Emissions of N₂O, CH₄ and CO₂ from tropical forest soils

Abstract

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.