Study: Human activity breaks soil carbon density link in coastal zones, adding uncertainty to blue carbon accounting

A new study published in Environmental Science and Ecotechnology finds that human activities like farming are breaking the predictable relationship between soil organic carbon and bulk density in coastal wetlands. This decoupling introduces significant uncertainty into blue carbon accounting, which relies on standard formulas developed for dry land. The research team collected 123 soil profiles in China's Jiangsu coastal zone and found that traditional pedotransfer functions performed poorly in human modified areas, with a mean prediction uncertainty of 0.22 g cm³ for bulk density. The study recommends a land cover based sampling strategy. In vegetated wetlands, high resolution vertical sampling is needed to capture the carbon density gradient. In tidal flats, less intensive sampling works. For croplands and other human modified lands, the team advises directly measuring bulk density instead of relying on standard formulas. This approach could reduce uncertainty in blue carbon projects and improve carbon budgets for coastal ecosystems.