| Summary: | 碩士 === 國立中央大學 === 土木工程研究所 === 98 === It is well know that plant transpiration and sap flow are influenced by the environmental parameters, such as wind, solar radiation, soil moisture, vapor pressure deficit and temperature. This study used the Granier-type heat dissipation sensors to investigate the transient response of sap flow on two plant species: Pachira macrocarpa and Messerschmidia argentea (L.). The results of wind speed and blackout experiments revealed that the transient responses of sap flow of these two plants could be described by the resistance-capacitance model of Phillips et al. (2004). But the time constant and steady sap flow velocity were dependent on the location on the sensors. For Pachira macrocarpa, the time constant Tc of lower height on the stem is smaller than that of higher height, and the steady sap flow velocity Vs at lower height is larger than that of higher height. It was also found that under the same wind speed, the sap flow velocity of plant in under-saturated soil is smaller than that of in saturated soil, but the time constants of well-watered plant and plant in under-saturated soil are about the same. The experimental results of branch autonomy demonstrated that the branches react independently to the change of environmental parameter.
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