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i • ~rarioc Div -rsity. Species diversity will generally be evaluated by comparing the relative importance of species occurring in the upland sagebrush reference area to the relative importance of species occuning in the reclaimed areas. The relative importance value to be used is relative cover with the minimum value set at 3 percent relative cover. Because the postmine land use is a combination of dryland pasture and rangeland, a modified compar_ ison between the_iwo-areas-will-be_made. The upland sagebrush reference area contained three grasses, tw.o_sJ)rubs~ one succulent, and one annual grass with relative cover values greater than_3•_ ercent. The forb component was generally lacking in individuals and none achieved values of 3 percent relative cover. The combined species, (i.e., those with relative cover greater than 3 percent) totaled nearly 85 percent of the relative cover. Establishment of succulents and annual grasses in the reclaimed communities is either impractical or undesirable. Thus, these two growth forms will not be considered, Again, because of the combined postmine land use of dryJarld_pasture and rangeland, the establishment of_sh[ubs_in the reclaimed community will not be at or near premine levels. The shrub fourwing saltbush is included in the rangeland seed mix to enhance overall woody densities and has been successfully established in the past. No forbs were found to have relative cover values equal to or greater than 3 percent. The rangeland seed mix includes two ~~,q$~o- forbs (one is also a legume), one subshrub,, and one shrub. The seed mix has been developed to achieve the postmine land use and be equal to or superior in utility to the premining vegetation. - The species diversity standard to be achieved for rangeland will be three grasses, one forb, and one shrub. The three grasses, one forb, and one shrub will have relative cover values of 3 percent or greater. The establishment of at least one forb wilt mitigate for a reduction in seasonal ~..- variety and shrub composition. The combined relative importance will not be greater than 85 punt and no one species will contribute greater than 40-percent.re(aUve importance. ,_ Seasonal Variety. !t is requested that the seasonal variety requirements be waived for the following reasons. t~warm season_grasses, blue grama and galleta, occur in the premining vegetation community. Both of these species have been used in past reclamation activities at the Nucla Mine with very poor results. To achieve quick establishment of a protective vegetative ---~~ cover and utilitarian levels of production, drought tolerant cool season grasses are included in the mix. These cool season grasses easily out-compete the poorly germinating and slower developing warm season grasses. This is compounded further by the very low precipitation received in the area. In order to document this concern, support previous field observations, and provide additional basis for the requested waiver, a study of areas revegetated with mixes containing warm season grasses was undertaken in the summer of 1988 to evaluate the success of warm season grass establishment. Cover and frequency data were collected on July 13-14 in 22-12