晋西北黄土丘陵区小流域土壤团聚体稳定性及其分异特征

土壤团聚体是土壤结构的基本组成部分,在影响水分入渗和转移、土壤肥力方面起到重要作用。分析土壤团聚体结构特征及其稳定性影响机制,对揭示黄土高原退耕还林还草生态环境效应具有重要意义。研究以晋西北朱家川流域内7个坝控小流域不同土地利用方式(林地、草地、农地)下土壤团聚体为研究对象,利用GIS平台空间分析模块提取样点地形因子,用湿筛法分析水稳性团聚体粒径组成,借助通径分析法分析各理化因子对于分形维数的影响。结果表明:晋西北朱家川流域不同土地利用方式下,土壤团聚体稳定性存在显著差异,团聚体稳定性从高到低顺序为:林地>草地>农地。分形维数和小粒径团聚体含量呈显著正相关,而与大粒径团聚体含量呈显著负相关。处于流域下游的后会沟流域土壤团聚体稳定性最低,中游柳树咀沟流域土壤团聚体结构稳定性最优。对土壤团聚体分形维数影响最大的因子是有机质含量,其次是海拔高度,直接通径系数分别为-0.427和-0.229,决策系数分别为0.168 0,0.085 6。研究结果可为黄土高原生态恢复和土地合理利用提供科学依据。

Stability of Soil Aggregates and Its Differentiation Characteristics in Small Watersheds in Loess Hilly Region of Northwestern Shanxi

Soil aggregates are the basic components of soil structure and play an important role in affecting water infiltration and transfer,and soil fertility.Analysis of the structure characteristics of soil aggregates and their stability influencing mechanism is of great significance to reveal the ecological and environmental effects of Grain for Green on the Loess Plateau.We took soil aggregates under different land use patterns(forest,grass,farmland)in seven dam-controlled small watersheds in the Zhujiachuan Watershed of northwest Shanxi as the research objects,and used the spatial analysis module of the GIS platform to extract the topographic factors of the sample points,and the wet sieve method to analyze the particle size composition of water-stable agglomerates,and analyzed the influence of physical and chemical factors on the fractal dimension by the method of path analysis.The results show that there are significant differences in the stability of soil aggregates under different land use methods in the Zhujiachuan watershed of northwestern Shanxi;the order of stability of aggregates is:forest>grass>farmland;the fractal dimension is significantly positively correlated with the contents of small-sized aggregates,but is significantly negatively correlated with the contents of large-sized aggregates;the soil aggregate stability of the Houhuigou watershed in the lower reaches of the watershed is most susceptible and the structure stability of the soil aggregates in the Liushuzuigou watershed in the middle reaches is optimal;the factor that has the greatest influence on the fractal dimension of soil aggregates is organic matter content,followed by altitude,and the direct path coefficients are-0.427 and-0.229,and the decision coefficients are 0.1680 and 0.0856,respectively.These research results can provide the scientific basis for ecological restoration and rational use of land in the Loess Plateau.