Avaliação das estratégias de recuperação de áreas degradadas pela mineração de bauxita em Poços de Caldas (MG)

Abstract

This study was carried out in áreas belonging to "ALCOA Alumínio S.A." located at Poços de Caldas, State ofMinas Gerais, Brazil, that explores bauxite mine. Since 1978 they have adopted different procedures to recover the área without any technical evaluation. In this study, five and seven áreas were selected in sites called <cRetiro Branco" and "Santa Rosália" respectively, and a control área for each of these sites. It was observed that in native forest the root system reached 80 cm deep, while in mined áreas only 20 cm deep. Compaction layers were observed in mined áreas at different deep and also rock fragments along the profile. The density values (Ds and Dp) were not always smaller in nature forest at 20 cm deep layer. Ali the procedures contributed to improve ofsoil fertility and were efficients in recovering the biological diversity of these áreas. Among the procedures the most efficient was "bracatinga" {Mimosa scabrella) cultivation. The litter production in the área planted with eucalipt was greater than other áreas. Among the eleven studied áreas only three presented lower annual yields in relation to the control. Three sequences of nutrient leveis of litter were found: Ca>N>K>Mg>P; Ca>N>Mg>K>P and N>Ca>K>Mg>P. The greater amount ofnutrients in the litter were: 361,04 kg/ha ofN; 22,95 kg/ha ofP; 65,73 kg/ha ofK; 544,73 kg/ha ofCa and 74,19 kg/ha ofMg. Only in two áreas were planted a greater number of seedlings than the native forest. In recent procedures, with less than five years, the natural regeneration were greater than the old ones, suggesting one evalution on the process ofrecovering mined áreas.