Carbon Sequestration in Created Riverine Wetlands.

The use of natural systems for carbon sequestration is one of the most cost-effective tools to abate the greenhouse effect of carbon emissions. Wetlands are highly productive ecosystems that have the ability to accumulate large amounts of organic matter in the soil, functioning as significant carbon sinks. The conditions that enhance the ability of wetlands to accumulate carbon needs much research, and knowledge in this area would help to determine the potential role of created and restored wetlands as natural carbon sequestering systems. Carbon accumulation was estimated in two flow-through riverine wetlands 15 growing seasons after they were created (2009). One wetland was planted in 1994; the second wetland vegetation colonized naturally. Soil cores were extracted in three different communities of both wetlands (open water, emergent, and edge) at the inflow, middle and outflow sections, and analyzed for total carbon. Soil carbon accumulation rates were 176 ± 7 and 225 ± 4 gC m^-2yr^-1 and soil carbon concentrations were 41 ± 1.8 and 49 ± 0.8 gC kg^-1 respectively for planted and unplanted wetlands. Accumulation rates continue to increase over rates measured after 2 and 10 years in these created wetlands. The carbon pool was greatest in the inflows and decreased towards the outflows, while the wetland communities where emergent vegetation is present are the ones accumulating the most carbon. Wetland carbon accumulation is much higher in the wetlands than in the original upland site (by 55%), and is 42% higher than the accumulation rate measured in a similar flow-through natural wetland in the same region.