树干液流研究进展与展望
Stem Sap Flow Research: Progress and Prospect

树干液流是土壤-植物-大气连续体水流路径中一个关键的链接，承接了庞大的地下根系所吸收、汇集的土壤水，并决定着整个树冠的蒸腾量，因此成为分析树木耗水特性、研究树木水分传输机理的重要指标。结果表明，1）常见的测定树干液流的5种方法，对比分析各种方法的原理以及优点和缺点，热比率法是目前研究树干液流最可靠的方法。2）分析树干液流的日季变化、方位变化和高度变化，发现大多树干液流日变化呈单峰型，季节变化总体上呈现夏季液流速率最高，春秋次之，冬季最小的变化趋势。3）分析不同树种树干液流与环境因子的滞后效应及与环境因子的关系，发现树木液流与太阳辐射、水汽压亏缺等呈正相关，与空气相对湿度呈负相关。针对目前研究中存在的问题提出了有待进一步解决的问题，旨在为进一步研究树木耗水及生态需水提供理论依据。
Sap flow is a key link in soil-plant-atmosphere cotinuum which undertakes the soil water of root absorbed and decides the amount of tree transpiration. It can be used to analyze the characteristics of water consumption and the mechanism of water transport of trees. This paper summarized,1) the principles and methods of thermal technique and comparative analyzed the advantages and disadvantages of each methods. 2) The changes of sap flow in different tree species including diurnal variation, seasonal variation, height changes and the reasons which caused these changes. 3) The relationship of sap flow and environmental factors in different tree species. In the last, the future trends in development of sap flow technique researches were forecasted. The purpose of this paper was to provide some theoretical foundations for water consumption and ecological water requirement of trees