6000 aBP以来洞庭湖沉积记录的环境演变及其同人类活动的关系

Environmental Changes and Relationships with Human Activities of Dongtinghu Plain Since 6000 aBP

通过对东洞庭湖地区ZK01钻孔沉积物的粒度、磁化率、孢粉等古环境指标的分析，初步揭示了该地区6000 aBP以来湖泊环境及气候演变的历史：6000～4000aBP,ZK01钻孔所在区域为水深较大的湖泊环境，湖泊周围地区分布有亚热带常绿阔叶林植被，代表较为湿热的气候；4000～1000aBP仍为深湖环境，但后期水深有所减小，其中4000aBP的气候有明显变干变凉的趋势，植被也发生了明显的变化；1000～600aBP湖泊演变为浅湖环境，600aBP之后进一步演变为浅滩与湖沼交互相环境。该地区环境演变同史前及历史时期人类活动的相互关系研究表明，6000-1000aBP的水文环境及气候变化显著地影响了区域的古代人类文化与历史的进程，其中4000aBP的气候变凉及水文环境的变化可能是该地区史前文明迅速衰落的原因：1000aBP以来，人类在长江两岸的筑堤和围垦等活动明显影响了洞庭湖地区的水沙过程及河湖环境的演变历史。

A continuous record from the Dongtinghu Lake is presented in this work. The authors provide detailed evidence of particle size, magnetic capacity and pollen analysis of ZK01 core that reveals the changes of lake＇s environment and climate since 6000 aBP. The study shows that 6000-4000 aBP, the water depth was deep in the area of ZK01 core and subtropical evergreen broad-leaved forest developed around the lake, implying a hot/humid climate; 4000-1000 aBP, the water depth was still deep with decreasing trend in the late period, and the climate became relatively dry and cool, vegetation changed significantly; 1000-600 aBP, the lake shrank to be a shallow lake and further developed to the alternate shoal and lacustrine bog environment after 600 aBP, The results reveal that hydrological environment and climate change evidently affected the process of regional ancient culture and history. Particularly, the changes of hydrological environment and climate maybe were the main fading reason of prehistoric civilization in Dongtinghu area. Since 1000 aBP, human activities such as embankment and reclamation in the banks of Yangtze River affected obviously the evolution history of flow and sediment process and river-lake environment in Dongtinghu region.