不同海拔三种橐吾属植物叶结构的适应意义

研究了分布于青藏高原东部3种橐吾属植物(掌叶橐吾、箭叶橐吾和黄帚橐吾)不同海拔高度9个居群的叶结构特征、空间位置及其存活策略;对一些适应性特征与高寒环境的关系进行了分析讨论.发现气孔密度、叶片厚度、海绵细胞和栅栏细胞层的分布及表皮毛和表面蜡质的覆盖程度随海拔的升高而增加,其中叶片厚度的增加主要是由于细胞间隙的增大;叶片空间位置在3种橐吾中没有出现一致性的变化;气孔大小、角质层厚度以及等面叶和异面叶与海拔变化无明显相关性,而后两种特征更多地代表着物种属性.研究结果显示在植物对高寒环境的适应及其存活策略中,形态及结构的改变起重要作用,并且这些改变具多样性.就叶的形态结构而言,3种橐吾属植物对高寒环境的存活对策是:黄帚橐吾主要采取逃避策略,箭叶橐吾为耐受适应,而生长在林下遮阴微生境中的掌叶橐吾主要表现为对稀薄空气和低氧胁迫的适应.

Ecological signification of the leaf structure of three species of Ligularia in different altitudes

Leaf structure, orientation and other properties concerning survival strategies were investigated in nine populations along elevation gradients of Ligularia virgaurea, L. sagitta and L. przewalskii, which are distributed in the east of the Qinghai-Tibet Plateau of China. The relationship between the properties of survival strategies and psychro-environment was evaluated. It was found that stomatal density, leaf thickness cover degree of trichomes and epicuticuular wax presented an increasing trend from low to high elevation. Leaf thickness increase was mainly a result from expansion of interstitialspace with increasing elevation. The changes of leaf orientation in space were different for the three studied plants. Stomatal size, cuticular thickness, isolateral and dorsiventral leaves were not traits sensitive to changing elevation. These results suggested that morphological and structural modifications played important roles in plants adaptation to psychro environments and these modifications were diverse. As survival strategies and in terms of morphology and structure, Ligularia virgaurea mainly adopted avoidance strategies, while L. sagitta showed a tolerance adaptation. Due to shaded microhabitat, L. przewalskii mainly showed adaptability to thin air and low oxygen.