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| Titel |
Simulated effects of a seasonal precipitation change on the vegetation in tropical Africa |
| VerfasserIn |
E. S. Gritti, C. Cassignat, O. Flores, R. Bonnefille, F. Chalié, J. Guiot, D. Jolly |
| 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 ; 6, no. 2 ; Nr. 6, no. 2 (2010-03-30), S.169-178 |
| Datensatznummer |
250003442
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| Publikation (Nr.) |
 copernicus.org/cp-6-169-2010.pdf |
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| Zusammenfassung |
| Pollen data collected in Africa at high (Kuruyange, valley swamp, Burundi)
and low altitude (Victoria, lake, Uganda; Ngamakala, pond, Congo) showed that
after 6 ky before present (BP), pollen of deciduous trees increase their
relative percentage, suggesting thus the reduction of the annual amount of
precipitation and/or an increase of in the length of the dry season. Until
now, pollen-climate transfer functions only investigated mean annual
precipitation, due to the absence of modern pollen-assemblage analogs under
diversified precipitation regimes. Hence these functions omit the potential
effect of a change in precipitation seasonality modifying thus the length of
the dry season. In the present study, we use an equilibrium biosphere model
(i.e. BIOME3.5) to estimate the sensitivity of equatorial African
vegetation, at specific sites, to such changes. Climatic scenarios, differing
only in the monthly distribution of the current annual amount of
precipitation, are examined at the above three locations in equatorial
Africa. Soil characteristics, monthly temperatures and cloudiness are kept
constant at their present-day values. Good agreement is shown between model
simulations and current biomes assemblages, as inferred from pollen data. To
date, the increase of the deciduous forest component in the palaeodata around
6 ky BP has been interpreted as the beginning of a drier climate period.
However, our results demonstrate that a change in the seasonal distribution
of precipitation could also induce the observed changes in vegetation types.
This study confirms the importance of taking into account seasonal changes in
the hydrological balance. Palaeoecologists can greatly benefit from the use
of dynamic process based vegetation models to acccount for modification of
the length of the dry season when they wish to reconstruct vegetation
composition or to infer quantitative climate parameters, such as temperature
and precipitation, from pollen or vegetation proxy. |
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