Emissions of N2O, CH4 and CO2 from tropical forest soils

Emissions of nitrous oxide, methane, and carbon dioxide were measured at diverse locations in tropical forests of Brazil, Ecuador, and Puerto Rico, using a static open chamber technique. Mean fluxes to the atmosphere were 1.7 × 10 10 , −0.7 × 10 10 , and 1.5 × 10 14 molecules cm −2 s −1 for N 2 O, CH 4 , and CO 2 , respectively. The data indicate that tropical forests contribute a significant fraction of the global source for atmospheric N 2 O, about 40% of the current source and possibly 75% of the preindustrial source. Methane is consumed by soils on average, but the sink is an insignificant part (<5%) of the atmospheric cycle for the gas. Emissions of CO 2 from forest soils are higher at equatorial sites than at middle or high latitudes, as expected from ecological considerations. Soils emit CO 2 at rates more than twice as large as the rate of carbon infall in litter; hence much of the emitted CO 2 must arise from root metabolism.