Evaluation of forest restoration techniques in area with Fundão dam tailing in Mariana, Minas Gerais, Brazil.

• Ano de defesa: 2020
• Autor(a) principal: Campanharo, Ítalo Favoreto
• Tipo de documento: Dissertação
• Tipo de acesso: Acesso aberto
• Idioma: eng
• Instituição de defesa: Universidade Federal de Viçosa
• Palavras-chave em Português: Recuperação ecológica; Fertilidade do solo; Biomassa; Recuperação de Áreas Degradadas
• Link de acesso: https://locus.ufv.br//handle/123456789/29226

Forest restoration activities in the areas affected by the Fundão dam rupture, in the municipality of Mariana, MG, have been combining different methods of active and passive restoration. However, there is still a need to compare these methods and define the most efficient ones. It was measured and compiled data of the aboveground biomass (AGB), penetration resistance of tailings and fertility, community diversity, structure attributes and functional traits in 36 plots (12 × 12 m each) distributed in six treatments and six replicas: planting of native tree seedlings with fertilization and pH correction (PSf) and without fertilization and pH correction (PS); seeding of native trees with fertilization and pH correction (SDf) and without fertilization and pH correction (SD); natural regeneration with fertilization and pH correction (NRf) and without fertilization and pH correction (NR). The data on substrate and vegetation were collected in 2019 (2 years and 4 months post- restoration interventions) and the penetration resistance measured in two contrasting periods (dry and wet). No significant differences in penetration resistance between treatments were observed, only between periods (dry and wet). The main univariate model explained the significant effects of depth and seasonality, mainly by a negatively wet effect on penetration resistance. Despite of the early stage of restoration interventions the substrate properties are not limiting the AGB recovery. The study results show how resistance can be an indicator to select the best period to manage the soil and the restoration process. The AGB stored in the plots ranged from 0.06 Mg ha -1 to 10.49 Mg ha -1 , following this order: PSf > PS > SDf > SD > NRf > NR. Although biomass storage between treatments was not statistically different, there is a clear pattern showing higher values for each restoration method where fertilization/correction were used compared with the same methods, but without fertilization and pH correction. No significant differences in soil fertility were found between treatments, the results were similar to the soils found in the region. The only contrasting nutrient was Fe, which demonstrated high values; however, it wasexpected due to the iron tailings deposition. The Pielou index ranged from 0.520 (SDf) to 0.943 (NR), except for SDf all the others treatments had values higher than 0.76. This result suggests evenness in the plant community. On the other hand, the Shannon index ranged from 0.528 (PS) to 1.705 (PSf), however it is a low value compared to those found in areas under restoration processes in Minas Gerais. As expected, at this early stage of the restoration process, the more representative successional group was the pioneer species and the anemochoric syndrome mainly represented by naturally regenerated stems. The autochoric dispersal and the nitrogen-fixing trees showed to be biomass dominant groups, driven mostly by Senna alata, because of its high abundance. It was found that high community-weighted mean of wood density and active restoration methods determine higher levels of AGB on mining tailings. These results support the mass ratio hypothesis, and explain how functional composition as the main predictor determines AGB during restoration. The functional dominance overrides the effects of species richness and abundance on AGB, and hence, it is important to test the mutual effects of functional composition when testing the effects of restoration methods on forest functioning. Overall, active forest restoration showed better responses in the study area, indicating important implications for the forest restoration where natural regeneration is limited. Keywords: Active restoration. Passive restoration. Fertilization. Aboveground biomass. Mining tailings.