A substituição de espécies expressa a substituição de funcionalidade ecológica diante de condições edáficas heterogêneas: um estudo de caso nas florestas tropicais sazonalmente secas (FTSS)

Abstract

In this paper we hypothesized that at a local scale functional diversity and species turnover are non-randomly related and the possible relationship between them is mediated by the variations of edaphic conditions.We assume that the functional approach allows a better understanding of the influence of stochastic and deterministic processes on ecological patterns at different spatial scales.For the study we selected five different environments with heterogeneous edaphic characteristics in a Seasonally Dry Tropical Forest (SDTF) region located in Juvenília, extreme north of Minas Gerais, Brazil. In each environment five plots of 20x20m were allocated and soil samples were collected for soil characterization. All individuals withcircumference at breast height(CBH) ≥10cm were identified. Leaves and branches of three individuals of each species were collected to obtain values corresponding to 20 different functional traits.In order to evaluate the relationships between functional traits and species turnover, generalized linear models (GLM) were fitted based on Euclidean distance ofcommunity-weighted mean(CWMs), Euclidean distance of soil texture and Euclidean distance of soil fertility. The substitution of species showed a significant relationship with functional distance, followed by soil texture. The functional distance was positively related to Bray-Curtis dissimilarity. The results confirm the hypothesis, demonstrating that the distribution of the species among the environments occurs by non-random processes, even in local scales, indicating that floristic differentiation and functional distance are related, and conditioned by soil texture. We suggest that future studies contemplate phylogenetic diversity in order to understand the role of evolutionary processes in determining adaptive characteristics and more consistent analyses of the ecological strategies responsible for the long-term persistence of tree species in plant communities.