The influence of livestock grazing on wildfire risk in the western United States: economic and management tradeoffs

Abstract

Wildfire risk has increased over the last thirty years in the western United States. Current wildfire risk management tools, including prescribed fire and mechanical treatments, are not implemented at target levels. Large-scale, low-intensity livestock grazing is a potentially under-recognized tool for managing wildfire risk. This research considers how livestock grazing on western United States Forest Service (USFS) National Forests may reduce wildfire risk and addresses some of the associated management and economic tradeoffs. While the USFS permits grazing on approximately 73 million of 157 million acres of western National Forest land, the grazing is not intentionally managed to reduce wildfire risk. I use an ordinary least squares two-way fixed effects model on novel panel data to estimate the relationship between livestock grazing and wildfire activity. I find that a 10 percentage point increase in livestock grazing is associated with a 12.6 percent decrease in overall wildfire area burned and 11.9 percent decrease in wildfire area burned at high severity. These effects vary by region. I do not find evidence that the USFS uses prescribed fire and livestock grazing as substitutes when managing wildfire risk. However, livestock grazing may be useful as a substitute for suppression activities - if all livestock grazing were removed from National Forests in the western United States, I estimate suppression expenditures would increase by $324 million per year. Increasing livestock grazing could be a valuable wildfire risk management tool, but practical barriers, such as resource limitations tied to National Environmental Policy Act processes, constrain opportunities for expansion.