Restoring tropical forests on lands mined for bauxite: Examples from the Brazilian Amazon

Abstract

Restoring self-sustaining tropical forest ecosystems on surface mined sites is a formidable challenge that requires the integration of proven reclamation techniques and reforestation strategies appropriate to specific site conditions, including landscape biodiversity patterns. Restorationists working in most tropical settings are usually hampered by lack of basic information on the wide variety of native tree species that characterize the pre-disturbance forests, as well as insufficient understanding of the ecology of disturbance and natural recovery to design effective restoration programs. A notable exception to this is the forest restoration program developed since the early 1980s by a Brazilian bauxite mining company operating at Trombetas in Pará State in central Amazonia. A systematic nursery and field research strategy was used to develop a reforestation program based on mixed plantings of more than 70 native old-growth forest tree species. This technique has been used to replant about 100 ha of deforested minelands each year over the past 15 years. Research in recent years has evaluated this approach and other, generally simpler, reforestation methods used at a smaller scale at this site. Post-plantation biodiversity development and other indicators of restoration success or sustainability were recorded. The results of these studies have shown the overwhelming importance of careful site preparation and topsoil handling/replacement practices in determining both future productivity and biodiversity of the redeveloping forests, irrespective of the complexity of the planting design used. The inclusion of a wide variety of forest species, particularly later successional species, was very important for long-range restoration owing to limitations on natural recovery processes that inhibit seed dispersal and subsequent colonization of many old-growth forest species. Many of the lessons learned at this site are applicable to improve the design of mineland rehabilitation and forest restoration programs worldwide.