Chapter 1: Study area description

The boundary for the Wyo- ming Basins Ecoregional Assessment (WBEA) was largely determined by the co-occurrence of some of the largest tracts of intact sagebrush (Artemisia spp.) re- maining 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. Pri- vate 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 Man- agement. Sagebrush in the WBEA faces many potential threats that also influence the broader sagebrush ecosystem. Cli- mate change, drought, land-use practices (e.g., livestock grazing, oil and gas devel- opment), and human development have eliminated and fragmented the sagebrush ecosystem, altered fire regimes, and accel- erated the invasion of exotic plants such as cheatgrass (Bromus tectorum). Less than 2% of sagebrush in the WBEA is perma- nently protected from land cover conver- sion.