99th ESA Annual Meeting (August 10 -- 15, 2014)

OOS 9

Understanding Woody Plant Encroachment as a Coupled Human and Natural System

After centuries existing as grasslands rangeland systems worldwide have been transforming into woodlands and shrublands. This phenomenon, known as woody plant encroachment (WPE), is especially prevalent in the Southern Great Plains of the United States where it is estimated to be 5 to 7 times greater than in other regions of the country. The rapid ecological transition is driven largely by human-related elimination of fire from the system—both because overgrazing has reduced fuel available for fire to propagate and because of active fire suppression the WPE has resulted in significant changes to primary production, trophic structure, biological diversity, and nutrient cycling of rangeland systems. Rangeland systems with high densities of WPE provide fewer ecosystem services including changes in hydrological regimes and forage for livestock. Further, the woody-plant dominated ecosystem state is highly resilient; it is extremely difficult and cost prohibitive to covert established woodlands back to grasslands. This, in turn, has significant social and economic implications and impacts on human well being and highlights the need to understand the social and ecological factors that facilitate or inhibit this widespread environmental change. A new understanding of WPE is needed that treats it as complex social-ecological system that encompasses the interactions of physical, ecological and social systems. This symposium explores the opportunities and challenges of addressing woody plant encroachment as a complex problem with both ecological and social dimensions.