Long-Term Chronosequence of Forest Succession in the Upper Rio Negro of Colombia and Venezuela

SUMMARY (1) In the upper Rio Negro region of Colombia and Venezuela, a chronosequence of twenty-three stands ranging from recently abandoned fallows to mature forests in a 'tierra firme (unflooded) area was examined for species composition, structure and biomass following slash-and-burn agriculture. (2) Number of species increased during the early stages of succession, with stands twenty to forty years old having a species richness similar to that found in mature forests. (3) Basal area varied from 11 m2 ha- ' in a ten-year-old stand to 37 m2 ha- ' in a mature forest. (4) Allometric relationships between tree dimensions and tree weight were used to estimate biomass harvested in the field. (5) Dry weights are given for leaves, twigs, branches, stems and roots in successional and mature tierrafirme forests. The biomass for each component for ten-year-old and mature forest stands, respectively, was 6-1 1 t ha- ' for leaves, 11-23 t ha- ' for twigs, 9-76 t ha-'