Who leads matters: A governance-informed typology for implementing and scaling nature-based solutions.

Existing nature-based solutions (NbS) typologies prioritize technical form, ecosystem function or spatial scale and treat governance as secondary, limiting their ability to explain variation in feasibility, coordination, persistence and scaling. We propose a governance-informed typology anchored in implementation leadership-defined as the actor or coalition in which constitutive levers (decision authority, resource control and stewardship responsibility) converge at institutional stabilization. Operationalized through four analytical levers and applied to 35 urban NbS cases, the framework identifies five recurring governance archetypes: state-led, market-led, co-led, community-led and citizen-led. Leadership type is best inferred from the alignment of constitutive levers rather than from initiation. The typology complements existing classifications by demonstrating that seemingly similar interventions diverge substantially in governance structure and enabling conditions, with direct implications for policy instrument fit and plausible scaling pathways. As an analytical lens, it supports comparative learning and anticipates institutional constraints when scaling NbS across heterogeneous urban contexts.