WWETAC Projects

Project Title: Evaluation of models for assessment of threats to wildlands in the Western United States from displacement by cheatgrass and pinyon-juniper woodlands

Principal Investigators: Mary M. Rowland and Michael J. Wisdom, USDA Forest Service, Pacific Northwest Research Station, La Grande, OR; Lowell H. Suring, USDA Forest Service, Washington Office; Robin J. Tausch, USDA Forest Service, Rocky Mountain Research Station, Reno, NV


Collaborators: Bryan Endress, Zoological Society of San Diego, Escondido, CA; Jennifer Boyd, Susan Geer, Bridgett Naylor, and Catherine G. Parks, USDA Forest Service, Pacific Northwest Research Station, La Grande, OR; Mark Finco and Ken Brewer, Remote Sensing Applications Center (RSAC), Salt Lake City, UT

Key Issues/Problems Addressed:

One of the most prevalent threats to sagebrush (Artemisia spp.) and other native shrublands of the western U.S. is displacement by cheatgrass (Bromus tectorum) and by pinyon-juniper (Pinus-Juniperus spp.) woodlands. Because of these losses and degradation, sagebrush and associated species are declining.

Setting and Approach:

A regional assessment of habitat threats was conducted for 40 sagebrush-associated vertebrates of concern in the Great Basin. The primary goals were to (1) evaluate habitat conditions for species of concern for conservation planning and management, (2) demonstrate the application of new methods of regional threat assessment in shrubland communities, and (3) describe implications of results for management.

Key Findings:

Over 55 percent (4.8 million ha) of sagebrush in the Great Basin is at moderate or high risk of being displaced by cheatgrass. Cheatgrass invasion also threatens other shrubland communities, particularly salt desert scrub where 7.1 million ha (96 percent) are at moderate or high risk. Substantial areas of sagebrush (2.0 million ha or 41 percent) are predicted to be at moderate or high risk of displacement by pinyon-juniper in the eastern Great Basin. One third of the area in sagebrush cover types in the eastern Great Basin  was both at high risk to cheatgrass and low or moderate risk from woodlands. Habitat loss of sagebrush and other native plant communities to cheatgrass within species’ ranges in the Great Basin could exceed 50 percent, impacting 83%  of the 40 vertebrate species evaluated.


Maintenance and restoration of native shrublands in the Great Basin will require both active and passive management to mitigate the formidable threats posed by cheatgrass and pinyon-juniper woodland expansion.

Rowland, M. M., L. H. Suring, R. J. Tausch, S. Geer, and M. J. Wisdom. 2010. Dynamics of western juniper woodland expansion into sagebrush communities in central Oregon.  Natural Resources and Environmental Issues. Volume 16, Article 13.  11 pp. (PDF, 1.0 MB)

Rowland, M. M., L. H. Suring, and M. J. Wisdom. 2010. Assessment of habitat threats to shrublands in the Great Basin: a case study. Pages 673-685 in Pye, J. M., H. M. Rauscher, Y. Sands, D. C. Lee, and J. S. Beatty, technical editors. Advances in threat assessment and their application to forest and rangeland management. Gen. Tech. Rep. PNW-GTR-802. U.S. Department of Agriculture, Forest Service, Pacific Northwest and Southern Research Stations, Portland, Oregon, USA.  708 p. 2 vol. (PDF, 424 KB)

Wisdom, M.J., M.M. Rowland, and R.J. Tausch. 2005. Effective management strategies for sage-grouse and sagebrush: a question of triage? Transactions of the 70th North American Wildlife and Natural Resources Conference pp 206-227. (PDF, 902 KB)

Wisdom, M. J., M. M. Rowland, and L. H. Suring, technical editors. 2005. Habitat threats in the sagebrush ecosystem: methods of regional assessment and applications in the Great Basin. Alliance Communications Group, Lawrence, Kansas, USA. (PDF, 3.6 MB)

WWETAC Project ID: FY06JB13



Model development, application, and evaluation