Design principles for mainstreaming of nature-based solutions in cities: A proposal for future pathways

Examining how city-level governments respond to the coupled climate and biodiversity crises can build an understanding of how to enable urban sustainability transitions. In this paper, we refer specifically to mainstreaming, as an approach for embedding novel sustainability solutions into governance and practice. The focus is to better understand the governance of nature-based solutions in cities, from the perspective of the processes of mainstreaming. Therefore, we define a novel and comprehensive mainstreaming framework that is built from three previous frameworks that describe social-institutional elements of mainstreaming: actors’ roles, institutional spaces, and governance mechanisms. These three elements provide the foundations for conceptually deepening the understanding of mainstreaming processes through an organising framework that distils the principles of mainstreaming and the key considerations for designing mainstreaming. The new framework presented in this paper is useful for understanding the interdependencies of different social-institutional dimensions and dynamics of mainstreaming by defining overarching principles that can be considered as key factors for enabling and accelerating mainstreaming. This is further conceptualised in relation to how mainstreaming pathways can be designed, in other words, how mainstreaming can be mobilised in practice. The conceptual work of this paper is illustrated with examples of how mainstreaming can manifest from a case study of urban forestry governance across metropolitan Melbourne, Australia.