Past and present long-term refugia for biodiversity in mountains

Biodiversity loss is one of the main consequences of the two major current drivers of global change: land cover change and climate change. While climate warming is a universal driver, changes in land use are expected to be lower in protected areas. However, land cover changes could be important if protection leads to vegetation recovery following the abandonment of intensive traditional land uses. Our studies in the Ordesa y Monte Perdido National Park (central Spanish Pyrenees) aim to identify areas that have been most resistant to land cover change in the long-term past, and areas that will be most resistant to rising temperatures in the future. The approach to the past was made by comparing pairs of historical and current photographs and analysing the probability of patches of different cover types remaining or changing. This was done using a 3D model and the Monoplotting Tool software, which also allowed us to identify the topographical variables that promoted resistance to change. The analysis of more than 1000 floristic inventories distributed over different landcover types allowed us to reveal winners and losers, as well as to infer the type of flora sheltered in long-term landcover refuges. The approach to the near future (climatic refugia) was analysed using thermal images taken by UAVs (drones) during heat waves, and exploring areas of narrow thermal range across thermal landscapes. Identifying environments where temperatures are buffered reveals climatic refugia, and allows investigation of topographic variables that create them. In turn, floristic inventories in these environments showed the type of flora that is protected in climatic refugia. Overall, the combination of approaches that explore past and future effects has allowed us to identify different types of refugia for biodiversity in harsh mountain landscapes.