Eucalyptus Edge Effect on Quercus-Herbivore Interactions in a Neotropical Temperate Forest.

Abstract

Fragmentation leads to the formation of edges between habitats, which in turn changes biotic and abiotic factors that might influence herbivory or plant-herbivory interactions. The aims of this study were to describe the herbivory community associated with oak (Quercus) and to determine the effects of proximity to a Eucalyptus edge and season on insect herbivory. We selected three forest sites that were subsequently divided into three quadrants located at different distances from the Eucalyptus edge: edge (0m), intermediate (30m), and oak forest interior (60m). We randomly selected 10 oak trees per quadrant and conducted monthly surveys, during the dry and rainy season (from February to October 2010), where we quantified leaf area and the percentage of herbivory. These were analyzed using linear mixed models, with distance and season as fixed factors and individual and site as random factors. The primary oak herbivores were Lepidoptera caterpillars. We found that herbivory increased away from the edge but just during the rainy season, although higher herbivory levels were found during the dry season. These results seem to be related to a specialist community of herbivorous associated to the Quercus. This study emphasizes the importance of considering border effect, especially within Natural Protected Areas to establish strategies to improve and maintain native oak forest and the biodiversity of its Lepidoptera herbivorous community.