2010-03-12_REPORT - C1981019 (8)

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2.2.2 EP042 EP042 is comprised of 21.0 acres of moderately sloping revegetation that has a predominately north- easterly aspect. This unit was seeded in 2002 and therefore, has undergone seven growing seasons prior to sampling in 2009. A total of 27 plant taxa were observed in the unit (see Table AB-1). Current annual production across the unit averaged 1,401.8 pounds per acre in 2009 with perennial grasses and annual grasses the dominant categories (see Compendium 2). Ground cover in EP042 consisted of 69.5% live vegetation, 0% rock, 18.2% litter, and bare soil exposure of 12.3%. Perennial cover across the unit averaged 34.7% with annual and biennial cover averaging a notable 34.8% and noxious weed cover of 0.4%. Dominant taxa were cheatgrass, Kentucky bluegrass (Poa pratensis), Japanese brome (Bromus japonicus), thickspike wheatgrass, and Western wheatgrass with 25.7%, 18.7%, 7.8%, 6.1% and 4.4% average cover, respectively. Woody plant density was determined from 20 belt transacts. Density (Table 3) totaled 119.4 young and mature stems per acre with big sagebrush the dominant woody plant. With regard to diversity, EP042 t 0 -ate ® M C. a swne.ed".aghput it CdOW10 Mine - RlMOe2Ibf1 Monitairg • ®' 1 Npl Fps 200 kU .?. EP042 • s.?ct Earn w sa: zm . uv o nco .m uo ? _-_--- exhibited three perennial grasses with between 3% and 50% relative cover and relative forb cover of 2.6% (excluding noxious weeds). This unit readily passes the production bond release comparison to the reference areas but fails the cover comparison (see Charts 1 and 2). Unit EP042 currently passes the bond release diversity standard of 2 perennial grasses with between 3% and 50% relative cover and relative forb cover between 1% and 50% (see Charts 3 and 4). This unit contains 6.98 acres of qualified shrub units which contribute to the woody plant density standard of 150 stems per acre on 3% of the reclaimed land. Shrub patches were delineated using 300 stems per acre as a guideline. Therefore, actual acreage that meets the new standard is presumably higher. Noxious weeds appear to be under control in this unit, however several modest populations of Canada thistle were observed throughout the unit. Annual bromes are present with a substantial 33.5% cover. The use of the herbicide Plateau should be considered in conjunction with spot reseeding to try and improve the amount of perennial cover on this unit. Overall, Unit EP042 should be monitored closely to evaluate if further intervention is needed to facilitate progress toward bond release. In fact, it is recommended that annual qualitative and cover monitoring occur for the next few years to track this unit's progress. Unit EP042 exhibits good production and diversity for seven-year old revegetation. However, the cover values exhibited by this unit can only be considered fair, due to the high annual cover. The annual cover is primarily a result of the shrub seed mix used on this unit, which did not seed enough perennials to compete with the annual brome populations. This unit has a large shrub patch component (6.98 acres) and could be combined with reclamation units without shrub patches to effect a successful woody plant density comparison. Monitoring and control of the noxious weed and annual brome patches is recommended and will allow for perennials to take a stronger hold in this unit. It should also be noted that the vast majority of perennial grass cover in this unit is from seed blown in by the wind from neighboring units. CEDAR CREEK ASSOCIATES, Inc. Page 14 Colowyo Mine 2009 Revegetation Monitoring Report