Multiscale synergistic evolution of China's water-land-energy-food-carbon system: Static-dynamic coupling analysis across sectoral, regional, and national levels

Against the background of increasingly stringent resource and environmental constraints, the coupling among water, land, energy, food, and carbon emissions has continued to intensify, and the multi-element system has become highly complex. Existing studies rarely examine coupling mechanisms from a sectoral perspective and lack a dynamic characterization of system co-evolution, which limits the identification of potential synergies and structural trade-offs within the nexus. To address these gaps, this study proposes a multi-scale analytical framework at sectoral, regional, and national levels for the Water-Land-Energy-Food-Carbon ( W-L-E-F-C ) system. By integrating the coupling coordination degree and dynamic synergy degree, the framework evaluates synergy and trade-off relationships among the five subsystems and the overall W-L-E-F-C system from both static structural and dynamic evolutionary perspectives, thus addressing the shortcomings of existing research in terms of sectoral heterogeneity and system evolution mechanisms. The results showed that: (1) China's W-L-E-F-C system exhibited a moderately high level of coupling coordination. At the sectoral level, industrial sectors showed generally strong internal coupling coordination, whereas coupling between services sectors and some industrial sectors was weak, indicating pronounced sectoral heterogeneity. (2) Dynamic synergy degree analysis identified the land, energy, and carbon subsystems as key contributors to system Non synergy. (3) The static-dynamic coupling analysis revealed that parts of Southwest China and Central China maintained high static coordination, while Northwest China and North China displayed insufficient dynamic synergy, presenting an overall state of Static synergy-Dynamic trade-off. These findings provide a scientific basis for identifying weak links in sectoral and regional coordination in China and for optimizing resource allocation. • Proposes a static-dynamic coupling framework integrating CCD and DWS to assess W-L-E-F-C system synergy. • Reveals strong sectoral heterogeneity, with industrial sectors showing higher coordination than service sectors. • Widespread Static synergy–Dynamic trade-offs, especially in Northwest and North China, reveal latent sustainability risks.