Data from: Refuge-yeah or refuge-nah? Predicting locations of forest resistance and recruitment in a fiery world

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 disturbed 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
potential value to forest ecosystems, there is an urgent need to
anticipate (1) where refugia are most likely to be found and (2) where
they align with environmental conditions that support post-fire tree
recruitment. Using biophysical predictors and patterns of burn severity
from 1,180 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 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, refugia were
36.4% (moderate weather) and 31.2% (extreme weather) more common across
forests that experienced recent fires, as compared to recently unburned
areas, supporting increased fire use during moderate weather and shoulder
seasons 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.