Driving mechanisms of vegetation carbon sink distribution based on explainable machine learning and evaluation of carbon sequestration in open-pit mines.

Vegetation carbon sequestration plays a crucial role in mitigating global warming and maintaining regional carbon balance. The Yellow River Basin (YRB) is a key region for energy development and ecological conservation in China, yet the driving mechanisms underlying the spatial distribution of vegetation carbon sequestration and the carbon sequestration capacity of open-pit mines have not been systematically evaluated. Based on multi-source datasets, this study first employs the Sen's slope estimator combined with the Mann-Kendall trend test model to identify the temporal trends of vegetation carbon sequestration. It then applies a Bayesian-optimized Bayesian-optimized Extreme Gradient Boosting model integrated with Shapley Additive Explanations model to uncover the driving mechanisms of climate, soil, and human activities on its spatial distribution. Finally, a buffer zone comparison method is used to quantify the carbon sequestration potential of open-pit mines. The main conclusions are as follows: (1) Over the 24-year period, Net Ecosystem Productivity (NEP) in the YRB has shown a continuous increase, reaching 159.69 gC·m-2 in 2024, which is five times the level in 2001. The most significant growth occurred in the middle and upper reaches, while the endorheic region exhibited limited improvement, with some areas even functioning as carbon sources. (2) Among the driving factors of NEP distribution in the YRB, precipitation, solar radiation, and soil organic carbon are the dominant contributors, accounting for more than 58 % in total. (3) The NEP of different types of open-pit mines varies substantially. Active mines function overall as carbon sources (-17.93 Gg), whereas stable and revegetated mines act as carbon sinks. The total carbon sequestration potential of all open-pit mines is 93.57 Gg, representing approximately 89 % of the current carbon sequestration level. This study provides a quantitative foundation for enhancing carbon sequestration, evaluating ecological restoration, and supporting the implementation of the "dual-carbon" strategy in the YRB.