The Net Flux of Carbon from Deforestation and Degradation in South and Southeast Asia

Abstract

Changes in the area of forests in South and Southeast Asia between 1850 and 1990 were studied, and the resulting release of carbon to the atmosphere was estimated to be between 19.2 and 32.6 Pg. The range results from uncertainty in the average biomass of forests in the region. Some current estimates of average biomass are higher than others. If these high and low estimates are taken to represent undisturbed and degraded forests, respectively, then these estimates of biomass can be used with estimates of the area of forests in 1980, their average biomass, and data from Flint and Richards on temporal trends in the ratio of degradation to deforestation to help constrain the biomass of the forests actually deforested during the 140 years studied. With these constraints, the total net flux of carbon was calculated and found to be 29.5 PgC, 54% higher than that calculated with low estimates of biomass and 10% lower than that calculated with high estimates of biomass. Thus, although the lower estimates of biomass may be good estimates of current biomass in Asia, they are inadequate for calculation of carbon emissions from deforestation unless the calculations explicitly include degradation as well as deforestation. Of the total net release, 19.8 PgC (67%) was found to be from deforestation, and 9.7 PgC (33%) from degradation.KeywordsTropical ForestGlobal Carbon CycleAverage BiomassMoist ForestDeforestation RateThese keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.