North American Sagebrush Steppe and Shrubland

Abstract

The sagebrush (Artemisia spp.) biome extends throughout arid and semi-arid environments in the western U.S., stretching northward into southwestern Canada and eastward to the western Great Plains. The sagebrush biome primarily consists of sagebrush-steppe, with relatively abundant perennial bunchgrasses, and sagebrush shrublands that are generally more desert-like with sparser herbaceous cover. Big sagebrush (A. tridentata) is the most widely distributed species, but other sagebrush species are found throughout the biome, some in relatively distinct environments. Sagebrush communities range from almost pure sagebrush to a diverse mix of shrubs, grasses, and forbs, often with complex biological soil crust communities. Sagebrush ecosystems provide habitat for hundreds of species of conservation concern, including sagebrush-obligate wildlife such as the greater sage-grouse (Centrocercus urophasianus), a widely distributed species that is declining across most of its range, primarily due to deteriorating habitat quality. Roughly ~45% of the historical area of sagebrush steppe/shrublands has been lost due to human activities, including: over-grazing by livestock, clearing to enhance rangeland forage, energy development, roads, cropland conversion; altered fire regimes driven by invasive, fire-prone, annual plant species; and expansion of woodlands caused by land use and climate variability. Climate change will likely have significant future impacts on sagebrush ecosystems. Conservation of sagebrush ecosystems is critical for the myriad species supported, ecological services provided, and the iconic character of western U.S. landscapes, and will likely require enhanced efforts to restore and protect sagebrush habitat from detrimental land uses and wildfire. Scientific research can provide a better understanding of how interactions among various stressors affect sagebrush communities, and how to best manage and prioritize sagebrush habitats for conservation.