2013-04-10_PERMIT FILE - C1981019A (4)

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RULE 2 PERMITS Woody plant density in the bottomland community baseline study area was 2,315 woody plants per acre with dominance by basin big sagebrush (Artemisia tridentata) (699 plants per acre), rubber rabbitbrush (516 shrubs per acre), mountain snowberry (441 shrubs per acre), and silver sage (Artemisia cana) (408 shrubs per acre). The shrub lifeform accounts for 99 percent (2,304 plants per acre) and trees account for 1 percent (11 plants per acre) of the total (Table 2.04.10 -48). The reference area is located in an area that exhibits "die-off' of sagebrush. It is anticipated that sage reinvasion will occur over the next several years. In the bottomland reference area, average ground cover was 64.2 percent, with 0.5 percent rock, 31.65 percent litter, and 3.65 percent bare ground exposure. Dominant plant species and their ground cover percentage included: cheatgrass (27.3 percent), western wheatgrass (9.6 percent), Sandberg bluegrass (Poa secunda) (7.45 percent), basin wildrye (Elymus cinereus) (4.55 percent), and thickspike wheatgrass (3.15 percent). Of the total plant cover, 56 percent (35.8 percent average cover) was comprised of perennial plants (excluding noxious weeds). Annual species contributed 44 percent and noxious weeds contributed 0.0 percent of the composition. Four perennial species contributed at least 3 percent relative cover or composition, with all four of those species being grasses (Table 2.04.10 -46). The average herbaceous production in the bottomland reference area was 1,696 pounds per acre, oven -dry weight, with 66 percent (1,114 pounds per acre) due to perennials (grasses contributing 1,113 pounds per acre and forbs providing 1 pound per acre) and 34 percent (582 pounds per acre) due to annuals (grasses contributing 578 pounds per acre and forbs contributing 5 pounds per acre). Noxious weeds were not found in any of the sampling quadrats in the bottomland community, but were observed in the area (Table 2.04.10 -49). Woody plant density in the bottomland reference area was 540 plants per acre with dominance by rubber rabbitbrush (221 plants per acre) and basin big sagebrush (198 plants per acre). The shrub lifeform accounted for 100 percent of the total (Table 2.04.10 -50). The comparison of the calculated t- statistic (t *) for the bottomland community baseline study area and the bottomland reference area with the respective tabular t values indicates that in each case t* is less than t. So, it can be concluded that the total vegetation ground cover and production for the bottomland community baseline study area is comparable (equal) to the values obtained from the bottomland reference area (Table 2.04.10 -38). Grassland - The grassland community baseline study area occupies 816 acres (Map 4C). It is predominately an early -seral community found in the flat uplands where natural and prescribed burns have removed the sagebrush or mountain shrub overstory vegetation and the usually sub - dominant grasses have flourished. Small patches of the grassland community can be found along high elevation ridges and summit where thin soils and high winds have inhibited shrub densities. The grassland reference site is located in the northern uplands on the bench between Collom and Morgan Creeks and occupies 27.7 acres (Map 4C). It appears that the reference area was subject to a prescribed burn approximately 1 to 2 decades prior to sampling and re- invasion of sagebrush has been generally slow compared with burned areas at higher elevations. The reference area was selected because of its easy access, low probability of future disturbance, and representative grassland characteristics. It is unlikely to see extensive sagebrush re- invasion in the immediate future. A total of 93 plant species were observed within the grassland community baseline study area while the reference area exhibited 26 taxa. No sensitive species w -'re observed within the study area. Noxious weeds, Canada thistle, musk thistle, whitetop, and bindweed (Convolvulus ar mnsis) were observed in the study area (Table 2.04.10 -34). Collom — Rule 2, Page 64 Revision Date: 9/28/11 Revision No.: PR -03