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• <br />• <br />ERO Resources <br />Vegetation types dominated by cheatgrass and annual forbs occur throughout <br />the permit area. The cheatgrass-annual forb type is the result of surface <br />disturbance on sites underlain by loamy to more coarse textured soils <br />(Table 4). Cheatgrass has invaded these areas following overgrazing and <br />other severe damages to surface soils. The cheatgrass is maintained on <br />areas it has invaded where grazing pressures are not extreme. This winter <br />annual is capable of high utilization of surface moisture and continuous <br />seed production and germination (Hulbert 1955, Harris 1967 and Young et <br />al. 1979), but is not notably tolerant of overgrazing (Dauberaire 1942). <br />The annual forbs characteristic of some areas in this vegetation type <br />occur as the result of lowered competition with perennials due to <br />declining soil and nutrient cycling conditions. This type accounts for <br />17.6 acres of the total affected area (Table 5). <br />may LE <br />.. .... . , <br />The ground cover values for the Cheatgrass-Annual Forb sites sampled are <br />summarized in Figure 4 and Table 6. The average values are lichens and <br />mosses - 1.9%, litter - 29%, soil - 68.2% and woody species - 0.2%. <br />The herbaceous layer in the vegetation type is dominated by cheatgrass and <br />western wheatgrass with mean cover values of <0.1% and 0.1%, <br />respectively. Total mean cover in this type is 0.1%. This is the lowest <br />cover by herbaceous species of all vegetation types sampled. Western <br />wheatgrass, a rhizomatous grass species, has declined due to surface <br />disturbance in this type. Squirreltail grass is the only other grass <br />species present with a cover value of <0.1%. Forbs that are encountered <br />in some frequency are African mustard and plantain (Plantago purshii), <br />both with cover values of less than 0.1% (Figure 4, Table 6). It can be <br />readily seen that western wheatgrass has declined in importance in the <br />cheatgrass-annual forb types that this species once dominated. It is also <br />II.F-46 <br />