Frugivory and seed dispersal in tropical urban areas: a review

Abstract

The diversity of fruits and frugivorous species is especially high in tropical regions where frugivory and seed dispersal interactions are particularly critical for the structure and functioning of terrestrial communities. However, the increasing urbanization in tropical areas has caused profound landscape changes, affecting species interactions and associated ecosystems functions. Here, we present an overview of the studies on frugivory and seed dispersal in tropical urban areas, discussing emergent patterns and processes underlying plant-frugivore interactions as well as major research gaps. Our review highlights an uneven geographical distribution of studies, which are more frequent in the Neotropics in comparison to Indomalayan and Afrotropical regions. We found that in tropical urban areas: (i) the most frequently studied group are flying frugivores (birds and bats), (ii) fruits of Myrtaceae, Moraceae, and Arecaceae are most frequently reported as consumed by frugivores, (iii) introduced plants are often present in frugivores’ diets, and become more common with urbanization, (iv) frugivores niche breadths vary with seasonality in fruit availability, (v) a higher diversity of fruits are consumed by frugivores in (or near) habitats that preserve more natural characteristics, such as higher proportion of green areas. Since suitable habitats within cities are highly variable in size, shape, connectivity, patterns of human activity, vegetation management and socioeconomic contexts, we recommend future studies to sample gradients in such variables. Furthermore, as new urban areas are often planned in advance, ‘before-after impact’ studies may be particularly insightful to understand how frugivores respond to urbanization and how to create frugivore-friendly areas without promoting undesirable (invasive) plants. Although the scarcity of studies and their geographical bias limit generalizations across distinct tropical regions, based on our review we provide a preliminary list of broad recommendations of management practices towards creating biodiversity-friendly urban areas.