Data to: Understanding acoustic indices as multi-taxa biodiversity and habitat quality indicators

Acoustic monitoring captures the sound of nature, revealing biodiversity patterns and underlying drivers. Acoustic indices are increasingly used to analyse obtained recordings, but studies show inconsistent performance of acoustic indices as biodiversity indicators. Here, we develop a conceptual framework on what acoustic indices reflect, including sound sources as well as their direct and indirect drivers. We evaluate our framework using recordings from six land use types and old growth forest sites in north-eastern Madagascar. We found the highest correlation (adj. R² > 0.51) of Acoustic Diversity Index and Acoustic Entropy with endemic multi-taxa species richness, canopy closure, and vegetation density. The results suggest that including multiple taxa strengthens the association between the indices and species richness, potentially accounting for unobserved vocalising taxa, and that acoustic indices indicate habitat quality, reflecting underlying indirect and direct drivers affecting biodiversity. Yet, some acoustic indices are limited by saturation and their sensitivity is too low to detect small changes in biodiversity (i.e., loss of few species).声学监测（acoustic monitoring）可捕获自然声响，用以揭示生物多样性的分布模式及其潜在驱动因素。声学指数（acoustic indices）被愈发广泛地应用于已获取录音的分析，但相关研究表明，声学指数作为生物多样性指示物的表现并不统一。在此，我们构建了一套阐释声学指数内涵的概念框架，涵盖声源及其直接与间接驱动因素。我们借助马达加斯加东北部六种土地利用类型与原始林样地的录音数据对该框架进行了验证。研究发现，声学多样性指数（Acoustic Diversity Index）与声学熵（Acoustic Entropy）与特有多类群物种丰富度、林冠郁闭度及植被密度的相关性最高（调整后R²>0.51）。研究结果表明，纳入多类群可强化声学指数与物种丰富度之间的关联，这或许可以解释未被观测到的发声类群；同时声学指数能够指示生境质量，反映影响生物多样性的潜在间接与直接驱动因素。但部分声学指数存在饱和性局限，且其灵敏度不足以检测生物多样性的细微变化（即少量物种的消失）。