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(orbs were Canada thistle with 4.1 percent cover and 100 percent frequency, and dandelion with • <br />3.9 percent cover and 86.7 percent frequency. Alfalfa (Medicaao satival was also moderately <br />common with 1.2 percent cover and 66.7 percent frequency. The dominant native annual /biennial <br />forb was Douglas knotweed with 0.8 percent cover and 60.0 percent frequency. The dominant <br />introduced annual and biennial forb was hound's tongue with 4.2 percent cover and 80.0 percent <br />frequency. <br />Species Comnosi ion - Si~plem n~`•r <br />In the Supplemental Area, cover dominance (Table B6) was also shared by native and introduced <br />graminoids which accounted for 61.8 and 21.1 percent, respectively. Of the native perennial <br />graminoids, Agassiz bluegrass and nodding brome (Bromoosis canadensis ssp. canadensisl were by <br />far the most abundant. Nebraska sedge and Baltic rush were also moderately abundant. Of <br />introduced perennial graminoids, redtop and timothy provided the most cover. Smooth brome and <br />orchard grass were also present in the stand at more than trace levels. Native perennial forts <br />totaled 10.5 percent cover, of which the bulk was provided by Pacific aster and western yarrow. <br />The only introduced perennial forb of any significance in the cover was Canada thistle. <br />Improved Pasture - Upland (Figure 16) • <br />The Improved Pasture -Upland vegetation type is located in the Supplemental Study Area on sites <br />formerly occupied by Sagebrush or Mountain Brush vegetation types. Total cover in the type was <br />observed to be only 36.9 percent (Table B7), compared to 60.8 and 84.4 percent in the Sagebrush <br />and Mountain Brush vegetation types, respectively. Species density was only 11.4 species per 100 <br />sq. m. in the Improved Pasture -Upland type, compared to 27.0 and 27.3 species per 100 sq. m. in <br />the Sagebrush and Mountain Brush vegetation types. Production in the Improved Pasture -Upland <br />vegetation type was not assessed in 1992. Shrubs in this type (primarily big sagebrush) averaged <br />1,918 stems per acre (Table 823). <br />The following discussion describes species dominance in the Improved Pasture -Upland vegetation <br />type based on the allall-ITver Lg~(jyg cover values. All percentages given in the following paragraph <br />refer to this cover statistic. <br />Species Composition - ~pplemental Area <br />Introduced perennial grasses provided the bulk of the vegetation cover (86.6 percent). Of this <br />cover, most was contributed by smooth brome (81.2 percent). Intermediate wheatgrass and <br />timothy were the other species contributing to cover. Native perennial grasses had developed about • <br />3.6 percent cover, primarily comprised of Agassiz bluegrass. Native shrubs (4.0 percent cover) <br />16 <br />