Abstract: Mangrove ecosystems constitute critical blue carbon sinks that play a vital role in climate change mitigation through long-term soil organic carbon (SOC) storage. However, the distribution patterns and stabilizing mechanisms of SOC in mangrove wetlands remain poorly understood. In this study, we conducted a systematic review and synthesis of 152 published studies to investigate the spatial and temporal distribution, environmental drivers, and stability of SOC in China’s mangrove wetlands. The results revealed that mangrove SOC exhibited clear distribution patterns: SOC content (1) decreased progressively with increasing soil depth; (2) declined with increasing latitude; (3) increased with plant age; and (4) was lower in sediments under the introduced species Sonneratia apetala and Spartina alterniflora compared to native vegetation. Plant biomass was the key determinant of the vertical distribution of mangrove SOC, whereas temperature-mediated variations in plant productivity primarily influenced latitudinal gradients. Furthermore, specific abiotic factors emerged as universal drivers regulating SOC storage through plant-soil-microbial interactions: fine soil particles (clay and silt), original SOC content and nutrient availability (especially nitrogen and phosphorus) acted as the primary positive determinants. Due to the combined effects of plant input and strongly anoxic conditions, the 20-60 cm soil layer may represent a key zone for long-term SOC preservation. This synthesis provides novel insights into the ecological processes underpinning SOC sequestration in mangroves and offers a more comprehensive scientific basis for optimizing blue carbon management in coastal wetlands.

Key words: mangrove wetlands, blue carbon, soil organic carbon, carbon sequestration, 5 carbon stability