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Biogeographic theory has been given much attention for its potential application to biodiversity conservation in areas fragmented through anthropic action. The objective of this study was to determine whether ant community structure established in natural woodland fragments immersed in a matrix of natural grasslands could be explained by this theory. We therefore investigated whether the relationship between species richness and both area and isolation that have previously been found in anthropogenically formed forest fragments are applicable to naturally formed forest fragments. The sampling consisted of eight natural woodland fragments with varying areas and degrees of isolation. Sampling was undertaken proportionally to the fragment size, and each sampling point was spaced at least 10 m apart. Ants were collected from each point through arboreal and epigeic “pitfall” traps. In addition, five epigeic traps were placed 100 m from each sampled fragment in the adjacent grassland. A total of 81 ant species were sampled. Total and epigaeic species richness increased with size of area and fragment isolation. However, arboreal ants responded positively only with respect to increasing area, but not with isolation. Moreover, specialist and generalist species richness had a positive relationship with area, but not with isolation. Biogeographic Theory can only be applied to some of the patterns found in the natural fragments in the present study. This positive relationship of ant richness and isolation suggests that these environments bear unique characteristics and therefore, must be regarded as conservation targets. The results obtained in this study suggest the need for further studies, to reinforce the importance of biodiversity conservation of this characteristic habitat in the Pantanal.

We evaluated ants as bioindicators of environmental impacts caused by arsenic residuals in the soil. We tested the hypotheses that the presence of arsenic in the soil affects: (1) estimates of resources and habitat condition for arboreal and epigaeic ants; (2) species richness of arboreal and epigaeic ants and (3) arboreal and epigaeic ant species composition. Ants were sampled at an inactivated raticide factory in Nova Lima, Minas Gerais, Brasil, which used arsenic as one of its main byproducts. The following environmental variables were measured: bioavailable arsenic concentration in the soil, the number and density of tree species, plant cover and leaf litter depth. The species richness of arboreal ants decreased with increased bioavailable arsenic concentration whilst epigaeic ants increased with arsenic. Arboreal ants were positively related to the number of tree species, which in turn were negatively affected by arsenic. We verified which ants are good bioindicators of arsenic. Independent verification of the influence of arsenic on background environmental variables was fundamental in defining responses of ant communities, as well as in identifying the most effective pathways for the recovery of biological communities in degraded areas.