Carbon sequestrationWetlands capture more carbon than earlier thought

Published 27 January 2012

New study shows that wetlands in temperate regions are more valuable as carbon sinks than current policies imply; the study found that the stagnant wetland had an average carbon storage rate per year that is almost twice as high as the carbon storage rate of the flow-through wetland

Beautiful, and a valuable carbon sink as well // Source: merecat.org

A new study comparing the carbon-holding power of freshwater wetlands has produced measurements suggesting that wetlands in temperate regions are more valuable as carbon sinks than current policies imply, according to researchers.

The study compared several wetlands at two Ohio wetland sites: one composed of mostly stagnant water and one characterized by water regularly flowing through it. The study showed that the stagnant wetland had an average carbon storage rate per year that is almost twice as high as the carbon storage rate of the flow-through wetland.

An Ohio State University release reports that in addition, the scientists came up with measures of carbon storage in the stagnant wetland that exceed carbon measurements recorded in recent years in various types of wetlands, suggesting to the researchers that temperate freshwater wetlands may have a significant role in worldwide strategies to offset greenhouse gas emissions.

All types of wetlands deserve more credit than they receive as carbon sequestering systems in global carbon budgets, the researchers say. They also say, however, that boreal peatlands — wetlands containing deep layers of organic matter in subarctic regions — should not be the only wetlands favored in policy considerations.

“These numbers are a lot higher than those often used to determine policy about wetlands. All of our numbers are, in general, considerably higher than average rates of carbon sequestration for boreal peatlands, but the boreal peatland numbers rule the roost in climate change,” said William Mitsch, senior author of the study and an environment and natural resources professor at Ohio State University. “Wetlands make up 6 to 8 percent of the landscape, but they hold much more than 6 to 8 percent of the world’s carbon. They are the forgotten carbon sink.”

Mitsch completed the study with Blanca Bernal, a graduate student in Ohio State’s School of Environment and Natural Resources. The research appears online and is scheduled for future print publication in the journal Global Change Biology.

Mitsch and Bernal collected soil core samples from a forested wetland in Gahanna, in central Ohio, and from Old Woman Creek, a freshwater wetland near Lake Erie in northern Ohio. The Gahanna wetland is called a depressional wetland, or a swamp that remains saturated year-round. Old Woman Creek is part of a state park connecting an agricultural watershed with the lake that experiences pulses of water from both entry points.

They analyzed both the carbon content of the soil as well as the depth