Assessing scaling strategies for nature-based solutions: An indicator-based analysis of policy documents in the Canary Islands

As nature-based solutions (NBS) gain momentum in global and EU agendas for climate, biodiversity, and societal challenges, a key question is how to scale them beyond isolated interventions. This study examines three complementary scaling strategies: scaling-out (spatial expansion), scaling-up (institutional adoption), and scaling-deep (cultural integration), within the Canary Islands' multi-level governance system. We conducted a qualitative content analysis of 23 policy documents, identifying 445 NBS proposals across four intervention types and 14 ecosystem-based sub-types. These proposals were assessed using 11 quantitative indicators that measure spatial distribution, governance and sectoral integration, and decision-makers' values. Findings show uneven progress across strategies. Scaling out is the most advanced. Scaling up is constrained by limited actor diversity and weak collaborations, although municipal actors show bottom-up potential. Scaling deep is least developed, with multifunctional design rare and isolated. Collaborative proposals address a few goals, limiting multifunctionality. We conclude with practical and research directions to strengthen interconnections among scaling strategies.