Final Report: Disappearing Refugia: Identifying Trends and Resilience in Unburned Islands under Climate Change
Dates
Date Collected
2017-08-01
Citation
Final Report: Disappearing Refugia: Identifying Trends and Resilience in Unburned Islands under Climate Change: .
Summary
Unburned islands are areas within wildfire perimeters that did not burn. These islands are important because they serve as a refuge both during and after the fire for plants and animals to survive and subsequently repopulate adjacent burned areas. This project sought to better understand how and why these islands occur – what makes some areas of the landscape fireproof, even as everything around them burns? How can we use that information to manage forests and rangelands in a way that supports continued development of unburned islands and fire refugia, even under climate change? To answer these questions, we developed a historical atlas of unburned islands across the Northwest (Washington, Oregon, and Idaho) and analyzed trends. We [...]
Summary
Unburned islands are areas within wildfire perimeters that did not burn. These islands are important because they serve as a refuge both during and after the fire for plants and animals to survive and subsequently repopulate adjacent burned areas. This project sought to better understand how and why these islands occur – what makes some areas of the landscape fireproof, even as everything around them burns? How can we use that information to manage forests and rangelands in a way that supports continued development of unburned islands and fire refugia, even under climate change? To answer these questions, we developed a historical atlas of unburned islands across the Northwest (Washington, Oregon, and Idaho) and analyzed trends.
We found that unburned islands conservatively comprise 10% of all area within wildfire perimeters in the Northwest, and that this proportion has not increased or decreased over the last three decades. We examined several case study fires where repeat fires occurred and found that most unburned islands are ephemeral; that is, they don’t remain unburned through multiple fires. The exception was particularly wet sites such as boggy meadows or riparian areas, or unburnable materials such as rocks or bare soils. Further, we found that the proportion of the fire that was unburned and the size and density of unburned islands was not related to fire size. This means that as fires become larger with climate change, there will still likely be a relatively consistent proportion that does not burn, to serve as a refuge for species. Finally, climate was a poor predictor of unburned proportion. This is quite meaningful because it suggests that what determines the formation of unburned islands is localized conditions: topography, fuels, and fire suppression tactics. This means that local actions can be taken to support unburned island formation and maintenance.
