Holocene vegetation changes in the Sahelian zone of NE Nigeria: The detection of anthropogenic activity

Waller, Martyn and Salzmann, Ulrich (1999) Holocene vegetation changes in the Sahelian zone of NE Nigeria: The detection of anthropogenic activity. In: Palaeoecology of Africa and the Surrounding Islands. PALAEOECOLOGY OF AFRICA AND THE SURROUNDING ISLANDS, 26 . A A Balkema, Leiden, Netherlands, pp. 85-102. ISBN 9789054104766

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Abstract

The relative importance of climate change and anthropogenic activity in the vegetation history of the Sahel has been the subject of much recent discussion. Pollen diagrams from the Manga Grasslands (NE Nigeria) indicate a Holocene vegetation history primarily controlled by climate. During the relatively humid early and mid-Holocene the interdune depressions of the Mangas were occupied by swamp forest with Guinean affinities. Savanna, with Sudanian and Sahelian arboreal elements, occurred on the surrounding dunefields. The modem Sahelian vegetation of the region became established c.3300 yr BP as a result of drier conditions. Although the archaeological record indicates that the Manga Grasslands themselves have been occupied since at least c.3700 yr BP, there is little evidence of human activity in the pollen diagrams. The number of herb taxa recorded declines after c.3300 yr BP and unambiguous indicators of human activity are absent even from a diagram which covers the recent past. The drier post c.3300 yr BP conditions are probably masking human activity. In addition, nomadic pastoralism (which is still the major economic system) appears to be palynologically undetectable, the major effect of this activity today being the replacement of perennial grasses and herbs with more xeromorphic and less palatable species.

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