A review of urban green spaces multifunctionality assessment: A way forward for a standardized assessment and comparability

The concept of multifunctionality has been increasingly integrated in the assessment of urban ecosystem services (ES). Although an indicator-based approach has been widely used for urban green spaces multifunctionality assessment, a variation in assessment methods still exists. The comparability of the assessment results across cities thus becomes difficult. This article reviewed 94 studies which included more than a single urban ES. The findings demonstrate a variation in the coverage of multifunctionality, indicator types, assessment methods, scoring systems, and the consideration of two important concepts: trade-offs and ecosystem service demands. A standardized assessment framework for urban ecosystems is therefore proposed. It contains five features: enabling users to select ecosystem structures, enabling users to assess the same ecosystem services which are mandatory, enabling users to select indicator types to suit their data availability, the use of reference values to have informative results, and integration of the analysis of trade-offs or ecosystem service demands. With this standardized approach, the comparability of urban green spaces multifunctionality is possible.