Hao Liu , Yi-Ning Zhang, Yu-Jia Cai, Zi-Yan Liu, Liang Li, Ya-Qin Wang, Xiao Shu, Royston Goodacre, Zheng Chen

Flooded soils play a critical role in global carbon cycling, serving as significant reservoirs of soil organic carbon and sources of carbon emissions. Leaf litter, particularly from local vegetation, is a major contributor to soil organic carbon formation in these ecosystems, with its decomposition driving the production of carbon dioxide and methane. While numerous studies have investigated the factors influencing leaf litter decomposition and the associated greenhouse gas emissions, the impact of millimeter-scale variations in leaf litter placement within the soil-water interface (SWI) remains underexplored. This study hypothesizes that such minor changes in burial depth can significantly alter the emission patterns of CO2 and CH4. To test this, a microcosm experiment was conducted, monitoring gas fluxes and profiles of physicochemical properties in treatments with leaf litter closely placed at two depths within the SWI. Results revealed that a sub-centimeter difference in leaf litter
placement could lead to a substantial shift in CO2 and CH4 emissions, with important implications for modeling wetland carbon dynamics and predicting their climate impact. These findings underscore the sensitivity of greenhouse gas emissions to small-scale environmental variations, highlighting the need for more precise models in estimating wetland contributions to global carbon fluxes.