In western Cascadia, the region west of the Cascade Crest in Washington and Oregon, wildfire has historically been infrequent, occurring at intervals ranging from one to several centuries. Though rare, wildfires that do occur in this region are often severe, burning areas potentially as large as one million hectares and resulting in extensive tree mortality. As climate continues to warm, some of the largest increases in area burned by wildfire in the western United States are expected to occur in regions such as western Cascadia, where fire activity has historically been limited by cool and wet conditions. Post-fire management strategies, such as replanting, can reduce the negative impacts of fire on forest ecosystems in this region. Developing post-fire response plans, however, requires an understanding of the spatial patterns of burn severity within fire events, since areas with high levels of tree mortality are where management intervention is often most needed.

The objective of this research is to help land managers in western Cascadia develop strategies for adapting to a warmer, drier future that is likely to bring more frequent fire events. Using satellite data dating back to 1984, this project will explore how spatial patterns of burn severity vary with the size of fire events in western Cascadia. The analysis will describe the range of fire impacts, and thus forest regeneration needs, that may be expected with future wildfires in this region. The results of this research will be used by the Washington State Department of Natural Resources (DNR) to develop climate-resilient reforestation approaches and prepare for greater variability in forest growth, two priorities identified in their Climate Resilience Strategy. By gaining an understanding of the spatial patterns of tree mortality anticipated with future wildfires in western Cascadia, managers at DNR will be better able to plan for future seedling demand and post-fire replanting.