Abstract: Evapotranspiration includes soil evaporation and plant transpiration, being an important ecological process in the water vapor exchange between atmosphere and terrestrial ecosystem, by which, terrestrial ecosystem returns its soil water initially charged from precipitation to the atmosphere to balance regional and global water cycling. The tree transpiration in forest ecosystem is an important component of the hydrological budget controlled by canopy architecture and development, soil characteristics, and a variety of in situ environmental variables. Many researchers have determined and estimated tree transpiration by using the methods of rapid weighting (RM), steady-state porometer (SSP), photosynthesis system (PS), wholetree potometer (WP), ventilated chamber (VC), weighting potted-plant (WPP), sap flow measurements (SPM), lysimeter (L), water balance (WB), energy balance (EB), Bowen ratio (BR), eddy covariance (EC), Penman-monteith Method (PMM), and remote sensing (RS). This paper introduced the principles, practices, and application scopes of these methods, and compared their advantages and disadvantages, aimed to provide a systemic support for choosing proper method(s) to estimate the tree transpiration in forest ecosystem.

Key words: Evergreen broadleaved forest, Biomass, Net primary productivity(NPP), Fine root, Leaf lifespan