TROPICAL FORESTS AS SINKS OF ATMOSPHERIC CARBON

Changes in land use and rates of carbon accumulation by land use including mature, logged, and fallow tropical forests, and degraded tropical lands are used to estimate the role that the tropical landscape serves as sinks of atmospheric carbon. Results indicate that in 1980 tropical lands may remove between 1.5 and 3.2 Pg C from the atmosphere. We excluded from the analysis some 900 million ha of open tropical forests that could also be removing carbon from the atmosphere and an additional 0.5-0.6 Pg C year-1 sink associated with carbon export by rivers and in wood products. Our analysis challenges assumptions about the steady-state condition of the carbon budget of mature tropical forests and suggests that large areas of the tropical landscape are recovering from disturbance and act as atmospheric carbon sinks. We focus attention on sinks of atmospheric carbon only. In 1980, the estimated accumulation of carbon in the recovering landscape was equal to the net carbon flux due to tropical deforestation.