Abstract
Although protected areas are designed to halt human pressures and ensure the persistence of species and habitats of interest, they may experience land cover changes as a result of recovery from pre-protection disturbances. In this study, a two-step methodology was used to analyse the long-term landscape change and its potential impact on biodiversity in a steep southern European National Park. First, we used the WSL Monoplotting Tool software in conjunction with 18 centennial / current ground-based image pairs distributed over a vertical range of 2000 m to examine the fate of 1269 patches of seven land cover types. The use of a three-dimensional model allowed us to estimate real changes in an abrupt terrain where 27 % of its extent is hidden for classical or newer aerial imagery, and to assess the effect of topographic factors such as altitude, slope and perimeter-to-area ratio of the patch. The results showed an overall trend towards more advanced successional stages, with forests being the absolute winners at the expense of more open land cover types such as grasslands. Cliffs, on the other hand, showed the least change over the last century. Then, we analyzed 1108 plant inventories taken in these land cover types to assess how landscape change has potentially affected richness and the presence of plants of conservation interest (endemic, threatened, or species at the northern or southern limit of their distribution). The results suggest an overall loss of plants of interest over the last century, and highlight the conservation value of rocky habitats as refugia. Our analysis provides insights into the consequences of secondary succession of protected areas on biodiversity, and recommend some specific actions for an efficient management towards the most singular and vulnerable plant species.