Abstract: Understanding the distribution patterns of carbon density and influencing factors of wetlands is conducive to revealing the influence mechanism of wetland eco-hydrological processes on carbon sequestration. Based on variations in groundwater levels and the characteristics of plant community distribution, three habitats in the riparian wetland along the Yellow River in Yan’erwan Wetland Park of Lanzhou City were established sequentially from the riverside to the higher-elevation shoal: waterside zone, transition zone, and edge zone. The spatial distribution of carbon density of wetlands and its influencing factors were examined by community investigation. The results showed that from the waterside zone to the edge zone, groundwater level declined, soil water content decreased, and biomass, coverage and density of plant community decreased from 3409.51 g·m^-2, 97.84%, and 221.84 bunch·m^-2 to 1396.85 g·m^-2, 96.34%, and 149.00 bunch·m^-2, respectively. Ecosystem carbon density, vegetation carbon density, stem carbon density, and leaf carbon density decreased from 96.57, 14.26, 4.11, and 3.31 t·hm^-2 to 61.98, 5.55, 1.32, and 0.99 t·hm^-2, respectively. The proportions of stem and leaf carbon density declined from 28.79% and 23.24% to 23.80% and 17.77%, respectively, while the proportions of root carbon density and soil carbon density increased from 47.97% and 85.23% to 58.43% and 91.05%, respectively. There were significant differences in soil organic carbon content and carbon density across different habitats. The carbon density of the whole ecosystem and that of the vegetation and soil component were highly significantly positively correlated with community height, biomass, soil organic carbon content, and soil moisture (P<0.01). In summary, water level fluctuations among habitats significantly influence vegetation and soil carbon density in river wetlands.

Key words: carbon density, allocation pattern, groundwater table depth, plant community, Lanzhou section of the Yellow River