Surveys of the tree community, topography and soils of a fragment of tropical semideciduous forest were carried out with the purpose of assessing the impacts of a fire that struck the forest in 1999 on the community structure and tree species composition and diversity, as well as the relationship between fire severity and variables of the physical environment. The forest fragment, with an area of 57ha, is situated at 21º09'S of latitude and 44º50'W of longitude, in the municipality of Ibituruna, Minas Gerais state, Brazil. The surveys were carried out in two sectors of the fragment. There were two surveys in the Slope sector: the first, in 1997 (before the fire), within fifteen 5×50 m sample plots, and the second, in 2001 (after the fire), within thirteen 20×20 m sample plots. A single survey was carried out in the Valley sector within thirteen 20×20 m sample plots distributed along the frontline, defined by the maximum fire propagation. The surveys registered the species, the circumference at breast height and the total height of trees with diameter at breast height (dbh) > 5 cm. Topographic variables, soil chemical and textural variables, a fire damage index (FDI), and an edge factor were obtained for each sample plot. The fire caused considerable impacts to the arboreal component of the vegetation. Tree density and total basal area decreased and this was particularly concentrated in the classes of smallest diameter and height. Where fire severity was higher (> FDI), there were higher proportions of standing dead over surviving trees, expressed as both density and basal area. In the Slope sector, the species of lower stature at maturity dropped in the rank of relative abundances after the fire. Two years after the fire, there was an increase in tree species richness and diversity probably due to the addition of pioneer species in fire-opened areas. No correlations were detected between the FDI and the edge factor, not even any of the topographic or soil variables,
environmental impact; fire damage; forest fire; environment-vegetation relationship; tropical seasonal forest
