Influência de Variáveis Ambientais e Espaciais na Estrutura da Comunidade Arbórea em Área Sob Tensão Ecológica entre Floresta Estacional Decidual e Semidecidual no Sudoeste de Minas Gerais, Brasil

Abstract

This paper had the objective of verifying the influence of environmental and spatial variables in the structure of the tree component, in a gradient of transition deciduous/semideciduous forest in Arcos, M.G. 30 plots of 10 × 40m were established, distributed in three transects, positioned at a perpendicular angle to the gradient axis. In each plot, all individuals with DBH ≥ 3.2cm were identified and measured and environmental, chemical, textural, physical, as well as spatial variables were collected. The relationship between environmental variables and species distribution was tested by means of the canonical correspondence analysis, presenting the geographic position of the plots as covariable. The analysis of indicator species for the plot groups was also carried out. The plots separated themselves in two distinct groups, deciduous and semideciduous physiognomy, that didn´t differ as far as structure, but differed in terms of species composition and in correlations with soil variables. The sum of bases and the rock coverage positively influenced the deciduous physiognomy, where is the depth of the soil, Fe and S were positively correlated with the semideciduous physiognomy. The deciduous physiognomy showed itself to be more heterogeneous, with greater number of allochthonous species and smaller number of indicator species. The first class of diameter is constituted mainly by deciduous physiognomy individuals while the two subsequent classes had a greater number of individuals of semideciduous physiognomy. In this way, factors linked to the nutritional condition and to the soil depth apparently are the main factors responsible for the differences between the physiognomies.