Modelling long-term soil organic carbon dynamics of the typical salt marsh wetlands with the DNDC model: a case study from Yancheng wetland, China

Soil organic carbon (SOC) is an important component of the blue carbon ecosystems. Recently, the protection and restoration of blue carbon ecosystems have attracted widespread attention, with a focus on the mangroves in the south and the salt marsh wetlands in the north of China. However, there is a lack of studies committed to studying the dynamics and long-term temporal variations of SOC in wetland ecosystems. In this study, we used field sampling data combined with Denitrification-Decomposition (DNDC) process-oriented model to explore the long-term temporal changes of SOC contents at regional scales. The results showed that the DNDC model was well applicable to the study of SOC temporal changes in salt marsh wetlands of Jiangsu. The SOC content varied from 0.0066 kg−1 to 0.0169 kg−1 in Spartina alterniflora beach from 2004 to 2040. For Phragmites and Suaeda glauca beach, it changed from 0.0053 kg−1 to 0.0069 kg−1, and from 0.0052 kg−1 to 0.0063 kg−1, respectively. Whereas, for bare flat, SOC content decreased from 0.0022 kg−1 to 0.0012 kg−1. Sensitivity analysis identified temperature, clay content, initial SOC content, grazing stock and manure amount were the key factors affecting SOC concentration at 0–10 cm soil layer. This study offers a new understanding of using process-oriented model to present long-term SOC changes across different wetland beaches and assists the government in formulating policies to strengthen blue carbon stabilization ability in the context of climate change and intensive anthropogenic activity.