2008-03-13_REPORT - C1981019 (2)

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2.2.3 EP040 EP040 is comprised of 10.3 acres of moderately sloping revegetation. This unit was seeded in 2003 and therefore, has undergone four growing seasons prior to sampling in 2007. A total of 32 plant taxa were observed in the unit (see Table AB-i). Ground cover in EP040 consisted of 60.8% live vegetation, 0.7% rock, 27.9% litter, and bare soil exposure of 10.7%. Perennial cover across the unit averaged 40.1% with annual and biennial cover averaging a significant 20.7%. The dominant taxa were thickspike wheatgrass, cheatgrass, slender wheatgrass (Agropyron tractiycaulum), Japanese brome (Bromus japonicas), and streambank wheatgrass (Agropyron riparian), with 11.7%, 11.5°10, 9.7%, 9.1%, and 8.3% average cover, respectively. Woody plant density was determined from 15 belt transects. Density (Table 2) totaled 8.1 young and mature stems per acre with mountain snowberry (Symphoricarpos oreophilus) the dominant woody plant. With regard to diversity, EP040 exhibited 4 perennial grass and 0 perennial fortis with between 3% and 50% relative cover. A A p i 0 A IO O ® O't `, • R_ ~+ . ~ canned MraglwYt unit @1 ®. ~; m m Noxious weeds appear to be controlled in this unit, however populations of bull thistle and musk thistle were observed. Annual bromes are present with 20.6% cover and should be monitored in the coming years. If monitoring reveals expansion, use of the herbicide Plateau is recommended in conjunction with spot reseeding. Overall, Unit EP040 should be monitored closely to evaluate if intervention is needed to facilitate progress toward bond release. Rio Tirrto Energy America/Colowyo Mine Page 18 Revegetation Monitoring - 2007 • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • r