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Total vegetation cover in the portion of the Steep Mountain Brush type to be affected by
<br />mining was 66.1 percent (Appendix 10C, Table lOC-11, while standing dead, litter, bare soil, •
<br />and rock were 0.6, 11.7, 20.0, and 1.3 percents, respectively. By comparison, in the
<br />extended reference area portion of the Steep Mountain Brush vegetation type, total vegetation
<br />cover was 77.5 percent (Appendix 10C, Table tOC-21, while standing dead, litter, bare soil,
<br />and rock were 0.5, 11.2, 9.5, and 1.3 percents, respectively.
<br />Herbaceous biomass production averaged 762 pounds oven-dry per acre in the affected area
<br />(Appendix tOC, Table tOC-31 and 748 pounds oven-dry per acre in the extended reference area
<br />(Appendix 10C, Table 10C-41. In this type, although competing woody cover is less extensive
<br />than in the Mountain Brush type, the herbaceous vegetation is limited by steep slopes and
<br />inherent higher runoff, shallower soils with less moisture and nutrient holding capacities, and
<br />overall greater exposure heating and wind.
<br />Shrub density in the Steep Mountain Brush vegetation type affected area (Appendix 10C, Table
<br />10C-51 averaged 15,031 stems per acre. Major contributing species, in order of abundance,
<br />were mountain snowberry, Gambel's oak, Saskatoon serviceberry, Oregon grape, and big
<br />sagebrush. In the extended reference area (Appendix tOC, Table 10C-61, stem density
<br />averaged 14,173 stems per acre. Major contributors, in order of their numeric abundance were
<br />mountain snowberry, Gambel's oak, Saskatoon serviceberry, and black chokecherry.
<br />Sagebrush/Snow berry Vegetation Type (Photos 25 through 321
<br />
<br />Cover in this vegetation type is also dominated by native shrubs which account for 49.7
<br />percent of total vegetation cover (Appendix 10D, Table 10D-11. The major two contributors by
<br />far are big sagebrush and western snowberry. Occurrence of silver sagebrush /Seriphidium
<br />canum/ is highly local but may be fairly abundant where found. Saskatoon serviceberry and
<br />Douglas rabbitbrush (Chrysorhamnus viscidi//orusl are fairly commonly encountered in the type
<br />but account for little cover. Native perennial cool season grasses are the second most
<br />abundant lifeform, comprising 22.5 percent of total vegetation cover. The largest contributions
<br />to this total came from slender wheatgrass, western wheatgrass, and Agassiz bluegrass, but
<br />substantial portions came from Nelson needlegrass, elk sedge, and mountain brome. Native
<br />perennial (orbs were 17.7 percent of total vegetation cover; the largest contributors to this
<br />total were western yarrow, nettleleaf gianthyssop, timber milkvetch (Astraga/us miser var.
<br />ob/ongifo/ius/, showy daisy, tailcup lupine and common Yampa. Other common species were
<br />arrowleaf balsamroot, showy goldeneye, whiteflower peavine, longleaf phlox, James starwort,
<br />and American vetch. A total of forty-eight species of native perennial forbs were observed in
<br />the affected area samples. Native annual and biennial forbs accounted for 2.4 percent oT total
<br />vegetation cover, most of which was linearleaf collomia and bigfruit willowherb (Epi/obium
<br />brachycarpum/. Most of the 3.8 percent of total vegetation cover accounted for by introduced •
<br />56 Revised 9/98
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