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i CNAP~ERTHREE Affected Em~ironment largely restricted to elevations about 7,000 feet in higher precipitation zones. At lower elevations on deeper, well-drained soils, the type commonly intergrades with the Sagebrush Association. ' The overstory vanes from open to dense stands, and understory species density and diversity aze inversely related to overstory closure (BLM 1994). Where it occurs along the proposed pipeline corridor, the Mountain Shrub Association occurs primarily on ridgetops and on past- and north- facing slopes (BLM 1998c). This community is used extensively as wildlife habitat for mule deer and grouse from late spring to late fall (SCS 1982). ' The Mountain Shrub Association is a mixture of large to medium tree-like shrugs, most often dominated by Gambe] oak. A mixed understory of smaller shrubs includes snowberry, serviceberry, and Woods rose. The most common grasslike species are various :>edges. American vetch, bedstraw, Colorado columbine, and lambsquarter aze common .forbs. In some azeas, the mountain shrub type supports the highest herbaceous production and species diversity of any plant association. ' The third pipeline corridor segment includes approximately 22 miles of private land paralleling the existing north-south pipeline corridor and extending from the southern boundary of the BLM land south to the Parachute Site. This segment traverses about 11 miles of sagebrush vegetation, 4 miles of mountain shrub vegetation, including the top of Davis Point (Barrett 1994), and less than 2 miles ofpinyon-juniper woodlands (CIG 1995). In a few places, aspen sningers or stands approach the pipeline corridor between MPs 27 and 28, and small areas of Douglas-fir forest are crossed neaz MPs 14 and 20 (BLM 1998c). Batren/rock outcrop vegetation occupies the ' ridgeline at Davis Point (Barrett 1994). The pipeline corridor also crosses about 5 miles of agricultural land, including a small amount of irrigated land along Parachute Creek north of the Parachute Site (CIG 1995). A few riparian wetland communities in the study area occur as narrow bands associated with Piceance Creek and Parachute Creek (Steigers 1998b). Agricultural Land ~ a Agricultural lands aze found along valley bottom lands, primarily along Stewart Gulch, Piceance Creek, and Parachute Creek. Agricultural land is a man-made community that consists of hay meadows and natural vegetation interfaces. Common species include alfalfa, clover, wheatgrass, Kentucky bluegrass, red-top, brome, and orchard grass. Some of the fields are irrigated or flooded by ditches along the valley bottom. Riparian and Wetland Vegetation , Riparian vegetation in the area is dominated by grasses, including western wheatgrass, slender wheatgrass, and needlegrass, as well as several sedges and rushes. Shrubs, including big sagebrush, rubber rabbitbrush, and greasewood, are present but sparse (BLM 198:!). This community occurs south of the Piceance Site along Piceance Creek, where it occupies Hagga loam and Havre loam soils and typically is used extensively for winter range for mule deer. Pazachute Creek and its tributaries typically support box elder and narrowleaf cottonwoods in the ' overstory. Understory vegetation is vaned but typical species include sandbar willow, serviceberry, chokecherry, and skunkbrush (Steigers 1998a). Riparian vegetation in the vicinity of Parachute Creek occupies torrifluvent soils (alluvial soils on floodplains). These riparian 3-30 Vegetation '