Vegetation changes in the Neotropical Gran Sabana (Venezuela) around the Younger Dryas chron |
| |
| Authors: | Encarni Montoya Valenti Rull Nathan D Stansell Broxton W Bird Sandra Nogué Teresa Vegas‐vilarrúbia Mark B Abbott Wilmer A Díaz |
| |
| Institution: | 1. Palynology and Palaeoecology Lab, Botanical Institute of Barcelona, Barcelona, Spain;2. Department of Animal Biology, Plant Biology and Ecology, Autonomous University of Barcelona, Campus Bellaterra, 08193 Barcelona, Spain;3. Byrd Polar Research Center, The Ohio State University, Columbus, OH, USA;4. Oxford Long Term Ecology Lab, Biodiversity Institute, Department of Zoology, South Parks Road, Oxford, UK;5. Department of Ecology, University of Barcelona, Barcelona, Spain;6. Department of Geology and Planetary Science, University of Pittsburgh, Pittsburgh, PA, USA;7. CIEG – UNEG, Puerto Ordaz, estado Bolivar, Venezuela |
| |
| Abstract: | The occurrence of the Younger Dryas cold reversal in northern South America midlands and lowlands remains controversial. We present a palaeoecological analysis of a Late Glacial lacustrine section from a midland lake (Lake Chonita, 4.6501 °N, 61.0157 °W, 884 m elevation) located in the Venezuelan Gran Sabana, based on physical and biological proxies. The sediments were mostly barren from ～15.3 to 12.7 k cal a BP, probably due to poor preservation. A ligneous community with no clear modern analogues was dominant from 12.7 to 11.7 k cal a BP (Younger Dryas chronozone). At present, similar shrublands are situated around 200 m elevation above the lake, suggesting a cooling‐driven downward shift in vegetation during that period. The interval from 11.7 to 10.6 k cal a BP is marked by a dramatic replacement of the shrubland by savannas and a conspicuous increase in fire incidence. The intensification of local and regional fires at this interval could have played a role in the vegetation shift. A change to wetter, and probably warmer, conditions is deduced after 11.7 k cal a BP, coinciding with the early Holocene warming. These results support the hypothesis of a mixed origin (climate and fire) of the Gran Sabana savannas, and highlight the climatic instability of the Neotropics during the Late Glacial. Copyright © 2011 John Wiley & Sons, Ltd. |
| |
| Keywords: | Fire Late Glacial Neotropics vegetation change Younger Dryas |
|
|
