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A total of 18 species were observed in the cover data of which two were <br />• annual grasses, one perennial grass, two annual forbs, twelve perennial forbs <br />and two shrubs. Of these, eight species are considered weedy (Thornton et <br />al., 1974). <br />• <br />• <br />Table 1: Summary of data from the herbaceous reference area at the Orchard <br />Valley Mine. <br />COVER DATA PERCENT <br />Total Vegetation 63.0 <br />Bare Ground o 33.6 <br />Litter and Rock 3.4 <br />Annual Grasses and Forbs 3.4 <br />Perennial Grasses 9.3 <br />Perennial Forbs 60.3 <br />Shrubs and Trees 0.8 <br />PRODUCTION <br />(STANDING CROP BIOMASS) LBS/ACRE <br />Total Vegetation 1488.5 <br />Annuals 86.1 <br />Perennial Grasses 91.4 <br />Perennial Forbs 1311.0 <br />SPECIES DIVERSITY VALUE <br />Number of species observed 18 <br />DISCUSSION <br />The data from the herbaceous reference area clearly demonstrate that the <br />area is naturally weedy. The abundance of thistle, annual grasses and forbs <br />clearly indicate such. However, it appears that this type is naturally weedy <br />and not necessarily caused by man made disturbance. Of course, this area has <br />been grazed by both livestock and wildlife but presumably no more intensely <br />than the surrounding area. It appears that the lack of sfrrubs and trees is <br />due Lo soil factors, particularly the great amounts of clay and silt which <br />shrink and swell, thus causing a continual disturbance over the growing season. <br />Perennial species with taproots such as thistle and yellow sweetclover appear <br />to be favored in such environments over species with fiberous root systems. <br />Similarly, .rn ayaressive rhizomatous yrass such as western wheatgrass can <br />exist on such soils. Annuals are alr~,ays favured on continually disturbed <br />sites. <br />-3- <br />