Pollen-vegetation relationship in the Patagonian Andes of Argentina

FONTANA F., T. GIESECKE & S. ALISCIONI

Varna, Bulgaria

Congreso; 5th International Meeting of the Pollen Monitoring Programme (PMP); 2005

Museum of Natural History , Varna and Department of Botany, Biological Faculty of Sofia University, Bulgaria

The Patagonian Andes of Argentina today support temperate forests that extend as a narrow strip in a north-south direction for about 2000 km, between 37º S. to 55º S. The genus Nothofagus, (southern beech) is the most important component of the tree flora, comprising 90% of the forests. The upper tree limit is generally defined by Nothofagus pumilio (lenga), at about 1800 m above sea level in north Patagonia and at ca. 700 m asl in Tierra del Fuego. Above the treeline, mountaintops are characterized by alpine vegetation. The Patagonian steppe, with tussock grasses and shrubs, occurs at low elevations, to the east of the temperate forests. Modern-pollen vegetation relationships are studied in the mountain region of northern Patagonia, in the Lanín National Park, between 38.5° S to 40.5° S. This study is part of a major project that aims to reconstruct late-Quaternary vegetation history and alpine timberline fluctuations in the Patagonian Andes. Within the Lanín National Park, different types of forests occur along its latitudinal range, due to diverse climate, topography and soils. The northern region is characterized by pure forests of Araucaria araucana and mixed forests of Araucaria araucana, Nothofagus pumilio and Nothofagus antartica. The central and southern region of the Lanín National Park is dominated by mixed forests with Nothofagus alpina, Nothofagus obliqua and Nothofagus dombeyi. Forests of Austrocedrus chilensis occur to the southeast. The treeline ecotone is dominated by krummholz forms of Nothofagus pumilio with some Nothofagus antartica and Nothofagus betuloides. This study presents preliminary results of surface samples recovered from small lakes near the present timberline, obtained during the first field campaign (December 2004 – January 2005). Pollen assemblages from the diverse mountain vegetation types are analyzed in order to investigate to which degree the different communities can be distinguish by their pollen spectra. The results of this study will give a better understanding of pollen-vegetation relationship in mountain areas and can therefore assist interpretation of the fossil records.