Past fire scars are often used by fire managers to limit the severity and spread of active wildfires, however there has been little work to characterize the unique hazards posed to fire responders in these recently burned environments. Snags continue to pose an ever-present hazard to responders, and recent increases in fire activity have resulted in an accumulation of these hazards across forested landscapes of the American West. Developing tools to spatially quantify this hazard can help protect the fire management service as it strives to meet societal needs.
Through a combination of remote sensing, field based estimates of mortality and snag fall rates, and analytics, researchers developed a series of statistical models of snag dynamics for common tree species in dry conifer forests of the America West. These models were then applied to six recently burned landscapes to develop maps that summarize 50 years of projected fire responder exposure to snag hazards. Starting conditions for modeling after each fire were strongly influenced by fire severity, where snag density in high-severity patches was more than double that of low-severity patches. Larger fires also tended to have larger patches of high-severity fire with increased snag hazard.
To characterize risk to fire responders, the model results were summarized by snag height and density to produce a simple index of responder exposure through time. Logical next steps for this work include incorporating non-fire causes of tree mortality and probability of reburn, and additional evaluation by and integration with fire management operations.