Nature-based solutions knowledge gaps

When NbS are treated in isolation they can render negative trade-offs to biodiversity or the society. Carbon sequestration in forests and wood products is a good example because it’s straightforward implementation can easily lead to increased harvest, which can have negative impacts on biodiversity. On the other hand, focusing solely on biodiversity can negatively affect the economic situation of forest owners and the entire wood market. Neither prioritization takes into account maximizing cultural ecosystem services necessary for many stakeholders such as tourists, recreational users, and local residents. The ‘Do-No-Significant-Harm’ (DNSH) principle is recognized in policy instruments, but the implementation is far from easy and requires an integrated and comprehensive approach. An integrated view would try to optimize the various aspects in a more holistic approach. As an example, so far it is largely unknown what effects conservation measures have on the forest carbon sink, the sink in wood products, and the substitution of products with higher emissions. To fully consider the complexity of potential feedbacks, it is crucial to invest in inter- and transdisciplinary research in order to render the desired effects of NbS.

Which NbS are suited to dense urban areas with a built environment of high cultural heritage value?

While substantial research has investigated the potential for synergies and trade‐offs in ecosystem service flows related to green space management, the potential for positive and negative impacts are rarely considered across challenge sets.

With respect to small-scale NbS, apart from the need to continuously gain further evidence on their individual performance characteristics in different settings (i.e., different climate conditions, quantity and quality, cultural and governance contexts, single and multiple hazards, etc.) and associated costs, more efforts are needed to address the full potential of their co- benefits and how these can be quantified and/or monetised.