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ERO Resources <br />C J <br />g. COLORADO WILORYE TYPE <br />il) Location and Distribution: <br />Vegetation types dominated by extensive swards of Colorado wildrye and an <br />open shrub layer occur on west- and southwest-facing steppes (Table 4). <br />These bunchgrass slopes and terraces occur above the drainages in areas <br />where major gulch development has occurred. Exposure and soil are the <br />controlling factors in the formation and persistence of this vegetation <br />type. Soils on the sites are shallow and coarse and subject to erosion <br />from run-off. This type occurs on 5.3 acres of the total affected area <br />(Table 5). The Colorado wildrye is well-adapted to the conditions of the <br />steppes. The characteristic ecological amplitude of this species has been <br />previously discussed in detail. The open and scattered arrangement of <br />shrubs on these slopes tends to follow fractures and rock rubble on the <br />benches. In these places water is more available at depth from <br />fractures. Some of this water may be perched and soma pooled at the <br />meeting of convergent lineations. Additional moisture is also supplied <br />• via slope run-off. This run-off tends to slow when moving over the <br />benches and is partially infiltrated into the surface at this time. <br />f21 Structure and Cemnoeit ion; <br /> <br />Ground cover values for the Colorado wildrye sites sailed are summarized <br />in Figure 4, Table 6. The average mean values for stards sampled are <br />lichens and mosses - 0.3X, litter - 14.3X, rock - 27.9X, soil - 49.1X and <br />woody spec le6 - 7.6X, <br />The herb layer of the wildrye type is open and sparsely vegetated with a <br />mean herb cover of 8.9X. The configuration produced on the exposed <br />steppes is a scattering of large swards of wildrye separated by open soil <br />and rock areas. The interstitial spaces support a limited growth of other <br />grasses and fortis. Cover values for the dominant wildrye averaged 6.3X in <br />the affected stands sampled. Cheatgrass has a mean cover of 0.9X. Other <br />important grasses are squirreltail grass - 0.3X, Indian ricegrass - 0.2X <br />II.F-43 <br />