Laserfiche WebLink
Average herbaceous canopy cover was estimated to be 32 percent on the original reference • <br />area and 17.5 percent on the mine study area. Forbs were sparse, contributing an average <br />of 15 and 4.5 percent cover in the reference and mine study areas, respectively. No one <br />species was strongly dominant, but the more frequently encountered species were western <br />yarrow, nettleleaf gianthyssop, American vetch (Vicia americans), and Oregon fleabane <br />(E ri ge ron speciosus). Grasses contributed about 17 percent cover in the reference area <br />and 13 percent in the affected area, also with no single species being dominant. The more <br />frequently encountered species included fowl bluegrass (Poo palustris) and bl uebunch <br />wheatgrass (Agropyron spicatum) on the original reference area and elk sedge and fowl <br />bluegrass on the mine study area. <br />Herbaceous productivity for the original reference area and mine area was 103.1 g/m2 (920 <br />lb/acre) and 109.7 g/m2 (974 16/acre) respectively (Tables 3-17 and 3-18). Herbaceous <br />production data from the Mixed Brush vegetation type show that graminoids provided nearly <br />twice as much annual production as forbs. Kentucky bluegrass and New tlexico bluegrass <br />(Poo tra cyi) provided the bulk of the graminoid production. The four species which <br />provided most of the rest of the graminoid production rvere slender wheatgrass (Agropyron <br />trachycaulum), elk sedge, mountain brome, and basin wildrye (Elymus cinereus). The ~• <br />contribution of the latter was very sporadic but large where it does occur. Among the <br />forbs, perennial native forbs comprised the bulk of the production. Important among the <br />perennial native forbs were western yarrow, nettleleaf gianthyssop, Oregon fleabane, <br />lupines (Lupinus spp.), and common yampa (Peri de ridia gairdneri). <br />Estimated average shrub density on the mine study area was 63.0 stems/SOm2 (5,163 <br />stems/acre); reference area average density was estimated to be 62.5 stems/SOm2 (5,763 <br />stems/acre). Composition and relative density of different species is highly similar <br />between the reference and mine study area samples (Tables 3-19 and 3-20), <br />The number of species sampled in the Mixed Brush type was nearly equal to that of the <br />Aspen type. Shrubs, especially snowberry, contributed the majority of the canopy cover <br />and production in this type. <br />Sagebrush. Tables 4-21 and 4-22 in Appendix 10-4 list cover data tollecteJ in [I+e <br />Sagebrush vegetation type from the mine site and associated reference area. Tables 4-~~ <br />and 4-26 include shrub density data. Tables 4-23 and 4-24 present herbaceous pro ducti++n. • <br /> <br />:: <br />