Implications of regional agricultural land use dynamics and deforestation associated with sugarcane expansion for soil carbon stocks in Brazil

The use of bioenergy to replace fossil energy has grown in recent years, raising concerns about the “carbon (C) neutrality” of bioenergy and the benefits of its use to enhance energy security and mitigate climate change. In Brazil, sugarcane ethanol is a feasible option and can result in negative greenhouse gas (GHG) emissions through replacement of fossil fuels. This study evaluated the direct deforestation triggered by sugarcane expansion in Mata Atlântica and Cerrado biomes considering the periods of intense expansion from 2002 to 2008 and the stagnation of sugarcane production from 2009 to 2016. The expansion and associated land use changes (LUC) were evaluated and quantified to address direct effects on deforestation, soil C stocks, and associated GHG emissions/removals in two Brazilian watersheds. Most of deforestation in both biomes occurred before 2002. Two percent of the sugarcane expansion caused direct deforestation between 2002 and 2008. From 2009 to 2016, 3% of the new sugarcane areas were located outside the Sugarcane Agroecological Zoning program. Regarding the assessed basins, almost six times more deforestation was observed in Goiás basin (~ 15,000 ha) than in São Paulo basin (~ 2500 ha). Deforestation in Goiás basin was strongly linked to expansion of annual crops, while in São Paulo basin reforestation has occurred. Lastly, sugarcane expansion had negligible impacts on the overall soil C budget for both basins. This assessment is an important step forward for incorporating LUC-induced emissions to develop and evaluate GHG mitigation strategies towards greater sustainability of sugarcane production in Brazil.