Restoration of degraded areas after bauxite mining in the eastern Amazon: Which method to apply?

• Published in: Ecological engineering 2022-07, Vol.180, p.106639, Article 106639
• Main Authors: Barbosa, Rodrigo de Souza, Vale, Rodrigo Silva do, Schwartz, Gustavo, Martins, Walmer Bruno Rocha, Ribeiro, Sabrina Santos, Matos Rodrigues, Julia Isabella de, Ferreira, Gracialda Costa, Barbosa, Victor Moreira
• Format: Article
• Language: English
• Subjects: Bauxite; Bayer process; Conservation; Conservation status; Diversity indices; Ecosystem restoration; Environmental degradation; Environmental impact; Environmental restoration; Indicators; Methods; Mining; Natural regeneration; Nucleation; Plant species; Regeneration (biological); Restoration methods; Restoration monitoring; Seedling planting; Seedlings; Species; Species diversity; Wildlife conservation
• ISSN: 0925-8574; 1872-6992
• DOI: 10.1016/j.ecoleng.2022.106639

The Amazon has one of the largest bauxite reserves in the world and the growing demand for this ore intensifies environmental impacts and, consequently, the necessity of ecosystems restoration. In this sense, the monitoring of indicators is essential to ensure the restoration success. The objective of this study was to evaluate indicators of ecosystem restoration in areas degraded by bauxite mining in the eastern Amazon, Brazil, under three different restoration methods: Nucleation (NC), Seedling planting (SP), and induction of natural regeneration (NR) in comparison with a reference forest (RF). Structural and compositional indicators, including density, frequency, and dominance, as well as the Importance Value Index (IVI) of tree species, mortality, conservation status, diversity indices, and Mean Annual Increase in height and diameter (MAIH and MAIDBH) were assessed. Solanum crinitum, Cecropia distachya, Senegalia polyphylla, and Qualea grandiflora were the most important species according to IVI for SP, NR, NC, and RF, respectively. In SP, MAIH and MAIDBH were higher than in the other treatments, however, the difference between methods was not of significant. The diversity indices of the three restoration methods tested were close to those of RF. Four species with some conservation status were identified; Cedrela odorata, Genipa americana, Swietenia macrophylla, and Hymenaea parvifolia, all native to the eastern Amazon. Thus, through the indicators, we found that all restoration methods showed positive indicators of restoration and a gradual return of the structural characteristics of the vegetation. •Seedling planting did not present advantages over regeneration and nucleation.•Density is an indicator of short-term restoration, unlike basal area.•Seedling planting presented greater increment in height and diameter.•There were no differences among methods regarding the diversity indexes.•Endangered species should have priority in restoration projects.