长江中下游地区新石器文化时期的植被、环境和人类活动特征研究

Holocene environmental changes consist of natural variability and human activities. In the context of the current global warming, the human-nature relationship becomes a hot topic in the global change researches due to worldwide concerns for our environment deterioration. The middle and lower reaches of the Yangtze River in China is an ideal area to investigate the human-nature relationship because it is located in the typical Asian monsoon realm sensitive to climate change and it is a key place where Neolithic rice cultures originated and developed. This study use well- dated fine lake sediments from Lake Dongting, Lake Poyang, etc. for high-resolution pollen, phytolith, and charcoal analyses in order to reconstruct and interpret vegetation history, fire regime and climate changes. Furthermore, we focus on the two centers of Neolithic rice-dominated cultures, that is, Liyang Plain in Human Pronvince and Puyang River drainage in Zhejiang Pronvince,to make pollen, phytolich and charcoal analyses for representative and less-disturbed archaeological profiles. Key indicators of human impact will be used to discuss anthropogenic influence on vegetation and environment. Emphasis will be laid on to reveal the detailed process of human activities and to discern the different response of vegetation disturbance and environment change to changing rice practices from the "slash-and-burn" to "plough cultivation". We will make comparison of environment variation in its relation to rice agricultures to discuss the spatial-temporal changes of the human-nature relationship in the middle and lower reaches of the Yangtze River and their driving mechanisms. Our research will contribute to understanding the prehistoric human-nature relationship and to predicating the future environment change in the study area.

全新世环境变化受自然变化和人类活动共同作用和影响，在当今全球变暖背景下，关注人类生存环境，探讨两者相互关系是目前全球变化研究紧迫的热点科学问题。我国长江中下游地区地处典型东亚季风环境变化敏感区，又是新石器稻作文化起源和发展的核心区，是研究人地关系的理想区域。本研究择选洞庭湖、鄱阳湖等高质量钻孔岩芯，结合高精度的年代标尺，通过孢粉、植硅体、炭屑等代用指标的高分辨率综合分析，重建和解译全新世植被史、火活动及气候环境序列；同时，围绕长江中游湖南澧阳平原和下游浙江浦阳江流域两大新石器文化中心，基于典型遗址点边缘剖面记录的人类活动信息，着重揭示人类活动细节过程和"刀耕火种"到"犁耕"等不同稻作农作阶段对植被及环境的影响特征；综合对比长江中下游两地环境演变与稻作农业活动特点的异同，探讨两者相互作用的时空变化及其规律和机理。本项目对深入认识史前人地关系和未来环境变化预测具有重要的学术价值和现实意义。

遵照本项目研究计划和设计，紧扣“新石器时期稻作农业活动与自然环境关系”为核心问题，围绕长江中下游流域，聚焦“人与环境”为主题，旨在探讨一万年以来稻作农业文化兴衰与环境的关系。. 通过浙江萧山白马湖钻孔及跨湖桥遗址文化层和自然钻孔孢粉和硅藻证据，表明9.6–8.3 ka期间，受海侵影响，不宜人类定居生活。距今8.2 ka年跨湖桥文化出现，显示早期稻作并非“刀耕火种”而是直接利用湿地因地制宜的结果；6.5 ka年以来诸暨楼家桥遗址孢粉有力揭示了受钱塘江海潮上涌顶托及洪水灾害共同作用，从而导致文化层突然中断；河姆渡时期塔山地区显示周边植被为亚热带常绿阔叶林，气候暖湿促进了稻作文化发展，首次揭示了良渚层“异常”高含量榆属（Ulmus）花粉可能跟古人类栽培采集榆树嫩果“榆钱”食物资源有关。. 鄱阳湖和巢湖自然钻孔孢粉表明13.8–12.6 ka长江下游巢湖地区发育了落叶阔叶林-草地植被，属森林-草原景观，植被稀疏，气候干燥波动大；12.6–7.3 ka含有常绿成分以栎属（Quercus）为主的落叶阔叶林繁盛，炭屑含量达到峰值，火事情频发；7.3–2.4 ka繁育了以青冈属（Cyclobalanopsis）为主的中亚热带地带性森林植被，气候暖湿。距今约6.3 ka森林一度打开，退化为次生林；之后，与人类活动相关的松属（Pinus）、芒萁属（Dicranopteris）及禾本科（Poaceae）持续增加，表明该地区自春秋时期以来经历了强烈的农业活动影响。. 史前稻作农业与自然植被、海平面等环境息息相关。全新世早期转暖时期，浦阳江流域上游地区孕育了分布在丘陵岗地上的万年上山文化，8.2 ka年以来全新世气候相对稳定暖湿，下游平原地带的跨湖桥先民充分利用湿地环境进行稻作渔猎经济。之后河姆渡时期，稻作农业逐步进入发达期，对植被进行了显著的干预。在河谷地区，因受到了钱塘江海潮顶托影响，导致文化一度中断，良渚时期除了稻作外，可能还栽培榆树丰富了多样性食物资源。进入历史时期，研究区植被受到人类活动强烈干扰，发育了与今相似的次生松林。