Florística e estrutura da regeneração natural da vegetação ciliar do Rio Pandeiros, norte de Minas Gerais

Abstract

Despite their species richness, importance and although they are protected by law, the riparian vegetation has been gradually destroyed. This study focused in two main objectives: (1) evaluating the floristic composition and structure of natural regeneration of the river Pandeiros, through sampling different sectors of the river, since the spring until the estuary, focusing as the basin as a whole, as the similarity between the different sectors of the river; and (2) studying the possible correlations between the variable of fisionomic structure and the diversity and composition of species from the regenerating shrub/tree community and the environmental variations of one among the sampled points (Balneário), aiming to answer wich environmental factors are preponderant in the spatial distribution of the species in regeneration. For this, had been made, in six sectors of the riparian vegetation of the river Pandeiros, the sampling of the stratum regenerating in 70 plots/ each (5 x 5 m) being comprised individuals between ≥ 1 cm of DSH and < 5 cm of DBH. To determine the influence of environmental characteristics on the floristic and structure of regeneration were gotten some edafics variable, the opening of the canopy and the flooding regime in each plot. Besides the traditional calculations of the phytosociological parameters and grouping analysis to check the similarity betwen the areas, an canonical correspondence analysis it was made to verify the being relations between the environmental variable and the distribution of species in one of the sampled points. In the 420 plots, had been found 232 species shrub/tree, distributed in 152 genera and 57 families. The five families that showed greatest species richness were Fabaceae, with 55 species, Myrtaceae, with 24, Rubiaceae, with 12, Annonaceae with 10 and Anacardiaceae with eight. Were sampled 4374 individual and the more representative species were: Tapirira guianensis, Siparuna guianensis, Blepharocalyx salicifolius, Erythroxylum deciduum and Ladenbergia cujabensis. There were the formation of similarity groups, with Larga and São Domingos areas have been showing bigger similarity, the Agropop and Balneário areas showing little similarity, and Catolé area showed certain similarity with the two cited groups and the Pântano area dissimilar in relationchip the other areas, probably due to ocorrence periodical flooding. Thus, had been a floristic differentiation throughout the river, confirming that near areas are more similar that far areas. Concerning the influence of the environment variable on vegetation of Balneário area, the canonical correspondence analyses showed respectively autovalue of 0,6 and 0,48 for axis 1 and 2. The parcels were divided in three groups, the first group being more influenced by proximity to the calcareous outcrops; the second group by luminosity and flooding regime, and the third by ground fertility (addition of bases). Although there are common species to all groups, many species were exclusive to each group, showing that environmental variable had been influenced the distribution of species.