Habitat structure filters amphibian functional strategies in tropical agroforestry landscapes

Land‐use change is a major driver of biodiversity loss, yet its effects on ecological communities depend on how species with given traits respond to environmental modification. Amphibians are particularly sensitive to habitat alteration, but how species’ traits determine responses to agroforestry remains poorly understood in tropical landscapes. We investigated how land‐use change affects amphibian functional diversity and trait composition in northeastern Madagascar by comparing old‐growth forests with agroforestry systems differing in management intensity. Across 81 plots, we sampled amphibians using standardized visual encounter surveys, quantified functional diversity (functional richness, dispersion and divergence), assessed the effect of habitat features on functional diversity, analysed community‐weighted mean traits to identify shifts in trait composition across habitats, and used trait-environment analyses to identify environmental drivers of trait composition. Functional richness was significantly higher in old‐growth forests than in agroforests. Functional richness increased with canopy cover and showed a weak negative association with non‐woody plant cover, while functional dispersion and divergence did not vary among habitats. Community‐weighted mean traits differed markedly between habitats. Old-growth forest communities were characterized by higher proportions of cathemeral species, semi‐arboreal and terrestrial strata users, terrestrial and arboreal breeders, and species with endotrophic tadpoles. In contrast, agroforests were dominated by nocturnal species, aquatic breeders and species with exotrophic, free‐swimming tadpoles. Trait–environment analyses revealed a dominant gradient of vegetation structural complexity, with canopy cover, tree density and native tree composition associated with forest-dependent reproductive and microhabitat strategies, while simplified agroforests were associated with free-water reproductive strategies. Our results indicate that agroforestry systems can retain amphibian species, but that species with specific traits are filtered out. Consequently, some forest-associated traits become underrepresented or absent. Maintaining canopy cover, native trees, and vertical vegetation structure within agroforestry systems should be a management priority for conserving amphibian functional diversity.