云南哀牢山地区蕨类植物区系的垂直分布格局

Altitudinal patterns of floristic elements of ferns in Ailao Mountain， Yunnan Province

关键词:  垂直格局  区系成分  聚类分析  蕨类植物  哀牢山

Key words:  altitudinal patterns  floristic elements  cluster analysis  ferns  Ailao Mountains

摘要:

根据大尺度的物种分布信息，利用聚类分析和数理统计的方法分析了云南哀牢山蕨类植物区系的垂直分布格局。研究结果表明，随着海拔的升高，热带区系成分所占比重呈显著递减趋势，而温带区系成分所占比重呈明显递增趋势。在整个海拔梯度上，东亚分布和热带亚洲分布成分始终占主导地位。区系过渡性随着海拔的升高呈先增强后减弱的单峰分布格局，平衡点出现于海拔1 700 m左右。基于区系成分比重的聚类分析表明，在海拔1 300 m，1 900 m和2 600 m左右，将海拔梯度上的蕨类植物分为4组，这与各海拔段内的物种组成和区系成分性质是一致的。

Abstract:

Based on flora information in large scale，the altitudinal patterns of floristic elements of ferns in Ailao Mountain were investigated. The results showed that with the increase of altitude，the proportions of tropical elements decreased，and that of temperate elements increased. The whole altitudinal band was dominated by the proportions of both East Asia elements and Tropical Asia elements. Floristic transition increased and then decreased against altitude. The floristic equilibrium point was found around altitude 1 700 m. Four groups divided at altitude 1 300 m，1 900 m and 2 600 m were found respectively，which were consistent to distinct species and flora compositions in each altitudinal bands.