陕北黄土区不同植被下深剖面土壤的分形特征

Soil Fractal Characteristics of Deep Profiles Under Different Vegetation in Loess Areas of Northern Shaanxi,China

[目的]探究不同植被下深剖面土壤分形特征及其与土壤理化性质和水力学参数的关系,为植被恢复和农业生产提供重要的参考依据。[方法]以陕西省神木六道沟流域为研究区域,采集该区域4种植被(草地、杏树、油松、柠条)下>13 m深剖面土壤样品,测定土壤颗粒组成、含水率以及有机碳含量等,计算土壤分形维数,分析不同植被下深剖面土壤的分形特征。[结果](1)该区土壤黏粒、粉粒及砂粒含量分别为15%,40%和45%,不同植被下土壤颗粒组成的差异显著(p<0.05)。(2)整个剖面上4个样地的分形维数无显著差异(p>0.05),在1—2 m土层深度内,植被类型对土壤分形维数的影响显著(p<0.05),且油松及草地样地的分形维数大于其他两个样地。(3)土壤分形维数与黏粒含量及土壤水力参数(θ_(r),n和K_(sat))的相关性显著(p<0.05),但与有机碳和含水率相关性不显著(p>0.05)。[结论]土壤分形维数主要受土壤细小颗粒影响,且对土壤水力性质具有一定的指示作用,油松及草地对土壤结构改善作用最佳。

[Objective] The aims of this study are to explore the fractal characteristics of deep profile soil under different vegetation types and their relationship with soil physicochemical properties and hydraulic parameters,and to provide important reference basis for vegetation restoration and agricultural production.[Methods] Shenmu Liudaogou watershed in Shaanxi Province was taken as the research area.Soil samples with a depth of>13 meters were collected from four vegetation types(grassland,apricot,pine,and peashrub) in the area.Soil particle composition,moisture content,and organic carbon content were measured.Soil fractal dimension was calculate,The fractal characteristics of deep profile soil under different vegetation types analyzed.[Results](1) The soil clay,silt,and sand contents in this area are about 15%,40%,and 45%,respectively,and the differences in soil particle composition under different vegetation were significant(p<0.05).(2) The fractal dimension of the four sample plots did not differ significantly(p>0.05) throughout the profile,and the effect of vegetation type on soil fractal dimension was significant(p<0.05) in the depth of 1~2 m.(3) The fractal dimension of the pine and grassland was greater than the other two sample plots.In addition,soil fractal dimension is significantly correlated with clay content and soil hydraulic parameters(θ_(r),n and K_(sat))(p<0.05),but not with soil organic carbon and soil moisture content(p>0.05).[Conclusion] Soil fractal dimension is mainly influenced by soil fine particles,and is indicative of soil hydraulic properties.Pine and grassland have the best effect on soil structure improvement.This study has important implications for the sustainable use and management of vegetation and water resources in dryland areas.