Carbon sequestration and fluxes

Freshwater wetlands play a substantial role in the sequestration and long-term storage of carbon from the atmosphere and yet can be a potential source of greenhouse gases emissions; especially methane. Tropical and subtropical wetlands are affected by hydroperiods, whereby they may function as wet-season carbon sinks and dry-season carbon sources. Strikingly, studies on carbon fluxes have mainly focused on temperate wetlands; but less is known about carbon fluxes in tropical wetlands (e.g., ephemeral wetlands) and their soil profiles. A baseline understanding is required before analysis of land-use or climate change impacts on these aquatic ecosystems can occur. For this reason, it is increasingly important to not only unravel the carbon potential of wetlands to sequester or release carbon but to understand and quantify these processes. A quantitative comprehension of global carbon stores (especially where data are scanty) is necessary for us to predict, and perhaps reduce, some of the negative impacts of anthropogenic induced climate change. This Chapter gives the reader a general introduction to carbon cycling in wetlands, including the major sources and sinks of carbon, the processes that drive carbon fluxes, transformations, and some consequences of changes in those processes. Synopsis The carbon sequestration and storage value of wetlands is recognized. Specifically, wetlands provide a potential sink for atmospheric carbon but can become a source of greenhouse gases. This Chapter provides the reader with an introduction to carbon fluxes and storage in freshwater wetlands with a particular focus on wetlands in subtropical and tropical climates. Examples presented herein highlight the drivers of carbon fluxes by gleaning data from a diversity of authors. In addition, the Chapter discusses the key management and policy questions that must be considered to conserve these crucial ecosystems.