长江源多年冻土区热融湖塘的形成对土壤沙化过程的影响

The Influence of Thermokarst Lake Formation on Soil Desertification Process in Permafrost Regions of the Source Region of the Yangtze River

选择长江源区五道梁为研究区域,以典型发育的热融湖塘为研究对象,运用激光粒度仪测得土壤粒径分布,并结合分形模型对高寒草甸土壤颗粒分布与水文过程进行研究。结果表明:热融湖塘的形成加快了长江源区高寒草甸土壤沙质化的进程,随着其影响程度的加剧,黏粒、粉粒含量逐渐减小,砂粒含量逐渐增大,同时土壤颗粒体积分形维数也逐渐减小,并与黏粒、粉粒呈显著正相关,与砂粒含量呈显著负相关,土壤颗粒体积分形维数可代替土壤不同粒径颗粒组成表征土壤沙质化的进程。此外,在热融湖塘影响下的土壤水文过程的改变,是加快土壤沙质化的重要因素之一。

We chose Wudaoliang in the source region of the Yangtze River as the study area and a typically developed thermokarst lake as the study object,using the laser diffraction method to measure the soil particle size distribution(PSD),and studied the PSD and hydrological process of alpine meadow soil combined with a fractal model.The results show that the formation of the thermokarst lake speeds up the desertification of alpine meadow soil in the source region of the Yangtze River.As the affect intensifies,the share of clay particle(0-2μm)and silt particle(2-50μm)gradually decreases,while the share of sand particle(50-2 000 μm)increases.Meanwhile,the volume fractal dimension also reduces gradually,showing a significant positive linear correlation with the share of clay particle and silt particle and a significant negative linear correlation with the share of sand particle.Volume fractal dimension of soil can substitute for PSD to characterize the process of soil desertification.In addition,soil hydrological process changes under the influence of thermokarst lakes,which is one of the important factors speeding up soil desertification.