Analysis of Carbon Density Distribution Characteristics in Urban Wetland Ecosystems: A Case Study of Shanghai Fish and Dishui Lake

This paper examines two major artificial wetlands in Shanghai—Shanghai Fish and Dishui Lake—as case studies to explore the biomass, carbon content, carbon density, and carbon sequestration functions of wetland plants in urban ecosystems. Through field sampling and elemental analysis of 20 common wetland plant species, this study investigated the differences in aboveground and underground biomass and carbon storage capacity across different plant types. The results indicated that emergent plants have the highest carbon storage capacities, with species such as Cyperus involucratus, Arundo donax, Phragmites australis, and Nelumbo sp. exhibiting higher carbon densities, while floating plants demonstrated relatively weaker carbon storage capacity. The carbon content varied significantly between different parts and species of plants, while soil carbon density was much higher than that of the plant portions, highlighting the crucial role of soil in wetland carbon sequestration. Additionally, an inversion model for wetland plant carbon density was established, and remote sensing data were used to assess the vegetation distribution characteristics and carbon density variations in the two artificial wetlands. This distribution pattern reflects the influence of wetland vegetation and water level (which affect water availability and nutrient distribution) on carbon density. The results showed a significant increase in carbon density from 2018 to 2023, particularly in lakeshore areas, suggesting that wetland ecological restoration and management measures have achieved positive outcomes, including a measurable increase in carbon density and enhanced vegetation coverage. The findings are significant for understanding and enhancing the carbon sequestration potential of artificial wetlands in urban ecosystems.