2010-06-28_REVISION - C1981019 (6)

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3.0 RESULTS 3.1 Phase III Summary Tables 1 through 4 contain summary data regarding ground cover species, quantity, and production for all sampled areas. Tables 5 through 7 provide information on woody plant density, and Table 8 demonstrates success testing. In Appendix A, Tables Al through A7 identify vegetation cover, and Tables A8 through A13 show vegetation production for all areas. 3.1.1 2008 Ground cover for 2008 in the Phase III Bond Release area (Table 1 and Chart 1) consisted of 70.8% live vegetation, 0.8% rock, 21.8% litter, and bare ground exposure of 6.6 %. Perennial cover across the unit averaged 65.8% (93.0% relative cover) with annual and biennial cover averaging 5.0% (7.0% relative cover). Dominant taxa were thickspike wheatgrass (Agropyron dasystachyum), cicer milkvetch (Astragalus cicet), crested wheatgrass (Agropyron cristatum), and streambank wheatgrass (Agropyron riparium), with 14.9 %, 10.3 %, 9.5 %, and 6.4% average cover, respectively. With regard to diversity, the Phase III Bond Release Area exhibited 7 perennial grasses with between 3% and 50% relative cover (Table 2). Total relative cover for all forbs excluding noxious weeds in the Phase III area was 23.8 %. Plates 1 and 2 in Appendix A display typical revegetation in the Phase III area for 2008. Table 6 exhibits the results from 45 belt transects collected from the sample area for woody plant density. Perusal of the table reveals that there is an average of 148.4 woody plants per acre in the Phase III bond release area. Current annual herbaceous production across the Phase III area averaged 1910.5 pounds per acre in 2008 with the dominant category being perennial grasses (Table 3). 3.1.2 2009 A total of 53 plant species were observed within the Phase III Bond Release area (all or part of 14 revegetated units) evaluated in 2008 and 2009 combined. These consisted of 24 grass taxa, 27 forbs, and 6 shrubs as indicated on Table Al (Appendix A). Among these species is the occasional noxious weed such as Canada thistle (Cirsium arvense) or invasive weed such as cheatgrass (Bromus tectorum), the latter existing as notable patches. Plates 3 and 4 in the appendix display typical revegetation for the Phase III area for 2009. Ground cover in the Phase III Bond Release area (Table 1 and Chart 1) consisted of 74.6% live vegetation, 0.7% rock, 19.8% litter, and bare soil exposure of 4.9 %. Perennial CEDAR CREEK ASSOCIATES, Inc. Page 15 Rio Tinto Energy America - Colowyo Mine 2009 Phase III Bond Release Evaluation — Year 2