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Twenty Mile Mine Amendment - Baseline Vegetation Study Plan <br />1.1.1 Sagebrush Upland <br />This vegetation community is an upland rangeland dominated by dense patches of Wyoming big <br />sagebrush. Some native graminoids, forbs, and shrubs occur in the shrub understory and inner- <br />space in the shrub mosaic. Typically, grasses include crested wheatgrass, bluegrass species and <br />mountain brome. Forbs include white yarrow, common dandelion and a variety of mustard. <br />Shrubs include big sagebrush, silver sage, and Woods' rose. <br />1.1.2 Improved Agricultural pasture <br />The improved agricultural pasture community includes a variety of native grass species that have <br />been inter-seeded with pasture species, primarily crested wheatgrass. <br />1.1.3 Riparian Bottomland Complex <br />This complex is associated with bottomland areas along stream channels in alluvial deposits. <br />Plant species found in this complex include: Rocky Mountain alder, Wyoming big sagebrush, <br />silver sage, smooth brome, redtop, bluegrass, inland saltgrass, spikerush, cattails and Nebraska <br />sedge. <br />The Riparian Bottomland has been mapped and will be monitored for subsidence effects using <br />approved methods. Therefore, it will not be characterized by baseline vegetation sampling. Open <br />water areas within the Riparian Bottomland were delineated using aerial photographs. <br />1.1.4 Disturbed <br />Surface disturbance that is not related to mining activities will be mapped, as applicable. <br />1.1.5 Open Water <br />If it is present within the study area, open water and defined ephemeral channels will be mapped. <br />Ephemeral channels will only be mapped when they have a distinct bed and bank and the level of <br />flow within them creates scour that prevents the growth of vegetation. Ephemeral channels with <br />vegetation across their bottoms will be mapped in their appropriate vegetation community. <br />2 Vegetation Sampling Methods <br />Total ground cover, vegetation cover, herbaceous production, shrub density, and species <br />diversity data will be collected as required by the regulations in the proposed amendment area. <br />Other information will include a plant species list and representative photographs of the <br />vegetation communities. Additionally, the location of noxious weed and/or threatened and <br />endangered species, should any occur, will be documented. <br />Vegetation cover data will be collected using the point-intercept line-transect methods. <br />Herbaceous production data will be collected using quadrat sampling methods that harvest the <br />current season's herbaceous plant growth. Woody plant density data will be collected using the <br />belt transect method. Species diversity will be developed from the spring, summer and fall plant <br />species inventories and from quantitative sampling information. <br />Data will be collected at random sample points within each vegetation community to be <br />characterized. Samples will be collected until a statistically adequate sample is obtained, with a <br />minimum sample size of 15. A maximum of 50 samples will be collected. <br />4