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Effects of fertilization on the nutrient and organic matter dynamics of reclaimed coal-mined areas and… Ziemkiewicz, Paul F. 1979

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I EFFECTS OF FERTILIZATION ON THE NUTRIENT AND ORGANIC MATTER DYNAMICS OF RECLAIMED COAL-MINED AREAS AND NATIVE GRASSLANDS IN SOUTHEASTERN BRITISH COLUMBIA Paul F. B.S. Utah State M.S. Utah State by Ziemkiewicz Un ivers i ty , 1973 Un ivers i ty , 1975 A THESIS SUBMITTED IN PARTIAL FULFILLMENT OF • THE REQUIREMENTS FOR THE DEGREE OF DOCTOR OF PHILOSOPHY in THE FACULTY OF GRADUATE STUDIES (Faculty of Forestry, Univers i ty of B r i t i s h Columbia We accept th i s thesis as conforming to the required standard THE UNIVERSITY OF BRITISH COLUMBIA October, 1979 (c) Paul F. Ziemkiewicz, 1979 In presenting th i s thesis in pa r t i a l fu l f i lment of the requirements for an advanced degree at the Univers ity of B r i t i s h Columbia, I agree that the Library shal l make i t f ree ly avai lable for reference and study. I further.agree that permission for extensive copying of th i s thesis for scholarly purposes may be granted by the Head of my Department or by his representatives. It i s understood that copying or publ icat ion of th i s thesis for f inanc ia l gain shal l not be allowed without my written permission. Department of The Univers ity of B r i t i s h Columbia 2075 wesbrook Place Vancouver, Canada V6T 1W5 Ay t ABSTRACT Reclamation of coal mining disturbances has been undertaken on a large scale in B r i t i s h Columbia since 1972. Mining occurs pr imari ly in a narrow belt in southeastern B.C. from the international boundary northward para l le l to the continental divide to the headwaters of the Elk River at elevations of 1,000 m to 2*300 m. Since reclamation began, most treated areas have been f e r t i l i z e d annually as a precaution against reclamation f a i l u r e . While this practice has often maintained productive and at t ract ive reclamation s i tes i t was not known whether the maintenance f e r t i l i z a t i o n was necessary and what ef fect i t was having on plant community development. To answer these questions two productive reclaimed areas and two adja-cent native, undisturbed grasslands were selected. One set of plots was amid montane vegetation and the other amid subalpine vegetation. On each of the four s i t e s , paired plots were established and shoot, detr itus and root biomass levels were measured over a 14-month period. One of the paired plots was f e r t -i l i z e d in the spring. N, P and K analyses were done on so i l and plant samples so that organic matter and nutrient f lux in the four plant community compartments could be ex-pressed as mass per unit ground surface. Two phases in reclaimed area development, were i den t i f i ed . The develop-ment phase was characterized by detr itus accumulation and minor root mass turn-over in the f a l l . F e r t i l i z a t i o n had a profound influence on this phase mainly in stimulating shoot production though root production Was stimulated to a lesser degree. The withdrawal of maintenance f e r t i l i z a t i o n resulted in a severe drop in production and nutrient accumulation with a large part of yearly N and P up-take immobilized in surface detr itus by f a l l . The subalpine reclaimed area re-presented this phase. The data indicate that maintenance f e r t i l i z a t i o n w i l l be i i necessary to prevent degeneration of the plant community. The montane reclaimed area represented the mature phase of development. This phase may not indicate attainment of a steady state, but i t appeared to be capable of storing and cycl ing su f f i c i en t nutrients that withdrawal of maintenance f e r t i l i z a t i o n resulted in no apparent adverse e f fects . Rather, due to the mid-summer drought, f e r t i l i z a t i o n of this reclaimed area inhib i ted root production while i t stimulated shoot production. The additional shoot production could not be maintained through the dry period, so that shoot standing crop through the summer was not influenced by f e r t i l i z a t i o n . The native areas were characterized by massive root systems which caused the bulk of nutrient exchanges to occur within plant and from root to so i l to root. Thus the surface detr i tus system played a minor role in nutrient cycl ing re la t i ve to the reclaimed areas. F e r t i l i z a t i o n of natives areas stimulated shoot production and de t r i t a l decomposition so root:shoot rat ios narrowed and detr itus levels dropped after f e r t i l i z a t i o n . The reclaimed areas were less stable than the native areas in re lat ion to water and nutrient stress. However, the montane reclaimed area seemed s e l f -su f f i c i en t in. nutrients and should continue to develop without annual f e r t i l i z a -t ion. The subalpine reclaimed area i s not nutrient s e l f - s u f f i c i e n t and w i l l re -quire continued treatment. Dr. J . V. Thirgood Major Professor Dr. R. M. Strang Thesis Supervisor i i i TABLE OF CONTENTS Page ABSTRACT i TABLE OF CONTENTS i i i LIST OF FIGURES v i i LIST OF TABLES . v i i i ACKNOWLEDGEMENTS ix 1.0 INTRODUCTION 1 1.1 THE SETTING 1 1.2 THE PROBLEM 2 1.3 STATE OF THE ART 6 1.4 THE APPROACH 6 2.0 THEORY 7 2.1 ENERGETICS 7 2.2 NUTRIENT CYCLING 8 3.0 LITERATURE REVIEW n 3.1 ENERGETICS AND NUTRIENT CYCLING 11 3.1.1 A rc t i c Tundra 11 3.1.2 Alpine Tundra 14 3.1.3 Temperate Grasslands 18 3.2 ROLE AND DYNAMICS OF NUTRIENTS IN PLANT COMMUNITIES 20 3.2.1 Nitrogen 20 3.2.2 Phosphorus 22 3.2.3 Potassium 22 4.0 METHODS AND MATERIALS 23 4.1 THE STUDY AREA . . . . 23 4.2 EXPERIMENTAL DESIGN 26 4.3 THE STUDY SITES 29 i v Page 4.3.1 Reclaimed Areas 29 ~ 4.3.2 Native Grasslands .32 4.4 Sampling 33 5.0 RESULTS 34 5.1 TEMPORAL DISTRIBUTION OF ORGANIC MATTER 34 5.1.1 Montane Native Grassland 34 5.1.2 Montane Reclaimed Area 36 5.1.3 Subalpine Native Grassland 40 . 5.1.4 Subalpine Reclaimed Area 42 5.2 NET CHANGES IN ORGANIC MATTER •. 45 5.3 NUTRIENT CONCENTRATIONS 50 5.3.1 Nitrogen 50 5.3.2 Phosphorus 52 5.3.3 Potassium 53 5.4 TEMPORAL DISTRIBUTION OF NITROGEN 55 5.4.1 Montane Native Grassland 55 5.4.2 Montane Reclaimed Area 61 5.4.3 Subalpine Native Grassland 63 5.4.4 Subalpine Reclaimed Area 64 5.5 TEMPORAL DISTRIBUTION OF PHOSPHORUS 66 5.5.1 Montane Native Grassland 66 5.5.2 Montane Reclaimed Area 69 5.5.3 Subalpine Native Grassland 71 5.5.4 Subalpine Reclaimed Area 71 5.6 TEMPORAL DISTRIBUTION OF POTASSIUM 72 5.6.1 Montane Native Grassland 72 5.6.2 Montane Reclaimed Area 74 5.6.3 Subalpine Native Grassland 77 5.6.4 Subalpine Reclaimed Area 78 V Page 5.7 NITROGEN DYNAMICS 79 5.7.1 Montane Areas 80 5.7.2 Subalpine Areas 82 5.8 PHOSPHORUS DYNAMICS 82 5.8.1 Montane Areas 82 5.8.2 Subalpine Areas 86 5.9 POTASSIUM DYNAMICS 88 5.9.1 Montane Areas 88 5.9.2 Subalpine Areas 91 6.0 DISCUSSION 91 6.1 EFFECTS OF FERTILIZATION " 91 6.2 FATE OF APPLIED NUTRIENTS 97 6.2.1 Nitrogen 98 6.2.2 Phosphorus 101 6.2.3 Potassium 104 6.3 SUMMARY OF DISCUSSION 106 7.0 IMPLICATIONS FOR RECLAMATION 109 8.0 CONCLUSIONS 112 9.0 AREAS FOR FURTHER RESEARCH 115 10.0 LITERATURE CITED 116 11.0 BIBLIOGRAPHY 121 APPENDIX I N, P, K, Ca, Mg d i s t r ibut ion 128 APPENDIX II net changes in Ca and Mg masses 139 APPENDIX III p rec ip i tat ion during study 144 APPENDIX IV prec ip i tat ion during study 147 APPENDIX V mean monthly temperatures 150 APPENDIX VI monthly snowfall in study area (1973-1977) 153 Page -? -1 APPENDIX VII net change in organic matter (g m day ) 156 APPENDIX VIII nutrient concentrations in shoots, roots and d e t r i t u s . . . 159 vi i LIST OF FIGURES Page Figure 1. Map of Canada showing location of the study area 2 Figure 2. Model depicting energy flow through an ecosystem (after B a t z l i , 1974) 9 Figure 3. S impl i f ied model representing energy and nutrient flows through an ecosystem 10 Figure 4. Schematic diagram of plot layout 27 Figure 5. Shoot and detr itus masses on the montane native area 35 Figure 6. Root masses on the montane native and reclaimed areas 37 Figure 7. Shoot and detr itus masses on the montane reclaimed area 39 Figure 8. Shoot and detr itus masses on the subalpine native area 41 Figure 9. Root masses on the subalpine native and reclaimed area 43 Figure 10. Shoot and detritus masses on the subalpine reclaimed area 44 Figure 11. Shoot and detr itus N masses 56 Figure 12. Root N masses 57 Figure 13. Total so i l N masses 59 Figure 14. Soi l NO3 masses 60 Figure 15. Shoot and detr itus P masses 67 Figure 16. Root P masses 68 Figure 17. Soi l avai lable P masses 70 Figure 18. Shoot and detr itus K masses 73 Figure 19. Root K masses 75 Figure 20. Soi l avai lable K masses 76 vi i i LIST OF TABLES Page Table 1. Aer ia l standing crop by species on nine Kaiser Resources reclaimed areas 31 Table 2. F e r t i l i z a t i o n history of Lower C seam 30 Table 3. F e r t i l i z a t i o n history of the Assembly Pad 32 Table 4. Net change in shoot, detr itus and root masses on the montane areas 46 Table 5. Net change in shoot, detr itus and root masses on the subalpine areas 47 Table 6. N dynamics within shoot, det r i tus , root'and so i l compartments of the montane areas . . . . . 81 Table 7. N dynamics within shoot, det r i tu s , root and so i l compartments of the subalpine areas 83 Table 8. P dynamics within shoot, det r i tus , root and so i l compartments of the montane areas 85 Table 9. P dynamics within shoot, det r i tus , root and so i l compartments of the subalpine areas 87 Table 10. K dynamics within shoot, det r i tu s , root |and so i l compartments of the montane areas 89 i Table 11. K dynamics within shoot, det r i tus , root and so i l compartments of the subalpine areas 92 Table 12. Estimated f e r t i l i z e r N uptake, ef fect and ef f ic iency 99 Table 13. Estimated f e r t i l i z e r P uptake, ef fect and ef f ic iency 102 Table 14. Estimated f e r t i l i z e r K uptake, ef fect and ef f i c iency 105 ACKNOWLEDGEMENTS Many individuals and organizations co-operated to make th i s study a suc-ces. Deserving the utmost credit i s Mr. A. W. M i l l i gan , Director, Reclamation Department, Kaiser Resources Ltd. Without his help in arranging approvals, labor and f a c i l i t i e s this study would not have been possible. Also, deserving of special thanks is Dr. L. M. Lavkulich of the Soi l s Department, UBC for most generously providing the chemical analyses necessary for th is study. Without the support of these two individuals and the organizations which they represent this project would have remained a pipe dream. Many thanks are also due by Advisor, Dr. J . V. Thirgood and the other members of my committee: Dr. A. A. Bomke, Dr. V. C. Brink, Dr. J . P. Kimmins and Dr. R. M. Strang. These individuals provided excel lent advise and support throughout the study. I am par t i cu la r l y indebted to Dr. Strang for assuming the re spons ib i l i t i e s of Advisor during Thesis preparation. These acknowledgements would be incomplete without mention of the con-tr ibut ions made by members of my f i e l d crews. These individuals dug holes, sur-veyed p lots , pounded stakes, washed roots and clipped endlessly while the weather was invar iably too cold, too hot or too pleasant. Those who presevered with me the longest deserve special mention: Jennifer Hansen, Barbara Hunt, Ken MacDonald and Norman Johnson. Mr. Johnson's dedication and s k i l l in co l lec t ing Sample #6 portends a bright future in Biology. F ina l l y by deepest thanks to my wife, Chr i st ine, for her support and understanding, and for typing the draft copy of the Thesis. 1.0 INTRODUCTION 1.1 THE SETTING Coal mining in B r i t i s h Columbia has grown in recent years and has become a major component of the provincial economy. Production has increased from ab-out 1,000,000 t in 1969 to 11,000,000 t in 1973. This level has since been main-tained while value of the total product has increased from $6,800,000 in 1969 to $154,600,000 in 1975 (Warden, 1975). Most of the mining occurs in the Elk River Valley of southeastern B r i t i s h Columbia (Figure 1). Over 80% of B.C.'s coal i s extracted by surface mining met-hods. Two companies currently account for most of the production: Kaiser Resources Ltd. in Sparwood and Fording Coal Ltd. in Elkford. Most of the coal i s shipped under long-term contract to Japan for conversion to coke, the reduc-tion agent in the production of i ron. With 364,000 ha of the province under coal lease the potential for land use con f l i c t s and environmental damage i s great. The Elk Valley coal mines have been under part icu lar scrutiny by provincial agencies due to the large scale of the disturbances and the big game, f i sher ies and aesthetic values thus threatened. The Elk Valley i s in the extreme southeastern corner of B r i t i s h Columbia. Elevations of coal outcrops range from 1,000 to 2,200 m elevation and annual pre-c i p i t a t i on ranges from 600 to 1,400 mm. Prec ip i tat ion increases with elevat ion. Vegetation ranges from a lodgepole pine (Pinus contorta Dougl.)-Douglas f i r (Pseudotsuga menziesii (Mirbel) Franco) forest in the val ley bottom with i n te r -spersed grasslands and aspen (Populus tremuloides Michx.) forests to a subalpine f i r (Abies lasiocarpa (Hook.) Nutt.)-Engelmann spruce (Picea engelmannii Parry) dominated forest at higher elevations with grasslands occuring on west-facing slopes. (A l l taxonomy follows Hitchcock and Cronquist, 1973.) While the provincial government has required reclamation of these d i s -turbed areas, the mining companies have been responsible for developing approp-r ia te reclamation techniques. These have evolved into methods that, at least 2 Figure 1. Map of Canada showing location of the study area. in the short term, often give good resu l t s . After mining, spoi ls are recontoured to a maximum slope of 28°. No a t -tempt is made to store or reapply topso i l . Selected grass and legume seed (about 50 kg ha"*) are broadcast and about 200 kg ha"* of 13-16-10 f e r t i l i z e r applied and harrowed. The same amount of f e r t i l i z e r i s reapplied annually as an expensive precaution against reclamation f a i l u r e . This cautious approach is j u s t i f i e d in l i g h t of the lack of l i t e ra tu re concerning the rate at which overburden becomes capable of supplying the nutrient requirements of a plant community. 1.2 THE PROBLEM In reclamation leg i s l a t i on pertinent to North American wildlands, the term " se l f - susta in ing, productive plant cover" often defines land which has 3 been successfully reclaimed. The sel f -susta in ing state i s the goal of most re-clamation programs on non-cultivated land and represents the point at which the operator can recover the reclamation bond and return the land to the owner. If the land proves incapable of sustaining adequate plant cover the owner is re -sponsible for mitigation of resultant environmental impacts. In the milder climates of the eastern United States and Europe reclama-tion has been practiced long enough that a large body of information has deve-loped regarding the long-term behavior of reclaimed areas. (Bauer, 1973; Medvick, 1973). In western Canada we do not have the luxury of time and already one copper mining company in B.C. has col lected i t s reclamation bond while several western coal mines seem on the verge of terminating operations. So i t i s c r i -t i c a l that the provincial governments acquire techniques which w i l l allow at least an educated guess as to whether or not an area is indeed reclaimed. Other-wise the reclamation bond may be paid back to the operator on land that s t i l l requires cost ly reclamation work. The operators also might benefit from such techniques. For presently, maintenance f e r t i l i z a t i o n i s extremely cost ly and in many cases probably unnecessary or even harmful. If nutrient s e l f - s u f f i c i e n t areas could be i dent i f i ed a great savings in time, labor and precious f e r t i l i z e r would be rea l i zed. This study was conducted in the mountainous region of southeastern B r i t i s h Columbia. Study s i te elevations range from 1,500 to 2,100 m elevat ion. The region is subject to periodic summer droughts. The short, often cool and dry growing seasons impose constraints on the reclamation plant communities, and l i t t l e i s known about the f i tness of the agronomic grasses and legumes to these harsh conditions. Some authors (Bell and Meidinger, 1977) have suggested that these agronomic species cannot survive in the Rocky Mountains without i r r i ga t i on and continued f e r t i l i z a t i o n . Numerous species can survive without i r r i g a t i on but several factors m i l i t a te against the development of nutrient se l f - su f f i c i ency in this region. 1) Topsoil (LFH, Ah horizons) is scarce and, in B r i t i s h Columbia, 4 i t i s not replaced af ter coal mining. This forces reclamation to commence on nutrient-poor overburden and coal s po i l . Therefore, a large part of the re -clamation e f f o r t must be directed to accelerating the development of a so i l " i n  s i tu " and "reclamation" has become synonymous with accelerated succession. 2) The agronomic species used in reclamation have been, to varying degrees, bred and selected to meet the requirements of forage crops. These include maximization of shoot growth and maintenance of high nutrient qual i ty in the shoots. Soi l development in grass-forb communities i s dominated by the rate of fibrous root production and turnover. Root production, turnover and qual i ty are of c r i t i c a l importance in the reclaimed areas. Shoot production and, pa r t i cu l a r l y , surface detr itus production are also c r i t i c a l . For, i f inef fect ive translocation to the roots occurs pr ior to shoot death then carbohydrates and nutrients enter the detr itus pool. Ineffective translocation can result from frost or drought k i l l i n g of shoots pr ior to senescence. Once carbohydrates and nutrients enter the detr i tus system the i r fate i s largely determined by decomposers. I f decomposition operates at a high rate a great deal of de t r i t a l C w i l l leave the system as CO2 while the remainder w i l l become stable humic and f u l v i c acids. The i n f i l t r a t i o n of these organic acids into the so i l p r o f i l e i s a function of physical disturbance, cl imate, so i l tex-ture and so i l pH. In the dry, heavy and basic mine spoi ls of the study area the mobi l i ty of these organic acids i s l im i ted. Nutrients released in de t r i t a l de-composition then become avai lable to plants jus t below the so i l surface. The penetration of NO3 and NH4 i s largely determined by the rate of plant uptake and in the case of NH^ by so i l CEC as we l l . In a lka l ine so i l s P is v i r t u a l l y immobile beyond the so i l surface. Therefore, even with rapid de t r i t a l decomposition, in a system where nutrient return is largely in the form of surface detruitus, or-ganic acids and nutrients tend to remain near the surface. This results in de-velopment of a shallow and small root system with a l imited capacity to store carbohydrates and nutrients over winter or withstand summer drought. Soi l de-5 velopment would also be retarded as the organic compounds c r i t i c a l to develop-ment of the Ah horizon would be concentrated at the so i l surface. I f decomposition operates at a low rate as is often the case in cold or dry climates then so i l development is further retarded. In low decomposition environments detr itus tends to accumulate and acts as a nutrient and carbohydrate "s ink". Thus, in cold or dry environments the importance of in-plant cycl ing i s heightened. It i s , therefore, not surpris ing that tundra and grassland systems are characterized by large root:shoot rat ios and that f i r e is a c r i t i c a l factor in ox id iz ing accumulated detr itus and maintaining steady state. Many reclamation studies in the A r c t i c , Alpine and Subalpine have re-ported good i n i t i a l growth but poor persistence. (Brown et al_., 1976; Hu l l , 1974; Younkin, 1976). The decline in vigor is often matched by an accumulation of dead plant material on the so i l surface (Younkin, ib id . ) Usually, this decline in vigor is coincident with the withdrawal of f e r t i l i z a t i o n . While other factors undoubtedly contribute to this deter iorat ion, mineral nut r i t ion i s c r i t i c a l due to the depression of decomposition and nutrient cycl ing in cold regions (Hagg, 1972). Consequently, repeated f e r t i l i z a t i o n i s often required in these areas (Brown et al_.,. 1978). So, several c r i t i c a l factors emerged in assessing the nutrient s t a b i l i t y of the reclaimed area plant communities. What was the extent of in-plant nutrient cycling? Which ext ra -b iot ic exchange processes were dominant, root to shoot to detr itus or root to so i l to root? Dominance of the l a t t e r process would indicate more rapid so i l development. Native, undisturbed plots were valuable in demon-strat ing the type of processes which tend to maintain a productive steady state grassland in the region. Of part icu lar importance was the ef fect of f e r t i l i z a t i o n on these processes. Also, the effects of f e r t i l i z a t i o n on the rate of de t r i t a l decomposition, magnitude of the overwintering root mass and i t s annual turnover were c r i t i c a l in establ ishing the nutrient s t a b i l i t y of the reclaimed areas. 6 1.3 STATE OF THE ART Most of the long-term nutrient cycl ing work has come from forest ecology studies. In these studies the huge biomasses required sophisticated sampling methods and a great deal of manpower (Cole et al_., 1967; Kira and Shidei, 1967). Most tundra and grassland studies have extended for no more than one growing season so that overwinter root a t t r i t i o n and de t r i t a l changes could not be measured. Also, most studies were confined either to biomass or one or a few nutrients. The great majority of studies were intended to characterize the d i s -t r ibut ion of biomass in a system or individual plant compartments ( i . e . roots, shoots, de t r i tu s ) . In some studies nutrient concentrations in plant parts and detr itus were examined. These studies have developed the basis by which nutrient cycl ing can now be used as an hypothesis testing and predict ive too l . Such applications have already been made in forest ecology. The appl ication to reclamation plant ec-ology i s explored in this study. 1.4 THE APPROACH The approach taken in this study involved basing a l l estimates on b io-mass per unit area in the three predominantly organic compartments (root, shoot, det r i tus ) . Nutrient analyses were then made of the bulked samples as well as so i l samples so that, within each treatment, biomass, N, P, and K could be dimen-sioned as g rrf^. With the addition of a known amount of N, P and K as f e r t i l i z e r the fates of the added nutrients were estimated as the deviations from the un-f e r t i l i z e d paired p lot . Also, by using this method and sampling over a 14-month period the effects of f e r t i l i z a t i o n could be assessed as net accumulations to, and losses from, the various compartments. Two reclaimed areas and two native, undisturbed grasslands were included in the study. The native s i tes served as controls, indicat ing the effects of c l imat ic abberations on what were assumed to be stable plant communities. S t a b i l i t y was defined by the amplitude of system fluctuations (net pro-7 duct i v i t y , standing crop, nutrient levels) result ing from perturbations (Odurn, 1971a). Thus, using the native areas as representative steady state systems the effects of two major perturbations: f e r t i l i z a t i o n and c l imat ic extremes (however manifest) could be measured. The amplitude of f luctuations in the study parameters on reclaimed areas could then be compared to those of native areas. The degree to which these perturbations resulted in greater long-term impact on the plant communities was taken as a measure of the system's s t a b i l i t y . 2.0 THEORY A l l plant communities are essent ia l ly dynamic units through which energy and nutrients flow. In fac t , a plant community at any given time is th i s flow of energy and nutr ients, " frozen" for an instant. The mechanisms of energy f lux are photosynthesis and resp i rat ion, the creation and destruction of organic com-pounds. Nutrients other than carbon, hydrogen and oxygen flow through the com-munity in the i r own cycles. The instantaneous quantit ies of energy and nutrients in the system's b i o t i c , de t r i t a l and ab iot ic compartments represent the standing crop. Fluxes between compartments indicate the rate of energy flow and nutrient cyc l ing. 2.1 ENERGETICS Capture and a l locat ion of energy by the ecosystem are major functional character i s t i c s . Not only do these processes determine the quantity of biomass supported by the system, but also to a great extent, i t s organization. E. P. Odurn (1971b) defines th is relat ionship between structure and function: Organisms, ecosystems and the ent ire biosphere possess the essential thermodynamic character i s t ic of being able to create and maintain a high state of internal order or low entropy. Low entropy i s achieved by a continual d iss ipat ion of energy of high u t i l i t y ( l i gh t and food, for example) into energy of low u t i l i t y ( i . e . heat). In the ecosystem, "order" in terms of com-plex biomass structure is maintained by the total com-munity by respirat ion which continual ly "pumps out disorder". H. T. Odurn (1967), reviewing the works of Lotka (1925) and Schrodinger (1944), suggested that antithermal maintenance is of top p r i o r i t y in any complex 8 system of the real world. In the ecosystem the ra t io of tota l community re-spirat ion to the tota l biomass (R:B) can be considered as the rat io of main-tenance cost to structure. If R and B are expressed in calor ies and d i v i ded by absolute temperature, the R:B rat io becomes the rat io of entropy ( f ree energy) increase in maintenance to the entropy of ordered structure. Therefore, i t seems to fol low that as the biomass increases so does the maintenance cost. E. P. Odum (1971c) proposed that the gross primary production:respiration rat io is an index of ecosystem maturity. As succession proceeds the P:R ra t i o approaches one. This rule may not always apply to natural ecosystems, pa r t i cu la r l y those subject to frequent disturbance or extremely slow dynamics, ( i . e . tundra or desert). This argument, however, suggests the need for care in comparing net production data of systems in d i f ferent stages of succession. The energy f lux through a system i s a uni -d i rect ional energy flow within which minerals cycle. Batz l i (1974) has produced models describing these energy flows through various compartments of the ecosystem (Figure 2). This diagram was reworked into a form in which the major compartments in energy and nutrient flow could be measured. Figure 3 represents such a schem-a t i c energy flow diagram. In this approach four major compartments, representing l i v e shoot and root as well as detr itus (standing and f a l l en dead organic matter) and so i l serve as integrators of environmental or experimentally imposed con-d i t ions . Sampling of these compartments through the course of a year w i l l y i e l d net changes in mass. However, i t i s important to remember that the exchange pro-cesses indicated by the arrows may occur b i - d i r ec t i ona l l y and simultanteously. 2.2 NUTRIENT CYCLING The study of an ecosystem's energetics w i l l explain a great deal about i t s functioning and organization. However, the descriptive value of energy flow i s incomplete without some knowledge of the ecosystem's means of capturing and conserving nutr ients. E. P. Odum (1971d) indicated that as ecosystems progress toward climax, 9 (shortwave) TNSP TIM CO, TGP ARsp TNP HRsp NAcO HRsp TExM TERsp CO, (longwave) TEnF Thus: TGP=TGPrP+TGSP TNP=TNPrP+TNSP TERsp=TARsp+THRsp NAcO=TNP-THRsp+NTrM-TNSP NTrM=TIM-TExM Where: T=total G=gross P=production N=net Pr=primary S=secondary E=ecosystem Rsp=respiration A=autotroph H=heterotroph Ac=accumulation O=organic matter Tr=transported M=material I=imported Ex=exported F=flux En=energy Figure 2. Schematic diagram of energy flow through an ecosystem (after B a t z l i , 1974). 10 CO. shortwave radiation 60 c •H u CO CO, ongwave radiation respiration photosynthesis shoot o •H 4-1 cd u o tn c ca )-i 4-i 0J root senescence exudation sloughing leaching senescence -H •H N i CO i 3 •H detritus ~1 U—I grazers eluviation,leaching deep leaching erosxon Figure 3. A s impl i f ied model representing energy and nutrient flows through an ecosystem. 11 nutrient cycl ing becomes more e f f i c i e n t . Also, greater percentages of the cy-c l ing nutrients are contained in organic matter. The rates of nutrient exchange from one ecosystem compartment to another are more important in determining the structure of an ecosystem than the amounts present at a given time in various compartments. Therefore, cycl ing rates as well as standing crops of nutrients should be quantif ied. 3.0 LITERATURE REVIEW 3.1 ENERGETICS AND NUTRIENT CYCLING The two native grasslands in th is study were located amidst subalpine and montane vegetation types. L i t t l e work has been done on the productiv ity or nutrient cycl ing of grasslands in these vegetation zones. Consequently, the l i t -erature review w i l l concentrate on productiv ity and nutrient cycl ing studies most germane to the study areas: grasslands, a r c t i c tundra and alpine tundra. This should i l l u s t r a t e , by synthesis, the structural and functional r e l a t i on -ships and also, the special problems that might be expected in reclamation of the coal mining areas of B.C. Unfortunately, no comprehensive nutrient studies are avai lable from a l -pine areas. While some biomass d i s t r ibut ion data are avai lable for alpine and subalpine meadows, the nature of high-elevation nutrient cycles w i l l have to be inferred from the more extensive a r c t i c tundra and grassland studies. 3.1.1 A rc t i c Tundra Almost a l l of the aer ia l growth of tundra monocotyledeons is replaced annually. However, major portions of the root system may l i v e from two to ten years (Bunnell, et al_., 1975). S t i l l there i s a large production of organic matter, some of which undergoes rapid turnover. The greatest pool of energy resident to the a r c t i c tundra i s in the dead organic matter. Bunnell ( ib id. ) indicated that at Pt. Barrow, Alaska the top 20 cm of s o i l contained from 22 to 45 kg m"^ of det r i tus . The greatest accumu-lat ions of organic matter occurred where primary production was lowest. Detr i ta l 12 mass per unit area was 50 to 400 times greater than net primary production. Grazing has the ef fect of accelerating both energy flow and nutrient cyc l ing. Relative to primary production, grazing is probably more intense in the Barrow tundra than in most other systems. There, herbivory ranged from 1.7 to 700 kJ m" ^  y r over a f i ve year lemming cycle. Without grazing, most or-ganic substances lo s t 60% of the i r weight within three years following the i r death. This rate i s highly dependent on moisture and other microclimatic fac -tors. The cushion growth habit of some tundra plants may be adaptive to more rapid decomposition. There i s reason to believe that high a r c t i c cushion plants recycle products of the i r decomposition at a higher rate than other plants do (Svoboda, 1972). Cushion plants hold much of the organic matter under the cushion and new roots develop in this mass. Thus, a nutrient exchange system from roots to so i l to roots would seem optimized. The severity of the a r c t i c winter induces a low plant growth form. This minimizes energy and nutrient loss through t o p k i l l . Also, a great deal of the plant community's carbohydrate supplies are underground. Near Barrow, Alaska Dennis and Johnson (1970) estimated the rat io of below groundrabove ground standing crop to be 18:1. Muc (1972) found the same rat io to be 7.3:1 in sedge meadows on Devon Island. The data of Aleksandrova (1970 a&b) indicate root: shoot rat ios to be 4.8:1 and 7.2:1 in polar desert and a rc t i c tundra respectively in the USSR. McCown and Tieszen (1971) presented preliminary results of leaf analysis for low molecular weight carbohydrates and polysaccharides of three herbaceous species at Barrow, Alaska. Low weight carbohydrates ranged from 12 to 17% and polysaccharides from 20 to 30%. Muc ( ib id . ) and Svoboda ( ib id. ) on Devon Island found substant ia l ly less carbohydrate present both in roots and shoots of analyzed plants. Beach Ridge cushion plants contained only about 7% soluble carbohydrates at the peak. These data suggest caution in equating stored unavailable energy 13 ( i . e . ce l lu lose, l i gn in ) with avai lable stored energy ( i . e . soluble saccharides, starch). Mooney and B i l l i n g s (1965) found a tendency for carbohydrate content to decrease with increasing elevation. The data of Muc and Svoboda ( ib id. ) suggest that carbohydrate content and a v a i l a b i l i t y also decrease with increasing l a t i -tude. Like f ixed energy, plant nutrients are stored in the tundra's det r i tu s . Nutrient budgets of the Barrow, Alaska tundra to the depth of 10 cm reveal that most of the N and P i s in the so i l in a form unavailable to plants. Less than 1% of both N and P present in the system reside in the l i v i n g plants. There must be a cont inual , rapid turnover in the exchangeable and soluble nutrient pools within the growing season to maintain plant growth. To sat i s fy the demands of growing plants, soluble plus exchangeable N must "turn over" 11 times per growing season, while exchangeable P must be replaced 200 times per season or an average of three times a day. Su f f i c ient avai lable nutrients are not stored in the s o i l ; therefore, primary production ult imately depends on the rate of nutrient mobil ization through decomposition and internal cyc l ing. The po s s i b i l i t y of long-term nutrient loss in the tundra i s great, thus the importance of in-plant cyc l ing. In f ac t , most vascular plants at Barrow, Alaska show strong internal cycl ing of nutr ients, pa r t i cu la r l y P. In d r i e r , more effect ively-aerated so i l s at Barrow mycorrhizae further f a c i l i t a t e P main-tenance in vascular plants. Despite var iat ion in s o i l nutrient leve l s , plant concentrations of N, Ca and K are s imi lar among s i t e s , whereas P concentration was greatest on the most productive s i tes (Bunnell, et aj_. i b i d . ) . F e r t i l i z e r tests (Haag, 1973) in the low a rc t i c tundra near Tuktoyaktuk, NWT suggest that avai lable nitrogen is l im i t ing and that N f e r t i l i z a t i o n increases vascular plant production and protein content. P f e r t i l i z a t i o n had no such ef-fec t . The data, however, indicate that 10 weeks after f e r t i l i z a t i o n about 43 to 75% of the 100 and 200 kg h a - 1 P additions had either been f ixed in unavailable 14 form or had been leached from the rooting zone. Organic s o i l s , pa r t i cu la r l y those with low pH, can lose considerable P through leaching. Also, Fe ions made soluble by the low pH tend to f i x phos-phates in unavailable form. This potential loss of P and other nutrients from the system imposes strong select ive pressure in favor of nutrient conservation. It i s not sur-pr is ing that there are few annual plants in tundra f loras (B l i s s , 1971). In perennial plants, leaf Ca and Mg levels tend to remain constant throughout the growing season, result ing in a large addition of these elements to the detr itus pool upon death, whereas N and P tend to be translocated back to stem and roots before leaf f a l l (Reiners and Reiners, 1970). 3.1.2 Alpine Tundra Alpine tundras, l i k e the i r a r c t i c counterparts, are characterized by low annual energy budgets. Alpine climates are s imi lar in some respects to those of the a r c t i c but d i f f e r in the d i s t r ibut ion of rad iat ion, spectra l ly and tem-poral ly. Alpine areas also receive more snow, rain and wind with more intense sunlight and a higher proportion of u l t r av i o l e t radiat ion. Both a r c t i c and a l -pine environments are severe. However, the a r c t i c tundra may be more severe in winter due to the continuous heat loss and the lack of a deep, insulat ing snow cover. The alpine environment on the other hand may be more severe during the growing season with i t s high wind, high u l t r av i o l e t and cosmic radiat ion and i t s cold summer nights ( B i l l i n g s , 1970). As in the a r c t i c tundra, most of the biomass of the alpine tundra is present in the root system. The data of Thilenius (1975) suggest that this trend i s more pronounced in alpine tundra than in subalpine meadows. The root biomass data reported by Thilenius were higher than those noted by other workers. This difference was attr ibuted to more e f fect i ve sampling techniques. B l i s s (1963) reported underground biomass to be 3,634 g m~2 in an alpine mesic sedge meadow. Scott (1963) reported 1,400 g m"2 for the underground 15 biomass of an alpine mesic s i te and 750 g m~2 for a xer ic s i te in the Medicine Bow Mountains of Wyoming. However, the depth to which roots were sampled was not indicated. The roots of alpine plant communities are concentrated near the so i l surface. Rehder (1976) indicated that alpine ver t i ca l root d i s t r ibut ion was roughly 85% from 0-5 cm, 11% from 5-10 cm and 3% 10-15 cm. Knight and Kyte (1975), working in the Medicine Bow Mountains, reported a higher annual rate of l i t t e r decomposition (44%) than was noted by Bunnell, et aj_., (1975) in a r c t i c tundra (30%). Knight and Kyte also indicated that 70 to 80% of the annual l i t t e r decomposition occurred during the winter and that so i l was unfrozen under the snow. Despite the s l i gh t l y higher decomposition rate reported by Knight and Kyte, accumulations of organic matter s imi lar to those of the Barrow, Alaska tundra were reported by B l i s s (1956) in the Medicine Bow Mountains. Kuramoto and B l i s s (1970), working in the Olympic Mountains, also found considerable ac-cumulations of organic matter in so i l s of subalpine meadows. A gradient of i n -creasing organic matter seemed to coincide with colder and wetter microenviron-ments. , Soi l s of the subalpine meadows studied by Kuramoto and B l i s s were mostly young and poorly developed. Most important in retarding development i s f i r e , pa r t i cu la r l y in the dr ie r microsites (Fonda and B l i s s , 1969)'. Fire results in destruction of organic matter and erosion. This lowers the a b i l i t y of the A-horizon to absorb and retain water and to maintain a steady nutrient budget (Ahlgren and Ahlgren, 1960). The abbreviated growing season also tends to re-tard so i l development. Brooke (1965) estimated 11,000 to 18,500 years as the time required to accumulate 1 m of organic matter in low moor subalpine com-munities in Garibaldi Park, B.C. Unfortunately, there has not been a study for alpine tundra comparable to the A rc t i c Tundra Biome Project. Consequently, there i s i n su f f i c i en t i n fo r -16 mation on integrated community resp i rat ion, photosynthesis and organic matter accumulation to propose an energy flow model for alpine tundra. The carbohydrate cycles of several alpine species over the course of a year were studied by Mooney and B i l l i n g s (1965). The growth of these species was found to be quite rapid, in some cases commencing under the snow. The be-low-ground portions of the plants contained r e l a t i ve l y Targe proportions of the carbohydrate reserves. A high percentage of these reserves was u t i l i z e d in growth immediately following snowmelt. F i f t y percent of the rhizome carbohydrate reserves was spent in a one-week period of early growth. Except for th i s short period of rapid depletion in below-ground reserves, high levels of carbohydrates were maintained in above and below-ground parts throughout most of the growing season. Usually the carbohydrate reserve reached a nadir just before flowering, while peak storage occurred at the onset of f a l l dormancy. The carbohydrate cycle in these alpine plants is quite s imi la r to that in certain a r c t i c plants and seems to be adaptive for short, cold growing seasons (Knight and Thi lenius, 1975). In s i tu f i e l d measurements of net photosynthesis and so i l respirat ion were made by B i l l i n g s et aj_. (1961) using an infrared gas analyzer in Wyoming's Medicine Bow Mountains. Maximum net photosynthesis rates ranged from 4.15 to 13.4 mg COg dm"2 hr~*. Photosynthesis, by Geum ro s s i i (R.Br.) Ser., over the course of a cloudy day corresponded to changes in l i gh t and temperature. S imi lar measurements of Polygonum bistortoides (Pursh) in c lear weather showed a midday depression probably due to r i s i ng leaf temperatures and resp i rat ion. Net photo-synthesis of whole sod blocks were measured along with resp i rat ion, and dry weight gain was estimated at 2.79 g m~2 day There are apparently no comprehensive nutrient cycl ing studies avai lable for alpine tundra plant communities. The preceeding review of energetics, though, suggests general patterns regarding the nature of alpine nutrient cyc l ing . For example, i t seems that the rate of decomposition of surface and below-ground 17 detr itus is the c r i t i c a l factor influencing the rates of both energy and nut-r ient cyc l ing. Nutrient cycl ing in a r c t i c tundra i s slow because only abou t 30% of the year ' s l i t t e r f a l l decomposes in the same year (rates of root t u r n -over are not avai lable) result ing in substantial organic matter accumulations and nutrient storages. By comparison, in subalpine grasslands 30-51% of the year ' s l i t t e r f a l l may decompose over winter alone (Bleak, 1970). Energy re-lationships may then infer a great deal about a system's nutrient cyc l ing. The avai lable data indicate strong s im i l a r i t i e s between energy data from the a rc t i c and alpine tundras. For example, the high proportion of the biomass found underground, the accumulation of organic matter in surface horizons and the low net productivity a l l suggest s imi lar responses to low energy budgets. Therefore, nutrient cycl ing studies taken from the a r c t i c may serve as approx-imations of nutrient cycles in alpine tundras. Fire may play a greater role in accelerating nutrient cyc l ing , however, in certain alpine microenvironments than in a r c t i c tundra. The perched water table over permafrost result ing in the a rc t i c tundra's marshy character tends to retard not only f i r e , but also decomposition. The d i s t r ibut ion of organic matter and N, P and K was studied on four alpine plant communities in the Northern Alps (Rehder, 1976). Marked differences were evident in productivity as well as nutrient d i s t r ibut ions among communities. Also, while in most communities so i l N mineral ization exceeded the rate of net shoot N uptake, in one community net shoot N uptake during the growing season ex-ceeded the rate of so i l N mineral ization thus implying, at least in some cases, a strong " internal N cyc le " . Kuramoto and B l i s s (1970), studying subalpine meadows in the humid Olympic Mountains found high total N levels in so i l s of a l l s ix communities studied. Total N was highest in the surface horizons and decreased with depth. In a l l but the heath-shrub community C:N ratios were between 8:1 and 3:1 (12:1 i s commonly quoted for agr icu l tura l s o i l s ) . Among communities, tota l N in the 18 uppermost s o i l layers increased from xer ic to mesic plant communities. This re-lat ionsh ip, natura l ly , follows the d i s t r ibut ion of surface organic matter c losely and suggests d i f ferent nutrient cycl ing relationships for communities along en-vironmental gradients. The variety of microenvironments at high elevations due to radiation and wind exposure necessitates caution in generalizing about the i r nutrient-energy cycles. A rc t i c and alpine tundra ecosystems show many common features: low pro- ' duct i v i t y , large proportion of the biomass below ground, extreme scarc i ty of annual plants and the tendency to accumulate detr i tus. As the energy budgets decrease within these systems, tota l production drops, as does b i o t i c storage of energy below ground. However, f i r e seems to play a greater role in the a l -pine, especia l ly on dr ier areas. It tends to retard de t r i t a l accumulation in many alpine areas as well as accelerate nutrient cyc l ing. Also, the ground i s often unfrozen under alpine snowpacks while the tundra so i l freezes in the winter. This may explain the higher decomposition reported for alpine tundra. Decomposition i s highly dependent on temperature, moisture and a v a i l -a b i l i t y of oxygen. Since decomposition is often the major "bottleneck" in the nutrient cycle, i t i s reasonable to suppose that the rate of nutrient cycl ing i s highly dependent on the energy f lux into the so i l and the so i l moisture. 3.1.3 Temperate Grasslands Grasslands are characterized by high rates of energy and nutrient flow. Relative to other ecosystems the period between photosynthetic f i xa t ion of car-bon and i t s release in respirat ion i s very short. Consequently, decomposition of the large annual l i t t e r f a l l plays an important role in the a v a i l a b i l i t y of nutr ients. Also, the fibrous root system of grasslands undergoes rapid turnover, a large portion of the root system decomposing and growing back annually. The residual organic compounds l e f t a f ter decomposition of the wel l -d i s t r ibuted root system impart the diagnostic thick Ah horizon to grassland s o i l s . Grassland productivity i s highly dependent on p rec ip i ta t ion . Thus, pro-19 duct iv i ty estimates vary dramatically with the most marked impact of drought being manifested in the above ground parts. Rodin and Basi levich (1967a) i n --2 -2 dicated root:shoot levels of 840:140 g m and 2,010:450 g m in a wet year f o r two Central Asian grasslands. The same plant communities sampled in a drought - 2 - 2 year showed root:shoot levels of 920:40 g m and 2,300:180 g m respectively. Inhibit ion of root decomposition in the dry year was suggested as the reason for the r i se of root mass leve l s . Grassland production also varies widely within years as the plants re-cover from winter dormancy and explo i t the growing season conditions. This dynamic qual i ty of grasslands makes productiv ity estimates based on one standing crop measurement highly suspect. Shoot masses in a Minnesota grassland varied from 2.4 to 94.0 g m from Apr i l to August while root masses declined over the same period from 590 to 280 g m" 2 (Ovington, et al_., 1963). Studies conducted on grasslands of the USSR indicated that along a gradient of decreasing prec ip i tat ion and increasing evapotranspiration (north to south) root:shoot rat ios increased. This was consistent with s imi lar plant biomass levels along the gradient. So as more xer ic conditions induce a smaller shoot mass they provide conditions favorable to production of larger root masses. Root:shoot rat ios increased north to south from 3:1 to 10:1 (Rodin and Bas i lev ich, 1976b). The l a t t e r figure was comparable to that found by Ovington, et a l . i b i d . Along the same avai lable moisture gradient the annual l i t t e r f a l l input decreased north to south. Conversely, with greater root masses in the dr ier communities the influence of root turnover on nutrient cycl ing became more s i gn i f i cant (Rodin and Bas i lev ich, ib id . ) A common feature of grasslands is the accumulation of surface detr i tus . This can cause immobilization of s i gn i f i cant proportions of the system's less mobile elements (N, Ca, Mg and Fe) while the more mobile elements (K and P) are 20 less l i k e l y to be t ied up in the detr itus layer (Rodin and Bas i lev ich, 1967c). Thus, f i r e is an important factor in accelerating nutrient cycl ing in grasslands. Energy flows through grassland systems have t r ad i t i ona l l y been viewed as being dominated by grazing. However, Coleman, et al_. (1976) indicated that, even in heavily grazed rangelands, the bulk of photosynthetically f ixed energy passes d i rec t l y into the detrital-saprophagic pathway. Considering the amount of below-ground biomass and i t s reported rates of annual turnover: 25 to 50% (Dahlman and Kucera, 1965; Sims and Singh, 1971) root decomposition seems to be the dominant organic input to grasslands s o i l s . Lauenroth and Whitman (1977) found root masses in western North Dakota increased from annual minima to maxima within a 20-day period in midsummer. This 25% increase in root mass was la ter followed by a period of rapid decrease and la te r gradual increase. Grassland root biomass tends to concentrate in the upper 20 cm of the s o i l . Lauenroth and Whitman, i b i d , found 70% of the root mass between depths of 0 to 15 cm while a further 10 to 13% occurred from 15 to 30 cm. Other studies (Lauenroth, et al_., 1975) on the Northern Great Plains indicated 85 to 90% of the root mass was in the upper 20 cm of the s o i l . 3.2 ROLE AND DYNAMICS OF NUTRIENTS IN PLANT COMMUNITIES 3.2.1 Nitrogen Nitrogen's role as a constituent of amino acids makes i t c r i t i c a l to plant growth and metabolism. It i s required in r e l a t i ve l y large amounts and, as enzymes regulate many facets of nutrient uptake and transport, i t s deficiency can cause other nutrient def ic iencies to occur. Consequently, N has received the greatest attention from agronomists. Since the N cycle involves several gaseous forms and one of the u t i l i z a b l e forms, NO ,^ is a readi ly leached anion, N i s subject to loss from the plant system. Also, some of the N compounds within the plant are res istant to decomposition and are often t ied up in unavailable form in the detr itus or s o i l . 21 N may be added to a plant community via dust inputs, p rec ip i ta t i on , micro-organismal f i xa t ion or by a r t i f i c a l inputs. N may also be found in cer-tain sedimentary rocks, notably shales and coal. The decomposition of organic matter to y i e l d avai lable N occurs v ia the following reactions: aminization proteins R-NH 2 + ^2 + * i e a t + o t n e r Products ammonification R-NH2 + HOH NH3 + R-OH + heat This ammonia may: 1. enter the n i t r i f i c a t i o n process 2. be d i r ec t l y absorbed by plants 3. be used by heterotrophs in further decomposition 4. be f ixed in expanding-lattice clays in unavailable form 5. undergo v o l a t i l i z a t i o n under dry, basic conditions NHj + HOH + OH" NH3 + 2H0H n i t r i f i c a t i o n 2 N H - + Nitrosomonas 2 N Q - + 2 H Q H + 4 H + 2N02 + 0 2 Nitrobacter 2 N Q -The result ing n i t rate is the form most readi ly u t i l i z e d by grasses and forbs. Since i t s production is a highly dynamic, b io log ica l process several factors can l i m i t i t s a v a i l a b i l i t y : lack of energy substrate for the heterotrophs, sub-optimal thermal conditions, lack of oxygen or excessive buildup of H + . Also, the n i t rate may, under reducing conditions, undergo d e n i t r i f i c a t i o n : oufjn i l H 2HN0„ +4H H N Q +2H N 2HN03 _ 2 H Q H 2 ZmrT 2 2 2 -2H0H 2 Ammonia v o l a t i l i z a t i o n is of part icu lar s ignif icance in western Canadian reclamation since the overburden spoi ls are usually basic and often dry and warm im-imediately after surface application of f e r t i l i z e r s . Leaching of n i t rate is the 22 other major factor in N loss as the low cation exchange capacity of these spoi ls may result in the loss of ammonium, and the lack of a massive root system could allow mineralized nitrates to drain out of the rooting zone. 3.2.2 Phosphorus P functions in the plant as a constituent of sugar phosphates, nucleo-tides and nucleic acids. Phosphate ca r r ie r s , phosphorylation and i t s roles in the ADP-ATP system are c r i t i c a l in carbohydrate metabolism, resp i rat ion and photosynthesis. In the growing plant P concentrates in the meristematic regions. It i s also abundant in seeds and f r u i t . P i s highly mobile in the plant and w i l l translocate from older leaves to meristematic tissues during periods of def ic ienc ies. P def ic ient plants have a reddish hue result ing from the i nh ib i t i on of protein synthesis and subsequent accumulation of sugars in the leaves and stem. This high-sugar environment is conducive to anthocyanin synthesis, hence the red coloration (Meyer, et a l . , 1973). Soi l P i s quite immobile and consequently, res istant to leaching. In ac id ic so i l s phosphates tend to form nearly insoluble bonds with Fe and Al ions while bonding with Ca in basic s o i l s . Phosphates may also form very stable bonds with the clay l a t t i c e , replacing the hydroxide ion. The plant usually absorbs P in the reduced form HPO4 or H^PO^. Only at a so i l pH of 10 does P0^ occur in substantial amounts. 3.2.3 Potassium Unlike most nutrients K is not known to form any c r i t i c a l compounds within the plant. I t exists mainly as low-molecular weight sa l ts or as the unattached K ion. These ions are apparently c r i t i c a l in the opening and closing of stomata. Their supposed role i s in the free energy depression of guard ce l l cytoplasm allowing guard ce l l s to achieve turgor in the presence of sunlight (Boyer, 1976). K is also thought to serve a ca ta l y t i c role in the synthesis of proteins from amino acids. Apparently, photosynthesis i s inh ib i ted and respirat ion is increased 23 in K-deficient plants. However, the exact mechanism i s unknown. K i s highly mobile in the plant. It concentrates in the actively-growing portion of the plant at the expense of older t issues. Like P, Ca and Mg, K is ult imately supplied by decomposing so i l minerals. Also, l i k e P, plant K is readi ly translocated so considerable internal cycl ing between shoot and root probably occurs. Soi l K tends to occur in three forms in apparent equi l ibr ium: unavailable, s lowly-avai lable and read i ly -ava i lab le . Unavailable K is that which is s t i l l bound in the crystal l a t t i c e of such min-erals as b i o t i t e , muscovite and potash feldspars. Slowly-available K is found in the inner-lamellar spaces of 2:1 clays. Through the wetting and drying pro-cess this K may become avai lable to the plant. Readily-avai lable K occurs either in solution or on the cation exchange complex. Because this is a chemical equil ibrium system removal of readi ly -ava i lable K tends to cause i t s replace-ment from the other two forms. Conversely, large additions of f e r t i l i z e r K tend to drive the equil ibrium to the l e f t (Tisdale and Nelson, 1975a). Since ionized K is a monovalent cation i t w i l l leach out of the so i l i f i n su f f i c i en t cation exchange capacity ex i s t s . Also, the divalent cations of Ca and Mg are more strongly.held on the cation exchange s i tes than K +. So excessive levels of divalent cations can replace potassium on exchange s i tes or prevent i t s adsorption, inducing K deficiency. 4.0 METHODS AND MATERIALS 4.1 THE STUDY AREA The study was conducted on the property of Kaiser Resources Ltd. near Sparwood, B.C., in the extreme southeast corner of the province. The company owns the mineral r ights in two major coal f i e ld s in the area. The Crows Nest Coal F ie ld measures 48 km long by up to 19 km wide. It contains roughly 12 potent ia l ly exploitable seams outcropping within a 760 m strat igraphic sequence. The Elk River Coal F ield l i e s somewhat to the north and east of the Crows Nest F ield and contains 7 mineable seams within a 450 m sequence of coal-bearing 24 measures. The seams vary in thickness from 1.5 to 15.2 m and outcrop between 1,000 and 2,100 m elevat ion. The overburden rock in these areas consists of sandstone, shales and some conglomerate. Upon weathering the pH of these materials range from 4.2 to 8.4 The coal i s coking grade bituminous with an average su l fur content of 0.3 to 0.4% (Berdusco and M i l l i gan , 1977). Two major vegetation types occur within the study area: the val ley bot-tom to mid-mountain forest-grassland complex and above roughly 1,800 m the sub-alpine forest-grassland complex. Forests at lower elevations are dominated by Douglas f i r , lodgepole pine and western larch (Larix occidental is Nutt.). Lodge-pole pine dominates in the more recently burned, dr ier s i tes with Douglas f i r and pa r t i cu la r l y larch more common on cooler aspects and seepage s i te s . Common understory shrubs include soopola l l ie (Shepherdia canadensis (L.) Nutt.) , fa lse box (Pachystima myrsinites (Pursh) Raf.), honeysuckle (Lonicera utahensis Wats.) and bunchberry (Cornus canadensis L.). Krajina (1965) mapped this area under the boreal white and black spruce biogeoclimatic zone. However, i t seems more log ical to regard i t as the wet sub-zone of the i n te r i o r Douglas f i r biogeoclimatic zone. Rowe (1972) c l a s s i f i ed this area as part of the Southern Columbia forest region. He indicated that along gradients of decreasing moisture more t yp i ca l l y coastal species give way to Douglas f ir-western larch and lodgepole pine. This represents the t rans i t ion from the red cedar (Thuja p l i cata Donn.) and western hemlock (Tsuga hererophylla (Raf.) Sarg.) forest around Fernie, B.C. to that surrounding Sparwood. Grasslands form a s i gn i f i cant portion of the zone near Sparwood. These grasslands tend to dominate on southwest facing slopes at mid to high elevations and increase in area toward the dry val ley bottom. Those below 1,350 m represent the primary winter ungulate range of the region (Courtney, 1977). Both species composition and productiv ity of these grasslands vary with elevation. H i l l s i de communities near the val ley f loor (1,000 m) are dominated 25 by Canada bluegrass (Poa compressa L.) and timothy (Phleum pratense L.). Heavily overgrazed areas have been invaded by the annual cheatgrass (Bromus tectorum L.) and the biennial hop clover (Trifol ium agrarium L. ) . Occasional patches of blue-bunch wheatgrass (Agropyron spicatum (Pursh) Scribn. and Smith), Idaho fescue (Festuca idahoensis Elmer) and slender wheatgrass (Agropyron caninum (L.) Beauv.) may s t i l l be found. This degeneration of the native range was probably due to the combination of domestic grazing, f i r e and wi ld ungulate grazing over the last 80 years. These areas also support numerous shrub species: serv ice-berry (Amelanchier a l n i f o l i a Nutt.), Douglas maple (Acer glabrum Torr . ) , snow-brush (Ceanothus velutinus Doug!.) and others. Most shrub species show signs of heavy browsing. With increasing elevation the native perennial grasses become.more dom-inant and the influence of the introduced species i s less apparent. Also, moun-tain brome (Bromus carinatus H. & A.) and Hood's sedge (Carex hoodii Boott) become important components of the grasslands. The major forbs in th is area are balsamroot (Balsamorhiza sagittata (Pursh) Nutt.) , s i l k y lupine (Lupinus  sericeus Pursh) and purple aster (Aster conspicuus L i nd l . ) . These grasslands around 1,600 m are probably the most productive on the Kaiser property. For the purpose of th is study and in the interest of s imp l i c i t y th i s zone, from 1,000 to 1,800 m, w i l l be referred to under the general term, montane. The subalpine zone extends from 1,800 to 2,130 m. This range includes those areas dominated by subalpine f i r and Engelmann spruce. Lodgepole pine i s also a s i gn i f i cant component of forests in th is zone. Understory shrubs include: grouseberry (Vaccinium scoparium Leiberg), fa l se azalea (Menziesia ferruginea Smith.) and white rhododendron (Rhododendron albif lorum Hook.). Grasslands in this zone are s imi lar to the upper montane in species composition although they are somewhat less productive. Dominant species are: bluebunch wheatgrass, slender wheatgrass, Idaho fescue, s i l k y lupine and su l fur buckwheat (Eriogonum  umbel!atum Torr.) . 26 Soi l s of the study area consist of brunisols, luv i so l s and podzols. Native grasslands generally occur on eutr ic Brunisols with thin (0-5 cm) L, F, H horizons, thick (25 cm +) Ah horizons, Ae horizons are not apparent and the B horizons are characterized by clay accumulation. Under forest vegetation dyst r ic Brunisols are common with thick L, F, H horizons, no Ah and a Bfh horizon ex-tending as much as 40 cm beneath the surface. Podzols had been reported pr ior to mining on subalpine, forested s i tes . 4.2 EXPERIMENTAL DESIGN Four areas were examined in this study: montane and subalpine reclaimed areas and adjacent native grasslands (Figure 4). These s i tes were part i t ioned into shoot, root, detr itus and so i l compartments to allow examination of the major pathways of intra-and extra-plant nutrient exchange and storage. Both shoot and detr itus samples were obtained by c l ipp ing. The shoot compartment con-tained a l l above-ground l i v i n g t issues. Only two species on the native s i te s : rose (Rosa sp.) and serviceberry had aer ia l penennating structures. However, these were small (ca. 10 cm t a l l ) and rare. When such an individual was encoun-tered i t was included in the shoot sample. The detr itus sample included a l l dead standing and fa l l en shoot materials as well as other surface organic matter (ungulate droppings, dead insects) longer than 5 mm. Root and s o i l samples were obtained to a maximum depth of 24 cm from so i l cores. Roots were separated from so i l by immersion of the entire sample in a beaker of water, s t i r r i n g and re-peatedly removing the f loat ing roots. V i r tua l l y complete root recovery was thus possible. Core depth was noted for each sample. So i l samples were cleaned of roots by sieving and hand separation. They were then analyzed for toal (Kjeldahl) N, NO^ and avai lable P, Ca and Mg. Avai lable P was estimated by Olsen's sodium Bicarbonate extract ion. Since the so i l s were neutral to basic this seemed more appropriate than the Bray technique which is more applicable to acid s o i l s . A l l plant and detritus samples were weighed, ground and analyzed for total N, P, K, Ca and Mg. A l l samples were dried for 48 hours at 50 C immediately 27 Figure 4 . Map of the study area showing the re lat i ve locations of the test p lots. 28 29 after co l l ec t i on . The so i l and plant analyses were, done in the University of B r i t i s h Columbia Soil Science Dept. Laboratory under the supervision of Dr. L. M. Lavkulich. Shoot, detr itus and root masses per unit area were mult ip l ied by re -spective nutrient concentrations to y i e l d mass of nutrient per unit area per compartment. Soi l nutrient masses per unit area were estimated by the following formula: N, -2 X = (N, ,) d D S (g m ) (ppm)' where: N = nutrient level d = s o i l density* D = average so i l core depth to a maximum of 0.24 m S = % of so i l sample passing a 2 mm mesh _3 * Soi l density was assumed to be 1,494,000 g m (2,000,000 lbs per acre s ix inches) The process of co l lect ing a complete set of samples took from 4 to 7 days. Samples were taken on each of the paired plots commencing on 10 August 1976. Further samples were col lected on 13-16 October 1976, 24-30 May 1977, 21-27 June 1977, 8-12 August 1977 and 11-17 October 1977. On 3 June 1977 one of the paired plots at each s i te was f e r t i l i z e d with 13.0 g m" 2 N, 6.9 g m" 2 P and 8.3 g m" 2 K as Cominco 13-16-10. The other of the pair was l e f t un fe r t i l i z ed . The plot to be f e r t i l i z e d was randomly chosen. 4.3 THE STUDY SITES 4.3.1 Reclaimed Areas Two reclaimed areas were included in this study. Both received i n i t i a l reclamation treatments in 1974 and both were highly productive in 1976. Lower C seam was operated as an open-cast contour mine in the mid-1960's. It was resloped in 1974. The reclaimed area covers 6.9 ha. at 1,550 m and is surrounded by a Douglas f i r - lodgepole pine forest with interspersed meadows. This s i te i s near the upper l i m i t of the montane zone, and subalpine plant com-munities can be found in nearby gu l l ies and on.some north-facing slopes. 30 Immediately after resloping in May 1974 the area was seeded with a mix of agronomic grasses and legumes (see Table 1). The s i te was i n i t i a l l y broad-cast f e r t i l i z e d with 21-0-0, 13-16-10 or 14-14-7 (%N, %P 2 0 5 , %K20) in early June of each year. Only the i n i t i a l appl ication was incorporated by harrowing (Table 2). Table 2. F e r t i l i z a t i o n history of Lower C seam, appl icat ion rate i s given in g m 2. Year N P K 1974 2.32 1.11 1.20 1975 3.85 1.47 1.75 1976 4.09 1.56 1.86 Total 10.26 4.14 4.81 Lower C seam w i l l hereafter be referred to as the montane reclaimed area. The "Assembly Pad", at 2,100 m e l . was, at the s tar t of the study, the only high-elevation reclaimed area avai lable for examination. This 4.0 ha s i t e was leveled in 1968 for the construction of a dragline excavator. So, though not an overburden dump the resultant surface material was s imi lar to that of the mine dumps consisting of rapidly decomposing calcareous shale and some sand-stone with a pH of 7.5 to 8.5. This d i f fered considerably from the surface material at the montane reclaimed area which was more acid (pH 6.0 to 5.5) and contained more coal and carbonaceous shale. Otherwise, both study s i tes were on gently west-facing slopes and shared common treatment h i s to r ie s . The Assembly Pad was resloped in 1974, was seeded to an agronomic seed mix (see Table 1), f e r t i l i z e d and harrowed in July 1974. Table 3 shows the f e r t i l i z a t i o n history of the s i t e . 31 Table 1. Aer ia l standing crop by species (kg ha annually on Kaiser Resources Ltd. reel -Iv ) in mid-August measured imed areas. s p e c i e s y e a r "A" M i c h e l B a l d y E r i c k - M c G i l - Lower "C" " 2 " Assembly l a g o o n p i l e f a c e son v r a y "C" seam seaia pad c r e s t e d 1 9 7 5 1 3 4 8 21 1 3 3 106 36 16 2 6 w h e a t g r a s s 1 9 7 6 11 2 0 8 13 1 2 0 168 133 31 1 1 2 1977 6 4 0 4 1 9 7 3 6 2 9 9 1 1 i n t e r m e d i a t e 1 9 7 5 1 3 0 137 9 5 9 3 14 w h e a t g r a s s 1 9 7 6 1 24 2 1 0 1 3 4 7 1 24 1 9 7 7 7 8 8 7 2 3 2 5 . 4 r e d t o p 1 9 7 5 1 4 2 1 4 3 9 2 13 1 9 7 6 5 0 9 2 1 8 118 3 5 2 1 9 7 7 5 0 1 2 5 2 2 1 7 meadow 1 9 7 5 f o x t a i l 1 9 7 6 5 6 1 9 7 7 4 smooth 1 9 7 5 3 0 1 9 1 1 9 3 0 3 6 3 9 3 4 61 4 brome 1 9 7 6 3 0 0 1 4 6 1 2 2 3 2 4 8 165 1 6 2 0 6 3 0 1977 147 1 4 0 7 2 3 2 3 6 104 1 8 2 7 0 8 5 o r c h a r d g r a s s 1 9 7 5 5 2 2 9 128 164 2 0 1 9 7 6 2 3 7 2 3 7 4 6 5 9 5 8 8 1 9 7 7 2 4 7 9 399 5 4 0 4 9 2 r e d 1 9 7 5 1 0 5 5 5 1 9 9 0 7 1 9 3 8 1 f e s c u e 1 9 7 6 57 8 5 5 1 4 1 9 3 44 71 284 198 1 9 7 7 1 6 7 4 3 8 8 7 3 14 1 3 6 5 2 3 5 8 p e r e n n i a l 1 9 7 5 2 124 4 6 9 4 0 3 2 3 1 501 8 9 r y e g r a s s 1 9 7 6 6 4 ' 24 87 4 7 0 1 1 8 1 9 7 7 2 1 2 24 6 41 4 4 t i m o t h y 1 9 7 5 4 3 41 3 0 49 3 0 1 1 5 1 9 7 6 1 1 0 1 5 2 0 2 14 . 1 8 4 3 3 4 1 9 7 7 3 3 2 1 4 2 3 5 4 7 Canada 1 9 7 5 1 9 1 4 6 4 2 8 2 C 6 b l u e g r a s s 1 9 7 6 2 2 6 4 8 9 71 1 9 7 7 6 2 3 2 3 1 1 7 3 3 8 k e n t u c k y 1 9 7 5 b l u e g r a s s 1 9 7 S 1 1 0 2 3 8 1 2 3 1 9 7 7 4 2 1 3 1 a l f a l f a 1 9 7 5 4 8 6 0 3 1 0 9 0 1 1 8 9 7 3 8 343 6 -1 9 7 6 4 8 1 2 5 8 5 1 1 1 2 0 2 1001 1 4 5 6 1433 67 1 9 7 7 144 62 1 9 4 4 7 0 4 4 2 8 9 0 1289 8 6 s w e e t c l o v e r 1 9 7 5 1 0 1 9 4 1 4 5 1 6 7 2 1 9 7 6 72 3 4 1 3 1 1 149 1 9 7 7 5 4 5 6 3 2 4 163 3 red 1 9 7 5 1 5 0 4 2 0 9 113 c l o v e r 1 9 7 6 5 8 9 134 458 1 9 7 7 2 6 5 7 4 w h i t a / a l s i k e 1 9 7 5 7 6 2 2 6 1 0 0 120 c l o v e r 1 9 7 6 4 1 5 6 5 1 7 1 0 1 9 7 7 4 5 7 2 5 3 3 2 5 t o t a l 1 9 7 5 1 2 3 5 7 4 3 2 2 1 1 7 2 2 3 0 0 2 5 5 7 1498 1401 1 ">{, t o t a l 1 9 7 6 4 8 3 1 1 0 2 5 2 4 1 4 5 5 2 1 6 0 2 4 2 2 2 3 5 8 4 2 0 2 J. • 1 4 0 6 t o t a l 1 9 7 7 5 7 5 1 0 2 8 3 3 2 7 5 2 1 1 2 9 1 1 5 2 1 5 9 0 2 3 1 1 1 6 4 2 32 Table 3. F e r t i l i z a t i o n history of the Assembly Pad, appl ication rate is given in g m . Year N P K 1974 2.08 1.11 1.33 1975 4.77 2.56 3.04 1976 4.09 1.56 1.86 Total 10.94 5.23 6.23 The Assembly Pad was located amid subalpine f i r , Engelmann spruce and whitebark pine forest growing on podzolic to brum'solic s o i l s . Also present in th is area were subalpine grasslands, mainly on south to west-facing slopes. For the remainder of this report the Assembly Pad w i l l be referred to as the subalpine reclaimed area. These s i tes were chosen for th i s study because they were both highly productive and represented apparently successful reclamation. Also, aer ia l standing crop data had been col lected on these areas since 1975 (Table 1). 4.3.2 Native Grasslands Two native grasslands were included in th is study to act as indicators of nutrient dynamics and storages in native grasslands and to serve as c l imat ic controls. The l a t t e r function would prove useful in the event of extreme fluctuations in weather i . e . drought, late f rost or early winter. It would i n -dicate whether the reclaimed areas were subject to greater degrees of pertur-bation in the event of such disturbances which are common to the i n te r i o r moun-tains. Native grassland plots were chosen as near as possible to the reclaimed study areas and, l i k e the reclaimed areas, were located on west-facing slopes. The montane native grassland was located about 0.5 km from the montane reclaimed area. It has a westerly exposure and a 15° slope. The so i l i s brun-i s o l i c and the dominant species are typical of those previously described for 33 upper montane grasslands. Due to the extent of surface mining at the high elevations undisturbed subalpine grasslands were rare. Consequently, the nearest native grassland was about 3 km from the subalpine reclaimed area. The s i t e faced westward on a slope of 32° and was 90 m lower in elevation than the subalpine reclaimed area. This s i te was near the crest of a ridge and d i rec t l y overlooked the Elk Val ley. Thus, i t was subject to high winds and received minimal subsurface water flow from upslope. The dominant species on this area were bluebunch wheatgrass, Idaho fes-cue, Wheeler's bluegrass (Poa nervosa (Hook.) Vasey), s i l k y lupine, serviceberry, purple aster, wild buckwheat and rosy pussytoes (Antennaria microphylla Rydb.) 4.4 SAMPLING This type of study required destructive sampling over a year on small (30.5 m X 7.6 m) plots and imposed several constraints on sampling. Pr imar i ly , both c l ipp ing samples and par t i cu la r l y root and so i l cores had to be small to avoid damaging the plots during the study. Consequently, sampling had to be s u f f i c i en t l y intense to y i e l d , with small sample plot s izes, reasonably precise estimates. Several parameters were of interest in this study: the mean and variance of shoot, detr itus and root masses per unit area as well as the mean and variance of s o i l levels of N, P and K. Since chemical analyses were conducted on bulked shoot, detr itus and root samples no confidence intervals could be placed on thei r nutrient leve l s . At the beginning of the study there were no avai lable estimates of var-iance in any of the sample parameters. Also, the time involved in co l lect ing a compete set of samples was unknown. Too much time taken in co l lect ing a com-plete set of samples would increase the po s s i b i l i t y of delay due to adverse weather. I t would also allow changes due to growth, death and decomposition in plots according to the order in which they were sampled. Thus, a week was 35 MONTANE NATIVE shoots detritus A f e r t i l i z e d o unfertilized S O N D J F M A 1976 1977 M J j A f S 0 MONTH Figure 5. The temporal d i s t r ibut ion of organic matter in shoots and detr i tus . The l e t t e r ' f indicates the date of f e r t i l i z a t i o n . Each data point i s the mean of 15 observations and is bracketed by the standard deviation of the mean. 36 Detritus masses on both f e r t i l i z e d and un fe r t i l i zed plots dropped by nearly 50% between August and October 1976. Detritus levels rose by May 1977 to 1,050 and 800 g m for the un fe r t i l i zed and f e r t i l i z e d p lots , respectively. These increases may have been the resu l t of growth and death of shoot matter during the very early spring and by the addition of elk and deer droppings. Deer and elk herds congregated on such open areas during this period. Indeed, drop-pings were frequently encountered during the May sample. Another period of rapid decomposition followed from May to June lowering de t r i t a l masses to around _2 570 g m . Death of recently produced shoot matter probably accounted for the r i se in de t r i t a l levels to 690 g m by August while decreased shoot production and rapid decomposition resulted in detr itus losses by October. Here, for the f i r s t time, f e r t i l i z a t i o n effects become apparent in decreasing detr itus levels -2 -2 on the f e r t i l i z e d plot to 356 g m versus 570 g m on the un fe r t i l i zed plot (Figure 5). These data indicate two major periods of net detr itus loss (via decom-posit ion and/or grazing): late summer and early summer. Detritus accumulated during the winter and early spring as well as mid-summer. That f e r t i l i z a t i o n resulted in a net loss of detr itus despite increased inputs from shoot matter was probably due to accelerated decomposition. In October 1976 the root mass on the f e r t i l i z e d plot was somewhat ( s i gn i -f i cant only at the 80% confidence level) lower than that of the un fe r t i l i zed p lot . By the end of the study both levels were equal, suggesting a s l i gh t i n -crease in root mass due to f e r t i l i z a t i o n (Figure 6). 5.1.2 Montane Reclaimed Area Shoot dynamics on the reclaimed area di f fered from those of- the native area in several respects. F i r s t , the reclaimed areas maintained a large shoot mass unt i l late in 1976. This resulted in observable f rost k i l l i n g of some plant tops. Delay in the onset of f a l l dormancy due to f e r t i l i z a t i o n was also evident in October 1977 where the f e r t i l i z e d plot rebounded after the drought with 37 3500 MONTANE tn •P O O u o •p x: CP •H 0) >< M 3000 2500 ~ 2000| ' e Cn 1500 1000 500 native reclaimed o f e r t i l i z e d unfertilized A S O N 1976 D J F M A M J J A S 1977 f MONTH Figure 6. The temporal d i s t r ibut ion of organic matter in roots. The l e t te r ' f indicates the date of f e r t i l i z a t i o n . Each data point i s the mean of 30 observations and is bracketed by the standard deviation of the mean. 38 increased growth while the un fe r t i l i zed plot continued to lose shoot mass (F ig-ure 7). As this tendency to carry a greater shoot mass into October was also observed on the native f e r t i l i z e d plots i t seems that f e r t i l i z a t i o n can delay the onset of f a l l dormancy in native species as well as in agronomic species. Thus, what appeared in 1976 to be i l l - adapt i ve phenological responses to c l imat ic signals in the agronomic species were, at least part ly , due to f e r t i l i z a t i o n practices. Second, while both native plots produced less shoot mass than in 1976 they did not display the severe decline in shoot production evident in the reclaimed plots due to the mid-summer drought. This was probably due to the i n -creased so i l moisture holding capacity of the native areas as well as species tolerance to drought. Even within the reclaimed plant community differences in species drought tolerance were observed. While orchardgrass (Dactylis glomerata L.), timothy and the true clovers (Tr ifol ium spp.) were often k i l l e d to the ground; smooth brome (Bromus inermis Leys.), crested wheatgrass (Agropyron  desertorum Fisch..), intermediate wheatgrass (A. intermedium (Host.) Beauv.), Canada bluegrass, red fescue (Festuca rubra L.) and a l f a l f a (Medicago sativa L.) were apparently healthy throughout this period. However, a f ter the rains of early August orchardgrass rebounded remarkably we l l . No drought k i l l i n g was apparent on the native area. Like the montane native area the montane reclaimed area los t detr itus from August to October 1976 while detr itus increased from October to May. Again, as in the native area, deer and elk pe l lets were abundant in the May sample at least p a r t i a l l y accounting for the r i se in detr itus leve l s . With the onset of the growing season, detr itus levels f e l l on the un fe r t i l i zed plot while remaining constant on the f e r t i l i z e d p lot . F e r t i l i z a t i o n should have accelerated decom-pos i t ion. Maintenance of this high detr itus level resulted from an increase in shoot inputs su f f i c i en t to y i e l d a s l i gh t net increase in detr itus mass. Fert-i l i z a t i o n resulted in no net increase in shoot mass from May to June. Thus, i t seems the increased shoot production had been drought-ki l led and entered the 39 500 cn •P •A M •P (U T J T J C (0 cn •P O o Xi cn M-l O e CP -p •A <D 3 >i U T J 400 300 200 MONTANE RECLAIMED shoot d e t r i t u s * f e r t i l i z e d ° u n f e r t i l i z e d 100 MONTH gure 7. The temporal d i s t r ibut ion of organic matter in shoots and detr itus The l e t t e r ' f indicates the date of f e r t i l i z a t i o n . Each data poi is the mean of 15 observations and is bracketed by the standard deviation of the mean. 40 detr itus compartment. The s im i l a r i t y of shoot masses in the f e r t i l i z e d and un-f e r t i l i z e d plots in June suggests that factors other than nutrients were l i m i t i n g . Throughout the mid-summer drought detr itus accumulated in the un fe r t i l i zed plot to match that of the f e r t i l i z e d plot which was v i r t u a l l y unchanged from June. By October both plots l o s t considerable detr itus with the f e r t i l i z e d plot some-what lower than the un fe r t i l i zed plot (Figure 7). Differences in root masses between f e r t i l i z e d and un fe r t i l i zed plots were not highly s i gn i f i cant . However, the un fe r t i l i zed p lot , after June 1977, sup-ported a larger root mass for the duration of the study. The root dynamics of the montane reclaimed area resembled those of the montane native area in highly dampened form. So, while the periods of growth and a t t r i t i o n were s imi la r , the reclaimed area root systems were not nearly as productive as the native area and consequently returned much less organic matter to the so i l each f a l l (Figure 6). 5.1.3 Subalpine Native Grassland The response of the subalpine native area to f e r t i l i z a t i o n was s imi lar to that of the montane native area. However, in addition to greater shoot product-i v i t y on the montane native area i t d i f fered from the subalpine native area in that the f e r t i l i z e d plot reached maximum productiv ity in June whereas the high elevation f e r t i l i z e d plot achieved maximum shoot production in August. As on the montane native area f e r t i l i z a t i o n of the subalpine native area resulted in main-tenance of a larger l i v i n g shoot mass into October (Figure 8). Detritus levels on the f e r t i l i z e d and un fe r t i l i zed plots varied e r r a t i c a l l y in this area. The onset of the growing season brought on rapid depletion of detr itus so that by June f e r t i l i z e d and un fe r t i l i zed plots had only 440 and 315 _2 g m respectively. Over the mid-summer period detr i tus accumulated on the un-_2 f e r t i l i z e d plot r i s i ng to 520 g m while f e r t i l i z a t i o n resulted in a s l i ght de-crease in detr itus on the f e r t i l i z e d plot by August (Figure 8). As in the montane native area root masses on this area reached the yearly { nadir in the late f a l l and maximal levels in mid-June. While shoot levels were 41 shoot detritus ^ f e r t i l i z e d 0 u n f e r t i l i z e d 900 SUBALPINE NATIVE cn 3 •P u p (D TJ TJ C ID tn P o o X. cn M-l O CN I e -p tn •H 0) >i >-i TJ 750 600 4 5 0 300 150 S O 1976 M A M 1977 J J f MONTH Figure 8. The temporal d i s t r ibut ion of organic matter in shoots and detr i tus . The l e t t e r 1 f indicates the date of f e r t i l i z a t i o n . Each data point is the mean of 15 observations and is bracketed by the standard de-viat ion of the mean. 42 higher on the montane native area the subalpine native area produced a larger root mass. Thilenius (1975), working in subalpine areas of the Medicine Bow Mountains of Wyoming measured root masses from late June to late August. Within _2 this period root masses ranged from 2,729 to 7,186 g m . Other workers (B l i s s , 1963; Scott, 1963) reported root masses ranging from 750 to 3,634 g m in var-ious alpine plant communities. So, while the root masses of high-elevation plant communities are highly variable the data presented here f a l l within the range of reported values (Figure 9). 5.1.4 Subalpine Reclaimed Area Substantial overwinter shoot loss occurred on both reclaimed areas. Otherwise, shoot masses on the two reclaimed areas behaved quite d i f f e ren t l y . While the montane area los t nearly half of i t s shoot mass between June and Aug-ust due to drought, the subalpine area showed no such depression. Indeed, while summer drought negated f e r t i l i z e r effects unt i l October on the montane area, f e r t i l i z a t i o n had a dramatic ef fect on shoot production on the subalpine area nearly quadrupling shoot mass by August (Figure 10). This difference was due to a more favorable so i l moisture environment. Among the four study areas de t r i t a l dynamics on the subalpine reclaimed area were unique. Of part icu lar s ignif icance was the tendency of the unfert-i l i z e d plot to accumulate detr itus.despite lowered shoot production from the previous year. Indeed, detr itus nearly doubled on the un fe r t i l i zed plot from _2 October 1976 to October 1977 while August shoot levels were 87 g m lower in 1977. This suggests rapid shoot a t t r i t i o n during the growing season and slow decomposition. Also, detritus on a l l other un fe r t i l i zed plots underwent two major periods of net loss (early f a l l and early summer) as well as two periods of net accumulation (winter to early spring and mid-summer). The subalpine re-claimed area los t detr itus only in mid-summer while accumulating detr itus during the remainder of the year (Figure 10). This de t r i t a l accumulation represents a sink for the more slowly avai lable nutrients and w i l l resu l t in s i gn i f i cant 43 SUBALPINE native S O N D J F M A M J J A S 1976 1977 f MONTH Figure 9. The temporal d i s t r ibut ion of organic matter in roots. The l e t t e r ' f indicates the date of f e r t i l i z a t i o n . Each data point is the mean of 30 observations and i s bracketed by the standard deviation of the mean. 44 SUBALPINE RECLAIMED . shoot tn D P •H H -P <D TJ TJ C rO tn P 0 O J3 tn m O •P •i-t TJ 500 400 300 200 100 detritus f e r t i l i z e d unfertilized A S O 1976 N D J M A M 1977 J J A f MONTH Figure 10. The temporal d i s t r ibut ion of organic matter in shoots and detr i tus . The l e t t e r ' f indicates the date of f e r t i l i z a t i o n . Each data point is the mean of 15 observations and is bracketed by the standard deviation of the mean. 45 losses from the avai lable nutrient pools. At the least , unchecked accumulation w i l l cause formation of an insulat ing mat which in this cold environment w i l l lower surface temperatures, further retarding decomposition. The root system of the subalpine reclaimed area was in the early stages of development. The slow but constant increase in root mass unt i l the end of the study suggests young root material that was only beginning to undergo s i gn i f i cant f a l l a t t r i t i o n . Indeed, although both subalpine and montane reclaimed areas were i n i t i a l l y seeded in 1974 the subalpine area root system seemed to be a year "behind" that of the montane area. Also, unlike the montane reclaimed area the root mass of the subalpine area showed a s l i gh t increase due to f e r t i l i z a t i o n . Both reclaimed areas, regardless of f e r t i l i z e r treatment, reached peak root standing crop levels in August whereas the native areas root masses peaked in late June (Figure 9). Whether th is was due to d i f ferent l i f e cycle timing in the agronomic species or to so i l factors (nutrient mineral izat ion, supply) i s unclear. It i s clear that root systems of the native communities constituted a much greater storage f a c i l i t y for carbohydrates and nutrients and contributed more organic matter to the so i l in annual a t t r i t i o n than the reclaimed area root systems. This would permit greater in-plant carbohydrate and nutrient cycl ing and provide massive organic matter inputs to the s o i l , improving so i l structure and cation exchange capacity. Of course, the reclaimed areas as young communities could not match the root development of mature, native communities in only four years. 5.2 NET CHANGES IN ORGANIC MATTER Tables 4 and 5 represent balance sheets indicat ing periods of net accumu-lat ion and loss of organic matter in the shoot, detr itus and root compartments. The bottom l i ne of each section indicates net change within compartment from October 1976 to October 1977. Most of the organic matter turnover on native areas occurred in the root systems and to a much lesser extent in the detr itus and shoot compartments. This 46 Table 4. Net change in oven dry organic matter (g m~ ) between sampling dates. The le t ter s ' F ' and 'NF' indicate f e r t i l i z e d and un-f e r t i l i z e d plots respectively. shoot detr i tus root total Montane native F Aug/Oct -255.5 -302.1 -486.5 -1044.1 Oct/May -14.5 353.3 -194.6 144.2 May/June 192.9 -267.0 2380.7 2306.6 June/Aug 6.5' 164.4 -911.9 -741.0 Aug/Oct -156.8 -343.6 -877.9 -1378.3 total (Oct/Oct) 28.1 -92.2 396.3 311.5 Montane native NF Aug/Oct -333.7 -390.0 -490.0 -1213.7 Oct/May 2.4 556.3 -228.4 330.3 May/June 109.0 -456.9 2009.3 1661.4 June/Aug 12.7 99.5 -324.1 -211.9 Aug/Oct -141.9 -127.3 -1280.5 -1549.7 total (Oct/Oct) -17.8 71.6 176.3 230.1 Montane reclaimed F Aug/Oct -29.2 -178.7 -436.6 -644.5 Oct/May -76.1 167.1 392.1 483.1 May/June 94.0 4.2 121.4 219.6 June/Aug -89.7 -4.8 23.6 -70.9 Aug/Oct 46.6 -146.1 -276.3 -375.8 total (Oct/Oct) -25.2 20.4 260.8 256.0 Montaine reclaimed NF Aug/Oct -43.3 -75.5 -323.9 -442.7 Oct/May -78.3 140.6 228.4 290.7 May/June 83.6 -127.8 258.8 214.6 June/Aug -71.6 38.8 103.7 70.9 Aug/Oct -16.3 -113.2 -233.8 -363.3 total (Oct/Oct) -82.6 -61.6 357.1 212.9 47 Table 5. Net change in oven dry organic matter (g m~ ) between sampling dates. The le t te r s ' F ' and 'NF' indicate f e r t i l i z e d and un-f e r t i l i z e d plots respectively. shoot detr i tus root total Subalpine native F Aug/Oct -154.8 46.0 -763.6 -872.4 Oct/May 8.8 247.6 2672.0 2928.4 May/June 99.3 -331.6 291.5 59.2 June/Aug 44.5 -24.9 -501.1 -481.5 Aug/Oct -90.0 -202.2 -1999.1 -2291.3 total (Oct/Oct) 62.6 -311.1 463.3 214.8 Subalpine native NF Aug/Oct -86.3 -179,6 -672.9 -938.8 Oct/May -12.6 17.1 1134.6 1139.1 May/June 78.6 -169.6 1701.1 1610.1 June/Aug -27.3 204.9 -1061.2 -883.6 Aug/Oct -96.9 -250.1 -1331:6 -1698.6 total (Oct/Oct) -58.2 -197.7 422.9 167.0 Subalpine reclaimed F Aug/Oct -159.9 156.6 23.4 20.5 Oct/May -108.0 9.8 120.5 23.3 May/June 138.1 114.6 144.2 396.9 June/Aug 262.8 -7.1 222.8 478.5 Aug/Oct -64.2 -144.7 -97.3 -306.2 tota l (Oct/Oct) 228.7 -27.4 390.2 592.5 Subalpine reclaimed NF Aug/Oct -70.6 111.3 21.9 62.6 Oct/May -99.2 73.3 77.8 51.9 May/June 95.8 97.4 120.2 313.4 June/Aug -12.2 -67.6 107.1 27.3 Aug/Oct -19.9 19.1 -118.5 -119.3 total (Oct/Oct) -35.5 122.2 186.6 273.3 48 pattern was consistent regardless of f e r t i l i z e r treatment. On the reclaimed areas most of the organic matter turnover also occurred via the root system thought the surface detritus pathway was nearly as s i gn i f i cant . Except for the drought-impaired montane reclaimed area, f e r t i l i z a t i o n resulted in a large increase in shoot production. Although this increased inputs to the detr itus compartments, detritus losses were usually greater on the f e r t i l i z e d plots i n -dicating accelerated decomposition. The montane reclaimed area was again the exception where, despite s imi lar shoot standing crops in May and August, the un fe r t i l i zed plot los t considerable detr itus while the f e r t i l i z e d plot underwent l i t t l e change in detr itus l e v e l . This was due to increased shoot production on the f e r t i l i z e d plot which was rapidly drought-k i l led, maintaining s imi lar shoot standing crops while c on t r i -buting substant ia l ly to the rapidly-decomposing detr itus pool. While root masses on a l l plots increased over the year the increase was generally greatest on the f e r t i l i z e d p lots. The f e r t i l i z e d montane native plot root mass increased 125% more than on the un fe r t i l i zed plot while the subalpine reclaimed f e r t i l i z e d plot measured a 109% greater net increase in root mass over the un fe r t i l i zed plot from October 1976 to October 1977. Over the same period f e r t i l i z a t i o n resulted in only a 10% increase in net root mass accumulation in the subalpine native area. However, on the montane reclaimed un fe r t i l i zed plot the rate of root mass accumulation was 37% greater than that of the f e r t i l i z e d p lot . Again, this aberrant behavior in the montane reclaimed area was probably due to drought e f fects . The data of Table 4 show that most of the root mass gains on the f e r t i l i z e d plot were made between October 1976 and May 1977. From May to June root mass increase on the f e r t i l i z e d plot was only 4% of that recorded for the un fe r t i l i zed plot and during the June to August this dropped further to 23%. This suggests that f e r t i l i z a t i o n may have upset the system by inducing greater shoot growth than could be supported by so i l moisture supplies. This 49 represents a wastage of carbohydrate resources, apparently at the expense of the root system. No such ef fect was evident on the subalpine reclaimed area where effects of the drought were minimal. Indeed, the subalpine reclaimed f e r t i l i z e d plot showed the largest net gain in the three measured compartments of a l l the study areas. While most of this gain was in root mass a large portion was in shoot mass which by mid-October was probably a l i a b i l i t y rather than an asset since f rost k i l l i n g transferred most of i t s carbohydrates and nutrients to the detr itus pool before translocation to the root system could occur. Conversion of the data presented in the previous two tables into g m day ~* allows closer examination of peak net productivity and loss periods as well as comparison with net productiv ity data gathered in other studies. Addi-tion of net shoot and root accumulation estimates net primary productiv ity minus grazing and losses due to senescence of plant material. Perhaps the most s t r i k ing figures are those for May to June net production in the native areas, pa r t i cu la r l y the montane native area. In this period on the -2 -1 f e r t i l i z e d p lot shoot mass accumulated at 5.5 g m day while root mass accum--2 -1 ulated at 68.0 g m day . This gives an estimated net primary productiv ity - 2 - 1 of 73.5 g m day which i s very near the estimated maximum rate of net primary -2 -1 production of 77 g m day proposed by Loomis and Williams (1963). The mon-tane native un fe r t i l i zed plot during the same period showed net shoot and root - 2 - 1 -2 -1 mass accumulations of 3.1 and 57.4 g m day for a total of 60.5 g m day These data not only indicate an extremely high rate of net production for this short period but also indicate the photosynthetic demands imposed by the large annual turnover within these perennial root systems. Indeed, turnover of net annual root production averaged 77% in the montane and 85% in the subalpine native areas. Comparable figures for the reclaimed areas were 51% in the montane re-claimed f e r t i l i z e d plot and 40% in the montane reclaimed un fe r t i l i zed plot. The subalpine reclaimed area turnover rates were 20 and 39% respectively for the 50 f e r t i l i z e d and un fe r t i l i zed plots. Thus, for montane native, montane reclaimed, subalpine native and subal-pine reclaimed areas an average of about 1,910; 205; 2,450; and 108 g m of roots respectively were returned to the s o i l in 1977. These figures represent minimum inputs as the sampling procedure only recorded net changes in root mass and would conceal, for example, root senescence, exudation and sloughing during periods of rapid root growth. S t i l l , the data indicate the extent to which even the small root masses of the reclaimed areas influence so i l development through organic matter inputs. In re lat ion to the cost of a r t i f i c i a l l y d i s t r ibut ing and incorporating 1.0 to 2.5 t ha~* of high-quality organic matter this root turn-over i s highly s i gn i f i cant . 5.3 NUTRIENT CONCENTRATIONS 5.3.1 Nitrogen Shoot N concentration tended to decline s l i g h t l y in the f a l l of 1976, then r i se to a yearly maximum in May or June, decline throughout the summer and r i se s l i g h t l y by October 1977. (See Appendix VIII for a l l nutrient concentrations). F e r t i l i z a t i o n tended to move the period of peak N concentration from late May to late June and to maintain higher shoot N concentrations throughout the summer. Shoot N concentration on a l l un fe r t i l i zed p lots , native and reclaimed, varied with a s imi lar pattern and within a s imi lar range. Generally, on the un fe r t i l i zed plots yearly minima were between 0.6 and 1.0% while yearly maxima were between 2.0 and 3.0%. The subalpine reclaimed un fe r t i l i zed plot tended to have s l i g h t l y lower shoot N concentrations than the subalpine native plot throughout the study. The montane reclaimed un fe r t i l i zed had the lowest minimum and highest maximum value of any un fe r t i l i zed p lot . The subalpine reclaimed f e r t i l i z e d plot under-went the most pronounced r i se in shoot N concentration, more than doubling that of the un fe r t i l i zed p lot . On the montane areas detritus N concentration varied between 1.0 and 2.0% throughout the study. Peak detr itus N concentration in the native area occurred 51 in October 1977. However, on the reclaimed area the detr itus N concentration peaked in late June on the un fe r t i l i zed plot and in August on the f e r t i l i z e d plot. This suggests that s i gn i f i cant amounts of shoot N were added to the f e r t -i l i z e d plot detr itus pool during the mid-summer drought or that th is N was not rapidly mineralized. On the montane areas detr itus N concentrations varied between 1.0 and 2.0%. Detritus N concentrations on the subalpine areas tended to be lower than on the montane areas. Values ranged between 0.4% and 1.6%. The native area generally had higher detr itus N concentrations than the reclaimed area. In contrast to shoot and detr itus N concentrations root N concentrations tended, with a few exceptions, to remain nearly constant throughout the study. F e r t i l i z a t i o n increased root N concentrations in the subalpine native area while ult imately y ie ld ing a s l i gh t increase in the montane native area. F e r t i l i z a t i o n increased the root N concentration during the summer on the subalpine reclaimed area but by October 1977 root N concentrations were s imi lar on both f e r t i l i z e d and un fe r t i l i zed plots. The most s t r i k ing aspect of the root N concentrations through time was their lack of seasonal response. Thus, l i t t l e net translocation of N to the overwintering portions of the root systems occurred. This was true for both native and reclaimed areas. It was expected that s i gn i f i cant net translocation would occur from both senescing shoot and root matter. So i t becomes apparent that these plant communities possess an open-ended ext ra -b iot ic N cycle (Switzer and Nelson, 1972) or, N cycles from the plant through the decomposition system and, to some extent, back to the plant again in the spring. This suggests that, rather than maintaining a large, mobile store of N in the roots over winter for use in the spring-early summer growth period, the plants take most of the i r yearly N requirements from the mineralized N in the so i l each spring. The native areas maintained higher root N concentrations than the reclaimed areas. Also, the montane reclaimed area maintained a higher N concentration 52 than the subalpine reclaimed area. Although not apparent from the root N con-centration data, the mass of the native area systems over winter was much greater than on the reclaimed areas. Thus, the native areas possessed a larger root system with which to explo i t mineralized N in the c r i t i c a l spring-early summer period. In addit ion, the N concentration of senesced root material was high so that i t probably decomposed rapidly in spring and, thus, represented a s i g n i f i -cant avai lable M reserve. 5.3.2 Phosphorus Unlike shoot N, shoot P concentrations increased on the montane areas between August and October. The exception was the native f e r t i l i z e d plot which, in the f a l l after f e r t i l i z a t i o n , f a i l ed to concentrate shoot P. The subalpine native area also concentrated shoot P in the f a l l while on the subalpine reclaimed area shoot P concentration tended to drop toward October. Shoot P concentration tended to reach a yearly maximum of between 1.30 and 0.40% in October which con-tinued unt i l May. With the onset of rapid shoot growth shoot P concentration decreased to a minimum in August. F e r t i l i z a t i o n tended to increase shoot P con-centration s l i g h t l y . Detritus P concentrations tended to remain stable between 0.10 and 0.30%. On the montane areas detr itus P concentration tended to be higher than on the subalpine areas. The concentration of detritus P tended to be highest in October when the remainder of the year ' s shoot production was added, and at a minimum between May and June when decomposition was greatest. After dropping in August and October 1976, the detr itus P concentration on the subalpine reclaimed area remained v i r t u a l l y constant for the remainder of the study. Root P concentrations, l i k e those of shoot P tended to increase on every plot except the subalpine reclaimed during the f a l l of 1976, decrease to a yearly minimum between May and June of 1977, then slowly r i se again toward October. Fe r t i l i z a t i on had no apparent ef fect on root P concentration except to depress i t s l i g h t l y during the summer. 53 That root P concentration showed less net increase in the f a l l of 1977 than in the f a l l of 1976 may have been a re f lect ion of the dry summer of 1977. In contrast, the summer of 1976 was r e l a t i v e l y wet for the region. Thus, in a wet year more shoot matter survives unt i l f a l l and i t s P is avai lable for trans-location to the roots and perennating shoots. Indeed, the P cycle was much more conservative than that of N. In these communities i t would be c l a s s i f i ed as " b i o t i c " in contrast to the " extra b i o t i c " N cycle. Nonetheless, large amounts of P cycle through the detritus-decomposer system as evinced by the increases in de t r i t a l P concentrations in f a l l . Nonetheless, the fact that both perennating shoots and roots concentrated P toward f a l l suggests that i t was more mobile within the plant than N and that i t was se lect i ve ly conserved by the plants. The subalpine reclaimed area was unique in i t s apparent lack of P conservation in the f a l l of 1976 when both shoot and root P concentrations declined. Both plots had been f e r t i l i z e d that year and growth conditions were favorable with abnormally high r a i n f a l l throughout the summer. The combination of these factors resulted in maintenance of a large shoot standing crop into October when f rost k i l l e d most of the green shoots before translocation could occur. In f a c t , during the October sample f rost k i l l i n g of green shoots was evident on this area. In 1977, however, the lack of rain in mid-summer, while result ing in l i t t l e drought damage, may have induced ea r l i e r senescence than in the previous year. 5.3.3 Potassi urn Shoot K concentrations varied widely over the study period. Nonetheless, a pattern emerged over the year though i t s implications were not ent i re ly c lear. On the native areas shoot K concentrations dropped during the f a l l of 1976 and rose substant ia l ly by spring. Then a sharp r i se occurred in the montane native f e r t i l i z e d area while on the subalpine native area the un fe r t i l i zed plot showed the sharpest r i se in shoot K concentration. Shoot K concentrations then f e l l so that concentrations were equal on a l l native plots by August. By October the data again diverged so that the montane native f e r t i l i z e d plot los t while the un fe r t i l i zed 54 plot gained in concentration. The opposite occurred on the subalpine native area so that the plot which concentrated the most in shoot K between May and June continued to decline in shoot K concentration unt i l October. Why the de-c l ine occurred on the f e r t i l i z e d plot at low elevation and on the un fe r t i l i zed plot at high elevation is unclear. On the reclaimed areas shoot K concentrations tended to increase in the f a l l of 1976 and remain constant through the winter. By June concentration on both montane reclaimed plots were equal. Then, both f e l l by August and rose again by October to the previous October leve l s . From August unt i l October 1977 the f e r t i l i z e d plot maintained a higher shoot K concentration. On the subalpine reclaimed area f e r t i l i z a t i o n resulted in a rapid increase in shoot K concentration but af ter June, on both f e r t i l i z e d and un fe r t i l i zed p lots , shoot K concentration declined steadi ly unt i l October. Detritus K concentration tended to r i se between August and October, drop to a minimum by spring then r i se slowly by October again. The f a l l r i se in de-t r i t u s K concentration was most pronounced on the reclaimed areas and was pro-bably due to delayed senescence. On the subalpine reclaimed area, where f e r t -i l i z a t i o n caused the maintenance of a large standing crop, enrichment of detr itus with K was evident in October of 1977. No such ef fect was obvious on the montane reclaimed area where f e r t i l i z a t i o n had l i t t l e e f fect on shoot standing crop. The rapid losses in de t r i t a l K concentrations a f ter enrichment periods indicated a rapid leaching of K from detr i tus. Root K concentrations on a l l areas were very low re la t i ve to those of shoot and even detr i tus . Also, except for June increases on both reclaimed areas, root K concentrations were v i r t u a l l y constant throughout the study period at about 0.15%. F e r t i l i z a t i o n had no obvious e f fect on concentrations. The data indicate that K concentrated in the shoots, that i t tended to translocate to perennating parts only on the reclaimed areas and that i t s residence time in detr itus was very short. Thus, K cycled " e x t r a - b i o t i c a l l y " and 55 rapid ly. Also, the inconsistent effects of a r t i f i c a l K additions suggest the presence of a s o i l system in the subalpine native area where added K i s somehow made unavailable. Such a system could involve expanding-lattice clays where ad-d i t ion of excessive K + of NH^ might convert montmorillonite to i l l i t e and, thus, change the i n t e r s t i t i a l K from the slowly avai lable to unavailable form. Since no data are avai lable on the clay mineralogy of these s o i l s , however, this re-mains as speculation. 5.4 TEMPORAL DISTRIBUTION OF NITROGEN 5.4.1 Montane Native Grassland The organic matter levels presented previously were mult ip l ied by the appropriate nutrient concentration y ie ld ing nutrient masses per unit area in the shoot, root and detr itus compartments. Soi l nutrient levels were converted to mass per unit area and are also presented in the following section. F e r t i l i z a t i o n increased the mid-summer shoot N level by nearly 200% over the un fe r t i l i zed plot. F e r t i l i z a t i o n also caused more N to be carr ied by shoots into October. These changes would, of course, benefit the local ungulate herds but may adversely affect the plant community by delaying f a l l dormancy, seed set and translocation of N to the roots (Figure 11). The periods of net loss of de t r i t a l N coincided with the end of the growing season (mid-August to mid-October) and the peak of the growing season ( late May to late June) (Figure 11)., The timely release of N from the large detr itus pool in June may well be c r i t i c a l in supplying the rapidly-growing plants. F e r t i l i z a t i o n had l i t t l e e f fect on the de t r i t a l N level except by depressing i t at the very end of the study. This probably resulted from enhanced decomposition. F e r t i l i z a t i o n had l i t t l e e f fect on root N levels (Figure 12). The s l i gh t depression in the f e r t i l i z e d plot in August 1977 may have been due to the i n -creased demands of the larger shoot system. The root systems in these native communities consituted a very large N pool. Since plant N i s largely bound in highly mobile proteins this pool i s probably to some extent avai lable to the rap-i d l y developing shoot system in the spring. However, the large (pearly 50%) 56 17>! 15 I O ! 3 n 0 <u t3 C o o montane native A S O N D J F M A M J J A S 0 1976 1977 subalpine native •H 15 I s 2 10 0 15 10 montane reclaimed shoot detritus A f e r t i l i z e d o unfertilized A S O N D J F M A M J J A S 0 1976 1977 subalpine reclaimed 10 0 A S O N D J F M A M J J A S O A S O N D J F M A M J J A S O 1976 1977 W N T H 1976 . 1977 Figure 11. The temporal d i s t r ibut ion of N in shoots and det r i tus , the l e t t e r ' f indicates the'date of f e r t i l i z a t i o n . 57 n a t i v e reclaimed A f e r t i l i z e d o u n f e r t i l i z e d A S O N D J F M A M J J A S O A S O N D J F M A M J J A S O 1976 1977 1976 1977 f MONTH Figure 12. The temporal d i s t r ibut ion of root N, the l e t t e r ' f indicates the date of f e r t i l i z a t i o n . 58 turnover of the root N indicates that the N cycle in these grasslands i s to a large extent ex t ra -b io t i c . The root systems of th is grassland returned about -2 -1 21 g m (210 kg ha ) of N to the so i l between June and October. The f luctuations in s o i l N between sampling dates were as high as 600 g _2 m . These differences were much higher than could be accounted for by plant uptake (Figure 13). Since even most of these differences were not s i gn i f i cant at the 90% confidence level (See Appendix I) sampling error apparently masked any treatment e f fects . Sampling intens i ty was l imited by f inanc ia l considerations. Unfortunately, th i s intens i ty did not y i e l d adequately precise estimates to de-r ive meaningful input-output equations. However, the data do indicate that total so i l N was very high on the montane native grassland and that inputs to the so i l N pool from the plants or f e r t i l i z e r s were minor in comparison. The s ignif icance of the plant and f e r t i l i z e r inputs would T ie in the i r greater a v a i l a b i l i t y . Soi l n i t rate went through two periods of accumulation (winter-early spring and mid-summer) and two periods of depletion (early summer and early f a l l ) . Soi l n i t rate accumulation and depletion coincided with periods of de t r i t a l gain and loss, so f a l l i n g n i t rate levels occurred during periods of rapid de t r i t a l decom-pos i t ion. The loss of s o i l n i t ra te in early summer resulted from the coincidence of rapid decomposition and even more rapid plant N-uptake. However, the early f a l l drop in so i l n i t rate was accompanied by a s i gn i f i cant loss in both plant and detr itus N (Figure 14). The r i se in s o i l n i t rate during winter and early spring re f lect s the loss of root mass and i t s decomposition at a time when plant uptake was minimal. The accumulation of so i l n i t rate in mid-summer also occurred when decomposition was high yet plant uptake was low. The loss of s o i l n i t ra te in early f a l l , when decomposition was high and uptake was low was probably due to leaching as r a i n f a l l was high during this period and, unlike the rainy early summer period, plant uptake could not capture the released n i t ra te . F e r t i l i z a t i o n had no clear ef fect on so i l n i t rate l eve l s . The f e r t i l i z e d p lot had higher so i l 59 A 0 •reclaimed .native f e r t i l i z e d u n f e r t i l i z e d 1200 •H 900 o CD c •H CN I 3 600 2 fO P O P 300 I I td-/ I I montane / /? / I / I A S O N D J F M A M J f J A S O 1976 1977 90d 60 • 300 subalpine \ \ ^ A ? A S O N D J F M A M J f J A S 0 MONTH 1976 1977 Figure 13. The temporal d i s t r ibut ion of total so i l N, the l e t t e r 1 f indicates the date of f e r t i l i z a t i o n . 2.0 1.5 (2.9) Montane -reclaimed Subalpine native X f e r t i l i z e d o unfertilized 1.0 0.5 A S O N D J F M A M J_ J A S 0 2.0 1.5 1.0 0.5 0 A S O N D J F M A M J J A S O 1976 1977 1976 1977 Figure 14. The distribution of soil nitrate, the letter »f indicates the date of fertil i z a t i o n 61 n i t rate pr ior to f e r t i l i z a t i o n and the higher level was maintained after t rea t -ment. This suggests that the added N was rapidly u t i l i z e d by plants or micro-organisms. 5.4.2 Montane Reclaimed Area Without f e r t i l i z a t i o n shoot N levels were higher on the montane reclaimed area than on the montane native area from May through October. However, the native area, unlike the reclaimed area, showed a strong response to f e r t i l i z a t i o n (F ig-ure 11). This was due to the mitigation of drought effects on the native area. Mit igating factors could include greater moisture absorbtion and retention in the native so i l s as well as adaptive mechanisms of the native species, for ex-ample: greater rooting depth, u t i l i z a t i o n of the photosynthetic pathway and involution of stomate-bearing leaf surfaces with attendant reduction of trans-p i ra t ion . The higher shoot N levels on the un fe r t i l i zed reclaimed plot versus the native un fe r t i l i zed plot were probably due to the larger legume component of the reclaimed area. The persistence of higher nutrient levels on even the unfert-i l i z e d reclaimed area probably explains the ungulate preference for the reclaimed areas. ' The montane reclaimed f e r t i l i z e d plot showed peak de t r i t a l N levels in August 1977 while on the un fe r t i l i zed plot de t r i t a l N reached i t s maximum in June. However, shoot N levels from May to August were s imi la r on both plots (Figure 11). The August peak in de t r i t a l N on the f e r t i l i z e d plot may have re -sulted from continued growth into the drought period which could not be supported by avai lable so i l moisture. On the un fe r t i l i zed plot net shoot production was reduced during the drought. With less shoot N input, the detr itus N pool f e l l between June and August while detr itus N increased on the f e r t i l i z e d p lot . Detritus N levels on both plots were s imi lar by the end of the study and were substant ia l ly below de t r i t a l N levels on the native area. / 62 While shoot N levels on native and reclaimed areas were s imi lar through-out the study, root N levels were around 6 to 10 times higher on the native areas. So, reclaimed area root systems constituted a much smaller storage fac-i l i t y for N in early spring when rapid growth requires readi ly accessible N. Also, the un fe r t i l i zed plot had a larger root N mass throughout the growing season in the reclaimed area (Figure 12). This may have been due to the N de-mands of the a r t i f i c a l l y - s t imu la ted shoot mass of the f e r t i l i z e d p lot . Much of the added shoot N went d i rec t l y into the detr itus pool between June and Aug-ust. The increased shoot production apparently occurred at the expense of the root N pool. As in the native areas, estimates of total so i l N on the reclaimed area were imprecise due to the small sample s ize. Although estimated levels on the un fe r t i l i z ed p lot were generally twice those of the f e r t i l i z e d p lot the differences were s i gn i f i cant (at 90% confidence) only in June and August 1977. The data i n -d icate, however, that tota l s o i l N levels were lower on the reclaimed areas than on the native areas (Figure 13). However, total soi1 N levels on the montane reclaimed area were nearer those of the native areas than the subalpine reclaimed area. The two reclaimed areas had d i f ferent types of overburden l e f t at the surface. While the subalpine area was covered with calcareous shale the montane area was surfaced with carbonaceous shale and oxidized coal . This darker mat-e r i a l i s high in organic matter and may contain large amounts of total N. How-ever, this N is considered to mineralize at a very low rate (Fairbourn, 1974). Since total a r t i f i c i a l N inputs during the history of th is s i te were only about -2 -2 10 g m and N-fixation by legumes could account for only about 40 g m (Tisdale and Nelson, 1975b) in i t s 4 year reclamation period most of this N was apparently bound in the surface material. So i l n i t rate on the montane reclaimed un fe r t i l i zed plot decreased slowly from August 1976 to May 1977, f e l l sharply in early summer and continued to de-c l ine toward f a l l a f ter a s l i gh t r i se in August. The f e r t i l i z e d p lo t , l i k e the 63 native area, lo s t s o i l n i t rate in the f a l l of 1976 and accumulated n i t ra te by spring. With the onset of the growing season so i l n i t rate decreased then rose rapidly unt i l October (Figure 14). The nearly continual loss of s o i l n i t rate from the un fe r t i l i zed plot sug-gests that a new equil ibrium was becoming established that would be able to sup-ply less n i t rate than was previously avai lable. The low rate of s o i l N mineral-izat ion may be only temporary and may be reversed i f the population of decomposer microorganisms increases in the future. 5.4.3 Subalpine Native Area Subalpine native shoot N pools were lower than on the montane area. Even the un fe r t i l i zed reclaimed plot had higher June shoot N levels than the subalpine native un fe r t i l i zed plot. However, the subalpine native f e r t i l i z e d plot main-tained higher shoot N levels into October than either montane area. The subal-pine native un fe r t i l i zed plot had peak shoot N levels in June which quickly dropped to very low levels by October (Figure 11). Detritus N levels on the subalpine native plots were generally lower than those of the montane native plots. Like detr itus organic matter l eve l s , detr itus N varied inconsistently during the study. The difference between f e r t i l i z e d and un fe r t i l i zed plots in May was par t i cu la r l y anomalous (Figure 11). Root N masses on the subalpine native area were s imi la r to those of the montane native area. Maximal and minimal leve l s , however, were consistently lower on the subalpine native area (Figure 12). Thus, a higher root N: shoot N rat io was generally evident on the subalpine plots. In the spring, shoot N i n -creased more rapidly on the montane native area while root N increase was more rapid on the subalpine native area. F e r t i l i z a t i o n resulted in a higher August root N level but by October no f e r t i l i z e r ef fect on root N was apparent. Throughout the study, so i l total N fluctuated between 360 and 750 g m (Figure 13). Again, although standard deviations of the means were usually less than 15% of the mean, the low sample size resulted in very wide confidence interva l s . 64 Hence, no differences within treatments and only one between treatments were s i g -n i f i can t at the 90% confidence l e ve l . The f e r t i l i z e d plot tended to average s l i g h t l y higher than the un fe r t i l i z ed p lot . Without f e r t i l i z a t i o n the subalpine native so i l n i t rate dynamics were s imi la r to those of the montane native area (Figure 14). F e r t i l i z a t i o n , however, reduced the early summer loss of s o i l n i t rate and caused i t to increase sharply by October. The early increase of s o i l n i t rate was also measured on the montane reclaimed f e r t i l i z e d plot. So i l on the montane reclaimed and subalpine native areas seemed dr ie r than the other two areas during root and so i l sampling. The lower so i l moisture may have lessened the amount of so i l n i t rate l o s t by leaching 5.4.4 Subalpine Reclaimed Area This area showed the most dramatic effects of f e r t i l i z a t i o n , result ing in a more than 450% increase in shoot N (Figure 11). In contrast to the montane reclaimed area the increase in shoot N after f e r t i l i z a t i o n was probably due to a more favorable moisture regime at the high-elevation s i t e which permitted rapid growth throughout the summer. The higher N uptake was probably also influenced by the lack of s o i l organic matter and, consequently,.by the lack of s i gn i f i cant microbial u t i l i z a t i o n of avai lable N. F e r t i l i z a t i o n of the subalpine reclaimed area resulted in the highest October 1977 shoot N level of any study area. This shoot N was to a large extent transferred to the detr i tus compartment by f ros t k i l l i n g soon after the sample was taken. The extremely low de t r i t a l N masses in th is area at the beginning of the study were due to the low shoot production on the s i t e in 1975. The de t r i t a l N dynamics of th i s area were unique among the study areas. Without f e r t i l i z a t i o n , de t r i t a l N accumulated almost without interruption (Figure 11). This was due to inh ib i ted de t r i t a l decomposition which may have resulted from excessively wide C:N ra t i o s , lack of decomposers, low temperatures and a dry so i l surface. That growth of the de t r i t a l N pool exceeded that of the shoot N pool, even at the peak shoot growth period, suggests that s i gn i f i cant amounts of the system's avai lable 65 N was being quickly converted into r e l a t i ve l y unavailable detr i tus N. F e r t i l i -zation caused a higher detr itus N peak in August which, subsequently, decomposed more quickly than detr itus on the un fe r t i l i zed p lot . However, by the end of the study both plots had abo7ut the same mass of N bound in det r i tu s . Subalpine reclaimed area root N levels were extremely low. Even the mon-tane reclaimed area had substant ia l ly larger root N masses. Nonetheless, the subalpine reclaimed area root N pools grew s l i g h t l y even without f e r t i l i z a t i o n . F e r t i l i z a t i o n , however, caused a substantial increase in root N (Figure 12). Soi l total N levels were also extremely low on the subalpine reclaimed area. Both plots had between 33 and 70 g m of s o i l total N throughout the study and were the poorest surface materials encountered in terms of tota l N (Figure 13). Though to a much lesser extent than in the montane reclaimed area, total s o i l N exceeded a r t i f i c i a l and possible N-fixation inputs. Soi l n i t rate on the subalpine reclaimed area underwent a nearly constant decline during the study. F e r t i l i z a t i o n caused so i l n i t rate levels to r i se in early summer and there was a very s l i gh t increase over winter on the un fe r t i l i zed plot (Figure 14). The depletion of so i l n i t rate suggests i nh ib i t i on of N mineral-i zat ion processes. This, coupled with the extremely low tota l s o i l N l eve l s , means that the subalpine reclaimed area w i l l continue to suffer severe N de-f ic iency i f maintenance f e r t i l i z a t i o n is withheld. So i l n i t rate also declined on the un fe r t i l i zed montane reclaimed p lot . However, total so i l N was high in th is area and legumes were abundant and re-producing. Because a large pool of potent ia l l y avai lable N ex ists on the montane area in addition to a large N-fixation capacity adequate avai lable N levels might be maintained. No such po s s i b i l i t y exists for the subalpine reclaimed area. Inadequate decomposition is the major deterrent to establishment of a viable ext ra -b io t i c N-cycle. Even with low levels of N in an ecosystem plant productiv ity can be maintained given adequate decomposer populations, near optimal so i l moisture and temperature, a nutrient-conservative plant community which is 66 capable of substantial in-plant cycl ing and s ign i f i cant N-f ixat ion. Apparently few, i f any, of these conditions are met on the subalpine reclaimed area. 5.5 TEMPORAL DISTRIBUTION OF PHOSPHORUS 5.5.1 Montane Native Grassland The pattern of shoot P f luctuations generally resembled those of total shoot mass and shoot N though concentration was much lower. The doubling of shoot P levels on the f e r t i l i z e d plot in mid-summer was not ent i re l y the resu l t of luxury consumption since through that period total shoot mass was also doubled. Thus, the P concentration remained f a i r l y constant in f e r t i l i z e d and un fe r t i l i zed plots (Figure 15). Detritus P tended to remain at high levels throughout the study on the un fe r t i l i zed p lot . . The only periods of substantial decline were during the peak of the growing season (May to June) and from August to October 1977 (Figure 15). These periods of de t r i t a l P loss coincided with maximum r a i n f a l l periods which apparently accelerated decomposition as well as leaching. Since P in the plant largely occurs as highly mobile phosphates leaching could have accounted for a large proportion of P movement from the detr itus although the mobil ity of phos-phate would be severely res t r i c ted soon after contact with the s o i l . The roots contained larger P reserves than either shoots or detr i tus . Like root N, root P tended to increase during periods of peak shoot growth indicat ing that most of the system's P was drawn from the so i l (Figure 16). While over-winter root P storage may be c r i t i c a l in i t s a v a i l a b i l i t y early in the spring; i t does not constitute the bulk of the system's P throughout the growing season. F e r t i l i z a t i o n resulted in l i t t l e change in root P. Its effect was only apparent in depressing the root P reserve by October. Avai lable so i l P levels on both f e r t i l i z e d and un fe r t i l i z ed plots were _2 around 5.5 g m both at the beginning and end of the study period. Immediately -2 after f e r t i l i z a t i o n avai lable P on both plots increased by nearly 5.0 g m . Since s imi lar increases occurred on both p lots , no e f fect of f e r t i l i z a t i o n on 6 7 montane reclaimed shoot d e t r i t u s k f e r t i l i z e d o u n f e r t i l i z e d CN I S O N . D ^ F M A M J J A S O 1976 1977 f A S O N D J F M A M J J A S O 1976 1977 subalpine reclaimed A . S 0 N D J F M A M J, . J A S 0 1976 1977 A S O N D J F M A M J ^ J A S O " 1976 MONTH 1977 Figure 15. The temporal d i s t r i b u t i o n of P in chnnf- anrt ^+ ' f i nd i ca te s the date o f f e r t i 1 " z l t f on ' . a n d d e t r i t ^ > the l e t t e r 68 native reclaimed A f e r t i l i z e d o u n f e r t i l i z e d Montane A S O N D J F M A M J - J A S O 1976 1977 3 1 2Z Subalpine — • cf ^ A S O N D J F M A ' M J J A S O 1976 1977 MONTH Figure 16. The temporal d i s t r ibut ion of root P, the l e t t e r ' f indicates the date of f e r t i l i z a t i o n . 69 available so i l P was apparent (Figure 17). Also, as with the tota l s o i l N es-timates poor precision made interpretat ion of the data d i f f i c u l t . 5.5.2 Montane Reclaimed Area Shoot P on this area increased toward October in both years of the study. This tendency made i t unique among study areas and was unlike shoot N on the montane reclaimed area (Figure 15). The i nh ib i t i on of mid-summer shoot P uptake may have been caused by the drought. Both f e r t i l i z e d and un fe r t i l i z ed plots had been f e r t i l i z e d in June 1976. Since the un fe r t i l i zed plot in October 1977 was the only plot which did not show this response i t seems l i k e l y that this June peak, August trough, October peak in shoot P was a regularly occurring combination of f e r t i l i z a t i o n and drought e f fects . The reasons for the divergence of de t r i t a l P values in October 1976 were unclear (Figure 15). However, the f a l l of de t r i t a l P on the un fe r t i l i z ed plot and i t s concurrent r i se on the f e r t i l i z e d p lot between May and June were s im i la r to the behavior of de t r i t a l N after f e r t i l i z a t i o n . This was a period of rapid de t r i t a l decomposition. While the un fe r t i l i zed plot lo s t total detr itus i t re-mained constant on the f e r t i l i z e d p lot . The increase in detr itus P concentration on the f e r t i l i z e d plot was due to the accumulation of shoot P, drought-k i l l ing of the shoots and the transfer of shoot P to the detr itus compartment. The rate of detr itus P loss from May to June on the un fe r t i l i zed plot was almost 200% greater than net shoot P uptake. While some of this released P was undoubtedly t ied up in insoluble form upon reaching the so i l th is l iberated de-t r i t a l P may have contributed s i gn i f i c an t l y to plant P requirements during th i s growth phase. Root P levels on both f e r t i l i z e d and un fe r t i l i zed plots remained s imi lar throughout the study. However, l i k e root N leve l s , root P was lower after f e r t -i l i z a t i o n on the f e r t i l i z e d plot than on the un fe r t i l i zed plot (Figure 16). This was due to the stimulation of shoot N and P uptake by f e r t i l i z a t i o n and i t s rapid transfer to detritus by water stress. The rapid loss of shoot P was, in 70 re c1aime d native A f e r t i l i z e d o unfertilized s u b a l p i n e A S O N D J F M A M J J A S O 1976 1977 15 10 montane A S O N D J F M A M J . J A S O 1976 1977 MONTH Figure 17. The temporal d i s t r ibut ion of avai lable so i l P, the l e t t e r ' f indicates the date of f e r t i l i z a t i o n . 71 part, replaced by diminishing root P reserves. Again, the confidence intervals for avai lable so i l P were wide. However, levels on the reclaimed plots consistently averaged lower than those of corres-ponding sample periods on the native area (Figure 17). Avai lable so i l P on the f e r t i l i z e d plot did not reach i t s peak unt i l August even though quick-release monoammoniurn phosphate was the P source in the f e r t i l i z e r mix. The delay may have been due to the dry so i l conditions. 5.5.3 Subalpine Native Grassland Shoot P on this area followed a pattern s imi lar to that of the montane native area though P levels were consistently lower. Shoot P uptake was much more rapid on the montane native area between May and June while the subalpine area maintained higher shoot P levels into October 1977 (Figure 15). In contrast to the montane native area, no increase in root P storage oc-curred in October on the subalpine native area. Also, the un fe r t i l i zed plot maintained nearly constant root P levels except in June and August. The f e r t -i l i z e d plot fluctuated more widely and by May had accumulated far more root P than the un fe r t i l i zed plot. The f e r t i l i z e d plot also showed peak root P levels in August rather than in June but by October had a root P level s imi la r to that of the un fe r t i l i zed plot (Figure 16). Unlike the montane native area, f e r t i l i z a t i o n apparently increased a v a i l --2 able so i l P on the subalpine native area. The increase of 8 g m accounted for a l l of the added P. Avai lable s o i l P on the un fe r t i l i zed plot dropped somewhat during the May to June period and rose again in August after detr itus and root had undergone large net P losses. Despite avai lable so i l Ca levels as high as any other area avai lable so i l P remained high on the subalpine plot (Figure 17). 5.5.4 Subalpine Reclaimed Area Shoot P, l i k e shoot N on the subalpine reclaimed plot increased rapidly after f e r t i l i z a t i o n . However, while the subalpine reclaimed f e r t i l i z e d plot ex-ceeded a l l other areas in p o s t - f e r t i l i z a t i o n shoot N increase i t was exceeded in 72 shoot P uptake by the montane native f e r t i l i z e d p lot . The subalpine reclaimed area, however, maintained high shoot P levels longer than than any other p lot . Shoot P levels on the subalpine reclaimed un fe r t i l i zed plot were s imi la r to those of the subalpine native un fe r t i l i zed plot throughout the study (Figure 15). Detritus P on this area accumulated slowly but steadi ly on the un fe r t i l i z ed plot while i t rose quickly and f e l l again on the f e r t i l i z e d p lot to s l i g h t l y be-low that of the un fe r t i l i zed p lot . Relative to the other areas detr itus P on the subalpine area was very low (Figure 15). While f e r t i l i z a t i o n resulted in an i n i t i a l depression of root P (perhaps due to high shoot demands) i t eventually rose to nearly 200% of root P on the un fe r t i l i zed plot (Figure 16). This was the only area on which f e r t i l i z a t i o n had a strong posit ive influence on root P leve l s . Relative even to the montane reclaimed area the subalpine reclaimed area had very low root P l eve l s . However, without f e r t i l i z a t i o n root P did not decrease over the year. As in the other compartments avai lable so i l P on the subalpine reclaimed area was lower than on any other study area. While avai lable so i l P rose in summer on the f e r t i l i z e d plot the un fe r t i l i zed plot showedonly a very s l i gh t r i se in an otherwise downward trend (Figure 17). This suggests that whatever P is made avai lable by detr itus and root decomposition i s quickly t ied up in unavailable form. The very high levels of Ca on this area imply that mineralized phosphate would rapidly bond with Ca to form immobile calcium phosphates. 5.6 TEMPORAL DISTRIBUTION OF POTASSIUM 5.6.1 Montane Native Grassland F e r t i l i z a t i o n resulted in a substantial increase in shoot K uptake, nearly doubling shoot K levels in June. However, this ef fect was short l ived with most of the extra K l o s t by August and v i r t u a l l y none l e f t by October (Figure 18). Detr i ta l K on the f e r t i l i z e d plot started at 1.0 g m~* and remained near th is level throughout the study with only a s l i gh t dip in June and a slow decline -2 -2 from 1.0 g m to 0.6 g m between August and October 1977. The un fe r t i l i zed 73 montane native montane reclaimed A S O N D J F M A M J J A S O A S O N D J F M A M J J A S 0 1976 1977 1976 1977 tn C •H CN A S O N D J F M A M J J A S O A S O N D J F M A M J J A S O 1976' 1977 1976 1977 f MONTH Figure 18. The temporal d i s t r ibut ion of K in shoots and det r i tus , the l e t t e r ' f indicates the date of f e r t i l i z a t i o n . 74 plot de t r i t a l K followed the same response except for a r i se to 2.5 g m in October 1976 and an increase between August and October 1977 to previous October levels (Figure 18). This constancy in detr itus K levels occurred despite wide f luctuations in de t r i t a l organic matter. Apparently K is leached almost immediately from the newly-fallen detr itus leaving only very low resident leve l s , or i t was trans-located to the roots very e f f i c i e n t l y during senescence. Higher levels of root K occurred on the un fe r t i l i zed plot than on the f e r t i l i z e d p lot (Figure 19). This was surpris ing since i t occurred during a period when net root production was higher on the f e r t i l i z e d p lot . The i n h i b i -t ion of root K accumulation on the f e r t i l i z e d plot may have been due to the highly stimulated shoot mass and i t s vigorous uptake of K. Avai lable so i l K levels remained nearly constant (around 40 g m ) on the un fe r t i l i zed p lot . A s l i gh t depression in K levels occurred between October and May which was reversed as the growing season progressed. F e r t i l i z a t i o n resulted -2 -2 in an increase of 8.7 g m between May and June 1977 (8.3 g m of K were added). This level was maintained through August then dropped so that on f e r t i l i z e d and un fe r t i l i zed plots avai lable so i l K levels were s imi lar by the end of the study (Figure 20). 5.6.2 Montane Reclaimed Area The only apparent e f fect of f e r t i l i z a t i o n on the montane reclaimed area was to increase October levels of shoot K (Figure 18). This was of no great ad-vantage to the plant community since f r o s t - k i l l i n g transferred most of th is shoot K to the detr itus compartment. Detritus K on the f e r t i l i z e d and un fe r t i l i zed p lots , l i k e those of the montane native area, varied very l i t t l e over the study period. However, these levels were somewhat lower than those of the native area and generally varied _2 between 0.4 and 0.7 g m . In mid-summer the f e r t i l i z e d plot detr itus K rose s l i g h t l y above that of the un fe r t i l i zed plot but f e l l back below that of the 75 native reclaimed A f e r t i l i z e d o u n f e r t i l i z e d Figure 19. The temporal d i s t r ibut ion of root K, the l e t t e r ' f indicates the date of f e r t i l i z a t i o n . 76 rreclaimed native A f e r t i l i z e d o u n f e r t i l i z e d •H o (13 c e 3 £1 ro r-l •H > ro 70 60 50 40 30 20 10. 0 montane I \ I \ I \ I .-A 60 50 40 30 20 10 0 subalpine \ \ / \ \ V A S O N D J F M A M J f J A S O A S O N D J F M A M J J A SO 1976 1977 1976 1977 MONTH Figure 20. The temporal d i s t r ibut ion of avai lable so i l K, the l e t t e r ' f indicates the date of f e r t i l i z a t i o n . 77 un fe r t i l i zed plot by October (Figure 18). Like root levels of N and P, root K peaked in June and declined toward winter (Figure 19). Thus, while some translocation probably occurred, annual root a t t r i t i o n was su f f i c i en t to substant ia l ly lower total root nutrient pools by spring. Most of this loss occurred in the f a l l . F e r t i l i z a t i o n resulted in no increase in root K, rather a s l i gh t decrease was noted in August and October 1977. -2 Avai lable so i l K on both montane reclaimed plots averaged around 8.0 g m throughout the study. Both plots showed a s l i gh t depression in avai lable s o i l K during the maximum growth period then rose again by August. However, on the f e r t i l i z e d plot a much higher avai lable so i l K level was measured in August (Figure 20). Pr ior to 1977 roughly 6.6 g m of K had been added to these so i l s since reclamation began in 1974. Since l i t t l e more than this was found on the montane reclaimed area a r t i f i c i a l K inputs may have been c r i t i c a l in establ ishing a large portion of the present avai lable so i l K pool. However, the 8.9 g m r i se on _2 the f e r t i l i z e d plot in August, nearly coinciding with the 8.3 g m K input, was -2 nearly a l l l o s t by October 1977. Only 1.3 g m of this decline could be accounted for by plant uptake, so i t seems l i k e l y that the so i l avai lable K level on this area was l imi ted by the s o i l ' s cation exchange capacity. Thus, additions beyond the s o i l ' s capacity to adsorb exchangeable K would be leached away or perhaps f ixed within expanding-clay l a t t i c e s . 5.6.3 Subalpine Native Grassland F e r t i l i z a t i o n caused a larger shoot K pool to be carr ied into the f a l l . The subalpine native p lot absorbed much less of the added K into shoot matter than did the montane native plot (Figure 18). This may have been due to water stress. While so i l moisture was not measured, so i l cores taken in mid-summer appeared much dr ie r on the subalpine p lot . This difference may have been due to i t s posit ion at the top of a ridge with l i t t l e downslope water flow and i t s 78 high wind and radiation exposure. Detritus K levels on both subalpine native plots behaved s im i l a r l y to those on the montane areas. They tended to remain near 1.0 g m throughout the study, the only difference was a small peak on the f e r t i l i z e d plot in June 1977 (Figure 18). As in the montane native area, f e r t i l i z a t i o n of the subalpine native area depressed the accumulation of root K. Unlike the montane native area, however, th i s e f fect was shortl ived with both f e r t i l i z e d and un fe r t i l i zed plots reaching roughly the same root K levels by August (Figure 19). While avai lable so i l K was somewhat lower on the subalpine native area than on the montane native area i t was 3 to 4 times that found on the montane re -claimed area. Also, avai lable so i l K on the subalpine native area tended to fol low seasonal growth patterns, r i s i ng during peak growth periods and f a l l i n g as the plant community entered dormancy. F e r t i l i z a t i o n had no obvious ef fect on avai lable so i l K (Figure 20). 5.6.4 Subalpine Reclaimed Area Like the montane reclaimed area a large loss of shoot K occurred between October and May whereas the native areas gained s l i g h t l y in shoot K over this period (Figure 18). However, the subalpine reclaimed un fe r t i l i zed plot had roughly the same shoot K level in October 1977 as i t had in the preceding May. This indicates that the withholding of f e r t i l i z a t i o n mitigated the tendency of the reclaimed plant community to extend the growing season into late f a l l . Also, peak shoot K levels on a l l un fe r t i l i zed p lots , native or reclaimed, were v i r t u a l l y the same indicat ing that without f e r t i l i z a t i o n su f f i c i en t K was avai lable to the reclaimed plant communities to maintain apparently adequate shoot K leve l s . The question of what constitutes "adequate" nutrient levels is d i f f i c u l t to assess. It i s used here with the assumption that the native grasslands are, for our pur-poses, stable and that they would not have persisted so long without "adequate" nutrient supplies. ( 79 Detritus K on both subalpine reclaimed plots rose from 0.1 to about 1.4 g m between August and October 1976. These levels then f e l l o f f to between _2 0.3 and 0.9 g m for the remainder of the study. No strong f luctuations were evident nor were there any differences due to f e r t i l i z a t i o n (Figure 18). After the i n i t i a l r i se in de t r i t a l K i t soon assumed levels s imi lar to that of the other areas. On a l l four areas, regardless of f e r t i l i z e r treatment, detr i tus K remained v i r t u a l l y unchanged averaging around 1.0 g m throughout the study. Root K on this area increased steadi ly throughout the study period (F ig-ure 19). This was probably due to the youth of the root system and consequently the absence of substantial annual a t t r i t i o n . Unlike the montane reclaimed area f e r t i l i z a t i o n of the subalpine reclaimed area resulted in an increase in root K. However, even the un fe r t i l i zed plot showed a substantial increase in root K during the study. Avai lable so i l K, except fora peak on the f e r t i l i z e d p lot in May, remained -2 near 5.0 g m on both plots throughout the study (Figure 20). This pattern was s imi lar to that of the montane reclaimed area. However, avai lable so i l K levels on the native areas fluctuated widely. This apparent buffering of reclaimed so i l K may be due to an equil ibrium among unavailable, slowly avai lable and a v a i l -able forms of K. This could occur in the presence of large amounts of 2:1 clays which would f i x additional K between the clay l a t t i c e and remove i t from the avai lable pool. 5.7 NITROGEN DYNAMICS The data presented in the preceeding figures were converted to the d i f f e r -ences within compartments between successive sampling dates. This permits an estimate of the magnitude of nutrient gains and losses and i dent i f i e s the periods during which these changes occurred. The data in the following tables represent shoot N, detr itus N, root N and the sum of these which is ca l led total N. Total s o i l N is also l i s t ed but is not included in the " t o t a l " f igure. 80 5.7.1 Montane Areas F e r t i l i z a t i o n on the montane native area increased N f lux through the shoot compartment and increased the net accumulation of N in the root compart-ment. The greater accumulation of detr itus N in the un fe r t i l i z ed plot was due to greater inputs between October and May so th i s difference cannot be attr ibuted to f e r t i l i z a t i o n . Between August and October 1977 the f e r t i l i z e d plot lo s t 8.1 -2 -2 g m of shoot and detr itus N while the un fe r t i l i zed plot los t only 1.5 g m from these compartments during this i n te rva l . This suggests a higher rate of decomposition on the f e r t i l i z e d p lot , apparently commensurate with higher N i n -puts, result ing in l i t t l e net change in de t r i t a l N leve l s . Thus, while f e r t -i l i z a t i o n accelerated the rates of N exchange among compartments i t apparently, at least in the short term, did not result in any serious depletion of the de-t r i t u s N pool or cause an overproduction of shoot at the expense of the root system. Also f e r t i l i z a t i o n did not seriously a f fect the' timing of shoot N loss in f a l l so l i t t l e shoot N was l e f t standing by October (Table 6). The un fe r t i l i zed montane reclaimed plot accumulated more plant and de-t r i t u s N over the year than the f e r t i l i z e d p lot . Table 6 shows that most of the un fe r t i l i zed plot increase occurred in the root compartment and most of that occurred between May and June. During this peak growth interval the f e r t i l i z e d plot accumulated much less root N. Had root N on the f e r t i l i z e d plot not increased _ 2 by 4 g m between October and May (before f e r t i l i z a t i o n ) the difference in root N gains of the two plots would have been even greater. A large portion of the net N accumulation on the f e r t i l i z e d p lot occurred as a resu l t of shoot N i n -creases between August and October 1977. This la te season uptake was accompanied by an accelerated root N loss and would probably be of minimal benefit to the plant community as i t came during a period of low temperatures which had already caused some frost k i l l i n g by October. The un fe r t i l i zed plot showed net de t r i t a l losses from May through October while the f e r t i l i z e d plot accumulated de t r i t a l N from May to August and only los t 81 Table 6. Net change in N mass between sampling dates in the shoot, detr i tus , root and so i l compartments. The so i l data re-present total N. The le t ter s ' F ' and 'NF' indicate f e r t i l i z e d and un fe r t i l i zed plots respectively. NITROGEN (G M**-2) MONTANE NATIVE F SHOOT DETRITUS ROOT TOTAL SOIL AOG-OCT -3.3 0 -1 .94 -15.09 -20.33 15.01 OCT-MAY 0.72 5.77 -3.93 2.55 159.73 MAY-JON 4.48 -4.60 34.72 34.6 1 25. 18 JON-AUG -0.86 3. 38 -13.32 - 10.80 -157.36 AOG-OCT -3.89 -4.20 -7.82 -15.90 279.80 NET(OCT-•OCT) 0.45 0.35 9.65 10.46 307.35 MONTANE NATIVE NF AOG-OCT -4.28 -6.29 -7.66 -18.23 684.01 OCT-MAY 0.93 12. 14 -7.93 5.14 -438.49 MAY-JDN 1.71 -8. 30 30.25 23.66 -187.46 JUN-AOG -1.22 2.79 -1 .97 -0.39 7.59 AUG-OCT -1.09 -0.44 -18.87 -20.40 273.06 NET (OCT-•OCT) 0.3 3 6. 19 1.48 8.01 -345.30 MONTANE RECLAIMED F AUG-OCT -0.74 -2.43 -4.14 -7. 32 78.75 OCT-MAY 1.09 2.06 4.39 7.53 -40.77 MAY-JUN 2. 71 1.29 1 .74 5.75 -40.50 JUN-AOG -3.43 1.26 -0.05 -2.23 69.51 AOG-OCT 1.73 -3.45 -2.61 -4.31 -98.27 NET(OCT-•OCT) 2.10 1.16 3.47 6.7 4 -1 10.03 MONTANE RECLAIMED NF AUG-OCT -3. 17 -2. 47 -0.87 -6.50 79.88 OCT-MAY 1.67 5.41 2.73 9.79 -153.94 MAY-JUN 2. 15 -0.61 5.18 6.72 123.51 JON-AUG -2.58 -1. 14 -1.34 -5.05 24.6 3 ADG-OCT -0. 25 -1.76 -1.93 -3.95 -241.49 NET(OCT-•OCT) 0.99 1. 90 4.64 7.51 -247.29 82 de t r i t a l N from August to October. This suggests sizeable shoot N inputs to the detritus compartment throughout the summer drought period and may account for the low root N gains on the f e r t i l i z e d plot. The stimulation of shoot growth due to f e r t i l i z a t i o n may have caused a continual drain on root N reserves which, soon after entering the shoot compartment, were transferred by water stress to the de t r i t a l compartment. Indeed, dead early season growth, pa r t i cu la r l y of non-drought-hardy species such as orchard grass and the true clovers, was abundant on the f e r t i l i z e d p lot in mid-summer. 5.7.2 Subalpine Areas F e r t i l i z a t i o n on the subalpine native area increased N inputs to the shoot compartment though most of th is N was s t i l l not released to detr itus by the end of the study. F e r t i l i z a t i o n accelerated the rates of de t r i t a l loss though the net yearly loss was less than on the un fe r t i l i zed plot due to a large detr itus N input over the winter. F e r t i l i z a t i o n enhanced root N accumulation (Table 7). F e r t i l i z a t i o n resulted in a 300% increase in plant and detr itus N accumu-lat ion on the subalpine reclaimed area. Much of the gain in the f e r t i l i z e d plot was in the shoot compartment which maintained a large N pool into October. How-ever, f e r t i l i z a t i o n also resulted in a nearly doubled root N accumulation. Both plots accumulated de t r i t a l N. From October 1976 to October 1977 the f e r t i l i z e d -2 -2 p lot gained 1.7 g m of detr itus N while the un fe r t i l i zed plot gained 1.2 g m of detr itus N. The annual turnover of detr itus N on the un fe r t i l i zed plot was lower than on any other study area. Only between June and August was there a net loss of detr itus N on th i s p lo t . Detritus N buildup on th i s un fe r t i l i z ed plot was not large re la t i ve to those on some of the other study p lot s , but the low N levels in shoots and roots on this plot suggest that detr itus N accumulation and i t s low rate of release may prove a s i gn i f i cant loss of avai lable N in the future (Table 7). 5.8 PHOSPHORUS DYNAMICS 5.8.1 Montane Areas 83 Table 7. Net change in N mass between sampling dates in the shoot, detr i tus , root and so i l compartments. The so i l data represent total N. The le t ter s ! F ' and 'NF' indicate f e r t i l i z e d and un fe r t i l i zed plots respectively. N I T R O G E N (G M**-2) S U B A L P I N E N A T I V E F S H O O T D E T R I T U S ROOT T O T A L S O I L A U G - O C T - 1 . 9 0 - 3 . 0 4 - 1 4 . 1 1 - 1 9 . 0 5 - 2 1 9 . 4 6 C C T - M A T 0 . 7 7 6 . 9 9 4 5 . 1 3 5 2 . 8 8 1 9 8 . 1 7 M A Y - J U N 3 . 0 2 - 3 . 5 7 1 . 0 2 0 . 4 8 . - 4 8 . 2 3 J U N - A U G - 0 . 3 7 - 2 . 2 9 - 2 . 1 3 - 4 . 7 8 - 2 8 0 . 4 0 A U G - O C T - 0 . 8 4 - 1 . 5 0 - 3 1 . 6 5 - 3 4 . 0 0 1 8 2 . 6 7 N E T ( O C T - OCT) 2 . 5 8 - 0 . 3 7 1 2 . 3 7 1 4 . 5 8 5 2 . 2 1 S U B A L P I N E N A T I V E NF A U G - O C T - 1 . 4 5 - 4 . 9 2 - 1 3 . 0 0 - 1 9 . 3 6 - 1 2 1 . 5 8 O C T - M A Y 0 . 8 1 - 1 . 12 1 4 . 9 2 1 4 . 6 0 - 2 2 . 0 1 H A Y - J U N 1 . 0 3 0 . 4 1 2 7 . 1 0 . 2 8 . 5 5 - 4 9 . 3 6 J U N - A U G - 1 . 1 1 2 . 8 8 - 1 4 . 0 6 - 1 2 . 2 9 - 1 0 1 . 4 6 A U G - O C T - 1 . 0 5 - 3 . 3 7 - 2 0 . 7 5 - 2 5 . 1 7 1 5 7 . 19 N E T ( O C T - •OCT) - 0 . 3 2 - 1 . 2 0 7 . 2 1 5 . 6 9 - 1 5 . 6 4 S U B A L P I N E R E C L A I M E D F A U G - O C T - 2 . 3 7 - 0 . 4 1 - 0 . 0 6 - 2 . 8 6 1 8 . 2 9 O C T - M A Y - 0 . 4 8 2 . 2 2 1 . 3 4 3.0 9 - 1 0 . 4 6 M A Y - J U N 6. 14 0 . 3 5 1 . 4 1 7 . 9 0 - 8 . 0 2 J U N - A U G 2. 3 8 0 . 6 3 1 . 3 7 4 . 3 9 - 4 . 0 7 A U G - O C T - 4 . 1 4 - 1 . 5 0 - 0 . 8 0 - 6 . 4 4 -2 . 7 2 N E T ( O C T - O C T ) 3 . 9 0 1 . 7 0 3 . 3 2 8 . 9 4 - 2 5 . 2 7 S U B A L P I N E RF.CL A I M ED N F A U G - O C T - 1 . 5 6 0. 3 0 - 0 . 1 6 - 1 . 4 2 2 1 . 5 6 O C T - M A Y - 0 . 2 9 1. 0 4 0 . 6 0 1. 3 4 - 1 5 . 0 9 M A Y - J U N 1 . 3 4 0 . 7 1 0 . 4 8 2 . 5 4 - 9 . 4 2 J U N - A U G - 0 . 8 0 - 0 . 6 2 1 . 0 0 - 0 . 4 3 - 1 2 . 3 3 A U G - O C T - 0 . 3 7 0 . 0 3 - 0 . 4 7 - 0 . 8 0 9 . 0 0 N E T ( O C T - •OCT) - 0 . 1 2 1 . 1 6 1 . 6 1 2 . 6 5 - 2 7 . 8 4 84 While the montane native plots both lost plant and de t r i t a l P throughout the study, the loss was twice as high on the f e r t i l i z e d p lot . Most of this ad-d i t iona l loss occurred in the detr itus and root compartments. While net root P increases between May and June were s imi la r on the two p lots , f e r t i l i z a t i o n accelerated root P loss between August and October. F e r t i l i z a t i o n also resulted in a nearly 200% increase in shoot P uptake between May and June. However, the rate of decline was commensurate so that the f e r t i l i z e d plot simply underwent a larger P f lux though the shoot compartment (Table 8). On the montane reclaimed f e r t i l i z e d plot plant and detr itus compartments gained 0.1 g m of P from October 1976 to October 1977. During this period the un fe r t i l i zed plot los t 0.3 g m of P from the same compartments. However, i n -spection of individual compartments (Table 8) revealed that the un fe r t i l i zed plot gained more root P while i t los t more detr itus P and pa r t i cu la r l y shoot P. The loss of shoot P indicates that the un fe r t i l i zed plot shoot system entered f a l l dormancy more rapidly than did that of the f e r t i l i z e d p lo t . The periods of root P increase on the un fe r t i l i zed plot were May to June and June to August with the greatest increase occurring between June and August. The f e r t i l i z e d p lo t , however, gained root P between October and May (before f e r t i l i z a t i o n ) , l o s t a s l i gh t amount of root P between May and June then gained 40% less root P than did the un fe r t i l i zed plot between June and August. The shoot uptake and loss pattern was s imi la r to that of nitrogen in th is area. Shoot P uptake was v i r -tua l l y the same on both plots between May and June and both plots l o s t the same amount of shoot P between June and August. Then, as shoot P on the un fe r t i l i zed plot remained constant through October the f e r t i l i z e d plot gained 0.3 g m of shoot P. Also, between May and June detr i tus P increased strongly on the f e r t -i l i z e d plot while the un fe r t i l i zed plot los t equally as much detr itus P. On the f e r t i l i z e d plot coincidence of root P loss, a net gain in shoot P s imi lar to that of the un fe r t i l i zed plot and a large increase in f e r t i l i z e d plot de t r i t a l P sug-gest that f e r t i l i z a t i o n caused a stimulation of shoot growth at the expense of 85 Table 8. Net change in P mass between sampling dates in the shoot, detr i tus , root and so i l compartments. The so i l data re-present avai lable P. The le t te r s ' F ' and 'NF' indicate f e r t i l i z e d and un fe r t i l i zed plots respectively. PHOSPHORUS (G M**-2) MONTANE NATIVE F SHOOT DETRITUS ROOT TOTAL SOIL AOG-OCT -0.32 0.39 1.41 1.48 1 . 27 OCT-MAY -0. 1 1 -0. 43 -2.12 -2.66 2.91 MAY-JON 0.82 -0.22 2.34 2.9 3 5. 34 JON-AUG -0.39 0. 47 -0.09 0.0 -3.06 AUG-OCT -0.44 -0.59 -1.55 -2.58 -6.09 NET (OCT-OCT) -0. 12 -0.77 -1.42 -2.31 -0. 90 HONTANE NATIVE NF AUG-OCT -0.61 0.48 1 .60 1.49 2. 13 GCT-MAY -0.01 -0.02 -2.17 -2.21 -2.48 MAY-JUN 0.34 -0.62 2 .36 2.07 4. 20 JUN-AUG -0. 14 0.76 -0.26 0.37 -4.12 AUG-OCT -0.23 -0.23 -0.88 -1.34 -0.04 NET (OCT-OCT) -0.04 -0. 1 1 -0.95 -1.11 -2.44 MONTANE RECLAIMED F AUG-OCT 0.24 -0.09 -0.29 -0.-14 1.39 OCT-MAY -0.26 0.13 0.23 0.10 -0.71 MAY-JUN 0.22 0.47 -0.01 0.67 1. 33 JUN-AUG -0.33 -0.15 0.44 -0.04 2.47 AUG-OCT 0.32 -0.46 -0.51 -0.64 -2.71 NET (OCT-•OCT) -0.05 -0.01 0.15 0.09 • 0.38 MONTANE RE CLAIMED NF AUG-OCT 0.22 0.41 0.09 0.71 1. 29 OCT-MAY -0.3 3 0. 29 -0.07 -0.10 0.84 MAY-JUN 0.21 -0.57 0.26 -0.09 -2.09 JUN-AUG -0.30 -0.07 0.73 0.35 0.23 AUG-OCT 0.04 0.17 -0.65 -0.44 0.37 NET (OCT-OCT) -0.38 -0. 18 0.27 -0.28 -0.65 86 root P reserves and that the added growth was under environmental control (water stress) which l imited net gains so that the additional shoot P was rapidly trans-ferred to the detritus compartment. Very l i t t l e of the added P was apparent as avai lable so i l P. F e r t i l i z a t i o n of the montane native area increased s o i l P by only 1.1 g m . F e r t i l i z a t i o n of the montane reclaimed area, however, increased avai lable s o i l P by 3.8 g m . The result ing increase in avai lable so i l P peaked in August when plant uptake was minimal. As very l i t t l e of this added so i l P was taken up by plants the _2 loss of 2.7 g m of avai lable so i l P between August and October was probably due to phosphate immobilization by Ca. 5.8.2 Subalpine Areas The net accumulation of P in the subalpine native plant and detr itus com-_2 partments between October 1976 and October 1977 was 1.0 g m on the f e r t i l i z e d -2 plot while the un fe r t i l i zed plot underwent a net loss of 0.7 g m in these compartments over the year. Most of the P increase on the f e r t i l i z e d plot was in the root system pr io r to f e r t i l i z a t i o n so the ef fect of f e r t i l i z a t i o n on root P uptake i s unclear. F e r t i l i z a t i o n accelerated the rate of de t r i t a l P loss. This was in part due to the longer retention time of shoot P in the f e r t i l i z e d plot for much of i t s P was not added to the detr itus compartment unt i l a f ter the study was completed (Table 9). Most the plant and detr itus P on the f e r t i l i z e d plot accumulated pr ior to f e r t i l i z a t i o n . This p r e f e r t i l i z a t i o n increase of 4.2 g m was largely in -2 the root compartment. After the addition of 6.9 g m of f e r t i l i z e r P avai lable -2 -2 so i l P rose by 8.0 g m . However, plant P uptake was only 0.7 g m between May and June. Between June and August avai lable so i l P f e l l at over three times the rate of root P uptake. Between June and October, when plant P uptake was -2 -2 only 0.8 g m , avai lable s o i l P f e l l by 4.9 g m . Most of th i s was probably lo s t to the formation of nearly insoluble calcium phosphates. 87 Table 9. Net change in P mass between sampling dates in the shoot, detr i tus , root and so i l compartments. The so i l data re-present avai lable P. The let ter s ' F ' and 'NF' indicate f e r t i l i z e d and un fe r t i l i zed plots respectively. PHOSPHORUS (G M**-2) SD BALPINE NATIVE F SHOOT DETRITUS ROOT TCTAL SOIL AUG-OCT -0. 26 0.21 -0.92 -0.96 -1 . 19 OCT-MAY 0.05 0.06 4.13 4.23 1. 17 MAY-JUN 0. 43 0.01 0.27 0.71 8.03 JUN-AUG -0.07 -0.28 0.80 0.45 -2.78 AUG-OCT -0. 15 -0.30 -3.93 -4. 38 -1.86 NET (OCT-OCT) 0. 26 -0.51 1.27 1.01 4.56 SUBALPINE NATIVE NF AUG-OCT -0. 1 4 0. 08 OCT-MAY 0.01 -0. 62 MAY-JUN 0.26 0. 02 JUN-AUG -0.21 0. 29 AUG-OCT -0.22 -0. 35 NET(OCT-•OCT) -0. 16 -0. 66 SUBALPINE RECLAIMED F AUG-OCT -0.40 0. 06 OCT-MAY -0.06 0. 1 1 MAY-JUN 0.6 0 0. 22 JUN-AUG 0. 15 0. 02 AUG-OCT -0.03 -0. 27 NIT(OCT-•OCT) 0.66 0. 08 SUBALPINE RECLAIMED NF AUG-OCT -0.33 0. 11 OCT-MAY -0. 11 0. 02 MAY-JUN 0.26 0. 1 1 JUN-AUG -0. 17 -0. 05 AUG-OCT -0.08 -0. 01 NET(OCT- OCT) -0. 10 0. 07 0.02 -0.04 0.26 0.43 -0.1 8 0.49 2.52 2.8 0 -0. 67 -1.36 -1.28 1.39 -1 .49 -2.06 -3.04 0. 10 -0.72 -1 .83 -0.01 -0.36 -0.82 0.16 0.23 0.03 -0.03 0.79 1. 15 0.76 0.92 0.28 -0.03 -0.33 -1.51 0.86 1.61 -0.05 -0.22 -0.44 -0. 30 -0.10 -0.19, -0.65 0.23 0.60 0.41 0.08 -0.15 0.01 -0.21 -0.29 -0. 46 0.0 -0.03 -0.69 88 -2 F e r t i l i z a t i o n of the subalpine reclaimed area resulted in a 1.6 g m i n -crease in plant and detritus P over the year. Most of the increase was in the _2 roots though 0.7 g m of the increase remained in the l i v e shoot mass. The un fe r t i l i zed plot los t a very s l i gh t amount of plant and detritus P (0.03 g m ) with root P levels remaining unchanged between October 1976 and October 1977. There was a s l i gh t decrease in shoot P levels re f lect ing e a r l i e r entry into f a l l dormancy in the un fe r t i l i zed p lot . Detritus P increased by the same small amount on both plots (Table 9). Root P on the f e r t i l i z e d plot was depleted during the period of maximum shoot growth but increased between June and August. The major net increases in root P on the un fe r t i l i zed plot occurred between May and June in a pattern s imi la r to those of the un fe r t i l i zed native p lots. F e r t i l i z a t i o n t r i p l ed the net i n -crease in shoot P. However, po s t - f e r t i l i z a t i o n plant net uptake was only 1.5 -2 g m re f lect ing i n e f f i c i e n t P u t i l i z a t i o n . Even avai lable so i l P increased only _2 1.0 g m after f e r t i l i z a t i o n . Between August and October a l l compartments on both plots l o s t P. The inef f ic iency of P f e r t i l i z a t i o n was evident on a l l of the areas and may be unavoidable as methods which could increase e f f i c iency ( i . e . f e r t i l i z e r banding) would be impractical in the rocky, often steep overburden. 5.9 POTASSIUM DYNAMICS 5.9.1. Montane Areas F e r t i l i z a t i o n decreased plant and detritus K levels on the montane native area, while on the un fe r t i l i zed plot plant and detritus K increased. Root K net gains and losses were s imi lar throughout the year on both plots except between May and June where the un fe r t i l i zed plot gained 38% more root K than the f e r t -i l i z e d plot. This was also a period when shoot K increased rapidly and was 59% greater on the f e r t i l i z e d plot (Table 10). The stimulation of shoot growth and K uptake may have been responsible for the lower accumulation of K in the roots. Available so i l K levels rose after f e r t i l i z a t i o n but less than the 9.0 g m"' 89 Table 10. Net change in K mass between sampling dates in the shoot, detr i tus , root and so i l compartments. The so i l data re-present avai lable K. The l e t te r s ' F ' and 'NF' indicate f e r t i l i z e d and un fe r t i l i zed plots respectively. POTASSIUM (G M * * - 2 ) MONTANE N A T I V E F SHOOT DETRITUS ROOT TOTAL S O I L AOG-OCT - U . 3 2 0. 16 - 0 . 3 2 - 4 , 4 8 1.66 OCT-MAY 0.47 - 0 . 18 - 0 . 3 0 0.0 10.71 MAY-JON 6.4 9 - 0 . 2 3 2 .47 8 .72 15.43 J U N - A U G - 3 . 9 0 0 .18 - 0 . 6 3 - 4 . 3 5 - 0 . 6 0 AOG-OCT - 2 . 6 7 -o. a 1 - 1 . 5 2 - 4 . 6 0 - 16.80 N E T ( O C T - O C T ) 0.39 - 0 . 6 4 0.02 - 0 . 23 8.74 MONTANE N A T I V E NF AOG-OCT - a , 99 0 .89 - 0 . 5 6 - 4 . 6 5 3.62 OCT-MAY 0.58 - 1 . 0 2 - 0 . 4 0 - 0 . 8 5 - 8 . 7 7 MAY-JON 2.66 - 0 . 57 3.98 6 .07 1 .77 JUN-AOG - 1 . 03 0 .63 - 0 . 5 8 - 0 . 9 8 9. 87 AUG-OCT -1.7.7 0. 24 -1 .74 - 3 . 2 8 6.48 N E T ( O C T - O C T ) 0.44 - 0 . 7 2 1 .26 0.9 6 9 .35 MONTANE RECLAIMED F AUG-OCT 0.61 0 .03 - 0 . 8 5 - 0 . 1 9 - 1 . 9 5 OCT-MAY -1 .35 - 0 . 3 1 0.61 - 1 . 0 6 4.94 MAY-JUN 2. 37 0 .35 1.25 3 .97 - 0 . 5 1 J U N - A U G - 2 . 72 - 0 . 1 6 - 1 . 0 0 - 3 . 8 8 8.91 AUG-OCT 1.83 - 0 . 10 - 0 . 4 4 1 .29 - 1 0 . 9 1 N E T ( O C T - O C T ) 0.13 - 0 . 2 2 0 .42 0 .32 2.43 MONTANE RECLAIMED NF AUG-OCT 0.48 0 .77 - 0 . 3 5 C.89 0 .87 CCT-MAY - 1 . 1 4 - 0 . 6 8 0.18 - 1 . 6 3 1.11 MAY-JUN 2.00 - 0 . 14 1.60 3.46 - 2 . 8 5 J U N - A U G - 2 . 6 8 0 .10 - 0 . 7 4 - 3 . 3 2 3. 65 AUG-OCT 0.55 - 0 . 0 6 - 0 . 4 4 0.04 - 4 . 37 N E T ( O C T - O C T ) - 1 . 2 7 - 0 . 78 0 .60 - 1 . 4 5 - 2 . 4 6 90 _2 r i se in plant K levels which alone would more than account for the 8.3 g m a r t i f i c i a l K input. Nonetheless, leaching and perhaps K-f ixat ion in expanding l a t t i c e clays brought avai lable so i l K to nearly the same levels by October 1977 in f e r t i l i z e d and un fe r t i l i zed plots. F e r t i l i z a t i o n of the montane reclaimed area increased plant and detritus _2 K by 0.3 g m between October 1976 and October 1977 while the un fe r t i l i zed plot _2 los t 1.4 g m over this period (Table 10). However, most of this difference was in shoot K ind icat ing, as with P, the ea r l i e r entry into f a l l dormancy on the un fe r t i l i zed plot. The un fe r t i l i zed plot gained more root K over the year. While shoot K gains were s l i g h t l y higher on the f e r t i l i z e d p lot , root K increased at a lower rate than on the un fe r t i l i zed p lot . This, combined with the r i se in de t r i t a l K between May and June suggests, again, stimulation of shoot K uptake at the expense of root K and i t s rapid transfer to the de t r i t a l K pool. As sug-gested for N and P, water stress probably l imited the amount of shoot that could be supported at any given time. Thus, new shoot additions resulted in comensur-ate additions to the detr itus compartment. Avai lable so i l K on the f e r t i l i z e d plot increased rapidly between June and August. By then v i r t u a l l y a l l of the plant and detr itus K that had accumulated -2 -2 between May and June (4.0 g m ) had been lost again, releasing 3.9 g m of K to the s o i l . Additional. K was perhaps released from undissolved KC1 grains that had not entered solution by the June sample. This was a dry period and the so i l surface was pa r t i cu la r l y dry on this s i t e . Indeed, some of the pink muriate of potash granules were observed on the surface, two weeks after app l icat ion, during the June sampling. K losses from plant and detritus compartments on the unfert--2 -2 i1 ized plot between June and August were 3.3 g m and corresponded to a 3.6 g m increase in avai lable so i l K over the same period. However, a l l of this so i l K increase was lo s t between August and October suggesting either leaching or f i x a -tion of the additional K in expanding-!attice clays. 91 5.9.2 Subalpine Areas F e r t i l i z a t i o n on the subalpine native area resulted in a large net i n -crease of plant and detr itus K (Table 11). As on the other areas, however, most of this increase was in the shoot compartment re f lect ing the delay in f a l l dor-mancy caused by f e r t i l i z a t i o n . Also, as noted on the montane areas, f e r t i l i z a t i o n resulted in a smaller increase in root K levels than on the control p lot. Fert-i l i z a t i o n increased de t r i t a l K between May and June while the un fe r t i l i zed plot los t de t r i t a l K over the same period. F e r t i l i z a t i o n also inhib ited the accumu-lat ion of root K. So f e r t i l i z a t i o n again stimulated shoot growth so that the root - so i l system could not supply su f f i c i en t water or K. The result was s imi la r to that of the montane reclaimed area where the net shoot increase was s imi la r on both f e r t i l i z e d and un fe r t i l i zed plots while f e r t i l i z a t i o n increased detr i tus K and depressed the accumulation of root K. Available so i l K increased rapidly between October and May on the f e r t -i l i z e d plot and between May and June on the un fe r t i l i zed p lot . The same pattern was apparent for avai lable so i l P. This may explain the ea r l i e r i n i t i a t i o n of rapid growth on the f e r t i l i z e d plot and may have been due to a s l i gh t difference in s o i l moisture, snow d r i f t i n g or aspect. F e r t i l i z a t i o n of the subalpine reclaimed area resulted in a large net i n -crease of plant and detr itus K between October 1976 and October 1977. While nearly a l l of th is increase was in the shoot compartment, root K increased at a greater rate than on the un fe r t i l i zed plot (Table 11). This was the only study area where f e r t i l i z a t i o n did not depress the net increased in root K over the year. 6.0 DISCUSSION 6.1 EFFECTS OF FERTILIZATION In a l l study plots f e r t i l i z e r addition resulted in increased shoot pro-duction. This increase was most pronounced on the subalpine reclaimed area. On the montane reclaimed area the increased shoot production due to f e r t i l i z a t i o n was 92 Table 11. Net change in K mass between sampling dates in the shoot, detr i tus , root and so i l compartments. The so i l data re-present avai lable K. The le t ter s ' F ' and 'NF' indicate f e r t i l i z e d and un fe r t i l i zed plots respectively. POTASSIUM (G M**-2) SUBALPINE NATIVE F SHOOT DETRITUS ROOT TOTAL SOIL AUG-OCT -1.39 0. 30 -0.38 -1.48 -12.86 GCT-HAY 0.56 -0.22 2.44 2.79 11.68 MAY-JUN 1.67 0. 86 0.83 3.36 7.27 JUN-AUG -0. 19 -0.98 . -0.61 -1.77 5.22 AUG-OCT -1.10 -0.14 -2.30 -3.55 -16.25 NET(OCT-OCT) 0.94 -0.48 0.36 0.33 7.92 SUBALPINE NATIVE NF AUG-OCT -1.34 0.02 OCT-MAY 0.52 -0.14 MAY-JUN 1.97 -0.51 JUN-AUG -1.59 0.42 AUG-OCT -1.39 -0.29 NET(OCT-OCT)-0.49 -0.52 SUBALPINE RECLAIMED F AUG-OCT -1.81 1.55 CCT-HAY -2.13 -1.39 MAY-JUN 5.26 0.58 JUN-AUG 5.36 0.07 AUG-OCT -3.66 -0.15 NET(GCT-OCT) 4.83 -0.89 -0.75 -2.07 -3. 89 1.37 1 .74 7.82 2.88 4.35 11.72 -2.07 -3.24 4.31 -1.55 -3.24 -26.58 0.63 -0.39 -2.73 0.11 -0. 16 -1.52 0.09 -3.42 8.23 0.82 6.67 -4.85 -0.49 4.94 -0.72 0.19 -3.6 3 -2. 10 0.61 4.56 0.56 SUBALPINE RECLAIMED NF AUG-OCT -0.97 1.11 CCT-MAY -1.42 -0.71 MAY-JUN 2.63 0.25 JUN-AUG -1.35 -0.33 AUG-OCT -0.92 0.21 NET(OCT-OCT)-1.06 -0.58 0.05 0.20 -0. 72 0.04 -2.10 0.60 0.49 3.37 0.29 0.14 • -1.54 0.25 -0.31 -1.0 1 -1.59 0.36 -1.28 -0.45 93 not apparent unt i l October because shoot masses on both f e r t i l i z e d and unfert-i l i z e d plots were equally depressed by the mid-summer drought. Larger shoot standing crops were also maintained into October on the f e r t i l i z e d plots. This ef fect was apparent on both native and reclaimed areas indicating that the tendency of reclaimed areas to remain green very late in the year was mainly due to maintenance f e r t i l i z a t i o n and only to a lesser extent the resu l t of poor adaptation of the agronomic species. Evidence for some genetic component in f a l l dormancy l i e s in the somewhat greater shoot masses l e f t in the un fe r t i l i zed reclaimed plots in October 1977 as opposed to the native plots. Also, f e r t i l i z a t i o n delayed flowering on the subalpine reclaimed area where no mature seed could be found by mid-September 1977. F e r t i l i z a t i o n stimulated shoot production to a greater degree than root production. This resulted in a narrowing of root:shoot rat ios even on native areas though the e f fect was most pronounced on the subalpine reclaimed area. Also, while net root production was stimulated by f e r t i l i z a t i o n on the subalpine reclaimed area, f e r t i l i z a t i o n resulted in diminished gains in root mass, root N, root P and root K on the montane reclaimed area. The explanation l i e s in the effects of drought at the montane area where no s i gn i f i cant prec ip i tat ion f e l l between the second week of June and the f i r s t week of August 1977. This was also a period of clear skies and high daytime temperatures. By the f i r s t week of August several species on the montane re-claimed area had died to the ground. Those included orchard grass and the true clovers. Red fescue was also damaged by drought while the wheatgrass, smooth brome and a l f a l f a showed no adverse e f fect s . Since this study was conducted at the community level the responses of a l l plant species within a given plot were integrated. F e r t i l i z a t i o n of the montane reclaimed area resulted in increased shoot production, decreased root production and increased inputs into detr itus as compared to the un fe r t i l i zed montane reclaimed p lot . That shoot standing crop on both plots were s imi lar unt i l early f a l l suggests factors other than 94 nutrient a v a i l a b i l i t y l imited the mass of shoot that could be supported through the summer. Water stress seems the most l i k e l y explanation as many species had died back to the ground by early August. Since an e f fect of water stress i s to l i m i t d i f fus ion and mass flow of nutrients from the so i l to the roots, increased a c t i v i t y of nutrient ions due to f e r t i l i z a t i o n could p a r t i a l l y of f set th is e f fect and allow continued production while the d e f i c i t between water uptake and trans-p i rat ion would be aggravated. This would, under s u f f i c i en t l y severe conditions, result in shoot death. No drought effects were apparent on the subalpine reclaimed area. This could have been due to greater s o i l moisture storage from the greater winter snowpack as well as lower temperatures throughout the summer. The native areas, as we l l , showed l i t t l e effect.due to the mid-summer drought. In cold regions the detritus pool often acts as a "s ink" for nutr ients. This i s the resu l t of inh ib i ted decomposition and has been a major problem in high elevation and high lat i tude reclamation. For th is reason de t r i t a l dynamics, pa r t i cu la r l y on the subalpine reclaimed area, were important in assessing nutrient s t a b i l i t y in the study. F e r t i l i z a t i o n increased the rate of detr itus decomposition. However, i t also tended to increase both shoot production and de t r i t a l nutrient qua l i ty . Consequently, in most cases de t r i t a l organic matter levels f e l l while de t r i t a l N and P levels rose on f e r t i l i z e d p lots. F e r t i l i z a t i o n narrowed the nutr ient: carbohydrate rat ios of det r i tus , thus accelerating decomposition. On un fe r t i l i z ed plots de t r i t a l organic matter either increased dramatically (subalpine reclaimed) or decreased at a slower rate than on the f e r t i l i z e d plot (subalpine nat ive). The aberrant behavior of the montane reclaimed area i s attr ibuted to the stimu-la t ion of shoot and detr i tus production during the drought period at the expense of the root system. For example, between May and June 1977, the period of peak shoot and root production as well as detr itus decomposition, the f e r t i l i z e d plot gained only half as much root mass as the un fe r t i l i zed plot. During the same 95 period the un fe r t i l i zed plot los t 128 g m of detr itus while the f e r t i l i z e d plot gained 4 g m . Also, during this period net shoot standing crops were nearly ident ica l on both plots. The accelerated de t r i t a l decomposition on the native areas could have pro-found effects i f a long-term program of heavy f e r t i l i z a t i o n was employed to o f f -set losses in ungulate range due to mining. Effects would probably include accelerated nutrient cycl ing with attendant losses in surface det r i tus . Also, i t i s l i k e l y that plant community composition would change to the detriment of legumes in par t i cu la r . On the pos it ive s ide, such a program would increase both shoot and root productiv ity and the carrying capacity of the range. Also, in a r e a l i s t i c native range f e r t i l i z a t i o n program much lower rates of f e r t i l i z a t i o n would be used. Also, f e r t i l i z a t i o n would l i k e l y occur at 2-3 year interva ls at most. This would minimize the chances of adverse changes while assuring i n -creased product iv i ty. On the subalpine reclaimed area de t r i t a l accumulation over the year ex-ceeded net shoot production on the un fe r t i l i zed plot. On the adjacent f e r t i l i z e d plant, however, detr itus levels dropped s l i g h t l y over the year. Detritus behaves as a mulch and moderates the so i l thermal and moisture environment by reducing incident radiation and wind. Brink e_t al_. (1967) i n -dicated the problems in plant establishment posed by needle-ice on bare, high elevation s o i l s . Soi l coverage by l i v e or dead vegetation mitigates th i s hazard. However, in cold regions excessive de t r i t a l buildup can have adverse effects as we l l . For example, insulat ion of the so i l from the a i r can aggravate f rost i n -jury to plants (Geiger, 1965). This results from inh ib i ted upward thermal con-duct iv i ty . On c lear , cool and calm nights, when convection i s low and radiation losses to the sky are rapid, the res t r i c ted conduction of heat from the so i l (and the s o i l ' s res t r ic ted a b i l i t y to absorb heat during the day) increase the l i k e l i -hood of freezing at the interface between a i r and s o i l . The insulat ing qua l i t i e s of detr itus i nh i b i t thermal inputs during the day and, in cold regions, retard 96 microbial a c t i v i t y c r i t i c a l in nutrient mineral izat ion. Also, root metabolism i s strongly dependent on so i l temperature. Nutrient uptake, pa r t i cu la r l y that of P, is strongly inhib ited by low so i l temperatures. Perhaps even more c r i t i c a l than the thermal effects of detr itus accumu-lat ion are the attendant effects of nutrient immobilization in undecomposed d e t r i -tus. The rates of de t r i t a l accumulation, however, were not ind icat ive of nut-r ient accumulation in detr i tus. For example, on the subalpine reclaimed area net accumulation of detr itus over the year was 122 g m on the un fe r t i l i zed plot while the f e r t i l i z e d plot los t 17 g m of detr i tus . However, detr itus N showed the greatest increase on the f e r t i l i z e d plot. So the more rapid detr itus decomposition on the f e r t i l i z e d p lot was more than compensated for by the i n -crease in de t r i t a l N concentration. The concentration in detr itus also i n -creased on the f e r t i l i z e d p lot so that the accumulation of de t r i t a l P was s imi la r in both p lots. Detr i ta l N also increased on both montane reclaimed plots while de t r i t a l P decreased. The greater accumulation of de t r i t a l nutrients on f e r t i l i z e d plots may be misleading. For with higher N and P concentrations and consequent narrowing of C:N, P rat ios decomposition w i l l l i k e l y proceed at a higher rate than on the un fe r t i l i zed plots. So, on the un fe r t i l i zed plots nutrients contained in de-t r i t u s were less mobile and detr itus was more l i k e l y to act as a nutrient sink. Another c r i t i c a l area l i e s in the re la t i ve amounts of nutrients bound in det r i tus . On the subalpine reclaimed area more N accumulated in detr itus on the f e r t i l i z e d plot than on the un fe r t i l i zed p lot . However, on the f e r t i l i z e d plot de t r i t a l N accumulation amounted to 20% of the year ' s shoot N uptake while 86% of shoot N uptake was s t i l l in the detr itus pool by October on the un fe r t i l i z ed p lot . Both montane and subalpine reclaimed areas showed large net increases in de t r i t a l N over the year. However, the October to May period was one of s i g n i f i -cant de t r i t a l decomposition and nutrient release on the montane area while v i r t u a l l y no de t r i t a l decomposition occurred on the subalpine reclaimed 97 area during this period. Unlike N and P, K did not accumulate in detr i tus . Although detr itus mass varied widely throughout the study period de t r i t a l K levels on a l l plots generally _2 remained near 1 g m . This suggests that K leaches readi ly from newly-fallen shoots. Also, K may leach from l i v e shoots and may be e f f i c i e n t l y translocated to l i v e plant parts p r io r to senescence. These results suggest that, re la t i ve to both shoot and root N requirements, a substantial amount of previously mobile N w i l l be immobilized in detr itus on the subalpine reclaimed area i f f e r t i l i z a t i o n is discontinued. P i s bound to a lesser extent in detr itus and K i s not immobilized to any s i gn i f i cant degree. The paucity of legumes on the high-elevation area w i l l aggravate N-deficiencies in the future. On the montane reclaimed area net production continued at high levels without f e r t i l i z a t i o n and nutrients showed no evidence of accumulating to any great extent. Also, f e r t i l i z a t i o n of the montane reclaimed area affected the a l locat ion of photosynthate and nutrients. F e r t i l i z a t i o n tended to increase shoot and detr itus production at the expense of root production. Drought-ki l l ing of th is new shoot material i s taken as the explanation. Also, the large legume component of the montane reclaimed area w i l l help maintain nutrient se l f - su f -f i c iency. 6.2 FATE OF APPLIED NUTRIENTS Nutrients applied to a plant community are subject to s ix fates: 1) plant uptake, 2) erosion, 3) deep leaching, binding in the so i l in e i ther 4) avai lable or 5} unavailable forms and, in the case of N, 6) v o l a t i l i z a t i o n . Fates 1 and 4 represent gains to the plant community while the rest are irreversable losses and some may even degrade surrounding surface or ground waters. Nutrient losses, pa r t i cu la r l y those of deep leaching, v o l a t i l i z a t i o n and so i l tieup are nearly impossible to measure d i rec t l y . To avoid this, problem nut-r ient losses and gains were estimated by inference. F i r s t , shoot and root "uptake" 98 were estimated by adding the nutrient increases in these compartments for each sampling interval between October 1976 and October 1977 which showed a net gain. Shoot and root uptakes of un fe r t i l i zed and f e r t i l i z e d paired plots were then subtracted to y i e l d an estimate of " f e r t i l i z e r e f f e c t " . F e r t i l i z e r e f fect was then divided by the amount of added nutrient and mult ip l ied by 100 to y i e l d an estimate of " f e r t i l i z e r e f f i c i ency " . This approach was taken with the understanding that net uptake as used here is largely a function of sampling frequency and the integration i n te r va l . And, as the interval increases, estimates of net uptake become less sensit ive to short term f luctuat ions. Mindful of these constraints, nutrient uptake, f e r t i l i z e r e f fect and f e r t -i l i z e r e f f i c iency are discussed in the following section. 6.2.1 Nitrogen A l l areas except for the montane reclaimed area registered high f e r t i l i z e r N e f f i c i enc ie s (Table 12). The highest e f f i c iency was apparent in the subalpine reclaimed area where 71% of added N was u t i l i z e d by the plant community. How-ever, 78% of N uptake was s t i l l in shoots at the end of the study while the re -maining 22% went to the root compartment. While tota l N uptake increased 370% on the subalpine reclaimed area, f e r t i l i z a t i o n also caused root:shoot N-uptake rat ios to reverse. On the f e r t i l i z e d p lot the rootrshoot N-uptake rat io was 35: 65 while i t was 60:40 in the un fe r t i l i z ed p lot . On the native plots f e r t i l i z a t i o n resulted in a s l i gh t s h i f t in the d i s -t r ibut ion of N-uptake. For example, on the montane native area the root:shoot N-uptake rat io changed from 92:8 to 87:13 as the resu l t of f e r t i l i z a t i o n . These data indicate the dominant role played by roots of these mountain grasslands in N-uptake, storage and release. Only the montane reclaimed area showed a net loss of N due to f e r t i l i z a t i o n . F e r t i l i z a t i o n resulted in a large gain in shoot N but an even larger loss in root N re la t i ve to the un fe r t i l i zed p lot . Thus, the net f e r t i l i z e r e f fect was -0.07 g m 99 Table 1 2 . E s t i m a t e d f e r t i l i z e r N uptake, e f f e c t and e f f i c i e n c y . SHOOT ROOT TOTAL PLANT UPTAKE + UPTAKE = UPTAKE (g m-2) (g m-2) (g rn- 2) Montane N a t i v e F e r t i l i z e d ' cr j .20 34 .72 3 9 . 92 N o n f e r t i l i z e d 2 .64 30 • 25 32 .89 " F e r t i l i z e r E f f e c t " 2 .56 4 .47 7 .03 " F e r t i l i z e r E f f i c i e n c y " 54 .1% Montane Reclaimed F e r t i l i z e d 5, .53 .6, .13 1 1 . 6 6 N o n f e r t i l i z e d 3. .82 7. • 91 1 1 . 7 3 " F e r t i l i z e r E f f e c t " 1. .71 - 1 . .78 - .07 " F e r t i l i z e r E f f i c i e n c y " 0% S u b a l p i n e N a t i v e F e r t i l i z e d 3. 79 4 6 . 15 49 .94 N o n f e r t i l i z e d 1. 84 4 2 . 02 43 . 86 " F e r t i l i z e r E f f e c t " 1. 95 4 . 13 6 . 08 " F e r t i l i z e r E f f i c i e n c y " 4 6 . 8 % S u b a l p i n e Reclaimed F e r t i l i z e d 8. 52 4 . 12 12.64 N o n f e r t i l i z e d 1. 34 2 . 08 3. 42 " F e r t i l i z e r E f f e c t " 7. 18 2. 04 9 .22 " F e r t i l i z e r E f f i c i e n c y " 7 0 . 9 % . 100 y ie ld ing 0% f e r t i l i z e r e f f i c iency. The influence of drought on this phenomenon has been discussed in previous sections. Perhaps as surprising as the negative f e r t i l i z e r e f f i c iency on the mon-tane reclaimed area were the high e f f i c i enc ie s on the other areas. F e r t i l i z e r e f f i c iency was probably a function of two major factors: so i l moisture and nut-r ient competition from non-vascular users (decomposers). So i l s on the two native areas and the subalpine reclaimed area seemed to remain at least palpably moist throughout the summer. The native area so i l s were r ich in organic matter which tended not only to capture and hold moisture but also served as substrate for decomposers. Thus, f e r t i l i z e r N-efficiency was lower on the native areas than on the subalpine reclaimed area which was well-suppl ied with so i l moisture throughout the summer while nearly devoid of s o i l organic matter. A high rate of f e r t i l i z e r N (130 kg ha~^) was applied in this study. This i s roughly 500% of Kaiser Resources' normal rate of N- fer t i1 i zat ion. That even at this level high N uptake e f f i c i enc ie s were achieved suggests several conclusions. F i r s t , in vigorously growing reclamation plant communities normal rates of N - f e r t i l i z a t i on w i l l be quickly incorporated by the plants result ing in i n s i g -n i f i can t N-losses v ia v o l a t i l i z a t i o n , leaching or f i x a t i on . Of part icu lar con-cern pr ior to the study were the extent of N-losses due to the v o l a t i l i z a t i o n of NHg. The reclamation " s o i l s " were basic and tended to become warm and dry in mid-summer, perfect conditions for the oxidation of NH^. F e r t i l i z e r was ap-p l ied during a very l i gh t rain so that nearly optimal conditions for f e r t i l i z a t i o n prevailed. Also, because the three plant communities were able to accelerate N-uptake rates l i t t l e applied N v/as avai lable for leaching or v o l a t i l i z a t i o n . S ign i f icant loss of th is sort may well have occurred on the montane reclaimed area where enough N entered the plants to shrink the root systems and accelerate shoot growth. However, this probably represented only a f ract ion of applied N. In order to make f e r t i l i z a t i o n more e f f i c i e n t N should be applied, along with 101 the other nutr ients, ea r l i e r in the season. Regular maintenance f e r t i l i z a t i o n of these areas i s usually applied sometime in June. This caused the f e r t i l i z e d area to begin rapid shoot growth just before the drought period began. Con-sequently, that N which was u t i l i z e d tended to work to the detriment of the plant community while most of the applied N was probably lo s t via v o l a t i l i z a t i o n . In a wetter year this late appl ication date might not have had such adverse ef fects . However, the c l imat ic data indicate that the July drought i s a regular occurrence. In order to maximize u t i l i z a t i o n of added N pr ior to the drought period future f e r t i l i z a t i o n of the low to mid-elevation s i tes should, i d ea l l y , be completed by the th i rd week of May. Thus, the plants would have both moisture and nutrients during the maximum growth period of late May to late June. F e r t i l i z a t i o n of sub-alpine areas should be completed by the f i r s t week of June. 6.2.2 Phosphorus Compared to N, the u t i l i z a t i o n of applied P was extremely low. The highest f e r t i l i z e r P e f f i c iency was measured on the subalpine native plot at 36%. The subalpine reclaimed area was 16% and the montane native area only 7%. As was the case with N the montane reclaimed area showed a net decrease in P uptake due to f e r t i l i z a t i o n (Table 13). The high levels of Ca in a l l of these so i l s undoubtedly influenced the low P uptake rates. High so i l Ca levels combined with surface appl ication would tend to maximize calcium phosphate formation and thus remove a large part of the added P from the nutrient cycle. That f e r t i l i z a t i o n resulted in a doubling of shoot P uptake in the montane native area yet a s l i gh t decrease in root P uptake suggests that the plant com-munity was already well-supplied with avai lable P without f e r t i l i z a t i o n . The ad-d i t ion of f e r t i l i z e r caused a doubling of shoot mass and the P demands of the added mass were met with no increase of shoot or root P concentration. The rate of shoot P uptake also doubled on the montane reclaimed area after f e r t i l i z a t i o n . However, the rate of root P uptake dropped far below that 102 Table 1 3 . E s t i m a t e d f e r t i l i z e r P uptake, e f f e c t and e f f i c i e n c y . SHOOT ROOT TOTAL PLANT UPTAKE + UPTAKE = UPTAKE (g rn"2) (g m-2) ( g m - 2 ) Montane N a t i v e F e r t i l i z e d .82 ' 2 .34 3.16 N o n f e r t i l i z e d .34 2 .36 2.70 " F e r t i l i z e r E f f e c t " .48 — • .02 .46 " F e r t i l i z e r E f f i c i e n c y " 6.7% Montane Reclaimed F e r t i l i z e d . .54 .67 1.21 N o n f e r t i l i z e d .25 .99 1.24' " F e r t i l i z e r E f f e c t " .29 - • 32 - .03 " F e r t i l i z e r E f f i c i e n c y " .0 58 S u b a l p i n e N a t i v e F e r t i l i z e d .48 5 .20 5.68 N o n f e r t i l i z e d .27 2 . 9 5 ' 3 .22 " F e r t i l i z e r E f f e c t " . 21 2 .25 2.46 " F e r t i l i z e r E f f i c i e n c y " - 35:M . S u b a l p i n e Reclaimed F e r t i l i z e d .75 • .92 1.67 Noiif e r t i l i z e d .26 • 31 .'57 " F e r t i l i z e r E f f e c t " .49 .61 1.10 " F e r t i l i z e r E f f i c i e n c y " 1 6 . 0 % 103 of the un fe r t i l i zed plot y ie ld ing a s l i gh t net decline in P uptake due to f e r t -i l i z a t i o n . As was true of N uptake on this area f e r t i l i z a t i o n had l i t t l e ef fect on the net plant P uptake. Rather, f e r t i l i z a t i o n influenced the par t i t ion ing of the incorporated nutrients. In the case of both N and P the repart i t ion ing involved a massive diversion of nutrient to the shoots at the expense of the roots. Since the root systems of the reclaimed plant communities were already small th i s trend could have an adverse e f fect on i t s a b i l i t y to withstand f u r -ther drought and to store carbohydrates and nutrients over winter. Also, i f continued, this phenomenon would tend to drive the plant processes away from those displayed in the native areas. So, f e r t i l i z a t i o n induced, on the reclaimed areas at least, a detritus-based nutrient cycle. Whereas nutrient exchanges v ia the detritus compartment were minor in re lat ion to those of the root compartments of native areas, on reclaimed areas nutrient f lux via the detr itus pool was only s l i g h t l y smaller than root f lux for N and was equal to root f lux for P. Part-i c u l a r l y on the montane reclaimed area, f e r t i l i z a t i o n tended to accelerate this process. In short, i f the nutrient exchange processes of the native grasslands were indicat ive of stable grasslands in this region then continued f e r t i l i z a t i o n , at least of the montane reclaimed area, i s a destab i l i z ing factor. The case of the subalpine reclaimed area was quite d i f fe rent . There, N and P levels in the plant community were so low that f e r t i l i z a t i o n resulted in large gains to the root system. Also, s o i l moisture was su f f i c i en t that drought effects did not confound f e r t i l i z a t i o n e f fec t s . The subalpine area may well r e -present a plant community in the early stages of development, as evinced by the negl ig ib le annual root a t t r i t i o n . The montane reclaimed area, however, underwent a large root a t t r i t i o n in the f a l l of 1976 and 1977. This suggests that the mon-tane reclaimed area has reached a degree of maturity and supports as much biomass as i t possible under the circumstances. In other words, the montane reclaimed area has developed to the point where factors other than nutrient a v a i l a b i l i t y l i m i t sustainable biomass. The dominant factor among these i s , doubtless, s o i l 104 moisture. Thus, any increment in avai lable so i l nutrient levels has no influence on standing crop. Rather, i t merely repart i t ions the standing crop. In this case, the repart i t ion ing occurred to the detriment of the plant community. For the subalpine reclaimed area, in contrast, avai lable s o i l nutr ients, pa r t i cu la r l y N and P, were s t i l l the dominant l im i t i ng factors. Consequently, f e r t i l i z a t i o n increased net production and sustainable standing crop. As the previous discussions indicated, decomposition and nutrient mineral ization were rest r ic ted on this area. This tendency w i l l probably continue. Thus, N and P a v a i l a b i l i t y w i l l continue to be c r i t i c a l l im i t i ng factors to production on the subalpine reclaimed areas. 6.2.3 Potassium The ef f i c iency of f e r t i l i z e r K uptake was high on only the subalpine re-claimed area. On the subalpine native area i t was 0% while only 26% on the mon-tane native area (Table 14). K was the only nutrient which showed any e f f i c iency of uptake on the montane reclaimed area. On both native areas root K uptake de-cl ined due to f e r t i l i z a t i o n . Except for the subalpine native area a l l areas showed strong increases in shoot K uptake due to f e r t i l i z a t i o n . The low u t i l i -zation rate of K in the native areas and the montane reclaimed area supports the argument, presented in e a r l i e r sections, that f e r t i l i z e r K entered into an equ i l -ibrium between slowly avai lable and avai lable form. This explanation would pre-suppose the presence of expanding-lattice clays in substantial quant it ies. That f e r t i l i z a t i o n resulted in a net posit ive uptake on the montane reclaimed area ref lects i t s strong translocation to the shoots. Thus, even though f e r t i l i z a t i o n caused a loss in net root production on th i s area, th is had l i t t l e e f fect on the net plant uptake of K. In conclusion, f e r t i l i z a t i o n had a s l i gh t posit ive ef fect on root K uptake on the reclaimed areas while i t caused a minor decrease in root K uptake in the native areas. In contrast, f e r t i l i z a t i o n tended to increase shoot K uptake. Whether this increase in shoot K uptake was merely "luxury consumption" or 105 Table '14 . E s t i m a t e d f e r t i l i z e r K uptak e , e f f e c t and e f f i c i e n c y . SHOOT ROOT TOTAL PLANT UPTAKE + UPTAKE = UPTAKE (g rn"2) (g m-2) (g m - 2 ) Montane N a t i v e F e r t i l i z e d 6 .96 2 .47 9 . 4 3 N o n f e r t i l i z e d 3 .24 3 .98 7. 22 " F e r t i l i z e r E f f e c t " 3 .72 - l .51 2 . 21 " F e r t i l i z e r E f f i c i e n c y " 2 6 . 5 % Montane Reclaimed F e r t i l i z e d 4 .20 1 .86 6 .06 N o n f e r t i l i z e d 2 .55 1 .78 4 . 3 3 " F e r t i l i z e r E f f e c t " 1 .65 .08 1.73 " F e r t i l i z e r E f f i c i e n c y " 20 . 8% S u b a l p i n e N a t i v e F e r t i l i z e d . s 2 .23 3 .27 5-50 N o n f e r t i l i z e d 2 .49 4 .25 6 . 74 " F e r t i l i z e r E f f e c t " - .26 - .98 . -1.24 " F e r t i l i z e r E f f i c i e n c y " 0 35 S u b a l p i n e Reclaimed F e r t i l i z e d 10 .62 1 .10 1 1 . 7 2 N o n f e r t i l i z e d 2 .63 .67 • 3 .30 " F e r t i l i z e r E f f e c t " 7 .99 .43 8.42 " F e r t i l i z e r E f f i c i e n c y " 1 0 1 . 6 % 106 benefited the plant community i s uncertain. 6.3 SUMMARY OF DISCUSSION A clear picture of two types of grass-forb communities emerged in the foregoing discussion. The two community types appear s imi lar from the surface and even maintained s imi lar shoot standing crops in summer. However, in terms of community function (net production, decomposition and nutrient cycling) they were very d i f ferent . The native areas represent the f i r s t functional type. Its most outstanding feature was the dominance of below-ground plant structures in the storage and release of carbohydrates and nutrients. This root-based carbohydrate and nut-r ient cycle i s typica l of temperate grasslands and becomes even more pronounced at high elevations and high la t i tudes . The rapid turnover of carbohydrates and nutrients deep in the so i l results in the character i s t ic Ah horizon of grassland s o i l s . The advantages of such a system are many. For example, even though most of the system's nutrients are " l o s t " each f a l l through root a t t r i t i o n the Ah horizon in r ich in root-supplied organic matter capable of holding the mineral-ized cations in exchangeable form. Also, the sloughed roots provide an avai lable energy source for decomposers which allow rapid mineral ization so that the cycl ing rate of sloughed nutrients remains high. In these areas the dry summer often leaves the so i l surface dry. This i nh ib i t s the decomposition of surface detr itus and desiccates shallow rooted plants. However, the organic matter of the native so i l s hold considerable moisture even during extended drought periods. This not only serves the plant water demands but maintains microbial a c t i v i t y and nutr ient mineral izat ion. Also, this functional type i s capable of storing a large pool of carbohydrates and nutrients for immediate use by the plant in spring. The a v a i l -a b i l i t y of this store is c r i t i c a l since in this region, the optimal growth period i s compressed between the long winter and the dry summer. Consequently, the plants must be able to photosynthesize most of the i r annual carbohydrate needs within a roughly four-week period ( late May to late June). 107 The reclaimed areas represent the other functional type which became evident in this study. The type was characterized by narrow root:shoot ra t io s . In this type the magnitude of carbohydrate and nutrient f lux through roots and detr itus were s imi la r . Thus, while the magnitude of detr itus compartment ex-change processes was minor in re lat ion to tota l community f lux on the native areas, i t was a major contributor to total f lux on the reclaimed areas. As i n -dicated previously, this phenomenon can have two adverse e f fects . F i r s t , the surface detr itus dries out rapidly and thus decomposition and nutrient mineral-izat ion are inh ib i ted. Also, since a major portion of the communities' nutrients leach down from the so i l surface the root system would tend to develop near the surface. This would retard the formation of an Ah horizon and increase the su scept ib i l i t y of the community to drought. In short, this type of plant com-munity would be more susceptible to natural perturbations and would, therefore, be less stable. For convenience, th i s functional type w i l l be ca l led a det r i tu s -root nutrient cycle. The causes behind the development of a root-based nutrient cycle on the native areas and a detr i tus-root cycle on the reclaimed areas are not clear. In the early stages of primary succession p r i s t ine grasslands may possess cycl ing systems s imi lar to those of the reclaimed areas and the root-based system may only be ind icat ive of mature grasslands on mature s o i l s . However, i t is possible that the detr i tus-root type was the resu l t of revegetation with agronomic forage crops which have been selected to produce large, nut r ient - r i ch shoot masses. However, the results of this study cannot answer this question since s o i l s , species and community age were unavoidably confounded. It i s c lear , however, that f e r t i l i z a t i o n resulted in greater carbohydrate and nutrient cycl ing through the detr itus compartment and narrowed root:shoot rat ios . These effects were s l i gh t on the native areas and profound on the re-claimed areas. The long-term, heavy appl icat ion of f e r t i l i z e r to the native areas would probably result in changes in community composition and perhaps even 108 in a drast ic s h i f t in the community's cycl ing system. Such change could occur through the invasion of species better able to u t i l i z e the highly avai lable i n -organic nutrients and to convert them into enough shoot mass to out-compete the climax perennials for l i g h t . Indeed, the f e r t i l i z a t i o n of native ranges has occasionally led to the invasion of "weedy" species._ F e r t i l i z a t i o n would change the root-based cycl ing system from an asset to a l i a b i l i t y in that the apportionment of most of the p lant ' s photosynthate to the roots at the expense of the shoots would be unnecessary for nutrient accumulation and storage. Thus, plant species possessing the minimum necessary root mass and maximum shoot mass would soon shade the previous climax species. This phenomenon may expla in, in large part, the absence of s i gn i f i cant native grass invasion on f e r t i l i z e d re -claimed areas. Conversely, i t seems l i k e l y that i f f e r t i l i z a t i o n on reclaimed areas is discontinued after adequate so i l enrichment has occurred that the root-based system would slowly encroach. The encroachment process would, of course, be accelerated by d i s t r ibut ion of the appropriate propagules. The tendency of f e r t i l i z a t i o n to induce a detr i tus-root cycle figures in the development of the reclaimed areas as we l l . Within these plant communities there appeared to be a development phase, when maintenance f e r t i l i z a t i o n resulted in a net accumulation of perennating structure and nutr ients, and a mature phase when maintenance f e r t i l i z a t i o n was unnecessary and even inhib i ted further de-velopment. The subalpine reclaimed area represented development phase and the montane reclaimed area the mature phase. In the development phase the plant community has not accumulated enough carbohydrate and nutr ients; nor has i t s u f f i c i en t l y enriched the s o i l that i t can survive the interruption of maintenance f e r t i l i z a t i o n without serious d i s -ruption. Thus, during the development phase maintenance f e r t i l i z a t i o n is c r i t i c a l . The adverse effects of f e r t i l i z a t i o n of a mature area have already been discussed though, in th is case, drought aggravated the effects of f e r t i l i z a t i o n . Proof that these two reclaimed area are in the suggested developmental states w i l l be 109 in the i r future performance without f e r t i l i z a t i o n . Monitoring data on these areas are now avai lable for the summer of 1978 (Fyles, 1979). The data indicate that, indeed, the montane reclaimed area main-tained i t s 1977 level of net production without f e r t i l i z a t i o n while net production continued to decline on the subalpine reclaimed p lot . Though these two areas both received i n i t i a l reclamation treatments in 1974 thei r levels of development were very d i f ferent between 1976 and 1978. This was due to the retarding ef fect of the cold, dry subalpine environment on the development of reclamation plant communities. The combination of cold and sur-face dessication aggravated problems associated with the detr i tus-root nutrient cycle in that a large part of the system's nutrients were t ied up in undecomposed surface detr i tus . Indeed, the subalpine climate of this region may ensure that these reclaimed areas w i l l never reach the mature stage of the montane reclaimed areas. The solution to this problem may well l i e in the use of adapted native herbaceous species which w i l l a l locate a greater portion of the i r photosynthate to the root system and, s ac r i f i c i ng shoot production, thus develop a root-based nutrient cycle. The persistance of the mature phase on the montane reclaimed area is not certa in. It is possible that, for example, with i t s shallow root system a three to four year period of very dry summers could cause severe damage. However, i t seems more l i k e l y that these plant communities w i l l pers ist for a considerable time. Eventually they w i l l probably be supplanted by local ecotypes which are phys io log ica l ly , reproductively and morphologically better adapted to the region. 7.0 IMPLICATIONS FOR RECLAMATION Perhaps the most s i gn i f i cant result of this study was the development of a method by which the degree of nutrient s t a b i l i t y and maturity of reclaimed areas can be assessed. Two d i s t i n c t phases in the development of reclamation plant communities were i den t i f i ed . The immature phase i s characterized by a small root system that undergoes 110 l i t t l e yearly a t t r i t i o n , and a major portion of the system's avai lable nutrients are transferred from the shoots to the detr itus in the f a l l . Consequently, un-less rapid de t r i t a l decomposition occurs the plant community becomes nutrient def ic ient and quickly loses productiv ity. N and P are immobilized to the great-est extent in surface detr itus while K i s leached from the det r i tus . The slow decomposition of detr i tus i s aggravated by cold and dry conditions. Therefore, the high elevation areas are most l i k e l y to experience N and P def ic iencies and require longer periods of maintenance f e r t i l i z a t i o n , pa r t i cu la r l y with N and P. The mature phase is recognized by a larger root system which undergoes a high rate of turnover each year. Since the large root turnover places in the so i l a large cycl ing pool of nutrients which mineralize rap id ly , these communities no longer require maintenance f e r t i l i z a t i o n . Indeed, f e r t i l i z a t i o n in a drought year can damage a mature reclaimed area. Knowing that root and de t r i t a l dynamics are the key areas for nutrient cycl ing in these reclaimed areas i t i s necessary only to sample shoots, roots and detr itus for a f u l l year or more. Chemical analysis of this material pro-vides helpful information and should be carried out in an area where no previous work has been done. However, once the nutr ient concentrations are established further analyses may be unnecessary as nutrient concentrations tended to remain stable for given phenological events. Estimates of s o i l nutrient levels tended to vary widely and were d i f f i c u l t to interpret due to the i r low precis ion. Generally, there was l i t t l e correlat ion between so i l nutrient estimates and plant behavior or de t r i t a l decomposition. In future studies th i s aspect should receive less attent ion. Mature reclamation plant communities should not be f e r t i l i z e d . Immature plant communities should be. While there is no indicat ion of how long the mature communities w i l l pers i s t , they w i l l l i k e l y pers ist at least several years after f e r t i l i z a t i o n i s discontinued with l i t t l e drop in product iv ity. The immature communities w i l l decline rapidly in productivity immediately af ter the discontinuance I l l of f e r t i l i z a t i o n . They w i l l not, however, die o f f immediately. Most of the plants w i l l survive for at least two years though production w i l l f a l l drast-i c a l l y . Immature reclamation plant communities do not necessarily become mature plant communities. At subalpine and alpine locations reclamation plant commu-n i t ie s may never become mature unt i l adpated native species become established. This i s an area of research that requires a great deal more attent ion. The overburden in th is area i s calcareous. So, most of the surface-applied P is bound in unavailable form in the s o i l . In the currently-used f e r t -i l i z e r mix (13-16-10) there i s only half as much P as N. Due to s o i l immobili-zation even less P is avai lable to the plant. Therefore, 13-16-10 appl ication provides the plant with a disproportionate amount of N and very l i t t l e P. Since surface broadcast application is the only pract ical method of applying maintenance f e r t i l i z a t i o n this problem might only be a l lev iated by using a f e r t i l i z e r with a higher percentage of P. K cycles rapidly and did not appear to be in short supply. However, even with K additions each year the legumes have become dras-t i c a l l y less abundant on a l l reclaimed areas. This may not be due to competition with the grasses for K, but as long as N i s added year ly, K should be added as well i f only as a precaution. K-deficiency symptoms were observed in legumes on reclaimed areas. Therefore, a f e r t i l i z e r grade or mixture y ie ld ing approxi-mately 10-40-10 i s recommended. Maintenance f e r t i l i z a t i o n should be completed by the th i rd week of^May on the low elevation areas and the f i r s t week of June on the high elevation areas. These dates usually coincide with the f i r s t evidence of shoot growth on the reclaimed areas. Since large areas are f e r t i l i z e d the process can take sev-eral weeks. Therefore, some areas are f e r t i l i z e d too early and some too la te . For this reason dates were suggested for the completion of f e r t i l i z a t i o n since waiting for the evidence of shoot growth w i l l guarantee that some areas are not f e r t i l i z e d unt i l late June. Early f e r t i l i z a t i o n w i l l result in some f e r t i l i z e r . 112 loss but this i s considered minor compared to the damage done by late f e r t i l i -zation. Also, el imination of maintenance f e r t i l i z a t i o n on many of the montane areas w i l l shorten the time required to complete the annual f e r t i l i z a t i o n pro-gram. Ear l ie r f e r t i l i z a t i o n w i l l mitigate the tendency of f e r t i l i z a t i o n to ex-tend the growth period into the summer drought period at low elevations and into f a l l at high elevations. "Top dressings" of ammonium sulphate or ammonium n i t rate are sometimes applied in mid-summer when the plants begin to look ch lorot ic . This practice should be discontinued as the chlorosis i s the result of drought-induced dor-mancy. Any attempt to break this dormancy by top dressing to cause a "greening" of the reclaimed area only damages the root systems. The immature plant community monitored in this study was capable of ab-sorbing much more f e r t i l i z e r than i s usually added in maintenance appl icat ions. However, most of the additional N remained in the shoots unt i l f a l l when i t was f rost k i l l e d , whereas a majority of the added P resided in the roots by the f a l l This suggests that greater additions of P could be retained by the plants while large N additions are wasted. Therefore, the current rate of 200 kg 13-16-10 ha~* should be raised to about 300 kg 10-40-10 ha"*. This would increase added N s l i g h t l y and increase P by 370% thereby accelerating development of a vigorous root system. Also, by stopping the practice of top dressing the onset of f a l l dormancy should be hastened. 8.0 CONCLUSIONS 1. F e r t i l i z a t i o n stimulated the production of shoot mass on both native and reclaimed areas. Where so i l moisture was l im i t i ng (montane reclaimed area) the increase in shoot production did not result in greater mid-summer standing crops. Rather, i t merely accelerated nutrient and carbohydrate f l ux through the shoot compartment and increased additions to the detr i tus pool. The maintenance of a high shoot production caused a reduction of net root production. On the other study areas, though f e r t i l i z a t i o n narrowed 113 root:shoot ratios i t also increased net root production. F e r t i l i z a t i o n also tended to accelerate de t r i t a l decomposition. On a l l study s i tes f e r t i l i z a t i o n caused larger shoot masses to pers i s t into the f a l l , thus f a l l dormancy was delayed. 2. Even at the high f e r t i l i z a t i o n rates used in this study plant uptake of N was high suggesting l i t t l e N-loss via v o l a t i l i z a t i o n or leaching. The drought-affected montane reclaimed area did not follow th i s trend. Rather, f e r t i l i z a t i o n resulted in a net loss of N to the plant community. P u t i -l i z a t i on was low due to the surface appl ication of P on calcareous s o i l s . Thus, phosphates were immobilized by Ca and Mg. K u t i l i z a t i o n was high on the subalpine reclaimed area and low elsewhere. 3. The native and reclaimed areas d i f fered dramatically in net productiv ity and the a l locat ion of photosynthate. The native areas were much more pro-ductive with most of the photosynthate translocated to the i r massive root systems. 4. The differences in plant phenology and morphology between native and reclaimed areas resulted in d i f ferent systems for nutrient and carbohydrate cyc l ing. The native areas possessed a root-based cycle in which the bulk of the annual turnover of nutrients and carbohydrates occurred below-ground. On the re-claimed areas roughly equal portions of the system's nutrients and carbo-hydrates were released via the detritus and root pools. 5. Factors which affected surface detr itus decomposition were, thus, c r i t i c a l in determining the rate of nutrient cycl ing and the degree of nutrient s e l f -suff ic iency on the reclaimed areas. The productiv ity of root systems was another c r i t i c a l factor. Reclaimed areas which, without maintenance f e r t -i l i z a t i o n , showed vigorous root growth in spring and nearly equal f a l l a t t r i t i o n and which apparently reached steady state detr itus levels were considered "mature". Reclaimed areas with small root systems which under-went neither rapid spring growth nor major f a l l a t t r i t i o n and which accumulated 114 detr itus throughout the study were considered "immature". Immature reclamation plant communities of this area accumulate, with annual f e r t i l i z a t i o n , carbohydrates in the root and surface detritus pools. If the communities develop s u f f i c i e n t l y , a mature stage i s reached where, without f e r t i l i z a t i o n , decomposition roughly matches shoot inputs to detr itus and detritus ceases to accumulate upon reaching steady state levels . Also, as the root systems develop to a mature state a large root - so i l - root exchange system develops. Immature plant communities require maintenance f e r t i l i z a t i o n , mature com-munities do not. Even the mature reclamation plant communities are not as stable as native grasslands. They w i l l continue to be more susceptible to drought and do not have the massive carbohydrate and nutrient pools character i s t ic of the native areas. At the mature stage, when maintenance f e r t i l i z a t i o n is discontinued efforts can be made to introduce native species to the reclaimed area. At least in subalpine and montane areas of southeastern B r i t i s h Columbia ef forts to introduce native species while f e r t i l i z a t i o n i s s t i l l practiced w i l l re -su l t in minimal success unless competition from the agronomic species is reduced. Immature reclamation areas w i l l not necessarily develop into mature plant communities. Factors retarding de t r i t a l decomposition, low temperatures and moisture may ensure that, with current reclamation pract ices, subalpine and alpine reclaimed areas w i l l never mature or w i l l do so very slowly. Native and reclaimed plant community dynamics w i l l change even short d i s -tances from the study area. Therefore, s imi lar studies done elsewhere should begin with a s im i l a r l y high sampling intens i ty. While the results of this study w i l l be important to reclamation planning on the study area, the main contribution of this work l i e s in the i den t i -f i ca t ion of a method which, within a r e l a t i ve l y short time, can give a better 115 understanding of the development cf reclamation plant communities than has hitherto been possible. The applications outside the f i e l d of reclamation are numerous, though i t is su f f i c ient that a method now exists by which se l f -su f f i c ient reclamation plant communities can be ident i f ied. 9.0 AREAS FOR FURTHER RESEARCH The methods developed in this study have wide application. In the f i e l d of reclamation the following research may now y ie ld valuable results: A. The contribution of genetics in determining plant phenology and eventual nutrient se l f - suf f ic iency. 1. Do native herbaceous species posses adaptive features which accelerate the development of nutrient se l f -suff ic iency ( i . e . greater internal- ' cycl ing, more rapid entry into winter dormancy, greater al location of photosynthate and nutrients to the roots)? 2. If these characteristics exist, are they s ignif icant at the community level of integration? B. What maintenance f e r t i l i z a t i o n programs optimize the development of nutrient self-suff ic iency? 1. Effects of f e r t i l i z e r grade, rate and maintenance period on community function. 2. The relat ive nutrient requirements cf native and agronomic reclamation plant communities. These questions could be answered in simple, though long-term, studies. Mixtures of appropriate native and agronomic species could be sown on overburden and mature, devegetated s o i l . The use of a range of f e r t i l i z e r rates, grades and maintenance periods would complete the treatments. Monitoring of the shoot, root and detritus pools over time wou'd illuminate most of the questions l e f t answered by this study. 116 10.0 LITERATURE CITED Ahlgren, I.F. and Ahlgren, C E . 1960. Ecological effects of forest f i r e s . Bot. Rev. 26:483-533. Aleksandrova, V.D. 1970a. Above-ground and below-ground plant biomass of d i f ferent a r c t i c subzone assns. J_n. A.E. Ershov (ed.). Bio-log ical Basis of the U t i l i z a t i o n of Northern Nature, pp. 13-19 SSR Acad. Sc i . Aleksandrova, V.D. 1970b. The vegetation of the tundra zones in the USSR and data about i t s productiv ity. I_n. W. A. Ful ler and P. G. Kevar (eds.). Productivity and Conservation in Northern Circum-poplar Lands. Edmonton, Alberta. B a t z l i , G.0. 1974. Production, ass imi lat ion and accumulation of organic matter in ecosystems. J . Theor. B i o l . 43:1-13. Bauer, H.J. 1973. Ten Years' Studies of Biocenological succession in the excavated mines of the Cologne Lignite D i s t r i c t . Jj^. R.J. 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F and NF designations represent f e r t i l i z e d and non- fe r t i l i zed plots respectively. 129 NITROGEN (G M**-2) MONTANE NATIVE F DET-SHOOT+RITUS+ROOT=TOTAL X AUG 4.48 7. 88 31. 28 43. 64 740. 32 OCT 1. 18 5. 94 16. 19 23.31 755.33 MAY 1.90 1 1. 71 12. 26 25.86 915. 06 JUN 6.38 7.11 46.98 60.47 940.24 SOIL SX 107. 77 78. 46 75. 34 36. 71 AUG 5.52 10. 49 33. 66 49. 67 782. 88 75. 98 OCT 1. 63 6. 29 25. 84 33. 77 1062. 68 57.00 90% CONFIDENCE LIMITS LOWER UPPER 425.63 1055.01 526.23 984.43 695.07 1 135.05 833.05 1047.43 56 1. 02 1004.74 896.24 1229.12 MONTANE NATIVE NF AUG 4. 98 10.82 28. 85 44. 65 606. 59 108. 38 290. 12 923.06 OCT 0.70 4.53 21.19 26.42 1290.60 MAY 1. 63 16. 67 13.26 31. 56 852. 11 JUN 3. 34 8. 37 43.51 55. 22 664. 65 AUG 2.12 11.16 41.54 54.83 672.24 OCT 1.03 10.72 22.67 34.43 945.30 93. 02 101 8.98 1562.22 95. 55 573. 10 1 13 1. 12 229.31 1099.99 430.49 913.99 149. 09 32. 79 120. 46 593.56 1297.04 MONTANE RECLAIMED F AUG 2. 53 4. 19 5. 09 1 1. 82 176.58 3. 97 164.99 188. 17 OCT 1. 79 1 . 76 0. 95 4. 50 255. 33 48. 80 112.83 397.83 MAY 2. 88 3. 82 5. 34 12. 03 214.56 40. 56 96. 12 333.00 JUN 5. 59 5. 11 7. 08 17. 78 174.06 38. 70 6 1.06 287.06 AUG 2. 16 6. 37 7. 0 3 15. 55 243.57 41.71 12 1.78 365.36 OCT 3. 89 2. 92 4. 42 11. 24 145. 30 38. 89 3 1.74 258.86 MONTANE RECLAIMED NF AUG 4. 05 3. 69 2. 02 9.76 407. 19 77. 12 182.00 632. 38 OCT 0. 88 1 . 22 1. 15 3. 26 487.07 94. 84 210. 14 764.00 MAY 2. 55 6. 63 3. 88 13. 05 333. 13 37. 33 224.13 442. 13 JUN 4. 70 6. 02 9. 06 19.77 456.64 31. 38 36 5.01 548.27 AUG 2. 12 4. 88 7. 72 14. 72 481.27 27. 70 40 0.39 562. 15 OCT 1. 87 3. 12 5. 79 10.77 239.78 71.79 30. 15 449.41 130 NITROGEN (G M**-2) SUBALPINE NATIVE F 90% CONFIDENCE DET- SOIL LIMITS SHOOT+aiTUS+ROOT-:TOT AL X SX LOWER UPPER AUG 2. 53 7. 02 2 1.03 30. 63 748. 57 69. 19 546.54 950.60 OCT 0. 68 3. 98 6.92 11. 58 529.11 68. 90 327. 92 73 0.30 MAY 1. 45 10. 97 52.05 64. 46 727.28 89. 46 466.06 98 8.50 JUN 4. 47 7. 40 53. 07 64. 94 679.05 35. 19 576.30 781.80 AUG 4. 10 5. 11 50. 94 60. 16 39R.65 182. 09 -133.05 930.35 OCT 3. 26 3. 61 1 9. 29 26. 16 581.32 180. 17 55.22 1 107. 42 SUBALPINE NATIVE NF AUG 2. 16 9. 10 2 1.29 32. 54 655.30 39. 51 53 9.93 770. 67 OCT 0. 71 4. 18 8. 29 13. 18 533. 72 72. 62 321.67 745. 77 MAY 1. 52 3. 06 23. 21 27. 78 511.71 59. 62 33 7. 62 685. 80 JUN 2. 55 3. 47 50. 31 56.33 462.35 105.79 153. 44 771. 26 AUG 1. 44 6. 35 36.25 44. 04 360.89 6 1. 82 180.38 54 1. 40 OCT 0.39 2. 98 15. 50 18. 87 518.08 80. 79 282.17 753. 99 SUBALPINE RECLAIMED F AUG 3. 55 0. 46 0. 57 4. 59 47. 53 2. 65 39.79 55. 27 OCT 1. 18 0. 05 0.51 1. 73 65. 82 8.72 40,36 9 1. 28 MAY 0. 70 2. 27 1.85 4. 82 55. 36 2. 57 47. 86 62. 86 JON 6,84 2. 62 3. 26 12.72 47. 34 3. 31 37.67 57. 01 AUG 9. 22 3. 25 4. 6 3 17. 11 43.27 6. 37 24. 67 61. 87 OCT 5. 08 1. 75 3.83 10. 67 40. 55 1.62 35.82 45. 28 SUBALPINE RECLAIMED NF AUG 2. 45 0. 35 0. 64 .3. 44 48.77 6. 98 28.39 69. 15 OCT 0. 89 0. 65 0. 48 2. 02 70. 33 9. 59 42.33 9 3.33 MAY 0. 60 1. 69 1. 08 3. 36 55.24 0. 57 53. 53 56.90 JUN 1.94 2. 40 1. 56 5. 90 45. 82 2. 05 3 9.83 51.81 AUG 1.14 1. 78 2. 56 5. 47 33. 49 5. 02 18.83 48.15 OCT 0. 77 1. 81 2. 09 4. 67 42. 49 2. 14 36.24 48.74 131 PHOSPHORUS (G M**-2) MONTANE NATIVE F DET-SHOOT+RITUS+ROOT=TOTAL AUG 0.73 1. 12 1.85 3. 70 OCT 0.41 1. 51 3. 26 5. 18 MAY 0. 30 1 .08 1.14 2. 52 JUN 1. 12 0. 86 3. 48 5. 45 AUG 0. 73 1. 33 3.39 5. 45 OCT 0. 29 0.74 1. 34 2. 87 MONTANE NATIVE NF AUG 0. 85 1 . 12 1. 87 3. 83 OCT 0.24 1.60 3. 47 5. 32 MAY 0. 23 1 . 58 1. 30 3. 11 JUN 0. 57 0. 96 3.6 6 5. 18 AUG 0. 43 1.72 3. 40 5. 55 OCT 0. 20 1. 49 2. 52 4. 21 MONTANE RECLAIMED i F AUG 0. 34 0.41 0.32 1. 57 OCT 0. 53 0.32 0. 53 1. 43 MAY 0. 32 0. 45 0.76 1. 53 JUN 0. 54 0.92 0. 75 2. 20 AUG 0.21 0.77 1.19 2. 16 OCT 0. 53 0.31 0. 68 1. 52 MONTANE RECLAIMED ' NF AUG 0. 40 0. 40 0. 48 1. 28 OCT 0. 62 0. 81 0. 57 1. 99 MAY 0. 29 1. 10 0.50 1. 39 JUN 0. 50 0. 53 0. 76 1. 80 AUG 0. 20 0.46 1.49 2. 15 OCT 0. 24 0. 63 0. 84 1. 71 90% CONFIDENCE SOIL LIMITS X SX LOWER UPPER 5. 27 0, 49 3. 84 6.70 6.54 0. 62 4.7 3 8. 35 9.45 2. 82 1. 22 17.68 14. 79 4. 09 2. 85 26.73 1. 73 1. 49 7.38 16.08 5. 64 0.46 4. 30 6.98 5.76 1. 03 2.75 8.77 7. 89 0. 94 5. 15 1 0.63 5. 41 1. 03 2. 40 8.42 9.61 4. 37 -3.15 22.37 5. 49 0. 92 2.80 8.18 5. 45 1.55 0.92 9.98 1. 59 0. 16 1.12 2.06 2. 98 0. 63 1.14 4.82 2.27 0.30 1. 39 3.15 3. 60 0.79 1.29 k 5. 91 6.07 0. 45 4. 76 7.38 3.36 0. 48 . 1.96 4.76 1.72 0. 57 0.06 3.38 3. 01 0. 80 0.67 5.35 3. 85 1. 44 -0.35 8.05 1. 76 0. 50 0.30 3. 22 1, 99 0. 10 1.70 2. 28 2. 36 0.79 0.05 4.67 132 PHOSPHORUS (G M**-2) SUBALPINE NATIVE F 90? CONFIDENCE DET- SOIL LIMITS SHOOT+RITUS+ROOT= TOTAL X SX LOWER UPPER AUG 0.41 0.72 1.52 2. 65 4. 94 1. 96 -0.78 10.66 OCT 0. 15 0.93 0.60 1.69 3.75 0. 48 2.35 5.15 MAY 0. 20 0.99 4.73 5.92 4. 92 1. 36 0.95 8. 89 JUN 0. 63 1. 00 5.00 6. 63 12. 95 2. 02 7.05 18.85 AUG 0. 56 0. 72 5. 80 7. 08 10. 17 1. 98 4. 39 1 5.95 OCT 0.41 0. 42 1.87 2.70 8.31 2. 28 1.65 1 4.97 SUBALPINE NATIVE NF AUG 0. 37 0. 95 1. 54 2. 86 OCT 0. 23 1.03 1. 56 2. 82 MAY 0. 24 0.41 1. 99 2. 64 JUN 0.50 0. 43 4. 51 5. 44 AUG 0.29 0.72 3. 15 4. 16 OCT 0. 07 0. 37 1. 6 6 2. 10 3. 50 0. 63 1.66 5. 34 3. 76 1. 18 0.31 7. 21 4. 25 1. 35 0.31 8. 19 3. 58 0.50 2. 12 5. 04 4. 97 2. 15 -1.31 1 1. 25 1. 93 0. 91 -0.73 4. 59 SUBALPINE RECLAIMED F AUG ; 0. 64 0. 06 0. 1 1 0. 81 OCT 0. 24 0. 12 0. 10 0. 45 MAY 0. 18 0. 23 0. 26 0. 68 JUN 0. 78 0. 45 0.23 1. 47 AUG 0. 93 0.47 0.99 2. 39 OCT 0. 90 0. 20 0. 96 2. 06 1. 90 0. 53 0.35 3.45 1. 08 0. 19 0.53 1.6 3 1. 11 0. 56 -0.53 2.75 2. 26 0. 41 1.06 3.46 2. 54 0. 59 0. 8 2 4.26 1. 03 0. 15 0.59 1.47 SUBALPINE RECLAIMED NF AUG 0. 56 0. 08 0. 49 1. 13 OCT 0. 23 0. 19 0. 27 0. 69 MAY 0. 12 0.21 0. 17 0. 50 JUN 0.38 0. 32 0. 40 1 . 10 AUG 0. 21 0. 27 0. 43 0. 95 OCT 0. 13 0.26 0. 27 0. 66 1. 59 0. 11 1. 27 1.91 1.29 0.31 0.38 2.20 0. 64 0. 09 0. 3 8 0.90 1. 05 0. 26 0.29 1.81 1. 06 0. 08 0.83 1.29 0. 60 0. 03 0.51 0.69 133 POTASSIUM (G M**-2) MONTANE NATIVE F DET-SHOOT+RITUS+ROOT=TOTAL AUG 5. 37 1 .05 2. 0 1 8. 43 OCT 1. 05 1. 21 1. 69 3. 95 MAY 1. 52 1.03 1. 39 3. 95 JUN 8.01 0. 80 3. 86 12. 67 AUG 4. 11 0.98 3. 23 8. 32 OCT 1. 44 0.57 1. 71 3. 72 MONTANE NATIVE NF AUG 5. 64 1. 60 2. 42 9. 66 OCT 0. 65 2.49 1 . 36 5. 0 1 MAY 1. 23 1. 47 1. 46 4. 16 JUN 3. 89 0. 90 5. 44 10. 23 AUG 2. 36 1.53 4. 86 9. 25 OCT 1.09 1.77 3. 12 5. 97 MONTANE RECLAIMED i F l AUG 2. 53 0.64 1. 08 4. 24 OCT 3. 14 0. 67 0. 2 3 4. 05 MAY 1.79 0. 36 0. 84 2. 99 JUN 4. 16 0.71 2. 09 6. 96 AUG 1. 44 0. 55 1. 09 3. 08 OCT 3. 27 0.45 0. 65 4. 37 MONTANE RECLAIMED i NF AUG 2. 42 0.49 0. 69 3. 61 OCT 2. 90 1 . 26 0. 34 4. 50 MAY 1. 76 0.58 0. 52 2, 37 JUN 3. 76 0. 44 2. 12 6. 33 AUG 1.08 0. 54 1. 38 3. 01 OCT 1.6 3 0.48 0. 94 3. 05 90f. CONFIDENCE SOIL LIMITS X SX LOWER UPP ER 39. 48 4. 98 24.94 54. 02 41.34 1. 90 35.79 46. 89 52.05 8. 59 26. 97 77. 13 67. 48 1 3. 59 27.80 107. 16 66. 88 4. 77 5 2.95 80. 81 50. 08 3. 32 25.79 74. 37 39. 56 1. 93 33.92 45. 20 43. 18 4. 53 29.95 56. 41 34. 41 5. 27 19.02 49. 80 36. 18 1 2. 71 -0.93 73. 29 46. 05 7. 99 22.72 69. 38 52. 53 1 1. 40 19.24 85. 82 7.36 1. 35 3.42 11. 30 5. 41 0. 64 3.54 7. 28 10. 35 1. 60 5.68 15. 02 9. 84 2. 49 2.57 17. 1 1 18. 75 1. 68 13.84 23. 66 7. 84 1. 15 4. 48 1 1. 20 7. 19 1.91 1.61 12.77 8. 06 1. 68 3. 15 12. 97 9. 17 1. 47 4. 88 1 3. 46 6.32 1. 32 2.47 10. 17 9. 97 1. 61 5.27 14. 67 5.60 0. 82 3.21 7. 99 134 POTASSIUM (G M**-2) SUBALPINE NATIVE F DET-SHOOT+RITUS+ROOT=TOTAL AUG 1.88 0.91 1. 25 4. 04 OCT 0.49 1.21 0. 87 2. 56 MAY 1. 05 0. 99 3.31 5. 35 JUN 2. 72 1. 85 4. 14 8. 71 AUG 2. 53 0. 87 3. 53 6. 94 OCT 1. 43 0. 73 1. 23 3. 39 SUBALPINE NATIVE NF AUG 2. 08 1. 10 T. 67 4. 85 OCT 0. 74 1 . 12 0.92 2. 78 MAY 1.26 0. 98 2. 29 4. 52 JUN 3. 23 0. 47 5. 17 8. 87 AUG 1. 64 0. 89 3. 10 5. 63 OCT 0. 25 0.60 1.55 2. 39 SUBALPINE RECLAIMED F AUG 4. 80 0.09 0. 19 5. 08 OCT 2. 99 1 . 64 0. 30 4. 92 MAY 0. 86 0. 25 0. 39 1. 50 JUN 6. 12 0. 33 1.21 8. 17 AUG 11.48 0. 90 0.72 13. 11 OCT 7. 82 0. 75 0.91 9. 48 SUBALPINE RECLAIMED NF AUG 3. 19 0. 07 0. 15 3. 41 OCT 2. 22 1.18 0. 20 3. 61 MAY 0. 80 0. 47 0.24 1. 51 JUN 3.43 0. 72 0.73 4. 88 AUG 2. 08 0. 39 0.87 3. 34 OCT 1. 16 0.60 0. 56 2. 33 90% CONFIDENCE SOIL LIMITS X SX LOSER UPPER 37.69 6. 20 19.59 55.79 24. 83 4.71 1 1.08 38. 58 36. 51 2.38 2 9.56 43.46 43.78 15. 21 -0.63 88. 19 49. 00 4. 81 34. 95 6 3.05 32. 75 8.24 8.6 9 56.81 29. 50 5. 46 1 3. 56 45.44 25.61 6.33 7. 13 44.09 33. 43 8. 05 9.92 56. 94 45. 15 7. 5 3 23. 16 67.14 49. 46 4.36 36.73 62.19 22. 88 1. 18 19.43 26.33 5.64 0. 70 3.60 7.68 4. 12 0. 40 2. 95 5.29 12. 35 2.20 5. 93 18.77 7.50 0. 66 5.57 9.43 6.78 0. 51 5.29 8.27 4.68 0.81 2. 31 7.05 4. 96 0. 77 2.71 7.21 4. 24 0. 56 2. 60 5.88 4. 84 0. 42 3. 61 6.07 5. 13 0. 84 2. 68 7.58 5. 38 0. 32 4.45 6.31 3.79 0. 36 2.74 4.84 135 CALCIUM {G M**-2) MONTANE NATIVE F DET-SHOOT+RITUS+ROOT=TOTAL AUG 6. 66 6.2 3 18.84 31. 74 OCT 0. 63 3.72 11. 00 15. 35 MAY 0. 23 5.4 3 8. 27 13. 93 JUN 1. 32 6. 42 33.46 41 . 20 AUG 1. 50 6. 43 22. 1 4 30. 06 OCT 0. 56 4. 05 1 3. 85 18. 47 MONTANE NATIVE NF AUG 3. 26 6. 22 17. 13 26. 62 OCT 0. 39 4.69 13.77 18. 85 MAY 0. 22 12. 63 11.06 23. 91 JUN 0. 72 5. 62 35.65 42. 00 AUG 1. 54 4. 54 36. 68 42. 76 OCT 0. 18 6. 79 12. 19 19. 15 MONTANE RECLAIMED F AUG 2. 80 3. 91 1.88 8. 59 OCT 1. 82 1.68 0. 49 3. 98 MAY 1. 10 3. 53 1. 33 5. 97 JUN 2. 85 3. 28 3. 26 9. 39 AUG 1. 97 4.22 1.92 8. 10 OCT 0.86 1.75 1.27 3. 88 MONTANE RECLAIMED NF AUG 2. 74 3. 19 0.88 6. 80 OCT 1.16 2. 88 0. 49 4. 53 MAY 0. 59 6. 48 0. 96 8. 03 JUN 2. 91 3. 30 3. 31 9. 52 AUG 1. 44 1. 20 6. 85 9. 49 OCT 0.65 3. 20 1.78 5. 63 90% CONFIDENCE SOIL LIMITS X SX LOWER UPPER 702.49 96. 32 42 1. 24 983. 74 658.63 60. 22 482. 79 834.47 774. 46 37. 80 664.08 884. 84 77 3. 46 64. 39 58 5. 4 4 96 1. 48 714.63 11 2. 12 387.24 1042. 02 777.71 76. 87 55 3. 25 100 2. 17 586.82 34. 00 487. 54 686. 10 960.97 3 0, 79 87 1.06 1050. 88 673.33 58. 46 502.63 844. 03 628.31 8. 46 603.61 653. 01 6 57.25 47. 18 51 9.48 795. 02 700. 90 34. 37 600. 54 80 1. 26 201.06 2. 01 195. 19 206. 93 245.93 42. 52 121.82 37C. 14 209.27 20. 89 148.27 270. 27 186.91 36. 17 8 1. 29 292. 53 253. 43 2 9. 97 165.92 340. 94 312.38 35.70 208. 14 416. 62 375.32 51. 46 225.06 525. 58 414.79 28. 01 333.00 496. 58 308.31 2 4. 90 235.60 381. 02 3 95.90 33. 96 296.74 495. 06 417.93 17.75 366. 10 469. 76 428.64 36. 16 323.05 534. 23 136 CALCIUM (G M**-2) SUBALPINE NATIVE F 90% CONFIDENCE DET- _ SOIL _ LIMITS SHOOT+RITUS+ROOT= TOTAL X SX LOSER UPPER AUG 1. 46 5. 41 1 5. 70 22. 57 765.04 66. 70 570. 28 95 9.80 OCT 0. 43 4. 30 5.60 10.32 577.85 115. 16 241.58 914.12 MAY 0. 25 9. 14 52. 27 61. 66 761.94 3 8. 12 650. 63 873.25 JUN 0.61 4. 41 51.34 56. 36 684.46 45. 40 55 1. 39 817.03 AUG 1. 74 4. 95 49.77 56. 45 764.84 51. 03 615.83 913.85 OCT 0. 87 2. 43 13. 90 17.21 634. 11 12 4. 35 27 1.0 1 997.21 SUBALPINE NATIVE NF AUG 1. 51 7. 26 14.63 23. 40 734. 77 26. 58 657. 16 812.38 OCT 0. 88 5. 34 6.35 12. 56 641.60 108. 33 325.28 957.92 MAY 0. 41 1. 81 20.75 22. 96 522.43 41.93 399.99 644.87 JUN 0.69 2. 90 51. 35 54. 95 591.91 82. 45 351. 16 832.66 AUG 0. 92 6. 56 3 1. 48 38. 96 726. 25 38. 71 61 3.23 839.29 OCT 0. 28 3. 19 14.98 18. 46 61 1.79 53. 65 455. 13 768.45 SUBALPINE RECLAIMED i F AUG 1. 55 0.42 0. 34 2. 31 1247.63 56. 50 1082.65 1412.61 OCT 0. 59 0. 92 0. 52 2. 03 1016.98 54. 43 858.04 1175.92 MAY 0. 10 1. 42 1. 02 2. 53 1119.57 83. 51 37 5.72 1363.42 JUN 0. 51 1.39 2. 80 4. 69 968. 63 30. 85 878.60 1058.76 AUG 1. 20 1.84 3. 6 1 6. 64 942.29 91. 35 675.55 1 20 9. 0 3 OCT 1. 07 0.69 4. 74 6. 50 715.54 279. 39 - 100.28 1531.36 SUBALPINE RECLAIMED NF AUG 0. 93 0. 31 0. 32 1. 56 1046.60 177.22 529.12 1564. 08 OCT 0. 52 0. 69 0. 39 1. 60 855. 14 149. 95 417.29 1292.99 MAY 0.09 0. 91 0. 63 1. 63 846.73 1 1 8.94 499.43 1194.03 JUN 0. 47 1 . 62 1. 13 3. 22 731.24 239. 27 3 2.57 1429.91 AUG 0. 30 1. 53 2. 02 4. 36 725.38 5 1. 55 57 4. 85 87 5.91 OCT 0.37 1 . 26 3. 27 4. 90 714.04 33.09 617.42 810.66 137 MAGNESIUM (G M**-2) MONTANE NATIVE F DET-SHOOT+RITUS+ROOT=TOTAL AUG 0.54 0.68 2. 32 3. 53 OCT 0. 11 0.45 1.69 2. 25 MAY 0. 1 1 0.71 1. 26 2. 08 JUN 0. 47 0. 56 4. 25 5. 27 AUG 0. 37 0.78 3.09 4. 23 OCT 0. 20 0. 39 1.51 2. 10 MONTANE NATIVE NF AUG 0.64 0.71 2. 42 3. 78 OCT 0. 08 . 0.55 1. 98 2. 61 MAY 0. 09 0.99 1.37 2. 45 JUN 0. 25 0.63 4. 20 5. 08 AUG 0. 33 0. 66 3. 86 4. 84 OCT 0. 06 0. 74 1.67 2. 47 MONTANE RECLAIMED i F AUG 0. 69 0.61 0.59 1. 89 OCT 0.51 0.39 0.05 0. 94 MAY 0. 32 0.33 0.50 1. 14 JUN 0. 55 0. 37 0.73 1. 65 AUG 0. 28 0.49 0.54 1. 32 OCT 0. 28 0. 21 0.31 0. 80 MONTANE RECLAIMED NF AUG 0. 86 0. 56 0. 37 1. 78 OCT 0. 46 0. 65 0. 14 1. 26 MAY 0. 27 0.73 0. 34 1. 34 JUN 0. 65 0.39 0. 74 1. 78 AUG 0. 29 0.31 1. 10 1. 70 OCT 0. 20 0.51 0.48 1. 20 90^ CONFIDENCE SOIL LIMITS X SX LOWER UPPER 6 3.33 15.51 2 3.04 113. 62 57. 38 1. 31 53.55 6 1. 21 65. 40 5. 15 50.36 80. 44 74. 59 7. 21 53. 54 95. 64 56.26 8. 66 30.97 3 1. 55 75. 10 1 1. 64 41.11 10 9. 09 52. 49 6.72 32.87 72. 1 1 94. 12 9. 50 66.38 121. 86 77. 23 16. 73 2 3.38 126. 0 8 59.09 5. 33 43.53 74. 65 71.28 12. 02 36.18 106. 38 64.51 6. 84 44.54 84. 48 24. 18 1. 76 19.04 29. 32 31. 16 6. 85 11.16 5 1. 16 25. 57 3. 36 15.76 35. 38 23. 59 4.33 10.95 36. 23 29.17 6. 03 1 1. 56 46. 78 42. 19 8. 67 16.87 67. 51 55. 96 13. 05 1 7. 85 94. 07 58. 82 6. 48 39.90 77. 74 42.76 5.67 26.20 59.32 67. 04 8.25 42.95 91. 13 67. 20 4. 12 55. 17 79. 23 66. 42 6. 41 47.70 85. 14 138 MAGNESIUM (G M**-2) SUBALPINE NATIVE F AUG OCT MAY JUN AUG OCT DET-SHOOT+BITUS+ROOT=TOTAL 0. 30 0.72 1. 99 3. 01 0. 09 0. 09 0. 24 0. 41 0. 20 0. 58 0. 97 0. 55 0. 58 0.33 0. 82 6.5 9 5.72 5.6 0 1.60 1. 49 7. 65 6.51 6.59 2. 12 _ SOIL X 82. 65 63. 86 92. 79 85. 13 89. 40 78.55 SX 3. 24 1 0. 60 0. 65 9. 06 1 1. 46 14.81 90% CONFIDENCE LIMITS LOWEB UPPEH 73. 19 32.91 90.89 58. 67 5 5.94 35.30 92. 1 1 94.81 94.69 11 1.59 122. 86 12 1.80 SUBALPINE NATIVE NF AUG 0. 32 0. 97 2. 18 OCT 0. 12 0. 70 0. 85 MAY 0. 11 0. 45 2. 64 JUN 0. 22 0. 37 5.72 AUG 0. 24 0. 72 3. 98 OCT 0.05 0. 40 1. 52 3. 48 1. 68 3. 19 6.31 4. 95 1. 97 76.33 67.51 57.93 70. 94 81. 70 58. 93 3. 52 7.50 6. 37 12. 52 8. 84 8. 04 66.05 45.61 39.33 3 4. 3 8 55.89 3 5.45 86.6 1 89.41 7 6.53 107.50 107.51 82.41 1 SUBALPINE RECLAIMED F AUG 0.43 0.09 0.11 OCT MAY JUN AUG OCT 0. 24 0. 06 0. 36 0. 86 0.59 0.31 0.18 0.41 0.45 0.21 0. 10 0. 26 0.65 0. 90 1. 05 0.63 0. 66 0. 49 1.41 2.22 1. 85 33.62 27.20 27. 96 35. 87 32.71 26.78 2. 39 3.59 1. 84 2. 55 2. 22 0. 15 26.64 16.72 22.59 28.42 26.23 26.34 40.60 37.68 33.33 43.32 3 9.19 27.22 SUBALPINE RECLAIMED NF AUG 0. 27 0 .07 0. 10 OCT 0.19 0.22 0.06 MAY 0.05 0.22 0.13 JUN 0.21 0.34 0.21 AUG 0. 24 0. 33 0.40 OCT 0.15 0.31 0.62 0. 45 0.48 0. 46 0. 77 0. 97 1.08 37.25 30. 85 28. 10 30. 02 29. 78 23.69 5. 58 4. 15 2. 82 6. 04 3. 06 1. 36 20.96 18.73 1 9.87 12.38 20. 84 19.72 53.54 42.97 36.33 47.66 38.72 27.66 139 Appendix I I . Net change i n Ca and Mg mass (g m ) between sampling dates i n the shoot, d e t r i t u s , root and s o i l compartments, the s o i l data represent exchangeable l e v e l s . 140 CALCIUM MONTANE N A T I V E P SHOOT DETRITUS AUG-OCT - 6 . 0 3 - 2 . 51 OCT-MAY - o . ao 1. 71 MAY-JUN 1.09 0. 99 JUN-AUG 0.18 0. 01 AUG-OCT - o . 9 a - 2 . 38 NET (OCT--OCT) - 0 . 07 0. 33 MONTANE NATIVE NF AUG-OCT - 2 . 87 - 1 . 53 OCT-MAY - 0 . 17 7. 94 MAY-JUN 0.50 - 7 . 0 1 JUN-AUG 0.82 - 1 . 08 AUG-OCT - 1 . 3 6 2. 25 NET (OCT-•OCT) - 0 . 2 1 2. 10 MONTANE RECLAIMED F AUG-OCT - 0 . 9 8 - 2 . 23 OCT-MAY - 0 . 7 2 1. 85 MAY-JUN 1.75 - 0 . 25 JUN-AUG - 0 . 8 8 0. 94 AUG-OCT - 1 . 1 1 - 2 . 47 N E T ( O C T - •OCT) - 0 . 9 6 0. 07 MONTANE RECLAIMED NF AUG-OCT - 1 . 5 8 - 0 . 31 OCT-MAY - 0 . 5 7 3. 60 MAY-JUN 2. 32 - 3 . 18 JUN-AUG - 1 . 4 7 - 2 . 10 AUG-OCT - 0 . 7 9 2. 00 N E T ( O C T - OCT) - 0 . 5 1 0. 32 M * * - 2 ) ROOT - 7 . 8 a - 2 . 7 3 25 .19 -11 .32 - 8 . 2 9 TOTAL - 1 6 . 3 9 - 1 . 4 2 2 7 . 2 7 - 1 1 . 1 4 - 1 1 . 5 9 S O I L - 4 3 . 8 6 115.83 -1 .CO - 5 8 . 8 3 63 ,C8 2 .85 3. 12 1 19.08 - 3 . 3 6 - 2 . 7 1 24 .59 1.03 •24.49 - 7 . 7 7 5.06 18.09 0.76 - 2 3 . 6 1 374 .15 - 2 8 7 . 6 4 - 4 5 . 0 2 28 .94 43 .65 - 1 . 5 8 0 .30 - 2 6 0 . 0 7 - 1 . 3 9 0.84 1.93 -1 .34 - 0 . 6 5 - 4 . 6 1 1.99 3.42 - 1 . 2 9 - 4 . 2 2 4 4 . 9 2 - 3 6 . 7 1 - 2 2 . 3 6 66 .52 56 .95 0 .78 - 0 . 10 66. 40 - 0 . 3 9 0 .47 2.35 3.54 - 5 . 0 7 - 2 . 2 7 3.50 1 .49 - 0 . 0 3 - 3 . 8 6 39 .47 - 1 0 6 . 4 8 87 .59 22.03 10.71 1 .29 1. 10 13 . 85 141 CALCIUM (G M**-2) SUBALPINE NATIVE F SHOOT DETRITUS RCOT TOTAL S GIL AUG-OCT -1.03 -1.11 -10.10 - 12.25 -187.19 OCT-MAY -0. 18 4. 84 46.67 51.34 184.09 MAY-JUN 0.36 -4.73 -0.93 -5.30 -77.48 JUN-AUG 1.13 0. 54 -1 .57 0.09 80.38 AUG-OCT -0. 87 -2.52 -35.87 -39.24 -13C.73 NET(OCT-•OCT) 0. 44 -1.87 8.30 6.89 56. 26 SUE ALPINE NATIVE NF AUG-OCT -0.63 -1. 92 -8.28 -10.84 -93.17 OCT-MAY -0.47 -3.53 14 .40 10. 40 -119. 17 MAY-JUN 0.28 1.09 30.60 31.99 69.48 JUN-AUG 0.23 3. 66 -19.87 -15.99 134.35 AUG-OCT -0.64 -3. 37 -16.50 -20.50 -114.47 NET(OCT- OCT) -0.60 -2. 15 8.63 5.90 -29.81 SUBALPINE RECLAIMED F AUG-OCT -0.96 0.50 0.18 -0.28 -230.65 OCT-MAY -0.49 0.50 0.50 0.50 102.59 MAY-JUN 0.4 1 -0.03 1.78 2.16 -150.89 JUN-AUG 0.69 0.45 0.81 1.95 -26.39 AUG-OCT -0. 13 -1. 15 1.13 -0.1 4 -226 .75 NET(OCT- OCT) 0.48 -0.23 4.22 4.47 -301.44 SUEALPINE RECLAIMED NF AUG-OCT -0.41 0.38 0.07 0.04 -191.46 OCT-MAY -0.43 0. 22 0.24 0.03 -8.41 MAY-JUN 0. 38 0.71 0.50 1.59 -115.49 JUN-AUG 0.33 -0. 09 0.89 1. 14 -5. 86 AUG-OCT -0.43 -0.27 1.25 0.54 -11 .34 NET(OCT- OCT) -0. 15 0.57 2.88 3.30 -141. 10 142 MONTANE NATIVE F SHOOT AUG-OCT -0.43 OCT-MAY 0.0 MAY-JUN 0.36 JUN-AUG -0.10 AUG-OCT -0.17 NET (OCT-OCT) 0.0 9 MAGNESIUM (G M**-2) DETRITUS ROOT -0.23 -0.63 0.26 -0.43 -0.15 2.99 0.22 -1.16 -0.39 -1.58 -0.06 -0.18 TOTAL SOIL -1.28 -10.95 -0.17 8.02 3.19 9.19 -1.04 -18.33 -2.13 18.84 -0.15 17.72 MONTANE NATIVE NF AUG-OCT -0.56 OCT-MAY 0.01 MAY-JUN 0.16 JUN-AUG 0.08 AUG-OCT -0.27 NET (OCT-OCT) -0.0 2 -0.16 -0.44 0.44 -0.61 -0.36 2.83 0.03 -0.34 0.08 -2.19 0.19 -0.31 -1.17 41.63 -0.16 -16.89 2.63 -18.14 -0.24 12.19 -2.37 -6.77 -0.14 -29.61 MONTANE RECLAIMED F AUG-OCT -0.18 -0.22 GCT-MAY -0. 19 -0.06 MAY-JUN 0.23 0.04 JUN-AUG -0.27 0. 12 AUG-OCT 0.0 -0.28 NET(OCT-•OCT) -0.23 -0. 18 MONTANE RECLAIMED NF AUG-OCT -0.40 0.09 OCT-MAY -0. 19 0.08 MAY-JUN 0.38 -0.34 JUN-AUG -0.36 -0.08 AUG-OCT -0.0 9 0.20 SET(OCT-OCT) -0.26 -0.14 -0.54 -0.95 6.98 0.45 0.20 -5.59 0.23 0.5 1 -1.98 -0.19 -0.33 5,58 -0.23 -0.52 13.02 0.26 -0.14 11 .03 -0.23 -0.52 2. 86 0.20 0.08 -16 . G6 0.40 0.44 24.28 0.36 -0.08 0. 16 -0.62 -0.50 -0.78 0.34 -0.06 7.60 143 MAGNESIUM (G M**-2) SUBALPINE NATIVE F SHOOT DETRITUS ROOT TOTAL SOIL AUG-OCT -0.21 -0.14 -1.17 -1.52 -18.79 OCT-MAY 0.0 0.39 5.77 6.16 28.93 MAY-JUN 0.15 -0.42 -0.87 -1.14 -7.66 JUN-AUG 0.17 0.03 -0.12 0.08 4.27 AUG-OCT -0.21 -0.25 -4.00 -4.47 NET(OCT-OCT) 0.11 SUBALPINE NATIVE NF AUG-OCT -0.20 OCT-MAY -0.01 MAY-JUN 0.11 JUN-AUG 0.02 AOG-OCT -0.19 NET(OCT-OCT) -0.07 AUG-OCT -0.19 OCT-MAY -0.18 MAY-JUN 0.30 JUN-AUG 0.50 AUG-OCT -0.27 NET(OCT-OCT) 0. 35 10.85 -0.25 0.78 0.63 14.69 -0.27 -0.25 -0.0 8 0. 35 -0.32 -1.33 1 .79 3.08 -1 .74 -2.46 -1.80 1.51 3.12 -1.36 -2.98 -8.82 -9.58 13,01 10.76 -22.77 -0. 30 0.67 0.29 -8.58 F 0.22 -0. 13 0.23 0.04 -0.24 -0.01 0.16 0.39 0.25 0.15 0.03 -0. 17 0.92 0.81 -0.37 -6.42 0.76 7.91 -3. 16 -5. S3 -0. 10 0.95 1.19 -0. 42 AUG-OCT OCT-MAY MAY-JUN JUN-AUG AUG-OCT -0.08 -0. 14 0. 16 0.03 -0.09 0.15 0.0 0. 12 -0.0 1 -0.02 -0.04 0.12 0.03 0.19 0.22 0.03 -0.02 0.31 0.20 0.1 1 -6.40 -2.75 1.92 -0.24 -6 .09 NET(OCT-OCT) -0. 04 0. 09 0.56 0.60 -7. 16 144 Appendix III. Prec ip i tat ion data (cm rLO) over the study period measured at the val ley bottom (Natal) and the ridge top (Harmer). These data represent the range of prec ip i tat ion regiernes found within the study area. The hatchures represent prec ip i tat ion f a l l i n g as rain and the white as that f ract ion of total prec ip i tat ion which f e l l as snow. 145 146 J F M A M J J A S O N D J F M A M J J A S O N 1976 ' 1977 147 Appendix IV. Prec ip i tat ion which f e l l as rain or snow during the study period as well as average maximum and minimum a i r temperatures. The Natal and Harmer stations were at 1030 and 2100 m ASL respectively. 148 Month R a i n (cm Eo0) Snow (cm HoO) T o t a l . rT.emp( X Hax.. sratur.e X i-i i n N a t a l 1976-J 0 . 2 0 6 . 1 5 6 . 3 5 - 0 . 6 -1Q..0 F 0 . 0 3 6 . 4 3 6.4-6 0. - 7 . 3 M 2.46 1 .65 4-. 06 1 .7 - 8 . 9 i\ ±s. 1 . 30 0 . 2 0 1 . 50 1 1 . 7 - 1 . 1 M 6 ..86 0 6 . 8 6 1 7 . 2 1.7 J 3 . 0 5 0 3 - 0 5 1 7 . 8 3 - 3 J 3 . 5 6 0. 3 • 56 2 3 . 3 7 - 2 A. 16 . 5 1 0 16 . 5 1 2 1 . 7 7 . 8 o 1 . 2 5 0 1 . 25 2 1 . 1 3 . 3 0 3 - 3 0 0 . 2 0 3 - 5 0 1 1 . 7 - 1 . L N 2 . 2 1 1 . 57 3.81 3 . 9 - 6 . 7 D 1 .37 0.81 2 ..18 2 . 2 - 7-2 T o t a l . 4-2.16 1 7 . 0 2 59.18 N a t a l . 1 977 J 1 . 09 1.4-0 2.4-9 - 4 . X 7 - 1 2 . 5 0 j? Q.ia 0.-30 0...48 3 - 7 8 - 6 . 3 3 H 0 . 5 3 2 . 7 7 3 . 3 0 4 . 2 1 - 5 . 9 5 A 1 .63 0 1 . 63 14 . 5 0 - 2 . 7 6 M 3.01 0 3.01 ,14.28 3.33. J 4 . 6 5 0. 4 . 6 5 23-78 5 . 1 7 J 2 . 6 9 0 2 . 6 9 2 3 - 3 7 ' 6 . 3 6 xi. 1 1 . 3 0 0. 1 1 - 3 0 2 3 . 3 5 5 . 6 7 S> 5.4-1 0 5.41 1 5 - 3 9 2.48 0. 3 . 7 3 0.06 3.81. 11.-94 - 2.74 N 2.36 2.18 4 . 5 5 0.1-7 - 9 . 6 7 149 Month. R a i n (cm EUO) Snov; (cm IlpO) T o t a l . _Temp X' Max er a t u r e . X Min Harmer. 1976 J 0. 1 1 . 0 5 11 .05 - 3 - 5 - 1 2 . 0 F o.. 16 .51 16 .51 - 5 . 0 -12...0 M 0 7.62 7.62 - 4 . 5 - 1 2 . 0 i i . - 0 1.17 1 .17 5 .0 -4..0 M 0^0.8 3 . 1 0 3 -18 9.5 - 0 . 5 J 2.21 0 . 7 4 2.95 1 0 . 5 1.5 J 4.-57 0 4-, 57 • 18.0 7.0 A i i 3 1 . 5 0 . o. 3 1 . 5 0 16.0 5 -5 1 .25 0 . 3 6 • 1..61 1.5.0 5.0 0 a . 51 2.82 3 - 3 3 . 0 . 5 - 1 . 5 N 0 . 71 ' 3 - 0 5 3 . 76 0 - 7 . 0 D 0 5.92 5 .92 - 4 . 5 . - 1 0 . 0 Total.. 4 0 .33 5 2 . 3 ^ 9.3.17. Earmer 1 977 J 0, 3.66 3.65 - 8 . 1 7 -14 .91 E 0 3 . .81 3.-81. - 1 . 3 7 - 8 . 9 1 M 0, 9.52, 9.52 - 1 . 6 8 -11. .09 A 1.-.0.7 1 . 40 2 . 4 7 6 . 5 7 - 4 . 4 7 M 1.42 5 .00. 6.42 7 . ^ 9 - 2 . 0 4 J 2 . 0 8 0.38 2 . 4 6 I 6 . 1 5 4.24 J 3 .25 0 . 51 3.76 16.92 4 . 2 7 A_ 8.26 0.18 - 8.-44 17 - 2 4 4 .64 S 10.16 1 . 35 II..5I. 9.56 0.24 0 a. 13 2 . 7 9 2 . 9 2 . 5 . 1 8 - 4 . 2 3 T-.T 11 0 8.89 8.89 - 4 . 8 3 - 1 1 . 7 8 D 150 Appendix V. Mean monthly temperatures at Natal (1030 M ASL) and Harmer (2100 m ASL) from 1973.to 1977. 70 • MEAN MONTHLY TEMPERATURE - NATAL 1 1 1 R ! I ; I T T I . T 1 ; ! : : ! I I I I !. ! ] i i ST 1 ! I I I t I i ] i ! | i i i i : i I I M 'I "I I . i I I I I | l ! 60' I i 'l i I i l M i" I i i i M i i i r i ' I ' l ' I T i ' I ! I ! i I ! '! I T i |T i i • i . ' ' ' r r r n i rr r I "r i T T ! r i T T i r r I 5 0 ' J | : i ; r | : , :..L '.T ! i r r n t i r t i 1 1 1 i r r i i ! I r rTIT'T l i r I r r i r i i i i i • 'I I I I T ! i i n H i"! I : ri "i I T T IT I T T T ' i ! I"IT r t t h . n i ri r r r ' i I T T T T 40' • "" ' V i n i i : i i i i i i i i rri r IT i i r n rr""' i i n i rr i r IT n rr r n i ITT r; i i I i r n , i' IT I I I' rrr i r n IT : rt i i ri r r n 1 T T I i i ! I V f IT I ! i i ! ri IT"]'" 3 0 ! M ! I I r r i ! r n Month 153 Appendix VI. Monthly snowfall at Natal (1030 m ASL) and Harmer (2100 m ASL) from 1973 to 1977. wa.tci ( x 10= 4now) •<0WrH/./ SNOWFALL - hi AT A L Month M .1 ^rrrrJJ^n LU.TJ i "u "j .1 i.i , , ! Q U 0 > MONTHLV SNOWFALL - WARMER V LU. ! . i I i T r n I I.I I . I . I ! i s ••! i I i i i s i I i i..i M M . " r r ' < 1 M I I I i Ii , I || | | || | ( |i S O N M i l l . I I . I I I I ! i I i I I i I I M I i i I I I I"I i I . I 156 Appendix VII. Net change in oven dry organic matter (g rn"2 day" 1) between sampling dates for the shoot, detr itus and root compartments. shoot detr i tus root •total Montane native F Aug/Oct -4.33 -5.12 -8.25 -17.70 Oct/May -0.07 1.74 -0.96 0.71 May/June 5.51 -7.63 68.02 65.90 June/Aug 0.13 3.36 -18.61 -15.12 Aug/Oct -2.49 -5.45 -13.93 -21.88 Montane native NF Aug/Oct -5.66 -6.61 -8.30 -20.57 Oct/May 0.01 2.74 -1.13 1.63 May/June 3.11 -13.05 57.41 47.46 June/Aug 0.26 2.03 -6.61 -4.32 Aug/Oct -2.25 -2.02 -20.33 -24.60 Montane reclaimed F Aug/Oct -0.49 -3.03 -7.40 -10.92 Oct/May -0.37 0.82 1.93 2.38 May/June 2.69 0.12 3.47 6.27 June/Aug -1.83 -0.10 0.48 -1.46 Aug/Oct 0.74 -2.32 -4.39 -5.96 Montane reclaimed NF Aug/Oct -0.73 -1.28 -5.49 -7.50 Oct/May -0.38 0.69 1.13 1.43 May/June 2.93 -3.65 7.39 6.13 June/Aug -1.46 0.79 2.12 1.45 Aug/Oct -0.26 -1.80 -3.71 -5.77 158 shoot detr i tus root total Subalpine native F Aug/Oct -2.62 0.78 -12.94 -14.79 Oct/May 0.04 1.22 13.16 14.43 May/June 2.84 -9.47 8.33 1.69 June/Aug 0.91 -0.51 -10.23 -9.83 Aug/Oct -1.43 -3.21 -31.73 -36.37 Subalpine native NF Aug/Oct -1.48 -3.04 -11.40 -15.91 Oct/May -0.06 0.08 5.59 5.61 May/June 2.25 -4.85 48.60 46.00 June/Aug -0.56 4.18 -21.66 -18.03 Aug/Oct -1.54 -3.97 -21.45 -26.96 Subalpine reclaimed F Aug/Oct -2.70 2.65 0.40 0.35 Oct/May -0.53 0.05 0.59 0.11 May/June 3.95 3.27 4.12 11.34 June/Aug 5.36 -0.14 4.55 9.77 Aug/Oct -1.02 -2.30 -1.54 -4.86 Subalpine reclaimed NF Aug/Oct -1.20 1.89 0.37 1.06 Oct/May -0.49 0.36 0.38 0.25 May/June 2.74 2.78. 3.34 8.95 June/Aug -0.25 -1.38 2.19 0.56 Aug/Oct -0.32 0.30 -1.88 -1.89 159 Appendix VIII. Nutrient concentrations in the shoot, root and detr itus compartments throughout the study. 160 N i t r o g e n C o n c e n t r a t i o n (%) Shoot D e t r i t u s Root F NF F NF F NF Montane N a t i v e Aug 1 . 25 1.24 1.05 1.22 2.02 1.67 Oct 1.15 1.01 1.32 0.91 1.53 1 .71 May 2.15 2 .29 1.46 1 .58 1. 42 1. 31 June 2 . 27 1. 85 1 .33 1.40 1.46 1.21 Aug 1 .92 1.10 1.50 1.60 1.46 1.54 Oct 1 . 25 2.02 1 .77 1 .88 1 .81 1.60 Montane Reclaimed Aug 1.31 1.94 1.38 1.19 0.95 0.44 Oct 1.10 0.53 1.42 0. 52 0.93 0.84 May 3.29 2 . 92 1.31 1.77 1.02 1.06 Jun 3.08 2.75 1.73 2.44 1.15 1.45 Aug 2.35 2.13 2.19 1.71 1.10 1.06 Oct 2 . 81 2 .25 2.02 1 .81 1.22 1.17 S u b a l p i n e N a t i v e Aug 1.22 1.20 1.47 1.40 1.69 1.66 Oct 1.20 0.'8l 0 .76 0 .89 1.43 1.36 May 2.21 2.00 1.42 0.63 1 .65 1.33 Jun 2. 71 1 .65 1.68 1.10 1.54 1.46 Aug 1.96 1.13 1.23 1. 22 1.73 1 .52 Oct 2.73 1.30 1.69 1.10 2.04 . 1.50 S u b a l p i n e Reclaimed Aug 1.15 1 .18 1 . 25 1. 21 0.63 0. 74 Oct 0.78 0 . 65 0.02 0.46 0.45 0.44 May 1 .65 1 .60 1.17 0.79 0.79 0.58 Jun 3.79 1.46 0.85 0 . 77 0 .86 0.51 Aug 2.08 0.94 1.08 0.73 0.77 0.62 Oct 1. 28 0.76 1.12 0.69 0.76 0 .71 161 Phosphorus C o n c e n t r a t i o n (%) Shoot D e t r i t u s Root' F • NF F NF F NF Montane N a t i v e Aug 0 .20 0 . 21 ' 0 .15 0 .13 0 .12 0 .11 Oct 0 .40 0 . 3 6 0 .34 0 • 32 0 .31 0 .28 May 0. 34 0 . 32 0 .14 0 .15 0 .13 0 .13 Jun 0.40 0 . 32 0 .16 0 .16 0 .11 0 . 21 Aug 0 .26 0 . 22 0 .19 0 .25 0 .15 0 .13 Oct o .22 0 .39 0 .21 0 .26 0 .13 0 .18 Montane Reclaimed Aug 0 .18 0 .19 0 .13 0 .13 0 .15 0 .10 Oct 0 .35 0 . 3 7 0 .25 0 .35 0 .'52 0 .41 May 0 . 3 7 0 . 33 0 .15 0 .29 0 .15 0 .14 Jun 0 . 30 0 .29 0 .31 0 .22 0 . 12 0 .12 Aug Q.23 0 .20 0 .26 0 .16 0 .19 0 .20 Oct 0 . 3 8 0 .29 0 .21 0 .37 0 .19 0 .17 S u b a l p i n e N a t i v e Aug 0 .19 0 .21 0 .15 0 .15 0 .12 0 .12 Oct 0 . 2 7 0 .26 0 .18 0 .22 0 .12 0 .26 May 0. 30 0 . 32 0 .13 0 .08 0 .15 0 .11 Jun 0 . 38 0 . 32 0 .23 0 .14 0 .14 0 .13 Aug 0 . 2 7 0 . 2 3 0 .17 0 .14 0 . 20 0 .13 Oct 0. 34 0.24 0 .20 0 .14 0 . 20 0 .16 S u b a l p i n e Reclaimed Aug 0 .21 0 . 27 0 .17 ' 0 .29 0 .12 0 .57 Oct 0 .16 0 .17 0 .06 0 .13 0 .09 • 0 .25 May 0.42 0. 31 0 .12 0 .10 0 .11 0 .09 Jun 0 .43 0 . 2 8 0. .14 0 .10 0 .06 0 .13 Aug 0 .21 0 . 1 7 0 .16 0 .11 0 .16 0 .12 Oct 0 .23 0 . 1 3 0 .13 0 .10 0 .19 0 .09 162 Potassium C o n c e n t r a t i o n (%) Shoot D e t r i t u s .Root F NF F NF F NF Montane N a t i v e Aug 1. 50 1.40 0.14 0 .18 0.13 0.14 Oct 1.02 0.95 0 . 27 0 . 50 0 . 16 0.15 May 1.73 1.73 0 .13 0.14 0 .16 0.15 Jun 2.85 2.16 0.15 0 .15 0.12 0 . 18 Aug 1.43 1.48 0 .14 0 .22 0 .14 0 .18 Oct 1.10 2.13 0.16 0 . 31 0.12 0 .22 Montane Reclaimed Aug' 1.31 1.16 0 .21 0 . 16 0. 20 0.15 Oct 1 .92 1.75 0 . 54 0.54 0 .23 0 .25 May 2.04 2.02 0.12 0 .16 0 .17 0.14 Jun 2 .29 2. 20 0 .24 0 .18 0.34 0 . 34 Aug 1.57 1.09 0 .19 0 .19 0.17 0 .19 Oct 2.36 1.96 0 .31 0 . 28 0 .18 0 .19 S u b a l p i n e N a t i v e Aug 0. 89 1.16 0 .19 0.17 0.10 0.13 Oct 0.86 0.84 0 .23 0.24 0 . 18 0.15 May 1 .60 1.66 0.13 0.20 • 0 .10 0 .13 Jun 1.65 2.09 0.42 0 .15 0.12 0 .15 Aug 1. 21 1 .29 0.21 0.17 0 .12 0 .13 Oct 1.20 0 .82 0 .34 0.22 0 .13 0 .15 S u b a l p i n e Reclaimed Aug 1.55 1.54 0 . 23 0 . 23 0.21 0 .18 Oct 1.99 1.63 0. 89 0.84 0.26 0 .19 May 2.03 2.15 0.13 0.22 0.17 0.13 Jun 3.39 2.58 0 .27 0 . 23 0 . 32 0.24 Aug 2.59 1. 72 0 .30 0 .16 0 .12 0 .21 Oct 1.97 1.15 0.48 0 . 23 0 . 18 0 .19 

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