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Till-derived podzols of Vancouver Island Lewis, Terence 1976

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THE TILL - DERIVED PODZOLS OF VANCOUVER ISLAND by TERENCE LEWIS B . S . F . , Univers i ty of B r i t i s h Columbia, 1968 A THESIS SUBMITTED IN PARTIAL FULFILMENT OF THE REQUIREMENTS FOR THE DEGREE OF DOCTOR OF PHILOSOPHY in the Department of So i l Science We accept th is thesis as conforming to the required standard THE UNIVERSITY OF BRITISH COLUMBIA September 1976. In p r e s e n t i n g t h i s t h e s i s in p a r t i a l f u l f i l m e n t o f the r e q u i r e m e n t s for an advanced degree a t the U n i v e r s i t y o f B r i t i s h C o l u m b i a , I agree tha t the L i b r a r y s h a l l make i t f r e e l y a v a i l a b l e f o r r e f e r e n c e and s t u d y . I f u r t h e r a g r e e t h a t p e r m i s s i o n f o r e x t e n s i v e c o p y i n g o f t h i s t h e s i s f o r s c h o l a r l y p u r p o s e s may be g r a n t e d by the Head of my Department or by h i s r e p r e s e n t a t i v e s . It i s u n d e r s t o o d that c o p y i n g or p u b l i c a t i o n o f t h i s t h e s i s f o r f i n a n c i a l g a i n s h a l l not be a l l o w e d w i t h o u t my w r i t t e n p e r m i s s i o n . Department o f JUCi J< The U n i v e r s i t y o f B r i t i s h Co lumbia 2075 Wesbrook Place Vancouver, Canada V6T 1W5 Date Q j - c W S i r i k ABSTRACT Moderately wel l drained, non - l i t h i c podzol s o i l s developed in g lac ia l t i l l s of f i ve l i t h o l o g i e s , (andes i t ic , b a s a l t i c , i n t rus i ve , limestone and sch is tose) , were characterized throughout the dry and wet subzones of the Coastal Western Hemlock biogeocl imatic zone of Vancouver Is land. The s o i l s are benchmark s o i l s that occupy large areas, which could be used to assess the ef fects of loca l s i t e di f ferences and various land management p rac t ises . Analysis of the range of Vancouver Island podzols i s followed by the synthesis of a Vancouver Island model of podzols, which i s t yp i f i ed by large accumulations of sesquioxides throughout a th ick B hor izon, and yet the frequent absence of any Ae horizon. Accumulations of organic matter, both as mor surface horizons and wi th in the B hor izon; as well as ac id i t y and low base saturat ion are a lso cha rac te r i s t i c , as in the long-standing c l ass i ca l Ae/B model of podzols. However, the c l a s s i c a l model requires the presence of an Ae horizon and general ly has a much th inner , less sesquioxidic B horizon than the Vancouver Island model of podzols. I t i s suggested that the present concept of podzol genesis, which focuses on the t ranslocat ion of sesquioxides and organic matter from Ae to B, be broadened to encompass the two rather divergent models of podzols. The proposed concept envisages podzol formation as 11 111 resu l t ing from three groups of processes - the i n - s i t u weathering of parent materials and solum, which involves losses of the bases and s i l i c a and residual enrichment with iron and aluminum; horizonation processes, which red is t r ibu te organic matter and sesquioxides wi th in the solum; and ant i -hor izonat ion processes, including physical turbat ion and the b io log ica l cyc l ing of elements, which r e s t r i c t the development of the master B and sub-horizonation within the master B. In the c l a s s i c a l podzol, horizonation processes dominate while weathering acts to supply some of the const i tuents that are t ranslocated. In the Vancouver Island model, i n - s i t u weathering dominates and the t rans locat ion of sesquioxides i s res t r i c ted by re l a t i ve l y rapid i n s o l u b i l i z a t i o n of organo-metal l ic complexes by the abundance of weathered i ron and aluminum. A dupl icate composite sampling method wi th in 0.04 hectare plots was designed in order to generate precise estimates of both the mean and v a r i a b i l i t y of nutr ient stocks in the s o i l s . Assessment of both physical and chemical propert ies in the plots allowed the expression of nutr ient status in kilograms per hectare, an expression bel ieved more useful for management purposes. Two-way analys is of variance with in teract ion involv ing the geologic and c l ima t i c so i l - forming factors and one-way analys is of variance to assess the geologic factor wi th in c l imat ic zones were undertaken. The in tegr i t y of the subdiv is ion of the Vancouver Island podzols on the basis of t i l l l i tho logy and biogeocl imatic subzone was confirmed since the analyses of variance and Duncan's mul t ip le range tests ind icate that no natural grouping of the s o i l s i s poss ib le . However, grouping of the s o i l s , on the basis of a few proper t ies , for special purposes, such as f e r t i l i z a t i o n , i s f eas ib l e . The double composite sampling scheme allowed quant i ta t ive estimation of s o i l v a r i a b i l i t y . The optimum number of samples required to a t ta in spec i f ied al lowable errors i s presented. To a t ta in an al lowable error of ten percent requires between three and 62 samples, depending on the so i l property of concern. When 16 samples are taken per p lo t , as in t h i s study, the error is wi th in ten percent for pH in CaCl^ . to ta l carbon, to ta l ni t rogen, to ta l su l fu r and ava i lab le phosphorus; and wi th in 20 percent for the exchangeable cat ions and ava i lab le copper, z i n c , iron and manganese. Comparison of values determined from one modal p i t with values from composite sampling in rep l icated p lots ind icates that modal p i t means commonly f a l l outside of the interval defined by the p lo ts mean +1 standard dev ia t ion. This casts considerable doubt on the adequacy of modal p i t sampling for the purposes of generating the estimates of nutr ient stocks required for management purposes. ACKNOWLEDGEMENTS The f inanc ia l support of the National Research Council of Canada is g ra te fu l l y acknowledged. The support and cooperation, during f i e l d work, of the B r i t i s h Columbia Forest Serv ice, B r i t i s h Columbia Forest Products, Canadian Forest Products, MacMillan Bloedel and Rayonier, Canada i s g ra te fu l l y acknowledged. I would l i k e to express thanks to Les Herr ing, Len Leskiw, and Mohammed A l i Z u l k i f l i for the i r assistance in the frequently arduous f i e l d work; to Shei la McMeekin for her un t i r i ng , d i l i gen t assistance in the s o i l s laboratory, and to Ann Har r i s , and Bernie Von Spindler for the i r advice in the laboratory. The advice of Dr. Maier and the use of the X-ray emission equipment of the Department of GeoTogy i s g ra te fu l l y acknowledged. Valuable assistance and advice was g ra te fu l l y received from John Wiens in s t a t i s t i c a l analysis and data compilation by computer. I a lso wish to express my deep appreciat ion to Joan Sawicki for both her encouragement and her edi t ing of the thes is . I thank my committee for the i r patience and guidance and my thes is adv isor , Dr. Les Lavkul ich, for his encouragement and advice. F i n a l l y I would l i k e to acknowledge the encouragement of many fr iends and associates who urged me on to the attainment of my object ive. v TABLE OF CONTENTS Page INTRODUCTION : 1 CHAPTER I. MORPHOLOGY AND GENESIS OF THE SOILS 3 Introduction 3 Mater ia ls and Methods 5 F ie ld Sampling. 5 Laboratory Methods 5 Results and Discussion 7 Var ia t ion wi thin the Vancouver Island Podzol S o i l s . 7 The Effects of Var ia t ion in Climate 7 The Ef fects of Var ia t ion in Geology. 24 The Vancouver Island Model 31 The LFH 31 The Ae Horizon 32 The B Horizon 33 The BC Horizon 41 The C Horizon 42 The " C l a s s i c a l " Podzol 42 Concepts of Podzol izat ion 45 Transport of Iron and Aluminum in Ionic Form 46 v i v i i CHAPTER Page Transport of Iron and Aluminum as Sols 48 Transport as Organo-metaTl i c Complexes 50 Prec ip i ta t ion of Sesquioxides in the B Horizon. . . 54 Enrichment of the B with Organic Matter 56 The C lass i ca l Podzol Versus the Vancouver Island Model 57 Possible Causes of the Divergent Models . 60 Overlying Ae Horizons 60 L i tho log ic Discont inu i t ies 62 In-s i tu Weathering 63 Proposed Genesis of the Vancouver Island Model 68 Summary and Conclusions 76 II . THE NUTRIENT STATUS OF THE SOILS 80 Introduction 80 Methods 81 Experimental Design 81 F ie ld Sampling Methods 81 Laboratory Methods 84 Data Analysis 85 Results and Discussion 88 The Signi f icance of Climate and Geology 88 In the LFH Horizon . 88 In the B Horizon 94 Summary and Conclusions 103 v i i i CHAPTER Page I I I . VARIABILITY OF THE SOILS 105 Introduction 105 Methods 106 F ie ld Sampling. . 106 Laboratory Methods 107 S t a t i s t i c a l Ana lys is . 108 Results and Discussion . . . 110 Summary and Conclusions 112 SUMMARY AND CONCLUSIONS 117 LITERATURE CITED 121 APPENDICES 1 - 1 Descript ion and analysis of the modal s o i l s and descr ip t ion of the associated vegetation 129 2 - 1 The nutr ient status of the s o i l s 149 3 - 1 Optimum number of samples required to meet spec i f ied allowable errors 154 LIST OF TABLES TABLE Page 1-1 THE EXPERIMENTAL DESIGN. 4 1-2 SELECTED CLIMATE STATIONS WITHIN THE STUDY AREA 8 1-3 AVAILABLE PHOSPHORUS (BRAY PI) IN THE UPPERMOST B (0-15 cm) 13 1-4 THE CATION EXCHANGE CAPACITY OF THE UPPERMOST B HORIZONS (0-15 cm) 15 1-5 THE BASE SATURATION OF THE UPPERMOST B HORIZONS (0-15 cm). . . 16 1-6 EXCHANGEABLE CATIONS (NH^OAc) IN THE UPPERMOST B HORIZONS (0-15 cm) . . 17 1-7 ELEMENT TO ALUMINUM RATIOS IN THE B AND C HORIZONS AND THE PERCENT CHANGE FROM C TO B 25 1-8 CHEMICAL PROPERTIES OF THE TWO Ae HORIZONS 29 1-9 THE SESQUIOXIDE CONTENT OF THE B AND C HORIZONS OF THE VANCOUVER ISLAND PODZOL 37 1-10 THE RELATIONSHIPS BETWEEN CATION EXCHANGE AND ORGANIC MATTER, CLAY AND SESQUIOXIDES 38 1-11 THE CATION EXCHANGE CAPACITY AND BASE SATURATION OF THE PARENT TILLS 42 1-12 VARIOUS PROFILE TYPES CALLED "PODZOLS" 44 1-13 VARIATION IN THE SOLUBILITY OF FERRIC IRON AND ALUMINUM WITH pH 47 1-14 THE CONCENTRATION OF COMPLEX-ED IRON IN 10- 4M PARA-HYDROXYBENZOIC ACID IN EQUILIBRIUM WITH FERRIC HYDROXIDE . . . 54 1-15 THE IRON, ALUMINUM AND SILICON CONTENT OF CLASSICAL PODZOLS . V 59 1-16 RATIOS OF VARIOUS ELEMENTS TO ALUMINUM AND THE CHANGE IN RATIO FROM THE TILL TO THE B HORIZON 66 ix X TABLE Page 1- 17 THE ANNUAL IONIC GEOCHEMICAL BALANCE OF JAMIESON CREEK WATERSHED, WATER YEAR 1970-71 68 2- 1 THE EXPERIMENTAL DESIGN. 81 2-2 THE RANGE OF NUTRIENT VALUES MEASURED 89 2-3 THE RESULTS OF TWO-WAY ANOVA WITH INTERACTION FOR AD, AW, BD, BW, GD AND GW. SOILS. 90 2-4 THE RESULTS OF ONE-WAY ANOVA FOR THE WET SUBZONE SOILS AW, BW, GW, LW AND SW 92 2-5 THE RESULTS OF ONE-WAY^  ANOVA FOR THE DRY SUBZONE SOILS AD, BD AND GD. . . . 93 2-6 THE RESULTS OF DUNCAN'S MULTIPLE RANGE TEST FOR THE B HORIZONS WHERE THE GEOLOGY-CLIMATE INTERACTION IS SIGNIFICANT 99 2- 7 DUNCAN'S MULTIPLE RANGE TEST APPLIED TO ONE-WAY ANALYSIS OF VARIANCE FOR WET SUBZONE SOILS 101 3- 1 THE OBSERVED RANGE OF VARIATION ASCRIBED TO SUBSAMPLING AND ANALYTICAL METHOD 107 3-2 THE NUMBER OF-SAMPLES REQUIRED TO.ATTAIN AN ALLOWABLE ERROR OF ±10 PERCENT FOR DRY SUBZONE SOILS, WET SUBZONE SOILS AND ALL- SOILS USING MEDIAN ESTIMATES OF VARIANCE I l l 3-3 A COMPARISON OF NUTRIENT STOCKS IN THE TOTAL B HORIZONS AS DETERMINED BY. MODAL PIT SAMPLING VERSUS COMPOSITE SAMPLING WITHIN PLOTS 113 LIST OF FIGURES FIGURE Page 1-1 THE STUDY AREAS AND CLIMATE STATIONS 9 1-2 WALKLEY-BLACK ORGANIC CARBON AND pH-DEPENDENT CATION EXCHANGE CAPACITY. . . 12 1-3 PYROPHOSPHATE-EXTRACTABLE IRON AND ALUMINUM IN THE B HORIZONS 19 1-4 OXALATE-EXTRACTABLE IRON AND ALUMINUM IN THE B HORIZONS 20 1- 5 CITRATE-DITHIONITE-EXTRACTABLE IRON AND ALUMINUM IN THE B HORIZONS 21 2- 1 SAMPLING METHODS 83 x i INTRODUCTION At the present t ime, deta i led information on the s o i l s of Vancouver Island i s la rge ly res t r i c ted to the up l i f ted coastal p la in areas, the Nanaimo Lowland, the Estevan Coastal P la in and the Alberni Basin of Holland (1964). The published so i l surveys of Day, Farstad and Lai rd (1959) and Valentine (1971) are confined to the Nanaimo Lowland and Estevan Coastal Pla in respec t ive ly , where s o i l s developed predominantly from glaciomarine, g l a c i o f l u v i a l and a l l u v i a l parent mater ia ls . Only minor areas of so i l s developed from g lac ia l t i l l were mapped. The deta i led studies and/or mapping of Keser (1969), Bhoojedhur (1969), Baker (1974) and Lewis (1974) s im i l a r l y assess mainly the coastal lowlands and only encompass a minor area of the t i l l so i l s of Hol land's (1964) Vancouver Island Ranges physiographic region. Keser and St. P i e r re ' s (1973) compendium of s o i l s of Vancouver Is land, however, provides descr ipt ions and some analyses for a number of t i l l s o i l s which occur mainly in the coastal lowland areas. Many s o i l s of the Vancouver Island Ranges are among the most productive forest s i tes in Canada, yet they have received very l i t t l e study un t i l recent ly . Current ly , s o i l survey e f for ts are being expended throughout Vancouver Island by the Resource Analysis Unit of the Environment and Land Use Committee Secre ta r ia t , by the B r i t i s h Columbia Forest Service and by a number of pr ivate forestry companies. Because of the increasing in terest shown in the capab i l i t i e s 1 2 and l im i ta t ions of the t i l l derived s o i l s of the Vancouver Island Ranges, th is d isser ta t ion was envisioned as providing background information on, and a genetic understanding of , a number of widely-occurring benchmark s o i l s across the i n te r i o r port ion of Vancouver Is land. F ie ld reconnaissance during 1971 indicated that so i l morphology was re lated to the l i t h o l o g i c o r i g in of the g l ac i a l t i l l s from which the s o i l s der ived, supporting, the emphasis placed on bedrock geology by Dr. Keser in his then recent ly completed mapping and interpretat ion system for the forest lands of B r i t i s h Columbia (Keser, 1970). The reconnaissance also confirmed.the better known re la t ionsh ips of so i l to c l imate, b io ta , topography and time. In add i t ion , the considerable v a r i a b i l i t y of these s o i l s became apparent. As a resu l t of the reconnaissance i t was proposed to study non-l i t h i c , moderately well drained, g l ac i a l t i l l - d e r i v e d s o i l s of f i ve 1 i t ho log i ca l l y d i s t i nc t t i l l s in two cl imate-vegetat ion zones. Cl imate, vegetation and geology fac tors were allowed to vary wi th in l im i t s whi le other s i t e factors such as so i l water regime and topographic pos i t ion were kept as constant as possible in order to ascerta in the impact of t i l l l i tho logy and of cl imate and vegetation on so i l morphology, pedogenesis, and nutr ient s tatus. V a r i a b i l i t y was quant i ta t ive ly assessed by the design of a su i tab le sampling scheme. CHAPTER I MORPHOLOGY AND GENESIS OF THE SOILS Introduction The deep, moderately well drained, t i l l - d e r i v e d s o i l s of Vancouver Island are general ly c l a s s i f i e d as various subgroups of the podzol great groups of so i l (Canada Soi l Survey Committee, 1974). Eight n o n - l i t h i c , moderately well drained, t i l l - d e r i v e d so i l s were characterized in deta i l in order to encompass the observed range of the Vancouver Island podzols. Vancouver Island was a su i tab le study area since a wide range of bedrock geology and re lated t i l l s occurs and, although the cl imate i s general ly wet, considerable di f ferences in to ta l p rec ip i ta t ion are experienced on the windward and leeward sides of the Island. Five geology groupings based on dominant t i l l l i tho logy were studied: andesi t ic (A), basa l t i c (B), g ran i t i c (G), limestone (L) and schistose (S). The so i l s developed on the various t i l l s were placed into two c l imat ic subzones on the basis of vegetation and supportive c l imat ic data. The dry subzone (D) corresponds to Kra j ina 's (1969) dry subzone of the Coastal Western Hemlock biogeocl imatic zone (CWHa), which is characterized by a pronounced summer dry season and i s dominated by Douglas f i r [Pseudotsugo. menziesii (Mirb.) Franco) and western hemlock {Tsuga heterophylla (Raf.) Sarg . ) . The wet subzone (W) of the Coastal 3 4 Western Hemlock biogeocl imatic zone (CWHb) i s character ized by a perhumid cl imate which engenders forests dominated by western hemlock, P a c i f i c s i l v e r f i r {Abies amabilis (Dougl.) Forbes) and western red cedar (Thuja -plioata Donn). Since l imestone- and sch is t -der ived t i l l s were not found in the dry subzone, the design was not complete and eight rather than ten d i s t i n c t s o i l s were sampled as out l ined in Table 1-1. Other so i l forming factors such as topography, drainage and aerat ion, and age were kept r e l a t i v e l y constant. TABLE 1-1 THE EXPERIMENTAL DESIGN Geology - T i l l Lithology andesi t ic basa l t i c g ran i t i c limestone schistose (A) (B) (G) (L) (S) Climate subzone: CWHa (D) s o i l AD s o i l BD s o i l GD -CWHb (W) s o i l AW s o i l BW s o i l GW s o i l LW s o i l SW Af ter ou t l in ing materials and methods employed, var ia t ions among the eight Vancouver Island podzols are discussed and the impact of the c l imat ic and geologic so i l forming factors i s assessed. A generalized "Vancouver Island model!1 of podzols i s then synthesized from these eight s o i l s by considerat ion of the many properties that these s o i l s have in common. Subsequently, th is model is compared and contrasted with the " c l a s s i c a l model" of podzols, which arose in Europe, formed the basis of c l a s s i f i c a t i o n in North America un t i l the 5 1960's, and which even today strongly inf luences thinking on podzol genesis. The substant ial d i f ferences between the two models that are brought out by th is comparison w i l l be analyzed and a concept of genesis i s presented which accounts for the occurrence of these two divergent models of podzol s o i l s . Mater ia ls and Methods F ie ld Sampling Modal p i ts representing the eight s o i l s were chosen a f ter extensive f i e l d checking of v a r i a b i l i t y (see Chapters 2 and 3). A l l strongly expressed horizons - LF, H, Ae where present, B and C - were described and sampled. The dominant B horizon was a r b i t r a r i l y subdivided into 15 centimetre s l i ces for descr ip t ion and sampling in order to ca re fu l l y assess depth functions within th is master horizon. Laboratory Methods The s o i l s were a i r dr ied and the mineral samples were crushed with a wooden r o l l e r and sieved in order to determine the f rac t ions less than two mil 1imetres,from two mi l l imetres to two centimetres and greater than two centimetres. So i l texture was determined by a combination of wet s ieving to determine percent sand, and the hydrometer method (Day, 1965) to determine percent c lay . Percent s i l t , taken as the two to 50 micron f r a c t i o n , was taken to be 100 percent minus percent sand and percent c lay . Chemical analyses were undertaken for the two mi l l imetre f r ac t i on . pH of mineral samples was determined in both a 1:1 so i l :water suspension and in a 1:2 soi l :0.01M CaCl ? suspension. pH of organic 6 samples was determined in 1:4 so i l :water and 1:8 so i l :0 .1M C a C ^ suspensions. Total carbon was determined by induction furnace techniques (A l l i son , 1965); organic carbon., by the Walkley-Black method ( A l l i s o n , 1965). Total nitrogen was assessed by the semi-micro Kjeldahl method (Bremner, 1965); to ta l su l f u r , by induction furnace techniques (Leco, 1954). Avai lab le phosphorus was estimated by Bray's 0.03N NH4F - 0.025N HC1 extract ion (Olson and Dean, 1965). The exchangeable cat ions were determined for the mineral samples by atomic absorption spectrophotometry af ter displacement by neut ra l , normal NH^OAc. Cation exchange capacity at pH 7.0 was determined by displacement with KCI and d i s t i l l a t i o n by semi-micro Kjeldahl a f ter the extract ion of the exchangeable cations by NH^OAc. The e f fec t ive cation exchange capacity was determined by displacement with NaCl according to the method of Clark (1965). Base saturat ion was also assessed on the basis of C la rk ' s method. Exchange ac id i t y was evaluated by the barium chlor ide-tr iethanolamine method (Peech, 1965). Total rather than exchangeable values were determined for the organic LFH samples, since i t i s believed that the to ta l values are more sens i t ive to geologic d i f ferences. Furthermore the bulk of the elements u l t imate ly become ava i lab le to organisms by decomposition. The method involved dry ashing with a muffle furnace, d isso lu t ion in warm 2N HC1 and determination of Ca, Mg, Na, K, Fe, A l , Mn, Cu and Zn by atomic absorption spectrophotometry (Chapman and Pra t t , 1961). Studies were undertaken to determine the i ron and aluminum that is extractable from the mineral samples using sodium pyrophosphate 7 (pH 10.0) (Bascomb, 1968), acid ammonium oxalate (McKeague and Day, 1966) and c i t r a t e -d i t h i on i t e (McKeague and Day, 1966). The c lay f rac t ion was separated for X-ray d i f f r a c t i o n analys is by means of a super-centr i fuge. Glass s l ides were prepared of the clays af ter saturat ion of the c lay with potassium and magnesium. Further treatment included heating the potassium.si ides to 300°C and 500°C and solvat ion of the magnesium s l i de with g l yce ro l . Interpre-ta t ion of the c lay mineralogy followed Rich and Kunze (1964) and Jackson (1956). X-ray f luorescence.techniques were used to determine the elemental content of the uppermost B and C horizons (Kubota and Lazar, 1971). Results and Discussion Var ia t ion wi th in the  Vancouver Island Podzol So i l s The eight d i f ferent n o n - l i t h i c , moderately wel l- 'drained, t i l l -derived podzol s o i l s that were sampled in th is study encompass a range of cl imate and geology as out l ined e a r l i e r in Table 1-1. Detai led descr ipt ions and analyses are presented, in f u l l in Appendix 1-1. Comparing and contrast ing of these eight so i l s allows the assessment of the ef fect of cl imate and geology upon the Vancouver Island podzols and f a c i l i t a t e s the synthesis o f .a general ized concept of genesis. The Effects of Var ia t ion in Climate Cl imat ic data relevant to the eight s o i l s i s presented in Table 1-2. The locat ion of the cl imate stat ions in re la t i on to the 8 TABLE.1-2 SELECTED CLIMATE STATIONS WITHIN THE STUDY AREA Climate Stat ion So i l Mean Temperature Annual Jan. (°c) July Mean Prec ip i ta t ion Annual July-Aug. (mm) Days Cowichan L. Forestry AD 9.6 1.0 17.3 2121 72 172 Duncan Bay BD 8.9 2.2 17.8 1:593 99 123 Nanaimo River Camp GD 9.0 2.0 17.3 1598 56 153 Hoi berg ( h i l l s i t e ) AW.LW 6.1 1.7 11.1 3653 .296 Port A l i c e BW 9.4 3.2 17.3 3207 134 208 Port Renfrew GW.SW - - - 3917 157 --Source: B.C. Department of Agr icu l tu re . modal p i ts i s given in Figure 1-1. For s o i l s assigned to the dry subzone (D), annual p rec ip i ta t ion ranges from 1593 to 2121 mi l l imet res ; for s o i l s assigned to the wet subzone (W), from 3207 to 3653 m i l l i -metres. Mean temperatures for the two zones are not notably d i f f e ren t , except in the Hoi berg area where cool summer temperatures keep the mean annual temperature almost three degrees below a l l other s ta t ions . Given the res t r i c ted range of cl imate wi thin the study area, the ef fect of cl imate upon gross p r o f i l e morphology is .by no means obvious. Although a general, trend to somewhat darker-colored B horizons (one unit of value on the Munsell charts) i s usual in the wet subzone, i t appears that so i l co lo r , the most s t r i k i ng charac te r i s t i c of the B horizons, is more c lose ly re lated to geology than c l imate. For basa l t i c t i l l s o i l s , probably the most uniform of the geologic 9 FIGURE 1 - 1 . STUDY AREAS AND CLIMATE STATIONS 10 groupings, the dominant B color i s SYR 5/6 (d) i n the dry subzone as opposed to 5YR 4/6 (d) in the wet subzone. S i m i l a r l y , texture cannot eas i l y be re la ted to c l imate, because the var ia t ion in parent mater ia ls , a charac te r i s t i c of t i l l s , obscures any trend. Neither structure nor consistence were observed to be s i g n i f i c a n t l y affected by the range of cl imate under considerat ion. The amount and d i s t r i bu t i on of organic matter in s o i l s wi th in the wet and dry subzones, however, i s a main point of d i f ference that can be at t r ibuted to c l imate. Surface accumulations of organic matter are not affected so much as are the subsurface accumulations in the B horizon. The to ta l thickness of LFH in both subzones i s general ly between seven and twelve centimetres, with approximately f i f t y percent LF and f i f t y percent H. The H tends to be more amorphous and mucky in the wet subzone, and more f e l t y in the dry subzone. The thickness and nature of the LFH i s much more sens i t i ve to elevation-induced c l imat i c d i f ferences. One s o i l , GW, sampled at a somewhat higher elevat ion than the other seven s o i l s , has an LFH of 22 centimetres. This fo l lows the trend of much greater accumulation of surface organic mater ia ls with increased elevat ion that was observed in the Lower Coast Mountains of the mainland. 1 Possib ly the lower so i l temperatures together with the increased moisture at higher e levat ions , rather than increased wetness alone as at lower e levat ions, is responsible for these greater accumulations. The accumulation of organic matter in the B horizon of the Vrom unpublished f i e l d notes of H. Luttmerding and T. Lewis during so i l survey of the Langley and Vancouver mapsheets. 11 eight so i l s i s shown graphica l ly in Figure 1-2. Consistent ly with the andes i t i c , basa l t i c and g ran i t i c t i l l s o i l s , the wet subzone s o i l s have greater accumulations of organic mater ials in the B than do the corresponding dry subzone s o i l s . The wet limestone s o i l (LW) also exhibi ts large organic accumulations. Only one wet subzone s o i l , that derived from the schistose t i l l (SW), has re l a t i ve l y low organic matter content, and in th is regard i s more c lose ly a l l i e d with the three dry subzone s o i l s (AD, BD, 6D). It would appear, therefore, that the higher r a i n f a l l of the wet subzone s i g n i f i c a n t l y increases the amount of organic material that i s transported into the B in suspension; in e f fec t , the more perco la t ion, the more organic matter accumulated in the B horizon. If th is i s the case, the r e l a t i ve l y low organic matter content in the B of the SW so i l can be at t r ibuted to i t s s i l t loam texture. Percolat ion and therefore turbulent flow and transport of f ine organic mater ials i n th i s s i l t y B can be expected to be considerably lower than in the sandy to loam B horizons of the other s o i l s . The somewhat lower amount of organic matter in the BW B horizon may well be a resu l t of the somewhat lower tota l p rec ip i ta t ion in the Port McNeil area of the wet subzone. Nitrogen and su l fu r content i s c lose ly related to organic matter and therefore general ly s im i la r trends and re la t ionships apply. Ava i lab le phosphorus by Bray's PI method is s i g n i f i c a n t l y affected by cl imate. In the dry subzone s o i l s , ava i lab le phosphorus ranges from three to eleven parts per m i l l i o n . In the wet subzone s o i l s ava i lab le phosphorus i s usual ly below two parts per m i l l i o n . (See Table 1-3). 1 2 F i g u r e 1 -2 . W a i k l e y - B l a c k o r g a n i c c a r b o n and pH dependent c a t i o n exchange c a p a c i t y i n the B h o r i z o n s . o) 80 pH dependent • cation exchange capacity \ i AW,--, \ VA \\ \sw 0 15 30 45 60 75 90 105 120 135 Depth (cm) Walk ley-Black organic carbon 13 TABLE 1-3 AVAILABLE PHOSPHORUS (BRAY PI) IN THE UPPERMOST B (0-15 cm) Soi l Avai lab le P (ppm) AD 11.0 AW 1.2 BD 5.0 BW 1.6 GD 3.2 GW 0.4 LW 3.7 SW 0.6 The pH of the LFH horizons of the wet subzone s o i l s i s usual ly one hal f to one f u l l pH unit lower than that of dry subzone s o i l s . In the B horizons, a di f ference of less than one half of a pH uni t i s common, although the trend i s less consistent than in the LFH. Since the eight s o i l s were sampled over a three month per iod, var ia t ion in pH due to season and recent weather condit ions may have clouded the above trends. The appreciable di f ferences observed in cat ion exchange capac-i t y resu l t from the methodology as well as c l imat ic d i f ferences. Cation exchange capacity determined by NH^OAc (pH 7.0) i s cons is tent ly much higher than that determined by the NaCl method. In r e a l i t y , the widely-used NH^OAc (pH 7.0) exchange values are a r t i f i c i a l l y high because the 14 highly-buffered extract ing solut ion at pH 7.0 induces exchange of H, Al and Fe from organic matter which would not be exchanged under the natural low pH s i tua t ion experienced in the s o i l . The unbuffered sodium chlor ide method involves exchange of cations at a much lower pH, which i s near that of natural s o i l condi t ions. The sodium ch lor ide cat ion exchange capacity thereby estimates the "e f fec t i ve " exchange capacity of the s o i l . Most of the t ru l y pH-dependent cat ion exchange capacity is represented by the di f ference in the exchange capaci t ies between the NH^OAc (pH 7.0) and NaCl methods. This di f ference represents highly pH-dependent exchange s i tes associated with organic matter and sesquioxides. Three mechanisms for such pH-dependent cation exchange s i tes have been impl icated. At pfi 7.0 considerable aluminum and i ron that i s complexed to organic matter is replaced by the ammonium and i s prec ip i ta ted as insoluble hydroxides (Clark, 1964). S im i l a r l y , exchange s i tes on layer s i l i c a t e s to which aluminum and iron are f ixed can be released by ra i s ing the pH to favor the formation of insoluble hydroxides (Clark, 1964; Shen and R ich , 1962). Dissociat ion of protons from the funct ional groups of organic matter also contributes to pH-dependent cat ion exchange capaci ty. As seen in Table 1-4 cat ion exchange capacity i s cons is tent ly higher in the wet subzone s o i l s , regardless of which of the two methods was used. Furthermore, the pH-dependent component ranges from 11 to 35 times the pH-independent or "e f fec t i ve" component of cat ion exchange capacity. For the most par t , the e f fec t ive component of cation exchange capacity l i e s below two mi l l iequ iva len ts per 100,grams of s o i l . 15 TABLE 1-4 THE CATION EXCHANGE CAPACITY OF THE UPPERMOST B HORIZONS ( 0 - 1 5 cm) Cation Exchange Capacity NH40Ac(pH 7.0) NaCI method method pH-dependent So i l — meq/lOOg BD 12.0 0.7 11.3 BW 43.7 1.2 42.5 AD 34.8 0.9 33.9 AW 57.7 2.7 55.0 GD 11.9 1.4 10.5 GW 67.1 1.9 65.2 LW 47.8 4.1 43.7 SW 20.8 1.0 19.8 The fact that the pH-dependent component is greater in the wet subzone than in the dry subzone s o i l s r e f l ec t s the greater organic matter and sesquioxide content of the wet subzone s o i l s . As with organic matter, one wet subzone so i l is somewhat anomalous with regard to exchange capaci ty. The SW so i l has not iceably lower pH-dependent cat ion exchange capacity as a resu l t of i t s lower organic matter and sesquioxide contents. The range of base saturat ion experienced in the uppermost B horizons is indicated in Table 1-5. The low base saturat ion values derived from the NH^OAc (pH 7.0) method are deceiv ingly low, a d i rec t 16 TABLE 1-5 THE BASE UPPERMOST B SATURATION OF HORIZONS (0 -THE 15 cm) Percent base saturat ion So i l Nf 140Ac (7.0) NaCl AD 1.2 80.7 AW 0.5 16.8 BD 7.4 62.9 BW 0.6 40.2 GD 13.2 95.8 GW 1.3 83.7 LW 1.4 12.7 SW 0.6 20.4 resu l t of the un rea l i s t i c estimation of the cat ion exchange capacity at pH 7.0. They are included here only for comparative purposes, because a considerable volume of e a r l i e r work does not employ the NaCl method. Clark (1964) maintains that estimates of base saturat ion should be based on cat ion exchange capacity values which include only that part of the exchange complex occupied by ions that are exchangeable and which do not include exchange s i tes that are blocked by f ixed Al or Fe. S im i l a r l y , Coleman et al. (1959) suggests that base saturat ion values should be calculated from the so-ca l led permanent charge or "e f fec t i ve" component of the C.E.C. The NaCl-derived base saturat ion values more reasonably f u l f i l l the aims of Clark and Coleman. 17 As expected, both cat ion exchange capacity and base saturat ion of the B horizons are i nd i r ec t l y and d i r ec t l y affected by c l imate. The wet subzone so i l i s 64, 23 and 12 percent lower than the dry subzone so i l for andes i t i c - , basa l t i c - and gran i t i c -der ived so i l s respect ive ly in the upper 15 centimetres of the B horizons. At greater depth in the B ' s , the ef fect of. c l imate i s less pronounced, so that wet and dry subzone base saturat ion values tend to converge. The response of the indiv idual cations to cl imate i s var iab le . Exchangeable magnesium, potassium and sodium a t ta in a s imi la r range of values in the dry and wet subzones. Exchangeable calcium, on the other TABLE 1-6 EXCHANGEABLE CATIONS IN THE UPPERMOST B HORIZONS ( 0 - 1 5 cm) (NH,0Ac method) Ca Mg K Na So i l meq/lOOg AD .15 .12 .10 .05 AW N.D. .14 .06 .11 BD .70 .09 .06 .04 BW .01 .17 .07 .03 GD 1.21 .17 .16 .03 GW .30 .37 .12 .10 LW .02 .47 .07 .09 SW N.D. .04 .05 .03 18 hand, i s very much lower in the wet subzone so i l s and in fact i s frequently not even detectable, in the B horizon of the AW and SW s o i l s . It was observed on several occasions during analysis that the SW so i l ac tua l ly t ied up the small amount of calcium ava i lab le in the extract ing so lu t ion ; the analysis for the B horizon samples was even lower than that of the reagent blank. Furthermore, the low calcium contents, unl ike tota l base saturat ion remain consis tent ly low throughout the thickness of the B horizon. Probably the most profound inf luence of cl imate upon the t in-derived s o i l s of Vancouver Island i s with respect to the strength of B horizon development, as measured by the content of extractable sesquioxides. Figures 1-3 to 1-5 present the depth functions of pyrophosphate-, oxa la te - , and c i t r a t e - d i t h i o n i t e - i r o n and aluminum within the B and C horizons of the s o i l s . Pyrophospha.te-iron content e f fec t i ve ly separates the dry and wet subzone s o i l s . The dry subzone s o i l s are grouped well with very low values; wet subzone s o i l s , while general ly separated from the dry, show considerable dev ia t ion. The separation between the dry and wet basal t -der ived s o i l s i s less d i s t i n c t , perhaps because the amount of p rec ip i ta t ion at the BW s i t e is not great ly d i f fe rent from that at the BD s i t e . Although the vegetation in the Port Hardy-Port McNeil area i s d i s t i n c t l y wet western hemlock subzone, annual p rec ip i ta t ion i s r e l a t i v e l y low (1638 mm.) but i s well supplemented by high summer .humidities and frequent fog. Such factors exert a r e l a t i v e l y stronger ef fect upon vegetation than upon the s o i l , which i s much more sens i t ive to the actual amount of rainwater percolat ing through the s o i l . Figure 1-3. Pyrophosphate-extractable i ron and aluminum in the B hor izons. E D .5 3 E 3 c 2 N Q W AW Aluminum AW--'' * « 60 75 90 105 120 135 Depth (cm) P 31 c W O J i w $ W ^ X Iron BD 15 30 17 G W 6'0 75 90 Depth (cm? 135" 20 Figure 1-4. Oxalate-extractable i ron and aluminum in the B horizons I 6 c 1 < 5 c S i 4 Q_ Aluminum ..Mf. .AW_\.... \' • xm 15 3 0 45 6 0 75 9 0 105 120 1 3 ? Depth fcm) F i g u r e 1 -5 . C i t r a t e - d i t h i o n i t e - e x t r a c t a b l e i r o n and a luminum i n the B h o r i z o n s . 0 1 —• 1 , , , 15 3 0 45 6 0 75 9 0 105 120 135 Depth (cm) 22 Pyrophosphate aluminum fol lows s im i la r trends to i ron , however the separation of dry and wet subzone basa l t i c s o i l s i s more pronounced, pa r t i cu la r l y in the upper B horizon. Oxalate-extractable i ron achieves excel lent separation of the dry and wet subzone s o i l s of andesi te- , basal t - and gran i t i c -der ived t i l l s . The separation cons is tent ly l i e s between one and two percent. The separation of the two basa l t i c s o i l s i s notably improved in comparison to pyrophosphate i ron. Oxalate-extractable aluminum content also e f fec t i ve l y separates the dry and wet subzone s o i l s . Since oxalate extracts dominantly the ac id-so lub le organic complexes and amorphous, hydrous sesquioxides (Bascomb, 1968), i t probably provides an ind ica t ion of recent ly weathered sesquioxides as well as weathered sesquioxides accumulated over considerable pedogenic time. Pyrophosphate-extractable sesqui-oxides on the other hand, are l i k e l y more c lose ly related to recent so i l dynamics. Oxalate extract ion therefore i s more useful as an ind icat ion of the degree of weathering and should be expected to more e f fec t i ve ly separate the dry and wet subzone s o i l s . The fact that th is separation is observed would tend to suggest that i n - s i t u weathering may be a mechanism in the formation of the B horizon. C i t r a te -d i t h i on i t e extract ion of i ron and aluminum does not always make a c lear separation of the dry and wet subzone s o i l s . The separation of the dry and wet andesite-derived t i l l s o i l s is pa r t i cu la r l y poor. Since c i t r a t e - d i t h i o n i t e extracts r e l a t i ve l y well c r ys ta l l i zed oxides as well as the range of sesquioxide compounds extracted by oxalate (Bascomb, 1968), d i f ferences in geology tend to obscure the ef fect of c l imate. Even the separation between the dry and 23 wet basal t -der ived t i l l so i l s i s poorer than with ei ther oxalate or pyrophosphate. This probably ar ises because the c i t r a t e -d i t h i on i t e solut ion extracts a s i m i l a r , r e l a t i v e l y large, more c r y s t a l l i n e f rac t ion from both s o i l s , thereby overshadowing the contr ibut ion of amorphous and complexed forms of the sesquioxides. Elemental composition i s probably the most sens i t ive index for determining the long-term i r r eve rs i b l e ef fects of cl imate upon so i l development, in par t i cu la r the weathering component of the to ta l so i l development process. Table 1-7 presents the ra t ios of calc ium, magnesium, potassium, sodium, s i l i c o n , and iron to aluminum in the B and C horizons, as determined by semi-quant i tat ive X-ray f luorescence. The percent change in these ra t ios from the B to the C i s also tabulated. With very few exceptions, the percent change shows s ign i f i can t reductions of the bases and s i l i c o n , but s i gn i f i can t increases of i ron in the B horizons of a l l eight s o i l s . Comparison of the wet and dry subzone s o i l s derived from andesite, basalt and g ran i t i c t i l l s shows that the percent changes are general ly much greater in the wet subzone s o i l s . Calcium and magnesium are espec ia l l y consistent in th is regard and changes in the wet subzone s o i l s are usual ly two to three times greater than in the dry subzone s o i l s . The same trend i s observed with potassium in basa l t i c and g ran i t i c mater ia ls . However in th is regard andesi t ic s o i l s are somewhat anomalous. Percent change for sodium is least consistent . However, the proximity of most of the wet subzone s o i l s (AW, GW, LW, SW) to the open ocean re la t i ve to the dry subzone.soi ls and BW, which occur on the 24 eastern side of the Is land, would r e s u l t . i n somewhat higher sodium inputs from prec ip i ta t ion ( C a r r o l l , 1962). Such continual inputs w i l l o f fset to some extent, losses of sodium due to weathering of the primary minerals. The percent change in. the s i l icon/a luminum.rat ios i s general ly larger in wet than in dry subzone s o i l s , as i s evidenced by the comparison of BD to BW and GD to GW. The andesi t ic s o i l s , as with potassium, are somewhat anomalous. The Effects of Var iat ion in Geology In order to assess the ef fects of geologic parent material var ia t ions on so i l development, one must f i r s t quantify the inherent geologic d i f ferences. The semi-quanti tat ive X-ray fluorescence data achieves th is end. This method i s a more sensi t ive tool than extract ions in detecting parent material d i f ferences, as i t i s much less affected by grain s ize d i f ferences. Table 1-7 presents the ra t io of various elements to aluminum in the parent t i l l , as well as in the B hor izon, and also shows percent change in the ra t ios between the t i l l and the B horizon. Concentrating f i r s t on the t i l l s , there i s a r e l a t i v e l y low Ca/Al ra t i o in the andesi t ic t i l l s in comparison, with the basa l t i c t i l l s . To a somewhat lesser degree magnesium pa ra l l e l s th is trend. In the g ran i t i c t i l l s , the r e l a t i v e l y low C a / A l , Mg/Al , Fe/Al ra t ios and r e l a t i v e l y high K/Al ra t io of the dry subzone t i l l confirms the f i e l d observation that th is t i l l i s derived from r e l a t i v e l y ac id i c granodior i tes. The f i e l d c l a s s i f i c a t i o n of the wet subzone t i l l as TABLE 1-7 ELEMENT TO ALUMINUM RATIOS IN THE B AND C HORIZON AND THE PERCENT CHANGE FROM C TO B AD AW BD BW GD GW LW SW Ca/Al B 3.96 1.90 15.1 6.8 5.9 6.0 8.0 2.1 T i l l 4.56 5.76 18.8 21.3 8.1 13.9 13.25 3.5 % Change -13.2 -67.0 -19.7 -68.1 -27.2 - -56.8 -39.6 -40.0 K/Al B .845 1.00 1.22 .507 2.14 .415 .999 1.45 T i l l 2.00 1.90 1.22 1.01 2.47 .812 1.37 2.64 % Change -57.7 -47.4 +0.6 -50.0 -13.6 -48.9 -27.1 -44.9 Na/Al B .034 .036 .056 .036 .035 .033 .056 .039 T i l l .041 .042 .055 .059 .044 .037 .052 .045 % Change -17.1 -14.3 +1.8 -39.0 -20.5 -10.8 +7.7 -13.3 Mg/Al B .059 .054 .077 . .052 .050 .058 .085 .054 T i l l .078 .085 .111 .135 .065 .114 .111 .085 % Change -24.4 -36.5 -30.6 -61.5 -23.1 -49.1 -23.4 -36.5 S i / A l B 1.39 1.80 2.81 1.25 2.27 .758 2.54 2.65 T i l l 2.36 2.68 3.33 3.14 3.08 1.86 3.00 3.73 % Change -41.1 -32.9 -15.6 -60.2 -26.3 -59.2 -15.3 -29.0 Fe/Al B 9.43 10.8 10.5 11.4 4.16 7.68 15.0 6.37 T i l l 7.21 7.16 7.42 9.71 4.36 6.05 8.09 4.77 % Change +30.7 +50.8 +41.5 +17.4 -4.6 +26.9 +85.4 +33.5 i 26 being comprised of more basic d i o r i t i c rocks i s s im i l a r l y confirmed by i t s r e l a t i ve l y high Ca/Al and Mg/Al r a t i o s , yet low K/Al r a t i o . The re la t i ve a c i d i t y , or perhaps more co r rec t l y , the r e l a t i v e l y more s i l i ceous nature, of the dry subzone in t rus ive t i l l is further supported by i t s high S i / A l r a t i o . The S i / A l ra t io of the GW t i l l , on the other hand, is pa r t i cu la r l y low. The impure nature of the limestone t i l l ; that i s , the inc lus ion of a s ign i f i can t component of igneous mater ia ls , i s indicated by the fac t that none of the ra t ios of the limestone t i l l i s d r a s t i c a l l y d i f fe rent from the other t i l l s . It i s by no means dominated by calcium or magnesium as would be expected with a pure l imestone- or dolomite-derived t i l l . The c lay mineralogy of the t i l l includes traces of quartz and fe ldspar as wel l as dolomite. The sch is t -der ived t i l l i s d i s t i n c t i v e because of i t s very low Ca/Al r a t i o , low Fe/Al ra t io and yet high K/Al and S i / A l r a t i o s . The clay f rac t ion of th is t i l l contains s i gn i f i can t quartz and vermicu l i te with traces of i l l i t e and kao l i n i t e . T i l l composition di f ferences are also re f lec ted in the B horizons of these Vancouver Island podzols, but to a lesser degree than in the parent t i l l . Through time, and espec ia l l y in the wet subzone where weathering i s more severe, the podzol forming processes tend to ameliorate the t i l l composition d i f ferences. Inherited di f ferences are more apparent in dry subzone s o i l s , where weathering is less intense. Comparison of aluminum r a t i o s , exchangeable cations and extractable sesquioxides in the B horizons allows for the evaluat ion of the ef fect of t i l l d i f ferences on B horizon composition. The r e l a t i ve l y 27 high calcium content in the basa l t i c t i l l s in contrast to the andesi t ic t i l l s resul ts in higher calcium content in the B horizons, pa r t i cu la r l y in the dry subzone. Exchangeable calcium values are also correspondingly high. In the wet subzone, the stronger weathering environment of the BW so i l has reduced the Ca/Al ra t i o from 21.3 in the parent t i l l to only 6.8 in the B horizon. Exchangeable calcium i s low in comparison to BD but i s quite high in re la t ion to the other wet subzone s o i l s (See Table 1-6). S i m i l a r l y , the low calcium content of the andes i t ic t i l l has resulted in a calcium-poor B horizon. Both Ca/Al ra t io and exchangeable calcium values are low; exchangeable calcium i s not even detectable in much of the B horizon of the AW s o i l . The r e l a t i v e l y high calcium and magnesium content of the g ran i t i c t i l l of the wet subzone i s not apparent in the overly ing B horizon. The equal iz ing ef fect of weathering has brought the Ca/Al and Mg/Al ra t ios into l i ne with most other s o i l s . In a para l le l fash ion, the high calcium and magnesium content of the limestone t i l l i s s i g n i f i c a n t l y reduced in the B. However, magnesium remains anomalously high in the B horizon of the LW s o i l . This is confirmed by the exchangeable values; calcium i s merely 0.02 meq/lOOg but magnesium, 0.47 meq/lOOg. The low potassium content of the GW t i l l i s carr ied over into the B hor izon, even though th is i s not re f lec ted in exchangeable potassium values. S i m i l a r l y , the high potassium GD t i l l has a high potassium B hor izon, but in th i s s o i l the. high va lues. in the B are confirmed by exchangeable K. The l o w , s i l i c a content of the GW t i l l i s also strongly re f lec ted in i t s B hor izon, which has a S i / A l ra t io of 28 only 0.76. Furthermore, the consistent absence of an Ae horizon in th is podzol suggests the importance of t i l l l i tho logy in podzol development. This i s further supported by the development of the GD s o i l ; in th is case, under a r e l a t i v e l y dry c l imate, a high s i l i c a , low i ron parent material has developed into a s o i l with a good Ae but a very weak B horizon (Fe/Al ra t io of only 4.16). The weakness of the B horizon of the GD so i l was indicated ea r l i e r by very low pyrophosphate, oxalate and c i t r a t e - d i t h i o n i t e extract ions of i ron and aluminum. At the other end of the climate-geology spectrum of these eight s o i l s , the highly s i l i ceous nature of the schistose t i l l i s car r ied over into i t s over ly ing B horizon. Furthermore, the SW s o i l consis tent ly has a well expressed Ae horizon. A correspondingly strong Bf is not observed however, as one might expect according to c l a s s i c a l podzol izat ion theory. In f a c t , when assessed on the basis of e i ther Fe/Al ra t i o or pyrophosphate-, oxalate- and c i t r a t e - d i t h i o n i t e -extractable i ron values, the B horizon of the SW s o i l i s the poorest in the wet subzone. Despite the strong morphological s i m i l a r i t y of the two Ae's encountered in th is study, one in the.SW so i l of the wetter western side of Vancouver Is land, the other, in the GD s o i l of the dr ie r eastern s ide , the two Ae horizons have some notably d i f fe rent chemical propert ies (See. Table 1-8). While both have r e l a t i v e l y low pH-dependent cat ion exchange capaci ty , the exchange complex.of the Ae of the dry subzone s o i l i s dominated by calcium, that of the wet subzone s o i l , by aluminum. As a resu l t , base saturat ion i s 95.8 percent for the dry subzone so i l and only 2.7 percent for the wet subzone s o i l . Both 29 TABLE 1-8 CHEMICAL PROPERTIES OF THE TWO Ae HORIZONS Ae horizon Variables GD Soi l SW Soi l Climate dry wet Material - g ran i t i c t i l l schistose t i l l Texture loamy sand s i l t loam pH in water 5.0 4.1 CEC (NH40Ac) meq/lOOg 12.9 5.5 CEC (NaCl) meq/lOOg 3.0 6.1 Exchange Ca. (NH40Ac) meq/lOOg 2.2 0.3 Exchange Al (NaCl) meq/lOOg 0.1 5.9 % base saturat ion (NaCl) 95.8 2.7 Exchange ac id i t y meq/lOOg 6.7 25.4 Pyrophosphate Fe + Al (%) .26 .46 Oxalate Fe + Al (%) .50 .48 C i t r a te -d i t h i on i t e Fe + Al (%) 1.63 1,08 horizons, however, y i e l d very l i t t l e iron and aluminum when c i t r a t e -d i t h i on i t e , oxalate and pyrophosphate extract ions are carr ied out, thereby j us t i f y i ng the "Ae" notation for an e luv ia ted, surface mineral horizon. The inf luence of the schistose t i l l on i t s overlying B i s further evidenced by considerat ion of, calcium and potassium contents. The exceedingly low calcium content is . re f lec ted strongly in the B horizon. As mentioned e a r l i e r , exchangeable calcium was usual ly not detectable by standard analysis and in fac t , the SW s o i l frequently absorbed whatever calcium was present in the extract ing so lu t ion . The high potassium content of the parent t i l l car r ies over into the B horizon. Exchangeable potassium values for the SW s o i l , however, are not s i g n i f i c a n t l y d i f fe ren t from the other s o i l s . Comparison of the S i / A l and Fe/Al ra t ios in the B and C horizons of the LW so i l strongly indicates the ro le of weathering in B horizon formation. The percent change in the S i / A l ra t io from C to B i s pa r t i cu la r l y low, espec ia l l y for a wet subzone s o i l , whereas the percent change in the Fe/Al ra t io i s the highest observed. In the other s o i l s , the main source of weathered i ron i s s i l i c a t e minerals, therefore S i / A l percent changes are c lose ly re la ted . However, in the limestone t i l l , even though s i g n i f i c a n t l y contaminated by s i l i c a t e rocks, a s ign i f i can t amount of i ron/could be expected to weather from the limestone i t s e l f . Only i f th i s i s a major source of iron could r e l a t i v e l y small changes in the S i / A l ra t i o be coincident with large changes in the Fe/Al r a t i o . The observed ra t ios would therefore tend to indicate that the limestone component of the t i l l has weathered to a residual material r i ch in i r on , as i s the case with terra rossa s o i l s . In summary, the inherent parent material di f ferences pers is t in the roughly 10,000-year old B horizons of the Vancouver Island podzols. The extent of th is persistence i s re lated to cl imate as i t af fects the degree of weathering. Modi f icat ion: of the t i l l i s thereby considerably more pronounced in the wet subzone than in the dry. Minerals that are res is tan t to weathering, notably quartz, pers is t and accumulate to form contrast ing Ae horizons. 31 X-ray f luorescence i s more d iscr iminat ing in the study of these changes than i s assessment of exchangeable cat ions. Exchangeable values are apparently less sens i t i ve and more var iab le because of the small proportion that exchangeable cat ions represent in re la t ion to elemental content, and because of the inf luence of grain s ize and so i l dynamics pa r t i cu la r l y with respect to organic matter. The Vancouver Island Model In general , the Vancouver Island model i s character ized by a seven to 20 centimetre surface layer of accumulated mor organic matter. A t h i n , gray Ae horizon only infrequent ly marks the beginning of the mineral s o i l . Below the Ae, or more t y p i c a l l y d i r e c t l y below the H, the B i s usual ly a 60 to 120 centimetres th i ck , br ight , reddish brown to yel lowish brown, somewhat f i rm, and only weakly structured horizon. Transi t ion to the r e l a t i v e l y unaltered t i l l i s always abrupt, although there i s evidence that the uppermost t i l l i s somewhat more indurated than at depth. The LFH The surface organic layer i s fur ther subdivided on the basis of the degree of decomposition. The fresh l i t t e r (L) i s usual ly a t h i n , loose scat ter ing of recent forest debr is . Beneath, the fermenting horizon (F) has a r e l a t i v e l y constant two-to-eight centimetre th ickness, is layered and f e l t y and often permeated by white and yellow fungal mycel ia. Where accumulations of rotten wood occur, the F i s l o c a l l y much th icker , up to a metre. The well decomposed humus horizon (H) i s a mucky, amorphous, black to dark reddish brown organic material that 32 ranges from f i v e to ten centimetres in thickness. Roots are abundant, in fact at a maximum, in the H hor izon. The demarcation between the organic and mineral horizons i s sharp; that i s , there i s very l i t t l e mechanical incorporat ion of organic.matter into the mineral s o i l by the a c t i v i t y of s o i l animals. Chemical analysis indicates that the surface organic horizons of these podzols are strongly a c i d i c ; pH in water ranges from 3.2 to 4.9. Most of the ava i lab le nutr ient stock of these s o i l s resides in the organic layers . This appl ies to the bases as well as to the nutr ients more commonly associated with organic matter; namely, n i t rogen, phosphorus and su l fu r . The carbon-nitrogen ra t io of the LF horizons ranges from 37 to 54; of the H horizons, from 24 to 45. Such physical and chemical propert ies are d e f i n i t i v e for mor types of humus. The Ae Horizon The Ae horizon i s only sporad ica l ly present in the Vancouver Island podzols. It i s en t i re l y absent in so i l s derived from t i l l s with cer ta in l i t h o l o g i e s , such as the andes i t ic and basa l t i c t i l l s , but i t does occur as a discontinuous horizon up to f i ve centimetres in thickness in s o i l s derived from ac id i c in t rus ive or schistose t i l l s . Where i t occurs, the Ae i s a s t r i k i ng grayish mineral horizon comprised of very c lean , uncoated gra ins , mostly sand and s i l t , that are not aggregated. This imparts a sharp feel to the material when rubbed between the f i nge rs , even to the s i l t y Ae of the sch is t -der ived t i l l . The lack of i ron and organic coatings causes the horizon's color to assume the l i gh t colors of the predominant minerals, quartz and the fe ldspars. 33 The B Horizon The B horizon strongly dominates the p r o f i l e of the Vancouver Island model because of i t s considerable thickness and r e l a t i v e l y bright co lo ra t ion . The master B ranges in thickness from 60 to 120 centimetres. The predominance of oxid ized as opposed to reduced iron engenders reddish brown to yel lowish brown co lo rs , general ly of 5YR or 7.5YR Munsell hues with chromas of four or more. Var iable amounts of f i n e , dark-colored organic matter further color the B horizon. Because of the somewhat random d is t r i bu t ion of the organic matter, d iscrete colors are frequently patchy, pa r t i cu la r l y in the upper B horizon. This patchiness resu l ts from the per iodic churning of the so i l by the uprooting of trees during storms. Upturned root systems, which in coastal B r i t i s h Columbia are frequently several metres across, d is turb a considerable volume of s o i l . Varying amounts of organic debris are buried in the process, subsequently undergo decomposition and thereby l o c a l l y increase organic matter content. The importance of th is process has only recent ly been recognized, and the " tu rb ic " (u) horizon modif ier has been introduced into the 1976 Canadian c l a s s i f i c a t i o n ( C . S . S . C . , 1976). In the "nu t r i t i on p l o t s " , s o i l p i ts having unmixed B horizons were in the minor i ty ; mixing was frequently apparent in at least half of the 16 p i ts dug in each p lo t . In-s i tu decomposition of old roots and, on steeper s lopes, mixing by so i l creep further detract from order ly sub-horizonation of the master B. Regardless of the mixing in the upper B, organic content general ly decreases with depth. The lowest 30 to 45 centimetres of the B commonly have somewhat mott led, du l le r co lo rs , ind ica t i ve of inc ip ien t g ley ing. The periodic reducing condit ions that occur when the s o i l becomes saturated above the impermeable t i l l have resulted in "g j " horizons. These horizons also have increased organic matter content and carbon-nitrogen ra t i os . Sandy loam textures predominate in the B horizons of the Vancouver Island podzols, although coarser and f i ne r t i l l s with accompanying coarser or f i n e r . B ' s also occur. The clay s i ze f r a c t i o n , general ly below ten percent, is dominated by oxides rather than p h y l l o s i l i c a t e s . As a r e s u l t , these B horizons have predominantly weak subangular blocky s t ruc tures, f r i a b l e to somewhat f i rm consistence when moist and only s l i gh t p l a s t i c i t y when wet. I t i s the chemical rather than physical proper t ies, however, that are diagnost ic for the B horizons of the Vancouver Island model. In pa r t i cu l a r , the high content of sesquioxides sets these s o i l s apart. Analysis of the BW s o i l , which has been selected as representat ive of the Vancouver Island model, y i e lds the fol lowing data. C i t ra te -d i th ion i te -ex t rac tab le i ron content var ies from about three to f i ve percent in th is basa l t i c t i l l - d e r i v e d s o i l ; oxalate-extractable Fe + A l , from 6.5 to almost eight percent. The current c r i t e r i on for a podzol Bf horizon in the Canadian c l a s s i f i c a t i o n system i s an increase of 0.8 percent in oxalate-extractable Fe + Al over the C horizon. In the representat ive BW s o i l , th is would necessi tate an oxalate-extractable Fe + Al content of 2.5 percent in the B horizon. The BW so i l exceeds th is requirement by from four to 5.5 percent, s ix to eight times that required to meet the Bf c r i t e r i o n . 35 Pyrophosphate-extractable Fe and A l values of the BW s o i l are about 2.5 times greater than the required 0.6 percent but only in the uppermost Bf. At greater depth, values are adequate but not excessive. While oxalate- and c i t ra te -d i th ion i te -ex t rac tab le values tend to be more sens i t i ve to long-term accumulations of sesquioxides, pyrophosphate is believed to extract mainly the iron and aluminum that i s complexed with organic matter (Bascomb, 1968). Pyrophosphate-extractable values, therefore, can be expected to be more c lose ly re lated to present and recent s o i l dynamics. These large concentrations of sesquioxides are , in add i t ion , maintained throughout the thickness of the B horizon. Perusal of the depth funct ions, indicates that f luc tuat ion of the various extract ions of Fe and Al ranges from less than one to over two percent. Much of the var ia t ion is random, a resu l t of turbat ion, so that the order ly occurrence of maxima reported in other work (Franzmeier and Whiteside, 1963b; Blume and Schwertmann, 1969) i s not observed. A general trend of somewhat decreased content-with depth is observed however. A notable exception to the general trend i s that of oxa la te -A l , which frequently at ta ins i t s maximum in the gj horizons overlying the t i l l . Table 1-9, summarizes the mean and standard deviat ions of extractable sesquioxide values for 44 B and 15 BC and C horizons. The large sesquioxide accumulations dominate the mineralogy of the c lay f r ac t i on . X-ray d i f f r a c t i o n of the B horizons of the Vancouver Island podzols resu l ts i n general ly low in tens i ty peaks for the p h y l l o s i l i c a t e clays and in two s o i l s , BW and GW, no peaks were in evidence. Most commonly the B horizon clay f rac t ion contains only small TABLE 1-9 THE SESQUIOXIDE CONTENT OF THE B AND C HORIZONS OF THE VANCOUVER ISLAND PODZOLS Mean Standard Deviation Var iable % B horizon samples (n=44): Pyrophosphate-extractable Al 1.12 ±0.75 Fe 0.49 ±0.56 Fe + Al 1.61 ±1.19 oxalate-extractable Al 3.42 ±2.05 Fe 1.81 ±0.94 Fe + Al 5.23 ±2.58 c i t ra te -d i th ion i te -ex t rac tab le Al 2.12 ±1.20 Fe 2.91 ±1.27 Fe + Al 5.02 ±1.92 BC and C horizon samples (n=15): Pyrophosphate-extractable Al 0.28 ±0.16 Fe 0.09 ±0.18 Fe + Al 0.37 ±0.32 oxalate-extractable Al 1.30 ±0.78 Fe 0.59 ±0.25 11 Fe + Al 1.89 ±0.95 c i t ra te -d i th ion i te -ex t rac tab le Al 0.52 ±0.28 Fe 0.88 ±0.47 n II Fe + Al 1.40 ±0.61 37 amounts, trace to less than f i ve percent, of kaol . in i te, ch lo r i t e and ch lo r i te -vermicu l i te i n t e r s t r a t i f i e d minerals. The B horizons, of the Vancouver Island podzols contain appreciable amounts of organic matter. Data from the "nu t r i t ion p lo ts" ind icate a range from 76,000 to 745,000 kilograms per hectare. Corresponding organic carbon values in the B range from one to eleven percent. Such var ia t ions are not a t y p i c a l ; the wide range i s due par t ly to var ia t ions in the c l imat ic and geologic s i t e factors and par t ly to the random addit ions of organic matter caused by mechanical s o i l mixing. The combination of high sesquioxide and organic carbon contents of the Vancouver Island podzols engenders large pH-dependent cat ion exchange capaci ty. Table 1-4 indicates the cat ion exchange capacity of the uppermost B horizon both as determined by ammonium acetate buffered at pH 7.0 and by unbuffered sodium ch lo r ide , as well as the di f ference in exchange capacity as derived by these two methods. A number of se lec t ive mul t ip le regression analyses were under-taken for the 44 B horizon samples of the Vancouver Island podzols, in order to e lucidate the re la t ionsh ip between cation exchange capacity and c l ay , organic matter and sesquioxide. The independent var iables were selected on the basis of some known or inferred physico-chemical mechanism. In add i t ion , they were chosen because of the i r re la t i ve independence, an important basic assumption in mul t ip le regression. Table 1-10, presents a summary of the most useful regressions. From a pred ic t ive point of view, equation 4 provides the best 38 TABLE 1-10 THE RELATIONSHIPS BETWEEN CATION EXCHANGE AND ORGANIC MATTER, CLAY AND SESQUIOXIDES Equation Variables 9 Standard Error No. Dependent (Y) Independent (X's) R F Prob. (Y) 1. CEC7 WBC, CLAY, ALP .9446 0.0 4.95 2. CEC7 WBC, CLAY, SP .9439 0.0 4.99 3. CEC7 WBC, CLAY, ALOX .9683 0.0 3.75 4. CEC7 WBC, CLAY, SOX .9795 0.0 3.01 5. CEC7 WBC, CLAY, ALCD .9673 0.0 3.81 6. CEC7 WBC, CLAY, SCD .9773 0.0 3.17 7. DCEC WBC, ALP .9272 0.0 5.53 8. DCEC WBC, SP .9246 0.0 5.63 9. DCEC WBC, ALOX .9695 0.0 3.58 10. DCEC WBC, SOX .9730 0.0 3.37 11. DCEC WBC, ALCD .9681 0.0 3.66 12. DCEC WBC, SCD .9488 0.0 4.64 (n= =44) Where: CEC7 i s cat ion exchange capacity by NH^OAc (pH 7 .0) , WBC is organic carbon by Walkley Black Method., CLAY i s percent c l ay , ALP and SP are extractable aluminum and extractable aluminum + iron by pyrophosphate (pH 10.0), ALOX and SOX are oxalate-extractable aluminum and aluminum + iron respec t ive ly , ALCD and SCD are c i t r a t e - d i t h i o n i t e -extractable aluminum and aluminum + iron respect ive ly and DCEC i s the di f ference in exchange capacity between NH.OAc (7.0) and NaCl methods. 39 estimate of the cat ion exchange capacity at pH 7.0: CEC7 = 4.10 + 4.63 (WBC) - 0.23 (CLAY) + 2.50 (SOX) The contr ibut ions of each of the three independent va r iab les , Walkley-Black organic carbon, percent c l ay , and oxalate-extractable sesquioxides are highly s ign i f i can t ( i e . at p = 0.01) in th is instance, although the contr ibut ions of organic carbon and oxalate-extractable sesquioxide far outweigh that of percent c lay . The three var iables account for almost 98 percent of the var ia t ion in the cat ion exchange capacity (pH 7 .0) , with a standard error of only 3.0 meq/lOOg. The probab i l i t y of achieving th is resu l t by chance i s n i l for a l l p rac t ica l purposes. Equation 3 which u t i l i z e s oxalate-extractable aluminum is only s l i g h t l y less p red ic t i ve , ind icat ing that the contr ibut ion of the amorphous i ron materials to cat ion exchange i s much lower than that of the amorphous aluminum mater ia ls . The r e l a t i v e l y low simple cor re la t ion between oxalate-extractable aluminum and i ron (r = 0.17) supports th is in te rpre ta t ion . Pa ra l l e l r e s u l t s , with only s l i g h t l y lower coe f f i c ien ts of determination and somewhat higher standard e r ro rs , are found when pyrophosphate- or c i t ra te -d i th ion i te -ex t rac tab le values are used. One anomaly is observed when comparing equations 1 and 2. Here the use of pyrophosphate-extractable^aluminum values is s l i g h t l y more predic t ive than the use of combined.iron plus aluminum values. Simple cor re la t ion coe f f i c ien ts indicate that Walkley-Black carbon alone accounts for 93 percent of the var ia t ion in cat ion exchange capacity (pH 7.0) ; oxalate-extractable aluminum a lone , . fo r 83 percent of th is va r ia t i on . Percent c lay accounts for only 14 percent of th is var ia t ion . From the point of view of understanding the mechanisms of cation exchange, the l im i ta t ions of regression techniques are apparent from the above s t a t i s t i c s . Although i t i s evident that the contr ibut ion of clays to cat ion exchange in these B horizons i s r e l a t i v e l y smal l , i t i s more d i f f i c u l t to assess the re la t i ve importance of organic matter and amorphous sesquioxides, since these two var iables are somewhat in te r re la ted . The simple cor re la t ion coef f i c ien ts between Walkley-Black organic carbon and pyrophosphate-, c i t r a t e - d i t h i o n i t e - and oxalate-extractable aluminum are 0.98, 0.96 and 0.83, respec t ive ly . Referring to Table 1-10, in equation #1, 3 and 5, the more pred ic t ive nature of equation #3 may well be the resu l t of the lesser degree of in teract ion among the independent var iables than any physico-chemical mechanism. The di f ference in cat ion exchange capacity between ammonium acetate and sodium chlor ide values i s a measure of the pH-dependent exchange capacity and strongly corre la tes with organic matter and sesquioxides. In the most predic t ive equation #10, Walkley-Black carbon and oxalate-extractable iron plus aluminum accounts for. 97.3 percent of the var ia t ion in pH-dependent cat ion exchange capaci ty . The base status of the Vancouver Island podzols var ies considerably in response to both the c l imat ic and geologic s o i l forming fac tors . When based on ammonium acetate cation, exchange, percent base saturat ion i s usual ly below ten percent. Sodium chlor ide cat ion exchange values, however, are more d iscr iminat ing and the observed range of base saturat ion i s greater. The BC Horizon The uppermost 15 centimetres of the loamy sand to loam parent t i l l s exh ib i t some structura l mod i f i ca t ion , from the basal t i l l s at greater depth. This BC horizon i s pa r t i cu la r l y massive, extremely f i rm and impermeable and has more pronounced piat iness than does the unmodified t i l l below. The coarse plates are separated by very th in brown layers and, in s o i l s with A e ' s , th in l i gh te r colored layers as we l l . These could be regarded as micro Bf and Ae horizons respect ive ly . Such propert ies character ize the duric horizon (BCd), a concept current ly being invest igated by the Canadian So i l Survey Committee ( C . S . S . C . , 1973). Contents of extractable sesquioxides and organic matter are somewhat higher in the BCd than in the underlying parent t i l l . Understanding the morphology and genesis of these indurated BC horizons, however, w i l l require micromorphological and microanalyt ical methods. The recent work of McKeague and Sprout (1975) suggests a cementing agent comprised of amorphous materials of various proportions of A l , Si and Fe. The C Horizon pH of the C horizon is general ly about one half to one unit higher than in the overly ing horizons. Organic carbon is low, general ly less than 0.5 percent., Because exchangeable Al i s very low, base saturat ion (NaCl) cons is tent ly exceeds 90 percent and often approaches 100 percent. (See Table.1,-11). The noticeable discrepancy between cat ion exchange capacity, values determined by ammonium acetate and sodium chlor ide methods does ind ica te , however, that considerable 42 Table 1-11 THE CATION EXCHANGE CAPACITY AND BASE SATURATION OF THE PARENT TILLS C.E.C. (meq/lOOg) B.S. (%) So i l NH40Ac NaCl NaCl AD 8.6 0.6 98.2 AW 13.0 1.5 92.0 BD 4.1 0.3 98.1 BW 2.6 1.0 99.4 GD 8.6 2.7 100.0 GW 13.5 0.5 95.5 LW 7.0 0.3 92.9 SW 5.2 0.2 96.9 aluminum and iron i s f ixed to layer s i l i c a t e s , even in the parent mater ia l . The i ns ign i f i can t content of organic matter in the parent t i l l precludes any s ign i f i can t contr ibut ion of protons or complexed aluminum and i ron as a source of th is pH-dependent cation exchange capaci ty. This i ron and aluminum, therefore, is probably derived from pre-g lac ia l weathering of the rego l i t h . Amount of i ron and aluminum extracted by pyrophosphate, oxalate and c i t r a t e - d i t h i o n i t e var ies with t i l l l i tho logy but i s cons is tent ly very much lower than in the B horizon. The " C l a s s i c a l " Podzol Lutz and Chandler, in the i r basic text.on forest s o i l s published in 1946, presented a general ized descr ip t ion of the podzol so i l p r o f i l e as fo l lows: . . . the f i r s t layers encountered usual ly consis t of organic matter in varying stages of decomposition. F a i r l y wel l -def ined subdivis ions of the unincorporated organic matter are frequently d is t ingu ishab le ; they are referred to as the Aoo and Ao layers or as L, F, and H layers . The thickness of the unincorporated material var ies from less than 1 to more than 12 inches. It ranges in color from brown to black, possesses a r e l a t i v e l y high cation-exchange capaci ty , and i s acid in react ion. The mineral s o i l immediately below the humus layer i s also acid in react ion and is commonly dark gray because of organic material which has washed i n . When present, th is so i l i s designated as the Al (Ah) horizon. Below the Al (Ah) i s the A2 (Ae) hor izon, in which e luv ia t ion has been most ac t i ve ; sometimes the Al horizon i s lacking or is present only as a t race. The A2 i s gray or whi t ish gray, s t ructure less or sometimes laminated, acid in reac t ion , high in s i l i c a , and r e l a t i v e l y low in i r on , aluminum, and bases. Usual ly i t contains less nitrogen and organic matter and has lower cation-exchange capacity than the horizon below. The thickness of the A2 var ies from less than 1 to more than 30 inches, depending on the degree of p ro f i l e development. Underlying the bleached A2 hor izon, sometimes ca l led Bleicherde, i s the B2 horizon or zone of i l l u v i a t i o n . The Bl (Bh) hor izon, which i s t r a n s i t i o n a l , is commonly lacking in podzols. As a r u l e , the B2 (Bf) hor izon, which var ies from about 1 to 10 inches in th ickness, i s brown or dark brown in color and may or may not be indurated. When f i rmly cemented, th is material i s referred to as hardpan or Ortstein; i f indurated but not f i rm ly cemented, i t i s ca l led Ortevde. Var iat ions in the amount of humus and i ron have resulted in recogni t ion of so-ca l led humus podzols and i ron podzols. In passing from the B2 to lower hor izons, the color becomes l i gh te r . The B horizon contains a r e l a t i ve l y high content of organic matter, i r on , and aluminum; occasional ly there i s enrichment in bases. In podzol s o i l s the ent i re p ro f i l e above the C horizon has an acid reac t ion , but the lowest pH values general ly occur in the H layer or in the Al horizon . . . (Lutz and Chandler, 1946). In a 1959 paper that out l ined the "modern concepts of the genesis of podzols" , Stobbe and Wright (1959) concluded that , "the downward movement of organic matter and sesquioxides from the upper horizons and the i r accumulation in the B i s common to a l l so i l s in th i (the podzol) group". Table 1-12 indicates the range of p ro f i l e types that , at one TABLE 1-12 VARIOUS PROFILE TYPES CALLED "PODZOLS" P r o f i l e type (1) (£) (D (!) "(i) LH LH LH LH LH Ae Ae Bf Ae Ael Bm B C Bt Bf C C C Ae2 Bt C C l a s s i f i c a t i o n "Podzol" Canadian - pre 1968 no yes* no no no - post 1968 no yes yes no no American - Baldwin et al. (1938) yes yes no no yes - Comprehensive System (1973) no yes yes no yes German - Kubiena (1953) yes yes no no yes Russian yes yes yes 1 t yes t yes *Yes, provided the Ae i s over 1" in thickness + Y e s , i f in podzol zone time or another, have been regarded as podzols in Canadian, American, German or Russian so i l c l a s s i f i c a t i o n systems. The " c l a s s i c a l " podzol i s p ro f i l e #2; the Vancouver Island model, p ro f i l e #3. In the c l ass i ca l podzol, therefore, the diagnost ic property is the presence of a l i gh t - co lo red , ash- l i ke Ae.horizon that i s high in coarse-grained s i l i c a and from which has been eluviated sesquioxides, 45 organic matter and in some cases a lumino-s i l i ca te c l a y s . 1 T rad i t i ona l l y th is Ae horizon over l ies an i l l u v i a l B horizon that i s enriched with sesquioxides and organic matter. It i s only in recent decades that podzols have been redefined in North America, on the basis of the propert ies of the B horizon alone. In both the Canadian and American c l a s s i f i c a t i o n s , Ae's are no longer diagnost ic for spodosols or podzols. The diagnost ic charac te r i s t i c i s now regarded as Bf or spodic horizon that has been enriched with sesquioxides. In fac t , many so i l s with t rad i t iona l "podzol Ae 's " do not have B horizons s u f f i c i e n t l y enriched with sesquioxides to meet the new c r i t e r i a of Canadian Bf or American spodic horizons. These s o i l s are now c l a s s i f i e d as degraded brunisols or i ncep t i so l s . In the U .S .S .R . , zona l i ty concepts have dominated so i l c l a s s i f i c a t i o n since Dokuchaev and s o i l s that are morphologically d i s t i nc t from both c l a s s i c a l and modern North American podzols are regarded as various types of podzols i f they occur in the "podzol so i l zone". Thus, s o i l s that would now be c l a s s i f i e d as Orthic Gray Luvisols in Canada l i k e l y would be ca l led "podzols on clayey grounds" in the podzol zone (Ponomareva, 1969), or "gray forested" s o i l s in the forest-steppe t rans i t i on zone. Concepts of Podzol izat ion , C lass ica l concepts of podzol izat ion focus on the formation of the Ae and B horizons as being inexorably related to one another. The Hhe word "podzol" or ig inates from the Russian and l i t e r a l l y t ranslated means, "under the ash". 46 mobi l izat ion and downward transport of i ron and aluminum in the so i l has been at t r ibuted to three basic mechanisms: i o n i c , c o l l o i d a l , and complexed. / Transport of Iron and Aluminum in Ionic Form Both Deb (.1950) and Stobbe and Wright (1959) noted that the s o l u b i l i t y of f e r r i c iron above pH 3.5 i s very low and therefore both discounted movement of f e r r i c ions as an ef fec t ive method of transport of iron into the B horizon. Van Schuylenborgh and Bruggenwert (1965), by knowing.the v a r i a b i l i t y of f e r r i c i ron s o l u b i l i t y with pH and by making assumptions concerning porosi ty and p rec ip i t a t i on , calculated that 430,000 years at pH 4.0 and 17,400,000 years at pH 5.0 would be required to form an ex is t ing podzol through transport of i ron in the f e r r i c state (See Table 1-13). Since the podzol considered in the study was known to be about 15,000 years o l d , having developed an aeol ian sands since Pleistocene g l a c i a t i o n , ion ic transport of iron was discounted. S i m i l a r l y , the authors calculated that 204 years at pH 4.0 and 67,200 years at pH 5.0 would be required to t ranslocate su f f i c i en t ion ic aluminum to explain i t s present d i s t r i bu t i on . Van Schuylenborgh and Bruggenwert concluded, therefore, that the s o l u b i l i t y of aluminum hydroxide appeared to be. large enough to explain removal of the aluminum from the Ae during podzol izat ion. Since upward movements of aluminum (or iron) were not considered in the Van Schuylenborgh and Bruggenwert study, i t i s also necessary to consider other mechanisms of aluminum movement in order to f u l l y explain the observed red i s t r i bu t i on . 47 TABLE 1-13 VARIATION IN THE SOLUBILITY OF FERRIC IRON AND ALUMINUM WITH pH Concentration of Concentration of +++ +++ Fe Al pH mo les / l i t r e 4.0 6.98 X l O " 7 6.92 X 10" 3 4.5 9.41 X 10" 8 2.54 X l O " 4 5.0 1.72 X 10" 8 2.10 X 10" 5 5.5 4.21 X l O " 9 3.80 X 10" 6 6.0 1.21 X l O " 9 1.21 X l O " 6 Source: Van Schuylenborgh and Bruggenwert (1965). Although most podzols experience ox id iz ing condit ions throughout the year, small pockets of reducing condit ions may occur where there are higher than average organic buildups or where pore space d i scon t i nu i t i es , resu l t ing from textural cont rasts , temporari ly perch water wi thin the pedon. Reduced or ferrous i ron that forms under anaerobic condit ions i s appreciably more soluble over a wide range of pH (Deb, 1950). Transport of ferrous i ron , therefore, may be pa r t i cu la r l y s i gn i f i can t in imperfect ly drained, gleyed (often ortstein) podzols which experience periods of reducing condi t ions. Reducing condit ions tend to speed up the formation of the Ae when present, as evidenced by comparing two s o i l s of s im i la r age, both developed.on sandy materials of old ra ised beaches. The wel l -drained Sunshine ser ies has an Ae that ranges from a trace to one inch ; the imperfectly drained Summer se r i es , from f i ve to 48 ten inches. Apparently the per iodic reducing condit ions in the imperfectly drained Summer ser ies enhance the downward movement of i r on , most l i k e l y in the ferrous form. Although the s o l u b i l i t y of f e r r i c iron and, to a lesser extent, aluminum i s low at the pH range common in wel l -drained podzols, movement in th is form should not be en t i re l y discounted but only regarded as playing a rather minor ro le in the red is t r i bu t ion of these const i tuents. Transport of Iron and Aluminum as Sols Several modes of transport of i ron involving sols have been suggested. Mattson et al. (1937) suggested that i ron was translocated as posi t ively-charged iron oxide s o l s . There i s no evidence of Ae horizons having excess pos i t i ve charge, however, and th is theory has since been discounted. S i l i ca -p ro tec ted iron oxide sols have also been suggested (Reifenberg,(1947)). Deb (1950) noted that the pept iz ing act ion of s i l i c a i s e f fec t ive from a lka l i ne to s l i g h t l y acid react ion but i s ine f fec t i ve at pH 4.0. Barbier (1938), on the other hand, pointed out that 13 parts of s i l i c a are required to peptize one part of i ron oxide. If th i s i s so, negative enrichment of i ron oxide should be evident in the Ae rather than the observed case, negative enrichment of s i l i c a . Aarnio (1913) proposed that i ron was moved as negat ively-charged, humus-protected i ron oxide so l s . His data suggests that the amount of humus required may exceed. 2.5 times the concentration of f e r r i c oxide, an amount of co l l o i da l humus that i s considerably larger than i s present in a so i l so lu t ion . Deb (1950) studied the ef fects of concentration and react ion of the humus-protected i ron oxide sols on the i r mutual coagulation and pept izat ion. His major f indings were: a) The pept iz ing a b i l i t y of humus var ies widely with the source of humus, concentration of the i ron-oxide sol and pH. Humus may carry from three to ten times i t s own weight of i ron oxide. b) The lower the concentration of the i ron , the less humus i s required for pept iza t ion. c) The ra t io of humus to f e r r i c oxide i s constant for each kind of humus over a wide range of concentrat ions. d) The lower the pH, the more humus i s required for pept izat ion and coagulat ion. e) The amount of humus required to peptize one half of the coagulated mixture i s on the average 10 parts humus to 100 parts f e r r i c oxide. Amounts of humus necessary for the f u l l pept izat ion of an iron oxide sol having 100 ppm iron oxide and pH near 4.0 w i l l not be more than 30 to 40 percent of the amount of i ron oxide, much less than was previously thought necessary. However, Deb's data does not prove conclus ively whether the mechanism of i ron transport involves a sol or an organic complex. His observation that the ra t io of humus to i ron is constant over a wide range of concentrat ions, a sto ichiometr ic type of re la t i onsh ip , points to a chemical rather than a co l l o i da l mechanism. "Protect ion" by humus could then be interpreted as chemical bonding. Transport as Organo-metall ic Complexes Recently, more sophist icated chemical studies point more and more to a mechanism of transport involv ing organo-metall ic complexes. One of the controversies surrounding the organo-metal l ic complex theory centers around whether the complexed i ron i s in a reduced or oxidized form. Bloomfield (1953), using extracts of Scots pine needles and Kauri bark and leaves, found that i n i t i a l reduction of f e r r i c i ron by the extract was rap id . This suggested that the extract contained a powerful reducing agent but, since the extract i t s e l f was not suscept ib le to atmospheric ox idat ion , Bloomfield concluded that a read i ly reducible f e r r i c complex must f i r s t be formed pr ior to reduction to a ferrous complex. The presence of a complex was indicated when he found that , at pH 8 .0 , large amounts of i ron were retained in so lu t ion . Since ferrous hydroxide prec ip i ta tes at pH's greater than 5.5, the ferrous iron remaining in solut ion must be complexed. Bloomfield la te r (1955) at t r ibuted the solut ion and reduction of f e r r i c oxide to the j o i n t act ion of carboxyl and phenol groups, reduction being effected pr imar i ly by the phenol groups. Khanna and Stevenson (1962) concurred, observing that the metals were bound pr imar i ly by ac id ic groups, probably carboxyls. Schnitzer and Desjardin, (1962) characterized the organic matter of the Bh of the Armadale so i l ser ies and l a t e r , Schnitzer and his co-workers elucidated the react ion mechanisms involved in complex formation between a number of metals and the Armadale Bh f u l v i e acid f r ac t i on . Their major f indings inc lude: 1. The organic matter formed s tab le , water-soluble complexes with F e 3 + , A l 3 + , C a 2 + , M g 2 + , C u 2 + and N i 2 + (Schnitzer and Skinner, 1963a). 3+ 3+ 2. At pH 3.0, Fe and Al formed soluble 1:1 molar complexes; at 3+ pH 5.0, water-soluble 2:1 Fe - f u l v i c acid complexes were formed (Schnitzer and Skinner, 1963a). 3+ 3+ 3. Indications of 6:1 molar Fe - and Al - f u l v i c acid complexes were also found. As these are inso lub le , the f indings suggest that a ser ies of complexes from 1:1 to 6:1 resu l t with decreasing water s o l u b i l i t y (Schnitzer and Skinner, 1963a). 4. There was evidence of e lect rovalent bonding between negatively charged COOH groups and pos i t i ve l y charged, p a r t i a l l y hydroxylated iron and aluminum (Schnitzer and Skinner, 1963a). 5. Methylation of the act ive acid groups. (COOH) reduced i ron uptake to very low values, ind icat ing the important ro le of the carboxyl group in the complexing react ion (Schnitzer and Skinner, 1963b). 6. Infra-red spectra indicated the presence of both i ron- and aluminum-carboxylate . bonds (Schnitzer and Skinner, 1964). 7. Blocking of e i ther COOH or phenolic OH groups s i g n i f i c a n t l y reduced complexing of metals (Schnitzer and Skinner, 1965). 8. Both COOH and phenolic OH groups appeared to react simultaneously with a react ion of the same type as f e r r i c i ron and s a l i c y l i c acid (COOH and OH in ortho pos i t ion on benzene r ing ) . A lcoho l ic OH did not par t i c ipa te in the react ion (Schnitzer and Skinner, 1965). 52 A natural s o i l leachate was compared with the f u l v i c acid preparation used in the above work in. order to determine the extent of modi f icat ion of. the f u l v i c f rac t ion ascr ibable to extract ion and pu r i f i ca t i on (Schnitzer and Desjardins, 1969). The f u l v i c acid of the leachate, which amounted to 87 percent,, was very s im i la r to the extracted f u l v i c ac id . Due to i t s water s o l u b i l i t y and the high content of oxygen-containing funct ional groups, the leachate had a l l the charac te r i s t i cs of an e f f i c i en t metal.complexing agent (Schnitzer and Desjardins, 1969). Schnitzer (1970) fur ther determined that the charac te r i s t i cs of the Armadale Bh f u l v i c acid were also typ ica l of other podzols with respect to elemental composition, funct ional group content, E4/E6 ra t ios and IR spectra. The recent work of Gamble (1970)/ supports Schn i tzer 's f indings and further i den t i f i es the importance of. f u l v i c acids with C00H and phenolic OH funct ional groups in an.ortho conf igurat ion in the complexing of metals. The ro le of simple organic acids in the podzol izat ion process has been theorized for many years by both s o i l sc ien t i s t s and plant eco log is ts . More recent ly , the work of .Bruckert (1970a, b) shed considerable l i gh t on the ro le that th is f rac t ion of s o i l organic matter plays in podzol formation. Simple organic acids are normally short-l i ved in the s o i l . Espec ia l l y in s o i l s with mull type surface horizons, abundant cat ion supply and vigorous b io log ica l a c t i v i t y favors i n - s i t u decomposition or organic acids and very l i t t l e movement of them into the B. Acid production under mor is much greater than under mu l l ; for example, 14 times more c i t r i c acid and 9 times more v a n i l l i c acid i s produced annually under mor than mul l . The acids produced are longer - l i ved , as they are subjected to less b io log ica l a c t i v i t y . Under mors, which are charac te r i s t i c of podzols, there is therefore, a pronounced movement of simple organic acids into the B. A l ipha t i c ac ids , notably oxa l i c and c i t r i c , were found to be capable of complexing sesquioxides and other metals. Aromatic ac ids , such as p-coumaric and p-hydroxybenzoic a c i d , on the other hand, were incapable of complexing. It should be noted, however, that the aromatic acids studied did not include any with an ortho conf igurat ion of carboxyl and phenolic OH groups. Bruckert a lso examined other f rac t ions of. so i l organic matter regarding the i r complexing a b i l i t y . He found that the higher molecular weight precursors of f u l v i c acid were about hal f as e f fec t ive on a weight bas is , as the simple organic acids in the complexing of f e r r i c i ron . Van Schuylenborgh and Bruggenwert (1965) carr ied out a study on complex formation using para-hydroxybenzoic a c i d , which they believed to be a decomposition product of l i g n i n and in abundant supply in podzols as a model substance. Note that Bruckert (1970) found that para-hydroxybenzoic acid was an ine f fec t i ve complexing agent. By making the same assumptions as for transport in ion ic form, Van Schuylenborgh and Bruggenwert (1965) calculated that 20,000 years at pH 4.0 and 70,000 years at pH 5.0 would be required by th is complexing mechanism for the i r 15,000 year old podzol to develop, assuming also a para-hydroxybenzoic acid concentration of 10~ 4 moles per l i t r e . Since the rate of movement of iron i s also proportional to the concentration 54 TABLE 1-14 THE CONCENTRATION OF COMPLEXED IRON IN 10" 4M PARA-HYDROXYBENZOIC ACID IN EQUILIBRIUM WITH FERRIC HYDROXIDE pH cone, of complexes (moles / l i t re ) 4.0 0.15 x 10~ 4 4.5 0.90 x 10" 5 5.0 0.43 x IO" 5 of para-hydroxybenzoic a c i d , Van Schuylenborgh and Bruggenwert concluded that , "the leaching of i ron can be read i l y understood by assuming the formation of soluble complexes with f i n a l simple decomposition products of fresh organic matter" (Van Schuylenborgh and Bruggenwert, 1965). The l i t t e r of cer ta in spec ies, such as kaur i , cer ta in eucalypts and possib ly hemlock, has an unusual a b i l i t y to mobi l ize sesquioxides, thereby resu l t ing in l o c a l l y strong Ae horizons. Hingston (1963), for example, pointed out the special complexing e f f i c iency of several tannin-derived compounds, espec ia l l y g a l l i c acid from a eucalypt l i t t e r . P rec ip i ta t ion of Sesquioxides in the B Horizon Aarnio 's (1913) o r ig ina l humus-prptected sol theory includes prec ip i ta t ion in the B by the presence of d ivalent cat ions. Stobbe and Wright (1959), on the other hand, maintain that , while some podzols have a supply of exchangeable divalent cat ions, in the B, many have i ns ign i f i can t amounts, and also that exchangeable d ivalent cations may be ine f fec t i ve in the p rec ip i ta t ion of i ron . 55 This l a t t e r observation of Stobbe and Wright i s substantiated by Deb (1950), who a f ter variously, saturat ing podzol B horizons with lime water, found that p rec ip i ta t ion of i ron from humus-protected sols was not effected by the adsorbed calcium. Conf l i c t ing opinions regarding Bf formation ex is t among supporters of the organo-metal l ic complex theory of iron mobi l izat ion and transport. Bloomfield (1953) concluded that , "the re la t i ve s t a b i l i t y of the ferrous and aluminum compounds at high pH's indicates that reprec ip i ta t ion of oxides cannot be caused by the comparatively small changes in pH and degree of aerat ion that are l i k e l y to occur in the B hor izon." Rather, he favors the p rec ip i ta t ion of i ron by microbial attack and destruct ion of the organic Vigand. Although Deb supports the humus-protected sol concept, he acknowledges the p o s s i b i l i t y of the existence of organo-metal l ic complexes and also concludes that i t i s necessary, "to postulate a microbio logica l mechanism for the p rec ip i ta t ion of i ron" (Deb, 1950). Van Schuylenborgh and Bruggenwert (1965), on the other hand, maintain that higher pH's in the podzol B cause hydrolysis of the organo-metal l ic complexes and subsequent s p l i t t i n g of f of i ron hydroxide. Supporting evidence for th is hypothesis, however, is not extensive. The ear ly work of Gallagher (1942), Harder (1919) and Starkey and Halvorson (1927) also pointed to the microbial destruct ion of . the l igand as the means of. iron p rec ip i t a t i on . Bruckert (1970b) used carbon-14 as a tracer in order to determine the fate of downward-moving simple organic ac ids . He found.that these acids were ei ther 56 mineral ized to carbon dioxide or incorporated into humic polymers. Except for o x a l i c , which was mostly minera l ized, 75 percent of c i t r i c , 65 percent para-hydroxybenzoic, and 35 to 90 percent of v a n i l l i c acids were incorporated into polymers. Schn i tzer 's f indings that increas ing ly polynuclear metal lo-organic complexes become more inso lub le provide the basis for another possible mechanism of Bf formation. (Schni tzer , 1963a). As each f u l v i c acid molecule percolates downward i t complexes more and more sesquioxide. This increased metal loading leads to s tead i ly decreased s o l u b i l i t y un t i l f i n a l l y , the polynuclear complex i s precip i tated in the B. The molar metal-organic molecule ra t io w i l l vary with the metal , the organic molecule and the condit ions of the so i l environment. Van Schuylenborgh and Bruggenwert (1965) found that one aluminum was su f f i c i en t to p rec ip i ta te para-hydroxybenzoic a c i d ; Schnitzer and Skinner (1963a) found that f i ve to s ix iron were required to prec ip i ta te the Armadale Bh f u l v i c acid preparat ion. Enrichment of the B with Organic Matter I n f i l t r a t i o n of humus into podzol B horizons i s by means of solut ion and co l l o i da l suspension.. Dark-colored organic matter suspensions have been observed passing through Ae horizons a f ter ra ins . This organic matter i s sedimented in the B because of the slower percolat ion rates and concomittant f i l t r a t i o n of humic substances from the percolat ing water (Stobbe and Wright, 1959), Dissolved organic substances may also be immobilized in the B horizon by incorporat ion into insoluble polymeric humic substances (Bruckert, 1970b) or by the 57 formation of inso lub le , polynuclear metal lo-organic complexes. Addit ions of organic substances to the B are o f fset by minera l izat ion so that a rough equi l ibr ium is reached between addit ions and losses of organic matter to and from the s o i l . The equi l ibr ium is determined by a number of so i l and s i t e fac to rs , such as s o i l temperature and water regimes, pH and base s ta tus , and carbon-nitrogen ra t i o . The C lass ica l Podzol versus the  Vancouver Island Model As already noted, the Ae horizon i s diagnost ic in the c l ass i ca l model whereas i t is absent more often than not in the Vancouver Island model. Where i t does occur, i t has the usual character of the c l a s s i c a l Ae; namely l i gh t co lo r , acid reac t ion , high s i l i c a , and low iron and aluminum. The general morphology of the B horizon of the two models is comparable although Vancouver Island podzols tend to have much th icker B horizons than i s typ ica l of the c l a s s i c a l podzol: 60 to 120 cm. as compared with 2 to 25 cm. respect ive ly . S i m i l a r l y , in the Vancouver Island model, the B horizon tends to be much th icker than the overly ing Ae horizon whereas in the c l a s s i c a l model, the thickness of the Ae and B are usual ly e i ther comparable or the B may even be thinner than the overly ing Ae. This l a t t e r charac te r i s t i c of the c l a s s i c a l podzol i s probably la rge ly responsible for the concepts of podzol genesis that centre on the t ranslocat ion of iron and.aluminum from the Ae to the B horizon. The extent of enrichment of the B horizon of c l ass i ca l podzols i s general ly much less than that of the Vancouver Island model. 58 S t r i c t l y comparable data i s scarce because of the wide var ie ty of ana ly t ica l techniques employed at various times in .d i f fe ren t countr ies. Table 1-15 summarizes the to ta l i r on , aluminum and s i l i c o n contents as oxides of a number of " c l a s s i c a l " podzol B horizons. Even to ta l values as oxides do not compare with the extractable values of the Vancouver Island podzols. In the comparison of the two podzol models, i t i s useful to consider so i l propert ies in two rather, abstract groups: those propert ies associated with revers ib le processes and those that are bas ica l l y determined by i r r eve rs ib le processes. Propert ies associated with revers ib le processes, such as the nature of the LFH, organic matter content and d i s t r i b u t i o n , pH and base saturat ion, and even pyrophosphate-extractable sesquioxides, are l inked quite c lose ly to the environmental complex of the present and recent pedologic past. Since recent cl imate and biota la rge ly determine such propert ies and these factors themselves are r e l a t i v e l y changeable, i t i s reasonable that the so i l propert ies as well are subject to r e l a t i v e l y rapid change. A minor c l imat ic change to warmer, d r ie r condi t ions, for example, may well lead to the extension of Garry oak (Queraus -garryana Dougl.) forests on Southern Vancouver Island along with the charac te r i s t i c r i ch herbaceous understories that accompanies such fo res ts . Concurrently; there would resu l t a sh i f t from mor to mull humus forms, .as well as an increase in such factors as pH and base saturat ion. Because revers ib le processes, such as organic and nutr ient c y c l i ng , are common to both the c l ass i ca l and Vancouver Island models, the associated so i l propert ies are comparable. TABLE 1-15 THE IRON, ALUMINUM AND SILICON CONTENTS OF CLASSICAL PODZOLS Fe Al Si % as oxides So i l and Source Ae Bf C Ae Bf C Ae Bf C Adirondacks (Lutz & Chandler, 1946) 1. 36 3. 44 2.72 5. 92 14. 45 • 10. 45 86. 70 67. 09 77.11 Karel ian Isthmus (Ponamareva, 1964) 0. 30 . 1. 25 0.94 .. 5. 50 11. 46 10. 59 92. 90 82. 62 82.47 Lakewood ser ies (Jof fe , 1933) 1. 10 1. 90 1.35 0. 32 2. 50 2. 09 98. 12 93. 32 95.97 10 60 Propert ies determined by i r r eve rs ib l e processes, on the other hand, are related to the long-term pedologic environment, and for th is group there i s considerable divergence between the two models. Propert ies included in th is category involve the mineralogic and elemental composition of the s o i l . This is not to imply that the two groups of propert ies are t o t a l l y unrelated, as the posi t ion of equi l ibr ium for those factors that.respond to revers ib le processes can be expected to sh i f t somewhat in response to i r r eve rs i b l e weathering processes. The increasing amounts of sesquioxides that are produced by weathering, for example, w i l l inf luence the ef fec t ive cat ion exchange capaci ty. This in turn may sh i f t the equi l ibr ium of exchangeable bases, base saturat ion and pH. Possible Causes of the  Divergent Models The essent ia l d i f ference between the c l a s s i c a l and Vancouver Island models i s the very much greater accumulation of sesquioxides in the B horizons of the Vancouver Island model-. Since the Ae i s usual ly absent or merely a discontinuous horizon a few centimetres th ick , i t would appear that the large increase in. the sesquioxide content of the B cannot be explained so le ly by the t ranslocat ion of sesquioxides from the Ae horizon. Unless geomorphic fac to rs , such as erosion or l i t h o l o g i c d iscon t inu i t i es are implicated therefore, the genesis of these B f ' s must involve other pedogenic processes. Overlying Ae Horizons In the c l ass i ca l concept of podzol genesis, the sesquioxide accumulations of the B horizon are believed to or ig inate in the Ae 61 horizon and to be translocated to the B in i on i c , co l l o i da l or complexed forms. The absence of the Ae horizon over large areas in many of the Vancouver Island podzols gives r i se to some questions regarding the v a l i d i t y of the c l ass i ca l concept. Examination of the 16 p i ts of each of the 33 nutr ient plots allowed a thorough assessment of morphological as well as chemical var ia t ion so that the presence or absence of Ae's was well documented (See Chapter two). Even when Ae horizons were found to be associated with s o i l s derived from par t i cu la r t i l l l i t h o l o g i e s , they were discontinuous and only, a few centimetres th ick. The p o s s i b i l i t y that Ae's were formerly much th icker and have since been phys ica l l y removed needs to be considered. The la tes t ed i t ion of So i l Taxonomy .(Soi l Survey S ta f f , 1973) i den t i f i es the mixing of horizons by animals and f a l l i n g trees as a factor when well-developed spodic horizons comprise the surface mineral hor izon, over la in by only an 0 (LFH) horizon. While i t i s true that mixing by f a l l i n g trees i s a s ign i f i can t ant i -hor izonat ion process in the Vancouver Island podzols, i t does not s a t i s f a c t o r i l y explain the to ta l absence of Ae horizons over substant ial acreages. This process does exp la in , however, the discontinuous nature of Ae's where they do occur. In add i t ion , pockets of buried Aeb horizons were commonly observed within B horizons ly ing beneath the discontinuous Ae ' s . Where the Ae horizon was absent, physical removal of the Ae by surface erosion i s considered un l i ke ly . The th ick mor organic horizons of the Vancouver Island podzols provide excel lent protect ion of the underlying mineral so i l against sheet and r i l l erosion by running water 62 (Chamberlin, 1972). High i n f i l t r a t i o n rates are maintained since the organic mat precludes the dispersion of the mineral so i l by raindrop impact. In add i t ion , any overland flow that occurs does so through a tangle of f ibrous organic matter, which slows down the flow and thereby reduces the energy ava i lab le for erosion. Any mineral material that i s dislodged i s quick ly sieved out by the LFH. Removal of the protect ive LFH can occur through forest f i r e s or high-lead logging followed by slashburning, but i t i s general ly f e l t that, such events only p a r t i a l l y remove the LFH hor izon; studies indicate that even severe slashburning only removes the LFH on less than f i ve percent of the area treated (Fowells and Stephenson, 1934; Dyrness et al.* 1957; Fu l le r et al.* 1955; Tarrant, 1956). Furthermore, i f erosion of the Ae had been a factor in the genesis of Vancouver Island podzols, i t would be expected to have a random occurrence contro l led to some extent by slope gradient. Such a trend was not evident on Vancouver Island. In add i t i on , accumulations of Ae material on gently sloping areas at the foot of steep slopes was not observed. It would appear, therefore, that the c l ass i ca l concept of podzol genesis cannot alone account for the large sesquioxide accumulations in the B horizons of the Vancouver Island podzols. L i tho log ic Discont inu i t ies It could be argued that the high sesquioxide content of the B horizons i s inher i ted from the parent material and.that the abrupt t rans i t i on to the r e l a t i v e l y unweathered t i l l represents a d iscre te 1 i tho log ica l change to parent materials that have inherent ly lower iron 63 and aluminum content. Such a theory cannot eas i l y be refuted because so i l formation would have great ly changed the deposit ional charac te r i s t i cs (sor t ing , s t r a t i f i c a t i o n , texture, mineralogy, co lo r , e tc . ) of the supposed upper sediment. Examination of the to ta l content of some of the less mobile elements, such.as copper, z inc and manganese, however, reveal no s ign i f i can t anomalies. The r e l a t i v e l y constant 60 to 120 centimetre thickness of the upper-, high sesquioxide material in i t s e l f i s probably the strongest evidence against the existence of a major l i t h o l o g i c d iscon t inu i t y . If the upper layer was a separate sediment, one would expect i t to exh ib i t a range in thickness s im i la r to that observed in the lower sediment. Uniform deposit ion over large areas regardless of topography and gradient i s not conceivable for known sediments apart from loess. In th is case, textures preclude an aeol ian o r i g in for the B horizon mater ia ls . In-s i tu Weathering A th i rd hypothesis is that the high content of sesquioxides in the B horizon resul ts from the co l l ec t i on of physico-chemical processes encompassed by the term, i n - s i t u weathering. The most highly weathered s o i l s , the l a t e r i t i c or o x i s o l i c s o i l s . o f the t r op i cs , are large ly comprised of sesquioxides. Such so i ls .apparent ly resu l t from the rapid weathering associated with warm humid Tropical c l imates, operating over long periods of geologic t ime, and. involv ing repeated sequences of deposi t ion, so i l formation, and erosion. The t i l l s o i l s of Vancouver Is land, on the contrary, are developed in geo log ica l ly young parent materials that were deposited 64 during the Ple istocene. While these t i l l s undoubtedly have incorporated within them various amounts of p re -g l ac i a l l y weathered mater ia ls , as do a l l transported parent mater ia ls , r e l a t i ve l y unweathered mater ials are believed to be dominant. The cl imate of Vancouver Is land, un l ike i t s recent geologic h is tory , engenders the existence o f weathered materials (See Table 1-2). The temperature regime of the lower elevations (below 750 metres) i s moderate with mean January temperatures ranging from 1.0 to 3.2°C and mean Ju ly temperatures ranging from 11.1 to T7.8°C. The f ros t - f ree period frequently exceeds 200 days and ground freezing i s rare . Annual p rec ip i ta t ion var ies considerably throughout Vancouver Is land. Within the study area, p rec ip i ta t ion ranges from 1593 to 3917 mi l l imetres and can be expected 125 to over 200 days per year. Ju ly and August r a i n f a l l ranges from 56 mi l l imetres at Nanaimo River on the eastern side of Vancouver Island to 296 mi l l imetres at Hoi berg on the western side of the Is land. Such a temperature-precipi tat ion regime means that the many chemical react ions involved in weathering operate e f f i c i e n t l y without s i gn i f i can t in ter rupt ion. P rec ip i ta t ion , is general ly su f f i c i en t to maintain the s o i l i n a well-watered state throughout most of the year, except i n the d r ies t parts of the eastern s ide , and thus the continual f lushing of the s o i l engenders the e f f i c i e n t removal of the end products of chemical react ions. In contrast , c l a s s i c a l . podzols often develop under considerably colder and d r ie r cond i t ions. . The podzols near Hinton, Alberta for example developed under an annual p rec ip i ta t ion of about 500 m i l l i -65 metres. January mean monthly temperature i s -10.5°C; J u l y , 15.0°C. The f ros t - f ree period is only 66 days (Dumanski, 1971). Under these condit ions the rate of weathering i s considerably slower because the ground is frozen for extended periods of the year and because the removal of the end products of weathering processes is less e f fec t ive due to the lower p rec ip i t a t i on . Given the high extractable sesquioxide values of the Vancouver Island podzols and the several c l imat ic aspects that point to i n - s i t u weathering as a po ten t ia l l y s i gn i f i can t process in podzol genesis, i t i s per t inent , therefore, to examine the to ta l content of a number of elements in the B hor izon, as well as the C horizon from which the B i s presumed to be derived. Do the high extractable sesquioxides, in f ac t , r e f l ec t s i gn i f i can t changes in the to ta l composition of the solum from i t s parent material? Table 1-16 presents the ra t ios of various elements to aluminum in the B and C horizons of two of the Vancouver Island podzols, GW and BW. Aluminum was used as the base for the ra t io because of i t s abundance in the Earth 's crust and because of i t s known immobil ity under normal weathering condit ions (Polynov, 1937; Craig and Loughnan, 1964). The percent changes in the ra t ios from the C horizon to the B are comparable for the two s o i l s ; both exh ib i t large reductions in the ra t ios of calc ium, potassium and s i l i c o n to aluminum, ranging from 50 to 60 percent. Percent reductions in the sodium to aluminum rat ios are less consistent . The lower reduction in. th is ra t io for. the GW s o i l is l i k e l y a resu l t of i t s proximity, to the west coast, where sodium inputs from prec ip i ta t ion counteract to some extent sodium losses due to 66 TABLE 1-16 RATIOS OF VARIOUS ELEMENTS TO ALUMINUM AND THE CHANGE IN RATIO FROM THE PARENT TILL TO THE B HORIZON Soi l Horizon Ca/Al K/Al Na/Al S i / A l Fe/Al BW B 6.8 .507 .036 1.25 11.4 T i l l 21.3 1.0.1 .059 3.14 9.71 % Change -68.1 -50.0 -39.0 -60.2 +17.4 GW B 6.0 .415 .033 .758 7.68 T i l l 13.9 .812 .037 1.86 6.05 % Change -56.8 -56.8 -10.8 -59.2 +26.9 leaching. The iron to aluminum ra t io is the only ra t io to exh ib i t an increase for the basal t -der ived and in t rus ive-der ived t i l l s o i l s , 17.4 and 26.9 percent respect ive ly . It would appear, therefore, that the B horizon of the Vancouver Island podzols experiences large losses of bases and s i l i c a and s ign i f i can t increases in i ron re la t i ve to aluminum. Losses of bases and s i l i c a in the B can be at t r ibuted to the i r physical removal from the so i l system. It does not necessar i ly fo l low that the increase in i ron resul ts from d iscrete addit ions to the B„ since the. Ae. hor izon, the most log ica l source, is absent in many, of these s o i l s . Rather, the increase in i ron represents a re la t i ve increase, brought about by the loss of the other const i tuents. In other words, th i s could be considered as negative or residual enrichment. S i m i l a r l y , although the ra t ios assume that the absolute content of aluminum has not changed great ly , the 67 re la t i ve content has no doubt increased by v i r tue of the losses of bases and s i l i c a . Geochemical ( ion ic) balance determined for two small West Coast watersheds i nd i rec t l y corroborates these trends of absolute loss and re la t i ve gain of cer ta in minerals. Zeman (1973) monitored inputs and outputs from the Jamieson Creek basin of Greater Vancouver's Seymour watershed during 1970-71. The basin i s characterized by podzol s o i l s very s im i la r in nature to those of the Vancouver Island model, although, wi th in the Jamieson Creek.basin, there i s a greater range of e leva t ion , s o i l drainage and so i l depth. 1 A pa ra l l e l study by Fredriksen (1972) in Oregon y ie lds strong corroboration for that of Zeman. Table 1-17 shows inputs, outputs, and the balance or net change for a.range of ions as measured in the Jamieson Creek Study. Large net losses from the watershed of the bases, espec ia l l y calcium and sodium; s i l i c a ; and the anions, bicarbonate and ch lo r ide , are evident. Zeman determined that tropospheric f a l l ou t provides most of the n i t r a t e , ammonium, su l fa te and ch lor ide but t e r r e s t r i a l sources provide the bulk of t h e - s i l i c a , calc ium, magnesium, potassium and bicarbonate found in discharge waters. Phosphate and sodium derived equally from tropospheric and t e r r e s t r i a l sources (Zeman, 1973). The t e r r e s t r i a l sources of ions po ten t ia l l y include changes in the biomass, release from decomposing organic materials and weathering from geologic mater ials and s o i l s . In small basin s tud ies , such as Jamieson Creek, the assumption i s often made that the net annual change ^From unpublished so i l survey information by T. Lewis and H. Luttmerding, So i l Survey D i v i s i o n , Kelowna, B .C . , 1969. 68 TABLE 1-17 THE ANNUAL IONIC GEOCHEMICAL JAMIESON CREEK WATERSHED, WATER BALANCE OF YEAR 1970-71 Input (prec ip i ta t ion &. dust) Output (streamwater) Balance Precip. , discharge 4,541 3,668 873 Ca 7.25 41.66 -34.41 Mg 2.21 8.82 -6.61 K 0.86 2.56 . -1.70 Na 13.17 25.61 -12.44 S i 0 2 0.75 92.06 -91.26 NH4 0.57 0.54 0.03 N03 1.13 0.82 0.31 HC03 7.55 37.24 -29.77 so4 6.70 9.04 -2.34 P O 4 0.40 0.73 -0.33 Cl 23.11 38.06 -14.95 Prec ip i ta t ion and stream discharge are in mm. Ionic balances are in kg/ha-yr. Source: Zeman (1973) in standing biomass and dead organic mater ia ls , pr imar i ly the forest f l o o r , is small in climax communities (Borman and L ikens, 1971). If th i s i s t rue, then weathering is indicated as the prime source of the bulk of the ions carr ied in discharge waters. Proposed Genesis of the  Vancouver Island Model The ear ly stages of genesis of the Vancouver Island podzols were probably comparable to those of the s o i l s studied by Crocker and 69 Major (1955) and Ugol in i (1968).in the Glac ier Bay area of southeastern Alaska. Both groups of s o i l s developed on g lac ia l t i l l under the inf luence of moderate and wet c l imates, dominated by P a c i f i c maritime a i r masses. At Gustavus near the mouth of Glac ier Bay, a mean annual temperature of 5°C and a mean annual p rec ip i ta t ion of 1376 mi l l imetres have been recorded, over a 29-year period (Ugo l in i , 1968). Summer r a i n f a l l i s h igh; 170 mi l l imetres was recorded between June 15th and Ju ly 31st, 1965 {op. ait.). Ugol in i describes the genesis of the f i r s t 150 years of the Glac ier Bay s o i l s as fo l lows: Fresh deposited g lac ia l t i l l i s immediately attacked by a number of processes - carbonates are depleted and cryopedo-log ica l processes a t ta in the i r maximum. As plants are es tab l ished, organic matter enters the mineral so i l s and a s u r f i c i a l Al horizon is formed. So i l . pH decreases and cat ion exchange capacity increases. The addit ion of more plants resu l ts f i r s t i n a th in layer (01 horizon) and then a humified layer (02 hor izon). Af ter about 55 years, an inc ip ien t B horizon has appeared. The pH continues to decrease and exchangeable ac id i t y to increase un t i l exchange-able bases are considerably depleted. One hundred f i f t y years a f te r deg lac ia t ion , the A2 horizon f i r s t appears. Forest f l oo r thickness increases from 2 at 12 years to 20 centimetres a f ter 150 years. The C/N ra t io has also increased. . . . (Ugo l in i , 1968). At 250 years Ugolini notes that a S i tka spruce-hemlock forest i s establ ished and the forest f l oo r of LFH is 20 centimetres th ick and carpeted with a th ick moss layer . The solum is comprised of a f i ve centimetre Ae and a ten centimetre B horizon. In the 250-year old Glac ier Bay."podzols", . the group of s o i l propert ies that are usual ly associated with revers ib le processes are quite comparable with those of both the c l a s s i c a l and Vancouver Island models. Mor forest f l o o r s , low pH and base satura t ion, high carbon-nitrogen ra t ios and high 70 exchangeable ac id i ty , are already well expressed. Crocker and Major observed that , under a lder , "the react ion.of uppermost horizons of the g lac ia l t i l l i s reduced from pH 8.0 to less than pH 5.0 wi th in 35 to 50 years. During the same per iod, calcium carbonate. in. the f i ne earth i s reduced from i n i t i a l values of the order of f i ve percent to neg l ig ib le quant i t ies" (Crocker and Major, 1955,).. At the 250-year stage, however, the strength of expression of the B horizon i s lacking and in th is respect, the Glac ier Bay "podzols" deviate great ly from the Vancouver Island model. The Glac ier Bay B hor izon, at th is stage, contains only 1.63 percent free iron oxides (Ki lmer, 1960) over a ten centimetre depth, compared to 0.47 percent in the C horizon. Such deviat ion i s expla inable, however, as the weathering of i ron and aluminum in 250 years under, a s im i la r b ioc l imat ic system cannot be expected to compare with that weathered in the TO,000-year old Vancouver Island podzols. Although great ly reduced, the B of the 250-year "podzol" s t i l l contains measurable amounts of carbonates. It is suggested that , once th is i n i t i a l rapid adjustment of the s o i l to cl imate and biota has taken p lace, so i l development involves the gradual ampl i f i ca t ion of the group of propert ies which are determined by pedological ly i r r eve rs ib l e processes. For example, with time i t i s expected that oxalate-and c i t ra te -d i t h ion i te -ex t rac tab le i ron and aluminum w i l l s tead i ly increase as they are released from the primary minerals by i n - s i t u weathering. Concomittantly, bases and s i l i c a w i l l be s tead i ly l os t to drainage waters. A basic point of issue remains unexplained - the ubiquitous nature of the Ae in c l ass i ca l podzols versus the usual absence of Ae's 71 in the Vancouver Island model. It i s suggested that the. answer l i e s not in divergence of soi l - forming processes but in divergence of parent mater ia ls . Two s o i l s wi th in the study area, namely GD and GW, serve to i l l u s t r a t e th is theory. Both are developed from t i l l s derived from predominantly coarse-grained in t rus ive rocks. The in t rus ives on the dry east side of Vancouver Island are r e l a t i v e l y acid granodior i tes; on the wet western s ide , more basic d i o r i t e s . The in terest ing observation i s that the dry subzone s o i l (GD) has the best expressed Ae horizon and yet the weakest Bf hor izon, weakest in terms of i t s content of sesquioxides. The wet subzone so i l (GW), on the other hand, has no Ae horizon whatsoever but has one of the strongest Bf horizons of a l l s o i l s studied. A more careful examination of the parent material of both these s o i l s reveals that the granod ior i t i c t i l l (GD) contains considerable coarse-grained quartz and that i t s to ta l content of i ron i s low. The d i o r i t i c t i l l (GW), however, contains v i r t u a l l y no quartz and i t s i ron content is r e l a t i v e l y high. It should be noted here that the s o i l s developed from the basa l t i c t i l l s , (BD and BW), also have no Ae horizons. It has already been observed in a number of studies that the amount of i ron mobi l izat ion or movement i s inversely proportional to the amount of i ron that i s ava i lab le for movement (Bloomfield, 1953; Deb, 1950; Kawaguchi and Matsuo, I960).. This is the opposite re la t ionsh ip to that expected i f dealing with an ion ic system. It would indicate therefore, that a predominantly nonTionic mechanism is involved in i ron 72 mobi l izat ion and transport. Such an inverse re la t ionship could be expected i f the mechanism involved complex formation, since increasing metal loadings on organic l igands resu l ts in the i r eventual i n so l ub i l i za t i on (Schnitzer and Skinner, 1963a). In e f fec t , th is means the more iron ava i l ab le , that i s , weathered out; the more rapid ly the organic l igands w i l l become insoluble due to metal loadings. In low- i ron , quar tz- r ich mater ia ls , i n so l ub i l i za t i on w i l l not take place for a considerable depth - the minimum depth equal l ing the lower boundary of the Ae - because of the re la t i ve paucity of ava i lab le i ron . The typ ica l Ae- less Vancouver Island podzols, however, develop in mater ia ls that are r icher in i ron and poorer in coarse quartz. Inso lub i l i za t ion of a complex by metal loading w i l l thus take place r e l a t i v e l y qu ick ly ; in f ac t , a proportion of the complexes w i l l even be immobilized r ight at the mineral so i l surface. The development of an Ae i s thereby retarded, even prevented, not only because of the lack of coarse quartz but also because of the i n a b i l i t y of a l l the weathered i ron to.be moved out of the surface s o i l . As a ru le , then, in an equivalent environment, Ae/B podzols w i l l always have poorer B horizons than Ae-less podzols. On Vancouver Is land, in both wet and dry subzones the s o i l s with the strongest Ae's exhib i t the least sesquioxidic B horizons. Ponomareva (1969) describes somewhat s im i la r s o i l s in the U.S.S.R. and has proposed the name, . "cryptopodzol ic" , to indicate that these "hidden podzols" have no Ae horizons. She notes that , "many scholars bel ieve that such s o i l s cannot a r i se under ta iga.vegetat ion but only by man's a c t i v i t y , developing on former plowland. . ." 73 (Ponomareva, 1969). Ponomareva presents evidence to the contrary, and maintains that the cryptopodzols are of natural occurrence, developing from, "parent rock that i s more or less r i ch (by mineralogical composit ion)." Under such condi t ions, podzol izat ion in the Russian sense, that i s , Ae formation, f a i l s because of the richness of the parent rock in read i l y weatherable forms of iron and aluminum. As a r e s u l t , "the decrease from top to bottom of calc ium, considered as an agency of humus f i x i n g , happens to be compensated immediately by an increase in mobile i r on ; the decrease (with depth) of i ron i s s i m i l a r l y compensated by an increase of mobile aluminum." Note that , in th is biochemical treatment of podzo l iza t ion , the emphasis i s on the mobi l i ty of organic matter rather than the mobi l i ty of sesquioxides. From ei ther point of view, i t i s the s o l u b i l i t y of the complex that i s of concern, and Schnitzer and Skinner 's (1963a) f indings that increased metal loadings resu l t in i n s o l u b i l i z a t i o n supports Ponomareva's hypothesis. Despite the points of s i m i l a r i t y , the Ae- less cryptopodzols of the taiga zone in northern U.S.S.R. s i g n i f i c a n t l y d i f f e r from the Ae- less podzols of Vancouver Island in. the strength of the B horizon. In the cryptopodzol, the increase in to ta l i ron and aluminum in the B over the C i s 2.4 and 0.2 percent, respect ive ly . Weathering has apparently been retarded in the taiga s o i l s by the colder, d r i e r c l imate. In a watershed dominated by s o i l s having B .horizons comparable to the typ ica l Vancouver Island model, Zeman (.1973) recorded large losses of s i l i c a and bases. These s o i l s , however, were over la in by discontinuous s i l i ceous Ae's up to three inches th ick . I n i t i a l l y , th is 74 appears somewhat contradictory in that , on the one hand, s i l i c a is being los t in great quant i t ies to groundwater and ul t imately streamwaters but, on the other hand, i t i s being concentrated in the Ae horizon. In order to explain th i s apparent cont rad ic t ion , the diehotomous nature of the s i l i c o n of so i l minerals must be considered. The s o l u b i l i t y of the s i l i c a of s i l i c a t e minerals released by weathering i s s l i g h t l y greater than two milTimol.es per l i t r e between pH 3.0 and 6.0 (Loughnan, 1969). The s i l i c a of quartz, on the contrary, has a s o l u b i l i t y approximately one-tenth that of the amorphous s i l i c a released from s i l i c a t e s (Krauskopf, 1959). Hence, the s i l i c a leached from the s o i l has a predominantly s i l i c a t e o r i g i n , such as the feldspars and mafic minerals, while the s i l i c a that enriches surface s o i l horizons i s dominantly quartz. As a r u l e , the strongest Ae horizons do not develop on the heterogeneous t i l l s but rather on the we l l - so r ted , coarse, s i l i ceous sands, where the content of bases, i ron and even s i l i c a t e s i s r e l a t i v e l y low. In Boreal c l imates, Ae horizons of up to 20 centimetres are found on such mater ia ls ; the B horizons of these s o i l s , however, are not correspondingly strong or th ick . In hot and wet Tropical c l imates, Ae's of several metres in thickness occur (Eyk, 1957). In Ae- less podzols, then, accumulation of sesquioxides in the B horizon i s accomplished through negative or residual enrichment, since the losses of bases and s i l i c a occur more rap id ly than the losses of aluminum and i ron . Redist r ibut ion of i ron and aluminum.by the t rans-locat ion of soluble organo-metal l ic complexes is res t r i c ted because these complexes tend to. become quick ly overloaded and thereby 75 i nso lub i l i zed . This negative enrichment takes place to varying degrees in a l l podzols, in fact in a l l s o i l s with free through drainage, including many brunisols and regosols of.-the wetter c l imates. In the c l ass i ca l podzol, however, the processes leading to negative enrichment of the B horizon are overshadowed by the more s t r i k i ng pos i t ive enrichment of the B, which occurs by v i r tue of t ranslocat ion of sesquioxides from the Ae to the B. It i s not suggested, therefore, that a new concept of genesis replace the old but rather that the c l a s s i c a l should be broadened somewhat to explain the considerable range of s o i l s that we presently c a l l podzols. It i s proposed that podzols resu l t from a combination of three groups of so i l forming processes: 1. i n - s i t u weathering of both the parent geological mater ials and the solum, 2. horizonation trends involving the red is t r ibu t ion of various const i tuents , notably i r on , aluminum and organic matter wi th in the solum, 3. ant i -hor izonat ion as a resu l t of pedoturbation by b io ta , slope processes and b iocyc l ing . The re la t i ve strengths of these three general trends leads to the formation of the var iab le assemblage of s o i l s ca l led podzols. The " c l a s s i c a l " model of podzols results>when horizonation trends predominate, whereas the Vancouver Island model, resu l ts when i n - s i t u weathering dominates. C lass i fy ing both the c l a s s i c a l and Ae-less podzols as members of the podzol order appears j u s t i f i e d since the presence or absence of an Ae appears more dependent on materials dif ferences than on di f ferences in the so i l forming processes. Summary and Conclusions Eight non-1 i th ic , moderately well drained, t i l l - d e r i v e d podzols in the dry and wet subzones of the Coastal Western Hemlock biogeocl imatic zone were characterized in order to explore the genesis of the Vancouver Island model of podzols. In comparison to the dry subzone, podzols of the wet subzone have greater accumulations of organic matter, both as mor surface horizons and wi th in the B hor izon; higher contents of n i t rogen; greater cat ion exchange capaci ty , pa r t i cu la r l y the pH-dependent.component; and much greater contents of extractable sesquioxides. On the other hand, ava i lab le phosphorus, base saturat ion and exchangeable calcium are higher in the dry subzone. The e f fec t of parent material composition, the l i tho logy of the t i l l , pers is ts in the B horizon in varying degrees. As a r u l e , the impact of t i l l l i tho logy on the resu l t ing B horizon i s less apparent in the wet subzone podzols than in the dry. Ae horizons form when the parent material contains su f f i c i en t res is tan t quartz. When quartz is lacking in the parent rock, as is most common on Vancouver Is land, the Ae horizon is absent. The typ ica l Vancouver Island podzol i s characterized by a mor type surface organic horizon that d i r e c t l y over l ies a th ick , br ight-colored B hor izon, great ly enriched wi th sesquioxides and organic matter. Where Ae's occur, they are th in and discontinuous. In contrast , the c l a s s i c a l podzol requires the presence of an 77 Ae; the c l ass i ca l B horizon i s weaker both in terms of i t s concentration of sesquioxides and i t s thickness. The Vancouver Island podzols and c l a s s i c a l podzols, though, have much in common in regard to the edaphic proper t ies, most relevant to and most influenced by vegetation. Chronosequences studied elsewhere indicate that th is group of so i l propert ies adjust to the preva i l ing b ioc l imat ic regime wi th in a few centur ies. C lass i ca l concepts of.podzol genesis are t rans locat ion-or iented; the Ae and B horizons are seen to be int imately re la ted. The mobi l izat ion and movement of sesquioxides involve a combination of d isso lu t ion of f e r r i c and ferrous iron and the formation of soluble metal lo-organic complexes. Immobilization in . the B apparently resul ts from both the decomposition of the organic l igands and the p rec ip i ta t ion of the metal lo-organic complexes by overloading of the complex with sesquioxides. Translocat ion of organic matter i s by means of suspension in percolat ing waters; immobil ization resu l ts from the s ieving act ion of the B horizon. For Ae- less podzols, i t has long been assumed that the Ae i s absent because of some physical disturbance. Observations of the Vancouver Island podzols preclude th is explanation. Rather, i t i s suggested that the strong B horizons of the Vancouver Island model develop without the par t i c ipa t ion of an Ae horizon. In-s i tu weathering, which involves great losses of bases and s i l i c a to drainage waters, leads to the negative enrichment, of the.residual material in the B horizon with i ron and aluminum. The presence of Ae horizons in some Vancouver Island podzols i s a function of parent material rather than 78 di f ferences in s o i l forming processes. Since s i l i ceous mater ia ls tend to be iron-poor, in a given b ioc l imat ic system, i t i s expected that Ae/B podzols w i l l have weaker B horizons than the Ae-less podzols. It i s suggested that the prevai l ing concept of podzol genesis, which centres on the development of the Ae/B sequence, be broadened to more ra t i ona l l y encompass both c l a s s i c a l and Vancouver Island models. This broadened concept would recognize three groups of so i l forming processes: a) horizonation trends involving the red is t r ibu t ion of various const i tuents , notably organic matter and sesquioxides, wi th in the solum, b) un id i rect ional trends involving i n - s i t u weathering of the parent geologic materials and the solum, resu l t ing in losses to drainage waters of bases and s i l i c a , and negative or residual enrichment of sesquioxides in the solum, and c) ant i -hor izonat ion that resu l ts from both turbat ion of the solum by windthrown trees and slope processes, and biocycl ing by vegetat ion. It i s suggested that these three groups of processes are act ive in a l l podzols, and to some extent, in many other s o i l s . Di f ferent kinds of podzols resu l t from the re la t i ve strengths or weaknesses of these three groups of processes. In the c l ass i ca l model of podzols, the horizonation trends predominate, although undoubtedly weathering plays an important ro le in making various consti tuents ava i lab le for red i s t r i bu t i on . In the Vancouver Island model, on the other hand, the un id i rect ional weathering trend dominates; horizonation is poorly expressed and ant i -hor izonat ion i s strong. 79 The in tens i ty of weathering in the Vancouver Island model, as in a l l s o i l s , i s contro l led large ly by cl imate and l i t ho logy ; the strongest expression of weathering i s observed,in the wet subzone on weatherable limestone t i l l mater ia ls ; the weakest expression, in the dry subzone on r e l a t i v e l y res is tant granod ior i t i c t i l l mater ia ls . C l a s s i f i c a t i o n of both the Vancouver Island and c l ass i ca l models as podzols i s j u s t i f i e d because the processes involved in the i r formation are essen t ia l l y s im i l a r . The fact that the edaphic propert ies of the two models are general ly shared would also support s imi la r c l a s s i f i c a t i o n of the two models from an ecological point of view. The dependence of Ae formation upon parent material character is -t i c s as opposed to a par t i cu la r process should be deal t with at a c l a s s i f i c a t i o n level below the great group or subgroup, possibly at the family or ser ies l e v e l , as i s done with other more obvious parent material d i f ferences. The recent demise of the "min i " subgroup of podzols in the Canadian System of Soi l C l a s s i f i c a t i o n (Canada Soi l Survey Committee, 1974) i s supported by the resu l ts of th is study. The great strength of the Vancouver Island podzol B horizons should not be referred to as "mini" because of the absence of or the presence of only a th in Ae horizon. If mini i s to be applied at a l l i t i s suggested that the term "mini l a t e r i t e " would be more appropriate. CHAPTER II THE NUTRIENT STATUS OF THE SOILS Introduction In the evaluation of the nutr ient status of agr icu l tu ra l s o i l s , in terpretat ion i s commonly based d i r e c t l y on data concerning the concentration of nutr ients in the less than two mi l l imetre so i l f rac t i on . This i s l i k e l y su f f i c i en t for most pract ica l purposes since the range of the physical var iables of agr icu l tu ra l s o i l s that a f fect nutr ient s ta tus; that i s , gravel and stone content, bulk density and ef fec t ive so i l depth, is r e l a t i v e l y r es t r i c t ed . In forest s o i l s , the relevant range of these physical var iables becomes many times greater. For example, whereas the stone content of agr icu l tu ra l s o i l s is usual ly low, the stone content of forested s o i l s i s frequently above f i f t y percent. S i m i l a r l y , while the e f fec t ive so i l depth for annual agr icu l tu ra l crops is large ly determined by the nature of the crop, the e f fec t ive depth of forest s o i l s i s often defined by the occurrence of r es t r i c t i ng layers , such as rock or cemented so i l horizons. The r e l a t i ve l y greater s ign i f icance of var ia t ion in basic physical propert ies of forest so i l s i s the ra t iona le , in th is study, for assessing nutr ient status on an areal basis (that i s kg/ha), which integrates chemical and physical data, rather than on the basis of nutr ient concentration in the two mi l l imetre f rac t i on . 80 81 Prel iminary f i e l d observations indicated that var ia t ion wi thin pedons and polypedons of Vancouver Island podzols i s s i g n i f i c a n t , largely because of the extensive pedoturbation that the s o i l s undergo during formation. Consequently, a mul t ip le sampling technique and subsequent production of composite samples for analysis was devised so as to encompass the expected range of va r ia t i on . Methods Experimental Design A design was u t i l i z e d that allowed for the evaluation of the ef fect of c l imate, geology and between plot var ia t ion on s o i l propert ies. Where poss ib le , f i ve plots were sampled for each cl imate-geology combination, except in the limestone and sch is t t i l l s , which were not found in the dry subzone. The number of plots for each of the remaining eight s o i l s i s shown, in Table 2-1. TABLE 2-1 THE EXPERIMENTAL DESIGN Climate Geology: Andesites Basalt Gran i t i c Limestone Schist Dry 5 AD 4 BD 5 GD Wet 1 AW 5 BW 3 GW 5 LW 5 SW Number of Plots F ie ld Sampling Methods Sampling of each of the s o i l s for assessment of nutr ient status f i r s t involved the locat ion on the ground of an area of so i l wi th in 82 which var ia t ion was wi th in the l im i t s of a polypedon. A point was a r b i t r a r i l y located within th is area to serve as the centre of a 0.04 hectare (1/10 acre) c i r c u l a r . p l o t . Four, random azimuths were determined using random number tab les. Four points at 2.75 metre (9 foot) in terva ls outward from the p lo t centre along the four azimuths were then located (see Figure 2-1). At each of these 16 points a s o i l p i t was excavated down to the basal t i l l contact, usual ly the top of the BCd horizon. Further excavation into and sampling of the t i l l was considered unnecessary since only a few anchor roots penetrate th is tough, massive mater ia l . At each p i t , the e f fec t ive so i l depth was measured from mineral surface to the basal t i l l contact or BCd horizon. Three s o i l samples were taken from each of the sixteen p i t s , one from the LFH, one from the upper 45 centimetres of the B hor izon, and one from the lower B horizon. Two composite samples, each comprised of eight ind iv idual samples, were derived for each of these three horizons (See Figure 2-1). The f ie ld -mois t weight of the composite samples of the mineral horizons was general ly between 12 and 15 k i l o s . These samples were sieved in the f i e l d to determine the percentage of fragments over two centimetres and a subsample of two to four k i l os (a i r dry) was taken of the less than two centimetre f r ac t i on , for further physical and chemical analys is in the laboratory. F ie ld moisture content was determined gravimetr. ical ly in order to bring the coarse fragment content to an oven dry (105°G) bas is . Bulk density was determined i n : t he .p lo t for r e l a t i v e l y large samples of upper and lower B combined. At each p lo t , two bulk density samples ranging from 15 to 25 l i t r e s in volume were assessed. Such a FIGURE 2-1. SAMPLING METHODS M O D A L PIT METHOD vs PLOT M E T H O D cm 84 large sample hopeful ly encompasses and averages most of the var ia t ion in bulk density over small d istances. E a r l i e r work with s im i la r s o i l s indicated that the large var ia t ion among standard three inch cores wi thin one horizon of one pedon required many core samples to derive reasonable mean values (Lewis, 1968). Furthermore, and perhaps more important, the small core technique introduces a bias towards the f iner so i l f ract ions and undersamples the coarse fragments. This aspect rendered the use of small cores inappropriate for th is study. The method employed involved f i r s t the preparation of a plane surface on the mineral s o i l . A so i l p i t was then excavated through the B horizon. A l l material was saved from the p i t , weighed, the coarse fragment content (over two centimetres) determined, and moisture samples taken for oven drying and subsequent correct ion of a l l weights to an oven dry bas is . A p las t i c sheet was placed in the p i t and a measured volume of water poured into the p i t up to the or ig ina l so i l surface. This volume of water equals the volume of so i l removed and th is volume is subsequently used in ca lcu la t ing the bulk density for the whole s o i l . Laboratory Methods The a i r - d r y , two to four k i l o , composite mineral samples were sieved to determine the so i l f rac t ion, comprised of the twomi l l imet re to two centimetre f r ac t i on . Moisture samples were taken to bring th is percentage to an oven-dry bas is . The LFH composite samples were ground in a Wiley m i l l . Chemical analys is of the two mi l l imetre f rac t ion included pH of mineral samples in both a 1:2 soi l :0 .01M C a C ^ suspension and in a 1:1 so i l :water suspension. pH of organic samples was deter-85 mined in 1:8 soi1:0.01M CaCl^ and 1:4 so i l :water suspensions. Total carbon was determined by induction furnace techniques (A l l i son et al. , 1965); to ta l nitrogen for both mineral and LFH samples, by the semi-micro Kjeldahl method (Bremner, 1965); and total su l fu r for mineral and LFH, by induction furnace techniques (Leco, 1954). Avai lab le phosphorus of both mineral and organic samples was estimated by Bray's 0.03N NH4F - 0.025N HC1 extract ion . (01 son and Dean, 1965). The exchangeable cat ions in the mineral samples were determined by atomic absorption spectrophotometry af ter displacement by neut ra l , normal NH^OAc. Ava i lab le copper and zinc in the mineral samples were estimated by extract ion with O.TN HOI ( F i s k e l l , 1965); ava i lab le i ron and manganese in the mineral samples, by extract ion with IN NH^ OAc at pH 4.8 (Olson, 1965). The to ta l content of the cat ions, copper, z i n c , i ron and manganese in the LFH samples was determined by atomic absorption a f ter dry ashing and d isso lu t ion with HC1 (Chapman and Pra t t , 1961). Data Analysis Integration of physical and chemical data involves the conversion of nutr ient values of concentration in the two mi l l imetre f rac t ion to values of kilograms per hectare for the whole s o i l . The fol lowing equation accomplishes th is conversion for nutr ient "n" in the mineral samples -N = n • DIL B • d - T O 8 • 1/10 3 2 kgN _ g of n . # g of so i l < 2mm # g so i l % cm t cm # kg so i l ha g of so i l < 2mm " g of whole so i l " 3 . , " ha " g so i l 86 where: N is the amount of nutr ient "n" on an area! bas is , n i s the concentration of nutr ient "n" in the 2mm f r ac t i on , DIL i s the proportion of the 2mm f rac t ion to the whole s o i l , inc lus ive of gravel and stones, B is bulk density of the whole s o i l , and d i s the e f fec t ive s o i l depth. "DIL" refers to the d i l u t i on e f fec t that gravel and stone content has on the e f fec t i ve s o i l volume. Bulk densi ty is that of the whole s o i l in that i t s measurement includes whatever gravel and stones are present in the s o i l , although admittedly very large stones and, boulders were not included. For organic samples, a pa ra l l e l equation was appl ied. The factor "DIL" became 1.0, since neg l ig ib le amounts of gravel or stones 3 were present in the LFH horizons. A value of 0.15 g/cm was used for bulk density (Plamondon, 1972). Plamondon's value of 0.15 g/cc represents an average of 240 observations made on an area having general ly s imi la r organic horizons to those of the study area. S t a t i s t i c a l analysis involved two methods of analys is of variance. A two-way analys is of variance with in teract ion was performed on the andes i t i c , basa l t i c and g ran i t i c so i l s of both c l imat ic subzones as fo l lows: Source 87 Degrees of freedom Sum of squares Mean square F Climate 1 Geology 2 Climate x Geology 2 Plot (Error) 24 TOTAL 29 Because some s o i l s were represented by less than f i ve plots and the design was therefore incomplete, analysis was carr ied out by the U.B.C. -B.M.D. 10V program of the U.B.C. Computing Centre (Bjerr ing et al. , 1975), which compensates for missing observations and evaluates s ign i f i cance with F tests having somewhat lower degrees of freedom than for the complete design. Duncan's mul t ip le range test at the f i ve percent level was also computed by .U.B.C. - B.M.D. 10V. In order to explore the e f fec t of geology within a c l imat ic subzone, one-way analysis of variance was carr ied out separately for the f i ve wet subzone s o i l s and for the three dry subzone s o i l s . The fo l lowing i s the design for the wet subzone s o i l s : Source Degrees of freedom Sum of squares Mean square F Geology 4 - -P lot (Error) 20 TOTAL 24 U.B.C. - B.M.D. 10V was also used for these two analyses of variance and for Duncan's mul t ip le range tes ts . 88 Results and Discussion A complete data summary for a l l 33 of the nutr ient plots i s presented in Appendix 2-1. Table 2-2 indicates the considerable range of nutr ient values found in the various horizons of the s o i l s . In the B horizons, the range in values commonly involves two orders of magnitude; for phosphorus and calc ium, a spread of four orders of magnitude. In the LFH, the range commonly encompasses two orders of magnitude. Such large ranges of values undoubtedly have nu t r i t iona l s ign i f i cance to plant communities. Is th is var ia t ion related to the so i l forming factors of cl imate and. geology? Or, to what extent i s th is an ind icat ion of the great spat ia l v a r i a b i l i t y wi th in these s o i l ind iv idua ls? These and other re lated questions are discussed in the second and th i rd chapters of th is d i sse r ta t i on . The S ign i f icance of  Climate and Geology In the LFH Horizon Two-way analys is of variance with in te rac t ion , which was carr ied out to assess the s ign i f i cance of c l imate, geology and the climate-geology in te rac t ion , is presented in Table 2-3. The geology factor and the climate-geology in teract ion are not s i gn i f i can t . The ef fect of cl imate on the to ta l amount.of organic matter wi thin s u r f i c i a l LFH horizons, however, i s highly s i gn i f i can t . In.the dry subzone, the mean and standard deviat ion for organic matter is 235,000±. 146,000 kilograms per hectare from 14 observat ions; in the wet subzone, 676,000± 302,000 kilograms per hectare from 9 observations. The highly s ign i f i can t e f fect of the c l ima t i c factor on organic 89 TABLE 2-2 THE RANGE OF NUTRIENT VALUES MEASURED LFH Upper B Lower B Mineral So i l Variable . Icn/hfl O.M. high 1,190,000 483,000 262,000 745,000 low 40,400 48,600 0.0 76,300 N high 13,900 10,600 6,360 16,900 low 281 938 0.0 1,580 P high 42 107 204 311 low 1 0.19 0.0 0.19 S high 1,340 1,480 1,120 . 2,450 low 24 90.3 0.0 167 Ca high 2,460 2,600 3,320 5,820 low 155 0.0 0.0 1.74 Mg high 1,290 218 135 327 low 32 25.1 0.0 35.3 K high 473 269 272 541 low 32 25.7 0.0 25.7 Na high 112 162 77.6 199 low 3 11.6 0.0 18.5 Cu high 14 7.85 6.51 12.4 low <1 0.53 0.0 0.68 Zn high 37 15.5 24.9 33.6 low 1 1 .48 0.0 2.66 Fe high 4,050 845 287 1,140 low 128 93.0 0.0 117 Mn high 515 91.8 39.5 . 96.4 low 17 1.63 0.0 2.26 90 TABLE 2-3 THE RESULTS OF THE TWO-WAY ANOVA WITH INTERACTION FOR AD, AW, BD, BW, GD AND GW SOILS _ — Horizon Variable LFH Upper B Lower B Total B GROUP I Organic Matter c** GxC** GxC** GxC** Nitrogen GxC** GxC** GxC** Sul fur C * * , G * GxC** GxC*' GxC** Calcium C* GxC* GxC* GxC* Magnesium c** GxC** N.S. GxC* Potassium c** GxC** G* GxC* Sodi um c** GxC** GxC** GxC** GROUP II Phosphorus c* c* Q** C* Copper c** C * * , G * * c** C**,G Manganese N.S. c** c* Iron c* G* G** G** Aluminum c* GROUP III Zinc c* N.S. N.S. N.S. Factors: C - c l imate; G-geology; GxC - geology-climate in teract ion S ign i f i cance : * * - at one percent; * - at f i ve percent N.S. - not s ign i f i can t 91 matter content resul ts mainly from di f ferences in tota l depth of LFH in the two subzones. Var ia t ion in the percent organic matter in the mor type forest f l oo r is quite low; var ia t ion in bulk density was not assessed. The content of almost a l l the nutr ients contained in the LFH i s also s i g n i f i c a n t l y affected by the c l imat ic fac to r , because of the dominant ef fect of the to ta l amount of LFH. Concentration d i f fe rences, even i f s i g n i f i c a n t , are general ly overshadowed by the amount of LFH, except for manganese in the wet subzone s o i l s . Considerably lower manganese concentrations in the LFH e f fec t i ve l y o f fset the higher tota l amount of organic matter. Calcium, phosphorus, i ron and zinc concentration di f ferences between subzones reduce the s ign i f i cance of the c l imat ic ef fect from the one percent level to the f i ve percent l e v e l . The geologic factor i s only once marginal ly s i g n i f i c a n t , with respect to to ta l su l fu r . For the one-way analysis of variance for the wet subzone s o i l s , the resu l ts ind icate that geology i s frequently a s i gn i f i can t determinant of nutr ient contents in the LFH (See Table 2-4), In the dry subzone, geology is cons is tent ly i ns ign i f i can t (See Table 2-5). It i s conceivable that the a b i l i t y of the more highly weathered, lower base status wet subzone s o i l s to supply cer ta in nutr ients i s res t r i c ted at times so that the di f ferences among bedrocks become more apparent in the LFH. In the dry subzone s o i l s , higher base status resul ts in a greater a b i l i t y of the so i l to supply the needs of vegetation so that bedrock di f ferences are not evidenced in the LFH. 92 TABLE 2-4 THE RESULTS OF ONE-WAY ANOVA FOR THE WET SUBZONE SOILS - AW, BW, GW, LW AND SW Horizon Variable LFH Upper B Lower B Total B Organic Matter G** G** G* G* Nitrogen G* N.S. N.S. Sul fur G* G** G* Phosphorus N.S. N.S. N.S. N.S. Calcium Q** N.S. N.S. N.S. Magnesium N.S. G** N.S. G* Potassium G** G** G** G** Sodium G* G** G** G** Copper G* N.S. N.S. G* Zinc N.S. N.S. N.S. N.S. Iron N.S. G** G** G** Manganese G** N.S. N.S. N.S. Factors: C - c l imate; G - geology S ign i f i cance: * * - at one percent; * - at f i ve percent N.S. - not s i gn i f i can t 93 TABLE 2-5 THE RESULTS ON ONE-WAY ANOVA FOR THE DRY SUBZONE SOILS - AD, BD, AND GD Horizon Variable LFH Upper B Lower B Total B Organic Matter N.S. N.S. N.S. N.S. Nitrogen N.S. N.S. N.S. N.S. Sul fur N.S. N.S. N.S. N.S. Phosphorus N.S. N.S. N.S. N.S. Calcium N.S. G** N.S. G* Magnesium N.S. N.S. N.S. N.S. Potassium N.S. N.S. N.S. N.S. Sodium N.S. N.S. N.S. N.S. Copper N.S. G** N.S. Q** Zinc N.S. N.S. N.S. N.S. Iron N.S. N.S. G* N.S. Manganese N.S. N.S. N.S. N.S. Factors: C - c l imate; G - geology .S igni f icance: * * - at one percent; * N.S. - not s i gn i f i can t - at f i ve percent 94 In the B Horizon In the upper B horizons, for one group of va r iab les , namely organic matter, to ta l n i t rogen, tota l su l f u r , exchangeable calcium, magnesium, potassium and. sodium, the in teract ion between cl imate and geology i s usual ly s i gn i f i can t at the one percent level (See Table 2-3). This often drops somewhat in the lower B hor izon, however, espec ia l l y for exchangeable magnesium and potassium. For the to ta l B horizon the geology-climate in teract ion i s cons is tent ly s i gn i f i can t . Furthermore, for f i ve of the seven var iables in the f i r s t group, the leve ls of s ign i f i cance pa ra l l e l s those of the upper B, ind icat ing that di f ferences in the upper B horizon are r e l a t i v e l y more pronounced than those in the lower B horizon. Since the in teract ion factor i s s i g n i f i c a n t , no conclusions can be drawn from the cl imate and geology factors i nd i v i dua l l y . The physical meaning of the s ign i f i can t in terac t ion term i s open to in te rpre ta t ion , since the analys is of variance technique i s merely a mathematical procedure which par t i t ions the sum of squares into various components. It i s correct to say, though,.that the ef fect of the geology factor with respect to organic matter, tota l n i t rogen, to ta l su l fur and the exchangeable ca t ions , i s d i f fe rent in the two c l imat ic zones. Possib le reasons for th is include the d i f fe rent weathering regimes, d i f f e ren t i a l ef fects of geology, on organic matter accumulation and/or d iscrete di f ferences in geology not recognized ,i;n somewhat imperfect geologic groupings. The response of exchangeable potassium varies with depth. In the upper B horizon the geology-climate in teract ion i s s ign i f i can t for 95 potassium, whereas at depth, geology alone i s s i gn i f i can t at one percent. The fact that cl imate becomes more important in the upper B tends to re inforce the concept of genesis proposed ea r l i e r that B formation in the Vancouver. Island podzols i s dominated by weathering processes which tend to equalize inherent parent material di f ferences over time. Since weathering in tens i ty decreases with depth, one would expect the geologic factor to assert i t s e l f moreso. in the lower B. In the second group of va r iab les , which includes ava i lab le phosphorus, copper, iron and manganese, the geology and/or cl imate factors alone are cons is tent ly s i gn i f i can t . For both ava i lab le phosphorus and ava i lab le manganese, the cl imate f a c t o r . i s s i g n i f i c a n t ; geology i s not s i gn i f i can t . For phosphorus in the to ta l B hor izon, cl imate i s s i gn i f i can t at the f i ve percent l e v e l ; for manganese, at the one percent l e v e l . The general ly higher content of organic matter in the wet subzone s o i l s is probably responsible for the lower a v a i l a b i l i t y of manganese, because of i t s tendency to complex with organic matter (Heintze, 1957). Climate probably acts on phosphorus a v a i l a b i l i t y i nd i rec t l y by way of sesquioxides. The more sesquioxidic B horizons of the wet subzone s o i l s f i x more phosphorus than the B horizons of the dry subzone s o i l s , except for s o i l LW. Geology i s cons is tent ly a s ign i f i can t determinant of ava i lab le i ron throughout the B hor izon; cl imate i s not s i gn i f i can t ; This i s rather surpr is ing in view of the evidence presented ea r l i e r in Chapter I, which suggests that cl imate as well as geology, is an important factor in determining the extractable iron content of podzol B horizons. A review of Figures 1-3 to 1-5 however, confirms that geology 96 often overshadows c l imat ic ef fects in determining the content of oxalate - and c i t r a t e - d i t h i o n i t e - extractable i ron. For example, extractable i ron leve ls of the AD s o i l general ly exceed those of the GW s o i l . The fact that low-iron granod ior i t i c parent materials coincide with the dry subzone, while higher- i ron d i o r i t i c parent materials coincide with the wet subzone, fur ther obscures the ef fect of c l imate. The th i rd type of response i s evidenced by ava i lab le z i n c , which i s not s i g n i f i c a n t l y affected by ei ther the range of cl imate or geology factors encountered in th is study, e i ther i nd i v idua l l y or in combination. Results of the one-way analys is of variance, for the f i ve wet subzone s o i l s are presented in Table 2-4. Geology i s cons is tent ly a s i gn i f i can t determinant of organic matter, total, su l f u r , exchangeable potassium and sodium, and ava i lab le i ron throughout the B horizon of these s o i l s . However, geology is s i gn i f i can t only in the upper part of the B horizon with respect to tota l nitrogen and exchangeable magnesium. Geology does not s i g n i f i c a n t l y a f fec t ava i lab le phosphorus, exchangeable calcium, and ava i lab le copper, z inc and manganese. Table 2-5 summarizes the one-way analys is for the three dry subzone s o i l s . For. most va r iab les , the ef fect of geology i s quite d i f fe rent than in the wet subzone. Geology does not s i g n i f i c a n t l y inf luence organic matter content, to ta l su l fu r , exchangeable potassium, or exchangeable sodium. Also contrary to the wet subzone is the lack of s ign i f i cance of the geologic factor on tota l nitrogen and exchangeable magnesium. Unlike in the wet subzone, geology s i g n i f i c a n t l y af fects exchangeable calcium in the dry subzone. 97 These f indings strongly corroborate the two-way analysis of variance f ind ings , which indicated a s ign i f i can t climate-geology in teract ion for the above var iables that respond d i f f e ren t l y to geology in the two c l imat ic subzones. The true nature of the s ign i f i can t in teract ion becomes c lear by a considerat ion of the two one-way analyses of variance. It i s Tikely that the general s ign i f i cance of geology in the wet subzone versus i t s general ins ign i f i cance in the dry subzone is re lated to the d i f ferent ranges of the geologic factor under study in the two subzones. Perhaps ins ign i f i cance in the dry subzone resul ts from looking at only three geologic types, a l l t i l l s of igneous der iva t ion . S ign i f icance in the wet,subzone, on the contrary, resul ts from comparison of f i ve t i l l s ; three from igneous rocks, one from sedimentary rock and one from metamorphic rock. The importance of cl imate alone in determining the leve ls of ava i lab le phosphorus and manganese.is supported by the non-s ign i f icant e f fect of geology when separately analysed for the two c l imat ic subzones. As in the two-way analysis with in te rac t ion , i ron i s inf luenced by geology wi th in each of the c l imat ic subzones, although geology i s much more s i gn i f i can t in the wet subzone s o i l s . The highly s ign i f i can t ef fect of geology in the wet subzone i s no doubt strengthened by the inc lus ion of the iron-poor schistose t i l l s o i l s and the i ron - r i ch limestone t i l l s o i l s in the one-way analysis of variance. Geology s i g n i f i c a n t l y a f fects ava i lab le copper leve ls in the dry subzone s o i l s but i s not s i gn i f i can t for the wet subzone s o i l s . Zinc i s not s i g n i f i c a n t l y influenced by geology in e i ther the dry or the 98 wet subzone. Duncan's mul t ip le range test at the f i ve percent level was carr ied out to determine i f any log ica l grouping of the so i l s could be undertaken. The resu l ts for the B horizon propert ies where the climate-geology in teract ion i s s i gn i f i can t are presented in Table 2-6. Although i t i s obvious that groupings are apparent for a few var iab les , the groupings are general ly not constant. The best potent ial for grouping involves the s o i l s , AD, BD, and GD. However, even here, as indicated by the one-way analysis of these dry sub-zone s o i l s there are s ign i f i can t di f ferences with respect to exchangeable calcium and ava i lab le copper (Table 2-5). The potent ia l for grouping wi th in the wet subzone so i l s i s even l e s s . This can be expected considering resu l ts of the one-way ana lys i s , which indicated so many var iables to be s i g n i f i c a n t l y inf luenced by geology. Grouping might s t i l l be possib le i f the ef fects of geology on each of the so i l propert ies were p a r a l l e l . However, th is is not the case. For example, in Table 2-7, i t i s apparent that , although s o i l AW is general ly well separated from the other four s o i l s , i t i s homogeneous with SW with respect to exchangeable potassium, and homogeneous with GW, BW, and SW with respect to ava i lab le i ron. It becomes apparent, therefore, that no natural grouping encompassing a l l the propert ies i s f eas ib le . This f inding supports the o r ig ina l concept employed in d is t ingu ish ing the eight s o i l s . It also suggests that in so i l mapping pro jec ts , wherever the scale of mapping a l lows, these eight s o i l s should be iden t i f i ed and separated. Special purpose groupings, however, can be car r ied out e f fec t i ve ly with respect 99 TABLE 2-6 THE RESULTS OF DUNCAN'S MULTIPLE RANGE TEST FOR THE B HORIZONS WHERE THE GEOLOGY-CLIMATE INTERACTION IS SIGNIFICANT Organic Matter upper B AD GD BD GW BW AW lower B GD AD BW BD GW AW mineral GD AD BD BW GW AW Nitrogen upper B GD AD BD BW GW AW lower B GD BW AD BD GW AW mineral GD AD BD BW GW AW Sul fur Calcium Magnesium upper B GD AD BD BW GW AW lower B GD BW BD AD GW AW mineral GD AD BD BW GW AW upper B GW AD BW BD AW GD lower B GW BW AD BD AW GD mineral GW AD BW BD AW GD upper B GW AD GD BD BW AW lower B GW GD BD AD BW AW mineral GW GD AD BD BW AW TABLE 2-6, Continued TOO Potassium upper B lower B mineral Sodium upper B lower B mineral BW GW BD AD GD AW BW GW BD GD AD AW BW GW BD GD AD AW AD GD BW GW BD AW BW AD GD BW BD AW AD GD BW GW BD AW 101 TABLE 2-7 DUNCAN'S MULTIPLE RANGE. TEST APPLIED TO ONE-WAY ANALYSIS OF VARIANCE FOR WET SUBZONE SOILS Organic Matter LFH S L G A B upper B S G B L A lower B B G S L A to ta l B B S G L A Ni trogen LFH S G L A B upper B B S G L A Sul fur LFH S G L A B upper B B G L S A lower B B G L S A to ta l B B G L S A Magnesium upper B G S B L A to ta l B G S B . L A Calcium LFH S L G A B TABLE 2-7, Continued 102 Potassium LFH upper B lower B to ta l B Sodium LFH upper B lower B to ta l B Iron upper B lower B tota l B Manganese LFH Copper LFH S G L B A B G L A S B G L A S CQ G L A S S L B A B G S L A B G S L A B G S L A G B A S L B G A S^  L G B A S L S G B L A S G L A B 103 to one par t i cu la r property or even for a few propert ies. For example, i f one were planning a nitrogen f e r t i l i z a t i o n pro ject , i t would be desi rable to apply d i f fe ren t rates of nitrogen f e r t i l i z e r to three groups of s o i l s : AD, BD and GD; GW and BW; and AW alone. If exchangeable potassium was of concern, one should group the s o i l s as fo l lows: AD and AW; GD alone; and BW, GW and BD. For calc ium, one should group a l l the wet subzone s o i l s ; AD and BD together, and GD alone. Where the climate-geology in teract ion i s i n s i g n i f i c a n t , but cl imate alone i s s i g n i f i c a n t , the log ica l grouping for s ing le purpose appl icat ions can be made on th is bas is : AD, BD, GD; and AW, BW, GW, LW and SW. In a pa ra l l e l fash ion, where geology alone i s s i g n i f i c a n t , as with ava i lab le i r on , Duncan's test indicates that three groups are f eas ib l e : GD, GW, BD and BW; AD, AW and SW; and LW alone. Summary and Conclusions The assessment of both chemical and physical var iables makes possible the expression of nutr ient stocks on an a r e a l ; that i s , kilogram per hectare, bas is . The range in the various nutr ient stock values for the 33 plots studied commonly encompasses two orders of magnitude. For calcium and phosphorus in the B horizons, four orders of magnitude are encompassed. Analysis of variance shows that ,a considerable port ion of the ranges of various nutr ient stocks can be ascribed to the cl imate and geology fac to rs , e i ther alone or in combination. The remainder of the var ia t ion can be ascribed to spat ia l va r ia t ion and local s i t e 104 di f ferences among the 0.04 hectare p lo ts . Climate was found to be the key determinant of the amount of organic matter per hectare in the LFH. On the average, the wet subzone s o i l s had almost three times more LFH than the dry subzone s o i l s . S i m i l a r l y , the ni t rogen, su l fu r , phosphorus, calcium, magnesium, potassium, sodium, copper, z inc and i ron contents of the LFH were s i g n i f i c a n t l y affected by the c l ima t i c fac to r . The ef fect of geology was obscured by the imbalance in experimental design caused by the lack of limestone t i l l - and schistose t i l l - d e r i v e d s o i l s in the dry.subzone. As a resu l t of th is imbalance, the geologic factor tended to appear more s ign i f i can t in the wet subzone than in the dry subzone. This i s evidenced by the s ign i f i cance of geology in the one-way analysis of variance for the f i ve wet subzone so i l s versus the ins ign i f i cance of geology for the three dry subzone s o i l s . Appl icat ion of Duncan's Mu l t ip le Range Test indicates that no feas ib le grouping of the eight s o i l s i s possible that does not resu l t in the grouping of some propert ies that are s i g n i f i c a n t l y d i f fe ren t . The in tegr i t y of the o r ig ina l de f i n i t i on of the eight s o i l s i s thereby upheld. In mapping, research or management, therefore, the eight s o i l s should be recognized and treated d i f f e ren t l y wherever poss ib le . For special purpose app l i ca t ions , where one or a few s o i l propert ies are re levant , some grouping of the eight s o i l s may be undertaken. CHAPTER III VARIABILITY OF THE SOILS Introduction Choice of a sampling design involves a number of fac to rs , including the purpose of sampling, the prec is ion required and the resources ava i lab le to carry out the sampling program. In s o i l science, two major schemes are used. The modal p i t approach involves sampling one or more representat ive pedons for the purpose of character iz ing a so i l taxonomic or mapping uni t . The p i ts are selected and sampled a f ter a subject ive evaluation of v a r i a b i l i t y i s carr ied out for the survey or research area. The " f i e l d tes t ing" approach involves compositing a number of samples, general ly taken on a random or gr id pattern. This approach i s often used where reasonably precise estimates of the nutr ient status of an area are required for purposes of management, since the compositing of samples tends to encompass most of the range of var ia t ion of so i l propert ies. Choosing the optimum sampling method in forested, mountainous regions, such as Vancouver Is land, is made more d i f f i c u l t - because of the various pedoturbation mechanisms that p reva i l . These mixing processes tend to increase the random var ia t ions in morphology and s o i l propert ies wi th in both polypedons and indiv idual pedons. Concommitantly, systematic horizonation within many indiv idual pedons i s severely interrupted. 105 106 Since in terpretat ion of so i l data should i dea l l y be based on estimates of variance as well as on estimates of mean values, an attempt was made in the study to quant i ta t ive ly evaluate s o i l v a r i a b i l i t y . To date no other work has been carr ied out on the v a r i a b i l i t y of Vancouver Island s o i l s . The recent review by Beckett and Webster (1971) provides as a "rough rule of thumb", approximate median values of the coe f f i c ien ts of var ia t ion of ind iv idual topso i l samples randomly d is t r ibu ted within the landscape. For 0.01 hectare areas, these values are 35, 10 to 20, 10 to 40, 2.5 to 10 and 2.5 to 10 percent for ava i lab le potassium, phosphorus and calc ium, nitrogen and organic matter respect ive ly (Beckett and Webster, 1971). The authors a lso note that , as a r u l e , "even in the natural landscape, as much as hal f the coe f f i c i en t of var ia t ion present wi th in one hectare i s already present wi th in a few square metres" (Beckett and Webster, 1971). A comparison of nutr ient stock values in kilograms per hectare, derived using the nutr ient p lo t composite sampling method and the modal p i t sampling method i s presented. Through the use of the comparison tab le , the appropriateness of modal p i t sampling as a method for generating meaningful estimates of nutr ient stocks can be ascertained. Methods F ie ld Sampling The f i e l d sampling methods employed in th is study have been described in deta i l in Chapters I and I I . Figure 1-2 diagrammatically out l ines both the modal sampling method used for the genetic studies and the p lo t sampling method used for assessment of nutr ient status. In 107 each nut r i t ion p lo t , 16 p i ts were excavated to the t i l l parent material and samples of LFH, upper B and lower B horizons were taken. Rather than subsequently pooling a l l 16 samples to form one composite sample per hor izon, the samples were pooled into two composites of eight samples each, in order to make possib le the estimation of variance as well as mean. Laboratory Methods V a r i a b i l i t y was assessed for pH in 0.01M C a C l 2 , to ta l carbon, to ta l n i t rogen, tota l su l f u r , ava i lab le phosphorus, exchangeable calcium, magnesium, potassium and sodium, as well as for ava i lab le copper, z i n c , i r on , and manganese in the B horizons of the Vancouver Island podzols. Analy t ica l methods are those out l ined e a r l i e r in Chapter I I . Repl icate analyses were rout inely carr ied out in the laboratory to check the precis ion of the methods employed. The range of coe f f i c ien ts of var ia t ion ascr ibable to subsampling and analys is i s shown in Table 3-1. TABLE 3-1 THE OBSERVED RANGE OF VARIATION ASCRIBED TO SUBSAMPLING AND ANALYTICAL METHOD Range in Coef f ic ien t Subsample of Var ia t ion Size Variable (%) (g) PH 0 - 1 10.0 Total C 5 - 1 0 0.50 Total N 2 - 3 2.00 Avai lab le P 5 - 25 2.00 Exchangeable cations 2 - 1 0 10.0 Ava i lab le Cu, Zn, Fe, Mn 5 - 1 5 10.0 108 S t a t i s t i c a l Analysis Two composite samples per horizon per p lot were taken rather than one sample in order to estimate the v a r i a b i l i t y of the population as well as i t s mean. Cl ine (1944) noted that . the standard deviat ion of the composites can be considered an approximation of the standard error of the mean with respect to the to ta l population of sampling un i ts . The standard deviat ion of the population can be estimated through the use of the fol lowing formula: where S i s the estimated standard deviat ion of the populat ion, P S c i s the standard deviat ion of composites (an estimate of standard error of the mean), and n $ i s the number of samples per composite. C l ine (1944) also noted that as the number of composites decreases, the estimated standard error of the mean i s subject to more error . However, since the values for the two composites are representative of eight ind iv idual samples, i t i s f e l t that the use of a small number of composites i s j u s t i f i e d . With estimates of variance i t is possible, t o . ca l cu la te , for the (1) benefi t of future work, the number of samples required to estimate the mean wi th in a given al lowable er ror : (2) where n i s the number of samples required, is the value of. Student's t d i s t r i bu t ion with n-1 degrees of freedom, 109 2 Sp i s estimated population var iance, and E i s the allowable error . To do th is r igorous ly ; that i s , to ca lcu la te n for each plot would not be of great p rac t ica l value. Much more prac t ica l for the Vancouver Island podzol s o i l s as a whole, or for subsets of these podzols, would be a method that would provide a guide for the future sampling of these so i l s for management purposes, such as forest f e r t i l i z a t i o n . Inspection of the estimated population variances derived from the composite samples of the 33 plots according to C l i ne ' s method reveals a considerable range of variance for each of the s o i l propert ies under study. What value of var iance, then, is the most appropriate one to use in the determination of n for the s o i l s as a group? Cer ta in ly the lowest variance value would y i e l d an u n r e a l i s t i c a l l y low value for n. Almost as ce r t a i n l y , the highest values of variance would y i e l d except ional ly high values of n, since they tend to re f l ec t unusual or abnormal leve ls of variance. The ideal value, of course, l i e s somewhere between these two extremes. Since the ideal value was impossible to determine, n, the optimum number of samples necessary to meet spec i f ied allowable e r ro rs , was calculated using variance values ly ing above 90, 75 and 50 (median) percent of the tota l observed range of estimated variances. Admittedly, th is approach has no theoret ica l basis but i s undertaken for purely pract ica l reasons. One could also j u s t i f y using mean or modal values. It was fe l t . , however, that the approach taken in th is study can be used by future workers to decide on the number of samples required for the i r par t i cu la r purpose, with a known degree of cer ta inty regarding prec is ion . n o For the comparison of nu t r i t i on plot and modal p i t values of nutr ient s tocks, kilogram per hectare values were calculated for the modal p i ts in a para l le l fashion to that used for the nu t r i t i on plots described in Chapter I I . Results and Discussion The optimum number of samples required to meet an al lowable error of ± 10 percent at the 95 percent confidence level is presented in Appendix 3-1 and i s summarized in Table 3-2. Three values of n, derived from three estimates of var iance, are presented in the Appendix. The three estimates of variance used encompassed 90, 75 and 50 percent of the to ta l range of variance estimated from the 33 nu t r i t ion p lo ts . Table 3-2 i s derived from the 50 percent or median values of variance. The degree of v a r i a b i l i t y i s strongly dependent upon the par t i cu la r s o i l property. Soi l pH, for example, is by far the least var iab le and the 16 rep l ica tes employed in th is study resu l t in an error well wi th in ten percent. Noticeably high v a r i a b i l i t y i s exhibi ted by exchangeable calcium and magnesium, and ava i lab le i ron and manganese. Of the exchangeable ca t ions , sodium and potassium exh ib i t considerably less var ia t ion than calcium and magnesium. The v a r i a b i l i t y of to ta l nitrogen and ava i lab le phosphorus c lose ly pa ra l l e l s that of tota l carbon. Total su l fur pa ra l l e l s to ta l carbon to a somewhat lesser degree. Wet subzone so i l s are general ly much more var iab le than dry subzone s o i l s . Exceptions to th is general observation are v a r i a b i l i t y of ava i lab le copper and tota l ni t rogen. Avai lab le copper v a r i a b i l i t y i s I l l TABLE 3-2 THE NUMBER OF SAMPLES REQUIRED TO ATTAIN AN ALLOWABLE ERROR OF ±10 PERCENT FOR DRY SUBZONE SOILS, WET SUBZONE SOILS AND ALL SOILS, USING MEDIAN ESTIMATES OF VARIANCE Var iable Dry subzone (n = 28) Wet (n subzone = 38) A l l s o i l s (n = 66) PH 3 3 3 C 19 12 15 N 16 15 12 S 12 29 14 P 18 19 13 Ca 29 60 46 Mg 30 58 48 K 18 20 18 Na 1 26 34 Cu 22 27 23 Zn 22 40 31 Fe 54 34 42 Mn 60 94 62 s im i la r in s o i l s of both subzones; to ta l ni t rogen, more or less var iab le in the wet subzone, depending on whether the 90 or 75 percent variance i s used. In the wet subzone, the extremely high v a r i a b i l i t y of exchangeable calcium and to a lesser extent, of magnesium, can la rge ly be ascribed to one par t i cu la r s o i l , LW. This i s l i k e l y a t t r ibu tab le to the presence of scattered remnants of limestone in the B horizon of th is s o i l . 112 A comparison of nutr ient stock values derived from nu t r i t i on p lot sampling and modal p i t sampling i s presented in Table 3-3. The d i s t i n c t advantage of the nu t r i t i on p lot method, the estimate of v a r i a b i l i t y as well as the mean, is immediately apparent. This value was unavai lable for s o i l AW, however, because of the lack of rep l i ca t i on of p lo ts . Depending upon the va r iab le , the mean derived from modal sampling f a l l s wi th in ±1 standard deviat ion of the mean derived from plot sampling for between three and f i v e s o i l s out of seven. Apart from exchangeable calcium and to ta l su l f u r , the modal mean for s o i l GW consis tent ly l i e s outside of the ±1 standard deviat ion i n t e r v a l , thereby cast ing considerable doubt on the choice, of the GW modal p i t . The best agreement between the two sampling methods i s observed for exchangeable calcium and magnesium, (5 out of 7 ) , followed by exchangeable potassium and sodium, to ta l nitrogen and ava i lab le phosphorus (4 out of 7). Summary and Conclusions The attainment of an al lowable error of ±10 percent at the 95 percent confidence level presents a formidable sampling problem to researchers working with the Vancouver Island podzols. Even using the somewhat conservative median value of variance estimates in order to ca lcu la te the optimum number of samples, considerable rep l i ca t ion would be necessary. For some var iab les , attainment of ±10 percent al lowable error requires between 40 to 60 rep l i ca tes . I f , fo r a par t i cu la r data app l i ca t i on , ±20 percent al lowable error i s acceptable, then the required rep l i ca t i on can be reduced to approximately one quarter. 113 TABLE 3-3 A COMPARISON OF NUTRIENT STOCKS IN THE TOTAL B HORIZONS AS DETERMINED BY MODAL PIT SAMPLING VERSUS COMPOSITE SAMPLING WITHIN PLOTS Plot Modal Mean Standard Deviation Variable Mean - kilograms per hectare — Replicates. AD 113,000 125,000 37,300 5 AW 404,000 745,000 - 1 BD 290,000 179,000 53,500 4 BW 184,000 234,000 71,800 5 GD 77,000 124,000 21,600 5 GW 884,000 303,000 151,000 3 LW 249,000 390,000 133,000 5 SW 282,000 273,000 100,000 5 AD 3,590 3,040 1,050 5 AW 8,760 16,900 - 1 BD 6,000 3,520 1,220 4 BW 3,570 5,010 2,180 5 GD 1,560 2,510 288 5 GW 27,000 7,600 4,930 3 LW 6,390 9,200 3,940 5 SW 6,130 7,290 2,330 5 AD 18.3 52.2 23.8 5 AW 5.51 9.30 - 1 BD 44.2 44.1 45.7 4 BW 6.02 3.54 3.03 5 GD 12.4 79.6 59.3 5 GW 0.99 10.8 3.40 3 LW 10.9 83.6 128 5 SW 24.9 76.5 72.6 5 TABLE 3-3, Continued 114 _ piot — Modal Mean Standard Deviation Var iable Mean - kilograms per hectare — Replicates AD 776 570 517 5 AW 1,980 2,450 - 1 BD 716 685 290 4 BW 1,670 751 152 5 GD 411 236 48.4 5 GW 1,460 1,070 610 3 LW 842 1,440 553 5 SW 1,070 1,450 299 5 AD 74.2 421 405 5 AW 1.69 938 - 1 BD 1,550 593 369 4 BW 157 453 627 5 GD 613 1,170 280 5 GW 62.6 33.5 32.7 3 LW 12.5 1 ,410 2,470 5 SW 23.3 37.0 29.8 5 AD 23.9 83.9 62.7 5 AW 58.0 314 - 1 BD 115 93.5 35.7 4 BW 106 124 119 5 GD 63.5 80.2 23.9 5 GW 91.0 49.2 9.69 3 LW 91.3 178 90.5 5 SW 37.9 64.1 8.50 5 TABLE 3 - 3 , Continued 115 Plot Modal Mean Standard Deviation Variable Mean - kilograms per hectare -<-- Replicates AD 77.5 164 73.0 5 AW n o 286 - 1 BD 120 104 44.6 4 BW 89.4 61.4 38.7 5 GD 193 144 69.4 5 GW 120 70.6 15.9 3 LW 46.8 n o 63.3 5 SW 114 351 139 5 AD 32.6 27.9 8.39 5 AW 78.4 199 - 1 BD 101 92.0 73.7 4 BW 27.9 40.6 22.0 5 GD 26.7 39.3 10.6 5 GW 109 51 .7 18.5 3 LW 48.4 85.7 23.3 5 SW 50.4 71.0 30.1 5 It i s apparent that the extent of v a r i a b i l i t y is strongly dependent upon the spec i f i c so i l property. The least v a r i a b i l i t y i s evidenced by pH in C a C ^ , which requires only three rep l ica tes to a t ta in an error of ±10 percent. Exchangeable calcium and magnesium, and ava i lab le iron and manganese are most var iab le and require 40 to 60 rep l i ca tes . The group of var iables that includes to ta l carbon, to ta l n i t rogen, to ta l su l f u r , exchangeable potassium and sodium, and ava i lab le copper and zinc exhib i t intermediate v a r i a b i l i t y and require between ten and th i r t y rep l i ca tes . 116 The 16 samples tha t form the basis of nutr ient status in Chapter 2, resu l t in errors of less than ±10 percent for pH in C a C ^ , to ta l carbon, to ta l n i t rogen, to ta l su l fu r and ava i lab le phosphorus. Errors wi thin ±20 percent were attained for a l l four exchangeable cations plus ava i lab le copper, z i n c , i ron and manganese. These f indings are based on the use of . the median estimates of var iance. Wet subzone s o i l s tend to be more var iab le than dry subzone s o i l s and the limestone t i l l - d e r i v e d so i l of the wet subzone (LW) i s pa r t i cu l a r l y var iab le with respect to calcium and magnesium. As would be expected, numbers of samples required in the wet subzone are correspondingly higher. The comparison of nutr ient stock values derived from modal p i t sampling as opposed to composite sampling wi th in plots casts considerable doubt upon the adequacy of modal sampling in providing meaningful estimates of nutr ient stocks. The mean value derived from modal sampling frequently f a l l s outside of the in terval defined by the mean ±1 standard deviat ion as determined by composite sampling within p lo ts . Although the use of modal p i ts may be defended for genetic s tud ies , i t i s f e l t i t cannot be defended when the assessment of the nu t r i t iona l status of a s o i l i s the major concern. The d i s t i n c t advantage of the composite sampling method wi th in plots, i s that i t does provide some quant i ta t ive estimate of v a r i a b i l i t y for users of the data. SUMMARY AND CONCLUSIONS The Vancouver Island model of podzols exhib i ts many features s im i la r to the c l a s s i c a l Ae/B podzols, such as mor surface organic hor izons, accumulations of organic matter in the B, br ight-colored B horizons, a c i d i t y , low base saturat ion and low inherent f e r t i l i t y . In f ac t , a l l of the edaphic features of the s o i l , which are most relevant to and most inf luenced by vegetat ion, are comparable in the Vancouver Island and c l a s s i c a l models. Two essent ia l features of the Vancouver Island model of podzols however, set i t apart from other so i l s c l a s s i f i e d as podzols. Foremost is the great strength of the B horizon as measured by the concentration of sesquioxides. Furthermore, these large amounts of sesquioxide are maintained throughout a considerable th ickness, commonly in excess of one metre. Second i s the frequent, to ta l absence of Ae horizons over wide areas. Where Ae's do occur, they are th in and discontinuous so that the enrichment of the B horizon with sesquioxides cannot be accounted for so le ly by t ranslocat ion of sesquioxides from the Ae to the B. Physical removal or disturbance of the Ae can explain the discontinuous nature of Ae's where they do occur but cannot explain the i r tota l absence over large areas. A broadened concept of podzol genesis, which encompasses both Ae/B and Ae-less podzols, i s offered in order to support the c l a s s i f i c a t i o n of both kinds of so i l in the podzol order. The proposed 117 118 concept envisages podzol formation as involv ing three groups of processes. - i n - s i t u weathering., horizonation and ant i -hor izonat ion. In-s i tu weathering, which resu l ts in large losses of the bases and s i l i c a and the residual enrichment of sesquioxides, dominates the genesis of Ae- less podzols. Hor izonat ion, which involves the mobi l izat ion and movement, of sesquioxides both as organo-metal l ic complexes and as ions , dominates the genesis of the c l a s s i c a l Ae/B podzols, although weathering plays a ro le in making ava i lab le some of the consti tuents for subsequent t rans locat ion . Ant i -hor izonat ion by means of turbation and b iocyc l ing plays an important ro le in both models of podzols. Ae horizons do not form in the majori ty of Vancouver Island podzols, nor in the crypto-podzols of the U .S .S .R . , because the weathering of r e l a t i v e l y i r on - r i ch parent materials leads to the rapid overloading and i nso l ub i l i za t i on of metal lo-organic complexes, thereby precluding any s ign i f i can t downward t rans locat ion . Ae's do form in r e l a t i v e l y i ron-poor, s i l i ceous mater ials which o r i g i n a l l y formed at lower temperatures according to Bowen's react ion se r ies . Since such mater ials are r e l a t i v e l y more res is tan t to weathering 1and contain less i r on , i t i s suggested that , under a given b ioc l imat ic regime, Ae/B podzols w i l l always have a less sesquioxid ic B horizon than Ae- less podzols. As in a l l s o i l s , but to a greater degree in Vancouver Island podzols, the extent of weathering is a funct ion of materials and cl imate. Both the deta i led chemical studies of modal p i ts and.the assessment of nutr ient status in 0.04 hectare plots indicates that the ranges of both cl imate and t i l l l i tho logy experienced on Vancouver Is land, 119 s i g n i f i c a n t l y a f fect the propert ies of the eight indiv idual podzols. Wet subzone s o i l s have greater accumulations of organic matter and sesquioxides in the podzol B. The greater organic accumulations provide a means to of fset the more weathered and more intensely leached sola of the wet subzone, thereby maintaining the productive nature of these s o i l s . Weathering rates are apparently su f f i c i en t to maintain the excel lent product iv i ty of these s o i l s . f o r fo res ts . A more deta i led understanding of the ro le of weathering in nutr ient supply w i l l await studies on the dynamics of weathering along with the assessment of the dynamics of organic turnover. Such a level of understanding w i l l be required in the near future in order to assess the impact, on continued product iv i ty , of repeated harvesting of the forest crop and the ef fect of ro tat ion length on nutr ient deplet ion. The in tegr i t y of the eight ind iv idual s o i l s , pointed out in the assessments of deta i led morphology and nutr ient s ta tus , indicates that : wherever scale a l lows, these so i l s should be separated in s o i l surveys; in research and management, these s o i l s should be iden t i f i ed and treated according to the i r inherent propert ies. For par t i cu la r management purposes, such as nitrogen f e r t i l i z a t i o n , grouping of the s o i l s i s f eas ib le . The turbat ion component of ant i -hor izonat ion genetic processes great ly increases v a r i a b i l i t y wi th in pedons and polypedons. As a resu l t increased sample numbers are required to meet spec i f ied allowable er rors . For future research and management programs, i t i s recommended.that the adequacy of sampling a l imi ted number of modal p i ts be ca re fu l l y evaluated. Where inherent v a r i a b i l i t y might obscure the 120 true consequences of some factor or ac t i on , a composite sampling design, which attaches confidence l im i t s to sample means, should be undertaken. The concept of genesis presented provides a ra t ional basis for c l ass i f y i ng both Ae/Bf p ro f i l es and Ae-less, p ro f i l es as podzols. At the subgroup level both should be termed o r th i c . The presence or absence of an Ae horizon i s best handled below the subgroup level as are other inherent parent material d i f ferences. LITERATURE CITED Aarnio, B. 1913. Experimental!e Untersuchungen zur Frage der Ausfa l l ing des Eisens in Podsolboden. Int. Mitt. Bodenk 3: 131-140. A l l i s o n , L. E . , W. B. Bol len and C. D. Moodie. 1965. Total carbon. In C. A. Black (ed.) Methods of so i l ana lys is . Agronomy 9: 1346-1366. Atkinson, H. J . and J . R. Wright. 1957. Chelation and the ve r t i ca l movements of so i l const i tuents. Soil So. 84: 1-11. Baker, T. 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L. and H. 0. Halvorson. 1927. Studies on transformations of i ron in nature. I. Theoretical Considerations. J. Phys. Chem. 31: 626-631. Stobbe, P. C. and J . R. Wright. 1959. Modern concepts of the genesis of podzols. Soil Sc. Soc. Amer. Proc. 23: 161-164. Tarrant, R. F. 1956. Ef fect of slashburning on some s o i l s of the Douglas- f i r region. Soil Sci. Soc. Amer. Proc. 20: . 408-413. Ugo l i n i , F. C. 1968. So i l development and alder invasion in a recent ly deglaciated area of Glac ier Bay, Alaska. In Biology of Alder. Proc. Symp. of N.W. Sc. A s s ' n . , Pullman. Published by Pac i f i c Northwest Forest and Range Sta t ion , Por t land, Oregon. Valent ine, K. W. G. 1971. Soils of the Tofino - Ucluelet Lowland of British Columbia. Report No. 11 of the B r i t i s h Columbia So i l Survey. 128 Van Schuylenborgh, J . and M. G. M. Bruggenwert. 1965. On s o i l genesis in temperate humid c l imate. V. The formation of " a l b i c " and "spodic" horizons. Neth. J. Agrio. So. 13: 267-279. Wright, J . R. and M. Schni tzer. 1963. Metal lo-organic in teract ions associated with podzol izat ion. Soil So. Soo. Amer. Proa. 27: 171-176. Zeman, L. J . 1973. "Chemistry of Tropospheric Fa l lout and Streamflow in a Small Mountainous Watershed near Vancouver, B r i t i s h Columbia." Unpub. Ph.D. thes is . Univers i ty of B r i t i s h Columbia, Vancouver, 154 pp. APPENDIX 1 - 1 Descript ion and analysis of the modal s o i l s and descr ip t i of the associated vegetation H o r i z o n Depth i n PH i n H 20 pH i n C a C l 2 O r g a n i c C O r g a n i c C v. N C/N S i P i B ray ppm CEC (NH^OAc) E x c h a n g e a b l e C a t i o n s Ca Mg K Na CEC ( N a C l ) S a t u r a -t i o n % E x c h . A c i d i t y me./100 g . • cm. h LF 5-2.5 4.5 4.0 45.94 - .943 49 .078 53. H 2.5-0 3.9 3.3 36.94 - .815 45 .086 61. B f h 0-15 5.5 4.8 3.80 4.53 .209 18 .019 11.0 34.8 .15 .12 . 10 .05 0.9 80.7 26:3 B f x 15-30 5.6 5.1 2.23 2.25 .117 19 .016 4.2 27.0 .13 .07 06 .05 0.6 89.6 21.0 B f 2 30-45 5.8 5.1 2.10 2.24 .121 17 .038 3.7 25.7 .12 .06 . 06 .05 0.6 93.4 20.1 B f 3 45-60 5.7 5.1 2.06 2.05 .117 18 .024 5.2 25.5 .13 .06 . 07 .05 0.6 95.5 30.7 B V 60-75 5.8 5.1 1.80 1.74 .092 20 .030 5.2 26.5 .12 .05 . 06 .05 0.6 95.1 20.0 B f g j * . 75-90 5.7 5.2 1.36 1.38 .074 18 .035 10.5 21.3 .11 .04 . 06 .04 0.5 97.7 14.8 c 90+ 6.0 5.2 0.43 0.35 .020 21 .008 26. 8.6 .41 .04 . 05 .04 0.6 98.2 9.1 H o r i z o n Sand S i l t C l a y G r a v e l S t o n e s P y r o p h o s O x a l a t e C i t - D i t h „ Fe A l Fe A l Fe A l B f h 52 34 14 49 28 .28 1.26 1 .86 3.56 3. ,78 2. ,30 B f ! 61 36 3 41 32 .13 .77 1 .88 3.03 4. ,15 1, .93 B f 2 53 40 7 39 34 .08 .71 1 .73 2.87 . 3. ,78 1, .30 B f 3 54 38 8 35 41 .08 .71 1 .73 2.98 3. ,85 1. .75 B V 76 23 1 45 31 .07 • .69 1. .56 2.87 3. ,73 1. .65 B V 57 35 8 57 27 .06 .58 1, .80 2.91 4. ,00 1. .43 C .02 .26 .78 1.43 1. ,35 .50 131 Soi l Name: AD Locat ion: 48°51'N, 124°15'W Parent Mater ia l : stony, gravel ly sandy loam Elevat ion: 750' andesi t ic t i l l Aspect: eastern Landform: morainal blanket-veneer Drainage: moderately w e l l , minor receiv ing slope pos i t ion . C l a s s i f i c a t i o n : Duric Humo-ferric Podzol Slope: 25% 5 - 2 . 5 LF variegated mixture of fresh needles, twigs and moss; loose consistence; no roots ; abrupt, wavy boundary to , 2 . 5 - 0 H dark reddish brown (5YR 2/2 (m) muck; f e l t y mor; f i rm when moist; abundant roots; abrupt, wavy boundary to , 0 - 1 5 Bfh l i gh t brown (7.5YR 6/4 (d) gravel ly sandy loam to loam; weak, medium and coarse subangular blocky; common concret ions; very f r i a b l e when moist; abundant roots ; c lear wavy boundary to , 15 - 30 Bfi l i gh t ye l lowish brown (10YR 6/4 (d) gravel ly sandy 30 - 45 B f 2 loam; weak, medium and coarse subangular blocky 45 - 60 Bf 3 s t ructure; common concret ions; f r i a b l e when moist; s l i g h t l y p l as t i c and non-st icky when wet; abundant roots ; c l ea r , wavy boundary to , 60 - 75 Bf •! pale brown (10YR 6/3 (d) gravel ly sandy loam to loamy _ g_ 9J sand; weak, medium and coarse subangular blocky g j 2 s t ructure; f i rm when moist; s l i g h t l y p las t i c and non-s t icky when wet; occasional roots ; abrupt wavy boundary to , 90 - 105 BCd l i gh t brownish gray (2.5Y 6/3 (d) gravel ly sandy loam; breaks in strong, coarse pseudoplaty s t ructure; non-s t icky and non-p last ic when wet; extremely f i rm when moist; roots absent; gradual wavy boundary t o , 105 + C l i gh t brownish gray (2.5Y 6/3 (d) and o l i ve gray (5Y 5/2 (d) gravel ly sandy loam; structureless-massive; extremely f i rm when moist; no roots , unaltered basal t i l l parent mater ia l . Horizon Depth in pH in H20 pH in CaCl 2 LECO Organic C W-B Organic C N C/N S % Pi Bray ppm CEC (NH4OAc)• Exchangeable Cations Ca Mg K Na CEC (NaCl) Base Satura-t ion of Exch. Acidi ty me./lOO g. cm. 10 LH 10-0 4.7 4. 4 43.07 .932 46 .114 16.8 B f h 0-15 4.7 4. 2 7.10 8.47 .191 37 .040 1.2 57.7 - .14 06 .11 2.7 16.8 32.8 B f h x 15-30 5.1 4. 6 4.42 5.54 .169 26 .042 0.9 47.8 - .15 06 .07 1.0 59.8 27.8 B f h 2 30-45 5.0 4. 4 . 3.83 5.05 .125 31 .041 0.9 37.7 - .13 05 .07 1.8 20.5 25.5 B f h 3 45-60 5.2 4. 7 3.86 4.47 .195 20 .044 0.9 42.9 .01 .07 05 .06 0.8 74.4 27.3 B f h 4 60-75 5.1 4. 6 4.92 6.03 .212 23 .041 1.3 48.4 - .05 07 .06 0.8 63.8 29.5 B f h . 8J 75-90 4.9 4. 5 5.74 6.74 .229 25 .042 1.9 52.3 - .05 07 .06 1.15 47.3 23.4 B C d 90-105 5.7 4. 9 0.77 1.01 .038 20 .021 23.6 19.5 .28 .04 04 .06 0.8 86.1 13.3 C 105+ 5.9 5. 1 0.3.1 0.30 .011 28 .008 24.5 13.0 1.01 .15 07 .13 1.5 92.0 10.2 Horizon Sand S i l t Clay Gravel Stones Pyrophos Oxalate C i t - D i t h Fe A l Fe A l Fe A l /, - %  B f h 34 42 24 29 17 1.47 1.98 3. ,41 4. ,21 4. .43 3.05 B f h ! 52 40 8 28 16 .67 1.40 2. .72 4. .19 3. ,98 2.50 B f h 2 24 58 18 26 16 .94 1.05 2. .94 2. .47 4. .73 1.83 B f h 3 43 47 10 32 11 .44 1.05 2. ,22 4. .24 3. .35 2.43 B f h i , 36 52 12 29 25 .81 1.80 2. .34 4. ,65 3. .35 3.00 B f h . £3 53 37 10 24 26 1.12 2.25 2. ,45 4. .65 3, .23 3.33 B C d 48 40 12 35 31 .05 .47 ,95 2. .16 1. .93 .85 C 51 34 15 - - .02 .23 .65 1, .19 1. .60 .40 133 Soi l Name: AW Parent Ma te r ia l : gravel ly sandy loam andesi t ic t i l l Landform: morainal blanket-veneer Locat ion: 50°42'N, 128°2'W Elevat ion: 550' Aspect: eastern Drainage: moderately w e l l , minor receiv ing slope pos i t ion C l a s s i f i c a t i o n : Duric Ferro-Humic Podzol Slope: 20% 10 - 7.5 LF 7 . 5 - 0 H 0 - 1 5 Bhf 1 5 - 3 0 B f h i 30 - 45 B f h 2 45 - 60 Bfh3 60 - 75 Bfhi+ 75 - 90 Bfh 9J mixture of needles, twigs and fern l i t t e r in various stages of decomposition, loose to f e l t y ; few roots ; abrupt, wavy boundary to , dark reddish brown (5YR 2/2 (d) muck; amorphous mor; f i rm when moist ; abundant roots ; abrupt, wavy boundary to , var ious ly colored (from l i gh t ye l lowish brown 10YR 6/4 (d) to very dark grayish brown 10YR 3/2 (d) depending on organic matter content) grave l ly loam; weak, medium and coarse subangular blocky; f r i a b l e when moist ; non-s t icky and s l i g h t l y p l as t i c when wet; abundant roots ; c l e a r , wavy boundary to , a mix of ye l lowish brown (10YR 5/4 (d) and l i gh t ye l lowish brown (10YR 6/4 (d) gravel ly loam to gravel ly sandy loam; weak, medium and coarse subangular blocky; f r i a b l e when moist; non-st icky and s l i g h t l y p las t i c when wet; occasional roots ; c l ea r , wavy boundary t o , ye l lowish brown (10YR 5/4 (d) and l i gh t yel lowish brown (10YR 6/4 (d) grave l ly s i l t loam; weak, medium and coarse subangular blocky; f i rm when moist; non-st icky and s l i g h t l y p las t i c when wet; occasional roo ts ; c lear wavy boundary to , ye l lowish brown (10YR 5/4 (d) and l i gh t yel lowish brown (10YR 6/4 (d) grave l ly loam; weak, medium coarse subangular blocky; f i rm when moist; non-st icky and s l i g h t l y p l as t i c when wet; occasional roots ; c l ea r , wavy boundary to , l i gh t ye l lowish brown (10YR 6/4 (d) with patches of darker, more organic dark brown (10YR 4/3 (d) gravel ly s i l t loam; weak, medium and coarse, subangular blocky; f i rm when moist; non-st icky and s l i g h t l y p l as t i c when wet; occasional roots ; c lear wavy boundary t o , dark brown (10 YR 3/3 (d) gravel ly sandy loam with patches of l i gh t ye l lowish brown (10YR 6/4 (d); weak, medium and coarse subangular blocky; f i rm when moist; non-st icky and s l i g h t l y p l as t i c when wet; occasional roots ; abrupt, wavy boundary to , 134 90 - 105 BCd l i gh t o l i ve gray (5Y 6/2 (d) gravel ly loam matrix with brownish yel low (10YR 6/6 (d) and dark brown (7.5YR 3/2 (d) colors along ped sur faces; coarse pseudoplaty s t ructure; non-st icky and non-plast ic when wet; extremely f i rm when moist; roots absent; gradual wavy boundary to , 105+ C l i gh t o l i ve gray (5YR 6/2 (d) grave l ly loam unaltered parent t i l l ; massive; extremely f i rm when moist; no roots. 1 Horizon Depth in PH in H20 pH in CaCl 2 LLLU Organic C V'J — • Organic C N C/N S % Pi Bray ppm CEC (NI^OAc) Exchangeable Cations Ca Mg K N« CEC (NaCl) Satura-t ion % Exch. Acid i t me./IOO cm. /o LF 7.5-4 4.6 4.4 44.60 1.187 38 .089 58 H 4-0 4.5 4.0 32.92 .845 39 .106 57 Bf i 0-20 5.4 4.7 1.69 1.53 .059 29 .007 5.0 12.0 .70 .09 .06 .04 0.7 62.9 11.8 Bf 2 20-40 5.4 4.7 1.55 1.69 .062 25 .008 5.4 12.7 1.41 .15 .04 .06 . 0.9 75.1 12.5. Bf 3 40-60 5.4 4.8 1.71 1.86 .068 25 .005 8.5 14.3 1.54 .14 .03 .06 0.9 93.5 12.7 B V B f 9 3 2 BCd 60-80 5.8 4.9 2.10 2.31 .037 24 .009 4.6 20.8 1.25 .17 .04 .07 1.0 97.1 15.1 80-112 5.7 4.9 3.41 2.67 .109 31 .015 5.8 23.1 .65 .11 .03 .06 1.7 50.0 15.7 112-127 4.9 4.5 0.27 0.29 .016 17 - 20.4 7.3 .20 .03 .03 .07 0.4 98.4 5.3 C 127+ 4.9 4.5 0.12 0.06 . 006 20 - 20.6 4.1 .18 .04 .03 .05 0.3 98.1 3.4 Horizon Sand S i l t Clay Gravel Stones Pyrophos Oxalate Ci t - Dith Fe Al Fe Al Fe Al Bf i 28 57 15 34 6 99 1.08 .15 46 3.15 .98 Bf 2 19 61 20 36 19 1 23 1.02 .39 53 3.43 .93 Bf 3 44 44 12 54 6 1 14 1.71 .14 56 2.65 1.15 Bf 60 31 9 41 22 1 37 2.97 .12 68 2.05 1.40 g j 1 Bf 50 40 10 43 12 1 29 2.67 .14 88 2.20 1.53 g j 2 BCd 47 43 10 28 11 .32 .84 .02 21 .76 .49 C 25 .54 .01 14 .68 .30 136 Soi l Name: BD Locat ion: 50°12'N, 125°31'W Parent Mate r ia l : gravel ly loam Elevat ion: 800' basa l t i c t i l l Aspect: west Landform: morainal blanket Slope: 10% Drainage: moderately well drained, minor receiv ing C l a s s i f i c a t i o n : Duric Humo-ferric Podzol 7 . 5 - 4 LF variegated mix of coniferous and sa la l l i t t e r in varying stages of decomposition; f e l t y ; abrupt wavy boundary to , 4 - 0 H dark reddish brown (5YR 2/2 (d) muck; f e l t y mor; abundant roots ; abrupt, wavy boundary to , 0 - 2 0 Bf! yel lowish red (5YR 4/6 to 4/7 (d) s i l t loam; weak, 20 - 40 B f 2 medium and f ine subangular blocky; very f r i a b l e when moist; non-st icky and s l i g h t l y p las t i c when wet; abundant roo ts ; c lear wavy boundary to , 40 - 60 Bf 3 brown (7.5YR 4/4 (d) gravel ly loam; weak medium subangular blocky; f r i a b l e when moist; non-st icky and s l i g h t l y p las t i c when wet; common roots ; c l ea r , wavy boundary to , 60 - 80 Bf •! reddish brown (5YR 4/4 (d) grave l ly loam to gravel ly R f sandy loam; st ructure less - s ing le g ra in ; loose when gh 2 moist; non-st icky and non-p las t ic ; many, f i n e , prominent mottles (7.5YR 5/6, 5YR 4/3 and 2.5Y. 5/3) common roots ; scattered t i l l fragments; abrupt wavy boundary to , 112-127 BCd o l i ve gray (5Y 4/2 (d) gravel ly loam t i l l ; breaks out in coarse pseudo-platy s t ructure; extremely f i rm ; non-s t icky and non-plast ic when wet; roots absent; gradual, wavy boundary t o , 127+ C o l i ve gray (5Y 4/2 (d) gravel ly loam parent t i l l ; s t ructureless-massive; extremely f i rm ; no roots. LECO W-B Base Horizon Depth in cm. pH in H20 PH in CaCl 2 Organic C Organic C __ 0/ N C/N S 1 Pi Bray ppm CEC (NH40Ac) Exchangeable Cations Ca Mg K Na m n /inn r, CEC (NaCl) Satura-t ion i Exch. Acidi ty me./100 g. h LF 10-7.5 3.2 2.9 48.23 1.041 46 .100 16.4 H 7.5-0 3.2 2.8 48.81 . 1.340 36 .143 10.4 Bfhj 0-15 5.4 4,6 4.24 3.44 . .140 30 .034 1.6 43.7 .01 .16 . 07 .03 1.2 40.2 26.5 Bfh 2 15-30 5.6 4.9 3.23 3.74 .102 32 .034 1.3 34.6 .21 .20 . 06 .03 0.9 92.6 22.7 30-45 5.9 5.3 2.11 2.31 .091 23 .048 0.9 35.6 .21 .15 . 06 .03 0.8 100.0 19.7 Bf 2 45-50 6.3 5.6 1.22 1.56 .056 22 .046 1.3 25.7 .11 .16 . 04 .02 0.7 99.3 17.3 60-75 6.3 5.7 1.12 1.07 .044 25 .035 1.4 21.6 .17 .16 . 04 .02 0.7 99.3 13.2 B V 75-90 6.1 5.3 2.11 2.17 .032 66 .024 1.6 27.8 .33 .34 . 03 .03 1.0 96.6 22.3 BCd 90-105 6.2 5.4 0.41 0.33 .017 24 .003 12.9 6.8 .17 .08 . 01 .03 0.5 97.8 7.4 C 105+ 6.5 5.3 0.17 0.12 .003 57 .005 30 2.6 .83 .15 . 02 .04 1.0 99.4 4.7 Horizon Sand S i l t Clay Gravel Stones Pyrophos Oxalate Ci t -Di th «, Fe Al Fe Al Fe Al h %  Bfhi 58 33 9 47 5 .51 1.18 2. .96 4. ,75 4. ,18 2.30 Bfh 2 49 40 11 46 6 .13 .76 2. .97 3. ,65 5. ,28 2.10 Bfj 65 35 0 42 4 .07 .66 3. .11 4. 55 5. 30 2.15 Bfi 61 38 1 • 39 20 .06 .51 2. ,85 5. ,00 3. ,25 1.70 73 27 0 45 n .04 .43 2. .30 4. ,20 2. ,38 1.40 B V 60 38 2 40 16 .12 .59 2. ,65 3. ,99 2. ,63 1.60 BCd 76 21 3 42 14 .02 .23 .86 1. ,50 ,70 .45 C 78 19 3 - - .02 .11 .78 ,87 ,35 .20 138 Soi l Name: BW Locat ion: 50°32'N, 127°20'W Parent Mate r ia l : gravel ly loamy sand Elevat ion: 550' basa l t i c t i l l Aspect: Ni l Landform: morainal blanket Slope: 5% Drainage: moderately well C l a s s i f i c a t i o n : Duric Humo-ferric Podzol 10 - 7.5 LF variegated mixture of coniferous l i t t e r and mosses; loose consistence; no roots ; abrupt wavy boundary to , 7 . 5 - 0 H dark reddish brown (5YR 2/2 (d) muck; f e l t y above, amorphous below; abundant roots ; abrupt, wavy boundary to , 0 - 1 5 Bfh! ye l lowish red (5YR 4 /5 , and 5/6 (d) with lesser 15 30 Rfh component of reddish brown (5YR 4/3 and 5YR 4/4 (d), 2 gravel ly sandy loam to grave l ly loam; weak, medium and coarse subangular blocky; f r i ab l e when moist; non-s t icky and s l i g h t l y p l a s t i c , wet; common roots ; abrupt, wavy boundary to , 30 - 45 B ^ strong brown (7.5YR 5/6 (d) gravel ly sandy loam; minor 45 - 60 Bf brownish yellow (10YR 6/6 (d); weak medium and coarse 2 subangular blocky; f r i a b l e ; non-st icky and s l i g h t l y p l a s t i c , wet; occasional roots ; c lear wavy boundary to , 60 - 75 Bf -i brownish yellow (10YR 6/6 and yellow (2.5Y-7/6 (d) 75 - 90 Bf gravel ly sandy loam; weak medium and coarse subangular g j 2 blocky; f i rm when moist; non-st icky and non-p las t ic , wet; occasional roo ts ; abrupt, wavy boundary to , 90 - 105 BCd o l i ve gray (5Y 5/2 (d) .gravel ly loamy sand matrix with yellow (2 .5Y7 /6 ) and strong brown (7.5YR 5/6 (d) coatings along cleavage planes; coarse pseudoplaty s t ructure; extremely f i rm , moist; non-st icky and non-p l a s t i c , wet; no roots ; c l ea r , wavy boundary to , 105+ C o l i ve gray (5Y 5/2 (d) gravel ly loamy sand parent t i l l ; extremely f i rm, moist; no roots. L t t u w-ts Doie Horizon Depth in PH in H20 pH in CaCl 2 Organic C Organic C i N C/N S Pi Bray ppm CEC (NH^OAc) Exchangeable Cations Ca Mg K Na CEC (NaCl) Satura-t ion t Exch. Acidi ty me./IOO g. cm. io io LF 7.5-5 4.9 4.5 42.02 1.140 37 .055 H 5-0 4.9 4.5 31.90 1.340 24 .078 Ac 0-2.5 5.02 4.05 1.89 2.56 .050 38 .013 6.3 12.9 2.21 .31 ,. 30 .03 3.0 95.8 6.7 Bml 2.5-17.5 5.42 4.9 1.31 1.05 .027 49 .006 3.2 11.9 1.21 .17 . 16 .03 1.4 97.6 8.9 am2 17.5-32.5 5.4 4.7 1.25 1.16 .043 29 .011 3.0 11.3 .74 .13 . 13 .03 1.0 95.0 8.7 Bm3 32.5-47.5 5.4 4.8 0.89 0.92 .046 19 .014 3.0 11.5 .47 .10 . 10 .03 0.7 90.7 8.0 Bmgj 47.5-12.5 5.3 4.8 1.04 0.77 .043 24 .011 3.1 9.5 .50 .11 09 .03 0.9 85.1 7.8 BCd 62.5-77.5 5.6 5.1 0.35 0.30 .018 19 .007 11.0 9.0 .20 .04 . 07 .03 0.4 98.6 6.0 C 77.5+ 5.7 5.2 0.12 0.14 .011 11 .006 4.8 8.6 2.39 .48 . 11 .12 2.7 100.0 3.3 Horizon Sand S i l t Clay % Gravel Stones Pyrophos Fe Al Oxalate Fe Al Cit-Fe •Dith Al 7o -Ae 58 34.5 7.5 - - .10 .16 .33 17 1 34 .29 Bml 60 35 5 - - .08 .30 .38 57 1 72 .88 Bm2 72 27 1 - - .07 .36 .49 86 1 42 .80 Bm3 70 29 1 - - .06 .33 .30 81 1 16 .70 Bmgj 65 33 2 - - .06 .31 .53 53 94 .57 BCd 80 18 2 - - .02 .24 .59 1 03 66 .46 C 82 18 0 - - .02 .11 .36 21 68 .14 140 Soi l Name: GD Locat ion: 49°3'N, 124°10'W Parent Mater ia l : stony, very g rave l l y , E levat ion: 1200' loamy sand g ran i t i c t i l l Aspect: south Landform: morainal blanket Slope: 10% Drainage: well C l a s s i f i c a t i o n : (Duric) Degraded Dystr ic Brunisol 7 . 5 - 5 . 0 LF var iegated, loose mixture of coniferous and sa la l l i t t e r ; f e l t y below; occasional roots ; abrupt, wavy boundary to , 5 . 0 - 0 H black (10YR 2/1 (d) muck; f e l t y ; abundant roots ; abrupt, wavy boundary to , 0 - 2.5 Ae gray (10YR 6/1 (d) grave l ly sandy loam; s t ruc ture less-s ingle g ra in ; loose when moist; non-st icky and non-p l a s t i c ; abundant roots ; abrupt wavy boundary t o , 2.5 - 17.5 Bml l i gh t yel lowish brown (10YR 6/4 (d) to pale brown 17.5 - 32.5 Bm2 (10YR 6/3 (d ) .grave l l y loamy sand to gravel ly sandy loam; st ructureless s ing le g ra in ; loose when moist; non-st icky and non-p las t i c , wet; common roots ; c l e a r , wavy boundary to , 47.5 - 62.5 Bmgj l i gh t brownish gray (2.5Y 6/2 (d) gravel ly sandy loam; s t ruc tu re less-s ing le g ra in ; loose when moist; non-s t icky and non-p las t i c , wet; many, prominent, coarse and medium l i gh t ye l lowish brown (10YR 6/4 (d) mott les; occasional roots; abrupt, wavy boundary to , 62.5 - 77.5 BCd o l i ve gray (5Y 5/2 (d) gravel ly loamy sand matrix which breaks to coarse p la tes ; along cleavage planes, micro-Ae's with clean sand grains and l i gh t brownish gray (2.5Y 6/2 (d) over micro B's with coatings of l i gh t yel lowish brown (10YR 6/4 (d); extremely f i rm when moist; non-st icky and non-p las t ic ; no roots ; c lea r , wavy boundary to , 77.5+ C o l i ve gray (5Y 5/2 (d) gravel ly loamy sand parent t i l l ; s t ructureless-massive; extremely f i rm; no roots. LECO W-B Base Horizon Depth in cm. pH in H20 PH i n CaCl 2 Orqanic C Organic C «i N C/N S i Pi Bray ppm CEC (NHi»OAc) Exchangeable Cations Ca Mg K Na mo /inn n CEC (NaCl) Satura-t ion % • Exch. Acidi ty me./lOO g. h LF 22.5-7 . .5 4.4 3.7 25.07 1.103 23 .091 13.8 H 7.5-0 3.9 3.3 50.34 .564. 89 .051 14.4 Bhfx 0-15 5.4 4.5 10.98 n .83 .495 22 .031 0.4 67.1 .30 .37 12 .10 1.9 33.7 37.8 Bhf 2 15-30 5.5 4.8 8.56 9.10 .403 21 .027 0.0 64.5 .03 .12 . 05 .08 1.2 89.1 36.5 Bhf3 30-45 5.5 4.8 7.93 10.55 .508 16 .022 0.0 75.7 .03 .10 . 05 .07 1.1 85.9 38.6 Bhf!. 45-60 5.6 4.6 11.01 12.35 .569 19 .024 0.2 79.6 .01 .11 05 .12 1.2 81.0 42.8 B h f g j l 60-75 5.6 4.7 9.58 10.74 .469 20 .029 0.3 79.0 .01 .08 . 04 .09 1.2 83.6 32.9 B h V 75-90 5.4 4.7 9.35 10.26 .550 17 .031 0.3 74.1 .01 .09 . 04 .07 1.2 82.4 49.5 BCd 90-105 5.9 5.2 1.51 1.42 .059 26 .015 3.3 18.7 .06 .03 . 02 .04 0.5 94.1 17.1 C 105+ 6.0 5.3 1.43 1.31 .046 31 .013 3.8 13.5 .25 .07 . 03 .04 0.5 95.5 13.1 Horizon Sand S i l t Clay % -Gravel Stones Pyrophos Fe Al Oxalate Fe Al . . . . % . . . . Cit-Fe •Di th Al Bhf! 23 58 19 20 29 1.13 2. .85 2, .29 6. ,76 2. .93 4.43 Bhf2 33 55 12 26 7 .58 2. .35 1, .49 7. ,46 2. ,35 4.33 Bhf3 42 49 9 18 11 .70 2. .45 1. .45 7. ,18 2. 33 4.65 Bhf4 36 52 12 20 13 .90 2. ,85 1. .54 8. .01 2. ,30 4.88 B h f g j l 59 35 6 21 27 .76 2. ,50 1. .62 7. ,57 2. ,30 4.63 Bhf - 2 46 45 9 24 17 .90 2. .55 1, .57 7. ,91 2. ,05 4.73 gj BCd 65 34 1 - .60 .65 .57 2. ,82 ,73 1.13 C 75 21 4 - - .42 ,51 .58 2. .52 ,55 .95 142 Soi l Name: GW Locat ion: 48°36'N, 124°22'W Parent Ma te r ia l : g rave l ly sandy loam Elevat ion: 1750' d i o r i t i c t i l l Aspect: southeast Landform: morainal blanket-veneer Drainage: moderately w e l l , minor receiv ing Slope: 40% C l a s s i f i c a t i o n : Duric Ferro-humic Podzol 22.5 - 7.5 LF variegated mix of coniferous l i t t e r over F with high proportion of red rotten wood; occasional roots ; abrupt, wavy boundary to , 7.5 - H dark reddish brown (5YR 2/2m) muck; f i rm consistence; strong medium subangular blocky; abundant roots ; abrupt, wavy boundary to , 0 - 1 5 Bhf! reddish brown (5YR 4/4m) and yel lowish red (5YR 1 5 - 3 0 Bhf 2 4/6m) s i l t loam to loam with about 25% organic r i ch 30 - 45 Bhf 3 pockets of dark reddish brown (5YR 2/2m); moderate, 45 - 60 Bhf^ coarse and medium subangular blocky; f i rm, moist; s l i g h t l y s t i cky and s l i g h t l y p l a s t i c , wet; common roots; c lea r , wavy boundary to , 60 - 75 B n f a i i reddish brown (5YR 4/4m) and yel lowish red (5YR 75 _ gQ Bhf 4/6m) loam to sandy loam, with about 50% organic g j 2 r i ch dark reddish brown (5YR 2/2m); moderate, medium and coarse subangular blocky; f i rm, moist; non-st icky, s l i g h t l y p l as t i c when wet; occasional roots ; abrupt, wavy boundary to , 9 0 - 1 0 5 BCd dark grayish brown (2.5Y 4/2m) gravel ly sandy loam; structureless-massive breaking out in coarse p la tes ; extremely f i rm, moist ; non-st icky and non-p l a s t i c , wet; no roots; c l e a r , wavy boundary to , 105+ C very dark grayish brown (2.5Y 3/2m) grave l ly sandy loam; st ructure less-massive; extremely f i rm when moist; non-st icky and non-p las t i c , wet; no roots. Horizon Depth in pH in H20 PH in CaCl 2 LECO Organic C W-B Organic C N C/N S V Pi Bray ppm CEC (NH40Ac) Exchangeable Cations Ca Mg K Na CEC (NaCl) tsase Satura-t ion t Exch. Ac i d i ty me./IOO g. cm. h LF 12.5-10 4.7 4.3 33. 41 .899 37 .089 44 H 10-0 3.8 3.3 44. 35 1.456 30 .123 18.8 Bhf 0-15 4.9 4.1 6. 13 6.91 .244 25 .026 3.7 47.8 .02 .47 . 07 .09 4.1 12.7 31.0 Bfh 15-30 5.1 4.1 5. .33 6.25 .254 21 .024 4.0 47.3 .03 .27 . 05 .07 3.2 17.4 30.9 B f h g j l 30-45 5.3 4.4 3. 67 4.40 .177 21 .029 3.4 39.0 .02 .13 . 02 .06 1.1 46.6 25.2 B f h g j 2 BCd 45-55 5.6 4.7 3. 30 3.42 .146 23 .031 3.0 32.5 .01 .07 . 01 .05 0.7 72.2 23.5 55-70 5.6 5.0 0. 93 0.92 .031 30 .009 11.3 11.2 .03 .02 . 01 .02 0.4 85.4 14.3 C 70+ 5.8 5.3 0. 39 0.36 .012 32 .015 29.5 7.0 .09 .02 . 02 .04 0.3 92.9 .8 .2 Horizon Sand S i l t Clay Gravel Stones Pyrophos Oxalate Cit-Dith 0 / Fe Al Fe Al Fe Al k — — _ %  Bhf 41 46 13 26 9 2. .64 1, .60 3. .84 2. ,67 4. .83 2.18 Bfh 39 41 20 30 9 1. .82 1 .60 3. .23 2. ,75 4. .43 2.73 62 39 1 31 10 1. .17 1, .20 2. ,91 3. ,26 3. .90 2.23 B ^ j 2 50 49 1 34 ' 11 .99 1 .16 2. .71 3. .53 3. ,38 1.95 BCd 64 34 2 31 13 ,06 .44 ,82 1. .92 1. .38 .75 C 69 30 1 - - .02 .23 .85 1. .42 .98 .43 144 Soi l Name: LW Parent Mate r ia l : Gravel ly sandy loam mixed l imestone, igneous t i l 1 Landform: morainal veneer Drainage: moderately well C l a s s i f i c a t i o n : Duric Ferro-humic Podzol Locat ion: 50°37'N, 128°3'W Elevat ion: 900' Aspect: southeast Slope: 20% 12.5 - 10 LF 1 0 - 0 H 0 - 1 5 Bhf 1 5 - 3 0 30 - 45 45 - 55 55 - 70 70+ Bhf B f h g j 2 BCd variegated, loose mixture of coniferous needles and twigs; no roots ; abrupt, wavy boundary to , dark reddish brown (5YR 2/2m) muck; amorphous; abundant roots; abrupt, wavy boundary t o , dark brown (7.5YR 4/4d) loam; small patches of brownish yellow (10YR 6/5d); moderate, f ine subangular blocky; f r i a b l e when moist; non-st icky, p las t i c when wet; common roots; abrupt, wavy boundary to , brown (7.5YR 4/2 to 4/4d) loam; patches of brownish yellow (10YR 6/5d); moderate, coarse and medium, subangular blocky; f i rm , moist; non-st icky and p l a s t i c , wet; occasional roots ; c l ea r , wavy boundary to , brown (7.5YR 5/4d) gravel ly sandy loam; moderate, coarse and medium subangular blocky; f i rm, moist; non-st icky and s l i g h t l y p l a s t i c , wet; occasional roots ; common, f i n e , prominent, reddish yellow (7.5YR 6/6d) and few, f i n e , prominent, l i gh t ye l lowish brown (2.5Y 6/4d) mott les; abrupt, wavy boundary to , l i gh t brownish gray (2.5Y 6/2d) gravel ly sandy loam; st ructureless-massive, breaking to coarse plates with brownish yellow (10YR 6/6d) and reddish yel low (7.5YR 6/6d) coatings along cleavages; extremely f i rm, moist ; no roots ; c l e a r , wavy boundary t o , l i gh t brownish gray (2.5Y 6/2d) grave l ly sandy loam parent t i l l mate r ia l ; s t ructureless-massive; extremely f i rm, moist; no roots. Horizon Depth i n PH in H 20 PH in CaCl 2 LECO Organic C W-B Organic C N C/N S °/ Pi Bray ppm CEC (NH^OAc) Exchangeable Cations Ca Mg K Na CEC (NaCl) Base Satura-t ion % Exch. Acidi ty me./TOO g. cm. Jo int.. / i W 3 . LF 1 0 - 7 . 5 4 . 4 4 . 2 46.61 .870 54 .074 57 H 7 . 5 - 0 3 . 6 3.1 4 3 . 1 6 1.427 30 .120 27 Ae 0 - 5 4.1 3 . 4 1 .16 1.37 .043 27 .002 2 . 5 5 . 5 .28 .17 . 04 . 0 3 6.1 2 . 7 2 5 . 4 Bfh 5-20 5 . 0 4 . 5 2 . 9 8 2.81 .090 ' 33 .017 0 . 6 2 0 . 8 . 0 4 . 05 .03 1 .0 2 0 . 4 2 3 . 8 Bf! 2 0 - 3 5 5 . 4 4 . 9 2 . 5 9 2 .24 .093 23 . 024 0 . 4 2 0 . 5 .03 05 .03 0 . 5 6 4 . 6 20.1 Bf 2 3 5 - 5 0 5 .4 4 . 9 1.63 1.34 .060 27 .021 1.2 1 4 . 3 .01 . 0 3 . 04 . 0 3 0 . 3 60.1 14.1 Bf 3 50-6.5 5 .4 4 . 9 0 . 8 5 0 . 8 6 .031 27 .016 5 .8 8.1 . 0 3 . 03 .03 0 . 4 2 8 . 3 1 0 . 7 Bf,, 6 5 - 8 0 5 .4 4 . 7 1.96 1.58 .066 30 . 0 1 5 3 . 0 1 4 . 8 . 0 4 . 04 . 04 0 . 6 2 5 . 3 1 6 . 3 B C 9 J 2 Ci 8 0 - 9 5 5 . 2 4 . 5 2 .77 2 . 2 2 .114 24 .008 6 . 0 2 0 . 0 . 04 . 04 .03 0 . 9 2 5 . 3 18 .7 9 5 - 1 1 0 5.1 4 . 5 3 . 9 2 4.41 .171 23 .011 8 . 0 3 5 . 4 . 0 5 . 04 . 0 3 0 . 9 . 2 8 . 4 2 7 . 5 110 -125 5 . 5 5 . 2 0 . 4 3 0.31 . 0 1 5 29 .011 24 3 . 4 .01 .01 04 . 0 3 0 . 2 6 5 . 0 5 .8 C 2 125+ 5 . 9 5 . 2 0 .24 0 .13 .008 36 . 0 1 0 29 5 . 2 .01 .01 . 05 . 0 3 0 . 2 9 6 . 9 5 . 2 Horizon Sand S i l t Clay Gravel Stones Pyrophos Oxalate Ci t-Di th Fe Al Fe Al Fe Al " * " — % — Ae 17 72 11 18 4 . 34 .12 .27 .21 .98 .10 Bfh • 32 58 10 25 7 . 6 8 1 .05 1 .42 1 .99 2 . 4 8 1. .93 Bfi 52 43 5 27 9 .28 . 8 5 1 .12 2 . 3 9 1.73 1. . 65 Bf 2 . 42 47 5 30 5 .11 . 4 8 . 76 1 .45 1.28 1, .03 Bf 3 58 35 7 31 3 . 0 5 . 26 .57 . 86 . 8 8 .53 Bf 4 42 55 3 35 8 . 1 2 . 4 8 . 7 3 1.51 1 .03 .93 BC . i 44 53 3 25 8 . 1 5 . 8 2 . 5 5 1 .60 .80 1 . 2 3 g j 1 BC . , 26 66 8 23 10 . 3 2 1 .28 . 6 0 2 . 5 9 . 7 3 1. . 9 0 g j 2 c i 36 56 8 - - .01 . 1 8 . 1 8 .37 . 4 3 . 4 0 c 2 28 58 14 - -.01 . 1 5 . 3 3 . 64 . 4 3 . 3 8 146 So i l Name: SW Locat ion: 48°34'N, 124°20'W Parent Mate r ia l : g rave l l y , s i l t loam Elevat ion: 750' schistose t i l l Aspect: north Landform: morainal veneer Drainage: moderately w e l l , minor rece iv ing . Slope: 25% C l a s s i f i c a t i o n : Orthic Humo-ferric Podzol 10 - 7.5 LF variegated mix of coniferous twigs and needles; loose mat; no roots ; abrupt, wavy boundary to , 7 . 5 - 0 H dark reddish brown (5YR 2/2m) muck; amorphous; abundant roots and mycel ia; abrupt, wavy boundary to , 0 - 5 Ae l i gh t gray (2.5Y 6/0 and 7/0d) coarse s i l t loam; clean gra ins , sharp f e e l ; f i rm , moist; non-st icky, s l i g h t l y p l a s t i c , wet; abundant roots; abrupt, wavy boundary to , 5 - 2 0 Bfh l i gh t o l i ve brown (2.5Y 5/4d) and l i gh t ye l lowish brown (2.5Y 6/4d) s i l t loam; moderate, medium and coarse subangular blocky; f i rm, moist; non-st icky, s l i g h t l y p l a s t i c , wet; common roots ; c l e a r , wavy boundary to , 20 - 35 Bf x l i gh t yel lowish brown (2.5Y 6/4d) gravel ly sandy loam 35 - 50 B f 2 to gravel ly s i l t loam with patches of gray (2.5Y 5/0d) 50 - 65 Bf 3 weathering t i l l ; moderate, medium and coarse subangular 65 - 80 Bf^ blocky; f i rm when moist; non-st icky and non-p las t ic , wet; common roots , gradual, wavy boundary t o , 80 - 95 Bf •! o l i ve gray (5Y 5/2d) and grayish brown (2.5Y 5/2d) 95 - 110 Bf gravel ly s i l t loam; moderate, medium and coarse, g j 2 subangular blocky; f i rm , moist ; non-st icky, s l i g h t l y p l a s t i c , wet; common, medium and coarse prominent o l i ve (5Y 5/4d) mott les; common roots; abrupt, wavy boundary to , 110+ C gray (2.5Y 6/0d) gravel ly s i l t loam parent t i l l ; s t ructureless-massive; extremely f i rm, moist; non-s t i c k y , non-plast ic when wet; no roots. VEGETATION COVER AT THE MODAL SOIL PITS 147 Modal So i l P i t Trees: Pseudotsuga menziesii Tsuga heterophylla Abies amabilis Thuja plicata Picea sitchensis Pinus monticola Taxus brevifolia Prunus emarginata AD 3 4 AW 4 1 2 BD 4 2 BW 3 3 GD 3 2 GW 1 + LW 4 2 1 + SW 2 2 2 Shrubs: Gaultheria shallon Vaccinium alaskaense Vaccinium parvifolium Mahonia nervosa Rubus spectabilis Sambucus pub ens Rubus macropetalus Herbs: Polystichum munitum Blechnum spicant Dryopteris austriaca Pteridium aquilinum Gymnocarpium dryopteris Athyrium filix-femina Achlys triphylla Tiarella trifoliata Cornus canadensis Disporum oreganum 2 + 1 + 1 2 + + + + 1 1 + 1 + + 1 + 1 2 1 1 2 1 + + + + 2 2 2 148 Herbs, Continued: Linnaea borealis Chimaphila wnbellata Trillium ovatum Streptopus amplexifolius Pyrola secunda Adenooaulon bioolor Trientalis latifolia Viola glabella Laotuoa muralis Mosses: Eurhynchium oreganum Hyloeomium splendens Rhytidiadelphus loreus Mnium glabrescens Mnium insigne Plagiothecium undulatum Plagiothecium elegans (?) Isotheciwn stoloniferum Dicranum fuscescens(?) Polytrichum juniperinum Sphagnum sp. Cladina spp. Modal So i l P i t AD AW BD BW GD GW LW SW 2 1 + + + + + + + 1 5 1 1 1 + + + + + 5 2 1 1 + 1 1 1 1 1 + 1 + Key: + = less than 1%; 1 = 1-5%; 4 = 51-75%; 5 = 76-100%. 2 = 6-25%; 3 = 26-50%; 149 APPENDIX 2 - 1 The nutr ient status of the s o i l s . NUTRIENT CONTENT WITHIN THE LFH HORIZON - ALL VALUES IN KILOGRAMS PER HECTARE Plot O.M. N total P ava i l . S Ca Mg K Na Cu Zn Fe Mn AD 1 166,000 816 13 90 317 352 114 4 2 5 1,150 99 2 211,000 1,560 15 143 371 278 127 13 3 5 1,070 89 3 103,000 794 7 65 175 288 156 .9 1 4 801 116 4 243,000 1,910 16 173 463 505 139 12 1 8 1,600 245 5 145,000 1,290 9 133 938 223 136 11 1 9 631 297 AW 1 533,000 6,990 13 553 1,740 769 416 87 6 14 2,240 383 BD 1 211,000 1,860 6 159 398 334 75 18 3 9 1,240 171 2 185,000 1,300 5 148 251 355 75 16 3 • 7 1,280 121 3 56,400 352 2 35 246 97 43 5 1 3 424 112 4 568,000 ' 5,860 21 470 1,840 811 371 36 5 12 1,490 237 BW 1 1,010,000 10,200 42 1,030 2,410 1,060 351 104 3 37 2,740 159 ' 2 704,000 8,370 25 734 1,530 436 201 61 7 13 1,070 161 3 354,000 4,040 15 358 869 467 198 33 4 13 1,550 337 4 1,190,000 13,900' 21 1,320 2,460 1,290 473 100 14 22 4,040 211 •5 948,000 11,600 17 1,340 2,050 933 385 79 8 18 1,050 153 GD 1 40,400 231 1 24 • 202 32 32 3 0 1 128 17 2 219,000 1,500 7 134 932 155 156 13 2 3 490 331 3 352,000 2,450 13 303 1,930 297 224 19 2 12 1,090 268 4 390,000 4,470 16 337 2,050 245 256 15 2 18 336 163 5 391,000 2,570 13 176 1,140 241 161 17 4 9 1,100 211 GW 1 423,000 4,650 15 407 1,530 541 235 49 4 12 1,430 94 2 444,000 2,860 14 273 1,490 456 150 36 4 18 1,010 175 3 472,000 3,970 24 397 831 555 186 47 5 12 1,290 84 LW 1 219,000 2,600 16 222 622 295 134 16 3 8 955 182 2 631,000 6,370 15 565 845 808 249 112 4 10 1,660 233 3 590,000 7,410 19 693 1,190 766 284 103 6 12 2,500 307 4 336,000 4,360 17 420 839 536 240 64 3 10 1,130 344 5 407,000 6,070 25 478 1,480 677 256 26 6 13 2,970 515 SW 1 459,000 3,700 21 448 747 492 238 22 5 14 1,460 184 2 151,000 1,210 8 144 155 246 91 12 1 5 955 98 3 231,000 2,090 13 186 351 274 127 10 2 8 853 139 4 94,900 1,100 5 95 201 149 70 6 1 3 615 3 4 -5 284,000 3,310 16 310 1,030 460 146 20 3 10 1,080 123S NUTRIENT CONTENT WITHIN THE UPPER B HORIZON - Al VALUES IN KILOGRAMS PER HECTARE O.M. Riot total P S available total Ca Mg K exchangeable Na Cu Zn Fe -- available -Mn AD 1 2 3 4 5 AW 1 BD 1 2 3 4 BW 1 2 3 4 5 GD 1 2 3 4 5 1 2 3 1 2 3 4 5 1 2 3 4 5 GW LW SW 91,600 125,000 73,500 94,800 48,600 483,000 115,000 148,000 81 ,700 154,000 124,000 187,000 239,000 243,000 186,000 70,100 89,200 101,000 88,400 101,000 200,000 109,000 269,000 310,000 179,000 234,000 220,000 228,000 134,000 95,200 153,000 195,000 187,000 2,040 2,810 1,820 2,220 938 10,600 2,150 2,910 1,240 3,280 2,740 4,210 5,560 3,940 3,320 1,770 1,870 1,650 1,390 1,790 4,480 1,870 7,230 7,950 3,140 4,980 4,420 5,250 3,370 2,750 4,180 4,680 4,970 36.4 8.56 28.0 30.4 27.3 202 627 181 269 90.3 391 22.2 243 48.0 562 65.5 25.1 39.8 30.0 114.0 6.02 1,480 591 218 6.34 335 230 48.2 10.5 403 626 94.5 77.4 496 617 74.5 12.8 331 204 55.2 2.95 848 49.9 39.3 2.93 512 1,030 197 5.44 544 354 88.7 .19 573 60.2 58.2 1.13 652 9.47 50.6 91.9 136 958 58.0 76.6 161 866 51.0 55.3 193 876 73.9 11.6 151 562 40.3 10.3 176 733 54.4 3.74 687 1.74 27.5 5.72 278 51.1 35.7 7.30 956 17.7 41.3 107 1,030 268 108 5.92 493 37.8 84.0 9.11 790 N.D. 65.0 12.8 683 283 149 21.9 624 2,600 184 12.2 852 16.2 50.4 68.7 581 12.3 39.1 60.0 651 82.5 50.1 6.20 716 8.28 36.8 11.8 846 18.8 40.8 98.1 77.9 76.7 76.1 125 183 48.2 84.5 114 57.6 36.1 61.3 72.5 25.7 33.3 153 132 98.5 47.2 53.0 37.4 51.4 E9.0 104 28.1 42.8 60.9 92.5 230 269 203 162 94.5 16.9 17.0 11.6 13.8 19.2 121 162 79.5 20.1 22.6 31.8 38.5 45.5 21.6 17.4 31.3 22.3 27.3 20.8 18.7 25.0 26.7 43.4 53.2 39.2 47.5 60.6 51.9 34.4 35.2 33.6 25.3 71.0 1.59 1.00 1.36 2.13 1.94 .53 4.67 7.35 5.61 6.01 2.49 3.40 1.73 2.21 2.60 6.47 4.52 5.19 3.09 4.81 .83 1.59 1.89 4.10 4.75 3.22 4.67 1.56 3.74 6.27 4.78 1.38 2.55 1.93 I. 48 9.26 2.36 2.95 11.8 2.86 4.25 3.65 7.18 3.27 6.43 15.5 5.02 2.36 2.72 4.52 4.37 4.00 5.62 2.48 3.52 5.60 9.09 6.10 7.47 7.60 8.77 9.68 10.9 II. 7 6.61 7.45 158 151 144 199 141 261 114 185 115 261 115 200 215 175 247 93.0 134 139 131 152 120 175 106 354 592 418 833 356 234 360 386 233 ' 207 33.2 15.3 33.8 31.7 51.3 10.0 91.8 33.6 58.2 16.8 4.97 15.0 22.6 2.74 2.46 35.7 44.6 40.4 12.5 19.9 1.63 3.59 5.23 37.6 3.98 12.2 19.4 25.1 6.08 26.2 23.4 14.7 -5.10 2 NUTRIENT CONTENT WITHIN THE LOWER B HORIZON - ALL VALUES IN KILOGRAMS PER HECTARE Plot ' O.M. N P available s total Ca Mg K Na Cu Zn Fe Mn total AD 1 52,900 1,460 48. 1 225 237 35.2 157 20.3 1. 16 19.4 96.3 • 17.1 2 49,500 1,630 9. 26 843 11.7 10.2 45.7 13. 4 2. 75 2.63 71.7 7.94 3 34,200 973 22. 1 135 132 18.7 33. 1 • 7. 08 . 71 .94 60.2 13.3 4 24,400 686 19. 9 203 17.3 8.9 23. 6 5. 95 1. 25 1.06 34.5 5.87 5 27,600 643 30. 7 76.3 439 71.9 104 14. 6 2. 19 2.04 85.4 11.7 AW 1 262,000. 6,360 3. 27 971 346 95.7 104 77. 6 15 4.29 85.8 4.42 BD 1 51,300 1,110 23. 1 760 58.6 10.9 17. 6 23. 8 1. 62 1.30 26.2 4.61 2 91,100 1,800 6. 45 205 253 39.2 34. 4 35. 9 4. 45 3.03 64.4 8.83 3 30,800 682 '34. 7 131 323 38.3 46. 2 18. 1 5. 51 1.12 55.8 18.4 4 44,400 929 4. 92 79.3 55.6 12.9 12. 9 6. 08 2. 02 1.67 40.4 6.12 BW 1 12,900 281 33 140 21.3 6.65 3. 94 3. 97 53 .50 11.5 .68 2 90,500 2,280 2. 17 245 445 130 42. 4 23. 6 1." 94 3.11 54.0 9.18 3 82,300 2,530 2. 37 . 204 289 44.8 30. 9 19. 7 1. 09 5.62 40.2 10.3 4 0 0 0. .0 0 0.0 0.0 0. .0 0. 0 0. 0 0.0 0.0 0.0 5 8,190 173 14 36.5 6.34 2.81 1. 26 1. 11 25 .30 5.12 .13 GD 1 21,900 672 53. .5 40.7 449 22.3 71. 6 23. 4 5. 19 2.29 23.9 6.92 2 29,300 • 824 48.6 95.4 362 19.0 67. 8 14. 0 2. 91 1.04 41.7 12.5 3 40,700 989 35. .6 76.1 534 45.1 48. 3 17. 5 2. 90 • 1.52 46.7 13.7 4 35,000 657 7. 37 40.2 177 13.9 21. .0 7. 71 2. 15 2.11 37.2 4.40 5 45,200 965 6. 74 108 332 • 23.3 29.3 13. 4 4. 08 2.71 33.4 4.83 GW 1 130,000 3,470 5. 49 486 N.D. 10.6 17. ,1 22. 9 56 1.84 57.6 .62 2 31,900 629 2. ,80 142 16.0 17.6 19. .6 8. 14 71 .87 29.6 1.84 3 170,000 5,100 7. 41 671 14.0 14.9 27. 3 28. 1 1.' 18 2.44 43.2 4.40 LW 1 292,000 7,140 204 1,120 218 61.4 72. 7 61. 1 6. 51 10.4 287 39.5 2 54,400 1,080 3. 71 211 5.95 17.6 10. ,2 11. 1 1. 17 1.09 145 1.29 3 145,000 3,670 7. .24 998 288 34.7 25. ,7 32. 8 1. 86 4.60 163 12.8 4 142,000 3,590 14. ,1 655 150 53.9 31. 5 30.1 1. 36 2.82 183 17.2 5 143,000 4,750 32. ,6 592 3,220 135 83. ,3 40. 8 1. 36 24.9 131 23.1 SW 1 119,000 2,840 12. ,9 593 34.3 27.7 183 26. 2 3. 48 5.47 132 4.29 2 50,200 1,870 103 601 12.7 21.2 272 29.1 6. ,17 11.3 167 13.4 3 • 72,800 2,150 78. ,0 477 N.D. 13.4 139 22. 5 • 4. 59 4.90 117 9.35 4 146,000 4,080 •7. ,95 933 N.D. 18.6 132 24. .6 1. .99 7.88 132 7.34 5 215,000 5,550 22. .2 982 N.D. 22.4 72. .0 52. ,9 • 1. .46 5.83 123 2.52 NUTRIENT CONTENT WITHIN THE MINERAL SOIL - ALL VALUES IN KILOGRAMS PER HECTARE O.M. N P S Ca Mg K Na Cu Zn Fe Mn Plot total available total — exchangeable - available AD 1 145,000 3,500 84.6 426 628 101 255 37.2 2. 76 21. ,3 254 50. ,3 2 175,000 4,440 17.8 1,470 33.9 35.3 124 30.4 3. 75 4. ,10 223 23. 2 3 108,000 2,790 50.1 316 375 58.5 110 18.6 2. 07 10. .2 204 47. 1 4 119,000 2,910 50.3 472 65.3 38.9 99. 7 19.7 3. 38 3. 41 233 37. .6 5 76,300 1,580 58.0 167 1,000 186 229 33.8 4. 14 4. .99 226 63. .0 AW 1 745,000 16,900 9.29 2,450 938 314 286 199 68 16. ,1 346 14. ,4 BD 1 167,000 3,260 29.5 1,090 288 59.2 65. .8 186 6. 29 • 4. ,17 140 96. ,4 2 239,000 4,710 16.9 608 885 134 119 115 12. 3 7. ,28 250 47. 4 3 112,000 1,920 112 627 940 113 160 38.2 11. 1 4. ,76 171 76. .6 4 193,000 4,200 17.7 410 260 63.1 70. 5 28.6 8. 03 8. 84 301 22. ,9-BW 1 136,000 3,020 3.28 983 71.2 45.9 39. .9 35.8 3. 02 3. 77 127 5. 55 2 277,000 6,500 5.10 758 1,480 327 104 62.1 5. 34 9. ,54 254 24. 2 3 321,000 8,090 ' 7.81 748 643 133 103 65.1 2. 32 21. ,1 255 32. 9 4 243,000 3,940 .19 573 60.2 58.2 25. 7 21.6 2. 21 5. 02 175 2. ,74 5 194,000 3,490 1.27 688 15.8 53.4 34. 5 18.5 2. 85 2. ,66 253 2. 63 GD 1 92,100 2,440 145.0 177 1,410 80.2 225 54.7 11. 7 5. ,01 117 42. 6 2 119,000 2,690 125.0 257 1,230 69.9 200 36.2 7. 42 5. 56 176 57. 2 3 142,000 2,630 90.9 269 1,410 119 147 44.8 3. 09 5. 90 185 54. .1 4 123,000 2,040 19.0 191 739 54.2 68. 1 28.5 5. 24 6. ,11 168 16. ,9 5 146,000 2,750 17.6 284 1,070 77.7 82. 3 32.1 8. 89 8. ,33 186 24. .7 GW 1 329,000 7,950 9.23 1,170 1.74 38.1 54. .5 48.9 1. 39 4. ,32 178 2. ,26 2 141,000 2,500 8.53 420 67.1 53.3 71. .0 34.8 2. .29 4. ,39 205 5. ,43 3 439,000 12,300 14.7 1,630 31.6 56.2 86. 3 71.5 3! 06 8. ,04 149 9. .63 LW 1 601,000 15,100 310 2,150 486 170 177 114 10. ,6 19. ,4 1,140 77. 1 2 233,000 4,220 9.63 705 4c. 7 102 38. .2 50.3 5. 92 7, .19 737 5. ,27 3 379,000 8,650 16.4 1,790 288 100 68. 5 80.3 5. ,08 12, ,1 587 24. .9 4 363,000 8,010 26.9 1,340 433 202 92. 4 90.7 6. 03 10, .4 1,016 36. ,6 5 371,000 9,990 54.5 1,220 5,820 320 176 92.8 2. ,92 33. .6 487 48. ,1 SW 1 253,000 6,210 25.1 1,450 50.4 78.2 412 60.6 . 7. ,22 15. ,2 365 10. .4 2 145,000 4,620 171 1 ,-180 24.9 60.2 541 64.3 12. ,4 22. .2 527 39. ,6 3 226,000 6,340 138 1,130 82.5 63.5 341 56.1 9. ,37 16. .6 503 ' 32. .7 4 341,000 8,760 14.2 1,650 8.28 55.4 293 49.9 3. 37 14. .5 365 22. ,1 5 402,000 10,500 34.1 1,830 18.8 63.2 166 124 4. ,01 13. .3 330 7. .62 154 APPENDIX 3 - 1 The optimum number of samples required to meet an allowable error at the 95 percent confidence l e v e l , derived from variance estimates which encompass 50 percent (median), 75 percent and 90 percent of the observed range in the estimated variances. Coeff icents of var ia t ion and the percent error when 16 samples are taken as in th is study are also presented. is'4 APPENDIX 3 - 1 Variance Level % S X C V . n. % Error (n = 16] Dry 90 .35 4.75 .074 5 3.9 75 .25 .053 4 2.8 50 .17 .036 3 1.9 Wet 90 .59 4.54 .130 9 6.9 75 .36 .079 5 4.2 50 .17 .037 3 2.0 ALL 90 .56 4.63 .121 8 6.4 75 .31 .067 5 3.6 50 .17 .037 3 2.0 Dry 90 .99 2.29 .432 74 23.0 75 .71 .310 39 16.5 50 .48 .210 19 11.2 Wet 90 3.27 4.62 .708 195 37.7 75 1.84 .398 63 21.2 50 .71 .154 12 8.2 ALL 90 2.03 3.63 .559 123 31.4 75 1.21 .333 45 17.7 50 .65 .179 15 9.5 Dry 90 .057 .090 .633 157 33.7 75 .025 .278 32 14.8 50 .017 .189 16 10.1 Wet 90 .108 .185 .584 134 31.1 75 .071 .384 59 20.4 50 .034 .184 15 9.8 ALL 90 .082 .145 .566 126 30.1 75 .051 .352 50 18.7 50 .023 .159 12 8.5 156 APPENDIX 3 - 1 , Continued Variance _ % Error Level % S X C V . n. (n = 16) Dry 90 .0060 .013 .462 85 24.6 75 .0040 .308 39 16.4 50 .0020 .154 12 8.2 Wet 90 .0221 .030 .737 211 39.2 75 .0181 .603 143 32.1 50 .0079 .263 29 14.0 ALL 90 .0201 .023 .874 294 46.5 75 .0099 .430 73 22.9 50 .0040 .174 14 9.3 Dry 90 6.99 15.8 .442 77 23.5 75 5.01 .317 41 16.9 50 3.20 .203 18 10.8 Wet 90 6.59 7.8 .845 277 45.0 75 3.20 .410 67 21.8 50 1.61 .206 19 11.0 ALL 90 6.99 11.2 .624 153 33.2 75 4.61 .412 67 21.9 50 1.81 .162 13 8.6 Dry 90 .600 0.91 .659 170 35.1 75 .441 .485 92 25.8 50 .241 .265 29 14.1 Wet 90 1.361 0.67 2.031 1,585 108.2 75 .700 1.045 420 55.6 50 .260 .388 60. 20.7 ALL 90 1.980 0.77 2.571 2,539 136.9 75 .600 .779 236 41.5 50 .260 .338 46 18.0 Dry 90 .221 0.19 1.163 520 61.9 75 .119 .626 151 33.3 50 .051 .268 30 14.3 Wet 90 .541 0.26 2.081 1,664 110.8 75 .201 .773 232 41.2 50 .099 .381 58 20.3 ALL 90 .506 0.23. 2.200 1,859 117.1 75 .188 .817 259 43.5 50 .079 .343 48 18.3 APPENDIX 3 - 1 , Continued 157 Variance Level % S X C V . n. % Error (n = 16) Dry 90 .040 0.10 .400 64 21.3 75 .040 .400 64 21.3 50 .020 .200 18 10.6 Wet 90 .099 0.093 1.065 436 56.7 75 .040 .430 73 22.9 50 .020 .215 20 11.4 ALL 90 .074 0.10 .740 213 39.4 75 .040 .400 64 21.3 50 .020 .200 18 10.6 Dry 90 .020 0.06 .333 46 17.7 75 .020 .333 46 17.7 50 .000 .000 1 0.0 Wet 90 .040 0.08 .500 98 26.6 75 .020 .250 26 13.3 50 .020 .250 26 13.3 ALL 90 .040 0.07 .571 128 30.4 75 .020 .286 34 15.2 50 .020 .286 34 15.2 Dry 90 6.50 8.85 .734 209 39.1 75 3.55 .401 64 21.4 50 2.00 .226 22 12.0 Wet 90 3.95 6.15 .642 162 34.2 75 2.55 .415 68 22.1 50 1.55 .252 27 13.4 ALL 90 3.95 7.30 .541 115 28.8 75 2.80 .384 59 20.4 50 1.70- .233 23 12.4 Dry 90 1.70 2.20 .773 232 41.2 75 1.01 .457 83 24.3 50 .50 .225 22 12.0 Wet 90 3.81 2.90 1.312 661 69.9 75 2.71 .933 334 49.7 50 .91 .312 40 16.6 ALL 90 3.61 2.55 1.416 770 75.4 75 1.90 .743 214 39.6 50 0.70 .273 31 14.5 158 APPENDIX 3 - 1, Continued Variance _ % Error Level % S X C V . n. (n = 16) Dry 90 43.22 58.64 .737 211 39.3 75 32.01 .546 117 29.1 50 21.61 .368 54 19.6 Wet 90 148.08 97.92 1.512 878 80.5 75 56.83 .580 132 30.9 50 28.02 ;.286 34 15.2 ALL 90 56.83 81.28 .699 190 37.2 75 43.22 .532 111 28.3 50 25.94 .319 42 17.0 Dry 90 16.16 13.20 1.224 576 65.2 75 8.08 .612 147 32.6 50 5.12 .388 60 20.7 Wet 90 7.04 4.43 1.589 970 84.6 75 4.64 1.047 421 55.8 50 2.16 .488 94 26.0 ALL 90 8.64 8.15 1.060 432 56.5 75 6.88 .844 274 45.0 50 3.20 .393 62 20.9 

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