Tree community dynamics in a submontane forest in southeastern Brazil: growth, recruitment, mortality and changes in species composition over a seven-year period

AUTOR(ES)
FONTE

Acta Bot. Bras.

DATA DE PUBLICAÇÃO

2014-06

RESUMO

In order to assess long-term community dynamics in tree populations, we investigated trees with a diameter at breast height (DBH) > 5 cm in an 11-ha fragment of submontane tropical forest in southeastern Brazil, at the beginning and end of a seven-year period. We observed a general tendency toward decreasing numbers of trees and toward stability in basal area. The stability in basal area was associated with an equilibrium between the loss of trees and the basal area gain from the horizontal growth of surviving trees, as well as from recruits The abundance of dead trees was significantly higher than was that of recruits. Changes in tree abundance occurred mainly in the lower DBH classes, whereas changes in basal area occurred mainly in the intermediate DBH classes. Among trees with a DBH > 10 cm, the observed rates of mortality and recruitment (2.4% yr-1 and 1.8% yr-1, respectively) were similar to those reported for other tropical forests. When we examined only trees with a DBH > 10 cm, we found the half-life to be 29.5 years, which places the forest fragment studied among the most dynamic of tropical forests. Over the seven-year period evaluated, the tree community lost ten species, with no new records. The most abundant species showed the highest rates of mortality and recruitment. Climax species, whether shade-tolerant or light-demanding, accounted for more species and individuals than did pioneer species, suggesting that the former group has a greater influence on forest dynamics. The results suggest that the tree community studied is in or is approaching a state of dynamic equilibrium, the changes in community structure and composition being attributed to periodic fluctuations.

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