Estrutura da vegetação arbórea em um fragmento de Floresta Atlântica em Igarassu, Pernambuco

Abstract

The purpose of this work was to characterize the arboreaus vegetation in a remainder of Atlantic Forest in Mata North of Pernambuco, to analyze the structure of the community in distinct habitats (east and west), to classify the arboreaus species in accordance with the sucessional group and to analyze the floristic and structural similarity between habitats. The study area is situated in the Usina São José, Igarassu- PE, Brazil, with an area of 474 ha. For sampling of the arboreaus individuals, 40 permanent plots of 10,0 x 25,0 m had been installed, totalizing 1,0ha. Twenty plots was installed in the hillside east and 20 in the hillside west, where was included all the woody individuals, with the CAP ≥ 15 cm. In 1 ha, it was showed 1,576 individuals, representing 43 families, 71 genus and 115 species, of which 5 meet indetermined. How much to the sucessional classification 50 species had been classified in early secondary 28 as late secondary, 10 pioneer, and 27 species are without classification. The index of diversity of Shannon (H ') calculated was of 3,62. The families with bigger richness of species were: Myrtaceae (17), Melastomataceae and Mimosaceae (7), Caesalpiniaceae and Sapotaceae (6), Apocynaceae, Fabaceae and Rubiaceae (5). The most individuals (58.6%) is inserted in the first class of diameter and in the intermediate class of height. In the fisionomic comparison between two hillsides, had significant difference to the parameters of basal area (p = 0,02, N=40, gl=38) and average diameter (p = 0.0041, N=40, gl=48), being the biggest values registered for the hillside east. There was difference in the comparison of distribution for height and diameter frequency. In the structural comparison, using the dendrogram of similarity, there was a trend of separation between the hillside east and west, however it wasobserved that the species of the hillside east had appeared forming little groups. The basal area was more influenced by the number of individuals than by the value of diameter, and that the joined species had been classified in bigger percentage as secondary initials, suggesting that the related fragment meets in initial stage of regeneration. The two hillsides showed floristic differences, however the hillside east is more homogeneous. The chemical characteristics of the soil do not showed statistical differences to the orientation east and west of the fragment. Variations of temperature and lightly during the day between the hillsides, can be contributing to the fisionomic and floristic differences between them.