The “Walking Forest” is an innovative urban green project aiming to literally bring nature back into the heart of the city. One of the best-known examples of this concept was realized in 2022 in Leeuwarden, the Netherlands, as part of the BOSK project. During BOSK, more than 1,000 trees were placed in special movable containers, and over 100 days, these trees slowly and systematically “migrated” through the city center of Leeuwarden. Along their route, parks, main squares, and streets were transformed into temporary green oases, offering city residents a unique experience. The movement of the trees did not happen all at once, but gradually, in stages, so the “forest” appeared in different parts of the city at different times.
BOSK was designed to draw attention to:
The project placed great emphasis on community involvement: the trees were moved with the help of local residents and volunteers, and many community events were linked to the moving forest (e.g., music festivals, cultural programs, educational activities).
The CleanAIR project is inspired by the BOSK Walking Forest, but takes it a step further:
Thus, within the CleanAIR project, the Walking Forest is not just a message, but a tool for measurable change and evidence-based urban development.
During the project, scientifically selected plants (trees and shrubs) are tested.
With air quality sensors placed near the plants, we continuously monitor:
This allows us to directly measure how much different plant species can improve air quality in various urban environments.
The large amount of environmental data from the sensor network is not only stored, but also processed using artificial intelligence and machine learning algorithms.
Our objectives:
The models continuously learn from new data, providing increasingly accurate, city-specific forecasts.
The data collected during the project:
Provide the foundation for scientific publications on the effects of urban green spaces on air quality, microclimate, and community life,
Serve as a starting point for further research on climate adaptation, urban biodiversity, or sustainable urban development.
CleanAIR brings measurable change not only at the local level but also contributes to international scientific knowledge.
In the Walking Forest phase of the CleanAIR project, the movement of plants uniquely combines technology, human power, and community cooperation.
The 400 trees placed in mobile containers throughout the city are moved as follows:
We have 10 custom-made manual transport carts designed specifically for the size and weight of the containers.
With these tools, volunteers, residents, and students can directly participate in moving the Walking Forest, strengthening community spirit and environmental awareness.
The concept is inspired by the Dutch BOSK project, where the mobile forest was also moved by people—every relocation became a festive, community event.
Where manual movement is not feasible due to terrain or distance (e.g., busy roads, longer transports):
We deploy 2 electric forklifts for loading the mobile containers,
The trees are then placed on electric trucks,
This ensures the trees are transported with zero local emissions, in line with the project’s environmental goals.
Moving the trees is not just a logistical task:
Thus, the moving trees have not only a physical, but also a symbolic significance: they represent the cooperation between nature and people for a more sustainable future.
The content of this website does not necessarily represent the official position of the European Union.
This project is supported by the Interreg Danube Region Programme co-funded by the European Union.
