The ecosystem services supplied by urban green infrastructure depend on their naturalness, functionality and imperviousness

Urban green infrastructure (UGI) can provide key ecosystem services (ES) for human well-being. For this purpose, it is critical to ascertain which characteristics regulate the provision of ES by UGI. In this study, eight ES (water supply, water regulation, waste regulation, nutrient regulation, soil formation, carbon sequestration, air temperature regulation and air humidity regulation) of thirty UGI sites of Zaragoza (Spain), were evaluated using proxy indicators derived from analyzed soil samples, and in-situ measured air temperature and humidity. A principal component analysis was performed to group different ES, and to study the dispersion of different types of UGI along the distinct ES. Additionally, relationships, between the evaluated ES and predictors; flatness, imperviousness, regularity, naturalness and functioning of the UGI sites were studied through linear and quadratic regressions. Large UGI sites such as riparian zones, meanders and natural forests showed relatively high values of ES in contrast with more artificial sites. Moreover, the study showed that water supply, water regulation, soil formation, carbon sequestration and air temperature regulation were significantly and positively related to ecological naturalness and functioning, while imperviousness was the main predictor explaining the reduction of five ES. Our findings provide evidence for the existence of important interactions between predictor variables and ES in UGI. It also showed that the provision of urban ES can be improved expanding the variety and type of green infrastructure sites, decreasing impervious area, and increasing the naturalness and functioning of UGI.