In the Yukon, the goal of most reclamation programs is to return disturbed lands as close to their original wildlands state as is feasible. The revegetation process, an integral component of reclamation, can be manipulated in ways to reflect this ultimate land use objective. The report reviews past Yukon reclamation practices and looks at how natural successional processes can be encouraged on lands disturbed by mining and mineral exploration practices. By examining the factors that affect the successional patterns of revegetation on disturbed sites, and by noting the composition of plant communities that colonize these areas, the most appropriate pioneering shrub species can be selected for assisted revegetation programs. The species selected for revegetation must reflect each site's ecological variables, as well as the nature of the mining-related disturbances. The reclamation potential of Yukon native shrub species is discussed in this report, along with techniques for assisted revegetation, including the collection of plant materials and propagation methods. The reclamation capabilities of 23 locally occurring shrub species is appended to this report. This information has been extracted primarily from vegetation experimentation in Alaska and northern Alberta. In order to determine whether these native shrubs are viable as species for reclamation work in the local environment, seeding and planting trials are recommended at Yukon mine and mineral exploration sites.

Considerable research has been carried out into the reclamation and revegetation of disturbed lands in the Yukon, including operating and abandoned mines, and mineral exploration sites in the Yukon. Reclamation efforts on tailings have focused on methods to establish an initial vegetative cover on disturbed areas. Guidelines have been established by Kennedy (1993) and Hill et al. (1996) for the optimum mixtures of fertilizer and seeds (both agronomic and native varieties)¿. ¿.A relatively new and unique method of tailings processing and disposal that is being used at a few mines around the world is called dry stacking. This method of tailings disposal has the potential to provide many benefits to mining companies and affords numerous environment advantages that slurry deposits do not¿. ¿.The purpose of this proposed project was to research current practices in other jurisdictions and to examine the best approaches for encouraging vegetative establishment on dry stack tailings in norhtern environments, particularly for potential mine sites in the Yukon.

There have recently been many changes in the way mining exploration projects operate, including new technologies, new exploration targets and new environmental regulations. Following recent amendments, to the Yukon Quartz and Placer Mining Acts, a significant new piece of legislation came into effect in December, 1999. The Yukon Quartz Mining Land Use Regulations, administered by the Department of Indian Affairs and Northern Development, now requires the reclamation of disturbed land on mining claims. But what happens at these reclaimed sites several years after the work is finished? Is there more than one way to successfully reclaim such land? How do local conditions affect the regrowth of plants on these sites and how much preparation of the reclaimed surface is needed? This report may not provide answers to all these questions, but it presents data collected at several Yukon sites, each with different ages and having had different reclamation treatments. From these observations, patterns on the success or failure of revegetation programs emerge and provide information on the rate and extent of natural revegetation at reclaimed mining trenches. Several types of reclamation sites were looked at in several different areas of Yukon, both above and below the treeline. Three of these were exploration trenches that were backfilled and revegetated as part of an experimental reclamation program in 1995. These reclaimed exploration sites included the Red Ridge trench, near Annie Lake in the Whitehorse area, the Nucleus trench, west of Carmacks and the Hawk trench near Dawson City. Each of these reclaimed trenches were revegetated with different seed and fertilizer mixes. This report summarizes how these sites looked in 1999, four years after the reclamation work was done. At Division Mountain, west of Braeburn, several coal trenches and drill pads were reclaimed by a mineral exploration company between 1995 and 1997. These sites were also looked at in 1999 in order to measure the success of the revegetation program. The last place visited in 1999 was Jason Knoll near Macmillan Pass where a number of exploration trenches and drill pads were reclaimed in the early 1980s. This site provides a look at the longer-term success rate of a revegetation program near the treeline. Refilled and contoured trenches, with rough and loose surfaces seem to revegetate well. The replacement of original soil is most important and makes the most significant contribution to the revegetation process, particularly at high elevation sites or sites in extreme climatic conditions. The replacement of tree debris significantly improves habitat conditions for small mammals by decreasing access and visibility for predators.

Placer mining occurs extensively in parts of the Yukon, denuding riparian zones and lining valley bottoms with mine tailings. Revegetation of tailings was examined at two placer mines near Mayo to determine the influence of environmental variables on the speed and direction of the natural process. Vegetation species density and frequency on various substrates were compared with: age, slope and aspect of the site, and pH, particle size distribution, moisture content and organic content of the soill. In central Yukon, tailings are first colonized by ruderal (weedy pioneer) species such as fireweed and members of the Compositae (dandelion) family. These are replaced by willow-dominated communities after nine years. Willow communities support many species characteristic of the adjacent undistrubed black spruce forest, suggesting that the placer succession is similar to that of riverbank environments in interior Alaska. Revegetation of the tailings proceeds at the same rate for the first twelve years as does that following natural disturbance. Of the environmental factors examined, only age and slope were, statistically, associated with rate of revegetation. Both the percent cover and the number of species at a site were inversely associated with slope, suggesting that reduction of slope angle enhances vegetation regeneration.

Reclamation testing was carried out on 3 mineral exploration sites in Yukon: an alpine site at the Red Ridge property in the Whitehorse area, and 2 subalpine sites, a boreal forest site at the Nucleus property in the Carmacks area, and a site in moist permafrost at the Hawk propeerty int he Dawson City area.

This is a re-release of data collected and published as the Yukon GEOPROCESS FILE between 1994-1996. The data set is a compilation of information and knowledge on geological processes and terrain hazards in the Yukon Territory. The original work was carried out in three phases from 1992 to 1995. Contractors performed the work under the supervision of the Environmental Geologist, Exploration and Geological Services Division, Yukon Region, Indian and Northern Affairs Canada. The following individuals and companies were involved in carrying out the project: Mougeot GeoAnalysis, Aurum Geological Consultants Inc., L. Walton and C. Hart.

A mineral assessment of the Tombstone study area was undertaken by the Department of Economic Development in the summer of 1998 at the request of the Department of Renewable Resources. The purpose of the mineral assessment was to produce a mineral potential map, which was to be used to assist with the finalization of the boundaries of the Tombstone Territorial Park. Following an initial compilation, a field program was designed to document known mineral occurrences, test and improve the existing regional mapping, investigate geochemical anomalies, characterize favourable environments for mineralization, sample for lithogeochemistry, and prospect for mineralization. A field program resulted in the discovery of several new mineral occurrences, as well as the discovery of previously unmapped geological formations. Fieldwork was followed by a compilation phase that integrated the new information to the existing geoscientific data. The geology of the study area was subdivided into thirteen geological tracts. A panel of five industry and government experts, familiar with the geology, mineral occurrences and mineral deposit types to be found in the area, was convened in June 1999. Based on the final compilation and their expertise, they produced a relative ranking of all the tracts according to their potential to host mineral deposits, from highest potential to lowest. The highest-ranking tracts are those that include, or are near the Cretaceous intrusions (Tombstone, Mount Brenner and smaller intrusions) and have strong potential for intrusion-hosted (Fort Knox-type, porphyry uranium, skarn) and intrusion-related (skarns, veins, replacement) mineralization. Other tracts demonstrate potential for Wernecke Breccia, shale-hosted nickel sulphide, ultramafic-hosted nickel and listwaenite, Carlin-type, Mississippi Valley-type or replacement lead-zinc, as well as volcanogenic mineralization. A final boundary was adopted in December 2000; it includes land outside of the original study area. This final boundary therefore includes areas that were not assessed in this study. All our wildlife sightings were documented and were included in the subsequent wildlife survey.

The revegetation of northern tailings sites presents many challenges. By using plants, which are naturally adapted to both the tailings environment and northern climatic conditions, fewer amendments and intervention will be required. In 2003, vegetation growing on and off the tailings and soil at three Yukon Territory, Canada, mine sites (United Keno Hill, Mount Skukum, and Wellgreen) was assessed and soil samples were collected. Through Canonical Correspondence Analysis (CCA), a statistical program that assesses relationships between plant species and environmental variables, I found that these plant communities are largely governed by a chemical-nutrient gradient (heavy metals and nutrients) and a ground cover gradient (bare and exposed conditions compared with full ground cover). The native grass Deschampsia caespitosa L. Beauv. was found colonizing all three tailings sites and its presence was associated with low nutrients, high heavy metal levels, and exposed ground, but it was also a habitat generalist. Five Yukon populations of D. caespitosa, originating from mine and uncontaminated sites were tested hydroponically for their tolerance to elevated Ni, Zn, and Cd concentrations. Intrinsic multiple metal tolerance occurred in all populations. In revegetation field trials in the Yukon, I planted seeds and transplants of 7 populations of D. caespitosa under different treatments: i) untreated, ii) compost, iii) fertilizer, and iv) combined (compost and fertilizer). At all sites, during the two years of data collection, local and non-local populations, including those from non-contaminated sites were able to establish, grow, and reproduce, even in unamended tailings and despite successive hot and dry summers. D. caespitosa also acted as a nurse crop, facilitating invasion of plants from adjacent habitats. The short term results suggest that the inclusion of Deschampsia caespitosa as a nurse crop for the revegetation of these northern mine tailings sites will be beneficial.

This is the third in a series of five-year planning documents that have guided government geoscience in Yukon over the last ten years. It presents a broad set of needs and priorities for Yukon geoscience for the next five years, but is not a business or work plan. Although developed primarily from the Yukon Geological Survey (YGS) perspective, the Geological Survey of Canada and universities will help to meet these needs either independently or through partnerships with the YGS. It was developed during the spring, summer of 2004 as an internal draft that was later modified and refined through consultation with the Geological Survey of Canada and the Technical Liaison Committee to the YGS. Over the last five years, the need for geoscience information has grown and spread to a wider and wider audience. Geoscience is utilized primarily by the mining and petroleum sectors to support exploration for minerals and hydrocarbons, but it is increasingly playing a role in other industries such as forestry, fisheries and tourism. In all of these industries it is playing a role in their development and management. Decisions related to the utilization of natural resources are increasingly being made or influenced by many groups including developers, land managers planners, regulators, First Nations, and the general public. Their decisions need to be formed with accurate information about the nature and potential of resources, and the best practices in mitigating and preventing environmental damage. This volume includes sections on: bedrock mapping, mineral deposit studies, mineral assessments, regional geochemical and geophysical surveys, subsurface geology, energy/hydrocarbons, surficial geology and placer deposits, information management and outreach.