Factors affecting the natural revegetation of areas disturbed by airborne emissions were studied at the Anyox smelter on the northern coast of British Columbia. Revegetation of areas where vegetation and soil were removed by industry were studied on mine waste dumps on Vancouver Island, on mine wastes in the West Kootenays, and on abandoned logging roads on Vancouver Island and near Lumby. At Anyox, much of the direct evidence of fume damage was eradicated by a fire in 1942, which occurred eight years after smelting operations ceased. This fire encompassed a five-mile radius surrounding the smelter. Tree-ring analysis on surviving western hemlock trees, extending from the edge of the fire to the head of Alice Arm, showed a strong relationship between the tonnage of ore smelted and the radial increment. Tree growth was initially depressed when smelting began in 1914 and remained low until smelter operations ceased. At this time the growth dramatically increased, but by 1970 the annual radial increment had returned to a slow rate similar to before smelting operations began. Western hemlock was much less susceptible to fume damage than western red cedar. Although total fume kill occurred on western red cedar as far south as the Nass River, north to the head of Hastings Arm and East to the head of Alice Arm, total kill on hemlock took place within a few miles of the smelter. Fume damage was the heaviest near the smelter and near the head of Alice Arm where the topography confined the fumes, rendering them more effective. Within the area affected by the 1942 fire, revegetation was slow near the smelter and was more rapid near the mature vegetation. Seeds which are easily dispersed by light wind, were responsible for the majority of colonizing species many of which were found rarely in the surrounding unburned vegetation. On logging roads and mine waste materials, seed source availability appeared to be the major factor in determining the colonizing species. Light wind-blown seeds were the initial colonizers on coastal logging roads, and adjacent vegetation supplied the seed source for the interior logging roads. The establishment of salal through vegetative means was' observed to occur on coastal logging roads. Species with the ability to fix nitrogen, with the exception of alder, played a minor role in natural revegetation of most areas. Slow revegetation of large-scale disturbances was attributed partly to the lack of adequate seed. The most common cause of slow revegetation in most areas was moisture deficiency. Moisture availability on mine wastes at Cumberland appeared to be determined by slope, aspect, color, shading and mound height. On logging road surfaces, in both Lumby and coastal areas, a reduction in plant growth on steeper slopes was attributed to reduced moisture. Wind exposure was found to be the most important factor governing revegetation of mine wastes in the West Kootenays. Coarse textured material was related to a lower percentage cover of vegetation on the surface of coastal logging roads. Uniformly coarse textured material on the waste dumps in the West Kootenays precluded any significant statistical relationships. Coarse textured materials, nevertheless, had a general inhibitory effect on the rate of revegetation of many of the mine waste dumps. Steep unstable slopes were a major factor which prevented revegetation of West Kootenay mine wastes and on the upslope of road cuts. The scale of disturbance was found to magnify or obscure many of the factors important to successful plant colonization. The chemical composition of waste material, although studied only peripherally, did not appear to be a major factor in determining the revegetation of disturbed areas at the sites studied. Low pH values, which are often taken as a barometer of mine waste toxicity, occurred rarely. In many instances, high pH values may have prevented the successful invasion of acid-loving species. In applied reclamation procedures, it is mandatory that objectives for future land use be incorporated into planning, along with the anticipation of inhibiting factors. If no conditions are left which prevent plant growth, then reclamation will be straightforward and land use goals will be more easily satisfied. / Forestry, Faculty of / Graduate

This study describes an investigation of the potential for pioneer grass-legume communities to stabilize and ameliorate geologically-fresh soil leading to the establishment of a self-sustaining, progressive plant succession on a surface-mined subalpine site. The study area is located 2,000 m above sea level in the Canadian Rocky Mountains. Field surveys at the site indicated extremely limited invasion of reclaimed areas (3-7 years old) by native species from the adjacent subalpine forest. Soils on revegetated sites were generally warmer and drier than soils of the associated forest and have less than half the content of fine soil fragments (<2 mm). Field studies revealed chronological trends in grass-legume communities at four sites revegetated during 1974-1978 including: species composition, legumes (Trifolium repens L., T. hybridum L. and Medicago sativa L.) performing increasingly poorly on the older sites; biomass changes, a shoot to root ratio (S/R) decreasing from 2.3 to 0.2 as the communities aged; and litter accumulation which continued even on the oldest site. Fertilizer (13-16-10) operationally applied at 150 -391 kg/ha enhanced the growth of Dactylis glomerata L. and litter degradation, and acidified the soil. Nitrogen fertilization was also associated with two clear inverse relationships identified between D. glomerata and Festuca rubra L. biomass, and between soil pH and phosphorus levels. In greenhouse tests grasses were revealed to be more efficient soil nitrogen consumers than were legumes and nitrogen fixation decreased significantly (P<0.01) and linearly with increasing grass seeding rates. In the presence of grasses, nitrogen fixation was positively correlated with aboveground legume biomass at all nitrogen fertilizer levels tested. The results further revealed that operational seeding and fertilizer rates at this site may not optimize plant productivity and the ability of legumes to fix nitrogen symbiotically. Field trials based upon the experimentaly derived combination (17.5 : 30 : 50 kg/ha grass seeding rate : legume seeding rate : nitrogen fertilizer rate) would be desirable to evaluate these data on the site. Other potential practical implications from this study are: (1) The need for improved legume establishment, involving legume seed germination, species and variety selection, and selection of Rhizobium strains. (2) Improved control of the operational fertilizer application. (3) Alteration of grass and legume species composition of the present seed mix. (4) Selective placement of initial material (overburden or spoil) handling. A modification of the acetylene reduction assay, "the open system" technique, was developed for evaluation of legume nitrogen fixation of mine spoils. Although the unit developed is limited to detection of the presence or absence of ethylene, calibration with the closed system of ethylene levels obtained by the open system appeared feasible. Further refinement of the system for quantitative use would increase its usefulness in nitrogen fixation studies of legumes on mine spoils, nitrogen fixing woody plants in forests, and legumes in grassland sods. / Land and Food Systems, Faculty of / Graduate

Mine reclamation is a long-term process but few long-term (> 15 years) assessment studies are carried out. Considerable effort has gone into test-plot experiments to design revegetation programs prior to termination of mine production but little is known from the results of this work of the long-term effect of competitive interactions between seeded species themselves and between seeded and immigrating native species during the progression to a natural vegetation for that site. The present study revisited and repeated benchmark scientific studies carried out at five mine-sites during the period 1973-1978. The mine-sites were Bull River mine, Coal Creek mine, Cumberland No. 4 mine, Pinchi Lake mine and Texada Iron mines. They were in different biogeoclimatic locations and at each mine, sample sites were located on different waste materials. On-site studies carried out during the 1993 field season included substrate observation and sampling, and visual observation of plant species and percent cover. Substrate samples were later analysed in the laboratory for soil nutrients. The graphical presentation of data honours the original data and is an effective way of assessing the development of substrate health and plant succession. Results show that if sufficient attention is paid to improving land-form then over a long period natural regenerative processes can accomplish remarkable results. Moisture deficiency will restrict growth to deep rooting, drought tolerant species and result in slow encroachment. This may require intensive management if erosion is likely. This type of study performed by staff with interdisciplinary training or experience can be used to make economical long-term assessments of site rehabilitation. They would not in any way replace the detailed quantitative monitoring conducted at critical phases early in the decommissioning process. However, as a complement, such studies could provide data for predicting long-term development on newer sites. In addition, they are an ecologically acceptable alternative to assessments of "productivity" on sites where rehabilitation is slow.

Mine reclamation is a long-term process but few long-term (> 15 years) assessment studies are carried out. Considerable effort has gone into test-plot experiments to design revegetation programs prior to termination of mine production but little is known from the results of this work of the long-term effect of competitive interactions between seeded species themselves and between seeded and immigrating native species during the progression to a natural vegetation for that site. The present study revisited and repeated benchmark scientific studies carried out at five mine-sites during the period 1973-1978. The mine-sites were Bull River mine, Coal Creek mine, Cumberland No. 4 mine, Pinchi Lake mine and Texada Iron mines. They were in different biogeoclimatic locations and at each mine, sample sites were located on different waste materials. On-site studies carried out during the 1993 field season included substrate observation and sampling, and visual observation of plant species and percent cover. Substrate samples were later analysed in the laboratory for soil nutrients. The graphical presentation of data honours the original data and is an effective way of assessing the development of substrate health and plant succession. Results show that if sufficient attention is paid to improving land-form then over a long period natural regenerative processes can accomplish remarkable results. Moisture deficiency will restrict growth to deep rooting, drought tolerant species and result in slow encroachment. This may require intensive management if erosion is likely. This type of study performed by staff with interdisciplinary training or experience can be used to make economical long-term assessments of site rehabilitation. They would not in any way replace the detailed quantitative monitoring conducted at critical phases early in the decommissioning process. However, as a complement, such studies could provide data for predicting long-term development on newer sites. In addition, they are an ecologically acceptable alternative to assessments of "productivity" on sites where rehabilitation is slow. / Graduate and Postdoctoral Studies / Graduate