^(137)Cs示踪法研究青藏高原草甸土的土壤侵蚀

^(137)Cs Trace Technique to Study Soil Erosion at Alpine Meadow of Tibetan Plateau

运用137Cs示踪法对青藏高原高寒草甸典型的两个小流域的土壤侵蚀进行了研究,结果表明:高寒草甸植被区的土壤137Cs在土壤剖面中呈指数型分布,分布深度一般在20cm左右;坡顶部由于风蚀、冻融侵蚀和水蚀较强,致使侵蚀强于下部,除坡顶部外其他坡位侵蚀强度都符合坡上部<坡中部<坡下部的规律;高寒草甸植被覆盖度与土壤侵蚀强度呈显著的负相关关系(p<0.01),土壤平均侵蚀模数随植被覆盖度的增加呈线性降低的趋势,相关系数R2达到0.997以上。高寒草甸退化程度越高,土壤侵蚀越强。退化较强的草甸区的平均侵蚀模数是退化较弱区的2.23倍,最大侵蚀模数可达2960.22t/(km2.a)。

^137Cs tracing technique to studied the soil erosion of two basins at alpine meadow of Tibetan Plateau. The results showed：^137Cs in soil profile is exponential distributing at alpine meadow. Depth of about 20 cm in general distribution of ^137Cs. Slope top because wind erosion, water erosion and frozen-thaw erosion is stronger than the bottom of slope. Intensity of erosion is consistent with other slope spaces erosion intensity law of others slope position all accorded with upper 〈 middle 〈 down. Alpine meadow cover and soil erosion is a degree of significant negative correlation. With an average of soil erosion module is a linear increase in vegetation cover degrees lower trend, that correlation coefficients is R^2 = 0. 997. Alpine meadow higher degree of degradation is soil erosion more powerful. The maximal soil erosion module is 2 960. 22 t/（ km^2·a）. Degradation serious meadow areas average erosion module is 2. 23 times the degradation of the weaker areas.