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were mostly either mountain sagebrush or big sagebrush. Native perennial (orbs were numerous <br />• but cumulatively provided only 2.9 percent cover. Although cover in this vegetation type was very <br />low, the openness was not accompanied by abundant development of weedy annuals; introduced and <br />native annual and biennial forbs combined amounted to only 0.7 percent of total vegetation cover. <br />This condition is typical of older, often sod-bound smooth brome plantings. <br />Steep Mountain Brush Vegetation Type (Figures 8 and 17) <br />Duantitative sampling of this vegetation type took place in 1992 across the combined Baseline and <br />Supplemental Areas. In areas mapped as Steep Mountain Brush, the underlying slopes were 2 to <br />3(h):1(v) or steeper. These steep sites often correspond with the presence of underlying resistant <br />geologic material, usually sandstone. When these steep slopes are north- to east-facing, a dense <br />cover of Gambel's oak and serviceberry, usually of substantially reduced stature, with an elk sedge <br />understory, is typically present. <br />Primarily occurring on south- to west-facing slopes, the cover (compared to Mountain Brush) was <br />much more open with relatively little development of Gambel's oak; when oak was present it was <br />usually dwarfed in stature. Soils on these sites were shallow and droughty and the vegetation <br />reflects this lack of soil moisture. Vegetation cover in general was less than the Mountain Brush <br />• vegetation type, but Gambel's oak and Saskatoon serviceberry were still the dominant species. <br />Mountain mahogany (Cercocarous montanusl and bitterbrush (Purshia tridentatal although not <br />abundant over the entire type, were locally abundant. <br />Total top layer vegetation cover was 52.3 percent, while bare soil, litter, and rock cover amounted <br />to 19.9, 23.3, and 4.5 percent (Table B6), respectively. Species density was 23.1 species per <br />100 sq. m. Herbaceous production was observed to be only 352 Ibs per acre (Table B73) in 1992 <br />sampling, consistent with the sparse appearance of the understory. Shrub density averaged 13,404 <br />stems per acre (Table B24), most of which was Saskatoon serviceberry, Gambel's oak, and <br />mountain snowberry. <br />The following discussion describes species dominance in the Steep Mountain Brush vegetation type <br />based on the atl-layer relative cover values. All percentages given in the following paragraph refer <br />to this cover statistic. <br />By far the most abundant lifeform in this vegetation type was shrubs, accounting for 67.5 percent <br />• of cover. Nearly all of this cover was provided by Gambel's oak, Saskatoon serviceberry, mountain <br />17 <br />