Transpiration rate and influencing environmental factors of Casuarina equisetifolia on coastal sand

The transpiration rate and its influencing factors of Casuarina equisetifolia on the coastal sands of Chishan Forest Center in Dongshan,Fujian were investigated for 1 year.The results showed as follows.(1) The diurnal variation of transpiration rate(Tr) in branchlet appeared as a single-peak curve.The transpiration rate peaked at 12:00-14:00 and sharply dropped after 16:00.The diurnal variation of transpiration rate varied among different months,of which the daily peak was the highest in August and the lowest in December,3.43 and 1.08 mmol·m-2·s-1,respectively.The diurnal variation of transpiration rate presented similar trend with that of atmospheric temperature(Ta).(2) The transpiration rate in branchlet varied obviously in a season,which was higher from July to September,lower in May,June and October,and the lowest from November to the next April.(3) The relative humidity,atmospheric temperature,and vapor pressure deficit were environmental factors that mainly influenced the transpiration rate in branchlet,among which atmospheric temperature was the most important.The correlation between the transpiration rate and atmospheric temperature could be simulated by the quadratic function of Tr=4.603-0.372Ta+0.009Ta2(R2=0.855,P0.01).The correlation between the transpiration rate and soil moisture(Wc) could be simulated by the exponential function of Tr=0.665e0.09Wc(R2=0.848,P0.01).