关键词: 兰科植物, 物种多样性, 海拔梯度, 相似性系数, 象头山

Abstract: A specific wild survey of orchids was conducted in Xiangtoushan National Nature Reserve, Guangdong province from 2019 to 2022. The species, population size, life forms, altitude and habitats were recorded about these orchids. The elevational distribution patterns were analyzed. Meanwhile, the endangered status of the recorded orchids was counted?according to The Provincial Red List of Higher Plants in Guangdong and the List of Key Protected Wild Plants in China. The results showed that: (1) 48 species of orchids belonging to 33 genera were recorded, most of which had small populations; (2) The orchid species diversity showed a hump-shaped pattern along the elevational gradient with a peak at mid-elevations, of which terrestrial, epiphytic, and saprophytic orchids showed the same trend; (3) The endangered species were mainly concentrated at 200–500 m; (4) The similarity coefficient of orchid species was higher at adjacent elevations, while the similarity coefficient was lower at greater elevation gradient. The species diversity of orchids decreased at low elevations probably due to the frequent human disturbance. And the mid-elevations owned the higher orchid species diversity partly because the habitat is suitable for the survival of orchids. A few orchids appeared in high elevations with the limited available resources for the growth and development of orchids.

Key words: Orchidaceae, species diversity, elevation gradient, similarity coefficient, Xiangtoushan