Estabelecimento de espécies florestais em diferentes condições de sítio após mineração de caulim na Amazônia Oriental

Abstract

The Amazon is the largest tropical rainforest in the world, home to more than 10% of terrestrial biodiversity and an estimated 15,000 tree species. Kaolin mining causes significant changes in the landscape, including the destruction of native vegetation, soil compaction, and the creation of barren areas, which compromise biodiversity and ecosystem services. In this context, the general objective of this thesis was to investigate how different silvicultural practices can catalyze the recovery of degraded areas, promoting ecological restoration and the initial establishment of forest species in reconstructed soils (Technosols). Chapter 1 presents the general introduction, the objectives and hypotheses of the research chapters, as well as the theoretical framework supporting the thesis. Chapter 2 evaluates the impact of planting pit size on the chemical properties of Technosol and on the establishment and productivity of four forest species (Parkia multijuga, Moquilea tomentosa, Terminalia argentea, and Tapirira guianensis) after 24 months of planting. The results suggested that physical changes to the Technosol, such as increasing pit size, did not affect its chemical properties. However, these changes effectively enhanced survival, growth, and aboveground biomass accumulation, highlighting the relevance of physical interventions to improve soil conditions in mined areas. Chapter 3 explored, through separate experiments, how different management techniques (organic compost and trenches versus liming and larger planting pits) impact the physical and chemical properties of Technosol after 20 months of restoration interventions. The results showed significant improvements in pH, organic matter, and cation exchange capacity, along with reduced soil compaction, creating a more favorable microenvironment for the establishment of native vegetation. Chapter 4 investigated, through distinct experiments, the performance of four native Amazonian forest species (Byrsonima spp., Clitoria fairchildiana, Inga edulis, and Tachigali vulgaris) under different planting methods, 18 months after restoration interventions. Techniques such as trenches and the use of organic compost proved superior in promoting the survival and initial growth of the investigated species. Clitoria fairchildiana stood out with a 100% survival rate in almost all treatments. Chapter 5 presents the final considerations of the thesis and practical implications for forest restoration in mining-impacted areas. The results provide practical and innovative guidelines for forest restoration in areas degraded by mining in the Amazon. By combining adaptive management of Technosol with the selection of well-adapted native species, it was possible to accelerate the recovery of ecological functions and structure resilient plant communities. It is also hoped that the outcomes achieved will stimulate the implementation of restoration programs that meet legal requirements, promote socio-environmental benefits, and align with global biodiversity conservation and climate change mitigation goals.