Dynamic equilibrium and decelerating growth of a seasonal Neotropical gallery forest in the Brazilian savanna

摘要

Describing and understanding growth patterns in tropical forests is crucial to assessing their role in carbon balance. Growth and vital rates of a protected gallery forest in central Brazil were estimated, based on six measurement intervals between 1985 and 2009. The sample consisted of all stems >= 10 cm diameter at breast height measured in 151 permanent plots (10 x 20 m), distributed in 10 transects perpendicular to the watercourse and 100 m apart from each other. Statistical significance of changes in density, basal area, growth and vital rates were tested using Wilcoxon signed-rank tests. Vital rates oscillated during the study period. Growth, recruitment and turnover rates fluctuated, but had a net decrease over the whole study period, whereas mortality seemed to be affected by a high disturbance event during the 1994-1999 period. The oscillatory behaviour of growth suggests that the forest is pulsating around a stable state (dynamic equilibrium). Nonetheless, persistence of decelerating growth trends may force the site's carrying capacity to a lower density or biomass state.