Natural regeneration for restoration of degraded areas after bauxite mining: A case study in the Eastern Amazon

Abstract

Natural regeneration is becoming more frequently used on a global level as a method of ecological restoration after mining operations. The objective of this study was to investigate forest restoration as a function of the exclusive use of natural regeneration in systems with two (NR2) and seven (NR7) years of age after bauxite mining in Eastern Amazon, Brazil (3° 14′ 51″–3° 15′ 48″ S and 47° 44′ 14″–47° 43′ 09″ W). Soil's physical and chemical parameters (organic matter, bulk density, porosity, infiltration, and fertility), landscape-level quantification of vegetation in the areas surrounding the study sites and attributes of the established vegetation (abundance of individuals and families, Shannon diversity index, evenness index, and ecological dominance index) were assessed. The method of natural regeneration, in seven years, was efficient to occupy and cover the soil by regenerating tree and shrub species, as well to contribute to the recovery of important surface-depth attributes of the quality of rebuilt soils, such as organic matter, nutrient availability, density, porosity, and water infiltration. The regenerating tree and shrub species had low diversity and high dominance of a few pioneer species, which indicates the necessity of introducing early and late secondary successional species to correct the successional trajectory in order to ensure the ecosystem restoration.