『Abstract
　The ¹³⁷Cs tracer technique was used to study soil erosion of alpine meadow grassland in two small river basins in the headwater region of the Yellow River. The results show that the levels of ¹³⁷Cs in soil samples from this alpine meadow vegetation zone exhibit an exponential distribution, generally within a depth of approximately 20 cm. Due to strong winds, freeze-thaw cycles and water, soil erosion was found to be stronger on the upper slope than on the lower slope, and except for the slope crest, the intensity of soil erosion at other sites was as follows: upslope＜midslope＜downslope. There was a significant negative correlation between the intensity of soil erosion and the extent of alpine meadow vegetation cover (P＜0.01). The mean soil erosion modulus exhibited a linear reduction trend with an increase in vegetation cover, and the correlation coefficient R² was ≧0.997. The higher the degradation degree of the alpine meadow grassland, the greater is the soil erosion. The mean erosion modulus in the severely degraded meadow zone was 2.23 times greater than the one in the slightly degraded zone, and the maximum erosion modulus reached 2.96×10⁶ kg/km²/a.

Keywords: ¹³⁷Cs tracer technique; Soil erosion; Degradation of vegetation; Alpine meadow; Headwater area; Yellow River』

Introduction
Description of the study area
Collection and analysis of soil samples
Calculation model
Analysis of results
　¹³⁷Cs background value
　¹³⁷Cs mass activity in soil profiles
　Effects of vegetation cover
Soil erosion moduli and distribution of ¹³⁷Cs on the slopes
Annual erosion thickness
Discussion and conclusion
Acknowledgments
References