Refuge‐yeah or refuge‐nah? Predicting locations of forest resistance and recruitment in a fiery world

• Published in: Global change biology 2023-12, Vol.29 (24), p.7029-7050
• Main Authors: Rodman, Kyle C., Davis, Kimberley T., Parks, Sean A., Chapman, Teresa B., Coop, Jonathan D., Iniguez, Jose M., Roccaforte, John P., Sánchez Meador, Andrew J., Springer, Judith D., Stevens‐Rumann, Camille S., Stoddard, Michael T., Waltz, Amy E. M., Wasserman, Tzeidle N.
• Format: Article
• Language: English
• Subjects: Biota; Climate change; climate vulnerability; Coniferous forests; Coniferous trees; Conifers; disturbance refugia; Ecological effects; ecological resilience; Environmental conditions; Extreme weather; Fire resistance; fire severity; Fires; fire‐driven transformations; Forest ecosystems; Forests; Global climate; Global warming; Land use; Locations (working); post‐fire tree recruitment; Refuges; Refugia; southwestern United States; Sustainable ecosystems; Terrestrial ecosystems; Weather
• ISSN: 1354-1013; 1365-2486
• DOI: 10.1111/gcb.16939

Climate warming, land use change, and altered fire regimes are driving ecological transformations that can have critical effects on Earth's biota. Fire refugia—locations that are burned less frequently or severely than their surroundings—may act as sites of relative stability during this period of rapid change by being resistant to fire and supporting post‐fire recovery in adjacent areas. Because of their value to forest ecosystem persistence, there is an urgent need to anticipate where refugia are most likely to be found and where they align with environmental conditions that support post‐fire tree recruitment. Using biophysical predictors and patterns of burn severity from 1180 recent fire events, we mapped the locations of potential fire refugia across upland conifer forests in the southwestern United States (US) (99,428 km2 of forest area), a region that is highly vulnerable to fire‐driven transformation. We found that low pre‐fire forest cover, flat slopes or topographic concavities, moderate weather conditions, spring‐season burning, and areas affected by low‐ to moderate‐severity fire within the previous 15 years were most commonly associated with refugia. Based on current (i.e., 2021) conditions, we predicted that 67.6% and 18.1% of conifer forests in our study area would contain refugia under moderate and extreme fire weather, respectively. However, potential refugia were 36.4% (moderate weather) and 31.2% (extreme weather) more common across forests that experienced recent fires, supporting the increased use of prescribed and resource objective fires during moderate weather conditions to promote fire‐resistant landscapes. When overlaid with models of tree recruitment, 23.2% (moderate weather) and 6.4% (extreme weather) of forests were classified as refugia with a high potential to support post‐fire recruitment in the surrounding landscape. These locations may be disproportionately valuable for ecosystem sustainability, providing habitat for fire‐sensitive species and maintaining forest persistence in an increasingly fire‐prone world. Climate warming and altered fire regimes are driving ecological transformations that can have critical effects on Earth's biota. Using information from >1000 recent fire events and >10,000 field plots, we mapped the locations of potential fire refugia—forested sites that may be most resistant to transformation—throughout the southwestern United States, and identified those that are most likely to support post‐fire tr