天涝池流域祁连圆柏林地土壤持水特征研究

Research on the Soil Water Holding Characteristics of Sabina Przewalskii in Tianlaochi Watershed

探究祁连圆柏林地的土壤持水能力,对研究高寒山区土壤水运动、溶质运移、林草植被生理用水等具有重要意义。本研究以祁连圆柏样地0~60 cm处的土壤为研究对象,利用离心分离法获取不同土层深度在指定转速下的土壤含水率,并选用Gardner、van Genuchten、Broods Corey、Fredlund Xing 4种经验模型对实测含水率和土壤基质势进行拟合,得到拟合土壤水分特征曲线。研究结果表明:①van Genuchten与Fredlund Xing模型的拟合精度最高且相差较小,因此两者均可作为祁连圆柏样地的最优拟合模型,但Fredlund Xing模型参数的物理意义更加明确。②祁连圆柏样地不同土层深度的土壤持水能力不同,且随土壤含水率的降低,这种差异性更加显著,其中40~50 cm土层在高吸力下(>0.1 MPa)仍能释放较多的水分,保持较高的含水率,持水能力相对较强;而0~10 cm土层释放水分少,含水率低,持水能力相对较弱;此外,30~60 cm土层的土壤持水性整体上要优于0~30 cm土层,因此30~60 cm土层是祁连圆柏样地的主要水源涵养层。

To explore the soil water holding capacity of Sabina przewalskii forest land is of great significance to the study of soil water movement,solute transport and physiological water use of forest and grass vegetation in Alpine mountainous areas.In this study,the soil of 0~60 cm in the Sabina przewalskii field is taken as the research object.The centrifugal method is used to obtain the soil moisture content of different soil depths under the specified rotation speed.Four empirical models,Gardner,van Genuchten,Broods Corey and Fredlund Xing,are used to fit the measured water content and soil matrix potential,and the fitted soil water characteristic curve is obtained.The results show that:①van Genuchten and Fredlund Xing models have the highest fitting accuracy and the difference is small.Therefore,both of them can be used as the optimal fitting models for Sabina przewalskii forestland,but the physical significance of the parameters of Fredlund Xing model is clearer.②The soil water holding capacity of Sabina przewalskii forestland is different in different soil depths,and the difference is more significant with the decrease in soil moisture content.Among them,40~50 cm soil layer can still release more water under high suction(>0.1 MPa),maintain high water content,and have relatively strong water holding capacity.However,0~10 cm soil layer releases less water,has low water content and relatively weak water holding capacity.In addition,the soil water holding capacity of 30~60 cm soil layer is better than that of 0~30 cm soil layer,so 30~60 cm soil layer is the main water conservation layer of Sabina przewalskii forestland.