贡嘎山石松类和蕨类植物的多样性与海拔分布

Species diversity and altitudinal distribution of lycophytes and ferns in Gongga Mountain

关键词:  区系, 贡嘎山, 濒危物种, 温带成分, 海拔分布

Key words:  floristics, Gongga Mountain, endangered species, temperate elements, altitudinal distribution

摘要:

贡嘎山是横断山脉海拔最高的一座大山,是研究山地植物多样性和海拔分布的理想地区。为了探讨贡嘎山地区石松类和蕨类植物多样性组成及海拔分布特点,该研究基于野外考察、标本采集鉴定及文献考证,对贡嘎山地区石松类和蕨类植物进行统计和分析。结果表明:(1)贡嘎山地区有石松类植物3科4属25种,蕨类植物有23科56属291种。(2)主要的珍稀濒危植物有6种,分别是高寒水韭(Isoëtes hypsophila)、松叶蕨(Psilotum nudum)、桫椤(Alsophila spinulosa)、小叶中国蕨(Aleuritopteris albofusca)、玉龙蕨(Polystichum glaciale)和扇蕨(Lepisorus palmatopedatus)。(3)优势科为鳞毛蕨科(Dryopteridaceae)75种、水龙骨科(Polypodiaceae)56种、凤尾蕨科(Pteridaceae)54种和蹄盖蕨科(Athyriaceae)37种; 优势属为耳蕨属(Polystichum)45种、鳞毛蕨属(Dryopteris)24种、蹄盖蕨属(Athyrium)24种和瓦韦属(Lepisorus)19种。(4)区系以温带成分为主,有286种(93.77%)。随着海拔的上升,石松类和蕨类的物种多样性逐渐增加,2 000～3 000 m海拔段的物种多样性最高,为20科46属192种,3 000 m以上物种多样性逐渐下降,4 500 m以上仅分布有4种蕨类植物。此外,该研究还发现,随着海拔的升高,中国-喜马拉雅成分逐渐增加。

Abstract:

Gongga Mountain is the highest peak of Hengduan Mountains and is an adequate site to study species diversity and the successive distribution of species along altitude. In this study we present an account of the species diversity and floristic characters of lycophytes and ferns in Gongga Mountain based on field survey, specimens identification, and literatures reviewing. The results are as follows:(1)A total of 316 species of 60 genera in 26 families of lycophytes and ferns were recognised in this study.(2)Of these species, six species are assessed to be rare and endangered and need special protection in China. They are Isoëtes hypsophila, Psilotum nudum, Alsophila spinulosa, Aleuritopteris albofusca, Polystichum glaciale and Lepisorus palmatopedatus.(3)Of the fern flora in this mountain, the largest four families are Dryopteridaceae(75 species), Polypodiaceae(56 species), Pteridaceae(54 species), and Athyriaceae(37 species); The largest four genera are Polystichum (45 species), Dryopteris(24 species), Athyrium (24 species), and Lepisorus(19 species).(4)Temperate species are the dominant floristic elements(286 species, 93.77%)in this mountain. With the ascending of the elevation from 1 000 to 3 000 m, the species diversity gradually increases, which reaches the highest at the zone between 2 000-3 000 m where 192 species(belonging to 60 genera in 20 families)were recorded, and above 3 000 m, the species diversity declines, with only four species of ferns found over 4 500 m. When viewing the floristic elements, the Sino-Himalaya species are found to be gradually increased along the ascension of elevations.