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ERO Resources <br />inclusions occur on sideslopes and knolls where soils are shallow and <br />• clayey, yet not rocky to the surface. The parent materials are shales on <br />these sites. Slope is an important, yet secondary influence. The <br />wheatgrass inclusions occur on relatively gentle slopes where the effects <br />of erosion and sheet wash are less severe. Sheet wash contributes to <br />reduced soils moisture regimes through surface sealing by fine clay <br />deposited by the slope wash. Within the wheatgrass patches, particularly <br />on the heavier, more shallow soils where soil erosion is more marked, the <br />dominant plant is Gordon saltbush. This species is a reliable indicator <br />of clay soils (Costello 1944, Cannon 1971) and visually marks those sites <br />on the permit area where shales lie close to the surface. The Gordon <br />saltbush sites are sparse; a condition ostensibly maintained by sheep use <br />and continued erosion. The herbaceous saltbush may provide adequate <br />winter forage for sheep (Costello 1944). <br />Sagebrush -Western Wheatgrass/Annual Forb Complex <br />This upland complex occurs as the direct result of disturbance initiated <br />• by heavy animal traffic. In some areas big game animals also contribute <br />to this feature, as well as sheep. One of the sites that supports this <br />complex was littered with antelope pellets. This site is apparently a <br />watch post for these animals. The conditions produced by this use are <br />perpetuated into a disclimax state by surface erosion and the presence of <br />an abundant and vigorous annual plant seed disseminule. The complex <br />• <br />occurs on fine -textured soils that are not conducive to the establishment <br />of cheatgrass. Heavy animal use is also a deterrent to cheatgrass <br />establishment. High erosion rates at the surface of the annual forb sites <br />contribute more to the damage of existing rhizomatous perennials than to <br />the germination of annual forb seed. The predominant fracturing of the <br />heavy clay soils is apparently favorable to the maintenance of the annual <br />forb population. Cracking of the surface may additionally favor the <br />annual forbs by removing seed from the active erosion surface. <br />II.F-23 <br />