Megafires are exceptionally large wildland fires that burn more than 100,000 acres. They are driven by hot, dry, windy conditions. In recent years, they have become more common, and some have questioned whether prior fuel-reduction treatments make a difference when extreme fire weather conditions are fanning an uncontrollable wildfire. USDA Forest Service scientists with the agency's Pacific Northwest Research Station and their colleagues are conducting a series of studies examining how past wildfire and fuel reduction treatments influenced fire severity during the 2014 Carlton Complex, a megafire in north-central Washington. They designed these studies to inform implementation of the National Cohesive Wildland Fire Management Strategy. Key findings to date provide useful information to land managers wanting to prioritize the type and strategic placement of fuel treatments to optimize their effectiveness in dry forest management:
(1) Burn severity was significantly lower within the footprint of past fuel treatments than in untreated forest.
(2) Fuel reduction treatments that combined mechanical thinning from below with post-harvest broadcast burns were particularly effective.
(3) Placement of fuel-reduction treatments mattered. Burn severity was significantly lower in fuel treatments positioned on leeward slopes that are sheltered from wind and typically drier and warmer than windward slopes.