CARBON IN TROPICAL WETLANDS

About half of the world's wetlands area is found in the tropics. The i mportance of wetlands to the global carbon cycle, water balance, wildl ife, biodiversity and human food production is much greater than their proportional surface area on Earth (7%) would suggest. High net prima ry production of organic matter produced by retarded decomposition mak e natural tropical wetlands an important sink for carbon. About 250 Gt carbon are conserved in tropical wetlands. Tropical wetlands are also a significant source for atmospheric methane. Wetland rice agricultur e alone contributes 5 to 20% to the global methane budget. Rice, the s table food for about half of mankind, is grown on tropical wetlands. S mall differences in climate, water and nutrient regimes, and land use can drastically change the delicate balance of tropical wetlands. (C) 1997 Elsevier Science B.V.