Review on Methodologies of Assessing Carbon Sequestration Amount of Coastal Wetlands

In coastal wetlands, the high primary productivity and slow degradation rate of organic matter result in a substantial carbon sink function. Quantitative research on net carbon sequestration capacity provides important technical support for formulating policies for increasing sinks, reducing emissions and achieving carbon neutrality. Many methods of observation, calculation and prediction of wetland net carbon sinks are used worldwide, thus resulting in low comparability among research methods. In this study, the existing research is systematically reviewed from the perspectives of carbon flux observation, ecosystem carbon budget measurement, soil carbon storage variation and carbon cycle simulation. According to an analysis of existing research gaps, future research directions for determining the net carbon sequestration capacity of coastal salt marshes are proposed. On the basis of the biogeochemical cycle mechanisms of carbon in wetland ecosystems, combined with satellite remote sensing technology, a carbon source/sink process model should be constructed, and carbon flux observations and carbon budget measurement data should be used for model parameter calibration and verification suitable for different temporal and spatial scales. Development of this model should provide an effective way to quantitatively evaluate the net carbon sink capacity of coastal salt marshes.