黄土高原关键带土壤水分空间分异特征

Spatial Variations of Soil Water Content in the Critical Zone of the Chinese Loess Plateau

地球关键带是人类生存和发展的关键区域。关键带发生的一系列物理、化学和生物过程与人类活动密切相关。土壤水分是黄土高原关键带的关键要素,同时又是黄土高原植被恢复与生态环境重建的决定因子。为揭示黄土高原关键带土壤水分的空间分异特征,采用网格（50m×50m）布点,雨季结束后采集0~500cm深度土壤样品,结合室内分析,结果表明：黄土高原小流域中73个样点0~500cm的土壤含水量分布范围介于1%~23%之间,降水对0~100cm土层的土壤水分补充明显;土壤水分在水平和垂直方向都表现出明显的空间异质性,在不同方向上的水分控制过程有所不同,是对土地利用方式、植被类型、地形要素、土壤质地等多因素综合响应的结果。充分理解关键带土壤水分空间的分异规律及其主控因素有助于该区小流域综合治理中的植被建造与布局,也有助于对该区土壤水文和生物地球化学过程的理解。

The critical zone（ CZ） where occurred series of physical,chemical and biological processes closely related to human activities,is essential for the survival and development of mankind. Soil water content（ SWC）,which plays a key role in the earth＇s CZ,is a dominant factor of vegetation restoration and eco-environment reconstruction on the Chinese Loess Plateau. To determine the spatial variations of SWC in the CZ of the Loess Plateau,we selected 73 sampling sites at a small catchment with a grid of 50 m×50 m,and collected soil samples to a depth of 500 cm after a rainy season. Results show that the values of all measured SWC range from 1% to 23%.The SWC located at 0 ~ 100 cm depth is highly replenished by rainfall. SWC demonstrates an obvious spatial heterogeneity both in the horizontal and vertical direction,which is controlled by different processes in different directions. Spatial pattern of SWC is the combined effect of land use and vegetation type,tographical elements and soil texture. Understanding this information is helpful for the planting and layout of vegetation at a catchment scale,and also for investigating the soil hydrological and biogeochemical processes in the CZ of the Loess Plateau.