EVALUATION OF SOIL QUALITY UNDER DIFFERENT FOREST COVERS AND PASTURE IN SOUTHERN MINAS GERAIS STATE, BRAZIL

Native forests have frequently been substituted by Eucalyptus or annual crops cultivation in Brazil. In southern Minas Gerais State the substitution of Araucaria angustifolia forests by agricultural systems or extensive Eucalyptus stands has also been observed. However, few studies are focused on the impacts of such land use changes on soil physical, chemical and microbial and visual aspect of soils. With this goal in mind, different ecosystems were selected, including introduced Eucalyptus and Araucaria and native forest and pasture in Delfim Moreira county, state of Minas Gerais, in the summer 2006. Disturbed and undisturbed soil samples were collected to determine chemical (pH, P, K, Ca, Mg, Al, H + Al, SB, t, T, V, m, organic matter), physical (soil bulk density, soil particle density, flocculation index, mean weight diameter, macro and microporosity) and microbial attributes (microbial activity, qCO(2), microbial biomass, relation microbial biomass / organic carbon). Based on visual aspects related to soil, plants and animals, a visual quality index was calculated for each ecosystem, which proved practical, simple and sensitive to the different vegetation covers. The great majority of the physical and microbial attributes was efficient to evaluate the environmental quality, and indicated high dissimilarity between the pasture and the other ecosystems, and great similarity between the Eucalyptus ecosystem with a well developed understory and that of planted Araucaria.