Comparing size of Osmoderma eremita populations and habitat quality in different French localities: conservation perspectives

Abstract

Osmoderma eremita is a beetle living in old deciduous trees with cavities. Its populations are met in forest habitats and habitats of substitution like hedgerow networks and orchards. These habitats of substitution covered about 10% of the French territory, particularly prior the fragmentation of hedge networks and orchards caused by the modernization of agriculture in the past 50 years. Nowadays, forest habitats of O. eremita, which are closer to natural habitats, represent very small areas distant from each other. Distances between these sites are much higher than the species’ dispersion capacity. Thus, metapopulations that live in these areas are isolated. The conservation of the species appears to be best guaranteed in relictual forest habitats, whereas the disappearance rate of old trees with cavities accelerates in hedged farmlands and orchards, which reduces very quickly the conservation potential of viable metapopulations of O. eremita in traditional agrarian landscapes.