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

Anne-Marie Lezine, Kévin Lemonnier, Martyn Waller, Ilham Bouimetarhan, Lydie Dupont, African Pollen Database contributors, Ulrich Salzmann

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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.
Original languageEnglish
Title of host publicationQuaternary Vegetation Dynamics
Subtitle of host publicationThe African Pollen Database
EditorsJürgen Runge, William D. Gosling, Anne-Marie Lézine, Louis Scott
Place of PublicationLondon
PublisherCRC Press
Number of pages20
ISBN (Electronic)9781003162766
ISBN (Print)9780367755089
Publication statusPublished - 29 Nov 2021

Publication series

NamePalaeoecology of Africa: International Yearbook of Landscape Evolution and Palaeoenvironments


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