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species that contributed greater than 1 percent cover. The native perennial forbs that contributed <br />• between 1 and 2.2 percent cover were western yarrow (Achillea lanulosal, spreading aniseroot <br />(Osmorfiiza depauperata), Engelmann aster, nortfiern bedstraw (Galium septentrionale), ballhead <br />valerian (Valerians capitata ssp. acutilobal, and American vetch. The most common introduced <br />species were hound's tongue with 0.8 percent cover and 46.7 percent frequency, smooth brome <br />(Bromopsis inermis) with 0.3 percent cover and 20.0 percent frequency, and salsify (Traaoooaon <br />dubiusl with less than 0.1 percent cover but 53.3 percent frequency. <br />Species Composition -Supplemental Area <br />In the 1992 Supplemental Area, Mountain Brush shrub cover was dominated by Gambel's oak with <br />31.9 percent cover, Saskatoon serviceberry with 10.8 percent cover, and chokecherry with 5.4 <br />percent cover. Mountain snowberry was the only abundant short shrub with 8.3 percent cover. <br />Native perennial graminoids accounted for 32.1 percent cover, while native perennial forbs <br />comprised 9.2 percent of all layer vegetation cover. Introduced perennial grasses accounted for <br />only 0.8 percent cover, while inVoduced perennial forbs were nearly nonexistent with 0.1 percent <br />cover. <br />Sagebrush (Figures 3, 12) <br />• Total top-layer vegetation cover in the Sagebrush vegetation type of the Baseline Area was 67.3 <br />percent (Table A3), bare soil was 9.7 percent, litter cover was 22.9 percent, and no exposed rock <br />was sampled on the transacts: The average species density was 24.7 species per 100 sq.m. The <br />average production estimated for 1990 was found to be 888.6 Ib/acre (Table A9). Baseline Area <br />Sagebrush shrub density averaged 6,087 stems per acre (Table A16). <br />In the Supplemental Study Area (Table 63), the top-layer vegetation cover of the Sagebrush <br />vegetation type in 1992 was 60.8 percent, compared to 67.3 percent cover in the Baseline Study <br />area in 1990. Bare soil was 8.5 percent while litter was 30.4 percent, somewhat higher than in <br />the 1990 sampling of the Baseline Area. Species density was 27.0 species per 100 sq. m. in the <br />Supplemental Area in 1992, compared to 24.7 species per 100 sq. m. in the 1990 Baseline area <br />sampling. Production was not assessed in the Sagebrush vegetation type in 1992. The shrub layer <br />comprised 22.0 percent cover in the Supplemental area, compared to 29.3 percent cover in the <br />Baseline area. Supplemental Study Area shrub density averaged 6,354 stems per acre (Table B20). <br />The following discussion describes species dominance in the Sagebrush vegetation type based on the <br />all-laver relative cover values. All percentages given in the following two paragraphs refer to this <br />• cover statistic. <br />9 <br />