Vegetative functional traits guide plant species selection for initial mineland rehabilitation

Abstract Functional ecology provides useful tools for selecting native species for rehabilitation purposes. Here, we evaluated a list of native tree and shrub species as candidates for use in waste pile rehabilitation in the Carajas National Forest, eastern Amazon, Brazil, to increase the diversity and stability of the reinstated communities. Native species lists were compiled from vegetation inventories performed in two different ecosystems in the region, i.e., dense evergreen Amazonian forests and ferriferous savannah formations, locally known as cangas. For prospection, we evaluated the functional differences among the forest, canga and waste pile communities and computed the functional space defined by wood density and 14 leaf traits of species that had already established during former rehabilitation efforts targeting the waste piles. Native species falling within this trait space were selected for further initial rehabilitation activities, while species outside this space were considered unsuitable for this purpose. As a proof of concept, we compared the survival of seedlings of selected and nonselected tree species to evaluate their potential for initial rehabilitation activities. We found functional differences in the communities between the rehabilitating waste piles and natural environments but higher functional congruence with forest than with canga ecosystems, making the conversion of waste piles into forests more likely. The assessment of functional differences enabled the identification of additional species for initial waste pile rehabilitation; we present a list of 76 candidates for future waste pile rehabilitation activities in Carajas National Forest. Our approach was validated by the seedling survival experiment, where selected species showed higher survival than nonselected species, highlighting the suitability of the selected species for initial waste pile rehabilitation in the region to increase the species richness and functional redundancy of the reinstated communities. The validation via the seedling survival experiment furthermore encourages the replication of the proposed functional prospection procedure for other environments to be rehabilitated, with different species sets being sought for different regions.