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• GRAZING EFFECTS OF PLANT SPECIES DIVERSITY <br />Plant species diversity is a reclamation requirement which has <br />burdened most reclamation specialists. Grazing has been <br />incorporated into several post-mining management schemes, on a <br />research basis, to evaluate its influence on plant diversity. <br />The impact of grazing on species diversity has shown a wide <br />range of responses dependent upon climate, herbivore type and plant <br />species. Bowns and Bagley (1986) studied the impact of sheep <br />grazing on species diversity on a high elevation summer range in <br />Utah. Thev cor_cluded that species diversity and richness were much <br />greater on the ungrazed reference area than in the grazed pasture <br />as a result of selective grazing by sheep. 3rady et al. (1989) <br />studied the response of a grassland to the removal of grazing <br />• pressure. After 16 years of rest from grazing, species diversity <br />increased as did total foliar cover. These results indicated that <br />long-term changes in vegetative composition are occurring with the <br />removal of grazing. <br />Another set of studies illustrated the positive impact of <br />grazing on species diversity. Research by Deouit and Coenenberg <br />(1980), Kofmann and Ries (1980), Kleinman and Layton (1981), and <br />Williamson (1981) have shown that grazing can be used as a <br />management scheme to positively affect species diversity and <br />richness on reclaimed mine lands. DePuit and Coenenberg (1980) <br />reported that species diversity increased following three years of <br />grazittg on a reclaimed site in Montana. These changes were <br />• attributed to openings in the canopy which allowed colonization by <br />other species. Williamson (1981) reported that more intensively <br />