Environmental Variables Influence the Composition of Frog Communities in Riparian and Semi-Deciduous Forests of the Brazilian Cerrado

Abstract

A central issue for ecologists is to understand the variables that determine species distribution. Many studies have suggested that environmental variables are the main factors that shape anuran communities. Nevertheless, several natural environments have not been assessed with ecological studies of this nature, including specific ecosystems of the South American Cerrado morphoclimatic domain. In the present study, we investigated the relationship between environmental variables and the spatial distribution of anurans in ecosystems of semi-deciduous and riparian forests in a transitional region between the Cerrado and Caatinga environments in the western Bahia state, Brazil. We collected fauna and environmental variables data in 10 sampling units during two rainy periods. The original information on species composition and abundance in the community was reduced to a single axis using a non-metric multidimensional scaling method (NMDS) and environmental data were reduced to two main factors using a principal component analysis (PCA). We tested the absence of an association between the structural variation of the environment and spatial distribution of the anuran community using a multiple regression analysis. The anuran community was ordered following a gradient of dry semi-deciduous seasonal areas toward riparian forest with areas of direct insolation and lentic water bodies. Among the components extracted by the PCA, only PC1 was associated with anuran community composition, explaining 69% of the ordination obtained by the NMDS according to variables related to the presence of water bodies. The great contribution of water bodies appears to reflect the degree of modification of the landscape in the region and seasonal restrictions in the availability of water, with both aspects increasing the expected influence of water bodies on the distribution of anurans in the western Bahia state. Future investigations exploring the structure of anurofauna during dry seasons could extend and complement the results provided by this study.