‘Walking’ forest of 1,000 trees transforms Dutch city​

It is less of a marathon and more of an amble. But then a “walking forest” of 1,000 trees was never going to move at speed. Since May, volunteers have been transporting the native trees planted in wooden containers along a 3.5km stretch through the centre of the northern Dutch city of Leeuwarden, giving people an opportunity to experience an alternative, greener future.

“We are a generation that has almost lost all hope,” says Johan Lakke, a student at the University of Groningen who is helping with the project, which is called Bosk, meaning “forest” in the local Frisian language. “This project gives me hope,” he says. “It shows us that if you’re crazy enough to think outside the box, you can achieve things.”

More tree cover in urban environments means lower land temperatures – a planning feature that is becoming increasingly crucial in a heating world. A study conducted across nearly 300 European cities showed that urban trees can cool the land surface temperature by up to 12C in summer.

The brainchild of landscape architect Bruno Doedens and his longtime collaborator, the late Joop Mulder, Bosk emerged from Doedens’ 2021 essay Planet Paradise, which questioned humans’ relationship with the natural world. “Right now, we as a species are behaving like adolescents who don’t want to clean up their room,” says Doedens. “We need to grow up and stop making a mess of everything. We need to take care of our surroundings.”

Passersby stop to appreciate the trees along Tweebaksmarkt in Leeuwarden city centre

In addition to the grand spectacle of the “walking” forest, the Bosk programme, which is part of Arcadia, a triennial art festival, includes debates, exhibitions and performances around the theme of reconnecting with nature. Sjoerd Bootsma, Arcadia’s artistic director, says: “We need art and artists to help us imagine different possibilities.”

The first stop on the walking route was Stationsplein, outside Leeuwarden’s train station. “The trees created such a calming effect, people immediately felt relaxed,” says Sjoukje Witkop, the general manager of a nearby hotel. Witkop has been inspired to to install 10 large plant pots outside the hotel. “Why didn’t we have trees there before?” she says.

‘Calming effect’: the walking forest provides a space to unwind in Leeuwarden. The map indicates the route the trees will take

When the “walking” forest is stationary, seating areas are provided between the trees. Some hotels are offering picnic baskets to guests so they can unwind in the shade.

The 1,000 trees are made up of 60-70 native species, including alder, ash, elm, maple, oak and willow, planted in 800 wooden containers. Each has a QR code providing details such as species, average lifespan and preferred soil type. A soil sensor alerts the city’s gardening team when the trees need water. “These are some of the best cared for trees in the world,” says Doedens.

The project has received overwhelming local support, and people of all ages, genders and backgrounds have volunteered to move the trees. A local brewery has even developed a special beer – BoskBier – with 10 cents from every sale donated to Plan Boom, a national tree planting programme.

Managers of other city centres in the Netherlands have also come to see what can be done. “Even churches want to be part of Bosk,” says Bootsma.

According to Doedens, people have enjoyed the trees so much they want them to stay. “We created a ‘walking’ forest and people want us to leave it in place,” he says with a laugh.

But not everyone is thrilled. Some feel the project is a waste of time and money. Others dislike the fact that they have to park elsewhere for a week, or vehicular access to certain places is blocked because of the trees. Almar Dam, who is leading the project for the municipality of Leeuwarden, urges them to look at the bigger picture. “Normally, the streets are so noisy and you have to watch out because drivers are going to kill you with their cars,” he says. “But look at a Bosk location. It’s so peaceful.”

Leeuwarden train station gets a green makeover

From 14 August – 100 days after they arrived – the trees will be planted around the city, including in low-income neighbourhoods, where greenery is scarce. Friesland aims to be the most circular region in the EU by 2025, reducing waste, pollution and biodiversity loss. While this will not be easy, Doedens is hopeful. “If trees can walk, we can change,” he says.

Find more age of extinction coverage here, and follow biodiversity reporters Phoebe Weston and Patrick Greenfield on Twitter for all the latest news and features