Inter-relations between frugivorous vertebrates and pioneer plants: Cecropia, birds and bats in French Guyana

In this study, plant-animal interrelations are examined in the early stages of forest regeneration in French Guyana, where ninety-three percent of the pioneer plants have zoochorous fruits and are mostly exploited by bats or small birds.

Abstract

In this study, plant-animal interrelations are examined in the early stages of forest regeneration in French Guyana. Ninety-three percent of the pioneer plants have zoochorous fruits and are mostly exploited by bats or small birds. They present typical syndromes of ornithochory or chiropterochory, including temporarily extended fruit production strategies. These peculiarities are discussed in relation to the unpredictability of gap occurence (in space and time). Two species of Cecropia compete for colonization of natural gaps and artificial clearings: C. sciadophylla, which is mostly an ornithochore and C. obtusa, which is mostly a chiropterochore. Chemical analysis of C. obtusa pulp shows low concentrations of soluble sugars and free amino acids that bats compensate for by eating large amounts of fruit and rapidly passing the pulp through their intestines. Seed rain evaluations made in different habitats indicate differences in bird and bat patterns of dissemination. These differences are discussed with respect to the occurence of germination: mostly in the periphery of gaps for C. sciadophylla (seed bank origin) and mostly in uprooted trees mounds for C. obtusa (direct seed rain origin).