Relationship between environmental change and human activities in the period of the Shijiahe culture, Tanjialing site, Jianghan Plain, China

A new 3.3-m long archaeological sedimentary profile from Tanjialing, Hubei Province, was examined for pollen, TOC, TN, and δ¹³Cₒᵣg content. The results contribute to a better understanding of the interaction between environment and human activities in the late Neolithic Jianghan Plain, discussed in the context of archaeological record and published available data. During the early Shijiahe culture (4.6–4.4 ka BP), a mixed broadleaved evergreen and deciduous forest, mainly consisting of evergreen Quercus, Pinus, Cyclobalanopsis, Liquidambar, and Ulmus, developed at Tanjialing. The high values of TOC, TN, and C/N suggests that the organic matter is mainly from allochthonous terrestrial plants. Combined with δ¹³Cₒᵣg analysis, C₃ plants occupied the area, and the climate was warm and humid, with less human disturbance during this period. The abrupt rise of TOC, TN and C/N content and decrease of δ¹³Cₒᵣg, combined with the local spread of Typha and Cyperaceae, show that this area witnessed a short-term water regime expansion event during the early period of the Shijiahe culture. In the mid-period of the Shijiahe culture (4.4–4.2 ka BP), a significant rise in herbs especially Poaceae and a remarkable decline in broadleaved trees imply an increasingly intensified human interference. The continuous decline of TOC, TN and C/N content indicates the reduction of allochthonous organic matter from terrestrial plants. All proxies' responses suggest decreasing effective moisture and temperature during this stage. In the early and middle period of the Shijiahe culture, the warm and wet climate was favorable for agriculture, which promoted the prosperity of the Shijiahe culture, and Shijiahe ancient city played an important role in the defense against flood and invasion. Chronic drought around 4.2 ka BP not only hindered the development of local agriculture, but also hindered the ditch system work, leading to the fall of the Shijiahe culture. The defense function of the ancient city vanished due to dry climate and groundwater decline: therefore, the ancient city was abandoned. The extreme events (flood, extreme drought etc.) related to the climate transformation played an important role in the legendary Yu Zheng Sanmiao War.