Dinâmica da comunidade arbórea em uma floresta estacional semidecidual sob queimadas recorrentes

Abstract

The effects of fire on tree mortality can change floristic and forest structure depending on intensity, frequency and the length of a fire. Areas of semideciduous forest in Parque Estadual da Serra Azul, Barra do Garças (MT, Brazil), exposed to different frequencies of fire, were monitored: 0.9 ha burned in 2007 (Q1) and 0.9 ha in 2005 and 2007 (Q2). The dynamics were based on the average interval of 2.02 years between T1 (outubro/2006-maio/2007) and T2 (March/2009), including individuals with PAP ≥ 15 cm. Diversity (H') and species richness (estimated by Jackknife) were higher in Q2, in both at T1 and T2. The decrease of tree density between surveys was significant for Q1 and Q2, but the proportion of deaths was higher in Q1. There were no differences in the dynamic parameters between Q1 and Q2 when considering both the number of individuals and basal area. The increase of diversity in Q2 may be partially explained by the hypothesis of inter- mediate disturbance. However, despite the absence of differences in recruitment and mortality between Q1 and Q2, the high turnover rates, independent of fire frequency, suggest future changes in the flora and structure of the forest if fire continues to be frequent in the area.