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6.6 Sagebrush - 2 Type (SG-2) The sagebrush -2 vegetation type represents remnants of <br />native rangeland that has not been converted to the more characteristic intensive agricultural <br />land uses in the area. This type occurs on toe slopes of mesa sides with slopes ranging 5 to <br />30 percent. Sagebrush ranged in height 3 ft. to 9 ft. with and average height of 6 ft. <br />Associated with the sagebrush were the shrubs rubber rabbitbrush and four -wing saltbrush. <br />Understory plants are typical of rangeland plants found in the sagebrush -1 type except where <br />irrigation water had run onto the site. In these situations, the understory is dominated with <br />Russian knapweed. <br />Total vegetation cover (first hit) for the type averaged 56 percent, with bare ground at 7.6 <br />percent, litter at 32.8 percent, and rock outcrop and rock fragments at 3.6 percent (Table <br />2.04.10 -24). Lichen and moss accounted for 0.2 percent of the mean cover. The shrub <br />component dominated with 45.4 percent cover and the annual grass component at 6.5 percent <br />cover. Perennial grasses and forbs at 1.6 and 1.6 percent cover, respectively. Consistent with <br />the type designation, Basin big sagebrush ( Artemisia tridentata ssp. tridentata had the highest <br />perennial species cover at 36.9 percent (85 percent frequency), followed by rubber rabbitbrush <br />with cover at 8.5 percent (35 percent frequency) while the ubiquitous invader of sagebrush <br />rangelands, cheatgrass ( Anisantha tectorum had a cover of 6.5 percent (44 percent <br />frequency). Russian knapweed had a cover of 0.2 percent (10 percent frequency) where <br />irrigation runoff was present. The remaining species generally contributed less than one <br />percent cover to the mean total vegetative cover. <br />Total herbaceous production (including shrubs) totaled 138.5 g /m2 or 1236 pounds /acre <br />(Table 2.04.10 -25). Herbaceous production without the shrub component totaled 19.2g/m2 or <br />171 pounds /acre. The perennial shrub component contributed the highest value at 119.3 g/m <br />(1065 pounds /acre) followed by annual grass at 10.2 g /m (91 pounds /acre). While the <br />contribution of perennial grasses and forbs was (2.2 and 6.8 g /m respectively). In order to <br />sample the perennial species at the peak of their production, many of the earlier maturing <br />annual species were senescent or were already gone from the stand. Thus the annual grass <br />production is likely higher than stated. <br />Woody plant density measurements in 1999 differed from 1987 as suffruticose species were <br />not measured consistent with Guidelines for Compliance with Land Use and Vegetation <br />Requirements for Coal Mining. Succulents were also not included in the density calculations. <br />Revised September 2010 (PR 06) 2.04.10 -76 <br />