2002-07-08_GENERAL DOCUMENTS - M2002004 (4)

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SUMMARY Vegetation diversity, both within and among plant communities, is often an important consideration in reclamation of mined lands in the Northern Great Plains. The specific nature of topsoil application and management methods can be expected to directly influence diversity as well as other aspects of vegetation on mined lands. Several topsoil application /management practices may affect diver- sity within mined land plant communities. Existing evidence strongly supports the beneficiality of rapid reapplication of topsoil following salvage and relatively limited use of fertilization to increased intra- plant community diversity. Multiple lift topsoiling and supplemental fresh soil top- dressing may have some potential to increase diversity; however, further evaluation is needed to substantiate /disprove the actual utility of these approaches. The relationship of topsoil appli- cation depth to intra - community diversity is not fully understood, has proven rather inconsistent, and consequently requires further research on a site /vegetation- specific basis. However, some research has demon- strated higher plant community diversity under shallower depths of reapplied topsoil. Two topsoiling strategies were hypothesized to have potential for creation of increased edaphic heterogeneity and hence greater diver- sity among different plant community types on mined lands: varied top- soil depths on different sites and selective soil type salvage /deposi- tion. Both approaches, however, require field research and application with respect to practicability and effectiveness before firm recommenda- tions on utility can be made. A strong implication from a number of principles discussed is that in certain instances topsoil practices to enhance vegetation diversity may not be identical to practices to maximize absolute, total producti- vity. Optimum diversity within plant communities has sometimes occurred under fertilization regimes, topsoil depths and /or mulching regimes below those necessary to achieve maximum productivity. Increased diver- sity among plant community types achieved via varied topsoil depth or selective topsoil type handling approaches, if such ultimately do prove utilitarian, could also conceivably be at the expense of total, area - wide productivity. Therefore, a tacit acceptance of some degree of lower overall productivity may sometimes be necessary, at least initially, for increased vegetation diversity on mined lands. Whether or not this price is "too high" to pay will then depend upon site - specific reclamation goals. 267