Fire is an increasingly frequent disturbance in the Atlantic Forest, where most bird species are poorly adapted to fire-driven habitat change. We evaluated how fire regime and landscape structure jointly influence bird beta diversity and its components (turnover and nestedness). Birds were surveyed at 15 landscapes, each containing paired burned and unburned forest patches. Beta diversity was quantified using Bray–Curtis dissimilarity, partitioned into turnover and nestedness, and complemented by the Community Habitat Specialization Index (CHSI) to assess functional composition. Fire consistently reduced turnover between burned and unburned patches, revealing taxonomic homogenization driven by the loss of specialists and the expansion of generalists. CHSI increased with landscape-level fire refugia, and unburned forests supported higher specialization overall, indicating that specialist-rich assemblages persist where long-term unburned forest remains, whereas the loss of refugia accelerates functional homogenization. CHSI also declined with increasing matrix resistance, reflecting reduced recolonization potential in simplified landscapes. Landscape heterogeneity increased dissimilarity and showed a forest condition–dependent effect on CHSI, but heterogeneity alone did not ensure resilience, as many heterogeneous landscapes were dominated by fire-susceptible or low-quality land covers. Nestedness was not significantly associated with fire or landscape predictors, suggesting that ordered species loss may depend on longer-term processes. Our findings highlight how fire regimes and landscape context jointly shape bird community responses and challenge the assumption that heterogeneity universally buffers disturbance. Effective conservation should reduce matrix resistance, enhance functional connectivity and fire refugia, and limit fire recurrence to sustain biodiversity and long-term resilience in tropical forest landscapes.
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