Identifying cause-effect links between nature-based solutions, ecosystem services and urban challenges to enhance the assessment of nature-based solutions

Poster Abstract: The use of Nature-based Solutions (NBS) to support sustainable urban development is increasing. However, the cause-effect relationships between NBS and their supply of ecosystem services (ES) in order to address urban challenges (UC) are still not fully understood, hampering the optimal plan and design of NBS. This research aims to identify cause-effect links between different NBS, ES, and UC, thus providing a robust technical and scientific ground for the sustainability assessment of urban NBS. First, an identification of UC was developed through a critical review of the scientific and grey literature. Second, links between ES and UC were established. Third, an analysis of NBS was conducted to define an operational urban NBS typology. Finally, main biophysical factors of specific urban NBS and their related ecological processes influencing different ES supply were identified. As a result, twelve groups of UC (e.g. climate change; public health; water security and management) and associated ES (e.g. regulation of temperature and humidity, filtration, sequestration and storage of pollutants by plants) are identified. For several UC (e.g. social equity, cultural identity), the type of implementation needs to be known before making an evaluation of NBS possible. The proposed multi-hierarchical urban NBS typology classifies NBS in i) new biophysical features, ii) restoration & reclamation interventions, iii) management techniques; iv) spatial levels; and v) media. The typology facilitates the association of specific NBS types with biophysical factors affecting the ecological processes responsible for different ES supply. The identification of UC-ES-NBS links and their related socio-environmental factors and processes increases the pool of knowledge on the appropriateness of different NBS to address specific UC. However, this study also points out that further research is needed to support quantitative assessments of urban NBS. Keywords: Urban Challenges; Ecosystem Services; Nature-based Solutions; Cause-effect Links; Urban Plannin