Epiphytic Characteristics of Oxystophyllum changjiangense （Orchidaceae） in Bawangling National Nature Reserve,Hainan,China

Key words: 
• habitat /
• host /
• epiphytic /
• bark

Abstract: Oxystophyllum changjiangense is a rare and endangered epiphytic orchid in Hainan Island. In order to explore its epiphytic characteristics,the epiphytic orchard O. changjiangense distributed in Bawangling National Nature Reserve was selected to study its preference to epiphytic hosts,distribution on the host,correlation between population size and DBH or bark texture of hosts based on an systematic investigation of its resource status,habitats and host species. The results showed that O. changjiangensewas were mainly growing on the tall arbor nearby the water resources in the montane rain forest,with 86. 6% individuals found at 800 to 1 000 m above sea level. It was attached to 18 host species,most of which belonged to families Magnoliaceae,Fagaceae,Anacardiaceae,Sterculiaceae or Anacardiaceae. The selectivity index（ SI） ranged from 0. 32 to 0. 94,of which the SI of Michelia mediocris,Reevesia longipetiolataand Castanopsis hystrixis was approximately equal to 1. The individuals of O. changjiangense were were all attached to the first or secondary branches of the host,without any significant difference in selectivity between the first and the secondary branches. The correlation between individual numbers and host DBH was significantly positive（ R = 0. 397,P ＜ 0. 05）. The O. changjiangense has a preference for bark texture.