广东象头山国家级自然保护区兰科植物垂直分布格局

于2019～2022年对广东象头山国家级自然保护区内的兰科植物进行专项调查，记录兰科植物种类、数量、生活型、海拔、生境等信息，分析保护区内兰科植物的垂直分布格局，并根据《广东高等植物红色名录》和《国家重点保护野生植物名录》对各海拔高度兰花濒危等级的物种数量进行统计。结果显示：(1) 实地记录兰科植物33属48种，多数种类种群数量较少；(2) 随着海拔上升，各海拔梯度的兰科植物总种数和不同生活型的种数均呈现“中间高度膨胀型”分布特点，峰值在中低海拔区域；(3) 濒危物种主要集中在海拔200～500 m区间；(4) 相邻海拔段的兰科植物种类相似性系数较高，垂直梯度差异越大，相似性系数越小。低海拔地区可能由于人为干扰频繁，兰科植物物种多样性较低；中海拔物种多样性最丰富；高海拔地区生长环境较苛刻，物种数量较少。

Elevational Distribution Patterns of Orchids in Xiangtoushan National Nature Reserve,Guangdong Province

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.