Carbon storage potential in a recently created brackish marsh in eastern North Carolina, USA.

Highlights • We evaluated C dynamics in a created marsh having salinity of 10–30 psu. • The marsh was a net C sink and fixed 1.85 g C m−2 day−1 by plants. • 41–46% of the fixed C remained in plants while 8.6–13.2% was transformed to soil. • CO 2 credit of $30.76–$47.90 USD per hectare was realized from this project. Abstract Carbon (C) sequestration through accumulated plant biomass and storage in soils can potentially make wetland ecosystems net C sinks. Here, we collected GHG flux, plant biomass, and litter decomposition data from three distinct vegetation zones (Spartina alterniflora , Juncus roemerianus and Spartina patens) on a 7-year-old created brackish marsh in North Carolina, USA, and integrate these data into an overall C mass balance budget. The marsh fixed an average of 1.85 g C m−2 day−1 through plant photosynthesis. About 41–46% of the fixed C remained in plants, while 18.4% of the C was decomposed and released back to the atmosphere as CO 2 and CH 4 , and 8.6–13.2% of the decomposed C was stored as soil C. In all, this created marsh sequestered 28.7–44.7 Mg CO 2 year−1 across the 14 ha marsh. Because the brackish marsh emitted only small amounts of CH 4 and N 2 O, the CO 2 equivalent emission of the marsh was −0.87 to −0.56 g CO 2-eq m−2 day−1, indicating the marsh has a net effect in reducing GHGs to the atmosphere and contributes to cooling. However, resultant CO 2 credit (through the increment of soil C) would be worth only $30.76–$47.90 USD per hectare annually, or $431–$671 per year for the project, which, coupled with other enhanced ecosystem services, could provide landowners with some additional economic incentive for future creation projects. Nevertheless, C mass balance determinations and radiative cooling metrics showed promise in demonstrating the potential of a young created brackish marsh to act as a net carbon sink. [ABSTRACT FROM AUTHOR]