The Costs of Achieving Forest Resilience in California

Wildfires in California have become increasingly severe and costly, prompting a significant policy focus on reducing the risk through forest fuel treatments. We provide a novel spatially explicit analysis of the costs associated with achieving forest resilience in California. Our approach integrates empirical models of treatment choice and treatment costs, generating site-specific estimates of the costs of, and the likelihood that managers would choose, two treatment strategies.

With data from the US Forest Service (USFS) Forest Activity Tracking System and landscape data from the Landscape Fire and Resource Management Planning Tools program, we use hierarchical clustering methods to aggregate USFS activities into two primary treatment types: mechanical thinning and prescribed burns. We then use a choice model to predict which treatment type is selected at each site based on site-specific landscape characteristics. Finally, we estimate per-acre treatment costs for each treatment type by linear regression. To address sample selection bias, we apply a Heckman two-step correction procedure to the cost models.

Our results highlight variability in treatment costs across locations and landscape conditions. On average, mechanical thinning and prescribed burns cost $577 and $170 per acre, respectively. We find that mechanical thinning is more commonly applied in areas with higher slopes and elevation; prescribed burns are more likely in flatter areas farther from populated zones. Our cost models indicate that proximity to populated areas, vegetation type, and topography significantly influence treatment costs.

We use our models to project statewide treatment costs for policy scenarios that vary in ambition and identify areas for treatment based on wildfire hazard potential (WHP) and proximity to the wildland–urban interface (WUI). Treating 17 million acres in high-WHP areas is projected to cost $9.7 billion, and treating only high-WHP areas near the WUI (8.7 million acres) is estimated to cost $5.0 billion. A hybrid scenario, which includes all moderate-WHP areas near the WUI and high-WHP areas elsewhere, would require treating 30.7 million acres at an estimated cost of $16.8 billion.

Our analysis is subject to several important limitations. The cost data we use come from 2 USFS-administered projects, and although they are the most comprehensive available, they may not fully capture costs on private or state lands. Additionally, we do not account for permitting or environmental review costs, which are a major component of overall treatment costs. Moreover, as treatment capacity scales up, increased demand for labor and equipment could raise per-acre treatment costs.

Despite these limitations, our study provides policymakers with critical insights into the spatial heterogeneity and key cost drivers of forest fuel treatments. By offering granular, site-specific cost projections, we aim to support more efficient and cost-effective wildfire mitigation strategies. Our findings suggest that current levels of state and federal funding may be sufficient to achieve the lowest-cost treatment goals, but more ambitious strategies would require substantial increases in funding.