Variação estrutural e florística da comunidade arbórea em veredas sob efeito de impacto ambiental na APA do rio Pandeiros, MG

Abstract

The objective of this study was to characterize the flora and plant community structure of six veredas (palm swamps) at different stages of conservation through floristic and phytosociological description and comparison of the structure, composition, richness and abundance. In each area 100 plots of 100 m2 were distributed, totaling 6 ha sampling, where we sampled all individuals above the 3 cm in diameter at breast height (DBH, 1.30 m above the ground). The classic quantitative parameters were calculated and the diversity and evenness index, and floristic similarity by cluster analysis. Variations of richness and abundance (GLM) and the structural characteristics of basal area and size distribution were compared among the selected areas. It was determined the relationship between vegetation and environment (CCA) and the preferences of species for specific habitats (ISA). It was found 7965 individuals in 53 families, 102 genera and 165 species identified and three unidentified. The richest families were Fabaceae, Melastomataceae, Myrtaceae and Lauraceae. The 10 most abundant species were Tapirira guianensis, Xylopia emarginata, Zygia latifolia, Cecropia pachystachya, Byrsonima pachyphylla, Myrsine umbellata, Calophyllum brasiliense, Calyptranthes widgreniana, Miconia sp. and Tapirira obtusa. The diversity and evenness indices were 3.573 and 0.698, respectively, for the total sample. There was great phytosociological and structural composition variation. The sites have suffered different levels of degradation and therefore the richness and abundance differed among areas, as well the values of total basal area, height, and diversity varied. These differences show that most disrupted veredas present reduced structural parameters compared to those preserved. The data revealed the formation of three groups: preserved areas, those with intermediate level of disturbance and more disrupted ones. There was also a separation of species. The highest proportion of shade-tolerant and light-demanding species was found in less disturbed areas. Thus anthropic disturbances have caused changes in the natural composition, with loss of species and biomass reduction. It is demonstrated in this study that environmental impacts have affected the structure of the tree community decreasing the richness, abundance and diversity in the veredas with higher rates of degradation