三峡大老岭植物区系的垂直梯度分析

为探讨山地植物区系构成特征及其垂直梯度的生态意义，根据对三峡大老岭地区植被垂直样带 调查获得的植物区系资料，分析了该地区植物区系成分构成的基本特征及其随海拔梯度的变化趋势，寻找了区系平衡点的位置；并利用聚类方法分析了山地气候垂直分异对区系成分构成的影响。结果表明：①大老岭植物区系具有温带性质，但仍反映了与热带区系的历史联系，有强烈的区域性；②属的分布区类型可归为热带分布、温带分布、地中海—中亚中心和东亚中心4组，各组区系成分的垂直梯度特征不同；热带、亚热带成分与温带成分的平衡点大致位于海拔650m；③区系成分构成和属的物种数量构成的聚类分析结果一致显示了植物区系构成与山地气候和植被垂直带相对应的格局。

A vertical gradient analysis of the flora of Dalaoling Mountain in the Three Gorges region, China

To explore its floristic compositional characteristics, and the ecological significance of the vertical gradient pattern of the Dalaoling Mountain flora in the Three Gorges region,China, this flora was investigated along a vertical vegetation transect. The structural characteristics of the flora and the altitudinal distribution pattern of its floristic components were analyzed, the floristic equilibrium point (FEP) was detected, and the effects of the mountain climate on the vertical variation of floristic composition were studied using clustering method. The results are summarized as follows: 1) The flora of Dalaoling Mountain is of a temperate nature in floristic composition,with a high endemism in Eastern-Asian and Chinese elements, but exhibits some historical connections with tropical flora. 2) The areal-types of the genera are tropical, temperate, Mediterranean to Central Asian and Eastern Asian. The vertical distribution patterns of the 4 types are different from each other. The floristic equilibrium point between the tropical elements and the temperate ones is roughly located at the altitude of 650 m. 3) The clustering analysis of the floristic composition and the species number of the genera showed that the vertical distribution pattern of floristic elements and species number of the genera corresponds with that of the mountain climate and vertical vegetation spectrum.