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Soil loss in pastures was 160 times greater than in preserved areasÂngela Macário / Getty ImagesThe conversion of native vegetation into pasture and agricultural land over recent decades has accelerated soil erosion in the Cerrado (a wooded savanna biome), at least temporarily. By analyzing the concentration of different varieties (isotopes) of chemical elements that remain stable in the soil and atmosphere for hundreds of thousands of years, as well as others that undergo transformations within decades, an international group of scientists estimated the soil denudation rate in central Brazil over the last 50 years. Led by a group from the Federal University of Goiás (UFG) and the European Center for Research and Teaching in Environmental Geosciences (CEREGE), based in France, a team collected soil and sediment samples from rivers in and around Brasília National Park, a conservation area created in the federal capital in 1961. Soil loss was approximately 0.01 millimeters (mm) per year, close to the level observed in other areas of Cerrado. In areas converted for pasture or agriculture, the erosion rate was up to 1.6 mm per year (160 times greater), especially between 1975 and 1985, when most of the region’s original vegetation was cut down (Earth’s Future, August 10).
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