河北坝上地区不同植被类型土壤持水性能研究

以河北坝上地区不同植被类型土壤为研究对象,使用离心机法测定不同土层深度不同吸力下的土壤含水率,利用Van Genuchten模型拟合土壤水分特征曲线,分析土壤水文特征。研究表明:(1)研究区土壤为砂土,土壤容重为1.59 g/cm3,土壤水分特征曲线呈现"迅速下降–缓慢下降–稳定"的形态,不同植被类型土壤水分特征曲线相似;(2)农地的持释水能力最强,杨树样地的持水能力最差,柠条样地的释水能力最差,研究区内非农地的土壤凋萎系数平均为8.69%,随着土层深度的增加,土壤的持水能力、释水能力和凋萎系数都逐渐减小(P<0.05)。(3)坝上地区应逐步减少高耗水乔木,建立起可持续发展的乔灌草防护体系。本研究可以为确定张北地区土壤凋萎系数和土壤干层,并合理选择种植植被提供理论依据。

Water Holding Capacities Under Different Vegetation Types in Bashang Area of Hebei Province

In this paper, different vegetation types in Bashang area were selected, soil moisture under different suction in different soil layers were measured by a high-speed centrifuge, and water characteristic curves fitted using Van Gennuchten model in order to analysis water retention characteristics. The results showed that soils in the study area are sandy with the bulk density of 1.59 g/cm³. Soil water characteristic curves were similar under different vegetation types, all in the shape of "rapid decline-slow decline-stability". Farmland has the strongest water holding supply capacities. Water holding capacity was the lowest under Populus, and water supply capacity was the lowest under Caragana korshinskii. Average soil wilting coefficient of non-farm land was 8.69%. As depth increased, soil water holding and supply capacities and wilting coefficient decreased. In Bashang area, high water consumption trees should be gradually reduced and sustainable system of trees, shrubs and grasses should be established. The above results can provide theoretical basis for determining soil wilting coefficient and soil dry layer and selecting vegetation reasonably in Zhangbei area.