A Quantitative Analysis of Fuel Break Effectiveness Drivers in Southern California National Forests

Fuel and wildfire management decisions related to fuel break construction, maintenance, and use in fire suppression suffer from limited information on fuel break success rates and drivers of effectiveness. We built a dataset of fuel break encounters with recent large wildfires in Southern California and their associated biophysical, suppression, weather, and fire behavior characteristics to develop statistical models of fuel break effectiveness with boosted regression. Our results suggest that the dominant influences on fuel break effectiveness are suppression, weather, and fire behavior. Variables related to fuel break placement, design, and maintenance were less important but aligned with manager expectations for higher success with wider and better maintained fuel breaks, and prior research findings that fuel break success increases with accessibility. Fuel breaks also held more often if burned by a wildfire during the previous decade, supporting the idea that fuel breaks may be most effective if combined with broader fuel reduction efforts.

Automated summary

Decisions regarding fuel break construction, maintenance, and use in fire suppression lack sufficient information on their success rates and driving factors. This study analyzed the encounters between fuel breaks and recent large wildfires in Southern California, incorporating various characteristics such as biophysical factors, suppression strategies, weather conditions, and fire behavior. Statistical models were developed to determine the effectiveness of fuel breaks, and the results indicated that successful fuel break implementation is influenced by suppression efforts, weather conditions, and fire behavior. Factors related to fuel break placement, design, and maintenance are less significant, although wider and better maintained fuel breaks align with higher success rates and previous research findings that accessibility improves fuel break effectiveness. Additionally, fuel breaks that have experienced wildfire burn in the past decade are more likely to be effective, suggesting that combining fuel breaks with broader fuel reduction efforts may yield better results.