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The role of grass-legume communities in revegetation of a subalpine mine site in British Columbia Yamanaka, Koji 1982

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THE ROLE OF GRASS-LEGUME COMMUNITIES IN REVEGETATION OF A SUBALPINE MINE SITE IN BRITISH COLUMBIA by KOJI YAMANAKA B . S c , M i y a z a k i U n i v e r s i t y , 1969 M . S c , U n i v e r s i t y o f B r i t i s h Columbia, 1975 A THESIS SUBMITTED IN PARTIAL FULFILMENT OF THE REQUIREMENTS FOR THE DEGREE OF DOCTOR OF PHILOSOPHY . i n THE FACULTY OF GRADUATE STUDIES (DEPARTMENT OF PLANT SCIENCE) We a c c e p t t h i s t h e s i s as c o n f o r m i n g t o t h e r e q u i r e d s t a n d a r d THE UNIVERSITY OF BRITISH COLUMBIA 1982 (c) K o j i Yamanaka, 1982 In presenting t h i s thesis i n p a r t i a l f u l f i l m e n t of the requirements for an advanced degree at the University of B r i t i s h Columbia, I agree that the Library s h a l l make i t f r e e l y available for reference and study. I further agree that permission for extensive copying of t h i s thesis for scholarly purposes may be granted by the head of my department or by his or her representatives. I t i s understood that copying or publication of t h i s thesis for f i n a n c i a l gain s h a l l not be allowed without my written permission. Department of f/C.si^c ^ x f T ^ g y t ^ The University of B r i t i s h Columbia 1956 Main Mall Vancouver, Canada V6T 1Y3 ABSTRACT This study describes an investigation of the potential for pioneer grass-legume communities to s t a b i l i z e and ameliorate geologically-fresh s o i l leading to the e s t a b l i s h -ment of a s e l f - s u s t a i n i n g , progressive plant succession on a surface-mined subalpine s i t e . The study area i s located 2,000 m above sea l e v e l in the Canadian Rocky Mountains. F i e l d surveys at the s i t e indicated extremely limited invasion of reclaimed areas (3-7 years old) by native species from the adjacent subalpine forest. S o i l s on revegetated s i t e s were generally warmer and d r i e r than s o i l s of the associated forest and have less than half the content of fine s o i l fragments (<2 mm). F i e l d studies revealed chronological trends i n grass-legume communities at four s i t e s revegetated during 1974-1978 including: species composition, legumes (Trifolium repens L., T. hybridum L. and Medicago sativa L.) performing increasingly poorly on the older s i t e s ; biomass changes, a shoot to root r a t i o (S/R) decreasing from 2.3 to 0.2 as the communities aged; and l i t t e r accumulation which continued even on the oldest s i t e . F e r t i l i z e r (13-16-10) operationally applied at 150 -391 kg/ha enhanced the growth of Dactylis glomerata L. and l i t t e r degradation, and a c i d i f i e d the s o i l . Nitrogen f e r t i l i -zation was also associated with two clear inverse relationships i d e n t i f i e d between D. glomerata and Festuca rubra L. biomass, and between s o i l pH and phosphorus l e v e l s . i i i In greenhouse tests grasses were revealed to be more e f f i c i e n t s o i l nitrogen consumers than were legumes and nitrogen f i x a t i o n decreased s i g n i f i c a n t l y (P<0.01) and l i n e a r l y with increasing grass seeding rates. In the presence of grasses, nitrogen f i x a t i o n was p o s i t i v e l y correlated with aboveground legume biomass at a l l nitrogen f e r t i l i z e r levels tested. The r e s u l t s further revealed that operational seeding and f e r t i l i z e r rates at t h i s s i t e may not optimize plant productivity and the a b i l i t y of legumes to f i x nitrogen symbiotically. F i e l d t r i a l s based upon the experimentaly derived combination (17.5 : 30 : 50 kg/ha grass seeding rate : legume seeding rate : nitrogen f e r t i l i z e r rate) would be desirable to evaluate these data on the s i t e . Other pot e n t i a l p r a c t i c a l implications from t h i s study are: (1) The need for improved legume establishment, involving legume seed germination, species and variety selection, and selection of Rhizobium s t r a i n s . (2) Improved control of the operational f e r t i l i z e r a p plication. (3) A l t e r a t i o n of grass and legume species composition of the present seed mix. (4) Selective placement of i n i t i a l material (overburden or spoil) handling. A modification of the acetylene reduction assay, "the open system" technique, was developed for evaluation of legume nitrogen f i x a t i o n of mine s p o i l s . Although the unit developed i s limited to detection of the presence or absence of ethylene, c a l i b r a t i o n with the closed system of ethylene i v l e v e l s obtained by the open system appeared f e a s i b l e . Further refinement of the system f o r q u a n t i t a t i v e use would increase i t s usefulness i n n i t r o g e n f i x a t i o n s t u d i e s of legumes on mine s p o i l s , n i t r o g e n f i x i n g woody p l a n t s i n f o r e s t s , and legumes i n grassland sods. V TABLE OF CONTENTS 1. INTRODUCTION Page 2. LITERATURE REVIEW 2.1 Revegetation at high-altitude 2.1.1 S o i l amendment 2.1.2 Species selection . 2.1.3 Plant establishment 2.2 Legume nitrogen f i x a t i o n . 2.2.1 Biochemistry of nitrogen f i x a t i o n 2.2.2 Physiological factors and nitrogen f i x a t i o n . . . . . 2.2.3 S o i l nitrogen and phosphorus e f f e c t s on nitrogen f i x a t i o n 2.3 S o i l nitrogen transformations . 2.3.1 Mineralization . . . . 2.3.2 Immobilization and d e n i t r i f i c a t i o n 2.3.3 Nitrogen a v a i l a b i l i t y and accumulation STUDY AREA 3.1 Location 3.2 Climate 3.3 Geology 3.4 S o i l and vegetation MATERIALS AND METHODS 4.1 Weather data 4.2 F i e l d survey 4.2.1 Natural subalpine 4.2.2 Reclaimed areas 4.3 Greenhouse pot tests forest 3 5 k 5 11 12 15 16 20 21 2k 25 30 30 30 33 35 37 37 37 37 39 41 v i Page 4.4 F i e l d tests . . . . . . . 45 4.4.1 F e r t i l i z e r e f f - c t s on s o i l and vegetation . . . . . . 45 4.4.2 Native legumes . . . . . 47 4.4.3 Open system acetylene reduction assay . 47 5. RESULTS AND DISCUSSION . . . . - 5 3 5.1 Weather data . . . . . . . 53 5.2 F i e l d survey . . . . . . . 55 5.2.1 Natural subalpine forest . . . 55 5.2.1.1 Vegetation . . . . 55 5.2.1.2 S o i l and understory phytomass. 58 5.2.2 Reclaimed areas . . . . 6 0 5.2.2.1 S o i l factors . . . . 60 5.2.2.2 Plant biomass . . . . 76 5.3 Greenhouse pot tests . . . . . 9 1 5.3.1 Chemical analysis of fresh s p o i l s . 91 5.3.2 Treatment e f f e c t s on acetylene reduction . . . . . . 9 1 5.3.2.1 Grass composition . . . 94 5.3.2.2 Legume composition . . . 1 0 2 5.3.2.3 Nitrogen f e r t i l i z e r . . 1 0 3 5.3.3 Treatment e f f e c t s on biomass and s o i l factors . . . . . . 1 0 6 5.3.3.1 Biomass 1 0 6 5.3.3.2 S o i l nitrogen . . . . 1 0 8 5.3.3.3 S o i l phosphorus . . . 1 0 9 5.3.4 Treatment interactions . . . 5.3.4.1 Two-way interactions . . 1 1 0 5.3.4.2 Three-way interactions . . 5.4 F i e l d t ests . . . . . . . 1 42 5.4.1 S o i l factors . . . . . . 1 4 3 5.4.1.1 Operational f e r t i l i z a t i o n . 143 5.4.1.2 S o i l reaction . . . . 143 5 . 4 . 1 . 3 Phosphorus 5 . 4 . 1 . 4 N i t r o g e n 5 .4 .2 Phytomass compos i t ion 5 . 4 . 2 . 1 Grasses . . . . 5 . 4 . 2 . 2 Legumes . . . . 5 . 4 . 2 . 3 Belowground biomass 5 . 4 . 2 . 4 L i t t e r 5 . 4 . 2 . 5 Phytomass 5 .4 .3 I n t e r r e l a t i o n s h i p s 5 .4 .4 N a t i v e legumes . . . . 5 .4 .5 Open system ace ty lene r e d u c t i o n assay 5 . 4 . 5 . 1 System development . 5 . 4 . 5 . 2 Open system t r i a l at mined s i t e . . . . 6 . GENERAL DISCUSSION 7. SUMMARY 8. LITERATURE CITED . . . . . APPENDIX 1 Breakdown of v a r i a n c e ana lyses f o r ace ty lene r e d u c t i o n , biomass and s o i l f a c t o r s (pot t e s t 1) APPENDIX 2 Breakdown of v a r i a n c e ana lyses f o r a c e t y l e n e r e d u c t i o n , biomass and s o i l f a c t o r s (pot t e s t 2) APPENDIX 3 Y i e l d v a r i a b l e s used t o c a l c u l a t e the d i f f e r e n c e i n grass and legume performance between two legume seeding r a t e s APPENDIX 4 R e l a t i v e c o n t r i b u t i o n of aboveground grass and legume biomass . . . . APPENDIX 5 A c e t y l e n e r e d u c t i o n data u s i n g an open system assay on the r e c l a i m e d a rea s , 1980 V l l l APPENDIX 6 Acetylene reduction data using open and closed assays on the reclaimed areas, 1980 . . . . . APPENDIX 7 Acetylene reduction data using open and closed assays i n the subalpine fo r e s t , 1980 . . . . Page 229 231 LIST OF TABLES Grass and legume species used i n high a l t i t u d e revegetation . . . . . Recommended seed mixes for high a l t i t u d e s i t e s according to aspect . . . . Monthly mean temperature and p r e c i p i t a t i o n of Natal Harmer Ridge weather s t a t i o n , B.C. L i s t of equipment and types of weather data c o l l e c t e d from 1974 area . . . . Operational seed' mix (56 kg/ha) for high a l t i t u d e s used by Kaiser Resources Ltd. L i s t of plant species i n an undisturbed subalpine forest adjacent to the study area pH, phosphorus, ammonium and n i t r a t e of sub-alpine forest s o i l (0-10 cm depth), and phytomass fractio n s . . . . . S o i l moisture (%) and texture between sub-alpine forest and reclaimed s o i l s pH, phosphorus, ammonium and n i t r a t e of the s o i l samples (0-10 cm depth) c o l l e c t e d from the reclaimed areas . . . . . S o i l pH, phosphorus, ammonium and n i t r a t e l e v e l s of s o i l s of d i f f e r e n t reclaimed areas at 0-5 and 5-10 cm depths . Aboveground biomass of grasses, legumes, and l i t t e r on areas reclaimed from 1974 to 1978 Aboveground biomass by species of grasses and legumes on areas reclaimed from 1974 to X 9 7 8 • • • • • • • • Plant density on the areas reclaimed i n 1977 and 1978 . . . . . . . pH, phosphorus, ammonium and n i t r a t e of fresh s p o i l s . . . X Table Page 5.10 Variance analyses for acetylene reduction, biomass and s o i l factors (pot test 1) . . >5 5.11 Variance analyses for acetylene reduction, biomass and s o i l factors (pot tes t 2) 5.12 . Acetylene reduction, aboveground biomass and s o i l factors determined by seeding and nitrogen f e r t i l i z e r rates . . . . . . . 5.13 Changes of y i e l d variables incurred by changing legume seed rate from 15 to 30 kg/ha (pot t f i S t 2 ) • • • • • • m 5.14 Estimate of a e r i a l f e r t i l i z e r d i s t r i b u t i o n on the reclaimed areas . . . . 5.21 Covariance analyses for aboveground Festuca  rubra biomass, t o t a l biomass (g/m^) and s o i l pH . . . . . . . 5.22 Ef f e c t s of f e r t i l i z a t i o n on s u r v i v a l of Lupinus sericeus and Astragalus alpinus on 1974 s i t e . . . . . . 5.23 Laboratory r e s u l t s of aluminum tubes tested for open system acetylene reduction assay . 96 97 121 144 5.15 Variance analyses for pH, phosphorus, ammonium and n i t r a t e of s o i l s before and afte r f e r t i l i z e r . . . . . . . 146 5.16 Percentage r a t i o changes i n aboveground biomass by species within grasses and legumes a f t e r f e r t i l i z e r treatment on reclaimed areas . .154 5.17 Number of culms or stems per m on 1974 s i t e . 158 5.18 Percentage r a t i o changes i n aboveground grass and legume biomass, and l i t t e r a f t e r f e r t i l i z a t i o n . . . . . . .160 5.19 Variance analyses for phytomass fracti o n s before and after f e r t i l i z a t i o n . . . .168 5.20 Variance analysis for aboveground biomass of Dactylis glomerata and Festuca rubra before and afte r f e r t i l i z a t i o n . . . . .170 171 177 180 Preliminary f i e l d (University of B.C. Campus) re s u l t s of aluminum tubes tested for open system acetylene reduction assay Preliminary f i e l d (University of B.C. Campus) test r e s u l t s : sampling tube distance from a test plant for open system acetylene reduction assay . . . . . . Presence and absence of ethylene detected by gas chromatography: open system acetylene reduction assay on reclaimed areas A comparison of aboveground grass and legume biomass obtained by f i e l d survey and green-house pot tests . . . . . . x i i LIST OF FIGURES Figure 2.1 Mic r o b i o l o g i c a l processes of nitrogen transformation . . . . . 3.1 Study area and experimental plo t location 3.2 Study area . . . . 4.1 Weather station on s i t e reclaimed i n 1974 4.2 Closed system acetylene reduction assay 4.3 A preliminary test of aluminum tubes for an open system acetylene reduction assay 4.4 Open system f i e l d acetylene reduction assay 5.1 A i r temperature and p r e c i p i t a t i o n recorded at the 1974 reclaimed area; summer of 1980 5.2 Relative humidity measurements recorded weekly at the reclaimed 1974 area; summer of 1980 . . . . . . . . 5.3 Minimum and maximum s o i l temperatures recorded weekly for the 1974 reclaimed area and the adjacent subalpine fo r e s t ; summer of 1980 . 5.4 Subalpine forest adjacent to study area 5.5 General view of mining p i t and b l a s t i n g 5.6 Rapidly d i s i n t e g r a t i n g shales found on the 1977 s i t e . . . . . . . 5.7 Moisture percentages of s o i l fine fragment (10 cm depth, <2 mm) from reclaimed areas and subalpine fo r e s t ; summer of 1980 . 5.8 Water tension (10 cm depth) of the reclaimed areas and subalpine f o r e s t , summer of 1980. 5.9 Area reclaimed i n 1974 . . . . 5.10 Site views of areas reclaimed i n 1975, 1977 2 5.11 Aboveground t o t a l biomass and l i t t e r (g/m ) of reclaimed areas, 1979 . . . . Page 22 31 32 38 kk 49 51: 54 % 56 57 62 63 65 69 77 78 80 x i i i Figure 2 5.12 Aboveground t o t a l biomass and l i t t e r (g/m ) of reclaimed areas, 1980 5.13 Early season plant growth and Medicago  sativa on 1974 s i t e . . . . . 5.14 Fresh s p o i l s adjacent to the study area 5.15 Grass-legume stands treated with 25 kg/ha nitrogen f e r t i l i z e r , pot te s t 2 . 5.16 Grass-legume stands treated with 50 kg/ha nitrogen f e r t i l i z e r , pot test 2 . 5.17 Grass-legume stands treated with 75 kg/ha nitrogen f e r t i l i z e r , pot te s t 2 . 5.18 Acetylene reduction of legumes treated with various grass seeding and nitrogen f e r t i l i z e r 5.19 Aboveground biomass (g/pot) of legumes treated with various grass seeding and nitrogen f e r t i l i z e r rates . . . 5.20 Aboveground biomass (g/pot) of grasses treated with various nitrogen f e r t i l i z e r rates 5.21 Aboveground grass-legume biomass (g/pot) treated with various nitrogen f e r t i l i z e r rates 5.22 Combined ammonium and n i t r a t e l e v e l s of s p o i l under grass-legume stand treated with various nitrogen f e r t i l i z e r rates . . . . 5.23 Acetylene reduction a c t i v i t y of legumes seeded at 15 kg/ha with various grass seeding and nitrogen f e r t i l i z e r rates (pot te s t 1) 5.24 Acetylene reduction a c t i v i t y of legumes seeded at 30 kg/ha with various grass seeding and nitrogen f e r t i l i z e r rates (pot te s t 1) 5.25 Aboveground biomass of grasses and legumes seeded at 15 kg/ha (pot t e s t 1) . 5.26 Aboveground biomass of grasses and legumes seeded at 30 kg/ha (pot t e s t 1) . Page 81 x i v Figure Page 5.27 Ammonium, n i t r a t e and phosphorus leve l s of s p o i l under the stand of grasses at various seeding rates and legumes seeded at 15 kg/ha (pot t e s t 1) . . . . . . 5.34 Aboveground grass-legume biomass and ammonium + ni t r a t e l e v e l s , legumes seeded at 30 kg/ha (pot t e s t 2) 5.35 Maintenance f e r t i l i z e r a p p l i c a t i o n by helicopter . . . . . . . 5.36 pH and phosphorus on f e r t i l i z e d and u n f e r t i l i z e d plots . . . . . 5.37 Nitrogen (ammonium and nitr a t e ) l e v e l s on f e r t i l i z e d and u n f e r t i l i z e d plots 5.38 F e r t i l i z e r e f f e c t s on the aboveground grass biomass . . . . . . . 5.39 F e r t i l i z e r e f f e c t s on aboveground biomass of Dactylis glomerata and Festuca rubra 134 5.28 Ammonium, n i t r a t e and phosphorus l e v e l s of s p o i l under the stand of grasses at various seeding rates and legumes seeded at 30 kg/ha (pot t e s t 1) . . . . . . . 1 3 5 5.29 Acetylene reduction a c t i v i t y of legumes seeded at 15 kg/ha with various grass seeding and nitrogen f e r t i l i z e r rates (pot test 2) . . . . . . . . 1 3 6 5.30 Aboveground biomass of grasses at various seeding rates and legumes seeded at 15 kg/ha (pot t e s t 2) . . . . . . . 1 3 7 5.31 Acetylene reduction a c t i v i t y of legumes seeded at 30 kg/ha with various grass seeding and nitrogen f e r t i l i z e r rates (pot te s t 2) . 133 5.32 Aboveground biomass of grasses at various seeding rates and legumes seeded at 30 kg/ha (pot t e s t 2) . . . . . . . 1 3 9 5.33 Aboveground grass-legume biomass and ammonium + ni t r a t e l e v e l s , legumes seeded at 15 kg/ha (pot t e s t 2) W 141 144 147 150 153 155 X V Figure Page 5.40 T r i f o l i u m spp. establishment and s u r v i v a l on 1978 area . . . . . . . 5.41 Grass dominated vegetation on 1977 area 5.42 F e r t i l i z e r e f f e c t s on vegetation of 1975 and 1974 areas . . . . . . 5.43 Layout of f i e l d t e s t plots reclaimed i n 1974 and 1975 . . . . . . . 5.44 Seedlings of Lupinus cericeus and Astragalus  alpinus on 1974 area . . . . . 5.45 I n s t a l l a t i o n of open system acetylene reduc-t i o n assay units on legumes of reclaimed areas 5.46 An ethylene percentage comparison of open and closed systems tested on reclaimed areas 161 162 163 176 178 187 188 x v i ACKNOWLEDGEMENTS The w r i t e r w i s h e s t o thank D r s . F.B. H o l l , R.M. S t r a n g , and the o t h e r members o f h i s committee f o r t h e i r guidance i n a c c o m p l i s h i n g t h i s r e s e a r c h . S p e c i a l thanks a re due t o the p e r s o n n e l o f t h e E n v i r o n m e n t a l S e r v i c e s Department, B.C. C o a l L t d . ( f o r m e r l y K a i s e r Resources L t d . ) f o r t h e i r c o - o p e r a t i o n i n c o n d u c t i n g t h i s r e s e a r c h , e s p e c i a l l y A.W. M i l l i g a n and P. Da v i d s o n . Help p r o v i d e d ' b y t h e f o l l o w i n g i s s i n c e r e l y a p p r e c i a t e d : D.M. Andrews f o r f i e l d a s s i s t a n c e , G.W. Eaton f o r d e s i g n and s t a t i s t i c a l a n a l y s e s , A.N. M i n j a s , S.S. Parmar and J . F y l e f o r comments and a d v i c e , I.M. M i l n e and J.H. L a r s e n f o r s o i l a n a l y s e s , R i c h a r d s o n Seed Co. L t d . f o r seed s u p p l y , C.J. Johnson and C h r i s t i n e van den D r i e s e n f o r t y p i n g and P.M. G a r n e t t f o r t e c h n i c a l a s s i s t a n c e . Many o t h e r i n d i v i d u a l s have a l s o p r o v i d e d a s s i s t a n c e i n v a r i o u s phases o f the s t u d y . F i n a n c i a l s u p p o r t was p r o v i d e d by t h e U n i v e r s i t y o f B r i t i s h Columbia ( K a i s e r Resources F e l l o w s h i p ) , E n v i r o n m e n t a l S e r v i c e s Department, B.C. C o a l L t d . , a U n i v e r s i t y o f B.C. summer f e l l o w s h i p and the N a t u r a l S c i e n c e s and E n g i n e e r i n g Research C o u n c i l . 1 1. INTRODUCTION This study describes investigations into some aspects of vegetation restoration on sub-alpine, surface-mined lands in the southeastern Canadian Rockies near Sparwood, B r i t i s h Columbia. Environments at t h i s moderately high a l t i t u d e are generally unfavorable for non-native plant growth. Moreover, s o i l media, i . e . geologically-fresh coal mine sp o i l s are often located on steep slopes and are low i n s o i l f e r t i l i t y and water holding capacity. Under such conditions i n i t i a l plant establishment as well as rates of plant succession are slow. Therefore i t i s important to ameliorate t h i s adverse environ-ment for successful short-term revegetation. Potential improvements may be c l a s s i f i e d into two categories: those leading to the i n i t i a l establishment of plant communities and those influencing secondary succession or natural succession. The f i r s t type of improvement involves such a c t i v i t i e s as surface manipulation and s o i l amendments, e.g. harrowing and f e r t i l i z e r application; the second includes the influence of the i n i t i a l plant communities per se i n s o i l s t a b i l i z a t i o n through root system establishment and addition of organic matter to give increased s o i l f e r t i l i t y . The establishment of pioneer plant communities consist-ing of grasses and legumes may e f f e c t i v e l y accomplish the second type of improvement, p a r t i c u l a r l y with respect to s o i l nitrogen. S o i l nitrogen i s one of the major l i m i t i n g factors 2 i n successful revegetation (Goodman and Bray, 1975). Nitrogen may be applied i n i t i a l l y as f e r t i l i z e r , but i n the longer term, b i o l o g i c a l addition of nitrogen i s l i k e l y to be more economical and desirable. However, to e s t a b l i s h s e l f -sustaining plant communities, factors such as composition of grass-legume cover and s o i l nitrogen levels have to be considered. Available s o i l nitrogen i s of special concern here, because of the complicated nitrogen-dependent grass-legume i n t e r r e l a t i o n s (de Wit et a l . , 1966). While a rapidly established grass cover i s desirable for immediate s o i l s t a b i l i z a t i o n , a degree of legume cover i s also e s s e n t i a l to produce plant communities which may eventually lead to s e l f -sustaining, progressive plant succession, an ultimate objective of reclamation which i s widely recognized (Curry, 1975). The experiments reported i n t h i s thesis were designed to evaluate factors involved i n the establishment of such early s e r a i stages in plant succession including: 1. an analysis of the s o i l - p l a n t dynamics on e x i s t i n g revegetated s i t e s , 2. a study of grass-legume relationships under e x i s t i n g f e r t i l i z e r management, and 3. an evaluation of nitrogen fertilizer-grass-legume relationships with respect to optimizing nitrogen use, legume nitrogen-fixing symbiotic p o t e n t i a l and plant productivity. 3 2. LITERATURE REVIEW 2.1 Revegetation at high-altitude Limiting environmental factors for plant growth at high altitudes are well documented ( B i l l i n g s , 1973; Brown et a l . , 1978). They include short, cool growing seasons, summer drought, unstable s o i l s , extreme fluctuation i n d a i l y tempera-tures, great d i v e r s i t y of micro-climate, f r o s t heaving and strong winds. Furthermore, the rate of s o i l development i s limited by cold temperatures that retard the chemical reac-tions and b i o t i c a c t i v i t y that contribute to s o i l genesis (Retzer, 1974). Alpine plants adapted to these environments may have underground storage organs, low tufted growth forms, pre-formed over-wintering buds, seed dormancy at low tempera-ture, drough resistance, cold resistance, vegetative . reproduction, high l i g h t saturation values i n photosynthesis, and rapid growth during favorable periods (B l i s s , 1962; B i l l i n g s and Mooney, 1968). It i s apparent that successful re-establishment of persistent vegetation under these environments inevitably requires a c a r e f u l o v e r a l l assessment of reclamation a c t i v i t i e s including planned use of reclaimed lands. The assessment includes, i n order of importance, material (overburden or spoils) handling, configuration (e.g. aspect and steepness of slope) and plant establishment. The f i r s t two operations e s s e n t i a l l y determine the scope of the l a t t e r a c t i v i t y . Since the f i r s t two features involve mining p o l i c y and engineering 4 tasks, only factors that influence plant establishment are reviewed here. 2.1.1 S o i l amendment Coal s p o i l s , without amendment, are generally not suitable for plant growth. The spo i l s are often i n f e r t i l e , and show adverse physical properties, e.g. coarse s o i l texture and low organic matter content. Amendments that are u t i l i z e d for mined-lands at high a l t i t u d e s are, i n p r i n c i p l e , the same as those applied at low a l t i t u d e s . For example, Brown and Johnston (1980), i n the i r work on a high a l t i t u d e s p o i l , tested such amendments as f e r t i l i z e r (N:P:K = 18:24:6), lime, manure and surface mulch. The s o i l reaction of coal overburden can be one of the chemical factors most l i m i t i n g for plant establishment. Van Kekerix et a l . , (1979) reported that the geological materials of high a l t i t u d e s i n the western U.S. are often of p y r i t i c o r i g i n , and r e s u l t i n low pH levels l e t h a l to plants. Amend-ment often includes surface mechanical treatments of the spoils and requires various types of machinery. The applica-t i o n of these mechanical treatments can be d i f f i c u l t , and steepness of slopes at high elevations l i m i t s t h e i r application. The coal s p o i l s of high a l t i t u d e s i n southeastern B.C. are generally calcareous (pH values s l i g h t l y above 7) therefore s p o i l reaction per se i s not as serious a problem as reported i n many parts of the United States (Gardiner and Stathers, 1979; Van Lear, 1971). 5 2.1.2 Species selection There have been numerous investigations concerning the selection of plant species that are useful for high a l t i t u d e revegetation. Eaman (1974) suggested that the follow-ing features characterized for appropriate species: perennial, environmentally-adapted, primitive i n the evolutionary scale, and commercially available. From the viewpoint of plant adaptability, Brown e_t a l . , (1978) added the following c r i t e r i a : low-growing form, drought resistance, vegetative reproductive c a p a b i l i t i e s , capacity for high rate of photosynthesis, and r e s p i r a t i o n at low temperatures. Species selection may be notably s i t e - s p e c i f i c , i s limited by seed a v a i l a b i l i t y and depends on the objectives or the after-use of reclaimed lands. Etter (1973) proposed that grasses and forbs be established on warmer xeric south-facing slopes as winter range, and shrubs or trees on cooler north-facing slopes. In l i g h t of the general view that adaptation to environment i s an important factor, native species have been considered as p o t e n t i a l plant materials for high a l t i t u d e revegetation. Walker et a l . , (1977) investigated u t i l i z a t i o n and genetic improvement of native Alberta grasses from the eastern slopes of the Rocky Mountains. They reported that Agropyron trachycaulum and A. dasystachyum had high p o t e n t i a l for revegetation application. However, t h e i r studies, in which container grown plants were transplanted to mountain test s i t e s of other locales, remained inconclusive. The 6 revegetation p o t e n t i a l of these two species over wide geogra-phical areas needs to be demonstrated. At present operational use of native species has not been f u l l y r e a l i z e d i n most revegetation practices. As Brown et a l . , (1978) reported, cu l t i v a t e d agronomic species which were commercially available would l i k e l y play an important role i n short-term alpine revegetation, although t h e i r long-term su r v i v a l and persistence in these applications has not been well documented. For long-term s t a b i l i t y of vegetation, the incorporation of native species obviously would be more desirable, based on t h e i r demonstrated a b i l i t y to p e r s i s t . Table 2.1 summarizes the variety of native and non-native species that have been reported for use i n high a l t i t u d e revegetation. Mixtures of agronomic grasses and legumes have been seeded on to mined lands at high al t i t u d e (see e.g. Berg, 1972). The grasses may provide rapid ground cover, s t a b i l i z e the s o i l and build-up organic matter i n the s o i l s , while legumes appear to become established more slowly but may f i x atmospheric nitrogen and thus ultimately enrich the s o i l . The grasses and legumes i n commercial seed mixes generally include several species of broad ecological amplitude that buffer the wide environmental variations encountered on mined-lands. The botanical composition of seed mixes may also be altered to su i t s i t e - s p e c i f i c environments. Kaiser Resources Ltd. (1978) employed two seed mixes for i t s revegetation program at Sparwood, B.C., one for lower a l t i t u d e s and another for higher 7 Table 2.1 Grass and legume spec ie s used i n h i g h a l t i t u d e r e v e g e t a t i o n . nomenclature and common names  Grasses Agropyron c r i s t a t u m ( L . ) G a e r t n . Cre s ted wheatgrass A . s c r i b n e r i Vasey . Spreading wheatgrass A . t rachycaulum ( L i n k ) M a l t e . S lender wheat grass Alopecurus arundinaceus P o i r . F o x t a i l A . p r a t e n s i s L . Meadow f o x t a i l Bromus inermis Leyss Smooth brome grass D a c t y l i s glomerata L . O r c h a r d grass Deschampsia c a e s p i t o s a ( L . ) Beauv. Tuf ted h a i r g r a s s Elymus junceus F i s c h . Russ ian w i l d rye grass Festuca arundinacea Schreb. T a l l fescue (Reed fescue) F . ov ina v a r . duriuscula ( L . ) Hard f e scue . F . rubra L . Red fescue F . rubra v a r . commutata Gaud comments and source 1 Promis ing s p e c i e s , E t t e r (1973). N a t i v e , has p o t e n t i a l , Brown et a l . , (1978) . L o c a l source produced v i a b l e seeds but not from commercial Berg (1974); n a t i v e , has p o t e n t i a l , Brown et a l . , (1978); and promisTng s p e c i e s , E t t e r (1973). E s t a b l i s h e s w e l l , Berg ( 1 974) . E s t a b l i s h e s w e l l , Berg ( 1 974) . High n i t r o g e n requirement , e s t a b l i s h e s w e l l , Berg ( 1 974) . C o m p e t i t i v e , Berg (1974) N a t i v e , has p o t e n t i a l , Brown et a l . , (1975). Promis ing s p e c i e s , E t t e r (1973) C o m p e t i t i v e , Berg (1974) . Koch. Good s u r v i v a l , Se iner (1975). E s t a b l i s h e s w e l l , Berg (1974) ; promis ing s p e c i e s , E t t e r (1973) and good s u r v i v a l , S e i n e r (1975). Good s u r v i v a l , Se iner 8 L o l i u m perenne L . P e r e n n i a l ryegrass Phleum alpinum L . A l p i n e t imothy P . pratense L . Timothy Poa a l p i n a L . A l p i n e b luegrass P . p r a t e n s i s L . Kentucky b luegras s Legumes A s t r a g a l u s c i c e r L . C i c e r m i l k v e t c h C o r o n i l i a v a r i a L . Crown ve tch Lotus c o r n i c u l a t u s L. B i r d s f o o t t r e f o i l Medicago s a t i v a L . A l f a l f a Tr i f o l i u m hybridum L A l s i k e c l o v e r T. pratense L . Red c l o v e r T. repens L . White c l o v e r C o m p e t i t i v e , Berg (1974) N a t i v e , has p o t e n t i a l , Brown et a l . ( 1978). No v i a b l e seed produced, e s t a b l i s h e s w e l l , Berg (1974) ; p romis ing s p e c i e s , E t t e r (1973). N a t i v e , has p o t e n t i a l , Brown et a l . (1978). Good s u r v i v a l , Se iner (1975) . L i m i t e d i n a d a p t a b i l i t y , Berg (1974) . D i f f i c u l t to e s t a b l i s h from seed, Berg (1974). L i m i t e d i n a d a p t a b i l i t y , Berg (1974). L i m i t e d i n a d a p t a b i l i t y , Berg (1974). Short l i v e d , Berg (1974). Short l i v e d , Berg (1974) Grows b e t t e r on moist s i t e s , Berg (1974). Study areas and e l e v a t i o n Berg (1974): Utah , C o l o r a d o , and Montana, a l t i t u d e 2,700-3,000m. Brown et a l . (1978): Montana, a l t i t u d e 3,000 m. E t t e r TT973): A l b e r t a , a l t i t u d e 1,700 m. Se iner (1975): A l b e r t a , a l t i t u d e 2,000 m. 9 a l t i t u d e s . S i m i l a r l y , Macyk (1976) recommended two d i f f e r e n t seed mixes (Table 2.2) according to aspect of the s i t e . Besides species selection, seed provenance and s e l f -seeding can be important attributes for revegetation at high-a l t i t u d e s . Ritchie (1973), studying seed sources i n r e l a t i o n to high alti t u d e s (1,220 m) i n New Zealand, found that the samples of Phleum pratense with the heaviest seed weights and highest germination percentages came from s i t e s above 300 m. However, Berg (1974) found that P. pratense did not produce viable seed at a l t i t u d e s between 2,700 and 3,000 m. Sometimes a large grain species such as Secale cereale L. i s included i n the seed mix for subalpine revegetation as a nurse crop (Brown, 1974). The nurse crop provides a similar function to grasses: quick ground cover, s o i l s t a b i l i z a t i o n and after dying back, serving as a mulch. Similar uses of S. cereale were reported by Jones et a l . , (1975) and Bennet et a l . , (1972). A number of legume species have been selected and tested for high a l t i t u d e revegetation, but the re s u l t s have not always been successful. Moore et a l . , (1975) noted that establishment of legume species tested was greatest i n shallow furrows created p r i o r to the broadcasting. Legume seedlings were also found to be more susceptible to f r o s t than grasses (Macyk, 1973). T r i f o l i u m repens and T. hybridum were not as e f f e c t i v e as Medicago sativa i n Alberta (Macyk, 1974). Berg and Barrau (1972) found that M. sativa dominated vegetation on a mine s p o i l that had been seeded two to eight years previously 10 Table 2.2 Recommended seed mixes for h igh a l t i t u d e s i t e s accord ing to aspect (Macyk, 1976). Spec i e s Percentage of mix by weight D r i e r N and S Moi s t c o o l e r N and f a c i n g s lopes S f a c i n g s lopes Agropyron c r i s t a t u m (L . ) G a e r t n . ( c re s ted wheat grass c v . Fa irway) 20 15 Bromus inermi s Lyss (smooth broome c v . Caton) 15 35 Elymus junceus F i s c h . (Russian w i l d rye c v . Sawki) 15 0 Festuca .rubra -L. • (red fescue c v . . B o r e a l ) 35 '15 Phleum pratense L . ( t imothy c v . Cl imax) 20 Medicago s a t i v a L . ( a l f a l f a c v . Rambler) 15 U T r i f o l i u m hybridum L . ( a l s i k e c l o v e r ) 0 1 5 11 with a mixture of grasses and legumes. They concluded that, once established, M. sativa probably outgrew the grasses because of i t s nitrogen f i x i n g a b i l i t y and i t s deep root system which can u t i l i z e water unavailable to grasses. Macyk (1976) also reported that M. sativa continued to thrive after i n i t i a l establishment, e s p e c i a l l y i n areas where the grass growth had become less vigorous such as those i n which no f e r t i l i z e r had been applied recently. Nonetheless the future persistence of M. sativa was uncertain and Moore et a l . , (1975) predicted that i t would probably reach peak density and productivity between 5 and 10 years after planting. 2.1.3 Plant establishment Once mined-lands are revegetated with an immediate ground cover, continued maintenance i s needed to ensure s t a b i l i t y . In consequence, colonization of revegetation s i t e s by native species has been studied at many locations. In an investigation of disturbed land revegetation i n the Northwest T e r r i t o r i e s , Younkin and Friesen (1976) found a s i g n i f i c a n t negative c o r r e l a t i o n between t o t a l seeded cover and native vascular plus bryophyte cover from the second growing season on. Furthermore, seed and f e r t i l i z e r application appeared to encourage native plant invasion where the cover of seeded vascular plants remained below 20%. As cover of seeded vascular plants increased above 40%, the contribution of invading species decreased. S i m i l a r l y Owen and Van Eyk (1975) reported that native species could not compete with the densely-12 seeded, rapidly-growing introduced grasses. They thought that heavy f e r t i l i z a t i o n favored the growth of grasses over natural colonization by native species. It i s also apparent that colonization i s not only affected by i n i t i a l seeding rates and f e r t i l i z a t i o n practises, but also by time. Brown (1974) found that i n one area, after 10 years, native grasses and forbs from natural succession constituted approximately 50% of the ground cover. As Ward (1974) stated, i t may be u n r e a l i s t i c to attempt to e s t a b l i s h o r i g i n a l native plant communities on mined-lands de novo. Disturbances provide e n t i r e l y new environments to which many natives are not adapted (Anderson, 1971). This view i s supported i n part by Brown et al., (1976) who found that only 10% of the native vascular species on the Beartooth Plateau, Montana were natural colonizers on alpine disturbances. 2.2 Legume nitrogen f i x a t i o n Goodman and Bray (1975) surveyed plants more or less s a t i s f a c t o r y for mine-land reclamation throughout the world, and observed that among them there was a high proportion of nitrogen-fixing species. Based on t h i s information, they concluded that nitrogen i s one of the nutrients that l i m i t s plant establishment on these s i t e s . The practice of using nitrogen-fixing species on mined-lands i s a consequence of the observation that such species can often play an important role i n enriching s o i l s with nitrogen i n natural succession, e.g. Van Cleve et a l . , (1971). 13 The f u l l e xploitation of symbiotic nitrogen-fixing species, however, demands an understanding of t h e i r compati-b i l i t y with non-fixing species and the function of the unique Rhizobium - legume association. Legumes can be incompatible with grasses (Dyrness, 1975) or high rates of nitrogen f e r t i l i z a t i o n may i n h i b i t legume germination (Warrington, 1976). When Tri f o l i u m repens (New Zealand pedigreed white clover) was grown associated with Lolium multiflorum Lam. (Ita l i a n ryegrass), i t was found that the grass took up almost a l l of the available s o i l nitrogen. Only 5 to 6% of labelled combined nitrogen was then recovered i n the clover (Walker et a l . , 1956). Although accurate determination of the nitrogen fixed by legumes in the f i e l d i s d i f f i c u l t , i t has been estimated that clovers and a l f a l f a (Medicago sativa) i n the temperate regions might add 150-200 kg/ha/yr of nitrogen to the s o i l (Russell, 1973). Legumes can be b e n e f i c i a l not only because of nitrogen f i x a t i o n but also by scavenging additional water supplies through t h e i r deep root systems. Relative water supply was reported by Motorina et a l . , (1971) to be higher under legume cover (Medicago sativa or Lupinus  polyphyllus Lindl.) than under grasses. These authors attributed the difference observed to the a b i l i t y of the legumes to u t i l i z e deeper water reserves during the summer dry period. 14 2.2.1 Biochemistry of nitrogen f i x a t i o n The Rhizobium - legume association i s i n i t i a t e d when bacteria invade a host v i a root hairs; a nodule develops from a small group of c e l l s i n the inner cortex of the roots. Once the bacteria have f i l l e d a p r o l i f e r a t i n g c e l l , they form the non-dividing bacteroids which possess an enzyme system, nitrogenase, responsible for the f i x a t i o n of nitrogen. The nitrogenase complex consists of two proteins, one containing molybdenum, iron and sulfur (Mo-Fe protein) and the other iron and sulfur (Fe protein). Both are e s s e n t i a l for enzyme 2 + a c t i v i t y , together with Mg and ATP (Russell, 1973). Nitrogen f i x a t i o n involves the reduction of ^ to NH^, and must take place i n an environment low i n oxygen. Nodules that are f i x i n g nitrogen contain leghaemoglobin, the function of which appears to be the active transport of oxygen for r e s p i r a t i o n while i t maintains a low free oxygen tension i n the nodule environment (Russell, 1973). In addition to ^ , nitrogenase also reduces a variety of triply-bonded nitrogen analogues such as C^ H,,, HCN, N 20, CH^NsC (Eady and Postgate, 1974). The substrate promiscuity of nitrogenase with C^B^ i s the basis i n the development of the widely used acetylene reduction assay. The e f f i c i e n c y of nitrogen f i x a t i o n i n nodulated symbionts i s affected by the l e v e l of nitrogenase-dependent hydrogen evolution which requires approximately four ATP per produced (Schubert and Evans, 1976). These authors reported a substantial species difference with respect to the 15 e f f i c i e n c y of nitrogen f i x a t i o n . For example, the r e l a t i v e H 2(air) e f f i c i e n c y 1- — — 7 - ^ — r — of Glycine max (L.) M e r r i l l (soybean) 2 was 0.52 and that of Alnus rubra Bong, (red alder) was 0.99, where (air) and (Ar) stand for natural and enforced hydrogen evolutions i n a i r and in argon based (N 2 free) gas, respectively. The nitrogen-fixing a b i l i t y of legumes may also r e f l e c t a basic physiological difference i n root nitrogen absorption from non-nitrogen f i x i n g herbaceous plants. I s r a e l and Jackson (1978) suggested an electrogenic hydrogen ion extru-sion pump as the primary d r i v i n g force for nutrient uptake i n legumes. In t h e i r model, cations enter the roots either i n response to the e l e c t r i c a l p o t e n t i a l gradient generated by the pump or as an in t e g r a l part of the pump operation. An equal uptake of inorganic cations and anions from the external solution occurs with many herbaceous non-leguminous plants exposed to n i t r a t e as dominant anions. An excess cation uptake causes substantial rhizosphere a c i d i t y generation, because hydrogen ions are extruded. The a c i d i t y thus increased i s believed to a f f e c t the calcium requirement for nodulation of legumes, since Rhizobium growth i s inhi b i t e d by such a c i d i c conditions (Holding and Lowe, 1971; Vincent, 1965). Becker and Crockett (1976) reported that Glycine max L. and Medicago  sativa i n s o i l s could lower the pH by one unit i n approximately 70 days. This increase i n a c i d i t y may also be an important factor that modifies phosphorus a v a i l a b i l i t y , p a r t i c u l a r l y i n 16 s l i g h t l y alkaline s o i l s where fixed calcium phosphate unavail-able to plants may become soluble at lower pH values (Buckman and Brady, 197 2). 2.2.2 Physiological factors and nitrogen f i x a t i o n Sprent (1979), assuming a legume to be well-nodulated, l i s t e d the following factors that contribute to e f f i c i e n t legume nitrogen f i x a t i o n : 1. S u f f i c i e n t supplies of photosynthate: (a) adequate production, i . e . s u f f i c i e n t leaf area, l i g h t , temperature, and CO2; (b) e f f i c i e n t transport to the nodule: not too much diverted to seeds, growing root t i p s , storage regions (stems, root, e t c . ) , 2. Appropriate conditions for nodule r e s p i r a t i o n , so that supplies of photosynthate can be converted into energy and reductant for nitrogen f i x a t i o n , 3. Good environmental conditions for nitrogen f i x a t i o n , and 4. E f f i c i e n t transport for products out of nodules and r e d i s t r i b u t i o n throughout the plant; a well-functioning vascular system. 2.2.3 S o i l nitrogen and phosphorus e f f e c t s on nitrogen fixation Numerous plant environmental factors are altered by coal mining a c t i v i t i e s : substratum i n s t a b i l i t y , compaction, stoniness, low s o i l f e r t i l i t y , etc. (Goodman and Bray, 1975). Many of these factors can i n h i b i t the growth of legumes as well as of most other plants. However, only a few of these factors which may have a d i r e c t impact on legume nitrogen f i x a t i o n can be e a s i l y modified during the f i n a l stages of reclamation. Such modifications include s o i l surface mechanical 17 treatments, f e r t i l i z e r application, liming, and so on. There-fore a broader perspective of factors that a f f e c t legume nitrogen f i x a t i o n than those l i s t e d by Sprent (1979) i s necessary for mined-land revegetation. One such factor i s s o i l mineral nitrogen i t s e l f . It i s well known that mineralized s o i l nitrogen can reduce legume nitrogen f i x a t i o n . Some of the reasons are l i s t e d as follows: 1. Depression of nodule formation (van Schreven, 1959). (a) reduction of the number of root hairs that can be infected (Russell, 1973). (b) destruction of the indole acetic acid responsible for root hair c u r l i n g (Gibson and Nutman, 1960; Kefford et a l . , 1960). 2. Depression of nitrogen f i x a t i o n i n the nodules by the products of n i t r a t e reduction (Rigaud, 1976), e.g. i n h i b i t i o n of nitrogenase synthesis (Lehninger, 1977). 3. Diversion of photosynthate from nodule to root t i p s by the n i t r a t e reductase induced in the root t i p (Small and Leonard, 196 9). The e f f e c t s of s o i l nitrogen on nitrogen f i x a t i o n are of considerable i n t e r e s t , since applied nitrogen f e r t i l i z e r not only reduces legume f i x a t i o n , but may also increase t o t a l nitrogen fixed i f the f e r t i l i z e r i s s t r a t e g i c a l l y applied during the nitrogen stress period. This period often precedes development of f u l l nitrogen f i x i n g capacity (Bergerson, 1977). Low concentrations of applied nitrogen can stimulate f i x a t i o n by contributing to delayed nodulation during early stages of plant growth, while eventually providing more s i t e s for nodule formation (MacConnell and Bond, 1977; Gibson and Nutman, 1960). Russell (1973) also stated that the root could normally accommodate only a limited number of nodules per unit 18 l e n g t h : hence, i f r o o t growth ceased f a i r l y e a r l y i n the season (e.g. peas bu t not c l o v e r s ) t h e r o o t system c o u l d be s a t u r a t e d w i t h n o d u l e s . F u r t h e r m o r e , a p p l i c a t i o n o f n i t r o g e n f e r t i l i z e r e a r l y i n a season may a l s o be b e n e f i c i a l i f legumes a r e grown i n s o i l s o f low temperature such as s u b a l p i n e a r e a s (V.C. y. Brink'*', p e r s o n a l communication). T h i s i s p r o b a b l y because o f the low e f f i c i e n c y o f n i t r o g e n f i x a t i o n a t low t e m p e r a t u r e s as r e p o r t e d by Gibson (1961). A l t h o u g h c a p a b l e o f f o r m i n g a n i t r o g e n - f i x i n g s y m b i o s i s , legumes appear t o p r e f e r t o u t i l i z e s o i l n i t r a t e d i r e c t l y . T h i s s e l e c t i o n may be a consequence o f t h e energy c o s t o f n i t r o g e n f i x a t i o n . The r e a c t i o n o f m o l e c u l a r hydrogen and d i n i t r o g e n t o form ammonia i s an e x o e r g i c r e a c t i o n (AF=-9 k c a l ) (LaRue and-Mahon, 1976). As shown below, 12 ATP are b e l i e v e d t o be r e q u i r e d t o reduce one m o l e c u l e o f N 2 t o NH-j ( L e h n i n g e r , 1977). N 2 + 6H + + 6e" + 12ATP + 12H 20 -> 2 NH^ + 12 ADP + 12P ± A more r e c e n t paper (Hardy, 1981) suggests even h i g h e r energy and c a r b o h y d r a t e r e q u i r e m e n t s (25 ATPs/N 2 m o l e c u l e f i x e d o r 10 g of c a r b o h y d r a t e / g N 2 f i x e d ) . T h i s s u b s t a n t i a l ATP r e q u i r e m e n t a c c o u n t s f o r the o b s e r v a t i o n t h a t a p p r o x i m a t e l y o n e - t h i r d o f p l a n t p h o t o s y n t h a t e i s u t i l i z e d by nodule a c t i v i -t i e s ( M i n c h i n and P a t e , 1973). The p r e f e r e n c e o f legumes f o r R e s e a r c h P r o f e s s o r . Department o f P l a n t S c i e n c e , F a c u l t y o f A g r i c u l t u r a l S c i e n c e s , U n i v e r s i t y o f B.C., Vancouver, B.C. 19 s o i l nitrogen was demonstrated by Oghoghorie and Pate (1971). They found that any l e v e l of n i t r a t e appeared to suppress nitrogen f i x a t i o n i n Pisum arvense L. ( f i e l d pea) and that the general s u i t a b i l i t y of n i t r a t e as a source of nitrogen was shown by the o v e r a l l increase i n dry matter and i n t o t a l organic nitrogen. /Another f e r t i l i t y factor that influences legume f i x a t i o n i s phosphorus, which i s almost invariably applied as synthetic f e r t i l i z e r i n revegetation. Available phosphorus i s often found only i n trace amounts in coal mine spoils (Gardiner and Stathers, 1979; Reeder and Berg, 1977). It i s known that legumes require r e l a t i v e l y large amounts of phosphorus (Scanlan, 1928) and that i f these requirements are not met, nodule formation and nodule function are both depressed (Vincent, 196 5), probably because of the high demand for phosphorus used to synthesize ATP for nitrogen f i x a t i o n , i . e . synthesis and maintenance of the nodule, transport of carbohydrate and amino acid, and the enzymatic reduction of dinitrogen (LaRue and Mahon, 1976). This view i s supported by the experimental evidence of Graham and Rosas (1979) who found that nitrogen f i x a t i o n , s p e c i f i c nodule a c t i v i t y , and non-structural carbohydrate in nodules are highly correlated with phosphorus supply. Phosphorus application as f e r t i l i z e r therefore may be p a r t i c u l a r l y important in legume establishment and nitrogen f i x a t i o n on coal mined-lands. Gardiner and Stathers (1979) applied various amounts of phosphorus (up to 1,600 kg/ha as treble super phosphate) i n an 20 attempt to e s t a b l i s h legume-dominated vegetation on a coal mine s p o i l in B.C. Their seed mix, applied at 50 kg/ha, consisted of Medicago sativa cv. Rambler and Festuca rubra cv. Boreal at 1 : 1 r a t i o by weight. Nitrogen and potassium were applied at 50 kg/ha each during the f i r s t growing season. Second season biomass production (aboveground) of the legume ranged from 200 kg/ha with no phosphorus, to between 4,000 and 5,000 kg/ha with 800 kg/ha of phosphorus f e r t i l i z e r a pplication. The nitrogen y i e l d expressed as biomass times nitrogen content (percentage) ranged from 3 kg/ha with no phosphorus to 12 3 kg/ha with 800 kg/ha of phosphorus f e r t i l i z e r . Based on these results i t can be concluded that phosphorus plays an important role i n the growth and nitrogen f i x a t i o n a c t i v i t y of M. sativa on such a s p o i l . 2.3 S o i l nitrogen transformations In order to e s t a b l i s h a s e l f - s u s t a i n i n g plant community on a mined-land, a certain l e v e l of available s o i l nitrogen must be created and maintained. S o i l nitrogen levels can be increased by applying nitrogen f e r t i l i z e r or through b i o l o g i c a l f i x a t i o n of atmospheric nitrogen. The l e v e l of available s o i l nitrogen, however, does not necessarily correlate with the t o t a l amount of nitrogen i n s o i l s because much of that n i t r o -gen may ex i s t in an unavailable form. Consequently, an under-standing of s o i l nitrogen transformations and c y c l i n g becomes important. Nitrogen transformations of significance i n long-term 21 revegetation involve b i o l o g i c a l conversions v i a mineralization, immobilization and d e n i t r i f i c a t i o n . These processes and th e i r relationships are i l l u s t r a t e d in Figure 2.1. Because these changes are often mediated by b i o l o g i c a l agents, factors which influence b i o l o g i c a l a c t i v i t i e s i n s o i l also control rates and amounts of the nitrogen transformations. Such factors include: water, oxygen, energy (organic matter), carbon/nitrogen r a t i o , and s o i l environmental factors such as pH and temperature. 2.3.1 Mineralization The organic nitrogen —* ammonium nitrogen transformation i s c arried out by conspecialized organisms. The ammonium —** n i t r i t e n i t r a t e transformations, however, are said to be carried out by specialized organisms. Greatest importance i s attached to Nitrosomonas, which oxidizes ammonium to n i t r a t e , and to Nitrobacter, which oxidizes n i t r i t e to n i t r a t e (Black, 1968). For the a c t i v i t i e s of these specialized organisms any nutrient other than an energy substrate, i . e . ammonium and n i t r i t e , i s ra r e l y required (Alexander, 1965). These micro-organisms, however, do require elemental oxygen for th e i r a c t i v i t y . Under anaerobic conditions, the process i s halted at the stage of ammonium formation (Black, 1968). The adapta-ti o n of nitrogen mineralizing organisms to d i f f e r e n t s o i l moisture levels i s broader than that of plants. However, drying tends to k i l l the n i t r i f y i n g microorganisms, and in semi-arid regions there may be a considerable i n t e r v a l between the onset of the rains after a pronounced dry season and the n o n s p e c i a l i z e d s p e c i a l i z e d s p e c i a l i z e d organisms a u t o t r o p h s , a u t o t r o p h s , N itrosomonas N i t r o b a c t e r O r g a n i c n i t r o g e n (slow) -+ NH4+ ( f a s t ) N02" ( v e r y f a s t ) -> N03-ammoni f i c a t i o n 1 n i t r i f i c a t i o n 2 m i n e r a l i z a t i o n ' i m m o b i l i z a t i o n d e n i t r i f i c a t i o n 5 (- • ) F i g u r e 2.1 M i c r o b i o l o g i c a l p r o c e s s e s of n i t r o g e n t r a n s f o r m a t i o n ( a f t e r B l a c k , 1968) 1. A m m o n i f i c a t i o n : t r a n s f o r m a t i o n of o r g a n i c n i t r o g e n t o ammonium. 2. N i t r i f i c a t i o n : o x i d a t i o n of ammonium t o n i t r i t e and n i t r a t e . 3. M i n e r a l i z a t i o n : c o n v e r s i o n of o r g a n i c n i t r o g e n t o a m i n e r a l form w i t h o u t d i s t i n c t i o n of the s e v e r a l forms of m i n e r a l n i t r o g e n as e n d - p r o d u c t s 4. I m m o b i l i z a t i o n : change of m i n e r a l n i t r o g e n , t o o r g a n i c form. 5. D e n i t r i f i c a t i o n : c u r r e n t l y used o n l y t o r e f e r t o p r o c e s s e s by which gaseous forms of n i t r o g e n a r e produced from n i t r i t e and n i t r a t e . 23 onset of n i t r i f i c a t i o n (Russell, 1973). As a general rule, the greatest n i t r i f y i n g a c t i v i t y appears to occur at about 50-60% of s o i l moisture-holding capacity (Alexander, 1965). The e f f e c t of s o i l pH on mineralization i s rather complex. In general, between pH 5 and 8 there i s l i t t l e e f f e c t of pH on n i t r i f i c a t i o n (Russell, 1973). However, t h i s same author also stated that no clear relationship existed in very acid s o i l s between s o i l pH and rate of n i t r i f i c a t i o n because the e f f e c t of a c i d i t y was mediated by the toxic e f f e c t of aluminum ions. A c i d i t y i t s e l f , within reasonable l i m i t s , seemed to have l i t t l e influence on n i t r i f i c a t i o n when adequate bases were present (Buckman and Brady, 1972). These authors contended that n i t r i f i c a t i o n required an abundance of exchange-able bases and that t h i s accounted i n part for feeble n i t r i f i -cation a c t i v i t y in acid s o i l s and the seeming s e n s i t i v i t y of the organisms to low pH. It i s well established that temperature has s i g n i f i c a n t e f f e c t s on the a c t i v i t i e s of n i t r i f y i n g bacteria (Alexander, 1965). Increasing temperature stimulates microbial a c t i v i t y generally. Alexander (196 5) c i t e d an optimum temperature range between 30 and 35°C. N i t r i f i c a t i o n goes on very slowly below 4 or 5°C (Russell, 1973). There may, however, be a slow but s i g n i f i c a n t ammonium and n i t r i t e oxidation at 2°C (Frederick, 1956). I t i s also i n t e r e s t i n g to note that n i t r i f y i n g bacteria can become adapted to cold s o i l s , for Mahendrappa et a l . , (1966) found that n i t r i f i c a t i o n went on most rapidly at between 20 and 25°C i n s o i l s from the northern 24 part of the western United States, but at between 35 and 40 °C in s o i l s from the southern region. Because the rates of nitrogen mineralization i n s o i l s and of nitrogen use by plants are d i f f e r e n t functions of temperature, the s u f f i c i e n c y of s o i l nitrogen for plant development may vary with the tempera-ture (Black, 1968). 2.3.2 Immobilization and d e n i t r i f i c a t i o n Nitrogen immobilization results from the synthesis of microbial c e l l tissue containing organic nitrogen. The opposing processes of immobilization and mineralization occur continuously and simultaneously i n most systems where organic debris i s undergoing microbiological decomposition (Bartholo-mew, 1965) . Thus the amounts of mineral nitrogen released from organic reserves depend on the balance that exists between the factors that a f f e c t nitrogen mineralization, immobilization, and losses from the s o i l (Tisdale and Nelson, 1969) . According to Russell (1973), and Broadbent and Clark (1965) d e n i t r i f i c a t i o n i s a r e s u l t of the substitution of n i t r a t e or n i t r i t e for oxygen as a hydrogen acceptor in enzymatic oxidation reactions, and i t takes place only i f oxygen i s d e f i c i e n t . D e n i t r i f i c a t i o n can occur a c t i v e l y only in s o i l s containing an adequate supply of organic matter. As in the case of other b i o l o g i c a l processes, i t exhibits a temperature dependence, the optimum range (60 - 6 5°C) being surp r i s i n g l y high. Its rate i s profoundly influenced by s o i l 25 pH, being very slow i n acid s o i l s (pH below 4.5) and very rapid in s o i l s of high pH. D e n i t r i f i c a t i o n also may be strongly enhanced by soluble organic matter exuded from a plant root system (Day et a l . , 1978). 2.3.3 Nitrogen a v a i l a b i l i t y and accumulation There are three basic factors which play an important role i n assessing long-term accumulation and a v a i l a b i l i t y of s o i l nitrogen; t o t a l nitrogen, carbon to nitrogen r a t i o (C/N ratio) of fresh organic matter or the whole s o i l body, and nitrogen c y c l i n g . The t o t a l nitrogen of s o i l s i s an important factor i n the maintenance of s o i l organic matter the accumula-tion of which bears a close relationship to the process of nitrogen accumulation (Stevenson, 1965). This i s a r e s u l t of the constancy of the C/N r a t i o i n s o i l s . As Russell (1973) stated, the C/N r a t i o varied between 8.5 and 12.8 i n spite of a wide v a r i a t i o n i n carbon content and land use. This constancy of a C/N r a t i o r e s u l t s from continuous mineraliza-t i o n and immobilization of nitrogen. The magnitude and d i r e c -t i o n of the net e f f e c t i s greatly influenced by the nature and quantity of organic matter added. If carbonaceous matter i s in excess (C/N r a t i o > ca. 20), nitrogen i s generally im-mobilized (Tisdale and Nelson, 1969). However, as Bartholomew (1965) pointed out, the C/N r a t i o i s less r e l i a b l e as an index of nitrogen immobilization than are nitrogen percentages of s o i l organic residues, because the former incorporates the normal errors of determining both carbon and nitrogen. Further-26 more, decomposition depends on the C/N r a t i o d i r e c t l y only when a l l carbon and nitrogen are re a d i l y available (Norman, 1933). S i m i l a r l y Black (1968) stated that the r a t i o was a poor index of the s u s c e p t i b i l i t y of s o i l nitrogen immobiliza-t i o n because of inclusion of nonexchangeable ammonium i n measuring the t o t a l nitrogen of s o i l s . In mine s p o i l s , the assessment of accumulation and a v a i l a b i l i t y of s o i l nitrogen becomes more complex as a r e s u l t of the presence of indigenous nitrogen and carbon. Total nitrogen analysis of revegetated s p o i l s could be misinterpreted i f i t were assumed that the nitrogen accumulation had a l l occurred since disturbance and revegetation (Berg, 1978) . This approach was also thought to overlook the nitrogen naturally present in geological materials which may range from 10 ppm in some igneous rocks (Stevenson, 1965) to 8,000 ppm i n o i l shales (Thorne et a l . , 1951). S i m i l a r l y , Wilson (1965) indicated that the determination of easily-oxidizable organic matter by the commonly used Walkley-Black method (Al l i s o n , 1965) might include some carbon from coal. Consequently, Berg (1978) questioned the significance of determining organic matter on carbonaceous shales i f plant growth correlations had not been made. Nitrogen c y c l i n g i s an important factor to be considered i n the determination of available nitrogen, p a r t i c u l a r l y i n s o i l s with low t o t a l nitrogen. An extreme example occurs i n t r o p i c a l r a i n forests where b i o l o g i c a l nutrient c y c l i n g v i a 27 decomposition i s rapid, and plant biomass acts as an important source of nutrients for plant growth (Luse, 1970). However, under unfavorable conditions, e.g. low pH and low temperature, organic matter decomposition and nitrogen c y c l i n g can be inhi b i t e d . Williams (1978) investigated nitrogen c y c l i n g i n two types of c o l l i e r y s p o i l s , acid (pH 4.0) and near-neutral (pH 6.0 - 7.0). On the acid s p o i l ammonium was consistently higher than n i t r a t e or n i t r i t e . On the near-neutral s p o i l , the concentrations of ammonium, n i t r i t e , and ni t r a t e ranged from 0 to 7 ppm without seasonal v a r i a t i o n , i n d i c a t i n g that rapid mineralization and n i t r a t e removal was occurring. He also found that the aboveground dry matter of l i v i n g plants was higher on the near neutral s p o i l , but the aboveground dry matter of dead plants was le s s . Thus his results suggested that while nitrogen a v a i l a b i l i t y was growth-limiting, the favorable pH value allowed the development of an active microfauna which promoted rapid c y c l i n g of the small quantities of nitrogen present i n t h i s c o l l i e r y s p o i l system. In an ecosystem at high al t i t u d e as in the acid s p o i l i n Williams 1 study, organic matter accumulation and slow nitrogen c y c l i n g can be expected i n an environment unfavorable for organic matter decomposition and nitrogen mineralization. In a sub-alpine forest of old growth /Abies amabilis Dougl. Forbes (Pacific s i l v e r f i r ) , Turner and Singer (1976) s i m i l a r l y found that the r e l a t i v e l y small productivity i n a h o s t i l e environment 28 required only small quantities of nutrients, and that there was a large reservoir of nutrients within the forest f l o o r organic matter. The process of t o t a l nitrogen accumulation i n a natural ecosystem i s very i n t e r e s t i n g . In a l l of the C a l i f o r n i a and Alaska ecosystems that Crocker (1967) investigated there was a very rapid buildup of t o t a l nitrogen during the pioneer and early stages of succession. As succession continued, a decline was observed i n the rate of nitrogen accumulation. Such observations pose an important question: How do nitrogen accumulation and c y c l i n g occur i n mine spoils? In the study of Anderson (1977) both nitrogen and organic matter accumulated very rapidly on 28 - 40 years old g l a c i a l t i l l mine s p o i l banks i n the semiarid grassland i n Saskatchewan. Nitrogen had accumulated at a rate of 24 kg/ha/yr, several times greater than those reported elsewhere for grasslands in Saskatchewan. Organic matter accumulation of 2 50 kg/ha/yr, suggested that levels c h a r a c t e r i s t i c of the regional s o i l s could be accumu-lated i n 250 - 350 years. Caspall (1975) also reported rapid increases i n organic matter i n the surface 15 cm of I l l i n o i s s p oils from an i n i t i a l l e v e l of 0.4 to 2.5% after 14 years, i . e . at a rate of 3,300 kg/ha/yr. However, i t i s not clear whether t h i s organic matter buildup came at least i n part from natural carbon i n the spoils which had become rapidly oxidizable upon exposure and weathering (Berg, 1975). Si m i l a r l y , transformation of nitrogen naturally present 29 in spoils i s equally i n t e r e s t i n g . Power et a l . , (1974) reported that Paleocene shale below 10 m contained 10 - 40 ppm exchangeable ammonium and 1 - 3 ppm n i t r a t e . The exposure of the shale to atmospheric weathering for one summer generally resulted i n rapid n i t r i f i c a t i o n and a reversal i n the r e l a t i v e concentrations of the exchangeable ammonium and n i t r a t e . The shale also contained organic nitrogen (about 200 ppm). However, th e i r 154 day incubation did not r e s u l t i n a net increase i n the inorganic nitrogen content. They suggested that the extent of mineralization of the organic nitrogen was minimal, and that t h i s component i s b i o l o g i c a l l y r e l a t i v e l y i n e r t . Reeder and Berg (1977) also f a i l e d to detect nitrogen minerali-zation i n Cretaceous shale when i t was incubated for 168 days. However, they found that microorganisms were capable of using the forms of nitrogen present i n the shale and were not limited by the amount of available nitrogen present. They postulated that the mineralized ammonium might be immobilized by the microbial population before i t could be n i t r i f i e d . It was assumed that only a small percentage of t o t a l organic carbon was available to microorganisms i n the shale because of i t s l i k e l y occurrence i n a condensed, i n e r t form. Upon weathering of the shale t h i s i n e r t form of the carbon may become more available, thus producing a corresponding increase in microbial a c t i v i t y . 30 3. STUDY AREA 3.1 Location The study area i s located at an a l t i t u d e of 2,000 m above sea l e v e l (a.s.l.) on the coal mining property of B.C. Coal Ltd. (formerly Kaiser Resources Ltd.) near Sparwood B.C. (Figures 3.1 and 3.2). This area has been extensively surface mined i n recent years by B.C. Coal Ltd., one of the major producers of metallurgical coal i n Canada. The company was reported to have produced 5.7 m i l l i o n tons of raw metallurgical coal from open p i t i n 1978 (Worobec, 1979). 3.2 Climate Climatic patterns i n t h i s region are influenced by three main types of a i r masses: continental a r c t i c , maritime p a c i f i c , and maritime t r o p i c a l . Continental a r c t i c a i r influences the study area only infrequently because the ranges of the continental divide form a ba r r i e r to i t s westward spread. Occasionally, however, "polar outbreaks" occur i n winter, and tongues of cold a i r flow westward through the main r i v e r valleys of the region. These outbreaks bring exceptionally low minimum temperatures of -35°C or lower. Maritime p a c i f i c a i r originates i n the Gulf of Alaska as a modification of polar continental a i r which, through a long passage over the North P a c i f i c , acquires marine characteris-t i c s . Such occurrences are common in the region, p a r t i c u l a r l y during the winter months, and r e s u l t i n most of the annual 31 Figure 3.1 Study area and exper imenta l p l o t l o c a t i o n . Each area i s l a b e l l e d w i t h the year i n which r e v e g e t a t i o n was i n i t i a t e d . F i e l d t e s t p l o t s are i n d i c a t e d by • i n each a r e a . i 32 F i g u r e 3.2 Study a r e a . (a) L o o k i n g west. The study area i s l o c a t e d a t the upper f a r l e f t on the h i l l . (b) L o o k i n g toward the m i n i n g complex from the study a r e a . 3 3 p r e c i p i t a t i o n . The maritime t r o p i c a l a i r masses arise i n the P a c i f i c Ocean at latitude 30 - 35° N and arrive i n the region somewhat cooled although they seldom reach the surface (Marshall, 1959). In the mining area climate may be c l a s s i f i e d as continental sub-humid (Dfb) at the lower elevation, and continental cold-humid (Dfc) at the higher elevations (after Koppen, i n Dick, 1978). The nearest weather station, on Harmer Ridge, i s at an al t i t u d e of 1,920 m a . s . l . and i s located approximately 2 km northwest of the study area. Temperature and p r e c i p i t a t i o n data from the station are summarized i n Table 3.1. The 1971-1974 data showed that snow occurred i n a l l months of the year and accounted for approximately 78% of the annual p r e c i p i t a -t i o n . P r e c i p i t a t i o n was heaviest from November to February, and was r e l a t i v e l y evenly d i s t r i b u t e d throughout the rest of the year. The average f r o s t - f r e e period was 61 days, while the growing season for hardy perennial plants, as defined by those months with a mean temperature of 5°C or higher, averaged 4 months (Dick, 1978) . 3.3 Geology The area i s part of the Fernie Basin of the Rocky Mountain system, a s t r u c t u r a l basin i n which so f t , e a s i l y -eroded sandy and shale-like sedimentary rocks of Mesozoic age occur. The general aspect of the Fernie Basin i s one of moderate r e l i e f , gently r o l l i n g upland, steep v a l l e y walls, and f l a t a l l u v i a l p l a i n s . The maximum elevation reached i s 3k T a b l e 3.1 Monthly mean temperature and p r e c i p i t a t i o n o f N a t a l Harmer Ridge weather s t a t i o n , B.C. temp e r a t u r e (°C) p r e c i p i t a t i o n (cm) 3 month 1971-74 1 1980 2 1971-1974 1980 r a i n snow t o t a l r a i n snow t o t a l J a n u a r y -13.2 -13.9 0.0 141.2 14.1 0.0 131.5 13.2 F e b r u a r y - 8.2 - 8.2 0.0 79.6 8.0 t r a c e 6.4 6.4 March - 5.2 - 7.7 t r a c e 58.8 5.9 0.0 62.2 6.2 A p r i l - 2.2 1.6 t r a c e 62.1 6.2 1.3 19.2 3.2 May 3.6 7.3 1.2 27 .6 4.0 6.9 0.0 6.9 June 9.2 8.0 4.2 8.5 5.0 4.2 2.6 4.4 J u l y 11.8 10.2 6.1 1.6 6.3 3.9 0.0 3.9 August 13.4 7.1 4.2 2.8 4.5 5.1 0.0 5.1 September 5.2 6.4 2.6 30 .1 5.6 6.1 0.0 6.1 October 1.2 1.2 0.6 42.7 4.7 0.3 17.0 2.0 November - 6.2 - 8.2 0.0 116 .8 11.7 0.0 72.2 7.2 December -10.2 -16 .9 0.0 112.3 11.2 0.0 160 .5 16 .0 Data f o r 1971-1974 were e x t r a c t e d from D i c k (1978) . 2 Data f o r 1980 were d i r e c t l y o b t a i n e d from t h e N a t a l Harmer Ridge weather s t a t i o n . F o r u n i f o r m i t y i n t h e T a b l e a l l measurements are g i v e n i n cm, r e g a r d l e s s o f t h e u n i t used i n the o r i g i n a l s o u r c e . 35 2,260 m a . s . l . w i t h the m a j o r i t y o f the upl a n d a r e a l y i n g between 1,650 and 2,140 m a . s . l . The e n t i r e F e r n i e B a s i n was g l a c i a t e d but the o n l y s i g n i f i c a n t t i l l d e p o s i t s o ver 1,700 m a . s . l . a r e i n g u l l i e s and d e p r e s s i o n s ( H o l l a n d , 1976; H a r r i s o n , 1974) . A c o a l - b e a r i n g s t r a t i g r a p h i c u n i t , t h e Kootenay forma-t i o n c o m p r i s e s t h r e e members: E l k , C o a l - b e a r i n g and Moose Mountain. The E l k member i s upper-most and i s composed o f c h e r t y c o n g l o m e r a t e s , c o a r s e g r a i n e d sandstones and gray t o b l a c k c a l c a r e o u s s h a l e s . The C o a l - b e a r i n g member i s composed o f grey t o b l a c k carbonaceous s h a l e s , f i n e t o medium-grained s a n d s t o n e s , a few bands o f peb b l e conglomerate and a v a r y i n g number o f c o a l seams. Sandstones and conglomerate make up 30% o f t h e f o r m a t i o n w i t h t h e b a l a n c e e i t h e r c o a l o r s h a l e . T h i s member v a r i e s i n t h i c k n e s s from 560 t o 1,100 m a t M i c h e l , a few k i l o m e t e r s o f f t h e s t u d y a r e a . A massive b a s a l sand-stone l a y e r t h e Moose Mountain member forms the lower l i m i t s o f t h e Kootenay f o r m a t i o n (Newmarch, 1953; P r i c e , 1962; D i c k , 1978). 3.4 S o i l and v e g e t a t i o n G e n e r a l l y the s o i l s o f t h i s r e g i o n a re young, and s o i l p r o c e s s e s have o n l y weakly m o d i f i e d t h e p a r e n t m a t e r i a l s . However, because o f t h e r a t h e r complex g l a c i a l and p o s t - g l a c i a l h i s t o r y , c o n s i d e r a b l e s o i l v a r i a b i l i t y e x i s t s . W i t t n e b e n (1969) r e p o r t e d t h a t t h e s o i l s around the stu d y a r e a c o n s i s t e d o f : (a) a t h i g h e l e v a t i o n s (above 1,500 m) - M i n i and Ortho Humo-36 F e r r i c P o d z o l s , . and A l p i n e D y s t r i c B r u n i s o l s , a l t e r n a t i n g w i t h exposed bedrock and R e g o s o l s on u n s t a b l e c o l l u v i u m , and (b) a t m i d d l e e l e v a t i o n s : E u t r i c B r u n i s o l s and more r a r e l y Dark brown o r Dark-gray Chernozems. D i c k (1978) r e p o r t e d t h a t two o f the B i o g e o c l i m a t i c Zones d e s c r i b e d by K r a j i n a (1965) o c c u r r e d on t h e B.C. C o a l L t d . m i n i n g a r e a : t h e I n t e r i o r D o u g l a s - f i r Zone a t a l t i t u d e s from 1,100 m t o 1,500 m a . s . l . , and t h e Engelmann S p r u c e -S u b a l p i n e F i r Zone from 1,500 m t o 2,100 m a . s . l . W i t h i n the l a t t e r zone were t h r e e p l a n t communities w h i c h r e f l e c t e d b o t h p h y s i o g r a p h i c i n f l u e n c e s and v a r i a t i o n s i n s u c c e s s i o n a l h i s t o r y . They were: Open S u b a l p i n e F o r e s t P a r k l a n d , C l o s e d -canopy S u b a l p i n e C l i m a x F o r e s t a t a l t i t u d e s 1,500 - 1,700 m a . s . l . , and F i r e - i n d u c e d S e r a i F o r e s t . The st u d y a r e a (2,000 m a . s . l . ) i s i n t h e Open S u b a l p i n e F o r e s t P a r k l a n d r e f e r r e d t o by D i c k (1978). 37 4. MATERIALS AND METHODS 4.1 Weather d a t a I n t h e e a r l y s p r i n g o f 1980 a weather s t a t i o n was s e t up on t h e s i t e o f t h e s t u d y a r e a r e c l a i m e d i n 1974, and d a t a c o l l e c t e d weekly d u r i n g t h a t summer ( F i g u r e 4.1). Independent weather d a t a c o l l e c t i o n was c o n s i d e r e d n e c e s s a r y because th e n e a r e s t weather s t a t i o n ( N a t a l Harmer Ridge) d i d not p r o v i d e some i n f o r m a t i o n r e q u i r e d f o r t h e s t u d y o b j e c t i v e s . D e t a i l s o f equipment and d a t a c o l l e c t i o n are l i s t e d i n T a b l e 4.1. For comparison s o i l minimum and maximum te m p e r a t u r e s a t 10 cm depth were a l s o r e c o r d e d i n t h e u n d i s t u r b e d s u b a l p i n e f o r e s t a s s o c i a t e d w i t h the s t u d y a r e a . 4.2 F i e l d s u r v e y 4.2.1 N a t u r a l s u b a l p i n e f o r e s t D u r i n g t h e summer o f 1979, v i s u a l r e c o n n a i s s a n c e was conducted t o c o m p i l e a l i s t o f n a t i v e s p e c i e s found i n t h e u n d i s t u r b e d v e g e t a t i o n a d j a c e n t t o t h e s t u d y a r e a . I d e n t i t y o f the p l a n t specimens c o l l e c t e d was s u b s e q u e n t l y c o n f i r m e d by S. Kojima (Toyama U n i v e r s i t y , J a p a n ) . Three 2 x 2 m p l o t s were demarcated i n t h e s u b a l p i n e f o r e s t from w h i c h s o i l and p l a n t samples were c o l l e c t e d on two s a m p l i n g d a t e s f o r p r e p a r a -t i o n and a n a l y s i s as d e s c r i b e d i n S e c t i o n 4.2.2 f o l l o w i n g . 38 Figure 4.1 Weather s t a t i o n on s i t e reclaimed i n 1974. Photographed i n May, 1980 Table 4.1 L i s t of equipment and types of weather data c o l l e c t e d from 1974 area. equipment r a i n gauge hygro-thermograph (weekly recording) i n a Stevenson Screen minimum and maximum thermometers data prec i p i t a t i o n a i r temperature and r e l a t i v e humidity s o i l min. & max. temperatures at 10 cm depth 39 4.2.2 Re c l a i m e d a r e a s D u r i n g t h e summers o f 1979 and 1980 a f i e l d s u r v e y was conducted on e x i s t i n g r e c l a i m e d a r e a s o f d i f f e r e n t ages. R e v e g e t a t i o n on t h e f o u r s i t e s was i n i t i a t e d i n t h e y e a r s : 1974 1, 1975, 1977 and 1978. The areas were p r e p a r e d by b u l l -d ozer f o r subsequent s e e d i n g by h e l i c o p t e r (Table 4.2). At s e e d i n g about 120 kg/ha o f 13-16-10 f e r t i l i z e r was a p p l i e d by h e l i c o p t e r . An a d d i t i o n a l 150-200 kg/ha o f 13-16-10 has been a n n u a l l y a p p l i e d as a maintenance f e r t i l i z e r t r e a t m e n t ( K a i s e r Resources L t d . , 1977, 1978 and 1980). S o i l and p l a n t samples were c o l l e c t e d from 1 m di a m e t e r c i r c u l a r p l o t s a l o n g l i n e t r a n s e c t s e s t a b l i s h e d on the s t u d y a r e a . I n t h e second y e a r p l o t s were sampled a l o n g the same l i n e t r a n s e c t s u s i n g a r e a s w h i c h had not been sampled d u r i n g t h e p r e v i o u s summer. P l a n t samples i n c l u d e d aboveground biomass, c l i p p e d and s e p a r a t e d by s p e c i e s , and l i t t e r . Biomass samples were d r i e d f o r 48 hours a t 70°C i n a f o r c e d d r a f t oven b e f o r e w e i g h i n g . S o i l samples (0-10 cm) were a i r d r i e d a t room te m p e r a t u r e and a n a l y z e d f o r t e x t u r e , pH, phosphorus, n i t r a t e and ammonium. A l l s o i l pH and phosphorus a n a l y s e s were made i n t h e l a b o r a t o r y o f t h e Department o f E n v i r o n m e n t a l S e r v i c e s , B.C. C o a l L t d . U n l e s s o t h e r w i s e i n d i c a t e d , s o i l samples were f r o z e n i m m e d i a t e l y a f t e r a i r - d r y i n g u n t i l a n a l y s i s ^ The a r e a r e v e g e t a t e d i n 1974 was not an overbur d e n dump. The ar e a was l e v e l l e d i n 196 8 f o r t h e i n s t a l l a t i o n o f a d r a g l i n e e x c a v a t o r and the r e s u l t a n t s u r f a c e m a t e r i a l was s i m i l a r t o t h a t o f t h e mine dumps ( Z i e m k i e w i c z , 1979). 40 T a b l e 4.2 O p e r a t i o n a l seed mix (56 kg/ha) f o r h i g h a l t i t u d e s used by K a i s e r Resources L t d . (1978). S p e c i e s A g r o s t i s a l b a L. Red top A l o p e c u r u s p r a t e n s i s L. Meadow f o x t a i l Bromus i n e r m i s Leyss Smooth broom c v . Manchar D a c t y l i s g l o m e r a t a L. Orchard g r a s s c v . Chinook F e s t u c a r u b r a L. Red f e s c u e L o l i u m perenne L. P e r e n n i a l r y e g r a s s Phleum p r a t e n s e L. Timothy c v . C l i m a x Poa compressa L. Canada b l u e g r a s s c v . Canon P. p r a t e n s i s L. Kentucky b l u e g r a s s cv. Geronimo T r i f o l i u m repens L. White c l o v e r T. hybridum L. A l s i k e c l o v e r P e r c e n t a g e o f mix by weight 15 15 10 15 15 41 for n i t r a t e and ammonium by Norwest-Priva Plant Laboratories Inc., B.C. The methods used for these analyses are as follows: texture for coarse and fine fragments by 2 and 4 mm mesh sieves; pH determined by a pH meter on a 1 : 1 (by weight) s o i l : d i s t i l l e d water mixture; phosphorus by the sodium bicarbonate method for extractable phosphorus (Olsen and Dean, 1965); n i t r a t e and ammonium extracted by 1 N KCl and deter-mined by steam d i s t i l l a t i o n (Byers, 1978). S o i l moisture percentages were also determined weekly by the gravimetric method (Lavkulich, 1978) on samples ( ca. 2 mm) col l e c t e d at 10 cm depth from the four areas adjacent to the f i e l d test plots described i n Section 4.4, and from the undisturbed subalpine forest. In the early spring of 1980, three tensiometers were i n s t a l l e d to 10 cm depth. Two of them were located adjacent to the test plots established i n areas reclaimed i n 1974 and 1977, one of them i n the subalpine forest. Water tension was recorded at weekly i n t e r v a l s . 4.3 Greenhouse pot tests Two greenhouse pot tests were conducted using s p o i l material c o l l e c t e d from the mining p i t near the study area. The f i r s t test was a 3 x 2 x 3 f a c t o r i a l experiment arranged in three randomized complete blocks. The pots were 27 cm in diameter and 18 cm deep. Treatments included three seeding rates of grasses, two seeding rates of legumes, and three rates of nitrogen f e r t i l i z e r . The three seeding rates of 42 g r a s s e s were 0, 17.5, and 35 kg/ha, u s i n g a m i x t u r e o f n i n e s p e c i e s a t 1:3:1:1:3:1:1:2:1 by w e i g h t o f A g r o s t i s a l b a : A l o p e c u r u s p r a t e n s i s : Bromus i n e r m i s : D a c t y l i s g l o m e r a t a : F e s t u c a r u b r a : L o l i u m perenne : Phleum p r a t e n s e : Poa  compressa : P. p r a t e n s i s , . r e s p e c t i v e l y . The two s e e d i n g r a t e s o f legume were 15 and 30 kg/ha, w i t h a two s p e c i e s m i x t u r e of 1:1 by w e i g h t o f T r i f o l i u m hybridum : T. p r a t e n s e , r e s p e c t i v e l y . These s e e d i n g r a t e s were a m o d i f i c a t i o n o f t h e o p e r a t i o n a l seed mix employed by B.C. C o a l L t d . f o r r e v e g e t a -t i o n a t a l t i t u d e s above 1,800 m a . s . l . (Table 2.2). The t h r e e r a t e s o f n i t r o g e n f e r t i l i z e r were 10, 50, and 100 kg/ha as e l e m e n t a l n i t r o g e n u s i n g 34-0-0 ammonium n i t r a t e (NI^NO^) . The s t a n d a r d amount o f 13-16-10 f e r t i l i z e r o p e r a t i o n a l l y a p p l i e d by t h e company i s 113 kg/ha a t s e e d i n g . The n i t r o g e n o f t h i s f e r t i l i z e r i s an ammonium form and e q u i v a l e n t t o 12 kg/ha o f e l e m e n t a l n i t r o g e n o r 15 kg/ha. A l l p o t s were a l s o t r e a t e d w i t h 200 and 100 kg/ha o f e l e m e n t a l phosphorus and p o t a s s i u m u s i n g 0-45-0 t r i p l e superphosphate T^?2°5^  and 0-0-65 m u r i a t e o f p o t a s h ( K C l ) , r e s p e c t i v e l y . The p o t s were seeded on October 13, 1979 and p l a n t s were h a r v e s t e d on F e b r u a r y 1-8, 1980 (subsequent r e f e r e n c e s w i l l be t o the 112 day h a r v e s t ) . For t h e second t e s t a 4 x 2 x 3 f a c t o r i a l e x periment was a r r a n g e d i n f i v e randomized complete b l o c k s . The f o u r s e e d i n g r a t e s o f g r a s s e s were 0, 17.5, 35, and 70 kg/ha, and the t h r e e r a t e s o f n i t r o g e n f e r t i l i z e r , 25, 50 and 75 kg/ha. 43 A l l pots were given the same treatment of phosphorus and potassium as described in the f i r s t experiment. The pots were seeded on December 1, 1980 and harvested on March 13-19, 1981 (subsequent references w i l l be to the 103 day harvest ) . Nitrogen f i x a t i on was measured by the acetylene reduc-t i on assay (Burris, 1974) c a r r i ed out twice for the f i r s t t e s t : 80-84 days (January 7-10, 1980) and 99-100 days (January 26-28, 1980) a f ter seeding; and three times for the second te s t , 64-65 days (February 2-3, 1981), 78-79 days (February 16-17, 1981) and 99-100 days (March 9-10, 1981) a f ter seeding. An a i r - t i g h t c losed system was obtained by sea l ing the drainage holes of the 9 l i t e r pots which contained approximately 7 l i t e r s of s p o i l and growing p lants , p lac ing an i d e n t i c a l pot upside down on top of the pot, and sea l ing the adjoining edges with v i n y l e l e c t r i c i a n ' s tape. The top pot was equipped with a serum stopper for sampling and a gas i n jec t i on hole where a 1 l i t e r polyethylene bot t le f i l l e d with commercial acetylene was f i t t e d (Figure 4.2). The closed system i s about 19 l i t e r s i n volume, containing approximately 8% by volume of acetylene. Af ter a one-hour incubat ion, gas samples (1 ml) were withdrawn by syringe and analyzed by gas chromatography using a Hewlett-Packard Model 5830 gas chromatograph equipped with dual flame i on i za t i on detectors . The one-hour incubation was always conducted between 9:00 a.m. - 12:00 noon. Running condit ions for gas chromatography were as fo l lows: oven temperature 50°C, s ta in less s tee l column (0.3 x 180 cm) packed Figure 4.2 Closed system acetylene reduction assay. (a) Close-up of a c l o s e d system. (b) In s i t u one-hour incubation i n progress. 45 with Porapak N (80 - 100 mesh), using nitrogen as the c a r r i e r gas at a flow rate of 40 ml/min. At the end of each pot t e s t , aboveground and below-ground biomass was harvested for dry matter determination of grasses and legumes separately. S o i l samples were collected on termination of the f i r s t pot t e s t , and at 52 days (January 21, 1981) after seeding i n the second pot te s t . The s o i l samples were analyzed for phosphorus, n i t r a t e and ammonium i n the f i r s t experiment, and ni t r a t e and ammonium i n the second experiment (analytical d e t a i l s i n Section 4.2.2). 4.4. F i e l d tests F i e l d tests on the e x i s t i n g vegetation of mined-lands were conducted to study the ef f e c t s of operational f e r t i l i z a -t i o n on legume nitrogen f i x a t i o n , biomass and i t s botanical composition. As a part of a native legume establishment t r i a l two native legume species were planted and observed on the area revegetated i n 1974. A new non-destructive, open-system method of acetylene reduction assay was also investigated to determine i t s f e a s i b i l i t y for future use on mined-lands. 4.4.1 F e r t i l i z e r e f f e c t s on s o i l and vegetation F i e l d tests were conducted on the ex i s t i n g vegetation of the four s i t e s reclaimed during 1974-1978 (Figure 3.1). The design was a 2 x 2 x 2 f a c t o r i a l arranged as a s p l i t - s p l i t p l o t , of which a p a r t i a l layout i s i l l u s t r a t e d i n Figure 5.43 (see p. ). The three treatment factors were age, location 46 and f e r t i l i z e r . The b l o c k s were a c t u a l l y samples w i t h i n the l o c a t i o n and the f e r t i l i z e r t r e a t m e n t s . Age t r e a t m e n t s were young and o l d ; s i t e s r e v e g e t a t e d b e f o r e and a f t e r 1976, r e s p e c t i v e l y . L o c a t i o n t r e a t m e n t s were two s i t e s r e v e g e t a t e d i n two d i f f e r e n t y e a r s w i t h i n t h e young (1978 and 1977) and t h e o l d (1975 and 1974) s i t e s . F e r t i l i z e r t r e a t m e n t s were f e r t i l i z e d and u n f e r t i l i z e d . The 24 b l o c k s were sampled on two d a t e s . H a l f o f each one o f the f o u r p l o t s was p r o t e c t e d from a e r i a l f e r t i l i z e r a p p l i c a t i o n by s p r e a d i n g p l a s t i c s h e e t i n g d u r i n g t h e f e r t i l i z e r o p e r a t i o n s on June 17, 1980. A c t u a l amounts o f t h e f e r t i l i z e r a p p l i e d by h e l i c o p t e r were e s t i m a t e d by t h e d i s t r i b u t i o n o f m a t e r i a l i n 30 j a r s (10 per p l o t ) p l a c e d on t h e 1975, 1977 and 1978 r e c l a i m e d a r e a s . The j a r s were. 10 cm i n d i a m e t e r and 21 cm deep w i t h sponge a t the bottom t o p r e v e n t t h e f e r t i l i z e r r e b o u n d i n g from the j a r s on i m pact. A c c o r d i n g t o t h i s e s t i m a t e e x t r a 13-16-10 f e r t i l i z e r a t 150/kg/ha was a p p l i e d by hand on June 20, 1980 t o t h e p l o t s on a r e a s r e c l a i m e d i n 1977 and 1978 t o make the f e r t i l i z e r t r e a t -ment as u n i f o r m as p o s s i b l e . The p l o t s on t h e a r e a r e c l a i m e d i n 1974 were a l s o f e r t i l i z e d on June 20, 1980 by hand a t 150 kg/ha because t h i s a r e a was not a e r i a l l y f e r t i l i z e d . M aintenance f e r t i l i z e r had been a p p l i e d t o t h e s e a r e a s a t 150 kg/ha/yr i n t h e p r e c e d i n g y e a r s . Aboveground p l a n t samples were c o l l e c t e d , from a 28 cm 2 r a d i u s c i r c l e (0.25 m ) , t h e n t h e a r e a w i t h i n t h e c i r c l e was e x c a v a t e d t o 10 cm f o r belowground p l a n t samples. The below-ground samples were washed and o v e r - d r i e d t o o b t a i n d r y m a t t e r k7 w e i g h t s . S o i l samples were c o l l e c t e d t o 10 cm d e pth a l o n g t h e edge o f t h e c i r c l e a f t e r belowground s a m p l i n g . S o i l and p l a n t s a m p l i n g were r e p e a t e d : once b e f o r e f e r t i l i z a t i o n (May 28 -June 6, 1980), and a g a i n a f t e r f e r t i l i z a t i o n ( J u l y 15-22, 1980). The s o i l samples were a n a l y z e d f o r pH, phosphorus, n i t r a t e and ammonium t o s t u d y t h e e f f e c t s o f t h e s e s o i l f a c t o r s on t h e v e g e t a t i o n changes ( d e t a i l s o f s o i l a n a l y s e s have been des-c r i b e d i n S e c t i o n 4.2.2). 4.4.2 N a t i v e legumes Seeds o f two n a t i v e legume s p e c i e s , A s t r a g a l u s a l p i n u s and L u p i n u s s e r i c e u s were c o l l e c t e d on the s o u t h - f a c i n g s l o p e a d j a c e n t t o t h e s t u d y a r e a i n August, 197 9. The seeds were the n p l a n t e d 1-2 cm deep a t 5 s e e d s / h o l e d u r i n g August 16-20, 1979. The s i x h o l e s per t r e a t m e n t were p l a c e d on a 1 x 1 m p l o t , each h o l e 20 o r 40 cm a p a r t . G e r m i n a t i o n and s u r v i v a l were r e c o r d e d d u r i n g the summer o f 1980. W i l d l i n g s and g r e e n -house-grown s e e d l i n g s o f t h e two legume s p e c i e s were a l s o t r a n s p l a n t e d d u r i n g August 16-20, 1979, and on May 23, 1980, r e s p e c t i v e l y . The s i x s e e d l i n g s per t r e a t m e n t were p l a c e d i n t h e same manner as d e s c r i b e d above. The o v e r a l l l a y o u t i s shown i n F i g u r e 5.43. 4.4.3 Open system a c e t y l e n e r e d u c t i o n assay The a c e t y l e n e r e d u c t i o n a s s a y has been a p p l i e d e x t e n -s i v e l y i n e v a l u a t i n g n i t r o g e n f i x a t i o n a c t i v i t y (Hardy e t a l . , 1973). The c l o s e d system a c e t y l e n e r e d u c t i o n assay u s u a l l y i n v o l v e s d e s t r u c t i v e s a m p l i n g u n l e s s the p l a n t m a t e r i a l s can 48 be p l a c e d i n a c l o s e d system w i t h o u t b e i n g u p r o o t e d . Under f i e l d c o n d i t i o n s where p l a n t m a t e r i a l s may be e a s i l y u p l i f t e d w i t h o u t s i g n i f i c a n t l o s s o f r o o t s o r n o d u l e s t h i s c l o s e d system can be e f f e c t i v e l y a p p l i e d . However, t h i s . i s not always p o s s i b l e i n e s t a b l i s h e d sods o r when c o a r s e fragments ( >2 mm) compose 70% o f a s o i l as i n the case o f the c o a l mine s p o i l o f t h i s s t u d y . In an attempt t o overcome t h e s e d i s a d v a n t a g e s an "open system" a c e t y l e n e r e d u c t i o n a s s a y was d e v e l o p e d . The r a t i o n a l e of t h e open system i s t h a t the a c e t y l e n e c o n c e n t r a t i o n r e l a t i v e t o a i r i s e x p e c t e d t o d e c r e a s e i n a s h o r t time span because o f a c e t y l e n e d i f f u s i o n i n t o s u r r o u n d i n g a i r . N o n e t h e l e s s , the r a t i o o f a c e t y l e n e and e t h y l e n e i n t h e open system s h o u l d remain t h e same as t h a t i n a c l o s e d system i f a c e t y l e n e o f d i f f e r e n t c o n c e n t r a t i o n r e l a t i v e t o a i r can be reduced i n t o e t h y l e n e a t t h e same r a t i o . I n a p r e l i m i n a r y l a b o r a t o r y i n v e s t i g a t i o n a s e r i e s o f aluminum tubes ( o u t s i d e d i a m e t e r 13 mm, i n s i d e 9 mm) were i n s t a l l e d i n the c o a l s p o i l as shown i n F i g u r e 4.3. The tubes i n c l u d e d an a c e t y l e n e i n j e c t i o n tube (No. 1 ) , an e t h y l e n e i n j e c t i o n tube (No. 2 ) , and s a m p l i n g tubes (No. 3-10). The e t h y l e n e i n j e c t i o n tube a c t e d as a s i m u l a t e d n i t r o g e n - f i x i n g p l a n t p r o d u c i n g t h e r e d u c t i o n p r o d u c t , e t h y l e n e . I n i t i a l l y , 250 ml o f a c e t y l e n e was i n j e c t e d i n t o tube No. 1. Immediately a f t e r a c e t y l e n e was d e t e c t e d i n tube No. 2, 50 ml o f 100 ppm e t h y l e n e was s i m i l a r l y i n j e c t e d i n t o tube No. 2. Gas samples (1 ml) were c o l l e c t e d by s y r i n g e from tubes No. 3-10 a t s i d e v i e w F i g u r e 4.3 A p r e l i m i n a r y t e s t of aluminum tubes for an open system ace ty lene r e d u c t i o n assay. (a) The o r i e n t a t i o n of ten aluminum tubes i n s t a l l e d i n a c o a l s p o i l (b) D e t a i l s of an aluminum tube . The tubes c o n s i s t e d o f : No.1 ace ty lene i n j e c t i o n tube ; No.2 e thy lene i n j e c t i o n tube; and No.3-10 sampling tubes . The l e n g t h and hole d iameters a r e : No.1 30 cm, 2mm; No.2 20 cm, 2 mm; No.3-4 30 cm, 5 mm; No.5-6 25 cm, 5 mm; No.7-8 30 cm, 2 mm; and No.9-10 25 cm, 2 mm. 50 d i f f e r e n t time inter v a l s and analyzed by gas chromatography. On the basis of t h i s laboratory investigation, two units of aluminum tubes were developed. Each unit consisted of three aluminum tubes; one acetylene i n j e c t i o n , and two sampling tubes as shown below. unit. . . tube tube length (cm) hole diameter (mm) i n j e c t i o n 30 2 1 sampling 30 5 sampling 2 5 2 i n j e c t i o n 30 2 2 sampling 25 5 sampling 25 5 These units were tested on T r i f o l i u m sp. and Lupinus sp. growing i n the f i e l d on the University of B.C. campus on March 24, 1981. Tubes within a unit were placed 20 or 15 cm deep around plants and equidistant (10 cm) from each other. The top 10 cm of a l l tubes was above the ground l e v e l . A round c h i s e l (approximately 13 mm diameter) was at f i r s t driven into the ground to make a hole for aluminum tube i n s t a l l a t i o n . Acetylene was injected with a polyethylene bottle (250 ml) f i l l e d with acetylene. Gas samples were colle c t e d from the sampling tubes at d i f f e r e n t time intervals using evacuated tubes and analyzed by gas chromatography. The f i n a l unit developed for f i e l d use consisted of three aluminum tubes, one i n j e c t i o n and two i d e n t i c a l sampling tubes (Figure 4.4). A t o t a l of 101 units were i n s t a l l e d at the study s i t e , 72 on the four test p l o t s , 24 adjacent to the test p l o t s , and 5 i n the nearby subalpine forest. For compari-F i g u r e 4.4 Open system f i e l d a c e t y l e n e r e d u c t i o n a s s a y . The u n i t c o n s i s t s of t h r e e aluminum t u b e s : one ( C j H 2 ) i n j e c t i o n tube and two s a m p l i n g t u b e s . (a) Top view showing placement of the u n i t of t h r e e t u b e s . (b) D e t a i l s of s a m p l i n g and i n j e c t i o n t u b e s . 52 son c l o s e d system sampling was a l s o conducted on those p l a n t s of the 24 u n i t s adjacent to but outside the t e s t p l o t s and two of the 5 u n i t s i n the subalpine f o r e s t . P l a n t s were uprooted immediately a f t e r the open system in c u b a t i o n and put i n t o a i r - t i g h t 1.5 l i t e r c ontainers equipped w i t h a gas-sampling serum stopper and a gas i n j e c t i o n hole where a 250 ml polyethylene b o t t l e f i l l e d w i t h acetylene was f i t t e d . 53 5. RESULTS AND DISCUSSION 5.1 Weather d a t a Data from N a t a l Harmer Ridge weather s t a t i o n (Table 3.1) i n d i c a t e d t h a t the a n n u a l t o t a l p r e c i p i t a t i o n f o r 1980 (80.6 cm) was comparable t o t h a t d u r i n g the p e r i o d from 1971 t o 1974 (87.2) cm), as was the t o t a l p r e c i p i t a t i o n from May t o August: 20.3 and 19.8 cm, r e s p e c t i v e l y . Temperature d a t a f o r 1971-1974 and 1980 a l s o showed s i m i l a r t r e n d s , w i t h s l i g h t v a r i a t i o n s i n t h e months o f May and August (3.7°C h i g h e r i n May, and 6.3°C lower i n August, 1980 compared t o t h o s e of 1971-1974). T h i s suggested t h a t the growing season o f 1980 s t a r t e d somewhat e a r l i e r but a l s o ended e a r l i e r t h a n would have been p r e d i c t e d from th e l o n g e r term d a t a . Independent d a t a c o l l e c t e d from the s t u d y a r e a ( F i g u r e 5.1) showed t h a t t h e t o t a l p r e c i p i t a t i o n d u r i n g June t o August, 1980 was 15.5 cm, and s i m i l a r t o t h a t o f the N a t a l Harmer Ridge weather s t a t i o n d u r i n g t h e same p e r i o d (13.4 cm). However, much o f t h e p r e c i p i t a t i o n o c c u r r e d i n June (44%) and l i t t l e i n J u l y 1980 ( 2 0 % ) , w h i l e t h a t o f t h e N a t a l Harmer Ridge weather s t a t i o n was more e v e n l y d i s t r i b u t e d . R e l a t i v e h u m i d i t y d a t a showed t h a t d u r i n g much o f the p e r i o d maximum-r e l a t i v e h u m i d i t y was c l o s e t o 95% e x c e p t on. J u l y 7 (64%) and 28 ( 8 0 % ) , and t h e minimum r e l a t i v e h u m i d i t y g r a d u a l l y i n c r e a s e d from 10% t o a p p r o x i m a t e l y 35% d u r i n g the measurement p e r i o d ( F i g u r e 5.2). 5k F i g u r e 5.1 A i r temp e r a t u r e and p r e c i p i t a t i o n r e c o r d e d at the 1974 r e c l a i m e d a r e a ; summer 1980. • minimum weekly t e m p e r a t u r e X average weekly t e m p e r a t u r e 0 maximum weekly temperature 1 weekly p r e c i p i t a t i o n R H . 0 ' I I I 1 i 1 i i 1 i ' •— J 1 6 J L l J L U J L 2 S A l l A S S F i g u r e 5.2 R e l a t i v e h u m i d i t y measurements r e c o r d e d weekly a t the 1974 r e c l a i m e d a r e a ; summer of 1980. • minimum r e l a t i v e h u m i d i t y o maximum r e l a t i v e h u m i d i t y 55 S o i l minimum and maximum tem p e r a t u r e s (10 cm depth) are shown i n F i g u r e 5.3. Minimum te m p e r a t u r e s o f t h e s u b a l p i n e f o r e s t were c o n s i s t e n t l y lower t h a n t h o s e o f t h e r e v e g e t a t e d a r e a , w h i l e maximum te m p e r a t u r e s o f the f o r e s t were s l i g h t l y h i g h e r d u r i n g the e a r l y season. T h e r e f o r e t h e weekly tempera-t u r e extremes under the f o r e s t canopy were g r e a t e r than t h o s e o f t he r e v e g e t a t e d a r e a . The lower minimum temperature o f s u b a l p i n e s o i l was p r o b a b l y caused by the i n s u l a t i n g e f f e c t o f t he f o r e s t canopy where w i n t e r snow p e r s i s t e d f o r l o n g e r p e r i o d s t h a n i n t h e r e v e g e t a t e d a r e a . T h i s r e s u l t was c o n s i s -t e n t w i t h t h e f i n d i n g s o f B a l l a r d (1972), who r e p o r t e d t h a t d u r i n g t h e p e r i o d o f J u l y t o September s o i l t e m p e r a t u r e s (60 cm depth) under t r e e clumps were c o n s i s t e n t l y lower t h a n t h o s e o f bare ground o r shrub c o v e r i n t h e w e s t e r n Cascade Mountains o f B.C. 5.2 F i e l d s u r v e y 5.2.1 N a t u r a l s u b a l p i n e f o r e s t 5.2.1.1 V e g e t a t i o n A v e g e t a t i o n s u r v e y o f t h e s u b a l p i n e f o r e s t on the n o r t h w e s t - f a c i n g s l o p e a d j a c e n t t o t h e st u d y a r e a ( F i g u r e 5.4a) r e v e a l e d a t r e e component co m p r i s e d o f A b i e s l a s i o c a r p a , P i n u s  a l b i c a u l i s , P i c e a e n g e l m a n n i i and P i n u s c o n t o r t a v a r . l a t i f o l i a . Most o f t h e s e t r e e s were f a i r l y mature and formed a dense canopy. A b i e s l a s i o c a r p a , P i n u s a l b i c a u l i s and P i c e a  engelmanni a re i n d i c a t o r p l a n t s o f the Engelmann s p r u c e -°c 20 H J 1 6 J L l J L 1 4 J L 2 8 A l l A 25 F i g u r e 5.3 Minimum and maximum s o i l t e m p e r a t u r e s r e c o r d e d weekly f o r the 1974 r e c l a i m e d a r e a and the a d j a c e n t s u b a l p i n e f o r e s t ; summer of 1980. • minimum, s u b a l p i n e f o r e s t o maximum, s u b a l p i n e f o r e s t • minimum, 1974 a r e a • maximum, 1974 a r e a 57 Figure 5.4 Subalpine f o r e s t adjacent to study area. (a) S u b a l p i n e f o r e s t . (b) N a t i v e p l a n t s on open south-facing s l o p e . 58 S u b a l p i n e f i r (ESSF) B i o g e o c l i m a t i c zone ( K r a j i n a , 1965). Two o t h e r t r e e s p e c i e s , L a r i x l y a l l i i and Tsuga m e r t e n s i a n a w h i c h a r e a l s o i n d i c a t o r p l a n t s o f t h i s zone were not found i n t h e s u r v e y a r e a . Open s u b a l p i n e f o r e s t p a r k l a n d , one o f the t h r e e communities r e c o g n i z e d by D i c k (1979) w i t h i n the ESSF Zone, c o n s i s t e d o f t h r e e o f the above f o u r s p e c i e s found i n t he s u r v e y ( e x c l u d i n g P i c e a e n g e l m a n n i i ) . The u n d e r s t o r y was dominated by Rhododendron a l b i f l o r u m , M e n z i e s i a f e r r u g i n e a , V a c c i n i u m membranaceum, and V. scoparium. A s m a l l open s o u t h - f a c i n g s l o p e had s c a t t e r e d t r e e s w i t h an u n d e r s t o r y dominated by low-growing s p e c i e s w h i c h were not p r e s e n t under t h e c l o s e d canopy o f the s u b a l p i n e f o r e s t ( F i g u r e 5.4b). The v i s u a l s u r v e y showed d r a m a t i c v e g e t a t i o n changes a c c o r d i n g t o a s p e c t even w i t h i n the l i m i t e d s u r v e y a r e a . T h i s o b s e r v a t i o n suggested t h a t a s p e c t might be one o f t h e i m p o r t a n t f a c t o r s i n e s t a b l i s h i n g r e v e g e t a t i o n s t r a t e g i e s f o r a p a r t i c u -l a r s i t e . ' A complete s p e c i e s l i s t f o r t h e survey a r e a i s shown i n Table 5.1. 5.2.1.2 S o i l and u n d e r s t o r y phytomass S o i l development d i f f e r e d c o n s i d e r a b l y w i t h i n s h o r t d i s t a n c e s (5-10 m) i n the s u b - a l p i n e f o r e s t . On r e l a t i v e l y l e v e l ground, d i s t i n c t Ah and Ae h o r i z o n s were p r e s e n t . How-e v e r , on s l o p e s n e i t h e r Ah nor Ae h o r i z o n s were d e t e c t e d and s o i l was much s h a l l o w e r t h a n t h a t on the l e v e l ground. A v a i l a b l e s o i l phosphorus, ammonium and n i t r a t e were c o n s i s t e n t between samples c o l l e c t e d on d i f f e r e n t d a t e s , r a n g i n g from 18.3 59 Table 5.1 L i s t o f p l a n t s p e c i e s i n an u n d i s t u r b e d s u b a l p i n e f o r e s t a d j a c e n t t o t h e stu d y area- 1. S p e c i e s ^ Trees A b i e s l a s i o c a r p a (Hook.) N u t t . P i c e a e n g e l m a n n i i P a r r y P i n u s a l b i c a u l i s Engelm. P i n u s c o n t o r t a v a r . l a t i f o l i a Engelm. Shrubs J u n i p e r u s communis L. M e n z i e s i a f e r r u g i n e a Smith Rhododendron a l b i f l o r u m Hook. V a c c i n i u m membranaceum Dougl. V a c c i n i u m s c o p a r i u m L e i b e r g Forbs Common name S u b a l p i n e f i r Engelmann spruce White bark p i n e Lodgepole p i n e Common j u n i p e r F o o l ' s h u c k l e b e r r y White rhododendron T h i n - l e a v e d b l u e b e r r y G r o u s e b e r r y A c h i l l e a m i l l e f o l i u m L. A n a p h a l i s m a r g a r i t a c e a (L.) B. & H. A n t e n n a r i a m i c r o p h y l l a Rydb. A n t e n n a r i a sp. A q u i l e g i a f I a v e s c e n s Wats. A r a b i s l y a l l i i Wats. A r n i c a c o r d i f o l i a Hook. A r n i c a sp. A s t r a g a l u s a l p i n u s L. C a s t i l l e j a sp. C i r s i u m hookerianum N u t t . C o l l i n s i a p a r v i f l o r a L i n d l . E r i g e r o n compositus P u r s h E r i g e r o n p e r e g r i n u s (Pursh) Greene E r y t h r o n i u m g r a n d i f l o r u m P u r s h H i e r a c i u m sp. Lupin u s s e r i c e u s P u r s h P e d i c u l a r i s b r a c t e o s a Benth. P e d i c u l a r i s sp. Penstemon p r o c e r u s Dougl. V eratrum v i r i d e A i t . V i o l a sp. Yarrow P e a r l y - e v e r l a s t i n g Rosy p u s s y - t o e s P u s s y - t o e s Y e l l o w columbine L y a l l ' s r o c k c r e s s H e a r t - l e a f a r n i c a A r n i c a A l p i n e m i l k - v e t c h P a i n t b r u s h White t h i s t l e B l u e - e y e d mary C u t - l e a v e d d a i s y S u b a l p i n e d a i s y P a l e f a w n - l i l y Hawkweed S i l k y l u p i n e B r a c t e d l o u s e w o r t Lousewort S m a l l - f l o w e r e d penstemon Green f a l s e h e l l e b o r e V i o l e t Nomenclature a f t e r H i t c h c o c k and C r o n q u i s t (1973). Grass s p e c i e s were p r e s e n t on o t h e r a r e a s nearby t h e sub-a l p i n e f o r e s t f o r w h i c h t h i s l i s t o f p l a n t s p e c i e s was made. 60 t o 21.7 ppm f o r phosphorus, and 5.1 t o 2.6 ppm f o r ammonium and n i t r a t e combined. S i m i l a r l y , s o i l was a c i d i c on b o t h l o c a t i o n s w i t h pH r a n g i n g from 4.6 t o 4.7. The phytomass breakdown o f u n d e r s t o r y v e g e t a t i o n showed 2 t h a t i n t h e f i r s t s a m p l i n g aboveground biomass was 64.3 g/m 2 o f which Rhododendron a l b i f l o r u m accounted f o r 60.4 g/m and 2 i n t h e second s a m p l i n g 8.4 g/m : t h e d e t r i t u s 86 9.7 and 2 9.2 2 g/m , r e s p e c t i v e l y . On b o t h s a m p l i n g s V a c c i n i u m s c o p a r i u m , E r y t h r o n i u m g r a n d i f l o r u m and V i o l a sp. were p r e s e n t (Table 5.2). 5.2.2 R e c l a i m e d a r e a s 5.2.2.1 S o i l F a c t o r s S p o i l v a r i a b i l i t y In e v a l u a t i n g the measurements o f s o i l parameters on the r e c l a i m e d s i t e s , the p o t e n t i a l i n f l u e n c e o f i n h e r e n t s p o i l v a r i a b i l i t y cannot be o v e r s t r e s s e d . S p o i l m a t e r i a l s were d e r i v e d from v a r i o u s s t r a t i g r a p h i c l a y e r s i n c l u d i n g c o n g l o -merates, c a l c a r e o u s and carbonaceous s h a l e s , sandstones and low grade c o a l s . These g e o l o g i c a l m a t e r i a l s d i f f e r i n t h e i r r e sponse t o w e a t h e r i n g , c o n t r i b u t i n g a t l e a s t i n p a r t t o v a r i a b i l i t y i n t e x t u r a l d i s t r i b u t i o n . N o n - s e l e c t i v e m i x i n g and placement o f s p o i l s on t h e r e c l a i m e d a r e a s r e p r e s e n t a d d i t i o n a l f a c t o r s c o n t r i b u t i n g t o t h e o v e r a l l h e t e r o g e n e i t y o f the s u b s t r a t e f o r p l a n t growth on t h e s e s i t e s . F i g u r e s 5.5 and 5.6 i l l u s t r a t e t h e p r o d u c t i o n o f t h e o v e r b u r d e n and the o b v i o u s v i s u a l h e t e r o g e n e i t y o f t h e source m a t e r i a l on t h e 61 T a b l e 5.2 pH, phosphorus, ammonium and n i t r a t e o f s u b a l p i n e f o r e s t s o i l (0-10 cm d e p t h ) , and phytomass f r a c t i o n s . s a m p l i n g date s o i l and phytomass June 6, 1980 J u l y 22, 1980 S o i l f a c t o r s pH 4 , .6 + 0 , .3 4 , .7 + 0, .3 P (ppm) 18, .3 + 9, .7 21, .7 + 16 , .9 NH 4+ (ppm) 2 , .6 + 1, .2 0 , .9 + 0 , .8 NO3- (ppm) 2, .5 + 1, .4 1, .7 + 0 , .3 N H 4 + + NC>3~ (ppm) 5, .1 + 0 , .5 2 , .6 + 0 , .7 lytomass f r a c t i o n s (g/m^) aboveground biomass by s p e c i e s V a c c i n i u m scoparium 2, .8 + 2 , .2 6 , .3 + 5, .8 E r y t h r o n i u m g r a n d i f l o r u m 0 , .1 + 0 , .2 "I 0 , .1 + 0 , .1 V i o l a sp. (0, .02 + 0 , . 0 3 ) 1 0 , .1 + 0 , .1 Rhododendron a l b i f l o r u m 60, .4 + 53, .8 0 , .0 + 0, .0 V a c c i n i u m membranaceum 1. .0 + 1, .9 0 , .0 + 0 , .0 A r n i c a c o r d i f o l i a 0, .0 ± 0 , .0 0 , .8 + 0, .4 A r n i c a sp. (0, .03 + 0 , .05) 0 , .0 + 0 , .0 P e d i c u l a r i s sp. (0, .02 + 0 , .03) 0 , .0 + 0 , .0 u n i d e n t i f i e d 0, .0 + 0 , .0 1, .1 + 1, .3 r o o t ( i n c l u d i n g some o f o v e r s t o r i e s ) 76, .4 + 24 , .5 50. .3 + 14 , .5 d e t r i t u s 869, .7 + 267, .7 29. .2 + 18, .2 aboveground biomass 64 . 3 + 58. .1 8, .4 + 7, .7 t o t a l biomass 140. .7 + 82 , .6 58, .7 + 22. .2 t o t a l phytomass 1010 , .4 + 350. .3 87. .9 + 40. .4 F i g u r e s i n p a r e n t h e s e s a r e not i n c l u d e d i n c a l c u l a t i n g above-ground biomass. The f i g u r e s a r e means and s t a n d a r d d e v i a t i o n s o f t h r e e o b s e r v a t i o n s . The s u b a l p i n e f o r e s t was l o c a t e d a d j a c e n t t o the s t u d y a r e a . F i g u r e s o f phytomass f r a c t i o n s were not always s i g n i f i c a n t t o one d e c i m a l s , e.g. d e t e r i t u s c o u l d o n l y be h a n d - c o l l e c t e d upto a c e r t a i n a c c u r a c y . The same a p p l i e d t o the o t h e r t a b l e s i n S e c t i o n 5.2 and 5.4. 62 F i g u r e 5 .5 General view of mining p i t and b l a s t i n g . (a) Mining p i t (b) B l a s t i n g . The overburden i s b l a s t e d b e f o r e i t s r e m o v a l 63 F i g u r e 5.6 R a p i d l y d i s i n t e g r a t i n g s h a l e s found on the 1977 s i t e . (Photographed i n the summer of 1979). Note the m i x t u r e and i n t e g r a t i o n of v a r i o u s s h a l e s . 64 reclaimed s i t e s . The blackish p i l e s evident in Figure 5.14 are carbonaceous shales containing inert carbon and nitrogen. These elements may play a more important role i n the chemical properties of the s p o i l as the material weathers (Berg, 1975 and Power et a l . , 1974). In view of the limited information available on the influence of t h i s apparent heterogeneity on the physicochemical properties of the reclaimed s p o i l s , the reader i s cautioned to view the s o i l s data i n the context of t h i s inherent v a r i a b i l i t y and the limited sampling which was undertaken during the course of t h i s study. S o i l water Moisture percentages of the fine fragment (<2 mm) fr a c t i o n of the s o i l showed that the subalpine forest had much higher moisture levels (19 - 32%) than the s o i l s of the reclaimed area (2 - 13%) throughout June to August, 1980 (Figure 5.7). Within the reclaimed areas the differences were much smaller than those between the forest and reclaimed s i t e s . However, the area reclaimed i n 1974 showed consistently higher moisture percentages than the others. This difference within the reclaimed areas was probably caused by factors such as s o i l texture, s o i l organic matter content, vegetation (via t r a n s p i r a t i o n ) , location or i t s surroundings which might have affected snow melt or trapping, wind speed, ground water seepage and p r e c i p i t a t i o n . 65 s oi I moisture 0 I I > 1 1 1 1 ' i 1 i i J 16 J L l JL14 JL 28 A l l A 2 5 Figure 5.7 Moisture percentages of s o i l f i n e fragments (10 cm depth, < 2mm) from reclaimed areas and subalpine f o r e s t ; summer of 1980. o subalpine f o r e s t a 1974 area A 1975 area x 1977 area • 1978 area Each point i s the mean of three observations. 66 When s o i l m o i s t u r e was computed f o r the combined c o a r s e ( >2 mm) and f i n e fragment f r a c t i o n s (based on t h e i r r e l a t i v e p r o p o r t i o n o f the s o i l ) , t h e d i f f e r e n c e between the f o r e s t and r e c l a i m e d s i t e s was enhanced. T h i s e f f e c t was a consequence o f t h e l a r g e r p e r c e n t a g e o f c o a r s e fragments p r e s e n t i n s o i l s from t h e r e c l a i m e d a r e a s t h a n t h o s e o f t h e f o r e s t (Table 5.3). The c o m p u t a t i o n was based on t h e assumption t h a t the c o a r s e fragment f r a c t i o n had z e r o m o i s t u r e a l t h o u g h t h i s was not always a p p r o p r i a t e . Coarse fragments o f t h e f o r e s t s o i l s c o n s i s t e d m a i n l y o f o r g a n i c m a t t e r ( d e t r i t u s ) w h i l e t h o s e o f t h e r e c l a i m e d s o i l s were composed o f c o n s o l i d a t e d s h a l e s w i t h l i t t l e m o i s t u r e . T h e r e f o r e m o i s t u r e p e r c e n t a g e s f o r t h e whole s o i l f o r t h e f o r e s t were p r o b a b l y h i g h e r than t h e 9.9% e s t i m a t e s . A c c o r d i n g t o t h i s computed m o i s t u r e l e v e l , the f o r e s t s o i l h e l d a t l e a s t 5 t o 10 t i m e s more water t h a n t h e r e c l a i m e d a r e a s . S i m i l a r l y , the a r e a r e c l a i m e d i n 1974 h e l d t w i c e as much water as the o t h e r r e c l a i m e d a r e a s . The h i g h e r m o i s t u r e l e v e l i n f o r e s t s o i l s may be caused, i n p a r t , by the l a r g e r p e r c e n t a g e s o f f i n e f r a g m e n t s , but i t may be r e l a t e d a l s o t o d e l a y e d snow m e l t under the f o r e s t canopy and reduced e v a p o r a t i o n as a consequence o f s h e l t e r from wind and sun. Water t e n s i o n S o i l m o i s t u r e p e r c e n t a g e s per se a r e not a p p r o p r i a t e measurements t o p r e d i c t water a v a i l a b i l i t y t o p l a n t s , because the t e x t u r e s o f t h e s e s o i l s are d i f f e r e n t (Table 5.3). Water t e n s i o n , w h i c h i s more d i r e c t l y r e l a t e d t o ease o f water 67 (°) and te x t u r e of subalpine f o r e s t and Table 5.3 S o i l moisture U) and t e x t u reclaimed s o i l s . s i t e s o i l moisture (%) whole o m m 2 c o i l 3 <2mm R e c i a i r n e l a r e a s <ca^2mm sojU 1978 1977 1975 1974 Subalpine f o r e s t 7.9 5.7 6.3 9.4 24.5 14.5± 2.4 20.7± 2.6 0 16.5± 2.0 2.2 23.4± 9.2 1 . 1 1.2 1 c o i l t e x t u r e (%)' 2-4 mm 10.8± 1.7 11.4+ 0.8 8.7± 2.3 11 .5± 0.6 >4mm 74.7± 3.4 67. 9± 2.4 74.8± 2.7 65.1± 9.1 9.9 40.4±15.0 27.0125.4 32.6112.7 1. Means and standard d e v i a t i o n s of four samples except 1974 area which had three samples. 2. Means of 12 measurements taken during the three month pe r i o d (June to August, 1980). 3. Computed as f o l l o w s : f r a c t i o n of s o i l (< 2mm) m u l t i p l i e d by moisture percentage of s o i l (< ca. 2mm). Example of subalpine s o i l : 0.404 x 24.5 = 9.9%. 68 uptake by p l a n t s , p r o v i d e s a more a c c u r a t e assessment o f s o i l w ater a v a i l a b i l i t y t o p l a n t s . Water t e n s i o n o f t h e s u b a l p i n e f o r e s t s o i l was found t o i n c r e a s e g r a d u a l l y ( i . e . l e s s water a v a i l a b l e t o p l a n t s ) from 9 k i l o p a s c a l s on June 9 t o 4 9 k i l o p a s c a l s on J u l y 29, 1980, th e n d e c r e a s e t o 30 k i l o p a s c a l s i n August ( F i g u r e 5.8). S o i l s o f the r e v e g e t a t e d a r e a s changed more d r a s t i c a l l y i n water t e n s i o n d u r i n g t h e same p e r i o d , and d u r i n g most o f J u l y water t e n s i o n was h i g h e r t h a n i n s o i l s o f t h e s u b a l p i n e f o r e s t . T h e r e f o r e , the p l a n t s on the r e v e g e t a t e d a r e a s were exposed t o g r e a t e r water s t r e s s d u r i n g t h e month o f J u l y t h a n t h o s e o f t h e f o r e s t . Water s t r e s s may be one o f t h e major f a c t o r s t h a t l i m i t s p l a n t growth and seed p r o d u c t i o n on the r e c l a i m e d a r e a s s i n c e i t was apparent t h a t low m o i s t u r e c o n d i t i o n s c o i n c i d e d w i t h the p e r i o d when most p l a n t s were s t i l l i n t h e e a r l y s t a g e s o f f l o w e r i n g . I n s p i t e o f t h e f a c t t h a t the a r e a r e c l a i m e d i n 1974 showed h i g h e r s o i l m o i s t u r e t h a n the o t h e r r e c l a i m e d s i t e s , w ater t e n s i o n o f t h i s a r e a was h i g h e r t h a n t h a t o f t h e more r e c e n t 1977 p l a n t i n g . T h i s may be caused by the t r a n s p i r a t i o n o f p l a n t s s i n c e t h e former a r e a s u p p o r t e d more l i v e p l a n t m a t e r i a l i n terms o f d r y w e i g h t t h a n t h e l a t t e r ( F i g u r e 5.10). S o i l t e x t u r e The f i n e fragment f r a c t i o n (< 2 mm) o f t h e s u b a l p i n e s o i l was a l m o s t double t h a t o f t h e r e c l a i m e d a r e a s , 40.4% v s . 14.5 - 23.4%. When the c o a r s e fragment was f u r t h e r d i v i d e d 69 F i g u r e 5.8 Water t e n s i o n (10 cm depth) of the rec la imed areas and suba lp ine f o r e s t , summer of 1980. o suba lp ine f o r e s t D 1974 area X 1977 area 70 i n t o two c a t e g o r i e s , <4 and >4 mm, the 2 - 4 mm f r a c t i o n of the f o r e s t s o i l again represented more than double t h a t of the reclaimed areas (Table 5.3). Moreover, the coarse fragments of f o r e s t s o i l c o n s i s t e d mainly of organic matter ( d e t r i t u s ) while p r a c t i c a l l y a l l of the coarse fragment f r a c t i o n of the reclaimed areas was co n s o l i d a t e d shales of various types. Therefore the f o r e s t s o i l was superior i n textur e f o r p l a n t growth when compared to those of the reclaimed areas. Texture d i f f e r e n c e s between the f o r e s t and reclaimed s i t e s apparently r e s u l t e d from both temporal and b i o l o g i c a l f a c t o r s . The primary bare areas upon which the f o r e s t developed were formed by past physiographic processes such as d e g l a c i a t i o n which have provided ample time f o r s o i l formation and p l a n t succession. Within the reclaimed areas, the 1974 area had only s l i g h t l y more f i n e fragments than the other areas. The s l i g h t d i f f e r e n c e s i n s o i l t e x t u r e between the reclaimed areas were understandable i n view of the small age d i f f e r e n c e between d i f f e r e n t s i t e s and i n s p i t e of the v a r i - : able g e o l o g i c a l o r i g i n s of s p o i l components described e a r l i e r . A large p o r t i o n (65 - 75%) of the s o i l s ( s p o i l s ) i s composed of coarse fragments w i t h a negative i n f l u e n c e on many f a c t o r s , e.g. s o i l n u t r i e n t a v a i l a b i l i t y . S o i l and p l a n t data c o l l e c t e d from t h i s study area should be evaluated i n the context of the heterogeneous t e x t u r a l d i s t r i b u t i o n . 71 S o i l reaction The s o i l reactions of the reclaimed areas (0 - 10 cm depth) were mainly near neutral and ranged from pH 6.3 to 8.1 (Table 5.4). The older s i t e s tended to be lower i n pH than the younger areas except the 1975 s i t e with a pH of 6.3 (measured i n 1980). Samples coll e c t e d i n 1979 gave s l i g h t l y higher pH values than those of 1980 except for the 1975 area. There were also some differences i n pH related to depth, those at 0 - 5 cm being s l i g h t l y lower than those at 5 - 10 cm depth (Table 5.5). The pH values of the same area reported by Kaiser Resources Ltd. (1980) generally agreed with those recorded i n t h i s study. Company data s i m i l a r l y indicated that there was a trend toward lower pH values i n the older s i t e s . Based on t h i s evidence i t i s apparent that the pH of the spoils (soils) could be lowered i n a r e l a t i v e l y short period, i . e . 2 to 7 years. This may be related to calcium leaching or the annual maintenance f e r t i l i z e r (13-16-10) applications. A pH change over a short period i s possible i n a s o i l which has l i t t l e pH buffering capacity as i s l i k e l y to be the case i n s p o i l material. The s p o i l contains l i t t l e organic matter (excluding the i n e r t condensed form of naturally present organic matter). Rapid leaching of calcium during a short period has been reported by Riley (1973). The applied f e r t i l i z e r probably attributed to the lower pH (5.8, 0 - 5 cm) observed i n the 1975 reclamation area because of the heavy f e r t i l i z e r applica-t i o n (400 kg/ha) 52 days p r i o r to s o i l sampling. The f e r t i l i z e r 72 Table 5 4 pH, phosphorus, ammonium and n i t r a t e of the s o i l samples (0-V6 cm depth) c o l l e c t e d from the rec l a imed areas . reclaimed sampled pH P j f f i n ) N H ^ m ) NC^pm) 1978 1977 1 975 1974 1979 1 7.410.1 7.8 + 5.4 3.2 + 0.8 1980 2 8.1+0.5 4.3+1.4 0.210.2 1979 7.310.4 10.614.2 11.2+10.4 1980 7.610.2 4.912.9 4.31 6.2 1979 7.110.5 30.5+9.3 3 .7± 1.7 1980 6.310.1 18.317.3 4 . 8 i 6.2 1979 7.3+0.1 18.119.1 2 .7± 1.6 1980 7.510.4 7.715.2 0.41 0.6 1 1 .8114.8 0.31 0.8 8.51 7.8 0.61 1.1 1.11 2.8 1.11 1.0 0.81 0.8 0.71 0.8 N H 4 + + NQ3-(ppm) 14.9115.5 0.61 0.8 19.6114.2 4 . 9 i 7.1 4 .7± 3.0 5.91 6.9 3.41 2.1 1.11 1.2 1 . August 3-22, 1*979 2. August 7-8, 1980. The f i g u r e s are means and s tandard d e v i a t i o n s of 6 to 8 samples T a b l e 5 . 5 S o i l p H . p h o s p h o r u s , a m m o n i u m a n d n i t r a t e l e v e l s o f s o d i f f e r e n t r e c l a i m e d a r e a s a t 0 - 5 a n d 5 - 1 0 c m d e p t h s . 1 9 7 8 y e a r r e v e g e t a t e d 1 9 7 7 1 9 7 5 1 9 7 4 s o i l f a c t o r s 0 - 5 c m 5 - 1 0 c m 0 - 5 c m 5 - 1 0 c m o--5 c m 5 - 1 0 c m 0 - 5 c m 5 - 1 0 c m p H 8 . 2 + 0 . 1 8 . 2 ± 0 . 2 7 . 5 ± 0 . 5 7 . 7 + 0 . 2 5 . 8+o. e 6 . 7 + 0 . 4 7 . . 1 + 0 . 4 7 . 4 + 0 . 4 P ( p p m ) 5 . 0 + 2 . 8 3 . 5 + 0 . 7 1 2 . 5 ± 9 . 2 2 . 5 ± 0 . 7 3 2 . . 0 + 8 . 5 5 . 5 ± 2 . 1 6 . 5 ± 0 . 7 1 . 0 ± 1 . 4 N H 4 * ( p p m ) 1 . 0 ± 0 . 9 0 . 1 + 0 . 1 0 . 4 + 0 . 5 2 0 . 1 ± 2 8 . 1 6 . 5 ± 5 . 3 0 . 7 ± 1 . 0 0 . 4 + 0 . . 5 0 . 7 ± 0 . . 3 N 0 3 ~ ( p p m ) 0 . 2 ± 0 . 3 1 . 2 ± 1 . 7 0 ± 0 2 . 3 + 2 . 5 2 . 5 ± 0 . 6 3 . 2 ± 4 . 5 2 . 6 + 2 . 5 0 . 4 ± 0 G N H 4 * + N 0 3 ~ ( p p m ) 1 . 2 ± 0 . 6 1 . 3 ± 1 . 8 0 . 4 + 0 . 5 2 2 . 3 ± 3 0 . 6 9 . 1 ± 5 . 9 3 . 9 + 3 . 5 3 . 0 ± 2 . 0 1 . 1 + 0 . 9 S a m p l e s w e r e c o l l e c t e d A u g u s t 7 - 8 . 1 9 8 0 . T h e f i g u r e s a r e m e a n s a n d s t a n d a r d d e v i a t i o n s o f t w o s a m p l e s . 7k c o n t a i n s n i t r o g e n i n t h e ammonium form which i s known t o a c i d i f y s o i l v i a the f o l l o w i n g r e a c t i o n (Buckman and Brady, 1972): N H 4 + + 2 0 2 > 2 H + + N0 3~ + H 20 Phosphorus Phosphorus l e v e l s on the r e c l a i m e d a r e a s v a r i e d w i d e l y , i n o l d e r a r e a s t e n d i n g t o be h i g h e r t h a n i n younger ones (Table 5.4). F r e s h s p o i l m a t e r i a l had phosphorus l e v e l s o f a p p r o x i -m a t e l y 4 ppm o r l e s s (Table 5.9). S i n c e a r a p i d i n c r e a s e o f phosphorus l e v e l s i n s l i g h t l y a l k a l i n e s o i l was u n l i k e l y , t h e ob s e r v e d v a r i a t i o n i n samples t a k e n i n 1979 was p r o b a b l y a consequence o f t h e v a r i a t i o n i n f e r t i l i z e r a p p l i c a t i o n between t h e a r e a s . I n s p i t e o f t h e wide v a r i a t i o n i n the amounts o f f e r t i l i z e r a p p l i e d i n 1980 i t i s r e a s o n a b l e t o assume t h a t t h e o l d e r a r e a had r e c e i v e d more t o t a l phosphorus d u r i n g the y e a r s a f t e r r e v e g e t a t i o n . T h i s assumption would s a t i s f a c t o r i l y e x p l a i n t h e g e n e r a l tendency o f h i g h e r phosphorus l e v e l s on the o l d e r s i t e s . /Another i n t e r e s t i n g d i s c o v e r y was t h a t t h e phosphorus l e v e l s a t t h e 0 - 5 cm were always h i g h e r t h a n t h o s e a t 5 - 10 cm de p t h t h r o u g h o u t t h e r e c l a i m e d a r e a s . A p p l i e d phosphorus appeared t o remain i n t h e upper s o i l p r o f i l e . Such a r e s u l t i s not unexpected i n view o f t h e known r e t e n t i o n o f phosphorus as c a l c i u m phosphate a t near n e u t r a l pH. The h i g h e r l e v e l o f the phosphorus i n t h e 0 - 5 cm depth c o u l d have s e r i o u s 75 i m p l i c a t i o n s i n p l a n t growth and e s t a b l i s h m e n t d u r i n g t h e summer months when t h e l i m i t e d s u p p l y o f a v a i l a b l e water t o the p l a n t s may encourage deeper p l a n t r o o t i n g i n such a way t h a t t h e phosphorus s u p p l y i n t h e upper s o i l may be a v a i l a b l e no l o n g e r t o t h e p l a n t s . The u n u s u a l l y h i g h phosphorus l e v e l (30.5 ppm a t 0 - 10 cm'depth, T a b l e 5.4) o f t h e 1975 r e v e g e t a t e d a r e a p r o b a b l y o r i g i n a t e d as a r e s u l t o f t h e heavy maintenance f e r t i l i z e r a p p l i c a t i o n . I n view o f the v a r i a b i l i t y o b s e r v e d (Table 5.14) i n t h e d i s t r i b u t i o n o f f e r t i l i z e r i n the 1980 a p p l i c a t i o n , i t would not be s u r p r i s i n g t o f i n d o t h e r a r e a s i n w h i c h t h e phosphorus l e v e l s were h i g h e r (or lower) t h a n might o t h e r w i s e have been p r e d i c t e d on the b a s i s o f t h e an n u a l maintenance f e r t i l i z e r program. 7Ammonium and n i t r a t e On t h e r e c l a i m e d a r e a s o f f o u r d i f f e r e n t ages, t h e r e were l a r g e v a r i a t i o n s i n ammonium and n i t r a t e l e v e l s , between and w i t h i n t h e s a m p l i n g y e a r s and between depths (0 - 5 and 5 - 1 0 cm) (Tables 5.4 and 5.5). Both ammonium and n i t r a t e l e v e l s were lower i n 1980 tha n i n t h e p r e v i o u s y e a r . T h i s v a r i a t i o n may be a consequence o f the a n n u a l e n v i r o n m e n t a l v a r i a t i o n , e.g. e a r l y summer p r e c i p i t a t i o n d i f f e r e n c e s between 1979 and 1980. The v a r i a t i o n found w i t h i n each o f t h e two s a m p l i n g y e a r s p r o b a b l y r e f l e c t e d d i f f e r e n c e s i n biomass and d i s t r i b u t i o n o f t h e a n n u a l maintenance f e r t i l i z e r . For i n s t a n c e , l e v e l s o f combined ammonium and n i t r a t e ( i n 1979) were lower on 1974 and 1975 areas (3.4 and 4.7 ppm, respec-. 76 t i ve l y ) than those on 1977 and 1978 areas (19.6 and 14.9 ppm, respect ive ly) (Table 5.4). This observation i s most ea s i l y explained with the higher uptakes of the nitrogen by the larger biomass on the former areas. It was also i n te res t ing to note that the ammonium l e v e l was extremely high (20.1 ppm) at 5 - 10 cm depth of the 1977 area compared to those of the other areas (Table 5.5). The ava i lab le data as wel l as observation of the s i t e d id not provide any r a t i o n a l explanation of th i s phenomenon. Further invest i gat ion would be necessary to define the precise causes of some of the va r i a t i on observed. However, the data provided some evidence of : (a) n i t r i f i c a t i o n on areas reclaimed in 1977 and 1978, because of the higher n i t ra te leve l s observed on these s i t e s . This agreed with the f ind ing of Reeder and Berg (1977) i n which n i t r i f i c a t i o n was found to occur in fresh spo i l s of Colorado, and (b) a general de f i c iency in ava i lab le nitrogen in s o i l s of the reclaimed areas. 5.2.2.2 Plant biomass Aboveground biomass and l i t t e r Aboveground biomass and l i t t e r were sampled in 197 9 and again in 1980 for s i tes revegetated from 1974 to 1978 (Figures 5.9 and 5.10). This procedure allowed c o l l e c t i o n of two sets of data on the vegetation and l i t t e r : each set provided a chronolog ica l sequence of four d i f f e r e n t ages, but d i f f e r e d in age by one year. 77 Figure 5.9 Area reclaimed i n 1974. (a) General s i t e view (b) T y p i c a l plant d i s t r i b u t i o n . The area i s w e l l covered by dense t a l l grasses which composed 62.0% of the t o t a l aboveground standing crop. The remaining 38.0% con s i s t e d of Medicago s a t i v a (94.6%) and T r i f o l i u m spp. (5.4%). Photographed i n August, 1979. 78 Figure 5.10 S i t e views of areas reclaimed in 1975, 1977 and 1 978 . (a) Areas reclaimed i n 1975 (foreground) and 1977. (b) Area reclaimed i n 1978. Photographed i n August, 1979. 79 Biomass samples c o l l e c t e d i n 1979 d i f f e r e d w i d e l y between 3 - 4 and 5 - 6 y e a r o l d v e g e t a t i o n ( F i g u r e 5.11). A s i m i l a r p a t t e r n was a l s o found i n the biomass d i s t r i b u t i o n o f samples i n 1980. However, th e biomass was found t o have i n c r e a s e d g e n e r a l l y as compared t o l e v e l s measured i n 1979. L i f t e r accumulated s l o w l y i n t h e e a r l i e r s t a g e s ( 2 - 3 and 3 - 4 y e a r o l d v e g e t a t i o n sampled i n 1979 and 1980, r e s p e c t i v e l y ) , t h e n r a p i d l y a t t h e l a t e r s tage ( 5 - 6 and 6 - 7 , r e s p e c t i v e l y ) ( F i g u r e s 5.11 and 5.12). A comparison o f t h e biomass and l i t t e r p a t t e r n s r e v e a l e d t h a t l i t t e r c o n t i n u e d t o accumulate i n the o l d e s t v e g e t a t i o n (1974 area) i n b o t h 1979 and 1980 s a m p l i n g , w h i l e t h i s was not t h e case w i t h r e s p e c t t o biomass. I t i s thus a p o s s i b i l i t y t h a t biomass on t h e o l d e s t (1974) area s measured i n 1979 and 1980 was a c t u a l l y l a r g e r t h a n r e c o r d e d ; l i t t e r a c c u m u l a t i o n s h o u l d r e f l e c t t h e amount o f t h e biomass from p r e c e d i n g y e a r s p r i o r t o s a m p l i n g . I t was n o t e d t h a t t h e a d d i t i o n o f biomass 2 2 (97 g/m a t age 6) t o l i t t e r (216 g/m a t age 6 i n F i g u r e 2 5.11) was 313 g/m , but the l i t t e r measured on t h i s a r e a i n 2 t h e f o l l o w i n g y e a r was 341 g/m (age 7 i n F i g u r e 5.12). The a d d i t i o n o f t h e biomass, w h i c h would become l i t t e r and weigh l e s s a f t e r d e c o m p o s i t i o n d u r i n g t h e f o l l o w i n g w i n t e r , and l i t t e r i n t h e 1979 s a m p l i n g s h o u l d be a t l e a s t as heavy as the l i t t e r measured i n the 1980 s a m p l i n g . T h i s p r o b a b l y caused t h e l a r g e v a r i a t i o n o b s e r v e d between samples. N o n e t h e l e s s , t h e g e n e r a l biomass p a t t e r n showed a c o n s i s t e n t p l a t e a u e f f e c t i n t h e o l d e r a r e a s . Aboveground 80 F i g u r e 5.11 Aboveground t o t a l biomass and l i t t e r (g/m 2) of re c l a i m e d a r e a s . Sampled i n 1979. o Aboveground t o t a l biomass • L i t t e r * No area reclaimed f o r t h i s age The samples were c o l l e c t e d August 3-22, 1979 from the areas r e c l a i m e d i n 1974-1978. The samples of age 2 were from the area r e c l a i m e d i n 1978. Each p o i n t and v e r t i c a l bar represent a mean and a standard d e v i a t i o n , r e s p e c t i v e l y , of 6 to 8 samples. 81 D.Wt. (g) 500 • 400 ] 3 4 5 6 7 age(year) Figure 5.12 Aboveground t o t a l biomass and l i t t e r (g/m2) of reclaimed areas. Sampled i n 1980. o Aboveground t o t a l biomass • L i t t e r * No area reclaimed f o r t h i s age The samples were c o l l e c t e d August 18-27, 1980 from the area reclaimed i n 1974-1978. The samples of age 3 were from the area reclaimed i n 1978. Each point and v e r t i c a l bar represent a mean and a standard d e v i a t i o n , r e s p e c t i v e l y , of 6 to 8 samples. 82 biomass measured i n t h e f i e l d p l o t t e s t a l s o showed a s i m i l a r p a t t e r n (see Ta b l e 5.19, page ). A number o f f a c t o r s may have c o n t r i b u t e d t o t h i s l e v e l l i n g o f f o f biomass p r o d u c t i o n . A v a i l a b l e s o i l n i t r o g e n i s t h e o b v i o u s c h o i c e as a l i m i t i n g f a c t o r . N i t r o g e n l e v e l s o f t h e 1974 a r e a were l e s s than t h o s e of 1975 a r e a i n b o t h t h e 1979 and 1980 sampli n g s (Table 5.4). S i m i l a r l y , l e v e l s o f a v a i l a b l e s o i l phosphorus, w h i c h might have a f f e c t e d the biomass p r o d u c t i o n , were much l e s s t h a n t h o s e o f t h e 1975 a r e a . Another p o s s i b i l i t y f o r t h e biomass p l a t e a u was t h a t the i n t r o d u c e d p l a n t community had reached i t s maximum p r o d u c -t i v e c a p a c i t y by t h e f i f t h y e a r . T h e r e a f t e r y e a r l y d i f f e r e n c e s i n biomass might m e r e l y r e f l e c t t h e y e a r l y f l u c t u a t i o n s o f e n v i r o n m e n t a l f a c t o r s , such as p r e c i p i t a t i o n . E n v i r o n m e n t a l v a r i a t i o n may s a t i s f a c t o r i l y account f o r the g e n e r a l l y h i g h e r biomass o b s e r v e d i n 1980 compared t o t h e 1979 samples, y e t a s i m i l a r p l a t e a u i n biomass l e v e l s on t h e o l d e r s i t e s was o b s e r v e d . The s t e a d y i n c r e a s e o f l i t t e r on the 1974 a r e a suggested a c o n t i n u o u s a d d i t i o n o f o r g a n i c m a t t e r and i t s r e l a t i v e l y slow d e c o m p o s i t i o n ( F i g u r e 5.13a). Z i e m k i e w i c z (1979) r e p o r t e d s i m i l a r l i t t e r a c c u m u l a t i o n on an u n f e r t i l i z e d p l o t l o c a t e d a t t h e same s i t e . However, on a f e r t i l i z e d p l o t o f the same t e s t , l i t t e r d e c o m p o s i t i o n was f a s t e r t h a n l i t t e r accumula-t i o n , i . e . n et l o s s i n l i t t e r . R a p i d d e c o m p o s i t i o n p r o b a b l y r e s u l t e d from t h e low C/N r a t i o s o f the l i t t e r , w h i c h , i n t u r n , r e s u l t e d from a heavy a p p l i c a t i o n o f f e r t i l i z e r (1,000 83 Figure 5.13 E a r l y season plant growth and Medicago s a t i v a on 1974 area. (a) E a r l y season plant growth. Rapid emergence of D a c t y l i s  g l o m e r a t a and T r i folium spp. i s obvious. Note d i s t r i b u t i o n of l i t t e r . May 12, 1980. (b) An area dominated by Medicago s a t i v a . Grass cover and l i t t e r accumulation are poor. T r i f o l i u m spp. are a l s o present i n the foreground. J u l y 4, 1980. 84 kg/ha o f 13-16-10). Thus, c o n t i n u e d l i t t e r a c c u m u l a t i o n r e s u l t e d i n an i n c r e a s e i n l i t t e r as a pe r c e n t a g e o f t h e combined aboveground biomass and l i t t e r as the v e g e t a t i o n aged, i . e . from 56.1% (age 5) t o 68.9% (age 6) i n 1979 o r from 44.2% (age 6) t o 58.8% (age 7) i n 1980 (Table 5.6). I t i s l i k e l y t h a t t h e r e c l a i m e d a r e a s would c o n t i n u e t o accumulate l i t t e r i n t h e near f u t u r e as t h e r e was l i t t l e i n d i c a t i o n o f d e c r e a s e d l i t t e r a c c u m u l a t i o n on t h e o l d e s t s i t e (age 7 ) . D i s t r i b u t i o n o f g r a s s e s , legumes and l i t t e r The r a t i o s o f aboveground biomass o f g r a s s e s and legumes showed s u b s t a n t i a l v a r i a t i o n among a r e a s r e c l a i m e d i n d i f f e r e n t y e a r s (Table 5.6). R a t i o s w i t h i n each a r e a a l s o v a r i e d i r r e g u l a r l y from t h e f i r s t t o the second s a m p l i n g d a t e . The v e g e t a t i o n o f t h e 1974 a r e a c o n s i s t e d o f a p p r o x i m a t e l y 60% g r a s s e s and 40% legumes and was r e l a t i v e l y s t a b l e d u r i n g the two summers o f s a m p l i n g (1979 and 1980). By f a r t h e most d r a s t i c change i n t h e legume component was found on the 1978 a r e a where t h e legume p e r c e n t a g e doubled from 38.1% i n 1979 t o 81.5% i n 1980. The o r i g i n a l seed mix comprised 70% g r a s s e s and 30% legumes by w e i g h t . The a v a i l a b l e d a t a may r e f l e c t changes caused by s e v e r a l f a c t o r s i n c l u d i n g s o i l n i t r o g e n , p l a n t d e n s i t y , g r a s s -legume c o m p e t i t i o n and p o s s i b l y the r e l a t i v e a d a p t a b i l i t y o f i n d i v i d u a l g r a s s and legume s p e c i e s t o the s u b a l p i n e e n v i r o n -ment. The d r a m a t i c i n c r e a s e o f the legume component on the 1978 a r e a i s p r o b a b l y a r e f l e c t i o n o f the c o r r e s p o n d i n g drop 85 Table 5.6 Aboveground biomass of grasses, legumes and l i t t e r on areas reclaimed from 1974 to 1978. grasses:legumes g r a s s e s + l e g . : l i t t e r year year reclaimed sampled grasses(%) legumes(%) grasses+leg(%) 1 i t t e r ( % ) 1 978 1 977 1 975 1 974 1 979 1 61 .9 38. 1 100.0 0.0 1980 2 18.5 81.5 95.2 4.8 1 979 72.5 27.5 . 96.3 3.7 1980 95.2 4.8 91.0 9.0 1979 88.9 11.1 43.9 56. 1 1980 93.3 6.7 55.8 44.2 1979 62.0 38.0 31.1 68.9 1980 63.6 36.4 41.2 58.8 1. August 3-22, 1979. 2. August 18-27, 1980. The f i g u r e s are means of 6 to 8 samples. 86 i n s o i l n i t r o g e n from 14.9 ppm i n 1979 t o 0.6 ppm i n 1980 (see Table 5.4). However, s i m i l a r changes i n s o i l n i t r o g e n (from 19.6 t o 4.9 ppm) d i d not r e s u l t i n a c o r r e s p o n d i n g i n c r e a s e i n t h e legume component on 1977 a r e a . T h i s l a c k o f response was a t t r i b u t a b l e m a i n l y t o the low d e n s i t y o f legumes on t h i s s i t e . The d e c r e a s e i n legume component ob s e r v e d on t h e 1975 a r e a was p r o b a b l y a consequence of the h i g h e r a v a i l -a b l e s o i l n i t r o g e n w h i c h gave t h e g r a s s e s i n t h e m i x t u r e a c o m p e t i t i v e advantage. The e s t i m a t e o f a e r i a l f e r t i l i z e r a p p l i e d i n d i c a t e d t h a t t h i s a r e a r e c e i v e d a p p r o x i m a t e l y 400 kg/ha o f 13-16-10 f e r t i l i z e r (Table 5.14). The s o i l d a t a p r e v i o u s l y d i s c u s s e d showed t h a t most o f the f e r t i l i z e r a p p l i e d on June 17, 1980 was not a v a i l a b l e when the aboveground biomass was sampled d u r i n g August 18-27, 1980. The i n o r g a n i c n i t r o g e n a p p l i e d p r o b a b l y encouraged more growth o f t h e g r a s s e s because t h e y are a b l e t o u t i l i z e t h e f e r t i l i z e r more e f f i c i e n t l y t h a n are t h e legumes when grown i n m i x t u r e (Walker e t a l . , 1956). S p e c i e s d i s t r i b u t i o n w i t h i n g r a s s e s and legumes S p e c i e s d i s t r i b u t i o n w i t h i n g r a s s e s showed t h a t the aboveground g r a s s biomass was g e n e r a l l y r e p r e s e n t e d by two s p e c i e s , D a c t y l i s g l o m e r a t a and F e s t u c a r u b r a (Table 5.7). In a l l a r e a s , e x c e p t t h e 1978 a r e a , the p e r c e n t a g e o f D. g l o m e r a t a i n c r e a s e d s u b s t a n t i a l l y , t o make up over 40% o f the g r a s s biomass i n 1980. F. r u b r a c o n s i s t e n t l y r e p r e s e n t e d more tha n 20% o f t h e biomass on a l l t h e a r e a s i n b o t h 1979 and 1980. Table 5.7 Aboveground biomass by species of grasses and legumes on areas reclaimed from 1974 to 1978. year rec1 a 1med 1978 year samp 1ed 1979 1 1980' D.g_l_. F . ru . 9.5 14. 1 25.2 31.7 grasses (%) P.gr B 20.2 2 . 3 i n 3.8 4 . 3 L.pe Psp_ A 20.6 33. 1 0.0 0.0 A.al 1 .0 0.3 A . pr . 0.0 0.0 unid. 19.7 14.1 legumes (%) T . SJD M. sa 99. 1 96 . 1 0.9 3.9 1977 1979 1980 21 .2 46 . 5 32 . 1 27 . 3 38 .8 20.8 1 .6 0.8 .0 . 2 0.3 0.0 1 .7 1 .6 0.0 O.O 3.3 1 .8 55.4 17.4 44 .6 82 .6 1975 1979 1980 49.8 50.3 35.9 35.4 12.6 11.6 1 .0 0.0 0.0 0.0 0.3 0.0 0.0 0.5 0.0 0.0 0.4 2 . 2 52 . 3 15.2 47 .8 84 . 7 1974 1979 1980 36 .0 43 . 6 39.3 23.2 16.2 14.2 7.8 9.7 0.6 0.0 0.0 7 . 2 0.0 0.0 0. 1 6.5 0.0 1 .6 5.4 3.3 94 .6 96.7 1 . August 3-22, 1979. 2. August 18-27. 1980. The data are means of 6 to 8 samples. Abbreviations are: D.gl - Dactyl 1s glomerata; F.ru - Festuca rubra; P.pr - Phieum pratense; B.ln - Bromus 1nerm1s; L.pe - Lo11 urn perenne; P.sp - Poa spp.; A.al - Agrost1s a 1 ba; A.pr - A1opecurus pratens1s; unid. - unidentified grasses; T.sp - Tr1fo1ium spp.; M.sa - Medicago sat iva. 88 Phleum p r a t e n s e was an i m p o r t a n t component on t h e 1977 and 1978 a r e a s where i t r e p r e s e n t e d 38.8 and 20.2%, r e s p e c t i v e l y , o f t h e g r a s s biomasses i n 1979. However, i t s r o l e on t h e s e a r e a s was s u b s e q u e n t l y much reduced t o 20.8 and 2.3%, r e s p e c -t i v e l y i n t h e 1980 s a m p l i n g . The dominant g r a s s s p e c i e s , D. g l o m e r a t a i s o n l y mode-r a t e l y w i n t e r hardy and f r e q u e n t l y w i l l not s u r v i v e n o r t h e r n c l i m a t i c c o n d i t i o n s i f snow c o v e r i s l a c k i n g (Heath e t a l . , 1974). However, i t i s r e p o r t e d t o be c o m p e t i t i v e a t a l t i t u d e s o f 2,700 - 3,000 m a . s . l . i n Utah, C o l o r a d o and Montana (Berg, 1974). The c o m p e t i t i v e n e s s demonstrated on t h e s u b a l p i n e a r e a s o f t h i s s t u d y i s due t o i t s a b i l i t y , under f a v o r a b l e m o i s t u r e and f e r t i l i t y c o n d i t i o n s , t o d e v e l o p i n 15 days a canopy o f l e a v e s t h a t i n t e r c e p t s 95% o f a v a i l a b l e s u n l i g h t (Pearce e t a l . , 1965, F i g u r e 5.13a). T h e r e f o r e the m a i n t e n -ance f e r t i l i z e r a p p l i e d y e a r l y p l u s the f a v o r a b l e m o i s t u r e c o n d i t i o n i n e a r l y s p r i n g ( F i g u r e 5.6) were p r o b a b l y t h e key t o i t s demonstrated c o m p e t i t i v e n e s s on t h e s t u d y a r e a . How-e v e r , s h o u l d t h e f e r t i l i z e r program be t e r m i n a t e d p r i o r t o s i g n i f i c a n t improvement o f s o i l f e r t i l i t y o f t h e r e c l a i m e d a r e a s , one might e x p e c t t h e dominance o f a s p e c i e s such as D. g l o m e r a t a , w h i c h responds t o h i g h f e r t i l i t y , t o d e t e r i o r a t e r a p i d l y . F. r u b r a i s p r i m a r i l y a lawn and t u r f s p e c i e s e s p e c i a l l y adapted t o shaded, d r y s i t e s . The p l a n t s , w h i c h form dense t u f t s w i t h numerous s t i f f , r a t h e r sharp d a r k green l e a v e s , were o b s e r v e d t o be u n i f o r m l y d i s t r i b u t e d t h r o u g h o u t the s t u d y a r e a s . T h i s s p e c i e s was found t o be p a r t i c u l a r l y 89 dominant near t h e n o r t h e r n edges o f t h e s u b a l p i n e f o r e s t w h i c h were shaded f o r l o n g e r p e r i o d s . F. r u b r a was always found under the dense canopy o f o t h e r g r a s s s p e c i e s . The h i g h d e n s i t i e s o b s e r v e d on the 1977 and 1978 areas (Table 5.8) were c o n s i s t e n t w i t h t h e d i s t r i b u t i o n d a t a f o r t h i s s p e c i e s on t h e same areas (Table 5.7). I t was i n t e r e s t i n g t o note t h a t on the 1978 s i t e , where the t o t a l g r a s s component dropped from 61.9% i n 1979 t o 18.5% i n 1980, the pe r c e n t a g e o f F. r u b r a i n t he biomass o f g r a s s e s r o s e from 25.2% t o 31.7%, r e s p e c -t i v e l y . C o n s i d e r i n g t h e f a c t t h a t t h i s a r e a was not f e r t i l i z e d i n 1980, i t appeared t h a t t h i s s p e c i e s might p l a y a more i m p o r t a n t r o l e i f the maintenance f e r t i l i z e r was stopped i n the f u t u r e p r i o r t o a c o r r e s p o n d i n g improvement o f t h e e x i s t i n g s o i l f e r t i l i t y . There were t h r e e legume s p e c i e s p r e s e n t on the r e c l a i m e d a r e a s , T r i f o l i u m r e p e n s , T. hybridum and Medicago s a t i v a . The c o n t r i b u t i o n o f M. s a t i v a tended t o be g r e a t e r on t h e o l d e r a r e a s (95% o f t h e aboveground legume biomass o f the 1974 a r e a i n b o t h 1979 and 1980). On b o t h t h e 1975 and 1977 areas M. s a t i v a n e a r l y , d o u b l e d t o more th a n 80% from 1979 t o 1980. The st e a d y i n c r e a s e o f M. s a t i v a occupancy t h r o u g h o u t t h e st u d y a r e a s suggested t h a t t h i s s p e c i e s was w e l l adapted t o t h i s e nvironment. T h i s s p e c i e s i s a p h r e a t o p h y t e and can o b t a i n water from deep underground t h r o u g h i t s w e l l - d e v e l o p e d t a p r o o t ( F i g u r e 5.13b). I t has a l s o been r e p o r t e d t o be a b l e t o f i x n i t r o g e n a c t i v e l y i n d r y s o i l s when o t h e r legumes c o u l d not (Johnson and Rumbaugh, 1981). However, i t s seed p r o d u c -T a b l e 5 . 8 P l a n t d e n s l t y / m ' o n t h e a r e a s r e c l a i m e d I n 1 9 7 7 a n d 1 9 7 8 1 e q u m e s g r a s s e s _ — Vegetated O . g , F . r u P - E H B . l n L . ^ E-1E A.al A px u n * . - — 35121 1 2 ^ 9 2 2 ± 3 3 18113 4 9 1 3 8 . O i 2 ± 2 0 6 7 1 7 9 1 0 7 1 S 8 0 1 0 7 8 1 7 1 1 0 7 1 7 6 6 6 1 4 5 13112 2 2 ± 5 0 2±3 6 1 7 O 10111 2 1 3 3 1 4 , « . , „ , . = + i P 7 q T h e f i g u r e s a r e m e a n s a n d s t a n d a r d £v^TiirJrS^ ,S°.A.UmSV«. ll'^ll^t » . ? , o r a b l a t i o n s . O 91 t i o n appeared t o be v e r y l i m i t e d i n t h i s e nvironment, so i t s f u t u r e was u n c e r t a i n . There may be some advantage, i n view o f the low r e s e e d i n g c a p a b i l i t y , i n t h e use o f c r e e p i n g r o o t e d a l f a l f a v a r i e t i e s t o encourage c r o p p e r s i s t e n c e i n such a r e a s . Except on t h e new s e e d i n g i n 1978, w h i c h was dominated by T r i f o l i u m spp. (over 96% o f legume biomass i n 1979 and 1980), M. s a t i v a was t h e s i n g l e most i m p o r t a n t s p e c i e s (over 82% i n 1980). 5.3 Greenhouse p o t t e s t s 5.3.1 C h e m i c a l a n a l y s i s o f f r e s h s p o i l s Greenhouse pot t e s t s were c a r r i e d out u s i n g a s p o i l composed o f mixed g r a y i s h and b l a c k i s h s h a l e s , r e p r e s e n t a t i v e o f t h o s e found on t h e s t u d y a r e a ( F i g u r e 5.14). R e s u l t s o f c h e m i c a l a n a l y s e s o f t h i s s p o i l are shown i n T a b l e 5.9. S p o i l s c o l l e c t e d d u r i n g t h e summers o f 1979 and 1980 were v e r y s l i g h t l y a l k a l i n e w i t h phosphorus l e v e l s o f 0.3 t o 3.7 ppm. However, the combined ammonium and n i t r a t e l e v e l o f t h e s p o i l c o l l e c t e d i n 1979 was s i g n i f i c a n t l y (P < 0.01) h i g h e r t h a n t h a n i n 1980. T h i s h i g h e r l e v e l o f n i t r o g e n might be the r e s u l t o f m i n e r a l i z a t i o n o f i n d i g e n o u s n i t r o g e n i n the u n f r o z e n s p o i l (Power e t a l . , 1974 and Reeder and B e r g , 1977). 5.3.2 Treatment e f f e c t s on a c e t y l e n e r e d u c t i o n I t became apparent t h a t n i t r o g e n f i x a t i o n a c t i v i t y c o u l d change d r a s t i c a l l y i n a r e l a t i v e l y s h o r t p e r i o d o f t i m e , i . e . c a . 20 days. I n pot t e s t 1 t h e grand mean o f e t h y l e n e 92 Figure 5.14 Fresh s p o i l s adjacent to the study area. (a) Close up of fres h s p o i l s . (b) General view of f r e s h s p o i l s . (Photographed i n August, 1979) . T a b l e 5 . 9 p H , P h o s p h o r u s , a m m o n i u m a n d n i t r a t e o f f r e s h s p o i l s . s p o 1 1 s s p o i l u s e d 1 n p o t t e s t 1 a n d 2 1 s p o i l u s e d 1 n p o t t e s t 2' pH N H 4 NO 2 7 . 3 b 0 . 3 a 4 . 3 a 3 . 2 a 7 . 9 a 3 . 7 a . 0 . 1 b 1 . 3 b 1 . C o l l e c t e d 1 n A u g u s t , 1 9 7 9 . S a m p l e s w e r e k e p t u n f r o z e n f o r 15 m o n t h s p r i o r t o n i t r o g e n a n a l y s e s . 2 . C o l l e c t e d I n J u l y - A u g u s t , 1 9 8 0 . S a m p l e s w e r e k e p t f r o z e n f o r a p p r o x i m a t e l y 4 m o n t h s p r i o r t o n i t r o g e n a n a l y s e s . M e a n s f o l l o w e d b y a c o m m o n l e t t e r w e r e n o t s i g n i f i c a n t l y d i f f e r e n t a t 1% l e v e l b y D u n c a n ' s m u l t i p l e r a n g e t e s t . NrU* + NO3" 7 . 5 a 1 . 5 b MO 94 p r o d u c t i o n changed from 11.6 ppm (80 days a f t e r seeding) t o 21.2 ppm (99 d a y s ) , and i n p o t t e s t 2 from 7.3 ppm (64 days) and 7.0 ppm (78 days) t o 14.1 ppm (99 d a y s ) . T h i s r e l a t i v e l y i n e f f e c t i v e f i x a t i o n i m p l i e d t h a t t h e legumes were more dependent on s o i l n i t r o g e n i n the e a r l i e r s t a g e s t h a n i n t h e l a t e r s t a g e s o f p l a n t growth. T h e r e f o r e s t r o n g c o m p e t i t i o n f o r n i t r o g e n uptake would be p a r t i c u l a r l y d e t r i m e n t a l t o the legumes d u r i n g the p e r i o d o f i n e f f e c t i v e f i x a t i o n i n t h e e a r l y s t a g e s o f p l a n t growth. G e n e r a l t r e n d s o f a c e t y l e n e r e d u c t i o n i n f l u e n c e d by the t r e a t m e n t s were s i m i l a r i n b o t h e a r l i e r and l a t e r s t a g e s o f p l a n t growth. S i n c e t r e a t m e n t d i f f e r e n c e s were more i n t e n s i -f i e d a t t h e l a t e r s t a g e s o f p l a n t growth, d i s c u s s i o n o f the r e s u l t s w i l l c o n c e n t r a t e on tho s e l a t e r s t a g e s . 5.3.2.1 Grass c o m p o s i t i o n Grass s e e d i n g r a t e s had s i g n i f i c a n t e f f e c t s (P <0.01) on t h e r e d u c t i o n o f a c e t y l e n e i n b o t h t e s t s e x c e p t a t 80 days i n t e s t 1 (Tables 5.10 and 5.11). W i t h the l a t t e r e x c e p t i o n , a c e t y l e n e r e d u c t i o n d e c r e a s e d l i n e a r l y (P < 0.01) w i t h ... i n c r e a s e d g r a s s s e e d i n g r a t e s (APPENDICES 1 and 2, and Table 5.12). The t h r e e r e g r e s s i o n e q u a t i o n s f o r p o t t e s t 2 are shown below: 64 days Y = .7,806 - 0.0180 X ( r 2 = 0.039) 78 dyas Y = 9.406 - 0.0471 X ( r 2 = 0.107) 99 days Y = 17.192 - 0.0996 X ( r 2 = 0.088) where X = g r a s s s e e d i n g r a t e (kg/ha) and Y = e t h y l e n e T a b l e 5 b 1 o m a s s 1 0 V a r i a n c e a n a l y s e s f o r a c e t y l e n e r e d u c t i o n , a n d s o i l f a c t o r s ( p o t t e s t 1 ) . a b o v e - a n d s o u r c e b l o c k g r a s s 1 e g u m e f e r t 1 1 1 z e r G * L G * F L * F G * L * F e r r o r t o t a l ( M e a n s q u a r e 1 ) a b o v e g r o u n d b e l o w g r o u n d . a c e t y l e n e a s s a y b i o m a s s ( 1 1 2 d a y s ) b i o m a s s ( 1 1 2 d a y s ) s o i l ( 1 1 2 d a y s ) D F 8 0 d a y s 9 9 d a y s q r a s s 1 e q u i n e 2 2 . 2 7 . 5 * * 0 . 2 5 . 0 2 2 . 4 1 1 . 5 * * 4 9 . 5 * * 3 5 . 8 ' 1 1 . 0 2 . 1 0 . 3 1 . 2 2 2 7 . 6 * * • 44 9 ** 2 0 . 6 * * 3 . 9 2 5 . 3 0 . 3 1 . 6 3 . 2 4 3 . 9 1 . 5 1 1 . 5 * * 6 . 9 2 3 . 7 0 . 3 1 . 3 2 . 6 4 6 . 2 9 . 4 * 2 . 7 2 . 9 3 4 4 7 . 9 2 2 . 4 1 2 . 2 3 8 . 4 5 3 1 0 0 . 0 1 O O . 0 1 O 0 . 0 1 0 0 . 0 ( 6 2 . 0 ) ( 6 0 . 0 ) ( 3 . 8 ) ( 1 1 . 9 ) g r a s s + 1 e g u m e 5 . 7 7 . 5 0 . 1 6 . 1 0 . 8 8 . 1 4 . 4 / 7 . 9 5 9 . 4 1 0 0 . 0 ( 2 7 . 5 ) N H 4 + N 0 3 ~ 1 1 . 9 * 0 . 8 3 . 2 1 1 4 . 1 6 . 5 . 5 4 . 8 1 0 0 . 0 . 6 9 1 4 2 ( 1 2 . 3 ) 16 . 3 . 0 . 9 . 2 . 7 * * 5 1 0 * 2 1 7 . 9 * * 0 . 7 1 2 . 7 * 3 7 . 4 1 0 0 . 0 ( 4 8 . 6 ) 1 . R e a l m e a n s q u a r e o f e r r o r . T h e f i g u r e s a r e s u m o f s q u a r e s e x p r e s s e d I n p e r c e n t a g e o f t o t a l s u m o f s q u a r e s . * . * * s i g n i f i c a n t a t 5 a n d 1 f. l e v e l r e s p e c t 1 v e l y . T a b l e 5 . 1 1 V a r i a n c e a n a l y s e s f o r a c e t y l e n e r e d u c t i o n , b i o m a s s a n d s o i l f a c t o r s ( p o t t e s t 2 ) . a c e t y l e n e r e d u c t i o n D F 6 4 d a y s 7 8 d a y s 9 9 d a y s b l o c k 4 2 2 . O * * 18 . 6 * * 18 . 8 * * g r a s s 3 5 . 0 * * 14 . 2 * * 9 . 5 * * 1 e g u m e 1 5 . 5 * * 2 . . 5 * 1 . 3 f e r t 1 1 1 z e r 2 18 . . 4 * * 5 . . 5 * * 4 . .2 * G * L 3 0 . . 8 0 . . 7 0 . .6 G * F 6 2 . . 1 4 . . 2 6 . . 5 L * F 2 1 . . 6 2 . 7 1 , . 1 G * L * F 6 8 . 1 * * 6 . 5 * 8 . 7 * e r r o r 9 2 3 6 . 5 4 5 . 1 4 9 . 5 t o t a l 1 1 9 1 0 0 . 0 1 0 0 . 0 1 0 0 . 0 ( m e a n s q u a r e ' ) ( 2 . 7 ) ( 8 . 1 ) ( 4 8 . 6 ) a b o v e g r o u n d b i o m a s s g r a s s t o t a l N H 4 * + q r a s s 1 e g u m e 1 e q u m e b i o m a s s ' NO3" 0 . 2 7 . 6 * * 1 4 . 0 * * 9 . 6 * * 1 0 . 2 * * 6 4 .-1 + * 3 1 . 6 * * 8 . 5 * * 2 7 . 6 * * 8 . 1 * * 0 . 9 * * 3 . 5 * * 1 . 5 0 . . 1 0 . 2 2 1 . 2 * * 7 . 2 * * 1 2 . 4 * * 14 . . 2 * * 2 6 . 7 0 . 4 * 0 . 7 0 . 4 1 . . 0 0 . 5 9 . 0 * * 1 3 . 6 * * 3 . 4 3 . 8 4 . 8 0 . 1 2 . 4 * 3 . 4 * 1 . 9 0 . 1 0 . 6 * 4 . 7 * 1 0 . 9 * * 1 0 . 3 * * 0 . 6 3 . 5 2 8 . 6 4 5 . 5 3 1 . 6 4 8 . 8 1 0 0 . 0 1 0 0 . 0 1 0 0 . 0 1 0 0 . 0 1 0 0 . 0 ( 1 . 1 ) ( 1 0 . 5 ) ( 1 0 . 9 ) ( 3 0 . 0 ) ( 9 5 . 2 ) 1 . A b o v e - p l u s b e l o w g r o u n d b i o m a s s . 2 . M e a n s q u a r e o f e r r o r . T h e f i g u r e s a r e s u m o f s q u a r e s e x p r e s s e d i n p e r c e n t a g e o f t o t a l s u m o f s q u a r e s . * , * * s i g n i f i c a n t a t 5 a n d 1 % l e v e l , r e s p e c t i v e l y . B i o m a s s a n d s o i l s a m p l e s w e r e c o l l e c t e d o n 1 0 3 a n d 5 2 d a y s a f t e r s e e d i n g , r e s p e c t i v e l y . CA Table 5 12 Acetylene reduction, .aboveground biomass and s o i l factors determined by seeding and nitrogen f e r t i l i z e r rates. days a f t e r seed i ng1 CjH^ p p m ) 80 99 64 78 99 grass (g/pot) 112 103 legume (g/pot) 1 12 103 0 13.5' 27. 1 7 .6« 8.3 18.0 0 0 15. 1 16.3 grass+leg.(g/pot) 112 15.1 103 16.3 NHf+NOfXppm) 1 12 52 P (ppm) 1 12 4 . 1 18.6 37 .6 seeding rate (kq/ha)  grass  N f e r t l l z e r (kq/ha) 17.5 35 70 I 5 . 10.4 10.8 N 10.7 20.0 16.6 N 19.4 7.9 7 . 1 6.5 6.7 8 . 4 5.7 5.4 6.4 14.9 12.9 10.8 13.2 5 . 3 6.2 10.2 13.2 15.5 19.4 4 . 2 12.2 36 .8 7.4 8.6 8.9 10. 1 16 . 3 18.7 4.9 10.6 33 . 7 N 10.6 N 8.5 N 19. 1 N 9.7 N 1equme 30 4.5 6.8 10.9 11.0 15.4 17.8 5. 1 13.4 36.4 10 25 50 75 100 12 . 5' 17.5 N 1 1 . 2 N 5 . 23. 1 32 .9 N 18 . 8 N 12 . 7 . 8 5 N 8.0 7 . 9 5 . 8 N 7 . 6 N 6.9 8 . 1 5 . 9 N 15. 1 N 14.7 16. 0 1 1 . 7 N 4 . 0 1 .6 N 4 . 6 N 6 . 5. 9 N 3.6 6 . 2 9 . 2 N 1 1 . .9 12.6 N 10 .9 N 10. 13 .0 N 12.6 13 . 4 10. . 1 N 15 .9 14.2 N 15 . 5 N 17 18 .9 N 16 . 2 19 .6 19 . 3 N 3 . 7 3.3 N 3 .6 N 6 12 . 2 N 6.4 10 .6 21 . 4 N 35 .7 32 .4 N 36 . 7 N 39 1 Days 80. 99 and 112 are for pot test 1; and 52. 64, 78 2,3.4 9and d5 1 ° 3 M^ans tof t18; 27, 30 or 60 measurements, respectively. tsi s No value 98 c o n c e n t r a t i o n (ppm). These e q u a t i o n s i n d i c a t e d t h a t t h e n e g a t i v e e f f e c t s o f h i g h e r g r a s s s e e d i n g r a t e s on a c e t y l e n e r e d u c t i o n i n c r e a s e d as p l a n t s matured from 64 t o 99 days because th e s t e e p n e s s o f t h e r e g r e s s i o n l i n e s l o p e s i n c r e a s e d s t e a d i l y d u r i n g t h i s p e r i o d from -0.0180 t o -0.0996, r e s p e c -t i v e l y . A s i m i l a r t r e n d was a l s o o b v i o u s i n p o t t e s t 1 (Table 5.12). T h e r e f o r e i t i s r e a s o n a b l e t o c o n c l u d e , w i t h i n the ranges o f t h e s e e d i n g r a t e s and growth p e r i o d s c o v e r e d i n t h i s s t u d y , t h a t : (a) i n c r e a s i n g g r a s s s e e d i n g r a t e s g e n e r a l l y d e p r e s s e d n i t r o g e n f i x a t i o n , and t h a t (b) t h e n e g a t i v e e f f e c t s o f t h e i n c r e a s e d s e e d i n g r a t e s i n t e n s i f i e d as t h e g r a s s and legume matured. The former d e p r e s s i n g e f f e c t o f i n c r e a s e d g r a s s s e e d i n g r a t e s was p r o b a b l y caused by the r e s u l t a n t l a r g e r g r a s s biomass wh i c h i n t e r c e p t e d more l i g h t and reduced l i g h t a v a i l a b i l i t y t o t h e legumes ( F i g u r e s 5.15 - 5.17). Grasses a r e known t o be more e f f i c i e n t i n m i n e r a l n i t r o g e n uptake t h a n a r e legumes (Walker e t a l . , 1956). The g r a s s r o o t h a i r s a re l o n g e r and more f r e q u e n t and t h e i r c a t i o n exchange ca p a -c i t y i s g e n e r a l l y h a l f t h a t o f legumes (Evan, 1977 and Asher and Ozanne, 1961). These m o r p h o l o g i c a l and p h y s i o l o g i c a l d i f f e r e n c e s f a v o r t h e g r a s s e s f o r e f f i c i e n t n i t r o g e n (NO^ -) uptake compared t o t h e legumes. I n c r e a s e d g r a s s s e e d i n g r a t e s were b e l i e v e d t o a s s i s t g r a s s e s i n t h e i r development o f r o o t systems w h i c h enhanced t h e i r n i t r o g e n uptake e f f i c i e n c y and biomass p r o d u c t i o n ( i . e . reduced l i g h t a v a i l a b i l i t y t o legumes), t h u s d e p r e s s i n g legume n i t r o g e n f i x a t i o n . However, i t s h o u l d F i g u r e 5.15 Grass-legume s t a n d s t r e a t e d w i t h 25 kg/ha n i t r o g e n f e r t i l i z e r , pot t e s t 2. (a) 15 kg/ha legume seeding. (b) 30 kg/ha legume s e e d i n g . The p o t s were seeded w i t h 0 , 1 7 . 5 , 35 and 70 kg/ha g r a s s e s ( l e f t t o r i g h t ) . Photographed 94 days a f t e r s e e d i n g . 100 Figure 5.16 Grass-legume stands t r e a t e d with 50 kg/ha nitrogen f e r t i l i z e r , pot t e s t 2. (a) 15 kg/ha legume seeding. (b) 30 kg/ha legume seeding. The pots were seeded with 0, 17.5, 35 and 70 kg/ha g r a s s e s ( l e to r i g h t ) . Photographed 94 days a f t e r seeding. 101 Figure 5.17 Grass-legume stands t r e a t e d with 75 kg/ha nitrogen f e r t i l i z e r , pot t e s t 2. (a) 15 kg/ha legume seeding. (b) 30 kg/ha legume seeding. The p o t s w e r e s e e d e d w i t h 0, 17.5, 35 a n d 70 kg/ha grasses ( l e f t to r i g h t ) . Photographed 94 days a f t e r seeding. 102 a l s o be noted t h a t t h e c o n c o m i t a n t lower s o i l n i t r o g e n l e v e l s c o u l d o c c u r as a r e s u l t o f the enhanced n i t r o g e n uptake ( F i g u r e 5.22), a change p o t e n t i a l l y f a v o r a b l e t o n i t r o g e n f i x a t i o n . The i n t e n s i f i e d n e g a t i v e e f f e c t s o f t h e i n c r e a s e d g r a s s s e e d i n g r a t e s on n i t r o g e n f i x a t i o n d u r i n g l a t e r p l a n t growth i n d i c a t e d . t h a t the g r a s s e s became more c o m p e t i t i v e t h a n the legumes, p r o b a b l y as a r e s u l t o f d i f f e r e n c e s i n s e e d l i n g growth r a t e o r t o i n e f f i c i e n t legume n i t r o g e n f i x a t i o n i n the e a r l i e r s t a g e s o f development. 5.3.2.2 Legume c o m p o s i t i o n Legume s e e d i n g r a t e s (15 and 30 kg/ha) g e n e r a l l y had much l e s s e f f e c t on a c e t y l e n e r e d u c t i o n a c t i v i t y t h a n g r a s s s e e d i n g r a t e s . I n p o t t e s t 1 legume s e e d i n g r a t e s showed no s i g n i f i c a n t e f f e c t on a c e t y l e n e r e d u c t i o n a t e i t h e r 80 o r 99 days. However, i n t e s t 2 a s i g n i f i c a n t e f f e c t on the a c e t y l e n e r e d u c t i o n was o b s e r v e d a t b o t h 64 (P < 0.01) and 78 days (P < 0.05) (Tables 5.10-12). I n b o t h t e s t s the h i g h e r legume r a t e always r e s u l t e d i n more a c e t y l e n e r e d u c t i o n (e.g., 13.2 and 15.1 ppm f o r 15 and 30 kg/ha, r e s p e c t i v e l y a t 99 days i n t e s t 2 ) . T h i s p o s i t i v e e f f e c t o f h i g h e r s e e d i n g r a t e s was encouraged by t h e r a p i d , e f f e c t i v e ground c o v e r e s t a b l i s h e d by the l a r g e r legume s e e d l i n g p o p u l a t i o n . I t was a l s o s u s p e c t e d t h a t t h e d i f f e r e n c e between g r a s s e s and legumes i n t h e r a t e o f emergence and s e e d l i n g v i g o u r had p l a y e d an i m p o r t a n t r o l e on t h e o b s e r v e d phenomenon. B l a s e r 103 e t a l . , (1956) had shown t h a t u s i n g 100 as a measure o f seed-l i n g v i g o r (based' on r e l a t i v e d r y weight) f o r Medicago s a t i v a , T r i f o l i u m hybridum and T. repens had v a l u e s o f 31 and 38, r e s p e c t i v e l y , whereas D a c t y l i s g l o m e r a t a , Phleum p r a t e n s e , F e s t u c a r u b r a and Bromus sp. had v a l u e s o f 42, 17, 13, 6, r e s p e c t i v e l y . However, t h e r e might e x i s t a s i t u a t i o n where the i n c r e a s e d legume component i n c r e a s e d legume f o r a g e amounts t o such an e x t e n t t h a t s e l f - s h a d i n g might o c c u r . Because legumes g e n e r a l l y p o s s e s s h o r i z o n t a l l y - i n c l i n e d ( p l a n o p h i l e ) l e a v e s and absorb l i g h t from o n l y a few l a y e r s o f l e a v e s , t h e y r e a c h a c r i t i c a l l e a f a r e a i n d e x more q u i c k l y t h a n g r a s s e s w i t h v e r t i c a l l y - i n c l i n e d ( e r e c t o p h i l e ) l e a v e s (Langer, 1973 and Haynes, 1980). I t i s not apparent whether such an e f f e c t on n i t r o g e n f i x a t i o n can be m a i n t a i n e d i n a p e r s i s t e n t s t a n d , p a r t i c u l a r l y d u r i n g second y e a r growth a f t e r p l a n t s have been s u b j e c t e d t o t h e h a r s h w i n t e r p e r i o d . Over-crowding may r e s u l t i n h i g h e r m o r t a l i t y , and reduce n i t r o g e n - f i x i n g p o t e n -t i a l i n f u t u r e y e a r s o f t h e s t a n d . 5.3.2.3 N i t r o g e n f e r t i l i z e r I n b o t h t e s t s t h e n i t r o g e n f e r t i l i z e r t r e a t m e n t s had s i g n i f i c a n t e f f e c t s on a c e t y l e n e r e d u c t i o n a c t i v i t i e s a t a l l s a m p l i n g d a t e s (Tables 5.10-11, pages and ). Over a wide range o f f e r t i l i z e r a p p l i c a t i o n (10-100 kg/ha o f t e s t 1 ) , a c e t y l e n e r e d u c t i o n d e c r e a s e d l i n e a r l y w i t h i n c r e a s i n g f e r t i l i z e r r a t e s , w h i l e , w i t h i n a narrow range o f f e r t i l i z e r (25-75 kg/ha o f t e s t 2 ) , t h i s was t r u e o n l y a t 64 days a f t e r 104 s e e d i n g . I n b o t h 78 and 99 day s a m p l i n g ( t e s t 2 ) , a c e t y l e n e r e d u c t i o n l e v e l s had s i g n i f i c a n t , n o n - l i n e a r r e l a t i o n s h i p s w i t h f e r t i l i z e r t r e a t m e n t (P <0.01 and 0.05, r e s p e c t i v e l y , Appendix 2) and the h i g h e s t a c e t y l e n e r e d u c t i o n a c t i v i t y o c c u r r e d a t 50 kg/ha n i t r o g e n f e r t i l i z e r ; t he l o w e s t a t 75 kg/ha (Table 5.12). The maximized n i t r o g e n f i x a t i o n a t 50 kg/ha n i t r o g e n ( t e s t 2),was a p p a r e n t l y c o n t r a r y t o t h e commonly-accepted i n f l u e n c e o f a p p l i e d n i t r o g e n on f i x a t i o n , i . e . reduced n i t r o g e n f i x a t i o n w i t h i n c r e a s e d s o i l n i t r o g e n . A p p l i e d n i t r o g e n has d i r e c t n e g a t i v e e f f e c t s on f i x a t i o n such as d e p r e s s i o n o f nodule f o r m a t i o n and r e d u c t i o n o f r o o t h a i r p r o l i f e r a t i o n (van Schreven, 1959; R u s s e l l , 1973; Gibson and Nutman, 1960; Ri g a u d , 1976; S m a l l and Leonard, 1969). A p p l i e d n i t r o g e n may a l s o have i n d i r e c t n e g a t i v e e f f e c t s on f i x a t i o n where i n c r e a s e d g r a s s growth reduces l i g h t a v a i l a b i l i t y t o a s s o c i a t e d legumes (Donald, 1963). I n a grass-legume a s s o c i a -t i o n t h e r e l a t i o n s h i p between n i t r o g e n f i x a t i o n and s p e c i e s b a l a n c e i s f u r t h e r c o m p l i c a t e d by t h e more e f f i c i e n t n i t r o g e n uptake by g r a s s e s w h i c h lo w e r s s o i l n i t r o g e n l e v e l s . Walker e t a_l. , (1956) r e p o r t e d t h a t i n p o t e x p e r i m e n t s 95% o f a p p l i e d n i t r o g e n was t a k e n up by g r a s s e s , a l t h o u g h t h i s might not o c c u r i n an e s t a b l i s h e d grass-legume a s s o c i a t i o n i n t h e f i e l d where t h e h i g h e r s o i l o r g a n i c m a t t e r c o n t e n t under such a s t a n d may r e s u l t i n a h i g h e r c a t i o n exchange c a p a c i t y and g r e a t e r ammonium a d s o r p t i o n . Legume growth and f i x a t i o n a r e 105 a f t e n i n c r e a s e d by a s m a l l dose o f n i t r o g e n d u r i n g t h e time between e x h a u s t i o n o f seed r e s e r v e s and e s t a b l i s h m e n t o f an e f f e c t i v e n i t r o g e n f i x i n g system (Pate and D a r t , 1961; D i a t l o f f , 1974). I t was p r o b a b l e t h a t the d i r e c t n e g a t i v e e f f e c t s o f a p p l i e d n i t r o g e n on legume n i t r o g e n f i x a t i o n would be s m a l l because o f the r e s u l t a n t low s o i l n i t r o g e n l e v e l caused by e f f i c i e n t g r a s s n i t r o g e n u p t a k e . V a l l i s (1978) r e p o r t e d t h a t v a r i o u s legume s p e c i e s d i f f e r e d i n t h e i r r e l a t i o n -s h i p between p a r t i t i o n i n g o f m i n e r a l n i t r o g e n uptake and b o t a n i -c a l (grass-legume) c o m p o s i t i o n o f e s t a b l i s h e d swards. T h i s o b s e r v a t i o n i m p l i e d t h a t t h e d i r e c t e f f e c t s o f a p p l i e d n i t r o g e n on legumes would be dependent on legume s p e c i e s and b o t a n i c a l c o m p o s i t i o n . S i m i l a r complex i n t e r a c t i o n s have been r e p o r t e d by H a l l (1974) and Haynes (1980) and might be a n t i c i p a t e d i n t h e systems s t u d i e d i n t h i s t h e s i s . I n t h e s e greenhouse e x p e r i m e n t s , the apparent maximiza-t i o n o f n i t r o g e n f i x a t i o n a t 50 kg/ha n i t r o g e n i s a r e f l e c t i o n o f t h e f a c t o r s d e s c r i b e d above. S t i m u l a t i o n o f the g r a s s component w i t h i t s a s s o c i a t e d i n c r e a s e i n n i t r o g e n uptake would reduce th e a v a i l a b l e n i t r o g e n l e v e l such t h a t i n s t e a d o f a d e p r e s s i o n o f f i x a t i o n , one o b s e r v e s the s i t u a t i o n analogous t o h a v i n g p r o v i d e d t h e legume w i t h a dose o f " s t a r t e r " n i t r o g e n . At lower n i t r o g e n f e r t i l i z e r l e v e l s , i n s u f f i c i e n t n i t r o g e n i s a v a i l a b l e t o s t i m u l a t e f i x a t i o n . At h i g h e r n i t r o g e n f e r t i l i z e r r e g i m e s , th e n e g a t i v e consequences o f i n c r e a s e d n i t r o g e n l e v e l s and l i g h t c o m p e t i t i o n are apparent 106 i n t h e reduced n i t r o g e n f i x a t i o n a c t i v i t y o f the legume component. 5.3.3 Treatment e f f e c t s on biomass and s o i l f a c t o r s Above ground biomass o f g r a s s e s and legumes and the t h r e e s o i l f a c t o r s (ammonium, n i t r a t e and phosphorus) i n v e s t i -g a t e d here are i m p o r t a n t i n u n d e r s t a n d i n g the e f f e c t s o f v a r i o u s t r e a t m e n t s on legume n i t r o g e n f i x a t i o n . Biomass, wh i c h p r o v i d e s a measure o f p l a n t s u c c e s s , i s the end p r o d u c t of growth and c o m p e t i t i o n w i t h o t h e r s p e c i e s . S o i l f a c t o r s may be used t o p r o v i d e e s t i m a t e s o f t h e l e v e l s o f t h e s e f a c t o r s a t s e l e c t e d t i m e s t o a s c e r t a i n i n f o r m a t i o n u s e f u l t o the under-s t a n d i n g o f grass-legume c o m p e t i t i o n and legume n i t r o g e n f i x a t i o n . 5.3.3.1 Biomass Aboveground g r a s s biomass was s i g n i f i c a n t l y (P 0.01) a f f e c t e d by g r a s s and n i t r o g e n f e r t i l i z e r t r e a t m e n t s (Tables 5.10 and 5.11). A n a l y s e s r e v e a l e d t h a t t h e s e two t r e a t m e n t s had p o s i t i v e l i n e a r r e l a t i o n s h i p s w i t h g r a s s biomass over a wide (10 - 100 kg/ha) and w i t h i n a narrow 25 - 75 kg/ha) f e r t i l i z e r range (APPENDICES 1 and 2 ) . These s i m p l e p o s i t i v e r e l a t i o n s h i p s were l i k e l y a consequence of an i n c r e a s e i n g r a s s n i t r o g e n uptake c o n s i s t e n t w i t h the denser g r a s s p o p u l a -t i o n ( h i g h e r g r a s s s e e d i n g r a t e ) o r h i g h e r n i t r o g e n f e r t i l i t y ( h i g h e r f e r t i l i z e r r a t e ) . Moreover, the f a c t t h a t t h e s e r e l a t i o n s h i p s were l i n e a r i n d i c a t e d l i t t l e c o m p e t i t i o n f o r s o i l n i t r o g e n between g r a s s e s and legumes. There were a l s o 107 s i g n i f i c a n t n o n l i n e a r r e l a t i o n s h i p s w i t h the g r a s s t r e a t m e n t s , but t h e s e r e l a t i o n s h i p s were c o n s i d e r e d v e r y minor because o f t h e i r s m a l l c o n t r i b u t i o n t o the t o t a l sum o f squares (10.8% as compared t o 52.7% f o r n o n l i n e a r i n t e s t 2 ) . The e f f i c i e n c y o f g r a s s n i t r o g e n uptake over legumes was b e l i e v e d t o be the main r e a s o n f o r t h e s e r e l a t i o n s h i p s w h i c h g e n e r a l l y agreed w i t h t h e f i n d i n g s r e p o r t e d by Walker e t a l . , (1956); Evan (1977); Asher and Ozanne (1961). Aboveground legume biomass was a l s o s i g n i f i c a n t l y (P <_ 0.01) a f f e c t e d by the g r a s s and f e r t i l i z e r t r e a t m e n t s , a l t h o u g h the f e r t i l i z e r t r e a t m e n t was not s i g n i f i c a n t (P < 0.05) over the wide f e r t i l i z e r range. A n a l y s e s f u r t h e r r e v e a l e d t h a t the s i g n i f i c a n t r e l a t i o n s h i p s o f legume biomass w i t h t h e g r a s s t r e a t m e n t were n e g a t i v e l y l i n e a r i n b o t h f e r t i l i z e r r a n g e s . However, w i t h t h e f e r t i l i z e r t r e a t m e n t s (25 - 75 kg/ha) b o t h n e g a t i v e l i n e a r and n o n l i n e a r r e l a t i o n s h i p s can be p e r c e i v e d i n F i g u r e 5.19b. I t was o f p a r t i c u l a r i n t e r e s t t h a t legume biomass d i d not show a s i g n i f i c a n t r e l a t i o n s h i p w i t h f e r t i l i z e r t r e a t m e n t s i n t h e 10 - 100 kg/ha range , w h i l e i t had s i g n i f i -c a n t l i n e a r and n o n l i n e a r r e l a t i o n s h i p s w i t h t h e f e r t i l i z e r t r e a t m e n t s r a n g i n g from 25 - 75 kg/ha. These r e s u l t s i m p l i e d t h a t legume biomass was i n f l u e n c e d i n a complex manner by the narrow range f e r t i l i z e r t r e a t m e n t which p r o b a b l y r e f l e c t e d legume n i t r o g e n f i x a t i o n and i t s response t o many f a c t o r s as d i s c u s s e d i n S e c t i o n 5.3.2.3. Fu r t h e r m o r e , d e t a i l e d a n a l y s e s showed t h a t aboveground a l o n e o r t o t a l grass-legume biomass showed v a r i o u s complex s i g n i f i c a n t (P <0.05) r e l a t i o n s h i p s 108 w i t h g r a s s and f e r t i l i z e r t r e a t m e n t s (APPENDICES 1 and 2 ) . I n t e r p r e t a t i o n o f t h e s e complex r e l a t i o n s h i p s was not attempted because t h e y were b e l i e v e d t o be caused m a i n l y by the combina-t i o n o f r e l a t i o n s h i p s o b s e r v e d i n d i v i d u a l l y on the aboveground g r a s s o r legume biomasses. These r e s u l t s can be summarized as f o l l o w s : (a) Aboveground g r a s s biomass had l i n e a r ( p o s i t i v e ) r e l a t i o n s h i p s w i t h g r a s s s e e d i n g r a t e s and n i t r o g e n f e r t i l i z e r r a t e s (P <0.01). (b) Aboveground legume biomass had l i n e a r ( n e g a t i v e ) r e l a t i o n s h i p s w i t h g r a s s s e e d i n g r a t e s (P <0.01). (c) Aboveground legume biomass had b o t h l i n e a r ( n e g a t i v e ) and n o n l i n e a r r e l a t i o n s h i p s w i t h n i t r o g e n f e r t i l i z e r r a t e (25 --75 k g / h a ) . 5.3.3.2 S o i l n i t r o g e n There was a s i g n i f i c a n t (P < 0.05), p o s i t i v e l i n e a r r e l a t i o n s h i p o f ammonium and n i t r a t e l e v e l s w i t h n i t r o g e n f e r i l i z e r t r e a t m e n t s i n b o t h t e s t 1 and 2 (Tables 5.10 and 5.11). However, most of the n i t r o g e n a p p l i e d as f e r t i l i z e r was not a v a i l a b l e 112 days a f t e r s e e d i n g (grand means o f n i t r o g e n l e v e l s 4.4 ppm a t 112 days v s . 12.8 ppm a t 52 days f o r t e s t 1 and 2, r e s p e c t i v e l y ) . N i t r o g e n l e v e l s d e t e r m i n e d a t 52 days ( t e s t 2) showed s i g n i f i c a n t (P <0.01) n e g a t i v e l i n e a r as w e l l as q u a d r a t i c r e l a t i o n s h i p s , w i t h g r a s s s e e d i n g r a t e s (Table 5.11) and Appendix 2 ) . These r e s u l t s were p r e d i c t a b l e and may be e x p l a i n e d as f o l l o w s : (a) A p o s i t i v e l i n e a r r e l a t i o n s h i p w i t h n i t r o g e n f e r t i l i z e r r a t e by n i t r o g e n f e r t i l i z e r r e s i d u a l ( f e r t i l i z e r n o t t a k e n up by p l a n t s ) , and 109 (b) A n e g a t i v e l i n e a r r e l a t i o n s h i p w i t h t h e g r a s s s e e d i n g r a t e by e f f i c i e n t n i t r o g e n uptake by the g r a s s e s . I n c r e a s i n g n i t r o g e n uptake by t h e g r a s s e s was r e f l e c t e d i n t h e i r p r o p o r t i o n a l biomass ( S e c t i o n 5.3.3.1). These g e n e r a l t r e n d s can be c l e a r l y p e r c e i v e d i n F i g u r e s 5.27(a), 5.28(a), 5.33(b) and 5.34 ( b ) . 5.3.3.3 S o i l phosphorus There was a s i g n i f i c a n t (P <0.05), p o s i t i v e l i n e a r r e l a t i o n s h i p between phosphorus l e v e l s and n i t r o g e n f e r t i l i z e r t r e a t m e n t s ( i n NH^NO^ form) (Table 5.10 and Appendix 1 ) . T h i s t r e n d was p r o b a b l y a r e s u l t o f the reduced phosphorus f i x a t i o n i n a l k a l i n e s p o i l s caused by t h e a c i d i f i c a t i o n o f the a p p l i e d ammonium ( D i s c u s s e d p r e v i o u s l y i n S e c t i o n 5.2.2.1). There were a l s o .two-way i n t e r a c t i o n s between g r a s s s e e d i n g r a t e and n i t r o g e n f e r t i l i z e r r a t e , and three-way i n t e r a c t i o n s amongst a l l t h r e e t r e a t m e n t s (Table 5.10). S o i l phosphorus l e v e l s (grand mean 36.0 ppm), 112 days a f t e r s e e d i n g and det e r m i n e d f o r t e s t 1 o n l y , were g e n e r a l l y much h i g h e r t h a n those (0.3-3.7 ppm) o f the i n i t i a l f r e s h s p o i l used f o r t h e t e s t (Tables 5.9 and 5.12). T h i s i n c r e a s e was a p p a r e n t l y a r e s i d u a l e f f e c t o f the heavy i n i t i a l a p p l i c a -t i o n (200 kg/ha). The r e s u l t s f u r t h e r showed a s l i g h t i n v e r s e r e l a t i o n s h i p between phosphorus l e v e l s and n i t r o g e n f i x a t i o n o f legumes seeded a t 30 kg/ha, but not a t 15 kg/ha ( F i g u r e 5.24b and 5.28b), r e f l e c t i n g t he p a r t i c u l a r l y h i g h phosphorus demand f o r n i t r o g e n f i x a t i o n o f legumes seeded a t the h i g h e r 1 10 r a t e . A l t h o u g h n i t r o g e n f i x a t i o n has a h i g h phosphorus r e q u i r e -ment ( S c a l a n , 1928 and Munns, 1977), a v a i l a b l e phosphorus c o n c e n t r a t i o n s remained r e l a t i v e l y h i g h even a t t h e end o f the e x p e r i m e n t , i n d i c a t i n g t h a t phosphorus was p r o b a b l y not a l i m i t i n g f a c t o r i n t h e f i x i n g a c t i v i t y o f legumes i n t h e s e s t u d i e s . O v e r a l l r e l a t i o n s h i p s o f phosphorus w i t h the t h r e e t r e a t m e n t s are shown i n F i g u r e s 5.27b and 5.2 8b. 5.3.4 Treatment i n t e r a c t i o n s As a l r e a d y d i s c u s s e d a l l t h r e e t r e a t m e n t s showed s i g n i f i c a n t independent e f f e c t s on legume n i t r o g e n f i x a t i o n a t some time d u r i n g growth. S i g n i f i c a n t t r e a t m e n t i n t e r a c t i o n s on f i x a t i o n were a l s o a p parent (APPENDICES 1 and 2 ) . Admit-t e d l y , t h e s e i n t e r a c t i o n s are complex. However, the r e l a t i o n -s h i p s become more u n d e r s t a n d a b l e when examined i n the c o n t e x t o f some o f the o t h e r measurements, i . e . biomass o f g r a s s e s o r legumes, and s o i l n i t r o g e n . 5.3.4.1 Two-way i n t e r a c t i o n s A wide range (10 - 100 kg/ha) o f n i t r o g e n f e r t i l i z e r t r e a t m e n t had pronounced e f f e c t s on a c e t y l e n e r e d u c t i o n a c t i v i t y . The l o w e s t r a t e (10 kg/ha) g e n e r a l l y enhanced a c t i v i t y , w h i l e t h e h i g h e s t r a t e (100 kg/ha) s e v e r e l y d e p r e s s e d a c e t y l e n e r e d u c t i o n a t a l l g r a s s s e e d i n g r a t e s ( F i g u r e 5.18a). However, w i t h i n a narrow range (25 - 75 kg/ha of t e s t 2 ) , a d i f f e r e n t p a t t e r n was o b s e r v e d where the two t r e a t m e n t s showed a s i g n i f i c a n t i n t e r a c t i o n (P < 0.01) on a c e t y l e n e r e d u c t i o n . 111 At 25 kg/ha, a c e t y l e n e r e d u c t i o n was s i m i l a r a t a l l f o u r g r a s s s e e d i n g r a t e s and f e l l w i t h i n a range o f e t h y l e n e l e v e l s from 13.5 t o 15.5 ppm. A t 50 kg/ha, a c t i v i t y i n c r e a s e d i n a l l g r a s s s e e d i n g r a t e s (except 70 kg/ha i n which a c e t y l e n e r e d u c t i o n d e c l i n e d ) . A t 75 kg/ha n i t r o g e n , t h i s t r e n d was f u r t h e r extended e x c e p t a t 17.5 and 35 kg/ha g r a s s s e e d i n g r a t e s where a c t i v i t y d e c l i n e d d r a s t i c a l l y ( F i g u r e 5.18b). When t h e s e r e s u l t s f o r n i t r o g e n f i x a t i o n a c t i v i t y were compared w i t h t h o s e o f t h e legume aboveground biomass, a remarkable s i m i l a r i t y o f p a t t e r n was found i n b o t h ranges o f n i t r o g e n f e r t i l i z e r t r e a t m e n t s , 10 - 100 and 25 - 75 kg/ha ( F i g u r e s 5.18 - 19). The s i m i l a r i t y o f t h e p a t t e r n s was more s t r o n g l y pronounced o v e r t h e narrower f e r t i l i z e r r a n g e , and was f u r t h e r emphasized i n the i s o m e t r i c graphs shown i n F i g u r e s 5.23 - 26b and 5.29 — 32b. These f s u l t s can be summarized as f o l l o w s : (a) I n t h e pr e s e n c e o f g r a s s e s , n i t r o g e n f i x a t i o n a c t i v i t y was c l o s e l y r e l a t e d t o the aboveground biomass o f legumes a t any n i t r o g e n f e r t i l i z e r r a t e t e s t e d . (b) I n t h e p r e s e n c e o f g r a s s e s seeded a t 17.5 and 35 kg/ha legume n i t r o g e n f i x a t i o n was most a c t i v e a t 50 kg/ha n i t r o g e n f e r t i l i z e r . The aboveground legume biomass was a l s o h i g h w i t h t h e s e t r e a t m e n t c o m b i n a t i o n s , and (c) When legumes were grown i n m i x t u r e w i t h g r a s s e s seeded a t 70 kg/ha, n i t r o g e n f i x a t i o n d e c r e a s e d w i t h i n c r e a s i n g n i t r o g e n f e r t i l i z e r r a t e s . There were two s i g n i f i c a n t (P < 0.05 and 0.01) two-way i n t e r a c t i o n s i n v o l v i n g aboveground g r a s s biomass: between g r a s s and legume s e e d i n g r a t e s , and between g r a s s s e e d i n g r a t e C a H 4 (ppm) 4 0 32 24 16 1 1 2 17.5 35 (a) 10 • 50 100 N kg/ha (b) C 2 H 4 (ppm) 2 0 16 12 4 1 — i — 2 5 5 0 7 5 N kg/ha F i g u r e 5.18 Acety lene r e d u c t i o n of legumes t r e a t e d w i t h v a r i o u s grass seeding and n i t r o g e n f e r t i l i z e r r a t e s . (a) Pot t e s t 1. (b) Pot t e s t 2. Legumes were seeded at 15 and 30 k g / h a , and t h e i r data of a c e t y l e n e r e d u c t i o n (determined 99 days a f t e r seeding) were combined. D.Wt. (g) 20 16 A 12 (b) 1 7.5 35 70 — i — 25 50 75 N kg/ha F i g u r e 5.19 Aboveground biomass (g/pot) of legumes t r e a t e d v a r i o u s grass seeding and n i t r o g e n f e r t i l i z e r r a t e s . w i t h (a) Pot t e s t 1 (112 days a f t e r s e e d i n g ) , days a f t e r s eed ing ) . Legumes were seeded and t h e i r data of aboveground biomass were combined. (b) Pot t e s t at 15 and 30 2 (103 kg /ha , 114 and n i t r o g e n f e r t i l i z e r r a t e . The former accounted f o r 1.6 and 0.4% and t h e l a t t e r 11.5% and 9.0% o f t h e t o t a l sum o f squares f o r t e s t s 1 and 2, r e s p e c t i v e l y (Tables 5.10 - 11 and APPENDICES 1 and 2 ) . The former i n t e r a c t i o n c o u l d be con-s i d e r e d minor compared t o the l a t t e r because of the s m a l l c o n t r i b u t i o n t o t h e t o t a l sum o f s q u a r e s . The l a t t e r i n t e r -a c t i o n was a s t a t i s t i c a l a r t i f a c t because g r a s s s e e d i n g t r e a t -ments i n c l u d e d 0 kg/ha where no g r a s s e s were seeded and t h e i r biomass was n i l . O t h e r w i s e g r a s s biomass i n c r e a s e d l i n e a r l y w i t h i n c r e a s i n g n i t r o g e n f e r t i l i z e r r a t e s and g r a s s s e e d i n g r a t e s ( F i g u r e 5.20b). There were a l s o two s i g n i f i c a n t (P < 0.05 and 0.01) two-way i n t e r a c t i o n s i n v o l v i n g t h e aboveground legume biomass between legume s e e d i n g r a t e s and f e r t i l i z e r r a t e s , and between g r a s s s e e d i n g r a t e s and f e r t i l i z e r r a t e s : the former a c c o u n t i n g f o r 2.4% and the l a t t e r 13.6% o f the t o t a l sum o f squares ( t e s t 2, T a b l e 5.11). F u r t h e r a n a l y s i s showed t h a t the l a t t e r i n t e r a c t i o n c o n s i s t e d o f t h r e e t y p e s o f s i g n i f i c a n t (P <0.05 or 0.01) two-way i n t e r a c t i o n s : g r a s s l i n e a r x f e r t i l i z e r l i n e a r ( 8 . 7 % ) , g r a s s q u a d r a t i c x f e r t i l i z e r l i n e a r ( 2 . 6 % ) , and g r a s s q u a d r a t i c x f e r t i l i z e r d e v i a t i o n (1.3%) (Appendix 2 ) . The p e r c e n t a g e s r e p r e s e n t t o t a l sum o f squares accounted f o r by each i n t e r a c t i o n . The most i m p o r t a n t i n t e r a c t i o n was the f i r s t o f the t h r e e l i s t e d above, because i t accounted f o r the l a r g e s t p o r t i o n o f t h e t o t a l sum o f s q u a r e s . An i n t e r e s t i n g o b s e r v a t i o n from t h i s i n t e r a c t i o n was t h a t the aboveground legume biomass was maximized a t 17.5 and 35 kg/ha g r a s s s e e d i n g F i g u r e 5.20 Aboveground biomass (g/pot) of grasses t r e a t e d w i t h v a r i o u s n i t r o g e n f e r t i l i z e r r a t e s . (a) Pot t e s t 1 (112 days a f t e r s e e d i n g ) . (b) Pot t e s t 2 (103 days a f t e r s eed ing ) . Legumes were seeded at 15 and 30 kg /ha , and the data for aboveground grass biomass under these two legume seeding ra te s were combined. 116 w i t h 50 kg/ha n i t r o g e n f e r t i l i z e r ( F i g u r e 5.19). A comparison o f biomass components ( g r a s s e s and legumes) f u r t h e r r e v e a l e d t h a t t h e legume component c o n t r i b u t e d more t o t o t a l biomass th a n the g r a s s , a c c o u n t i n g f o r 75.0 and 57.1% (17.5 and 35 kg/ha g r a s s s e e d i n g r a t e s , r e s p e c t i v e l y ) o f t h e t o t a l (APPENDIX 4b ) . Moreover, th e maximized grass-legume biomass a t t h e s e two p o i n t s was m a i n l y a consequence o f the maximized legume biomass ( F i g u r e s 5.19 - 21b).* I t was i n t e r e s t i n g t o note t h a t the s o i l n i t r o g e n l e v e l a t t h e s e c o r r e s p o n d i n g p o i n t s d i d not f o l l o w the p a t t e r n s o f the legume biomass, s u g g e s t i n g t h a t s o i l n i t r o g e n was not a f a c t o r i n t h e grass-legume c o m p e t i t i o n , a p p a r e n t l y r e f l e c t i n g t h e a b i l i t y o f t h e legumes t o u t i l i z e s y m b i o t i c a l l y f i x e d n i t r o g e n ( F i g u r e 5.22). T h i s d i s c u s s i o n i s f u r t h e r d e v e l o p e d i n t h e f o l l o w i n g S e c t i o n . 5.3.4.2 Three-way i n t e r a c t i o n s I n t h e two-way i n t e r a c t i o n s d i s c u s s e d i n S e c t i o n 5.3.4. legume s e e d i n g r a t e p l a y e d a minor r o l e i n t h e s o i l and p l a n t f a c t o r s i n v e s t i g a t e d . However, t h i s t r e a t m e n t i n t e r a c t e d s i g n i f i c a n t l y w i t h t h e o t h e r two t r e a t m e n t s on t h o s e f a c t o r s (Tables 5.10 and 5.11). S t a t i s t i c a l a n a l y s e s r e v e a l e d 16 three-way i n t e r a c t i o n s o f t r e a t m e n t s on the s o i l and p l a n t f a c t o r s measured (APPENDICES 1 and 2 ) . Some o f t h e s e i n t e r -a c t i o n s were c o n s i d e r e d t o be o f l i t t l e i mportance because o f t h e i r minor c o n t r i b u t i o n t o t o t a l sums o f s q u a r e s . F i g u r e 5.21 Aboveground grass-legume biomass (g/pot) t r e a t e d w i t h v a r i o u s n i t r o g e n f e r t i l i z e r r a t e s . (a) Pot t e s t 1 (112 days a f t e r s e e d i n g ) . (b) Pot t e s t 2 (103 days a f t e r s e e d i n g ) . Legumes were seeded at 15 and 30 kg/ha and t h e i r data for aboveground biomass were combined. 1 18 NKU+I (ppm)| 30 2 0 10 (b) 17.5 35 70 25 —1— 5 0 75 N kg/ha F i g u r e 5.22 Combined ammonium and n i t r a t e l e v e l s of s p o i l under grass-legume stand t r e a t e d w i t h v a r i o u s n i t r o g e n f e r t i l i z e r r a t e s . (a) Pot t e s t 1 (112 days a f t e r s e e d i n g ) . (b) Pot t e s t 2 (52 days a f t e r s e e d i n g ) . Legumes were seeded at 15 and 30 kg/ha and the n i t r o g e n l e v e l s under these two seeding ra te s were combined. 119 Over a wide f e r t i l i z e r range (10 - 100 k g / h a ) , a t h r e e -way i n t e r a c t i o n (2.7%) was s i g n i f i c a n t o n l y f o r aboveground g r a s s biomass (Tables 5.10 and 5.11). However, w i t h i n a narrow f e r t i l i z e r range (25 - 75 kg/ha) three-way i n t e r a c t i o n s were s i g n i f i c a n t f o r a l l biomass d a t a a n a l y s e d . A n a l y s i s o f pot t e s t 2 d a t a showed s i g n i f i c a n t i n t e r a c t i o n s as f o l l o w s : (a) Aboveground g r a s s biomass, G q u a d r a t i c x L x F l i n e a r (0.2%) and G d e v i a t i o n x L x F l i n e a r ( 0 . 3 % ) , (b) Aboveground legume biomass, G q u a d r a t i c x L x F l i n e a r ( 2 . 3 % ) , (c) Aboveground grass-legume biomass, G q u a d r a t i c x L x F l i n e a r (4.0%) and G d e v i a t i o n x L x F d e v i a t i o n ( 2 . 1 % ) , and (d) Above- and belowground grass-legume biomass, 4 t y p e s o f t h r e e way i n t e r a c t i o n s ( l e s s t h a n 3.2% o f e a c h ) . F i g u r e s i n p a r e n t h e s i s a r e the sums o f squares e x p r e s s e d as a p e r c e n t a g e o f t o t a l sum o f s q u a r e s . These r e s u l t s r e v e a l e d i m p o r t a n t t r e n d s t h a t can be l i s t e d as f o l l o w s : (a) Three-way i n t e r a c t i o n s were more i m p o r t a n t i n the narrow f e r t i l i z e r range than i n t h e wide r a n g e , (b) The i n t e r a c t i o n s were more i m p o r t a n t f o r t h e component o f legume biomass t h a n f o r t h e g r a s s i n the narrow f e r t i l i z e r r a n g e , and (c) I n t e r a c t i o n s were more i m p o r t a n t and complex f o r the combined g r a s s and legume biomass t h a n f o r the legume o r t h e g r a s s biomass a l o n e . Three-way i n t e r a c t i o n s o c c u r r e d g e n e r a l l y a t around 50 kg/ha n i t r o g e n f e r t i l i z e r and i n d i c a t e d t h a t legume biomass was more s t r o n g l y i n f l u e n c e d by the i n t e r a c t i o n t han t h a t o f the g r a s s e s . A c e t y l e n e r e d u c t i o n based on p o t t e s t 1 d e c r e a s e d a t 15 kg/ha legume ( F i g u r e 5.23b) w h i l e i t i n c r e a s e d a t 30 kg/ha 1 2 0 ( F i g u r e 5.24b) w i t h i n c r e a s i n g s e e d i n g r a t e s o f g r a s s e s f e r t i l i z e d a t 50 kg/ha. The l a t t e r r e s u l t was t h e r a t i o n a l e f o r d e v e l o p i n g pot t e s t 2 i n w h i c h t r e a t m e n t s were m o d i f i e d t o f o c u s around the 50 kg/ha f e r t i l i z e r r a t e . The r e s u l t s o f p o t t e s t 2 r e v e a l e d t h a t a l l t h r e e t r e a t m e n t s i n t e r a c t e d s i g n i f i c a n t l y (P <0.01) on a c e t y l e n e r e d u c t i o n (99 d a y s ) , a c c o u n t i n g f o r up t o 8.7% o f t h e t o t a l sum o f squares (Table 5.11). T h i s i n t e r a c t i o n was almost as i m p o r t a n t as g r a s s t r e a t m e n t (9.5%) i n s h e d d i n g a d d i t i o n a l l i g h t on t h e c o m p l e x i -t i e s and dynamics o f legume n i t r o g e n f i x a t i o n . F u r t h e r m o r e , the i n t e r a c t i o n s are d i s c u s s e d a g a i n s t t h e base o f legume s e e d i n g r a t e s s i n c e t h e s e r a t e s changed o n l y from 15 t o 30 kg/ha w h i c h made a comparison e a s i e r . A l l i s o m e t r i c graphs i n t h i s S e c t i o n were drawn on t h e base o f t h e two legume s e e d i n g r a t e s ( F i g u r e s 5.23 - 3 4 ) . I n g e n e r a l an i n c r e a s e i n the legume s e e d i n g r a t e from 15 t o 30 kg/ha a f f e c t e d a l l s o i l and p l a n t f a c t o r s s t u d i e d . I n terms o f grand means, i t s e f f e c t s on the f a c t o r s were r e l a - . t i v e l y moderate: e.g. d e c r e a s e o f aboveground g r a s s biomass by 19% and i n c r e a s e o f a c e t y l e n e r e d u c t i o n by 13%. I n o r d e r t o examine each change o f t h e s o i l and p l a n t f a c t o r s i n d e t a i l , i t s d i s t r i b u t i o n w i t h i n a c e r t a i n s o i l o r p l a n t f a c t o r was computed. As shown i n T a b l e 5.13, t h e i n c r e a s e i n legume s e e d i n g r a t e a f f e c t e d the f a c t o r s i n a d i f f e r e n t magnitude a c c o r d i n g t o t h e o t h e r two .treatment c o m b i n a t i o n s . A c l o s e e x a m i n a t i o n o f t h e d i s t r i b u t i o n r e v e a l e d the f o l l o w i n g : T a b l e 5 . 1 3 C h a n g e s o f y i e l d v a r i e s I n c u r r e d b y c h a n g i n g l e g u m e s e e d i n g r a t e f r o m 15 t o 3 0 K g / n a I F f a c t o r I n v e s t i g a t e d . c o m p u t a t i o n f o r m u l a N f e r t i 1 i z e r r a t e ( k q / h a ) g r a s s s e e d i n g r a t e 0 1 7 . 5 3 5 7 0 g r a s s b i o m a s s 1 c h a n g e ( g / p o t ) B - A 21 5 0 2 5 0 . 0 0 . 0 0 . 0 - 2 . 8 - 1 . 4 -1 . 0 - 0 . 2 - 2 . 7 -1 . 0 I I l e g u m e b i o m a s s c h a n g e ( g / p o t ) D - C 7 5 5 0 2 5 - 2 . 7 - 0 . G 5 . 2 -1 . 0 6 . 2 3 . 2 - 0 . 6 - 0 . 3 6 . 3 I I I g r a s s - l e g u m e b i o m a s s c h a n g e ( g / p o t ) 7 5 5 0 2 5 - 2 . 7 - 0 . 6 5 . 2 - 3 . 7 4 . 8 2 . 2 5 . 0 1 . 0 - 0 . 1 - 0 . 8 - 3 . 0 5 . 3 I V s o i l n i t r o g e n c h a n g e ( 5 2 d a y s . H - G p p m ) 7 5 5 0 2 5 - 4 . 8 - 2 . 0 - 0 . 7 a c e t y l e n e r e d u c t i o n c h a n g e ( 9 9 d a y s , p p m ) J - I 7 5 5 0 2 5 •10 0 9 - 2 8 - 1 2 . - 2 7 V I a c e t y l e n e r e d u c t i o n e f f i c i e n c y ' c h a n g e ( p p m / g ) ( D - J ) - ( C - I ) I5-5 0 2 5 - 0 . 1 0..1 - 0 . 4 0 . 2 0 . 2 - 0 . 3 0 . 8 - 0 . 3 - 0 . 1 1 . A l l b i o m a s s d a t a f o r a b o v e g r o u n d m a t e r i a l . 2 . A c e t y l e n e r e d u c t i o n ( p p m ) d i v i d e d b y l e g u m e b i o m a s s ( g / p o t ) . 3 . M a t r i c e s A , B . . . . J a l s o r e p r e s e n t t h e f i g u r e s u s e d t o _ ^ c o n s t r u c t F i g u r e s 5 . 3 0 a . 5 . 3 2 a , . . . , 5 . 3 1 b , r e s p e c t i v e l y . ^ C h a n g e s o f y i e l d v a r i a b l e s f o r a c e r t a i n f a c t o r w e r e o b t a i n e d b y s u b t r a c t i n g a s e t o f y i e l d v a r i a b l e s r e c o r d e d a t 1 5 k g / h a f r o m t h o s e a t 3 0 k g / h a l e g u m e s e e d i n g r a t e s . E a c h m a t r i x r e p r e s e n t s t h e c h a n g e s o f y i e l d v a r i a b l e s f o r a c e r t a i n f a c t o r i n v e s t i g a t e d , w h e r e A , B J ' a r e s u c h a s e t o f d a t a l i s t e d 1 n A P P E N D I X 3 . 122 (a) Aboveground g r a s s biomass d e c r e a s e d r e l a t i v e l y u n i f o r m l y a t a l l t r e a t m e n t c o m b i n a t i o n s , i n d i c a t i n g g e n e r a l l y weak c o m p e t i t i o n between the g r a s s e s and the legumes. There was one e x c e p t i o n (at 35 kg/ha g r a s s and 75 kg/ha n i t r o g e n ) where the g r a s s biomass i n c r e a s e d by 0.8 g/ pot ( m a t r i x I i n Table 5.13), (b) Aboveground legume biomass tended t o i n c r e a s e more a t lower n i t r o g e n f e r t i l i z e r r a t e s . N o n e t h e l e s s a l a r g e i n c r e a s e o f t h e legume biomass by 4.2 g/pot was r e a l i z e d a t 35 kg/ha g r a s s and 75 kg/ha n i t r o g e n ( m a t r i x I I ) , (c) Changes i n aboveground combined grass-legume biomass were c l o s e l y r e l a t e d t o changes i n legume biomass ( m a t r i c e s I I and I I I ) , (d) Changes i n s o i l n i t r o g e n l e v e l were not always a s s o c i -a t e d w i t h any change i n g r a s s , legume o r t o t a l biomass, a f f i r m i n g t h a t s o i l n i t r o g e n was not always a f a c t o r m e d i a t i n g c o m p e t i t i o n between the g r a s s e s and the legumes ( m a t r i c e s I , I I and I V ) , (e) Changes i n a c e t y l e n e r e d u c t i o n were r e l a t e d p o s i t i v e l y t o t h e change i n legume biomass, i . e . a l a r g e i n c r e a s e i n a c t i v i t y was g e n e r a l l y accompanied by a p r o p o r t i o n a l i n c r e a s e i n legume biomass ( m a t r i x V ) , and (f) Changes i n a c e t y l e n e r e d u c t i o n e f f i c i e n c y were somewhat n e g a t i v e l y r e l a t e d t o t h e change i n s o i l n i t r o g e n l e v e l , and p o s i t i v e l y t o the change i n a c e t y l e n e r e d u c t i o n ( m a t r i c e s I V - V I ) . T h i s i n d i c a t e d t h a t t h e e f f i c i e n c y was weakly a f f e c t e d by t h e s o i l n i t r o g e n , and t h a t an e f f i c i e n c y i n c r e a s e was one o f r e a s o n s f o r the r e d u c -t i o n i n c r e a s e o f m a t r i x V. I t s h o u l d be r e c a l l e d here t h a t t h e s e summaries ( a - f ) ar e based on changes i n c u r r e d by i n c r e a s i n g t h e legume s e e d i n g r a t e and s h o u l d not be c o n f u s e d w i t h the e a r l i e r d i s c u s s i o n s o f t h e t h r e e t r e a t m e n t e f f e c t s on a c e t y l e n e r e d u c t i o n a c t i v i t y . Legume s t a n d I n a pure legume s t a n d ( t e s t 2 ) , d o u b l i n g o f the s e e d i n g r a t e r e s u l t e d i n d e c r e a s e d s o i l n i t r o g e n , legume biomass, a c e t y l e n e r e d u c t i o n and r e d u c t i o n e f f i c i e n c y , a t the h i g h e r (75 kg/ha) n i t r o g e n f e r t i l i z e r r a t e ( m a t r i c e s I I - V I i n T a b l e 123 5.13). However, a t t h e lower (25 kg/ha) f e r t i l i z e r r a t e the d o u b l i n g was f o l l o w e d by i n c r e a s e s i n legume biomass, a c e t y l e n e r e d u c t i o n and r e d u c t i o n e f f i c i e n c y accompanied by a s l i g h t d e c r e a s e o f s o i l n i t r o g e n (0.7 ppm). These d a t a i m p l i e d t h a t t h e 75 kg/ha r a t e was somewhat d e t r i m e n t a l t o a pure s t a n d o f legumes seeded a t 30 kg/ha ( F i g u r e s 5.29 - 32b). A comparison o f F i g u r e s 5.30b and 5.32b r e v e a l e d t h a t a t 15 kg/ha legume biomass i n c r e a s e d l i n e a r l y as t h e n i t r o g e n f e r t i l i z e r was i n c r e a s e d from 25 t o 75 kg/ha, w h i l e a t 30 k g / ha i t remained r e l a t i v e l y s t a b l e . T h e r e f o r e a t the h i g h e r f e r t i l i z e r l e v e l the biomass o f legumes a t 30 kg/ha was l e s s t h a n t h a t a t 15 kg/ha, and v i c e v e r s a . B i o l o g i c a l l y t h i s phenomenon can be e x p l a i n e d i n terms o f legume c o m p e t i t i o n . Under c o n d i t i o n s o f denser p o p u l a t i o n s and h i g h e r n i t r o g e n f e r t i l i t y , legumes were b e l i e v e d t o have shown e i t h e r p l a s t i -c i t y and/or Sukatschew r e s p o n s e s 1 (Harper, 1977 and Sukatschew, 1928) . These d i f f e r e n c e s i n aboveground legume biomass a f f e c t e d n i t r o g e n f i x a t i o n i n a s i m i l a r manner, but were more pronounced ( m a t r i c e s I I and V ) , r e s u l t i n g i n lower r e d u c t i o n e f f i c i e n c y a t h i g h e r n i t r o g e n f e r t i l i t y and v i c e v e r s a ( m a t r i x V I ) . T h e r e f o r e the denser legume p o p u l a t i o n had severe n e g a t i v e e f f e c t s , a t h i g h e r n i t r o g e n f e r t i l i t y , on biomass, a c e t y l e n e r e d u c t i o n and r e d u c t i o n e f f i c i e n c y . S o i l n i t r o g e n l e v e l s were 1 P l a s t i c i t y r e s p o n s e : r e d u c t i o n i n i n d i v i d u a l p l a n t s i z e t o dense p o p u l a t i o n i n f e r t i l e s o i l s . Sukatschew r e s p o n s e : s i m i l a r r e d u c t i o n i n i n d i v i d u a l p l a n t number, i . e . h i g h e r m o r t a l i t y i n f e r t i l e t h a n poor s o i l s . 124 g e n e - a l l y lower under legumes seeded a t 30 kg/ha t h a n under t h o s e a t 15 kg/ha ( m a t r i x IV and F i g u r e s 5.33 - 34b). Lower n i t r o g e n l e v e l s were p o s i t i v e l y c o r r e l a t e d t o the c o r r e s p o n d -i n g biomass o n l y a t t h e h i g h e r n i t r o g e n f e r t i l i z e r r a t e but not a t 25 kg/ha. That lower n i t r o g e n l e v e l s n o r m a l l y enhance legume n i t r o g e n f i x a t i o n ( R u s s e l l , 197 3) would not a p p l y i n t h i s case s i n c e lower n i t r o g e n l e v e l s were not a s s o c i a t e d w i t h h i g h e r n i t r o g e n f i x a t i o n ( m a t r i c e s I V - V I ) . These d a t a a l s o s u p p o r t e d t h e c o n t e n t i o n t h a t legume c o m p e t i t i o n i n t h e h i g h p o p u l a t i o n d e n s i t y was a g g r a v a t e d under h i g h e r f e r t i l i t y where t h e legumes responded by e i t h e r r e d u c i n g i n d i v i d u a l p l a n t s i z e o r p l a n t numbers. A comparison o f aboveground legume biomass under d i f -f e r e n t f e r t i l i z e r regimes ( t e s t 1 and 2) showed t h a t t h e legumes seeded a t 30 kg/ha had a s i m i l a r p a t t e r n , w h i l e t h o s e seeded a t 15 kg/ha were more v a r i a b l e i n response ( F i g u r e s 5.26b v s . 5.32b and 5.25b v s . 5.30b). The legumes seeded a t 15 kg/ha i n t e s t 1 produced l e s s biomass a t 100 kg/ha n i t r o g e n and more a t 10 kg/ha t h a n one would e x p e c t from t h e r e s u l t s o f t e s t 2. The former r e s u l t ( l e s s biomass a t 100 kg/ha) may p o s s i b l y be a consequence o f n i t r i t e t o x i c i t y because t h e ammonium n i t r a t e a p p l i e d a t 100 kg/ha was h i g h c o n s i d e r i n g t h e n a t u r e o f t h e s p o i l ( a l k a l i n e and low o r g a n i c m a t t e r c o n t e n t ) . N i t r i t e t o x i c i t y w i l l be c o n s i d e r e d l a t e r i n t h i s S e c t i o n . The o b s e r v a t i o n o f h i g h e r biomass p r o d u c t i o n a t 10 kg/ha n i t r o g e n f e r t i l i z e r appeared t o be a consequence o f c o r r e s p o n d -i n g d i f f e r e n c e s i n n i t r o g e n f i x a t i o n . Legumes seeded a t 15 . 125 kg/ha and f e r t i l i z e d a t 10 kg/ha produced more biomass and h i g h e r a c e t y l e n e r e d u c t i o n , 15.8 g/pot and 32.5 ppm, r e s p e c -t i v e l y t han t h o s e seeded a t 15 kg/ha and f e r t i l i z e d a t 25 kg/ha; 11.0 g/pot and 10.8 ppm, r e s p e c t i v e l y ( F i g u r e s 5.23b, 5.25b, 5.29b and 5.30b). The i n c r e a s e d n i t r o g e n f i x a t i o n a t 10 kg/ha might have r e s u l t e d i n t h e l a r g e r n e t biomass a t 10 kg/ha r e l a t i v e t o t h a t a t 25 kg/ha n i t r o g e n . Grass-legume s t a n d I n t h e grass-legume s t a n d f e r t i l i z e d a t 75 kg/ha n i t r o g e n , a d r a s t i c d e c r e a s e i n s o i l n i t r o g e n by 7.5 ppm (37%) o c c u r r e d a t t h e 35 kg/ha g r a s s s e e d i n g r a t e as the legume s e e d i n g r a t e was d o u b l e d . However, t h i s d e c r e a s e i n s o i l n i t r o g e n was a s s o c i a t e d w i t h 0.8 and 4.2 g/pot i n c r e a s e s o f g r a s s and legume biomass, r e s p e c t i v e l y ( m a t r i c e s I - I V i n T a b l e 5.13, and F i g u r e s 5.30 and 5.32 - 34). These d a t a i m p l i e d t h a t the g r a s s e s and legumes underwent a c o o p e r a t i v e i n t e r a c t i o n and t h a t s o i l n i t r o g e n a t 75 kg/ha was not a l i m i t i n g f a c t o r t o p l a n t growth f o r e i t h e r t h e g r a s s e s o r the legumes seeded a t 35 and 30 kg/ha, r e s p e c t i v e l y . At 17.5 and 70 kg/ha g r a s s s e e d i n g r a t e s , s o i l n i t r o g e n a c t u a l l y i n c r e a s e d by 2.5 and 2.2 ppm, r e s p e c t i v e l y ( m a t r i x I V ) . I t was t h e r e f o r e u n l i k e l y t h a t t h e g r a s s e s and legumes were competing f o r s o i l n i t r o g e n a t a l l . Moreover, t h e f a c t t h a t b o t h t h e c o r r e s p o n d -i n g g r a s s and legume .biomass d e c l i n e d suggested t h a t t h e y were competing f o r a f a c t o r o t h e r t h a n s o i l n i t r o g e n ; l i g h t was most l i k e l y t o be such a f a c t o r . I t i s known t h a t T r i f o l i u m 126 spp. a r e l i g h t - d e m a n d i n g (Lnager, 1973). I f l i g h t was the p r i m a r y c o m p e t i t i v e f a c t o r , the mode o f c o m p e t i t i o n p r o b a b l y v a r i e d between t h e two g r a s s s e e d i n g r a t e s as the legume s e e d i n g r a t e d o u b l e d . At 17.5 kg/ha g r a s s and 75 kg/ha n i t r o g e n , t h e h e i g h t s o f g r a s s e s and legumes were s i m i l a r , f o r c i n g them t o compete w i t h each o t h e r f o r l i g h t w i t h i n the same l i m i t e d space ( F i g u r e 5.17). The d o u b l i n g o f legume s e e d i n g r a t e p r o b a b l y r e s u l t e d i n u n f a v o r a b l e c o n d i t i o n s f o r b o t h the g r a s s e s and t h e legumes. Decreased g r a s s and legume biomass, a c e t y l e n e r e d u c t i o n and r e d u c t i o n e f f i c i e n c y o c c u r r e d under t h e s e c o n d i t i o n s . At 70 kg/ha g r a s s and 75 kg/ha f e r t i l i z e r , t h e g r a s s e s were t a l l e r t h a n the legumes ( F i g u r e 5.17). D o u b l i n g t h e legume s e e d i n g r a t e caused d e c r e a s e s i n b o t h g r a s s and legume biomass, y e t a c e t y l e n e r e d u c t i o n and r e d u c t i o n e f f i c i e n c y i n c r e a s e d by 2.9 ppm and 0.8 ppm/g, r e s p e c t i v e l y . The above r i s e i n r e d u c t i o n e f f i c i e n c y may have been a c h i e v e d by t h e use o f a d d i t i o n a l s u r f a c e a r e a f o r l i g h t i n t e r c e p t i o n " ^ by t h e h i g h e r d e n s i t y o f legumes seeded a t 30 kg/ha. The mechanisms by whi c h the legumes a c h i e v e d t h i s was not a p p a r e n t , but t h e d i f f e r e n c e i n canopy s t r u c t u r e s and l e a f o r i e n t a t i o n between t h e two might have c o n t r i b u t e d t o t h e a b i l i t y o f the legume t o r a i s e t h e r e d u c t i o n e f f i c i e n c y as d i s c u s s e d by Haynes (1980). The g r a s s and legume canopy tended t o e x t e n d beyond the l i m i t e d a r e a s o f p o t s , c o m p l i c a t i n g the c o m p e t i t i o n f o r l i g h t between t h e two ( F i g u r e s 5.15 - 1 7 ) . 12? I n grass-legume s t a n d s f e r t i l i z e d a t 50 o r 25 kg/ha where g r a s s growth was more l i m i t e d t h a n t h a t a t 75 kg/ha n i t r o g e n f e r t i l i z e r , legumes were c o n s i d e r e d t o have t a k e n an advantage o f t h e lower g r a s s s t a t u r e f o r improved l i g h t i n t e r -c e p t i o n . At 50 kg/ha f e r t i l i z e r , the legumes appeared t o be s u c c e s s f u l i n competing w i t h g r a s s e s seeded a t 17.5 and 35 kg/ha showing i n c r e a s e d biomass, a c e t y l e n e r e d u c t i o n and r e d u c t i o n e f f i c i e n c y w h i l e t h e g r a s s biomass d e c l i n e d s l i g h t l y as t h e legume s e e d i n g r a t e was d o u b l e d ( F i g u r e s 5.29 - 3 2 ) . T h e r e f o r e , t h e legume c o n t r i b u t i o n t o t o t a l biomass i n c r e a s e d by 12.5 and 9.6% t o 80.8 and 61.8% i n t h e p r e s ence o f g r a s s e s seeded a t 17.5 and 35 kg/ha, r e s p e c t i v e l y (Appendix 4 ) . C o r r e s p o n d i n g d e c r e a s e s i n s o i l n i t r o g e n by 0.8 and 2.1 ppm, may be used t o argue t h a t legume performance i n n i t r o g e n uptake a t t h e i r h i g h e r s e e d i n g r a t e i n v o l v e d the c o n f o u n d i n g f a c t o r s o f l i g h t and s o i l n i t r o g e n . I n c r e a s e d l i g h t i n t e r c e p t i o n and d e c r e a s e d s o i l n i t r o g e n a r e b o t h f a v o r a b l e c o n d i t i o n s f o r n i t r o g e n f i x a t i o n ( S p r e n t , 1979) . A t 25 kg/ha f e r t i l i z e r n i t r o g e n may have been d e f i c i e n t f o r growth r e q u i r e m e n t s o f t h e g r a s s e s ; d o u b l i n g o f the legume s e e d i n g r a t e r e s u l t e d i n g r a s s biomass d e c r e a s e s and s o i l n i t r o g e n i n c r e a s e s ( m a t r i c e s I and I V ) . The c o r r e s p o n d i n g legume biomass i n c r e a s e d but not t h e r e d u c t i o n e f f i c i e n c y . The d e c l i n e i n r e d u c t i o n e f f i c i e n c y m i g h t be caused by i n c r e a s e d c o m p e t i t i o n w i t h i n the legumes f o r l i g h t as t h e i r s e e d i n g r a t e was d o u b l e d . 128 The above r e s u l t s o b t a i n e d a t 50 kg/ha n i t r o g e n f e r t i -l i z e r ( t e s t 2) were d i f f e r e n t from th e c o r r e s p o n d i n g r e s u l t s o f t e s t 1. I n t e s t 1, near m i x i m i z a t i o n o f grass-legume b i o -mass and a c e t y l e n e r e d u c t i o n o c c u r r e d a t 35 kg/ha g r a s s e s i n s t e a d o f t h e 17.5 kg/ha l e v e l i n t e s t 2 ( F i g u r e s 5.24 and 5.26). I n t e s t 2, n i t r o g e n f e r t i l i z e r r a t e s were 25 - 75 kg/ha and c l o s e r t o t h e b e s t c o m b i n a t i o n d i s c u s s e d above t h a n th o s e (10 - 100 kg/ha) of t e s t 1. Moreover, t e s t 2 had f i v e r e p l i -c a t i o n s , w h i l e t e s t 1 had o n l y t h r e e . C o n s e q u e n t l y , th e r e s u l t s o f t e s t 2 were c o n s i d e r e d t o be a more r e l i a b l e r e p r e -s e n t a t i o n o f t h e r e l a t i o n s h i p s t h a n th o s e o f t e s t 1. I t was c l e a r l y shown (based on t e s t 2) t h a t a combina-t i o n o f g r a s s (17.5 kg/ha) legume (30 kg/ha) and n i t r o g e n f e r t i l i z e r (50 kg/ha) was most f a v o r a b l e compared t o t h e o t h e r c o m b i n a t i o n s . I n t h i s c o m b i n a t i o n , aboveground grass-legume biomass (23,4 g/pot) was maximized as w e l l as a c e t y l e n e r e d u c t i o n (21.6 ppm) ( F i g u r e s 5.31b and 5.34a). F u r t h e r m o r e , t h e maximized grass-legume biomass was a t t r i b u t a b l e t o t h e maximized legume biomass ( F i g u r e 5.32b). A p p a r e n t l y , t h e legumes became v e r y c o m p e t i t i v e a t t h i s h i g h s e e d i n g r a t e (30 k g / h a ) , p o s s i b l y because o f t h e c o n f o u n d i n g e f f e c t s o f the l i g h t i n t e r c e p t i o n i n c r e a s e and s o i l n i t r o g e n d e c r e a s e , b o t h o f which would l i k e l y enhance legume n i t r o g e n f i x a t i o n . N i t r i t e t o x i c i t y S e v e r a l i n s t a n c e s o f n i t r i t e t o x i c i t y t o p l a n t s from o x i d a t i o n o f ammonium under a l k a l i n e c o n d i t i o n s have been 129 r e p o r t e d ( B l a c k , 1968). Because th e s p o i l s i n t h e s e t e s t s were s l i g h t l y a l k a l i n e (pH 7.3 - 7.9 i n T a b l e 5.9) and n i t r o g e n was a p p l i e d as ammonium n i t r a t e , t h e p o s s i b i l i t y o f n i t r i t e t o x i c i t y t o t h e t e s t p l a n t s has been c o n s i d e r e d . P a u l and P o l l e (1965), w o r k i n g on l e t t u c e i n a c a l c a r e o u s loam s o i l (pH 7.7), found t h a t ammonium n i t r a t e a p p l i e d a t 125 ppm c o n t a i n e d enough ammonium t o be o x i d i z e d i n t o p h y t o t o x i c n i t r i t e . The maximum amount o f ammonium n i t r a t e used i n t h i s s t u d y was 100 kg/ha o r 64 ppm 1, r o u g h l y h a l f o f t h e 125 ppm t h e y used. T h e r e f o r e i t was p o s s i b l e t h a t t h e growth of t h e t e s t p l a n t s , p a r t i c u l a r l y a t the h i g h e r n i t r o g e n f e r t i l i z e r r a t e , may have been reduced by p h y t o t o x i c n i t r i t e . P a u l and P o l l e (1965) a l s o r e p o r t e d an i n c r e a s e i n t h e p h y t o t o x i c i t y o f n i t r i t e a t lower p o p u l a t i o n d e n s i t i e s o f t h e l e t t u c e . T h e r e f o r e , t h e p o t e n t i a l f o r p h y t o t o x i c i t y o f n i t r i t e was p r o b a b l y i n c r e a s e d a t lower g r a s s and/or legume s e e d i n g r a t e s . Indeed, such n i t r i t e t o x i c i t y appeared t o o c c u r i n pure s t a n d legumes seeded a t 15 kg/ha where u n e x p l i c a b l y low biomass measurements were o b s e r v e d a t t h e 100 kg/ha n i t r o g e n f e r t i l i z e r r a t e as compared t o t h e biomass o f legumes i n pure s t a n d , seeded a t 15 kg/ha and f e r t i l i z e d a t 75 kg/ha ( F i g u r e s 5.25b and 5.30b). Legume biomass i n denser p o p u l a t i o n s (seeded a t 30 k g / h a ) , however, d i d not show such a r e d u c t i o n ( F i g u r e s 5.26b and 5.32b). The legumes o f t h e denser p o p u l a t i o n p r o b a b l y 1 N i t r o g e n f e r t i l i z e r r a t e x p o t a r e a T s p o i l w e i g h t / p o t = 1 0 3 ug/cm 2 x 572 cm 2 r (9 x 10 3g) = 64 ppm. 130 C2H4 (a) ( b ) Figure 5.23 Acetylene reduction a c t i v i t y of legumes seeded at kg/ha with various grass seeding and nitrogen f e r t i l i z e r rates (pot test 1 ). (a) 80 days a f t e r s e e d i n g . (b) 99 days a f t e r s e e d i n g . 131 F i g u r e 5.24 Acety lene r e d u c t i o n a c t i v i t y of legumes seeded at 30 kg/ha w i t h v a r i o u s grass seeding and n i t r o g e n f e r t i l i z e r r a te s (pot t e s t 1 ) . (a) 80 days a f t e r seed ing ; (b) 99 days a f t e r seed ing . 132 F i g u r e 5.25 Aboveground biomass 15 kg/ha (pot t e s t 1 ) . (a) Grass biomass ( g / p o t ) . (b) Measured 112 days a f t e r seeding of grasses and legumes seeded at Legume biomass ( g / p o t ) . 133 (a) (b) F i g u r e 5.26 Aboveground biomass of grasses and legumes seeded at 30 kg/ha (pot t e s t 1 ) . (a) Grass biomass ( g / p o t ) . (b) Legumes biomass ( g / p o t ) . Measured 112 days a f t e r s eed ing . 134 F i g u r e 5.27 Ammonium, n i t r a t e and phosphorus l e v e l s of s p o i l s under the stand of grasses at v a r i o u s seeding ra te s and legumes seeded at 15 kg/ha (pot t e s t 1 ) . (a) Ammonium and n i t r a t e . (b) Phosphorus. Measured 112 days a f t e r s eed ing . 135 F i g u r e 5.28 Ammonium, n i t r a t e and phosphorus l e v e l s of s p o i l under the stand of grasses at v a r i o u s seeding r a te s and legumes seeded at 30 kg/ha (pot t e s t 1 ) . (a) Ammonium and n i t r a t e . (b) Phosphorus. Measured 112 days a f t e r s eed ing . 136 (a) (b) F i g u r e 5.29 Acety lene r e d u c t i o n a c t i v i t y of legumes seeded at 15 kg/ha w i t h v a r i o u s grass seeding and n i t r o g e n f e r t i l i z e r ra te s (pot t e s t 2 ) . (a) 78 days a f t e r s eed ing . (b) 99 days a f t e r s eed ing . 137 F i g u r e 5.30 Aboveground biomass of grasses at v a r i o u s seeding r a t e s and legumes seeded at 15 kg/ha (pot t e s t 2 ) . (a) Grass biomass ( g / p o t ) . (b) Legumes biomass ( g / p o t ) . Measured 103 days a f t e r seeding. 138 Figure 5.31 Acetylene reduction a c t i v i t y of legumes seeded at 30 kg/ha with various grass seeding and nitrogen f e r t i l i z e r rates (pot test 2). (a) 78 days a f t e r seeding. (b) 99 days a f t e r seeding. F i g u r e 5.32 Aboveground biomass of g r a s s e s a t v a r i o u s s e e d i n g r a t e s and legumes seeded a t 30 kg/ha (pot t e s t 2 ) . (a) G r a s s biomass ( g / p o t ) . (b) Legume biomass ( g / p o t ) . Measured 103 days a f t e r s e e d i n g . F i g u r e 5.33 Aboveground grass-legume biomass and ammonium + n i t r a t e l e v e l s ; legumes seeded a t 15 kg/ha (pot t e s t 2 ) . (a) Grass-legume biomass, 103 days ( g / p o t ) . (b) Ammonium and n i t r a t e , 52 days. ( a ) ( b ) F i g u r e 5 . 3 4 A b o v e g r o u n d g r a s s - l e g u m e b i o m a s s a n d a m m o n i u m + n i t r a t e l e v e l s ; l e g u m e s s e e d e d a t 30 k g / h a ( p o t t e s t 2 ) . ( a ) G r a s s - l e g u m e b i o m a s s , 103 d a y s . ( g / p o t ) . ( b ) A m m o n i u m a n d n i t r a t e , 52 d a y s . 14-2 absorbed t h e ammonium a p p l i e d f a s t e r than t h o s e o f d e c r e a s e d p o p u l a t i o n d e n s i t y r e s u l t i n g i n l e s s n i t r i t e a c c u m u l a t i o n and reduced p o t e n t i a l f o r n i t r i t e p h y t o t o x i c i t y . Because o f the many s i g n i f i c a n t i n t e r a c t i o n s o c c u r r i n g , the p r e c i s e i m p l i c a -t i o n s o f p o t e n t i a l n i t r i t e t o x i c i t y i n t h e performance o f t e s t p l a n t s c o u l d not be d e t e r m i n e d . However, the above phenomenon s h o u l d be c o n s i d e r e d i n i n t e r p r e t i n g t h e performance o f t e s t p l a n t s a t h i g h e r n i t r o g e n f e r t i l i z e r r a t e s and lower s e e d i n g r a t e s , p a r t i c u l a r l y i n pure s t a n d s o f legumes. 5.4 F i e l d t e s t s F i e l d t e s t s were i n i t i a t e d t o i n v e s t i g a t e s o i l f a c t o r s and the dynamics o f p l a n t communities on t h e l i m i t e d a r e a s r e c l a i m e d from 1974 t o 1978. Of p a r t i c u l a r i n t e r e s t i n t h i s s t u d y was t h e impact o f t h e o p e r a t i o n a l f e r t i l i z e r management on t h e s o i l and p l a n t s . Because o f the s m a l l a r e a s i n c l u d e d i n t h e t e s t p l o t s and t h e l a r g e v a r i a t i o n i n p l a n t c o m p o s i t i o n w i t h i n each o f t h e r e c l a i m e d a r e a s o f d i f f e r e n t age, t h e r e s u l t s o f t h i s i n v e s t i g a t i o n w i l l be r e l a t e d t o tho s e o f the f i e l d s u r v e y t o improve t h e o v e r a l l assessment o f d a t a . The f o l l o w i n g r e s u l t s and d i s c u s s i o n were d e r i v e d p r i n c i p a l l y from a n a l y s e s o f samples c o l l e c t e d d u r i n g J u l y 11-22, 1980. Samples were c o l l e c t e d b o t h b e f o r e and a f t e r t h e f e r t i l i z e r t r e a t m e n t . I f v a l u e g a i n i s found t o be r e l a t e d t o i n i t i a l v a l u e s o f t h e f i r s t s a m p l i n g , a d j u s t m e n t s can be made t o improve t h e p r e c i s i o n o f t h e t r e a t m e n t e f f e c t ( L i t t l e and H i l l s , 1978). An attempt was made by a n a l y s e s o f l i n e a r H3 c o v a r i a n c e t o remove the v a r i a b i l i t y i n the second samples a s s o c i a t e d w i t h t h e independent v a l u e s o f the f i r s t samples. However, t h e s e two s e t s o f d a t a were o f t e n not s i g n i f i c a n t l y r e l a t e d (P <0.05) a c c o r d i n g t o the F t e s t s o f the l i n e a r r e g r e s s i o n between the two f o r v a r i o u s f a c t o r s d e t e r m i n e d on the samples. C o n s e q u e n t l y , the d e c i s i o n was made t o use the r e s u l t s o f a n a l y s i s o f v a r i a n c e based on the samples c o l l e c t e d a f t e r the f e r t i l i z e r t r e a t m e n t . N o n e t h e l e s s , Table 5.21 was p r o v i d e d t o i n d i c a t e the s i g n i f i c a n t (P <0.01) r e s u l t s o f t h e a n a l y s e s o f c o v a r i a n c e . 5.4.1 S o i l f a c t o r s 5.4.1.1 O p e r a t i o n a l f e r t i l i z a t i o n Measurements r e v e a l e d uneven d i s t r i b u t i o n o f the f e r t i -l i z e r a p p l i e d by h e l i c o p t e r on June 17, 1980. A l t h o u g h the a e r i a l f e r t i l i z a t i o n was d e s i g n e d t o be 150 kg/ha, th e a r e a r e c l a i m e d i n 1978 r e c e i v e d no f e r t i l i z e r , the 1975 s i t e was h e a v i l y f e r t i l i z e d a t 391 ± 135 kg/ha, w h i l e the 1977 s i t e r e c e i v e d o n l y 61 ± 155 kg/ha (Table 5.14 and F i g u r e 5.35). On t h e f e r t i l i z e d p l o t s o f the 1978 and 1977 a r e a s , f e r t i l i z e r was h a n d - a p p l i e d a t 150 kg/ha on June 20,11980 t o ensure a more u n i f o r m f e r t i l i z e r a p p l i c a t i o n on the e x p e r i m e n t a l p l o t s . A e r i a l f e r t i l i z a t i o n had o r i g i n a l l y been s c h e d u l e d much e a r l i e r i n the season but was d e l a y e d t o the m i d d l e o f June 1980 due t o u n s t a b l e weather c o n d i t i o n s p r i o r t o t h a t d a t e . 1^ 4 Figure 5.35 Maintenance f e r t i l i z e r app l i ca t ion by he l i copter . Photographed in June, 1980. Table 5.14 Estimate of a e r i a l f e r t i l i z e r d i s t r i bu t i on on the reclaimed areas. F e r t i l i z e r d i s t r i b u t i o n (kg/ha)  p lot 1978 area 1977 area 1974 area 1974 a r e a 1 f e r t i l i z e d 0 ± 0 2 120 ± 214 310 ± 101 u n f e r t i l i z e d (0 ± 0 ) (2 ± 4) (471 ± 121) average 0 ± 0 61 ± 155 391 ± 135 The 1974 area was hand f e r t i l i z e d at 150 kg/ha. 2 Figures represent estimates of f e r t i l i z e r d i s t r i b u t i o n on the p lot areas. U n f e r t i l i z e d p lots were protected from actual f e r t i l i z a t i o n by a covering of p l a s t i c sheeting. F e r t i l i z e r was appl ied on June 17, 1980. Deta i l s of estimate methods are described in Section 4.4.1. 145 5.4.1.2 S o i l r e a c t i o n A n a l y s i s o f v a r i a n c e o f d a t a c o l l e c t e d a f t e r f e r t i l i -z a t i o n showed s i g n i f i c a n t (P <0.01) pH d i f f e r e n c e s between the a r e a s o f d i f f e r e n t ages. However, c o v a r i a n c e a n a l y s i s i n d i c a t e d a s i g n i f i c a n t (P <0.05) i n t e r a c t i o n between f e r t i -l i z e r t r e a t m e n t and l o c a t i o n w i t h i n t h e age ( Tables 5.15 and 5.21). The r e s u l t s o f the above s t a t i s t i c a l r e s u l t s per se d i d n o t , t h e r e f o r e , show a c l e a r r e l a t i o n s h i p between pH and f e r t i l i z e r t r e a t m e n t . When pH v a l u e s were p l o t t e d f o r the f e r t i l i z e d and u n f e r t i l i z e d samples o f d i f f e r e n t ages, pH l e v e l s g e n e r a l l y d e c r e a s e d w i t h the age o f the s i t e s and f e r t i l i z e r t r e a t m e n t ( F i g u r e 5.36). These pH p a t t e r n s were p r o b a b l y r e l a t e d t o the a c i d i f y i n g e f f e c t o f t h e f e r t i l i z e r ammonium as p r e v i o u s l y d i s c u s s e d i n S e c t i o n 5.2.2.1. P a r t i c u -l a r l y low pH l e v e l s were o b s e r v e d on t h e 1975 s i t e w hich r e c e i v e d 391 ± 135 kg/ha f e r t i l i z e r i n 1980 (Table 5.14). T h i s o b s e r v a t i o n i n d i c a t e d t h a t t h i s s i t e might have r e c e i v e d a s i m i l a r l y heavy f e r t i l i z e r a p p l i c a t i o n i n the p a s t . Because th e pH v a l u e s found i n t h e s e f i e l d 1 t e s t s were s i m i l a r t o t h o s e o f f i e l d s u r v e y , th e t e s t p l o t s were c o n s i d e r e d t o be r e p r e s e n -t a t i v e o f t h e r e c l a i m e d a r e a s o f d i f f e r e n t ages. 5.4.1.3 Phosphorus A s i g n i f i c a n t d i f f e r e n c e (P <0.05) i n s o i l phosphorus was found between a r e a s o f d i f f e r e n t ages, where younger a r e a s were g e n e r a l l y lower i n phosphorus ( F i g u r e 5.36 and T able 5.15). U n f e r t i l i z e d p l o t s a l s o tended t o be lower i n phosphorus t h a n Table 5.15 Variance analyses for pH, phosphorus. ammonium and ni t r a t e of . o l , . - f o r e and after f e r t i l i z a t i o n . Age (year) 3-4 6-7 LocatIon/Age Age 3-4 78 ] 77 6-7 75 74 Ferti1Izer F * Unf Fert.xAge Age 3-4 F Unf 6-7 F Unf Fert.xLoct./Age Age 3-4 Loct. 78 7 . 7 8 7 . 6 . 7 . 7 . 7 . 7 8 7 7 9 . 3 .0 8 9 .6 6 6 7 0 4 1 8.0 7 . 2 * * 8.0 8.0 6.9a 7.5 I 3.0 7 . 4 2 . 2 12.8 19.4 2.7 * * * * 3.7a 4 . 3a 1 . 8a 2. 3a 10.5 b 2.6 be 14.7 c 22.0 d 3.2 c 10.8 b 16.8 c 2 . 4ab 8 . 3 16 . 8 2.4 7.4 10.0 2.6 3.2 10.5 1 .9 2.8 4.3 2.5 13.5 23.2 2.9 12.0 15.7 2.7 77 Age 6-7 Loct . 75 74 Block/Loct F • Unf F Unf F Unf F Unf •/Age 7 . 8 7 . 9 3 . 7 5. 7 8 . 2 8 . 1 3. 7 3 . 0 7 . 6 7 . 8 2 . 7 15 . 3 7 . 9 8 . 2 2 . 0 5. 7 7 . 2 6 . 7 14 .7 26 . 3 6 .7 7 . 1 14 .7 17 .7 7 .6 7 .5 12 .3 20 .0 7 .6 7 .6 9 . 3 13 .7 1 .9 1 .7 1 .8 3.4 2.9 3.5 2.9 1 .9 1980. 4 . 2 . 3 . 6 . 4 . 0 6 0 8 0 4 0 8 5 2 4 6 . 4 .5 .8 .9 .8 . 1 .9 5.6 0.9 12.2 0.6 8.0 1 . 2 0.2 0.6 5 2 .6 . 3 .9 .6 0 7 3 7 1 .8 2.7 2 2 2 2 2 1 2 . 2 . 2 . 2 , 1 .0 4 3 3 . 4 . 2 .0 Before f e r t i l i z a t i o n : May 28 - June 6. After f e r t i l i z a t i o n : July 11-22, 1980. Year revegetated. Fert11(zed Unfert111zed Means followed by a common lett e r were not s i g n i f i c a n t l y d i f f e r e n t at 5% level by Duncan's multiple range test. *, ** s i g n i f i c a n t at 5 and 1% levels, respectively. 2.8 2.4 2.2 3 . 3 2.4 2.4 2.8 2 . 3 * 3.7 b 1 .8a 1 . 9a 2.8ab 1 .8 2.9 Date 1 Date 2 4.7 5.0 4.4 4.9 6.0 4.0 4.4 5 . 3 4 . 1 5.2 4.6 5.4 4.0 4.8 4 . 2 5.7 5.2 6.9 4.0 3.9 7.6 4.9 5.5 9.8 6.9 2.8 9 3 12 2 6 3 3 2 .7 .6 .0 . 7 .0 .0 .4 . 2 8 0 2. 1 3.4 9 2 16  3. 9 4 147 ppm 3 0 H (a) (b) Figure 5.36 pH and phosphorus on f e r t i l i z e d and u n f e r t i l i z e d p l o t s . (a) pH (b) phosphorus. Age 3 represents an area reclaimed i n 1978. F e r t i l i z e r a p p l i c a t i o n and sample c o l l e c t i o n were made June 17-20 and J u l y 5-22, 1980, r e s p e c t i v e l y . • F e r t i l i z e d p l o t s o U n f e r t i l i z e d p l o t s x No area revegetated f o r t h i s age H 8 f e r t i l i z e d , a l t h o u g h t h i s d i f f e r e n c e was not s i g n i f i c a n t . Moreover, a comparison o f t h e s o i l pH and phosphorus r e v e a l e d a c l e a r i n v e r s e r e l a t i o n s h i p between t h e two ( F i g u r e 5.36). At lower pH v a l u e s t h e a v a i l a b l e phosphorus l e v e l s were h i g h e r . However, i t was not p o s s i b l e t o determine whether . the lower pH v a l u e s a s s o c i a t e d w i t h the h i g h e r phosphorus l e v e l s o f the o l d e r a r e a s (age 3-4 y e a r s ) were t h e r e s u l t o f the accumulated e f f e c t s o f ammonium a c i d i f i c a t i o n and phospho-r u s a p p l i e d as f e r t i l i z e r o r the e f f e c t s o f c a l c i u m l e a c h i n g o v e r t i m e . Accumulated o r g a n i c m a t t e r r e p r e s e n t e d a nother p o s s i b l e compartment o f phosphorus on the o l d e r s i t e s . C o n s i -d e r i n g t h i s c l o s e i n v e r s e r e l a t i o n s h i p between pH and phospho-r u s , i t would be i n t e r e s t i n g t o i n v e s t i g a t e the p o s s i b i l i t y o f l o w e r i n g pH v a l u e s o f f r e s h s p o i l s t o an a c i d i c - n e a r n e u t r a l l e v e l t o improve t h e a v a i l a b i l i t y o f phosphorus a p p l i e d as f e r t i l i z e r . 5.4.1.4 N i t r o g e n L e v e l s o f a v a i l a b l e ammonium were g e n e r a l l y v e r y low i n samples c o l l e c t e d b e f o r e and a f t e r f e r t i l i z a t i o n (Table 5.15). F e r t i l i z e r t r e a t m e n t i n c r e a s e d the l e v e l s o f ammonium by 5.7 t o 6.5 ppm, a l t h o u g h the d i f f e r e n c e was not s i g n i f i c a n t . A v a i l a b l e n i t r a t e l e v e l s were s i m i l a r l y low and showed no s i g n i f i c a n t d i f f e r e n c e s w i t h age, l o c a t i o n o r f e r t i l i z e r t r e a t m e n t . There was, however, a s i g n i f i c a n t i n t e r a c t i o n (P <0.05) between f e r t i l i z e r t r e a t m e n t and l o c a t i o n w i t h i n age i n wh i c h t h e f e r t i l i z e d p l o t s o f t h e younger are a s (age 149 3 - 4 ) had h i g h e r l e v e l s o f n i t r a t e than t h o s e o f the u n f e r t i l i z e d , w h i l e t h i s t r e n d was r e v e r s e d on the o l d e r a r e a s (age 6 - 7 ) . Because n i t r a t e l e v e l s were so low (below 3.7 ppm), t h e p r a c t i c a l i m p l i c a t i o n s o f t h i s i n t e r a c t i o n a r e m i n i m a l . Combined ammonium and n i t r a t e l e v e l s showed no s i g n i f i -c a n t d i f f e r e n c e s between t r e a t m e n t s nor any i n t e r a c t i o n s (Table 5.15). However, t h e r e was a t r e n d toward h i g h e r ammonium and n i t r a t e l e v e l s on t h e f e r t i l i z e d p l o t s e x c e p t the age 7 (1974) a r e a ( F i g u r e 5.37). Because most o f the n i t r o g e n on the f e r t i l i z e d p l o t s c o n s i s t e d o f ammonium r a t h e r t h a n n i t r a t e , the h i g h l e v e l s were m a i n l y a t t r i b u t a b l e t o t h e f e r t i l i z e r a p p l i c a t i o n and l i m i t e d a p l a n t uptake o f the ammonium. On t h e o l d e s t a r e a (7 y e a r s ) n i t r o g e n l e v e l s were lower on t h e f e r t i -l i z e d p l o t (2.1 ppm) than on the u n f e r t i l i z e d '. (3.4 ppm). The a v a i l a b l e d a t a p r o v i d e no o b v i o u s e x p l a n a t i o n f o r t h i s c o n t r a d i c t o r y o b s e r v a t i o n . I n v i e w o f the importance o f s o i l n i t r o g e n t o aboveground p l a n t biomass p r o d u c t i o n , an attempt i s made below t o i n t e r p r e t t h e s e o b s e r v a t i o n s . The p o s s i b l e f a t e o f a p p l i e d ammonium may be l e a c h i n g , v o l a t i l i z a t i o n , p l a n t u p t a k e , c l a y f i x a t i o n , n i t r i f i c a t i o n , o r i n c o r p o r a t i o n i n t o s o i l m i c r o b e s . S i n c e the f e r t i l i z e d and u n f e r t i l i z e d p l o t s were i n c l o s e p r o x i m i t y , e n v i r o n m e n t a l f a c t o r s were u n l i k e l y t o have been t h e source o f t h e obser v e d lower l e v e l s o f ammonium and n i t r a t e on the f e r t i l i z e d p l o t s . The lower aboveground biomass on f e r t i l i z e d v e r s u s u n f e r t i l i z e d p l o t s a l s o negated the argument t h a t h i g h e r p l a n t uptake o f 150 N H 4 +N0 3 ppm 24 F i g u r e 5.37 N i t rogen (ammonium and n i t r a t e ) l e v e l s on f e r t i l i z e d and u n f e r t i l i z e d p l o t s . Age 3 represents an area rec la imed i n 1978. F e r t i l i z e r a p p l i c a t i o n and sample c o l l e c t i o n were made d u r i n g June 17-20 and J u l y 15-22, 1980, r e s p e c t i v e l y . • F e r t i l i z e d p l o t s o U n f e r t i l i z e d p l o t s x No area revegetated fo r t h i s age 151 n i t r o g e n had o c c u r r e d on t h e f e r t i l i z e d s i t e . There was no e v i d e n c e t o s u s p e c t t h a t most o f t h e above p r o c e s s e s were not t a k i n g p l a c e . T h e r e f o r e a greenhouse e f f e c t c r e a t e d by the use o f p l a s t i c s h e e t i n g o v e r the u n f e r t i l i z e d p l o t was c o n s i -d e r e d t o be a p o t e n t i a l e x p l a n a t i o n o f the o b s e r v e d r e s u l t s . The t e s t p l o t i n q u e s t i o n was l o c a t e d near a h e l i c o p t e r l a n d i n g pad. To a v o i d s p i l l a g e o f f e r t i l i z e r on the u n f e r t i l i z e d p l o t , t h e s h e e t i n g was l e f t i n p l a c e l o n g e r t h a n on t h e o t h e r a r e a s . As a consequence, enhanced p l a n t growth and n i t r o g e n m i n e r a l i -z a t i o n may have o c c u r r e d on t h e u n f e r t i l i z e d p l o t r e s u l t i n g i n a s l i g h t l y h i g h e r n i t r o g e n l e v e l . Indeed, th e aboveground 2 biomass o f t h i s p l o t (103.7 g/m ) was s i g n i f i c a n t l y (P <0.05) 2 l a r g e r than t h e f e r t i l i z e d p l o t (59.3 g/m ) (Table 5.19). A d i r e c t comparison o f n i t r o g e n l e v e l s f o r t h i s a r e a t o the 1975 s i t e (6 y e a r s ) would not be v a l i d because the l a t t e r r e c e i v e d double the amount (310 ± 101 kg/ha) o f a p p l i e d f e r t i l i z e r . N i t r i f i c a t i o n o f ammonium was thought t o be more a c t i v e on t h e age 7 a r e a t h a n th e younger ones because o f the e x t r e m e l y low l e v e l s o f ammonium (0.2 ppm) on the o l d e s t f e r t i l i z e d p l o t . Throughout t h e season th e s o i l s o f the younger a r e a s were c o n s i s t e n t l y d r i e r t h a n i n the o l d e s t a r e a ( F i g u r e 5.3) w h i c h might a l s o have c o n t r i b u t e d t o t h e d i f f e r e n c e , s i n c e d r y i n g has been r e p o r t e d t o k i l l n i t r i f y i n g m i c r o o r g a n i s m s ( R u s s e l l , 1973) . 152 5.4.2 Phytomass c o m p o s i t i o n 5.4.2.1 Grasses The aboveground g r a s s biomass was s i g n i f i c a n t l y (P <0.05) l a r g e r on the o l d e r (age 6 - 7 ) a r e a s (Table 5.19 and F i g u r e 5.38). There was a l s o a s i g n i f i c a n t (P <0.01) i n t e r a c t i o n between f e r t i l i z e r t r e a t m e n t and l o c a t i o n w i t h i n age. T h i s i n t e r a c t i o n was unexpected and might be a t t r i b u t e d t o t h e greenhouse e f f e c t d i s c u s s e d i n S e c t i o n 5.4.1.4. A l t h o u g h t h e g r a s s biomass and s o i l n i t r o g e n l e v e l s were i n d i v i d u a l l y c o n t r a d i c t o r y on the o l d e s t (1974) s i t e , a g e n e r a l l y p o s i t i v e r e l a t i o n s h i p i s apparent i n t h e F i g u r e s 5.37 and 5.38. I t was p a r t i c u l a r l y i n t e r e s t i n g t o note t h a t a p p l i e d f e r t i l i z e r n o t o n l y changed abovegroung g r a s s biomass but a l s o the r e l a t i v e c o n t r i b u t i o n s o f i n d i v i d u a l s p e c i e s t o t h e biomass. Among n i n e s p e c i e s o f g r a s s e s seeded, o n l y two s p e c i e s , D a c t y l i s g l o m e r a t a and F e s t u c a r u b r a , c o n t r i b u t e d h e a v i l y t o g r a s s biomass t h r o u g h o u t the r e c l a i m e d a r e a s . On the age 6 (1975) s i t e t h e two s p e c i e s accounted f o r 97.4% o f t h e g r a s s biomass on t h e f e r t i l i z e d p l o t and 92.3% on the u n f e r t i l i z e d (Table 5.16). F e r t i l i z e r t r e a t m e n t g e n e r a l l y enhanced the growth of D. g l o m e r a t a and reduced t h a t o f F. r u b r a ( F i g u r e 5.39 and T a b l e 5.20), w h i l e o v e r a l l , g r a s s e s on the f e r t i l i z e d p l o t s produced more biomass t h a n on the u n f e r t i l i z e d e x c e p t f o r t h e 1974 a r e a . On t h i s o l d e s t s i t e the lower n i t r o g e n l e v e l o f t h e f e r t i l i z e d p l o t r e s u l t e d i n a reduced g r a s s biomass r e l a t i v e t o t h e u n f e r t i l i z e d t r e a t m e n t . T h e r e f o r e t h e 153 D.Wt. g/m2 9 0 6 0 3 0 Figure 5.38 F e r t i l i z e r e f f e c t s on the aboveground grass biomass. Age 3 represents an area reclaimed i n 1978. F e r t i l i z e r a p p l i c a t i o n and sample c o l l e c t i o n were made during June 17-20 and J u l y 15-22, 1980, r e s p e c t i v e l y . • F e r t i l i z e d p l o t s o U n f e r t i l i z e d p l o t s x No area was revegetated for t h i s age T a b l e 5 16 Percentage r a t i o changes 1n aboveground biomass by s p e c i e s w i t h i n g r a s s e s and legumes a f t e r f e r t i l i z e r treatment on r e c l a i m e d a r e a s . y e a r r e e l a 1med 1978 1977 1975 1974 f e r t 1 1 1 z e r t r e a t m e n t 1 f e r t 1 1 i z e d u n f e r t 1 1 1 zed f e r t i 1 1 z e d u n f e r t 1 1 i z e d f e r t 1 1 i z e d u n f e r t i 1 i z e d f e r t i 1 1 z e d u n f e r t 1 1 1 z e d D . a i F . ru P . en B . in L . pje P . §£ A . aj. A . er. un i d. 4 . 8 32 . 6 10. 3 14 . 3 22 . 3 0. 0 0. 0 0. 0 15.8 12 . 9 21 . 0 4. .3 28. 0 10. 2 0. .0 0. 0 0. 0 23 . 1 56 . 3 21 . 8 13 8 0. 0 0. 8 0. .0 3 . 4 0. .0 2.3 36 . 8 40 . 4 14 .0 0. .0 0. .7 0 .0 O. 7 0. .0 7.0 82 . 7 14 . 7 2 .6 0 .0 O. .0 0 .0 O. .0 0 .0 O.O 53 . 1 39 .2 6 . 2 0 .0 0 .0 0 .0 O .0 O o 1 .5 7 . 7 52 . 1 9 .4 4 .3 0 .o- 12 .8 0 .0 10 .3 0.0 4 . 2 58 . 2 32 .9 2 . 3 0 .5 1 .9 0 .0 0 .0 5 . 1 1equmes(%) T . SE M. sa 100. 0 0. 0 100. .0 0. .0 0 .0 100 .0 8 .9 91 . 1 O .0 100 .0 100 .0 0 .0 36 .0 64 .0. 7 . 1 92 .9 June 17-20. 1980. of 3 samples c o l l e c t e d d u r i n g J u l y The f i g u r e s a r e p e r c e n t a g e s based on means c^*.,^~ r„hrv 11-22 1980 A b b r e v i a t i o n s a r e : D.gl - D a c t y l i s glomerata; F ru - F e s t u c a r u b r a . P pr - Phleum p r a t e n s e : B . l n - Bromus i n e r m i s ; L.pe - L o l i u m perenne; P.sp - Poa spp.; A.al - A g r o s t l s a l b a ; A.pr - A l o p e c u r u s p r a t e n s i s ; u n l d . - u n i d e n t i f i e d g r a s s e s ; T.sp - T r l f o l I u m spp. M.sa - Medicago s a t 1va. 155 (a) (b) Figure 5.39 F e r t i l i z e r e f f e c t s on aboveground biomass of D a c t y l i s glomerata and Festuca rubra. (a) D. glomerata (b) F. rubra. Age 3 represents an area reclaimed i n 1978. F e r t i l i z e r a p p l i c a t i o n and sample c o l l e c t i o n were made during June 17-20 and J u l y 15-22, 1980, r e s p e c t i v e l y . • F e r t i l i z e d p l o t s o U n f e r t i l i z e d p l o t s x No area revegetated f o r t h i s age 1 % p o s i t i v e r e l a t i o n s h i p between g r a s s biomass and s o i l n i t r o g e n l e v e l was s t i l l m a i n t a i n e d . Moreover, the d r a s t i c d e c r ease o f D. g l o m e r a t a growth a s s o c i a t e d w i t h t h e i n c r e a s e o f F. r u b r a growth agreed w e l l w i t h t h e s o i l n i t r o g e n l e v e l s o f t h i s a r e a . On t h e above e v i d e n c e , s u r v i v a l o f D. g l o m e r a t a i s c l o s e l y t i e d t o the s o i l n i t r o g e n l e v e l . I t appears l i k e l y t h a t once t h e maintenance f e r t i l i z e r i s t e r m i n a t e d a d r a s t i c d e c r e a s e i n D. g l o m e r a t a a s s o c i a t e d w i t h an i n c r e a s e i n F. r u b r a o c c u r s d u r i n g a v e r y s h o r t time p e r i o d . Somewhat con-t r a d i c t o r y r e s u l t s were o b s e r v e d w i t h D. g l o m e r a t a biomass on the o l d e s t s i t e , when f i e l d t e s t d a t a were compared t o thos e o f the 1980 f i e l d s u r v e y (Tables 5.7 and 5.16). I n t h e s u r v e y , D. g l o m e r a t a accounted f o r 43.6% o f the g r a s s biomass as compared t o 7.7% on the f e r t i l i z e d p l o t o f f i e l d t e s t . T h i s d i f f e r e n c e p r o b a b l y r e f l e c t s t h e uneven f e r t i l i z a t i o n o f t h i s a r e a . The g e n e r a l s i t e o u t s i d e t h e t e s t p l o t was p r o b a b l y hand f e r t i l i z e d w i t h a t r e a t m e n t much g r e a t e r t h a n 150 kg/ha, w h i l e t h e f e r t i l i z e d a r e a o f t h e t e s t p l o t r e c e i v e d 150 kg/ha ( F i g u r e 5.42b). D. g l o m e r a t a appeared t o l o s e c o m p e t i t i v e n e s s w i t h F. r u b r a a t low n i t r o g e n l e v e l s w h i c h c o u l d l e a d t o d r a s t i c changes o f t h e i r r e l a t i v e c o n t r i b u t i o n t o t h e aboveground g r a s s biomass i n one growing season. An a d d i t i o n a l f a c t o r , s e l f - s e e d i n g , a l s o appeared t o p l a y an i m p o r t a n t r o l e i n such a change. Grass culm c o u n t s conducted i n 197 9 showed a l a r g e d i f f e r e n c e i n p l a n t d e n s i t y o f t h e two s p e c i e s on the 1974 157 s i t e , a p p r o x i m a t e l y 200 and 1500/m f o r D. g l o m e r a t a and F. r u b r a , r e s p e c t i v e l y (Table 5.17). I t appeared l i k e l y t h a t F. r u b r a was s u c c e s s f u l l y r e s e e d i n g each y e a r because i t s 2 p l a n t d e n s i t y on 1978 and 1977 s i t e s was 122 and 107/m , r e s p e c t i v e l y (Table 5.8). I t was a l s o o b s e r v e d t h a t F. r u b r a 2 p l a n t s had 10 t o 15 culms/m w i t h i n f l o r e s c e n c e s , but none o f the D. g l o m e r a t a culms were o b s e r v e d t o have i n f l o r e s c e n c e s (Table 5.17). D. g l o m e r a t a was ob s e r v e d t o produce i n f l o r e s -cences on t h e g e n e r a l r e c l a i m e d a r e a s and K a i s e r Res. L t d . (1979) s o u r c e s have r e p o r t e d g r a s s ( s p e c i e s n o t named) s e e d l i n g 2 d e n s i t y o f 1128 ± 228 / m on t h e 1974 s i t e measured i n August, 1978. 5.4.2.2.. Legumes Legume s p e c i e s found on t h e r e c l a i m e d a r e a s i n c l u d e d T r i f o l i u m r e p e n s , T. hybridum and Medicago s a t i v a . The T r i f o l i u m s p e c i e s were c o n t a i n e d i n the o r i g i n a l seed mix, but Medicago s a t i v a had been seeded s e p a r a t e l y a t a l a t e r t i m e . These legume s p e c i e s e s t a b l i s h e d r a t h e r p o o r l y on most a r e a s e x c e p t t h a t seeded i n 1978. C o n s e q u e n t l y , t h e i r d i s t r i b u t i o n on t h e r e c l a i m e d a r e a s was seldom u n i f o r m . The d a t a i n t h i s s t u d y r e f l e c t t h i s g e n e r a l o b s e r v a t i o n o f poor legume s u r v i v a l and i r r e g u l a r d i s t r i b u t i o n . Among t h e legumes found, T r i f o l i u m s p e c i e s accounted f o r o n l y about 7.0% o f the aboveground grass-legume biomass e x c e p t on t h e 1978 a r e a where t h e y accounted f o r almost 73% o f the t o t a l biomass. Medicago s a t i v a was g e n e r a l l y found t o T a b l e 5.17 Number of culms or stems per m' on 1974 area P l o t 1 D.gi F . ru B . 1 n P . sp F e r t 1 1 I z e d t o t a l stems 200+270 stems w i t h I n f l o r e s c e n c e 0+0 U n f e r t l 1 1 z e d t o t a l stems 2101345 stems w i t h i n f l o r e s c e n c e 0+0 1395+1610 2251270 15135 245+565 10125 5120 010 0+0 146512120 2301260 30185 180+335 15130 20+45 0+0 010 T . sp 15140 010 10+25 010 M. sa 85+135 0+0 55190 010 1. No f e r t i l i z e r treatment was executed at t h i s time. The f i g u r e s a r e means and s t a n d a r d d e v i a t i o n s of 24 o b s e r v a t i o n s made on August 15. 1979. CuTms or stems counted w i t h i n a 200 cm' c i r c l e were c o n v e r t e d f o r m e t e ^ u m e D r a t e n s e . A b b r e v i a t i o n s - D a l - D a c t y l 1s glomerata; F.ru - Fes t u c a r u b r a ; P.pr - PjTleum p r a t e n s e , R i n B romCr inermi s;-p-^-pia spp.; T • sp - T r i f o l l u m spp.; M.sa - Medicago s a t i v a . 159 be more v i g o r o u s and s u c c e s s f u l on a l l a r e a s where t h i s s p e c i e s had been seeded, a c c o u n t i n g f o r from 12.5 t o 40.2% o f t o t a l biomass (Table 5.18). The s u p e r i o r M. s a t i v a performance c o u l d be based on the f a c t i t was overseeded i n t o e x i s t i n g p l a n t c o v e r and t h e r e f o r e had a b e t t e r o p p o r t u n i t y f o r s u r v i v a l and e s t a b l i s h m e n t . Other p o s s i b l e r e a s o n s f o r the s u c c e s s o f the M. s a t i v a have been c o n s i d e r e d i n S e c t i o n s 5.2.2.2 and 6.1. The v a r i a n c e a n a l y s e s on d a t a from samples c o l l e c t e d a f t e r f e r t i l i z a t i o n showed no s i g n i f i c a n t d i f f e r e n c e s o r i n t e r -a c t i o n s o f t h e t r e a t m e n t (age, l o c a t i o n and f e r t i l i z e r ) on legume biomass (Table 5.19). Because o f t h e poor legume e s t a b l i s h m e n t and d i s t r i b u t i o n , f u r t h e r d i s c u s s i o n o f o v e r a l l legume performance i s based l a r g e l y on f i e l d o b s e r v a t i o n s . The g e n e r a l l y poor performance o f t h e legumes, p a r t i c u -l a r l y T r i f o l i u m spp., was p r o b a b l y a d i r e c t consequence o f poor s e e d l i n g e s t a b l i s h m e n t and s u r v i v a l . That T r i f o l i u m spp. c o u l d germinate and e s t a b l i s h w e l l was demonstrated by t h e i r s u c c e s s i n t h e 1978 s e e d i n g . However, i t was c l e a r t h a t T r i f o l i u m spp. performed w e l l o n l y on l i m i t e d s i t e s where f a v o r a b l e m i c r o e n v i r o n m e n t s had been c r e a t e d by b u l l d o z e r t r a c k s o r h a r r o w i n g ( F i g u r e 5.40). F u r t h e r m o r e , t h e legumes were not s u c c e s s f u l on t h e 1977 s i t e where g r a s s e s germinated and s u r v i v e d w e l l ( F i g u r e 5.41). On t h i s a r e a T r i f o l i u m spp. accounted f o r l e s s t h a n 3.9% o f t h e aboveground t o t a l biomass (Table 5.18). The g r a s s e s on t h i s a r e a were not w e l l - d e v e l o p e d and c o m p e t i t i o n between t h e g r a s s e s and legumes was not as s i g n i f i c a n t a f a c t o r as i t would have been on a r e a s where T a b l e 5.18 Percentage r a t i o changes 1n aboveground g r a s s and legume blomasses. and l i t t e r a f t e r f e r t i l i z a t i o n . y e a r rec1 a 1med 1978 1977 1975 1974 f e r t i 1 1 z e r t r e a t m e n t 1 f e r t 1 1 i z e d u n f e r t i 1 i z e d f e r t i 1 i z e d u n f e r t 1 1 i z e d g r a s s e s and legumes(%)  g r a s s e s T.sp. M . sa t 1 va 24 27 f e r t i 1 1 z e d 80.6 u n f e r t i 1 1 z e d 55.9 84 . 5 93.5 f e r t i 1 1 z e d 80.1 u n f e r t i l i z e d 83.2 76.7 72 .9 0.0 3.9 0.0 6.5 7.0 1 . 2 0.0 0.0 19 . 4 40. 2 15.5 0.0 12.5 15.6 g r a s s e s + l e g . and l i t t e r ( % )  grasses*1 eg. 85.4 78.7 75.5 72.9 44 28 22.9 32.0 1i t t e r 14.6 21.3 24 . 5 27. 1 55.6 71.6 77 68 1. June 17-20. 1980. The f i g u r e s a r e p e r c e n t a g e s based on means of 3 samples c o l l e c t e d d u r i n g J u l y 11-22. 1980. 161 Figure 5.40 T r i folium spp. establishment and s u r v i v a l on 1978 area. (a) General view of a t e s t p l o t . (b) E f f e c t s of microenvironments on T r i f o l i u m spp. establishment. H a r r o w i n g b u l l d o z e r t r a c k s created favorable microenvironments f o r T r i f o l i u m spp. establishment. Photographed on J u l y 4, 1980. 162 Figure 5.41 Grass dominated vegetation on 1977 area. (a) General view of a t e s t p l o t . (b) E f f e c t s of microenvironments on grass establishment. Grasses were e s t a b l i s h e d in rows where favorable microenvironments were created by harrowing or b u l l d o z e r t r a c k s . Photographed J u l y 4, 1980. 163 Figure 5.42 F e r t i l i z e r e f f e c t s on vegetation of 1975 and 1974 areas. (a) T e s t p l o t on 1975 a r e a . P l a n t s on u n f e r t i l i z e d p l o t ( l e f t ) c l e a r l y showed c h l o r o s i s symptom. (b) Test p l o t on 1974 area. P l a n t s on u n f e r t i l i z e d p l o t (two rows on r i g h t ) showed s l i g h t c h l o r o s i s symptom. 164 g r a s s e s were more v i g o r o u s . T h e r e f o r e i t appears t h a t legume performance was m a i n l y a consequence o f e i t h e r poor i n i t i a l g e r m i n a t i o n , or h i g h m o r t a l i t y o f young s e e d l i n g s . Where h i g h r a t e s o f n i t r o g e n f e r t i l i z e r were a p p l i e d , t h e poor performance of T r i f o l i u m spp. might be caused by t h e i r e l i m i n a t i o n as a r e s u l t o f s t r o n g c o m p e t i t i o n from the g r a s s e s . A r a p i d growth response by the g r a s s e s t o the h i g h ( n i t r o g e n ) f e r t i l i z e r was shown i n F i g u r e 5.42a. Under t h e s e c o n d i t i o n s t a l l e r g r a s s e s c o u l d i n t e r c e p t l i g h t and u t i l i z e n u t r i e n t s w h i c h would r e s u l t u l t i m a t e l y i n poor legume s u r v i v a l i n s p i t e o f a s e e d l i n g p o p u l a t i o n t h a t might have been i n i t i a l l y l a r g e . Another f a c t o r t o be c o n s i d e r e d was the a b i l i t y o f T r i f o l i u m spp. t o r e s e e d t h e m s e l v e s . In s p i t e o f abundant f l o w e r i n g , no i n d i c a t i o n o f young s e e d l i n g e s t a b l i s h m e n t was o b s e r v e d . S i m i l a r l y no young s e e d l i n g s o f Medicago s a t i v a were o b s e r v e d . I t was s u s p e c t e d t h a t e i t h e r no v i a b l e seed p r o d u c -t i o n o f t h e t h r e e legume s p e c i e s o c c u r r e d or u n f a v o r a b l e m i c r o -environments e x i s t e d f o r s e e d l i n g s u r v i v a l i f v i a b l e seeds were produced. A n n i t i o n a l c o n s i d e r a t i o n o f legume performance i s i n c l u d e d i n S e c t i o n 5.4.3. 5.4.2.3 Belowground biomass Data c o l l e c t e d b e f o r e the f e r t i l i z e r t r e a t m e n t showed a l a r g e v a r i a t i o n i n belowground biomass d i s t r i b u t i o n . Hence, t h e d a t a c o l l e c t e d a f t e r f e r t i l i z a t i o n were s t r o n g l y i n f l u e n c e d by t h i s i n i t i a l v a r i a t i o n and masked the e f f e c t o f t h e f e r t i l i -z e r t r e a t m e n t (Table 5.19). The v a r i a n c e a n a l y s i s showed non-165 s i g n i f i c a n t d i f f e r e n c e s i n t h e belowground biomass o f p l a n t s under d i f f e r e n t f e r t i l i z e r l e v e l s . However, t h e r e was a s i g n i f i c a n t d i f f e r e n c e (P <0.05) between belowground biomass of t he younger (age 3 - 4 ) v e r s u s the o l d e r (age 6 - 7 ) a r e a s . F r u t h e r m o r e , belowground biomass on t h e age 7 a r e a was s i g n i f i c a n t l y l a r g e r (P <0.01) th a n t h a t on age 6, showing a s t e a d y i n c r e a s e i n t h i s component on the o l d e r a r e a s . T h i s i n c r e a s e i n belowground biomass was much more th a n t h a t o b s e r v e d i n aboveground biomass w h i c h r e s u l t e d i n d e c r e a s e d shoot t o r o o t (S/R) r a t i o s as t h e p l a n t s aged, 2.3, 0.9, 0.3 and 0.2 f o r age 3, 4, 6 and 7 a r e a s . A l l g r a s s e s and legumes i n t h i s s t u d y a re p e r e n n i a l and l a r g e belowground biomass s h o u l d be b e n e f i c i a l t o l o n g e v i t y . A s u b s t a n t i a l r o o t system can s t o r e s u f f i c i e n t c a r b o h y d r a t e f o r use d u r i n g t h e dormant p e r i o d o f l o n g w i n t e r s and t o ensure r a p i d e a r l y s p r i n g growth, an advantage where s h o r t g r owing seasons p r e v a i l as i n s u b a l p i n e a r e a s . T h e r e f o r e p l a n t s o f t h e o l d e r a r e a s were e x p e c t e d t o be more s t a b l e and r e s i l i e n t t o w i n t e r k i l l i n g t h a n t h o s e o f the younger a r e a s . A l t h o u g h the f e r t i l i z e r e f f e c t on belowground biomass was not c l e a r from t h i s s t u d y , a s t o r e d c a r b o h y d r a t e i n r o o t s c o u l d be e x p e c t e d t o be reduced i n u n f e r t i l i z e d p l a n t s because o f t h e g e n e r a l low f e r t i l i t y o f t h e r e c l a i m e d a r e a s . Such an example was found i n the u n f e r t i l i z e d p l a n t s o f t h e 1975 a r e a 2 where belowground biomass d e c r e a s e d from 4 91.3 t o 2 98.1 g/m i n 44 days between the two s a m p l i n g p e r i o d s . W i n t e r k i l l i n g 166 might be p r e d i c t a b l y h i g h e r on p l a n t s w i t h reduced c a r b o h y d r a t e r e s e r v e s . I n g e n e r a l , e x c e s s n i t r o g e n d e l a y s p l a n t m a t u r i t y w h i l e abundant phosphorus h a s t e n s m a t u r i t y and s t i m u l a t e s r o o t r e l a t i v e t o shoot growth ( S a l i s b u r y and Ross, 1978). A p p l i e d f e r t i l i z e r (13-16-10) ranged from 150 t o 310 kg/ha and c o n t a i n e d b o t h n i t r o g e n and phosphorus. I t was not det e r m i n e d from t h i s s t u d y how the a p p l i e d n i t r o g e n and phosphorus a c t e d on shoot and/or r o o t growth. 5.4.2.4 L i t t e r L i t t e r p l a y s an i m p o r t a n t r o l e i n n u t r i e n t c y c l i n g o f p l a n t communities i n t r o d u c e d on t o mined-lands ( W i l l i a m s , 1975 and Z i e m k i e w i c z , 1979). Data from the f i e l d t e s t . i n d i c a t e d t h a t l i t t e r accumulated q u i c k l y i n a s h o r t time p e r i o d ( 6 - 7 y e a r s ) , but a l s o underwent r a p i d d e g r a d a t i o n d u r i n g t h e e a r l y summer (Table 5.19). The amounts o f l i t t e r d e t e r m i n e d d u r i n g May 28 - June 6, 1980 were s i g n i f i c a n t l y d i f f e r e n t (P < 0.01) on t h e young (age 3 - 4 ) v e r s u s t h e o l d 2 (age 6 - 7 ) a r e a s : 6.2 and 278.9 g/m , r e s p e c t i v e l y . Measured a f t e r 44 days ( J u l y 11 - 22, 1980), t h e d a t a r e f l e c t e d t h e 2 same d i f f e r e n c e s , i . e . , 11.3 and 169.2 g/m , r e s p e c t i v e l y . 2 Thus a p p r e c i a b l e amounts o f l i t t e r (10 9.7 g/m ) appear t o have been degraded d u r i n g t h a t p e r i o d . F e r t i l i z e r t r e a t m e n t was a l s o found t o have s i g n i f i c a n t (P <0.05) e f f e c t s on l i t t e r d e g r a d a t i o n . F e r t i l i z a t i o n 2 enhanced d e g r a d a t i o n , 84.0 v e r s u s 96.4 g/m f o r t h e amounts o f l i t t e r o f the f e r t i l i z e d and t h e u n f e r t i l i z e d a r e a s , r e s p e c -167 t i v e l y . The data further supported the view that l i t t e r continued accumulating even 7 years after revegetation was i n i t i a t e d . Therefore, f e r t i l i z a t i o n could be viewed as supply-ing nutrients not only d i r e c t l y to the plants but also through enhancement of nutrient c y c l i n g through faster l i t t e r degrada-t i o n . Ziemkiewicz (1979) applied 1,000 kg/ha of f e r t i l i z e r (13-16-10) on the same general s i t e of the oldest area i n t h i s study and reported the tendency of u n f e r t i l i z e d plots to 'accumulate l i t t e r despite lowered aboveground biomass from a previous year. 5.4.2.5 Phytomass Phytomass (above- and belowground biomass plus l i t t e r ) d i f f e r e d s i g n i f i c a n t l y (P < 0.05) from the youngest to the oldest areas. Phytomass accumulation was apparently greater on the older areas as shown i n phytomass changes from 60.6, 106.7, 469.9 to 691.0 g/m2 for age 3, 4, 6, and 7 areas, respectively. F e r t i l i z e r treatment did not contribute s i g n i -f i c a n t l y to ef f e c t s on the phytomass of areas of d i f f e r e n t ages (Table 5.19). Because there were large increases i n belowground biomass and l i t t e r as the plant communities aged, the r e l a t i v e contribution of aboveground biomass to the phytomass tended to decrease (Table 5.18). These continuous changes observed on the areas of four d i f f e r e n t ages suggested that a phytomass structure equilibrium had not yet been reached. Therefore, the present trend of increases i n l i t t e r and belowground biomass could be expected to continue T a b l e 5 . 1 9 V a r i a n c e a n a l y s e s f o r p h y t o m a s s f r a c t i o n s b e f o r e a n d a f t e r f e r t i l i z a t i o n . a b o v e g r o u n d b i o m a s s ( g / m 2 ) S o u r c e D F  A q e ( y e a r ) 1 3 - 4 6 - 7 L o c a t i o n 2 A g e 3 - 4 7 8 ' 7 7 6 - 7 7 5 7 4 F e r t i 1 1 z e r 1 F ' U n f » F e r t . x A g e 1 A g e 3 - 4 F U n f 6 - 7 F U n f F e r t . x L o c t . / A g e 2 A g e 3 - 4 L o c t . A g e 6 - 7 L o c t . B l o c k / L o c t . / A g e 8 0 . q l o m e r a t a D a t e I 1 D a t e 27 F . r u b r a g r a s s 1 e g u m e g r a s s •*• l e g u m e D a t e 1 D a t e 2 D a t e 1 D a t e 2 D a t e 1 D a t e 2 D a t e 1 D a t e 2 1 . 7 7 . 5 2 . . 4 5 9 . 6 2 4 . 8 6 . 3 2 6 * * * * * * 0 . 2 a 0 . . 7 a 1 . . 1 2 3 . . 3 a 14 . 2 b 3 . 7 8 1 5 . 2 b 4 6 . 2 c 4 . 7 1 6 4 , 0 a 3 , 5 a 7 . 8 3 7 . 6 a 6 . 8 2 3 . 5 2 . 3 a 5 . . 3 2 2 . 0 5 . . 0 1 1 . 9 6 . 0 1 0 . 3 3 . * . 7 2 0 . 5 2 . . 2 1 0 . . 2 1 , 9 a 5 . . 7 1 . 3 4 . 8 2 . 8 a b 5 , , 5 8 . 5 3 3 . . 9 8 . 0 c 18 . . 0 1 0 . 7 1 5 . 8 4 . 5 b 3 5 . 5 C21 . 2 * 1 5 . 8 1 4 . 5 1 9 . 6 6 9 2 9 d 6 5 c 6 7 4 2 . 9 4 2 . 5 6 . 9 a 2 3 . 1 6 . 8 a 1 5 . 3 2 4 . 8 c 6 2 . 6 2 2 . 2 b • 6 9 . 6 7 8 F 0 . 1 0 . 5 0 . . 9 3 . . 6 2 . 6 1 1 U n f 0 . 2 1 . 0 1 . . 3 1 . 6 2 . 1 7 7 7 F 4 . 2 1 9 . 8 3 . 0 7 . 8 1 1 . 2 3 5 U n f 2 . . 4 8 . 6 4 . 4 9 . 3 1 1 . 5 2 3 1 a 6 a . 2 b e . 1 a 1 0 1 9 11 0 1 7 5 F 1 5 . 4 6 4 . 2 6 . 3 1 1 . 2 2 7 . . 1 7 7 . . 7 U n f 1 5 . 0 2 8 . , 1 3 . . 1 2 0 . 7 2 4 . . 5 5 2 . . 9 7 4 F 1 . 6 3 . 6 9 8 2 4 . 9 2 2 . . 4 4 7 , . 7 U n f 6 . 3 3 . 5 5 . . 9 5 0 . 3 19 . 9 8 6 . 4 b d c c d 7 2 0 . 3 1 2 . 5 3 9 . 6 8 1 1 . 7 2 5 . 3 7 7 . 9 3 b 2 7 . 4 1 2 . 6 3 6 . 7 1 a 1 3 . 3 1 2 . 5 4 2 . 4 5 a 9 . 0 2 8 . 4 7 4 . 3 1 a 14 . 4 2 2 . 2 8 1 . 5 3 1 7 . . 1 2 0 . 1 6 0 . 0 2 14 , . 9 17 . 7 5 7 . 4 2 2 1 . . 3 1 2 . . 1 4 4 . . 4 2 19 . 4 1 3 . . 0 3 4 , . 7 5 1 3 . 0 2 8 . . 2 7 5 , . 7 1 1 0 . 5 2 2 . , 4 8 0 . * . 1 6 3 4 . 1 1 2 . 1 4 5 . 2 a 0 2 0 . 7 1 3 . 1 2 8 , 2 a 8 8 . 5 1 2 . 0 4 3 . 6 a 5 1 8 . 1 1 3 . 0 4 1 . 2 a 0 14 . 4 3 2 . 2 9 2 . 0 b e 0 3 . 7 2 4 . 5 5 6 . 6 a 9 1 1 . 6 2 4 . 3 5 9 . 3 a b 2 17 . 3 2 0 . 2 1 0 3 . 7 c 1 . B e f o r e f e r t i l i z a t i o n : M a y 2 8 - d u n e 6 , 1 9 8 0 . 2 . A f t e r f e r t i l i z a t i o n : J u l y 1 1 - 2 2 , 1 9 8 0 . 3 . Y e a r r e v e g e t a t e d 4 . F e r t i l i z e d . 5 . U n f e r t i l i z e d . OA Co T a b l e 5.19 V a r i a n c e a n a l y s e s f o r phytomass fr a c t i o n ' s b e f o r e and a f t e r f e r t i l i z a t i o n . CONTINUED be1owground biomass!a/m 2) :otal b1on:ass*(g/ m 2) 1 1 t t e r ( g / m 2 ) phytoma s s 7 ( q / m Source DF Date 1 Date 2 Date 1 Date 2 Date 1 Date 2 Date 1 Date 2 Age ( y e a r ) 1 +* * * + * + * 1 1 . * * * 3-4 26 . 5 32 . 8 39 . 1 73. 7 6 . 2 3 45 . 3 83 . 6 6-7 361 .6 333 . 4 386 .9 411 . 3 278 .9 16S I.2 665 i .8 580.6 Locat1on 2 * * * * * Age 3-4 78 13 . 2 16. 2a 25. 8 55. 6a 3 . 1 7 . 7a 28. 9 60. 6a 77 39 . 9 49 . 5a 52 . 4 91 . 9a 9. 2 14 . 8a 61 . 6 106.7a 6-7 75 373 . 4 267 . 0 b 401 . 7 341 . 3 b 274 . 3 128 . 6 b 676 . 0 469.7 b 74 349 . 9 399. 8 C372 . 1 481 . 1 C283 . 4 209. 8 C655 . 7 691.0 i F e r t 1 1 I z e r 1 * 302.8 F 157 . 2 158. 7 177. 3 220. 1 131 . 2 84 . 0 308 . 5 Unf 231 . 0 207 . 5 248 . 7 264 . 9 153 . 9 96 . 4 402 . 5 361 . 3 Fe r t . x A a e 1 * 47 . 88. 1 Age 3-4 F 29 . 6 32 . 8 41 . 7 79. 9 5 . 4 10. 9a 0 Unf 23 . 5 32 . 8 36 . 5 67 . 6 7 . 0 1 1 . 7a 43 . 6 79.2 6-7 F 284 . 7 284 . 6 312 . 9 360. 3 257 . 0 157 . 2 b 570. 0 517.7 Unf 438 . 5 382 . 1 460. 8 462 . 4 300. 7 181 . 1 C761 . 7 643.5 F e r t . x L o c t . /Age 2 * Age 3-4 71.9 Loct . 78 F 13. 7a 19. 1 25. 8 69 . 7 2 . 5 7 . 6 28 . 4 Unf 12 . 6a 13. 2 25. 8 41 . 5 3 . 7 7. .9 29. 5 49.4 77 F 45 . 5a 46. 5 57 . 5 90. 1 8 . 2 14 . 1 65. 7 104 . 3 Unf 34 . 3a 52 . 4 47 . 3 93. 6 10. 3 15. . 4 57 . 6 109. 1 Age 6-7 1 442 .9 L o c t . 75 F 255 . 6 b i 235. 8 287 . 7 327 . 9 221 . 6 1 15. .2 509 . Unf 491 . 3 d298 . 1 515. 6 354 . 7 327 . 1 141 .9 842 . 9 496.5 74 F 313 . 8 bc333. 4 338. 1 392 . 7 292 . 5 199 . 3 630. .5 591 .9 Unf 385 . 9 C 4 6 6 . 1 406 . 0 569. 6 274 . .4 220 .4 680 .5 790. 1 B l o c k / L o c t . / A g e 8 6. Above- p l u s belowground biomass. • 7. T o t a l biomass p l u s l i t t e r . Means f o l l o w e d by a common l e t t e r were not s i g n i f i c a n t l y d l f f e r t at 5% l e v e l by Duncan's m u l t i p l e range t e s t . *. ** s i g n i f i c a n t at 5 and 1% l e v e l s , r e s p e c t i v e l y . _^ T a b l e 5.20 V a r i a n c e a n a l y s i s f o r aboveground biomass of D a c t y l 1s g l o m e r a t a and F e s t u c a r u b r a b e f o r e and a f t e r f e r t i l i z a t i o n . F . r u b r a l g / m J ) Source DF Date 1' Date 2 l A q e ( y e a r ) 1 3-4 2 . 1 6.5 G-7 7 . 9 25.8 Locat1on/Aqe Age 3-4 78* 2 * * * 0. 6a 1 .7a 77 3 . 5 b 1 1 . 4 b 6-7 75 9 , .9 c 31.1 d 74 5 .9 b 20.6 c F e r t i 1 1 z e r F' 5 . 2 17.0 U n f 4 . 8 15.4 F e r t . x A q e 1 Age 3-4 F 2 . 1 7.9 Unf 2 . 1 5 . 1 6-7 F 8 . 3 26 .0 Unf 7 .6 25.7 F e r t . x L o c t . / A g e 2 * * ^  Age 3-4 2. 1a L o c t . 78 F 0 .5 Unf 0 .7 1 . 3a 77 F 3 .6 13.8 b Unf 3 . 4 9.0ab Age 6-7 L o c t . 75 F 10 .8 37.7 d Unf 9 . 1 24.4 c 74 F 5 .7 14.2 b Unf 6 . 1 26.9 c D.glomerata + F . njbraCg/m 2) Source  S p e c l e s fn glomerata) (F. r u b r a ) SpeclesxAge Age 3-4 • 6-7 Sp.xLoct./Age Age 3-4 L o c t . 78 77 Age 6-7 L o c t . 75 74 Sp.xFert . F e r t . U n f e r t . Date 1 Date 2 1 D. g 5.7 16.2 F . r 1 4.3 16 . 2 D g 1 .7 7.5 F . r 2.4 5.6 D • g 9.6 24 .8 F . r 6.3 26.8 2 * * * D. g 0. 2a 0. 7a F . r 1 . lab 2 . 6a D. g 3 . 3ab 14 . 2 b F . r 3 . 7ab 8. 6ab D. g 15. 2 c 46. 2 F . , r 4 . 7ab 16 . 0 b 0 g 4 , Oab 3 5a F . r 7 .8 37 .6 D 1 g 5 .3 22 .0 F . r 5 .O 1 1 .9 D • g 6 .0 10 . 3 F 3 .7 ' 20 .5 Source Sp.xFert.xAge Age 3-4 F e r t . U n f e r t . Age-6-7 F e r t . U n f e r t . D.g F .r D.g F .r D.g F .r D.g F . r DF 1 Sp.xFert.xL/A 2 SP.xBk/L/A 8 D.qlomerata + F.rubra(g/m 2) Date 1 Date 2 2 1 1 2 8 8 10 4 10 5 4 5 33.9 18.0 15 . 8 35.5 B l o c k / L o c t . / A g e 8 1. B e f o r e f e r t i l i z a t i o n : May 28 - June 6, 1980. 2. A f t e r f e r t i l i z a t i o n : J u l y 11-22. 1980. 3 . Year f e r t i 1 1 z e d . 4. F e r t i l i z e d . 5. U n f e r t i l i z e d . -» O Means f o l l o w e d by a common l e t t e r were not s i g n i f i c a n t l y d i f f e r e n t at 5% l e v e l by Duncan's m u l t i p l e range t e s t . *, ** s i g n i f i c a n t at 5 and 1% l e v e l s , r e s p e c t i v e l y . 171 Table 5.21 Covariance a n a l y s e s 1 for aboveground F. rubra biomass, t o t a l biomass (g/m2) and s o i l pH. Source  Age (year) 3-4 6-7 Location/Age 3 r4 18* 77 6-7 75 74 F e r t i l i z e r F * Unf 5 Fert.xAge Age 3-4 F Unf 6-7 F Unf Fert.xLoct./Age Age 3-4 Loct. 78 DF F.rubra F Unf F Unf F Unf F Unf Block/Loct./Age Age 6-7 Loct. 77 75 74 10. 22. 10. 10, 15. 28, 10, 22 4 0 6 1 1 9 3 1 11.6 9.1 8.9 35. 1 ** 12.1a 9.1a 11.1a 9.2a 6, 23, 1 1 , 46, ** 4a 8 b 3a 4 c t o t a l biomass 2 -135.2 620.4 * -169.3a -101.1a 568.0 b 672.3 c * 177.2 307.8 * -125.9a -144.5a 480.3 b 760.0 c -155, -183, - 96, -105, 417 718 543 801 2 4 7 4 8 2 2 ,9 pH 7. 7. 7. 7. 7. 7. 7. 7, 7, 7, 7, 7 * 8 4 ,8 ,8 ,3 ,6 .5 .7 .7 .8 .2 .6 7.8 be 7.7 be 7.7 be 8.0 c 7.0a 7.6 be 7.5 b 7.6 b 1. Sect ion 5.4. 2. The r e s u l t s were rather c o n t r o v e r s i a l . A f t e r adjustment of means by covariance a n a l y s i s , some means had negative values. 3. Year revegetated. 4. F e r t i l i z e d 5. U n f e r t i l i z e d Means followed by a common l e t t e r were not s i g n i f i c a n t l y d i f f e r e n t at 5% l e v e l by Duncan's m u l t i p l e range t e s t . *, s i g n i f i c a n t at 5 and 1% l e v e l , r e s p e c t i v e l y . 172 f o r some time w i t h o u t much change i n t h e e x i s t i n g v e g e t a t i o n physiognomy. 5.4.3 I n t e r r e l a t i o n s h i p s I n t h i s S e c t i o n d i s c u s s i o n o f the d a t a i s f u r t h e r d e v e l o p e d t o s y n t h e s i z e an o v e r a l l p i c t u r e o f v e g e t a t i o n changes o b s e r v e d on t h e r e c l a i m e d a r e a s . The heterogeneous v e g e t a t i o n and a s s o c i a t e d e d a p h i c f a c t o r s combine t o p r o v i d e an e x c e l l e n t o p p o r t u n i t y t o s t u d y many a s p e c t s o f v e g e t a t i o n dynamics as w e l l as c h r o n o l o g i c a l sequences on r e c l a i m e d a r e a s o f d i f f e r e n t ages. G e n e r a l o b s e r v a t i o n s and t h e accumulated d a t a showed t h a t t h e p l a n t communities o f t h e r e c l a i m e d a r e a s o f d i f f e r e n t ages were u n d e r g o i n g dynamic changes i n g r o s s c o m p o s i t i o n o f aboveground biomass o f b o t h g r a s s e s and legumes. When t h e legumes were p o o r l y e s t a b l i s h e d , g r a s s e s tended t o compensate by o c c u p y i n g t h e a v a i l a b l e s p a t i a l n i c h e , and v i c e v e r s a ( F i g u r e s 5.40 - 5.42). Many v a r i a b l e s a f f e c t e d t h i s b a l a n c e , some o f whi c h were i n t r i n s i c (edaphic c h a r a c t e r i s t i c s o f f r e s h s p o i l s ) and o t h e r s e x t r i n s i c ( r e s u l t s o f b i o t i c a c t i v i t y ) (sensu Daubenmire, 196 8 ) . The i n t r i n s i c v a r i a b l e s appeared t o be p r i m a r y f a c t o r s a f f e c t i n g t h e b a l a n c e o f e x i s t i n g v e g e t a t i o n , w h i l e the e x t r i n -s i c v a r i a b l e s were secondary because o f the r e l a t i v e l y young v e g e t a t i o n and s o i l s o f t h e r e c l a i m e d a r e a s . As time p r o -g r e s s e s the e x t r i n s i c v a r i a b l e s can be e x p e c t e d t o p l a y a more i m p o r t a n t r o l e i n i n f l u e n c i n g t h e b a l a n c e o f v e g e t a t i o n . 173 P r i m a r y e s t a b l i s h m e n t o f g r a s s e s and legumes was h e a v i l y i n f l u e n c e d by the i n i t i a l s e e d i n g , i t s r a t e , t i m i n g , e x i s t i n g m i c r o e n v i r o n m e n t s and f e r t i l i z e r t r e a t m e n t . Subsequent f e r t i l i z e r management f u r t h e r a f f e c t e d s o i l f e r t i l i t y and c o n s e q u e n t l y the v e g e t a t i o n , f a v o r i n g c e r t a i n s p e c i e s o f g r a s s e s , o r g r a s s e s over legumes and v i c e v e r s a . On the o l d e r s t a n d s , r a p i d l y i n c r e a s i n g l i t t e r and belowground biomass d e v e l o p as an i m p o r t a n t component o f t h e ecosystem o f t h e s e r e c l a i m e d a r e a s . Moreover, th e v i t a l i t y and r e p r o d u c t i o n ( s e x u a l o r a s e x u a l ) o f the i n t r o d u c e d p l a n t s p e c i e s c o u l d be e x p e c t e d t o have c o n t i n u e d i n c r e a s i n g e f f e c t s on t h e i r u l t i -mate s u c c e s s o r f a i l u r e i n t h e l o n g e r term. A l t h o u g h t h e o p e r a t i o n a l f e r t i l i z a t i o n program d i d not p r o v i d e u n i f o r m d i s t r i b u t i o n o f t h e f e r t i l i z e r o v e r the r e c l a i m e d a r e a s , t h e r e were i n d i c a t i o n s o f f e r t i l i z e r - i n d u c e d dynamic changes i n v e g e t a t i o n c o m p o s i t i o n , e.g. D a c t y l i s g l o m e r a t a v e r s u s F e s t u c a r u b r a , and g r a s s e s v e r s u s legumes on t h e o l d e r a r e a s . Of p a r t i c u l a r i n t e r e s t t o t h i s s t u d y was t h e performance of t h e legumes wh i c h were shown t o occupy a r e l a t i v e l y minor s p a t i a l n i c h e i n most o f t h e r e c l a i m e d a r e a s . T r i f o l i u m s p e c i e s , p r i n c i p a l components (30% by weight) o f t h e seed mix, were p a r t i c u l a r l y u n s u c c e s s f u l as compared t o overseeded Medicago s a t i v a . T h i s t r e n d o f poor legume e s t a b l i s h m e n t c o u l d be e x p e c t e d t o c o n t i n u e i n t h e f u t u r e because o f t h e o b s e r v e d absence o f young legume s e e d l i n g s . T r i f o l i u m spp. c o u l d i n c r e a s e v e g e t a t i v e l y ( s t o l o n s ) i f r e d u c t i o n o f the g r a s s 174 c o m p e t i t i o n were .achieved (e.g. reduced n i t r o g e n f e r t i l i z e r a p p l i c a t i o n ) . Medicago s a t i v a a l t h o u g h p r e s e n t l y showing v i g o r o u s growth i n d i c a t e d a low p o t e n t i a l f o r seed r e p r o d u c t i o n . T h i s s p e c i e s d i d produce i n f l o r e s c e n c e s on t h e r e c l a i m e d a r e a s , but e i t h e r t h e u n f a v o r a b l e environments o r l a c k o f i n s e c t s f o r p o l l i n a t i o n (Heath e t a l . , 1974) were thought t o be t h e main r e a s o n s o f t h e apparent absence o f s e e d l i n g s . Because most o f t h e M. s a t i v a s t a n d s were a p p a r e n t l y n ot r e p r o d u c i n g e i t h e r s e x u a l l y o r a s e x u a l l y , s t a n d v i g o r c o u l d be e x p e c t e d t o de c r e a s e as t h e y aged. I n t h e f u t u r e , M. s a t i v a w i t h a c r e e p i n g - r o o t h a b i t c o u l d be i n t r o d u c e d t o g i v e i n c r e a s e d p o t e n t i a l f o r v e g e t a t i v e m u l t i p l i c a t i o n i f t h e p r e s e n t c u l t i v a r i s not t h i s t y p e . 5.4.4 N a t i v e legumes L a b o r a t o r y g e r m i n a t i o n t e s t s showed t h a t L u p i n u s  s e r i c e u s had a 10/30 seeds g e r m i n a t i o n r a t e (one o b s e r v a t i o n ) d u r i n g t h e 19 day t e s t p e r i o d . S i m i l a r l y , A s t r a g a l u s a l p i n u s had an 11 ± 6/30 seeds (mean and s t a n d a r d d e v i a t i o n o f t h r e e o b s e r v a t i o n s ) . P r i o r t o the above g e r m i n a t i o n t e s t s , L. s e r i c e u s seeds were s c a r i f i e d w i t h a r a z o r b l a d e t o a s s i s t q u i c k g e r m i n a t i o n , w h i l e A. a l p i n u s seeds were s a c r i f i e d . The L. s e r i c e u s seed c o l l e c t e d i n 1979 i n c l u d e d many u n h e a l t h y seeds w h i c h were not i n c l u d e d i n t h e l a b o r a t o r y g e r m i n a t i o n t e s t s . The A. a l p i n u s seeds were a l l u n i f o r m and no seed s e l e c t i o n p r i o r t o t h e t e s t s was n e c e s s a r y . Each seed o f L. s e r i c e u s and A. a l p i n u s weighed a p p r o x i m a t e l y 28 and 3 mg 175 (average of 50 s e e d s ) , r e s p e c t i v e l y . A d d i t i o n a l seeds o f L. s e r i c e u s s u p p l i e d by B.C. C o a l L t d . had a 14/30 (one o b s e r v a -t i o n ) g e r m i n a t i o n r a t e . These seeds were c o l l e c t e d i n 1976 and k e p t a t low t e m p e r a t u r e s (about 5°C), i n d i c a t i n g t h a t L. s e r i c e u s seeds c o u l d remain v i a b l e f o r a t l e a s t t h r e e y e a r s . The seeds o f L. s e r i c e u s i n the f i e l d a l s o tended t o mature over a few weeks making seed c o l l e c t i o n d i f f i c u l t . F i e l d o b s e r v a t i o n s showed t h a t among the two n a t i v e legume s p e c i e s seeded th e g e r m i n a t i o n o f L. s e r i c e u s (4.3 -4.7/30 seeds) was much l e s s t h a n t h a t o f A. a l p i n u s (11.3 -20/30 seeds) ( F i g u r e 5.43 and T a b l e 5.22). I n b o t h s p e c i e s m o r t a l i t y o f t h e s e e d l i n g s was s l i g h t d u r i n g most o f May and June, but i n c r e a s e d as t h e summer p r o g r e s s e d . I t a l s o appeared t h a t added f e r t i l i z e r had a n e g a t i v e e f f e c t on s u r v i v a l . For L. s e r i c e u s o n l y 46% (1.7 o f 3.7) o f t h e p l a n t s i n e x i s t e n c e p r i o r t o f e r t i l i z a t i o n s u r v i v e d w h i l e on t h e u n f e r t i l i z e d p l o t 73% (2.7 o f 3.7) s u r v i v e d . S i m i l a r l y , on t h e f e r t i l i z e d p l o t o n l y 44% o f A. a l p i n u s s u r v i v e d as compared t o 82% (1.6.7 o f 20.0) on t h e u n f e r t i l i z e d . The r e a s o n s f o r poor s u r v i v a l of t h e two s p e c i e s on t h e f e r t i l i z e d p l o t s were not c l e a r and f u r t h e r i n v e s t i g a t i o n would be n e c e s s a r y t o u n d e r s t a n d them. These d a t a were not a n a l y s e d s t a t i s t i c a l l y s i n c e d a t a on s u r v i v a l was based on a s m a l l number of p l a n t s , and a t l e a s t some o f t h e p l a n t s f a i l e d t o s u r v i v e r o d e n t damage. A l t h o u g h the two legume s p e c i e s seeded d i r e c t l y on the r e c l a i m e d a r e a s u r v i v e d r e l a t i v e l y w e l l , t h o s e o f w i l d l i n g s and c o n t a i n e r - g r o w n s e e d l i n g s d i d not s u r v i v e a t a l l d u r i n g t h e A l B L C K B B 26m ED • 1 1 m rr 2 m J U2m ED EH 0 El • -2 m-| 6 m A l J I J f e r t . unf e r t . Area reclaimed i n 1975 • 0 f f l • 176 Aw As LwLs B B B B L* As Aw Lw A l Lw As Aw Ls B B • mo A I Ag El • El As Lw Ls Aw |Aw!As Ls -2m-l lmU-A l 1 1m J L f e r t . unf er t. Area reclaimed i n 1974 Figure 5.43 Layout of f i e l d t e s t p l o t s reclaimed i n 1974 and 1975. The diagram shows f e r t i l i z e r treatments, and l o c a t i o n s of s o i l and plant samplings (B), n a t i v e legumes planted and aluminum tubes i n s t a l l e d f o r acetylene reduction assay. Abbreviations of the legumes are: Ag, greenhouse grown Astragalus a l p i n u s s e e d l i n g s ; As, A. al p i n u s seeded; Aw, A. a l p i n u s Aw, A. al p i n u s w i l d l i n g s ; and Lw, Lupinus ser i c e u s w i l d l i n g s . Table 5.22 Effects of f e r t i l i z a t i o n on survival of Lupinus serlceus and Astragalus alplnus on 1974 area. M 161 M 21 J 2 u 9 0 .16 J 23 J L1 J L14 J 28 A 1 1 A 25 L . serIceus f e r t i l i z e d ' 4.0+2.6 4.311.2 4.311.2 4.311.2 3.7+1.5 3.311.2 3.311.2 3.311.2 3.0+1.0 2.310.6 1.711.2 u n f e r t i l i z e d 4.3+2.3 4.712.1 4.712.5 4.012.6 3.712.1 3.712.1 3.7+2.1 3.712.1 3.712.1 3.011.0 2.710.6 A. alplnus f e r t i l i z e d 10.713.1 10.713.1 11.314.0 10.715.5 10.715.5 10.7+5.5 8.315.5 8.0+5.0 7.3+4.0 5.312.1 4.7+1.5 u n f e r t i l i z e d 17.7+0.6 19.7+1.2 20.011.0 20.0+1.0 20.011.7 20.011.7 18.013.0 17.013.6 16.713.8 16.7+3.8 16.7+3.8 1. 1980. 2. F e r t i l i z e r (13-16-10) at 150 kg/ha on dune 20, 1980. The figures are means and standard deviations of three observations (number of seedlings and their survival per 30 seeds). 178 (a) (b) Figure 5.44 Seedlings of Lupinus s e r i c e u s and Astragalus a l p i n u s on 1974 area. ( a ) L. s e r i c e u s . (b) A. a l p i n u s . Photographed on May 12, 1980. 179 same p e r i o d a f t e r b e i n g t r a n s p l a n t e d t o the same a r e a . A few p l a n t s o f A. a l p i n u s s u r v i v e d a p p r o x i m a t e l y two months a f t e r t r a n s p l a n t a t i o n , then d i e d out b e f o r e the end o f August, 1980. T h i s p r e l i m i n a r y s u r v e y i n d i c a t e d t h a t d i r e c t s e e d i n g o f t h e s e n a t i v e legume s p e c i e s was p r o b a b l y a b e t t e r method f o r t h e i n t r o d u c t i o n o f t h e s e s p e c i e s on the r e c l a i m e d a r e a s t h a n t h e t r a n s p l a n t o f w i l d l i n g s o r greenhouse grown s e e d l i n g s . However, seed c o l l e c t i o n was o f t e n d i f f i c u l t as a r e s u l t o f the l a c k o f a v a i l a b i l i t y o f mature p l a n t s and the i r r e g u l a r m a t u r a t i o n o f t h e seeds. 5.4.5 Open system a c e t y l e n e r e d u c t i o n a s s a y 5.4.5.1 System development L a b o r a t o r y t r i a l L a b o r a t o r y r e s u l t s i n d i c a t e d t h a t a c e t y l e n e and e t h y l e n e gas c o u l d d i f f u s e 10 cm t h r o u g h t h e t e s t s p o i l s w i t h i n 5 minutes (Table 5.23). A c e t y l e n e was found i n a l l samples c o l l e c t e d a t t h r e e d i f f e r e n t time i n t e r v a l s e x c e p t No. 10. L e v e l s g e n e r a l l y d e c r e a s e d i n samples c o l l e c t e d a t l a t e r t ime p e r i o d s . However, i n some ca s e s (Tube Nos. 7 and 9) a c e t y l e n e l e v e l s a lmost do u b l e d a t t h e l a t e r t i m e , e.g. Tube No. 7, 460 v s . 842 a t 16 and 69 minutes a f t e r a c e t y l e n e i n j e c t i o n , r e s p e c t i v e l y . On the o t h e r hand e t h y l e n e was d e t e c t a b l e o n l y i n samples from Tube Nos. 3, 5 and 7 p l a c e d 10 cm away from the e t h y l e n e i n j e c t i o n tube (No. 2 ) , a l t h o u g h samples from Tube No. 9 d i d not have e t h y l e n e . F u r t h e r m o r e , a t no time was e t h y l e n e found i n any samples c o l l e c t e d from tubes (Nos. 4, 6, Table 5.23 Laboratory r e s u l t s of aluminum tubes tested f o r open system acetylene reduction assay. tube Nol d1 s . -Lenqth-dlaT 10-30-5 20-30-5 10-25-5 20-25-5 10 10-30-2 20-30-2 10-25-2 20-25-2 s a f t e r Injections of areas C 3 H 4 /C2H2 C,H, C7H4 C2H2 C7H4 % 16 5 1836 925 50 34 23 1244 577 46 69 58 1446 238 16 16 5 - - -34 23 252 0 0 69 58 189 0 0 16 5 1030 282 27 34 23 549 282 51 69 58 696 0 0 16 5 - - -34 23 388 0 0 69 58 191 0 0 16 5 460 135 29 34 23 447 0 0 69 58 842 0 0 16 5 - - -34 23 6662 0 0 69 58 6090 0 0 16 5 4569 0 0 34 23 6335 0 0 69 58 10850 0 0 16 5 - - -34 23 0 0 0 69 58 0 0 0 1. Shown in Figure 4.3. 2. Distance (cm) of tube No.3-10 to No.2; tube length (cm); and hole diameter (mm). Gas samples were not c o l l e c t e d from tube No.4. 6. 8, and 10 at the e a r l i e s t time Intervals Co O 181 8 and 10) p l a c e d 20 cm away from Tube No. 2. The above r e s u l t s i n d i c a t e d t h a t s a m p l i n g tubes s h o u l d be p l a c e d c l o s e r t h a n 20 cm from t h e s i m u l a t e d p l a n t (Tube No. 2) because no d e t e c t a b l e e t h y l e n e was found i n samples c o l l e c t e d from any o f the tubes p l a c e d a t 20 cm away from Tube No. 2. I t was e v i d e n t t h a t i n c u b a t i o n time s h o u l d be l e s s t h a n 69 minutes a f t e r a c e t y l e n e i n j e c t i o n s i n c e a c e t y l e n e l e v e l s tended t o decrease and e t h y l e n e c o u l d not be d e t e c t e d i n some samples c o l l e c t e d a f t e r t h e l o n g e r i n c u b a t i o n time (Tube Nos. 5 and 7 ) . P r e l i m i n a r y f i e l d t r i a l Based on t h e l a b o r a t o r y r e s u l t s v a r i o u s c o m b i n a t i o n s o f two d i f f e r e n t tube l e n g t h s and h o l e d i a m e t e r s were t e s t e d on L u p i n u s sp. and T r i f o l i u m sp. growing i n f i e l d s on t h e U n i v e r -s i t y o f B.C. campus (Table 5.24) . Among s i x samples c o l l e c t e d from an a s s a y u n i t on L u p i n u s sp. , o n l y one sample (from a 30 cm long-5 mm h o l e tube a t 60 minutes) had d e t e c t a b l e e t h y l e n e . Samples c o l l e c t e d from two u n i t s t e s t e d on T r i f o l i u m sp. showed a g e n e r a l d e c r e a s e i n e t h y l e n e as a p e r c e n t a g e o f a c e t y l e n e w i t h time e x c e p t samples from a 25 cm-5 mm t u b e . I n g e n e r a l a c e t y l e n e l e v e l s tended t o i n c r e a s e w i t h t ime i n most samples c o l l e c t e d from t h e t h r e e assay u n i t s i n s t a l l e d on t h e two s p e c i e s . W h i l e t h e a c e t y l e n e l e v e l was 3 l e s s than 20 x 10 i n most samples, t h o s e c o l l e c t e d from 25 cm-5 mm tubes showed a much h i g h e r a c e t y l e n e l e v e l . E t h y l e n e p e r c e n t a g e s o f t h e samples c o l l e c t e d from t h e 2 5 cm-182 Table 5.24 P r e l i m i n a r y f i e l d ( U n i v e r s i t y of B.C. Campus) r e s u l t s of aluminum tubes t e s t e d for open system acetylene system acetylene reduction assay. s p e c i e s  Lupinus sp, T r i f o l i u m sp, minutes a f t e r C2H4/C2H2 tube i n j e c t i o n of C lenqth-dia 1. C 2H 2 area(x10 3) % 30-5 15 3 0 30 1 5 0 40 0 0 60 36 1 .9 25-2 15 1 0 30 8 0 40 12 0 60 3 0 30-5 1 5 1 0 30 5 4.07 40 9 1 .96 60 1 4 1 .5 25-2 15 - -30 1 0 40 0 0 60 .10 0.99 25-5 1 5 - -30 1 502 0.07 40 2465 0.11 60 0 0 25-5 15 - -30 263 0.12! 40 23 0 60 1 1 59 0.09 1. Aluminum tube length (cm) and hole diameter (mm). A u n i t of three tubes was i n s t a l l e d as shown i n Figure 4.4. Samples were c o l l e c t e d on May 24, 1980. 183 5 mm tubes a l s o tended t o be lower t h a n t h o s e o f t h e samples c o l l e c t e d from o t h e r t u b e s . The r e s u l t s o f t h i s t r i a l r e f l e c t b o t h t h e s t r e n g t h s and weaknesses o f t h i s system as a u s e f u l f i e l d a s s a y . There was an i n d i c a t i o n t h a t a 60 minute i n c u b a t i o n was most d e s i r -a b l e because o f t h e h i g h f r e q u e n c y o f e t h y l e n e d e t e c t i o n i n thes e s a m p l i n g s . N e v e r t h e l e s s , samples w h i c h had d e t e c t a b l e e t h y l e n e a t e a r l i e r samples t i m e s sometimes gave z e r o r e a d i n g s on the s i x t y minute samples; s a m p l i n g t e c h n i q u e may be an i m p o r t a n t f a c t o r . The e r r a t i c r e s u l t s i n T a b l e 5.24 r e l a t i n g t o t h e r e l a t i o n s h i p o f e t h y l e n e / s a m p l e and time may be a t t r i -b u ted t o one o r more o f t h e f o l l o w i n g f a c t o r s : (1) the i n f l u e n c e o f s o i l m o i s t u r e o r t h e presence o r absence o f r o c k s i n t h e s o i l on t h e d i f f u s i o n p a t t e r n o f t h e e t h y l e n e and a c e t y l e n e . (2) absence o f any c o n t r o l on the d i f f u s i o n p a t t e r n once t h e a c e t y l e n e has been i n j e c t e d i n t o t h e s o i l . (3) s o i l t y p e : t h e s o i l o f t h i s t e s t i s a sandy t e x t u r e d s o i l . E v i d e n c e from o t h e r t r i a l s (F.B. H o l l , unpub-l i s h e d ) i n our l a b o r a t o r y i n d i c a t e d some problems w i t h p l u g g i n g o f t h e h o l e s i n the t u b e s , p a r t i c u l a r l y t h o s e o f 2 mm d i a m e t e r . (4) sample d i s t r i b u t i o n i n t h e tube may not n e c e s s a r i l y be homogeneous and t h e v a c u t a i n e r may thus draw an a t y p i c a l sample from the t u b e . The use o f a l o n g e r s a m p l i n g n e e d l e t o p r o v i d e some m i x i n g o f gases i n t h e tube and deeper p e n e t r a t i o n i n t o t h e sample r e g i o n s h o u l d e l i m i n a t e much o f t h i s d i f f i c u l t y . Because b o t h 30 and 2 5 cm l o n g tubes produced samples w i t h measurable e t h y l e n e , e i t h e r tube l e n g t h was p o t e n t i a l l y u s a b l e f o r t h e proposed open system. S i m i l a r l y , t h e r e was no c l e a r l y d e f i n e d p r e f e r e n c e f o r h o l e s i z e , i . e . 2 and 5 mm i n d i a m e t e r . I n view o f t h e c o a l s p o i l t e x t u r e i n w h i c h c o a r s e 184 fragments ( >2mm) dominate and r a p i d gas d i f f u s i o n c o u l d o c c u r , a f u r t h e r i n v e s t i g a t i o n o f t h e p o t e n t i a l o f a 30 cm long-2 mm h o l e s a m p l i n g tube f o r t h e proposed open system was u n d e r t a k e n . Comparison o f open and c l o s e d systems A comparison o f open and c l o s e d systems showed a r e l a -t i v e l y c l o s e r e l a t i o n s h i p i n e t h y l e n e p e r c e n t a g e s , c o n s i d e r i n g t h e l a r g e d i f f e r e n c e between th e two systems i n background a c e t y l e n e l e v e l (Table 5.25). Sampling tubes p l a c e d i m m e d i a t e l y a d j a c e n t t o a t e s t p l a n t produced samples t h a t showed e t h y l e n e p e r c e n t a g e s t h a t d e v i a t e d l e s s from t h o s e o f t h e c l o s e d system t h a n from t h o s e o f t h e tubes p l a c e d f a r t h e r away from the . 1.;. p l a n t . A c e t y l e n e l e v e l s tended t o d e c l i n e as t h e tubes were l o c a t e d f a r t h e r from t h e p l a n t . An i n c u b a t i o n time o f 60 minutes appeared t o be as e f f e c t i v e as 30 m i n u t e s , s i n c e samples from b o t h time i n t e r v a l s had r e l a t i v e l y s i m i l a r a c e t y -l e n e l e v e l s and e t h y l e n e p e r c e n t a g e s . A l t h o u g h t h e s a m p l i n g tubes p l a c e d r i g h t b e s i d e the t e s t p l a n t (0 cm i n T a b l e 5.25) produced t h e most r e l i a b l e samples w i t h r e s p e c t t o e t h y l e n e p e r c e n t a g e , i t was s u s p e c t e d t h a t t h i s might s e v e r e l y damage a p l a n t growing i n mine s p o i l s w h i c h c o n s i s t e d p r i m a r i l y o f c o a r s e fragments. T h e r e f o r e a s a m p l i n g tube d i s t a n c e 10 cm away from a t e s t p l a n t was c o n s i d e r e d t o be a r e a s o n a b l e compromise. Based on t h e s e r e s u l t s , a c o m b i n a t i o n o f 6 0 minutes i n c u b a t i o n time and a s a m p l i n g tube d i s t a n c e o f 10 cm was c o n s i d e r e d t o be most r e a s o n a b l e and p r a c t i c a l . 185 Table 5.25 P r e l i m i n a r y f i e l d ( U n i v e r s i t y of B.C. campus) t e s t r e s u l t s : sampling tube d i s t a n c e from a t e s t plant for open system acetylene reduction assay. min. a f t e r aluminum tube i n j e c t i o n of area C 2H 4/C 2H 2 d i s . - l e n g t h - d i a 1 . C 2H 2 C 2 H a ( x l O 3 ) % 0-30-2 30 248 0.87 30 229 0.83 60 274 0.87 10-30-2 30 10 1 .97 60 24 1 .97 20-30-2 30. 0 0 60 1 '7.4 1. Distance (cm) from a t e s t p l a n t , T r i f o l i u m sp.; tube length (cm); and hole diameter Cmm). An acetylene i n j e c t i o n tube was i n s t a l l e d 10 cm away from the t e s t p l a n t . A cl o s e d system using one l i t e r polyethylene j a r (60-65 minute incubation) showed acetylene area 23550 ± 6670 (X10 3) and C 2H 4/C 2H 2 percentage 0.050 ± 0.004 (means and standard d e v i a t i o n s of three o b s e r v a t i o n s ) . 186 5.4.5.2 Open system t r i a l a t mine s i t e T a k i n g i n t o c o n s i d e r a t i o n t h e r e s u l t s d i s c u s s e d i n S e c t i o n 5.4.5.1, t h e system shown i n F i g u r e s 4.4 and 5.45 was de v e l o p e d f o r t e s t i n g on t h e s u b a l p i n e mine s i t e where 24 such u n i t s were i n s t a l l e d i n 1980. Open system s a m p l i n g was conducted on two d a t e s , a f t e r w h i c h p l a n t s were i m m e d i a t e l y u p r o o t e d and r e a s s a y e d i n a c l o s e d system i n an attempt t o compare t h e e t h y l e n e p e r c e n t a g e s o b t a i n e d by the two methods. Complete raw d a t a o b t a i n e d from the above t r i a l a r e l i s t e d i n APPENDIX 6. Out o f 48 s e t s o f samples c o l l e c t e d , o n l y 10 o f them showed r e a s o n a b l e e t h y l e n e p e r c e n t a g e s i n b o t h open and c l o s e d a s s a y s ( F i g u r e 5.46). The r e s u l t s i n d i c a t e d t h a t t h e e t h y l e n e p e r c e n t a g e s o f t h e two a s s a y s were somewhat r e l a t e d t o each o t h e r , but p r e c i s e c a l i b r a t i o n o f e t h y l e n e o b t a i n e d by the open system w i t h t h o s e o f t h e c l o s e d system was not f e a s i -b l e because o f t h e l a r g e v a r i a t i o n and s m a l l number o f samples. I t was a l s o apparent t h a t s e p a r a t e c a l i b r a t i o n s a c c o r d i n g t o legume s p e c i e s might be r e q u i r e d because e t h y l e n e p e r c e n t a g e s o f T r i f o l i u m spp. and Medicago s a t i v a c l u s t e r e d s e p a r a t e l y . T h e i r r e g r e s s i o n e q u a t i o n s and c o r r e l a t i o n c o e f f i c i e n t s a r e shown below: M. s a t i v a Y = 0.1213 + 97.4047 x r = 0.8676 T r i f o l i u m spp Y = 0.9228 - 13.7093 x r = 0.8490 A d d i t i o n a l open system a s s a y s w i t h o u t comparable c l o s e d system comparisons were conducted on t h e r e c l a i m e d a r e a s . The 187 Figure 5 . 4 5 I n s t a l l a t i o n of open system acetylene r e d u c t i assay u n i t s on legumes of reclaimed areas. Refer to Figure 4 . 4 . Photographed J u l y 4 , 198©. 188 open s ystem C 2 H 4 (%) 0 | I ~ 1 r~ 0 0.0 2 0.04 0.06 C 2 H 4 ( % ) c l o sed system Figure 5.46 An ethylene percentage comparison of open and closed systems t e s t e d on reclaimed areas. Ethylene percentages of an open system were p l o t t e d against those of a cl o s e d system. The open system sampling (non-d e s t r u c t i v e to p l a n t s ) was c a r r i e d out p r i o r to the cl o s e d system ( d e s t r u c t i v e ) using the same p l a n t s . Summer of 1980. • M. s a t i v a . o T r i f o l i u m spp. 189 raw d a t a are c o m p i l e d i n APPENDIX 5. Out o f 288 gas samples c o l l e c t e d , 68 had measurable e t h y l e n e ; samples f e l l i n t o t h r e e groups based on a s s o c i a t e d a c e t y l e n e l e v e l s as shown i n T a b l e 5.26. The r e s u l t s showed a t r e n d o f i n c r e a s e d a c e t y l e n e l e v e l s i n t h o s e samples w i t h measurable e t h y l e n e compared t o t h o s e w i t h o u t measurable e t h y l e n e : a c e t y l e n e l e v e l s (of samples p o s i t i v e i n e t h y l e n e ) 205 ± 208 and 156 ± 137 f o r f e r t i l i z e d and u n f e r t i l i z e d p l o t s ; and t h o s e n e g a t i v e i n e t h y l e n e 41 ± 6 3 and 41 ± 52, r e s p e c t i v e l y . These o b s e r v a t i o n s t o g e t h e r w i t h o t h e r s d e r i v e d from T a b l e 5.26 can be summarized as f o l l o w s : 1. There was a g e n e r a l t r e n d t h a t the p e r c e n t a g e o f samples p o s i t i v e i n e t h y l e n e i n c r e a s e d as the a s s o c i a t e d a c e t y l e n e l e v e l s i n c r e a s e d . 2. E t h y l e n e l e v e l s o f t h e samples c o l l e c t e d a f t e r one hour i n c u b a t i o n v a r i e d w i t h i n a r e a s , but samples from 1974 a r e a s tended t o have h i g h e r e t h y l e n e l e v e l s t h a n o t h e r a r e a s . A l t h o u g h t h e u n i t d e v e l o p e d i n t h i s s t u d y was l i m i t e d t o d e t e c t i o n o f t h e presence o r absence o f e t h y l e n e , c a l i b r a -t i o n w i t h t h e c l o s e d system o f e t h y l e n e l e v e l s o b t a i n e d by the open system appeared f e a s i b l e . M a i n t a i n i n g a h i g h background a c e t y l e n e l e v e l appeared t o be a p o s s i b l e key f o r a f i r s t s t a g e improvement. T h i s would i n v o l v e a d d i t i o n a l i n v e s t i g a -t i o n s o f : i n c u b a t i o n t i m e , tube l e n g t h and h o l e d i a m e t e r , s a m p l i n g tube d i s t a n c e from a t e s t p l a n t and amount o f a c e t y -l e n e i n j e c t e d . I f t h i s open system c o u l d be f u r t h e r r e f i n e d f o r q u a n t i t a t i v e use, i t would be u s e f u l i n n i t r o g e n f i x a t i o n T a b l e 5.26 Presence and absence of e t h y l e n e d e t e c t e d by gas chromatography: open system a c e t y l e n e r e d u c t i o n assay on r e c l a i m e d a r e a s . range of C ? H o ( x 1 0 3 ) C1H4 F e r t i 1 1 z e d p l o t s 0-50 + 1978 a r e a 1977 a r e a 1975 a r e a 1974 a r e a t o t a l d a t e l 1 2' 9 d a t e 2 2 0 11 d a t e l 1 16 date2 0 15 d a t e l 3 10 date2 0 17 d a t e l 2 1 date2 1 2 date1+2 9 81 (%) (10) (90) 51 - 100 + 1 1 0 3 1 0 0 2 1 3 0 0 1 0 1 1 5 10 (33) (67) 101-1000 ^ + 4 1 4 0 0 0 0 1 0 1 0 1 14 0 5 8 27 12 (69) (31) mean + S t . Dev. 52 + 58 ' 60+60 16±22 23 + 35 51+78 24±23 309+267 166196 U n f e r t 1 1 1 z e d p l o t s 0-50 + 1 10 0 13 0 16 0 15 0 1 1 0 14 1 5 0 2 2 86 (2) (98) 51 - 100 + 1 1 0 5 1 0 0 3 0 2 0 2 2 O 1 5 5 18 (22) (78) 101-1000 + 3 2 , 0 0 1 0 0 0 0 5 0 • 2 10 0 6 4 20 13 (61) (39) mean ± S t . Dev. 57+54 37±31 21+28 28±28 72±91 41+36 169±185 105+50 1. June 24-25, 1980 Immediately a f t e r f e r t i l i z e r t r eatment on June 17-20, 1980. 2. J u l y 31 - August 1, 1980 a f t e r the f e r t i l i z e r t r e a t m e n t . 3. Number of gas samples i n which e t h y l e n e was r e c o r d e d by G .C. 4. Real e t h y l e n e c o n c e n t r a t i o n s 1n a r b i t r a r y u n i t . A t o t a l o f 72 a s s a y u n i t s were I n s t a l l e d on f o u r a r e a s (18 u n i t s each) r e c l a i m e d 1n d i f f e r e n t y e a r s . S a m p l i n g was done t w i c e . T h i s d e s i g n p r o v i d e d 72 (4 x 18) gas samples/area. Presence and absence of e t h y l e n e r e c o r d e d by gas chromatography were c a t e g o r i z e d a c c o r d i n g t o the a c e t y l e n e c o n c e n t r a t i o n ( a r b i t r a r y u n i t ) . O 191 s t u d i e s of legumes on mine s p o i l s or nit r o g e n f i x i n g woody pl a n t s i n f o r e s t where uprooting of the p l a n t i s g e n e r a l l y not f e a s i b l e . 192 6. GENERAL DISCUSSION F i e l d s t u d y o f t h e s u b a l p i n e r e c l a i m e d a r e a s r e v e a l e d n a t u r a l and man-induced dynamic r e l a t i o n s h i p s between p l a n t and s o i l f a c t o r s . The r e l a t i o n s h i p s were complex, but mani-f e s t e d s e v e r a l u n d e r l y i n g e c o l o g i c a l p r i n c i p l e s . F i r s t , i n i t i a l r e v e g e t a t i o n on mined-lands can be d e f i n e d as a p r i m a r y s u c c e s s i o n , a l t h o u g h t h i s may not be s t r i c t l y a p p r o p r i a t e when a p p l y i n g Daubenmire 1s (1969) concept i n w h i c h p r i m a r y bare a r e a s a r e d e f i n e d as t h o s e w h i c h are formed by r e c e n t l y a c t i v e n a t u r a l p h y s i o g r a p h i c p r o c e s s e s . * N o n e t h e l e s s , r e v e g e t a t i o n c o u l d , i n p r i n c i p l e , be viewed as a component o f a p r i m a r y s e r e where the o b s e r v e d p l a n t - s o i l dynamic changes too k p l a c e . Second, th e p l a n t - s o i l dynamics, viewed i n c h r o n o l o g i -c a l sequence, underwent s t e a d y c o n t i n u o u s changes where e x t r i n s i c e f f e c t s as a r e s u l t o f b i o l o g i c a l a c t i v i t y on e d a p h i c f a c t o r s were b e l i e v e d t o become i n c r e a s i n g l y i m p o r t a n t i n t h e development o f t h e i n t r o d u c e d p l a n t community. I n t r i n s i c c h a r a c t e r i s t i c s o f f r e s h s p o i l s had s t r o n g , o f t e n c h r o n i c , e f f e c t s on t h e i n i t i a l and subsequent e s t a b l i s h m e n t o f t h e i n t r o d u c e d p l a n t s p e c i e s . Moreover, i n d i g e n o u s c h a r a c t e r i s t i c s o f t h e f r e s h s p o i l s a p p a r e n t l y i n t e r a c t e d w i t h v a r i o u s o n going r e v e g e t a t i o n p r a c t i c e s on p r i m a r y p l a n t e s t a b l i s h m e n t . Over-a l l , t h i s p r o c e s s r e f l e c t s the s o i l development concept o u t l i n e d by Jenny (1941): s o i l i n c o n j u n c t i o n w i t h v e g e t a t i o n 193 d e v e l o p s as a f u n c t i o n o f c l i m a t e , t i m e , p a r e n t g e o l o g i c a l m a t e r i a l , r e l i e f and o r g a n i s m s . T h i r d , p l a n t c o m p e t i t i o n w i t h i n o r between g r a s s and legume s p e c i e s was an i m p o r t a n t p r i n c i p l e which had p l a y e d a v i t a l r o l e i n p l a n t community development. C o m p e t i t i o n e f f e c t s , p a r t i c u l a r l y between g r a s s and legume s p e c i e s , were not always c l e a r l y shown on the e x i s t i n g v e g e t a t i o n . o f r e c l a i m e d s i t e s , but t h e i r i mportance was s u b s t a n t i a t e d i n t h e s e p a r a t e greenhouse pot t e s t s . F i n a l l y , n a t i v e s p e c i e s c o l o n i z a t i o n o f t h e r e c l a i m e d a r e a can be viewed as secondary s u c c e s s i o n . I t i s w e l l - r e c o g n i z e d t h a t s u b a l p i n e environments are g e n e r a l l y u n f a v o r a b l e t o p l a n t growth as i t i s g e n e r a l l y viewed i n an agronomic c o n t e x t ( B i l l i n g s , 1973 and Brown e t a l . , 1978). The d a t a c o m p i l e d i n t h i s s t u d y s u b s t a n t i a t e d t h e h a r s h s u b a l p i n e e n v i r o n m e n t s , e.g. a 5 cm s n o w f a l l o c c u r r e d a t t h e s t u d y a r e a as l a t e as June 3, 1980. F u r t h e r m o r e , a comparison o f e d a p h i c f a c t o r s between r e c l a i m e d a r e a s and t h e a s s o c i a t e d s u b a l p i n e f o r e s t r e v e a l e d b a s i c d i f f e r e n c e s i n t h e i r p h y s i c a l and c h e m i c a l p r o p e r t i e s . Of p a r t i c u l a r i n t e r -e s t were lower s o i l t e m p e r a t u r e s (10 cm depth) and pH, and h i g h e r s o i l m o i s t u r e i n t h e s u b a l p i n e f o r e s t . T h e i r b a s i c d i f f e r e n c e s s u g gested t h a t i n v a s i o n o f n a t i v e s p e c i e s t h a t o r i g i n a t e d from t h e s u b a l p i n e f o r e s t ( c o n s i d e r e d as a q u a s i -r e f u g i u m by t h e w r i t e r ) would be e x t r e m e l y slow whether o r not i m m i g r a t i o n o f d i s s e m i n u l e s o r p r o p a g u l e s i n t o t h e r e c l a i m e d a r e a s was s u c c e s s f u l . Indeed, E r y t h r o n i u m g r a n d i f l o r u m and 194 some mosses were t h e o n l y s p e c i e s w h i c h had s t a r t e d t o invade t h e o l d e s t r e c l a i m e d a r e a . The o b s e r v e d d i f f e r e n c e s between t h e d i s t u r b e d a r e a s and t h e n a t u r a l s u b a l p i n e v e g e t a t i o n c o u l d p r o v i d e i n f o r m a t i o n on p o t e n t i a l improvements o f mined l a n d s . Among many v a r i a b l e s a c r u c i a l f a c t o r l i m i t i n g p l a n t growth on the r e c l a i m e d a r e a s was a p p a r e n t l y s o i l m o i s t u r e , w h i c h i n t h e f o r e s t s o i l was e s t i m a t e d t o be f i v e t o t e n tim e s h i g h e r t h a n i n t h e r e c l a i m e d s i t e s . Hence, mid-summer drought c o u p l e d w i t h the c o o l , s h o r t growing seasons were a l s o l i k e l y t o have s e v e r e , n e g a t i v e e f f e c t s on i n i t i a l p l a n t e s t a b l i s h m e n t . A l t h o u g h i t was b e l i e v e d t h a t s o i l ( s p o i l ) o f r e c l a i m e d a r e a s had been improv-i n g i n water c o n t e n t because o f r a p i d w e a t h e r i n g o f s h a l e s and a c c u m u l a t i o n o f o r g a n i c m a t t e r s i n c e r e v e g e t a t i o n s t a r t e d , i t would r e m a i n , i n t h e near f u t u r e , f a r d i f f e r e n t from t h e f o r e s t s o i l i n t h i s r e s p e c t . The r e s u l t s o f t h e f i e l d s u r v e y , w h i c h attempted t o e v a l u a t e t h e o v e r a l l o n g oing r e v e g e t a t i o n , r e v e a l e d some i n t e r e s t i n g t e n d e n c i e s : i n s b i l pH, o l d e r o r s h a l l o w e r ( 0 - 5 cm) s o i l s b e i n g lower t h a n younger o r deeper ( 5 - 1 0 cm depth) s o i l s ; phosphorus, t h e i n v e r s e r e l a t i o n s h i p o f t h a t shown above f o r pH; and ammonium-nitrate n i t r o g e n , i r r e g u l a r v a r i a -o t i o n w i t h i n s a m p l i n g y e a r s , r e c l a i m e d a r e a s o f d i f f e r e n t ages, and s a m p l i n g d e p t h s . I n f i e l d t e s t s o f f e r t i l i z a t i o n e f f e c t s on p l a n t - s o i l r e l a t i o n s h i p s s i m i l a r r e s u l t s were o b s e r v e d . F e r t i l i z e r g e n e r a l l y a c i d i f i e d t he s o i l as a r e s u l t o f 195 t h e ammonium c o n t a i n e d i n t h e f e r t i l i z e r . The r e l a t i v e l y s m a l l change i n pH v a l u e was c o n s i d e r e d t o be an i m p o r t a n t f a c t o r i n f l u e n c i n g phosphorus a v a i l a b i l i t y , because o f t h e c l e a r i n v e r s e r e l a t i o n s h i p o f pH and phosphorus l e v e l s o b s e r v e d . A r a t h e r l a r g e i n c r e a s e i n a v a i l a b l e phosphorus was r e a l i z e d a f t e r f e r t i l i z a t i o n . T h i s i n c r e a s e was p r o b a b l y caused by t h e a d d i t i o n o f phosphorus i n the f e r t i l i z e r and by a d e c r e a s e i n phosphorus f i x a t i o n as a r e s u l t o f ammonium a c i d i f i c a t i o n on f e r t i l i z e d s i t e s . F e r t i l i z a t i o n a l s o tended t o i n c r e a s e n i t r o g e n l e v e l s much more i n t h e younger (age 3 - 4 ) t h a n i n the o l d e r (age 6 - 7 ) a r e a s , i n d i c a t i n g t h a t t h e a p p l i e d n i t r o g e n was absorbed more by p l a n t s w i t h l a r g e r biomass o r p o s s i b l y i m m o b i l i z e d i n the m i c r o b i a l p o p u l a t i o n s o f t h e o l d e r s i t e s w h i c h had l a r g e r amounts o f l i t t e r t h a n t h e younger a r e a s . V a r i a t i o n i n n i t r o g e n l e v e l s was a l s o l i k e l y t o be a f f e c t e d by a n n u a l v a r i a t i o n i n p r e c i p i t a t i o n on t h e s i t e s . The e x i s t i n g v e g e t a t i o n on the r e c l a i m e d a r e a s under-went dynamic changes, some o f w h i c h were c l o s e l y t i e d t o s o i l f a c t o r s w h i l e o t h e r s were l e s s so. Survey r e s u l t s showed t h a t t h e g r a s s e s were g e n e r a l l y more dominant t h a n t h e legumes. W i t h i n t h e g r a s s s p e c i e s o n l y two, D a c t y l i s g l o m e r a t a and F e s t u c a r u b r a , were predominant i n terms o f aboveground biomass. F i e l d t e s t s f u r t h e r s u p p o r t e d t h e c o n t e n t i o n t h a t f e r t i l i z a t i o n n o t o n l y i n c r e a s e d g r a s s biomass but a l s o changed i t s composi-t i o n : h i g h f e r t i l i t y g e n e r a l l y enhanced D. g l o m e r a t a and reduced F. r u b r a growth. When th e D. g l o m e r a t a biomass was 196 l o w e r , F. r u b r a tended t o o f f s e t t h a t biomass w h i c h l e d t o a c l e a r i n v e r s e r e l a t i o n s h i p between the two. T h e r e f o r e , D. g l o m e r a t a , r e p o r t e d t o have a r a p i d response t o f e r t i l i z a t i o n and c o m p e t i t i v e n e s s a t h i g h a l t i t u d e by Heath e t a l . , 1974 and B e r g , 1974, c o u l d l o s e i t s c o m p e t i t i v e edge over F. r u b r a a t low n i t r o g e n l e v e l s and produce a d r a m a t i c change i n t h e i r r e l a t i v e c o n t r i b u t i o n d u r i n g one growing season. I n a d d i t i o n t o s o i l n i t r o g e n , s e l f - s e e d i n g was s u s p e c t e d t o p l a y an i m p o r t a n t r o l e i n such c o m p o s i t i o n changes because o f d i f f e r e n c e s i n s p e c i e s p o p u l a t i o n d e n s i t y and i n f l o r e s c e n c e p r o d u c t i o n . I t appeared p r o b a b l e t h a t F. r u b r a was s u c c e s s -f u l l y r e s e e d i n g each y e a r . Moreover, the performance o f F. r u b r a c o u l d be r e l a t e d t o t h e i n f l u e n c e o f n a t u r a l s e l e c t i o n , s i n c e s e x u a l r e p r o d u c t i o n p e r m i t s g e n e t i c r e c o m b i n a t i o n and p o t e n t i a l improvement w h i c h c o u l d l e a d t o b e t t e r a d a p t a t i o n t o t h e s u b a l p i n e environment. Indeed, such improvement has been r e p o r t e d t o o c c u r f o r t h i s s p e c i e s i n two g e n e r a t i o n s ( S y l v e n , 1937). The o b s e r v e d u n i f o r m d i s t r i b u t i o n , dense p o p u l a t i o n and p o t e n t i a l f o r improved a d a p t a b i l i t y o f F. r u b r a were p r o b a b l y t h e main r e a s o n s f o r i t s i n c r e a s e i n biomass on t h e o l d e r o r u n f e r t i l i z e d p l o t s . I t i s p r o b a b l e t h a t F. r u b r a may p l a y an even more i m p o r t a n t r o l e i n t h e f u t u r e i f t h e m a i n t e n -ance f e r t i l i z e r a p p l i c a t i o n i s stopped p r i o r t o a c o r r e s p o n d i n g s t a b l e improvement i n e x i s t i n g s o i l f e r t i l i t y . I t i s w e l l known t h a t s o i l n i t r o g e n p e r se r educes legume n i t r o g e n f i x a t i o n ( R u s s e l l , 1973). I n r e a l i t y , however, a p p l i c a t i o n o f n i t r o g e n f e r t i l i z e r i s n e c e s s a r y i n most ca s e s 197 of o p e r a t i o n a l r e v e g e t a t i o n . Nitrogen may be a p p l i e d at seeding and/or l a t e r f o r maintenance. This a p p l i e d n i t r o g e n o f t e n c o n t r o l s a d e l i c a t e balance i n the p l a n t community regarding n i t r o g e n f i x a t i o n and biomass as demonstrated i n the greenhouse t e s t s . On the subalpine reclaimed areas, legumes o f t e n occupied a r e l a t i v e l y minor s p a t i a l niche. Their poor performance was l i k e l y a r e s u l t of e i t h e r poor i n i t i a l germination and establishment, or high m o r t a l i t y a f t e r i n i t i a l establishment because of severe grass competition as a consequence of the a p p l i e d maintenance f e r t i l i z e r . The greenhouse t e s t s demonstrated the p o t e n t i a l complex grass-legume r e l a t i o n s h i p s which could occur under f i e l d c o n d i -t i o n s . In general, grass seeding and ni t r o g e n f e r t i l i z e r treatments had much more e f f e c t than a legume seeding treatment on aboveground grass-legume biomass and n i t r o g e n f i x a t i o n . In grass-legume stands, grasses proved to be e f f i c i e n t and compe-t i t i v e n i t r o g e n consumers compared to the legumes, which supports s i m i l a r observations i n c l u d i n g those of Walker et a l . , (1956). However, s o i l n i t r o g e n was not always a f a c t o r i n grass-legume competition nor was i t the sole f a c t o r t h a t determined acetylene r e d u c t i o n e f f i c i e n c y . In such stands n i t r o g e n f i x a t i o n was c l o s e l y r e l a t e d to the legume biomass at a l l n i t r o g e n f e r t i l i z e r r a t e s t e s t e d . In view of the pot t e s t design, which i n v o l v e d high r a t e s of i n i t i a l phosphorus and potassium, one of the c r u c i a l f a c t o r s i n competition was a v a i l a b i l i t y of l i g h t . At higher n i t r o g e n f e r t i l i z e r r a t e s the grasses were t a l l e r i n s t a t u r e 198 and denser than t h o s e a t the lower r a t e s . I t was apparent t h a t an i n t e r m e d i a t e r a t e (50 kg/ha) was l i k e l y t o accommodate b o t h t h e g r a s s e s and the legumes w i t h r e s p e c t t o optimum l i g h t i n t e r c e p t i o n by t h e m i x t u r e . B i o l o g i c a l a d d i t i o n o f n i t r o g e n t o t h e ecosystem o f the r e c l a i m e d a r e a s has been r e p o r t e d t o be a key f a c t o r i n e s t a b l i s h i n g s e l f - s u s t a i n i n g p l a n t communities on mined-lands ( J e f f e r i e s e t a l . , 1981). Thus, legume e s t a b l i s h m e n t and p e r s i s t e n c e are i m p o r t a n t i n r e v e g e t a t i o n s t r a t e g i e s . A d i r e c t c omparison o f f i e l d s u r v e y d a t a and greenhouse t e s t r e s u l t s may supplement our a p p r e c i a t i o n o f grass-legume r e l a t i o n s h i p s (Table 6.1). I n pot t e s t s , grass-legume aboveground biomass p r o d u c t i o n i n 103 - 112 days was e q u i v a l e n t t o growth w h i c h took minimum o f 6 - 7 y e a r s t o a t t a i n on the s u b a l p i n e r e -c l a i m e d a r e a s i n s p i t e o f c o n t i n u o u s maintenance f e r t i l i z a -t i o n o f t h e l a t t e r . The legume c o n t r i b u t i o n t o t h e g r a s s -legume biomass was g e n e r a l l y much l e s s on r e c l a i m e d a r e a s t h a n i n t h e p o t t e s t s . T h i s o b s e r v a t i o n r e f l e c t e d the more e f f e c -t i v e e s t a b l i s h m e n t o f legumes i n greenhouse t r i a l s . N i t r o g e n o p e r a t i o n a l l y a p p l i e d (12 kg/ha) was a l s o much l e s s than t h e l e v e l (50 kg/ha) i n po t t e s t s w h i c h o p t i m i z e d biomass p r o d u c -t i o n and n i t r o g e n f i x a t i o n . Pot t e s t d a t a c l e a r l y i n d i c a t e d t h a t the o p e r a t i o n a l n i t r o g e n f e r t i l i z e r r a t e (12 kg/ha) c o u l d be i n c r e a s e d t o 50 kg/ha w i t h o u t d e c r e a s i n g legume e s t a b l i s h m e n t and t h a t legume s e e d i n g r a t e s c o u l d be i n c r e a s e d from 17 t o a t l e a s t 30 kg/ha. I t i s i m p o r t a n t t o note here t h a t the above c o m p a r i -T a b l e 6.1 A comparison of abovegrourd g r a s s and legume biomass o b t a i n e d by f i e l d survey anc greenhouse pot t e s t s Treatment c o m b i n a t i o n g r a s s : 1egume : n i t r o g e n (kg/ha) aboveground biomass c o n t r i b u t i o n  grassC/.) 1 egume(%) t o t a l (g/m* ) F i e l d survey' 39: 17: 12 ! D i t t o Di t t o D i t t o ( a r e a ( a r e a ( a r e a ( a r e a 1978 , 1977 . 1975, 1974, age 3 y e a r s ) age 4 y e a r s ) age 6 y e a r s ) age 7 y e a r s ) 18.5 95.2 93 . 3 63.6 81 .5(96. 1 ]) 4.8(17.4) 6.7(15.2) 36.4 (3.3) 91 93 234 238 Greenhouse pot t e s t s 4 -35:15:10 ( q u a s i - o p e r a t i o n a 1 , age 112 days) 23.0 35:15:25 ( q u a s 1 - o p e r a t i o n a l , age 103 days) 33.3 17.5:30:50 (maximized, age 103 days) 19.2 77.0(100.0) 66 . 7(100.0) 80.8(100.0) 262 306 442 1 E x t r a c t e d from T a b l e s 5.6 and 5.7, and F i g u r e 5.10. 2 Based on the s t a n d a r d seed mix at h i g h a l t i t u d e ( T a b l e 2.2) and n i t r o g e n f e r t i l i z e r ( 12 kg/ha) 1n a form of complete f e r t i l i z e r (112 kg/ha, 13-16-10) a p p l i e d at s e e d i n g ( K a i s e r Res. L t d . , 1978) 3. R e l a t i v e biomass (%) c o n t r i b u t e d by T r i f o l I u m spp. w i t h i n legume biomass. The b a l a n c e was Medicago s a t i v a . 4. E x t r a c t e d from Appendix 4. 200: son has t o be i n t e r p r e t e d c a r e f u l l y , because o f t h e o b s e r v e d i r r e g u l a r f e r t i l i z e r d i s t r i b u t i o n and the p o t e n t i a l d i f f e r e n c e s between pot t e s t s and f i e l d t e s t s , i . e . f e r t i l i z e r r a t e s d e t e r m i n e d by the pot t e s t s may not c o r r e s p o n d t o t h o s e under f i e l d c o n d i t i o n s because o f some o f t h e c o m p l i c a t i o n s d i s c u s s e d by Terman and M o r t v e d t (1978) (e.g. p l a n t response i n f l u e n c e d by n o n - t e s t n u t r i e n t s and l e n g t h o f growth p e r i o d s ) . Because o f the o b s e r v e d i r r e g u l a r d i s t r i b u t i o n and poor performance o f legume s p e c i e s on the r e c l a i m e d a r e a s , t h e i r r e s p o n s e s t o f e r t i l i z e r o r g r a s s c o m p e t i t i o n c o u l d not be a s s e s s e d q u a n t i t a t i v e l y . N o n e t h e l e s s , f i e l d o b s e r v a t i o n p r o -v i d e d some i n f o r m a t i o n p o t e n t i a l l y u s e f u l f o r f u t u r e r e v e g e t a -t i o n p r a c t i c e s . I n g e n e r a l T r i f o l i u m repens and T. hybridum p l a y e d a minor r o l e on t h e o l d e r a r e a s . However, i t was c l e a r t h a t some i n d i v i d u a l p l a n t s c o u l d p e r s i s t as l o n g as seven y e a r s a f t e r i n i t i a l e s t a b l i s h m e n t . Medicago s a t i v a , not i n c l u d e d i n t h e o r i g i n a l seed mix but overseeded l a t e r , was more v i g o r o u s t h a n T r i f o l i u m spp. on the o l d e r a r e a s . The d i f f e r e n c e s i n performance o f t h e s e legume s p e c i e s were p r o b a b l y caused by v a r i o u s f a c t o r s i n c l u d i n g c u l t i v a r s e l e c t i o n , l i f e span, p h y s i o l o g i c a l a d a p t a b i l i t y and, p o s s i b l y , Rhizobium s p e c i e s a d a p t a b i l i t y . I t was p r o b a b l e t h a t M. s a t i v a , was a b l e t o t a p under-ground water which was not a v a i l a b l e t o T r i f o l i u m spp. Heath e t a_l. (1974) s t a t e d t h a t r o o t s o f M. s a t i v a might p e n e t r a t e s o i l 9 m o r more w h i l e t h o s e o f T r i f o l i u m repens c o u l d p e n e t r a t e t o o n l y 1 m or more under f a v o r a b l e c o n d i t i o n s . 201 M o i s t u r e u t i l i z a t i o n was c o n s i d e r e d t o be one o f the main reaso n s f o r t h e r e l a t i v e l y b e t t e r performance o f M. s a t i v a under t h e o f t e n w a t e r - s t r e s s e d s u b a l p i n e environment. Because M. s a t i v a s t a n d s were a p p a r e n t l y not r e p r o d u c i n g e i t h e r s e x u a l l y o r a s e x u a l l y , s t a n d v i g o r c o u l d be e x p e c t e d t o d e c r e a s e w i t h age. A s i m i l a r t r e n d was l i k e l y t o a p p l y t o T r i f o l i u m spp. because o f t h e apparent l a c k o f s e x u a l r e p r o d u c -t i o n c o n t i n u e d w i t h l i m i t e d a s e x u a l p r o p a g a t i o n by s t o l o n s . The f i e l d s t u d i e s f u r t h e r r e v e a l e d a s t e a d y i n c r e a s e i n l i t t e r a c c u m u l a t i o n and belowground biomass as v e g e t a t i o n became o l d e r , a l t h o u g h accumulated l i t t e r on t h e o l d e r a r e a s decomposed r a p i d l y d u r i n g t h e e a r l y summer. F e r t i l i z a t i o n a l s o s i g n i f i c a n t l y s t i m u l a t e d t h i s p r o c e s s o f l i t t e r decompo-s i t i o n . L i t t e r , produced i n t h e f a l l a f t e r f e r t i l i z a t i o n , p r o b a b l y decomposed f a s t e r t h a n on the u n f e r t i l i z e d p l o t s because o f t h e a n t i c i p a t e d low C/N r a t i o s r e s u l t i n g from t h e h i g h e r n i t r o g e n c o n t e n t o f s h o o t s a f t e r f e r t i l i z a t i o n . Such enhanced l i t t e r d e c o m p o s i t i o n has an i m p o r t a n t i m p l i c a t i o n f o r n u t r i e n t c y c l i n g , p a r t i c u l a r l y i n s u b a l p i n e environments o f low f e r t i l i t y where d e c o m p o s i t i o n may be slow (Turner and S i n g e r , 1976). Thus the o b s e r v e d mode o f l i t t e r a c c u m u l a t i o n and d e c o m p o s i t i o n would p l a y an i n c r e a s i n g l y i m p o r t a n t r o l e on t h e ecosystem o f t h e r e c l a i m e d a r e a s as time p r o g r e s s e s , p a r t i c u l a r l y a f t e r maintenance f e r t i l i z a t i o n c e a s e s . The s t e a d y i n c r e a s e o f belowground biomass ( r o o t s ) on t h e o l d e r a r e a s i n r e l a t i o n t o aboveground biomass was l i k e l y t o i n c r e a s e the a b i l i t y o f t h e i n t r o d u c e d p l a n t community t o 202 b u f f e r sudden environmental changes because of the l a r g e r carbohydrate reserve p o t e n t i a l . I t appeared t h a t the observed c h r o n o l o g i c a l changes i n phytomass f r a c t i o n s provided i n c r e a s -i n g s t a b i l i t y or homeostasis to the community as i t became o l d e r . Nonetheless i t was c l e a r l y shown that the s o i l and vegetation on the reclaimed areas were s t i l l young and under-going r a p i d changes i n many respects and that present trends of increases i n l i t t e r and belowground biomass could be expected t o continue i n the immediate f u t u r e . Reclamation i s an i n t e r d i s c i p l i n a r y p r a c t i c e and no s i n g l e f a c t o r should be over-emphasized. Economic l i m i t a t i o n s as w e l l as p u b l i c a t t i t u d e s o f t e n play an important r o l e i n reclamation a c t i v i t i e s . The w r i t e r b e l i e v e s that the data presented here w i l l b e n e f i t future reclamation a c t i v i t i e s . 203 7. SUMMARY R e v e g e t a t i o n on a s u b a l p i n e mine s i t e may be r e g a r d e d e c o l o g i c a l l y as a s i m u l a t e d p r i m a r y s e r e because o f i t s g e o l o g i c a l l y - f r e s h s o i l and t o t a l absence o f v e g e t a t i o n . Development o f r e v e g e t a t i o n s t r a t e g i e s under such c o n d i t i o n s a r e dependent p r i m a r i l y upon u l t i m a t e o b j e c t i v e s . S u r f a c e m i n i n g a c t i v i t i e s not o n l y d e s t r o y v e g e t a t i o n i n s i t u but a l s o d i s t u r b l o c a l ecosystems which may i n f l u e n c e water systems and f i s h and w i l d l i f e h a b i t a t s . C o n t r o v e r s y i s o f t e n a s s o c i -a t e d w i t h t h e degree o f r e h a b i l i t a t i o n o f d i s t u r b e d s i t e s , p a r t i c u l a r l y w i t h r e s p e c t t o t h e e x t e n t o f v e g e t a t i o n r e s t o r a -t i o n and the s e l e c t i o n o f ' n a t i v e o r n o n - n a t i v e s p e c i e s . N a t i v e s p e c i e s a r e more adapted l o c a l l y and more l i k e l y t o be p e r s i s t -e nt t h a n t h e n o n - n a t i v e m a t e r i a l and may t h e r e f o r e be p r e f e r a b l e . However, n a t i v e s p e c i e s a re seldom c o m m e r c i a l l y a v a i l a b l e i n s u f f i c i e n t amounts a t an e c o n o m i c a l l y a c c e p t a b l e c o s t . The p r e s e n t s t u d y i n v e s t i g a t e d p i o n e e r p l a n t communities o f n o n - n a t i v e g r a s s and legume s p e c i e s t o e v a l u a t e t h e i r p o t e n t i a l f o r s e l f - s u s t a i n i n g p l a n t s u c c e s s i o n . The r e s u l t s o f t h i s i n v e s t i g a t i o n and i t s i m p l i c a t i o n s w i t h r e s p e c t t o s u c c e s s f u l l o n g - t e r m r e v e g e t a t i o n a re summarized i n t h e f o l l o w i n g s e c t i o n s . 20i+ P l a n t - s o i l dynamics (1) In the introduced grass-legume communities on the subalpine reclaimed (age 2 - 7 years) areas, r e l a t i v e c o n t r i b u t i o n s of aboveground grass and legume biomass v a r i e d s u b s t a n t i a l l y . Grasses g e n e r a l l y composed 62% of the aboveground biomass. Of the nine grass species included i n the seed mix only two, D a c t y l i s glomerata and Festuca rubra were dominant species i n terms of biomass. Since t h i s observation was common to a l l s i t e s i n the study, one might question the n e c e s s i t y of using a complex m u l t i - s p e c i e s mixture. An a l t e r n a t e mixture i s proposed in, the f i n a l s e c t i o n of t h i s summary. The r e l a t i v e c o n t r i b u t i o n s of T r i f o l i u m repens and and T. hybridum tended to d e c l i n e on o l d e r reclaimed areas, while that of Medicago s a t i v a c o n t r i b u t e d r e l a t i v e l y more. Nevertheless, the o v e r a l l legume c o n t r i b u t i o n d e c l i n e d w i t h age i n the absence of any evidence f o r s u b s t a n t i a l improvement i n s o i l f e r t i l i t y . The importance of the legume c o n t r i b u t i o n to the development of a s t a b l e ecosystem has been emphasized by J e f f e r i e s et a_l. (1981) . The poor p e r s i s t e n c e of legumes on these s i t e s suggests that present revegeta-t i o n s t r a t e g i e s are not producing the d e s i r e d o b j e c t i v e of s e l f - s u s t a i n i n g grass-legume communities le a d i n g u l t i m a t e l y t o secondary p l a n t succession. 205 (2) C o m p e t i t i o n between g r a s s and legume s p e c i e s i s one of the i m p o r t a n t p r i n c i p l e s i n f l u e n c i n g the development of p l a n t communities o f such m i x t u r e s . C o m p e t i t i o n e f f e c t s f o r s o i l n i t r o g e n were n o t c l e a r l y demonstrated on the e x i s t i n g v e g e t a t i o n o f r e c l a i m e d s i t e s because o f poor e s t a b l i s h m e n t and i r r e g u l a r d i s t r i b u t i o n o f legumes. However, t h e i r importance was s u b s t a n t i a t e d i n c o n t r o l l e d greenhouse t e s t s i n wh i c h g r a s s e s were r e v e a l e d t o be more e f f i c i e n t i n s o i l n i t r o g e n uptake t h a n were legumes. (3) The i n t r o d u c e d grass-legume communities on t h e sub-a l p i n e r e c l a i m e d a r e a s were s t i l l young and u n d e r g o i n g c o n t i n u i n g changes i n s p e c i e s i n t e r a c t i o n s and phytomass ( l i t t e r , aboveground, and belowground biomass) d i s t r i b u -t i o n . P r e s e n t i n c r e a s e s i n l i t t e r a c c u m u l a t i o n and belowground biomass c o u l d be e x p e c t e d t o c o n t i n u e i n the f o r e s e e a b l e f u t u r e . U l t i m a t e l y , one might e x p e c t a s h i f t t o i n c r e a s e d community s t a b i l i t y . However, t h e p r e s e n t dependence o f the ecosystem on c o n t i n u e d f e r t i l i z e r i n p u t s , and the r e l a t i v e e c o l o g i c a l i n s t a -b i l i t y o f t h e s i t e s a r e cause f o r c o n c e r n t h a t t h e s e a r e a s w i l l e v e r d e v e l o p a more s t a b l e p l a n t community. (4) The s p o i l m a t e r i a l s , d e r i v e d from v a r i o u s s t r a t i g r a p h i c l a y e r s and composed o f s e v e r a l g e o l o g i c a l m a t e r i a l s , d i f f e r i n c o m p o s i t i o n and response t o f a c t o r s such as 206 w e a t h e r i n g , c o n t r i b u t i n g a t l e a s t i n p a r t t o t h e obs e r v e d v a r i a b i l i t y i n t e x t u r a l d i s t r i b u t i o n . Non-s e l e c t i v e placement o f s p o i l s on the r e c l a i m e d a r e a s a l s o c o n t r i b u t e s t o the o v e r a l l h e t e r o g e n e i t y o f t h e s u b s t r a t e f o r p l a n t growth on t h e s e s i t e s . S p o i l v a r i a b i l i t y i s u n d e s i r a b l e from a p l a n t management p e r s p e c t i v e and may be reduced by c a r e f u l p l a n n i n g and s e l e c t i v e placement o f s p o i l s . On t h e r e c l a i m e d a r e a s , a l a r g e p o r t i o n (65 - 75%) o f the s p o i l s was composed o f c o a r s e ( >2 mm) fragments and t h e f i n e fragment ( <2 mm) f r a c t i o n s had low mois-t u r e l e v e l s (2 - 13%) t h r o u g h o u t June t o August, 1980. T h i s o b s e r v a t i o n c o u l d be i n t e r p r e t e d t o mean t h a t p l a n t s were s u b j e c t e d t o water s t r e s s and had l i m i t e d growth d u r i n g t h a t p e r i o d . Phosphorus l e v e l s tended t o be h i g h e r i n s o i l s ( s p o i l s ) o f o l d e r r e c l a i m e d a r e a s o r a t s h a l l o w d e pth t h a n i n s o i l s o f younger age or deeper. A v a i l a b l e s o i l ammonium and n i t r a t e tended t o be low i n s p i t e o f c o n t i n u e d f e r t i l i z e r management. The o b s e r v e d low l e v e l o f s o i l n i t r o g e n i s an u n d e s i r -a b l e f a c t o r f o r t h e p e r s i s t e n c e o f the p r e s e n t g r a s s -dominated communities. I t i s not u n u s u a l t o f i n d low m i n e r a l n i t r o g e n l e v e l s i n s t a b l e g r a s s l a n d s because o f an e f f i c i e n t n i t r o g e n uptake by t h e e x t e n s i v e r o o t systems. However, c o n s i d e r i n g the c o a r s e s o i l t e x t u r e and g e n e r a l l y poor ..vegetative c o v e r , the low l e v e l s o f 207 n i t r o g e n observed were b e l i e v e d to r e f l e c t the low ni t r o g e n s t a t u s of the reclaimed areas. There were wide d i f f e r e n c e s between the s o i l s of the reclaimed areas and the associated subalpine areas. S o i l s of the reclaimed areas were g e n e r a l l y warmer and d r i e r than those of the ass o c i a t e d f o r e s t and had l e s s than h a l f of the content of f i n e s o i l fragments ( <2 mm). Reclaimed s o i l s were g e n e r a l l y a l k a l i n e , while the subalpine f o r e s t s o i l was a c i d i c , w i t h a pH below 5.0. These environmental d i f f e r e n c e s suggest t h a t i n v a s i o n of n a t i v e species o r i g i n a t i n g from the subalpine f o r e s t w i l l be extremely slow. Greenhouse t e s t s showed that a treatment combination of 17.5 : 30 : 50 (grass seeding r a t e : legume seeding r a t e : n i t r o g e n f e r t i l i z e r r a t e , kg/ha) produced optimum aboveground grass-legume biomass and ni t r o g e n f i x a t i o n . Since t h i s combination i s q u i t e d i f f e r e n t to tha t p r e s e n t l y employed on these s i t e s , f u t u r e i n v e s t i g a t i o n i n the f i e l d should be undertaken to determine whether the same o p t i m i z a t i o n of p r o d u c t i v i t y and n i t r o g e n f i x a t i o n can be r e a l i z e d under f i e l d c o n d i t i o n s . Since the environment of these areas cannot be c o n t r o l l e d and much of the response that i s observed i n rev e g e t a t i o n s t u d i e s i s s i t e - s p e c i f i c , t h i s combination would not n e c e s s a r i l y be the most appropriate one. Nevertheless, i f one i s to e x p l o i t the a b i l i t y of legumes to c o n t r i -208 bute f i x e d n i t r o g e n t o t h e system, such a management scheme would r e p r e s e n t a u s e f u l s t a r t i n g p o i n t f o r f i e l d e v a l u a t i o n . Open system a c e t y l e n e r e d u c t i o n assay A m o d i f i c a t i o n o f the a c e t y l e n e r e d u c t i o n a s s a y , "the open system" t e c h n i q u e was d e v e l o p e d f o r e v a l u a t i o n o f legume n i t r o g e n f i x a t i o n . The open system assay has the f o l l o w i n g advantages o v e r c o n v e n t i o n a l c l o s e d system methods: (1) n o n d e s t r u c t i v e s a m p l i n g , (2) c o n t i n u o u s s a m p l i n g over t i m e , (3) wide a p p l i c a t i o n t o p l a n t s o f v a r i o u s s i z e s , and (4) e s t i m a t e s o f f i x a t i o n a c t i v i t y i n environments o t h e r -w i s e u n s u i t e d f o r c l o s e d system t e c h n i q u e s . A l t h o u g h the u n i t d e v e l o p e d i n t h i s s t u d y i s l i m i t e d t o d e t e c t i o n o f t h e p r e s ence o r absence o f e t h y l e n e , c a l i b r a t i o n w i t h the c l o s e d system o f e t h y l e n e l e v e l s o b t a i n e d by t h e open system appeared f e a s i b l e . M a i n t a i n i n g a h i g h background a c e t y l e n e l e v e l appeared -to be a p o s s i b l e key f o r a f i r s t s t a g e improvement. T h i s would i n v o l v e a d d i t i o n a l i n v e s t i g a -t i o n s o f : i n c u b a t i o n t i m e , tube l e n g t h and h o l e d i a m e t e r , s a m p l i n g tube d i s t a n c e from a t e s t p l a n t , e t c . I f t h i s open system c o u l d be f u r t h e r r e f i n e d f o r q u a n t i t a t i v e use, i t would be u s e f u l i n n i t r o g e n f i x a t i o n s t u d i e s o f legumes on mine s p o i l s , n i t r o g e n f i x i n g woody p l a n t s i n f o r e s t s , and legumes g r a s s l a n d sods where u p r o o t i n g o f t h e p l a n t might not be f e a s i b l e o r e f f e c t i v e . 209 Improvement o f r e v e g e t a t i o n s t r a t e g i e s (1) The greenhouse t r i a l s i n t h i s t h e s i s i n d i c a t e t h a t t h e s e e d i n g and f e r t i l i z e r r a t e s p r e s e n t l y employed on t h e B.C. C o a l L t d . s i t e may not o p t i m i z e p l a n t p r o d u c t i v i t y and t h e a b i l i t y o f legumes t o f i x n i t r o g e n s y m b i o t i c a l l y . O p e r a t i o n a l s c a l e f i e l d t r i a l s u s i n g t h e e x p e r i m e n t a l l y d e r i v e d c o m b i n a t i o n (17.5 : 30 : 50 kg/ha g r a s s s e e d i n g r a t e : legume s e e d i n g r a t e : n i t r o g e n f e r t i l i z e r r a t e ) would be d e s i r a b l e t o e v a l u a t e t h e s e d a t a on the s i t e . (2) The d a t a o f t h i s s t u d y and g e n e r a l o b s e r v a t i o n s on the s i t e , i n d i c a t e d t h a t c o n s i d e r a b l e a d d i t i o n a l s t u d y would be d e s i r a b l e i n t h e a r e a s o f legume seed germina-t i o n and e s t a b l i s h m e n t , t i m i n g o f s e e d i n g , s e l f - s e e d i n g c a p a b i l i t y o f components o f the m i x t u r e , s p e c i e s and v a r i e t y s e l e c t i o n , and s e l e c t i o n and use o f Rhizobium s p e c i e s f o r t h e legumes. A l t h o u g h none o f t h e s e a r e a s has been s p e c i f i c a l l y examined i n t h i s t h e s i s , i t i s a pparent t h a t i n f o r m a t i o n i s l a c k i n g on a p p r o p r i a t e t e c h n o l o g y f o r t h e s e a s p e c t s , p a r t i c u l a r l y w i t h r e s p e c t t o e x p l o i t a t i o n o f t h e legume-Rhizobiurn n i t r o g e n f i x i n g s y m b i o s i s on s u b a l p i n e s i t e s . (3) A l t h o u g h complex m i x t u r e s are a common recommendation f o r r e v e g e t a t i o n s i t e s , i t i s apparent t h a t many o f t h e s p e c i e s i n c l u d e d i n t h i s m i x t u r e are not p e r f o r m i n g w e l l . A s i m p l e r , more e f f e c t i v e c o m b i n a t i o n would 210 p r o b a b l y i n c l u d e D a c t y l i s g l o m e r a t a , F e s t u c a r u b r a , L o l i u m perenne, Poa compressa, Phleum p r a t e n s e and L o l i u m m u l t i f l o r u m . The l a t t e r s h o u l d be i n c l u d e d f o r r a p i d c o v e r i n the e s t a b l i s h m e n t y e a r . Medicago s a t i v a , not g e n e r a l l y recommended f o r such u s e s , i s a p p a r e n t l y d o i n g w e l l and c o u l d be i n c l u d e d . In t h i s i n s t a n c e , a c u l t i v a r such as Rhizoma o r A n i k w h i c h have a c r e e p i n g -r o o t e d h a b i t and known h a r d i n e s s would l i k e l y be d e s i r a b l e . The p o t e n t i a l f o r o t h e r legumes such as O n o b r y c h i s v i c i i f o l i a ( s a i n f o i n ) , V i c i a v i l l o s a ( h a i r y v e t c h ) and Medicago l u p u l i n a ( b l a c k medic) might a l s o be c o n s i d e r e d . (4) Improved c o n t r o l o f t h e o p e r a t i o n a l f e r t i l i z e r a p p l i c a -t i o n t o ensure more r e g u l a r d i s t r i b u t i o n would be d e s i r a b l e . G r e a t e r emphasis r e l a t i n g f e r t i l i z e r use t o e f f e c t i v e e x p l o i t a t i o n o f the legume component i s recommended. (5) Ongoing r e v e g e t a t i o n s t r a t e g i e s r e s u l t e d i n r e l a t i v e l y poor e s t a b l i s h m e n t o f s e l f - s u s t a i n i n g p l a n t communities and slow n a t u r a l c o l o n i z a t i o n . S o l u t i o n s t o t h e s e phenomena are complex. A s i g n i f i c a n t improvement i n r e v e g e t a t i o n s t r a t e g y may be made i n i n i t i a l m a t e r i a l (overburden o r s p o i l ) h a n d l i n g . At p r e s e n t s p o i l s are n o n - s e l e c t i v e l y p l a c e d on a r e a s t o be r e c l a i m e d . S o i l c o n d i t i o n s may be d r a m a t i c a l l y improved i f s p o i l s more co n d u c i v e t o p l a n t growth can be s e l e c t i v e l y p l a c e d on 21 1 the surf a c e . 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S t a n f i e l d , J . S . B a l l and J .W. H o m e . 1951. Green R i v e r o i l sha les and p r o d u c t s . O i l Shale and Cannel C o a l , P r o c . C o n f . , 2nd, 1950, 2 :301-341. I n s t . Of Pe t ro leum, London. T i s d a l e , S . L . and W.L . N e l s o n . 1969. S o i l f e r t i l i t y and  f e r t i l i z e r s . The Macmi l l an C o . , 694p. Turner , J . and M . J . S i n g e r . 1976. N u t r i e n t d i s t r i b u t i o n and c y c l i n g i n a sub-a lp ine c o n i f e r o u s f o r e s t ecosystem. J . A p p l . E c o l . 13(1) :295-301. 221 Vaar tnou , H . 1976. Revegetat ion r e s e a r c h . A progress repor t on work accomplished i n 1975. A l b e r t a A g r i c u l t u r e , Edmonton, A l b e r t a , 350p. V a l l i s , I . 1978. N i t rogen r e l a t i o n s h i p s i n grass/ legume m i x t u r e s . I n : P l a n t r e l a t i o n s i n p a s t u r e s , J . R . Wi l son ( e d . ) , C . S . I . R . O . , A u s t r a l i a , p p l 9 0 - 2 0 l . Van C l e v e , K . , L . A . V i e r e c k and R . L . S c h l e n t n e r . 1971. Accumulat ion of n i t r o g e n i n a l d e r (Alnus) ecosystems near F a i r b a n k s , A l a s k a . A r c t i c and A l p i n e Research 3(2) :101 -114. Van K e k e r i x , L . K . , R.W. Brown and R . S . Johns ton . 1979. S e e d l i n g water r e l a t i o n s of two grass spec ies on h i g h -e l e v a t i o n a c i d mine s p o i l s . USDA F o r . Se rv . INT-262, Intermounta in F o r . and Range Exp. S t n . , Ogden, U t a h , I7p. Van L e a r , D . H . 1971. E f f e c t s of s p o i l t e x t u r e on growth of K-31 t a l l f e scue . USDA F o r . S e r v . , NE Exp. S t n . , Upper Darby, P a . , Res. Note NE 141, 7p. Van Schreven, D . A . 1959. E f f e c t s of added sugars and n i t r o g e n on n o d u l a t i o n of legumes. P l a n t and S o i l 11:93-112. V i n c e n t , J . M . 1965. Environmenta l f a c t o r s i n the f i x a t i o n of n i t r o g e n by the legume. I n : Agronomy N o . H ) . So i 1 n i t r o g e n . American S o c i e t y of Agronomy Monograph, Madison, pp.354-435. Walker , D . , R .S . S ada s iv i ah and J . W e i j e r . 1977. The u t i l i z a t i o n and genet ic improvement of n a t i v e A l b e r t a grasses from the eas tern s lopes of the Rocky Mounta ins . Department of G e n e t i c s , U n i v . Of A l b e r t a , unpub l . Repor t , 52p. Walker , T . W . , A . F . R . Adams and H . D . O r c h i s t o n . 1956. Fate of l a b e l l e d n i t r a t e and ammonium n i t r o g e n when a p p l i e d to grass and c l o v e r grown separa te ly and t o g e t h e r . S o i l S c i . 81:339-351 . Ward, R . T . 1974. A concept of n a t u r a l v e g e t a t i o n b a s e l i n e s . I n : P r o c . Of a Workshop on r e v e g e t a t i o n of h i g h a l t i t u d e  d i s t u r b e d l a n d s . W.A. Berg , J . A . Brown and R . L . Cuany (eds . ) Colorado State U n i v . , F o r t C o l l i n s , C o . , p p . 2 - 4 . W a r r i n g t o n , N . 1976. T e s t i n g of legumes on v a r i o u s s o i l types . I n : Revegetat ion Research. A progress report on work accomplished i n 1975. H . Vaartnou (ed.) A l b e r t a A g r i c u l t u r e , Edmonton, A l t a . , pp.275-312. W i l l i a m s , P . J . H . 1975. I n v e s t i g a t i o n s i n t o the n i t r o g e n c y c l e i n c o l l i e r y s p o i l . I n : The Ecology of resource degradat ion  and renewal . M . J . Chadwick and G .T . Goodman (eds . ) 15th Symp. Of the B r i t i s h E c o l . S o c , John W i l e y & Sons, N . Y . , pp.259-274. 222 W i l s o n , W.H. 1965. The m i c r o b i o l o g y of s t r i p - m i n e s p o i l . West V i r g i n i a U n i v . A g r i c . Exp. S t n . , B u l l . 506 T . , 44p. W i t , C . T . de, P.W. Tow and G . C . E n n i k . 1966. Compet i t ion  between legumes and gra s se s . V e r s l . Landbouwk. Onderz. ( A g r i c . Res . Rep.) 687, Wageningen, 30p. Wi t tneben , U . 1969. S o i l s of the East Kootenay. I n : Lands of  the East Kootenay. Report to the B . C . S o i l C a p a b i l i t y for A g r i c u l t u r e and F o r e s t r y Committee, compi led by G . G . Runka, pp .17-32 . C i t e d i n Dick (1978). Worobec, A . 1979. Canadian mines handbook 1979-1980. Northern "Miner Press L t d . , Toronto , p .383 . Y o u n k i n , W.E. and W. F r i e s e n . 1976. Sans S a u l t r e v e g e t a t i o n t r i a l s . I n : Revegetat ion s t u d i e s i n the Northern Eng ineer ing S e r v i c e s Company L t d . for Canadian A r c t i c Gas Study L t d . B i o l . Rep. S e r i e s V o l . 3 8 , 28p. Z i e m k i e w i c z , P . F . 1979. E f f e c t s of f e r t i l i z a t i o n on the n u t r i e n t and organic matter dynamics of rec la imed coa l -mined areas and n a t i v e gras s lands i n southeastern B r i t i s h Columbia . P h . D . T h e s i s , U n i v e r s i t y of B . C . , 148p. 223 APPENDIX 1 Breakdown of variance analyses for acetylene r e d u c t i o n , biomass and s o i l f a c t o r s (pot t e s t 1) acetylene reduction aboveground biomass + Source 80 days 99 days grass legume t o t a l NH4 • biomass 1 N0 3" f P grass G l i n G dev ** ** ** ** ** ** ** * f e r t i l i z e r F l i n F dev ** ** ** ** ** ** ** ** ** * * * * ** ** G x L G l i n G dev x L x L * G x F G l i n G l i n G dev G dev x F l i n x F dev x F l i n x F dev ** ** ** * ** L x F L x F L x F l i n dev G x L x G l i n G l i n G dev G dev F x L x F x L x F x L x F x L x F * l i n dev ** l i n dev * * * * 1 . Above- plus belowground biomass. A l l biomass and s o i l samples were c o l l e c t e d 112 days a f t e r seeding. *, ** s i g n i f i c a n t at 5 and 1% l e v e l s , r e s p e c t i v e l y . APPENDIX 2 Breakdown of v a r i a n c e a n a l y s e s f o r a c e t y l e n e r e d u c t i o n , biomass and s o i l f a c t o r s (pot t e s t 2 ). A c e t y l e n e aboveground b 1 omass g r a s s * t o t a l NH4+ so u r c e 64 days 78 days 99 days g r a s s 1egume 1equme b1omass 1 NO3" g r a s s * + . * * * * * * * * * * * * * * G 1 1n * * * * * * * * * * * * * * * * G qua * * * * * * * * 9 dev * * * * f e r t 1 1 1 z e r * + * + * * * * + * * * * * F 1 In * * + * * * + * * * F dev * * * * * * * * * * * G x L * G 1 1n X L G qua X L G dev X L * * G x F * * * * * G 1 i n X F 1 In * * * * * * G 1 1n X F dev * G qua X F 1 1n * * * * G qua X F dev + * * G dev X F 1 1n * G dev X F dev * * L x F * * L x F 1 In * * * * * L x F dev G x L x F * * * * * * * * * * G 1 1n X L x F 1 In G 1 1n X L x F dev * * * G qua X L x F 1 1n * * * * * * G qua X L x F dev G dev X L x F 1 i n * * G dev X L x F dev * * * * * 1. Above- p l u s belowground biomass. Biomass and s o i l samples were c o l l e c t e d 103 and 52 days a f t e r s e e d i n g , r e s p e c t 1vely. ro -p-*, ** s i g n i f i c a n t at 5 and 1% l e v e l s . APPENDIX 3 Y i e l d v a r i a b l e s used to c a l c u l a t e the d i f f e r e n c e i n g r a s s and legume performance between two legume s e e d i n g r a t e s . R e f e r to T a b l e 5.13. f a c t o r s measured aboveground g r a s s biomass ( g / p o t ) aboveground legume biomass ( g / p o t ) ni t r o g e n f e r t 1 1 i z e r r a t e (kg/ha) 75 50 25 75 50 25 seed, r a t e 30 kg/ha aboveground g r a s s - 75 legume biomass (g/pot) 50 25 s o i l n i t r o g e n (NH + NO , ppm) a c e t y l e n e r e d u c t i o n (C H , 99 days, ppm) 75 50 25 75 50 25 g r a s s seed. r a t e i (kg/ha) g r a s s seed. r a t e I (kg/ha) 0 17 . 5 35 70 0 17 . 5 35 70 0.0 10. 9 11 . 6 15 . 6A ' 0. 0 8 . 1 12 . 4 15.4B 0.0 5. 9 10. 6 1 1 . 8 0. 0 4 . 5 8. 3 9. 1 0.0 4 . 4 5. 4 6. 4 0. 0 3 . 4 4 . 1 5.4 19.9 10. 7 4 . 6 5 . IC 17 . 2 9 . 7 8 . 8 4 . 5D 17.0 12 . 7 10. 8 9 . 2 16 . 4 18 . 9 13. 4 8.9 11.0 12 . 2 10. 8 8 . 6 16 . 2 15. 4 12 . 1 14 . 9 19.9 21 . 5 16. 2 20. 7E 17 . 2 17 . 8 21 . 2 19.9F 17.0 18 . 6 20. 7 21 . 0 16. 4 23 . 4 21 . 7 18.0 11.0 16 . 6 16 . 2 15 . 0 16 . 2 18 . 8 16 . 1 20. 3 34 . 7 18. 8 20. 3 15 . 5G 29. .9 21 . 3 12 . 8 17 . 7H 18.0 10. 7 8. 6 8 . 3 16 .0 9 . 9 6 . 5 6.9 6.9 6 . 1 7 . 7 4 . 9 6 . 2 6 . 2 7 . 9 5.0 25.2 13. .4 5. 1 4 . 81 15 . 2 1 1 . 0 11. 7 7 . 7J 18 . 3 13. . 1 13. 5 12 . 6 18 .6 21 . 6 20. 0 10.0 10.8 15. .8 14. 7 1 1 . . 1 20 . 1 14 . 7 12 . 4 18.4 1. Each m a t r i x 1s r e p r e s e n t e d by A, B, , and J . ro APPENDIX 4 Relative contribution of aboveground grass and legume biomass. (a) Pot test 1 grass seeding rate (kg/ha) 1egume seeding rate(kg/ha) 15 30 15 + 30 (average) above- 17.5 35 ground n 1trogen fert i11zer rate (kg/ha) biomass 10 50 100 19 50 100 12 50 100 g.+leg(g/pot) 15 . 8 15. 2 15.9 15.7 15.6 14.2 13.9 14 . 7 17 . 5 grass (%) 0. 0 0. 0 0.0 17.8 53 . 2 56 . 3 23 .0 53 . 7 58 . 9 legume (%) 100. 0 100. 0 100.0 82 . 2 47 . 4 43 . 7 77 .0 46. 3 4 1 . 1 g.+leg(g/pot) 13 . 6 13. 3 16.6 14.7 12.9 19 . 7 11.8 21 . 0 19 . 0 grass (%) 0. 0 0. 0 0.0 10.9 17.8 44 . 7 17.8 42 . 4 62 . 6 1egume (%) 100. .0 100. .0 1O0.0 89. 1 82 . 2 54 .8 82 . 2 57 . 6 37 . 4 g.+leg(g/pot) 14 . 7 14 . 3 16.3 15.2 14.3 17.2 12.9 17 . 9 18 . 3 grass (%) 0 .0 0 .0 0.0 14.5 37 . 1 49.4 20.9 46 . 9 60. 7 legume (%) 100. .0 100. .0 100.0 85.5 62.9 50.0 79 . 1 53 . 1 39 . 3 (b) Pot test 2 1egume seeding rate(kg/ha) 15 30 15 + 30 (average) above ground b i omass g.+leg(g/pot) grass (%) 1egume (%) g.+leg(g/pot) grass (%) 1egume (%) g.+1eg(g/pot) grass (%) 1egume (%) grass seeding rate (kg/ha) 35 17.5 70 nitrogen f e r t i l i z e r rate (kg/ha) 25 50 75 25 50 75 25 50 75 25 50 75 11.0 17.0 19.9 16. 6 18 . 6 21 . 5 16 . 2 20. 7 16 . 2 15. 0 21 . 0 20.7 0.0 0.0 0.0 26. 5 31 . 7 50. 7 33. 3 48 . 3 7 1 . 6 42 . 7 56 . 2 75.4 100.0 100.0 100.0 73 . 5 68. 3 49 . 8 66 . 7 52 . 2 28 . 4 57 . 3 43. 8 24 .6 16.2 16.4 17.2 18 . 8 23 . 4 17 . 8 16 . 1 21 . 7 2 1 . 2 20. 3 18 . 0 19.9 0.0 0.0 0.0 18 . 1 19 . 2 45. 5 25. 5 38 . 2 58 . 5 26 . 6 50. 6 77 . 4 100.0 100.0 100.0 81 . 9 80. 8 54 . 5 75. 2 61 . 8 41 . 5 73 . 4 49 . 4 22 .6 13.6 16.7 18.6 17 . 7 21 . 0 19. 7 16 . 2 21 . 2 18 . 7 17 . 7 19. 5 20.3 0.0 0.0 0.0 22 . 0 24 . 8 48 . 2 29 . 0 42 . 9 64 . 2 33 . 3 53. 8 76.4 100.0 100.0 100.0 78 . 0 75 . O 51 . 8 70. 4 57 . 1 35 . 8 67 . 7 46 . 2 23 . 6 ro Conversion factor from g/pot to g/m! : x 18.87 227 APPENDIX 5 Acetylene reduction data using an open system assay on the reclaimed areas, 1980. F i r s t sampl June 24-25, 1 ng 1980 subplot unit Area 1978 Fert i1 73 83 CtHi Cor-U Second sampling July 31 - Aug.1, 1980 Aug.23, 1980 SRj. HT , DIAM 87 76 82 78 d plot 27, 14 1 68000 891 1 . 310 46040 0 0. 000 T . rep, 5064 0 0. 000 7 380 0 0. 000 29, 12 2 132500 844 0. 637 50470 0 0. 000 T . hyb, 110000 684 0. 622 38990 0 0. 000 40, 16 3 840 0 0. 00 121100 329 0. 272 T . hyb, 9856 0 0. 000 206300 474 0. 230 4 1 , 23 1 26140 248 0. 949 1849 0 0. 000 T . rep, 1 1680 0 0. 000 1 164 . 0 0. 000 1 1 2 12170 148 1 . 216 5948 0 0. 000 T . hyb. 22, 9726 0 0. 000 9902 0 0. 000 22, 1 1 3 161500 1 162 0. 720 67580 0 0. 000 T . hyb, 100500 622 0. 619 42800 0 0. 000 33, 12 1 169400 942 0. 556 175500 837 0. 470 T . hyb, 19140 0 0. 000 126500 447 0. 353 17 2 14290 0 0. 00 20850 0 0. 000 T . rep, 24 , 13290 0 0. 000 52700 0 0. 000 21 , 3 8114 0 0. 000 30370 0 0. 000 T . rep, 7 70520 0 0. 000 76020 0 0. 000 zed plot hyb. 29, 14 1 2202 0 0, ,000 16050 0 0 .000 T . 1 1230 0 0. ,000 39680 0 0 .000 15, 10 2 136400 333 0 . 244 99220 0 0 .000 T . hyb, 66580 137 0 . 206 50050 0 0 .000 25, 12 3 8304 0 0 .000 42550 0 0 .000 T . hyb, 13300 0 0 .000 18320 0 0 .000 23, 10 1 8210 0 0 .000 55180 0 0 .000 T . rep, 49550 0 0 .000 20950 0 0 .000 22 , 14 2 131900 466 0 . 353 54510 0 0 .000 T . rep, 126700 398 0 .314 49100 0 0 .000 24, 21 3 32680 301 0 .921 98160 0 0 .000 T . hyb, 50760 0 0 .000 69180 0 0 .000 15, 9 1 155300 0 0 .00 1782 0 0 .000 T • rep, 132100 0 o .000 10250 0 0 .000 17 2 20940 0 0 .000 8440 0 0 .000 T . hyb. 22 , 26620 0 0 .000 1 1070 0 0 .000 21 3 36900 0 0 .000 9164 0 0 .000 T . hyb, 21 . 13020 0 0 .000 4485 0 0 .ooo Area 1977 55 65 69 58 62 d plot 25, 26 1 1984 0 0. 000 2745 0 0. 000 M. sat, 6135 0 0. 000 4540 0 ' 0. 000 26 2 13130 0 0. 000 3956 0 0. 000 M. sat, 28 , 7862 0 0. 000 2743 0 0. 000 13 3 2374 0 0. 000 2252 0 0. 000 T . rep. 37 . 7630 155 2 . 031 8342 0 0. 000 15 . 43 1 10900 0 0. 000 27990 0 0. 000 M . sat, 85740 390 0. 455 66840 0 0. 000 12 , 2 9034 0 0. 000 1667 0 0. 000 T . rep, 5 3934 0 0. 000 .1299 0 0. 000 48 3 10560 0 0. 000 5310 0 0. 000 M. sat, 25, 46400 0 0. .000 23560 0 0. 000 1 2658 0 0 ooo 6028 0 0. .000 T . rep. 6 , 5 3566 0 0 .000 6836 0 0. .000 49 2 24 190 0 0 .000 45120 0 0 .000 M . sat, 12 , 7214 0 0 .000 5523 0 0 .000 43 3 816 0 0 .000 92000 0 0 .000 M . sat, 20, 42100 0 0 .000 118500 0 0 .000 zed plot 47 , 53 1 3282 0 0 .000 1902 0 0 .000 M . sat, 1568 0 0 .000 920 0 0 .000 15, 2 8326 0 0 .000 10600 0 0 .000 T . rep. 4 22000 O 0 .000 31880 0 0 .000 30 3 354 0 0 .000 1373 0 0 .000 M . sat, 33, 2065 0 0 .000 1701 0 0 .000 32 1 18350 0 0 .000 43970 0 0 .000 M . sat, 14 , 36660 0 0 .000 35570 228 0 .641 APPENDIX 5 CONTINUED 228 F i r s t sampl1ng dune 2 4 - 2 5 , 1980 s u b p l o t 68 A rea 1975 39 47 49 un i t % 2' " 1 0 1 6 0 0 138 0. 136 48640 0 0. 000 3 33210 0 0. 000 70480 335 O. 745 1 2047 0 0. 000 2185 0 0. 000 2 13890 0 0, .000 2742 0 0 .000 3 3841 0 0 .000 5923 0 0 .000 Second s a m p l i n g d u l y 31 - Aug .1 . 1980 C ?H2 C ?Ha 86640 616 80340 338 32040 74080 2892 3822 26230 19290 7602 16130 0 489 0 0 0 0 0 0 % .711 .421 .000 .660 .000 .000 .000 .000 .000 .000 p l o t 42 44 54 A r e a 1974 F e r t i 1 i zed p l o t 19 27 110200 531500 25560 23980 190400 27129 162400 101000 515300 547500 469500 463900 993200 614900 195500 359900 87660 134400 459 3621 1067 1222 432 0 178 219 180 313 802 1083 3716 2016 1359 1466 641 1452 0. 0. 4 . 5 . 0 0 0 0 0 0 0 0 0 0 0 0 0 1 417 687 174 096 227 000 1 10 217 035 057 171 233 374 328 695 407 731 080 171600 323600 103500 77480 49160 17450 171800 1 14600 204000 204500 2889O0 332000 202300 201300 177100 243900 43330 61800 284 928 0 0 256 0 0 0 0 0 216 0 609 572 0 0 0 301 0. 166 0. 287 0 .000 0 .000 0. 52 1 0.000 0 .000 0 .000 0 .000 0 .000 0.075 .000 . 301 . 284 .000 .000 .000 .487 0. 0. 0. 0. 0. 0. 0. Aug .23 , 1980 tLL. DIAM M . s a t , 29, 27 M . s a t , 10, 23 M . s a t , 36, 49 M . s a t . 17, 39 M . sa t . 18, 38 1 53320 0 0. 000 40200 0 0. 000 M . s a t . 3, 38 9370 0 0. 000 8874 0 0. 000 2 30520 0 0. 000 26600 0 0. 000 M . s a t . 1 , 29 6880 0 0. 000 8232 0 0. 000 3 1 1540 0 0. 000 9718 0 0. 000 No l e g . 0, 0 12880 0 0. 000 6616 0 0. 000 3. 21 1 30910 667 2 . 158 23560 0 0. 000 M . sa t , 32460 0 0. 000 1 1760 0 0. 000 2 69460 520 0. 749 27100 0 0. 000 M . sa t , 5, 30 43330 1 137 2 . 624 25860 0 0. 000 3 24420 351 1 . 437 25820 0 0. 000 M . sa t , 15, 33 29960 0 0. 000 22940 0 0. 000 1 15720 0 0. 000 10080 0 0. 000 No l e g . 0, 0 12510 0 0. 000 14100 0 0. 000 2 93800 0 0. 000 42290 0 0. 000 No l e g . 0, 0 349100 0 0. 000 105400 0 0. 000 3 23120 0 0. 000 24950 0 0. 000 M . sa t , 13, 64 60490 0 0. ooo 28680 0 0. 000 i z e d p l o t 10. 34 1 23180 0 0. 000 47610 0 0. .000 M . sa t . 198800 0 0, ,000 126200 0 0. .000 T . h y b . 2 46030 0 0 .000 108100 0 0 .000 7 , 4 73360 0 0 .000 39540 0 0 .000 3 34470 0 0 .000 25500 0 0 .000 No l e g . 0. 0 41970 0 0 .000 35260 0 0 .000 0, 0 1 30560 0 0 .000 16980 0 0 .000 No l e g . 28610 0 0 .000 9636 0 0 .000 2 0 0 0 .000 8161 0 0 .ooo No l e g . 0, 0 0 O 0 .000 1 180 0 0 .000 7, 10 3 1114 0 0 .ooo 483 0 0 .000 T . h y b , 939 0 0 .000 2203 0 0 .ooo , 0, 0 1 373600 0 0 .000 69040 0 0 .000 No l e g , 107900 0 o .000 35160 0 0 .000 4, 8 2 110100 0 0 .ooo 46280 0 o .000 T . h y b , 64940 0 0 .000 30840 0 0 .000 8, 8 3 48710 0 0 .000 71550 0 0 .000 T . r e p . 110100 0 0 .000 87620 0 0 .ooo M.sa t , 2, 35 M. sa t , 3, 27 M . sa t , 14, 35 T . h y b . 12, 12 T . h y b , 13. 12 T . h y b , 16, 9 M . sa t , 12, 42 T . h y b , 18, 11 M . sa t , 22, 43 APPENDIX 5 CONTINUED 229 F 1 r s t sampl1ng June 2 4 - 2 5 , 1980 s u b p l o t un i t C i H j £zd4 °A U n f e r t i1 i z e d p l o t 1 1 1 79320 847 1 . 068 76520 756 0. 988 2 7382 0 0. .000 195500 2063 1 . 055 3 41030 0 0. .000 4188 0 0. .000 21 1 217900 690 0. 317 274500 1037 0. . 378 2 151300 1 159 0. . 766 45120 501 1 , 1 10 3 211800 536 0. . 253 168900 826 0 . 489 34 1 283700 807 0 . 284 116700 966 0 . 828 2 23210 0 0 .000 9304 0 0 .000 3 369000 1226 0 . 332 767800 2324 0 . 303 Second s a m p l i n g J u l y 31 - Aug .1 . 1980 Aug .23 , 1980  C ? H a C ? H d °£ S £ . ML. D l f l M 139500 683 0. .490 M. s a t , 10. 25 14 1100 583 0. 415 81520 0 0. .000 M. . s a t , 11 . 32 190900 395 0. 207 64960 0 0. .000 M. , s a t , 11 . 27 9632 0 0. ,000 136400 0 0. .000 T . hyb, 21 , 13 117000 0 0. .000 123300 1057 0 .857 M. . s a t . 17 , 22 60080 332 0. . 536 87240 0 0 .000 T . hyb, 14 , 6 66060 0 0 .000 159200 434 0 . 266 M . s a t , 18 , 29 54640 0 0 .000 111800 672 0 .601 M . s a t , 22 , 55 46840 0 0 .000 112900 0 0 .000 T .hyb. 26, 13 188200 0 0 .000 c. APPENDIX 6 A c e t y l e n e r e d u c t i o n d a t a u s i n g open and c l o s e d a s s a y s on the r e c l a i m e d a r e a s , 1980. Samp l ing d a t e Samp l ing d a t e June 24 - 2 5 , 1980 J u l y 31 - Aug .1 , 1980 a s s a y sp . , abgd sp 1..abgd t y p e s C 2 H 2 C 2 H 4 % b iomas s ( g ) C 0 H 0 C 2 H 4 °A b i omass(g) A rea 1978 open 352 10 135 0. 383 T . h y b , 7 . 5 9446 0 0. 000 T . h y b , 6 . 8 10750 0 0. 000 c 1 o s e d 42480000 17620 0. 041 39530000 7610 0. 019 4390000 . 7852 0. 018 open 6416 0 0. 000 T . r e p , 3 . .0 1 1010 0 0. 000 T . r e p . 5 . 0 35530 0 0. 000 c l o s e d 42330000 10040 0. .024 31290000 1942 0. 006 35200000 207 3 0. 006 open 5583 0 0. .000 T . r e p , 9 . 1 28940 0 0. 000 T . hyb ,5 .4 622 1 0 0. 000 c 1 o s e d 47030000 629 0. .013 34210000 2243 0. 007 38970000 2473 0. .006 open 99880 637 0 638 T .hyb,6 .6 7730 0 0. 000 T . r e p , 5 . 9 57770 0 0. 000 c 1 o s e d 41940000 1 1000 0 .026 34300000 2405 0 .007 38270000 2550 0. .007 open 22720 147 O . 647 T . r e p , 65280 O 0. .000 T . hyb .13 .3 T .hyb,5 . 5 89960 0 0 .000 c l o s e d 36540000 1 1 190 0 .031 19450000 2575 0 .013 26050000 3263 0 .013 open 75980 387 0 . 501 T .hyb,8 . 7 25380 0 0 .000 T . h yb ,22 .5 9538 0 0 .000 c l o s e d 37710000 1 1 160 0 .030 14980000 16800 0 .112 12730000 13690 0 . 108 A rea 1977 open 1 1520 0 0 .000 M . s a t , 3 . 7 3081 0 0 .000 M. s a t , 4 . 9 4569 0 0 .000 c 1 o s e d 46810000 2833 0 .006 44410000 2532 0 .006 41400000 2560 0 .006 APPENDIX 6 CONTINUED 230 a s s a v t y p e s open c l o s e d open c 1 o s e d open c l o s e d open c l o s e d open c l osed Area 1 9 7 5 open c l o s e d open c 1 osed open c 1 osed open c l o s e d open c l o s e d open c 1 o s e d Area 1974 open c 1 o s e d open c l o s e d open c 1 o s e d open c 1 o s e d open c 1 o s e d open c l o s e d Sampling date June 2 4 - 2 5 . 1 9 8 0 Sampl J u l y 31 -1 ng da Aug. 1 . te 1980 sp .abgd  C9H0 C 9 H 4 % biomass(g) 8 8 4 6 0 0 . 0 0 0 M . s a t , 7 . 9 4 2 0 6 0 0 0 0 2 4 2 6 0 . 0 0 6 6 9 1 0 0 1098 1 . 5 8 9 T . h y b , 5 . 0 4 6 5 6 0 0 0 0 1 2 9 6 0 0 . 0 2 8 5 0 1 7 0 1897 3 . 7 8 1 T.hyb.1 6 . 3 3 9 1 5 0 0 0 0 74 10 4 0 6 1 0 0 0 0 4 5 8 8 0 3 4 6 5 0 0 0 0 4 1 3 3 0 . 0 1 1 0 0 . 0 0 0 3361 0 . 0 0 8 0 0 . 0 0 0 2 4 6 9 0 . 0 0 7 1 0 3 2 0 0 8 1 4 2 3 1 7 0 0 0 0 1 5 3 9 1 0 9 4 0 0 O 3 3 3 3 0 0 0 0 5 0 1 4 2 3 9 5 0 1 7 1 7 0 0 0 0 2 5 7 4 3 7 6 1 0 0 0 0 3 2 3 1 0 1 9 7 9 0 0 0 0 0 1281 0 0 . 0 0 0 2 5 5 7 0 . 0 0 7 0 0 . 0 0 0 1655 0 . 0 0 8 0 0 . 0 0 0 M . s a t , 1 6 . 8 T.hyb,5.1 M . s a t , 3 . 2 T . r e p , 1 . 0 M.sat , 1 8 . 5 M. s a t . 1 . 3 T.hyb,1 . 7 T.hyb,3 . 9 2 5 2 3 0 0 0 0 1 4 8 7 0 0 . 0 5 9 1 1 2 3 0 0 0 . 0 0 0 M . s a t , 4 . 8 4 5 0 4 0 0 0 0 4 4 2 3 0 . 0 1 0 6 2 5 6 0 4 5 9 0 . 7 3 4 T.hyb,7 . 2 2 9 5 3 0 0 0 0 7 1550 0 . 2 4 2 6 2 8 4 0 0 7 4 5 2 1 . 1 8 6 M.sat,1 5 . 1 4 0 0 0 0 0 0 0 4 6 9 3 0 . 0 1 2 9 3 7 4 0 0 . 0 0 0 T.hyb.1 5 . 6 3 6 1 5 0 0 0 0 1 4 0 6 0 0 0 . 3 8 9 1 2 4 3 0 0 0 1272 0 . 1 0 2 T . h y b , 1 . 4 3 5 5 3 0 0 0 0 1 9 0 6 0 0 . 0 5 4 2 3 1 4 0 0 0 . 0 0 0 M . s a t , 3 . 8 3 6 3 0 0 0 0 0 3 7 9 7 0 . 0 1 0 C2H2 C2H4 % 3761 177 4 . 7 0 6 1 0 5 0 0 3 1 8 3 . 0 2 9 1 8 8 1 0 0 0 0 2 2 6 9 0 . 0 1 2 1 7 5 2 0 0 0 0 2 2 3 8 0 . 0 1 3 9 2 7 0 0 0 . 0 0 0 2 1 3 0 0 0 0 . 0 0 0 2 7 0 4 0 0 0 0 1582 0 . 0 0 6 2 6 4 2 0 0 0 0 1646 0 . 0 6 2 9 1 8 8 0 0 . 0 0 0 1 4 1 3 0 74 0 . 5 2 4 3 5 9 9 0 0 0 0 6 2 5 8 0 . 0 1 7 3 3 3 7 0 0 0 0 6 1 4 5 0 . 0 1 8 3 2 1 4 0 0 . 0 0 0 2 1 3 5 0 0 . 0 0 0 4 2 4 3 0 0 0 0 0 0 . 0 0 0 4 4 8 7 0 O 0 0 0 0 . 0 0 0 1 4 6 4 0 0 0 . 0 0 0 2 4 2 5 0 0 0 . 0 0 0 2 6 6 3 0 0 0 0 2 7 0 5 0 . 0 1 0 2 8 5 6 0 0 0 0 2 7 0 7 0 . 0 0 9 2 0 3 2 0 0 0 . 0 0 0 1 3 4 4 0 0 0 . 0 0 0 4 3 2 2 0 0 0 0 2 3 6 3 0 . 0 0 5 3 7 3 5 0 0 0 0 2 2 2 7 0 . 0 0 6 1 0 8 0 0 0 0 . 0 0 0 7 4 8 6 0 0 . 0 0 0 5 6 6 4 0 0 0 0 3 0 8 4 0 . 0 0 5 4 6 2 3 0 0 0 0 2691 0 . 0 0 6 2 1 5 5 0 0 0 . 0 0 0 2 3 2 1 0 0 0 . 0 0 0 4 5 1 3 0 0 0 0 2 4 6 8 0 . 0 0 5 3 8 4 3 0 0 0 0 2 2 5 0 0 . 0 0 6 1 1 5 5 0 0 0 . 0 0 0 9 7 9 2 0 0 . 0 0 0 3 7 1 4 0 0 0 0 431 1 0 . 0 1 2 3 8 9 5 0 0 0 0 4 6 3 6 0 . 0 1 2 9 0 7 4 0 0 . 0 0 0 3 8 3 2 0 0 0 . 0 0 0 4 3 1 0 0 0 0 0 2 4 5 0 0 . 0 0 6 3 9 9 8 0 0 0 0 2 4 4 7 0 . 0 0 6 5 0 5 1 0 0 0 . 0 0 0 5 1 3 3 0 0 0 . 0 0 0 374 1 0 0 0 0 6 0 7 9 0 . 0 1 6 3 9 4 5 0 0 0 0 6 7 8 0 0 . 0 1 7 2 6 7 0 0 0 3 3 0 5 1 . 238 1 8 5 4 0 0 2 1 9 5 1 . 184 3 8 7 2 0 0 0 0 3 4 5 1 0 . 0 0 9 4 0 8 1 0 0 0 0 3 3 6 7 0 . 0 0 8 2 8 9 8 0 0 0 . 0 0 0 3 8 1 7 0 0 0 . 0 0 0 4 2 8 2 0 0 0 0 2 5 3 3 0 . 0 0 6 4 3 5 3 0 0 0 0 2 4 2 4 0 . 0 0 6 3 4 1 8 0 0 0 . 0 0 0 3 1 3 0 0 0 0 . 0 0 0 4 0 4 1 0 0 0 0 2761 0 . 0 0 7 3 7 3 3 0 0 0 0 2 5 3 6 0 . 0 0 7 1 4 7 6 0 0 8 3 8 0 . 5 6 8 8 8 2 8 0 5 7 7 0 . 6 5 4 4 4 1 2 0 0 0 0 2 5 0 3 0 . 0 0 6 394 2 0 0 0 0 2 3 6 8 0 . 0 0 6 4 0 7 5 0 0 0 . 0 0 0 41 140 0 0 . 0 0 0 3 3 4 3 0 0 0 0 2 1 3 0 0 . 0 0 6 3 3 4 9 0 0 0 0 2301 0 . 0 0 7 5 6 4 3 0 0 0 . 0 0 0 9 7 4 4 0 0 0 . 0 0 0 264 3 0 0 0 0 1626 0 . 0 0 6 2 7 1 3 0 0 0 0 1699 0 . 0 0 6 sp.,abgd  b i omass(g) M . s a t . 3 5 . 4 M . s a t . 1 4 . 5 T . r e p . 9 . 1 T . r e p . 4 . 4 T.hyb.2 0 . 5 231 A P P E N D I X 7 A c e t y l e n e r e d u c t i o n d a t a u s i n g o p e n a n d c l o s e d a s s a y s i n t h e s u b a l p i n e f o r e s t , 1 9 8 0 . Samp 1 i n g d a t e S a m p l 1 n g d a t e a s s a y t y p e o p e n o p e n o p e n o p e n c l o s e d o p e n c 1 o s e d d u n e C H 1 9 6 7 0 0 1 6 3 0 0 0 4 7 9 5 0 5 1 9 4 0 2 4 0 9 0 3 7 5 9 0 4 0 6 3 0 2 4 - 2 5 ~C H 0 0 0 0 0 0 1 9 8 0 % 0 . 0 0 0 0 . 0 0 0 0 . 0 0 0 0 . 0 0 0 0 . 0 0 0 0 . 0 0 0 3 2 2 9 0 0 0 0 2 6 3 4 0 . 0 0 8 V . s c o p . s o i 1 d u l y 31 - A u g . JL. 1980 C H C H % sp_ 1 4 7 7 0 0 0 0 . 0 0 0 V . s c o p a r i urn 1 3 4 8 0 0 0 0 . 0 0 0 5 6 0 2 0 0 0 0 . 0 0 0 y . m e m b r a n a c e u m 8 7 7 8 0 0 0 . 0 0 0 1 0 5 4 0 0 0 0 . 0 0 0 v . s c o p a r iurn 6 2 7 5 0 0 0 . 0 0 0 1 4 4 3 0 0 0 . . 0 0 0 v . s c o p a r i urn 2 5 5 9 0 0 0 . 0 0 0 2 9 3 5 0 0 0 0 1838 0 . 0 0 6 3 6 9 5 0 0 0 0 2 1 5 4 0 . 0 0 6 3 4 3 1 0 0 0 . 0 0 0 y . m e m b r a n a c e u m 3 9 0 2 0 0 . 0 0 0 3 0 9 7 0 0 0 0 2 1 4 0 0 . 0 0 7 3 2 6 0 0 0 0 0 2 1 3 6 0 . 0 0 7 

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