Assessment of extreme wind erosion and its impacts in Inner Mongolia, China

Increasing land use intensity in the Xilingol Steppe has changed a former dust deposition area into a vulnerable area against wind erosion. Overgrazing caused large-scale soil degradation and destruction. The use as cropping land affects only a small area, but especially these parts of the steppe are extremely endangered. Strong winds, bare soil surface and high soil erodibility caused extreme wind erosion in April and May 2006 on a 147 ha fallow cropping field. The size and thickness of the deposited material in a sediment fan was measured to calculate the volume and the mass of the relocated material. The average thickness, the total size and the volume of the sediment fan were 11 mm, 257 ha and 27,600 m3, respectively. Comparison of the grain size distributions of soil and sediment material showed that up to 45,900 m3 of surface soil material were moved by wind and up to 18,300 m3, largely of the clay and silt fractions, were removed by dust emission. The average erosion rate from the cropped field was between 323 and 340 t ha−1, which was equivalent to 30 mm of the upper soil surface. The average dust production at the field amounted up to 136 t ha−1. Croplands are thought to contribute considerably to the total dust production and soil degradation in the temperate grasslands of Inner Mongolia. The sediment fan consisted predominantly of sand. This accumulation of coarse particles at the surface of the cropping and grassland locally degraded soil quality.