David Myers

A comparison of the avian soundscapes of organic and conventional olive groves in Messinia, Southwest Greece

Datum, tid och plats: Fredag den 18 maj, kl 14:00 i U29
Handledare: Håkan Berg och Heather Wood
Examinator: Maricela de la Torre-Castro
Masterprogram i landskapsekologi, 120 hp
Examensarbete i naturgeografi och kvartärgeologi, 30 hp
Presentationen är på engelska

Modern intensive agricultural practices are causing great stress on ecosystems worldwide, with the loss of biodiversity of particular concern. Intensification has increased the use of synthetic agro-chemicals as well as decreased landscape heterogeneity. Organic agriculture is seen as an effective way of counteracting this trend. Biodiversity hotspots such as Messinia in southern Greece are particularly vulnerable to losses of biodiversity and the olive groves which dominate this area are no exception. Due to the rapid nature of current ecological change it has become critical to develop quick, economical and practical methods of environmental monitoring. Soundscape ecology and bioacoustic indices are such methods which offer a way of estimating various aspects of audible species populations. The aim of this study was to assess the differences in avian abundance, species richness and diversity between organic and conventional olive groves. The aim was also to investigate the importance of landscape variables and grove structure on bird populations. Twenty-two sites on 11 organic and 11 conventional olive groves were assessed by installing audio recording devices for three hours around sunrise. This generated wave files which were converted to spectrograms and applied to three bioacoustic indices; the Acoustic Complexity Index (ACI), Acoustic Diversity Index (ADI) and Bioacoustic Index (BIO). The results showed olive groves under organic agriculture had significantly higher values for the ACI and BIO indices, and a higher, but not significant difference for ADI. Organic groves showed a more heterogeneous and complex structure with a mixture of tree species and varying canopy height. Landscape variables were similar between management practice and did not significantly influence the index results. Plot scale variables, especially underlying vegetation height had a significant influence on the ACI and BIO index results. Bioacoustic indices gave conclusive results and were an effective way of environmental monitoring in this study, although their implementation and interpretation still require development. Further study is required to discern the precise characteristics of organic olive cultivation which make it more attractive for bird species, although this study suggests certain key variables that play a role.