Shifting Baselines in Practice: Strengthening Ecological Foundations for Transformative NbS through Multi-Source Evidence

Delivering transformative Nature-based Solutions requires decisions grounded in robust ecological understanding, yet many implementation processes rely on a short-term or incomplete understanding of past system states. Such gaps limit the legitimacy of restoration proposals by narrowing what communities consider feasible or desirable. Using the Gausa Delta in Norway as a case, stakeholder interviews reveal substantial differences in how landscape change is perceived over time. These contrasting perspectives directly influence support for or resistance to proposed restoration measures, reflecting differing priorities related to flood protection, land use, and ecological recovery. Reintroducing historical and ecological system knowledge into these discussions helps counter narrow assumptions about what constitutes a “normal” or acceptable river state, broadening the shared understanding of viable options and enabling more ambitious, ecologically grounded NbS decisions. This challenge is reinforced by evaluations that often prioritise short-term co-benefits over ecological integrity, further constraining restoration ambition.

In the Gausa context, a more complete ecological understanding has direct implications for restoration design, including consideration of reconnecting side channels, enhancing habitat diversity, and accepting periodic natural flooding as part of a functioning river system. These dynamics highlight governance challenges rooted in fragmented institutional roles, competing expectations for land use and risk management, and limited incorporation of ecological evidence in planning, all of which weaken the legitimacy of restoration proposals. When ecological understanding is unevenly distributed among actors, decision processes tend to favour the status quo or risk-averse engineering measures over options that would restore natural processes or reintroduce hydromorphological variation.

Co-production and multi-actor learning provide a pathway to address this gap. Structured engagement processes that bring together ecological analyses, historical system knowledge, and stakeholder perspectives help create more inclusive and transparent decision environments. Such approaches strengthen the shared understanding of system dynamics, clarify trade-offs, and improve the credibility and acceptability of NbS options. Together, these insights show how linking ecological evidence with stakeholder perspectives and governance realities can support more ambitious, legitimate, and ecologically grounded Nature-based Solutions.