Phytogeography of Hong Kong bryophytes

Aim Hong Kong is in a biogeographically interesting location on the northern margins of the Asian tropics. This paper analyzes the phytogeography of Hong Kong's bryophyte flora for the first time. Location Hong Kong lies on the South China coast, 22°9′-22°37′ N, 113°52′-114°30′ E. It is one of the most densely populated places in the world, but because of the rugged topography only 20% of the total land area of 1100 km² is urbanized. Although 130 km south of the Tropic of Cancer, it has a subtropical climate with distinct hot, humid and cool, dry seasons. Methods The analysis is based on a new and relatively complete inventory of Hong Kong's bryoflora. Each taxon was assigned to a phytogeographical pattern on the basis of its present worldwide distribution. Krober's percentage similarity was employed to evaluate the floristic affinities between different regions. Results The bryophyte flora consists of at least 360 species and twelve infraspecific taxa in 159 genera and seventy families, of which four taxa are locally endemic. The largest families are Lejeuneaceae (fifty-one taxa), Fissidentaceae (28), Hypnaceae (21), Dicranaceae (20), Calymperaceae (18), and Sematophyllaceae (15). The largest genera are Fissidens (28), Cololejeunea (17), Lejeunea (10), Syrrhopodon (9), Frullania (8), and Macromitrium (8). Fourteen phytogeographical patterns are recognized. The East Asian pattern is the commonest (seventy-three taxa, 19.6%), followed by Asian-Australian-Oceanian (45, 12.1%) and Temperate (44, 11.8%). Overall, a third of taxa have tropical distributions. The bryofloras of eleven regions were compared with that of Hong Kong. The most similar regions are Hainan Province, Taiwan Province, and Japan. Mosses and liverworts show very similar phytogeographical distributions. Main conclusions (1) The Hong Kong bryoflora is best described as northern marginal tropical, with a strong Eastern Asian and Temperate influence; (2) the region of closest phytogeographical affinity for which information is available is Hainan; (3) in comparison with vascular plants, vertebrates and those invertebrate groups for which there is information, the bryoflora has a relatively low proportion of tropical taxa; (4) the bryoflora of Hong Kong appears to be exceptionally rich for its small area.