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2.2.6 EP046 <br />EP046 is comprised of 106.6 acres of <br />moderately sloping revegetation that has a <br />predominately north-easterly aspect. This unit was <br />seeded in 2005 and therefore, has undergone two <br />growing seasons prior to sampling in 2007. A total <br />of 26 plant taxa were observed in the unit (see Table <br />AB-1). Ground cover in EP046 consisted of 57.4% <br />live vegetation, 0.7% rock, 16.7% litter, and bare <br />soil exposure of 25.2%. Perennial cover across the <br />unit averaged 23.8% with annual and biennial cover <br />averaging a significant 33.6%. The dominant taxa <br />were cheatgrass, thickspike wheatgrass, mountain <br />brome (Bromus marginatus), Russian thistle (Sa/so/a <br />austra/is), and Kentucky bluegrass with 20.7%, <br />6.7%, 6.0%, 5.4%, and 5.1% average cover, <br />respectively. Woody plant density was determined <br />from 15 belt transects. Density (Table 2) totaled <br />43.2 young and mature stems per acre with <br />mountain snowberry the dominant woody plant. <br />With regard to diversity, EP046 exhibited 4 perennial <br />grasses and 0 perennial fortis with between 3% and <br />50% relative cover. <br />i <br />~ ~` <br />-- f~ r <br />Unada thkd~ <br />O A ~~ <br />~. <br />~~ <br />0 ~ ~ <br />~. <br />~'' <br />' A A 0,' <br />r. <br />® ® ® - <br />® m <br />• <br />Noxious weeds appear to be controlled in this unit, however populations of Canada thistle were <br />observed. Annual bromes are present with a substantial 20.7% cover and should be monitored in the <br />coming years. If monitoring reveals expansion, use of the herbicide Plateau is recommended in <br />conjunction with spot reseeding. Overall, Unit EP046 should be monitored closely to evaluate if <br />intervention is needed to facilitate progress toward bond release. <br />Rio Tinto Energy America/Colowyo Mine Page 24 Revegetation Monitoring - 2007 <br />