Breeding system and pollination of woody species in a subtropical forest invaded by alien plants.

Abstract

: Breeding system and pollination of woody species in a subtropical forest invaded by alien plants. In the riparian forest of Punta Lara (Buenos Aires province, Argentina) seven woody bird-dispersed species coexist, five of which are native (Ocotea acutifolia, Allophylus edulis, Myrsine laetevirens, Blepharocalyx salicifolius and Citharexylum montevidense), and two are invasive aliens (Rubus ulmifolius and Ligustrum lucidum). While seed dispersal of these species has been studied, other aspects of their reproduction are unknown. In this paper we studied the breeding systems, the quality of the pollination service they receive and their floral visitors. All species are xenogamous. One species (M. laetevirens) is anemophilous and the others are visited mostly by Diptera, Hymenoptera and Lepidoptera. For most of the native species the pollination service seems insufficient. In A. edulis and B. salicifolius natural fruit set was lower than that of hand cross-pollinated flowers, only O. acutifolia and the two exotic showed stigmatic pollen loads sufficient to achieve maximum seed production. A possible explanation for the patterns found lies in the reduction of populations of native species due to the expansion of the aliens, particularly L. lucidum.