Annual Carbon Mineralization and Belowground Production of Spartina Alterniflora in a New England Salt Marsh

Publisher Website
Google Scholar
Abstract
The annual rates and depth distribution of organic carbon mineralization to CO2 were determined in sediments supporting stands of short Spartina alterniflora. Carbon dioxide production was estimated by two independent techniques. We constructed a CO2 budget based on measurements of CO2 emission from the sediment to the atmosphere, export of dissolved inorganic carbon in porewater exchange, and changes in the porewater pool of dissolved inorganic carbon throughout the year. We also measured CO2 production in salt marsh sediments by monitoring changes in total inorganic carbon in cores. The estimates obtained by the two methods were similar, giving a total annual CO2 production of between 67 and 70 mol°m—2°yr—1. We also measured the losses of organic matter as methane (O.1—0.3 mol°m—2°yr—1) and dissolved organic carbon (0—3 mol°m—2°yr—1) and burial (7.4 mol°m—2°yr—1) in order to construct a carbon budget for the sediments. These data, when combined with the estimates of carbon mineralization, gave an estimate for the organic carbon loading to the sediments of 68—78 mol°m—2°yr—1. About 95% of the annual carbon input either decomposes to CO2 in situ or is buried, and —2°yr—1.