Interactions between the invasive treeMelia azedarach(Meliaceae) and native frugivores in South Africa

Abstract

Abstract:The spread of many invasive plants is facilitated through seed dispersal by frugivorous animals. The effectiveness of various frugivores as dispersers of the seeds ofMelia azedarach, a highly invasive alien tree species, was evaluated in South Africa in savanna and bushveld vegetation. During 264 h of observation, seven bird species and one bat species were recorded foraging on fruiting trees ofM. azedarach. The most common visitors were the dark-capped bulbul (Pycnonotus barbatus) followed by Wahlberg's epauletted fruit bat (Epomophorus wahlbergi), but both species dropped nearly as many seeds as they dispersed. Knysna turaco (Tauraco corythaix) dispersed the highest number of fruits per minute, but occurred in low abundance in our study sites. Seed germination differed significantly between de-pulped fruits and untreated fruits after 2 mo, but was similar after 4 mo. Germination success did not differ between animal-handled and hand-depulped fruits. In contrast to the high germination success in the greenhouse, seedlings showed very low recruitment in the field. Thus,M. azedarachseems likely to benefit from frugivores (particularly dark-capped bulbul and Wahlberg's epauletted fruit bat) dispersing seeds to suitable microsites.