Unraveling the potential of willow afforestation for long-term soil organic carbon sequestration under future climate and acclimation pathways

Floodplains play a pivotal role in global carbon cycling due to their substantial contribution to soil organic carbon storage . However, climate change and anthropogenic pressures threaten this essential carbon sequestration capacity. In this study, we investigated the influence of willow afforestation on long-term soil organic carbon dynamics at an authentic floodplain experimental site in South Korea under various climate change scenarios. Using an integrated ecohydrological and biogeochemical modeling approach – validated with observed data from the experimental plots – we assessed the impacts of willow acclimation , as well as elevated temperature and precipitation, on soil organic carbon dynamics . Our results indicate that under non-climate change scenarios, willow afforestation could sequester approximately 800 gC m −2 of soil organic carbon to a depth of 1 m. Without considering climate change scenarios, this sequestration stabilizes after roughly 30 years, with the majority of carbon stored in the topsoil . Under warming scenarios, willow leaf area acclimation mitigated soil organic carbon losses by increasing carbon inputs and providing shade that lowered soil temperatures . Furthermore, we found that soil organic carbon sequestration potential remained consistent with non-climate change scenarios, even with temperature increases of up to 4.7 °C above the 2004–2023 baseline period. These findings underscore the importance of afforestation as a climate mitigation strategy and highlight the need to account for adaptive plant traits – such as leaf area index – when projecting soil organic carbon dynamics under non-stationary climate conditions. • Willow afforestation boosted soil carbon by up to 800 gC/m² in 30 years. • Most carbon was stored in topsoil layers. • Willow traits like higher leaf area helped retain soil carbon. • The trait reduced soil heat and moisture, helping minimize soil carbon loss. • Even with 4.7 °C warming, willow planting can still store soil carbon effectively.