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Millennial-Scale Dynamics of Southern Amazonian Rain Forests
Francis E. Mayle,1*Rachel Burbridge,1Timothy J. Killeen23
Amazonian rain forest-savanna boundaries are highly
sensitive to climatic change and may also play an important role in
rainforest speciation. However, their dynamics over millennial timescales are poorly understood. Here, we present late Quaternarypollen
records from the southern margin of Amazonia, which showthat the humid
evergreen rain forests of eastern Bolivia havebeen expanding southward
over the past 3000 years and that theirpresent-day limit represents
the southernmost extent of Amazonianrain forest over at least the past
50,000 years. This rain forestexpansion is attributed to increased
seasonal latitudinal migrationof the Intertropical Convergence Zone,
which can in turn be explainedby Milankovitch astronomic forcing.
1 Department of Geography, University of
Leicester, Leicester LE1 7RH, UK.
2 Center for
Applied Biodiversity Science, Conservation International, 2501 M
Street, NW, Suite 200, Washington, DC 20037, USA.
3 Museo de Historia Natural "Noel Kempff
Mercado," Avenida Irala 565, Casilla 2489, Santa Cruz de la Sierra,
Santa Cruz, Bolivia.
*
To whom correspondence should be addressed. E-mail:
fem1{at}leicester.ac.uk
