A vegetation analysis of the transition between subalpine heathlands and their surroundings in the Monts du Forez (Massif Central, France)

The spatial distribution of species in boundary situations between heathland communities and adjacent vegetation types in the subalpine zone of the Monts du Forez was studied. Ten transects were analysed, four dealing with the transition between heathland and ombrotrophic peatland, and six dealing with the transition between heathland and communities characterized by tall forbs. Species cover and the composition of vascular plants in each square metre were studied in detail. The distribution pattern of the species along the transects is interpreted ecologically and discussed phytosociologically. The similarity between the heathland and adjacent vegetation was calculated and a number of quantitative characteristics of the boundary situations (species diversity, floristic fall, dissimilarity) were analysed. The four methods applied for measurement of alteration in the floristic composition were compared with each other, and their usefulness is discussed here.