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CLEARING HOUSE - Collaborative Learning in Research, Information-sharing and Governance on How Urban tree-based solutions support Sino-European urban futures

Periodic Reporting for period 1 - CLEARING HOUSE (CLEARING HOUSE - Collaborative Learning in Research, Information-sharing and Governance on How Urban tree-based solutions support Sino-European urban futures)

Reporting period: 2019-09-01 to 2021-02-28

CLEARING HOUSE is focussing on “Urban Forests as nature-based solutions” (UF-NBS) which are a subset of nature-based solutions (NBS) that build on tree-based urban ecosystems. They address societal challenges, simultaneously providing ecosystem services for human well-being and biodiversity benefits. UF-NBS include peri-urban and urban forests, forested parks, small woods in urban areas, and trees in public and private spaces. UF-NBS are an integral and traditional part of urban landscapes, supporting attractive environments for living, working and business investments.

Trees and forests are a proven nature-based solution that contribute to sustainable urban development. Their potential for delivering ecosystem services, enhancing biodiversity, mitigating negative impacts of climate change and urban growth and contributing to the wellbeing of urban societies is often underestimated and underused. CLEARING HOUSE aims to unite Chinese and European cities in their quest to finding pathways for an effective tree-based restoration of degraded urban environments in order to improve human well-being. Cities and researchers in China and EU are experimenting with UF-NBS at different urban scales, implementing different UF-NBS types and working in diverging economic, governance and institutional contexts. This creates an interesting living laboratory for comparative research on how to plan, establish, govern, manage and monitor tree-rich landscapes for the benefit of urban societies at large.

Therefore, the main objective of CLEARING HOUSE is to analyse and develop – across China and Europe – the potential of NBS in general, and UF-NBS in particular, for enhancing the resilience of cities facing major ecological, socio-economic, and human wellbeing challenges.
The 1st phase of CLEARING HOUSE (1 Sep 2019 – 28 Feb 2021) included two main items:
1. a review of the existing academic and practical knowledge;
2. an exploratory analysis of the CLEARING HOUSE case studies.

An academic literature review identified 422 articles (in English) eligible for analysis, resulting in a dashboard of academic knowledge ( and an analytical review report. A parallel analysis of 22 case histories (16 in Europe and 6 in China) demonstrated the importance of urban forests in practice. Both the academic review and the review of the cases illustrate the communalities and divergences between Europe and China, and suggest prospective research questions for further analysis in the second phase of the project (comparative analysis in 10 case studies in Europe and China, March 2021 – August 2023). Next to the review, a new typology for UF-NBS has been developed based on web ontology language (OWL). This innovative approach allows for interactive browsing and querying of knowledge, and for providing means of building UF-NBS inventories, databases and models.

The 22 case histories are the empirical ground for analysing governance, institutional and economic frameworks for UF-NBS in Europe and China. In both China and Europe, the engagement of the civil society in the selected case studies is relatively low, with the main actor being local authorities. There seems to be room for more active civic engagement, both in planning and implementation of UF-NBS, as in providing funding. There is a need to explore alternative economic arrangements, which can be also a starting point for new governmental and institutional arrangements.

Five local co-design workshops in selected European cases (Barcelona, Brussels, Gelsenkirchen, Halle-Leipzig, Krakow) and one Chinese co-design workshop, to be synthesized in a Sino-European co-design workshop (planned first half of June 2021), have contributed to including local knowledge and local research needs into the reviews mentioned above, and into the exploratory analysis. The exploratory analysis provided a GIS-analysis on UF-NBS in the case studies, and qualitative profiles for the 5 European case study cities.

Communication and dissemination work supported the project by building a community of interested stakeholders, prospective users, and potential multipliers for the outcomes of the project. Successful social media accounts (see have been initiated. The project hosts a successful blog on UF-NBS ( including a blog series on the impact of COVID-19 on the use of urban forests. Eight academic articles have been published (see with 37 citations in total by the 28 Feb 2021. Finally, an inspirational education package on urban forests as nature-based solutions has been created ( which will be implemented in schools in Belgium, Spain and Germany in the next school year (2021-2022).

The project initiated some unplanned research activities, to look into the impact of COVID-19 on the use and perceptions of UF-NBS. This includes surveys and interviews in the Kottenforst in Bonn (April-June 2020), resulting in a much-cited (17 citations) scientific article on the importance of forests as “critical infrastructure” during the COVID-19 pandemic, a self-selective survey in Europe (mainly Belgium, May-June 2020) (paper currently under revision), and including a COVID-19 section in the ongoing Europe- and China-wide societal representative survey on the perceptions and use of urban forests.
The innovative typology of UF-NBS has the potential to become a new standard, as it integrates diverging actual typologies with different viewpoints into a holistic approach that combines form, physical perspectives, function and institutional perspectives. The academic review, the review of case studies, and the governance, economic and institutional analyses gave interesting insights in commonalities and differences within and between Europe and China, in terms of urban forest types, ecosystem services focused at and solutions implemented. These comparative cross-continent analyses are novel, and generate interesting new insights on UF-NBS delivery under diverging systems and institutions in both continents. The outcomes will be published in high-ranked journals and will provide the ground for the comparative analysis in the second phase of the project.

Very interesting insights are expected to emerge from a Europe- and China-wide societal representative survey on use and perceptions towards urban forests in Europe and China. Multiple local, regional and national studies have been done in this field, but comparing between and within China and Europe will provide a novel and representative perspective. This comparative approach will be further applied in the upcoming in-depth analysis of the 10 CLEARING HOUSE case studies, and the Sino-European learning mechanisms.

Upcoming tools include a citizen science tool, a benchmarking tool, and a decision-support tool for assessing diverging UF-NBS scenarios. These tools will facilitate locally embedded research and planning that support urban forest implementation in cities and urban regions. These tools will be combined with a targeted communication and dissemination approach, including guidelines for implementation and an education package, to increase impact and uptake by cities and its citizens. This will support the implementation of the urban greening targets in the European Green Deal.