2016-12-23_PERMIT FILE - C1982056A (8)

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Total shrub stratum variables averaged 39.8% ground cover, 148.80 g/m2 0 328 Ib/acre) production, and a density • of 6,335.7 shrubs or stems per acre. Herbaceous stratum variables averaged 31.0% ground cover by grasses and 10.6% ground cover by forbs, 53.60 g/1112 (478 lbs/acre) production by grasses and 27.58 g/1112 (228 lbs/acre) production by forbs. The mountain brush vegetation type's overall variables are 81.4% vegetative ground cover, 229.98 g/1112 (2,052 lbs/acre) production, and 6,335.7 shrubs per acre for woody plant density. The diversity index as calculated by Shannon et al. (1973) for the entire community exhibits a value of 1.3243. Mountain shrub vegetation type variables as presented above were determined from statistically adequate sampling. Sample parameters for each variable, and the minimum sample size required for an adequate sample are presented in Table 27, Summary of Statistical Information. Based on data obtained in this study the carrying capacity of the mountain shrub community within the proposed permit area is 1.03 AUMS/acre. Pasture The pasture vegetation type exists only as a relatively small area within the south-central portion of the permit area immediately south of the east half of old Mine No. 2. This area was historically dominated by the sagebrush vegetation type. The pasture vegetation type currently occupies 6.4 percent of the proposed permit area or 839 acres. No surface facilities or other disturbance due to mining will occur within this community. As identified on Table 24, Vegetation -Soil Correlation, and Table 33, Characteristics of Soils underlying the Cropland and Pasture Vegetation Types, several soils are found below the pasturelands of the proposed permit area. A discussion of these soils has been presented under the portion of this section entitled Cropland. • As identified on Table 36, Pasture Vegetation Type, the community is overwhelmingly dominated by smooth brome which exhibits 80.2% ground cover and 339.98 g/1112 (3,033 lbs/acre) production. The pasture vegetation type's overall variables are 85.2% vegetative ground cover and 339.98 g/n12 (3,033 lbs/acre) production. The diversity index as calculated by Shannon et aL (1973) for the entire community exhibits a low value of 0.1292. Pasture vegetation type variables as presented above were determined from statistically adequate sampling. Sample parameters for each variable, and the minimum sample size required for an adequate sample are presented in Table 27, Summary of Statistical Information. Additional sampling data for the Pastureland Reference Area is presented in Exhibit 41, Pastureland Reference Area Sampling Data. Based on data obtained in this study the carrying capacity of the pasture community within the proposed permit area is 1.52 AUMS/acre. Aspen The aspen vegetation type is one of the more visually dominant communities in the foothills and mountains surrounding Twentymile Park. However, within the proposed permit area it is rare, occurring in very small and isolated stands. These small isolated stands occupy only 54.5 acres or 0.4 percent of the proposed permit area. No surface facilities or other disturbance due to mining will occur within this community. Because of the lack of planned disturbance of the aspen vegetation type, a reference area is not necessary. As identified in Table 24, Vegetation -Soil Correlation, and Table 37, Characteristics of Soils Underlying the •Aspen Vegetation Type, only one soil (Coutis fine sandy loam) is found beneath the community. This soil is deep and excessively drained and has developed from sandstone parent material. The permeability and available water capacity of this soil are both moderate, and the land capability subclass is Vle (see land use discussion under Rule 2.04.3 for further information regarding land capability subclasses). NIR 97-154 2.04-59 Revised 10/02/97