MEASUREMENT OF TREE TRANSPIRATION USING LARGE WEIGHING LYSIMETERS

The difference of transpiration process between coniferous and broad-leaved trees is one of the most interesting topics in forest hydrology and other study fields. Direct measurement of transpiration is indispensable for detailed discussion on the topics. The lysimeter is the most effective way to directly measure tree transpiration. In this study, large weighing lysimeters were constructed. Zelkova serrata (Japanese zelkova) and cryptomeria japonica (Japanese cedar) were planted in containers of the lisimeters, and transpiration was measured. The relationship between transpiration and heat pulse velocity which is an reliable index of transpiration rate and actual transpiration rate was investigated. Apparent differences of transpiration rate and process could not be found between two species as far as the results of the measurements.