中文摘要：

植物根系水力再分配（Hydraulic redistribution）是近几年提出的对植物根系水力提升现象一种更准确的描述.Ryel等（2002）建立的根系水力再分配模型（以下简称Ryel模型）模拟结果表明根系水力再分配是土壤水分动态的一个重要组成部分.该文基于Ryel模型,对模型中涉及的重要参数进行敏感性分析,更准确地阐述参数变化下根系水力再分配模型的行为动态,从而定量分析环境及植物自身等因素对根系水力再分配的影响.Ryel模型时间尺度和土层厚度的设定限制了模型的应用,该文通过参数调整,将模型从时间尺度为小时、土层厚度均一转换到时间尺度为天、土层厚度不等,并应用到内蒙古皇甫川流域.

英文摘要：

Background and Aims Hydraulic redistribution （HR） is an extension of hydraulic lift. The simulation of hydraulic redistribution done by Ryel et al. （2002） indicated that HR is beneficial for transpiration. Methods Based on the Ryel Model, we first conducted a sensitivity analysis by varying critical parameters of the model. We scaled the model for time steps of 1 hour to 1 day and soil from 10 cm to greater thicknesses by adjusting the necessary parameters. The scaled model was then applied to field observations of Caragana intermedia in Huangfuchuan Watershed of Inner Mongolia to simulate transpiration with and without HR. Daily changes in transpiration were simulated from April to October in 1998 and 1999. Key Results and Conclusions The ratio of water redistributed by root to transpiration was strongly negative to soil hydraulic conductivity. The ratio also increased when root hydraulic conductivity increased, but gradually approached a limit. Total transpiration with HR increased when root hydraulic conductivity increased 〈 1 cm· MPa^- 1· h^- 1 and decreased when it increased 〉 1 cm· MPa^- 1· h^- 1. The result of the scaling indicates that it provides a useful approach to incorporating HR into larger models of soil processes. Total transpiration with HR increased 4.4% more than without HR in 1998, in contrast to total transpiration without HR having increased 2.1% more than with HR. This may be related to high precipitation in 1998.