1. NBS Knowledge Databases

Nature-based solutions knowledge gaps

Explore the nature-based knowledge gap analysis below to help identify future avenues for research.

The knowledge gap database compiles an evidence base for nature-based solutions, to support defining research and innovation avenues, bolster policy and practitioners’ knowledge and knowledge-implementation. The database gathers 'gaps' collected through desk study and online consultations from August to October 2021 (see the NetworkNature report on practical, research and innovation needs for more information). 171 knowledge gaps were collected and categorized into 30 broad gap topics. This database will be updated during the course of the NetworkNature.


Displaying 21 - 40 of 169
Gap Description Origin of source Source Resource Broad topic

Communication of existing evidence

 Desk Study Institutional publication

UNEP-IEMP, 2019. Research on Ecosystem-based Adaptation (EbA): A reference guide.
  • Communication
  • Awareness and capacity building

Comparison of EbA vs. “grey” infrastructure: Detailed comparisons between EbA and alternative adaptation strategies particularly “grey” infrastructure are essential to contribute to informed decision-making.

 Desk Study Institutional publication

UNEP-IEMP, 2019. Research on Ecosystem-based Adaptation (EbA): A reference guide.
  • Effectiveness compared to conventional approaches

Complexity of socio-ecological systems: Ecosystems are dynamic and do not provide a static baseline against which to measure change and thus the success of EbA measures. Often uncertainty is as well a factor to add to the complexity in monitoring socio-ecological systems.

 Desk Study Institutional publication

UNEP-IEMP, 2019. Research on Ecosystem-based Adaptation (EbA): A reference guide.
  • Effectiveness across socio-ecological contexts

Consideration of social cohesion and well-being impacts of naturebased solutions as indirect or secondary to environmental impacts. In order to understand the effect of nature-based solutions on social and health outcomes for different groups there is a need to understand how different groups use or interact with a particular nature-based solution.

 Desk Study Academic literature

Dumitru, A., Frantzeskaki, N., Collier, M., 2020. Identifying principles for the design of robust impact evaluation frameworks for nature-based solutions in cities. Environmental Science & Policy 112, 107–116. https://doi.org/10.1016/j.envsci.2020.05.024
  • Impacts for health and well-being
  • Social cohesion and environmental justice

Cost and public acceptability is perceived to be a significant barrier to management implementation, and despite some indications that this may be changing, co-creating knowledge through community participation in management interventions is likely to garner support for their wider implementation. There is a need to improve understanding of monetary and non-monetary valuations and increase stakeholder involvement in urban NbS monitoring.

 Online public consulation University / Higher Education / Public research institute sector

Russo, A., Cirella, G.T., 2021. Urban Ecosystem Services: Current Knowledge, Gaps, and Future Research. Land 10, 811. https://doi.org/10.3390/land10080811
  • Stakeholder engagement

Cost-benefit analysis of urban green spaces - long term benefits to human health vs the opportunity cost of not building on land

 Desk Study Academic literature

Grace, M., Balzan, M., Collier, M., Geneletti, D., Tomaskinova, J., Abela, R., Borg, D., Buhagiar, G., Camilleri, L., Cardona, M., Cassar, N., Cassar, R., Cattafi, I., Cauchi, D., Galea, C., La Rosa, D., Malekkidou, E., Masini, M., Portelli, P., Pungetti, G., Spagnol, M., Zahra, J., Zammit, A., Dicks, L.V., 2021. Priority knowledge needs for implementing nature-based solutions in the Mediterranean islands. Environmental Science & Policy 116, 56–68. https://doi.org/10.1016/j.envsci.2020.10.003
  • Impacts for health and well-being
  • Synergies and trade-offs between goals

Cost-effectiveness aspects, including economic valuation knowledge gaps, are covered in more detail under (6) below, but in brief, Whiteoak (section 10) stresses that a comprehensive understanding has not yet been developed of the nature and scale of NbS benefits - and that the quantification of these benefits in monetised form would be valuable.

 Desk Study Institutional publication

European Commission. Directorate General for Research and Innovation., 2020. Nature-based solutions: state of the art in EU funded projects. Publications Office, LU.
  • Cost/benefit evaluations

Currently there is a lack of monitoring of implementation and management of tree NbS and thus a lack of evidence that would be needed to assess effectiveness of specific types tree NbS solutions and implementation methods (species composition, soil types, planting methodology, management options, delivery of social vs environmental benefits). Citizen science offers an opportunity to fill these gaps whilst garnering more support for urban NbS by raising awareness. These gaps limit the ability of decision makers and stakeholders to optimise tree NbS and ensure that limited resources (financial and human time) are used effectively. This is of utmost importance given the transformative change required to address the climate and biodiversity crises.

 Online public consulation University / Higher Education / Public research institute sector

Russo, A., Cirella, G.T., 2021. Urban Ecosystem Services: Current Knowledge, Gaps, and Future Research. Land 10, 811. https://doi.org/10.3390/land10080811
  • Awareness and capacity building
  • Cost/benefit evaluations

Decision makers and practitioners often lack the knowhow to successfully address possible trade-offs and make optimal use of the available technical solutions

 Desk Study Grey literature

Somarakis, G., Stagakis, S., Chrysoulakis, N., n.d. ThinkNature / Nature-Based Solutions Handbook. https://doi.org/10.26225/JERV-W205
  • Awareness and capacity building

demonstrate the economic viability of NbS in comparison to other types of solutions on a timescale compatible with that of global change.

 Desk Study Academic literature

Cohen-Shacham, E., Andrade, A., Dalton, J., Dudley, N., Jones, M., Kumar, C., Maginnis, S., Maynard, S., Nelson, C.R., Renaud, F.G., Welling, R., Walters, G., 2019. Core principles for successfully implementing and upscaling Nature-based Solutions. Environmental Science & Policy 98, 20–29. https://doi.org/10.1016/j.envsci.2019.04.016
  • Effectiveness of hybrid solutions
  • Effectivennes at different time scales

Develop indicators that crosscut challenges and are applicable within and across geographic scales, assess the validity and reliability of indicators across space and time and evelop specific ecological indicators and methods to relate ecosystem status to ecosystem service supply

 Desk Study Grey literature

Raymond, C.M., Centre for Ecology and Hydrology (Great Britain), 2017. An impact evaluation framework to support planning and evaluation of nature-based solutions projects: prepared by the EKLIPSE Expert Working Group on nature-based solutions to promote climate resilience in urban areas.
  • Methodologies and tools for systematic evaluation

Develop stakeholder engagement and governance processes to actively engage academics, practitioners, policy makers, NGOs and local residents in the design and assessment of NbS.

 Desk Study Grey literature

Raymond, C.M., Centre for Ecology and Hydrology (Great Britain), 2017. An impact evaluation framework to support planning and evaluation of nature-based solutions projects: prepared by the EKLIPSE Expert Working Group on nature-based solutions to promote climate resilience in urban areas.
  • Approaches and governance systems for implementation
  • Stakeholder engagement

Development of frameworks for selection of NBSs, for cost analysis and for optimal configuration.

 Desk Study Academic literature

Ruangpan, L., Vojinovic, Z., Di Sabatino, S., Leo, L.S., Capobianco, V., Oen, A.M.P., McClain, M.E., Lopez-Gunn, E., 2020. Nature-based solutions for hydro-meteorological risk reduction: a state-of-the-art review of the research area. Natural Hazards and Earth System Sciences 20, 243–270. https://doi.org/10.5194/nhess-20-243-2022
  • Methodologies and tools for systematic evaluation

Development of tools ( Application of new technologies and concepts and web-based decision support tools and systems)

 Desk Study Academic literature

Ruangpan, L., Vojinovic, Z., Di Sabatino, S., Leo, L.S., Capobianco, V., Oen, A.M.P., McClain, M.E., Lopez-Gunn, E., 2020. Nature-based solutions for hydro-meteorological risk reduction: a state-of-the-art review of the research area. Natural Hazards and Earth System Sciences 20, 243–270. https://doi.org/10.5194/nhess-20-243-2025
  • Monitoring tools

Drivers of global environmental change: The influence of other drivers of global environmental change, such as deforestation and invasive species, influence the ability of ecosystems to sustainably deliver adaptation services. Understanding of these linkages is important in vulnerability and risk assessments

 Desk Study Institutional publication

UNEP-IEMP, 2019. Research on Ecosystem-based Adaptation (EbA): A reference guide.
  • Risks from slow-onset events

Economic analyses of NbS require an understanding of ecological production functions and uncertainties and include benefits that typically accrue over longer time horizons than with conventional solutions.

 Desk Study Academic literature

Nelson, D.R., Bledsoe, B.P., Ferreira, S., Nibbelink, N.P., 2020. Challenges to realizing the potential of nature-based solutions. Current Opinion in Environmental Sustainability 45, 49–55. https://doi.org/10.1016/j.cosust.2020.09.004
  • Relationship between biodiversity, ecosystem functions and ecosystem services

Economic benefits generated by NbS (key aspects in a CBA assessment to determine the feasibility of such projects)

 Desk Study Academic literature

Grace, M., Balzan, M., Collier, M., Geneletti, D., Tomaskinova, J., Abela, R., Borg, D., Buhagiar, G., Camilleri, L., Cardona, M., Cassar, N., Cassar, R., Cattafi, I., Cauchi, D., Galea, C., La Rosa, D., Malekkidou, E., Masini, M., Portelli, P., Pungetti, G., Spagnol, M., Zahra, J., Zammit, A., Dicks, L.V., 2021. Priority knowledge needs for implementing nature-based solutions in the Mediterranean islands. Environmental Science & Policy 116, 56–68. https://doi.org/10.1016/j.envsci.2020.10.007
  • Cost/benefit evaluations

Ecosystem thresholds, boundaries and tipping points: Understanding the potential thresholds, boundaries and tipping points across a range of EbA approaches is critical, yet little is known

 Desk Study Institutional publication

UNEP-IEMP, 2019. Research on Ecosystem-based Adaptation (EbA): A reference guide.

Engaging the different stakeholders in the co-design and assessment of NbS is needed to enhance the social acceptability of these solutions and to tackle potential stakeholder conflicts in a better way.

 Desk Study Institutional publication

European Environment Agency., 2021. Nature-based solutions in Europe policy, knowledge and practice for climate change adaptation and disaster risk reduction. Publications Office, LU.
  • Stakeholder engagement

Evaluation of how scaling Nature-based Solutions can support for biodiversity conservation and restoration.

 Desk Study Institutional publication

Eggermont, H., Le Roux, X., Tannerfeldt, M., Enfedaque, J., Zaunberger, K., Biodiversa+ partners, 2021. Strategic Research & Innnovation Agenda : Horizon Europe Partnership on Biodiversity.
  • Biodiversity benefits