Abstract: A study was conducted to learn the annual water content variation in the leaves and top branches of four Rhododendron Species in the alpine shrubland of the Qilian mountains of northwestern China.The study also probed the relationship between water content variations and other ecological factors,and the relationship between moisture change and the plant’s metabolism.Results show that:1.Water content of leaves and top branches of the four Rhododendron Species changed periodically-abundant in the plant growing stage, and scanty during its dormancy.In the plant growing period,the leaf transpiration rates rose with the lengthening of the newly springing out branches,which amounted to more than 99% of the total growing in a year.2.The water content of leaves and top branches was notably affected by the soil temperature,though not by the extent of soil saturation.3.Different degrees of leaf coiling synchronized with the variations of moisture content of leaf tissues.4.Variations of tissue water content of the four Rhododendron Species resulted from their acclimation to the severe alpine conditions.Still there existed differences among the four species in water content variation and adaptation strategy.

Key words: Qilian mountains, Shrubland, Rhododendron Species, Water content variation, Ecological adaptation

摘要： 为了解高寒常绿植物水分状况及不同季节的动态变化规律,研究祁连山高寒灌丛草地4种杜鹃(Rhododendron L.)属植物叶片和顶生枝条含水量年际动态,探讨水分动态与土壤因子的关系,及其与代谢生长间的关系。结果表明:4种杜鹃属植物年组织含水量呈周期性动态变化;在越冬休眠期,枝叶含水量极低;在生长季枝叶水分含量高,叶片蒸腾作用强,新枝生长长度大,占全年的99%以上;土壤温度对枝叶含水量动态变化具有重要影响,但土壤含水量对枝叶含水量的影响不大;叶片不同程度的反卷与叶片组织含水量的变化一致;组织水分动态变化是杜鹃对高寒地区严酷环境的适应结果,在不同种间存在着一定差异。

关键词: 祁连山, 灌丛草地, 杜鹃属植物, 水分动态, 生态适应