2008-03-13_REPORT - C1981019 (2)

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2.5 Reference Areas 2.5.1 Mountain Shrub Reference Area The Mountain Shrub Reference Area is comprised of approximately 18 acres of gently to moderately sloping vegetation that has a predominately northwesterly aipect (mesic) and easterly aspect (xeric) (see Plate 1). The Mountain Shrub Reference Area was expanded in 2005 to include the east- facing slope of the ridge to provide representation from the xeric subtype of Mountain Shrub. The purpose of this inclusion is to provide a better representation of the distribution of Mountain Shrub communities located on and around Colowyo properties. The xeric exposure tends to exhibit more elevated herbaceous parameters given a modest reduction in the overstory. This reference area is located on a ridge west of the West Pit Area (see Map 1). A total of 35 plant taxa were observed in this reference area (see Table AB-1). Current annual herbaceous production across the area averaged 717.5 pounds per acre in 2007 with perennial grasses the dominant category (see Table 1). Ground cover in the Mountain Shrub Reference Area (Table 8) i consisted of 56.4% live vegetation, 0.7% rock, 33.6% litter, and bare soil exposure of 9.4%. Perennial cover across the unit averaged 51.4% with, annual and biennial cover averaging 5.0%. Dominant taxa were Mountain big sagebrush, bluegrass (Poa agasizensis), slender wheatgrass, Nelson's needlegrass (Stipa ne/sonic), and cheatgrass with 11.3%, 7.8%, 6.3%, 5.4%, and 4.6% average cover, respectively. With regard to diversity, the Mountain Shrub Reference Area exhibited 6 perennial grasses and no perennial fortis with between 3% and 50% relative cover. i 2.5.2 Sagebrush Reference Area The Sagebrush Reference Area is comprised of approximately 47 acres of gently to moderately sloping vegetation that has a predominately northerly aspect (see Plate 2). This reference area is located on a gently sloping ridge north of the Administration /Facilities Area (see Map 1). A total of 46 plant taxa were observed in this reference area (see Table AB-1). Current annual herbaceous production across the area averaged 588.1 pounds per acre in 2007 with perennial grasses the dominant category (see Table 1). Ground cover in the Sagebrush Reference Area (Table 8) consisted of 57.3% live vegetation, 3.0% rock, 29.0% litter, and bare soil exposure of 10.8%. ~ Perennial cover across the unit averaged 42.0% with annual and biennial cover averaging 15.3%. Domi i ant taxa were Japanese brome, Mountain big sagebrush, Sandberg's bluegrass (Poa secunda), western w eatgrass, and prairie junegrass Rio Tinto Energy America/Colowyo Mine Page 34 Revegetation Monitoring - 2007 • • • • t • • • • • • • • • • • • • • r • • • • • • • • • • • • • r • • •