2009-03-27_REPORT - C1981019 (7)

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2.4 West Pit 2.4.1 WP009 WP009 is comprised of less than 0.9 acres of gently sloping revegetation that has predominately a northerly aspect. This unit was seeded in 2001 and therefore, has undergone seven growing seasons prior to sampling in 2008. As indicated on the map to right, ' an area of re-disturbance (including and parallel to the centerline road extending along the long axis of the 'm unit) has occurred. This re-disturbed area is m revegetating on its own given invasion from the surrounding area. A total of 39 plant taxa were m observed in the unit (see Table AB-1). Current annual P m c production across the unit averaged 1,890.3 pounds m m °i per acre in 2008 with perennial grasses the dommant category (see Compendium 5). Ground cover in m m ° ° WP009 consisted of 67.2% live vegetation, 0.3% rock, m a.. ° 27.2% litter, and bare soil exposure of 5.4%. ° U Perennial cover across the unit averaged 46.3% with a ° annual and biennial cover averaging 20.9% and noxious weeds 0.2% cover. The dominant taxa were thickspike wheatgrass, Japanese brome (Bromus japonicus), crested wheatgrass, cheatgrass, and western wheatgrass, with 11.0%, 8.2%, 7.3%, 7.0%, k-vn and 5.1 average cover, respectively. Woody plant WPM •-°-?- ??- density was determined by a total count. Density (Table 2) totaled 219 young and mature stems per acre with Gambel Oak (Quercus gan7beiii) the dominant woody plant. With regard to diversity, WP009 exhibited 7 perennial grasses and 0 perennial forbs with between 3% and 50% relative cover. Unit WP009 currently fails the bond release diversity standard of 3 perennial grasses and 1 perennial forb with between 3% and 50% relative cover (see Chart 6). The unit does not exhibit a dominant forb. This unit easily passes both the cover and production bond release comparisons to the reference areas (see Charts 3 and 4). This unit does not presently meet the woody plant density standard of 90% of 1000 stems per acre and will probably not meet this in the foreseeable future due to the heavy competitive grass cover. See Appendix AA - Section 7.3 for a discussion on options and recommendations with regard to woody plant density. Noxious weeds were not observed in this unit. There is an occasional small patch of annual bromes within the unit. Although these bromes currently represent 15.2% cover, according to monitoring presented on Compendium 5 the populations appear to be shrinking with increased completion from perennial grasses. At present, WP009 is a good example of an improved pasture grassland community, despite its small size, that would contribute to the local system as both cover and foraging habitat for wildlife (especially elk), as well as provide a variety of management opportunities for livestock grazing. Rio Tinto Energy America/Colovdyo Mine Page 20 Revegetation Monitoring - 2008