Carbon Sequestration in Salt Marshes

The importance of the world's rainforests, and to some extent the mangroves, as storage sinks for atmospheric are carbon well-known. But salt marshes, too, are extraordinarily efficient mechanism for photosynthesis and the production of biomass that work together to sequester carbon at a high rate. So disappearing wetlands along the coast present much more peril than loss against storm surge, which itself plays significant part in their role in an ecosystem.

Now, Deepak Mishra, associate professor in the department of geography, has developed tools and techniques to map carbon storage in coastal marshes using satellite data:

[Mishra] is principal investigator on the new prototype demonstration study that will use NASA's MODIS—Moderate Resolution Imaging Spectroradiometer—Earth Observatory satellite to gather data to model the marshes.

"There is high demand to understand wetlands, and it's not just about land lost, land gained, marsh lost or restored-people want to know more about these marshes," Mishra said. "How they are performing in terms of their productivity, their resiliency, do they produce enough underground biomass to be stable? We hope to be able to answer these questions.

"The idea is to see what kind of carbon loss to the atmosphere is happening by means of satellite-derived proxies as we lose wetlands, not only in terms of area but also productivity."

Restoration projects along coastal areas are expensive, and their success is judged primarily by the amount of vegetation gained. This new modeling capability will allow for more complete assessments of the marshes' overall productivity: carbon capture, light-use efficiency for photosynthesis and biomass production. It also will differentiate which species of marsh grass provides better productivity.

"Right now, monitoring wetlands via satellite is problematic because of the way water and soil moisture interferes with the signal," Mishra said. "It can be difficult to effectively separate the water contribution from the vegetative contribution."

Data from the two monitoring stations along the Gulf Coast will be used to establish models for other areas around the U.S. as well. As Mishra explains, being able to quantify the carbon capture in these areas will become increasingly important as we begin to put a dollar value on carbon as a part of our ability to responsibly limit emissions - and more precisely, value the overall productivity of an ecosystem.

And while we didn't say this in the release, this new work is an important step forward in the fight against rising levels of atmospheric carbon, and thus, climate change. 

Image: UGA researchers deploy a flux tower in a marsh patch close to Wormsloe Historic Site near Savannah, Georgia, during the summer of 2013.​ (Credit: Mishra Lab/UGA)