Tourism transition and green productivity in China's ethnic minority regions: non-linear evidence on the digital economy's dual environmental role

Introduction Understanding whether tourism development fosters or hinders green productivity growth remains a pivotal question in sustainable tourism research. Drawing on Butler's Tourism Area Life Cycle (TALC) theory and the destination evolution literature, this study examines the nonlinear relationship between tourism expansion and green total factor productivity (GTFP). Particular attention is given to the moderating role of the digital economy, which may amplify or offset the environmental effects of tourism. Methods We construct a panel dataset of 28 prefecture-level cities in China's Guangxi-Yunnan-Guizhou ethnic minority region over the period 2013–2024. To capture potential nonlinearities, we employ a fixed-effects quadratic regression model, complemented by non-parametric machine learning (XGBoost-SHAP) for robustness and a heteroskedasticity-based instrumental variable approach to address endogeneity. Results Our analysis reveals a clear U-shaped pattern: in the early stages, tourism expansion suppresses GTFP through infrastructure-driven environmental degradation—including construction waste, dust emissions, and land-use change—a mechanism we term “ecological crowding.” Beyond a distinct developmental threshold, however, agglomeration economies and technology diffusion generate net environmental gains via a technology compensation effect. The digital economy exhibits a dual environmental character: its own energy-intensive infrastructure directly reduces GTFP, yet its interaction with tourism positively moderates the tourism-GTFP nexus. Discussion Heterogeneity analysis further shows that the U-shaped relationship is more pronounced in cities with richer tourism endowments, stronger innovation capacity, and higher environmental pressure. These findings suggest spatially differentiated governance strategies for destination management, industrial upgrading, and multi-stakeholder coordination, offering practical pathways to align tourism growth with green transition goals.