[Estimation of Carbon Storage and Analysis of Driving Factors in the Yiluo River Basin Based on the RHESSys Model]

The estimation of carbon storage and quantitative analysis of the impact of climate and land use changes on carbon storage are of great significance for explaining the hydrological and ecological response mechanisms of a watershed and achieving carbon neutrality. This study focused on the Yiluo River, an important first-order tributary of the Yellow River, using the RHESSys model to estimate soil, plant, litter, and total carbon storage in the watershed. A multiple regression analysis model was constructed to quantify the contributions of climate change and land use change to carbon storage. The results showed that： The Nash efficiency coefficients（NSE） of the RHESSys model were above 0.65 during both the calibration and validation periods, and the R² values were greater than 0.7, indicating that the model performed well in simulating the Yiluo River Basin. The spatial distribution of carbon density in the Yiluo River Basin decreased from west to east and from upstream to downstream. Over the period from 2000 to 2023, both the soil carbon and total carbon in the Yiluo River Basin showed a significant upward trend, with soil carbon density increasing by 4.48 kg·m^-2 and total carbon density increasing by 4.25 kg·m^-2. Moreover, plant carbon density slightly decreased, while litter carbon density slightly increased, but the interannual variations were not significant. The contrabution rates of impacts of meteorological factors and land use change on total carbon storage were 51% and 49%, respectively. Litter carbon was most sensitive to meteorological factors, especially changes in minimum temperature, whereas land use change had a more significant effect on soil and plant carbon, with changes in forest area having the most pronounced impact.