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LC-38 Abstract

Land-atmosphere Exchanges of Carbon Dioxide and Nitrous Oxide Associated with Agricultural Expansion in the Brazilian Amazon

Carlos Clemente Cerri — CENA - Centro de Energia Nuclear na Agricultura (USP) (SA-PI)
Jerry M. Melillo — Marine Biological Laboratory (US-PI)

Land-cover and land-use changes associated with agricultural expansion are important features of the Brazilian Amazon. In a crescent running from the northeast to the southwest, the clearing of forest and cerrado to create cattle pastures has accelerated over most of the last four decades. Today, pastures and areas of natural vegetation are being converted to mechanized agriculture, primarily soybeans. These shifts in land-cover and land-use have biogeochemical consequences including changes in the dynamics of carbon and nitrogen. In this proposal, we will combine process-based biogeochemistry models TEM and CENTURY with estimates of the extent, spatial pattern, and timing of land-cover and land-use changes to calculate the net land-atmosphere fluxes of CO2 and N2O for this region. For model calibration and testing, we will use data from a number of LBA-supported field studies, including many conducted by our Brazilian/US research team, of biogeochemical dynamics in forests, cerrado, pastures, and soybean fields. To produce a time-series estimate of the major land-cover and land-use transformations associated with agricultural expansion, we will use a combination of agricultural census data taken at the municipio level across the Brazilian Amazon, and extant remote sensing products. In a final synthesis step, we will link the time-series of land-cover and land-use changes with the process models to produce estimates of CO2 and N2O land-atmosphere fluxes for the Brazilian Amazon.

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