Abstract

HERNANDEZ, María Elizabeth. Wetland soils as carbon sinks and sources of methane. Terra Latinoam [online]. 2010, vol.28, n.2, pp.139-147. ISSN 2395-8030.

Wetlands cover only 4-6% of earth's surface; however, they play an important role in the planet's carbon (C) cycling. In these ecosystems, C is captured mainly by wetland plants that fix carbon dioxide (CO₂) from the atmosphere and convert it into organic C. Carbon productivities in the range of 0.4-32.0 Mg C ha^-1 year^-1 have been described for wetlands with different characteristics. Organic matter decomposition in wetlands soils is slow due to flooding conditions which favor C accumulation in soils. For different North American wetlands, it has been estimated that soils can accumulate 470-2902 Mg C ha^-1. Flooding causes anaerobic conditions in wetland soils that favor methane (CH₄) production, which is considered a greenhouse gas with a global warming potential 21 times higher than CO₂. Methane fluxes from wetlands soils are in the range of 0.001-1.810 Mg C ha^-1 year^-1. It is necessary to calculate the balance between C sequestration in plants and soils and CH₄ emissions in wetlands, so that C sequestration in these ecosystems is not overrated. In mexican wetlands there are few studies on C sequestration and CH₄ emissions.

Keywords : global warming; methanogenesis; peat; greenhouse gases.

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