A 90,000-yr record of environmental change before 18,000 cal yr B.P. has been constructed using pollen analyses from a sediment core obtained from Salar de Uyuni (3653 m above sea level) on the Bolivian Altiplano. The sequence consists of alternating mud and salt, which reflect shifts between wet and dry periods. Low abundances of aquatic species between 108,000 and 50,000 yr ago (such as Myriophyllum and Isoëtes) and marked fluctuations in Pediastrum suggest generally dry conditions dominated by saltpans. Between 50,000 yr ago and 36,000 cal yr B.P., lacustrine sediments become increasingly dominant. The transition to the formation of paleolake "Minchin" begins with marked rises in Isoëtes and Myriophyllum, suggesting a lake of moderate depth. Similarly, between 36,000 and 26,000 cal yr B.P., the transition to paleolake Tauca is also initiated by rises in Isoëtes and Myriophyllum; the sustained presence of Isoëtes indicates the development of flooded littoral communities associated with a lake maintained at a higher water level. Polylepis tarapacana-dominated communities were probably an important component of the Altiplano terrestrial vegetation during much of the Last Glacial Maximum (LGM) and previous wet phases.
Bibliographical noteFunding Information:
We are grateful to Ian Lawson and Phil Hughes for undertaking the pollen preparations; to Hazel Lintott for drafting Figures 1 and 3 ; to J. Fjeldså, S. Beck, I. Hensen, and M. Kessler for discussion concerning Polylepis; and to Keith Bennett, Simon Crowhurst, and Maria Sánchez-Goñi for technical advice. We also thank two anonymous reviewers whose constructive comments significantly improved the manuscript. This work was supported by NSF grant ATM-9906107.
Copyright 2011 Elsevier B.V., All rights reserved.
- Polylepis tarapacana
- Salar de Uyuni
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