Influence of vegetation structure on lemur recolonization of post-fire habitats in northwestern Madagascar

Abstract

Habitat quality is a key determinant of wildlife distribution and persistence. Any disturbance such as fire degrades forest habitats by increasing canopy openness, reducing tree basal area, and eliminating large, cavity-bearing trees providing shelter for many species. In Madagascar, fire has become a prominent disturbance, yet the mechanisms linking fire disturbance to lemur habitat occupation remain poorly understood. Using Generalized Linear Mixed Models, we assessed the effects of forest humidity, temperature, vegetation structural gradients, and tree species richness on lemur occurrence, and evaluated the impact of fire regime parameters on significant abiotic and structural vegetation gradients. Lemur responses varied by body size and ecological specialization. Eulemur fulvus most likely occurred in humid habitats with high floristic diversity. The latter also explained best the presence of Avahi occidentalis and Cheirogaleus medius, while Lepilemur edwardsi was rather connected to dense stands of overstory trees. Small-bodied Microcebus species displayed a higher structural and floristic tolerance. Tree species richness declined sharply in burnt areas and was highest in unburnt forest. Fires impacted vegetation structural gradients, increasing openness and understory density, while old burnt and unburnt forests maintained complex vertical layering. Tree species richness emerged as the strongest predictor of lemur species richness. These results indicate that fire primarily affects lemurs through floristic and structural pathways rather than microclimatic shifts, emphasizing the need to preserve intact forest refugia with mature canopies and species-rich tree communities to sustain lemur diversity under increasing fire pressure in dry forest landscapes of Madagascar. SummaryO_LIForest fires alter lemur habitats by reducing tree species richness and mature tree density. C_LIO_LIEulemur fulvus, Avahi occidentalis and Cheirogaleus medius preferentially occupied floristically diverse forests, suggesting the relevance of a diverse spectrum of food resources for species of divergent body size. C_LIO_LIThe medium-sized Lepilemur edwardsi was sensitive to fire-induced loss of canopy integrity, limiting their persistence in burnt forests, while small-bodied mouse lemurs (Microcebus ravelobensis and M. murinus) exhibited high resilience to fire-modulated habitat changes. C_LIO_LILemur species richness was strongly linked to tree species diversity, underscoring the role of floristic richness in post-fire lemur and habitat recovery. C_LI