滨海沙地木麻黄蒸腾速率及其影响因子

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

对福建省东山县赤山林场滨海沙地木麻黄的蒸腾速率及其影响因子进行了为期1 a的研究。结果表明:(1)木麻黄小枝蒸腾速率(Tr)全年日变化均呈单峰曲线,峰值通常出现在12:00-14:00时,并在16:00时后急剧下降。蒸腾速率日变化在各月间差异较大,峰值在1.08-3.43 mmol.m-.2s-1之间,最大值出现在8月份,最小值出现在12月份。蒸腾速率日变化趋势与温度日变化趋势一致。(2)小枝蒸腾速率的季节变化明显,呈"单峰型",7-9月蒸腾速率较高,5、6、10月份蒸腾速率相对较低,11-4月蒸腾速率最低。(3)相对湿度、大气温度、水蒸汽压亏缺等气象因子是影响小枝蒸腾速率季节变化的主要环境因子,其中大气温度(Ta)是最主要的环境因子,经逐步回归分析,可用二次函数Tr=4.603-0.372Ta+0.009Ta2(R2=0.855,P<0.01)表达。土壤含水量(Wc)与蒸腾速率呈显著的相关关系,可用指数函数Tr=0.665e0.09Wc(R2=0.848,P<0.01表达。

The transpiration rate and its influencing factors of Casuarina equisetifolia on the coastal sands of Chishan Forest Center in Dungshan, 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. 372 Ta ＋ 0. 009 Ta2 （R^2 =0. 855, P 〈 0. 01 ）. The correlation between the transpiration rate and soil moisture （We） could be simulated by the exponential function of Tr = 0.665e^0.09Wc （R^2 =0.848, P〈0.01）.