Implications of recent wildfires for forest management on federal lands in the Pacific Northwest, USA

Adoption of the Northwest Forest Plan (NWFP) in 1994 marked a pivotal moment in federal forest management in the Pacific Northwest, shifting focus away from intensive timber harvest toward an ecosystem management approach that emphasized late successional and old forest habitat with the creation of a reserve network across moist and dry forest zones. Thirty years after implementation, concerns over accelerating wildfire threats have prompted efforts to adapt the Plan to a warming climate, yet the actual effects of recent fires on NWFP forests are not well understood. In this study, we evaluated over 2200 fires that have burned in the NWFP area over the last four decades to inform conservation efforts and Plan amendments. We quantified patterns and drivers of fire severity across different land use allocations and major forest zones within the NWFP. We found that annual area burned and mean high severity patch size increased across the study area, and historically frequent-fire forest types experienced the most severe wildfire effects. Although moist forest types were less affected by wildfire than dry forests, we observed large-scale forest cover loss in late successional reserves. Weather was a prominent driver of fire severity across much of the region, but bottom-up influences including vegetation type, topography, and pre-fire forest structure exerted strong controls outside of large high severity patches. Our results present a comprehensive analysis of wildfire effects across the NWFP, providing context for future Plan amendments and climate adaptation strategies. • We evaluated over 2200 fires that have burned within the NWFP area. • Area burned and high severity patch size increased in both moist and dry forests. • We observed large-scale erosion of forest cover in late successional reserves. • Climate adaptation strategies will be integral to future NWFP amendments.