极端干旱条件下苦豆子蒸散量日变化研究

Diurnal Variation of Evapotranspiration of Sophora alopecuroides L.Under Extreme Dry Condition

基于波文比—能量平衡法的实测资料,对极端干旱条件下苦豆子地的蒸散量及能量通量进行了连续测定,并针对蒸散量与能量平衡的日变化特点进行了分析与探讨,结果表明:(1)蒸散速率在苦豆子不同的生长阶段具有不同的变化趋势,7月份为双峰型,其余的月份为单峰型;(2)在晴朗无云的天气条件下,苦豆子蒸散速率的日变化表现出明显的昼夜差异,即单峰或双峰曲线趋势,夜间水汽凝结,蒸散速率为负值;(3)在晴朗无云的天气条件下,苦豆子蒸散速率的变化趋势与净辐射、热通量的日变化都具有相同的峰型;(4)随着太阳辐射的逐渐增强,气温和水汽压均升高,蒸散作用增强。风速增大的同时,蒸散速率也随着升高。土壤温度升高值的变化趋势与蒸散速率的变化趋势基本一致。各环境因子对蒸散速率影响程度依次为:土壤温度升高值>冠层上方水汽压>气温>风速。

We made use of the data which were measured by the Bowen Ratio-equilibrium Energy Method and measured the evapotranspiration and energy flux of Sophora alopecuroides L.,analyzed the features of diurnal variation of evapotranspiration and energy equilibrium.The results showed that：（1）at different stages of growth of sophora alopecuroides L.and in different seasons,the evapotranspiration rate varied widely,the diurnal variation showed a bimodal type in July,while it was a unimodal type in the rest months;（2）the diurnal variation of evapotranspiration rate of Sophora alopecuroides L.was obvious under the clear and cloudless term,the curve trend was bimodal or unimodal,the evapotranspiration rate in the evening was negative and the atmospheric condensation process proceeded;（3）under the clear and cloudless term,the peak types of diurnal variations of evapotranspiration rate were the same as net radiation and heat flux;（4）with the increase of solar radiation,the temperature and the vapor pressure rose,the evapotranspiration enhanced.It also enhanced when the wind speed increased.The variation trend of diurnal variation of evapotranspiration was the same as the variation of soil temperature.The influence of environmental factors on evapotranspiration rate in turn is the order：variation of soil temperature〉vapor pressure above canopy〉temperature〉wind speed.