Fine-Scale Spatio-Temporal Heterogeneity of Nocturnal Soundscapes in a Small Urban Park

Small urban parks act as local acoustic refuges, yet their nocturnal soundscapes are rarely quantified at fine spatial scales. We assessed within-park spatio-temporal heterogeneity in Langiewicz Park (~1.1 ha), Wrocław, Poland, using a network of five autonomous AudioMoth recorders mounted on lighting poles at 3.5 m height during early spring campaigns (March–April 2025). Continuous nocturnal recordings (18:00–06:00) were collected, and for each recording, we computed a suite of ecoacoustic indicators capturing acoustic energy (RMS), biophony–anthrophony balance (NDSI), temporal complexity (ACI), spectral diversity (ADI), biotic activity (BI), and acoustic Entropy (H). Indicator time series were aggregated to 15 min resolution to characterise nocturnal trajectories, and dominant patterns were quantified using polynomial trend models and principal component analysis. Despite the small park area and inter-sensor spacing of 50–70 m, indicator distributions differed significantly among microphone locations, with particularly strong spatial contrasts observed in NDSI and BI. Seasonal shifts between March and April further modified the multivariate soundscape structure and the positioning of monitoring sites. These results demonstrate fine-scale nocturnal heterogeneity within a single compact urban park. Our findings suggest that multipoint monitoring design is essential to capture the complex micro-soundscape structures in urban green spaces that single-sensor approaches typically overlook.