Partição da diversidade de formigas em uma paisagem fragmentada / Ant diversity partitioning in a fragmented landscape

AUTOR(ES)
FONTE

IBICT - Instituto Brasileiro de Informação em Ciência e Tecnologia

DATA DE PUBLICAÇÃO

26/07/2010

RESUMO

Forest fragmentation events have been characterized as one of the main threats to biodiversity in modern times, and are the primary cause of species loss in tropical forests. Ants are organisms that present many suitable traits to be used in ecological studies, therefore they are frequently used in fragmentation surveys. However only epigaeic microhabitat have been considered in these studies, neglecting other important microhabitats. Hence, with this study we aimed to answer the following question: Why are there more ant species in forest remnants compared to matrices? We made explanatory hypotheses, in which environmental variables were taken as surrogates of resources and conditions. The study was carried out in four forest remnants and four surrounding matrices in Viçosa municipality, Minas Gerais state, Brazil. Ants were sampled with pitfall traps in two microhabitats, epigaeic and hypogaeic, with unbaited pitfall traps. The diversity was partitioned, following the equation γ = α + β. An ANOVA was made at each scale to test the assumption that fragment harbour more species than matrices. Explanatory variables were analysed through hierarchical partitioning to find out which variables are more important in explaining species richness and using GLM to depict the relationships among variables. Estimators of species richness were employed to asses the effect of fragmentation in the landscape. Species composition was tested through NMDS and significance values were obtained by ANOSIM. We confirmed our assumption only for β and γ diversity. The most important variables to explain diversity were %Sand (-), CEC (+), iron concentration (-) and soil organic matter (unimodal). Variation among environmental parameters in relation to fragmentation explained the variations in species richness. We found differences in species composition, with forest habitats being distinct from matrices at both epi- and hypogaeic microhabitats. A distinction between epigaeic/hypogaeic communities was found only in forest environments. We confirmed our assumption and confirmed that some variables are important for explaining species loss caused by fragmentation. It give support to the fact that alterations caused on environmental quality are important and must beconsidered. Moreover, species composition revealed that there are specific subsets in each local, matrices and forests. Still, the lack of difference in species composition between microhabitats in matrices reveals the strong effect of fragmentation on some hypogaeic species, that should depend on litter, that is not available after vegetation clearance.

ASSUNTO(S)

ecologia ecossistemas floresta atlântica formigas fragmentação partição aditiva uso da terra ecologia de ecossistemas ecology forest atlântica ecosystem ants fragmentation additive partitioning land use

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