近2000a毛乌素沙地沙漠化及成因

Desertification and Its Causes in Mu Us Desert in Recent 2000 Years

历史时期毛乌素沙地发生了沙漠化现象,但对沙漠化过程及成因尚有争议。利用毛乌素沙地风成沙-古土壤沉积的测年数据建立累积频度曲线,重建了沙漠化过程;结合高分辨率气候曲线与历史人类活动记录,对近2 000 a毛乌素沙地沙漠化与气候变化、人类活动的关系进行了探讨。结果表明:风成沙-古土壤沉积的测年数据记录了毛乌素沙地在公元440—570、840—960、1525—1890年经历3个沙漠化阶段,均属于温度较低、降水较少的冷干气候,且尘暴频次高;前2次沙漠化时期人口较少,土地开垦面积较小,人类活动程度较低,冷干气候在沙漠化过程中影响显著;第3个沙漠化阶段人口总体处于高压状态,土地开垦面积不断扩大,人类活动强度的增大加剧了沙漠化程度。

In the historical period,desertification occurred in Mu Us Desert,but the stage and cause of desertification of Mu Us Desert are still controversial. The frequency accumulation curve was established by using the chronology data of aeolian sand-paleosoil deposition in Mu Us Desert,and three desertification processes can be drawn which were corresponding to 440-570,840-960,and 1525-1890,respectively. All these periods were all characterized by low temperature,low precipitation and high frequency of dust storms. The relationship between desertification,climate change and human activities in Mu Us Desert in the past 2 000 years was discussed by combining the high-resolution climate curve and historical human activity records. The number of people and Land reclamation area in the first two desertification periods were small,so the cold and dry climate conditions had a significant impact on the desertification process. In the third period,the population increased with a high rate,the area of land reclaimed was constantly expanding. Thus,the increase of human activity intensifies the development of desertification.