The Picos de Europa socio-ecosystem research platform (LTSER-Picos de Europa) comprises the catchment areas of the Sella (1,284 km², average annual Q 30 m3/s) and Deva-Cares (1,187 km², average annual Q 40 m3/s) rivers that drain the Cantabrian Mountains towards the Cantabrian Sea. The Picos de Europa National Park is located in this area and it was the first National Park declared in Spain (1918). The LTSER-Picos de Europa has a maximum altitude of 2,648 m (Torres Cerredo). The average annual temperature varies between 6ºC (mountainous areas) and 15ºC (coast), while the average annual rainfall varies between 800 mm (Liébana, Cantabria) and 3,000 mm. It is dominated by broadleaf forests >grasslands>shrublands>rocky areas and contains the bio-climatic floors: Hill (0-700 m, crops and eucalyptus), Montane (500-1,100 m, oak and beech) and Subalpine (>1,100 m, birch, mountain pasture and cryosphere). It is a very interesting biogeographical area as it represents the convergence between the Mediterranean and Atlantic biomes. LTSER-Picos de Europa contains 5 SPAs and 9 SACs (Habitats Directive), where 40 habitats and 80 species of Community Importance have been described. The Picos de Europa National Park is practically the only populated National Park in Spain (20 towns; 1,100 inhabitants), although without large urban centres. LTSER-Picos de Europa contains a great deal of reprensentativity of the rural space of the Cantabrian Mountains. Human activities range from the production of hydroelectric energy, to different activities of the agro-livestock sector, tourism and other services.
The history of the LTSER-Picos de Europa is very recent, however, many interdisciplinary teams and national and international researches have been investigating in the area for more than half a century. The main objective of the LTSER-Picos de Europa is to improve our knowledge of the effects of global change on mountain socio-ecosystems. Our more specific objectives are: (1) to Identify mountain socio-ecological dynamics and patterns at large temporal and different spatial scales, (2) identify the main factors of global change that govern these dynamics and patterns, (3) determine the main relationships between the different components that make up mountain socio-ecosystems and (4) predict and model the future responses of the studied components under different scenarios of global change.