ABSTRACT Ant diversity is influenced by the structural complexity of the environment. Ants are thus an ecologically important group due to their potential to serve as indicators of environmental quality. The objective of this study was to evaluate ant diversity in areas with different land use histories and thus, within different stages of regeneration in the Permanent Preservation Area of the Foz do Chapecó Hydroelectric Plant reservoir. Ant assemblies among sample sites were compared using rarefaction analysis, and estimated richness, frequency of occurrence, and relative abundance were calculated. Associations between species and sample sites were evaluated using Principal Component Analysis (PCA). We identified 55 species in total from 24 genera, distributed among seven subfamilies. Eight species had positive associations with sample sites. Estimates indicated that ant richness may be up to 21.4% greater than that observed. This study presents an inventory of species capable of colonizing environments undergoing natural regeneration processes, and aids our understanding of ecological recovery dynamics in protected areas near hydroelectric plant reservoirs southern Brazil.

A diversidade e a estrutura das comunidades biológicas são afetadas pela intensificação das atividades antrópicas. Este estudo avaliou a estrutura das assembleias de formigas de quatro tipos de ambientes ao longo de um gradiente de intensidade de perturbação antrópica em dez cidades situadas na região austral do Domínio Mata Atlântica. Os ambientes avaliados foram: fragmentos florestais, áreas verdes, escolas e centros de reciclagem. Foram realizadas duas amostragens durante o ano de 2011, uma em fevereiro e março e outra em outubro e novembro. Para a comparação das assembleias de formigas foi desenvolvida uma análise de rarefação baseada no número de ocorrências nos quatro tipos de ambientes. A composição das assembleias foi verificada através de um teste de aninhamento utilizando a métrica a NODF. A associação das espécies de formigas com os ambientes amostrados foi obtida por meio de uma Análise de Espécies Indicadoras (ISA). Foram encontradas diferenças significativas de riqueza e de abundância entre os ambientes, mostrando uma tendência de redução nos ambientes escolares e centros de reciclagem em relação aos fragmentos florestais e áreas verdes. Observou-se um padrão de aninhamento ao longo do gradiente, ou seja, as assembleias pertencentes aos ambientes sob maior pressão antrópica são subconjuntos da mirmecofauna dos ambientes mais conservados. Não houve alteração da composição das assembleias, e sim uma perda importante de espécies de um ambiente para outro. Os fragmentos florestais apresentaram o maior número de espécies indicadoras (12), seguido pelas áreas verdes (4) e escolas (3). Os resultados podem ajudar na implementação de políticas de desenvolvimento urbano e na elaboração de planos de conservação.

Ant community structure (Hymenoptera: Formicidae) in four environments with different levels of human disturbance: The diversity and biological communities structure are affected by the intensification of human activities. This study evaluated the ant community structure from four types of environments with different levels of human disturbance intensity at ten cities in the southern region of the Atlantic Forest Biome. The environments were: forest fragments, green areas, schools, and recycling centers. Two samplings were conducted in 2011, one in February and March and another in October and November. To compare the ant assemblages, it was performed a rarefaction analysis based on occurrences number. The composition of the assemblages was evaluated by a nestedness test using the NODF metric. The association of ant species with the environments was obtained by an Indicator Species Analysis (ISA). Significant differences in richness and abundance were found between the environments, showing a downward trend in schools and recycling centers in relation to forest fragments and green areas. There was a nesting pattern along the gradient, ie the assemblies belonging to the high human pressure environments are subsets of the conserved ones. There was no change in the composition of the assemblies, but a significant loss of species from one environment to another. The forest fragments had the highest number of indicator species (12), followed by green areas (4) and schools (3). The results can help in the implementation of urban development policies and development of conservation plans.