Fifty years of regional-scale vegetation change on Atlantic heathlands

Heathlands are semi-natural habitats of high conservation interest in Europe. The Armorican Massif (north-west of France) is a prime area for heathlands conservation, although they have declined sharply during the last century. In order to understand the extent of the changes in heathland plant communities over the last 50 years in this region, we carried out a resurvey of 444 vegetation plots historically sampled between 1947 and 1992. After identifying the qualitative changes in habitat types between the historical and current periods, we analysed the response of various plant community parameters reflecting species diversity, the presence or abundance of particular species (typical heathland species, insect-pollinated species, rare species), and Ellenberg indicators of ecological conditions. We also determined whether the responses of these parameters depended on the location in coastal or inland areas, or in protected or unprotected areas. Almost half (46 %) of the most typical historic heathlands (i.e. open ericaceous vegetations) is now dominated by Molinia and bracken or has evolved into wooded vegetations. Responses for all community parameters indicate a heathland habitat degradation. For species richness and insect-pollinated plant species richness, this decline was more pronounced for inland than coastal heathlands. Also, our results show that the designation of sites as protected areas has not prevented heathland degradation. By identifying the changes that have taken place over the last 50 years at regional level, our results highlight the importance of conserving the last remaining heathlands by applying appropriate management methods.