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with greater topographic relief and /or with shallower depths of <br />reapplied topsoil. <br />A second prerequisite involves provision of spoil below topsoil <br />with acceptable characteristics, and, again, this prerequisite may be <br />most critical in situations where shallower topsoil redeposition is <br />contemplated. As noted by Dollhopf et al. (12), overburden - derived <br />spoil material with undesirable physical /chemical characteristics <br />should not be deposited within the root zone of vegetation on mined <br />lands; examples of poor revegetation success in situations where sur- <br />face spoil was inhibitory and reapplied topsoil was thin are common in <br />the literature (33). In short, spoil (which will constitute the new <br />"subsoil ") on sites treated with shallower topsoil depths should at <br />least be relatively non - inimical with respect to salts, pH, toxic <br />elements, etc., although it implicitly will be of lower and /or <br />different quality from topsoil in other respects. <br />Selective Handling of Soil Types <br />Many, if not most, pre- mining landscapes in the Northern Great <br />Plains are characterized by a variety of different soil types which <br />often support a corresponding variety of distinct plant communities. <br />Despite the availability of information on existence /characteristics <br />of pre - existing soil types from baseline studies and the known, varied <br />influence of different soil types on revegetation potential (e.g., 43), <br />with certain exceptions topsoil of most mined land sites is salvaged, <br />handled /mixed and reapplied without special attention to segregation <br />of different types. The result of this usually has been creation of <br />"homogenized" minesoils with increased micro- but decreased macro - <br />variability as compared to pre - existing soils (44). The reduction in <br />soil macro - variability (i.e., fewer defineable soil types) plus <br />differences in spatial arrangement of soil types over the landscape <br />after. mining (42) have significant implications on the feasibility of <br />ultimate achievement of inter -plant community diversity, if such is <br />desired. <br />Schafer (42) suggested that some degree of separate, selective <br />salvage, handling and redeposition of distinct soil types might comprise <br />one means of reducing the currently widespread homogenization of soils <br />following mining, and thereby might promote establishment of different <br />vegetation types. The goal of such an approach would be to create a <br />mosaic of distinctly different soil types after mining, possibly proper- <br />ly integrated with topographic variations. Such an array of soil types <br />would then provide a varied physical base conducive to development of <br />a correspondingly diverse array of vegetation types. <br />The principle of selective handling of soil types to enhance vege- <br />tation type differentiation and diversity is certainly theoretically <br />logical. However, the degree of selectivity possible /necessary, the <br />actual benefits and the practical feasibility of the approach remain to <br />be determined by research and /or application. <br />266 <br />