Composição, estrutura e diversidade em fragmento de mata atlântica no município de São Cristóvão, Sergipe

Abstract

The study of vegetation is an important instrument to subsidize techniques for the recovery of degraded areas, combining the conservation of existing biodiversity in the remnants of the Atlantic Forest. This work aims to know the composition and structure of plants, habits, conservation status, ecological groups and dispersion syndromes of the present species in a remnant of Atlantic Forest, located in the Campus of the Federal University of Sergipe, in the municipality of São Cristóvão, Sergipe. Botanical expeditions were carried out to the remnant forest from September, 2017 to January, 2018. For the analysis of the composition of plant species, a floristic listing was made with families, genera and species. Also, the species were classified according to origin (exotic, naturalized and cultivated); conservation status (endangered, endemic and rare plants); to habit (herbaceous, shrub, tree and climbing); to the ecological group (pioneers, early secondary and late secondary) and to the dispersion syndromes (anemocortical, autocoholic and zoocoric). For analysis of the structure of the shrubby-arboreal component, 30 plots of 20x30 m were installed, systematically distant at intervals of 77 m between each other. Only shrub-arboreal individuals with a diameter at chest height (DCH at 1, 30 m from soil level) ≥ 5 cm were measured. Its composition, structure (horizontal and vertical) and its diversity were analyzed. For all habitats of the remnant, the presence of 133 species, distributed in 114 genera and belonging to 50 botanical families, was observed. Fabaceae was distinguished with the largest number of species (23 species), followed by Asteraceae (11 species). Among the species identified, two of them are endemic to the Atlantic Forest, Ipomoea eriocalyx (Mart. ex. Choisy) Meisn. and Annona glabra L. As for habit, the herbaceous plants presented the largest number of species (69 species), followed by shrubs (25 species). The pioneer species (81) were more representative in the studied fragment, followed by the initial secondary ones (27 species). As for the dispersion syndromes, the anemocoria (54 species) was the most significant. For the structure of the treeshrub component, 1,250 individuals from 24 species, distributed in 22 genera and 14 botanical families, were observed. Shannon-Weaver (H ') diversity indexes of 2.05 and Pielou (J) equability of 0.48 point to low diversity. Amongst the largest IVIs, the species Annona glabra (141,78 ind.ha-1), Syzygium cumini (31,53 ind.ha-1) and Tapirira guianensis (19,821 ind.ha-1) stand out. These species had an absolute density of approximately 964 individuals per hectare, representing 77% of the total sampled individuals in this study. Despite being a Permanent Preservation Area (PPA), the vegetation was reduced about 5 ha in the last 15 years. Despite the advance of the urban area, Matinha da UFS harbors a taxonomic diversity of plants, in different successional strata, with species from other nearby areas that may be sharing this diversity. Due to the quick reduction of the fragment, it is suggested the immediate intervention by the Federal University of Sergipe, with the elaboration of measures that aim the preservation and the recovery ciliary vegetation stretches of the Poxim River.