2010-12-17_REVISION - C1981019 (160)

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reference area. No sensitive species were observed within this type, while the noxious weeds Canada thistle, burdock (Arctium minus), musk thistle (Carduus nutans), and whitetop (Cardaria draba), houndstongue, and mullein (Verbascum thapsus) were all observed in both the study and reference areas. Plates V5 through V8 provide photographic documentation of this community in the study area, as well as the reference area, at the time of sampling. 3.2.1 Bottomland Baseline Study Area Review of Table V4 and Chart V1 indicates that the average vegetation cover of the Bottomland community was 63.07%. Litter and rock provided an average of 24.0% and 0.4% of the ground cover, respectively, while bare ground exposure averaged 12.6%. The dominant plant species were western wheatgrass (Agropyron smithii), Japanese brome (Bromus japonicus), thickspike wheatgrass (Agropyron dasystachyum), cheatgrass (Bromus tectorum), and rubber rabbitbrush (Chrysothamnus nauseosus) with 10.2%, 9.1%, 4.8%, 4.4% and 3.8% of the ground cover, respectively. Perennial plants (excluding noxious weeds) contributed 73% of the total plant cover (46.1% average cover) while annual species and noxious weeds contributed 23.4% and 3.5% of the composition, respectively. Perusal of Table V10 indicates that a total of 7 perennial species contributed at least 3% relative cover or composition (3% is the typical lower limit for plant diversity bond release evaluations). Five of those species were grasses and the remaining two were shrubs. Review of Tables Vi l and Chart V3 indicates that the average herbaceous production of this area in 2005 was 1,515 pounds per acre, oven-dry weight. Eighty-eight percent (1,334 pounds per acre) of the total herbaceous production is attributable to perennials, with grasses contributing 1,153 lbs./acre, forbs providing 135 lbs./acre, and sub-shrubs adding 46 lbs./acre. Twelve percent (180 pounds per acre) of the total production is attributable to annuals, with grasses contributing 141 lbs./acre and forbs providing 40 lbs./acre. Noxious weeds contributed 0.1% or 1 pound per acre to the average herbaceous production. Perusal of Tables V12 and Chart V4 indicates that the estimated woody plant density in this area was 2,315 woody plants per acre. The shrub lifeform accounts for 99% of the total (2,304 plants per acre) with trees contributing 1% of the total (11 plants per acre). Basin big sagebrush (Artemisia tridentata var. tridentata) was the dominant woody species with 699 plants per acre followed by rubber rabbitbrush, mountain snowberry, and silver sage (Artemisia cana) at 516, 441, and 408 shrubs per acre, respectively. • CEImAR C1P IEKASSOMUMS, INC. Page 16 2005 Collom Vegetation Survey