Characterizing climate- and fire-driven habitat vulnerability for an old-forest species

Abstract Context Changes in climate and associated disturbance regimes are altering patterns of biodiversity by shifting macroenvironmental conditions and modifying the structure and composition of critical habitat. These threats require understanding the climate vulnerability of species habitat to inform conservation planning. Objectives We developed a framework to address this need for the Mexican spotted owl ( Strix occidentalis lucida ), a species whose range is experiencing widespread climate-driven increases in wildfire and drought that can have adverse impacts upon large, old trees, a vital habitat element for owl nesting and roosting. Methods We leveraged broad-scale data describing owl habitat quality, predicted fire severity, and tree recruitment probability to quantify the vulnerability of this species’ habitat in the southwestern United States. Results Owl habitat quality was positively associated with predicted fire severity and negatively associated with tree recruitment potential, indicating that portions of the Mexican spotted owl’s existing range may be vulnerable to forest recruitment failure and, under extreme weather, high-severity wildfire. Despite these patterns, we also identified large patches of high-quality habitat that have the potential to resist high-severity fire and foster tree recruitment, which are likely to sustain current forest communities, and owl nesting and roosting habitat in the near-term. Conclusions In identifying the relative vulnerability of habitat across a broad spatial extent, our framework provides a valuable tool for the conservation of this and other old-forest-obligate species, and habitat specialists in general. More broadly, the framework we have developed may help prioritize limited conservation resources to effectively promote biodiversity in an increasingly dynamic world.