Influência de variáveis edáficas e tipos de borda na dinâmica florístico-estrutural em um fragmento de floresta atlântica

Abstract

The present study aimed to evaluate the influence of soil type, environment type (dry border, wet border and fragment interior) and time on tree species dynamics in a Semi deciduous Seasonal Forest located in the municipality of Lavras MG, Brazil. The following hypotheses were tested: H1) Small fragments with remarkable environmental heterogeneity present different floristic composition and dynamics according to the characteristics of the environments and types of soils that compose it. H2). The environments most unfavourable to the tree community (drier edges and less fertile soils) have higher rates of dynamics, while those more favourable (moist edge, fragment interior and more fertile soils) have lower rates. Four measurements were carried out in the years 2000, 2005, 2011 and 2017, in which we recorded the DBH and the height of all tree individuals with diameter at breast height (DBH, measured at 1.3m from the ground) equal or superior to 5 cm. Data analysis was performed through the R environment, in which the tree community dynamics was carried out per environment, soil and the total community. Generalised linear mixed models were fitted in order to assess the influence of each variable on community dynamics. The species composition of the observed fragment underwent changes across time, both as a function of the existing habitats and as a function of habitats distinctly in each soil type. The observed pattern for tree community dynamics showed higher dynamics rates for the most restrictive environment of the fragment and for the poorer soil. The most favourable environments (wet and inner edge) and the most fertile soil presented a less accelerated dynamics, with lower rates.