Climate change in western US deserts: potential for increased wildfire and invasive annual grasses
Abatzoglou, J. T., & Kolden, C. A. (2011). Climate change in western US deserts: potential for increased wildfire and invasive annual grasses. Rangeland Ecology & Management, 64(5), 471-478. PDF.
Summary
In the western U.S. arid and semiarid ecosystems have already experienced climatic changes that create a more suitable environment for invasive annual grasses (Bromus tectorum, B. rubens, Pennisetum ciliare). In addition, these conditions are linked to a lengthened fire season, a disturbance which further facilitates the spread of invasive grasses. While projections for invasive grass spread have been made using bioclimatic envelope modeling, these models do not consider the mechanisms underlying the spread of invasives. Here, the authors investigate how climate change may influence the spread of invasive grasses directly, and indirectly by influencing fire, which acts as a mechanism for the spread of invasive grasses. They look at climate normals (e.g. mean temperature) as well as high order climate variables (e.g. interannual precipitation) to determine how climate change will impact both invasive spread directly and indirectly through fire. Projections for climate normals suggest significant warming overall which will continue to aid the spread of cold intolerant invasive grasses. Higher order climate statistics (e.g. an early end to cool season precipitation) will increase fire events and facilitate the spread of invasives. While smaller scale factors may still heavily influence invasive distribution, the authors suggest that these climate trends will act as baseline drivers in increasing suitable habitat for invasive annual grasses through increased climatic suitability and a lengthed fire season.
Take home points
Climate effects on the mechanisms behind the spread of invasives are as important as changing climatic suitability when predicting invasive species spread.
Invasive species are likely to take advantage of climate extremes, where disturbance facilitates spread and growth.
Management implications
Consider timing invasive species management with anomalous weather and climatic events.
An anomalously cold winter may be a good time to target cold intolerant invasives.
An anomalously wet winter may raise fuel moisture in natives allowing for prescribed fire management of invasives.
Suppress the emergence of new invasive communities following anomalous precipitation events.
Keywords
Range Expansion; Impact Study; Model; Invasive Plant; Terrestrial Habitat