【摘要】 水力再分配(hydraulic redistribution,HR)指在根-土界面水势梯度驱动下,水分经由根系在土壤不同部位之间的一种被动运输过程。目前,已在全球不同生态系统超过120种植物中发现了HR现象,试验观测与模型模拟的HR大小相差2个数量级:试验观测的HR在0.04~1.3 mm·d-1,而模型模拟的HR在0.1~3.23 mm·d-1,这主要受方法差异的影响。目前,HR测定所采用的方法主要有土壤水分法、同位素示踪法和液流法;任何一种单一的观测方法都存在缺陷,且由于各种观测结果之间缺乏系统的比较,造成HR的测定结果存在不确定性。HR模拟方法主要以土层连接模型为代表,而其他基于物理过程的大根模型、中尺度水分动态模型和动态根廓线模型,因其结构复杂、参数较多而未得到推广。未来,HR的大小量化和机理理解仍将是这一课题面临的难点问题。更多还原

【Abstract】 Hydraulic redistribution( HR) is a passive movement process of water between different soil parts via plant root systems,driven by water potential gradients in the root-soil interface. Now,HR has been observed in approximately 120 species that involve in a wide variety of ecosystems and a wide range of life forms. Empirical and modeling estimates of the average amount of water moved by HR span nearly two orders of magnitude,from 0.04 to 1.3 mm·d-1in the empirical literature,and from 0.1 to 3.23 mm·d-1in the modeling literature. The applicative techniques of HR measurements include soil moisture,isotopic labeling and sap flow methods.Each of the measurement techniques of HR has defects and uncertainty about test results,due to the lack of the comparison of the various methods. The soil connection model of HR has been widely applied,but other models,including the physical processes-based big root model,mesoscale moisture dynamic model and dynamic root profile model,have not been promoted for their complex structures and numerous parameters. In the future,quantifying the magnitude and understanding the mechanism of HR are still the difficulties of this subject.更多还原