Quantifying habitat vulnerability to assess species priorities for conservation management

Identifying species priorities for management and regional conservation plans requires explicit consideration of the relative vulnerability of their habitats. In this paper we propose an objective methodology to quantify habitat vulnerability based on three parameters: the priority status of the habitat (according to the E.C. Habitats Directive), the conservation status of the habitat(s) based on a recent E.C. assessment, and the proportion of known occurrences of the species in the study area which do not occur in a regulatory protected area. To illustrate the method we studied the 124 listed plant taxa that are present in the Pyrenees National Park (France). We combined the scores for the three parameters to produce five classes of habitat vulnerability which were combined with criteria for the territorial responsibility of the National Park for each taxon and their rarity in the National Park to produce a ranking of species. Discussion with park staff was undertaken to finalize species priorities for conservation action, and notably monitoring, not only because of their endemism or rarity but also their vulnerability and risk of extinction in the region. The use of parameters to score vulnerability that are based on European-wide conservation policy and assessments and a simple gap analysis of the proportion of protected populations allows the method to be easily adapted to other regions and taxonomic groups.