Dinâmica do estrato arbóreo em um gradiente florestal da estação ecológica do Panga, Uberlândia, Mg (1997-2002)

Abstract

The study was developed in a constituted forest gradient of three communities (gallery forest, semideciduous forest and “cerradão”) in the Panga Ecological Station, Uberlândia, Minas Gerais, Brazil (19th 09 ' 20 " S, 48th 23 ' 20 " W). The dominant vegetation in the region is the cerrado, and the Station is a representative area of several fitofisionomias that happen in this. The purpose of this paper was to accomplish a temporal analysis of structure and dynamics of the arboreal component of the gradient and your three communities, being appraised the temporal changes in floristic composition, density, basal area, mortality rates and recruitment, and life strategies of some species. They were sampled 211 plots (10 X 10 m) contiguous in eight transects approximately parallel and perpendicular to the Panga Stream (totaling 2.11 ha), in 1997 and 2002. They were made measures of all the individuais' circumference with minimum of 15 cm (DBH = 4,77 cm). The gallery forests, semideciduous forest and the “cerradão” presented entrances and exits of species of the sampling, and movements in positions of importance. In relation to the variations in the density and basal area, the forests presented similar changes, with decrease in the density and increase in basal area. However, the disparity among those measured it went larger for the semideciduos forest, suggesting that was more dynamic than the gallery forest, and that reached a State later sucessíonal in relation to the first inventory. The “cerradão” also presented expressive variations in the floristic composition, but differently of the forests, it presented considerable increase, in basal area and in density, becoming a forest physiognomy after five years. Probably, for being located in the border of the gradient, constituting an ecotone, that allowed a larger light entrance and it provided the increase in those parameters. The expressive variations of the number of individuais and of the basal area in some species were to diagnose those that best represented the changes happened in the communities among the two inventories. The forest gradient, as a whole, presented high dynamics and demonstrated to be in progress in the succession and recovering of the human disturbance of the past, and with characteristics of riper forest formations. The period of five years was satisfactory to verify considerable changes in the arboreal component, suggesting that studies of that nature adopt that interval of time as the minimum for the accompaniment of the vegetation in other areas of the cerrado.