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 41 - 60 of 169
Gap Description Origin of source Source Resource Broad topic

Even if it is recognized that reducing UHI can decrease energy costs and above all the carbon footprint at urban level, there are very few studies (with those being mainly from outside Europe) which try to estimate how much this contributes to the carbon savings either at local, city or regional level.

 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.
  • Relationship between biodiversity, ecosystem functions and ecosystem services

Evidence of positive benefits of NbS exists but only at scientific level. It must be disseminated among different stakeholders. Moreover, existing knowledge must be enlarged, considering diverse ecosystem services and translating these positive impacts into monetary units

 Online public consulation Private Research Institute sector
  • Stakeholder engagement
  • Awareness and capacity building

Finally, despite the prevalence of informal settlements in the region, a better understanding of the type of BGI recommended in different types of settlements is crucial.

 Desk Study Academic literature

Hamel, P., Tan, L., 2021. Blue–Green Infrastructure for Flood and Water Quality Management in Southeast Asia: Evidence and Knowledge Gaps. Environmental Management. https://doi.org/10.1007/s00267-021-01467-w
  • Effectiveness across socio-ecological contexts

Financial sustainability for NbS: I consider there is a need to test what is written in the literature about business development for NbS in real life cases. Platforms like connecting nature have done significant progress with this regard, but there is a need to implement more and in different socioeconomic contexts

 Online public consulation Private company (SME) sector
  • Effectiveness across socio-ecological contexts

First, there is an urgent need for more empirical data on large-scale effects of BGI to complement and support modelling studies on both flood hazard and water quality issues.

 Desk Study Academic literature

Hamel, P., Tan, L., 2021. Blue–Green Infrastructure for Flood and Water Quality Management in Southeast Asia: Evidence and Knowledge Gaps. Environmental Management. https://doi.org/10.1007/s00267-021-01467-w
  • Knowledge base

Fourth, there is insufficient information for practical design and implementation of BGI. For example, scenarios combining BGI and grey infrastructure or different levels of implementation of BGI would help understand investments needs

 Desk Study Academic literature

Hamel, P., Tan, L., 2021. Blue–Green Infrastructure for Flood and Water Quality Management in Southeast Asia: Evidence and Knowledge Gaps. Environmental Management. https://doi.org/10.1007/s00267-021-01467-w
  • Effectiveness of hybrid solutions

From the technological point of view, limited implementation of NbS for flood risk reduction is mainly due to the lack of sufficient technical references, design standards and guidelines

 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.
  • Technical references, design standards and guidelines

Fundamental knowledge of ecosystem functioning: Knowledge gaps in our research area (ecosystem functioning) include uncertainties related to the sustainability of agro-ecological, forestry and fishery management strategies inspired by nature due to lack of mechanistic and long-term data on biodiversity feedback, recycling loops and trade-offs between different ecosystem functionalities

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

Clough, Y., Barkmann, J., Juhrbandt, J., Kessler, M., Wanger, T.C., Anshary, A., Buchori, D., Cicuzza, D., Darras, K., Putra, D.D., Erasmi, S., Pitopang, R., Schmidt, C., Schulze, C.H., Seidel, D., Steffan-Dewenter, I., Stenchly, K., Vidal, S., Weist, M., Wielgoss, A.C., Tscharntke, T., 2011. Combining high biodiversity with high yields in tropical agroforests. Proceedings of the National Academy of Sciences 108, 8311–8316. https://doi.org/10.1073/pnas.1016799108 Johnson, J.A., Runge, C.F., Senauer, B., Foley, J., Polasky, S., 2014. Global agriculture and carbon trade-offs. Proceedings of the National Academy of Sciences 111, 12342–12347. https://doi.org/10.1073/pnas.1412835111 Chausson, A., Turner, B., Seddon, D., Chabaneix, N., Girardin, C.A.J., Kapos, V., Key, I., Roe, D., Smith, A., Woroniecki, S., Seddon, N., 2020. Mapping the effectiveness of nature‐based solutions for climate change adaptation. Glob Change Biol 26, 6134–6155. https://doi.org/10.1111/gcb.15310
  • Relationship between biodiversity, ecosystem functions and ecosystem services

Further efforts should also be placed on the developments of tools that combine real-time monitoring and control systems, advanced flood risk assessment methodologies and models, smart early warning systems, numerical weather prediction models and flood risk models to advance real-time operational potential of NbS

 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.
  • Monitoring tools

Further identification of synergies and trade-offs between different impacts is required, to understand which characteristics of nature-based solutions can act as enablers or amplifiers of effects, and which might act as buffers of negative trade-offs, thusincreasing the potential for multi-functionality and innovation.

 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.2020.05.027
  • Synergies and trade-offs between goals

Further research is needed into how business models, finance mechanisms and governance arrangements can be established that enable the implementation of NbS without generating large increases in the value of land and property that in turn produce forms of green gentrification.

 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.
  • Approaches and governance systems for implementation
  • Social cohesion and environmental justice

Furthermore, the evidence-base is currently lacking information on the implementation of EbA-relevant inter- ventions in certain ecosystems. These include the grass- land/savanna, mountain and marine biomes.

 Desk Study Academic literature

Doswald, N., Munroe, R., Roe, D., Giuliani, A., Castelli, I., Stephens, J., Möller, I., Spencer, T., Vira, B., Reid, H., 2014. Effectiveness of ecosystem-based approaches for adaptation: review of the evidence-base. Climate and Development 6, 185–201. https://doi.org/10.1080/17565529.2013.867249
  • Effectiveness across socio-ecological contexts

Furthermore, the question concerning performance of “networks” (or “trains”) of interconnected small-scale NbS, as well as their hybrid combinations with large-scale NbS and grey infrastructure still remains unclear and should be addressed in the future work.

 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.
  • Effectiveness of hybrid solutions
  • NbS interaction at the landscape scale

Furthermore, the uncertainty of future climate change precludes knowing whether any adaptation even be relevant, and this is not something that is covered within the literature analysed.

 Desk Study Academic literature

Doswald, N., Munroe, R., Roe, D., Giuliani, A., Castelli, I., Stephens, J., Möller, I., Spencer, T., Vira, B., Reid, H., 2014. Effectiveness of ecosystem-based approaches for adaptation: review of the evidence-base. Climate and Development 6, 185–201. https://doi.org/10.1080/17565529.2013.867251
  • Risks from slow-onset events

Gaps remain demonstrating the ecosystem service benefits of different tree/woodland interventions (tree NbS) in different situations. Urban tree NbS implementation, but also ongoing management requires a more research, particularly in relation to sustainable soil use. Soil is a non-renewable resources that is the basis of functioning ecosystems yet the different management regimes on urban greenspaces are not well researched and almost all studies focus on benefits to above-ground biodiversity alone. Soils are not currently included in widely used freely available tools (i.e., i-Tree Canopy and the United Kingdom Office for National Statistics) and this limits our understanding both for optimal tree species planting and deliver of wider ecosystem services.

 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
  • Relationship between biodiversity, ecosystem functions and ecosystem services
  • Biodiversity benefits

Given the multiple benefits that NbS can provide to society, there is a need for more strategic approaches to maximising benefits of NbS for multiple development goals including the Sustainable Development Goals.

 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.
  • Synergies and trade-offs between goals

How can the tangible and intangible benefits to human health arising from green open spaces be measured?

 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.2020.10.005
  • Impacts for health and well-being

How can we bridge the NbS knowledge gap of Member State governmental officials at the National, Regional and local level? Commission officials have extensive knowledge of NbS applications because of the demonstration projects and are supported by a significant number of experts that can help them resolve any questions. This knowledge is not trickling down to the member states at all levels of governance. This creates a significant challenge in the implementation of NbS especially at the local level which is for most projects the first level for the conception and approval of NbS projects. In addition, in many MS, the involvement of governmental personnel in European projects is not consistent and therefore the results and finding of the projects are not being integrated in the knowledge base and do not have a lasting effect. The question is how do we bridge this knowledge gap. We think the solution is to establish a certification program of NbS professionals for both governmental officials as well as for all other professionals in order to reinforce the importance of NbS.

 Online public consulation International or European research organisation/initiative sector
  • Awareness and capacity building
  • Planning and policy frameworks

How can we ensure the effectiveness of the chosen key performance indicators and set baselines?

 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.2020.10.009
  • Methodologies and tools for systematic evaluation

How effective is development and implementation of NbS through co-production?

 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.2020.10.015
  • Stakeholder engagement