CONICET | Buscador de Institutos y Recursos Humanos

This paper presents the main palaeoenvironmental results obtained from two sites located in the eastern(La Correntina peat bog) and southern (Terra Australis peat bog) sectors of the Lake Fagnano area, situatedat 54 S on the Tierra del Fuego island, at the southernmost extreme of Patagonia. Here, we providean overview of the postglacial ecosystem and vegetation dynamics on both slopes of the Fuegian Andesby combining palynological records of pollen and fungal remains analyses, supported by radiocarbondatings and multivariate statistics. The pollen data from the two sites indicate initial shrubby and herbaceousvegetation with scattered trees, under drier and colder climate conditions than today. Expansionof Nothofagus forest began about 11,200 cal BP in the Terra Australis area, while an open vegetation ofgrasslands and shrubs developed around La Correntina site by 11,500 cal BP followed by the establishmentof the forest-steppe ecotone after 9400 cal BP. These vegetation changes implied a modification ofthe climate toward warmer and drier climate conditions than present. At both sites, the predominance ofthe mycorrhizal Glomus was related to the presence of open ground grassland, indicating relatively drylocal conditions. Closed-canopy forests dominated the landscape after 6500 cal BP at Terra Australis, andafter 5000 cal BP at La Correntina, suggesting relatively cold and wet environmental conditions. However,the fungal assemblage in Terra Australis shows high abundances of epiphyllous Microthyriaceae,pointing that the Nothofagus trees grew closer than at La Correntina. These findings allows us to concludethat both mires have experienced dissimilar trends in the environmental evolution since Late-glacialtimes, probably due to their locations in two distinct flanks of the Andean range.