Landscape heterogeneity buffers soundscape degradation in human-modified landscapes

Land-use intensification reshapes tropical landscapes, altering the spatial structure of habitats and affecting acoustically active biodiversity. We assessed how habitat amount and landscape heterogeneity jointly influence soundscapes in 72 Atlantic Forest landscapes spanning 5–85% native vegetation. We calculated acoustic diversity (ADI, Distribution of acoustic energy across frequency bands) and acoustic complexity (ACI, Variability in acoustic amplitude) based on autonomous audio recordings for diurnal, nocturnal, and combined periods. ADI decreased with increasing habitat amount, likely reflecting the dominance of generalist and insect-driven acoustic signatures in more altered landscapes. In contrast, ACI increased with habitat amount, but this effect depended strongly on landscape heterogeneity. Heterogeneous landscapes maintained high ACI even at <40% habitat cover, acting as a buffer against soundscape degradation, whereas homogeneous landscapes required more than 40–50% habitat to reach comparable levels of acoustic complexity. These findings show that, under ongoing intensification and simplification of human-modified landscapes, maintaining the same proportion of native vegetation may still lead to biodiversity loss if heterogeneity declines. Integrating habitat amount and heterogeneity into conservation planning is therefore essential for sustaining the structure and function of acoustic communities in human-modified tropical regions.