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• <br />The sample t statistic (tc,~~) to be compared with the weighted tabular t comparison statistic (y) was then calculated <br />as follows: <br />where: <br />and: <br /> <br />s~-xz =szo (ni+nz)/ninz <br />szn°[(ni-1) szi+(nz-1)szz I/(ni+nz-2) <br />where: Subscript 1 = premine vegetation type parameters <br />Subscript 2 =corresponding reference area parameters <br />Calculation of Diversity Indices <br />Diversity indices (Ii) were calculated for each species and vegetation type <br />period. The Sannon-Weiner Index as presented by Shannon et al. (1973 <br />recommended by the OSM (Larson 1980) was the methodology employed for <br />study. Calculation of these indices occurted as follows: <br />H=-EP;IogP; <br />C <br />where: P; = N, / N <br />N; =individual cover value for species (i) <br />N =total vegetation cover for all species combined <br />Description of Veeetation Communities Sagebrush <br />sampled during the 1984 sampling <br />and again by Pielou (1975) and <br />the indices presented with this <br />The sagebrush vegetation type historically dominated Twentymile Park prior to the conversion of the land to <br />agriculture. It was found on moderate slopes, gently rolling hills, upland benches, and bottomland tertaces; and on <br />all aspects. Currently it is found along the toe of the foothills surtounding the park and on areas within the park <br />which are unsuitable for agriculture. The sagebrush vegetation type curtently occupies roughly 17.5 percent of the <br />proposed permit area or approximately 2,250 acres. Limited disturbances to this vegetation type, i.e. construction <br />Hof the EMD Borehole and Rock Dust Tank, has occurred at the mine. <br />As identified on Table 24, Vegetation-Soils Cortelation, and Table 25, Characteristics of Soils Underlying the <br />Sagebrush Vegetation Type, several soils aze found below the sagebrrsh community. These soils are always well <br />drained, usually deep, and were developed from shale and sandstone parent materials. The permeability of these <br />soils is usually very slow; however, it ranges to moderate and moderately rapid on occasion. The available water <br />capacity ranges from very low to high with no clear trends discernible, and the land capability subclass of these <br />soils is most often VIe (see land use discussion under 2.04.3 for further information regarding land capability <br />subclasses). <br />As identified on Table 26, Sagebrush Vegetation Type, the shrub stratum is dominated by low sagebrush with <br />10.73% ground cover and 57.37 g/mz production, mountain big sagebrush with 6.73% ground cover and 25.45 <br />• <br />~~~~~~~~ APR 2 4 2000 <br />Permit Renewal No. 3 <br />2.04-54 <br />11/1/99 <br />