Comparing the soundscapes of organic and conventional olive groves: A potential method for bird diversity monitoring

摘要

Modern intensive agricultural practices are causing stress on ecosystems worldwide, with the loss of biodiversity due to decreased landscape heterogeneity as well as high use of synthetic agro-chemicals. Organic farming is seen as an effective way of counteracting this trend. Despite this, relatively little research has been carried out on the effects of olive farming on biodiversity in Greece. This study uses bioacoustic monitoring for a first order assessment of the bird diversity in olive groves. It uses acoustic indices to compare the soundscape of eleven organic and eleven conventional olive groves in Messinia in southern Greece. Three bioacoustics indices: the Acoustic Complexity Index (ACI), the Acoustic Diversity Index (ADI) and the Bioacoustic Index (BIO) were used. Olive groves under organic farming had significantly higher values for the ACI and BIO indices, and a higher but not significant different value for the ADI index. Organic groves showed a much more heterogeneous and complex structure with a mixture of tree species and varying canopy height than conventional groves. Landscape variables were similar between management practices and did not influence the index results. Site level variables, especially underlying vegetation height, had a significant influence on the ACI and BIO indices. Our results suggest that bioacoustic indices could provide a cost effective and non-intrusive way for bird diversity monitoring.