Avaliação de uma área em restauração pós-mineração de bauxita, município de Descoberto, MG

• Autor(a) principal: Silva, Kelly de Almeida
• Data de Publicação: 2013
• Tipo de documento: Dissertação
• Idioma: por
• Título da fonte: LOCUS Repositório Institucional da UFV
• Texto Completo: http://locus.ufv.br/handle/123456789/3137
• topic: Restauração pós-mineração; Bauxita; Post-mining restoration; Bauxite; CNPQ::CIENCIAS AGRARIAS::RECURSOS FLORESTAIS E ENGENHARIA FLORESTAL::CONSERVACAO DA NATUREZA

The aim of this study was to evaluate the indicators of vegetation, the soil seed bank and the regeneration layer in an area which is being restored after bauxite mining as well as studying the species which are used for the restoration of the mining area. The studied area has 4 hectares and it is under restoration since 2011. For the evaluation of the structural characteristics of the planted individuals, 20 plots of 9 x 6 m were marked out, with a distance of 10 m between plots. Three things were measured: diameter at ground level, the height and the mortality rate of the trees planted in the studied area. For the analysis of the seed bank, 40 plots of 3 x 3 m were assigned, with a distance of 10 m between plots and a sample of the ground in the center of each plot was collected (0.30 x 0.25 x 0.05 m) for the evaluation in greenhouse, of the number of individuals and the identification of the species of the emerged seedling, during 6 months. For the analysis of the natural regeneration layer, 40 permanent plots of 3 x 3m were allocated in the restoration place, at intervals of 10 m between plots. All the woody tree individuals with circumference at 1.30m of height less than 15 cm were identified. Moreover, the diameter at ground level and the height of the ones were measured. Five stratus with different distances of a forest fragment were considered in order to evaluate the influence of a secondary forest fragment besides the studied area in the floristic composition of seed bank and regeneration of the area. These stratus were: Stratus 1- zero meters; Stratus 2 - 10 meters; Stratus 3 - 20 meters; Stratus 4 - 30 meters and the Stratus 5 - 40 meters. The average and the standard deviation were perfomed for the variable density of the individuals, number of species, coefficient of dispersion, succession category and life habit and made a comparison among the stratus using the variance analysis (ANOVA) and Tukey s test at 5% level. At sampling area were found 540 living trees of 700 planted (22.86% of mortality), belonging to 45 species and 18 families. The species with the highest importance values (VI) were Solanum lycocarpum (14.7%) and Schinus terebinthifolius (10.8%). The species S. terebinthifolius, S. lycocarpum and Joannesia princeps, contributed 30.36% crown cover. The average height of planted species ranged from 0.40 m to 3.90 m. Seed bank in the soil, there were 394 weed seedlings (131 seedlings m-2), belonging to 11 families and 31 species. The richest family was Asteraceae (8 species). The seed bank showed H' = 2.41 and J' = 0.704. Survey in the natural regeneration stratus was sampled 66 individuals belonging to 20 species and 12 families, with a density of 1.833 individuals ha-1. The richest families were Asteraceae (4 species), Fabaceae (3) and Solanaceae (3). There is a higher proportion of dispersal zoochory (60%) to the species and a higher proportion of dispersal anemochory (56%) for number of individuals. Regarding the category of succession, there is a greater proportion of the category of the pioneers for species (60%), and for number of individuals (81.8%). The species with the highest VI were Trema micrantha, Vernonanthura divaricata and Baccharis dracunculifolia, with 63.95% of the total VI and 57.58% of the individuals sampled. The regeneration layer presented H' = 2.35 and J' = 0.786. Regarding the habit of living among the stratus, there was a predominance of tree species in stratus 1 (0.01 < p < 0.05). For the individuals average distributed in different succession groups, there was a significant difference (0.01 < p < 0.05) among stratus with stratus 1 showing higher average number of pioneers. Regarding dispersion syndrome, distribution of the average number of species and individuals natural regeneration, it significantly (0.01 < p < 0.05) greater proportion syndrome zoochory the stratus 1. There was a good species diversity used for planting restoration of the mined area, already provide benefits to the area in restoration with land cover through their hearts. The soil seed bank of the restoration site had a high density of herbaceous species, but with species best adapted to the initial conditions of restoration that has degraded by mining. The density of individuals and species richness in natural regeneration stratus may be related to the short time of area restoration, proximity to grazing areas, low potential seed rain and seed bank.