Relações fitogeográficas e padrões estruturais de microescala em uma floresta tropical sazonalmente seca

Abstract

This work studied a fragment of Seasonally Dry Tropical Forest with the aim of evaluated the relationships between microscale edaphic variations and tree communities floristic-structural patterns to test the hypothesis that micro-scale edaphic heterogeneity plays a differentiating role in communities and acts as a diversity potentiator in Seasonally Dry Tropical Forests. The work was based on vegetation and soil data collected in 27 sample units of 20x20 m (400 m²) distributed noncontiguously in a fragment of Seasonal Deciduous Forest located in Juvenília, Minas Gerais State, Brasil. Inside each one, all tree individuals with Circumference at the Breast Height (CBH) greater or equal to 10, 1 cm were measured and identified and the soil collected to form composite samples. We identified three environments in the fragment, which we compared with the chemical and physical soil attributes, as well as the composition and structure of their communities. The relationship between the environments was different for different soil and community characteristics, with the floristic-structural differentiation responding to the edaphic and environmental heterogeneity of the three environments. Each presented a combination of species and structural characteristics in response to their specific environmental conditions. Biogeographic factors may also have had a significant influence on the fragment ecological patterns, considering the occurrence of species not predicted for the region. The results confirmed the proposed hypothesis, with the study forest presenting floristic-structural complexity in microscale associated to soil heterogeneity, which acts as an important factor for the Seasonally Dry Tropical Forests diversity. The results presented in both articles reaffirm the seasonally dry tropical forests diversity and the need to build knowledge about their ecological behavior.