A novel methodology to assess fuel treatment effectiveness: application to California’s forests

Background. Fuel treatments are increasingly used to mitigate wildfire risks. 

Aims. Proposing a novel, scalable and transferable methodology, this study investigates which treatment is (more) effective at a regional scale. 

Methods. This research evaluates the effectiveness of fuel treatments in California forests using the Fuel Treatment Effectiveness Monitoring (FTEM) database, which provides a binary (yes/no) assessment of treatment efficacy based on a structured subjective evaluation process. Proposed methodology enables scaling up site-specific treatment outcomes to the regional level. 

Key results. 61% of treatment footprints that were intersected by a wildfire were effective at modifying fire behavior. Treatments that included wildland fire and/or fuel removal were more effective in modifying fire behavior (>70%) than those dominated by fuel rearrangement (49–54%). Even treatments with lower overall efficacy successfully modified fire behavior when applied at large scales. Fuel treatment effectiveness outcomes were robust under extreme weather conditions. 

Conclusions. Fuel treatments are an effective wildfire mitigation tool, even under a warming climate with intensified fire weather. The proposed methodology can be used to assess fuel treatment effectiveness in United States regions that do not have California’s extensive case studies. 

Implications. The choice of treatment options needs to be carefully considered as their effectiveness widely varies.