毛乌素沙地南缘沙区不同类型地表水分特征曲线测定与分析

为探明不同类型地表(裸沙、浅灰色藻类结皮、黑褐色藻类结皮和藓类结皮)的持水性能,采用砂性漏斗法对毛乌素沙地南缘沙区不同类型地表表层[(0~5)cm]土壤水分特征曲线进行了测定;并用v-G模型进行拟合。结果表明:1不同类型地表持水性能有差异,持水性能由弱到强依次是裸沙、浅灰色藻类结皮、黑褐色藻类结皮和藓类结皮,不同类型生物结皮样地持水性能分别是裸沙的1.3、1.7和2倍,不同类型生物结皮的持水性随结皮的发育呈增加的趋势;2不同类型地表土壤水分特征曲线呈"S"型分布,不同类型地表吸湿过程较脱湿过程具有显著的滞后性;3用v-G模型对测定结果进行拟合,拟合系数均小于0.009,拟合度高,表明该模型适用于此地区土壤,可用于模拟水分特征曲线;研究结果有助于全面了解生物结皮的水文效应,为受损系统的生态修复过程具有现实意义。

Discussion on the Water Characteristic Curve of Various Types of Land Surface in Mu Us Sandy Lands

In order to study the water holding capacity of different types of land surface which include bare land, light gray algae crusts, dark brown algae crusts and mosses crusts, moisture characteristic curve of different types of land surface in southern Mu Us sandy lands were studied in this paper based on methods of using sandy funnel, simulated with van Genuchten model. The results showed as follows: 1 There has different textures in various types of land surface, from lowest to highest are bare land, light gray algae crusts, dark brown algae crusts and mosses crusts. The water holding capacity of light gray algae crusts, dark brown algae crusts, and mosses crusts is about 1.3, 1.7 and 2 times as bare land. The results indicated that the water holding capacity of different types of land surface was enhanced by the development of crusts. 2 The measured curve was in an S-shaped distribution. After comparison, absorption curve had a more significant hysteretic nature than desorption curve. 3 The date of the experiment was estimated by the v-G model which had high goodness of fit for that data and the fitting coefficients are less than 0.009. The results showed that the model which applies to the soil of Mu Us sandy lands can simulate the characteristic curve. The results help to a comprehensive understanding of the hydrological effect of biological crust, having practical significance for the ecological restoration of damaged system.