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Universidad de Chile Chili (2002)

Clima y vegetación del desierto de Atacama durante el cuaternario tardío, II región, Chile

Hidalgo Claudio Latorre

Titre : Clima y vegetación del desierto de Atacama durante el cuaternario tardío, II región, Chile

Auteur : Claudio Latorre Hidalgo

Université de soutenance : Universidad de Chile

Grade : Doctor en Ciencias con mención en Biología 2002

Résumé
This thesis presents the results obtained from a new paleoecological method specifically designed for use in the arid regions of the world. Known as rodent middens, these constitute veritable archives of past biological and climatic change of the Atacama Desert of northern Chile. The first chapter of this thesis presents the results obtained from eight altitudinal surveys performed in northern Chile between 18° and 26° latitude south. The results from this study afford the basic modern analogue for interpreting the midden records and also provide considerable insight into what climatic controls affect plant distributions in the Atacama Desert today. In the second chapter I present the results from 49 middens collected from Chile’s Second Region, the first such study in all of Chile. Results indicate that plants invaded considerable expansions of the desert for brief periods of increased summer rainfall during the past 45,000 years, radiocarbon dated between 13,800-9500 and 7000-3000 calendar years ago. The final chapter presents the results obtained from 44 rodent middens collected from the prepuna vegetation belt, between 3100-3400 m in elevation. The results from this study replicate and enhance our dating of the wet phases previously described. Results from both midden studies reject local insolation over South America as a major forcing factor of the intensity of atmospheric circulation over the central Andes for the past 22,000 years. This system today is partly affected by El Niño-Southern Oscillation, and we propose that sea surface temperatures changes of the tropical Pacific Ocean associated with extra-regional factors, are chiefly responsible for climate change over the central Andes.

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