Diversity and distribution of vascular epiphytes in the tropical natural coniferous forest of Hainan Island,China
海南岛热带天然针叶林附生维管植物多样性和分布

Aims As one of the most distinctive components of tropical forests, vascular epiphytes play vital roles in maintaining biodiversity and ecosystem functioning. The diversity and distribution of vascular epiphytes in tropical natural coniferous forest are reported systematically for the first time in this study. Our objective was to explore species richness, abundance, distribution patterns, and relationship between vascular epiphytes and host trees in the only Pinus latteri natural forest with large area in China. Methods Twelve plots of 10 m × 50 m were established in the tropical natural coniferous forest in Bawangling National Nature Reserve, Hainan Island, China. We recorded species, individuals and height of attachment of vascular epiphytes on each tree ≥ 5 cm diameter at breast height (DBH). Based on two datasets (individuals in each subplot of 10 m × 10 m and on each host tree), the horizontal distribution pattern of vascular epiphytes was analyzed using Kolmogorov-Smirnov test and Variance-to-mean Ratio. Based on species and individuals at 5 m intervals from the forest bottom to the top, the vertical structure of vascular epiphyte assemblages was analyzed. The relationship between vascular epiphytes and host tree size was assessed using Spearman correlation. Important findings We recorded 769 individual vascular epiphytes belonging to 27 species, 17 genera and 7 families in the total sample 0.6 hm2. The Orchidaceae and Asclepiadaceae were dominant. The vascular epiphytes were clumped horizontally. Vertically, 49.3% were at intermediate heights (10–20 m) and 19.0% at 0–5 m, but only 7.2% were at >25 m. Most vascular epiphytes showed no preference for host trees, but a few species, e.g., Phlegmariurus fordii, Eria rosea, Dischidia chinensis and Hoya pottsii had higher occurrence rates on the host tree of Pinus latteri. Vascular epiphyte abundance and species richness were both significantly positively correlated with host tree size.