Biological Disturbance Agents, Fuels, and Fire in Western Conifer Forests

Biological disturbance agents (BDAs) can affect forest composition and structure in multiple ways, including by changing fuels in ways that affect fire risk and behavior. While some research has shown that BDAs can increase the likelihood and severity of wildfires, other research has shown the opposite. These opposing findings have led to confusion around the influence of BDAs on fuels and fire behavior, and uncertainty about the best ways to manage for their impacts in western fire-adapted forests. To better understand the complex relationships at play in how BDAs impact fuels and fire, authors of this article identified the major BDA groups in western coniferous U.S. forests and reviewed existing literature on these groups to conceptualize how BDA-affected fuels will influence fire risk and outcomes. The resulting conceptual framework provides a generalized approach for characterizing BDA outcomes on fuels over time and space, including expected impacts on fuels heterogeneity throughout a BDA groups’ life history. These expected fuels outcomes in turn help develop hypotheses for BDA effects on fire risk and severity.