Chapter 1: Study area description

Abstract

The boundary for the Wyoming Basins Ecoregional Assessment (WBEA) was largely determined by the co-occurrence of some of the largest tracts of intact sagebrush ( Artemisia spp.) remaining in the western United States with areas of increasing resource extraction. The WBEA area includes two ecoregions in their entirety, Wyoming Basins and Utah-Wyoming Rocky Mountains, and portions of two others (Southern Rocky Mountains and Middle Rockies-Blue Mountains). Over half the study area is in Wyoming; the remainder includes parts of Colorado, Utah, Idaho, and Montana. Private landowners manage most (33.1%) of the land base in the WBEA, followed by the U.S. Forest Service (27.3%) and U.S. Bureau of Land Management (25.6%). Sagebrush is the dominant land cover type in the study area, totaling >130,000 km 2 ; nearly half the sagebrush in the WBEA is managed by the U.S. Bureau of Land Management. Sagebrush in the WBEA faces many potential threats that also influence the broader sagebrush ecosystem. Climate change, drought, land-use practices (e.g., livestock grazing, oil and gas development), and human development have eliminated and fragmented the sagebrush ecosystem, altered fire regimes, and accelerated the invasion of exotic plants such as cheatgrass ( Bromus tectorum ). Less than 2% of sagebrush in the WBEA is permanently protected from land cover conversion.