| The Holocene epoch, the latest global climate warming trend, has been regarded as the geological history with the close relationship to human, when prehistoric civilization generated and developed due to the relative stable and appropriative climate setting. However, the Holocene climatic variability has been proved recently by substantial evidences, showing centennial-millennial pacing period and abrupt climate-change events. Interestingly, the abrupt climatic events and the decline of ancient civilization occurred nearly coeval. Therefore, the research, concerning impacts of abrupt climatic change on the collapse of the early civilization, has become a hotspot topic in the field of interactive human and environment in Holocene.The Liangzhu civilization was born in the Yangtze Delta, while a "culture break-up" prevailed as a large number of the late-stage Liangzhu sites and the subsequent historical sites named "Maqiao" waned down around4.0kaBP. Was the result of the abrupt climatic change or coincidence in date merely, or there were of even other factors? This study, concerning the decline of the Liangzhu civilization due to the climate change and regional topographic response, will discuss the content further regarding the relationship between abrupt climate change and decline of ancient civilization as a peculiar case.The Qian-Mu-Tian bog is located on the Tian-Mu Mountain, northern Zhejiang Province. It is an ideal area to regain the signal of the paleo-climate record owning to far less away from human disturbance with consecutive peaty deposition, which has been proved by our field work and the previous investigation. Reliable dating materials were obtained in the sediments including plant debris, seeds and charcoal, which fit the dating materials for AMSI4C. Additionally, there were numerous the Liangzhu sites excavated in the Taihu Lake area, and therefore, the study area has taken the potential advantages to reveal the relationship between abrupt climatic change and the decline of the early civilization in the Yangtze delta.This paper will reconstruct the climatic history via the Qian-Mu-Tian bog peat from5.3cal. ka BP, firstly, on the basis of AMS14C dating. Then, the paper combines previous research achievements regarding climate change and sea level rise as well as a large number of the Liangzhu sites to analyze the climate-related impacts on the decline of the Liangzhu civilization. It concludes as follows:1. Characteristics of climate setting in the Taihu Lake area around5.3～4.2cal. ka BPThe chronological age of the bottom deposition is at5.3～4.2cal. ka BP in the Qian-Mu-Tian bog peat, which corresponds to the decrease of monsoon precipitation in East Asian. This probably initiates the formation of the bog peat. The characteristics of climate setting, as recorded by Qian Mutian peat layers, gradually dried after4.2cal. ka BP, particularly, being moderate wet at4,2～3,2cal. ka BP while comparing the upper phase, showing dry and wet for3,2～0.4cal. ka BP and0.4cal. ka BP, respectively. This demonstrates that the climate during the collapse of the Liangzhu civilization was changed towards a dry setting.2. Special characteristics of the Liangzhu sites in the Taihu Lake areaThis paper catalogued156Liangzhu sites from approximate400Liangzhu sites in the study area. These sites divided into the early-, middle-and late-stage of the Liangzhu culture, were plotted against the delta geography, via a tempo-spatial analysis by using ArcGIS9.3.(1) Characteristics of the sites number. The site numbers of the different stages of the Liangzhu culture indicate the rising trend from the initial-stage to late-stage slightly, while the growth rate dropped significantly. The accumulation characteristics of the different stages manifested that the proportion of the late-stage and mid-late-stage sites were higher compared to the early-stage and middle-stage sites as well as the earl-stage and late-stage sites.(2) Special characteristics. The majority Liangzhu sites were located in the north of the Qiantang River, the south of the Yangtze River delta and the east of the Ningzhen Mountain. These were not scattered, conversely, concentrated in some special areas as follows:①Changzhou-Jiangyin-Zhangjiagang-Wuxi;②Suzhou-Kunshan-Qinpu;③Jiaxing-Haining-Pinghu;④Pingyao-Liangzhu.(3) Migration characteristics:the majority Liangzhu sites stretched to southwestward and northeastward from the initial-to middle-stage and from the mid-to late-stage respectively. Particularly, the late-stage Liangzhu sites migrated on to the sandy Chenier ridges parallel to the coastline of the Yangtze delta plain. 3. Climate transformation and topographic response to the decline of Liangzhu civilization(1) Collected110paleoclimate and paleoenvironment records from84locations in China were employed to discuss the spatial characteristics of the climate change around4.0ka BP and its possible impacts on the transformation and collapse of the Neolithic culture of China (CNCC). The results indicate that cooling climate characterized by temperature decline prevailed for the most regions of China and the humidity exhibited some diversity. Dry and fairly drier conditions prevailed in the northern and northwestern arid regions, as well as the most places of southwestern and eastern monsoonal regions. A few records from the central Loess Plateau and the lower Yangtze River regions showed some extent humidity increase characterized by flood events. Humidity increases and accelerated soil erosion in some places around4.0ka BP, probably due to the amplified seasonal deviations of monsoon precipitations could result from the high El Nino-Southern Oscillation (ENSO) variability around5.0～4.3cal. ka BP.(2) The decline of the Liangzhu civilization was backed by the gradual dry climate, and the high precipitation variability, while these coevally happened with the expansion of limonization of the Taihu Lake at about4.0ka BP. Therefore, this paper proposes that integrated factors, including the drying climate setting, the high rainfal variability in relation to ENSO oscillation, and the expansion of the Taihu Lake wetlands coastal siltation and sea level rise, together, had played an important role in declining the Liangzhu culture in the Yangtze delta plain. |
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