CONICET | Buscador de Institutos y Recursos Humanos

tDeforestation affects climate and the energy balance of the Earth not only through the release of green-house gases but also through shifts in the physical properties of the surface. These physical effects can bestrongly dependent not only on the deforestation event but on the land use choices and management thatfollow it. Here we explored how the albedo and radiation balance of the dry subtropical Chaco forests ofSouth America changed over the last decade in response to both deforestation and land use/management.For the whole region we analyzed changes in the mean annual albedo derived from MODIS imagery andtheir relation with the dominant land use trajectories for a 12-year period (2000?2012). In two focal areaswe identified how specific land uses and management shifts affected the seasonality of surface albedoand green vegetation cover, quantifying their associated radiation budget changes and radiative forcingeffects. Deforestation accounted for 83% of the regional albedo increase observed in Chaco, yet, land useand land management changes were also a main driver of albedo shifts, explaining the rest of the albedorise occurred in the region. Albedo raises increased the mean annual outgoing shortwave energy fluxat the top of the atmosphere producing a biophysical cooling effect which was strongly dependent onthe land use choice and agricultural management, ranging from −8 W m−2in silvopastoral systems to−17 W m−2under single annual cropping schemes. These values are equivalent to a reduction in atmo-spheric CO2of 12?27 Mg C ha−1, or 15?55% of the typical emissions that accompany deforestation inthis region. Land use and management choices in the Chaco region produce strong divergences in theresulting albedo seasonality that should not be ignored in the assessment of their net climatic effects andthe discussion of possible mitigation actions.

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