Estabelecimento e crescimento de espécies florestais nativas sobre rejeito de mineração na bacia do rio Doce

Abstract

The rupture of the Fundão dam, in Mariana-MG, and the consequent spillage of iron ore tailings, result in the destruction and degradation of extensive areas of riparian forest in the Doce river basin. Mining tailings, added to all types of material that you drag can even be deposited on the banks of rivers, culminating in the formation of a technosol, with depth and variable chemical attributes. It is on this material that new ecosystems can be used, therefore, the effects of the physical, chemical and biological limitations of the technossol on the vegetation, need to be evaluated. In a pioneering way, the present work seeks to evaluate the germination, growth and initial growth of seeds and seedlings of native forest species planted in the technossol of degraded areas in the region of Mariana-MG, under field and controlled conditions of a forest nursery. When planting in the field, the low values of growth and survival observed are largely explained by abiotic factors, mainly by the edaphoclimatic characteristics and trampling of domestic animals. The technosol's high resistance to penetration and low permeability compromises plant growth. However, even in unfavorable environmental conditions, the species with the best performance, indicated for restoration projects of riparian forests by planting seedlings, on the technossol in the Doce river basin, were E. contortisiliqum, G. ulmifolia, H. courbaril, P. nitens, P. guajava, P. dubium and T. americana. In the emergency test, it was found that the humidity conditions influence the seedling emergence on the tailings. E. contortisiliqum, H. courbauril, P. nitens and P. dubium are potential species for use by the direct seeding method on iron ore tailings. In the analysis of different depths of rejection or growth in height and diameter, such as leaf area, leaf biomass and root and quality measures were not influenced by the presence or not. E. contortisiliquum has higher average values of growth in height and leaf dry matter while S. granulosoleprosum exhibits a higher root dry matter in the last depths of the substrate, and compared as two species. Both species can be used in restoration projects of family forests affected by the rupture of the bottom dam. Further studies should be carried out under field conditions.