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e ESPEY, HUSTON b ASSOCIATES, INC. • Species Diversity Species diversity is highest for the mountain shrub community with a diversity index of 48.1. Seventy-one species were encountered on thirty transects. Equitability or evenness of cover distribution among species is also highest with an index of 1.29. The higher species diversity and equitability indices for this community may be attributable to a varied shrub stratum and topographic and edaphic vaziability producing vazied habitat for plants. 3.3 VASCULAR PLANT INVENTORY The vegetation of the study site consists of 40 families, 116 genera and 153 species of vasculaz plants: 14 shrubs, 43 graminoids and 97 forbs (see Table K-8). The flora is chazacterized by a diversity of native deciduous shrubs; by numerous perennial, native, cool season mid-grasses with a bunch grass growth • form; and by perennial forbs. None of the plants identified on the study site aze listed on the U.S. Depaztment of Interior's proposed "Endangered and Threatened Species (Plants)," as published in the Federal Register, Wednesday, June 16, 1978. Furthermore, discussions with taxonomists at the Iierbazium, University of Colorado, indicate that threatened and endangered plants aze not likely to occur in the plant community types in the region of the mine plan area. Four plants of the flora aze listed as noxious weeds by Thornton et al. (1974). Two forbs, Canada thistle (Cirsium azvense) and leafy spurge (Euphorbia esula), aze prohibited noxious weeds (especially difficult to control). Fanweed (Thlaspi azvense), another forb,is a restricted noxious weed which can be controlled by cultural practices. Leafy spurge and fanweed are both present in the mountain shrub community, but each had a low cover and frequency. Quackgrass, a wheatgrass, is also cited as a restricted noxious weed. No element of the flora is r 1 ~J K-28