Modeling carbon emissions from multiple land use transitions in southern Amazonia
Douglas
C
Morton, University of Maryland, morton@geog.umd.edu
(Presenting)
Ruth
S
DeFries, University of Maryland, rdefries@mail.umd.edu
Guido
R
van der Werf, Vrije Universiteit Amsterdam, guido.van.der.werf@falw.vu.nl
James
T
Randerson, University of California Irvine, jranders@uci.edu
Louis
Giglio, SSAI, louis_giglio@ssaihq.com
James
Collatz, NASA-GSFC, george.j.collatz@nasa.gov
Prasad
S
Kasibhatla, Duke University, psk9@duke.edu
Victor
H
Gutierrez, University of Maryland, vgutier@umd.edu
Fires for deforestation and other land cover changes in southern Amazonia are an important source of carbon emissions to the atmosphere. Recent expansion of intensive agriculture has contributed to increases in forest and Cerrado conversion in the region characterized by larger clearings and higher combustion completeness than previous deforestation for cattle ranching. To more accurately quantify the influence of agricultural intensification on carbon emissions, we developed a high-resolution (250 m) model of Deforestation Carbon Fluxes (DECAF). DECAF estimates variations in forest and Cerrado biomass based on time series of MODIS NDVI and explicitly tracks the duration and combustion completeness of new deforestation as a function of post-clearing vegetation phenology and MODIS-based fire frequency. In our model runs for the Brazilian state of Mato Grosso, we quantify the contribution of fires for deforestation, pasture maintenance, and conversion of pasture and Cerrado to mechanized cropland to total fire emissions under low, best, and high emissions scenarios. During 2001-2005, deforestation contributed > 80% of gross fire emissions in the region. Higher combustion completeness for conversions of forest to cropland resulted in fire emissions (21%) disproportionate to the area cleared (14%). Agricultural expansion in non-forest areas accounted for >10% of estimated gross fire emissions, while maintenance fires in pasture and Cerrado land cover types accounted for <10% of all fire emissions during 2001-2005. Results suggest that effective policies to reduce emissions in this region would promote intensification of already-cleared land for cropland conversion and would target large rather than small (<25ha) clearings.
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