干旱区胡杨叶片含水量和叶绿素含量特征

Characteristics of Populus euphratica leaf water and chlorophyll contents in an arid area of Xinjiang,Northwest China

在阿拉干样区内,距河道不同距离选取40棵胡杨树(Populus euphratica)采样,使用相关分析方法探讨胡杨叶片相对含水量(fuel moisture content,FMC)、等效水厚度(equiv-alent water thickness,EWT)、叶绿素含量随距河道距离的空间差异,以及随地面温度的变化特征,并讨论了FMC、EWT和叶绿素含量之间的相关性。结果表明:FMC、EWT、叶绿素含量与河道距离有极显著的相关关系(P<0.01)。距河道越远,3项指标均随距河道距离的增加极显著的减少,其中EWT与距河道距离的相关性最大(-0.577)。温度变化对FMC和EWT均有极显著的影响(P<0.01),但对叶绿素含量影响不大(P>0.05)。因FMC、EWT的物理含义不同,它们的平均值在胡杨树个体尺度/水平上极显著相关,但在单片叶子尺度上FMC和EWT之间无显著相关(P>0.05),而胡杨树个体平均和单片叶子的EWT与叶绿素含量均极显著相关(P<0.01)。由于EWT与距河道距离和叶绿素含量的相关性极显著,而且对温度变化不敏感,因此,具有很好的开发应用潜力,建议将EWT作为干旱区河岸生态系统植被含水量遥感监测的一个指标。

In August 2011, forty Populus euphratica plants at the Arghan monitoring section in the lower reaches of Tarim River were selected to study the spatial differentia of their leaf physio- logical traits and surface temperature. The plants had different distances from the River. A signif- icant （ P 〈 0.01 ） negative correlations were observed between the leaf fuel moisture content （FMC）, equivalent water thickness （EWT）, and chlorophyll content and the distance of the plants from the River. All the former three variables decreased significantly with the distance from the River. Leaf surface temperature had 0. O1 ）, but minor effects on the chlorophyll significant effects on the leaf FMC and EWT （P〈 content （P〉0.05）. Due to the differences in the physical interpretation of FMC and EWT, their mean values were significantly correlated at tree level （P〈O. Ol ）, but less correlated at single leaf level. However, the correlation between EWT and chlorophyll content were significant （P〈0. 01 ） both at tree level and at single leaf level. Because of the significant correlation with chlorophyll content and with the distances of trees from river, leaf EWT could be used as a vegetation water index for remote sensing-based monitoring in arid area riparian ecosystems.