黄土高原刺槐林地土壤水分垂直分布特征及其动态模型的建立

Dynamic Model of Soil Moisture of Robinia pseudoacacia Plantations in the Loess Plateau

以位于黄土高原半干旱丘陵沟壑区的陕西省安塞县和半湿润残塬沟壑区的甘肃省泾川县为代表,研究了不同水分生态区刺槐林地土壤水分垂直分布特征;并在原有林地土壤水分入渗平衡模型的基础上,建立了林地土壤水分随时间、土壤深度变化的动态模型。结果表明：（1）不同水分生态区林地土壤水分垂直变化规律具有明显区别,泾川的土壤含水量峰值出现在20-40cm土层深处,后随着土层深度的增加逐渐降低,在200cm土层深度土壤含水量趋于稳定（11%左右）;安塞的土壤含水量峰值出现在约60cm左右的土层,并在220cm深度土壤含水量趋于稳定（5.5%左右）;说明泾川的土壤含水量高于安塞,安塞的降雨和林木根系耗水对土壤水分的影响程度和深度均大于泾川,且两地深层土壤水分含量不受降水和林木根系耗水等的影响。（2）利用降水在土壤中的入渗平衡模型能够很好地拟合黄土高原两地（泾川、安塞）刺槐林地的土壤水分垂直分布;并通过引入参数t（月份）建立了林地土壤水分随时间和土壤深度变化的动态模型,经验证该模型能够准确地刻画黄土高原不同水分生态区刺槐林地土壤水分的动态变化。

We studied the vertical change characteristics of soil moisture of Robinia pseudoacacia plantations grown in different water ecological zones of the Loess Plateau,sampling at Ansai County of Shaanxi Province and Jingchuan County of Gansu Province,which lie in semi-arid hilly and gully region separately.The results showed that：（1）there were objective different under the different water ecological zones of the soil moisture vertical changing regularities.The peak of soil moisture appeared in the 20-30 cm deep in Jingchuan,then the soil depth was gradually increased,while the soil moisture was gradually decreased,And below the 200 cm deep layer tended to be stable（about 11%）.The peak of soil moisture appeared in the 60 cm deep in Ansai,and below the 220 cm deep layer tended to be stable（about 5.5%）.It showed that the soil moisture of Jingchuan is higher than that of Ansai.The effects of rainfall and forest roots on soil moisture in Ansai were greater than in Jingchuan,both on extent and depth.The deep soil moisture tended toastable value,did not affecte by rainfall,roots consumption water etc.（2）The balanced model to describe precipitation infiltrating in the soil,it can good fit the vertical changes of soil moisture in the two zones（Jingchuan and Ansai）.By establishing functions of the parameter t（month）,a dynamic model was established to describe the changes of soil moisture with the time and the soil horizon depth.It was validated the dynamic model can be used to accurately calculate the soil moisture in different water ecological zones of black locust forest in the Loess Plateau,and has a higher application value.