U.S. Joint Fire Science Program


Date of this Version


Document Type



Fire Science Brief, Issue 135, June 2011


US government work.


Over the past 50 years, wildfire frequency and area burned have increased in the dry forests of western North America. To help reduce high surface fuel loads and potential wildfire severity, a variety of fuel treatments are applied. In spite of the common use of these management practices, there have been relatively few opportunities to quantitatively measure their efficacy in wildfires. That changed with the 2006 Tripod Complex fires in the Okanogan-Wenatchee National Forest in Washington—one of the largest fire events in Washington state over the past five decades. A serendipitous involvement of recent fuel treatments and the availability of pre-wildfire data provided a rare chance to study the effects of different types of fuel treatments on wildfi re severity. In this project, tree mortality, and tree damage were assessed and differences in wildfire severity were evaluated in units with thin-only treatments, thinning followed by prescribed burning treatments, and no treatment. With this study, researchers aimed to provide resource managers with the definitive evidence and specific scientifi c information needed to determine which fuel treatment methods will be the most successful at reducing fuels and mitigating wildfire severity.