Seed predation and dispersal of Ardisia solanacea in habitats with different degree of disturbance.
Effective dispersal is one essential course for invasive species on their process of invasion, while study on the effectiveness of seed dispersal was often neglected when predicting species' invasion. Native to Tropical Asia, Ardisia elliptica is an invasive species in North America. A. solanacea is a tree naturally distributed in southern Yunnan with biological characteristics similar to A. elliptica. In this study, we conducted observation on seed dispersal and seed predation of A. solanacea in two habitats with different degree of disturbance: the Wild Elephant Valley (WEV) with few disturbances and the Xishuangbanna Tropical Botanical Garden (XTBG) with high disturbances. The aim of the study was to understand how disturbances affect seed dispersal and seed predation of A. solanacea. In both habitats, three frugivorous birds were the main seed dispersers, i.e., Alophoixus pallidus, Pycnonotus melanicterus and Iole propinqua. However, the visiting frequency and feeding behaviour differed in the two habitats. In WEV, the visiting frequency of the three birds was 25%, 32% and 26%, respectively; while in XTBG, it was 67%, 8% and 5%, respectively. Only 4% of the birds got first stop far than 10 m away from the fruiting tree after feeding in WEV, but 26% in XTBG. Seed placement experiment indicated that rodents were the major predators to the seeds on ground. The predation rate in both habitats were rather low (2-6%) while seed predation rate in WEV was significantly higher than that in XTBG. In WEV, larvae of Curculionidae were another seed predator, which caused 17.9±3.5% (n=512) of seeds parasitized. In contrast, no seeds was found to be parasitized by the larvae (n=489) in XTBG. Disturbance significantly affect the composition and behaviour of animals inhabited. Consequently, those changes may influence seed dispersal and seed predation of related plants, and indirectly, affect the population recruitment of plants.