Biotic responses to fire disturbance in Canada

Wildfires are ecological disturbances that drive rapid and often long-lasting changes to biological communities in forest ecosystems. This review synthesizes post-fire responses across microbial (fungi and bacteria), insect and other invertebrate, landbird, forest-dwelling mammal, and aquatic communities, with an emphasis on Canadian forest ecosystems. Taxa show variable spatial and temporal responses to fire, with some exhibiting obvious fire-adapted traits or behaviour and others appearing less resistant or resilient, or both. While advances in molecular tools have significantly enhanced capabilities for detecting and characterizing microbial community responses to disturbance, overall, their responses remain generally understudied in Canada, particularly outside of western boreal forests. Insect responses range from mortality and habitat loss to population increases in fire-adapted species, with fire-insect feedback becoming increasingly important under climate change. Landbird communities show species- and region-specific responses to fire severity and time since burn, but long-term demographic data are lacking. Mammal responses vary widely depending on factors such as mobility, habitat requirements, and post-fire landscape configuration, and include at-risk species facing compounding threats from habitat fragmentation, salvage harvesting, and climate change. Aquatic biota likewise exhibit mixed responses to fire, ranging from increased productivity to declines that are driven by changes in water quality, temperature, and sedimentation. The prospect of more frequent large, high-severity wildfires highlights the need for a better understanding of ecological resilience and vulnerability. Critical research gaps include the need for more integrated, multi-taxa studies to inform conservation planning and fire management across diverse Canadian landscapes.