Good wildfires in western U.S. forests (2010-2020)

Abstract Wildfires are integral for western US forests that have evolved with fire. Here we define “good wildfire” as areas that burn in an ecologically beneficial way, with a severity and return interval analogous to their historical fire regimes prior to European settlement. When severities match what an ecosystem historically experienced they can regulate forest structure while promoting regeneration, even in a warming climate 1 . We quantified the amount of forested area (i.e., deciduous, conifer, or mixed forest types) burned with a severity and frequency matching its regime, and compared that to the area of prescribed burns in forests (2010-2020). Of forests that burned in the western US, 49% of the area burned as low-moderate severity good wildfire. High severity good wildfire (in systems that historically experienced this type of fire) represented an additional 9% of forest area burned, bringing the total area of good wildfire to 58% of forested area burned. The low-moderate severity good wildfires burned 3.1 million forest ha (N = 18,061 events), more than double the 1.4 million ha of prescribed burning (N = 24,817 events on federal land) over the same period. Knowing that fires are likely going to increase in frequency and area with warming 2 , our key challenge will be promoting good wildfire while still protecting lives and property.