Wind tunnel test and 137Cs tracing study on wind erosion of several soils in Tibet

The soils of alpine meadows and alpine grassland steppes, aeolian soils, coarse-grained soils, and farm soils cultivated from alpine grasslands in Tibet are typical soils that are suffering from different degrees of soil erosion by wind. Based on field investigations, wind tunnel experiments, and a 137Cs trace study, this work tested the erodibility of these soils by wind, simulated the protective functions of natural vegetation and the accelerative effects of damage by livestock, woodcutting, and cultivation on erosion, and estimated erosion rates from 1963 to 2001. The results indicated that alpine meadows have the strongest resistance to wind erosion, and that undamaged alpine meadow soils generally sustain only weak or no wind erosion. Alpine grassland steppes with good vegetation cover and little damage by humans exhibit good resistance to wind erosion and suffered from only slight erosion. However, soil erodibility increased remarkably in response to serious disturbance by livestock and woodcutting; wind erosion reached 33.03 t ha−1 year−1. The erodibility of semi-stabilized aeolian soil and mobile aeolian soil was highest, at 52.17 and 56.4 t ha−1 year−1, respectively. The mean erosion rates of coarse-grained soil with various levels of vegetation coverage and of farm soil were intermediate, at 45.85 and 51.33 t ha−1 year−1, respectively. Restricting livestock, woodcutting, and excessive grassland cultivation are the keys to controlling wind erosion in Tibet. In agricultural regions, taking protective cultivation and management to enhance surface roughness is a useful way to control wind erosion.