Assessment of Carbon Storage and Microbial Community Composition in Unique New England Wetlands

Blue Carbon, coastal ecosystems’ ability to store large quantities of carbon, is increasingly recognized for its important contribution to global carbon budgets. A key parameter determining an ecosystem’s long-term carbon storage function is hydrology. Hydrologic alterations associated with sea level rise and wetland restoration creates uncertainty regarding processes influencing long-term carbon cycling. To inform future wetland restoration planning and accurate carbon budgets, carbon cycling response to altered hydrologic regimes requires quantification. Two study sites were examined: a peat deposit from a historic cedar swamp and a prerestoration cranberry bog. Increased wave action from sea level rise is eroding the peat deposit stored under coastal dunes, while the cranberry bog will be converted into a natural wetland system. Soil cores were collected from these sites as well as natural reference sites. Soil carbon content (SC), CO₂, and CH₄ emissions were measured, and microbial functional diversity was examined in the cedar swamp sites through PCR screening for denitrification genes. The cranberry bog average SC was 0.05 g/cm³ significantly lower than the reference site average SC of 0.09 g/cm³. For the active cedar swamp the average SC was 0.05 g/cm³ while the average SC for the peat deposit was 0.12 g/cm³. CO₂ and CH₄ emissions from the active cedar swamp was significantly higher than the historic cedar swamp peat site. Microbial nitrite reductase and nitrous oxide reductase genes were consistently detected at the active cedar swamp indicating the potential for anaerobic utilization of organic carbon. This study highlights the wide range of carbon storage potential in coastal ecosystems, underscoring the value in examining unique ecosystems when quantifying Blue Carbon.