DIVERSITY, STRUCTURE AND DYNAMICS OF A GALLERY FOREST IN CENTRAL BRAZIL

The structure and dynamics of approximately 64 ha of undisturbed galle ry forest were studied over six years. Trees from 31 cm gbh (c. 10 cm dbh) were measured every three years from 1985. They were in 151 (10x2 0 m) permanent plots in the Gama forest in the Federal District of Bra zil. Natural regeneration (individuals under 31 cm gbh) was measured i n subplots (of 2x2 m, 5x5 m and 10x10 m) within the 200 m(2) plots. Th e total tree flora (gbh greater than or equal to 31 cm) consisted of 9 3 species, 81 genera and 44 families in 1985. The Leguminosae, Myrtace ae and Rubiaceae were the families richest in number of species. Most individuals and species were under 45 cm diameter and 20 m high while the maximum diameter per species ranged from 30 to 95 cm. The density structure of trees and natural regeneration was similar, in which the densities of c. 80% of the species represented less than 1% of the tot al density. The periodic mean annual diameter increment for trees from 10 cm dbh, was c. 0.25 cm/year. Variability was high with coefficient s of variation c. 100% or more. The Gama community may maintain tree d iversity and structure in undisturbed conditions. Regeneration of c. 8 0% of the species was found in the establishing phase (poles); the dia meter structure was typical of native forests with the number of indiv iduals decreasing with increasing size classes and showing little chan ge over the six years; recruitment compensated for the mortality of mo st of the abundant species. The soils in Gama gallery forest were dyst rophic with high aluminium content. Multivariate analysis suggested th e stream, natural gaps and edges as the main causes of floristic diffe rentiation at the community level.