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

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

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, 884m elevation) located in the Venezuelan Gran Sabana, based on physical and biological proxies. The sediments were mostly barren from ∼15.3 to 12.7k cal a BP, probably due to poor preservation. A ligneous community with no clear modern analogues was dominant from 12.7 to 11.7k cal a BP (Younger Dryas chronozone). At present, similar shrublands are situated around 200m elevation above the lake, suggesting a cooling-driven downward shift in vegetation during that period. The interval from 11.7 to 10.6k 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 11.7k 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.

Fire, Late Glacial, Neotropics, Vegetation change, Younger Dryas
0267-8179
207-218
Montoya, Encarni
7f93c60f-cc9c-4c5f-bb43-e42a38872e8e
Rull, Valenti
afd31aba-0540-4788-abea-f5f9e3ec3021
Stansell, Nathan D.
8ed1c662-7ce3-4b24-9b2c-1143c217fc49
Bird, Broxton W.
917f1f0a-764f-4edb-af06-74c3692711a4
Nogué, Sandra
5b464cff-a158-481f-8b7f-647c93d7a034
Vegas-Vilarrúbia, Teresa
f1a5df04-58b9-4d16-823c-47c193f63f01
Abbott, Mark B.
3cc55c60-688c-4438-86af-896856f75e07
Díaz, Wilmer A.
7363a624-f9ba-4c9d-bedd-e89cadf8f973
Montoya, Encarni
7f93c60f-cc9c-4c5f-bb43-e42a38872e8e
Rull, Valenti
afd31aba-0540-4788-abea-f5f9e3ec3021
Stansell, Nathan D.
8ed1c662-7ce3-4b24-9b2c-1143c217fc49
Bird, Broxton W.
917f1f0a-764f-4edb-af06-74c3692711a4
Nogué, Sandra
5b464cff-a158-481f-8b7f-647c93d7a034
Vegas-Vilarrúbia, Teresa
f1a5df04-58b9-4d16-823c-47c193f63f01
Abbott, Mark B.
3cc55c60-688c-4438-86af-896856f75e07
Díaz, Wilmer A.
7363a624-f9ba-4c9d-bedd-e89cadf8f973

Montoya, Encarni, Rull, Valenti, Stansell, Nathan D., Bird, Broxton W., Nogué, Sandra, Vegas-Vilarrúbia, Teresa, Abbott, Mark B. and Díaz, Wilmer A. (2011) Vegetation changes in the Neotropical Gran Sabana (Venezuela) around the Younger Dryas chron. Journal of Quaternary Science, 26 (2), 207-218. (doi:10.1002/jqs.1445).

Record type: Article

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, 884m elevation) located in the Venezuelan Gran Sabana, based on physical and biological proxies. The sediments were mostly barren from ∼15.3 to 12.7k cal a BP, probably due to poor preservation. A ligneous community with no clear modern analogues was dominant from 12.7 to 11.7k cal a BP (Younger Dryas chronozone). At present, similar shrublands are situated around 200m elevation above the lake, suggesting a cooling-driven downward shift in vegetation during that period. The interval from 11.7 to 10.6k 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 11.7k 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.

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More information

Published date: 1 February 2011
Keywords: Fire, Late Glacial, Neotropics, Vegetation change, Younger Dryas

Identifiers

Local EPrints ID: 445890
URI: http://eprints.soton.ac.uk/id/eprint/445890
ISSN: 0267-8179
PURE UUID: 35674132-2154-44b6-884c-0442ada10e08
ORCID for Sandra Nogué: ORCID iD orcid.org/0000-0003-0093-4252

Catalogue record

Date deposited: 13 Jan 2021 17:31
Last modified: 18 Feb 2021 17:25

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Contributors

Author: Encarni Montoya
Author: Valenti Rull
Author: Nathan D. Stansell
Author: Broxton W. Bird
Author: Sandra Nogué ORCID iD
Author: Teresa Vegas-Vilarrúbia
Author: Mark B. Abbott
Author: Wilmer A. Díaz

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