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| Titel |
Late Holocene plant and climate evolution at Lake Yoa, northern Chad: pollen data and climate simulations |
| VerfasserIn |
A.-M. Lézine, W. Zheng, P. Braconnot, G. Krinner |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1814-9324
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| Digitales Dokument |
URL |
| Erschienen |
In: Climate of the Past ; 7, no. 4 ; Nr. 7, no. 4 (2011-12-09), S.1351-1362 |
| Datensatznummer |
250004692
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| Publikation (Nr.) |
 copernicus.org/cp-7-1351-2011.pdf |
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| Zusammenfassung |
| The discovery of groundwater-fed Lake Yoa (19.03° N, 20.31° E) in
the hyperarid desert of northern Chad by the German research team ACACIA
headed by S. Kröpelin provides a unique, continuous sedimentary sequence
of late Holocene age available in the entire Saharan desert. Here we present
pollen data and climate simulations using the LMDZ atmospheric model with a
module representing the climatologically-relevant thermal and hydrological
processes occurring above and beneath inland water surfaces to document past
environmental and climate changes during the last 6000 cal yr BP. Special
attention is paid to wind strength and direction, length and amplitude of
the rainy season, and dry spell occurrence, all of which are of primary
importance for plant distribution and pollen transport. In addition to
climate changes and their impact on the natural environment, anthropogenic
changes are also discussed. Two main features can be highlighted: (1) the
shift from an earlier predominantly monsoonal climate regime to one
dominated by northern Mediterranean fluxes that occurred after 4000 cal yr BP.
The direct consequence of this was the establishment of the modern desert
environment at Yoa at 2700 cal yr BP. (2) Changes in climate parameters
(simulated rainfall amount and dry spell length) between 6 and 4000 cal yr BP
were comparatively minor. However, changes in the seasonal distribution
of precipitation during this time interval dramatically affected the
vegetation composition and were at the origin of the retreat of tropical
plant communities from Lake Yoa. |
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