Setting the Stage: Shrublands at Risk

The vast shrublands of Western North America, including the sagebrush (Artemisia spp.) ecosystem, provide a wide range of resource values, including recreation, livestock grazing, mining, energy extraction, wildlife habitat, and wilderness. Increasingly, however, these arid and isolated lands have faced a wide range of threats, including wildland fires, invasive plants, roads, oil and gas development, and climate change (Connelly and others 2004, Knick 1999, Wisdom and others 2005a). (In this paper we define a threat as a potentially detrimental human activity or ecological process as it affects native species or their habitats [Wisdom and others 2005a]and risk as "the potential, or probability, of an adverse event" [Burgman and others 1993].)

Despite the recognized values of shrublands and grasslands—collectively known as rangelands—such lands have seldom benefited from the long-term research and monitoring traditionally focused on forested ecosystems in the United States. This lack of a well-established body of research and monitoring presents special challenges in evaluating and predicting effects of disturbances, both natural and anthropogenic, on rangeland habitats and wildlife in the United States. The dearth of attention is especially noteworthy in that rangelands compose about 50 percent (39 million ha) of the 77 million ha managed under the National Forest System. Nationwide, rangelands total 312 million ha, with 43 percent managed by the Federal Government (http://www.fs.fed.us/rangelands/).

Great Basin Ecoregion

To address the needs of land managers charged with conservation planning and management of shrublands and associated wildlife, Wisdom and others (2005a) described methods for conducting regional assessments in native shrubland ecosystems of Western North America. They applied those methods in a prototype assessment of habitat threats within the Great Basin ecoregion (see figure on the right). Their goals were to (1) evaluate habitat conditions for species of concern for conservation planning and management, (2) demonstrate the application of newly developed methods of regional assessment of threats in shrubland communities, and (3) describe implications of results for management.

The following text draws heavily from their book. A requirement of the Great Basin prototype assessment as funded by the Bureau of Land Management (BLM) was that it be conducted with existing data (spatial and other) as a demonstration of products that could be readily delivered. Such pragmatism is often a necessity in natural resource management.

The reader is referred to the Wisdom and others (2005a) book for additional details of the Great Basin case study, especially background material and methods. Appendices with materials not published within the book can be found at http://www.fs.fed.us/pnw/pubs/sagebrush-appendices/.