Late Holocene Climate and vegetation changes in high Andean mediterranean Chile (32°S)

MALDONADO, A.; MARTEL-CEA, A.; SCHITTEK, K.; DE PORRAS, M.E.; GROSJEAN, M.

Medellín

Simposio; LOTRED-SA 3rd International Symposium; 2014

The understanding of the climate of a particular zone needs a long term picture that allows elucidating modern climatic trends, broad scale cycles, climatic variability and climate change mechanisms (natural or anthropic). Palaeoclimatic data allow the validation of the general circulation models outputs while providing clues to picture modern and future climatic scenarios for the models through the establishment of past environmental analogs. According to future IPCC climate predictions, Mediterranean Chile (30-34°S) is one of those areas in the world which are experimenting a strong aridification trend as a consequence of the ongoing climatic change. If this trend continues, critical economic and social future scenarios will arise in Mediterranean Chile given that it is a densely populated zone with extensive industrial and agriculture development.Mediterranean Chile appears therefore as an extremely vulnerable area to climatic change so understanding its natural climatic variability emerge as crucial to picture future scenarios. Despite that water resources for this densely populated area originate from high Andean basins, most paleoclimatical studies from Mediterranean Chile have been developed in lowlands. Therefore, the present paper presents a high Andean lake pollen record (3600 masl) fromMediterranean Chile (31º40?S; 70º30?W) characterized by finely laminated sediments encompassing the last 4.8ka. Between 4.8 and 2.1ka, low Andean vegetation occurred around the lake dominated by Fabaceae (Adesmia-type, 40%) and associated with Calandrinia (20-10%), Spergularia (2-15%) and Brasicaceae (2-10%). Around 2.1ka, a decrease of Fabaceae (0-23 %) point out the replacement of low by high Andean vegetation. Fluctuating values of Fabaceae (Adesmia type),Calandrinia, Azorella and Senecio-type pin point variable environmental conditions from 2.1ka to the present. The replacement of low to high Andean vegetation around 2.1ka suggest an effective moisture increase which is regionally recorded and therefore suggest a strong climatic variability synchrony between low and highland in Mediterranean Chile. Acknowledgements: FONDECYT #1100916; #1140837. Minera Los Pelambres