U.S. Joint Fire Science Program


Date of this Version


Document Type



Fire Science Brief, Issue 1, October 2007


US government work.


Strong scientific evidence has long been needed on the effectiveness of fuel treatments when subsequent wildfires encounter treated areas. This project studied what happened when wildfires met fuel treatments, using results from five large wildfires in mixed-conifer forests in the Western United States. The relation between fuel treatment effectiveness and wildfire severity differed by treatment type. Recent treatments (less than 10 years old) that reduced surface fuels were generally effective, whether or not thinning had been done first. Combination treatments, with thinning followed by slash disposal, showed the most impressive results, and in fact the effectiveness of combination treatments increased with weather severity. The study’s results suggest that fuel treatments such as thinning and prescribed burning may reduce the intensity and severity of subsequent wildfire. Treatment of surface fuels appears to be the most important factor for success. This study of real-world results helps support the argument that well-designed fuel treatments are worth the effort.