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Mountain Brush (Figure 2, 11) <br />Total top layer vegetation cover in the Mountain Brush vegetation type of the Baseline Area was <br />82.3 percent (Table A2), bare soil was 4.7 percent, litter cover was 12.8 percent, and rock was <br />0.3 percent. The average species density was 27.9 species per 100 sq.m. The average production <br />estimated for 1990 was found to be 760.1 Ib/acre (Table A8). Woody plant density in the Baseline <br />Area averaged 11,121 stems per acre (Table A15). <br />In the Supplemental Study Area, total top layer vegetation cover was 84.4 percent (Table 82), <br />while bare soil was 0.3 percent, and litter was 15.3 percent. Species density was 27.3 species per <br />100 sq.m., very similar to the level found in the Baseline Area in 1990. Production was not <br />assessed in the Mountain Brush Vegetation Type in 1992. Shrubs in the top layer comprised 63.9 <br />percent cover, compared to 66.1 percent in the Baseline Area; relative all-laver cover by shrubs <br />in the Supplemental Area averaged 56.7 percent compared to 63.2 percent in the Baseline Area. <br />Woody plant density averaged 12,562 stems per acre (Table 619). <br />The following three paragraphs describe species dominance in the Mountain Brush vegetation type <br />based on the all-laver relative cover values. All percentages given in the following paragraph refer <br />to this cover statistic. <br />The shrubs were slightly less dominant when evaluated with respect to the relative all-layer cover <br />(63.2 percent of total all-layer vegetation cover). Native perennial grasses provided 20.5 percent <br />of total all-layer vegetation cover and native perennial (orbs contributed 14.8 percent of total all- <br />layer vegetation cover. These last two growth forms, especially the native perennial forts, <br />contributed most of the diversity found in this vegetation type. InVOduced forts and grasses <br />comprised only a small part of any of the cover estimates. Even when the cover conVibutions from <br />each were combined, the total for any of the cover estimates was less than 1 percent. The native <br />annual and biennial (orbs also contributed less than 1 percent to any of the cover estimates, but <br />were commonly present (80 percent frequency). <br />The dominant tall shrubs were Gambel's oak with 32.5 percent cover, Saskatoon serviceberry with <br />14.3 percent cover, and chokecherry with 4.9 percent cover. Mountain snowberry was the <br />dominant short shrub with 10 percent cover. The combined native perennial grasses and (orbs <br />contributed 35.3 percent cover. Elk sedge with 10.8 percent cover, slender wheatgrass (Elymus <br /> <br />trachy~aulus ssp, trac ycaulusl with 1.1 percent cover, blue wildrye with 2.6 percent cover and <br />Agassiz bluegrass with 4.5 percent cover, were the only native perennial grass or grass-like <br />8 <br />