Nothofagus forest dynamics and palaeoenvironmental variations during the mid and late Holocene, in southwest Patagonia

ECHEVERRÍA, MARCOS; SOTTILE, G.D.; MANCINI. M.M.; FONTANA, S.

HOLOCENE (SEVENOAKS)

SAGE PUBLICATIONS LTD

Lugar: London; Año: 2014

0959-6836

Southern Patagonia intersects the core of the Southern Westerlies, providing a unique opportunity for palaeo-reconstructions and the implicationof past wind variations. There is a strong link between the strength of the westerlies and precipitation, which impacts vegetation communities. Thepalaeoenvironmental changes that occurred since the middle Holocene to present days are reconstructed from a peat record recovered in PeninsulaAvellaneda (50°15′57″S; 72°50′33″W). Interpretations are based on pollen, charcoal and sediment analyses. Closed Nothofagus forest together with lowfire activity characterized the region during the period c. 5500?3500 cal. yr BP, related to an increased in precipitation through an intensification of thewesterlies. After 3500 cal. yr BP, shrub and grass communities became dominant at the expense of Nothofagus forest, suggesting a climatic shift to dryconditions, as a result of weaker westerlies. This patchy forest-steppe vegetation has favoured the occurrence of fire events. Subsequently, Nothofagusforest recovered for a short period between 2000 and 400 cal. yr BP. Then, major vegetation changes took place with the re-establishment of an openlandscape. The calculated moisture balance index allowed us to hypothesize about the relationship between westerlies fluctuation and El Niño SouthernOscillation (ENSO) anomalies during the mid and late Holocene.