Wood types and human impact between 4300 and 2400 yr BP in the Hexi Corridor,NW China,inferred from charcoal records

Abstract

Based on identification of fossil charcoals from 11 sites in the Hexi Corridor, we reconstruct the local vegetation community and human impact on it in the period from 4300 to 2400 cal. yr BP. More than 20 broadleaved taxa and 4 coniferous trees are present. The charcoal identifications show that vegetation in the period 4300–2400 cal. yr BP differed regionally because of variations in local topography and water supply, with limited diversity in the northwest Hexi Corridor and relatively rich diversity in the southeast area. In the northwest Hexi Corridor, the oasis woodland consisted mainly of Tamarix sp., Salix sp., and Populus sp. In the southeast region, the vegetation was a mix of coniferous forest and broadleaf woodland. By comparison with modern patterns of vegetation, broadleaf trees were much more abundant and the spruce forest extended down to relatively low altitudes, suggesting greater vegetation cover and richer diversity than today. There was also temporal variation. In the period from 4300 to 4000 cal. yr BP, woodland was relatively scarce, while the greatest diversity of plants appears in the period from 4000 to 3500 cal. yr BP, probably because of better moisture conditions at that time. After 3500 cal. yr BP, there was the appearance of woodland dominated by Morus alba, suggesting that cultivated trees may have played a key role in the lives of local people.