Fuel treatment efficacy and longevity: regional trends and drivers

Background Understanding the drivers of fuel treatment effectiveness and longevity will help land managers strategically apply and maintain treatments. Aims To assess the relative importance of climate and weather (top-down factors) and vegetation and topography (bottom-up factors) in fuel treatment effectiveness. Methods We used climate, weather, vegetation, and topographic variables with the Fuel Treatment Effectiveness Monitoring database to assess fuel treatment effectiveness in California, USA. Machine learning models assessed the relative importance of these factors. Scenario analyses investigated treatment longevity. Key results Modelled fuel treatment effectiveness showed no marked decline over the first 10 years after treatment when controlling for treatment and vegetation types, topography, climate, and weather. Climate and weather helped predict successful modification of fire behaviour, whereas topography helped identify conditions associated with failure. Conclusions Fuel treatment effectiveness can be enhanced by carefully considering vegetation type, topography, and treatment size. Implications As warming and drying trends alter fire weather conditions, managers can use the vegetation, topographic, and treatment-size factors identified here to plan future fuel treatments.