Research Reveals Promising Management Tools for Decreasing the Severity of Wildfires

Researchers investigated factors contributing to the fire severity patterns within 150 wildfires in conifer forests throughout northeastern Washington occurring between 2001 to 2019. Their results showed that previous wildfires, timber harvest, thinning treatments — and especially prescribed burns — strongly influenced the severity of subsequent wildfires. In areas burned within the past 2 to 3 decades, prior fire decreased the severity of subsequent burns, particularly during the first 16 years. They found that thinning decreased the severity of subsequent fires, but thinning combined with prescribed fire was most effective. Planting, in contrast, could either increase or decrease burn severity, depending on the timing of subsequent fires and whether post-harvest slash was properly burned. Prescribed burning was the most effective treatment at lowering subsequent burn severity. Their results on prescribed fire treatments are compelling not only because they caused a decrease in future burn severity but they also almost completely prevented high-severity fire. Thus, prescribed fire sets up a strong stabilizing feedback, increasing resilience to subsequent fires. If managers wish to decrease the severity of subsequent fires, this research provides support for using prescribed fire treatments and allowing fires to burn under moderate weather conditions.