Early human occupation and land use changes near the boundary of the Orinoco and the Amazon basins (SE Venezuela): Palynological evidence from El Pauji record

This paper shows a Holocene paleoecological reconstruction based on a peat bog sequence (El Pauji. 4 degrees 28'N-61 degrees 35' W, 865 m elevation) located in the transition zone between the Gran Sabana (SE Venezuela) savannas and the Amazon rainforests. Paleoecological trends are based on the analysis of pollen and pteridophyte spores, algal and animal remains, fungal spores, and charcoal particles. The whole record embraces the last ca. 8000 cal yr BP, and was subdivided into five pollen zones, representing the following vegetation succession: savanna/rainforest mosaic (8250-7715 yr BP), dense rainforests (7715-5040 yr BP), savanna/rainforest mosaic (5040-2690 yr BP). secondary dry forests (2690-1440 yr BP), and peat bog in an open savanna landscape (1440 yr BP-present). These vegetation changes have been attributed to the action of climate and/or land use changes, as well as the corresponding synergies between them. Fire has been determinant in the landscape evolution. Based on the reconstructed fire and vegetation shifts, a changing land use pattern could have been recognized. Between the early and the mid Holocene (ca. 8.3-5.0 kyr BP), land use practices seem to have been more linked to shiffing agriculture in a rainforest landscape - as is usual in Amazon cultures - with medium fire incidence affecting only local forest spots or surrounding savannas. More extensive forest burning was recorded between ca. 5.0 and 2.7 kyr BP, followed by land abandonment and the dominance of drier climates between 2.7 and 1.4 yr BP. The modern indigenous culture, which prefers open environments and makes extensive use of fire thus preventing forest re-expansion, seem to have established during the last 1500 yr. Therefore, a significant cultural replacement has been proposed for the region, leading to the present-day situation. Changing human activities have been instrumental for ecological evolution in this savanna-rainforest transitional region, as well as for the shaping of modern landscapes. (C) 2011 Elsevier B.V. All rights reserved.