Soil and Biomass Carbon Accumulation Performance in Abandoned Paddy Wetlands(APWs)

Abandoned paddy wetlands (APWs), which are converted from rice paddy wetlands (RPWs) due to natural or artificial cessation of farming, function as crucial carbon sinks. Although APWs serve as vital cultural and ecological resources providing essential ecosystem services, these excellent ecosystems are often inadequately managed, leading to rapid degradation and transformation into carbon emission sources. This study was conducted to quantify the carbon accumulation capacity of reference APWs distributed across the central region of the Republic of Korea. In accordance with the Intergovernmental Panel on Climate Change (IPCC) Good Practice Guidance for Land Use, Land-Use Change and Forestry (GPG-LULUCF), soil samples were collected from each APW at a depth of at least 30 cm. Subsequently, soil organic matter (OM) content, soil organic carbon (SOC; g/kg), and soil organic carbon storage per unit area (SOCS; kg/m²) were calculated. Additionally, carbon absorption based on land cover was measured within the hydro-ecological impact zone (a 300-m buffer zone) surrounding the APWs, and carbon accumulation via the biomass of dominant vegetation was evaluated. For APWs dominated by woody plants, carbon storage was determined by tree height, diameter at breast height (DBH), and population size, whereas population coverage size determined carbon storage in wetlands dominated by herbaceous plants or mixed woody-herbaceous communities. The results revealed that the average OM of the APWs was 33.7 g/kg, and the SOC per unit weight was 19.54 g/kg. The accumulated SOCS per unit area was mathematically corrected from 67.97〖" kg/m" 〗^2 to 61.20±22.28〖" kg/m" 〗^2, which is approximately 8.5 to 40 times higher than the average SOCS of forest soils in South Korea (7.19 kg/m² in Jeju Island) and urban parks (1.56 to 2.84 kg/m²). Furthermore, the average carbon absorption within the hydro-ecological impact zone increased rapidly over time, rising from 20.45 tCO₂/ha in 2000 to 35.30 tCO₂/ha in 2013, and reaching 38.14 tCO₂/ha in 2021.