Habitat integrity drives Odonata diversity in Eucalyptus-dominated landscape.

Abstract

Silviculture can be considered a sustainable alternative to the extraction of wood from natural forests in Brazil. However, the high demand for wood products has decreased the area of natural Cerrado due to land transformation for forestry activities. This transformation could lead to the loss of species, including insects that cannot tolerate the new environment dominated by exotic plant species. This study aims to evaluate whether the presence of an extensive Eucalyptus silviculture in the Brazilian Cerrado decreases the integrity of nearby riparian environments and, consequently, decreases odonate diversity. Thirteen ponds were selected in patches of Cerrado embedded within a matrix of Eucalyptus silviculture in order to assess habitat integrity of ponds and their riparian zones and collect adult odonates. The physical integrity of the study sites was measured using a Habitat Integrity Index (HII) designed to determine the degree of conservation of aquatic environments. The HII of the study sites varied between 0.44 and 0.80, indicating differences in the degree of conservation. Therefore, a positive relationship was found between odonate richness and abundance and HII, and between the abundance of zygopterans and anisopterans and HII. These findings may be due to the fact that these insects are adapted to the natural resources maintained at the most conserved habitats, and which were lost in degraded riparian zones, such as the presence of aquatic vegetation and a diversity of organic debris on pond banks. We conclude that the conversion of natural areas to Eucalyptus silviculture can alter the integrity of nearby riparian zones and, consequently, odonate diversity.