RESTORATION OF IRONSTONES OUTCROPS DEGRADED BY IRON MINNING ACTIVITY IN MINAS GERAIS STATE-BRAZIL 1

Abstract

The properties of the soils and underlying substrates of "canga" (ironstones outcrops) in central Brazil have a number of restrictions for the establishment of plant species, and the high specialization of local vegetation contributes to a high rate of endemic adaptations. The close association between the mining of iron and the need for locally adapted vegetation presents a special condition of vulnerability. This study evaluated varied approaches to the restoration of "canga" fields considering technical and economic aspects related to the application of topsoil, re-introduction of plants from local sources and their regeneration. We set up a field experiment on one overburden pile of Capao Xavier iron mine (mined by the Vale Company), composed of eight treatments formed from combinations of two thicknesses of "canga" and associated salvaged soils (20 and 40 cm) and four levels of fertilization. In each plot, we planted the same number of seedlings following the same spatial arrangement. The evaluation of the treatments was made at 10 and 42 months after planting for survival of the planted species. There was no significant difference among the average survival of seedlings planted for the different thicknesses of substrate and fertilization levels. The development of programs for ecological restoration of ferruginous fields should therefore consider, among other factors, the complex soil x vegetation mosaic commonly found in natural settings and thus carry out the "canga" material soil reconstruction sequence in order to reproduce this scenario. Furthermore, in view of the possible reduction in the number of plant individuals over time, there must be a satisfactory amount of individual species selected for reintroduction.