Vegetação, biomassa microbiana e características químicas do solo como indicadores de reabilitação de áreas mineradas na Amazônia Oriental.

Abstract

An experiment was made to evaluate the reclamation of mined areas in Porto Trombetas and select soil properties to indicate the stage of reclamation of the altered sites. The studied area is located in Porto Trombetas, Oriximiná county on northwestern Pará, where bauxite is mined on plateaus. The chemical and/or biological characteristics of the arca were obtained from analyses of the soil of the altered and unaltered sites, and the soil samples were collected at 0 - 2.5,2.5 - 10 and 10 – 20 cm depths. Information of vegetation structure and samples of the soil were collected during the period of 1981 to 1994 in 14 sites of rehabilitated topography and landscape and under thinned forest on a Yellow Latosol (YL), taken as reference. Results were subjected to cluster analyses. The low levels of carbon, nitrogen and phosphorus in the altered soil relatively to YL indicated the need for a higher amount of organic matter and a more intensive biological activity for a faster recovery of the altered sites. The characteristics related to the organic matter showed to be a better indicator for the recovery stage in the surface soil. At deeper layers it should be also considered those characteristics related to the soil matrix. Carbon and microbial biomass phosphorus were sensitive indicators for those changes occurring into the altered soil.