2010-06-28_REVISION - C1981019 (5)

Home Browse Search

3.0 RESULTS 3.1 Phase III Summary 2007 A total of 45 plant species were observed within the Phase III Bond Release area (all or part of 29 revegetated units) evaluated in 2007 (See Plates 1 and 2). These consisted of 17 grass taxa, 14 forbs, and 14 shrubs (see Table A -1 in Appendix A). Table A -1 indicates all taxa observed during fieldwork. Among these taxa is the occasional noxious or invasive weed such as Canada thistle or cheatgrass, the latter existing as notable patches. Ground cover in the Phase III Bond Release area (Table 1 and Chart 1) consisted of 70.0% live vegetation, 0.3% rock, 24.6% litter, and bare soil exposure of 5.2 %. Perennial cover across the unit averaged 67.8% (96.8% relative cover) with annual and biennial cover averaging 2.2% (3.2% relative cover). Dominant taxa were intermediate wheatgrass (Agropyron intermediam), cicer milkvetch (Astragalus cicel), basin wildrye (Elymus cinereus), and crested wheatgrass (Agropyron cristatum) with 24.4 %, 7.6 %, 6.6 %, and 5.9% average cover, respectively. With regard to diversity, the Phase III Bond Release Area exhibited 7 perennial grasses and 2 perennial forbs with between 3% and 50% relative cover. Total relative cover for all perennial forbs in the Phase III area was 15.8 %. Table 6 exhibits the results from 45 belt transects collected at each sample site. Perusal of the table reveals that there is an average of 27.9 woody plants per acre in the Phase III bond release area external to shrub patches. Current annual herbaceous production across the Phase III area averaged 1806.1 pounds per acre in 2007 with perennial grasses the dominant category (see Table 3). 2008 A total of 55 plant species were observed within the Phase III Bond Release area (all or part of 29 revegetated units) evaluated in 2008 (See Plates 3 and 4). These consisted of 22 grass taxa, 19 forbs, 1 sub - shrub, and 14 shrubs as indicated on Table A -1 (Appendix A). Among these species is the occasional noxious weed such as Canada thistle or invasive weed such as cheatgrass, the latter existing as notable patches. Ground cover in the Phase III Bond Release area (Table 1 and Chart 1) consisted of 70.8% live vegetation, 0.5% rock, 24.5% litter, and bare soil exposure of 4.1 %. Perennial cover across the unit averaged 66.5% (93.9% relative cover) with annual and biennial cover averaging 4.3% (6.1% relative cover). Dominant taxa were intermediate wheatgrass, cicer milkvetch, crested wheatgrass, and basin Cedar Creek Associates, Inc. Page 15 Colowyo Mine - Bond Release Evaluation Phase III Year 2