Influence of Vegetation Structure on Lemur Recolonization of Post-Fire Habitats in Northwestern Madagascar.

Habitat quality is a key determinant of wildlife distribution. Fire degrades forests by increasing canopy openness and eliminating even large trees, providing shelter and necessary resources for many species. In Madagascar, fires are prominent, yet the mechanisms linking fire disturbance to lemur habitat occupation remain poorly understood. We conducted a study inside Ankarafantsika National Park during the dry seasons of 2022 and 2023, collecting data along paired burnt-unburnt transects in 18 sites containing burnt partitions with a 1-35-year fire age. Using Generalized Linear Mixed Models, we assessed the effects of forest humidity, temperature, vegetation structure, and woody species richness on lemur occurrence, and evaluated the impact of fire parameters on significant abiotic and vegetation parameters. Lemur responses varied by body size and ecological specialization. Eulemur fulvus most likely occurred in humid habitats with high floristic diversity. Floristic diversity also explained best the presence of Avahi occidentalis and Cheirogaleus medius, while Lepilemur edwardsi was rather connected to dense multi-layered canopies. Small-bodied Microcebus species displayed structural and floristic tolerance. Woody species richness declined in the burnt forest and was highest in the unburnt forest. Fires impacted vegetation structure, increasing openness and understory density, while old burnt and unburnt forests maintained complex vertical layering. Woody species richness emerged as the strongest predictor of lemur species richness. These results indicate that fire primarily affects lemurs through floristic and structural pathways, emphasizing the need to preserve intact forest refugia to sustain lemur diversity under increasing fire pressure in dry forest landscapes of Madagascar.