Interacció entre clima i ocupació humana en la configuració del paisatge vegetal del Parc Nacional d’Aigüestortes i Estany de Sant Maurici

The vegetation of the National Park of Aigüestortes and Lake of Sant Maurici is the result of an interaction process between climate, plant community dynamics and the human occupation of the territory. The OCUPA project aims to reconstruct this interaction ovar the last millennia using methods of palaeoecolagy and archaeology. Here, we describe the main features of the project and summarize the results obtained so far. The study focuses primarily on the Sant Nicolau valley and bases on the multidisciplinary analysis of the sedimentary archive of two lakes (LLebreta and Redó) and a number of archaeological sites located in shelters and outdoors. There is archaaological evidence of human presence since 9.000 yr cal BP. and a continuous record since 7.500 yr cal BP. At early stages, they transformad the surroundings of the shelters occupied and lithic tools indicate contacts with areas as lar as the Ebro plains. Since the Bronze Age (ca. 4,300 yr cal BP) there has been human impact on the vegetation without interruption until present. Initialty, the impacts were mostly related to livestock: use of fire to open grassing areas, soil erosion and, during the medieval period, forestry and water eutrophication of lakes. The agricultura impact in lhe lower part of the valley (e.g., Llebreta) occurred about 2,100 yr ago, although some cereal grains and tools for harvesting have been found from the Neolithic. In the medieval period, the impact was much higher than during the last centurias. In general, it can be concluded that changes in the human land use approximately follow the major changes in climate, but the specific causal link is likely to be related to the social and cultural dynamics of a broader territory since the Neoliihic.