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. CHAPTER IV DESCRIPTION OF AREA The greasewood community lies along arid drainage courses and val- ley floors in the western part of the area where the average annual pre- cipitation is approximately 10 inches or less. The soils are usually heavy and highly alkaline. The predominant plant species is greasewood, which is often accompanied by big sagebruSh, spiny sagebrush, saltbush, or rabbit brush. Grass and forb growth is usually limited. The saltbush community is found on drier, better drained, and slightly less alkaline soils than the greasewood community. It is characterized by Gardner saltbush, fourwing saltbush, shadscale salt- bush, and is accompanied by very sparse grasses and forbs. It is most common in the lower White River Basin, dominating larger areas in east- ern Uintah and western Rio Blanco Counties. The sagebrush community is the most prevalent of the semidesert zone communities and occurs at slightly higher elevations and in areas of higher precipitation than the greasewood and saltbush communities. It is found on moderately alkaline to neutral soils, well-drained but usually moist to considerable depth. It is characterized by the very common big sagebrush and often in association with bitterbrush on sandier soils and snowberry on medium-textured soils. It is often accompanied by fairly good stands of short grasses and forbs. . The pinyon-j uniper community is found on dry rocky slopes, usually from 5,000 to 7,000 feet elevation but occasionally as high as 8,500 feet on south and west slopes. The type species are pinyon-pine and three different junipers: Utah, oneseed, and Rocky Mountain junipers, the latter at slightly higher elevations than the first two. Stands vary from open to dense and are modified locally by the intrusion of sagebrush, bitterbrush, Gambel oak, mountain mahogany, rabbit brush, snowberry, or western serviceberry. Due to the dry site conditions and shallow soil, understory with this community is sparse or lacking. The mountain shrub community forms the transition between the semidesert areas and the coniferous forests of the higher elevations. It is generally found at elevations of 6,000 to 8,500 feet and on deeper and damper soils than the pinyon-juniper stands. The dominant shrub is usually Gambel oak. Other shrubs that grow in association with the oak or in mixed and pure stands are big sagebrush, bitter- brush buffalo currant, mountain mahogany, snowberry, western choke- cherry, and western serviceberry. A moderate to heavy understory of grasses and forbs usually exists in this community. The ponderosa pine-Douglas fir community generally lies between 6,000 and 8,500 feet in elevation, often forming a transitional link between the lower-lying pinyon-juniper stands and the higher-lying spruce-fir forests. This group is characterized by ponderosa pine and Douglas fir, the former dominating south-facing slopes and the latter, . 31