Wind erosion, land desertification and ecogeological effects in the northern piedmont of Yinshan Mountain in Inner Mongolia

This paper is the result of ecological geological survey engineering.

Objective As one of severe desertification areas in China, the northern piedmont of Yin Mountain is seriously impacted by wind erosion. The relationship of wind erosion, land desertification and the distribution of vegetation types in this area was studied, to clarify the impact of wind erosion on the weathering process from the bedrock to the soil, to reveal the effect of wind erosion on land desertification, to interpret the coupling relationship between eco-geological characteristics and ecosystems, and to provide a scientific basis for the protection and restoration of ecosystem at arid and semi-arid regions.

Methods Weathering profiles was selectively collected from rocks to soils, which distributed in the gentle slope hills, low mountain hills and mid-mountain. To compare the influence of different wind erosion intensities, some works were performed to analyze the migration processes of elements during rock weathering, characteristics of soil texture, and change patterns of surface vegetation types and its coverage.

Results The gentle slope hilly area was greatly influenced by wind erosion. Many fine particles of weathering products were moved out, which appeared as the content of Al₂O₃ in surface soil decreasing significantly and values of CIA in soil profile changing abnormally. Thus, the soil thickness became thinner with the soil nutrients being lost and the water retention ability be weakened. As the result, the grass is the main vegetation type with sparse distribution. The low hilly area was less affected by wind erosion. A small amount of clay and silt grains were emigrated, and some fine sands were immigrated, which appeared as the content of Al₂O₃ in surface soil decreasing and values of CIA in soil profile changing normally. Thus, the soil thickness was almost unchanged with the soil nutrients being lost slightly. As the result, the vegetation type was dominated by the grass with low shrubs growing, and their distribution was relatively denser. The middle-mountain area was impacted by the wind erosion at the least degree. A certain amount of clay and silt was immigrated almost without emigration of weathering products, which appeared as the content of Al₂O₃ in surface soil increased with a great increase of CIA values. As the result, the vegetation types were mainly short shrubs, and a large number of trees were densely grown on the hillside.

Conclusions Intense wind erosion caused the migration of fine-grained materials in the soil from the gentle slope hills north of Yin Mountain to the mid-mountain area, which resulted in worse soil thickness and quality at the gentle slope hills while comparing to those at the mid-mountain area. Consequently, vegetation is sparse and land desertification is more severe in the gentle slope hills, while vegetation shows better growth in the mountain areas.