Spatiotemporal Variation and Factors Influencing NEP in Resource-Based Cities in Arid Regions: A Case Study of Ordos City

In resource-based cities of arid regions, ecosystem carbon sequestration capacity is shaped by the interactive effects of climate change, resource exploitation, and ecological restoration. Quantitatively evaluating the dynamics of carbon sink capacity and its driving mechanisms is essential for unraveling carbon cycle processes in coupled human–environment systems, enhancing carbon sequestration efficiency, and advancing regional carbon neutrality and peaking targets. Taking Ordos City, a representative resource-based city in an arid region, as a case study, this study integrates an improved CASA model, a soil respiration model, trend analyses, stability analyses, partial correlation analysis, and the Optimal Parameters-based Geographical Detector (OPGD) to investigate the spatiotemporal dynamics, future trajectories, and influencing factors of net ecosystem productivity (NEP) in resource-based cities located in arid areas. The main findings are as follows: (1) From 2001 to 2023, NEP in Ordos City showed a fluctuating upward trend, with a spatial pattern characterized by “higher values in the east and lower values in the west”. Notably, some areas have successfully transitioned from carbon sources to carbon sinks. (2) Over the past 23 years, NEP has demonstrated a pronounced increasing trend with strong spatial heterogeneity and is projected to maintain continuous growth in the future. Areas characterized by sustained growth account for as much as 63.22% of the total region, indicating that the regional carbon sink capacity is strengthening and will continue to rise. (3) The explanatory power of factors influencing the spatial heterogeneity of NEP varies significantly, and the interactive effects among multiple factors have been greatly enhanced. Population density (q = 0.72) and evapotranspiration (q = 0.63) exhibit the strongest explanatory power for the spatial differentiation of NEP, whereas the explanatory power of the distance to mining areas has been continuously increasing. (4) Future research should prioritize the interactive coupling effects between natural factors and human activities, establish a compensation mechanism for carbon sink losses induced by mining development, strengthen the synergistic mechanisms linking ecological restoration and carbon sink enhancement, and focus on preventing and mitigating the risk of ecological carbon sink degradation triggered by unregulated urban spatial expansion.