Effects of patterns of urban green-blue landscape on carbon sequestration using XGBoost-SHAP model

As the main carriers of urban carbon sequestration benefits, green and blue landscape synergistically contribute to carbon sequestration and reduction. However, current research on the overall impact of the spatial patterns of urban green-blue landscape on carbon sequestration benefits is insufficient. Focused on the central urban area of Nanjing, with the years 2000, 2010, and 2020 as the study periods, the correlation among the spatial patterns of urban green-blue landscape and carbon sequestration amounts were explored using eXtreme Gradient Boosting- SHapley Additive exPlanations model. The results showed that the spatial patterns of urban green-blue landscape have an impact on carbon sequestration benefits, with varying degrees of influence from different features. Features such as Contiguity Index, Fractal Dimension Index, the Radius of Gyration, the Area at the patch level, and Edge Density, Splitting Index, and patch Cohesion index at the class level primarily influence carbon sequestration benefits. Increasing the area of green-blue patches and enhancing their shape complexity significantly promote carbon sequestration benefits. Higher levels of aggregation, adjacency, and connectivity of green- blue patches, along with lower fragmentation, lead to better carbon sequestration benefits. These findings provide a reference for optimizing the spatial patterns of urban green-blue landscape from the perspective of carbon sequestration benefits and support urban green-blue space planning and management.