The austral thrush (Turdus falcklandii) reduces the seed germination for the urban ornamental tree glossy privet (Ligustrum lucidum) in Santiago, Chile

Abstract

Seed dispersal by endozoochory is an important mechanism promoting the spread of exotic fleshy-fruit plants. Although the invasiveness of glossy privet (Ligustrum lucidum W.T. Aiton) in several regions has been associated with the presence of disperser birds, only a few studies have examined their seed germination after dispersal. In Central Chile, the privet grown is an ornamental species, but to date, it has not been observed to settle in natural or seminatural habitats. In Santiago city, the fruits of glossy privet are mainly consumed by the austral thrush (Turdus falcklandii Quoy & Gaimard), which could act as dispersers of their seeds. For this reason, we analyzed the role of endozoochory by the austral thrushes on the germination of glossy privet. We collected seeds from trees and feces of austral thrushes, and then we compared their viabilities and germination percentages. Viability was established using the tetrazolium test, while germination was studied using a factorial experiment (10 seeds in Petri dishes, replicated nine times for both sources). Our results showed that the germination of seeds from feces (58.3 %) was 12 % lower than those from trees (77.7 %), indicating that austral thrushes reduces significantly the germination percentage of the glossy privet. The viabilities of seeds from fruits and feces were 100 %. Because these values may be high enough to allow the population establishment, we suggest that further studies are necessary to examine the role of the endozoochory in the (unsuccessful) spread of the glossy privet in Chile.