Dinâmica da comunidade arbórea em floresta de galeria em Itutinga, MG, Brasil, em um intervalo de 10 anos (1994 a 2004)

Abstract

This work studied the structural changes of an arboreal community in a 10.75-year interval (from 1994 to 2004), at a Gallery Forest in Itutinga, MG, Brazil, 21º 21` S and 044º 36` W. The data were collected in 28 plots measuring 10 x 30 (300 m²), on the banks of a tributary stream that feeds into the Camargos Hydroelectric Dam, Rio Grande Basin . The plots were first arranged in four Blocks, and then subdivided in Border, Middle and Margin sectors. In 1994, all individuals with a diameter at soil level (DSL) ≥ 5 cm were registered, botanically identified, and measured. From 1998 to 2004, the dead individuals were registered; the surviving ones, re-measured and the recruits with DSL ≥ 5 cm were measured and identified. It was calculated the net change rates for the basal area and for the number of individuals, the mortality rates, recruitment, decrease, half-life, doubling time, rotation and amplitude time for each Block and Sector and for the total area sampled. The studies conducted by van den Berg (2001) complemented the analyses on the community dynamics from 1994 to 1998. In between 1994 and 2004, the forest was in a dynamic equilibrium and hardly affected because of the balance between growth and recruitmente and mortality rates. Regarding the number of individuals and the basal area, the doubling time increased from 1998 to 2004 if compared to the period between 1994 and 1998, which suggests a decrease of the biomass production and density gains. In community context, the borders showed higher dynamics rates along the investigated periods, while the differentiated dynamic rates observed during the same two periods at the Block C may be due to past disturbances. The small change observed in the species composition corroborates the community equilibrium proposition, which claims that the species found in the researched area, such as Protium spruceanum, Copaifera langsdorffii, Pera glabrata, Ixora warmingii, Geonoma schottiana, Trichilia emarginata, maintained their dominances along the period probably due to their adaptive advantages in obtaining resources in the diversified environment of a gallery forest.