Carbon storage in typical ecosystems of coastal wetlands in Jiangsu, China: Spatiotemporal patterns and mechanisms

Coastal wetlands have strong carbon storage capacity and are crucial for global carbon cycling research. To gain a detailed understanding of carbon storage and its mechanisms in coastal wetlands, we examined 15 sites in Jiangsu’s coastal wetlands, encompassing 5 typical ecosystems: Phragmites australis, Suaeda salsa, Spartina alterniflora, Mudflat, and Reclamation land. In this study, we used random forest (RF) classification algorithm based on Google Earth Engine (GEE) and Sentinel-2A dataset to accurately identify the spatiotemporal evolution of typical ecosystems in Jiangsu’s coastal wetlands. The results indicate that the Phragmites australis, Suaeda salsa, and Spartina alterniflora ecosystems are widely distributed in the central and southern of Jiangsu’s coastal wetlands, exhibiting strong patch connectivity, whereas patches in the north are relatively fragmented. On this basis, using the life-zone classification and supplemented by field measurements, the study further found that the total carbon storage decreased from 18.43 $\times {10}^{6}tC$ in 2019 to 16.59 $\times {10}^{6}tC$ in 2023. The overall trend exhibited a fluctuating trend of increase–decrease-increase–decrease, with higher carbon storage in the central region and lower levels in the north and south. Further exploration of the mechanisms on the spatial distribution of carbon storage revealed that the total carbon storage in Jiangsu’s coastal wetlands is primarily influenced by human activities such as vegetation harvesting, agricultural activities (planting, plowing), as well as inherent properties such as vegetation type (aboveground biomass, root depth) and soil physicochemical properties. Specifically, soil carbon pool is predominantly influenced by soil depth, total nitrogen, and ${{NH}_4}^{+}-N$, while vegetation carbon pool is primarily influenced by vegetation type and soil dry matter content. These methods and findings provide new insights for enhancing carbon management in coastal wetlands and formulating policies to maintain the balance of global carbon cycling processes.