Soundscape-based evaluation of small-scale forest management interventions

While forests worldwide decline and European forests bear extensive management impacts, biodiversity within these ecosystems faces increasing threats from human practices that alter habitat structures and species diversity. To address these effects and inform conservation efforts, ongoing biodiversity monitoring is essential to disentangle the impacts of specific forest management practices on biodiversity. This study investigates the impact of small-scale forest management interventions – canopy gaps and deadwood availability - on forest soundscapes, focusing on the abundance and diversity of biophony (animal sounds) and geophony (natural abiotic sounds).Using the FOrest gap eXperiment (FOX) with a full factorial design across 29 sites in German forests, we measured the impacts of these interventions on the soundscape. A machine-learning model classified sounds into the key soundscape categories. After filtering for biophony, the biophonic diversity was calculated using the acoustic complexity index. The combination of gap creation and deadwood enrichment produced the highest biophonic diversity, underscoring its ecological significance.Findings reveal that canopy gaps increase geophony by allowing abiotic sounds to penetrate lower forest layers, while deadwood enhances the abundance of biophony. Isolating biotic sounds before applying acoustic indices offers a novel, interference-free approach to accurately assess biodiversity, enabling precise monitoring of biophonic diversity. These insights demonstrate that integrating soundscape analysis into forest biodiversity assessments can effectively monitor biodiversity, enhancing conservation efforts in managed forests. • Deadwood enrichment increases biophonic activity but has limited impact on biophonic diversity. • Machine learning separates biophony, geophony, and silence in ecoacoustic data. • Pairing machine learning with acoustic indices can quantify soundscape shifts. • Passive acoustic monitoring can support biodiversity monitoring in managed forests.