黑滩沟小流域不同土地利用类型土壤团聚体稳定性空间变化特征研究

Study on the Characteristics of Spatial Variation of Soil Aggregate Stability under Different Land Use Types in the Heitanggou Small Watershed

土壤团聚体稳定性直接影响土壤的物理和化学过程,决定着土壤水分运动、通气性、溶质迁移、保水保肥能力和土壤抗蚀能力等。该文以青海省东北部的黑滩沟小流域为研究区域,基于湿筛法来研究土壤团聚体稳定性特征。针对林地、草地和耕地分别布设20个样点,采集0~20 cm和20~40 cm土层土样的土壤团聚体组分及相关土壤性质进行测定与计算。运用GS+9.0软件分析该流域土壤团聚体平均重量直径(mean weight diameter, MWD)的空间变异特征,并综合Spearman相关性分析和随机森林模型对MWD进行评价:(1)该流域MWD呈弱变异,林地与草地的MWD显著高于耕地(P <0.05);(2)不同土层土壤MWD具有强烈的空间自相关,变异主要由结构性因素引起;(3)3种不同土地利用类型下对MWD起主导控制作用。土壤因素(主要是SOC和pH)是小流域土壤团聚体稳定性特征空间变化的主控因素。地形因素对MWD的主要控制因素是LC和SA。因此,包含SOC、pH值与土地利用类型是影响黑滩沟小流域土壤团聚体稳定性空间变化的主导因素,地形因素通过植被间接影响土壤团聚体稳定性。

Soil aggregate stability directly affects soil physical and chemical processes,determining soil water movement,aeration,solute transport,water and fertiliser retention capacity,and soil erosion resistance.This study focuses on the Heitanggou sub-watershed in northeastern Qinghai Province,and investigates soil aggregate stability characteristics based on the wet sieve method.Twenty sample points were established for forestland,grassland,and arable land,and soil aggregate fractions and related soil properties were measured and calculated from soil samples collected from the 0-20cm and20-40cm soil layers.GS+9.0 software was used to analyze the spatial variability of mean weight diameter(MWD)of soil aggregates in the watershed,and Spearman’s correlation analysis and the random forest model were employed to evaluate the MWD:(1)The MWD in the watershed showed weak variation,with significantly higher MWD in forestland and grassland compared to arable land(P<0.05).(2)Soil MWD in different layers exhibited strong spatial autocorrelation,with variability mainly attributed to structural factors.(3)The MWD under three different land use types was predominantly controlled by soil factors,primarily SOC and pH.Topographic factors,mainly land cover(LC)and slope aspect(SA),were the primary controlling factors for MWD.Therefore,the inclusion of SOC,pH,and land use types were the dominant factors affecting the spatial variation of soil aggregate stability in the Heitanggou sub-watershed,with topographic factors indirectly influencing soil aggregate stability through vegetation.