The Relative Merits of Native Transplant Plugs and Topsoil Islands in the Enhancement of Understory Biodiversity on Reclaimed Minelands

Abstract

In northeastern Ontario, Canada, mine tailings and lands rendered barren by smelter emissions are commonly revegetated using a grass-legume mixture, then planted with native trees, mostly conifers such as Red, White and Jack Pine. Vigorous colonization by native pioneer tree species such as White Birch and Trembling Aspen occurs, as well as that of native herbs associated with forest openings, such as Asters and Goldenrods. However, it is rare for the herbs and shrubs found in the understory of a mature pine forest to colonize these artificially wooded sites. Native understory species have been transplanted from natural habitat at an experimental level over a number of years on grassed smelter-affected barrens and grassed tailings, to determine whether such transplants survive and spread. Small islands of forest topsoil have also been established on grassed tailings. The source of native plugs has been predominantly mature Jack, Red and White Pine forest, but species adapted to naturally exposed sites such as sand dunes have also been transplanted with success. Not surprisingly, the species that spread most readily are those possessing rhizomes or stolons, such as Canada Mayflower (Maianthemum canadense) and Starry False Solomon's Seal (Smilacina stellata) in the case of plugs, and Spreading Dogbane (Apocynum androsaemifolium) in the case of topsoil islands. Since results so far suggest that both approaches are valid, the relative advantages of each are critically appraised.