A protected Japanese honey locust tree in the Belgian city of Leuven has been valued at up to €2.5 million, according to new research by environmental economists at KU Leuven. The finding highlights the significant societal value residents attach to their urban green spaces and could influence future planning decisions.
The tree, known locally as the “Tree of Great Sorrow,” stands beside the Atrechtcollege building on Leuven’s historic Naamsestraat. Listed as a protected monument since 1974, it has long been admired by locals for both its age and its cultural symbolism.
Now, following a detailed study led by environmental economist Sandra Rousseau, its worth has been quantified in striking financial terms.
Rousseau and her team, including doctoral student Axelle Francx and master’s student Karen Peeters, surveyed 600 participants using a hypothetical scenario in which the tree was under threat.
Participants were then asked whether they would donate a one-time amount toward its protection, revealing both emotional and monetary support for preserving the tree.
“Two in three respondents considered urban trees ‘very important,’ and half were willing to donate,” Rousseau explained.
The average contribution was €17.50, rising to €21 among those already familiar with the Japanese honey locust. Even participants who had never seen the tree were willing to donate nearly €14.
Using these figures, the researchers calculated the tree’s broader societal value. A conservative estimate based solely on Leuven’s residents placed its worth at €1.3 million.
When expanding the scope to include neighbouring municipalities, the valuation increased to nearly €2.5 million. Francx noted that the tree’s specific history played a major role.
“This valuation reflects the unique identity and local context of this particular tree,” she said. The researchers stressed that not all protected trees in Flanders would reach similar figures, but the study demonstrates how public appreciation can be measured more accurately.
The research follows heated controversy in Antwerp last summer, when city plans to remove 62 trees for a tram project sparked widespread public outrage. The backlash resulted in a temporary halt to the works and highlighted a broader debate over the role of nature in urban environments.
Bart Muys, professor of forest management at KU Leuven, previously remarked that authorities often underestimate the true value of trees when drafting development plans. The new study aims to change that.
The researchers hope their findings will guide policymakers, urban planners, and developers in better assessing how communities value their public green spaces. Current tools used by governments typically focus on tangible financial metrics, often overlooking emotional, cultural, and environmental aspects.
Rousseau argues that integrating such subjective valuations could lead to more balanced decisions. “Our calculation offers a way to better understand public support for projects that affect nature,” she said, adding that trees often lose out when decisions lean solely on economic arguments.
As cities across Europe continue to expand, the study serves as a reminder that urban nature carries meaning far beyond its physical presence—and that communities are willing to fight, and even pay, to preserve it.
