Effect of ants on herbivory levels of Inga laurina: the interplay between space and time in an urban area

Extrafloral nectary plants not only occur in natural areas but also in urban parks. These areas are prone to edge effects, and plants face different microenvironmental conditions. We investigated the spatial variation of ant-plant interactions in an urban park, and we examined if plants with ants would show lower herbivory levels and if it depended on habitat type (interior or edges). Seedlings of Inga laurina were set in 200-m long transects (which covered both the west and east edges, and the interior) in an urban park and then experimentally assigned to be either ant-present or ant-excluded plants. Leaf herbivory was investigated throughout the wet season and was influenced by the interaction effect between ants and habitat type. Ants decreased the herbivory on the west edge, but on the east edge results were the opposite. The east edge had higher temperature and sunlight exposure in comparison to the other sites and was assumed to disrupt the stability of ant-plant interactions. In the interior of the fragment, herbivory depended on ant presence/absence and on the location of plants along the transect. Our study highlights how the outcomes of ant-plant interactions are spatially conditioned and affected by different types of habitats.