近2ka河西走廊及毗邻地区沙漠化的过程及原因

根据古城废弃、湖泊退缩、频降尘期等发生时代的相对一致性 ,确定了历史时期河西走廊沙漠化过程存在三次大发展时期 ,即南北朝、唐末五代和明清两朝 ,它们均对应近 2ka以来的气候干冷阶段 .认为清代中期河西走廊人口密度突破了干旱地带人口压力的“临界指标”且水资源利用率超过 4 0 %是晚近沙漠化土地迅速扩大的主要原因 .

Climatic and human factors for the desertification process in Hexi Corridor,China in the recent 2000 years

According to the relative consistency of the occurring ages when agro-cities were abandoned, lakes retreated and frequent dusts happened, it was sure that there were three periods when the desertification was enlarged rapidly in north China. The periods were South and North Dynasties,the late Tang Dynasty and the Five Dynasties, and Ming-Qing Dynasties. Just in these ages it was colder and drier than at present, which indicates that the macro-process of desertification in the region under study was affected mainly by the climatic changes. Based on the fact that the population density in the middle of the Qing Dynasty had exceeded the critical index of the population pressure in arid land and the rate of utilization of water resource had exceeded 40% in Hexi Corridor, this paper suggests that the human activities in desertification of the area in question have played an important role chiefly during the recent 300 years.