西双版纳热带森林附生维管植物的物种多样性与区系特征

附生植物是山地森林生态系统中重要的结构性成分。因受林冠调查技术限制, 人们对林冠附生植物知之甚少。本文在前人有关西双版纳植物区系研究的基础上, 结合野外调查和标本资料, 对该地区附生植物的物种组成与分布进行了整理。结果表明, 西双版纳热带森林附生维管植物共有29科134属486种, 约占全部维管植物的11%。附生兰科是最丰富的类群(69属293种), 其中以石斛属(Dendrobium) (49种)和石豆兰属(Bulbophyllum) (48种)物种数最多。蕨类是仅次于兰科的附生类群(13科38属97种), 其中水龙骨科(51种)占附生蕨类总数的50%以上。基于生活史和养分来源的划分标准, 该地区48%的附生物种属于兼性附生, 其次是以兰科为主的专性附生(46%), 半附生仅占6%。从区系上看, 西双版纳附生植物属的分布具有明显的热带亚洲性质。附生植物主要分布于资源受限的林冠生境, 对环境变化极为敏感, 在人为干扰日益加剧的背景下, 这类植物正面临严重威胁。因此, 需要加强对西双版纳林冠亚系统的保护。

Diversity and floristic characteristics of vascular epiphytes in the tropical forest of Xishuangbanna

Epiphytes are important structural components of mountain forest ecosystems; however, they have been given insufficient attention because of accessibility issues. In this study, we analyzed the species composition and floristic characteristics of vascular epiphytes in Xishuangbanna using field observations and herbarium specimens, combined with literature records. In total, 486 species (29 families, 134 genera) of vascular epiphytes were identified, contributing to ca. 11% to the Xishuangbanna’s vascular flora. Epiphytic orchids were the most abundant taxa (293 species, 69 genera), dominated by Dendrobium (49 species) and Bulbophyllum (48 species). Epiphytic ferns were the second most abundant taxa (13 families, 38 genera, 97 species), with more than half belonging to Polypodiaceae. Obligate, facultative and hemi-epiphytes accounted for 46%, 48%, and 6% of the species, respectively. Epiphytic orchids were the dominant taxa of obligate epiphytes. Analysis of floristic characteristics at the genus level revealed that epiphytic flora in Xishuangbanna belonged to Tropical Southeast Asia. Without access to soil, epiphytes must explore heterogeneous microhabitat in the forest canopy and are sensitive to environmental changes. They are seriously threatened by anthropogenic disturbances. Therefore, conservation for canopy sub-systems is an urgent and practical need in Xishuangbanna.