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Title

Vegetation changes in the Neotropical Gran Sabana (Venezuela) around the Younger Dryas Chron

AuthorsMontoya, Encarnación ; Rull, Valentí ; Stansell, Nathan D.; Bird, Broxton W.; Nogué, Sandra; Vegas-Vilarrúbia, Teresa ; Abbott, Mark B.; Díaz, Wilmer A.
KeywordsFire
Late Glacial
Neotropics
Vegetation change
Younger Dryas
Issue Date2011
PublisherJohn Wiley & Sons
CitationJournal of Quaternary Science 26: 207-218 (2011)
AbstractThe 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.
URIhttp://hdl.handle.net/10261/77093
DOI10.1002/jqs.1445
ISSN0267-8179
Appears in Collections:(IBB) Artículos
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