Seed dispersal ofSyzygium oblatum(Myrtaceae) by two species of fruit bat (Cynopterus sphinxandRousettus leschenaulti) in South-West China

Abstract

Abstract:In this study we investigated the importance of two species of fruit bat (Rousettus leschenaultiandCynopterus sphinx) as seed dispersers for a species of fruit tree (Syzygium oblatum) found in the Xishuangbanna Tropical Botanical Garden in South-West China. We found that althoughR. leschenaultiandC. sphinxwere the two primary seed dispersers ofS. oblatumover half of the fruit produced by the tree (65%) fell to the ground. Out of the fruit collected,R. leschenaultiandC. sphinxwere able to disperse seeds up to 73 m from the parent tree with the highest density of feeding roosts occurring at 21.3 m (SE = 5.2 m). We found no signs that either species of bat used the parent tree as a feeding roost, instead choosing specific trees that were at lower densities compared with other trees in the forest that were not used. When comparing the viability of seeds in three different habitats (under parent tree, in forest gap, under feeding roost) survival analysis revealed that seedling survival was significantly higher in the forest gap (91.7% ± 4.41%) than under the parent tree (78.3% ± 1.67%), but was not significantly different to seedling survival underneath feeding roosts (86.7 ± 1.67%). Further work also showed that the seeds did not have to be removed from the fruit or ingested by the bat in order to germinate. We conclude that althoughS. oblatumis not dependent onR.leschenaultiandC. sphinxfor successful germination of its seeds, these two species of bat are important seed dispersers and can move seeds to areas where there is a greater chance of germination success and survival.