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The experimental area is situated about 500 kin north of Beijing in the Xilin river catchment. The investigated soils are Chernozems under Leymus chinensisand Stipa grandis steppe and the annual precipitation is about 300 mm.

Increasing grazing intensities (sheep, goats) in Inner Mongolia, P.R. China, are reported to lead to an increasing degradation of the grassland followed by increasing soil erosion and desertification (Ojima et al., 1993; White et al., 2000; Schlesinger et al., 1990). It was explained by a soil structure change by sheep trampling and may result in a reduced infiltration of water and strength of the soil. Therefore the danger of surface run-off, accompanied by an enhanced erosion of the soil, is increased.

To estimate the influence of grazing on soil physical properties we investigated four plots that had different grazing intensities (overgrazed, winter grazed, ungrazed since 1979, ungrazed since 1999). To quantify soil stability the precompression stress value and the shear resistance of the bulk soil and the tensile strength of soil aggregates were determined. Furthermore, the saturated hydraulic conductivity was measured in vertical and horizontal direction to estimate the influence of trampling on soil functions.

Soil mechanical properties and soil hydraulic functions have found to be influenced by grazing which is reflected by decreasing shear resistance and hydraulic conductivity with increasing grazing/trampling intensity. Furthermore, the anisotropy of the saturated hydraulic conductivity is affected by trampling. Dynamic compressive and shearing loads generated by sheep trampling result in soil structure degradation with negative consequences for plant available water and soil erosion.