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ERO Resources <br />shrub cover for this community is 25,4X, Of this value 85% of the total <br />• cover is made up of big sagebrush and rabbitbrush. Other shrubs of <br />importance are snowberry - 1.9X, greasewood - 1.4X, shadsoale - 0.2X and <br />wood rose - 0,1X (Figure 4, Table 63. In terms of mean density <br />rabbitbrush has the largest value of 12,975 shrubs per hectare. Following <br />rabbitbrush in order are big sagebrush - 6293/Ha, snowberry - 2937/Ha, <br />greasewcod - 418lHa, shadscale - 243Ma and wood rose 22S/Ha iTabl• 7), <br />i <br />Mean primary productivity in the big sagebrush-greasewood type is the <br />largest of any vegetation type in the permit area at 60.6 g/m2. <br />Important grasses with their mean production values are quackgrass - 18.5 <br />g/m2, cheatgrass - 15.1 g/m2, saltgrass - 5.0 g/m2, Colorado wildrye <br />- 3.3 g/m2, western wheatgrass - 2.9 g/m2, Indian ricegrass - 0.4 <br />g/m2, Sandberg bluegrass - 0.4 g/m2 and needle-and-thread grass - 0.2 <br />g/m2. Grasses as a whole are the most inQortant contributors to primary <br />production making up 78X of the total biomass. Perennial forbs averaged <br />11.3 glm2 in this type. Important perennial forbs include fleabane <br />daisy, long-leaf phlox and globemallow (Figure 5, Table 9). <br />• <br />13) Succession and Land Use; <br />The big sagebrush-greasewood type is a topo-edaphio complex. This <br />vegetation type maintains an essential balance with the environmental <br />factors that predominate. Primary factors iralude soil depth, texture and <br />chemistry. The type is also influenced cyclically by heavy run-off and <br />peak flows. These effects provide the higher levels of soil moisture <br />during parts of the year that aid in the maintenance of the shrub layer. <br />The herb layer adjusts cyclically to the erosion, so that there is some <br />continuous reirnasion of the stream channels that cut through the type. <br />In marry places, however, the stream courses have exposed bed rock <br />materials. <br />The effects of grazing have apparently not caused extreme degradation in <br />the big sagebrush-greasewood type. Some surface disturbance has occurred, <br />as evidenced by the presence of cheatgrass and annual forbs. The <br />J <br />II.F-50 <br />