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

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RULE 2 PERMITS Five sub -types of the Bottomland community were identified (Wetland, Mountain Shrub, Sagebrush, Riparian Bottom, and Grassland) during the field vegetation verification studies and are described below. • The wetland subtype, owing to its disproportionate importance as a habitat, as well as jurisdiction by the U.S. Army Corps of Engineers under the Clean Water Act, is fully described below in this permit as a paraphrased section from the Wetland Delineation submitted to the Corps. • The mountain shrub subtype is simply described as invasions from upland sites into the numerous concave basins of the various headwater drainages throughout the study area. These invaded areas exhibit an identical character and ecological attributes as is described for the larger community presented below. • The sagebrush and grassland sub -types generally occupy the relatively flat floodplain terraces extending from the toe of the adjacent slopes to the creek channel or wetland. If recent burning or sagebrush removal has occurred, the area has been designated as grassland. These areas are variably dominated by perennial wheatgrass species (Agropyron sp.), Great Basin wildrye (Elymus cinereus) (at higher elevations), or annual bromes with occasional sagebrush or rabbitbrush reinvasion. The grasslands in the Bottomland community differ from upland Grassland communities in that they exhibit substantially higher production and cover values due to the increase in soil moisture levels. The sagebrush sub -type is visually dominated by basin big sagebrush with lower densities of rubber rabbitbrush, mountain snowberry and silver sage. The recent drought along with channel "down- cutting" has reduced the alluvial water table, which appears to have contributed to a substantial die -off of basin big sagebrush on the terraces, most notably in the Wilson Creek drainage. • The riparian bottomland sub -type is highly variable and scattered and includes the linear channel banks adjacent to the streamside and expanded streamside wetlands where an overstory of boxelder (Ater negundo) is often present. A total of 92 plant species were observed within the bottomland community baseline study area (excluding the wetland subtype), while the reference area exhibited 39 taxa. The noxious weeds observed in both the study area and reference area were Canada thistle, burdock (Arctium minus), musk thistle (Carduus nutans), whitetop (Cardaria draba), houndstongue, and mullein (Verbascum thapsus). No sensitive species were observed (Table 2.04.10 -34). The average ground cover within the bottomland community baseline study area was 63.07 percent, with 0.42 percent rock, 23.96 percent litter, and 12.56 percent bare ground exposure. Dominant plant species and their ground cover percentage included: western wheatgrass (Agropyron smithii) (10.24 percent), Japanese brome (Bromus japonicus) (9.09 percent), thickspike wheatgrass (Agropyron dasystachyum) (4.8 percent), cheatgrass (Bromus tectorum) (4.38 percent), and rubber rabbitbrush (Chrysothamnus auseosus) (3.82 percent). Of the total plant cover 73 percent (46.1 percent average cover) was comprised of perennial plants (excluding noxious weeds). Annual species contributed 23.4 percent and noxious weeds 3.5 percent of the composition. Seven perennial species contributed at least 3 percent relative cover or composition, with five of those species being grasses and the remaining two were shrubs (Table 2.04.10 -46). The average herbaceous production in the bottomland community baseline study area was 1,515 pounds per acre, oven -dry weight, with 88 percent (1,334 pounds per acre) due to perennials (grasses contributing 1,153 pounds per acre, forbs contributing 135 pounds per acre, and sub - shrubs contributing 46 pounds per acre) and 12 percent (180 pounds per acre) due to annuals (grasses contributing 141 pounds per acre and forbs contributing 40 pounds per acre). The remaining 0.1 percent (one pound per acre) is attributed to noxious weeds (Table 2.04.10 -47). Cullom — Rule 2, Page 63 Revision Date: 9/28/11 Revision No.: PR -03