Biomass and greenhouse-gas emissions from land-use change in Brazil's Amazonian “arc of deforestation”: The states of Mato Grosso and Rondônia

Abstract

We calculate greenhouse-gas emissions from land-use change in Mato Grosso and Rondônia, two states that are responsible for more than half of the deforestation in Brazilian Amazonia. In addition to deforestation (clearing of forest), we also estimate clearing rates and emissions for savannas (especially the cerrado, or central Brazilian savanna), which have not been included in Brazil's monitoring of deforestation. The rate of clearing of savannas was much more rapid in the 1980s and 1990s than in recent years. Over the 2006–2007 period (one year) 204 × 10 3 ha of forest and 30 × 10 3 ha of savanna were cleared in Mato Grosso, representing a gross loss of biomass carbon (above + belowground) of 66.0 and 1.8 × 10 6 MgC, respectively. In the same year in Rondônia, 130 × 10 3 ha of forest was cleared, representing gross losses of biomass of 40.4 × 10 6 MgC. Data on clearing of savanna in Rondônia are unavailable, but the rate is believed to be small in the year in question. Net losses of carbon stock for Mato Grosso forest, Mato Grosso savanna and Rondônia forest were 29.0, 0.5 and 18.5 × 10 6 MgC, respectively. Including soil carbon loss and the effects of trace-gas emissions (using global warming potentials for CH 4 and N 2O from the IPCC's 2007 Fourth Assessment Report), the impact of these emission sources totaled 30.9, 0.6 and 25.4 × 10 6 Mg CO 2-equivalent C, respectively. These impacts approximate the combined effect of logging and clearing because the forest biomasses used are based on surveys conducted before many forests were exposed to logging. The total emission from Mato Grosso and Rondônia of 56.9 × 10 6 Mg CO 2-equivalent C can be compared with Brazil's annual emission of approximately 80 × 10 6 MgC from fossil–fuel combustion.