shidei 1968. The Ci r c u l a t i o n of Nutrients i n Forest Ecosystem (L). On the Amount of Nutrients Contained i n the Above-Ground Parts of a Single Tree and of a Stand. Journal of Japanese Forest Society 50 (3): 66-74. 137. Voigt, G. K. 1965. Nitrogen Recovery from Decomposing Trees Leaf Tissue and Forest Humus. Proceedings of the S o i l Science Society of America 29: 756-759. 138. Waksman, S. A. 1958. Humus. The Williams & Wilkins Co., Baltimore 526 pp. 139. Walker, R. B.j S. P. Gesselj P. G. Haddock 1955. Greenhouse Studies i n Mineral Requirements of Conifers Western Red Cedar Forest Science l : 51-60. 140. Walters, J. 1954, 1966. Annual Reports. University of B r i t i s h Columbia Faculty of Forestry. 141. Ware, L. M. and R. Stahelin 1948. Growth of Southern Pine Plantations at Various Spacings. Journal of Forestry 46: 267-274. 81 142. Warrack, G. G. 1959. Forecast of Y i e l d i n Relation to Thinning Regimes i n Douglas F i r . Forest Service Tech. Publ. T 51. B. C. Forest Service, Dept. of Lands and Forest, V i c t o r i a , B. G. 56 pages. 143. Warren, P. G. and P. R. F f o l l i o t t 1969. Water Holding Capacity of Ponderosa Pine Forest Floor Layers. Journal of S o i l and Water Conservation Volume 24 : 22-23. 144. Webber, B. 1964. Certain S o i l Elements as Related to Tree Species. S o i l and Site B.S.F. Thesis, University of B r i t i s h Columbia, 95 pp. 145. Weetman, G. F. 1962. Nitrogen Relationship i n a Black Spruce Stand Subject to Various F e r t i l i z e r and S o i l Treatments. Pulp and Paper Research I n s t i t u t e of Canada, Woodland Research Index 129, 112 pp. 146. Weetman, G. F. 1965. The Decomposition of Confined Black Spruce Needles on Forest Floor. Pulp and Paper Research In s t i t u t e of Canada, Woodland Research Index 165, 18 pp. 147. Wilde, S. A. 1946. Forest S o i l and Forest Growth. Chronica Botanica Company, 241 pp. 148. W i l l , G. M. 1957. Variations i n the Mineral Content of Radiata Pine Needles with Age and Position i n the Tree Crown. New Zealand Journal of Science and Technology B. General Research Section 38(7): 699-706. 149. W i l l , G. M. 1959. Nutrient Return i n L i t t e r and R a i n f a l l under some Exotic Conifer Stands i n New Zealand, New Zealand Journal of Ag r i c u l t u r a l Research 2: 719-734. 150. W i l l , G. M. 1964. Dry Matter Production and Nutrient Uptake by Pinus radiata i n New Zealand. Commonwealth Forest Review 43J 57-70. 151. W i l l , G. M. 1967. Decomposition of Pinus radiata L i t t e r on the Forest Floor. Part I : Changes i n Dry Matter and Nutrients Content, New Zealand Journal S c i . 10 (4) 1030-44-152. Williams, C.B. J r . and C. T. Dyrness 1967. Some Characteristics of Forest Floors and Soi l s under True Fir-Hemlock Stands i n the Cascade Range, United States Department of Agriculture, United States Forest Service, P a c i f i c Northwest 37: 1-19. 153. Witkamp, M. 1966. Decomposition of Leaf L i t t e r i n Relation to Environment, Microflora and Microbial Respiration. Ecology 47: 194-201. 154. Witkamp, M.-& Van der Deift 1961. Breakdown of Forest L i t t e r i n Relation to Environmental Factors. Plant and S o i l 15: 295-311. 155. W i t t i c h , W. 1952. The Present State of our Knowledge about Humus i n the Forest. Schr Reihe F o r s t l Fak. University Gottingen no. 4, PP- 106. 82 156. Worthington, N. P. and G. R. Staeber 1961. Commercial Thinning of Douglas F i r i n the P a c i f i c Northwest. USDA Forest Service Tech. B u l l . No. 1230, 124 PP. 157. Youngberg, C. T. 1966. Forest Floors i n Douglas F i r Forests. Proc. S o i l . S c i . Soc. Amer. 30: 406-409. 83 APPEMDIX I: ANNUAL LITTERFALL OF DOUGLAS FIR IN OVEN-DRIED WEIGHT Age (Years) Kg/ha/yr 30 32 38 52 38 100 350 40 33 34 37 unthinned 37 med - thinned 37 light, thinned 37 heavy thinned 45 35 12 12 12 12 12 13 13 13 13 13 (3' (6' (9' (12' (15' (3-(6' (9« (12' (15" ) : V) : 6') : 9') x 12' x 15') x 3') x 6') x 9') 12') 15") 2,107 1,301 2,578 2,467 2,440 921 1,984 2,903 3,318 2,488 2,213 1,867 1,743 1,415 1,477 1,688 4,106 3,066 1,602 2,477 1,001 5,133 5,302 2,834 2,081 1,755 Reference Heilman, 1961 Heilman, 1961 Heilman, 1961 Heilman, 1961 Heilman, 1961 Tarrant et al 1951 Tarrant et al 1951 Will, 1959 Will, 1959 Will, 1959 Reukema, 1964 Reukema, 1964 Reukema, 1964 Reukema, 1964 Dimock, 1958 Rahmann, 1964 (Riekerk, 1967) Wooh, 1969 Woon, 1969 Woon, 1969 Woon, 1969 Woon, 1969 Woon, 1969 Woon, 1969 Woon, 1969 Woon, 1969 Woon, 1969 84 APPENDIX I I : FOREST FLOOR ACCUMULATION OF DOUGLAS FIR IN OVEN-DRIED WEIGHT Age (Years) Kg/ha Reference 30 61,000 Heijjnan, 1961 32 35,000 Heilman, 1961 38 63,000 Heilman, 1961 38 47,000 Heilman, 1961 52 117,000 Heilman, 1961 12 23,000 Paddock, 1962 (Riekerk 1967) 28 14,000 Paddock, 1962 (Riekerk 1967) 30 24,000 Paddock, 1962 (Riekerk 1967) 39 12,000 Paddock, 1962 (Riekerk 1967) 75 24,000 Paddock, 1962 (Riekerk 1967) 32 24,000 Cole 1963. 38 73,000 Cole, 1963 43 46,000 Cole, 1963 34 22,000 B a l c i , 1954 Old 85,000 B a l c i , 1954 Old 88,000 B a l c i , 1954 Old . 111,000 B a l c i , 1954 Old 53,000 B a l c i , 1954 35 22,000 Rhamann 1964 (Riekerk 1967) 30 14,000 Strand, 1964 45 20,000 Strand, 1964 30 28,000 Tarrant and M i l l e r , 1963 about 100 24,000 Youngberg, 1966 -(Different Plant About 100 29,000 Youngberg, 1966 communities) About 100 24,000 Youngberg, 1966 11 " About 100 23,000 Youngberg, 1966 " " About 100 29,000 Youngberg, 1966 " " About 100 34,000 Youngberg, 1966 " " About 100 31,000 Youngberg, 1966 " " About 100 86,000 Youngberg, 1966 " " About 100 67,000 Youngberg, 1966 11 " 21 , 22,000 Ovington, 1954 20 11,000 Ovington, 1954 46 8,000 Ovington, 1954 150 29,000 Gessel and B a l c i , 1965 100 14,000 Gessel and B a l c i , 1965 12 16,000 Woon, 1969 - 3' x 3' spacing 12 12,000 Woon, 1969 - 6' x 6" spacing 12 9,000 Woon, 1969 - 9' x 9' spacing 12 13,000 Woon, 1969 - 12' x 12' spacing 12 10,000 Woon, 1969 - 15' x 15' spacing 85 APPENDIX III? SOIL PROFILE CHARACTERISTICS OF THE DIFFERENT PLOTS HORIZON DEPTH COLOUR BOUNDARY TEXTURE STRUCTURE DISTRIBUTION B (3' X 31) DF Ap 0-24 10 yx.3/4 Diffused Sandy Loam Granular Abundant Abe 24-34 10 yr.5/1 Gradual Sandy Loam Granular Abundant Bfh 34-47 10 yr.4/4 Gradual Sandy Loam Granular Many Bf 47-62 5 yr.4/8 Gradual Loamy Sand Granular Many BIIC 62-74 10 yr.5/8 Gradual Loamy Sand Single Grain Occasional IIC 74+ 10 yr.6/6 Gradual Graval Sand Single Grain Occasional-none E (6' X 6') DF Ap 0-12 5 yr.3/2 Gradual S i l t y Loam Granular Abundant Ae 12-19 10 yr.5/1 Diffused S i l t Loam Granular Abundant Bf 19-47 7.5 yr .5/6 Diffused S i l t Loam Granular Abundant BC 47-52 10 yr.4/3 Diffused S i l t Loam Single grain Abundant C 52+ 10 yr.6/3 Diffused S i l t Loam Single grain Abundant A (9« X 9') DF Ap 0-10 2.5 yr.2/2 Gradual S i l t y Loam Granular Abundant Ae 10-13 10 yr.4/2 Gradual S i l t y Loam Granular Abundant Bfh 13-18 25 yr.2/4 Diffused Sandy Loam Granular Abundant B f l 18-41 5 yr.3/4 Diffused Sandy Loam Granular Many B f 2 41-61 10 yr.4/4 Diffused Sandy Loam Single Grain Scarce BIIC 61-71 10 yr.5/8 Gradual Sandy Loam Single Grain Scarce IIC 71+ C (12 1 • x 12') DF Ap 0-17 5 yr.3/2 Gradual Sandy Loam Granular Abundant Ae 17-20 10 yr.5/1 Gradual Sandy Loam Granular Abundant Bfh 20-30 10 yr.3/4 Diffused Sandy Loam Granular Many Bf 30-49 5 yr.3/4 Diffused Sandy Loam Granular Scarce BIIC 49-75 10 yr.4/4 Diffused Sandy Loam Granular Scarce IIC 75+ F (15 1 ; x 15«) DF yr.3/4 Ap 0-9 10 Abrupt Loamy Sand Granular Abundant Bf 9-13 10 yr.5/8 Gradual Gravelly loamy sand Granular Abundant Bfg 13-56 10 yr.5/8 Abrupt Gravelly Sand Single Grain Many Bfc 56-72 5 yr.4/6 Abrupt Gravelly Sand Single Grain Occasional C 72+ 25 yr.6/2 Abrupt Sand Single Grain None D (3' X 3') WH yr.5/8 Ap 0-5 10 Gradual Loamy Sand Granular Abundant Ae 5-6 10 yr.5/2 Gradual Loamy Sand Granular Abundant B f l 6-13 10 yr.5/6 Diffused Loamy Sand Granular Abundant B f 2 13-43 7.5 yr.5/6 Diffused Loamy Sand Granular Many BC 43-56 10 yr.6/8 Diffused Loamy Sand Granular Occasional C 56+ 7.5 yr.5/5 Diffused Loamy Sand Single Grain None CH (Thinned) yr.3/4 B f l 0-13 5 Abrupt Sandy Loam Weak Angular Block Abundant Bf2 13-17 5 yr.3/3 Diffused Sandy Loam Weak Angular Block-Occasion BIIC 17-24 5 yr.3/4 Diffused Sandy Sand Single Grain Occasional IIC 24+ 7.5 yr.5/4 Diffused • Sandy Sand Massive None Douglas F i r - WH = Western Hemlock - CH = Cedar-Hemlock 86 APPENDIX IV: MINERAL PERCENT CONTENTS OF DRY WEIGHT LITTER OF SEVERAL CONIFER SPECIES IN SEEGIES AGE N_ P_ K_ C_a_ Reference Douglas Fir- 40 1.07 0.11 0.29 1.05 Will, 1959 Douglas Fir 34 0.83 0.13 0.21 1.10 Will, 1959 Douglas Fir 30 1.51 0.16 0.04 1.48 Webber, 1964 Douglas Fir 30 1.46 0.22 0.09 1.43 Webber, 1964 Douglas Fir 30 1.56 0.21 0.05 1.80 Webber, 1964 W. Hemlock 30 1.34 0.15 0.06 1.06 Webber, 1964 W. Hemlock 30 1.11 0.20 0.07 1.44 Webber, 1964 ¥. Hemlock 30 1.39 0.20 0.09 1.75 Webber, 1964 W.R. Cedar 30 1.14 0.16 0.06 2.19 Webber, 1964 W.R. Cedar 30 1.52 0.19 0.07 2.11 Webber, 1964 W.R. Cedar 30 1.38 0.23 0.06 2.20 Webber, 1964 APPENDIX V: MINERAL CONTENTS OF FOREST FLOOR OF DOUGLAS FIR STANDS Age m Cag Site-Index Df Mor L Old G. 1.102 0.105 0.102 Gessel & Balci 1965 F Old G. 1.348 0.113 0.114 — Gessel & Balci 1965 H Old G. 1.215 0.093 0.089 - Gessel & Balci 1965 Duff Mull L Old G. 1.273 0.112 0.109 - Gessel & Balci 1965 F Old G. 1.463 0.122 0.116 - Gessel & Balci 1965 H Old G. 1.302 0.114 0.121 — Gessel & Balci 1965 DF — 0.633 0.07 0.11 0.43 110(1957)For S o i l of DF Region — 1.080 0.11 0.125 0.46 135(l957)For S o i l of DF Region - 0.685 0.08 0.10 0.55 95(l957)For S o i l of DF Region — 1.045 0.10 0.12 0.32 130(l957)For S o i l of DF Region Old Growth 0.92 0.11 0.18 0.86 - (l957)For S o i l of DF Region 65 0.69 - - — - (1957)For Soil of DF Region Old G. 0.84 - - - - (1957)For S o i l of DF Region Old G. 0.90 - - - - (1957)For S o i l of DF Region 120 1.06 0.10 0.12 0.32 - (l957)For S o i l of DF Region DF 100 0.71 0.089 0.130 1.050 Youngberg, 1966 100 0.88 0.138 0.232 0.875 Youngberg, 1966 100 0.74 0.137 0.132 0.875 Youngberg, 1966 100 0.87 0.211 0.275 0.875 Youngberg, 1966 100 1.02 0.141 0.117 0.838 - Youngberg, 1966 100 1.07 0.145 0.183 0.900 Youngberg, 1966 100 0.88 0.147 0.118 0.625 Youngberg, 1966 100 0.52 0.139 0.198 0.412 Youngberg, 1966 100 0.75 0.118 0.115 0.325 - Youngberg, 1966 88 APPENDIX VI: FOLIAGE MINERAL CONTENTS OF SEVERAL CONIFER SPECIES (in % dry weight) SPECIES Affi I g Ca| REFERENCE DF 13 1.28 0.21 0.69 0 . 2 5 Beaton et al 1965 13 1.25 0 . 2 6 0.55 O.4O Beaton et al 1965 13 1.20 0.29 0.49 0.50 Beaton et al 1965 13 0.98 0.22 0.69 0.31 Beaton et al 1965 13 1.00 0.24 0.50 0 . 5 6 Beaton et al 1965 13 0.99 O.24 O.48 0.82 Beaton et al 1965 27 1.22 0.15 O.42 0.25 Beaton et al 1965 27 1.18 0.18 0.39 0 . 3 6 Beaton et al 1965 27 1.10 0.20 0.39 0.42 Beaton et al 1965 27 1.22 0.17 0.69 0 . 3 0 Beaton et al 1965 27 1.37 0.16 0.69 0.25 Beaton et al 1965 27 1.35 0 . 1 6 0.53 O.24 Beaton et al 1965 30 1.67 0.16 0.66 1.10 Webber, 1964 30 1.28 0 . 2 5 0.45 1.08 Webber, 1964 3 0 1.28 0 . 3 0 0.65 2.35 Webber, 1964 350 o.77 0.10 0.19 0.60 Tarrant et al 1951 100 0.85 0.08 0.20 0.97 Tarrant et al 1951 100 1.27 0.09 0.38 0.74 Ovington, 1956 WH 60 1.17 0.16 0.43 0.20 Beaton et al 1965 60 1.21 0.18 O.4O 0.24 Beaton et al 1965 60 1.22 0.18 0.38 0.30 Beaton et al 1965 60 0.45 0.17 0.35 0.60 Daubenraire, 1953 30 0.99 0.17 0.30 2.33 Webber, 1964 30 1.16 0.20 0.47 1.60 Webber, 1964 30 1.35 0.23 0.47 1.06 Webber, 1964 0.85 0.15 0.15 0.93 Tarrant et al 1951 1.48 0.12 0.47 0.38 Ovington, 1956 W.R.C. 50 0.73 0.13 0.52 1.16 Beaton et al 1965 30 1.16 0.20 0.35 2.53 Webber, 1964 30 0.94 0.20 0.33 1.92 Webber, 1964 30 0.94 0.25 0.45 1.90 Webber, 1964 0.62 0.01 0.36 2.23 Tarrant et al 1951 DF = Douglas Fir WH = Western Hemlock WRC = Western Red Cedar 89 APPENDIX VII: AVERAGE OVEN-DEI WEIGHT, STANDARD DEVIATION AND CO-EFFICIENT OF VARIATION OF LITTERFALL AT DIFFERENT PERIODS gm/Screen Period Description No. of Oven-Dry S.D/ C.V.^ Kg/ha Screens Weight % May 12/67 B(DF 3' x 3') 10 85.84. 23.52 27 4,106.46 to E(DF 6' x 6') 8 64.IO 24.06 38 3,066.45 May 30/68 A(DF 9' x 9') 10 33.49 21.17 63 1,602.11 C(DF 12,xl2') 7 51.77 46.37 90 2,476.67 F(DF 15'xl5*) 10 20.93 10.30 49 1,001.26 D(WH 3' x 3') 10 24.40 14.13 58 1,167.26 CH 33 69.28 25.45 37 3,3H.26 May 30/68 B 10 107.30 20.77 19 5,133.17 to E 10 110.84 29.78 27 5,302.43 May 30/69 A 10 59.26 43.17 73 2,834-43 C 10 43.51 31.22 72 2,081.46 F 10 36.68 16.52 45 1,754-53 D 10 ' 40.01 25.42 64 1,914.02 CH 33 60.20 18.02 30 2,879.88 May 30/68 B 10 6.94 3.50 50 332.00 to E 10 16.24 5-35 33 776.90 Aug.20/68 A 9 6.90 7.22 105 330.09 C 9 4.99 2.80 56 238.66 F 10 8.35 4-28 51 399.45 D 10 6.43 4.51 70 307.60 CH 33 4.11 3.56 87 196.43 Aug.20/68 B 10 7.56 2.76 37' 361.42 to E 10 6.13 2.68 44 293.25 Sep.29/68 A 10 5.03 5.92 118 240.53 C 9 3.95 3-46 88 188.75 F 10 3.37 2.48 74 161.31 D 10 5.64 3.40 60 269.91 CH 33 3.39 1.88 55 162.15 Sep.29/68 B 10 6.41 1.66 26 306.74 to E 10 7.12 2.23 31 340.37 Nov. 9/68 A .10 5.09 2.94 58 243.50 C 10 5.95 5.03 85 284.69 F 10 15.41 10.66 69 737.38 D 10 12.53 11.20 89 599.27 CH 33 16.38 7.83 48 783.65 Nov. 9/68 B 10 86.40 18.27 21 4,133.01 to E 10 82.78 23.48 28 3,959.88 May 30/69 A 10 42.93 31.00 72 2,053.76 C 9 32.80 24-55 75 1,568.99 F 10 9.54 5.26 55 456.38 D 10 24.91 25.57 103 1,191.66 CH 33 36.33 11.28 31 1,738.15 1. Size of Screen=324 sq.in. (2,090 cm ) 2. Standard Deviation. 3. Co-efficient of Variation. DF = Douglas Fir WH = Western Hemlock CH = Cedar-Hemlock 90 APPENDIX V I I I : SUMMARY OF STATISTICAL ANALYSES Description df F Ratio Duncan's New Multiple Test (5%) L i t t e r f a l l May 12/67-May 30/68 4 3.33 ** B - E - C - A - F 40 L i t t e r f a l l May 30/68-Aug.20/68 4- 7.15 ** E - F - B - A - C 43 L i t t e r f a l l Aug.20/68-Sep.29/68 4 1.84 n * S ' N o n - s i g n i f i c a n t 44 L i t t e r f a l l Sep.29/68-Nov. 9/68 4 4.92 ** F - E - B - C - A 43 L i t t e r f a l l Nov. 9/68-May 30/69 4 19.79 ** B - E - A - C - F 44 L i t t e r f a l l May 30/68-May 30/69 4 12.60 ** E - B - A - C - F 45 L i t t e r f a l l Year 1 11.69 1967 - 1969 Treat. 4 19.46 B - E - C - A - F Y x Tr 4 1.84 n.s • Error 85 Forest Floor - L Layer 4 18.64 C - E. - A - F - B 87 Forest Floor-L + FH Layer 4 10.35 B - C - E - F - A 87 Seasonal L i t t e r -• Phosphorus 4 7.11 C - F _ E - A - B 42 Seasonal L i t t e r -- Potassium 4 5-06 *-* C - F - A - B - E 42 Seasonal L i t t e r - Calcium 4 3.30 * F - E - C - A - B 42 Phosphorus Species 1 16.91 *' 17 Potassium Species 1 3.60 n.s. at 5% 17 Calcium Species 1 43.58 17 1. Df = degree of fredom. ** = S i g n i f i c a n t at the 0.01 Pr o b a b i l i t y Level. B = 3 x 3 feet; E = 6 x 6 feet; A = 9 x 9 feet; C - 12 x 12 feet; F - 15 x 15 feet 2. Any two treat-lent means underscored by the same l i n e are not s i g n i f i c a n t l y d i f f e r e n t . * = S i g n i f i c a n t at 0.05 p r o b a b i l i t y l e v e l . 91 APPENDIX IX: AVERAGE GROWTH DATA FOR THE DOUGLAS FIR PLANTATIONS AS OF 1968 (UNIVERSITY OF BRITISH COLUMBIA RESEARCH FOREST DATA)  Height (Feet) DBH (Inches) % Crown Length Crown Width (Feet) 3' x 3' 6'x 6" 9' x 9' 12' x 12' 15' x 15' 3' x 3 DF DF DF DF DF WH 21.4- 23.2 22.0 21.8 21.5 12.0 2.3 3.6 3.7 4.2 3.3 1.5 65.: 79 90 97 35 93 6.7 9.1 10.7 12.4 11.8 5.8 92 APPENDIX X; LIST OF ASSOCIATED VEGETATION (MOSTLY GROUND OR UNDERSTORY) ON THE DIFFERENT PLOTS , 3,x3« 6'x6« 9'x9' 12'xl2' 15 W 3'x; Species DF DF DF DF DF WH Polystichum muniturn (Kaulf) Underw. 1 1 1 1 1 Pteridium aquilinum pubescens (L) Kuhn 3 2 2 2 Betula spp. 3 2 2 2 Gaulteria shallow Pursh 2 2 3 Cornus canadiansis L. 2 1 Populus trichocarpa T. & G. 1 2 1 3 Salix spp. 2 2 2 1 Alnus rubra Bong.' 1 2 3 3 Prunus emarginata Dongl. 2 2 2 3 Ii'nnaea borealis L. 2 1 1 2 Rubus parviflorus Nutt. 1 1 3 3 Rubus idaeus L. 3 3 3 3 Vaccinium spp. 2 1 3 1 Anaphalis margaritacea Benth. 3 1 1 Hypochaeris radicata L. 1 2 1 .1 Epilobium angustifolium L. 2 3 2 3 Acer circinatum Pursh 1 1 1 1 Polytrichum juniperinum Hedw. 1 2 2 1 2 Mnium insigne Mitt. 2 2 1 2 1 - Scanty 2 - Many 3 - Abundant 93 APPENDIX XI DIAGRAM OF THE LITTER TRAP VERTICAL VIEW SIDE VIEW SCREEN-94 APPENDIX XII: TRAP LOCATION IN DIFFERENT PLOTS 95 THINNED CEDAR-HEMLOCK (1X2 CHAINS) A 9'X9* DF (2X25 CHAINS) B 3'X3' DF (2X25 CHAINS) IZXI2' DF (2X2-5 CHAINS) E 6*X6' DF (2X2-5 CHAINS) °10 10 9o °2 2 ° °7 o . 6 I5'X15' DF (2X2-5 CHAINS) D 3'X3' WH (2X25 CHAINS) 

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