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Acta Amazonica

Print version ISSN 0044-5967

Acta Amaz. vol.41 no.4 Manaus  2011


Scientists confirmed dryer climate at the Early-Mid Holocene in the Northeastern Orinoco savannas



A group of researchers from Universidad Simón Bolívar and Instituto Venezolano de Investigaciones Científicas conducted a reconstruction of the vegetation dynamics and climate trends during the Early Holocene of a Mauritia flexuosa (Arecaceae) swamp, in the Eastern Venezuelan Llanos of the Orinoco Basin. This paleocological study support the existence of a dry phase between 8.000 to 2.500 years BP, which is consistent with the Early-Mid Holocene Dryness, widely documented in the Amazon Basin and neighboring areas, implying that the dry climate at that time could have had a more regional impact than previously thought.

This discovery, published in the scientific journal "Acta Amazonica" vol. 41 n. 4 of 2011, with the title: "Contribution to Early Holocene vegetation and climate history of Eastern Orinoco Llanos, Venezuela, from a paleoecological record of a Mauritia L.f. swamp" revealed also the occurrence of a previous humid phase between 10.000 to 8.000 years BP. The radiocarbon dates and pollen analysis in sediments obtained from the core collected in the swamp indicate the species Mauritia flexuosa (Arecaceae) was virtually absent in both phases of Early Holocene, although the climate between 10.000 to 8.000 years BP was similar to present. These results suggest the relatively recent occupation of this important palm in the Orinoco savannas.

This project was funded by the Decanato de Pregrado and by the Laboratory of Community Dynamics and Ecological Process (LABPROECO) of Simon Bolivar University. The preparation of samples for radiocarbon dates was done in the Stable Isotope Laboratory, University of California (Irvine), under the supervision of Susan Trumbore, and radiocarbon dates were determined at the Center for Accelerator Mass Spectrometry, Lawrence Livermore National Laboratory, USA.



Alejandra Leal
Laboratorio de Dinamica de Comunidades y Procesos Ecologicos
Universidad Simón Bolívar

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