Spatiotemporal patterns and nonlinear correlates of coordination between the digital economy and tourism ecological security in Chinese cities

Tourism ecological security (TES) is essential for sustaining destination resilience, ecological quality, and long-term tourism development. The digital economy (DE) plays a crucial role in improving TES by enabling smart monitoring, efficient resource allocation, and precision governance. Conversely, enhanced TES creates green demand and application scenarios for digital technologies, thereby facilitating DE upgrading. However, existing studies have mainly examined the one-way effects of DE on tourism or ecological performance, with limited attention to the bidirectional coupling coordination between DE and TES and its nonlinear correlates. Using panel data for 206 Chinese cities from 2006 to 2023, this study measures DE and TES using CRITIC and entropy-weighted TOPSIS, respectively; calculates the DE–TES coupling coordination degree (CCD); and combines kernel density estimation, Jenks natural breaks, and XGBoost–SHAP to examine its spatiotemporal evolution and associations with influencing factors. The results show that DE–TES CCD increased continuously, shifting from incoordination toward coordination, while displaying high values in eastern coastal urban agglomerations and lower values in central and western regions. Its influencing factors exhibit nonlinear associations, threshold patterns, and interactions in the model. Residents' educational attainment, tourism resource attractiveness, industrial structure upgrading, and population density are the key influencing factors, with educational attainment showing the strongest explanatory power. The interaction between tourism resource attractiveness and industrial structure upgrading is particularly prominent, indicating that higher tourism resource attractiveness is more positively associated with DE–TES CCD at higher levels of industrial structure upgrading. This study advances the theoretical understanding of DE–TES synergistic evolution and provides evidence for differentiated digital transformation and TES governance in tourism destinations.