OOS 27-1 - Annual Bromus invasions in the western United States: Comparisons among species and ecoregions

Thursday, August 11, 2016: 8:00 AM
Grand Floridian Blrm E, Ft Lauderdale Convention Center
Matthew L. Brooks, Western Ecological Research Center, U.S. Geological Survey, Oakhurst, CA, Cynthia S. Brown, Graduate Degree Program in Ecology, Bioagricultural Sciences and Pest Management, Colorado State University, Fort Collins, CO, Jeanne C. Chambers, Rocky Mountain Research Station, USDA Forest Service, Reno, NV, Carla D'Antonio, Environmental Studies, University of California Santa Barbara, Santa Barbara, CA, Jon E. Keeley, Western Ecological Research Center, U.S. Geological Survey, Three Rivers, CA and Jayne Belnap, Southwest Biological Science Center, U.S. Geological Survey, Moab, UT
Background/Question/Methods

Invasive annual Bromus species are widely recognized for their potential to invade, dominate, and alter the structure and function of ecosystems in the western United States. In this presentation we summarize the invasion potential and threats to fire regimes for different Bromus species within each of five ecoregions of the western United States. We characterize invasion potential and threats in terms of ecosystem resistance to Bromus invasion and ecosystem resilience to disturbance with an emphasis on the importance of fire regimes. We also explain how soil temperature and moisture regimes can be linked to patterns of resistance and resilience and provide a conceptual framework that can be used to evaluate the relative potential for invasion and ecological impact of the dominant invasive annual Bromus species in the western United States.

Results/Conclusions

We present models that illustrate how Bromus invasion potential and threats to fire regimes vary among both vegetation types and ecoregions, and among Bromus species. It should not be assumed that just because a particular Bromus is documented to pose a significant threat in one vegetation type or ecoregion, that other Bromus will pose similar threats to other vegetation types or ecoregions. We feel that these models are most reliable for B. tectorum and B. rubens, especially in the Cold Deserts, Mediterranean California, and Warm Desert ecoregions. The refinement and validation of these models would improve their reliability and utility in evaluating the relative potential for invasion and ecological impact of Bromus in western United States.