Spatial co-occurrence of soil organic carbon density and plant organic carbon density in wetlands of the Yellow River, Henan Province, China

Context The Yellow River in Henan has undergone major hydrological changes due to reservoir water-sediment regulation, leading to the development of extensive seasonal wetlands. Aims This study examined organic carbon distribution in the Henan Yellow River wetland by measuring soil and plant organic carbon across different vegetation zones. Methods Twelve sampling sites were selected; three 1 m × 1 m quadrats were set for each vegetation type. Plant tissues (0–50 cm soil layer) and soil samples were collected to analyze total organic carbon. Key results Soil organic carbon (SOC) was concentrated in topsoil (1.57–7.10 g kg−1), with density 0.61–4.14 kg m−2. Plant organic carbon density dominated aboveground biomass: grass highest, Tamarix lowest. Total wetland carbon storage was ~8.93 × 106 t C. Conclusions SOC concentrations were substantially higher in the 0–20 cm layer than in the 20–50 cm layer. Vegetation type strongly influenced the spatial variation in SOC, whereas total plant organic carbon (POC) was mainly allocated to aboveground biomass. The wetland exhibited a distinctive carbon pattern characterised by low soil organic carbon density but relatively high plant organic carbon accumulation. Implications We measured the distribution characteristics of organic carbon in the Henan Yellow River Wetland and identified a pattern of low soil carbon density coupled with relatively high plant carbon density, providing a basis for further research on carbon cycling in regulated riparian wetlands.