Current status and prospects of terrestrial ecosystem carbon sink in the Dongting Lake Basin, China

The enhancement of carbon sequestration in terrestrial ecosystems is regarded as one of the most effective measures for mitigating global carbon emissions and climate change. Compared to that at the local scale, watershed terrestrial ecosystems at the watershed scale typically exhibit the characteristics of more complex hydrological processes, intense anthropogenic disturbance, independence and intact. The Dongting Lake basin, as one of the most representative watershed in China, exhibits low carbon sink stability but significant carbon sequestration potential. We reviewed current research on the spatiotemporal patterns, carbon storage, sequestration potential, and carbon storage stability along the Dongting Lake basin, and proposed future research prospects. Currently, the mea-surement and monitoring of terrestrial ecosystem carbon sinks primarily rely on conventional models, with the limitations of inconsistent validation standards, relatively low precision, and neglecting anthropogenic disturbances. Data sources are predominantly confined to land use and remote sensing imagery, which often suffer from insufficient spatial resolution and untimely updates, leading to considerable uncertainties in carbon sink estimation. Overall, forest ecosystems are the primary contributors to carbon sequestration across the basin, while farmland and wetland ecosystems exhibit substantial carbon sequestration potential. Further attention should also be directed toward the complex hydrological conditions and regional characteristics. There is a critical need to develop carbon cycle models that couple watershed hydrological processes with biogeochemical cycles. Additionally, we require a systematic assessment and quantification of the mechanisms underlying the influences of human activities on ecosystem carbon sequestration. Such efforts are essential for more accurately evaluating the carbon sequestration function, potential, and multi-scale drivers of the terrestrial ecosystem in the Dongting Lake basin, thereby offering scientific support for achieving China's "Dual Carbon" goals.