Fire refugia are important landscape elements by which ecosystems can maintain biodiversity and resilience to disturbances. As climate change alters fire regimes and increases the frequency of so-called megafires, however, there is little understanding of what the impacts may be on fire refugia. This knowledge gap persists, in part, because fire refugia have been largely understudied across large spatial extents at the landscape-scale. Here, we utilize a 30-year database of unburned islands derived from remotely sensed spectral reflectance across Washington, Oregon, and Idaho to describe historical formation and biogeographic distribution of fire refugia across the northwestern US. We then synthesize prior research with our recent efforts to quantify relationships between climate drivers and the proportion, mean patch density, and mean patch size of fire refugia to conceptualize the ecological functions of refugia in a landscape change framework.
We show that while fire size and total area burned across the northwestern US have increased significantly over the last three decades, this increase has not resulted in a decline in refugial extent, nor has it impacted the size and distribution of refugial patches. However, the stationarity of refugial patches is less certain due to the short length of analysis, a case study for a single fire in the region demonstrated that refugia locations were not maintained in repeat burns. These results provide improved understanding of fire refugia that could lead to management strategies for maintaining these important elements throughout the landscape. Translating this understanding to management strategies, however, will require focused research in this arena to develop comparative crosswalks between species-focused and landscape pattern-focused analysis approaches.