Regional analysis of the impacts of climate change on cheatgrass invasion shows potential risk and opportunity

Bradley, Bethany A. “Regional Analysis of the Impacts of Climate Change on Cheatgrass Invasion Shows Potential Risk and Opportunity.” Global Change Biology, vol. 15, no. 1, Jan. 2009, pp. 196–208,



It is widely recognized that climate change can affect invasive species distributions. In this article, Bradley examines the effects of climate variables on the current and future distribution of cheatgrass (Bromus tectorum) in the western US. The best environmental predictor of current and future cheatgrass distribution was found to be summer precipitation followed by annual average precipitation, spring precipitation, winter maximum temperature, and winter minimum temperature. Currently cheatgrass is found in northern Nevada, western Utah, southern Idaho, and eastern Oregon and Washington. Ten atmosphere–ocean general circulation models (AOGCMs) were used to simulate future climate conditions (including three of the environmental predictors: spring precipitation, summer precipitation, and annual precipitation), recorded as percent change by 2100 across the western US. These climate projections were then used to model future distribution of cheatgrass through the year 2100. According to a middle-ground climate outlook scenario, parts of California and Wyoming are expected to lose climatic suitability for cheatgrass, while parts of Wyoming and Montana will gain suitability, and the rest of the region will maintain the same suitability. 


Take Home Points:

  • Summer, spring, and annual precipitation are the best environmental predictors for distribution and climatic suitability for cheatgrass
  • Future climate conditions will yield some regions that are more suitable, less suitable, or relatively similar suitability for cheatgrass invasion 


Management Implications:

  • Invasive plants can spread quickly so knowing which regions are at risk before invasion helps managers to prioritize prevention
  • Precipitation change is difficult to model due to its high level of uncertainty, but using a variety of models can capture variability and allow for robust predictions to best inform management decisions
  • Some regions are predicted to lose climatic suitability for cheatgrass in the future and this creates unique opportunities for ecosystem restoration efforts in these areas
  • Cheatgrass is widespread across the western US and future suitability varies by region so opportunities for cross-state management and collaboration are important