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• water application and the occurrence of rock outcrops or shallow soils. The type usually occurs <br />as small inclusions within the irrigated pasture type, within or adjacent to the Swale/drainage <br />type, or is associated with facilities and disturbed areas. The sagebrush type was delineated <br />based on the dominance of sagebrush within these areas. Some areas mapped as such may <br />occasionaly receive supplemental moisture during the growing season from adjacent agricultural <br />activities, however, a sagebrush overstory with an associated understory of introduced and <br />native species are present along with the irrigated pasture invader species Kentucky bluegrass. <br />Figure 4-6 (Peabody Appendix 10-4) shows one of the larger blocks of this type in the study <br />area. A grazing exclosure is also shown in the photograph. <br />Total vegetation cover (first hit) for the type averaged 37 percent, with bare ground at 29 percent, <br />litter at 30.2 percent, and rock at 3.7 percent (Table 2.04.10-11). Lichen and moss accounted for <br />only 0.1 percent of the mean cover. The shrub component dominated with 13.5 percent cover <br />followed closely by the annual grass component at 12.7 percent cover. Perennial grasses and <br />(orbs at 7.3 and 2.6 percent cover, respectively, followed in importance. Consistent with the type <br />designation, Basin big sagebrush (Artemisia tridentata ssp. tridentata) had the highest perennial <br />• species cover at 11.5 percent (97 percent frequency), while the ubiquitous invader of sagebrush <br />rangelands, cheatgrass (Bromus tectorum) had the highest cover for any species at 12.7 percent <br />(90 percent frequency). Kentucky bluegrass had the third highest cover at 2.7 percent (43 <br />percent frequency) and blue grams (Bouteloua aracilis), crested wheatgrass (Agropyron <br />desertorum), hairy goldenaster (Heterotheca villosa), broom snakeweed (Gutierrezia sarothrae) <br />all had approximately 1 percent cover. The remaining species generally contributed less than <br />one half percent cover to the mean total vegetative cover. <br />Herbaceous production totaled 20.0 g/m2 or 178.4 pounds/acre (Table 2.04.10-12). The <br />perennial grass component contributed the highest value at 13.6 glm (242.4 pounds/acre) <br />followed by perennial (orbs at 5.4 g/m' (96.2 pounds/acre). While the contribution of annual <br />grasses 2 and fortis was low (0.2 and 0.8 g/m2, respectively), their actual contribution to annual <br />production is most likely higher. In order to sample the perennial species at the peak of their <br />production, many of the earlier maturing annual species were senescent or were already gone <br />from the stand. <br />(REVISED BI15/00) 2.04.10 - 40 <br />