Mid to late Holocene environmental change and human impact: A view from Central China

Abstract

Abstract Dajiuhu, a rare peatland in Central China, has attracted several studies. There are differences in the interpretations of its Holocene record, and little has been written on landscape transformation by human impact. A 6100\u202fyr palynologic record, together with TOC and charcoal data, from Dajiuhu peatland is assessed to provide a new perspective on mid-late Holocene environmental change and human activity. We found that wetland herb pollen is a sensitive marker of effective precipitation, and the ratio of evergreen and deciduous tree pollen can be a proxy for temperature variability at the site. A mixed evergreen and deciduous forest dominates the record. Peak warming was at 2900\u202fcal\u202fyr BP and cool events occurred around 5100, 4100 and 2700\u202fcal\u202fyr BP. The cooling at 5100 and 2700\u202fcal\u202fyr BP may be related to decreased solar activity. There was a long-term drying trend punctuated by episodic droughts around 3000 to 2800\u202fcal\u202fyr BP and following 1500\u202fcal\u202fyr BP; we argue that these relate to the southward retreat of the ITCZ. A low level of regional fires was present as background. At 800\u202fcal\u202fyr BP there were declines in forest taxa, increases in ferns, herbs, burning and inorganic inputs into the sediment; these signal sustained human impact in the area. The relatively late human impact is probably related to the rugged mountain landscape and river systems prone to frequent flooding, or may be due to a late expansion in human population and land resource pressures at Dajiuhu.