Environmental and vegetation dynamics in the forest of Orile-Owu, southwest Nigeria, from the last ~ 1,4 k cal yr BP

ABSTRACT Vegetation history of southwestern Nigerian forest during the past ~1,416 cal yr BP (534 - 644 AD) is reconstructed based on palynological data from a core from Awerele, wetland in Orile-Owu. Six palynological zones were stablished. Zone I (195-175 cm; ~1,416 cal yr BP) was a period marked by low value of charcoal particles associated with low frequency of Elaeis guineensis pollen. In Zone II (175-135 cm), the environment experienced wet conditions depicted by high percentage mainly of Cyperaceae and fern spores. Further, the arable weeds and E. guineensis increased values, showing the higher frequency of Margaritaria discoidea pollen grains, coupled with a low charcoal amount. Zone III (135-105 cm) to Zone VI (50-0 cm) were characterised by the increase of E. guineensis and raising of charcoal particles, followed by the presence of plants exploited for food and medicinal purposes, which may indicate enlarged local landscape disturbance, probably associated with humans’ activities. Archaeological evidence suggest that humans occupied the Orile-Owu area from ~ 412 cal yr BP (AD 1,538 - 1,635). The pollen data displayed the persistence of a forest-savanna mosaic, associated with ecological perturbations, which were also noticed in other parts of sub-saharan Africa on the same period.