Biogeochemistry of Wetland Carbon Preservation and Flux

The recognition that wetlands play an important role in regulating global climate has led to management actions intended to maintain and enhance the globally significant amounts of carbon preserved in wetland soils while minimizing greenhouse gas emissions. Our goal in this chapter is to review the biogeochemical processes that are relevant to wetland climate regulation, which we do by discussing: (1) the concepts of radiative balance and radiative forcing; (2) the mechanisms for wetland carbon preservation; (3) factors influencing greenhouse gas emissions and other carbon losses; and (4) opportunities for wetland management actions to influence carbon preservation and flux. Wetland carbon preservation, which reflects the accumulation of undecomposed organic material, is a function of the redox environment, organic matter characteristics, and physicochemical factors that inhibit decomposition. However, the conditions that favor carbon preservation often result in increased emissions of methane and nitrous oxide such that there is a biogeochemical tradeoff between carbon preservation and greenhouse gas emissions. The losses of carbon via gaseous and dissolved pathways are sensitive to environmental disturbances and raise challenges about fully accounting for the climatic impacts of wetlands. Wetland management and disturbance intentionally or unintentionally affect biogeochemical processes, such that wise environmental management offers opportunities to enhance wetland carbon preservation, prevent the destabilization of accumulated soil carbon, and reduce greenhouse gas emissions, thus maintaining the role of wetlands as regulators of global climate.