Evaluating the efficacy of small-plot restorative management in an urban park using low-tech soundscape tools: an exploratory study

The role that cities play in enhancing biodiversity conservation is increasingly recognized. However, since locations for conservation within metropolitan areas are often spatially restricted, and management for biodiversity may conflict with interventions on behalf of other desirable objectives, it is important that the outcomes of urban conservation projects are carefully monitored. Such monitoring is relatively rare. In this study we explored the value of employing soundscape analysis to provide a holistic evaluation of biotic communities at urban sites undergoing different forms of vegetation management. Using readily affordable audio recorders, we evaluated soundscapes in replicated areas within a 481-hectare urban park in Chicago, Illinois. Areas within the park are managed to achieve multiple objectives including both recreational use and nature conservation. We found that relatively small areas within the park that had been subjected primarily to restorative vegetation management supported different acoustic environments with higher avian activity and more prevalent biophonic sound than was the case in managed lawn spaces. The use of a variety of acoustic indices supplemented the analysis of these soundscapes, and whereas all indices affirmed seasonal differences, the Acoustic Complexity Index (ACI) was more helpful than the other indices we employed in discriminating between management practices. We conclude that vegetation management employed even at a small spatial scale in an urban environment can enhance faunal diversity, and that these results can be evaluated using inexpensive sound monitoring equipment. ➢Relatively small areas (<1 hectare) that are under restorative management within a large urban park supported a richer acoustic environment with both higher avian activity and a greater diversity of animal sounds than managed lawn spaces. We show that such areas have low 'biophonic absence,' a term we use to highlight the diminished soundscapes of areas managed as traditional lawns. ➢ Inexpensive recording equipment can be used to detect differences in the quality of soundscapes in managed areas. The use of a variety of acoustic indices applied to these recordings were valuable in the analysis of urban soundscapes. Although all indices we used verified seasonal differences in sites, the Acoustic Complexity Index (ACI) was more helpful than the other indices we employed in discriminating between management practices. ➢ Vegetation management employed even at a small scale in urban environments can enhance faunal diversity.