Reestablishing natural succession on acidic mine spoils at high elevation

Methods for restoring native plant communities on acidic mine spoils at high elevations were evaluated in a "demonstration area" in the New World Mining District of southern Montana. Research plots installed in 1976 were assessed for 22 years and compared with adjacent native reference plant communities. A 1.5-acre (0.61-ha) area of mine spoils was shaped and treated with hydrated lime, organic matter, and fertilizer. The area was then seeded heavily with five native grasses collected from adjacent native plant communities. Natural seed rain, transplanting, refertilization, and use of introduced species were also studied. During periods of fertilization, biomass and cover were twofold greater than in adjacent native reference communities in some years, but then rapidly declined to levels observed in native reference communities. Natural succession was accelerating within the demonstration area toward formation of a native community with characteristics similar to adjacent reference areas. Soil genesis was progressing and a soil "A" horizon was developing. Use of native seral species appears necessary for long-term formation of a self-sustaining natural community. Both transplanting and natural seed rain on treated spoils resulted in significantly lower biomass and cover levels than on the seeded area. Our data demonstrate that acidic mine spoils, such as in the New World area, can be treated successfully in-place with lime, organic matter, and fertilizer, and then seeded with a mixture of native seral grasses, followed by surface mulching with erosion blanket. Capping with native soils is unnecessary. Reclamation principles and procedures are summarized.