Status and Threats in the Sagebrush Ecosystem

Sagebrush ecosystem in the U.S

The sagebrush ecosystem covers more than 43 million ha within the Western United States and Canada and constitutes one of the largest ecosystems in North America (Center for Science, Economics, and Environment 2002; Wisdom and others 2005a). More than two-thirds of the total area covered by sagebrush in the United States is on land publicly owned and managed by State or Federal agencies; the BLM alone manages 52 percent of the sagebrush in the United States (Knick and others 2003) (see figure on the right). Conservation and restoration of the sagebrush ecosystem are of special concern to State and Federal resource management agencies due to extensive habitat degradation and loss (Knick 1999, Knick and others 2003, Wisdom and others 2005a). Since European settlement, the area covered by sagebrush has been reduced more than 40 percent (Connelly and others 2004), and only a small fraction remains unaltered by anthropogenic disturbances (West 1999).

A plethora of threats to sagebrush and other native shrubland communities has been identified (Connelly and others 2004, Wisdom and others 2005a). Among these are invasion of exotic vegetation, altered fire regimes, road development and use, mining, energy development, climate change, encroachment of pinyon (Pinus spp.) and juniper (Juniperus spp.) woodlands, intensive livestock grazing, and conversion to agriculture or urban areas. The cumulative effects of these stressors have resulted in the sagebrush ecosystem being regarded as one of the most endangered in the nation (Noss and others 1995), and 20 percent of the plants and animals associated with this ecosystem may be at risk of extirpation (Center for Science, Economics, and Environment 2002).

Several scientific assessments have addressed the effects of multiple threats in the sagebrush ecosystem, (e.g., Boyle and Reeder 2005, Connelly and others 2004, West 1999); however, despite the knowledge gained from these studies and others, efforts to abate the degradation and elimination of sagebrush have not been successful at large scales (Hemstrom and others 2002, West 1999).