黄土半干旱区白榆和侧柏夜间液流动态分析

 利用TDP茎流计研究了黄土半干旱区白榆和侧柏夜间液流的特征,结果表明:与白天相比较,2树种夜间液流通量密度较小;夜间水分补充的时间段主要在前半夜;受干旱胁迫的影响,白榆的夜间水分补充量雨天要远大于晴天;白榆的夜间液流通量密度及其对日蒸腾量的贡献率对环境因子较为敏感,主要影响因素为降雨量;侧柏由于本身极强的保水能力和抗旱性,其夜间液流通量密度及其对日蒸腾量的贡献率受环境因子的影响不显著。在黄土半干旱区侧柏具有比白榆更强的适应能力。

Analysis on the dynamics of nighttime sap flow of Ulmus pumila and Platycladus orientalis in semi-arid area of Loess Plateau

In this paper,TDP sap flow meter was used for studying the nighttime sap flow characteristics of Ulmus pumila and Platycladus orientalis in semi-arid region of Loess Plateau.The results showed that the nighttime sap flux density was much smaller than which in daytime.The major duration of water recharging was from sunset to midnight.By the effects of drought,the amount of nighttime water recharge in Ulmus pumila at rainy days should be much larger than the amount at sunny days;the contribution of nighttime water recharge to total transpiration of Ulmus pumila had significant correlations with environmental factors and the main influencing factors was rainfall;Due to the strong water-retention capacity and drought resistance of Platycladus orientalis,the contribution of nighttime water recharge to total transpiration was not subject to the impact of environmental factors.Compared with Ulmus pumila,Platycladus orientalis showed stronger adjustability in the semi-arid area of Loess Plateau.