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FRO Rpsources <br />The shrub layer in the juniper -sagebrush communities is relatively diverse <br />• in species composition. Common shrubs include big sagebrush, shadscale, <br />little rabbitbrush, juniper saplings, horsebrush, prickly gilia <br />(LL=todactvlon RutGam), mountain mahogany and low sage (Artemisia <br />arhuscula). Half -shrubs which occur frequently are winterfat, petradoria <br />(Petradoria pumila), snakeweed and prickly pear (Figure 4, Table 7). <br />The tree layer in the juniper -sagebrush stands is open to savannah -like in <br />appearance. Tree densities are significantly reduced as compared to <br />density values in woodland stands. Average densities for Utah juniper are <br />697 mature trees per hectare (Table 8). Many of the trees occurring are <br />small in stature and mean age. Utah juniper was the only tree species <br />encountered. Mean basal cover averages 0.06m. <br />Primary productivity of the juniper -sagebrush communities is greater than <br />that measured in the woodland areas. The affected stands sampled averaged <br />21.2 g/m2. Important grass contributors include Colorado wildrye - 2.3 <br />g/m2, cheatgrass - 2.3 g/m2, beardless bluebunch wheatgrass - 1.6 <br />• g/m2, western wheatgrass - 1.0 g/m2, needle -and -thread grass - 0.7 <br />g/m2 and Indian ricegrass - 0.1 g/m2. Forbs important in production <br />averaged as follows: fleabane - 4.2 g/m2, cryptanthe 1.1 g/m2, <br />prostrate knotweed - 0.9 g/m2, globemallow - 0.7 g/m2 and peppergrass <br />- 0.2 g/m2. The half -shrubs snakeweed and petradoria contributed an <br />average of 2.9 g/m2 and 1.3 g/m2, respectively (Figure 5, Table 9). <br />• <br />.. . - ,,. - <br />The juniper -sagebrush community is a gradient phase demonstrating deeper <br />and finer -textured soils, as compared with the juniper woodlands. The <br />result of the topo-edaphic gradient (Figure 3 and Map 128, Pocket) is <br />displayed by the open tree and shrub canopy and regressing herb layer of <br />this vegetation type. The open nature of the shrub and grass layers in <br />these sites is a relict characteristic. The declining herb layer is the <br />product of overgrazing. Erosion at the surface is notable and past <br />disturbance is readily evidenced by the presence of cheatgrass, annual <br />II.F-30 <br />