浙江宁绍平原是研究河姆渡文化与自然环境发展关系的热点区域。选取田螺山遗址附近的TLS1402钻孔上部16.16m的沉积物进行AMS 14C测定、孢粉和微炭屑分析,旨在研究宁绍平原中全新世植被历史、环境变化和人类活动的变化规律。结果表明:1)约8460-7700 a B.P.,植被类型以落叶阔叶林为主,含有常绿成分和针叶成分,揭示了气候温凉偏干的特点;7700~6300a B.P.期间,乔灌木整体有所下降,波动显著,植被类型为亚热带常绿落叶阔叶混交林,气候暖湿,在7600-7500 a B.P.、7300-7200 a B.P.和6700~ 6300 a B.P.,粒径>38 mum的禾本科明显增加,可能显示了人类的3个农业发展阶段。另外,微炭屑增加对应栽培作物花粉的增加,暗示植被变化可能与人类活动有关;6300a B.P.至今,木本花粉含量总体大幅度下降,草本花粉含量升高,气候稍温凉偏干,植被类型仍以亚热带常绿落叶阔叶混交林为主,但植被变化可能受人类干扰。2)淡水藻类和沟鞭藻类含量表明,TLS1402钻孔所在地8460~7700a B.P.可能为浅海湾环境,但也受到淡水注入影响。7700~ 7200 a B.P.为过渡时期;7200a B.P.后环境发生较大变化,海平面上升速率大幅度降低,陆地逐渐生长,7000~ 6900a B.P.河姆渡文化逐步开始发育,水稻农业发展,但之后受到海水影响,在7200~ 6700 a B.P.、6600~ 6500a B.P.都出现农业发展低谷,分析认为和海水入侵有关。
英文摘要:
Climate and environmental changes, especially the abrupt climate changes during the Holocene, have changed the lifestyle of human and have a profound impact on human activities. Studying relationship of climate, environmental changes and human activities can provide reference and basis for predicting human adaptation in the future. Ningshao Plain is the coastal plain on the south bank of Hangzhou Bay significantly affected by monsoon climate. Extreme weather and environmental events such as floods and storm surge occurred frequently in this area during the Holocene. It is also a hot spot to study the origin of Neolithic rice farming. Tianluoshan site is located at Yuyao City, Zhejiang Province, northeastern of Ningshao Plain. It's a part of subtropical monsoon climate. The annual average temperature is 16.2℃. It's one of the typical Neolithic sites to study the possible information of regional vegetation, climate and human activities during Hemudu Culture period. In this study, three cores were drilled from Tianluoshan Site. We selected core TLS1402 (30°01'20"N, 121°22'38"E) for AMS 14C dating and palynological analysis. The age-depth model in this paper was established by Bacon Analysis. A total of 82 samples, indicating that the above 16.16 m core covers sediments since 8460 cal. a B.P. were analyzed. Compared with pollen, algae and charcoal, the results were as follows : (1) About 8460 ~7700 cal. a B.P., the vegetation was dominated by deciduous broad-leaved forests, containing evergreen components and coniferous components, revealing the cool and dry climate. From 7700 ~6300 cal. a B. P., the overall shrubs decreased and fluctuated significantly. The vegetation type was subtropical evergreen and deciduous broad-leaved mixed forest, during 7600~7500 cal. a B.P., 7300~7200 cal. a B.P. and 6700~6300 cal. a B.P., Poaceae bigger than 38 mum increased significantly, indicating the three stages of human agricultural development. The microcharcoal increase corresponds to the increase of cultivated crops pollen, suggesting that vegetation changes may be related to human activities. After 6300 cal. a B.P., the content of trees has dropped significantly, and the content of herbaceous plants has increased, indicating slightly cooler and drier climate. Vegetation was still dominated by mixed forests of subtropical evergreen and deciduous broad-leaved forests but influenced by human activities. (2)The content of algae indicates that the TLS1402 site may be a shallow bay environment, also affected by freshwater injection between 8460 ~7700 cal. a B.P. After 7200 cal. a B. P., the environment changed significantly, with decreasing significantly of sea level rise and increasing gradually of land. Hemudu Culture developed gradually and rice agriculture developed during 7000 ~6900 cal. a B.P.,but it was later affected by seawater. The agricultural development appeared low point at 7200~6700 cal. a B.P. and 6600~6500 cal. a B.P.,which may be related to seawater invasion.