CHANGES IN THE CARBON BALANCE OF TROPICAL FORESTS - EVIDENCE FROM LONG-TERM PLOTS

The role of the world's forests as a ''sink'' for atmospheric carbon d ioxide is the subject of active debate. Long-term monitoring of plots in mature humid tropical forests concentrated in South America reveale d that biomass gain by tree growth exceeded Losses from tree death in 38 of 50 Neotropical sites. These forest plots have accumulated 0.71 t on, plus or minus 0.34 ton, of carbon per hectare per year in recent d ecades. The data suggest that Neotropical forests may be a significant carbon sink, reducing the rate of increase in atmospheric carbon diox ide.