British Columbia Mine Reclamation Symposia

Hat Creek reclamation studies' results of the first year program Hathorn, F. G.; Docksteader, R. L.; McQueen, Donald K. 1979

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Proceedings of the 3rd Annual British Columbia Mine Reclamation Symposium in Vernon, BC, 1979. The Technical and Research Committee on Reclamation 239 HAT CREEK RECLAMATION STUDIES' RESULTS OF THE FIRST YEAR PROGRAM Paper Prepared Jointly by: F.G. Hathorn, B.C. Hydro and Power Authority and R.L. Docksteader and D.K. McQueen Acres Consulting Services Limited Proceedings of the 3rd Annual British Columbia Mine Reclamation Symposium in Vernon, BC, 1979. The Technical and Research Committee on Reclamation 241 HAT CREEK RECLAMATION STUDIES  RESULTS OF THE FIRST YEAR PROGRAM SUMMARY Test plots to evaluate the revegetation of waste materials expected from the proposed Hat Creek coal mine and powerplant have been established in the Hat Creek Valley.  These plots were seeded with three different seed mixes of four species each during the fall of 1977.  At the same time two additional tests were undertaken to evaluate the revegetation of typical waste embankments at slopes of 22, 26 and 30. During the late summer of 1978 the vegetation on these test plots was counted and harvested to determine the progress of the experiments in the first year following seeding.  This paper describes the sampling program and presents and discusses the results in the context of short-term revegetation goals, namely the establishment of vegetation for the prevention of wind and waterborne erosion. The principal conclusions are as follows: - Revegetation of surficial materials such as colluvium, gravel and till was readily achieved.  The sodic materials, gritstone and bentonitic clay proved more difficult to revegetate.  The carbon-aceous wastes would require a cover of suitable material in order to be revegetated in the first year.  Fly ash, because of its fine and uniform texture would likewise benefit from a thin surface cover if vegetation for erosion control is to be established in the short term.  - The effect of topsoil was to increase emergence success and biomass on carbonaceous soils, gritstone and bentonitic clay, while on colluvium and gravel a decrease was observed.  It is suggested that the retention of surficial materials such asProceedings of the 3rd Annual British Columbia Mine Reclamation Symposium in Vernon, BC, 1979. The Technical and Research Committee on Reclamation 242 colluvium and gravel with topsoll for the future surfacing of waste dumps would be beneficial. - Several vegetation species suitable for short-term revegetation practices have been identified. Of the grasses, Fall Ryegrass, Streambank and Slender Wheatgrasses performed particularly well while Sainfoin was the most successful legume. - Revegetation of 15 metre high embankments with up to 30° slopes constructed of till or gravel was readily achieved. Erosion in the first year was not apparent. INTRODUCTION Over the past several years B.C. Hydro has been examining the possibilities of developing the Hat Creek coal deposits to fuel a coal-fired powerplant. As part of the environmental planning for this project, a program was undertaken to examine the reclamation potential of the various waste materials expected from the proposed open pit mine, and to determine suitable vegetation species for this purpose.  Details of the rationale for this program, preparation of test sites and species used, have been described previously (1). In the summer of 1977, following the extraction of a bulk sample of coal, seven different waste materials, typical of those expected from a full-scale mine, were selected for reclamation testing.  In addition, a bulk sample of fly-ash was returned from a large-scale combustion test.  These eight materials were arranged in field test plots located in an open area near Aleece Lake at Hat Creek.  Half of each plot was capped with a thin layer of topsoil.  Three different saed mixes of four species each were sown on each plot in the fall of 1977. Additional testing of revegetation practices was undertaken at two other locations at Hat Creek, where typical waste retaining embankments were constructed and reclamation at slopes of 22°, 26° and 30° was examined. Proceedings of the 3rd Annual British Columbia Mine Reclamation Symposium in Vernon, BC, 1979. The Technical and Research Committee on Reclamation 243 In July and August of 1978, a counting and harvesting program was undertaken to determine the progress of these experiments.  This paper describes the methods of sampling and analysis and discusses the results obtained within the context of short-term revegetation goals. SAMPLING PROGRAM Aleece Lake The waste material test plots at Aleece Lake measured approximately 15 metres square by 1 metre deep.  Half of each plot was covered with a layer of topsoil about 5 centimetres deep.  Three seed mixes (Table 1) were used, such that each mix was applied to equal areas of both the topsoiled and non-topsoiled portions of each plot.  Two seed mixes only, were used on the fly-ash plot since it was smaller and could not accom-modate all three.  Thus there were 46 vegetation populations at the Aleece Lake test area made up of seven materials with two surface treat-ments and three seed mixes, plus the fly-ash plot with two surface treatments and two seed mixes.  Each material plot had six populations except the smaller fly-ash plot, which had four. Sample Locations. Each population was sampled at eighteen locations, selected as follows: Three transects, 1 metre apart, were marked lengthwise across each popu-lation (Figure 1).  Twenty equidistant points, 31.7 centimetres apart, were set out along each transect, an allowance being made for edge effects.  Thus sixty potential sampling points were located on each population.  Of these, 18 were randomly selected using the method de-scribed by Zar (2). A wooden quadrat 31.7 centimetres x 31.7 centimetres (0.1 square metres) within which all samplings were carried out, was centred on each Proceedings of the 3rd Annual British Columbia Mine Reclamation Symposium in Vernon, BC, 1979. The Technical and Research Committee on Reclamation  244 TABLE 1 SEED MIXES USED AT ALEECE LAKE  GRASS OR LEGUME (VARIETY) % BY NUMBER OF SEEDS SEED MIX I CRESTED WHEATGRASS (NORDAN) 41 CANADA BLUEGRASS 29 ALFALFA (DRYLANDER) 26  FALL RYEGRASS 4 APPLICATION RATE     5 KG/HA SEED MIX II RUSSIAN WILD RYEGRASS 39 SLENDER WHEATGRASS 18 SAINFOIN (MELROSE) 25 SWEET CLOVER 18 APPLICATION RATE     108 KG/HA SEED MIX III SMOOTH BROMEGRASS (MANCHAR) 19  STREAMBRANK WHEATGRASS 39  CANADA BLUEGRASS   (RUBENS) 14 DOUBLE   CUT  RED   CLOVER 28 . APPLICATION RATE 48  KG/HA Proceedings of the 3rd Annual British Columbia Mine Reclamation Symposium in Vernon, BC, 1979. The Technical and Research Committee on Reclamation 245  Proceedings of the 3rd Annual British Columbia Mine Reclamation Symposium in Vernon, BC, 1979. The Technical and Research Committee on Reclamation 246 of the selected sampling points.  The area covered in sampling each population was therefore approximately five percent of the total area of that population. Sampling Method.  Data recorded at each quadrat included:  the total number of each vegetation species present, their approximate height and the percent ground cover.  A general note on the condition of the vege-tation was also made.  Vegetation was harvested for biomass production analysis.  Samplers wearing plastic gloves clipped vegetation at ground level (i.e. only the aerial portion was collected) using acid-washed (10% HNO) stainless steel scissors.  Each of the agronomic species collected was bagged separately in bleached white paper bags. Sampling was carried out when the plants were relatively dry.  Native species (invaders) were identified and collectively bagged in one bag per population. Biomass production was determined by drying and weighing the bagged samples at B.C. Hydro Research and Development Laboratories.  Drying was carried out in a forced circulation oven at 100 C for 24 hours. Slope Test Plots Test slopes at Houth Meadows and Medicine Creek were approximately 15 metres wide and varied in length depending on the slope angle.  Half the width of each plot at Houth Meadows was covered with approximately 5 centimetres of topsoil.  The upper and lower halves of each test plot were sampled, thus 12 populations existed at Houth Meadows and 6 at Medicine Creek. Two transect lines were run across each slope, one was a quarter of the slope length from the top, and the other a quarter of the slope length from the bottom (see Figure 2).  Five sampling points were arbitrarily located at approximately equal distances along each transect line, care being exercised to avoid areas previously disturbed. Proceedings of the 3rd Annual British Columbia Mine Reclamation Symposium in Vernon, BC, 1979. The Technical and Research Committee on Reclamation 247  Proceedings of the 3rd Annual British Columbia Mine Reclamation Symposium in Vernon, BC, 1979. The Technical and Research Committee on Reclamation 248 Sampling was carried out as indicated previously for the Aleece Lake plots except at Medicine Creek, where the vegetation was not retained for biomass determination.  RESULTS FROM ALEECE LAKE PLOTS Soil characteristics of the eight waste materials at Aleece Lake exhibited a wide variation.  The success of the revegetation trials is discussed in the light of these characteristics.  The performance of the twelve vegetation species tested is discussed separately. Soils as Growth Media  Based on their chemical and physical properties (Table 2) the eight waste materials may conveniently be grouped into four categories:  carbonaceous, sodic, alkaline and fly-ash materials.  Results of biomass and plants produced per unit area are given in Tables 3 and 4.  Carbonaceous Materials.  Both the coaly waste and carbonaceous shale exhibited low pH and a moderately high soluble boron concentration. Their dark colour would be expected to cause high surface temperatures and surface drying.  In addition, the shale is somewhat water repellent and moisture does not easily penetrate the surface. In terms of biomass produced and seedling emergence, neither material proved to be a successful growth medium (Tables 3 and 4).  The chemical characteristics of the materials appear to be less deterrent to plant growth than do their physical properties, particularly their dark colour and the hydrophobic nature of the shale.  The poor plant emergence on these materials may be attributed to unsuitably low soil moisture con-ditions during the period of potential germination.  Average biomass production per plant was low compared with that in other soils (Table 5). Plants rarely progressed beyond the seedling stage. Proceedings of the 3rd Annual British Columbia Mine Reclamation Symposium in Vernon, BC, 1979. The Technical and Research Committee on Reclamation 249  Proceedings of the 3rd Annual British Columbia Mine Reclamation Symposium in Vernon, BC, 1979. The Technical and Research Committee on Reclamation 250  Proceedings of the 3rd Annual British Columbia Mine Reclamation Symposium in Vernon, BC, 1979. The Technical and Research Committee on Reclamation 251  Proceedings of the 3rd Annual British Columbia Mine Reclamation Symposium in Vernon, BC, 1979. The Technical and Research Committee on Reclamation 252  Proceedings of the 3rd Annual British Columbia Mine Reclamation Symposium in Vernon, BC, 1979. The Technical and Research Committee on Reclamation 253 The addition of topsoil markedly increased the emergence success and total biomass production.  Biomass per plant increased sharply for the coal waste, but remained essentially unchanged on the shale. In general terms, plants appeared stunted (Table 5) and suffered from chlorosis. Most of the grasses showed only limited spike development while the legumes were devoid of any signs of maturity. Sodic Materials.  The materials in this category, bentonitic clay and gritstone, exhibited high concentrations of sodium.  Field observations indicated that the soil structure was poor under extreme conditions of moisture, that is gel-like and swollen when saturated, and severely shrunken and cracked when dry. Results (Tables 3 and 4) indicated that those soils were moderately successful in terms of seedling emergence but biomass production was relatively low.  This may have been due to the high concentration of sodium which contributed to poor soil structure and nutrient imbalances. The effect of topsoil was to increase substantially the emergence success and to double the individual plant size. Plants on the bentonitic clay and gritstone were stunted (Table 5) and generally exhibited leaf tip chlorosis.  Grasses showed up to 20% inflorescence formation  except for Fall Ryegrass which exhibited a greater, almost 100%, degree of maturity.  None of the legumes showed flower development. Alkaline Materials.   These materials, colluvium, baked clay and glacial gravels, exhibited moderately good soil characteristics.  There did not appear to be any potentially adverse constituents to inhibit plant growth although, as with most other materials tested, they were low in nitrogen.  Physically they were relatively coarse.  Their water holding Proceedings of the 3rd Annual British Columbia Mine Reclamation Symposium in Vernon, BC, 1979. The Technical and Research Committee on Reclamation 254 capacity would therefore be low and thus they were expected to be dry during periods of low rainfall. Biomass production and seedling emergence confirmed the good soil cha-racteristics of these materials as growth media (Tables 3 and 4).  Al-though quantitative data showed less overall vegetative growth on baked clay and glacial gravel as compared to the colluvium plot, qualitatively they appeared similar (Table 5).  Growth in all three cases was most abundant.  Plants appeared healthy with little sign of chlorosis. The effect of topsoil on these materials was inconsistent.  The glacial gravels and colluvium exhibited similar results in that overall emergence success and biomass production decreased with topsoil.  The baked clay did not show a consistent trend; whilst a greater emergence success yielded more plants per square metre with topsoil, they were smaller in size resulting in a decrease in overall biomass production. Fly-Ash.  The fly-ash is discussed separately because it is anthropogenic. It exhibits a high pH and a high soluble boron concentration which might be sufficient to be detrimental to plant growth.  This material was a uniform silty loam which makes it susceptible to wind erosion in the absence of a vegetation cover.  The plant emergence data suggests that the fly-ash provided a good en-vironment for seed germination.  However, total biomass production was low and individual plants were stunted (Tables 3 and 4).  It is suggested that metabolic interference due to boron may have occurred.  Plants appeared dried out and exhibited chlorotic conditions. The topsoil treatment had a positive effect on average plant size. Biomass production was approximately doubled yet the number of plants that emerged was approximately the same. Proceedings of the 3rd Annual British Columbia Mine Reclamation Symposium in Vernon, BC, 1979. The Technical and Research Committee on Reclamation 255 Effect of Topsoil The practice of stripping and stockpiling topsoil or other suitable surface material during initial mining for subsequent surfacing of waste materials is being widely recommended as a method of improving the success of revegetation programs.  As a preliminary examination of this practice, half of each plot at Aleece Lake was covered with a 5 centimetre layer of topsoil.  Results of plant emergence and biomass production are given in Tables 3 and 4 for both topsoiled and non-topsoiled portions of the plots. Considering first the effect of topsoil on plant emergence:  On the least successful materials, the carbonaceous soils, the presence of top-soil dramatically increased the number of plants per square metre.  A smaller but nevertheless substantial increase also occurred with the gritstone and bentonitic clay materials, whereas, there was a marked decrease in overall emergence success on the colluvium and glacial gravels.  The baked clay and fly-ash showed variable responses among the seed mixes with the former showing a net increase and the latter a slight overall decrease. Emergence on the topsoiled portions of the plots showed an average value of 363 plants per square metre over all materials, with a range of values from 317 to 410 plants per square metre.  This consistency would be expected for vegetation germinating in the same medium.  The micro-enviro-ment presented to the seeds was clearly improved in the topsoil as compared with the carbonaceous materials, bentonitic clay and gritstone, where such adverse factors as soil pH, and soil structure as it affects the movement of gases and moisture, and salinity existed. Surprisingly, the glacial gravel and colluvium provided a more suitable micro-environment than the topsoil.  It would appear that the separate stripping and stockpiling of only topsoil horizons at Hat Creek need to Proceedings of the 3rd Annual British Columbia Mine Reclamation Symposium in Vernon, BC, 1979. The Technical and Research Committee on Reclamation 256 be evaluated further.  It may be beneficial to include suitable subsur-face materials such as gravels and colluvium, if soil for future sur-facing of dumps is to be retained. Biomass results and emergence data showed similar trends (Tables 3 and 5).  However, although major improvements were noted on the coal waste, carbonaceous shale, bentonitic clay and gritstone, the yields were substantially less than those obtained on other materials at Aleece Lake.  The reasons for these effects cannot be defined precisely with data presently available.  Nevertheless, it seems clear that the plant seedling, as its root system penetrated the thin topsoil layer, encoun-tered the poorer material where further root development was inhibited. Thus the continued uptake of nutrients and consequently, plant growth, was retarded.  The net result was that plants were stunted with a higher incidence of chlorosis than those grown on the better materials (Table 5).  It did not appear that acute toxic conditions, e.g. due to boron, existed, since vegetation continued to develop on the topsoil-treated side throughout the first year of growth. Invader Species.  Invader (weed) species were identified, counted and their biomass determined from all plots at Aleece Lake.  These data are shown in Table 6. As may be seen, there were substantially more invaders present on the topsoiled portions of the plots than on the non-topsoiled areas.  From this it may be inferred that the seeds of these species were transported to the test site in the topsoil. Comparisons between the total numbers of weeds produced and the numbers of agronomic species present would indicate that, for all but the fly-ash and gritstone plots, the invaders did not present a threat.  On the gritstone and particularly the fly-ash where invaders amounted to approximately 36% of the total plants produced, competition probably occurred to a limited extent. Proceedings of the 3rd Annual British Columbia Mine Reclamation Symposium in Vernon, BC, 1979. The Technical and Research Committee on Reclamation 257  Proceedings of the 3rd Annual British Columbia Mine Reclamation Symposium in Vernon, BC, 1979. The Technical and Research Committee on Reclamation 258 The invader species were generally quite large compared to the agrono-mics planted.  The invaders exhibited rapid early growth and matured earlier than the agronomics.  This behaviour is presumably indicative of their adaption to the climatic conditions at Hat Creek. The most prevalent weed species were Flixweed (Descurainia sophia), Prostrate Knotweed (Polygonum aviculare), Downy Bromegrass (Bromus tectorum) and Blueburr (Lappula echinata).  These accounted for 70% of the weeds present.  None of the invaders were toxic to either wildlife or other vegetation.  However, Foxtail Barley when young does exhibit very sharp spikes which have been known to lacerate the mouths of cattle.  In total this species represented only 1% of the weed population. Individual Vegetation Species Twelve plant species were tested at Aleece Lake; eight grasses and four legumes.  These species were originally selected on the basis of their suit-ability for use on the soil materials available and their adaption to the climate of the Hat Creek Valley.  Individual species were examined, counted and their biomass production determined.  These are reported in Tables 7 and 8.  Results are discussed for each species and collectively for the three seed mixes. Seed Mix I.  This mixture comprised Crested Wheatgrass, Fall Ryegrass, Canada Bluegrass, and Alfalfa.  Each species is discussed below. Crested Wheatgrass showed an overall emergence success of 17% on un-treated soils and ranked fifth among the eight grasses.  Its performance on the carbonaceous materials was relatively good.  Although it showed consistent results on the other materials its performance was not par-ticularly noteworthy.  The plants showed varied spike development de-pending on the soil material.  Little or no development was evident on Proceedings of the 3rd Annual British Columbia Mine Reclamation Symposium in Vernon, BC, 1979. The Technical and Research Committee on Reclamation 259  Proceedings of the 3rd Annual British Columbia Mine Reclamation Symposium in Vernon, BC, 1979. The Technical and Research Committee on Reclamation 260  Proceedings of the 3rd Annual British Columbia Mine Reclamation Symposium in Vernon, BC, 1979. The Technical and Research Committee on Reclamation 261 the untreated carbonaceous and bentonitic clay materials; maximum in-florescence (20 to 25%) was noted on the glacial gravels.  Toward the edge of the plots the Crested Wheatgrass appeared to be more fully de-veloped due to less competition from Fall Ryegrass. Fall Ryegrass is a vigorous, tall-growing annual which developed rapidly. In overall emergence success it was superior to all other species.  The presence of Fall Ryegrass may have contributed to the reduced growth of other species sown with it in Seed Mix I by outcompeting them for the available moisture, sunlight and nutrients.  Biomass production per plant was far in excess of other species tested.  Spike development was apparent on all plots with between 90 - 100% of plants having spikes.  The spikes ranged from 8 to 12 centimetres in length on carbonaceous shale and baked clay, respectively.  Although lodging was common on all plots it was noted that the root systems were still intact with the soil, allowing growth to continue.  From these results it appeared the Fall Ryegrass would be most useful in short-term reclamation activities such as erosion control on temporary stockpiles. Canada Bluegrass had the poorest emergence success of all species studied, failing to appear on three of the untreated soils.  Plants that did exist showed only rudimentary development, and few possessed panicles. The presence of topsoil generally improved success though it remained very low.  These results are surprising since this species is widely recommended for revegetation on poor soils and in dry climates.  Whilst it is speculated that either low seed viability or lack of compatibility with the other species with which it was sown may be responsible for its poor performance, it will continue to be monitored to see if it develops in subsequent years. Alfalfa showed only a 4% emergence success.  Plants were generally stunted and exhibited rudimentary, i.e. no flower, development.  Seed-lings never attained a height of greater than about 9 centimetres, Proceedings of the 3rd Annual British Columbia Mine Reclamation Symposium in Vernon, BC, 1979. The Technical and Research Committee on Reclamation 262 consequently biomass production was low.  Alfalfa was seeded with Fall Ryegrass which appeared to outcompete other species in the mix for available moisture and/or nutrients.  There is evidence elsewhere that when competition is reduced the Alfalfa was much more successful. Seed Mix I (Table 1) produced the greatest quantity of biomass, primarily as a result of the Fall Ryegrass.  This species was included to provide early revegetation.  However, its size and vigour is suspected to have inhibited the development of at least two of the other species, Alfalfa and Crested Wheatgrass, by outcompeting them for the available moisture and nutrients.  The Canada Bluegrass performed so poorly, it is suspected that, in addition to any competition effects, the seed itself may not have been viable.  The competition provided by Fall Ryegrass notwithstanding, it would obviously be of considerable value in any short-term revegetation program. Seed Mix II.  This seed mixture comprised Russian Wild Ryegrass, Slender Wheatgrass, Sainfoin, and Sweet Clover.  Each species is discussed below. Russian Wild Ryegrass with its overall emergence success of 29% on un-treated soils showed excellent results on all but the carbonaceous materials.  Of particular note is its performance on the bentonitic clay and gritstone soils where it would appear to be a most useful species. Whilst the number of plants per square metre was high, the plants them-selves were small and did not show any signs of spike development.  This species is characteristically slow to develop which would explain the observations.  It remains to be seen whether it will continue to develop into large plants and thus fulfill, in the long term, its short-term promise. Proceedings of the 3rd Annual British Columbia Mine Reclamation Symposium in Vernon, BC, 1979. The Technical and Research Committee on Reclamation 263 The average emergence success of Slender Wheatgrass was similar to that of Crested Wheatgrass, but a substantially greater percentage of plants showed spike development.  The plants themselves were generally quite large, as shown by the high biomass production and thus the species should be useful in short-term revegetation programs designed for ero-sion control.  The high emergence success on topsoiled coaly waste is noteworthy. Sainfoin showed good emergence success on all materials except the carbon-aceous soils and fly-ash.  It clearly outperformed all other legume species tested.  On average, about 5% of the plants were mature.  The addition of topsoil improved both emergence success and plant size substantially. The overall germination success of Sweet Clover was lowest of all legumes. Sweet Clover is a biennial which was expected to develop rapidly in the first year.  This did-not occur except along the periphery of the plot where, presumably, competition from other species was less. Seed Mix II (Table 1) produced the greatest number of plants per square metre overall even though its performance on the carbonaceous materials was poor.  The species in the mix appeared to be compatible.  Neither of the grasses provide Sainfoin with excessive competition.  The Sweet Clover did appear to suffer competition from the other species, collectively, since it was found to do well only along the periphery of the plots where competition was least. Seed Mix III.  This seed mixture comprised Smooth Bromegrass, Stream-bank Wheatgrass , Canada Bluegrass (Rubens), and Double Cut Red Clover. Each species is discussed below. Overall, the Smooth Bromegrass, a long-lived sod grass, ranked third in emergence success on untreated soils.  However, its average success was Proceedings of the 3rd Annual British Columbia Mine Reclamation Symposium in Vernon, BC, 1979. The Technical and Research Committee on Reclamation 264 enhanced by a particularly good showing on the "better" soils, colluvium, baked clay and glacial gravels.  It showed only average success on the bentonitic clay and gritstone.  The particularly good productivity on the topsoiled coaly waste is noteworthy.  Plants generally had not reached the reproductive stage at the time of sampling in early August.  Although Streambank Wheatgrass ranked only fourth overall, its emergence success on the carbonaceous materials, bentonitic clay and gritstone suggested that it is a valuable species for reclamation.  Second and subsequent years growth needs to be followed carefully before this is clearly established, since the plants on these plots had not progressed beyond the seedling stage.  It is interesting to note that on the coaly waste, bentonitic clay and gritstone, the addition of topsoil had little effect on emergence success while the biomass produced per plant always showed an increase.  Characteristically it has a vigorous rhizomatous rooting system which should enable the grass to spread rapidly in sub-sequent years to form a good ground cover and enhancing soil stabili-zation. Canada Bluegrass  (Rubens) showed very poor success and was only margin-ally better than the common variety.  It may yet develop in subsequent years; however, it does not appear suitable for short-term revegetation programs in the present seed mix. Double Cut Red Clover showed approximately the same germination success as Alfalfa.  Growth was particularly successful around the perimeter of the plot where plants became quite large.  Flower development was evident on approximately 5% of those species within the plot proper, while those plants along the perimeter were more prolific. Seed Mix III (Table 1) had an overall biomass production similar to that of Seed Mix II.  However, the average number of plants per square metre produced was slightly lower, due mainly to the poor emergence success of Proceedings of the 3rd Annual British Columbia Mine Reclamation Symposium in Vernon, BC, 1979. The Technical and Research Committee on Reclamation 265 Rubens and Red Clover.  Although the Streambank Wheatgrass has a cha-racteristically vigorous rooting system, this did not appear to have any effect on the performance of the Smooth Bromegrass.   The Red Clover would seem to have suffered some competition since it was found mostly along the edges of the plots. Additional Factors in Plant Growth Climate.  The Hat Creek region receives on average 317 millimetres of precipitation annually, about half falling in the form of snow.  Summers are typically hot and dry resulting in a short growing period when moi-sture is available.  This low rainfall is a major factor in revegetation. The effect of a lack of moisture is noted in those areas where shallow pools of water collected; the vegetation is markedly more successful both in abundance and size compared with adjacent areas outside the "pools".  Surface preparations designed to retain surface moisture should be beneficial and are being studied further. A greater than average rainfall during the growing season (May -September), 157 millimetres compared with 139 millimetres average, was precipitated in 1977.  The results presented here should be viewed in this light.  The greater than average rainfall was partially offset by the greater than average daily temperatures. RESULTS FROM SLOPE TEST PLOTS Slope plots of 22, 26 and 30 were prepared at two locations, Houth Meadows and Medicine Creek, to examine the relationship between slope and revegetation success.  At Houth Meadows, half the plots were covered with topsoil.  Seed Mix I was used on all plots.  Results of plant counts and biomass production are given in Tables 9, 10 and 11. Considering first the data for the upper and lower slopes at Houth Meadows Proceedings of the 3rd Annual British Columbia Mine Reclamation Symposium in Vernon, BC, 1979. The Technical and Research Committee on Reclamation 266 (Table 9), the number of plants per square metre on the upper slopes was consistently less than on the lower slopes.  These plots were hydroseeded using a truck-mounted sprayer from the base of the plots.  These plots were all 15 metres high and varied in length between 30.5 and 40.5 metres, depending on slope angle.  It is suspected that because of the rather long distances over which the seed/fertilizer/mulch was sprayed, the upper slo-pes received less than the lower areas.  This suspicion is borne out by qualitative field observations which indicated that mulch density at the top of the plots was less than on the lower portions.  At Medicine Creek where hydroseeding was carried out from a truck located at the top of the plots and on foot, using a hose, the upper and lower slopes show approxima-tely the same catch (Table 11). Comparing the number of plants produced on plots of different slope angle, Tables 9 and 11 show that the greatest number of plants per square metre were located on the steepest slope, 30°.  At Medicine Creek, the average difference between the 22° and 26° slopes and the 30° slope amounted to a factor of 2.  At Houth Meadows, the difference is not as great but the 30° is still the most successful.  As mentioned above it is difficult to obtain consistent application rates when hydroseeding.  It may be that the 30° slopes received a greater seed application than other plots.  In any event it would be unwise to infer from these data that slopes of 30° are actually more suitable for plant growth than those less steep.  However, it would seem reasonable to conclude that there are no major deterrents to growth, at slopes as steep as 30°.  Examination of the slopes indicated that waterborne erosion was minimal in the first year.  This is noteworthy since rainfall received at Hat Creek during 1977 was above the average. Effect of Topsoil Half of each plot at Houth Meadows was covered with approximately 5 centimetres of topsoil.  Results of plant counts and biomass production are shown in Tables 9 and 10.  As found on the glacial gravel at Proceedings of the 3rd Annual British Columbia Mine Reclamation Symposium in Vernon, BC, 1979. The Technical and Research Committee on Reclamation 267 TABLE  9 AVERAGE NUMBER OF PLANTS PRODUCED AT HOUTH MEADOWS  TABLE 10  TOTAL BIOMASS PRODUCED AT HOUTH MEADOWS (g/m2)  Proceedings of the 3rd Annual British Columbia Mine Reclamation Symposium in Vernon, BC, 1979. The Technical and Research Committee on Reclamation 268 TABLE 11 AVERAGE NUMBER OF PLANTS PRODUCED AT _________ MEDICINE CREEK ________   Proceedings of the 3rd Annual British Columbia Mine Reclamation Symposium in Vernon, BC, 1979. The Technical and Research Committee on Reclamation 269 Aleece Lake, there was a reduction in plants per square metre on the topsoiled portions of the plots.   The topsoil in this case came from a different location from that used at Aleece Lake and contained greater quantities of weed seeds.  The number of invaders on topsoiled portions of the Houth Meadows plots was appreciable and, as a result, may have caused competition contributing to the lower number of plants per square metre.  On average, 42 invaders per square metre were found on the Houth Meadows plots compared to 9 per square metre on the gravel plot at Aleece Lake. Weed species diversity was not as great as at Aleece Lake.  Three species, Flixweed (Descurainia sophia), Blueburr (Lappula echinata) and Stinkweed (Thalspi arvense) made up 86% of all invaders.  CONCLUSIONS The revegetation test results presented here relate only to vegetation success in the first season following a fall seeding.  The detailed examinations have been carried out to determine the degree to which vegetation may be established on the waste materials in the short-term.  This aspect refers to B.C. Hydro's major short-term goal in the overall reclamation effort, namely the rapid establishment of vegetation to prevent wind and/or waterborne erosion.  The primary conclusions of these studies may be summarized as follows: 1. Vegetation is readily established on surficial materials, colluvium, glacial and recent gravels and baked clay. 2. Although vegetation cover on the bentonitic clay and gritstone was substantially less than on the surficials, the effect was most notice able in terms of plant size rather than seedling abundance.  The nature of these clayey materials in forming a surface crust when dry would mitigate against wind erosion even in the absence of vegetation. Proceedings of the 3rd Annual British Columbia Mine Reclamation Symposium in Vernon, BC, 1979. The Technical and Research Committee on Reclamation 270 3. The carbonaceous materials would be the most difficult to revege- tate of all materials examined.  A surface capping would be necess ary if successful revegetation is required in the short-term. 4. Plant growth on fly-ash was stunted although there were a large number of individual seedlings.  Some problems due to the rela tively high boron content may be expected.  A surface capping of surficial soil would be beneficial if vegetation for short-term erosion control is to be established. 5. The addition of topsoil to the carbonaceous materials, bentonitic clay and gritstone resulted in improved seedling emergence and biomass production.  On the colluvium and gravels the converse was observed.  These results indicated that the materials selected for stripping and stockpiling as surface growth media, may comprise gravel, colluvium, till and topsoil either separately or in combi- nation. 7. Several grass and legume species suitable for short-term revegetation of waste materials at Hat Creek have been identified.  Among the grasses Fall Ryegrass, Streambank Wheatgrass and Slender Wheatgrass were of particular note, while Sainfoin was the most successful legume. 6.   Short-term revegetation of dump faces comprised of either colluvium/ till or gravel with an overall height of 15 metres and with slopes up to 30 was readily achieved without serious waterborne erosion problems during the first year.  Proceedings of the 3rd Annual British Columbia Mine Reclamation Symposium in Vernon, BC, 1979. The Technical and Research Committee on Reclamation 271 REFERENCES 1. Hathorn, F.G. and McQueen, D.K., Proceedings of the Second Annual British Columbia Mine Reclamation Symposium, Vernon, B.C., March 1978, P. 109. 2. Zar, J.R., 1974, Biostatistical Analysis, Prentice-Hall, Inc., Englewood Cliffs, N.J. 

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