A detailed pollen record of vegetation and climate changes in Central China during the past 16 000 years CHENG ZHU, CHUNMEI MA, SHI-YONG YU, LINGYU TANG, WENQING ZHANG AND XUEFENG LU BOREAS Zhu, C., Ma, C., Yu, S.-Y., Tang, L., Zhang, W. & Lu, X. 2010 (January): A detailed pollen record of vegetation and climate changes in Central China during the past 16 000 years. Boreas, Vol. 39, pp. 69–76. 10.1111/j.1502- 3885.2009.00098.x. ISSN 0300-9483. Detailed pollen analyses, along with magnetic and loss-on-ignition (LOI) measurements, were conducted on a 3 m long peat sequence recovered from the Dajiuhu Basin, the Shennongjia Mountains in Central China. Ten AMS 14 C dates provide a firm age control on this pollen record in terms of vegetation changes governed essentially by the rise and fall of the Asian summer monsoon during the past 16 000 years. Between 16 000 and 12 700 cal. yr BP, pollen assemblages were dominated by coniferous and broad-leaved trees, indicating a mixed forest landscape corre- sponding to the initial establishment of the monsoonal climate after the Last Glaciation. The progressive increases in percentages of evergreen tree pollen after 12 700 cal. yr BP point to a steady enhancement of the summer mon- soon, which was episodically weakened during the Younger Dryas stadial. From 11 000 to 6000 cal. yr BP, values of coniferous and deciduous tree pollen decreased, while evergreen broad-leaved tree pollen increased sub- stantially, implying a stronger than normal monsoonal climate condition corresponding to the Holocene Hyp- sithermal Interval. A great reduction in the values of evergreen tree pollen at about 4000 cal. yr BP indicates a sudden retreat of the summer monsoon from this area. Cheng Zhu and Chunmei Ma, School of Geographic and Oceanographic Sciences, Nanjing University, Nanjing 210093, P. R. China; Shi-Yong Yu (corresponding author; e-mail: syu2@tulane.edu) and Xuefeng Lu, State Key Laboratory of Loess and Quaternary Geology, Institute of Earth Environment, CAS, Xi’an 710075, P. R. China; Lingyu Tang, Nanjing Institute of Geology and Palaeontology, Chinese Academy of Sciences, Nanjing 210008, P. R. China; Wenqing Zhang, Institute of Hydrogeology and Engineering Geology Techniques, CGS, Baoding 071051, P. R. China; received 14th February 2008, accepted 11th May 2008. Climate conditions in the vast area of East Asia are regulated essentially by the monsoon circulation, a large-scale atmospheric pressure cell generated by the thermal contrast between the Eurasian landmass and the tropical oceans (Zhang & Lin 1992; Chao & Chen 2001). In winter, dry and cold northwestern winds ori- ginating from the Mongolian High prevail; conversely, warm and wet air-masses from the tropical Pacific dominate the area in the summer months. Seasonal changes in this large-scale wind pattern exert consider- able influence on hydrological cycling and thus human livelihood in the area. Given the archaeological fact that this area has been extensively colonized from the Neolithic Age onward (Zhu et al. 1997; Zhu 2005), studying past climate changes may provide a frame- work within which the rise and fall of human civiliza- tion during the Holocene can be better understood. Our knowledge of the history of the East Asian monsoon during the past glacial/interglacial cycles is mainly from loess-soil sequences (An 2000) and cave speleothem (Wang et al. 2001). Little is known about postglacial variations in the East Asian summer mon- soon in shorter time scales. Specifically, we are not sure whether the millennial-scale oscillatory pattern of sum- mer monsoon that prevailed during the Last Glaciation continued into the Holocene. Moreover, regarding the timing of postglacial strengthening of the summer monsoon on the Eurasian landmass, a synthesis of earlier published records reveals a time-transgressive or diachronous pattern, i.e. a stronger than normal mon- soonal climate occurred earlier in North China than in South China (An et al. 2000; He et al. 2004). According to recently published records with high resolutions and firm age constraints (Wang et al. 1999; Hong et al. 2005; Yancheva et al. 2007), this hypothesis is not convincing if the underlying forcing mechanism comes from the variation in summer solar insolation to the low lati- tudes through the changing position of the Inner tropi- cal convergence zone (Fleitmann et al. 2007). Reliable records from this area are therefore important in vali- dating this hypothesis. Given its unique geographical location (Fig. 1A), Central China is a key area for our understanding the spatial variability of the Asian summer monsoon sys- tem. An absolutely-dated cave speleothem d 18 O record from the eastern Shennongjia Mountains (Shao et al. 2006) gives only a general picture of changes in the Asian summer monsoon between 10 000 and 2000 years ago, and the history of the summer monsoon in this area beyond this period is unknown. Moreover, the speleothem record needs to be tested using other prox- ies. Ombrotrophic peatlands show promise as an excep- tional archive of climate and environmental changes in this area (Wang & Sun 1989; Zhao et al. 2007). Here, we present an AMS 14 C dated, high-resolution pollen record from a peatland in the Dajiuhu Basin on the western margin of the Shennongjia Mountains, Central China, to document vegetation and climate changes in DOI 10.1111/j.1502-3885.2009.00098.x r 2009 The Authors, Journal compilation r 2009 The Boreas Collegium