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changes to the historic record vegetation community occur, it was anticipated that this <br />period of time would reveal such trends or developmental changes. <br />5.3.1 HRSA Vegetation Cover: 1996-2010 <br />The mean total vegetation cover value for the 2010 quantitative sampling (56.40%) did <br />not vary significantly from the sampling means in 1997 and 1998 (66.80 and 50.67%, <br />respectively). The 2010 total vegetation cover mean was significantly higher than the <br />total vegetation cover mean from 1996 (38.27%). It is hypothesized that this difference, <br />given that the pre-growing season precipitation difference was 0.4 inches, is related to the <br />former impact of livestock grazing at the HRSA. Fencing the HRSA and removal of <br />horses from the area in the intervening years have reduced grazing pressure on the HRSA <br />(being a convenient source for graminoid forage for ungulates and livestock), allowing <br />maturation of the cool season graminoid component in the area. <br />The 2010 total vegetation cover mean is slightly elevated above that of the 1998 total <br />vegetation cover mean when compared to the pre-growing season precipitation totals. It <br />is hypothesized that maturation and more robust development of the adapted native cool <br />season graminoid component has occurred in the intervening time period. Since the last <br />sampling in 1998, the relative cover of the native cool season bunch/sod-forming <br />Agropyron smithii has increased 2,248 percent. Poa pratensis, a more diminutive cool <br />season grass, has decreased in relative cover 37.2 percent since 1998, and 68.6 percent <br />since the initial HRSA sampling in 1996 (Table 7). <br />5.3.2 HRSA Herbaceous Production: 1996-2010 <br />The mean total herbaceous production for the 2010 quantitative sampling (234.80 g/m2) <br />was significantly higher than the sampling means in 1996, 1997, and 1998 (127.71, <br />184.94, and 174.06g/m2, respectively). As with total vegetation cover, it is hypothesized <br />that maturation and more robust development of the adapted native cool season <br />graminoid component has occurred in the intervening time period. As noted with <br />vegetation cover, the greater representation of the robust native cool season bunch/sod- <br />forming Agropyron smithii has increased while the presence of the diminutive Poa <br />pratensis has decreased since the 1990's sampling (Table 7.). <br />5.3.3 HRSA Woody Plant Numbers: 1996-2010 <br />Woody plant numbers have increased 38.7 percent over the period 1996-2010 in the <br />historic record vegetation community. Four species have been present since the census <br />began in 1996, Artemesia tridentata, Chrysothamnus nauseous, Gutierrezia sarothrae, <br />and Symphoricarpos rotundifolius. One new species was encountered in 2010, <br />Amelanchier alnifolia, a common component of the adjacent mountain shrub community. <br />Over the period of sampling the general trend has been for a decrease in the number of <br />Symphoricarpos rotundifolius individuals, likely due to the fact that this species is more <br />successful as an understory species, not typically adapted to open meadows. Further, the <br />life span of this species is not as long as some of the other species encountered. The <br />Mountain Coal Company, LLC Page 9 <br />Historic Record Study Area Vegetation Sampling Report: 2010