2010-03-12_REPORT - C1981019 (8)

Home Browse Search

2.2.3 EP043 EP043 is comprised of 13.9 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 30 plant taxa were observed in the unit (see Table AB-1). Current annual production across the unit averaged 1,390.7 pounds per acre in 2009 with perennial grasses and annual grasses the dominant categories (see Compendium 3). Ground cover in EP043 consisted of 67.7% live vegetation, 0.2% rock, 24.7% litter, and bare soil exposure of 7.5% (see Table AB-2 and Chart AB-1). Perennial cover across the unit averaged 48.2% with annual and biennial cover averaging 19.5%. Dominant taxa were Kentucky bluegrass, Japanese brome, streambank wheatgrass, cheatgrass, and cicer milkvetch with 14.5%, 10.8%, 8.6%, 6.7%, and 5.7% average cover, respectively. Woody plant density was determined from 20 belt transects. Density (Table 3) totaled 188 young and mature stems per acre with Wyoming big sagebrush the dominant woody plant. With regard to diversity, EP043 exhibited eight perennial grasses with between 3% and 50% relative cover and relative forb cover of 12.6% (excluding noxious weeds). J ., o } i 0 0_ Shmb .: . 0 0 m ?,O iNstle ® ® m ® 0 m famda 7s CalwvfD Mine-Re.eoetatbn MOneMno Intl. ?oK 20D het BP043 • Swgk wew uu she: 170'k to - This unit readily passes the cover and production bond release comparisons to the reference areas (see Charts 1 and 2). Unit EP043 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 0.58 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 well controlled in this unit, although there are a few scattered patches of Canada thistle. Annual bromes are present with 17.4% cover and should be monitored in coming years. If monitoring reveals expansion, use of the herbicide Plateau is recommended in conjunction with spot reseeding. It is possible this activity could occur as a normal range management practice without resetting the clock. CDRMS would have to be consulted for specific allowances unless such are currently stated in Colowyo's permit. Unit EP043 exhibits good production, diversity, and perennial cover levels for seven-year old revegetation. This unit does not have a large shrub patch component (0.58 acres). However combining this with units with large shrub components for bond release will effect a successful woody plant density comparison. Monitoring and control of the noxious weed and annual brome patches is recommended. CEDAR CREEK ASSOCIATES, Inc. Page 16 Colowyo Mine 2009 Revegetation Monitoring Report