[Spatiotemporal Variation Characteristics and Driving Factors of Carbon Sinks in Resource-Depleted Transition Cities： A Case Study of Xuzhou].

Abstract

Ecological restoration and green transformation of resource-exhausted cities are vital pathways for carbon sequestration and sink enhancement. The quantitative evaluation of carbon sink capacity and its driving factors is essential for deepening the understanding of regional carbon cycling and its driving mechanisms， optimizing ecological restoration strategies， and advancing China's "dual-carbon" goals. In this study， we selected Xuzhou， a city transitioning from resource dependence， as our case study and employed an improved CASA model， soil respiration regression equations， slope trend analysis， Hurst index， optimal parameter Geodetector （OPGD）， and partial correlation analysis to reveal the spatiotemporal dynamics， driving factors， and future trajectories of net ecosystem productivity （NEP） during Xuzhou's transition away from resource dependence. The results show that： ① From 2000 to 2022， NEP in Xuzhou exhibited a fluctuating upward trend and displayed a spatial pattern of "low in the center， high in the periphery，" transitioning from a carbon source to a carbon sink. ② During 2011-2022， NEP increased significantly， and the area exhibiting a significant upward trend expanded by 28.21% （P < 0.05）； the carbon-sink capacity was projected to continue strengthening. ③ The explanatory power of individual drivers of NEP spatial heterogeneity differed markedly， while the intensity of multi-factor interactions rose significantly. Vegetation cover fraction （q=0.49） and built-up land proportion （q=0.47） exhibited the strongest explanatory power for the spatial heterogeneity of NEP， and the explanatory power of ecological restoration factors has been steadily increasing. ④ Future efforts should focus on establishing a synergistic mechanism that integrates ecological-restoration governance with carbon sink enhancement， strengthening the interplay between natural and anthropogenic factors， ensuring ecological sustainability， and averting the risk of carbon sink decline caused by uncontrolled urban expansion.