This Science article reports on a growing body of research challenging the widespread notion that beetle-killed forests are more vulnerable to more severe fires than those that have escaped infestation. The findings are highlighting the complex causes of western wildfires and raising new questions about the efficacy of some fire prevention policies, such as plans to remove beetle-killed trees from vast swaths of forest.
This synthesis describes what is known about the cumulative impacts of historic livestock grazing patterns and short-term effects of livestock grazing on fuels and fire in sagebrush ecosystems. Over years and decades grazing can alter fuel characteristics of ecosystems. On a yearly basis, grazing can reduce the amount and alter the continuity of fine fuels, potentially changing wildlife fire spread and intensity. However, how grazing-induced fuel alterations affect wildland fire depends on weather conditions and plant community characteristics. As weather conditions become extreme, the influence of grazing on fire behavior is limited, especially in communities dominated by woody plants.
The key findings of this synthesis are organized along nine topical areas: types of crown fires; crown fire initiation; crown fire propagation; crown fire rate of spread; crown fire intensity and flame zone characteristics; crown fire area and perimeter growth; crown fire spotting activity; models, systems, and other decision aids for predicting crown fire behavior; and implications for fire and fuel management.
This paper reviews the nature and characteristics of bark beetle-altered fuel complexes in the conifer forests of the Interior West and the challenges of understanding the effects on extreme fire behavior, including the initiation and spread of crown fires. We also discuss how emerging fire management plans in the U.S. have begun to integrate wildfire management and other forest health objectives with the specific goal of achieving biodiversity and ecosystem resiliency while simultaneously reducing the existence of hazardous fuel complexes.
This study reviewed and synthesized the published literature on modifications to fuels and fire characteristics following beetle-caused tree mortality. The literature agreed about responses in many conditions, including fuels measurements and changes in stands with longer times since outbreak. Disagreement or gaps in knowledge existed in several conditions, particularly in early post outbreak phases and crown fire behavior responses.
This report provides managers with the current state of knowledge regarding the effectiveness of fuel treatments for mitigating severe wildfire effects. A literature review examines the effectiveness of fuel treatments that had been previously applied and were subsequently burned through by wildfire in forests and rangelands. A case study focuses on WUI fuel treatments that were burned in the 2007 East Zone and Cascade megafires in central Idaho. Both the literature review and case study results support a manager consensus that forest thinning followed by some form of slash removal is most effective for reducing subsequent wildfire severity.