Bryophyte diversity on tree trunks in montane forests of Central Sulawesi, Indonesia

Previous studies have shown that submontane forests of Sulawesi harbor a very rich bryophyte flora, with more than 150 species occurring on eight canopy trees. We explore the relationships of trunk base bryophyte communities with elevation and tree characteristics (tree diameter, bark roughness) in montane forests of Sulawesi. The study showed that submontane, lower montane and upper montane forests of Sulawesi are characterized by very different bryophyte taxa. Calymperaceae, Fissidentaceae, Hypopterygiaceae, Lejeuneaceae, Leucobryaceae, Lophocoleaceae, Meteoriaceae, Neckeraceae, Porellaceae, Pterobryaceae Radulaceae and Thuidiaceae are mainly found at low elevations, while Herbertacaeae, Lepidoziaceae, Mastigophoraceae, Scapaniaceae, Schistochilaceae and Trichocoleaceae predominate at high elevations. Lejeuneaceae are the most important family in submontane and lower montane forests in terms of number of species, and Lepidoziaceae in upper montane forest. Plagiochilaceae are prevalent in lower montane forest. In general, species richness of liverworts increases towards higher elevation whereas moss richness decreases. Similar trends are observed elsewhere in the Tropics. Trunk community similarity decreases with distance and is about 25% between Sulawesi and Borneo, and virtually nil across continents. A few species showed a significant preference for rough bark but none for smooth bark. In general, trees with rough bark had more species than those with smooth bark. Trunk diameter correlated with the distribution of a few species but not with community composition or species richness. Our data are first statistically-supported evidence for bark roughness and trunkdiameter specificity of bryophyte diversity in tree-species rich tropical forest.