Composição, estrutura e similaridade florística do estrato arbóreo de três fragmentos de Floresta Atlântica, na Serra Negra, município de Rio Preto, Minas Gerais, Brasil

Abstract

The Atlantic Forest is considered the eighth greater hotspot of the world due high biodiversity and to the degree of degradation. Regions of Atlantic Forest in Minas Gerais state, still without inventory studies, have been proposed as priority for the scientific inquiry. The Serra Negra, in the city of Rio Preto, is one of these regions with no information on its composition and structure. The region understands a flooding area, surrounded for some stretches of mountain forests of the Mantiqueira Range and high mountains fields, between the rises of the massif of Itatiaia (RJ, SP e MG) and the Serra do Ibitipoca (MG). The objective of this study was to determine the flora´s composition, structure, the similarity between three samples of Atlantic Forest in the Serra Negra range and the similarity with other studies. Three areas were selected, each one composed for 25 contiguous parcels of 10 x 10 m, totalizing 0,75 ha. of sampled area, with criterion of inclusion bigger or equal to 10 cm of CAP. The calculated phytossociology parameters were: density, frequency, basal area and value of importance. The horizontal and vertical structure of the areas were described, the diversity was calculated by the index of Shannon and the test of hypothesis on differences between the two indices was carried through by the test proposed by Hutcheson. The similarity was calculated through the index of Sørensen and Jaccard. Detrended Correspondence Analysis between the sampled areas and Cluster Analysis with other works had been carried through. It was showed 2573 individuals, identified in 195 morphospecies, enclosed in 59 families, 115 genus and 180 species. The families with bigger wealth were Myrtaceae (30 morphospecies), Lauraceae (20), Melastomataceae (17) and Fabaceae (13). The sorts with bigger number of species were Ocotea and Miconia (12 morfo-species each), Eugenia and Myrcia (eight morfo-species each), Casearia and Solanum (four species each). The most abundant species were Myrciaria tenella (DC.) O.Berg, Alchornea triplinervia Müll. Arg., Aparisthmium cordatum (Juss) Baill., Guapira venosa (Choisy) Lundell. From the details of composition and structure, the samples could have been differentiated in Aluvial Rain Forest (Mata do Cambuí), Lower Montane Rain Forest (Mata do Benedito) and Upper Montane Rain Forest (Mata do Ninho da Égua).