Tropical wetlands as a carbon source

Abstract

Wetlands have long been recognized as a carbon sink, and a suggestion has been made that this may have served in the past several centuries to balance out releases from reduction of forests in the world. Cultural exploitation of wetland areas, such as excavation during exploration for fossil fuel and minerals, draining for farming of grain and fiber and production of animal protein, invariably results in the oxidation of the carbon storage sink. Destructive wetland alterations which reduce or remove the vegetative cover also decrease the fixation of atmospheric carbon, thus resulting in a net carbon release from wetlands. Wetland excavation for peat extraction is estimated to oxidize 472 metric tons of stored carbon per 1000 metric tons of dry peat combusted, while 375 metric tons of carbon are released from one hectare of mangrove swamp cleared and dug out for fish pond construction. Increasing and widespread alterations of this nature convert wetlands to a carbon source and could therefore play a significant role in the global cycle of carbon.