2010-12-17_REVISION - C1981019 (106)

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RULE 2 PERMITS Woody plant density in the grassland reference area was 348 woody plants per acre with dominance by low rabbitbrush (201 plants per acre) and mountain big sagebrush (136 plants per acre). The shrub lifeform accounts for 100 percent of the total (Table 2.04.10 -55). The comparison of the calculated t- statistic (t *) for the grassland community baseline study area and the grassland 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 grassland community baseline study area is comparable (equal) to the values obtained from the grassland reference area (Table 2.04.10 -38). Juniper Scrub - The juniper scrub community baseline study area occupies 580.1 acres and is located on the steeper slopes in the drier, rockier, and skeletal soil covered northern portions of the study area (Map 4C). The juniper scrub reference area site is located just north of the study area boundary on a low rolling mesa top and adjacent west - facing moderately steep slope and occupies 77.9 acres (Map 4C). This reference area was selected because of limited extent of the community in the vicinity of the study area, reasonable access, low probability of future disturbance, and the representative combination of two aspects that is similar to a majority of the area delineated as Juniper Scrub. The juniper scrub community is dominated by a juniper overstory with assorted shrubs, grasses, and forbs occupying the areas understory. Most of the community is located on steep, relatively barren and erodable soils along the drier, northern edge of the study area. A small portion of this community can be found on the flat tops on the slopes where it intergrades into the sagebrush dominated uplands. The juniper trees appear healthy and are expanding into both the mesic and xeric sagebrush areas that are adjacent to this community type. A total of 77 plant species were observed within the juniper scrub community baseline study area while the reference area exhibited 51 taxa. No sensitive species were observed. The noxious weeds musk thistle and houndstongue were observed (Table 2.04.10 -34). The average ground cover within the juniper scrub baseline study area was 34.69 percent, with 14.88 percent rock, 19.97 percent litter, and 30.47 percent bare ground exposure. Dominant plant species and their ground cover percentage included: Wyoming big sagebrush (Artemisia tridentata spp. wyomingensis) (6.56 percent), Griffith's wheatgrass (Elytrigia albicans) (3.88 percent), cheatgrass (3.81 percent), Sandberg bluegrass (2.53 percent), and western wheatgrass (2.09 percent). Of the total plant cover, 83 percent (28.81 percent average cover) was due to perennial plants (excluding noxious weeds). Annual species contributed 17 percent and noxious weeds 0.0 percent of the composition. Six perennial species contributed 3 percent relative cover or composition (3 percent is the typical lower limit for plant diversity bond release evaluations), with five of those species being grasses and one shrub (Table 2.04.10- 56). The average herbaceous production within the juniper scrub baseline study area was determined to be 213 pounds per acre, oven -dry weight, with 90 percent (192 pound per acre) due to perennials (grasses contributing 152 pounds per acre, forbs contributing 35 pounds per acre, and sub - shrubs contributing 5 pounds per acre) and 10 percent (20 pounds per acre) due to annuals (grasses contributing 13 pounds per acre and forbs contributing 8 pounds per acre). The remaining 0.1 percent (0.3 pounds per acre) was due to noxious weeds (Table 2.04.10 -57). Woody plant density was 2,395 plants per acre with dominance by Wyoming big sagebrush (817 plants per acre), mountain big sagebrush (355 plants per acre), and mountain snowberry (340 plants per acre). The shrub lifeform accounts for 90 percent (2,168 plants per acre), sub -trees account for 3 percent (65 plants per acre) and trees account for 7 percent (163 plants per acre) of the total (Table 2.04.10 -58) . Collom — Rule 2, Page 65 Revision Date: 1/23/09 Revision No.: PR -03