Development and Application of Thermal Methods in Measuring Stem Sap Flow
Yue Guangyang Zhang Tonghui Liu Xinping Yi Xiaoyong(1. Cold and Arid Regions Environmental and Engineering Research Institute, Chinese Academy of Sciences Lanzhou 730000;2. Graduate School of Chinese Academy of Sciences Beijing 100049)
This paper, dealing with the development and prospect of the thermal methods which can be divided into three ways (Heat Pulse Velocity, Heat Balance Method and Thermal Dissipation Method), advances the problems in practical applications and emphasizes on the principles and research instances up to date by reviewing the history of using it in sap flow calculation. The in_depth investigations and appropriate solutions of some intractable problems, such as extrapolating the stand water consumption from whole tree water use measured by thermal technique, considering the dominant environment factors in scale_up model and determining the transpiration of a heterogeneous canopy, will promote the thermal methods in theory and in practice. Analyzing the actual research progress and targets, we can make a conclusion that Thermal Dissipation Method will be the vital techniques on stem sap flow measurement and calculation in the future.