Unveiling the role of eco-certifications as spatial drivers of green tourism in Italian provinces

The measurement of sustainability in tourism remains a critical challenge for socio-economic planning, as many existing indicators describe environmental conditions or pressures rather than the concrete actions undertaken by destinations and tourism actors. This study develops a spatially explicit composite indicator of certification-based sustainability effort for Italian provinces. The indicator is built from eco-certifications and environmental management schemes adopted by public institutions, accommodation providers, tourism-related services, and environmental management actors. Rather than providing an absolute ranking of destination sustainability, the indicator captures the intensity and local coherence of certified environmental effort in tourism. Methodologically, the indicator is constructed through Geographically Weighted Principal Component Analysis (GWPCA), which allows the relevance of each certification to vary across territories according to local covariance structures. The resulting indicator is then analyzed through a Spatial Durbin Error Model (SDEM), to examine how certification-based sustainability effort is associated with local tourism, socio-economic, and environmental characteristics, as well as with neighboring territorial contexts. The empirical analysis highlights the spatially differentiated and interdependent nature of green tourism effort, showing that sustainability-oriented certification patterns are shaped by both local conditions and broader territorial linkages. The study contributes to the literature by combining an effort-oriented interpretation of tourism sustainability with a spatially sensitive framework for indicator construction and spatial modeling.