How to manage hedgerows as effective ecological corridors for mammals: A two-species approach

In European agricultural landscapes, forest fragmentation is one of the most serious threats to wildlife populations viability. Ecological corridors are the management tool used to mitigate the effects of this phenomenon and, in agro-ecosystems, they are traditionally represented by hedgerows. Hedgerows vary dramatically in their internal structure and quality and their effectiveness as corridors depends both on their physical features, such as width and continuity, and internal habitat conditions. Moreover, the ecological requirements related to hedgerow structure are strongly species-specific. In this study, we evaluated which characteristics make a hedgerow suitable for two mammal species sensitive to forest fragmentation at two very different spatial scales: the European Badger and the Hazel Dormouse. The study was carried out in a wide lowland area of northern Italy. Following a stratified cluster sampling design, we surveyed 55 hedgerows. For each hedgerow, we collected both structural and floristic variables and we evaluated how differently they affect hedgerows use by the European Badger and Hazel Dormouse. Our results suggested that, in order to simultaneously increase landscape connectivity for both mammal species, hedgerows should be wide and continuous. Moreover, they should be managed to allow the growth of native species with a complex physical structure in the shrub layer and to promote shrubs development by preventing an excessive tree canopy closure. The information we obtained by this two-species approach provided crucial suggestions for a correct management of hedgerows, which could be used for the conservation of any species with similar ecological requirements and a similar response to fragmentation.