Tree Communities in Three-Year-Old Post-Mining Sites Under Different Forest Restoration Techniques in the Brazilian Amazon

Forest loss and degradation in the Brazilian Amazon due to mining activities has been intense for many years. To reverse this situation, a range of restoration programs for deforested and degraded areas have been created and implemented. The aim of this study was to analyze the tree composition, successional stage, dispersal and pollination syndromes, conservation status of tree species, and proximity to seed sources under different forest restoration techniques (seedling planting, natural regeneration, and assisted natural regeneration or nucleation) implemented in post-mining sites in the Paragominas municipality (Para, Brazil). Sixty permanent plots with a restoration age of three years were selected for tree sampling. A total of 119 species, 83 genera and 27 botanical families were identified. Sites restored with different techniques significantly differed in tree composition. Seedling planting sites exhibited the highest abundance, species richness, and diversity values. These were dominated less by pioneer species when compared to the natural regeneration and nucleation sites. Entomophilic pollination and zoochory dispersal were highly represented in the three types of restored sites. Abundance and species richness were negatively correlated with distance from plots to seed sources, and they sharply declined in natural regeneration and nucleation plots at >250 m from seed sources. Four threatened species were identified in the restored sites. We conclude that a combination of different restoration strategies at three-year-old post-mining restoration sites in the Brazilian Amazon results in the recovery of considerable levels of local tree diversity.