Estrutura e composição florística da comunidade arbustivo-arbórea de uma clareira de origem antrópica, em uma floresta estacional semidecídua montana, Lavras-MG, Brasil

Abstract

This study analyzes the structure and the floristic composition of the tree and shrub community naturally regenerating in a forest gap of anthropogenic origin. This gap embraces about 3.2 hectares, and is located at the Quedas do Rio Bonito Forest Park, in Lavras, south of Minas Gerais, Brazil. It was formed in October of 1992 by a clearcut and totally abandoned afterwards. The original vegetation is Montane Semideciduous Seasonal Forest with Emergent Canopy. The natural regeneration was sampled with 20 circular plots, subdivided into three subplots of three sizes (4, 6 and 10 m2), in order to measure all individuals of three height classes (0,3 to 1m, 1 to 3m and above 3m heigh and up to 5cm DBH). The sampled 445 individuals belong to 49 species and 23 families. This community had a mean height of 2,32m and mean density of 36.136 individuals/ha. The four families with the largest number of individuals were: Asteraceae, Euphorbiaceae, Melastomataceae and Myrtaceae. The natural regeneration in the vicinity of the forest border was denser than in the centre of the gap, 20.134,70 and 16.001,20 individuals/ha, respectively. The species that presented the higher values of importance (VI), total natural regeneration and relative sociological position were: Baccharis dracunculifolia, Croton floribundus, Myrcia velutina, Baccharis sp., Vernonia polyanthes, Daphnopsis brasiliensis, Machaerium villosum, Myrsine coriacea, Tibouchina candolleana, T. fothergillae and T. moricandiana. Regarding to spacial distribution of the species, 61,22% had an aggregated pattern, 36,73% random pattern and 2,05% uniform pattern. The Shannon diversity index was 3,097. Pioneer and light demanding climax species presented very similar density, 17.309 and 17.601 individuals/ha, respectively, while shade tolerant climaxs species had 1.226 individuals/ha.