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    内蒙古阴山北麓的风蚀沙化作用及其生态地质效应

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

    • 摘要:
      研究目的 阴山北麓作为我国土地沙化最严重的区域之一,受风蚀作用影响严重。本文通过研究该地区风蚀作用、土地荒漠化与植被类型分布三者之间的关系,阐明风蚀作用对基岩风化成土过程的影响,揭示风蚀对土地沙化的影响,诠释生态地质特征与生态系统的耦合关系,为干旱、半干旱地区生态系统保护修复提供科学依据。
      研究方法 本文选择该地区缓坡丘陵、低山丘陵和中山三种地貌区的基岩风化剖面为研究对象,对比研究了不同风蚀强度下岩石风化过程中元素的迁移过程、土壤质地特征以及地表植被类型与覆盖度变化规律。
      研究结果 缓坡丘陵区受风蚀作用影响较大,细粒风化产物大量迁出,表土Al2O3含量显著减少,土壤剖面CIA值变化异常、厚度变薄、养分流失、保水能力下降,植被类型以草为主,稀疏矮小,覆盖度较低;低山丘陵区受风蚀作用影响较小,黏粒、粉粒少量迁出,少量极细砂迁入,表土Al2O3含量减少,土壤CIA值变化正常、厚度变化不大、养分少量流失,植被类型以草为主,分布相对密集,且有低矮灌木生长;中山区受风蚀作用影响最小,以黏粒、粉粒物质迁入为主,风化产物迁出甚少,表土Al2O3含量增加,CIA值显著升高,植被类型以低矮灌木为主,山坡上有大片乔木生长,长势较好。
      结论 强烈的风蚀作用使得阴山以北缓坡丘陵区土壤中的细粒物质被迁移至中山区,造成缓坡丘陵区土壤厚度与质量较中山区差,因此缓坡丘陵区植被稀疏,土地沙化较严重,山地区植被涨势较好。

       

      Abstract:
      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.

       

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