Changes in the West African landscape at the end of the African Humid Period

Lézine, Anne-Marie, Lemonnier, Kévin, Waller, Martyn P., Bouimetarhan, Ilham, Dupont, Lydie, African Pollen Database contributors, and Salzmann, Ulrich (2021) Changes in the West African landscape at the end of the African Humid Period. In: Quaternary Vegetation Dynamics – The African Pollen Database. Palaeoecology of Africa: International Yearbook of Landscape Evolution and Palaeoenvironments . CRC Press, London, pp. 65-84. ISBN 9780367755089, 9781003162766

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Existing pollen datasets from northern Africa stored in the African Pollen Database were used to assess changes in landscape physiognomy at the end of the African Humid Period (AHP) from 5000 cal yr BP to the present using arboreal pollen percentages. The thirty-six sites available were used to map changes in arboreal cover at a sub-continental scale. Based on their location in present-day forested and non-forested areas and their relatively higher temporal resolution eight of them were selected to examine the timing and amplitude of the vegetation response in more detail, and particularly in the Sahel. In spite of low pollen production and dispersal of many tropical plants, which lead to the under representation of most of the trees relative to their abundance in the landscape, we were able to distinguish the geographical pattern and timing of vegetation changes. The landscape response to the end of the AHP was far from homogeneous particularly in the Sahel where a clear east-west gradient of changing tree cover is indicated with the central Sahel being notably species poor. In areas where forests were well developed during the AHP, i.e. in the south and west, the establishment of the modern landscape was abrupt with a threshold crossed between 3300 and 2500 cal yr BP according to local conditions. Elsewhere in northern Africa the switch from tree (C3) to grass (C4) dominated landscapes occurred more gradually during the same period. This review shows that the timing of the ecosystem response at the end of the AHP was remarkably synchronous throughout northern Africa.

Item Type: Book Section
Additional Information: Funding information: This work contributes to the ACCEDE ANR Belmont Forum project ((18 BELM 0001 05). Thanks are due to M.J. Gaillard (Kalmar University, Sweden) for constructive comments on the manuscript and the African Pollen Database for data access. AML and KL are funded by CNRS,LD by the University of Bremen and IB by the BMF grant PMARS2015-100.
Subjects: F800 Physical and Terrestrial Geographical and Environmental Sciences
Department: Faculties > Engineering and Environment > Geography and Environmental Sciences
Depositing User: John Coen
Date Deposited: 10 Feb 2022 11:33
Last Modified: 16 Dec 2022 15:00

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