Holocene human occupation of the eastern Nigerian scarp lands:An impact assessment study

摘要

Palynological results from the 3000 BC archaeological sites on the Udi-Okigwe plateau have shown evidence of deforestation linked to two human activities: iron smelting, and agriculture with bush burning. The purpose of this paper is to use the palynomorphs recovered from the excavated cave deposits to assess the climate as well as vegetation change from tree- to grass-type, given the presence nearby, of hand-axe factories and iron-smelting sites; and to assess the impact of human activities on the environment during the Holocene. Pollen of plants associated with human impact was used to assess human influence on the vegetation. Despite climatic wetness indicated by fungal, club moss and fern spores, there was an increase in grass pollen resulting from human forest clearance which caused artificial environmental aridity rather than a true climate change. Selective felling of hard wood for fuel in the iron-smelting industry could have left open spaces which were colonized by the palm, Elaeis guineensis, to produce the 'oil-palm bush' anthropogenic climax vegetation. The itinerant mode of practice by the smelters must have caused an extensive devastation of the rainforest as the lateritic subsoil was dug up and the hardwood selectively felled from place to place. The caves, hand-axe quarry and factory sites, as well as iron-smelting sites are all closely situated along the plateau.