Linking Hydrological Connectivity to Wetland Vegetation Carbon Storage: Insights From the Largest Freshwater Lake in China

Abstract Wetlands, though covering only 2% of the Earth's surface, store over 20% of global organic carbon, making them vital reservoirs in the global carbon cycle. Despite this significance, the role of hydrological connectivity in wetland vegetation carbon storage remains poorly understood. This study addresses this gap by quantitatively assessing the impact of hydrological connectivity on wetland vegetation carbon sequestration in Poyang Lake, China's largest freshwater lake, based on multi‐source remote sensing data fusion. It reveals that total carbon storage in Poyang Lake increased from 2000 to 2020 at a rate of 0.09 Tg/year, with a more pronounced rise after the Three Gorges Dam began operation. Hydrological connectivity explained 73% variation in vegetation carbon storage, with connectivity functions (CFs, defined as the probability of water connection between surface units as a function of distance and direction) during the receding period having the most significant impact, and near‐distance CFs contributing more to carbon sequestration than middle‐ and far‐distance CFs. Additionally, enhancing hydrological connectivity does not necessarily result in higher carbon sequestration, as low‐connected seasonal isolated lakes (SILs) sequestered up to 2,051.18 g C/m 2 /year, exceeding the 1,593.75 g C/m 2 /year in high‐connected SILs. These findings challenge conventional understanding and offer actionable insights for optimizing wetland management strategies aimed at enhancing carbon sequestration, particularly through targeted hydrological regulation.