Open Access

Ulrich Salzmann

• Numerous ecologists postulate that West African savannas are mostly the result of degradation of formerly closed forests. This hypothesis can only be tested by palaeoecological investigations. The palynological results summarised in this paper document the history of the Sudanian and Sahelian savanna of NE-Nigeria during the last 11.500 years (uncal. BP). Both sites investigated provide evidence for the persistence of savanna throughout the entire Holocene. Patches of closed dry forest may have occurred, but never completely displaced the savanna vegetation. Humid conditions during the early and mid Holocene (from 10.000 BP onwards) caused a rapid spread of Guinean and Sudanian taxa into the northern vegetation zones. A slow return to drier climatic conditions between ca. 6800 BP and ca. 5500 BP can be recorded at both sites. Finally, between 3800 BP and 3300 BP a strong aridification resulted in the establishment of the modern vegetation zones. In both the Sahelian and Sudanian zone the vegetational changes appear to have been primarily controlled by climatic changes, whereas the effects of human activities remain palynologically silent even for the late Holocene.