重庆四面山不同土地利用方式土壤水分特征曲线测定与评价

Determination of Soil Water Characteristic Curve with Different Models and Their Evaluation Under Different Land Uses in the Simian Mountains,Chongqing

为满足在同类土地利用方式下测量大量土壤水分状况的需求,选择重庆四面山人工针叶混交林地、天然针叶混交林地和农耕地等3种土地利用方式,在采用常规方法测定土壤基本物理性质、压力膜仪法测定土壤水分特征曲线基础上,分别采用Brooks-Corey模型、Gardner模型和van Genuchten模型模拟不同土地利用方式的土壤水分特征曲线,以筛选出适用于特定土地利用方式的模型,用于模拟土壤水分特征曲线.结果表明,Brooks-Corey模型模拟的土壤水分特征曲线与实测值存在较大差异,在3个模型中拟合精度最差.Gardner模型对不同林地土壤水分特征曲线模拟的判别系数R2均大于0.97;van Genuchten模型对农耕地0～20,20～40,40～60 cm土壤水分特征曲线模拟的判别系数R2均在0.92以上.Gardner模型适用于林地土壤水分特征曲线的模拟,van Genuchten模型适用于农耕地土壤水分特征曲线的模拟.

In order to meet the requirements of measuring a great number of soil moisture conditions under the same land use patterns,three kinds of land use patterns were chosen in the Simian Mountains of Chongqing in this study,i.e.coniferous mixed plantation land,natural coniferous mixed forest land and agricultural land.Conventional methods were used to determine the basic physical properties of the soil and the pressure membrane instrument was employed to determine soil water characteristic curves.Then,Brooks-Corey model,Gardner model and van Genuchten model were adopted to simulate the soil water characteristic curves under different land use to find out which model had the highest simulation accuracy.The results showed that there was great difference between the Brooks-Corey model simulation value of the soil water characteristic curves and the measured values and its fitting accuracy was the poorest in the three kinds of models.Two-thirds of the discriminate coefficients R2 of soil water characteristic curve simulated with Gardner model under different forest land use patterns were larger than 0.97.The discriminate coefficients R2 in van Genuchten model simulation were larger than 0.92 in agricultural land.Gardner model is,therefore,recommended for simulating soil moisture characteristic curves in the forest lands,and van Genuchten model for the farmlands.